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Biomedical subjects

E H Williams

Publications and source records attributed to E H Williams.

At least 19 recordsLinked to original sources
PubMed1996

Environmental stress sensitivity of an ascorbic acid-deficient Arabidopsis mutant.

L-ascorbic acid (vitamin C) is a powerful reducing agent found in millimolar concentrations in plants, and is proposed to play an important role in scavenging free radicals in plants and animals. However, surprisingly little is known about the role of this antioxidant in plant environmental stress adaptation or ascorbate biosynthesis. We report the isolation of soz1, a semi-dominant ozone-sensitive mutant that accumulates only 30% of the normal ascorbate concentration. The results of genetic approaches and feeding studies show that the ascorbate concentration affects foliar resistance to the oxidizing gas ozone. Consistent with the proposed role for ascorbate in reactive oxygen species detoxification, lipid peroxides are elevated in soz1, but not in wild type following ozone fumigation. We show that the soz1 mutant is hypersensitive to both sulfur dioxide and ultraviolet B irradiation, thus implicating ascorbate in defense against varied environmental stresses. In addition to defining the first ascorbate deficient mutant in plants, these results indicate that screening for ozone-sensitive mutants is a powerful method for identifying physiologically important antioxidant mechanisms and signal transduction pathways. Analysis of soz1 should lead to more information about the physiological roles and metabolism of ascorbate.

Arabidopsis↗
PubMed1993

Epidemic misuse.

Explore the source record for details and available documents.

Animals↗
PubMed1993

Transfer of incompatibility factors between stocks of Nasonia (= Mormoniella) vitripennis.

The stock of Nasonia vitripennis marked by the nuclear eye color mutation "tinged" (ti) shows nonreciprocal cytoplasmic incompatibility with wild-type (+) strains. Homogenates prepared from ti female pupae and injected into + female pupae caused 39% of the recipients to acquire the incompatibility characteristics of the ti donors. When eggs obtained from ti females were fragmented and injected into + female pupae, or when the ti egg cytoplasm was injected into chick eggs and yolk sac homogenates were subsequently injected into + female pupae, 28% of the recipients acquired ti-type incompatibility characteristics. Results from passage of the egg cytoplasm through 0.23-microns millipore filters showed successful transfer of the incompatibility and suggest that the incompatibility system in N. vitripennis has two components: a bacterium and a smaller agent.

Animals↗
PubMed1992

Neobenedenia pargueraensis n. sp. (Monogenea: Capsalidae) from the red hind, Epinephelus guttatus, and comments about Neobenedenia melleni.

Neobenedenia pargueraensis n. sp. from Epinephelus guttatus of Puerto Rico differs from all known species in possessing scoop-shaped accessory sclerites with pointed tips. It is most similar to Neobenedenia melleni and Neobenedenia longiprostata but differs from the former in having a fenestrate ovary and from the latter in that the ducts of the accessory glands are short, terminating just anterior to the vitelline reservoir rather than reaching the caudal end of the body. It differs from both species in having smooth rather than lobate testes. Neobenedenia melleni occurs throughout the tropical and subtropical western North Atlantic including Bermuda. It kills aquarium and aquaculture fishes with massive infestations and is a severe restraint on the culture of tilapia in sea water in the Caribbean.

Animals↗
PubMed1991

Influence of collection methods on the occurrence of alimentary canal helminth parasites in fish.

The effect of collecting trauma on the metazoan parasites in the alimentary canal of French grunts, Haemulon flavolineatum (Desmarest) (Perciformes: Haemulidae), was evaluated by comparing the number and species of parasites in 10-fish lots that were identical except for collecting technique. Collecting techniques included speared (dead), speared through the caudal peduncle (live), trapped, dipnetted at night, and ostracitoxin exposed. Dead, trapped, and toxin-stressed fish had no alimentary canal parasites, whereas speared-live and night-dipnetted fish had comparable numbers of parasites. Fish collected by using apparently traumatic techniques quickly expelled their alimentary canal metazoan parasites. Our results cast doubt on the reliability of traditional fish parasite surveys, studies on population dynamics of fish parasites, and experiments that employ these traumatic collecting methods.

Animals↗
PubMed1988

Aldose reductase expression in human diabetic retina and retinal pigment epithelium.

