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Biomedical subjects

P Andrews

Publications and source records attributed to P Andrews.

At least 55 records · Page 3Linked to original sources
PubMed1996

The pharmacology of the emetic response to upper gastrointestinal tract stimulation in Suncus murinus.

This paper is the first to describe aspects of the mechanics of retching in the insectivore Suncus murinus (house musk shrew) and in an animal of such a small size (approximately 50 g). In anaesthetised animals using the novel stimulus of mechanical stimulation of the upper gastrointestinal tract as the provocative stimulus the frequency of retching was found to be about 4 retches/s, a much higher frequency than in other species (dog, cat, ferret). These studies show that quantification of retching in Suncus cannot be undertaken using direct observation. The temporal pattern of the emetic response was characterised in conscious Suncus using motion (1 Hz, 5 min) and nicotine (20 mg/kg s.c.). The ultrapotent capsaicin analogue resiniferatoxin (100 micrograms/kg s.c.) was discovered to be highly emetic and comparative studies showed that nicotine and resiniferatoxin induced the most intense responses with episodes (retches and a vomit) occurring every 10-15 s. The retching response to mechanical stimulation in the anaesthetised Suncus was not blocked by a 5-HT3 receptor antagonist (granisetron, 1-5 mg/kg s.c.), a tachykinin NK1 receptor antagonist (CP-99,994 20 mg/kg s.c. dihydrochloride salt (9+) -(2S,3S)-3-(2-methoxybenzylamino)-2-phenylpiperidine) or morphine (2 mg/kg s.c.) but was blocked by the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT 100 micrograms/kg s.c.). Suncus appears to be a suitable animal in which to study the pharmacology of the emetic response to mechanical stimulation of the gut. The results are discussed in the light of studies of the pharmacology of emesis in other species.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1996

Capillary GC-ECD and ECNI GCMS characterization of toxaphene residues in primate tissues during a feeding study.

Toxaphene is a pesticide whose use was banned in North America because of concerns regarding its toxicity. To obtain better data on the metabolism and toxicity of toxaphene in primates, a one year feeding study was carried out in cynomologous monkeys at a dose of 1 mg/kg/day for one year. Levels of toxaphene residues in blood and adipose tissue during the dosing period were measured by GC-ECD and ECNI GCMS. The dosing toxaphene mixture was found to be extensively metabolized. Four chlorinated bornane congeners were the predominate residues found in the tissue samples. Blood levels of toxaphene residues plateaued at 40 ppb, adipose levels at approximately 4000 ppb. Kidney, liver, feces and urine were analyzed for toxaphene residues after necropsy.

Adipose Tissue↗
PubMed1996

Acute renal failure as a complication of acute pancreatitis.

To assess the prevalence of acute renal failure (ARF) in patients with acute pancreatitis, as well as the factors predictive of a lethal outcome, we retrospectively studied the data of all patients admitted to our hospital over a 5-year period. Between 1989 and 1993, 554 patients presented with acute pancreatitis, of which 24 (4.4%) subsequently developed ARF. Death occurred in 14/24 (58%) of patients with ARF, and was associated with an increased incidence of multiorgan failure. There was no statistically significant difference in the age, admission blood pressure, or admission pulse rate of the patients who survived and those who died. In contrast, death was associated with a higher Ranson score, and the increased prevalence of multiorgan failure. The length of hospitalization of the nonsurviving group was significantly shorter. Acute renal failure is not a common finding in patients with acute pancreatitis. However, when it occurs, it is associated with a poor prognosis, and is predicted by a higher Ranson score and the presence of multiorgan failure.

Acute Disease↗
PubMed1996

Comparative trial of steroids and surgical intervention in the management of ulnar neuritis.

Fifty-seven ulnar nerves in 39 patients with early neuritis were studied to assess the benefits offered by medial epicondylectomy and external decompression in addition to steroid therapy. The patients were randomly allocated to the surgical or medical group. In those cases where there was bilateral involvement, surgery was carried out on only one side. All cases were assessed prior to treatment and after the first and second years following treatment. The improvement in motor and sensory functions attained at the end of the first year was sustained into the second year. The improvement sustained in both groups was similar even in the second year, and medial epicondylectomy with external decompression seems to have no added benefit as compared to steroid therapy alone in the early treatment of ulnar neuritis. Early diagnosis and treatment, especially in borderline lepromatous cases, seem to offer some hope of nerve function recovery.

