The accurate detection and quantification of human diabetic somatic polyneuropathy (DSPN) are important to define at risk patients, anticipate deterioration, and assess new therapies. Current methods lack sensitivity, require expert assessment and have major shortcomings when employed to define therapeutic efficacy. In recent years, in vivo corneal confocal microscopy (IVCCM) has shown potential as a surrogate endpoint for DSPN.This study aims to investigate fundamental aspects of IVCCM such as repeatability and optimal scanning methodology and establish changes in corneal nerve morphology in relation to the severity of DSPN and regeneration in response to normalisation of hyperglycaemia. Furthermore, it aims to provide a novel fully automated image analysis algorithm for the quantification of corneal nerve morphology and establish the diagnostic ability of CCM.IVCCM shows high repeatability which is enhanced with more experienced observers. Central corneal innervation is comparable to adjacent peripheral innervation in mild diabetic neuropathy but the central cornea may be more sensitive to change. Corneal nerve loss is symmetrical and progressive with increasing neuropathic severity and corneal nerves show significant regenerative capacity following rapid normalisation of glycaemic control after simultaneous pancreas and kidney transplantation. The novel image analysis algorithm strongly correlates with human expert annotation and therefore represents a rapid, objective and repeatable means of assessing corneal nerve morphology. Automated image quantification may replace human manual assessment with high diagnostic validity for DSPN.

Neuropathy is one of the main long term complications of diabetes affecting 30-50% of patients. It is the major contributing factor for foot ulceration with a life time risk which may be as high as 25%. Hence neuropathy leads to reduced pain and pressure perception, anatomic deformities and an impaired microcirculation. More specifically, unperceived minor trauma results in cutaneous injury which when combined with an inadequate pressure induced vasodilator response leads to tissue breakdown and ulceration. Once ulcers form, healing may be delayed or difficult to achieve, particularly if infection occurs in the deeper tissues and bone which can then lead to amputation. In the UK, South Asians (people originating from India, Pakistan and Bangladesh) have an excess mortality for coronary artery disease (CAD), stroke and end-stage renal disease when compared to white Europeans. However, it has been shown that South Asian people with type 2 diabetes in the UK are only one third as likely to have a foot ulcer compared with White European diabetic patients. This has been attributed to lower levels of peripheral neuropathy in Asians, but has not been systematically explored in detail. In the present study, both neurological and vascular deficits in a group of South Asian and European patients with type II diabetes have been assessed. The results demonstrate that: • South Asian diabetic patients have poorer glycaemic control, but paradoxically lower triglycerides. This finding may be relevant to the finding that they have a lower incidence of neuropathy, as triglycerides have been related to neuropathy and foot ulceration. • South Asians compared to Europeans have better small fibre function and a trend for better structure (Intra epidermal nerve fibre density and corneal nerve morphology) and large fibre function assessed with nerve conduction studies. • South Asians have higher foot skin oxygenation and hyperaemic blood flow response to heating. • South Asians have a thicker epidermis and a trend for a better capillary density. Therefore these alterations may protect South Asians from the development of foot ulceration.

Baroreflex control of heart rate (HR) is impaired in diabetes mellitus. We hypothesized that diabetes mellitus induced functional changes of neural components at multiple sites within the baroreflex arc. Type 1 diabetic mice (OVE26) and FVB control mice were anesthetized. Baroreflex-mediated HR responses to sodium nitroprusside- (SNP) and phenylephrine- (PE) induced mean arterial blood pressure (MAP) changes were measured. Baroreceptor function was characterized by measuring the percent (%) change of baseline integrated aortic depressor nerve activity (Int ADNA) in response to SNP- and PE-induced MAP changes. The HR responses to electrical stimulation of the left aortic depressor nerve (ADN) and the right vagus nerve were assessed. Compared with FVB control mice, we found in OVE26 mice that (1) baroreflex-mediated bradycardia and tachycardia were significantly reduced. (2) The baroreceptor afferent function in response to MAP increase did not differ, as assessed by the parameters of the logistic function curve. But, the inhibition of Int ADNA in response to MAP decrease was significantly attenuated. (3) The maximum amplitude of bradycardic responses to right vagal efferent stimulation was augmented. (4) In contrast, the maximum amplitude of bradycardic responses to left ADN stimulation was decreased. Since Int ADNA was preserved in response to MAP increase and HR responses to vagal efferent stimulation were augmented, we conclude that a deficit of the central mediation of baroreflex HR contributes to the overall attenuation of baroreflex sensitivity in OVE26 mice. The successful conduction of physiological experiments on the ADN in OVE26 mice may provide a foundation for the understanding of cellular and molecular mechanisms of diabetes-induced cardiac neuropathy.

