Search PubMed⌕ Search

Biomedical subjects

M C Thomas

Publications and source records attributed to M C Thomas.

At least 91 records · Page 5Linked to original sources
PubMed1996

Multiprimer PCR system for differential identification of mycobacteria in clinical samples.

A novel multiprimer PCR method with the potential to identify mycobacteria in clinical samples is presented. The assay relies on the simultaneous amplification of three bacterial DNA genomic fragments by using different sets of oligonucleotide primers. The first set of primers amplifies a 506-bp fragment from the gene for the 32-kDa antigen of Mycobacterium tuberculosis, which is present in most of the species belonging to the genus Mycobacterium. The second set of primers amplifies a 984-bp fragment from the IS6110 insertion sequence of the bacteria belonging to the M. tuberculosis complex. The third set of primers, derived from an M. tuberculosis species-specific sequence named MTP40, amplifies a 396-bp genomic fragment. Thus, while the multiprimer system would render three amplification fragments from the M. tuberculosis genome and two fragments from the Mycobacterium bovis genome, a unique amplification fragment would be obtained from nontuberculous mycobacteria. The results obtained, using reference mycobacterial strains and typed clinical isolates, show that the multiprimer PCR method may be a rapid, sensitive, and specific tool for the differential identification of various mycobacterial strains in a single-step assay.

Base Sequence↗
PubMed1996

Mucosal cytokine production in small-intestinal bacterial overgrowth.

BACKGROUND: Mucosal production of interferon-gamma, interleukin-6, and tumour necrosis factor-alpha is increased in inflammatory bowel disease and parallels disease activity. Interferon-gamma production is also increased in coeliac disease. Conversely, local cytokine profiles have not been investigated in small-intestinal bacterial overgrowth. This study addressed this issue. METHODS: Eighteen adult subjects were studies with culture of proximal small-intestinal luminal secretion and measurement of luminal interferon-gamma, interleukin-6, and tumour necrosis factor-alpha concentrations by enzyme-linked immunosorbent assay. Small-intestinal histology was assessed by light microscopy. RESULTS: Interferon-gamma, interleukin-6, and tumour necrosis factor-alpha were measurable in proximal small-intestinal luminal secretions of all subjects, even in the absence of light microscopic evidence of enteropathy. Small-intestinal bacterial overgrowth was present in 12 of 18 (66.7%) subjects. Luminal concentrations of neither interferon-gamma nor tumour necrosis factor-alpha differed significantly in subjects with and without small-intestinal bacterial overgrowth (P + 0.06 and P = 1.0, respectively). Conversely, luminal interleukin-6 concentrations were significantly increased in subjects with this disorder (P = 0.02). Multivariate linear regression analysis suggested that colonic-type rather than salivary-type flora mediated this increased interleukin-6 response (P = 0.02 and P = 0.64, respectively). No correlation was found between luminal interleukin-6 and tumour necrosis factor-alpha concentrations, even after the confounding influence of colonic-type bacteria was excluded (P = 0.60). CONCLUSIONS: These findings suggest that increased mucosal production of interleukin-6 occurs in small-intestinal bacterial overgrowth, particularly when the overgrowth flora includes colonic-type bacteria. Conversely, luminal levels of neither interferon-gamma nor tumour necrosis factor-alpha are increased in the circumstance, distinguishing the local cytokine profile in this disorder from those that occur in coeliac disease and inflammatory bowel disease.

Adult↗
PubMed1996

The expression of complement protein 4 and IgG3 in luminal secretions.

BACKGROUND: Factors regulating proximal small-intestinal luminal concentrations of IgG3, the predominant IgG subclass at this site, are unclear. This study determined whether luminal IgG3 concentrations are related to those of complement protein 4 (C4), an acute-phase reactant predominantly derived from local mucosa. METHODS: Proximal small-intestinal luminal and peripheral blood IgG subclass and C4 concentrations were measured by radial immunodiffusion in 30 adult subjects without predisposition to disturbed mucosal immunity. Mucosal C4 immunoreactivity and the presence or absence of small-intestinal bacterial overgrowth were determined in all subjects. Caecal luminal concentrations of IgG3 and C4 were measured in a separate cohort of eight asymptomatic subjects. RESULTS: Proximal small-intestinal luminal C4 and IgG subclass concentrations were not significantly influenced by the presence of absence of small-intestinal bacterial overgrowth (P > 0.2). Nor did plasma C4 levels significantly influence C4 concentrations in small-intestinal luminal secretions (P > 0.2). Mucosal immunoreactivity for C4 was present in every subject. A significant correlation was found between C4 and IgG3 concentrations in proximal small-intestinal luminal secretions (P < 0.0005) and also in caecal secretions (P < 0.05) but not in peripheral blood (P > 0.1). CONCLUSIONS: Common factors, not including the presence or absence of small-intestinal bacterial overgrowth, regulate luminal concentrations of C4 and IgG3. Local investigation is mandatory when assessing mucosal immune mechanisms.

