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Biomedical subjects

G R Hobbs

Publications and source records attributed to G R Hobbs.

29 records · Page 2Linked to original sources
PubMed1996

Enzyme-catalysed carbon-carbon bond formation: large-scale production of Escherichia coli transketolase.

Escherichia coli strain JM107/pQR700 possesses the vector pBGS18, a high copy number plasmid carrying kanamycin resistance, into which a 4.4 kb fragment containing the transketolase gene had been cloned. The bacterium was grown at 20 and 1000 1 scale for the production of transketolase. The specific growth rate was maintained at 0.15 h-1 until the bacterial concentration reached 20 g dry wt per litre at which point the culture was harvested. The clarified cell extract obtained after disruption of the bacteria in a high-pressure homogeniser contained about 230 U ml-1 of the enzyme, which represented about 40% of the total protein released. No further purification was done at large scale as the clarified cell extract could be used satisfactorily for biotransformations.

Biotechnology↗
PubMed1996

Trends in chlamydia and other sexually transmitted diseases in a university health service.

The incidence of sexually transmitted diseases in a primarily student-based patient population served by a university health service was reviewed because of the perception that the number of positive chlamydia tests was declining. The most striking finding that emerged was that there was, indeed, a persistent and steady decline in the rates of chlamydia infection over the study time period of 1989 to 1994. Other sexually transmitted diseases showed less definite declines or no significant change. The authors evaluated the number of positive chlamydia tests in the health service with symptoms suggestive of chlamydia infection. Of all university health service patients who tested positive for chlamydia, 48.8% were asymptomatic. A majority (75.2%) of the female patients who tested positive on their annual routine family-planning examination were also asymptomatic for chlamydia. Chlamydia-positive men presenting to the health service were far more likely to be symptomatic than were the women who were positive. Overall, a significant decrease in chlamydia occurred over the 5-year period in spite of an increasing enrollment, a fact that could perhaps be attributable to students' increased awareness of the risk of sexually transmitted infections and their use of condoms.

Chlamydia Infections↗
PubMed1996

Vigabatrin in childhood epilepsy: comparable efficacy for generalized and partial seizures.

Thirty-one patients, aged 12.6 +/- 5.6 years, with refractory seizures for 8 +/- 4.3 years, were treated with adjunctive vigabatrin. Twenty-four percent had a > 50% reduction in seizure frequency (95% one-sided confidence interval). Generalized myoclonic, atonic, and tonic clonic and partial, with and without secondary generalization, seizures were all reduced at a mean dose of 70 +/- 38 mg/kg/day. Comparison of vigabatrin therapy duration, for partial and generalized seizure groups, utilizing Kaplan-Meier methodology showed similar survival times. Vigabatrin therapy was ineffective in the four children with tuberous sclerosis. Transient somnolence, ataxia and dizziness were the most frequent side effects. A severe aggressive agitation occurred in three patients, and necessitated discontinuation of vigabatrin in one patient. Vigabatrin was as effective in generalized as in partial seizures in this study. Clinical utility may be limited by unacceptable behavioral side effects in some patients.

Adolescent↗
PubMed1996

Size of the corpus callosum in cerebral palsy.

It has been suggested that the size of the corpus callosum may have diagnostic significance in cerebral palsy, although this relationship is incompletely defined. Ninety-one patients with cerebral palsy had been studied by magnetic resonance imaging in the 5-year period from 1990 to 1994. Fifty-seven of these 91 patients had a technically appropriate midsagittal magnetic resonance image for quantitative morphometric analysis. The ratio of the area of the corpus callosum to the area of the supratentorial brain was compared to published age- and gender-specific norms. Imaging findings were correlated with clinical history and cause of cerebral palsy. The corpus callosum was of normal size in 43 patients and more than 2 standard deviations below the mean in 14 patients. The causes for cerebral palsy included hypoxic ischemic encephalopathy (32), cerebral dysgenesis (8), and porencephalic strokes (6); the etiology could not be established in 11 patients. The size of the corpus callosum was highly correlated with the cause of cerebral palsy, such that all patients with cerebral dysgenesis had hypoplasia of the corpus callosum (one-sided z test, p < 0.0001). Conversely, the callosum was of normal size in 32 of 38 patients with hypoxic ischemic encephalopathy and porencephalic strokes. The presence of a hypoplastic corpus callosum is highly associated with cerebral dysgenesis as a cause for cerebral palsy.

Adolescent↗
PubMed1996

Bone mineral density in geographically diverse adolescent populations.

