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Biomedical subjects

R B Dymock

Publications and source records attributed to R B Dymock.

At least 19 recordsLinked to original sources
PubMed2002

Brachylaima cribbi (Digenea: Brachylaimidae): scanning electron microscopical observations of the life-cycle stages.

Brachylaima cribbi is a recently described species of terrestrial trematode that infects mammals and birds with helicid land snails as its first and second intermediate hosts. The adult worm is 2.5-6.0 mm long by 0.5-0.8 mm wide being a long slender cylindrical worm with oral and ventral suckers in the anterior quarter and genital pore in the posterior quarter. Scanning electron microscopy shows that there is a dense covering of tegumental spines at the anterior end which diminishes towards the posterior extremities of the worm. Development of spines was observed in juvenile and mature adult worms. In young worms 1-3 weeks post infection (wpi) spines appear as buds with a serrated edge each having 1-4 spikes per spine. As the worm ages the spines broaden and by 5 wpi the number of spikes per spine increases to an average of 8.1. The serial development of oral sucker papillae in the cercaria, metacercaria and adult worm was observed with the finding of an elongated papilla with a bifurcated tip on the cercaria becoming a shorter and thicker elongated papilla with a large central stoma on the metacercaria. In the adult worm, this papilla becomes dome-shaped with a small central stoma. For some of these papillae a cilium could be seen extended from the central stoma. Other life-cycle stages illustrated were the hatched egg with an extruded egg membrane minus an operculum and a portion of the branched sporocyst dissected from the digestive gland of the land snail Theba pisana showing a terminal birth pore. Scanning electron microscopy morphological features of the adult worm observed for the first time in a Brachylaima were the unarmed cirrus extended from the genital pore with released sperm present and the Laurer's canal opening visible in tegumental folds on the dorsal surface approximately 300 microm posterior to the genital pore.

Animals↗
PubMed2001

The role of small intestinal bacterial overgrowth, intestinal permeability, endotoxaemia, and tumour necrosis factor alpha in the pathogenesis of non-alcoholic steatohepatitis.

BACKGROUND: Small intestinal bacterial overgrowth may contribute to the development of non-alcoholic steatohepatitis, perhaps by increasing intestinal permeability and promoting the absorption of endotoxin or other enteric bacterial products. AIMS: To investigate the prevalence of small intestinal bacterial overgrowth, increased intestinal permeability, elevated endotoxin, and tumour necrosis factor alpha (TNF-alpha) levels in patients with non-alcoholic steatohepatitis and in control subjects. PATIENTS AND METHODS: Twenty two patients with non-alcoholic steatohepatitis and 23 control subjects were studied. Small intestinal bacterial overgrowth was assessed by a combined (14)C-D-xylose and lactulose breath test. Intestinal permeability was assessed by a dual lactulose-rhamnose sugar test. Serum endotoxin levels were determined using the limulus amoebocyte lysate assay and TNF-alpha levels using an ELISA. RESULTS: Small intestinal bacterial overgrowth was present in 50% of patients with non-alcoholic steatosis and 22% of control subjects (p=0.048). Mean TNF-alpha levels in non-alcoholic steatohepatitis patients and control subjects were 14.2 and 7.5 pg/ml, respectively (p=0.001). Intestinal permeability and serum endotoxin levels were similar in the two groups. CONCLUSIONS: Patients with non-alcoholic steatohepatitis have a higher prevalence of small intestinal bacterial overgrowth, as assessed by the (14)C-D-xylose-lactulose breath test, and higher TNF-alpha levels in comparison with control subjects. This is not accompanied by increased intestinal permeability or elevated endotoxin levels.

Adult↗
PubMed2000

Effect of packing on nasal mucosa of sheep.

The effects of packing with ribbon gauze and neuropatties on the nasal mucosa was assessed using sheep as an animal model. Fourteen sheep either underwent ribbon gauze or neuropattie nasal packing. Trauma to nasal mucosa caused by ribbon gauze and neuropatties was compared to mucosa on the lateral aspect of the middle turbinate which was not in contact with any packing. This tissue was used as a control. Ribbon gauze packing resulted in significant loss of 68 per cent of the ciliated surface of the mucosa when compared with the control group with a 15 per cent loss of ciliated surface (p < 0.005). Neuropattie packing also resulted in significant loss of 50 per cent of the ciliated surface of the mucosa when compared with the control group (p < 0.005). There was no significant difference in loss of ciliated mucosa in the specimens packed with ribbon gauze or neuropatties (p = 0.25). Nasal packing results in a significant mucosal injury with loss of cilia. This may influence the mucociliary clearance of the nose in the post-operative healing phase. Pre-operative nasal packing should be used circumspectly and if possible avoided.

