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J Williams

Publications and source records attributed to J Williams.

At least 595 records · Page 33Linked to original sources
PubMed1993

Plasma L-arginine levels in a rabbit model of hypercholesterolaemia.

A novel method for the quantitation of L-arginine in plasma samples has been developed, based on the technique of enantiomer labelling coupled to the capillary gas chromatographic separation of amino acids. Using this technique plasma L-arginine levels have been measured in rabbits fed a 1% cholesterol-containing diet and compared with rabbits fed a standard diet. Blood cholesterol levels were significantly elevated in the rabbits fed cholesterol but no significant difference was found in plasma L-arginine levels between the cholesterol-fed and control animals. No D-arginine was found in any of the plasma samples. It is concluded that the impairment in endothelium-dependent relaxation previously described in this animal model of hypercholesterolaemia is not due to deficiency of plasma L-arginine.

Animals↗
PubMed1993

Agricultural soil fumigation as a source of atmospheric methyl bromide.

Methyl bromide (MeBr) is used increasingly as a biocidal fumigant, primarily in agricultural soils prior to planting of crops. This usage carries potential for stratospheric ozone reduction due to Br atom catalysis, depending on how much MeBr escapes from fumigated soils to the atmosphere and on details of atmospheric chemical reactions. We present direct field measurements of MeBr escape; 87% of the applied MeBr was emitted within 7 days after a commercial fumigation. Covering the field with plastic sheets retarded MeBr escape somewhat but first-day losses were still 40%; thicker sections of sheets were relatively more effective than thin sections. We also measured gaseous MeBr concentrations versus depth in the soil column; these profiles display diffusion-like evolution. In soil, MeBr is partitioned among gas, liquid, and adsorbed solid phases. Calculated soil inventories agreed only roughly with applied amounts, probably due to nonequilibrium partitioning (during the first 30 min) and to uncertainties in partitioning coefficients. Fumigated fields may release less MeBr if they are covered by more gas-tight plastic films, if injection techniques are improved and injection is deeper, and if soil moistures, organic amounts, and densities are greater than in the soil studied here.

Journal Article↗
PubMed1993

The new American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiac care: presented by the Emergency Cardiac Care Subcommittee of the Heart and Stroke Foundation of Canada.

CPR courses (both basic and advanced) continue to evolve. The recent CPR and ECC guidelines by the AHA consolidate the research and vast experience in one document. These guidelines are helpful to lay people and health care professionals who intervene in cases of cardiac arrest. They are also excellent resources for those involved in coordinating ECC systems in the community.

American Heart Association↗
PubMed1993

Discrepancy in mosaic findings between chorionic villi and amniocytes: a diagnostic dilemma involving 45,X, 46,XY, and 47,XYY cell lines.

Discrepancies between cytogenetic findings in chorionic villi (CV) and fetal tissue have been reported. Several embryogenic models have been proposed to explain such discrepancies. We describe a case in which analysis of the direct preparation showed 24% 45,X and 76% 46,XY, with 43% 45,X and 57% 46,XY cells in cultured villi. Amniocentesis results disclosed 97% 46,XY and 3% 47,XYY. No 45,X cells were found in cultured amniocytes. These findings suggest that nondisjunction occurred early in postzygotic cleavage resulting in 3 cell lines. It is postulated that through selection, the less viable 45,X cells died out among those destined to become fetus proper but persisted among the cytotrophoblast and extraembryonic mesoderm cells. While there is probably selection against all aneuploid cell lines, 47,XYY cells are more likely to survive in the fetus. An explanation for the lack of 47,XYY cells in the CV might be simply that the tissue sampled was not representative of the cytogenetic make up of the entire placenta.

Adult↗
PubMed1993

Dose-related efficacy and bleeding complications of double-chain tissue plasminogen activator in acute myocardial infarction. The Wellcome Tissue Plasminogen Activator Study Group.

