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Biomedical subjects

J Martin

Publications and source records attributed to J Martin.

At least 487 records · Page 27Linked to original sources
PubMed1995

Pseudomembranous colitis following clarithromycin therapy.

OBJECTIVE: To describe the association of clarithromycin, used to treat Helicobacter pylori infection and duodenal ulceration, with pseudomembranous colitis in two patients. SETTING: St Mary's Hospital, London, UK. PATIENTS: Two female patients aged 77 and 78 years, admitted with duodenal ulceration and H. pylori infection. INTERVENTION: Clarithromycin (500 mg three times daily) was administered concurrently with omeprazole (40 mg once daily). OUTCOME MEASURES: After an initial improvement in symptoms both patients experienced persistent Clostridium difficile-associated diarrhoea. CONCLUSIONS: High-dose clarithromycin should be used with caution for the treatment of H. pylori infection associated with gastroduodenal ulceration. The drug may induce antibiotic-associated colitis which can lead to morbidity and mortality, particularly in the elderly.

Aged↗
PubMed1995

Human beta-globin gene polymorphisms characterized in DNA extracted from ancient bones 12,000 years old.

Analyzing the nuclear DNA from ancient human bones is an essential step to the understanding of genetic diversity in current populations, provided that such systematic studies are experimentally feasible. This article reports the successful extraction and amplification of nuclear DNA from the beta-globin region from 5 of 10 bone specimens up to 12,000 years old. These have been typed for beta-globin frameworks by sequencing through two variable positions and for a polymorphic (AT) chi (T) gamma microsatellite 500 bp upstream of the beta-globin gene. These specimens of human remains are somewhat older than those analyzed in previous nuclear gene sequencing reports and considerably older than those used to study high-copy-number human mtDNA. These results show that the systematic study of nuclear DNA polymorphisms of ancient populations is feasible.

Archaeology↗
PubMed1995

[Impact on the quality of life of respiratory symptoms and airway obstruction in an agricultural population].

Respiratory diseases are known to have consequences on health status. The objective of this study was to assess the quality of life of subjects with obstructive respiratory disorders coming for preventive medicine examinations. We conducted a study on a sample of adults living in agricultural areas (n = 1,235). We used two questionnaires: a respiratory questionnaire and the Nottingham Health Profile (NHP), which is a questionnaire designed to capture self-reported morbidity. It has been recently validated in french. Each subject performed a pulmonary function test on a portable spirometer to separate lung function obstructive abnormalities. Statistical analysis was realized by non parametric test. The number of positive responses (which shows bad health status) and the scores of the six dimensions are higher in females than males. According to sex and smoking habits, cough and chronic bronchitis are responsible for bad scores of health profile (for the total number of positive responses and the scores of each dimension). In case of airway obstruction, there is no major consequences on health profile. Subjective health measurements are interesting tools in subjects with non-chronic diseases. They can be associated with medical questionnaires because they give complementary inquiries.

Adolescent↗
PubMed1994

Identification of non-catalytic conserved regions in xylanases encoded by the xynB and xynD genes of the cellulolytic rumen anaerobe Ruminococcus flavefaciens.

xynB is one of at least four genes from the cellulolytic rumen anaerobe Ruminococcus flavefaciens 17 that encode xylanase activity. The xynB gene is predicted to encode a 781-amino acid product starting with a signal peptide, followed by an amino-terminal xylanase domain which is identical at 89% and 78% of residues, respectively, to the amino-terminal xylanase domains of the bifunctional XynD and XynA enzymes from the same organism. Two separate regions within the carboxy-terminal 537 amino acids of XynB also show close similarities with domain B of XynD. These regions show no significant homology with cellulose- or xylan-binding domains from other species, or with any other sequences, and their functions are unknown. In addition a 30 to 32-residue threonine-rich region is present in both XynD and XynB. Codon usage shows a consistent pattern of bias in the three xylanase genes from R. flavefaciens that have been sequenced.

Amino Acid Sequence↗
PubMed1994

Transfusion of one HLA-DR antigen-matched blood to potential recipients of a renal allograft.

Patients awaiting a renal transplant were given 1 HLA-DR antigen-matched blood in order to compare the sensitization and graft outcome of these patients with those of control patients, who had been given random blood before transplantation. No differences in sensitization, measured by the formation of HLA antibodies, or in graft survival were found between the 2 groups. However, the incidence of rejection episodes was significantly reduced in the patients who received blood matched for 1 HLA-DR antigen compared with the patients who received random blood.