Animals↗
PubMed1999

A randomized controlled trial to determine the effects of humidified carbon dioxide insufflation during thoracoscopy.

BACKGROUND: The humidification of gas insufflated during laparoscopy can reduce the degree of postoperative hypothermia and may result in less peritoneal reaction and less postoperative pain. The present study was designed to determine whether the beneficial effects of humidified gas insufflation also applied to thoracoscopy. METHODS: Six pigs were each studied on three separate occasions with insufflation into the right thoracic cavity of either humidified gas, standard dry gas, or with no insufflation (control procedure). Core body temperature was recorded every 15 min, and biopsies of the parietal pleura were taken at the end of each study for electron microscopy. RESULTS: Humidification of insufflated gas significantly minimized the fall in core temperature during the procedure. Electron microscopy showed that dry gas insufflation resulted in greater structural injury to the pleura than humidified gas insufflation. CONCLUSIONS: The potential benefits of humidifying insufflation gas during thoracoscopy warrant its evaluation in the clinical setting.

Analysis of Variance↗
PubMed1998

Cutaneous necrosis from calcific uremic arteriolopathy.

Calcific uremic arteriolopathy (calciphylaxis) is an uncommon complication of chronic renal failure that is associated with high morbidity and mortality. We report 16 patients (13 female) who presented between 1985 and 1996. All patients developed painful livido reticularis that progressed to cutaneous necrosis and ulceration (11 cases on the proximal extremities and five cases on the distal extremities). Two patients with predominately distal leg disease survived; the cause of death in the other 14 patients was sepsis (six patients), withdrawal from dialysis (three), cardiac arrest (three), and gastrointestinal hemorrhage (two). Mesenteric ischemia from intestinal vascular calcification occurred in two cases. Clinical factors identified included the use of warfarin therapy in seven cases and significant weight loss (>10% body weight) in seven cases in the 6 months preceding the development of calcific uremic arteriolopathy. Skin pathology was studied in 12 cases, with all showing calcific panniculitis and small vessel calcification. Electron microscopic spectral analysis of the mineral content of the calcific lesions in the subcutaneous tissue showed only calcium and phosphorous. In two cases, substitution of low molecular weight heparin for warfarin therapy resulted in clinical improvement. Current theories of pathogenesis and treatment are reviewed. This study confirms the high morbidity and mortality of calcific uremic arteriolopathy producing ischemic tissue necrosis while drawing attention to significant weight loss and warfarin therapy as risk factors for the development of ischemic tissue necrosis. Hyperbaric oxygen therapy warrants further study.

Adult↗
PubMed1998

Somatic mutations, acetylator status, and prognosis in colorectal cancer.

BACKGROUND: Somatic mutations in K-ras and TP53 may be associated with both acetylator status and prognosis in colorectal cancer. AIMS: To determine whether cancers with somatic mutations are more frequent in fast acetylators and whether mutations or acetylator status influence prognosis after colorectal surgery. PATIENTS: One hundred consecutive subjects undergoing elective surgery for colorectal cancer. METHODS: Acetylator status was determined by polymerase chain reaction (PCR) genotyping for polymorphism in the N-acetyltransferase 2 (NAT2) gene. Mutations in K-ras (codon 12) and TP53 were determined by PCR analysis using restriction enzyme digestion and single strand conformation polymorphism respectively. Survival from colorectal cancer for up to five years after diagnosis was analysed using the Kaplan-Meier product limit estimator. Cox proportional hazards regression was used to compare survival rates after adjusting for tumour stage. RESULTS: Mutations in K-ras and TP53 were independent of acetylator status. By log rank test, survival was significantly reduced in subjects with TP53 mutations (p = 0.003) but was not significantly related to acetylator status or the presence of K-ras mutations. After adjustment for tumour stage, subjects with both TP53 and K-ras mutations had a 4.2-fold case fatality (95% confidence interval 1.5 to 11.6) when compared with that of a TP53 negative reference group. CONCLUSION: The presence of both TP53 and K-ras mutations in colorectal tumours is an adverse prognostic marker which is independent of tumour stage.

Acetylation↗
PubMed1991

Primary squamous carcinoma of the liver: clinical and histopathological features.

A case of primary squamous carcinoma of the liver is analysed in the light of 21 previously reported cases. Symptoms of abdominal pain, weight loss and intermittent fever were in keeping with those most frequently recorded for the tumour type. Histopathological evaluation suggested metaplastic origin from a cholangiocarcinoma. A squamous carcinoma found in the liver need not reflect metastatic spread and primary tumours can be resected if well localized.

Carcinoma, Squamous Cell↗
PubMed1988

Superficial angiomyxomas with and without epithelial components. Report of 30 tumors in 28 patients.

