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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Cellular renewal in the continuously erupting incisor of the rat.

Smith, Charles E. January 1975 (has links)
No description available.
12

An analysis of morphological variation within and between stream populations of Gasterosteus aculeatus Linnaeus

Shaw, Kate January 1985 (has links)
Two small streams on Vancouver Island, British Columbia, were examined for patterns of morphological variation in Gasterosteus aculeatus. A progressive analysis beginning with Principle Components Analysis, followed by Nested and Partially Nested Multiple Analysis of Variance and then Duncan's Multiple Range Test was used for pattern determination. This new technique allows the researcher to sequentially isolate the pattern of variation at different levels of generality from species to individual organisms. The pattern of variation for G. aculeatus in Bonsall Creek and Nunns Creek can be summarized as follows: The largest amount of variation accounted for by the analysis is interpreted as individual variation. Populations also account for a large amount of variation and show consistent, fully nested patterns of variation at each of the analysed geographic and microgeographic levels. These populations are probably genealogical units. The so-called "leiurus" and "trachurus" forms on the Pacific coast of North America do not appear to be evolutionary entities, but to be historical artifacts that are best viewed as labels for the extremes of a continuum of variation. In areas where distinct populations meet, different clines are documented in the two stream systems. In Nunns Creek there is a smooth cline between populations, whereas in Bonsall Creek there is a step cline. / Science, Faculty of / Zoology, Department of / Graduate
13

Comparison of the Incidence of Bolton Tooth Mass Discrepancy in African-American and Caucasian Populations

Adelsperger, M. Jayme January 1998 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Tooth mass discrepancies have been studied extensively in Caucasian populations, but little has been done to compare differences between Caucasian and African-American populations. The objective of this study was to determine whether the incidence of tooth mass discrepancies between the maxillary and mandibular arches was greater in African-American populations than Caucasian populations. Pretreatment plaster orthodontic models of 100 African-American and 100 Caucasian patients from the Indiana University Orthodontic Clinic and from one private practitioner were measured with a Mitutoyo Digimatic® caliper accurate to 0.01 mm. Mesiodistal widths of all teeth from first molar to first molar were measured with the mesio-buccal and disto-buccal contact areas normally being the widest area. The investigator was blinded to the gender and ethnicity of the subject by assigning each model a random number which was matched to the patient profile only following statistical analysis. Anterior ratios and total (posterior+ anterior) ratios were calculated according to the methods described by Bolton and were compared to the Bolton means and standard deviations. Incidence of tooth mass discrepancy was also investigated according to gender and dental malocclusion classification of the individuals. Tooth mass discrepancies present a hurdle to the clinician in achieving an ideal occlusion. Reports of the incidence of significant discrepancies in defined populations alerts the practitioner to problems in finishing their patients' occlusions. Results of the study show nearly double the incidence of overall Bolton tooth mass discrepancy in the African-American sample than in the Caucasian. The overall tooth mass discrepancy was more severe in the African-American sample, while anterior tooth mass discrepancies were nearly identical in both populations.
14

Quantitation of iron in the liver, pancreas and heart of hospital patients in Hong Kong.