Blood Grouping and Crossmatching↗
PubMed1994

Identification of eight mutations and three sequence variations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

To determine cystic fibrosis (CF) defects in a sample of 224 non-delta F508 CF chromosomes, we used denaturing gradient gel multiplex analysis of CF transmembrane conductance regulator gene segments, a strategy based on blind exhaustive analysis rather than a search for known mutations. This process allowed us to detect 11 novel variations comprising two nonsense mutations (Q890X and W1204X), a splice defect (405 + 4 A-->G), a frameshift (3293delA), four presumed missense mutations (S912L, H949Y, L1065P, Q1071P), and three sequence polymorphisms (R31C or 223 C/T, 3471 T/C, and T1220I or 3791 C/T). We describe these variations, together with the associated phenotype when defects on both CF chromosomes were identified.

Base Sequence↗
PubMed1994

Molecular chaperones in cellular protein folding.

The discovery of 'molecular chaperones' has dramatically changed our concept of cellular protein folding. Rather than folding spontaneously, most newly synthesized polypeptide chains seem to acquire their native conformation in a reaction mediated by these versatile helper proteins. Understanding the structure and function of molecular chaperones is likely to yield useful applications for medicine and biotechnology in the future.

Bacteria↗
PubMed1994

Malformations persist after metamorphosis of Xenopus laevis tadpoles exposed to Ni2+, Co2+, or Cd2+ in FETAX assays.

This study was performed to determine whether malformations induced in Xenopus laevis embryos by exposures to divalent nickel, cobalt, or cadmium chlorides in FETAX assays persist after the tadpoles undergo metamorphosis to juvenile frogs. Embryos were exposed for four days to EC50 concentrations of Ni2+, Co2+, or Cd2+ under the standard conditions of FETAX assays; thereafter, the exposures were discontinued and the tadpoles were kept in aquaria through metamorphosis. Controls were treated similarly, without exposure to metals. At 13 weeks of age, surviving frogs were killed and examined for malformations. Control and metal-exposed groups of Xenopus did not differ significantly in their median ages at metamorphosis, mean body weights, or survival at 13 weeks. Overall incidences of malformations found in Ni(2+)-, Co(2+)-, or Cd(2+)-exposed frogs at 13 weeks of age were 55, 40, and 51%, respectively (P < 0.01 vs. 3% in controls). The malformations of metal-exposed frogs included retinal depigmentation, diastematomyelia, scoliosis, kyphosis, phocomelia, sacro-pelvic and hind-limb deformities, and dysplasia of the heart, kidney, ovary and gut.

Abnormalities, Drug-Induced↗
PubMed1994

Calcineurin immunoreactivity in Alzheimer's disease.

Aberrant phosphorylation of tau is linked to formation of the paired helical filaments (PHF) seen in Alzheimer's disease. Protein kinases such as mitogen-activated protein kinase, and calcium-regulated protein kinases may, in part, be responsible for addition of phosphate groups to serine residues of PHFtau; however, less is known concerning the phosphatases which regulate tau. In this report, we used several well-characterized antibodies to document calcineurin immunoreactivity in brain tissue from patients with Alzheimer's disease. We now report that levels of immunoreactive calcineurin are not significantly altered in neocortex and cerebellum of Alzheimer's patients relative to similar regions of age-matched controls. Immunocytochemical studies indicated that calcineurin immunoreactivity was present in dendrites and perikarya of many different neuronal populations in both control and Alzheimer brain. When specific antibodies against PHFtau were used in double-labeling experiments with anti-calcineurin antibodies, calcineurin immunoreactivity was seen in association with neurofibrillary tangles. However, calcineurin was not seen in all tangle bearing neurons. These data suggest that calcineurin levels per se are not significantly altered in Alzheimer's disease, but that calcineurin is distributed around some neurofibrillary tangles and may play a role in regulation of tau phosphorylation.

Aged↗
PubMed1994

Serum levels of soluble immune factors and pathogenesis of chronic hepatitis C, and their relation to therapeutic response to interferon-alpha.