Cecum↗
PubMed1996

Luminal immunity in small-intestinal bacterial overgrowth and old age.

BACKGROUND: The independent influences of small-intestinal bacterial overgrowth and old age on mucosal immunoglobulin production and secretion have not been assessed. This is an important issue, since luminal IgA deficiency may exacerbate small-intestinal bacterial overgrowth, the prevalence of which is high in selected elderly populations. METHODS: Proximal small-intestinal aspirates were obtained from 33 subjects for bacteriologic analysis and measurement of total IgA, IgM, total IgG. IgG subclass, and IgD concentrations. IgA subclasses were measured in 24 unselected subjects. Serum immunoglobulin and salivary IgA concentrations were measured in all subjects. RESULTS: IgA2 and IgG3 were predominant IgA and IgG subclasses in proximal small-intestinal luminal secretions. Luminal concentrations of IgA2 and IgM, but not IgG3 or any other IgG subclass, were significantly increased in small-intestinal bacterial overgrowth, which was present in 19 of 33 (57.6%) subjects. Old age did not influence these levels. Luminal immunoglobulin concentrations did not correlate significantly with either serum or salivary values. IgD was not measureable in proximal small-intestinal secretions. CONCLUSIONS: Increased luminal concentrations of the secretory immunoglobulins, IgA2 and IgM, occur in small-intestinal bacterial overgrowth. Local investigation is mandatory when assessing the mucosal immunopathology of this disorder. Luminal IgG3 is unlikely to be predominantly derived from serum. Old age does not independently influence luminal immunity.

Age Factors↗
PubMed1996

The lactulose breath hydrogen test and small intestinal bacterial overgrowth.

OBJECTIVES: To i) document the sensitivity and specificity of a combined scintigraphic/lactulose breath hydrogen test for small intestinal bacterial overgrowth and ii) investigate the validity of currently accepted definitions of an abnormal lactulose breath hydrogen test based on "double peaks" in breath hydrogen concentrations. METHODS: Twenty-eight subjects were investigated with culture of proximal small intestinal aspirate and a 10-g lactulose breath hydrogen test combined with scintigraphy. Gastroduodenal pH, the presence or absence of gastric bacterial overgrowth, and the in vitro capability of overgrowth flora to ferment lactulose were determined. RESULTS: Sensitivity (16.7%) and specificity (70.0%) of the lactulose breath hydrogen test alone for small intestinal bacterial overgrowth were poor. Combination with scintigraphy resulted in 100% specificity, because double peaks in serial breath hydrogen concentrations may occur as a result of lactulose fermentation by cecal bacteria. Sensitivity increased to 38.9% with scintigraphy, because a single rise in breath hydrogen concentrations, commencing before the test meal reaches the cecum, may occur in this disorder. Sensitivity remained suboptimal irrespective of the definition of small intestinal bacterial overgrowth used, the nature of the overgrowth flora, favorable luminal pH, the presence of concurrent gastric bacterial overgrowth, or the in vitro ability of the overgrowth flora to ferment lactulose. CONCLUSIONS: Definitions of an abnormal lactulose breath hydrogen test based on the occurrence of double peaks in breath hydrogen concentrations are inappropriate. Not even the addition of scintigraphy renders this test a clinically useful alternative to culture of aspirate for diagnosing small intestinal bacterial overgrowth.

Bacterial Infections↗
PubMed1996

Bacteriological method for detecting small intestinal hypomotility.