January 1993 (has links)
by Yim-kam Kwong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 119-133). / ACKNOWLEDGEMENT --- p.vii / LIST OF TABLES --- p.viii / LIST OF FIGURES --- p.x / ABSTRACT --- p.1 / SECTION / Chapter 1. --- INTRODUCTION --- p.3 / Chapter 2. --- LITERATURE REVIEW --- p.6 / Chapter 3. --- MATERIALS AND METHODS --- p.39 / Chapter 4. --- RESULTS --- p.61 / Chapter 5. --- DISCUSSION --- p.103 / Chapter 6. --- CONCLUSION --- p.116 / REFERENCES --- p.119 / APPENDIX --- p.134 / Chapter SECTION 1 --- INTRODUCTION --- p.3 / Chapter SECTION 2 --- LITERATURE REVIEW --- p.6 / Chapter 2.1 --- IRON --- p.6 / Chapter 2.1.1 --- CHEMISTRY --- p.6 / Chapter 2.1.2 --- METABOLISM --- p.6 / Chapter 2.1.2.1 --- Homeostasis --- p.6 / Chapter 2.1.2.2 --- Absorption --- p.8 / Chapter 2.1.2.3 --- Transportation - Role of transferrin in iron transport --- p.9 / Chapter 2.1.2.4 --- Storage --- p.10 / Ferritin --- p.11 / Haemosiderin --- p.13 / Chapter 2.2 --- IRON OVERLOAD --- p.14 / Chapter 2.2.1 --- AETIOLOGY --- p.14 / Chapter 2.2.2 --- PREVALENCE --- p.15 / Chapter 2.2.3 --- MECHANISM --- p.16 / Chapter 2.2.4 --- PATHOLOGY OF IRON OVERLOAD --- p.17 / Chapter 2.2.4.1 --- Increased absorption of iron from the diet --- p.18 / Chapter 2.2.4.2 --- Parenteral administration of excess iron --- p.21 / Chapter 2.2.4.3 --- Increased iron absorption combined with transfusional overload --- p.22 / Chapter 2.2.4.4 --- Miscellaneous conditions --- p.23 / Chapter 2.2.5 --- CLINICAL PRESENTATION --- p.24 / Chapter 2.2.6 --- EFFECT OF IRON OVERLOAD --- p.25 / Chapter 2.2.6.1 --- Role of iron in lipid peroxidation --- p.25 / Chapter 2.2.6.2 --- Iron and neoplasia --- p.26 / Chapter 2.3 --- ASSESSMENT OF IRON OVERLOAD --- p.26 / Chapter 2.3.1 --- NON-SERUM PARAMETER --- p.26 / Chapter 2.3.1.1 --- Localization of stored iron --- p.27 / Chapter 2.3.1.2 --- Morphometric assessment of hepatic iron in liver biopsy --- p.30 / Chapter 2.3.1.3 --- Hepatic iron concentration --- p.31 / Chapter 2.3.1.4 --- Atomic absorption spectrophotometry --- p.32 / Chapter 2.3.1.5 --- Hepatic imaging studies --- p.33 / Chapter 2.3.2 --- SERUM PARAMETERS --- p.34 / Chapter 2.3.2.1 --- Serum ferritin measurement --- p.34 / Chapter 2.3.2.2 --- Serum iron --- p.36 / Chapter 2.3.2.4 --- Transferrin saturation --- p.37 / Chapter SECTION 3 --- MATERIALS AND METHOD --- p.39 / Chapter 3.1 --- SUBJECTS --- p.39 / Chapter 3.1.1 --- SOURCE OF TISSUE SAMPLES AND CASE SELECTION --- p.39 / Chapter 3.1.1.1 --- The controls --- p.39 / Chapter 3.1.1.2 --- The transfusion group --- p.39 / Chapter 3.1.1.3 --- The non-transfusion group --- p.40 / Chapter 3.1.1.4 --- The total group --- p.40 / Chapter 3.2 --- METHODS --- p.40 / Chapter 3.2.1. --- HISTOLOGICAL METHOD --- p.44 / Chapter 3.2.1.1 --- Haematoxylin and Eosin Stain --- p.47 / Chapter 3.2.1.2 --- Perls' Prussian Blue Method --- p.49 / Chapter 3.2.1.3 --- The Rowe's Method of Iron Deposition --- p.47 / Chapter 3.2.1.4 --- Method 1 --- p.48 / Chapter 3.2.1.5 --- Method2 Estimation and grouping of % area --- p.49 / Chapter 3.2.1.6 --- "Comparison of Rowe's method, and the two histological iron grading methods" --- p.54 / Chapter 3.2.2 --- CHEMICAL MEASUREMENT --- p.55 / Chapter 3.2.2.1 --- Sectioning of paraffin liver blocks for chemical measurement --- p.55 / Chapter 3.2.2.2 --- Paraffin removal --- p.56 / Chapter SECTION 4 --- RESULTS --- p.61 / Chapter 4.1 --- HISTOLOGICAL ASSESSMENT --- p.61 / Chapter 4.1.1 --- HISTOLOGICAL STUDY --- p.61 / Chapter 4.1.2 --- SEX DISTRIBUTION --- p.65 / Chapter 4.1.3 --- AGE DISTRIBUTION --- p.65 / Chapter 4.2 --- CHEMICAL MEASUREMENT --- p.81 / Chapter 4.2.1 --- EVALUATION OF ANALYTICAL PRECISION --- p.84 / Chapter 4.2.2 --- RESULT OF CHEMICAL MEASUREMENTS --- p.81 / Chapter 4.2.3 --- ASSOCIATED CONDITIONS IN PATIENTS WITH LIVER TISSUE IRON > 50 μMOL/G --- p.86 / Chapter 4.3 --- CORRELATION OF HISTOLOGICAL ASSESSMENT WITH CHEMICAL MEASUREMENT --- p.88 / Chapter 4.3.1 --- CORRELATION OF HISTOLOGICAL ASSESSMENT WITH CHEMICAL MEASUREMENT BY METHOD 1 --- p.88 / Chapter 4.3.2 --- CORRELATION OF ASSESSMENT WITH CHEMICAL MEASUREMENT BY METHOD 2 --- p.89 / Chapter 4.3.2.1 --- Percentage area --- p.95 / Chapter 4.3.2.2 --- Score --- p.96 / Chapter 4.4 --- PANCREATIC AND MYOCARDIAC HAEMOSIDEROSIS --- p.100 / Chapter 4.4.1 --- METHOD 2 --- p.100 / Chapter SECTION 5 --- DISCUSSIONS --- p.103 / Chapter SECTION 6 --- CONCLUSIONS --- p.116 / REFERENCES --- p.119 / APPENDIX --- p.134
15