To test the role of immune reactivity in the pathogenesis of hepatitis C, serum soluble immune factors were measured in a cohort of 57 patients with chronic hepatitis C, and in 20 healthy subjects. Levels of interleukin-1 beta, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and interleukin-6 were detected in some, but not all, HCV patients and were in general undetectable in healthy subjects. Patients had significantly higher concentrations of neopterin (P = 0.0026), beta 2-microglobulin (P = 0.046), soluble interleukin-2 receptor (P = 0.021), and soluble CD8 (P < 0.039), than healthy controls; conversely, interferon-gamma levels were significantly lower (P = 0.023). Significant correlations were observed between beta 2-microglobulin concentration and Knodell's index (r = 0.638, P = 0.00045), the score of piecemeal necrosis (r = 0.572, P = 0.0023), and the degree of fibrosis (r = 0.527, P = 0.0056). Interleukin-2 levels correlated significantly with Knodell's index (r = 0.412, P = 0.037), and the degree of lobular cytolysis (r = 0.389, P = 0.048). According to therapeutic outcome, pretreatment levels of soluble CD8 were only significantly elevated (P = 0.042) in patients with a sustained biochemical response. On interferon-alpha treatment, the levels of beta 2-microglobulin, neopterin, and soluble interleukin-2 receptor increased significantly (P < 0.05), irrespective of therapy outcome. In summary, HCV patients have an altered immune reactivity that might play a role in the pathogenesis of chronic hepatitis C, and might influence the therapeutic outcome to interferon-gamma.

Adult↗
PubMed1994

Further development of a transcervical technique for artificial insemination in sheep using previously frozen semen.

A transcervical technique (the Guelph System for transcervical AI) was used to inseminate 2060 ewes on 65 farms (average 31 ewes, range 5 to 107) in Ontario, Canada, from October 1990 to September 1992, using previously frozen semen. Estrus was synchronized using progestagen pessaries and PMSG with median inseminations done at 54 h from pessary removal. Maiden ewes were not included. Only ewes in which the cervix could be penetrated were inseminated with 150 million spermatozoa per insemination. A total of 1809 were penetrated and inseminated (penetration rate 87.8%). Success of penetration increased from 76.3% in the first 500 ewes to 97.9% in the last 500 (P=0.01). Cervical penetration was more successful in ewes in the accelerated lambing program (92.3%, average 3.1 mo since the previous lambing) than those in the annual lambing program (82.4%, average 7.0 mo since the previous lambing; P=0.06). The lambing rate for ewes bred during the combined traditional breeding seasons (Fall of 1990, 1991, 1992) was 50.7% compared to 24.4% for ewes bred at other periods (P=0.00001). The average time required for handling and insemination decreased from 8.62 min in the first 500 ewes to 3.62 min in the last 500 ewes. The Guelph System for Transcervical AI was found to be successful for cervical penetration in most ewes. Penetration success was affected by period since the last lambing and by inseminator experience. The lambing rate was higher for ewes bred during the traditional Fall breeding seasons than during other times of the year.

Journal Article↗
PubMed1994

Isolation and characterization of the gene encoding histone H2A from Trypanosoma cruzi.

In the present paper we report the isolation and characterization of the sequence of two genomic DNA fragments coding for the histone H2A of Trypanosoma cruzi. An analysis of the predicted amino acid sequence shows the presence of the amino-terminal motif characteristic of the H2A histones proteins and the Lys-Lys motif reported to be the site for the ubiquitin attachment. Southern blots of total parasite DNA probed with the H2A sequence suggested that the T. cruzi histone H2A gene is encoded in two independent gene clusters. The molecular karyotyping of the parasite indicated that these two clusters locate in a single chromosome of about 700 kb in length. The T. cruzi H2A mRNA is polyadenylated as are the basal histone mRNAs of higher eukaryotes and the histone mRNAs of yeast. By polymerase chain reaction amplification and sequencing and by S1 mapping we determined respectively the 5' and 3' end of the gene showing that the miniexon is added to the mRNA 71 nucleotides upstream of the ATG initiation codon and that the polyadenylation site locates in nucleotide position 773-775 close to invert repeats.

Amino Acid Sequence↗
PubMed1994

Self-presentation in everyday interactions: effects of target familiarity and gender composition.

This study examined people's self-presentation motives in unstructured, everyday social interaction as a function of participants' gender similarity to, and general familiarity with, the targets of their self-presentations. Participants maintained a variant of the Rochester Interaction Record for 1 week. For every interaction that lasted 10 min or more, they rated the degree to which they wanted to make each of 4 impressions (likable, competent, ethical, and attractive), how much they thought about the impressions others in the interaction formed of them, and how nervous they felt in the interaction. In general, participants' self-presentational motives were lower in interactions with highly familiar people of their own sex than they were either in interactions with less familiar people of their sex or in interactions with people of the other sex regardless of familiarity. When participants' interactions with only their 3 most familiar interactants were examined, self-presentational concerns decreased with familiarity in same-sex interactions but increased with familiarity in cross-sex interactions.

Analysis of Variance↗