Bone and Bones↗
PubMed1996

Evaluation of whole blood antibody kit to detect active Helicobacter pylori infection.

OBJECTIVES: To evaluate the sensitivity and specificity of a whole blood antibody test (Helisal Rapid Blood test) for the detection of Helicobacter pylori using endoscopic diagnostic criteria of histology and urease tests as the "gold standard." METHODS: A prospective trial of Helisal Rapid Blood (HRB) test was carried out in patients undergoing investigations for dyspepsia that included endoscopic biopsy for rapid urease test, microbiological culture, and histology. Blood samples were obtained at the time of endoscopy and were tested for the presence of antibody to H. pylori using the HRB test. In a separate patient group, results of antibody tests in whole venous and capillary blood were compared (n = 25). RESULTS: The rapid blood test was carried out immediately after the endoscopic examination with a result available in under 10 min in all cases. In 203 patients examined, the HRB test detected 70 of 203 to be H. pylori positive as compared with 71 of 203 using urease/histology. Against combined urease/histology tests, the HRB test achieved 82% sensitivity and 91% specificity. Five patients were judged to be "false negative" on endoscopic tests for H. pylori (extensive intestinal metaplasia n = 3; recent use of antimicrobials) yet the HRB test diagnosed the presence of infection, which could be shown to resolve on treatment. The HRB achieved 89% sensitivity and 91% specificity upon correctly including these five patients in the calculations. In all 25 patients tested, venous and capillary blood results concurred giving HRB test positivity in each case. CONCLUSIONS: Whether using whole venous or capillary blood, the HRB test is a quick, convenient, and accurate test for the diagnosis of active H. pylori infection in patients previously not treated. In a subgroup of patients with low level infection due to recent antimicrobials or intestinal metaplasia negative to all endoscopic tests, the blood test can still correctly diagnose H. pylori infection. Because blood samples require no centrifugation before testing, the greatest usefulness of this test will be that of a primary office diagnostic device.

Adult↗
PubMed1995

Omeprazole enhances efficacy of triple therapy in eradicating Helicobacter pylori.

Triple therapy has been recommended as the most effective treatment for Helicobacter pylori eradication. Despite achieving a comparatively high eradication result, however, around 10% of patients still fail to be cured. Omeprazole can enhance efficacy of single and double antibiotic protocols and is particularly effective when combined with clarithromycin and a nitroimidazole. This study examined the effect of combining triple therapy with omeprazole. A prospective, randomised, unblinded, single centre trial was carried out on consecutive patients with symptoms of dyspepsia and H pylori infection confirmed by rapid urease test, microbiological culture, and histological assessment. Patients were given a five times/day, 12 day course of colloidal bismuth subcitrate chewable tablets (108 mg), tetracycline HCl (250 mg), and metronidazole (200 mg) with either 20 mg omeprazole twice daily (triple therapy+omeprazole) or 40 mg famotidine (triple therapy+famotidine) at night. Compliance and side effects were determined using a standard questionnaire form. One hundred and twenty five of 165 triple therapy+omeprazole patients and 124 of 171 triple therapy+famotidine patients returned for rebiopsy four weeks after completion of treatment. Significantly more triple therapy+omeprazole patients achieved eradication 122 of 125 (97.6%) as assessed by negative urease test, culture, and histological assessment, when compared with 110 of 124 (89%) triple therapy+famotidine patients (p = 0.006; chi 2). There were 30 triple therapy+omeprazole (24%) and 26 triple therapy+famotidine (21%) patients with de novo metronidazole resistant H pylori included in the study. Side effects were mild and infrequent and were comparable in both groups, although pain in duodenal ulcer, gastric ulcer, and oesophagitis patients seemed to subside earlier in those taking omeprazole. Compliance (>95% of drugs taken) was achieved by 98% of patients of both groups. A 12 days regimen of triple therapy with omeprazole is more effective in achieving H pylori eradication than is triple therapy plus famotidine. Use of 20 mg omeprazole twice daily rather than 40 mg famotidine with a 12 day, low dose triple therapy enhances eradication to over 97% whether the H pylori is metronidazole sensitive or resistant.