This paper describes 30 uncommon dermal and subcutaneous angiomyxoid tumors in 28 patients whose ages ranged from 4 to 78 years (mean, 39 years). There were 16 male patients and 12 female patients. Tumor size varied from 0.5 to 9 cm, with the majority measuring 1-5 cm. Eleven tumors (37%) were located on the trunk, ten (33%) on the lower extremity, five (17%) on the head or neck, and four (13%) on the arm. Microscopically, there were moderately to sparsely cellular angiomyxoid nodules with scattered small vessels. Nine tumors had an epidermal component that took the form of a keratin-filled cyst or epithelial strands. The angiomyxoid components of all 30 tumors were morphologically similar. Electron microscopy showed fibroblastic stromal cells, proteoglycan matrix, and collagen fibers. The S-100 protein stain was negative in two tumors, and the vimentin stain was positive in stromal cells in one tumor. Follow-up information obtained for 20 of the 28 patients included data on eight tumors with epithelial components. Five (63%) of those eight tumors recurred once; three had not recurred, and one patient developed a new and separate purely angiomyxoid tumor. Three (23%) of 13 tumors without epithelial components recurred. None recurred more than once, and none metastasized. We suspect that superficial angiomyxoma, cutaneous focal mucinosis, trichogenic myxoma, trichogenic adnexal tumors, trichodiscoma, myxoid perifollicular fibromas, trichofolliculomas and fibrofolliculomas, the Carney complex, NAME and LAMB syndromes are all closely related. We also believe that the solitary superficial angiomyxoma with no epithelial elements is the most common manifestation of these myxoid tumors.

Adolescent↗
PubMed1987

Giant cell fibroblastoma. A distinctive, recurrent tumor of childhood.

Giant cell fibroblastoma, which was first described by Shmookler and Enzinger in 1983, is a rare fibroblastic tumor occurring mainly in male patients younger than 10 years of age. Only 28 cases have been reported so far. This paper describes seven new cases which were referred in consultation between 1968 and 1985. Five of the seven patients were male; their ages at the time of first surgery ranged from 2 to 18 years, but six of the seven were younger than 4 years. Tumors were all superficial and were situated in the chest (2 tumors), neck, axilla, scrotum, thigh, and finger; they generally grew slowly, were poorly circumscribed, and measured from 1 to 5 cm in maximum dimensions. Grossly, they were described variously as gray, gelatinous, firm, white, fibrous, pink, and watery. Histologically, there were varying proportions of moderately cellular solid areas and angiectoid areas, both featuring distinctive fibroblastic cells with what appeared to be multiple nuclei arranged in florets or wreaths. By electron microscopy, each wreath proved to be an excessively convoluted, but single, multilobed nucleus. The nuclei of the tumor cells were slightly hyperchromatic and not bizarre or pleomorphic. In follow-up times of from 12 months to 11 years (median 31 months), only one tumor recurred locally and none metastasized. The comparatively low recurrence rate in this series may well increase if the patients are followed for a longer period. Giant cell fibroblastoma should probably be classified with other nonmetastasizing, locally recurring fibroblastic proliferations of youth and childhood such as juvenile aponeurotic fibroma and recurring digital fibrous tumor of infancy.

Adolescent↗
PubMed1981

Cutaneous malignant melanoma in South Australia: the main features.

New cases of primary cutaneous melanoma occurring in South Australia in a period of 12 months were studied. The main clinical and pathological features are reported. The incidence is high, but is much less than that reported in Queensland in 1977. Some differences from the Queensland study, concerning the age, sex and site distribution, have been noted, but generally these features are quite comparable. All major pathological types of malignant melanoma occur in South Australia, with a marked preponderance of the superficial spreading type. On the basis of level of invasion and thickness, more than half of the tumours have a good prognosis. The most common reason for excision of melanomas was the observation of a change in the lesion, but some were excised after incidental recognition by a medical practitioner during medical examination for other reasons.

Adolescent↗
PubMed1980

Tuinal as a drug of abuse.

Six case reports are presented to illustrate the problems of abuse of Tuinal (equal parts of sodium quinalbarbitone and sodium amylobarbitone). Over a four-year period in South Australia, Tuinal has risen from causing no deaths to be second only to pentobarbitone as a cause of death. While deaths from pentobarbitone overdosage are largely suicidal, Tuinal deaths are largely accidental, the result of a lack of tolerance in combination with alcohol potentiation.

Adolescent↗
PubMed1980

Leprosy in Indo-Chinese refugees.

Five cases of leprosy, four borderline tuberculoid and one indeterminate, which were recently diagnosed in Indo-Chinese refugees in Adelaide are reported. This diagnosis should be kept in mind when dealing with skin lesions in Indo-Chinese refugees.

Adult↗