A morphological and biochemical study on the hemisected rat spinal cord implanted with cultured astrocytes.

January 1993 (has links)
Joie Jie Wang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 121-132). / ABSTRACT --- p.i / ACKNOWLEDGEMENTS --- p.iii / LIST OF TABLE --- p.vii / LIST OF FIGURES --- p.viii / LIST OF ABBREVIATIONS --- p.xii / Chapter CHAPTER I. --- INTRODUCTION --- p.1 / Chapter I.1. --- Fibre tracts of the rat spinal cord --- p.1 / Chapter I.2. --- Histopathological responses to spinal cord injuries --- p.2 / Chapter I.3. --- Failure of CNS regeneration --- p.4 / Intrinsic inability of CNS neurons themselves to regenerate --- p.4 / Inappropriate synapse without normal functioning --- p.5 / Progressive necrosis and cystic cavities --- p.5 / Autoimmune explanation for the failure of regeneration --- p.6 / Glial scarring --- p.6 / Absence of Schwann cells in the CNS --- p.7 / Lack of requisite growth factors --- p.8 / Chapter I.4. --- The use of transplants --- p.9 / Transplants of fetal nerve tissues --- p.9 / Transplants of peripheral nerve tissues --- p.10 / Transplants of neuroglial cells --- p.11 / Transplants of central neurons --- p.12 / Chapter I.5. --- Objectives of the present study --- p.13 / Chapter CHAPTER II. --- METERIALS AND METHODS --- p.15 / Chapter II.1. --- Hemisection of rats --- p.15 / Chapter II.2. --- Preparation of purified cortical astrocytes --- p.15 / Chapter II.3. --- Scanning electron microscopy (SEM) --- p.18 / Chapter II.4. --- HistologýؤLight microscopy --- p.19 / Chapter II.5. --- Measurement of volume of scar tissue --- p.19 / Chapter II.6. --- Immunofluorescence staining --- p.20 / Chapter II.7. --- Transmission electron microscopy --- p.23 / Chapter II.8. --- Comparison of expression of various proteins in the spinal cord --- p.24 / Polyacrylainide gel electrophoresis --- p.24 / Western blotting --- p.26 / Chapter CHAPTER III. --- RESULTS --- p.28 / Chapter III.1. --- Survival of cultured astrocytes --- p.28 / Chapter III.2. --- Light microscopy --- p.28 / Hemotoxylin and Eosin staining --- p.28 / Toluidine Blue staining --- p.30 / PHAL labelled astrocytes --- p.31 / Immunofluorescence staining --- p.32 / N-CAM --- p.32 / GFAP --- p.33 / NF --- p.34 / Chapter III.3. --- Transmission electron microscopy (TEM) --- p.35 / Chapter III.4. --- Determination of the volume of scar tissue --- p.37 / Chapter III.5. --- Gel electrophoresis --- p.38 / Chapter III.6. --- Immunoblotting and densitometry --- p.38 / Chapter CHAPTER IV. --- DISCUSSION AND CONCLUSIONS --- p.115 / REFERENCES --- p.121
16

Comparative morphology and functional anatomy of the digestive tract of the copepods Tigriopus californicus and Calanus plumchrus : a light and electron microscope study