Peripheral sensitisation and central sensitisation are implicated in the development of neuropathic pain with neuroplasticity occurring at multiple levels of the pain pathway. Hypersensitivity of the spinothalamic tract has been described in neuropathic animal models of diabetes. Spinal dorsal horn neurones of diabetic rats exhibit abnormally high spontaneous firing, suggesting an imbalance between excitatory and inhibitory signals converging within this structure. GABAergic neurones within the spinal cord and thalamus are crucial for the transmission of painful stimuli to higher centres of the brain that are involved in pain perception. GABAA receptors (GABAARs) are an important target for many clinical drugs, and certain endogenous neurosteroids act as potent allosteric modulators of these receptors. A developmental change in the rate of exponential decay of GABAergic synaptic events has been observed in other types of neurones and this may be related in part to fluctuations in endogenous neurosteroid tone. The objective of this study was to investigate changes to inhibitory neurotransmission with development in three levels of the pain pathway and to explore potential mechanisms underlying diabetic neuropathy. The whole-cell patch-clamp technique was used on slices of neural tissue. Electrophysiological recordings were obtained from wild type mice between the ages of 6 and 80 days in lamina II of the spinal cord, the nucleus reticularis (nRT) of the thalamus and the cerebral cortex. Recordings were also obtained from mice with diabetic neuropathy (ob/ob and db/db) between the ages of 60 and 80 days. Neurosteroids and their precursors were employed along with compounds that prevented their activity at the GABAAR such as ?-cyclodextrin, which is a barrel-shaped cyclic oligosaccharide with a lipophilic interior that sequesters neurosteroids. Behavioural experiments were also performed using von Frey filaments and the tail flick test to examine mechanical and thermal nociception. Recordings from the spinal cord, the thalamus and the cerebral cortex revealed that the decay time of miniature inhibitory postsynaptic currents are significantly reduced with development. The neurosteroids allopregnanolone and ganaxolone were significantly more effective in neurones from the older mice. In contrast, ?-cyclodextrin had significantly less effect in neurones from the older mice. In mature diabetic mice (ob/ob mice), the endogenous neurosteroid tone is reduced compared to control mice, but certain neurosteroid compounds have a greater effect on the GABAARs of these diabetic mice. In addition, the diabetic mice exhibit mechanical allodynia and hyperalgesia, which is responsive to exogenously applied neurosteroids. These results are consistent with the hypothesis that a dramatic reduction in endogenous neurosteroid tone occurs as development progresses and that this impacts on the exponential decay time of GABAergic mIPSCs within neurones of the pain pathway. The higher neurosteroid tone in the youngest mice may confer a degree of neural protection over the nervous system as it develops. The reduction of endogenous neurosteroid tone in diabetic mice may be associated with their hypersensitivity. It is possible that pregnane-derived neurosteroids may exert analgesic effects in pathological pain states by attempting to restore the physiological GABAergic inhibitory tone that is observed in immature animals.

Background: Despite a lack of consensus on its utility, clinicians have traditionally relied on plantar pressure (PP) to predict ulcer risk and prescribe interventions in individuals with diabetic peripheral neuropathy (DPN). Joint kinematics and kinetics have the potential to contribute to DPN assessment and treatment, however previous studies have not accounted for walking speed nor integrated a full-body analysis with a detailed foot model. Purpose: To assess PP and gait alterations in DPN by controlling walking speed and incorporating a multisegment foot model into a full-body gait analysis. We hypothesize that hip and ankle kinetics will be altered consistent with distal muscle weakness. Methods: Ten subjects with DPN (height: 178.79 ± 8.55 cm, weight: 108.78 ± 16.67 kg, age: 61.5 ± 13.53 years), and 10 healthy matched controls (height: 180 ± 6.37 cm, weight: 92.87 ± 14.5 kg, age: 59.4 ± 7.5 years) participated in this cross-sectional study. Fifty-six reflective markers were attached to each subject according to a full-body model, including a multisegment foot. Subjects walked at a controlled speed (1 m/s) while plantar pressure, kinematic and kinetic data were collected. Functional data analysis was used to compare kinematic and kinetic data between groups, while independent t-tests and a Benjamini-Hochburg procedure was used to compare plantar pressure and joint work metrics. Results: Individuals with DPN presented with a delayed transition from hip extension to hip flexion moment and a decrease in peak hip flexion moment. There were no major changes found at the knee. There was an increase in peak dorsiflexion angle and delayed power generation in both the ankle and midtarsal joints. DPN subjects also showed a decreased midtarsal positive work. The only significant PP metric found was a decrease in peak PP under the lateral toes. Conclusion: Findings demonstrated that individuals with DPN use a hip compensation mechanism to overcome distal muscle weakness. Ankle and midfoot alterations are consistent with muscle weakness, requiring proximal compensations. Joint mechanics were more informative than PP measurements and may provide additional insight into DPN assessment and treatment.

