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Biomedical subjects

S Ward

Publications and source records attributed to S Ward.

At least 235 records · Page 13Linked to original sources
PubMed1988

Evolutionary and morphological significance of the deflecting wrinkle in the lower molars of the Hominoidea.

The deflecting wrinkle is a well-known character state of the lower m2 and M1 of the human dentition, but there is little information regarding its presence in great apes. The deflecting wrinkle is more frequent on M2-3 in all extant pongid genera studied in this paper except Pan paniscus, in which M1 has the highest frequency (16.0%) and in which this wrinkle is absent on M3. In Gorilla, it is absent on M1, with only a low incidence on M2-3. Its greatest frequency in Pongo is always on M2 (20.2%), which is the greatest expression of the trait in the great apes. We interpret the presence of the deflecting wrinkle as an incidental effect and suggest that it represents a plesiomorphic character state in the Hominoidea.

Animals↗
PubMed1988

Progesterone profiles in luteal phase defect cycles and outcome of progesterone treatment in patients with recurrent spontaneous abortion.

The existence of luteal phase defect has been the focus of much debate, mainly because of inconsistencies in its diagnosis and management. This study was performed to compare progesterone profiles in women with luteal phase defect with those of women with normal cycles and to establish a discriminatory level of serum progesterone that may aid in the diagnosis of this condition. Compared with patients with luteal phase defect cycles, women with normal cycles produced significantly more progesterone in the luteal phase. The serum progesterone level (less than or equal to 21 nmol/L) was the optimal discriminatory level between luteal phase defect and normal cycles and provided a diagnostic test with 70% sensitivity and 71% specificity. In women with recurrent abortion, the incidence of luteal phase defect was 40%, but with treatment 81% of pregnancies were successful. The findings in this study support the existence of luteal phase defect as a clinically significant entity in recurrent first-trimester spontaneous abortion and one that can be treated successfully with the administration of progesterone. The histologic diagnosis of luteal phase defect may also be confirmed with serum progesterone.

Abortion, Habitual↗
PubMed1988

The changing response of Plasmodium falciparum to antimalarial drugs in east Africa.

For the past 20 years, chloroquine chemotherapy has been the single most effective malaria control measure in East Africa. The advent of chloroquine-resistant Plasmodium falciparum has reduced the clinical effectiveness of chloroquine and this trend is likely to continue. Combinations of antifol drugs are at present effective inhibitors of most P. falciparum infections in the region, in spite of widespread resistance to pyrimethamine. The development of (i) sensitive methods for monitoring changes in sensitivity to antifol combinations, (ii) more effective and less costly alternatives to commercially available combinations, and (iii) investigation of host and parasite factors leading to drug treatment failure in P. falciparum infections has been the primary goal of the Wellcome Trust Research Laboratories in Kenya (directed by Dr W.M. Watkins) within the malaria programme of the Kenya Medical Research Institute, and collaborating laboratories at the School of Tropical Medicine and the University of Liverpool.

Africa, Eastern↗
PubMed1988

Melatonin and light treatment of ewes for autumn lambing.

Forty spring lambing adult, and 24 unbred yearling, Suffolk crossbred ewes were allocated to 3 groups. Group I and II were maintained on 18L: 6D and Group III on Local light (51 degrees 42' N) during 24 Feb-13 April. During 13 April-11 July Group I changed to 9L: 15D and Groups II and III were group fed a diet containing melatonin and providing 3 mg/ewe at 16.00 hrs daily. A further 20 adult ewes, Group IV and V were maintained on Local light during 24 Feb-13 April; Group IV was transferred to 9L: 15D and Group V remained on Local light during 13 April-11 July. The ewes were exposed to vasectomised rams from the time of weaning on 3 June. All ewes were housed until 11 July and then remained at pasture thereafter. The performance of the yearling ewes was as follows - % Keel-marked during 11-28 follows: Group I - 90.0; Group II - 100.0: Group III 92.3; Group IV - 50.0; Group V - 10.0. There were no significant differences between Groups I, II and III. The following percentage of adult ewes lambed during 3-23 December - 66.7; 85.7; 69.2; 20.0 and 0.0 for Groups I - V respectively. Groups I, II and III were significantly higher than Group V. The performance of the yearling ewes was as follows - % keel-marked during 11-28 July: Group I - 100.0; Group II - 66.7; Group III - 22.2. The following percentage of yearling ewes lambed during 3-23 December - 50.0; 44.4 and 11.1 for Group I - III respectively. An assessment of these data in relation to autumn lambing is presented in the paper.

