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Biomedical subjects

M J David

Publications and source records attributed to M J David.

At least 19 recordsLinked to original sources
PubMed2002

Risk management of international trade: emergency preparedness.

Emergency preparedness and management are among the most important and critical issues facing animal health in the world today. The goals of a country for an animal health emergency management (AHEM) system should include the following: --being prepared to detect and manage an outbreak of a foreign animal disease --preventing the introduction of foreign and emerging animal pathogens --having an appropriate response system for control and eradication of the disease --having a system for recovery from animal health emergencies, including natural disasters. An AHEM system can no longer be limited to a single organisation within a country. In the event of a serious threat to the animal agriculture of a country, broader and more comprehensive participation is required. If not properly planned for, animal health emergencies can rapidly become national disasters. Therefore, it is essential that the central government of a country work towards these goals through partnerships with other Federal and State/Provincial/District organisations, academic institutions and national animal industries.

Animal Diseases↗
PubMed1999

Occurrence of monosialosyl pentahexaosylceramide GalNAc-GM1 as specific tumor-associated ganglioside of human head and neck squamous cell carcinomas.

In a recent study of the ganglioside profiles of human head and neck squamous cell carcinomas versus normal tissue, one unidentified GX ganglioside was found exclusively in tumor extracts, migrating between GM1 and GD3 by thin-layer chromatography. To determine the chemical structure of this ganglioside which accounted for 3-8% of the total gangliosides, the lipid samples were pooled and separated by high-pressure liquid chromatography to obtain individual ganglioside species purified to homogeneity. The tumor-associated GX ganglioside was analyzed by gas-liquid chromatography, mass spectrometry and immunostaining on thin-layer plates with mouse monoclonal antibodies after enzymatic cleavage. The data allowed the identification of GX ganglioside as GalNAc-GM1 that has been reported as a very minor brain ganglioside in humans. Thus, GalNAc-GM1 is a specific tumor-associated ganglioside in human head and neck squamous cell carcinomas that could be potentially valuable for clinicians.

Carcinoma, Squamous Cell↗
PubMed1998

Analysis of glycosphingolipids of human head and neck carcinomas with comparison to normal tissue.

Glycosphingolipids of head and neck carcinomas from six tumor-bearing patients were analyzed and compared to those of normal tissue from similar areas. The total glycosphingolipid content and the lipid-bound sialic acid were much higher in carcinomas than in normal tissue. Major neutral glycolipids were glucosylceramide, lactosylceramide, trihexosylceramide and paragloboside. Sulfatides were seen only in extracts from normal tissue which also showed a rather simple ganglioside pattern with #GM3 and GD3 as major species, whereas tumors showed additional species such as GM2 and GD2, along with a strong increase in LM1, GM1, GD1a and GT1b.

Biomarkers, Tumor↗
PubMed1996

Cloning and sequencing of an ovine interleukin-5 cDNA.

Interleukin-5 (IL-5) is a T-cell derived cytokine which stimulates eosinophil production and activation in human, mice and sheep. IL-5 is active as a growth factor for mouse but not human B cells. The role of IL-5 on ruminant B cells has not been clearly defined. By hybridisation with human IL-5 cDNA, the ovine IL-5 gene was isolated from a liver genomic library. The IL-5 cDNA was obtained by reverse-transcriptase PCR using primers designed from the 5' and 3' coding sequence derived from the ovine IL-5 gene. The sequences of the cDNA shows that there is 79% and 73% nucleotide homology with the human and mouse sequences. The ovine IL-5 cDNA encoded a protein of 132 amino acids and the level of amino acid homology with human and mouse IL-5 is 64% and 56%, respectively. Two cysteine residues are conserved in ovine, human and mouse IL-5. There are two potential N-linked glycoyslation sites in ovine IL-5.

Amino Acid Sequence↗
PubMed1995

Expression, biological activity and kinetics of production of recombinant ovine TNF-alpha.

Ovine tumour necrosis factor-alpha (OvTNF-alpha) was cloned by reverse transcription-polymerase reaction using RNA isolated from lipopolysaccharide (LPS)-stimulated alveolar macrophages and primers based on the human TNF-alpha cDNA sequence. An expression vector carrying the coding sequence of the mature form of ovine TNF was constructed. The recombinant Ov-TNF alpha (rOvTNF-alpha) was expressed as a glutathione-S-transferase (GST) fusion protein. It was cleaved with thrombin to yield rOvTNF free of the GST moiety. Growth at a lower temperature of 30 degrees C and use of Escherichia coli strains AM207, AM305, E392 and NM522 did not improve the recovery of rOvTNF-alpha from the soluble fraction to a significant extent. Purification of recombinant proteins was achieved rapidly and easily by affinity chromatography using glutathione-Sepharose. Yields of pure rOvTNF-alpha achieved in E. coli JM109 and AM207 were approximately 1 mg L-1. Both rOvTNF-alpha and recombinant human TNF-alpha (rhTNF-alpha) exerted cytotoxicity on L929 cells. However, rOvTNF-alpha but not rhTNF-alpha stimulated proliferation of ovine thymocytes. Maximum levels of TNF-alpha mRNA expression by LPS-stimulated ovine alveolar macrophages were detected at approximately 4 h post-stimulation.