El Glucagon-like peptide-1 (GLP-1), un pèptid derivat del processament del proglucagó en les cè_lules L del jejúnum i del colon, inhibeix la secreció àcida gàstrica i el buidament gàstric, a més de reduir la capacitat d'ingesta. Els mecanismes d'acció del GLP-1 no estan clars. Hi ha dades que suggereixen que la inhibició de les funcions gàstriques per part del GLP-1 estan mitjançades pel nervi vagus.L'acomodació o relaxació gàstrica en resposta a la ingesta és un reflex mitjançat pel vagus que dóna lloc a un increment del volum o capacitat gàstrica que impedeix l'increment de la pressió intragàstrica quan mengem, evitant així l'aparició de símptomes. La primera hipòtesi que vàrem plantejar va ser que el GLP-1 inhibeix el reflex d'acomodació gàstrica i que això explicaria en part la reducció de la capacitat d'ingesta que s'observa en administrar el GLP-1. Per provar aquesta hipòtesi vàrem comparar els efectes d'una infusió endovenosa de GLP-1 i placebo, en voluntaris sans, sobre l'acomodació gàstrica postprandial (mesurada amb la tècnica SPECT), l'increment postprandial del polipèptid pancreàtic (marcador de funció vagal abdominal) i el volum d'un nutrient líquid (Ensure®) ingerit fins atansar la sacietat màxima. Els resultats del primer estudi van demostrar que el GLP-1 no inhibeix l'acomodació gàstrica postprandial; al contrari, va augmentar el volum gàstric en dejú i després del menjar. Això es va acompanyar per una marcada inhibició de la secreció de polipèptid pancreàtic, la qual està sota control vagal colinèrgic. Degut a que el to gàstric està mantingut per influència colinèrgica vagal, els resultats obtinguts són compatibles amb la hipòtesi de que el GLP-1 indueix relaxació gàstrica (augment de volum gàstric) per inhibició de les vies colinèrgiques vagals. Si aquesta hipòtesi fos certa, en cas de disfunció vagal o vagotomia, el GLP-1 no produiria relaxació gàstrica (augment de volum gàstric). Per provar aquesta segona hipòtesi, vàrem estudiar l'efecte de la mateixa infusió endovenosa de GLP-1, comparada amb placebo, en els volums gàstrics de subjectes amb neuropatia vagal diabètica. Vàrem comparar també els volums gàstrics dels malalts diabètics que rebien placebo amb els dels subjectes sans estudiats en el primer estudi presentat en aquesta tesi. Al contrari del que vàrem observar en subjectes sans, el GLP-1 no va augmentar el volum gàstric en malalts diabètics amb neuropatia vagal. Això suggereix que l'efecte del GLP-1 sobre el volum gàstric està mitjançat pel nervi vagus.Els malalts diabètics avaluats presentaven volums gàstrics, tan en dejú com després del menjar, similars als dels subjectes sans. El nervi vagus participa en el control del to o volum gàstric, però hi ha altres mecanismes que també hi participen. Es més, hi ha evidència de que el to gàstric pot ser controlat adequadament en absència de innervació vagal extrínseca. De manera que la troballa de la existència de volums gàstrics normals en malalts amb neuropatia vagal s'afegeix a la evidència de que, en cas d'alteració del reflex principal vago-vagal, es produeix un mecanisme adaptatiu per preservar la resposta de relaxació gàstrica postprandial. / Glucagon-like peptide-1 (GLP-1), a peptide derived from the processing of the proglucagon molecule in L cells of the jejunum and colon, inhibits gastric acid secretion and gastric emptying rate and it also decreases food consumption. It is still not clear how these effects of GLP-1 are mediated. There are data that suggest that GLP-1 inhibition of upper gastrointestinal functions is mediated through the vagus nerve.The accommodation or relaxation of the stomach in response to meal ingestion is a vagally-mediated reflex that increases gastric volume. This prevents the increase in intragastric pressure when food and fluid enter in the stomach, avoiding the development of symptoms. We hypothesized that GLP-1 inhibits the gastric accommodation reflex and that this effect could partly explain the reduced food consumption with GLP-1. To test this hypothesis, we compared, in healthy volunteers, the effects of intravenous infusion of GLP-1 and placebo, on postprandial gastric accommodation (as measured by the SPECT technique), postprandial response of plasma human pancreatic polypeptide (a surrogate marker of vagal abdominal function) and the volume of a nutrient liquid meal (Ensure_) ingested at maximum satiation. The results of the first study showed that GLP-1 does not inhibit postprandial gastric accommodation; on the contrary, it increased fasting and postprandial gastric volumes. This was accompanied by a marked inhibition of the pancreatic polypeptide release, which is under vagal cholinergic control. Since gastric tone is maintained by vagal cholinergic input, the results observed in our first study suggested that GLP-1 could induce gastric relaxation (increase gastric volume) by inhibition of vagal cholinergic pathways. If this hypothesis were true, one would predict that in the presence of vagal dysfunction or vagotomy, GLP-1 would not induce gastric relaxation (increase gastric volume). To test this second hypothesis we studied the effect of the same intravenous infusion of GLP-1, compared to placebo, on gastric volumes in a sample of subjects with diabetes affected with vagal neuropathy. We also compared gastric volumes in diabetic patients on placebo to those in the healthy subjects who participated in the first study presented in this thesis. In contrast to effects in health, GLP-1 did not increase gastric volume in diabetics with vagal neuropathy. This suggests that the effect of GLP-1 on gastric volume is dependent on vagal function. The diabetic patients evaluated had gastric volumes similar to those of healthy controls. The vagus nerve participates in the control of gastric volume or tone; however, there are other mechanisms involved. Furthermore, there is increasing evidence that gastric tone may be adequately controlled in the absence of extrinsic vagal innervation. Thus, we believe that the normal gastric volume response to a meal observed in the presence of vagal neuropathy adds to the growing evidence of the existence of an adaptive response preserving postprandial gastric relaxation when the main vago-vagal reflex is impaired.