McGroarty, James Roy January 1985 (has links)
A study of the digestive tract of the copepods Tigriopus californicus and Calanus plumchrus was carried out using techniques of light and electron microscopy. In Tigriopus californicus, the foregut contains a curved cuticle lined esophagus which extends from the ventral mouth to the junction of the anterior midgut and midgut caecum. The noncuticulized portion of the digestive tract consists of: 1. A single spherical midgut caecum located anteriorly, 2. An anterior midgut, 3. A posterior midgut. There are cuticulized anterior and posterior hindgut regions ending in a dorsal anus. In Calanus plumchrus, the foregut consists of a cuticle lined esophagus extending from the ventral mouth to the junction of the midgut and the midgut diverticulum. The noncuticulized portion of the digestive tract consists of: 1. A single midgut diverticulum, 2. A midgut that is divisible on the basis of epithelial cell type and function. There is a long abruptly narrowing cuticle lined hindgut ending in an anus. In Tigriopus californicus, four cell types could be distinguished and from such ultrastructural characteristics as the position in the digestive tract, abundance, position, and type of organelles, lipid content, presence and type of vesiculation, and electron density, functions for the cells were determined. Cell type '1' is an embryonic 'stem' cell. It functions as a replacement cell and differentiates when cells are worn away or lost in secretion. Cell type '2' is mainly a secretory cell and functions in the synthesis of proteins. It also plays a role in lipid absorption. Cell type '3' is absorptive, mainly for lipids. Cell type M1, found only in the anterior midgut is also an absorptive cell. The presence of electron dense vesicles suggests that lipid absorption is not its major function. From the abundance of cell type and from examination of the ultrastructure in the various regions of the digestive tract, the following conclusions were made: 1. The midgut caecum functions in the absorption of digested nutrients. 2. The anterior midgut plays a role in nutrient absorption but is important in secretion. 3. The posterior midgut cells are mainly absorptive. In Calanus plumchrus, five cell types could be distinguished. Cell type 'E' is an undifferentiated 'stem1 cell. Cell type 'R' found in the midgut diverticulum and posterior midgut regions, is absorptive. Its developed basal surfaces suggest a transport function between the cell and the haemo-coel . Cell type 'D' is found in the glandular region of the midgut and is absorptive. It has an ultrastructure similar to that observed for cell type 'R'. Cell type 'B' is a large vacuolated absorptive cell found in the glandular region of the midgut. Cell type 'F' functions in the synthesis and secretion of digestive enzymes. In Calanus plumchrus, the midgut diverticulum is specialized for the absorption of digested nutrients and transport of metabolites to the haemocoel . The anterior midgut regions are mainly absorptive. It includes a vacuolated glandular region specialized for pinocytotic absorption. In the middle section of the midgut, adjacent and posterior to the glandular region, is an area of epithelial cells specialized for secretion. The posterior midgut regions are mainly absorptive. In Tigriopus californicus biological markers can be used to determine cell type function in correlation with the observed ultrastructure. / Science, Faculty of / Zoology, Department of / Graduate
17

A morphological and cytochemical analysis of bud initiation and development in the filamentous brown alga Sphacelaria Furcigera

Burns, Alan Robert January 1981 (has links)
A study on the process of bud initiation and development in the filamentous brown alga Sphacelaria furcigera (Kutz) was carried out using techniques of light and electron microscopy, as well as cytochemistry. A localized thickening and subsequent protrusion of the outer cell wall of the axial mother cell characterizes the earliest detectable stage of bud initiation. This protrusion forms through the combined deposition of newly synthesized microfibrils together with the partial lysis/loosening of the existing cell wall. Evidence is presented that of the three enzyme activities localized, peroxidase, adenosine triphosphatase and acid phosphatase activity, only peroxidase activity is related to the lysis/loosening of the cell wall during the early development of the bud initial. Continued incorporation of new cell wall material into the outer cell wall maintains its structural integrity. However, there is a change in the layered appearance of the cell wall microfibrils. The cell wall of the bud initial is characterized by two cell wall layers instead of the four found in the pre-existing cell wall of the axial mother cell. This original cell wall is composed of an outer-most fucan layer, overlying an alginate layer, which in turn overlies another fucan layer and finally terminates in an inner-most alginate layer. In contrast the bud initial's cell wall has only a thin outer fucan layer and a thick inner alginate layer. Concomitant with the formation of the cell wall protrusion, there is a loss of cytoplasmic vacuoles, an increase in cytoplasmic mass and density and an increase in the number of organelles. The endomembrane system (endoplasmic reticulum, dictyosomes and the derivative vesicles) also proliferates. Organelle migration into the bud protrusion keeps pace with bud expansion. The movement of the nucleus, however, lags behind and it migrates towards the bud protrusion only after a "vacuole free" cytoplasm becomes established. As the nucleus approaches a medial position between the base of the axial mother cell and the tip of the bud protrusion, cytoplasmic vacuoles re-appear. They are confined, however, to the basal region of the axial mother cell. After karyokinesis, a cross wall is deposited between the two daughter nuclei resulting in the formation of a bud cell and a sister axial cell. The sister axial cell is highly vacuolated and structurally resembles the adjacent quiescent axial cells. The bud cell is dense and non-vacuolated, a feature characteristic of a mefistematic cell. / Science, Faculty of / Botany, Department of / Graduate
18