Anti-Ulcer Agents↗
PubMed1994

The downregulation of GAP-43 is not responsible for the failure of regeneration in freeze-killed nerve grafts in the rat.

Freeze-killed nerve grafts in rats are able to support limited axonal regeneration from severed peripheral nerves, but by 6 weeks postoperation, axonal elongation through the grafts ceases. To find out whether this limited regeneration may be related to GAP-43 expression, 4-cm freeze-killed nerve grafts were attached to the proximal stumps of severed tibial nerves in adult inbred Fischer rats. For comparison, tibial nerve crush, to allow functional regeneration, or section and ligation, which allows only abortive axonal sprouting, were also performed. After survival for 3 or 6 weeks, the lumbar spinal cord and L4 dorsal root ganglia were stained for GAP-43 mRNA. Freeze-killed grafts of 3-8 weeks duration were processed for GAP-43 immunocytochemistry. Three weeks after all three operations, comparable numbers of axotomized spinal motorneurons and primary sensory DRG neurons reexpressed high levels of GAP-43 mRNA. Six weeks after tibial nerve crush, the number of tibial motorneurons and DRG cells expressing GAP-43 mRNA returned to control levels but after section and ligation or freeze-killed nerve grafting many positively stained cells were still visible. GAP-43 immunoreactivity was detectable using immunocytochemistry in many unmyelinated axons which had regenerated into the freeze-killed grafts at all times. Both axonal profiles in contact with Schwann cells and those which lacked such contact were GAP-43 positive. These results suggest that the cessation of axonal regeneration into freeze-killed tibial nerve grafts is not the result of a down-regulation of GAP-43. Furthermore, the presence of high levels of GAP-43 alone is not sufficient to ensure prolonged axonal regeneration.

Animals↗
PubMed1994

Helicobacter pylori reinfection rate, in patients with cured duodenal ulcer.

OBJECTIVE: To determine the reinfection rate of the gastric mucosa in patients previously cured of duodenal ulcers, following the eradication of Helicobacter pylori. Only those remaining H. pylori-negative beyond 12 months of follow-up were studied, to minimize the potential inclusion of patients with H. pylori recrudescence. METHODS: Patients with endoscopically proven duodenal ulcers who had been treated with triple therapy, resulting in documented eradication of H. pylori and cure of the ulcer for at least 4 years, were recalled and had their H. pylori status determined by the 14C-urea breath test. Those found positive for H. pylori underwent endoscopic confirmation of the infection. RESULTS: Of the 94 patients restudied, with a follow-up period range of 48-96 months or a total of 549.8 yr, only two (2.2%) were again H. pylori positive. This gives an effective reinfection rate of 0.36% per patient year. In the two H. pylori-positive patients, one had normal mucosa endoscopically, whereas duodenitis without active ulceration was present in the other. The former was asymptomatic, whereas the latter patient was using ranitidine daily for symptom control. CONCLUSION: In the Australian setting, following cure of duodenal ulcer disease by eradication of H. pylori, subsequent reinfection is an unusual phenomenon. We conclude that efforts aimed at eradication of H. pylori in duodenal ulcer are justified and are worthwhile.

Breath Tests↗
PubMed1994

Use of high efficacy, lower dose triple therapy to reduce side effects of eradicating Helicobacter pylori.

OBJECTIVES: To evaluate two triple-therapy (TT) regimens of colloidal bismuth subcitrate (CBS), metronidazole, and tetracycline HCl in eradicating Helicobacter pylori, with particular attention to the frequency of resulting adverse effects of the two therapies. METHODS: A prospective, randomized controlled trial was conducted in patients with symptoms of dyspepsia who were positive for H. pylori. Subjects received a 14-day course of either 4 x/day therapy of CBS (108 mg), tetracycline HCl (500 mg), and metronidazole (250 mg), or 5 x/day therapy of CBS (108 mg), tetracycline HCl (250 mg), and metronidazole (200 mg). H. pylori status was determined endoscopically by urease test, histology, and culture. Standard questionnaires were administered to determine compliance to treatment and side effects of therapy. RESULTS: H. pylori was eradicated in 196/213 (92%) patients in the 4 x/day group and 202/210 (96%) in the 5 x/day group (p = 0.07). Side effects were significantly less frequent and less severe in the 5 x/day group (p < 0.01). CONCLUSIONS: We conclude that a lower dose, 5 x/day triple therapy treatment of H. pylori is equally efficacious to the standard 4 x/day therapy, but is accompanied by fewer and milder adverse effects.