Animals↗
PubMed1988

Developmental genetics of chromosome I spermatogenesis-defective mutants in the nematode Caenorhabditis elegans.

Mutations affecting Caenorhabditis elegans spermatogenesis can be used to dissect the processes of meiosis and spermatozoan morphological maturation. We have obtained 23 new chromosome I mutations that affect spermatogenesis (spe mutations). These mutations, together with six previously described mutations, identify 11 complementation groups, of which six are defined by multiple alleles. These spe mutations are all recessive and cause normally self-fertile hermaphrodites to produce unfertilized oocytes that can be fertilized by wild-type male sperm. Five chromosome I mutation/deficiency heterozygotes have similar phenotypes to the homozygote showing that the probable null phenotype of these genes is defective sperm. Spermatogenesis is disrupted at different steps by mutations in these genes. The maturation of 1 degree spermatocytes is disrupted by mutations in spe-4 and spe-5. Spermatids from spe-8 and spe-12 mutants develop into normal spermatozoa in males, but not in hermaphrodites. fer-6 spermatids are abnormal, and fer-1 spermatids look normal but subsequently become abnormal spermatozoa. Mutations in five genes (fer-7, spe-9, spe-11, spe-13 and spe-15) allow formation of normal looking motile spermatozoa that appear to be defective in either sperm-spermathecal or sperm-oocyte interactions.

Alleles↗
PubMed1988

Characterization of an Escherichia coli rff mutant defective in transfer of N-acetylmannosaminuronic acid (ManNAcA) from UDP-ManNAcA to a lipid-linked intermediate involved in enterobacterial common antigen synthesis.

The rff genes of Salmonella typhimurium include structural genes for enzymes involved in the conversion of UDP N-acetyl-D-glucosamine (UDP-GlcNAc) to UDP N-acetyl-D-mannosaminuronic acid (UDP-ManNAcA), the donor of ManNAcA residues in enterobacterial common antigen (ECA) synthesis. An rff mutation (rff-726) of Escherichia coli has been described (U. Meier and H. Mayer, J. Bacteriol. 163:756-762, 1985) that abolished ECA synthesis but which did not affect the synthesis of UDP-ManNAcA or any other components of ECA. The nature of the enzymatic defect resulting from the rff-726 lesion was investigated in the present study. The in vitro synthesis of GlcNAc-pyrophosphorylundecaprenol (lipid I), an early intermediate in ECA synthesis, was demonstrated by using membranes prepared from a mutant of E. coli possessing the rff-726 lesion. However, in vitro synthesis of the next lipid-linked intermediate in the biosynthetic sequence, ManNAcA-GlcNAc-pyrophosphorylundecaprenol (lipid II), was severely impaired. Transduction of wild-type rff genes into the mutant restored the ability to synthesize both lipid II and ECA as determined by in vitro assay and Western blot (immunoblot) analyses done with anti-ECA monoclonal antibody, respectively. Our results are consistent with the conclusion that the rff-726 mutation is located in the structural gene for the transferase that catalyzes the transfer of ManNAcA from UDP-ManNAcA to lipid I.

Antigens, Bacterial↗
PubMed1988

Accumulation of a lipid-linked intermediate involved in enterobacterial common antigen synthesis in Salmonella typhimurium mutants lacking dTDP-glucose pyrophosphorylase.