Neurovascular lesions and mechanisms in suicidal hanging: an anatomical, physiological and pathological study

Moar, Jacob Joseph 25 April 2013 (has links)
Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Health Sciences, 2012 / Background and Purposes Suicide by hanging is a relatively common occurrence. The actual cause of death in suicidal hanging is, however, controversial, having been attributed variously to asphyxia, carotid artery compression and vagal nerve stimulation. The aim of this Ph.D thesis was to determine the possible neurovascular cause of death in suicides by hanging by careful study of the anatomy and physiology of the neck region in relation to the ensuing pathology. The study was, therefore, approached from an anatomical, physiological, histological and pathological pespective. It therefore comprised a detailed exploration of the anatomy and physiology of the neck structures to match these with the underlying traumatised neurovascular structures, the latter trauma being brought about by the suicidal hanging process. Methods The methods used in the study included an investigation of the ligature and position of the ligature in relation to the level of the neck and the physical effects of the ligature on the skin and underlying anatomical structures. A careful and detailed dissection of the neck was undertaken and samples of the vessels and nerves were processed for histological study. Fifty consecutive cases of suicidal hanging and five “non-hanging” cases which served as controls were used in the study. In addition, ten cases of suicidal hanging not included in the study were subjected to occlusion studies by means of probe exploration. This technique and procedure was not carried out or applied to the cases included in the study for fear that the probe itself might produce artefactual damage to the delicate endothelium lining the inner layer of the vessel wall. The study was classified into various components such as: 1. Examination of the type and structure of the ligature material; 2. The position of the ligature on the neck, i.e. whether involving upper, middle, or lower third of neck and to correlate this position with the underlying anatomical structures subjected to the accompanying tensile, compressive and haemodynamic forces; 3. The physical effects of the ligature upon the skin and the underlying deeper neurovascular structures of the neck; 4. Meticulous “bloodless” dissection of the neck structures to corroborate any pathology noted with the above three criteria. Currently, all putative causes of death remain speculative; 5. Particular attention was paid to those structures most vulnerable to the compressive forces, tensile forces and haemodynamic forces operative in hanging. These comprise the neurovascular structures contained within the fibrous carotid sheath and the phrenic nerves in the neck, in particular with regard to the anatomical relationship of these structures to the positioning of the ligature. As far as analysing the forces involved, the engineering principles pertaining to these were interpreted in consultation with the Faculty of Engineering at the University of the Witwatersrand. Results The main findings of the study showed damage to vascular, neural (including phrenic nerve), carotid bodies and accessory glomal bodies. The vascular findings emerged following an examination of the total number of arteries in the study, namely, 300, the figure derived as follows: six arteries in each of the fifty hanging subjects, viz., the left common carotid artery, the right common carotid artery, the left internal carotid artery, the right internal carotid artery, the left external carotid artery and the right external carotid artery (6 x 50 = 300). The damage shown was particularly the case with regard to the finding of tears in the various layers of the vessel wall. These extended from the intima through to the adventitia or outermost layer of the vessel wall and these were further subdivided into being either single or multiple. The tears found ranged from those involving the intima alone (single tears being found in 17 (5.6%) of the 300 arteries examined and multiple tears in 37 (12.3%) of the 300 arteries examined., the intima extending to the internal elastic lamina (single tears being found in 20 (6.6%) of the 300 arteries examined and multiple tears in 8 (2.6%) of the 300 arteries examined), tears involving the intima and extending through to involve the media, i.e. intimomedial tears and whether these latter tears involved the inner-, middle-, or outer-thirds of the media (single or multiple). Single intimo-medial tears extending through the intima to involve the inner-third of the media comprised 6 (2.0%) of the arteries examined, those extending from the intima to involve the middle-third of the media comprised 3 (1.0%) of the 300 arteries examined and single intimo-medial tears extending through the intima to involve the outeriv third of the media similarly comprised 3 (1%) of the arteries examined. Multiple intimo-medial tears extending through from intima to inner-, middle-, and outerthirds of the media respectively, comprised 