Abdominal Pain↗
PubMed1993

Q-T interval as predictor of serum calcium level.

To assess whether measurement of the electrocardiograhic (ECG) Q-T interval is a useful predictor of total serum calcium concentration, 15 uraemic patients were studied (10 female, five male; age range, 25-60 years). Resting ECGs were interpreted by three independent observers without knowledge of the patients' identity or serum calcium. Three variants of measurement of the Q-T interval were analysed, of which Q-aTc, the interval from the beginning of the Q-wave to the apex of the T-wave, was the most consistent (coefficient of variation, 2.7%). This also provided the best correlation with measured serum calcium concentration (P < 0.001). When compared to biochemical measurements, the predicted serum calcium concentration was within 95% confidence limits in 14 of the 15 patients studied. However, the wide confidence limits of this technique mean that it cannot be recommended in routine clinical practice.

Adult↗
PubMed1993

A phase I and pharmacokinetic study of intraperitoneal carboplatin and etoposide.

BACKGROUND: We attempted to determine the maximum tolerated dose and toxicity of etoposide (VP-16) when administered in combination with carboplatin (CBDCA) (300 mg m-2) and administered via the intraperitoneal (IP) route. METHODS AND MATERIALS: A total of 26 patients were treated on this trial. CBDCA was administered at a fixed dose of 300 mg m-2) while VP-16 was started at a dose of 200 mg m-2 and escalated at 50 mg m-2 increments. Both agents were mixed together in 2 litres of 5% Dextrose and administered as quickly as possible into the peritoneal cavity. Pharmacokinetic studies were performed at the maximum tolerated dose (MTD). RESULTS: The MTD for this regimen was CBDCA 300 mg m-2 and VP-16 350 mg m-2. Patients > or = 70 years of age or who had received more than six cycles of previous chemotherapy, tolerated this regimen poorly. The MTD for this group of patients was CBDCA 200 mg m-2 and VP-16 50 mg m-2. Neutropenia was the dose limiting toxicity for both groups. The mean peritoneal/plasma peak ratio was 18.3 for CBDCA and 12.7 for VP-16. The pharmacologic advantage (peritoneal/plasma AUC ratio) was 14.9 for CBDCA and 8.8 for VP-16. Although measurable disease was not a requirement for entrance into this study a response rate of 27% was noted in 15 patients with evaluable disease who had ovarian cancer. CONCLUSIONS: A pharmacologic advantage exists for both CBDCA and VP-16 when administered together via the IP route.

Adult↗
PubMed1993

Quantitative analysis of stress fiber orientation during corneal wound contraction.

Previous studies of actin and actin-binding proteins in corneal myofibroblasts suggest the development of a contractile apparatus composed, in part, of F-actin micro-filament bundles, i.e. stress fibers. To better understand the mechanics of wound contraction and the relationship between microfilament bundles and wound closure, we have analyzed the spatial and temporal organization of stress fibers during the process of corneal wound healing. Rabbit corneas (26 eyes) received 6 mm full-thickness, central incisions and were studied at various times for F-actin organization using en bloc (whole cornea) staining with FITC-phalloidin, as well as conventional histological techniques. 3-D datasets (z-series of 40 en face optical sections, 1 micron steps) were collected using the Biorad MRC-600 laser scanning confocal microscope at various regions within the wound. At 7 days, 3-D analysis showed randomly oriented, interconnected F-actin filament bundles (stress fibers). Between 7 and 28 days, stress fibers appeared to organize gradually into planes parallel to the wound surface, with a large population achieving a final orientation nearly parallel to the long axis of the wound. Using Fourier Transform analysis techniques, an orientation index (OI) was calculated to quantitate global fiber orientation at each time point. Analysis of variance demonstrated a significant change (P < 0.001) in overall stress fiber orientation from a random distribution at day 7 to an alignment more parallel to the lateral wound borders at day 28. Overall, these data suggest that stress fibers undergo temporal changes in spatial organization that correlate with wound closure, and that wound closure does not involve the development of previously described contractile or tractional forces aligned directly across the wound.

Actin Cytoskeleton↗