Animals↗
PubMed1995

Gangliosides from normal and osteoarthritic joints.

A decrease in all major gangliosides, contrasting with a marked increase in the GM3 third band (3B-GM3), has been demonstrated in osteoarthritic fibrillated cartilage. We found the 3B-GM3 in osteoarthritic fibrillated, grossly intact and osteophytic human cartilage, but it was undetectable in pig and bovine cartilage, bone, synovium, synovial fluid white cells, erythrocytes, and various extracellular tissues. We made a similar finding with lactosyl ceramide, the GM3 neutral glycolipid precursor. The search for an antibody against the 3B-GM3, as a possible specific antigenic marker of osteoarthritis (OA), was unsuccessful. However, an antibody against a molecule very close to 3B-GM3 on high performance thin layer chromatography, which will probably be identified as a glycosylphosphatidylinositol, was found in the serum of some patients with OA.

Animals↗
PubMed1993

Shedding of GD2 ganglioside in patients with retinoblastoma.

Retinoblastoma is a rare tumor of the young child with an intraocular localization that leads to certain problems of diagnosis. With the aim of defining a biochemical marker--which is still lacking for this disease--the gangliosides of a pool of fresh retinoblastoma tumors were analyzed. The ganglioside pattern was shown to have GM3, GM2, GM1, GD3, GD2, GD1b and GT1b as the major components. The occurrence of a high concentration of GD2 in the tumors led us to investigate the possibility of changes in the level of GD2 in the sera of retinoblastoma patients, using quantitative immunostaining with GD2-specific mouse monoclonal antibodies (MAbs). In 9 out of 10 tumor-bearing patients, the serum level of GD2 ganglioside was significantly higher than the average value found in normal individuals. A 2-year follow-up of patients showed that successful treatment resulted in a rapid decrease in the serum level of GD2 down to the normal range, from which a subsequent elevation was seen only in relapsing patients. Although the clinical study needs further development, the results obtained to date suggest that GD2 is shed in the serum of tumor-bearing patients and that the level of GD2 could be a potential serum marker of human retinoblastoma.

Child, Preschool↗
PubMed1993

Characterization of gangliosides from normal and osteoarthritic human articular cartilage.

OBJECTIVE: Glycosphingolipids (GSLs) are biologically active molecules in the physiology and pathology of cells. Since changes in GSLs might be associated with the impaired metabolism of articular cartilage in osteoarthritis (OA), we investigated gangliosides from normal and OA human cartilage. METHODS: OA and control cartilage was obtained from patients with hip OA and femoral neck fracture, respectively. Gangliosides were extracted and quantified by determining their lipid-bound sialic acid concentration. Major gangliosides were identified by immuno-detection on thin-layer plates, purified by high performance liquid chromatography, and analyzed for their carbohydrate, fatty acid, and long-chain base composition. RESULTS: The total ganglioside content of OA cartilage was decreased by 40% (per mg of DNA). Major gangliosides, GM3 and GD3, separated into 3 on thin-layer chromatography bands. All were decreased except for the lowest migrating band of GM3, which was increased 5-fold. This ganglioside had the same carbohydrate moiety and fatty acids as the other two, but differed by a long-chain base composed mainly of C20-sphingosine. CONCLUSION: OA cartilage is characterized by a decrease in all gangliosides except GM3, which demonstrates a large increase in the lowest band. These results indicate that there are changes in the biochemical composition of chondrocyte membranes in OA. The causes and roles of these changes remain to be determined.

Aged↗
PubMed1993

Role of egg consumption in sporadic Salmonella enteritidis and Salmonella typhimurium infections in Minnesota.

The incidence of Salmonella enteritidis infections has increased in the eastern United States, and consumption of undercooked eggs has been associated with outbreaks of S. enteritidis. In Minnesota, the incidence of S. enteritidis infections doubled from 1980 to 1990; however, no egg-associated outbreaks were identified. A case-control study was conducted to examine potential exposures for S. enteritidis and Salmonella typhimurium infections in Minnesota adults. Sporadic cases of S. enteritidis (odds ratio [OR], 5.2; 95% confidence interval [CI], 1.9-14.2; P = .003) and S. typhimurium infection (OR, 2.4; CI, 1.1-5.5; P = .03) were more likely to have consumed undercooked eggs or egg-containing foods during the 3 days before onset of illness compared to a similar reference period for controls. In addition, the extent to which eggs were cooked was directly associated with illness (chi 2 test for trend, P < .001). These findings demonstrate that eggs are important vehicles for S. enteritidis and S. typhimurium, even in the absence of recognized outbreaks.

Adolescent↗
PubMed1992

Effect of non-steroidal anti-inflammatory drugs (NSAIDS) on glycosyltransferase activity from human osteoarthritic cartilage.

