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Biomedical subjects

D T Jones

Publications and source records attributed to D T Jones.

At least 145 records · Page 8Linked to original sources
PubMed1987

Childhood asthma in New Zealand.

To determine the prevalence and severity of childhood asthma in New Zealand we studied 815 children from a birth cohort by questionnaire, clinical examination and pulmonary physiological measurements at age 9 years. More than 19% of the sample had experienced wheezing in the previous year, and 11% had wheezed in the month before assessment. In all, 220 of 815 children (27.1%) had had wheezing episodes by age 9; in 34 (4.2%) episodes had been of sufficient frequency to warrant regular anti-asthma treatment. Only 32% of all wheezing children were reported by their parents to suffer from asthma, and, in groups matched for frequency of symptoms, treatment given for wheezing was influenced strongly by whether or not the label of 'asthma' had been given. The detailed history provided most information useful in diagnosing asthma; clinical examination, peak flow records, spirometry and bronchial provocation testing provided only limited additional information. A wide spectrum of frequency and severity of recurrent wheezing disorders was evident in New Zealand children. Throughout all degrees of severity, prevalence rates appeared higher than those reported in studies from the United Kingdom.

Asthma↗
PubMed1986

An incentive management plan for hospital-based physicians.

Arthur D. Little, Inc., has developed an incentive management program for salaried, hospital-based physicians. The program is based on the tracking of physician productivity through the assignment of work units for both routine inpatient care and all medically performed tests and outpatient procedures. A monetary pool based on increases in the hospital's profitability over a base year is divided among physicians on the basis of their relative productivity throughout the year. Administratively assigned work units can be used to give physicians credit for activities which benefit the institution but which are not revenue producing. The system puts incentives in place for physicians to increase revenues while holding down costs. The main feature of the incentive system is a bonus pool, the size of which is based on hospital net income. A reporting application was developed that downloads data from the hospital's service bureau data-processing vendor, preprocesses the data through a C program, and produces reports through an extremely user-friendly, menu-driven, spreadsheet-based program.

Efficiency↗
PubMed1986

Cloning and expression of Clostridium acetobutylicum endoglucanase, cellobiase and amino acid biosynthesis genes in Escherichia coli.

Clostridium acetobutylicum P262 endoglucanase and cellobiase genes, cloned on a 4.9 kb DNA fragment in the recombinant plasmid pHZ100, were expressed from their own promoter in Escherichia coli. Active carboxymethylcellulase and cellobiase enzymes were produced, but there was no degradation of Avicel. The endoglucanase activities observed in cell extracts of E. coli HB101(pHZ100) differed in their pH and temperature optima from those previously reported for C. acetobutylicum P270. Complementation of E. coli arg and his mutations by cloned C. acetobutylicum DNA was also observed.

Amino Acids↗
PubMed1986

Characterization, Biosynthesis, and Regulation of Granulose in Clostridium acetobutylicum.

Synthesis of granulose was investigated in 15 solvent-producing Clostridium strains. Only one of the strains did not produce granulose. The structure of granulose in Clostridium acetobutylicum P262 consisted of a high-molecular-weight polyglucan containing only (1-->4) linked d-glucopyranose units. Biosynthesis of granulose in C. acetobutylicum P262 was dependent on ADPglucose pyrophosphorylase, and granulose synthase and mutants defective in granulose accumulation lacked either one or both enzyme activities. Granulose-positive revertants exhibited both enzyme activities. ADPglucose pyrophosphorylase and granulose synthase were not subject to allosteric control by metabolites. Granulose accumulation and the biosynthetic enzyme activities were initiated immediately before the pH breakpoint and were detected in cells only at the end of the exponential growth phase. Granulose accumulation did not occur under conditions of nitrogen limitation, excess carbon, or excess energy.

Journal Article↗
PubMed1986

Cloning, Expression, and Purification of Glutamine Synthetase from Clostridium acetobutylicum.

A glutamine synthetase (GS) gene, glnA, from the gram-positive obligate anaerobe Clostridium acetobutylicum was cloned on recombinant plasmid pHZ200 and enabled Escherichia coli glnA deletion mutants to utilize (NH(4))(2)SO(4) as a sole source of nitrogen. The cloned C. acetobutylicum gene was expressed from a regulatory region contained within the cloned DNA fragment. glnA expression was subject to nitrogen regulation in E. coli. This cloned glnA DNA did not enable an E. coli glnA ntrB ntrC deletion mutant to utilize arginine or low levels of glutamine as sole nitrogen sources, and failed to activate histidase activity in this strain which contained the Klebsiella aerogenes hut operon. The GS produced by pHZ200 was purified and had an apparent subunit molecular weight of approximately 59,000. There was no DNA or protein homology between the cloned C. acetobutylicum glnA gene and GS and the corresponding gene and GS from E. coli. The C. acetobutylicum GS was inhibited by Mg in the gamma-glutamyl transferase assay, but there was no evidence that the GS was adenylylated.

