Thesis (M.D.)--University of Hong Kong, 1995. / Includes bibliographical references (leaves 167-178).

Thesis (M.D.)--University of Hong Kong, 1995. / Includes bibliographical references (leave 167-178). Also available in print.

A study of hypersensitivity of high school students to the oleoresins of fifty common North Texas plants.

No description available.

No description available.

Wet-work exposure has been recognized as a main risk factor for developing Irritant contact dermatitis of the hand. Duration and frequency of wet-work exposure are the key risk determinants, but there is still no reliable objective method to assess these factors in the workplace. The current study aimed to further validate a newly invented wet-work exposure monitor (WWEM) among four high risk occupational groups of hairdressers, florists, caterers and nurses. The WWEM, which consists of two similar thermocouples provides a real-time indication of the wetness of the finger by measuring the temperature changes when the finger is wet and subsequent cooling when the water evaporates from the skin. A suitable data analysis routine was constructed and direct observation was employed as the gold standard. Receiver Operating Characteristic (ROC) analysis was used to compare the results. In laboratory experiments, the most suitable wet-event threshold value, as a criterion to distinguish the wet and dry exposure periods was identified as 1.6°C (Mean+5SD of the “dry” data). Using this value sensitivity and specificity were 70% and 78%, respectively. An area under the curve (AUC) of 0.78 demonstrated a “high” accuracy for WWEM in lab experiments. Field testing in real occupational fields identified varying degrees of user acceptability and different wet-event threshold values to produce maximal sensitivity and specificity of the instrument. Among hairdressers, the WWEM showed a “moderate” accuracy at the threshold value of 1.37°C with an AUC of 0.62. For florists, the most suitable threshold value in the range of examined thresholds was 1.14°C with a “good” accuracy. Among a cohort of caterers, a threshold value of 1.6°C demonstrated a “hi gh” accuracy with an AUC of 0.72. The WWEM demonstrates the minimum value of the largest AUC for nurses. This is the minimum amount of accuracy among the four occupational groups. The figure is 0.52, achieved at a threshold value of 2.5°C. The WWEM enables the frequency and duration of wet-work exposure to be assessed in an objective manner rather than the current costly and unreliable subjective methods of direct observation and questionnaire. The results indicate that the WWEM has good sensitivity and high specificity in detecting exposure to wet-work. This device provides new experimental data on wetwork exposure and may be used in future as an educational tool to highlight the importance of wet-work exposure to both employees and employers.

Atopic eczema is a common condition that can interfere with social function, sleep and employment. Its persistence and accompanying pruritis may be stressful and frustrating for patients (Zug and McKay 1996 : 1243). The purpose of this randomised, double-blind, placebo-controlled study was to evaluate the efficacy of a homoeopathic complex (Arsenicum album 12CH, Graphites 12CH, Petroleum 12CH, Rhus toxicodendron 12CH, Sulphur 12CH and Urtica urens 12CH), in the treatment of atopic eczema in terms of its clinical manifestations and the impact on the quality of life of the patient. Thirty patients between the ages of eighteen and sixty years who met the Diagnostic criteria (Appendix A), were selected to participate in this study. Simple random sampling was used to divide them into two equal groups of fifteen i.e. the treatment group (Group 1) and the placebo group (Group 2). The trial lasted three months; at the initial consultation patients filled in the Clinical Evaluation Index (Appendix C), the Patients’ Perception questionnaire (Appendix D) and the General Well Being Schedule (Appendix E). Patients then received their three months supply of medication or placebo. Patients returned after three weeks and filled in the questionnaires and repeated this procedure every two weeks until the end of the trial. This amounted to six consultations per patient. Statistical evaluation of the data obtained from the questionnaires were analysed using the SPSS ver. 9 package. The Friedman test and Wilcoxon signed rank test were used to analyse the intra group comparisons. These are non parametric tests. The Mann-Whitney U-test was used for the inter group comparison. Both groups showed improvements with regards to all three questionnaires. The placebo group showed consistent improvement throughout the study. Therefore, statistically there was no difference between the two groups. The results of this study demonstrated that the use of a homoeopathic complex (Arsenicum album 12CH, Graphites 12CH, Petroleum 12CH, Rhus toxicodendron 12CH, Sulphur 12CH and Urtica urens 12CH) was no more effective than the placebo in the treatment of atopic eczema. / Dr. M. R. A. Moiloa Dr. D. Naude Dr. C. Hall

A 22-year-old male college student presented to primary care with a pruritic rash on his mid abdomen for the past 2 weeks. He reported mild to moderate pruritus and had been scratching the area above his belt buckle.