The effect of non-steroidal anti-inflammatory drugs (NSAIDs) on the activity of glycosyltransferases required for the synthesis of the polysaccharide chains of proteoglycans, was studied in human osteoarthritic cartilage in vitro. Using exogenous acceptors, salicylate and indomethacin suppressed the activity of glucuronyl- and xylosyltransferases in a concentration-dependent manner, but had little effect on N-acetylgalactosaminyl- and galactosyltransferases. When used at a concentration derived from the values found in the synovial fluid, salicylate, indomethacin and chloroquine significantly suppressed the activity of glucuronyl- and xylosyltransferases, while tiaprofenic acid, paracetamol (acetaminophen), floctafenine, ketoprofen, ibuprofen and tenoxicam had no effect on the enzymes. An alteration of some glycosyltransferases could explain the reported suppressive effect of some NSAIDs on cartilage proteoglycan synthesis.

Aged↗
PubMed1991

Intra-articular steroids: confounder of clinical trials.

The effect of intra-articular (i-a) steroid injection on ESR and C-reactive protein (CRP) in rheumatoid arthritis (RA) was investigated. One week following injection of 1 or 2 knees there was a significant fall in ESR (p less than 0.0001) and CRP (p less than 0.01) in a cohort of 20 RA patients. The mean drop for both ESR and CRP was 46%. This effect lasted over a variable period up to 6 months. A survey of 50 published drug efficacy studies in RA revealed that, while 44 used ESR and 20 CRP as efficacy measures, 37 neither excluded nor recorded i-a steroid injections during the study. Steroid injections were excluded in 8 studies and recorded in 5, being used as an outcome measure in 2 of these. It is recommended that the frequency with which i-a injections are used in drug efficacy studies is reported and that they are avoided in the 3 months preceding an outcome measurement if ESR or CRP are being used as outcome measures.

Aged↗
PubMed1991

Nucleotide sequence of ovine macrophage interleukin-1 beta cDNA.

We have cloned and sequenced the cDNA for the coding region of ovine alveolar macrophage interleukin-1 beta. At the nucleotide level, the ovine cDNA shares 95, 74 and 71% homology with the bovine, human and murine cDNA equivalents or homologs. Comparison at the amino acid level revealed 95% homology with bovine IL-1 beta and approximately 57% with the human and murine homologs.

Amino Acid Sequence↗
PubMed1989

Tumor size-dependent elevations of serum gangliosides in patients with head and neck carcinomas.

Serum gangliosides were studied in 100 patients with benign or tumoral head and neck lesions. Whereas very few changes over the normal level were noticed in benign cases, 78% of patients with head and neck carcinomas had a significant elevation of serum gangliosides, mostly accounted for by GM3 and GD3. Such an increase was correlated with the observed tumor size, and the level of serum gangliosides returned to normal within one month after surgery. Follow-up of patients showed that further elevations of serum gangliosides were associated with relapses.

Biomarkers, Tumor↗
PubMedDate not supplied

A set of glycoproteins recognized by A2B5 antibody with major bands at 55 and 76 kDa is overexpressed in human head and neck squamous cell carcinomas.

A2B5 antibody was found to strongly label frozen sections of human head and neck squamous cell carcinomas. The low amount of glycolipids (c-series gangliosides and sulfatides) purified from the same tumors and reactive with A2B5 by immunostaining on thin-layer plates could not account for the high level of tissue labeling. Proteins were extracted from both normal tissues and squamous cell carcinomas and analyzed by Western blot with A2B5 antibody on PVDF membranes. The antibody was found to stain a set of glycoproteins with two major bands at 55 and 76 kDa present in normal tissues and overexpressed in carcinomas. Staining was abolished by prior treatment of the PVDF membranes either with Arthrobacter ureafaciens neuraminidase or with a solution of 10 mM periodate that is known to destroy carbohydrates. Our results show that the carbohydrate epitope recognized by A2B5 antibody can be displayed by both glycolipids and glycoproteins.

Antibodies, Monoclonal↗
PubMedDate not supplied

Occurrence of Salmonella enteritidis in the U.S. commercial egg industry: report on a national spent hen survey.

In order to estimate the prevalence and distribution of Salmonella enteritidis in U.S. commercial egg-production flocks, a survey of spent laying hens was conducted over a 3-month period. Seven of the 10 largest spent-hen processing plants in the United States participated. Ceca were sampled twice weekly from birds presented for slaughter at these plants. Samples were cultured for Salmonella and S. enteritidis, and S. enteritidis isolates were phage-typed. Overall, 23,431 pooled cecal samples were collected from a total of 406 layer houses. Salmonella (any serotype) and S. enteritidis were recovered from 24% and 3% of the pooled samples, respectively. The distribution of S. enteritidis phage types was consistent with data reported by others. Regionally, the estimated prevalence of S. enteritidis-positive houses (i.e., at least one positive sample found in a house) for the Northern, Southeastern, and Central/Western regions was 45%, 3%, and 17%, respectively. Overall, the prevalence of Salmonella-positive houses was 86%.

Abattoirs↗