The heteropolysaccharide chains of enterobacterial common antigen (ECA) are composed of linear trisaccharide repeat units having the structure----3)-alpha-Fuc4NAc-(1----4)-beta-D-ManNAcA-(1---- 4)-alpha-D-GlcNAc- (1----. Mutants of Salmonella typhimurium lacking the structural gene for dTDP-glucose pyrophosphorylase (rfbA) are severely impaired in their ability to synthesize dTDP-glucose, which is a precursor of dTDP-4-acetamido-4,6-dideoxy-D-galactose (Fuc4NAc), the donor of Fuc4NAc residues for ECA synthesis. These mutants synthesize only trace amounts of ECA, and they are hypersensitive to sodium dodecyl sulfate (SDS). Incubation of delta rfbA mutants with [3H]N-acetylglucosamine ([3H]GlcNAc) resulted in the accumulation of radioactivity in N-acetyl-D-mannosaminuronic acid (ManNAcA)-GlcNAc-pyrophosphorylundecaprenol (lipid II), the putative acceptor of Fuc4NAc residues in ECA synthesis. Lipid II did not accumulate in either wild-type cells or in rff mutants unable to synthesize ManNAcA. Both the accumulation of lipid II and the synthesis of trace amounts of ECA were abolished when delta rfbA mutants were grown in the presence of the antibiotic tunicamycin. Tunicamycin also prevented the SDS-mediated lysis of the mutants. SDS-resistant derivatives of delta rfbA mutants were isolated that were no longer able to synthesize trace amounts of ECA. Characterization of these derivatives revealed that they were defective in various steps of ECA synthesis leading to the synthesis of lipid II. The data support the conclusion that accumulation of lipid II is responsible in some way for the hypersensitivity of delta rfbA mutants to SDS.

Antigens, Bacterial↗
PubMed1988

Prophylaxis against acid aspiration syndrome. Single oral dose of H2-antagonist on the evening before elective surgery.

We have compared famotidine 40 mg, ranitidine 300 mg and placebo given in a single oral dose at 2200 hours as the sole means of prophylaxis in 286 patients who underwent elective surgery the following day. Standardised premedication was administered and anaesthesia induced. Gastric contents were aspirated by nasogastric suction and the pH and volume measured. Median values of pH after famotidine, ranitidine and placebo were 6.17, 6.74 and 2.45 respectively; median aspirate volumes were 8, 8 and 10 ml respectively. The proportions of patients considered 'not at risk' (pH greater than 2.5) were 90% after famotidine, 91% after ranitidine and 52% after placebo. We conclude that the administration of a potent H2-antagonist in a single oral dose at night offers a convenient routine means of providing extensive prophylactic cover in patients scheduled to undergo elective surgery the following day.

Administration, Oral↗
PubMed1988

Diagnostic test properties of serum progesterone in the evaluation of luteal phase defects.

The existence of LPD has been controversial, mainly because of inconsistencies in its diagnosis. The endometrial biopsy remains as a gold standard until newer and better tests are developed. Additional information may be provided from serum P determinations in the luteal phase by using the likelihood ratios and positive predictive values obtained in this study. Since the properties of sensitivity and specificity are inversely related, the selection of discriminatory cutoff level of serum P would optimize one at the expense of the other. There is no value that combines both sensitivity and specificity as far as correlation with endometrial biopsy is concerned.

Abortion, Spontaneous↗
PubMed1987

Pliocene hominid partial mandible from Tabarin, Baringo, Kenya.

Sediments in the Tugen Hills, west of Lake Baringo, Kenya, form one of the best fossiliferous successions known in Africa spanning the period from 14 my to less than 4 my. Hominoid fossils have previously been recovered from a number of localities in the region. We describe here a new hominid mandible (KNM-TH 13150) from the site of Tabarin, in the Chemeron Formation. Isotopic determinations on a tuff below the fossiliferous horizon gives dates of 4.96 my and 5.25 my. The associated fauna is consistent with these results and independently suggests a minimum age for the specimen of 4.15 my. Although fragmentary, the preserved morphology of the Tabarin mandible is consistent with the diagnosis of the Pliocene hominid Australopithecus afarensis. It can be distinguished from all other currently recognized hominoid taxa.

Animals↗
PubMed1987

Pharmacokinetics of atracurium and its metabolites in patients with normal renal function, and in patients in renal failure.

The plasma pharmacokinetic profiles of atracurium and its derivatives, laudanosine and monoquaternary alcohol, were studied in six patients with renal failure after a bolus dose of atracurium 0.3-0.4 mg kg-1. The pharmacokinetics of the derivatives only were studied in a group of four normal patients receiving atracurium 0.3 mg kg-1. Measurements of plasma and urine concentrations were performed by high pressure liquid chromatography. Pharmacokinetics of atracurium were not significantly different in the renal failure group when compared with those obtained in a previous study on six normal patients. Although 2-10% of the dose was recovered in the urine of normal patients as unchanged atracurium, and 3-4% as laudanosine, renal failure produced no significant differences in plasma pharmacokinetics, with mean plasma elimination half-lives of 20 min for atracurium, 234 min for laudanosine and 39 min for quaternary alcohol.

Adult↗