Journal Article↗
PubMed1986

Prevalence of bronchial reactivity to inhaled methacholine in New Zealand children.

The prevalence of bronchial hyperreactivity to inhaled methacholine and of a clinical history of symptoms of asthma was determined in a birth cohort of 9 year old New Zealand children. A history of current or previous recurrent wheezing was obtained in 220 of 815 children. Of 800 who had spirometric tests, 27 (3.4%) had resting airflow obstruction (FEV1/FVC less than 75%). Methacholine challenge was undertaken without problem in 766 children, the abbreviated protocol being based on five breaths and four concentrations. A fall in FEV1 of more than 20% was observed in 176 children (23% of challenges, 22% of the full cohort) after inhalation of methacholine in concentrations of up to 25 mg/ml. The prevalence of bronchial reactivity in children with symptoms was related to the frequency of wheezing episodes in the last year, and the degree of reactivity to the interval since the last episode. Sixty four children (8.0%) with no history of wheeze or recurrent dry cough were, however, also responsive to methacholine 25 mg/ml or less, while 35% of children with current or previous wheezing did not respond to any dose of methacholine. Bronchial challenge by methacholine inhalation was not sufficiently sensitive or specific to be useful as a major criterion for the diagnosis of asthma in epidemiological studies. The occurrence of airway reactivity in children without symptoms of asthma, however, raises the possibility that adult onset asthma and the development of airways obstruction in some subjects with chronic bronchitis could have origins in childhood.

Asthma↗
PubMed1986

Gene transfer, recombination and gene cloning in Clostridium acetobutylicum.

Although Clostridium acetobutylicum has been used for over 70 years for the industrial production of solvents, it is only recently that studies on the genetics of this organism have been initiated. Recent advances in the development of genetic transfer systems as well as the cloning and expression of genes from this organism in Escherichia coli are reviewed.

Cloning, Molecular↗
PubMed1985

Nemaline myopathy with associated cardiomyopathy. Report of clinical and detailed autopsy findings.

We describe the clinical features and autopsy findings of an adult patient who had nemaline myopathy and an associated progressive cardiomyopathy. The spinal cord and the results of morphometric analysis of multiple peripheral nerves were normal. There was probable intrafusal fiber involvement, in addition to the typical histopathologic features of extrafusal fibers. Cardiac dysfunction was a prominent clinical and autopsy feature, but it has been infrequently recognized in this entity. Our findings suggest that there is a poor correlation between clinical and pathologic features in this disorder, and they support the need for careful cardiac evaluation of affected patients. Furthermore, the constellation of features favors a myopathic basis for the disease, in contradistinction to some previously expressed views.

Adult↗
PubMed1985

Isolation and physiological characterization of mitomycin C-sensitive/UV-sensitive mutants in Bacteroides fragilis.

Mutants of Bacteroides fragilis sensitive to mitomycin C were isolated after mutagenesis with ethyl methane sulphonate. One mutant (MTC25) was markedly sensitive to mitomycin C but was unaffected as regards UV sensitivity; another mutant (UVS9) was sensitive to UV radiation but was only moderately sensitive to mitomycin C. Caffeine decreased the survival after UV-irradiation of the wild-type, MTC25 and UVS9 strains by the same relative amount. Aerobic liquid holding recovery occurred in each of the three strains. The MTC25 and UVS9 mutants showed reduced host cell phage reactivation. The wild-type, MTC25 and UVS9 strains all showed UV- and H2O2-induced phage reactivation. The physiological characterization of the MTC25 and UVS9 mutants indicates that it is possible to differentiate between mechanisms for the repair of mitomycin C- and UV-induced DNA damage in B. fragilis.

Bacteriophages↗
PubMed1985

Immobilized Clostridium acetobutylicum P262 Mutants for Solvent Production.

The production of acetone, butanol, and ethanol by two immobilized, sporulation-deficient (spo) Clostridium acetobutylicum P262 mutants which were held in the solventogenic phase was investigated. The spoA2 mutant, which was an early-sporulation mutant and did not form a forespore septum, produced higher solvent yields than did the spoB mutant which was a late-sporulation mutant and was blocked at a stage after forespore septum formation. The spoA2 mutant was also granulose and capsule negative. In a conventional batch fermentation, the wild-type strain produced 15.44 g of solvents per liter after 50 h at a productivity of 7.41 g of solvents per liter per day. The spoA2 mutant produced 15.42 g of solvents per liter at a productivity of 72.4 g of solvents per liter per day, with a retention time of 2.4 h in a continuous immobilized cell system employing a fluidized bed reactor. This represents a major advance, since the immobilization of wild-type cells showed similar increases in productivity but a ca. fivefold reduction in final product concentrations.