Although the efficacy of recombinant tissue-type plasminogen activator (rt-PA) in acute myocardial infarction has been demonstrated, little formal dose-ranging information is available. This study examined the use of duteplase, the double-chain rt-PA subsequently used in the Third International Study of Infarct Survival, in a multicenter trial of 267 patients with evolving acute myocardial infarction assigned to receive 1 of 6 weight-adjusted doses. The primary end point was infarct vessel patency after 90 minutes of drug infusion. Patency was defined as Thrombolysis in Myocardial Infarction trial grade 2 or 3 perfusion, and was determined by an independent core laboratory masked to treatment assignment. Patency was present in 48% of patients receiving the lowest dose range and 78% of those receiving the highest, with an association between thrombolytic dose and patency (p = 0.009). The frequency of serious bleeding complications also correlated with the total dose of rt-PA infused (p = 0.003). Bleeding complications were primarily related to instrumentation; blood loss requiring transfusion or otherwise deemed clinically significant occurred in 12% of patients (central nervous system hemorrhage occurred in 1.1%). Thus, higher doses of rt-PA are associated both with increased efficacy and increased risk of serious bleeding complications. Weight-adjusted dosing may provide an optimal risk-benefit ratio for thrombolysis during acute myocardial infarction.

Adult↗
PubMed1993

Interaction and dose equivalence of salbutamol and salmeterol in patients with asthma.

OBJECTIVE: To examine the pharmacological interaction of salmeterol and salbutamol and to derive an estimate of dose equivalence of salmeterol for airway and systemic effects in patients with asthma. DESIGN: Randomised double blind crossover study. SUBJECTS: 12 patients with mild asthma. INTERVENTION: Placebo or salmeterol 50, 100, 200 micrograms given on separate days followed two hours later by inhaled salbutamol in cumulative doses up to 3600 micrograms. MAIN OUTCOME MEASURES: Change in forced expiratory volume in one second (FEV1), heart rate, plasma potassium concentration, QTc interval, tremor amplitude, and creatine kinase myocardial isoenzyme concentration. RESULTS: Compared with placebo, the mean (95% confidence interval) changes in FEV1 and heart rate after salmeterol 200 micrograms were 0.61 (0.32 to 0.90) l and 7.0 (3.8 to 10.2) beats/min. Adding salbutamol caused a large increase in FEV1 after placebo (0.69 l) with progressively smaller changes after increasing doses of salmeterol (0.19 l after salmeterol 200 micrograms). Heart rate and QTc interval increased and plasma potassium concentration decreased roughly in parallel on the four study days with a suggestion of convergence at higher doses of salbutamol. Geometric mean dose equivalences for salmeterol 50 micrograms and 100 micrograms compared with salbutamol were 4.9 and 7.8 (mean 6.4) for FEV1 and ranged from 7.1 (2.9 to 17.0) to 12.6 (4.4 to 36.4) for heart rate, plasma potassium, and tremor (mean 9.5). CONCLUSIONS: The effect of adding salbutamol to salmeterol is largely additive. Weight for weight salmeterol may be up to 10 times more potent than salbutamol. Considering its longer duration of action salmeterol 50 micrograms twice daily could be equivalent to salbutamol in doses up to 500 micrograms four to six hourly.

Adolescent↗
PubMed1993

Use of iohexol as a gastrointestinal contrast agent in three dogs, five cats, and one bird.

Barium sulfate suspension is routinely used as contrast medium for upper gastrointestinal procedures. It has been contraindicated for use in cases of suspected perforation. In such instances, water-soluble iodides are recommended for use. Most of the water-soluble iodides available for use in veterinary medicine at this time are hyperosmolar. This results in in transit dilution of the contrast column. The dilution of the contrast agent within the intestines may prevent visualization of a perforation, especially if the perforation is in the distal portion of the small intestine. Iohexol a nonionic water-soluble iodide of low osmolality, is currently used in veterinary medicine for myelography. We have used it as the contrast agent for upper gastrointestinal studies in cases of suspected obstruction or perforation, with good results, and no adverse effects have been associated with its use. Opacity of the contrast column was adequate, and segmentation or flocculation of the column was not apparent.

Animals↗
PubMed1993

Cytogenetic abnormalities in mesoblastic nephroma: a link to Wilms' tumour?

Cytogenetic analysis of tumour material from a congenital mesoblastic nephroma is reported. Two cell lines were found, one with a normal 46,XY karyotype and the other with a hyperdiploid 51,XY karyotype, including a rearrangement of chromosome 11 at 11p15. This finding is of interest since loss of allelic heterozygosity at polymorphic 11p15 loci has been described in sporadic Wilms' tumour [1], and both cytogenetic [2] and molecular [3] changes of 11p15 are found in the Wiedemann-Beckwith syndrome, a condition with a predisposition to embryonal tumours, particularly Wilms' tumour. Our results lead us to speculate on the implications relating to the pathogenesis of this relatively benign tumour variant with respect to the current understanding of the genetics of Wilms' tumour.