OBJECTIVE: Small intestinal hypomotility is an important cause of small intestinal bacterial overgrowth, yet assessment of small intestinal motility in this setting is problematic. This study was performed to investigate the validity of a bacteriological method for detecting small intestinal hypomotility. METHODS: Twenty-five subjects without previous gastric surgery were studied with (i) concurrent bacteriological analyses of fasting saliva and gastric and proximal small intestinal aspirates, (ii) measurement of gastric pH, and (iii) scintigraphic assessment of small intestinal transit rates of a liquid test meal. The reproducibility of bacteriological analyses of saliva and small intestinal secretions was determined in 12 subjects. RESULTS: Serial bacteriological analyses of saliva and proximal small intestinal secretions yielded reproducible results over time periods of up to 1 month. Eleven subjects were deemed to harbor Enterobacteriaceae of nonsalivary origin in proximal small intestinal secretions. Orocaecal transit, but not gastric emptying, of a liquid test meal was significantly delayed in this group (p = 0.002 and p = 0.84, respectively), suggesting the presence of small intestinal hypomotility. Impaired gastric acidity unlikely confounded assessment of the origin of small intestinal Enterobacteriaceae in any instance. CONCLUSIONS: The presence of Enterobacteriaceae of nonsalivary origin in proximal small intestinal secretions may be taken to reflect the presence of small intestinal hypomotility. The presence of impaired gastric acidity does not confound this approach. Because small intestinal intubation and culture of aspirate are required anyway to accurately diagnose small intestinal bacterial overgrowth, the simple addition of concurrent bacteriological analysis of saliva may allow small intestinal hypomotility to be detected at the same time as the presence or absence of small intestinal bacterial overgrowth itself is established, thus streamlining the investigation of subjects for this disorder and its possible causes.

Bacterial Infections↗
PubMed1995

Factors influencing the 1-g 14C-D-xylose breath test for bacterial overgrowth.

OBJECTIVES: To document the sensitivity of the 1-g 14C-D-xylose breath test for bacterial overgrowth and to investigate luminal and nonluminal factors that may influence breath 14CO2 levels and impact on the clinical utility of this test. METHODS: Thirty-five adult subjects were investigated for bacterial overgrowth by culture of gastric and small intestinal aspirates and by a 1-g 14C-D-xylose breath test. Body weight, gastroduodenal pH and the in vitro capability of overgrowth flora to ferment D-xylose were assessed. Serial breath 14CO2 levels were also recorded before and after the resolution of malabsorption in a subject with celiac disease to determine the importance of postabsorptive metabolism of this substrate. RESULTS: Gastric and small intestinal bacterial overgrowth were present in 19/35 (54.3%) and 21/35 (60.0%) subjects, respectively. The positivity rate of culture of aspirate exceeded that of the 1-g 14C-D-xylose breath test. Endogenous CO2 production independently influenced breath 14CO2 levels. After excluding this influence, sensitivity of the 1-g 14C-D-xylose breath test for gastric bacterial overgrowth or small intestinal bacterial overgrowth was poor, even when overgrowth with specific "marker organisms" was considered. Poor sensitivity could not be explained by unfavorable luminal pH. Overgrowth flora were proven capable of in vitro D-xylose fermentation in 81.8% of subjects. Systemic and/or colonic metabolism of 1-g 14C-D-xylose appear to be important factors influencing results of the 1-g 14C-D-xylose breath test, especially in partial gastrectomy subjects. CONCLUSIONS: The 1-g 14C-D-xylose breath test is not a suitable alternative to culture of aspirate for the investigation of subjects for bacterial overgrowth.

Aged↗
PubMed1994

An outbreak of leptospirosis on a single farm in east Otago.

AIMS: To present an outbreak of leptospirosis on a dairy farm which had an unvaccinated herd. METHODS: Nine people working or living on the farm were tested for the presence of leptospira antibody by the microscopic agglutination test. Nineteen cows randomly selected, were also tested. RESULTS: Three human cases and one suspected case were detected over a one month period (December 1992-January 1993). Seventy-nine percent of the dairy herd tested had serological evidence of infection with L hardjo. CONCLUSIONS: Leptospirosis continues to be a major occupational problem in New Zealand. The importance of herd vaccination and the use of protective clothing during milking is emphasised.

Adolescent↗
PubMed1994

Characterization of SPf(66)n: a chimeric molecule used as a malaria vaccine.

