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Biomedical subjects

E A Edwards

Publications and source records attributed to E A Edwards.

At least 19 recordsLinked to original sources
PubMed1999

Anaerobic benzene biodegradation linked to nitrate reduction.

Benzene oxidation to carbon dioxide linked to nitrate reduction was observed in enrichment cultures developed from soil and groundwater microcosms. Benzene biodegradation occurred concurrently with nitrate reduction at a constant ratio of 10 mol of nitrate consumed per mol of benzene degraded. Benzene biodegradation linked to nitrate reduction was associated with cell growth; however, the yield, 8.8 g (dry weight) of cells per mol of benzene, was less than 15% of the predicted yield for benzene biodegradation linked to nitrate reduction. In experiments performed with [14C]benzene, approximately 92 to 95% of the label was recovered in 14CO2, while the remaining 5 to 8% was incorporated into the nonvolatile fraction (presumably biomass), which is consistent with the low measured yield. In benzene-degrading cultures, nitrite accumulated stoichiometrically as nitrate was reduced and then was slowly reduced to nitrogen gas. When nitrate was depleted and only nitrite remained, the rate of benzene degradation decreased to almost zero. Based on electron balances, benzene biodegradation appears to be coupled more tightly to nitrate reduction to nitrite than to further reduction of nitrite to nitrogen gas.

Anaerobiosis↗
PubMed1997

A long-term comparison between enalapril and captopril on insulin sensitivity in normotensive non-insulin dependent diabetic volunteers.

BACKGROUND: There are conflicting reports about the effects of angiotensin converting enzyme inhibitors on insulin sensitivity and glycaemic control. In addition, the chronic effects of ACEI on insulin sensitivity in normotensive but insulin resistant individuals have been controversial. AIM: To determine the long-term effects of low-dose captopril or enalapril on insulin sensitivity and lipid parameters in normotensive non-insulin dependent diabetic volunteers. METHODS: Twenty-eight normotensive non-insulin dependent diabetes mellitus subjects on diet alone or diet plus oral hypoglycaemic agents were randomized in a single-blind cross-over study to receive either captopril (12.5 mg daily) or enalapril (5 mg daily). Initially, captopril was compared with enalapril for 28 days with a 28-day washout period between drug regimens. For the long-term study, the subjects then remained on the second ACEI for a further 11 months. Insulin sensitivity was measured using the isoglycaemic hyperinsulinaemic clamp (insulin infusion rate 20 mIU/kg/min) at the start and completion of each part of the cross-over study and then at 3, 6 and 12 months of drug therapy. Fasting glucose, insulin, HbA1, lipids and lipoproteins were measured at the start of each clamp. RESULTS: No first or second order carry-over effects were demonstrated between the ACEIs. No differences were detected between enalapril and captopril on insulin sensitivity at any of the time points. Statistically significant hypotension was avoided, and at doses used the ACEIs did not modify any parameters of glycaemic control over the 12-month study period. There were no significant alterations in plasma cholesterol, triglycerides, HDL cholesterol or Apo A1 levels during the study. CONCLUSIONS: Long-term low-dose ACEIs (captopril/enalapril) do not modify insulin sensitivity, glycaemic control or lipids in normotensive non-insulin dependent diabetic subjects.

Aged↗
PubMed1995

The effects of increasing doses of enalapril on insulin sensitivity in normotensive non-insulin dependent diabetic subjects.

BACKGROUND: There are conflicting reports about the effects of ACE inhibitors (ACEI) on insulin sensitivity and glycaemic control. Most studies have used a standard high dose of an ACEI but there have been no studies reported to establish whether any changes in glycaemic control or insulin sensitivity associated with ACEI are dose-related. AIM: To examine the effect of increasing doses of enalapril on insulin sensitivity in normotensive non-insulin dependent diabetic subjects. METHODS: The effects of increasing doses of enalapril on insulin sensitivity in ten normotensive non-insulin dependent diabetic subjects were measured, using the hyperinsulinaemic isoglycaemic clamp technique. Following a baseline study, enalapril was commenced at 5 mg daily and increased to 10 mg daily then 20 mg daily at 14 day intervals. Repeat studies were undertaken after 14 days at each dosage. RESULTS: There was a significant dose-related reduction of systolic blood pressure with enalapril. In contrast enalapril at 5-20 mg daily produced no significant changes in insulin mediated glucose uptake (M-value) or insulin sensitivity index (ISI). CONCLUSIONS: These findings indicate that in this insulin resistant population of normotensive non-insulin dependent diabetics, angiotensin converting enzyme inhibition with enalapril has no significant effect on insulin mediated glucose uptake.