OBJECTIVE: Measure bone mineral density (BMD) in healthy Newfoundland adolescents and determine whether BMD is comparable in geographically diverse adolescent populations. STUDY DESIGN: Lumbar spine BMD was measured by dual-energy radiograph absorptiometry in 26 healthy adolescents between ages 8 and 20 years. The age and gender of these subjects were used to predict BMD from equations derived from normative BMD data in six geographically diverse populations. The actual BMD value obtained for each subject was then compared with each of the six predicted BMD values for that adolescent using the Wilcoxon signed-ranks test. RESULTS: Actual lumbar spine BMD in Newfoundland adolescents was not significantly different from that predicted by age and gender if they were from California, Finland, France, North Carolina, and Switzerland. Only the prediction based on the Spanish population resulted in a 4% greater BMD than was actually measured in the Newfoundland adolescents. CONCLUSIONS: Lumbar spine BMD measurements for most healthy adolescent populations, as in adults, are comparable despite geographic diversity. Thus, generation of institution-specific normative BMD data may not be necessary for most adolescent populations.

Adolescent↗
PubMed1995

Longitudinal head growth in developmentally normal preterm infants.

OBJECTIVE: To determine growth in head circumference from birth to 18 months of age in normal infants with low birth weight. METHODS: Healthy, appropriate-for-gestational-age, singleton, white infants weighing less than or equal to 2500 g at birth and with normal development at 18 months of age were included in this study. Serial measurements of head circumference (corrected for gestational age) from 450 eligible infants were compared with reference data for head circumference. RESULTS: Longitudinal measurements of head circumference for infants weighing more than 1000 g at birth were similar to reference data for term infants. Head measurements for infants weighing less than or equal to 1000 g at birth were notably smaller than the measurements in the reference data. A cubic spline curve drawn through the head circumference measurements between birth and age 18 months (corrected for gestational age) for infants weighing less than or equal to 1000 g at birth was significantly (P < .001) below the curve for infants weighing more than 1000 g at birth. At age 18 months, the mean difference in head circumference between the group weighing less than or equal to 1000 g at birth and the weights in the reference data was 1.6 cm (P < .01). (Data were analyzed with Wilcoxon's signed rank test.) CONCLUSIONS: These data show that head circumference grids are appropriate for observing head growth in infants with a birth weight more than 1000 g. However, head circumference growth for normal infants with birth weight less than or equal to 1000 g does not "catch up" with that of larger premature infants or term infants.

Birth Weight↗
PubMed1995

Effect of carbamazepine and valproate on bone mineral density.

OBJECTIVE: To examine the effect of carbamazepine and valproate monotherapy on bone mineral density in children. METHODS: Axial (second, third, and fourth lumbar vertebrae) and appendicular (distal third of radius) bone mineral density was measured by dual-energy x-ray absorptiometry in 27 healthy children and 26 children with uncomplicated idiopathic epilepsy treated with either carbamazepine (n = 13) or valproate (n = 13) for more than 18 months. Control subjects and patients were similar with respect to age, race (all white), and geographic area, and had no dietary restrictions, neurologic impairment, or physical handicaps. RESULTS: Subjects were seizure-free for more than 6 months on a regimen of carbamazepine or valproate therapy, and had mean serum trough levels of 6.88 +/- 2 micrograms/ml and 72.04 +/- 45.6 micrograms/ml, respectively. Dietary calcium intake was similar in control and treated groups. After correction for gender and age, children treated with valproate had a 14% (p = 0.003) and 10% (p = 0.005) reduction in bone mineral density at the axial and appendicular sites, respectively. The reduction in bone mineral density increased with the duration of valproate therapy. Carbamazepine did not significantly reduce bone mineral density. CONCLUSION: Valproate montherapy, but not carbamazepine therapy, significantly reduces axial and appendicular bone mineral density in children with idiopathic epilepsy and may increase their risk of osteoporotic fractures.

Absorptiometry, Photon↗
PubMedDate not supplied

Data mining and healthcare informatics.

OBJECTIVE: To acquaint members of the Academy with a relatively recent development in the area of data exploration and statistical analysis. METHODS: A review of the concepts and methods inherent in data-mining with a special emphasis on the those methods applicable to predictive modeling. RESULTS: Data-mining is demonstrated to be a useful tool for researchers in those circumstances where large amounts of information are available. CONCLUSIONS: With the advent and proliferation of on-line data collection, truly massive databases are now available to health care researchers. In that situation, data-mining methods yield some unique opportunities to researchers who wish to develop prediction models and to establish associations.

Database Management Systems↗
PubMedDate not supplied

An estimate of prostate cancer prevalence for a demographically similar workforce population.

To obtain an estimate of prostate cancer prevalence when screening is applied to a workforce, we conducted a search of the English world literature from West Virginia University. Thirty-one papers which met selection criteria for screening were followed by histopathologic diagnosis. Publications using Prostate Specific Antigen (PSA) as a screening test were reviewed. The data from these papers were combined. Population characteristics were then selected to represent the demographics of a working population. Prostate cancer prevalence estimates for the demographics of a working population were calculated using a weighted mean after relevant studies lacked homogeneity and therefore failed meta-analysis. The expected prevalence of prostate cancer in a workplace surveillance population is 2.03% (95% C.I. from 1.69% to 2.37%). This information is useful to entities considering workplace surveillance. Selection bias, geographic location, and uncertainty in prediction of a representative workforce population may strongly influence estimates.

Aged↗