Journal Article↗
PubMed1985

Experience in implementation of clinical guidelines: pre-operative chest radiography in non-cardiopulmonary surgery.

In 1983, the All-Wales Management Efficiency Group (All-Wales MEG) published a report on pre-operative chest radiography (POCR) and made recommendations about the use of POCR in district health authorities in Wales. The object of this paper is to describe experience within one Welsh authority, highlighting both perceived problems and the difficulties encountered in the implementation of these recommendations.

Hospitals↗
PubMed1985

Physical exercise and resistive breathing training in severe chronic airways obstruction--are they effective?

Twenty-one patients with severe chronic irreversible airflow obstruction (FEV1 consistently less than 1.2 l) were allocated randomly to one of two training programmes designed to reduce respiratory disability or a placebo training control group. Daily structured physical exercise, twice daily inspiratory muscle training by resistive breathing, or daily placebo training were undertaken for 10 weeks, and the effects on lung function, exercise capacity, respiratory symptoms and psychological state compared. Maximal work achieved on a progressive bicycle exercise test was significantly increased in all groups (36%, 23% and 34% respectively) and global improvement in mood also occurred. There was no significant change in respiratory symptom score, static lung function tests or 12 min walking distance. Neither form of active treatment showed superiority over placebo training.

Airway Obstruction↗
PubMed1984

Exercise-induced asthma: comparison of cromoglycate powder and aerosol four hours before exercise.

To establish whether sodium cromoglycate delivered by pressurised aerosol was more effective than sodium cromoglycate powder in preventing exercise-induced asthma four hours after drug administration, eight subjects known to be protected by sodium cromoglycate taken immediately pre-exercise, underwent delayed exercise challenge following double-blind premedication with sodium cromoglycate powder, sodium cromoglycate aerosol and placebo. The maximum fall in FEV1 induced by exercise four hours after inhaling sodium cromoglycate was modified slightly by sodium cromoglycate powder and by a smaller amount, sodium cromoglycate aerosol, compared with the unpremedicated run, but the calculated protection provided by sodium cromoglycate was not significantly different from that given by placebo. It was concluded that asthmatics should not expect significant suppression of exercise-induced bronchoconstriction four hours after the last dose of either cromoglycate powder or aerosol.

Adolescent↗
PubMed1984

Effect of UV irradiation on macromolecular synthesis and colony formation in Bacteroides fragilis.

Irradiation of Bacteroides fragilis cells with far-UV light resulted in the immediate, rapid and extensive degradation of DNA which continued for 40 to 60 min after irradiation. During the degradation phase, DNA synthesis was decreased but was never totally inhibited. DNA degradation after irradiation was inhibited by chloramphenicol and caffeine. DNA synthesis in irradiated cells was reduced by chloramphenicol but resumed after 100 min at the same exponential rate as in irradiated cells without chloramphenicol. Irradiated cells continued to synthesize DNA for 40 min in the presence of caffeine but after this time DNA synthesis was completely inhibited and never recovered. RNA and protein synthesis were decreased by UV irradiation and the degree of inhibition was proportional to the UV dose. Colony formation was not affected immediately by UV irradiation and continued for a dose-dependent period before inhibition. There was an inverse relationship between UV dose and inhibition of colony formation which occurred sooner in cells irradiated with lower doses of UV light. The characteristics of DNA synthesis in B. fragilis cells after UV irradiation differ from those in wild-type Escherichia coli cells, where DNA synthesis is stopped immediately by UV irradiation, but resemble those in E. coli recA mutant cells where extensive degradation occurs following UV irradiation.

Bacteroides fragilis↗
PubMed1984

Relation between pica and blood lead in areas of differing lead exposure.

Surveys were conducted in four areas in Wales with differing degrees of environmental lead. In two areas the source of the lead was traffic and in one it was spoil from lead mining in the past. The fourth area, which served as a control, was a village remote from heavy traffic, industry, and lead mining. Various environmental samples were taken, and children aged 1-3 years and their mothers were studied. Blood lead concentrations were raised in the lead mining area, and within the areas defined by traffic flow the blood lead concentrations of the mothers showed a gradient. Pica in the children, assessed by a questionnaire, showed no relation with blood lead, but the amount of lead removed from the children's hands with 'wet wipes' was an important contributor to blood lead concentrations.

Adult↗