No description available.

Made available in DSpace on 2014-06-11T19:22:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-15Bitstream added on 2014-06-13T19:28:14Z : No. of bitstreams: 1 nozabieli_ajl_me_prud.pdf: 389297 bytes, checksum: 18d283320999ea56627c9e2743d72159 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estudo teve por objetivo avaliar as pressões e áreas de superfícies plantares e os componentes vásculo-sensório-motores dos pés de portadores de neuropatia diabética. Sessenta e oito indivíduos divididos em dois grupos: 28 no grupo neuropata e 40 no grupo controle, participaram do estudo. Os voluntários foram submetidos às avaliações da circulação e perfusão periférica de membros inferiores, por meio do índice tornozelo/braço e oximetria; sensibilidade somatossensitiva, pela estesiometria; força muscular do tornozelo, por dinamômetro digital portátil; e pressões e superfícies plantares com um baropodometro eletrônico. Os grupos foram comparados por meio dos testes Mann-Withney e análises de variâncias (ANOVA e MANOVA) (p<0,05). A sensibilidade tátil, o índice tornozelo/braço e a força muscular de dorsiflexores e plantiflexores de tornozelo estiveram diminuídas no grupo neuropata em relação aos controles. Nos picos de pressões plantares não foram verificadas diferenças entre os grupos, mas ocorreu diferença nos locais onde essas pressões foram impostas. Na condição estática, a área de superfície plantar foi maior no grupo neuropata, quando comparado ao controle... / The objective of this study was to analyze the postural control, using baropodometry, in patients with diabetic neuropathic and relate with loss in the sensorimotor system. Twenty-eight healthy subjects and 25 patients with diabetic neuropathic were evaluated with baropodometry in two conditions: static (for measure the center of pressure displacement) and dynamics (for measure the stance phase of gait cycle – total period of support, double support and single support). The tactile sensitivity of the feet was measured with a Semmes-Weinstein pressure esthesiometer and the isometric muscle strength of ankle was measured with dinamometry. The MANOVA and ANOVA indicated lower performance in tactile and force muscle in diabetic neuropathy. In the dynamic condition the diabetic neuropathy group showed more time in the gait parameters. With this study, by regression analysis, we can say that the differences of balance in the neuropathy diabetic gait may result from decreased of sensitivity tactile and strength

No description available.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12876号 / 論農博第2803号 / 新制||農||1028(附属図書館) / 学位論文||H26||N4875(農学部図書室) / 31594 / (主査)教授 伏木 亨, 教授 保川 清, 教授 入江 一浩 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM