Search PubMed⌕ Search

Biomedical subjects

J M Watson

Publications and source records attributed to J M Watson.

At least 163 records · Page 9Linked to original sources
PubMed1991

The X chromosome of marsupials shares a highly conserved region with eutherians.

Ten genes, located on the long arm of the human X chromosome, were mapped in several marsupial species by somatic cell analysis and in situ hybridization. All were located on the X chromosome in each species. We conclude that the long arm of the human X chromosome represents a highly conserved region that formed part of the X chromosome in a therian ancestor 120-150 million years ago, before the mammalian infraclasses diverged.

Animals↗
PubMed1991

Genetic Diversity among Rhizobium leguminosarum bv. Trifolii Strains Revealed by Allozyme and Restriction Fragment Length Polymorphism Analyses.

Allozyme electrophoresis and restriction fragment length polymorphism (RFLP) analyses were used to examine the genetic diversity of a collection of 18 Rhizobium leguminosarum bv. trifolii, 1 R. leguminosarum bv. viciae, and 2 R. meliloti strains. Allozyme analysis at 28 loci revealed 16 electrophoretic types. The mean genetic distance between electrophoretic types of R. leguminosarum and R. meliloti was 0.83. Within R. leguminosarum, the single strain of bv. viciae differed at an average of 0.65 from strains of bv. trifolii, while electrophoretic types of bv. trifolii differed at a range of 0.23 to 0.62. Analysis of RFLPs around two chromosomal DNA probes also delineated 16 unique RFLP patterns and yielded genetic diversity similar to that revealed by the allozyme data. Analysis of RFLPs around three Sym (symbiotic) plasmid-derived probes demonstrated that the Sym plasmids reflect genetic divergence similar to that of their bacterial hosts. The large genetic distances between many strains precluded reliable estimates of their genetic relationships.

Journal Article↗
PubMed1991

Redundancy in perceptual-motor testing: confirmation and generalization.

The Developmental Test of Visual-motor Integration was administered to 63 children in regular classrooms and 51 children in Special Education. Prediction based on total score (r = .68) was similar to a multiple R utilizing only five scores (.67). The over-all raw test score, based on all 24 designs, correctly classified 85% of the children while a combined abbreviated score utilizing only 5 designs achieved an 80% differentiation. Results were interpreted as confirming the hypothesis of redundancy in this perceptual-motor test.

Attention↗
PubMed1990

Constitutive production of interleukin 6 by ovarian cancer cell lines and by primary ovarian tumor cultures.

We examined the production and utilization of interleukin 6 (IL-6), a multifunctional cytokine with diverse biological effects, by both ovarian cancer cell lines and primary ovarian tumor cultures. We have found that epithelial ovarian cancer cell lines (CAOV-3, OVCAR-3, and SKOV-3) constitutively produce varying amounts of IL-6. This molecule is biologically active as determined by the proliferation of an IL-6-dependent hybridoma cell line, MH60.BSF-2, and is detectable by an IL-6 enzyme-linked immunosorbent assay. By cytoplasmic immunoperoxidase staining, greater than 98% of the cells produce at least some IL-6, with variation in the staining intensity between individual cells. The ovarian cancer cell-produced protein has a molecular weight of approximately 24,000, and exhibits some molecular weight heterogeneity, with Mr 27,000 and 28,000 minor forms of IL-6. The levels of IL-6 produced by ovarian cancer cells can be modulated by other inflammatory cytokines, such as tumor necrosis factor-alpha, interleukin-1 beta, and interferon-gamma. Our results suggest that IL-6 is not an autocrine growth factor for these established ovarian tumor cell lines, because the addition of either exogenous IL-6 or antibodies to IL-6 did not affect the cellular proliferation of the cell lines. We also found significant levels (greater than 3 ng/ml) of IL-6 in ascitic fluids of ovarian cancer patients and in the supernants of primary cultures from freshly excised ovarian tumors. The production of IL-6 by epithelial ovarian cancer cells may prove to be a useful diagnostic tool and aid in investigation of the host immune response to ovarian cancer.

Cell Division↗
PubMed1990

Geographical and social variations in mortality due to childhood accidents in England and Wales 1975-1984.

An analysis was made of the death rates from accidents in children aged 0-14 by health districts in England and Wales during the five year periods 1974-79 and 1980-84. Death rates were generally higher in the north and west of England and lower in the south and east. Rates were higher in urban areas than in rural areas. There was a more than five-fold difference between the highest and lowest rates by districts during both periods. There was a very strong correlation with social deprivation. Greater efforts are required to reduce unnecessary deaths and disability from childhood accidents. The lessons already learned in many parts of the world must now be put into much wider use and practice in the United Kingdom.

Accident Prevention↗
PubMed1990

Two outbreaks of Legionnaires' disease in Bolton Health District.

In 1988, there were two outbreaks of legionellosis in Bolton Health District. Altogether 37 cases of Legionnaires' disease and 23 cases of non-pneumonic legionellosis were identified. Twenty-five patients with Legionnaires' disease were associated with an engineering plant, 4 with Bolton town centre, and 8 with both the plant and town centre. Twenty-two people with non-pneumonic legionellosis were linked with the engineering plant and one with the plant and the town centre. A case-control study carried out among 37 employees with legionellosis and 109 control subjects at the plant showed that infection was associated with one of the 15 cooling towers on the site. Legionella pneumophila indistinguishable by serological and genetic typing methods was isolated from this cooling tower and from sputum samples from two patients. In the town centre, no one tower was linked with infection and L. pneumophila was not cultured from any of the nine towers identified. Control measures were implemented and to date there have been no further cases of legionellosis associated with Bolton Health District.

Adult↗
PubMed1990

The X chromosome of monotremes shares a highly conserved region with the eutherian and marsupial X chromosomes despite the absence of X chromosome inactivation.

Eight genes, located on the long arm of the human X chromosome and present on the marsupial X chromosome, were mapped by in situ hybridization to the chromosomes of the platypus Ornithorhynchus anatinus, one of the three species of monotreme mammals. All were located on the X chromosome. We conclude that the long arm of the human X chromosome represents a highly conserved region that formed part of the X chromosome in a mammalian ancestor at least 150 million years ago. Since three of these genes are located on the long arm of the platypus X chromosome, which is G-band homologous to the Y chromosome and apparently exempt from X chromosome inactivation, the conservation of this region has evidently not depended on isolation by X-Y chromosome differentiation and X chromosome inactivation.

Animals↗
PubMed1990

Molecular characterization of the nodulation gene, nodT, from two biovars of Rhizobium leguminosarum.

DNA sequencing of the nodIJ region from Rhizobium leguminosarum biovar trifolii revealed the nodT gene immediately downstream of nodJ. DNA hybridizations using a nodT-specific probe showed that nodT is present in several R. leguminosarum strains. Interestingly, a flavonoid-inducible nodT gene homologue in R. leguminosarum bv. viciae is not in the nodABCIJ operon but is located downstream of nodMN. The sequence of the nodT gene from bv. viciae was determined and a comparison of the predicted amino-acid sequences of the two nodT genes shows them to be conserved; the predicted protein sequences appear to have a potential transit sequence typical of outer-membrane proteins. Mutations affecting nodT in either biovar had no observed effect on nodulation of the legumes tested.

Amino Acid Sequence↗
PubMed1989

Molecular linkage of the nif/fix and nod gene regions in Rhizobium leguminosarum biovar trifolii.

Nucleotide sequence analysis of a 2.5kb region downstream of the nifA gene from Rhizobium leguminosarum biovar trifolii has resulted in linkage, at the DNA sequence level, of the nifEN, nifHDK, fixABCX, nifA gene cluster with the nodEF, nodD, nodABCIJ genes. Four genes have been identified within this intervening region. Immediately 3' to the nifA gene is the nifB gene and the nifB-linked ferredoxin-encoding fdxN gene. Downstream of fdxN in R. leguminosarum bv. trifolii and in Rhizobium meliloti, we have identified an open reading frame which has not been described previously and which we propose to designate fixU. Downstream of fixU in R. leguminosarum bv. trifolii is a nod gene, nodT, which is contiguous with nodJ (B. Surin et al., manuscript in preparation). As a result of this study, the linkage relationships of 22 symbiotic genes spanning a 24 kb region of the symbiotic plasmid from R. leguminosarum bv. trifolii are now known.

Amino Acid Sequence↗
PubMed1989

The nifA gene product from Rhizobium leguminosarum biovar trifolii lacks the N-terminal domain found in other NifA proteins.