Skin and nasal bacterial dysbiosis is common in children with atopic dermatitis (AD). However, there is limited data of these bacterial changes in sub-Saharan children with AD. Therefore, this study investigated the bacterial alterations in skin and nasal bacterial communities in AD compared to healthy children in rural and urban South African settings. Staphylococcus aureus was more common in children with AD (cases) than healthy children (controls). S. aureus carriage was also associated with increased disease severity. Using spa typing, we also showed that cases and controls were colonised by distinct spa types. This led us to comprehensively explore genomic differences of S. aureus in cases and controls using whole-genome sequencing. Here, we showed that S. aureus strains from cases and controls had distinct genomic features, with cases harbouring genes associated with antibiotic resistance, DNA damage repair and virulence while controls had genes associated with adhesion. Recent reports indicate the potential role of coagulase-negative Staphylococcus (CoNS) in AD pathology. This study found that CoNS and S. aureus were commonly co-carried on nonlesional skin among cases (regardless of location) and anterior nares among urban cases than the control group. The carriage of S. capitis on nonlesional skin and anterior nares was positively associated with more severe disease in both rural and urban cases. 16S rDNA amplicon sequencing analysis revealed that bacterial diversity was higher on the nonlesional skin and anterior nares of controls. Bacterial community structure differed on lesional skin, nonlesional skin and anterior nares based on AD disease status. The relative abundance of Streptococcus, Granulicatela, Veillonella and Prevotella was high in lesional skin specimens, Anoxybacillus and Cutibacterium on nonlesional skin, and Staphylococcus, Veillonella and Sphingomonas in the anterior nares among cases Overall, the findings presented in this thesis indicate that S. aureus and other CoNS, particularly S. capitis, may predominate among cases and are associated with increased disease severity. However, the increased relative abundance of genera such as Streptococcus, especially among skin samples, indicates that other bacterial genera may be contributing to disease activity on lesional skin in AD than the traditionally reported Staphylococcus.

Clostridial dermatitis (CD) is a multifactorial disease of rapidly-growing turkeys. Clostridium septicum (Cs) has been identified as the primary cause, although C. perfringens (Cp) has also been implicated. Pathogenesis is not fully understood; however, it is hypothesized that Clostridia translocate from the gastrointestinal tract and spread hematogenously to capillary beds of skeletal muscles. Intense genetic selection has produced a rapidly growing bird that is heavier and less active. This may predispose birds to development of CD due to positional restriction of blood flow to the caudal breast and medial thigh. Subsequent reduction in oxygen tension within these tissues produces conditions conducive to germination, proliferation, and toxin production by previously trapped, non-replicative Clostridia. Studies were undertaken to investigate the epidemiology and pathophysiology of CD. Retrospective epidemiologic investigations evaluated incidence, risk factors, and economic impact of CD. Cs and Cp qPCR were performed on blood and tissue samples to demonstrate hematogenous spread in asymptomatic birds. Studies assessed the effect of prolonged recumbency by measuring oxygen saturation and surface temperature in dependent tissues. Tissues from CD cases were evaluated for Cs and Cp alpha toxin mRNA (CsA and CpA). Analyses were conducted to determine associations between these toxins and severity of histopathologic lesions. Whole genome sequencing was performed on the Cs type strain to identify other toxin genes. Flock type, breed, weight at time of processing, and stocking density affected disease incidence. Detection of Clostridium spp. in intestine, liver, and muscle from asymptomatic turkeys without cutaneous trauma implies hematogenous spread from an endogenous source. Focal polyphasic myonecrosis in dependent muscles of asymptomatic turkeys suggests an underlying predisposition to development of CD. Recumbency appeared to be associated with decreased perfusion to these tissues. Cs DNA was present in asymptomatic birds without corresponding CsA mRNA expression suggesting that organisms were present in a quiescent form. CsA was associated with CD while CpA did not appear to be involved in pathogenesis. Genome sequencing identified several coding regions which may correspond to other potentially active Cs toxins. These results support the proposed mechanism of pathogenesis and provide targets for further investigation of disease pathophysiology and vaccine development. / Ph. D.