Aged↗
PubMed1994

Anaerobic degradation of toluene and o-xylene by a methanogenic consortium.

Toluene and o-xylene were completely mineralized to stoichiometric amounts of carbon dioxide, methane, and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was creosote-contaminated sediment from Pensacola, Fla. The adaptation periods before the onset of degradation were long (100 to 120 days for toluene degradation and 200 to 255 days for o-xylene). Successive transfers of the toluene- and o-xylene-degrading cultures remained active. Cell density in the cultures progressively increased over 2 to 3 years to stabilize at approximately 10(9) cells per ml. Degradation of toluene and o-xylene in stable mixed methanogenic cultures followed Monod kinetics, with inhibition noted at substrate concentrations above about 700 microM for o-xylene and 1,800 microM for toluene. The cultures degraded toluene or o-xylene but did not degrade m-xylene, p-xylene, benzene, ethylbenzene, or naphthalene. The degradative activity was retained after pasteurization or after starvation for 1 year. Degradation of toluene and o-xylene was inhibited by the alternate electron acceptors oxygen, nitrate, and sulfate. Degradation was also inhibited by the addition of preferred substrates such as acetate, H2, propionate, methanol, acetone, glucose, amino acids, fatty acids, peptone, and yeast extract. These data suggest that the presence of natural organic substrates or contaminants may inhibit anaerobic degradation of pollutants such as toluene and o-xylene at contaminated sites.

Anaerobiosis↗
PubMed1994

A method for detection of aromatic metabolites at very low concentrations: application to detection of metabolites of anaerobic toluene degradation.

Difficulties inherent in working with anaerobic microorganisms and mixed cultures have hampered efforts to detect and identify metabolites of anaerobic degradation of monoaromatic compounds. Isotope-trapping experiments and analysis using a high-performance liquid chromatograph equipped with a flow-through radioactivity detector were used to detect very low concentrations of metabolites. Data obtained by this method suggest that toluene was degraded via methyl hydroxylation by a mixed methanogenic culture.

Anaerobiosis↗
PubMed1993

Cholecystectomy: a study of patient satisfaction.

A prospective study of 77 patients undergoing open cholecystectomy was undertaken to establish the degree of satisfaction experienced by these patients. Specific symptoms were recorded preoperatively and at one year postoperatively. Two patients died from unrelated diseases during the year of follow-up and were excluded from the analysis. All symptoms inquired about reduced in frequency postoperatively, the best cures being achieved for jaundice, upper abdominal colic, fatty food intolerance and back/shoulder pain. A third of patients developed at least one new symptom during the year of follow-up. Seventy-seven per cent graded themselves either completely or well satisfied. It was not possible to predict from preoperative symptoms those who would be dissatisfied or those who would develop a new symptom. This study refutes recent suggestions that up to 50% of patients are dissatisfied with cholecystectomy and provides data which may be used to counsel patients preoperatively.

Cholecystectomy↗
PubMed1992

Anaerobic degradation of toluene and xylene by aquifer microorganisms under sulfate-reducing conditions.

Toluene and the three isomers of xylene were completely mineralized to CO2 and biomass by aquifer-derived microorganisms under strictly anaerobic conditions. The source of the inoculum was gasoline-contaminated sediment from Seal Beach, Calif. Evidence confirming that sulfate was the terminal electron acceptor is presented. Benzene and ethylbenzene were not degraded under the experimental conditions used. Successive transfers of the mixed cultures that were enriched from aquifer sediments retained the ability to degrade toluene and xylenes. Greater than 90% of 14C-labeled toluene or 14C-labeled o-xylene was mineralized to 14CO2. The doubling time for the culture grown on toluene or m-xylene was about 20 days, and the cell yield was about 0.1 to 0.14 g of cells (dry weight) per g of substrate. The accumulation of sulfide in the cultures as a result of sulfate reduction appeared to inhibit degradation of aromatic hydrocarbons.

Anaerobiosis↗
PubMed1992

Complete mineralization of benzene by aquifer microorganisms under strictly anaerobic conditions.

Benzene was mineralized to CO2 by aquifer-derived microorganisms under strictly anaerobic conditions. The degradation occurred in microcosms containing gasoline-contaminated subsurface sediment from Seal Beach, California, and anaerobic, sulfide-reduced defined mineral medium supplemented with 20 mM sulfate. Benzene, at initial concentrations ranging from 40 to 200 microM, was depleted in all microcosms and more than 90% of 14C-labeled benzene was mineralized to 14CO2.

Anaerobiosis↗
PubMed1992

Molecular characterization of glutathione reductase cDNAs from pea (Pisum sativum L.).

A cDNA for pea glutathione reductase has been cloned and sequenced. The derived amino acid sequence of 562 residues shows a high degree of homology to the previously published GR sequences from human erythrocytes and from two prokaryotes: Escherichia coli and Pseudomonas aeruginosa. The pea enzyme differs from other GRs in having an N-terminal leader sequence of about 60-70 residues which may be a chloroplast transit peptide and a 20 amino acid C-terminal extension of unknown function.

Amino Acid Sequence↗
PubMed1988

Controlled clinical trial of a regimen of two durations for the treatment of isoniazid resistant pulmonary tuberculosis.

Patients with pulmonary tuberculosis who were failures of primary chemotherapy with strains resistant to isoniazid or to isoniazid and streptomycin were allocated at random to receive a regimen of rifampicin and ethambutol for 6 (4RE) or 9 months (7RE), supplemented in both treatment series by streptomycin plus pyrazinamide for the first 2 months. The patients were treated in hospital for the first 2 months and thereafter treatment was supervised on a daily basis in the nearest health institution by an appointed member of staff or at home by responsible members of the community. A total of 306 patients was admitted and 226 patients remained for analysis at the end of chemotherapy, 179 with a strain resistant to isoniazid alone and 47 with a strain resistant to isoniazid and streptomycin. There were only two failures at the end of chemotherapy, one in the 6-month series who had resistance to both isoniazid and streptomycin pretreatment, and one in the 9-month series who had resistance to isoniazid alone. For the 144 patients with initial resistance to isoniazid alone assessed up to 30 months, the relapse rates were low in both series: 4% for the 72 patients in the 6-month series and 3% for the 72 patients in the 9-month series. However, for the 34 patients with resistance to both drugs, three of the 14 in the 6-month but none of 20 in the 9-month series relapsed.

Adolescent↗
PubMed1987

A study of the use of maternity and child welfare clinics in case-finding for pulmonary tuberculosis in Kenya.

This investigation is the seventh in a series of case-finding studies in Kenya. It explores the potential value of questioning mothers attending maternity and child welfare (M & CW) clinics to identify tuberculosis suspects (individuals aged 6 years or more with a cough for 1 month or more or hemoptysis) living in their households. The study was carried out in all the eight M & CW clinics in two divisions (populations 86,000 and 112,000) of two different districts. The mothers were asked to give a standard letter, which explained the possible importance of a chronic cough, to each suspect they identified and invited the suspect to attend the district hospital chest clinic. Each suspect attending the clinic was entered in a special register and two sputum specimens were collected. For those who failed to attend, the specimens were collected at a home visit. Of the total of 342 suspects living in the two study areas who were registered at the M & CW clinics during 1 year, 261 were identified by the mothers but 19 denied having received the standard letter. The remaining 81 had not been identified by mothers but had attended the M & CW clinics on their own initiative. Of the 242 suspects who received the letter, 89 (39%) attended the hospital chest clinic, 74% within a week of the letter being issued from the M & CW clinic. The main reasons given for not attending the hospital chest clinic by the remaining suspects were financial or because their cough had improved or disappeared. Sputum was collected from 238 suspects and examined bacteriologically: in six (2.5%) it was positive for tubercle bacilli on smear and culture and in a further two (0.8%) the sputum was positive on culture only. Of those attending the hospital chest clinic 2.9% were smear- and culture-positive and 4.7% were culture positive. This method of case-finding has yielded disappointing results, for only 4% of the estimated annual incidence of smear-positive cases was detected.

Adult↗
PubMed1985

Studies of case-finding for pulmonary tuberculosis in outpatients at 4 district hospitals in Kenya.

This investigation is the sixth in a series of case-finding studies in Kenya. It explores the potential for case-finding by the identification of tuberculosis suspects (individuals with a cough for 1 month or more) through careful screening of general outpatients attending 4 district hospitals for the first time. Of 2299 suspects identified among 87 845 new outpatients attending the hospitals, 4.7% had culture-positive pulmonary tuberculosis, 3.6% having sputum positive on smear as well. In the 3 hospitals with radiographic facilities, 1.3% of suspects (whose sputum was negative on culture) were considered on review of their clinical history and chest radiograph by an independent assessor to have radiographically active tuberculous lesions and a further 2.5% to have inactive lesions. The proportion of bacteriologically positive cases per 1000 of the general population aged 6 years or more decreased as the distance of their homes from the hospital increased (P less than 0.001 for the trend). However, the proportion of cases per 1000 of the suspects identified increased as the distance of their homes from the hospital increased (P less than 0.001 for the trend). History of cough for between 1 and 12 months was the most useful factor for the identification of cases of tuberculosis among the suspects, and would have identified 92% of the smear-positive cases from the examination of 70% of the suspects; a history of weight loss identified 84% of the smear-positive cases from the examination of 64% of the suspects. A history of weight loss and/or a history of cough for between 1 and 12 months would have detected all the smear-positive cases from the examination of 89% of the suspects. The proportion of bacteriologically positive cases in the younger suspects aged 9-32 years (who had been eligible for a mass BCG campaign) was greater among the non-vaccinated than among the vaccinated suspects, 4.9% and 2.3% respectively (P=0.04), implying protection from vaccination of the order of 50%.

Adolescent↗
PubMed1984

Scope and limitations of collateral circulation. Presidential address.

The human body, possessing no true end arteries, is capable of furnishing some collateral vessels for any arterial, venous, or lymphatic obstruction. In places, only capillary anastomoses are immediately available and ischemia may be profound. We have learned to support organs like the heart, brain, or liver while small communications enlarge to increase the flow of blood or lymph. Even in the retina, some success has been obtained by retrograde perfusion through the supra-orbital artery. Supplemental flow, ie, blood varying in content or pressure--such as bronchial blood substituting for pulmonary blood--carries some detriment in the form of diminished function or the rupture of thin-walled vessels.

Arterial Occlusive Diseases↗
PubMed1984

Detection of Neisseria meningitidis group A, Haemophilus influenzae type b, and Streptococcus pneumoniae antigens in cerebrospinal fluid specimens by antigen capture enzyme-linked immunosorbent assays.

Antigen capture enzyme-linked immunosorbent assay was compared to coagglutination and counterimmunoelectrophoresis for the detection of meningococcal, Haemophilus, and pneumococcal antigens. Enzyme-linked immunosorbent assay detected 1 ng of purified meningococcal and Haemophilus polysaccharides per ml and 5 ng of pneumococcal polysaccharide per ml; coagglutination detected 20, 25, and 30 ng/ml, respectively, of these polysaccharides; and counterimmunoelectrophoresis detected 10, 50, and 60 ng/ml. Double-antibody sandwich-antiglobulin enzyme-linked immunosorbent assays, which employed antibodies produced in two animal species, differentiated 100% of the cerebrospinal fluid (CSF) specimens from meningococcal meningitis patients and 95% of the CSFs from Haemophilus patients from heterologous control CSFs. Double-antibody sandwich procedures, which use the same antiserum preparation for coating the wells of microtiter plates and for alkaline phosphatase-conjugated immunoglobulin, differentiated meningococcal CSFs from control specimens but were unable to effectively differentiate the Haemophilus or pneumococcal specimens from control CSFs. Coagglutination detected specific antigen in 92% of the meningococcal CSFs, 80% of the Haemophilus CSFs, and 92% of the pneumococcal specimens. The comparable percentages for counterimmunoelectrophoresis were 76, 95, and 71%.

Agglutination Tests↗
PubMed1984

Study of case-finding for pulmonary tuberculosis in outpatients complaining of a chronic cough at a district hospital in Kenya.

This investigation is the fifth in a series of case-finding studies in Kenya. It explores the potential for case-finding by the identification of persons with suspected tuberculosis (persons with a cough for 1 month or more) through careful screening of general outpatients attending a district hospital. Of 601 suspects identified among 20,756 new outpatients attending hospital during a period of 11 wk, 5.6% were considered by an independent assessor to have active pulmonary tuberculosis (2.2% with sputum positive on both smear and culture, 1.2% on culture only, and 2.2% negative sputum but radiographically active lesions). A further 2.0% were considered to have inactive tuberculosis. This method of case-finding appears to be uniformly effective within a radius of approximately 9 miles of the hospital, becoming less effective outside this range. There were certain important diagnostic pointers. There was an excess of tuberculosis cases in males, in those with weight loss, in those with a history of cough of less than a year, in those with a history of hemoptysis, and in those 35 yr of age or older. This investigation provides additional support to our previous studies, which demonstrated serious problems of case-finding in the peripheral health units and suggests that unless the infrastructure of primary health care at the periphery can be improved, the policy should be to diagnose tuberculosis in the district hospital and to operate a simple referral system for persons with suspected tuberculosis from the periphery.

Adolescent↗