3 (1.0%), 5 (1.6%) and 1 (0.3%) of the arteries examined. Single tears involving the inner-third of the media alone comrised 6 (2.0%) of the 300 arteries examined, single tears involving the middle-third of the media comprised 9 (3.0%) of the arteries examined and single tears involving the outer-third of the media alone comprised 8 (2.6%) of the arteries examined. Multiple tears involving the inner-, middle and outer-thirds of the media respectively comprised 6 (2.0%), 13 (4.3%) and 16 (5.3%) of the arteries examined. Single tears involving both adventitia and media, i.e. adventitio-medial tears extending through the inner-, middle-, or outer-thirds of the media to involve the adventitia comprised 1 (0.3%), 2 (0.6%) and 6 (2.0%) respectively of the 300 arteries examined. Multiple adventitio-medial tears of the inner-, middle-, and outer-thirds of the media, respectively, comprised 0 (0.0%), 3 (1.0%) and 2 (0.6%) of the 300 arteries examined. Single tears of the adventitia alone comprised 21 (7.0%) of the arteries examined while multiple tears comprised 7 (2.3%). Complete circumferential transverse rupture of the vessel wall was found in 3 (1.0%) of the arteries examined while adventitial haemorrhage was found in 103 (34.3%) of the 300 arteries examined. The vascular findings were represented numerically in tabular form in the 50 hanging subjects in Table III and were further analysed and compared with regard to either unilateral or bilateral vessel involvement in the fifty (50) suicidal hanging subjects and the findings represented in Tables IIIa (unilateral involvement) and IIIb (bilateral involvement). Additional vascular findings comprised endothelial elevation/avulsion, internal elastic lamina dehiscence, subendothelial clefts, multiple medial fenestrations, adventitio-medial separation, vascular congestion and a vascular plane of cleavage. These were similarly represented in Table IV and analysed with regard to unilateral or bilateral involvement in Tables IVa and IVb. Endothelial elevation/avulsion was found in 295 (98.3%) of the 300 arteries examined, internal elastic lamina dehiscence in 290 (96.6%) of the arteries examined, subendothelial clefts in 289 (96.3%) of the arteries examined, multiple medial fenestrations in 17 (5.6%) of the arteries examined, adventitiomedial separation in 273 (91.0%) of the arteries examined, vascular congestion in 224 (74.6%) of the arteries examined and a vascular plane of cleavage in 98 (32.6%) of the arteries examined. These findings, unexpected, showed the extreme fragility and vulnerability of the intima and adventitia to the compressive and tensile forces acting on the vessel wall during hanging, being explicable not only on the basis of the various complex forces interacting simultaneously during hanging but on the magnitude of forces applied. A mathematical analysis, found at the end of the Discussion chapter, conducted in order to estimate the minimum peak pressure applied and exerted on the vessel wall during hanging, in collaboration with the School of Mechanical, Industrial and Aeronautical Engineering at the University of the Witwatersrand, confirmed the magnitude of these forces. The neural findings (Table V) were divided into neural congestion, neural haemorrhage, neural internal dehiscence, neural tearing and perineural separation and these were similarly analysed with regard to either unilateral or bilateral involvement in the fifty hanging subjects (Tables Va and Vb). Neural congestion was found in association with 20 (6.6%) of the 300 arteries examined, neural haemorrhage in14 (4.6%), neural internal dehiscence in 54 (18.0%), neural tearing in 35 (11.6%) and perineural separation in 112 (37.3%). Neural ganglionic findings were similarly divided into ganglionic congestion, ganglionic haemorrhage, ganglionic internal dehiscence and ganglionic tearing. Ganglionic congestion, in association with the 300 arteries examined, was found in 20 (6.6%), ganglionic haemorrhage in 8 (2.6%), ganglionic internal dehiscence in 15 (5.0%) and ganglionic tearing in 6 (2.0%). The findings in the carotid bodies were divided into carotid body congestion, carotid body haemorrhage, carotid body internal dehiscence and carotid body tearing. Carotid body congestion, in association with the 300 arteries examined, was found in 8 (2.6%), carotid body haemorrhage in 2 (0.6%), carotid body internal dehiscence in 4 (1.3%) and carotid body tearing in 2 (0.6%). Accessory glomal body findings were, once again, divided into accessory glomal congestion, accessory glomal haemorrhage, accessory glomal internal dehiscence and accessory glomal tearing. However, in view of the close anatomical association between the accessory glomal bodies and the adventitia of the arterial walls, an additional pathological finding of accessory glomal adventitial separation emerged. Accessory glomal congestion, in association with the 300 arteries examined, was found in 20 (6.6%), accessory glomal haemorrhage in 7 (2.3%), accessory glomal internal dehiscence in 50 (16.6%), accessory glomal tearing in 18 (6.0%) and accessory glomal adventitial separation in 124 (41.3%). This latter finding once again demonstrated the vulnerability of the adventitial layer of the vessel wall to tensile forces, separating it from its associated structures. Damage to the phrenic nerves and surrounding muscles, underlying the site of ligature application, was similarly found, suggesting a role for phrenic nerve stimulation with consequent diaphragmatic paralysis in contributing to death in the hanging process. Discussion and Conclusion In this Ph.D thesis the principles of dimensional analysis i.e., the breaking down of a complex phenomenon into its component parts, have been applied. However, in view of the complexity and proximity of structures to one another in the neck, consisting not only of the rigid hyoid-larynx complex and vertebral column but also the integrated vascular and neural structures, it appears that not one single biological mechanism can be ascribed and attributed to the cause of death in suicidal hanging. Rather, it appears that unconsciousness and death causation appears to be multifactorial. Both the sympathetic and parasympathetic arms of the autonomic nervous system are involved, often with antagonistic and therefore paradoxical effects. In a ddition, pressure to the phrenic nerve, not previously considered in playing a role in death causation in hanging, may, it is suggested, be a major contributory factor in death causation. This nerve, the innervation to the major muscle of respiration, i.e. the diaphragm, in a neural response to the compressive and tensile forces in hanging, fixes the diaphragm in a state of inspiratory paralysis. This latter effect would be further augmented by neural stimulation of the accessory muscles of respiration, i.e. the sternocleidomastoid and scaleni muscles, similarly lying deep to the site of ligature application, contributing to the thoracic cage becoming fixed in a state of inspiratory paralysis. This latter effect, as described in that section of the Discussion chapter dealing with an analysis of the physiological functions at play, is brought about by initiation of the dynamic and static stretch reflexes occurring in these muscles on application of a compressive or tensile stimulus. Compression of the carotid arteries, on the other hand, results, as shown, not only in major damage to these vessels and their accompanying veins, but, in addition, must produce a dramatic element of cerebral ischaemia with ensuing loss of consciousness. It thus appears that loss of consciousness is the critical factor for it is the state when the victim is no longer able to save himself or herself. Without loss of consciousness survival may occur, but with it, death becomes inevitable. The question then arises :- what is the cause of unconsciousness? In physiological terms, carotid artery occlusion induces rapid unconsciousness, i.e. within 11 to 12 seconds, resulting ultimately in death. In other words, the sudden application and unremitting pressure of the ligature must inevitably result in death. On the other hand, the sudden application of a ligature with consequent vagal nerve compression may produce instantaneous cardiac arrest with cessation of blood flow to the brain and resultant loss of consciousness. This event would produce unconsciousness in less than the time period of 11 seconds of carotid artery occlusion (although the brain continues to survive for several minutes thereafter despite cessation of heart beat). If, however, unconsciousness is contributed to by phrenic nerve compression, it would not be instantaneous as shown by the fact that one can normally hold one’s breath for several minutes (as underwater swimmers do) and unconsciousness does not supervene either instantaneously or within 11 seconds. In short, unconsciousness would not occur within 11 seconds in the case of compression of the phrenic nerve unless a more critical factor supervenes.Thus, the rapidity of onset of unconsciousness appears to be the critical factor in determining the progression to ultimate (and inevitable) death. Moreover, as pointed out in the Materials and Methods chapter, the carotid arteries in several tested cases would not allow the passage of a probe through the obstructed arteries beneath a tightly applied ligature. This obstruction would, therefore, appear to be the initiator of the deadly unconsciousness factor, although respiratory arrest would be compounded by neural and muscular factors. While in this thesis the principles of dimensional analysis i.e., the breaking down of a complex phenomenon into its component parts have been applied, the principles of integrated analysis i.e., the combining and synthesis of separate parts into a whole have also been attempted. In essence, while it is suggested that the neural elements play a pivotal role in the hanging process due to the neural effect on both brain and heart as a result of autonomic nervous system stimulation and the function of the phrenic nerve in respiration, it appears that multiple factors, acting in concert, simultaneously or in rapid sequence to one another, all play a role in contributing to death causation in the hanging process.
19