Chromosome Deletion↗
PubMed1993

Mosaicism in chorionic villus sampling: an analysis of incidence and chromosomes involved in 2612 consecutive cases.

The incidence of chromosome mosaicism was analysed in 2612 consecutive chorionic villus sampling (CVS) cases. True mosaicism was found in five cases (0.19 per cent). Confined placental mosaicism (CPM) occurred in 51 cases (1.9 per cent). The chromosomes most frequently encountered in CPM were 2, 7, 8, and the sex chromosomes. Three types of CPM as proposed by Kalousek et al. (1992) were observed. Cases with CPM had a statistically significant association with spontaneous abortion (chi 2 = 3.92, p < 0.05). Based on the data analysed, we conclude that (1) CPM is as likely to occur in cultured chorionic villi as in the direct preparation; (2) as with amniocyte culture, chromosome 2 mosaicism occurs commonly in villus culture; (3) the incidence of false-positive results can be greatly reduced and concern about maternal cell contamination can be alleviated by using both direct cytotrophoblast preparation and cultured chorionic stroma cells in all cases; and (4) follow-up cytogenetic and obstetrical studies, such as ultrasound and fetal monitoring, should always be considered in cases where CPM is suspected.

Cells, Cultured↗
PubMed1993

Characterization of i(18p) in prenatal diagnosis by fluorescence in situ hybridization.

A case is presented in which chorionic villus direct preparation and cultured chorionic villus cells revealed a 47,XX+mar karyotype. The marker was a small metacentric chromosome and appeared to be i(18p)--isochromosome 18p. Follow-up studies in both amniotic fluid and fetal fibroblasts confirmed the karyotype. In order to characterize the marker, a panel of biotinylated DNA probes was used, including a whole chromosome 18 probe, chromosome 18-specific alpha satellite DNA, Yac clones, and a pan-telomeric probe. These studies show that the marker is a monocentric i(18p) in which about 80 per cent of chromosome 18 alpha satellite DNA has been lost.

Adult↗
PubMed1993

Transcervical CVS sample size: correlation with placental location, cytogenetic findings, and pregnancy outcome.

Data from 2907 transcervical CVS cases performed on singleton pregnancies were reviewed retrospectively and villus sample size was correlated with cytogenetic results, placental location, maternal age at the expected date of confinement (EDC), gestational age at the time of sampling, birth weight, gestational age at the time of delivery, and pregnancy outcome. No correlation was noted between villus sample size and maternal age, gestational age at sampling, gestational age at delivery, birth weight, or pregnancy outcome. An inverse correlation between villus sample size and percentage of abnormal cytogenetic findings was statistically significant (chi 2 = 8.53, p < 0.01). The percentage of small samples was greater when the placenta was anterior, lateral, or fundal than when the placenta was posterior.

Adult↗
PubMed1993

A new biologically, osmotically, and oncotically balanced gel that shows calcifications blocked by silicone.

The radiodensity of silicone gel-filled breast implants is well documented. It has been suggested that silicone gel may block the transmission of x-rays sufficiently to prevent visualization of microcalcifications that are frequently an indicator of malignancy. A new biologically, oncotically balanced gel has been developed that has increased radiotranslucency to approximately the density of normal breast tissue, increased lubrication qualities, and is quickly and safely eliminated by the body should the shell rupture. We present a case wherein a patient's mammogram was read as negative two years prior to breast reaugmentation due to Baker IV capsular contracture. During surgery, complete calcification of the capsule was discovered, as well as two ruptured prostheses; neither condition had been detected by the mammogram. These capsules, with their calcifications and scar intact, were removed in toto and radiographically compared through standard silicone gel-filled breast implants and through implants containing the new biologically, osmotically, oncotically balanced gel. The calcifications were completely obscured by the silicone gel-filled prosthesis and completely visible when viewed through the bio-oncotic gel-filled prosthesis. Postoperative mammograms confirmed the radiolucency of the new gel-filled prostheses. This new gel appears to be a reasonable alternative to silicone gel for filling breast implants.

Adult↗
PubMed1993

Suppression of eltoprazine-induced REM sleep rebound by scopolamine.