The nifA gene has been identified between the fixX and nifB genes in the clover microsymbiont Rhizobium leguminosarum biovar trifolii (R.I. bv. trifolii) strain ANU843. Expression of the nifA gene is induced in the symbiotic state and site-directed mutagenesis experiments indicate that nifA expression is essential for symbiotic nitrogen fixation. Interestingly, the predicted R.I. bv. trifolii NifA protein lacks an N-terminal domain that is present in the homologous proteins from R.I. bv. viciae, Rhizobium meliloti, Bradyrhizobium japonicum, Klebsiella pneumoniae and all other documented NifA proteins. This indicates that this N-terminal domain is not essential for NifA function in R.I. bv. trifolii.

Amino Acid Sequence↗
PubMed1989

The clinical utility of discriminant functions for the differential diagnosis of microcytic anemias.

Several groups of authors have derived discriminant functions (DFs) based on red cell indices (primarily MCH, MCV, and RDW) that can be used to differentiate iron deficiency from thalassemia minor. The Technicon H*1 analyzer provides a direct MCHC measurement (termed the CHCM), in addition to the conventional computed value (Hgb/PCV). To evaluate the clinical utility of red cell discriminant analysis, chart review was performed in 176 cases for which hemoglobin characterization and quantitation studies had been requested. Six published discriminants were evaluated for cases of clearly defined iron deficiency anemia and thalassemia minor. Overall diagnostic efficiency ranged from 50%-82%, and the diagnostic performance of three of the discriminants failed to achieve statistical significance. Mean values for both MCHC and CHCM were significantly lower in patients with iron deficiency than in patients with other causes of microcytic anemia. It was also observed that MCHC was significantly greater than CHCM in patients with iron deficiency anemia, but not in patients with other causes of microcytic anemia. Both MCHC and the difference between MCHC and CHCM showed potential value as parameters for the differential diagnosis of iron deficiency from other causes of microcytic anemia. It was noted, however, that in 67% of the cases studied, the use of a DF could not have resolved the diagnosis to the extent that hemoglobin characterization and quantitation studies were no longer indicated.

Anemia, Hypochromic↗
PubMed1988

Cholinergic antagonism of beta-adrenergic stimulated action potentials and adenylate cyclase activity in rabbit ventricular cardiomyocytes.

The cholinergic antagonism of beta-adrenergic stimulation was examined by measuring adenylate cyclase activity and calcium-mediated action potentials in isolated ventricular cardiomyocytes of adult rabbits. The beta-adrenoceptor agonist isoproterenol and the direct adenylate cyclase activator forskolin increased adenylate cyclase activity in homogenates of the myocytes. The cholinergic agonist carbachol (10 nM-100 microM) inhibited in a concentration dependent manner basal, isoproterenol-stimulated and forskolin-stimulated adenylate cyclase activity. The carbachol effect on basal adenylate cyclase activity was antagonized by atropine (10 microM). In parallel experiments using intact cardiomyocytes, calcium action potentials were elicited by intracellular depolarizing current pulses in partially depolarized preparations. These action potentials were prolonged by isoproterenol, forskolin and dibutyryl cyclic AMP. Acetylcholine reversibly inhibited the prolongation of the action potential induced by isoproterenol and forskolin but not dibutyryl cyclic AMP. These results suggest that cholinergic agonists modulate the increase in the calcium current elicited by isoproterenol and forskolin in isolated ventricular cardiomyocytes by inhibiting adenylate cyclase activity.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Tuberculous stenosis of the trachea.

A patient is described who presented with symptoms suggestive of asthma but was subsequently found to have a stenotic lesion of the lower trachea and main bronchi. Bronchoscopic biopsy of the lesion revealed tuberculosis. There was a good response to anti-tuberculosis chemotherapy, with no residual stenosis.

Adult↗
PubMed1988

Gene mapping in marsupials and monotremes, V. Synteny between hypoxanthine phosphoribosyltransferase and phosphoglycerate kinase in the platypus.

In order to extend comparative mapping studies to the monotreme mammals (subclass Prototheria), somatic-cell hybrids were obtained between Chinese-hamster cells deficient in hypoxanthine phosphoribosyltransferase (HPRT) and platypus fibroblasts. The characteristics of these hybrids closely resemble those of metatherian x eutherian hybrids, in that they are recovered at low frequency and they rapidly segregate and fragment platypus chromosomes. Biochemical and cytological studies of the hybrids, their subclones and HPRT-deficient revertants indicate that phosphoglycerate kinase is syntenic with HPRT in the platypus (as it is in other mammals); however, the studies do not permit chromosomal assignment of the syntenic group. The implications of the chromosomal location of this ancient synteny group for the evolution of the mammalian X chromosome are discussed.

Animals↗