Normal Mandibular Morphology of Inbred Mouse Strains

Edwards, Michelle Halum January 2004 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Even though the molecular events and pathways that underlie craniofacial development and morphogenesis are not fully understood, it is accepted that their orchestration is influenced by the interaction of genetic and environmental factors. Inbred mouse strains represent genetically homogenous groups of individuals. It is established that mice in one strain often differ quite remarkably from mice in other inbred strains. Those phenotypic differences make mice exceptional tools for the dissection of genetic factors that influence normal and abnormal craniofacial morphogenesis. While numerous investigations have focused on abnormal morphogenesis, a comprehensive study of normal craniometric morphology across multiple inbred strains of mice has not been previously performed. The Mouse Phenome Project, an international collaboration of investigators, was formed to systematically phenotype a collection of normal inbred mouse strains. The objectives of our studies were to determine and measure differences in quantitative mandibular traits/variables within and between different inbred mouse strains, and to assess sexual dimorphism through bilateral measurements of the hemimandibles. These studies were a component of the Mouse Phenome Project to collect normal craniometric data from 12 genetically heterogeneous inbred strains utilizing digital images from equal numbers of female and male mice at 7 to 8 weeks of age. Our central hypothesis was that morphometric analysis of mandibular structures from genetically disparate inbred mouse strains would reveal quantifiable differences. The null hypothesis of no difference among the strains for mandibular measurements was rejected. Overall, CAST/Ei and MOLF/Ei were consistently small in size measured by body weight with small skeletal structures. There was no strong pattern of body weight and site of skeletal size in the mid and heavy weighted strains. Evidence of sexual dimorphism was supported. Overall, it appears males and females that have the least significance between them are in the DBA/2J strain, followed by A/J. The strain with the most significant difference between males and females is in the C3H/HeJ strain.
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The influence of mother care on the relationship between self-esteem and neural subtrates in young men and women : a neuroimaging study

Wadiwalla, Mehereen. January 2007 (has links)
Introduction. Numerous studies have suggested that maternal care can influence the development and expansion of an individual's self-esteem. Yet the neural mechanisms of this relationship remain unexplored. Incidentally, it has already been demonstrated that a brain region, namely the Hippocampus (HC) is associated with both self-esteem and maternal care. Thus suggesting that there may be a three-way relationship. This also provided the impetus to speculate that a similar interaction could be observed in other brain regions like for example, the Dorsolateral Prefrontal cortex (DLPFC) and the Medial Prefrontal Cortex (MPFC). Therefore, the aim of this study is to scrutinize the possible relationship between mother care, self-esteem and neural correlates including the DLPFC, MPFC and HC, with emphasis on how normal variations in mother care could have consequences for the relationship between self-esteem and particularly the prefrontal cortices. Methods . Fifty-one subjects were recruited on the basis of their maternal scores, as assessed by the Parental Bonding Index and were consequently assigned to either a high mother care (MOCA) or low MOCA group. Their self-esteem was measured through various self-esteem scales including the Rosenberg self-esteem scale. The structural integrity of the regions was ascertained through the use of both manual and semi automated segmenting procedures. Results . Initial Bivariate correlations reported a negative association between DLPFC volumes and self-esteem in the high MOCA group while HC was positively associated with self-esteem in both high and low MOCA groups. There were no associations to report for the MPFC. Additional analysis revealed that the Biregional association was sex specific. Discussion. For the first time, we were successful in associating DLPFC volume with self-esteem. In addition, we successfully replicated the association between self-esteem and HC volume. This study could provide an indication how of maternal care could have a sex specific affect not only on the evolution of self-esteem, but also on the regions they may be targeting.

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