Previous studies have demonstrated that REM sleep suppression produced by the serotonin1 agonist eltoprazine (1 mg/kg b.i.d., administered i.p.) is followed by a dramatic rebound in REM sleep. In the present study, cats were treated with scopolamine (2 mg/kg b.i.d.) after 3 days of eltoprazine-induced REM sleep suppression. During scopolamine treatment, the percentage of REM sleep (9.9 +/- 3.5%) was well below baseline levels (13.7 +/- 1.6%; P < 0.05). Even after the 3-day scopolamine treatment ended, the subsequent REM sleep rebound after the combined eltoprazine-scopolamine treatment (16.8 +/- 2.8% REM sleep during 3-day rebound; P < 0.10 compared to baseline) was less than a third of the rebound normally seen after eltoprazine. These results provide evidence for the reciprocal relationship between acetylcholine and serotonin and suggest a new set-point model for the mechanism of REM sleep regulation and rebound.

Analysis of Variance↗
PubMed1993

Sézary syndrome with elevated serum IgE and hypereosinophilia: role of dysregulated cytokine production.

A 62-year-old man presented with a 4-year history of a pruritic erythematous rash. Initial workup was not diagnostic, and the rash was refractory to standard treatment. A complete blood cell count demonstrated a white cell count of 9100 cells/microliter with 61% polymorphonuclear neutrophils, 16% eosinophils, and 17% lymphocytes. A serum protein electrophoresis revealed an M spike identified as IgG kappa. His IgE level was 11,900 IU/ml. A bone marrow biopsy specimen demonstrated "atypical plasma cells" but was not diagnostic for myeloma. Peripheral blood smear was remarkable for highly convoluted lymphoid cells diagnostic for Sézary T cells. Consistent with this diagnosis, 89% of his peripheral blood CD2+ cells expressed CD4. The eosinophilia, elevated IgE level, and monoclonal gammopathy led to further investigations. Circulating adherent monocytes were 96% positive for presumed low-affinity IgE receptor expression as shown by surface IgE binding. In a 9-day lymphocyte coculture, the patient's T lymphocytes induced IgE production in vitro (1.25 ng/ml) by a normal donor's cultured B cells. A healthy donor's T cells failed to induce IgE production (0 ng/ml) in a similar culture system. In situ hybridization with an Sulfur-35-labeled cDNA probe revealed interleukin-4 mRNA expression by 84% and interleukin-2 mRNA expression by 62% of nonadherent peripheral blood mononuclear cells. Interleukin-5 mRNA was shown by reverse transcription and the polymerase chain reaction. These studies demonstrate a subject with Sézary T cell leukemia with hypereosinophilia and elevated IgE due to presumed enhanced interleukin-4 and interleukin-5 production by the Sézary T cells.

B-Lymphocytes↗
PubMed1993

Heterogeneity in schizophrenia: an extended replication of the hebephrenic-like and paranoid-like subtypes.

Hebephrenic-like (H) and paranoid-like (P) subtypes of schizophrenia have previously been described by Farmer et al. (1983, 1984). The stability of this subtypology of schizophrenia was explored using multivariate statistical techniques on a large independent data set. Both a discriminant function analysis and an admixture analysis produced strong evidence for a bimodel distribution of scores consistent with the H-like and P-like subtypes.

Adult↗
PubMed1993

A deleted hobo element is involved in the unstable thermosensitive vg(al) mutation at the vestigial locus in Drosophila melanogaster.

We have described a new unstable mutant of the vestigial locus isolated from a natural population. From this mutant, vestigial(almost) (vg(al)), wild-type (vg(al+)), and extreme (vg(ext)), alleles arose spontaneously. The molecular analysis of vg(al) shows that the mutation is due to a 1874 bp hobo element inserted in a vestigial intron. Two distinct kinds of events lead a wild-type phenotype. Three independent vg(al+) alleles result from an excision of the hobo element and two other vg(al+) alleles have further deletions of hobo sequence. The sequence of one of them shows a 1516 bp hobo insertion at the same place and in the same orientation as the 1874 bp insertion. In the vg(ext) alleles, we found a 5' or 3' variably sized deletion of vg sequences. One of them, which has been cloned and sequenced, has a deletion finishing exactly at the left terminal repeat' hobo element. The genetic implications of these different genetic structures are discussed.

Alleles↗