The conversion of glucose to sorbitol by aldose reductase (AR) and its subsequent intracellular accumulation have been implicated in the pathogenesis of diabetic cataracts. There is also evidence linking AR activity with retinal capillary basement membrane thickening in galactosemic rats, suggesting a possible role in diabetic retinopathy. In this study, we explored one feature of this issue by examining diabetic and nondiabetic eyes for immunoreactive AR. AR was immunohistochemically undetectable in the retinal pigment epithelia (RPE) and neural retinas of nondiabetic human eyes. Weak, focal staining for AR was present unilaterally in the RPE of 1 of 11 diabetic patients without pathologic ocular findings and in 43% of diabetic patients with mild ocular findings. Retinal positivity was found (unilaterally) in only 2 of 19 individuals from either of these mildly affected groups. Fifty-five percent of patients with background retinopathy demonstrated AR positivity in the RPE, and half of these expressed AR in the RPE of both eyes. Of the individuals with proliferative diabetic retinopathy, 87.5% showed bilateral staining in the RPE. Retinal positivity was present in 36% of background retinopathy and 75% of proliferative retinopathy cases, demonstrating a positive correlation between AR expression and the severity of the disorder. In weakly staining retinas, only the ganglion cell bodies, nerve fibers, and Müller cells were positive, whereas in intensely staining cases, virtually the entire retina, except for the rod outer segments, was positive. Eyes from patients who had had diabetes less than or equal to 6 yr were negative for AR, but those from long- term-diabetic patients (14-45 yr) manifested positively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde Reductase↗
PubMed1988

Digenetic trematodes of marine fishes of Okinawa, Japan.

Between May and September 1985, 348 fishes representing 50 families, 107 genera, and 152 species from the coastal waters of Okinawa were examined for digenetic flukes. Ten families (Lepocreadiidae, Opistholebetidae, Gyliauchenidae, Fellodistomidae, Acanthocolpidae, Opecoelidae, Bucephalidae, Cryptogonimidae, Syncoeliidae, and Hemiuridae), representing 29 genera and 34 species of digenetic flukes were recorded. Seven new geographic locality records and 25 new host records were established. Possibly 2 new species, one being a species of the genus Metadena from Meiacanthus grammistes and the other a species of the genus Mesolecitha from Plectorhynchus chaetodontoides, were detected. Most infections were of a single species, and although prevalence and intensity were low, host specificity was high. Only 3 of the 34 species identified transgressed family bounds in their definitive hosts.

Animals↗
PubMed1987

High glucose concentrations inhibit protein synthesis in retinal pigment epithelium in vitro.

There is mounting evidence suggesting functional and structural alterations in the retinal pigment epithelium (RPE) in experimental and clinical diabetes. In this study we examined the effect of high glucose concentrations on human RPE cells in vitro. After 24-hr incubation in media supplemented with glucose (19.5 mM, 25.5 mM, and 45.5 mM) and prepared both with and without osmotic adjustment, there was no significant effect on [3H]thymidine or [3H]uridine incorporation into TCA-precipitable material. There was, however, a significant decrease in [35S]methionine incorporation which became more marked with increasing glucose concentrations. This could not be attributed to increased osmolarity caused by the additional glucose as it occurred in isosmolar high glucose media. 3-O-methyl glucose, a non-metabolized glucose analog, did not have the same effect, suggesting that metabolism of glucose may be important. Resolution of newly synthesized proteins by gel electrophoresis and autoradiography suggests a generalized decrease in protein synthesis. These data suggest that elevated glucose levels cause a significant metabolic alteration in RPE cells in vitro.

Cell Division↗
PubMed1986

Admissions to a rural hospital in the West Nile District of Uganda over a 27 year period.

An analysis is presented of data on all 30 129 inpatient admissions to a mission hospital in the West Nile District of Uganda in the 27 year period from July 1951 to August 1978. For most of this period the hospital was staffed by the same two doctors. For each patient admitted, a record was made of their age (adult or child), sex, place of residence, duration of stay in hospital, diagnosis and vital status at discharge. The annual number of admissions increased steadily from around 300 in 1952 to over 1600 in 1966 and subsequently declined to about 900 in 1977. Sixty-five per cent of admissions were medical, 12% surgical, 11% obstetric and 9% gynaecological. Thirty per cent of admissions were children (aged 0-9 years). Forty-five per cent of admissions were from those resident in the same county as the hospital and another 20% were from an immediately adjacent county. Infective and parasitic conditions (including respiratory diseases) accounted for over 60% of admissions among children and over 38% of admissions among adults (excluding obstetric patients). The six most common causes of admission were: uncomplicated delivery (2308 admissions), pneumonia (2020), hookworm (1999), malaria (1806), schistosomiasis (1742) and diarrhoea (1041). In total 1960 deaths were recorded (6.5% of all admissions). High case fatality rates were observed for tetanus (61%), immaturity (54%), meningitis (38%), kwashiorkor (21%), other malnutrition (19%) and anaemia (19%). A striking increase in the number of admissions for measles was observed in the period 1976 to 1978. Admission rates for schistosomiasis (S. mansoni) appeared to be highest from counties adjacent to the Nile and 104 deaths were recorded among the 1742 patients with this as the primary diagnosis. Admissions for diabetes, as a percentage of all admissions increased from 0.2% in 1951-54 to 1.5% at the end of the study period. Marked seasonal variations in admission patterns were found for diarrhoea, measles, meningitis and respiratory infections, the last two, but not diarrhoea, being most common in the wettest months. Admissions for malaria showed no strong seasonal associations. Despite the limitations of hospital-based data, it is argued that the data analysed provide a reasonable indication of the important causes of severe morbidity and mortality in the district. Furthermore, some of the changes in admission patterns over time are likely to represent true changes in disease rates rather than artefacts of diagnosis or referral. The analyses presented indicate the value of simple record systems, carefully maintained.

Adolescent↗
PubMed1985

A temporal and spatial study of the synthesis and degradation of water-soluble and insoluble proteins in galactosemic rat lenses.

Events of synthesis and degradation of water-soluble and -insoluble rat lens proteins were examined during a 21-day period of galactose-induced cataractogenesis. Epithelial cells continued to synthesize both fractions of proteins throughout the duration of the experiment. There were few qualitative changes in the pattern of proteins expressed and the rate of synthesis did not decrease. In contrast, synthesis of both water-soluble and -insoluble proteins by the cortical cells decreased and then became totally inhibited indicating no selective or differential inhibition of synthesis of one protein fraction, but that both water-soluble and -insoluble proteins in the cortical cells are equally affected by the metabolic changes associated with galactose-induced cataractogenesis. The cells within the nuclear region of control lenses were capable of incorporating [35S]-methionine into protein. This synthesis was completely abolished in 7- and 14-day nuclear cells. Labeled proteins were found to be present in the 21-day nuclear preparation to a level almost three times greater than that observed in the control nucleus. Degradation was minimal in both fractions of epithelial proteins, whereas selective degradation of proteins from both fractions was apparent in 14- and 21-day cortical cells. At day 14, the water-soluble protein profile from nuclear cells became less complex with the loss of several major bands, but these bands as well as some unique bands appeared at day 21. The profile of water-insoluble nuclear proteins remained unchanged over 21 days.

Animals↗
PubMed1985

Effects of ketanserin on peripheral blood flow, haemorheology, and platelet function in patients with Raynaud's phenomenon.

Ketanserin, 40 mg b.i.d., or matching placebo were administered for 8 weeks each in a randomised double-blind crossover design to 23 patients with Raynaud's phenomenon. Ketanserin had no effect on Doppler arterial patency or blood flow at rest, 37 degrees C, 15 degrees C, or during recovery after cold challenge. Red cell deformability index and whole blood viscosity were not significantly affected by ketanserin treatment. In vivo bleeding time was prolonged on ketanserin (p less than 0.05) but beta-thromboglobulin and platelet factor 4 were unaffected. There was a nonsignificant decrease in platelet aggregation response to serotonin but no change at all with other aggregating agents on treatment with ketanserin.

Adult↗
PubMed1984

Endemic Kaposi's sarcoma: incidence and risk factors in the West Nile District of Uganda.

Out of 72 Kaposi's sarcoma patients diagnosed between 1951 and March 1976 at Kuluva Hospital, West Nile District, Uganda, 64 with known co-ordinates were plotted on a map. Sixty-two of these were noted to live at an altitude of 853 metres or more (greater than or equal to 2,800 feet). Twenty-four patients were thought to be still alive and visits were made to their homes. Space-time grouping of four cases was noted on two occasions, although analysis did not reveal statistically significant clustering. A case-control study employing an interview questionnaire with 32 variables was performed on 19 patients and their age- and sex-matched neighbourhood controls, and sera were collected from both groups and from their families for estimation of viral antibody titres. The results demonstrated that cases tended to be post-pubertal males, a high proportion of whom had been bitten by a blood-sucking insect identified as being similar to Haematopota. Both cases and controls had raised antibody levels to cytomegalovirus, but cases obtained their drinking water more commonly from rivers whereas controls tended to use water from springs, boreholes or pipes.

Adolescent↗