SPf66 is a chemically synthesized 45 amino acid peptide derived from fractions of four different proteins of Plasmodium falciparum (83, 55 and 35 kDa and CS, the circumsporozoite protein) that elicits a protective immune response against malaria. In this paper we show the characterization of the SPf(66)n in batch 9 to be used in a field trial in young children at Ifakara in Tanzania. The analysis of SPf(66)n indicates that it is highly soluble in water and that the amino acid composition and sequence corresponds to that designed for the synthesis of the polypeptide. The packed product has a molecular weight ranging from 10 to 25 kDa. It is pure, free of metallic contaminants, atoxic and stable at 4 degrees C. The antibodies raised against this product in rabbits recognize the individual antigenic determinants of the molecule and the native epitopes of merozoites.

Amino Acid Sequence↗
PubMed1993

Bats, cats, and rabies in an urban community.

Bats are the primary vectors of rabies in humans in the United States. In the urban environment they generally are found within buildings where they may bite people or be attacked by cats or dogs. Given the high probability that any bat that bites a person may be rabid, antirabies prophylaxis should be administered as soon as possible after the incident. This should not be delayed pending laboratory results on the bat. Children should be taught to avoid contact with moribund bats. Cats are more likely to be involved with rabid bats than dogs, but they are less likely to be vaccinated against rabies. The occasional rabid cat in an urban community may have acquired its infection from a bat. Therefore, it is vital that communities enforce rabies vaccination for cats as well as dogs.

Animals↗
PubMed1993

Educating a patient with dental implants.

A functional dentition can be restored for edentulous and partially edentulous patients through the placement of dental implants. Dental assistants have a significant role in the education of implant patients so that meticulous oral self-care can be accomplished. Only through the combined team efforts of the dental office staff and patients themselves will the continued success of dental implantology be insured.

Dental Assistants↗
PubMed1992

Effects of ethanol, acetaldehyde and cholesteryl esters on pancreatic lysosomes.

Recent studies indicate that altered lysosomal function may be involved in the early stages of pancreatic injury. Chronic consumption of ethanol increases rat pancreatic lysosomal fragility. The aim of this study is to determine whether the lysosomal fragility observed after chronic ethanol consumption is mediated by ethanol per se, its oxidative metabolite acetaldehyde or cholesteryl esters (substances which accumulate in the pancreas after ethanol consumption). Pancreatic lysosomes from chow fed rats were incubated for 30 minutes at 37 degrees C with ethanol, acetaldehyde or phosphatidylcholine vesicles containing cholesteryl oleate. Lysosomal stability was then assessed by determination of: (a) Latency--that is, the per cent increase in lysosomal enzyme activity after addition of Triton X-100 and (b) Supernatant activity--that is, the proportion of lysosomal enzyme remaining in the supernatant after resedimentation of lysosomes. Acid phosphatase, N-acetyl glucosaminidase, beta-glucuronidase and cathepsin B were assayed as lysosomal marker enzymes. Lysosomes incubated with homogenising medium alone or equivalent volumes of phosphatidylcholine vesicles without cholesteryl oleate were used as controls. Cholesteryl oleate at concentrations of 15 and 20 mM increased pancreatic lysosomal fragility as shown by decreased latency and increased supernatant enzyme. In contrast, ethanol (150 mM) and acetaldehyde (5 mM) had no effect on lysosomal stability in vitro. These results suggest that increased pancreatic lysosomal fragility observed with ethanol may be mediated by cholesteryl ester accumulation rather than by ethanol or acetaldehyde.

Acetaldehyde↗
PubMed1991

Vinyl chloride related hepatic angiosarcoma in a polyvinyl chloride autoclave cleaner in Australia.

OBJECTIVE: To present the first case of vinyl chloride related hepatic angiosarcoma in Australia. CLINICAL FEATURES: A 51-year-old male caucasian former polyvinyl chloride autoclave cleaner in an Australian chemical plant developed hepatic angiosarcoma, presenting 15 years after his last exposure to vinyl chloride monomer. OUTCOME: He developed encephalopathy and died in oliguric renal failure 21 days after admission to hospital. CONCLUSION: Hepatic angiosarcoma may develop in other workers similarly exposed.

Australia↗