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Biomedical subjects

J M Bell

Publications and source records attributed to J M Bell.

At least 55 records · Page 3Linked to original sources
PubMed1994

A comparison of the relation between oxygen uptake and heart rate during different styles of aerobic dance and a traditional step test in women.

The oxygen uptake and heart rate in various styles of dance and in a graded step test have been compared in ten healthy women aged [mean (SD)] 34 (5) years. Dance was choreographed into progressively more energetic sequences typical of community classes, and videotaped. Oxygen uptake was assessed using a respirometer carried in a back-pack. Each of the two tests (dance and step) took 15-20 min and measurements were made in randomised balanced order on the same day. The mean oxygen costs of dance ranged from 1.29 l.min-1 for low impact style to 1.83 l.min-1 for high impact style with arm work; mean heart rates were 135 and 174 beats.min-1 respectively. Low impact dance raised heart rates above 60% of predicted maximum and so would provide training; during high impact dance recorded heart rates sometimes exceeded recommended safe limits. The addition of arm work significantly increased heart rates in both high and low impact dance but when oxygen pulses for each style of dance were compared no significant differences attributable to arm work were found. Moreover calculated differences between oxygen uptakes in stepping and dance at the same heart rates (those recorded during dance) were not significant for any of the four styles. Analysis of variance confirmed that neither arm work nor impact contributed significantly to the differences, so there was no evidence that these forms of dance change the normal relation between heart rate and oxygen uptake found in dynamic activities with large muscle groups such as stepping.

Adult↗
PubMed1994

The effect of methyl palmoxirate on incorporation of [U-14C]palmitate into rat brain.

We examined the dose response, time course and reversibility of the effect of methyl 2-tetradecylglycidate (McN-3716, methyl palmoxirate or MEP), an inhibitor of beta-oxidation of fatty acids, on incorporation of radiolabeled palmitic acid ([U-14C]PA) from plasma into brain lipids of awake rats. MEP (0.1, 1 and 10 mg/kg) or vehicle was administered intravenously from 10 min to 72 hr prior to infusion of [U-14C]PA. Two hr pretreatment with MEP (0.1 to 10 mg/kg) increased brain organic radioactivity 1.2 to 1.8 fold and decreased brain aqueous radioactivity by 1.2 to 3.0 fold when compared to control values. At 10 mg/kg, MEP significantly increased brain organic fraction from 40% in controls to 85%, 30 min to 6 hr pretreatment, and resulted in a redistribution of the radiolabeled fatty acid toward triacylglycerol. MEP changed the lipid/aqueous brain ratio of incorporated [U-14C]PA from 0.67 to 5.7. The incorporation rate coefficient, k*, was significantly increased by MEP (10 mg/kg) at 2 hr (31%), 4 hr (59%) and 6 hr (34%). All effects were reversed by 72 hr, consistent with a half-life of approximately 2 days for carnitine palmitoyl transferase I. These results indicate that intravenous MEP may be used with [1-11C]palmitic acid for studying brain lipid metabolism in vivo by positron emission tomography, as it significantly reduces the large unincorporated aqueous fraction that would result in high background radioactivity.

Animals↗
PubMed1994

Potential diagnostic implications of breakpoints in the long arm of chromosome 8 in lipoblastoma.

We report a case of lipoblastoma in a 17-month-old male patient with a pseudodiploid karyotype of 46,XY,der(14)t(8;14)(q11.2;q24). The tumor cells show two normal chromosome 8 homologs in addition to the extra 8q11.2-->qter segment, making it trisomic for the region 8q11.2-->qter, and monosomic for 14q24-->qter. Reports of chromosome studies in lipoblastoma are rare; however, a breakpoint in the long arm of chromosome 8q11-13 appears to be emerging as a consistent finding.

Chromosome Aberrations↗
PubMed1994

In vivo cerebral incorporation of radiolabeled fatty acids after acute unilateral orbital enucleation in adult hooded Long-Evans rats.

We examined effects of acute unilateral enucleation on incorporation from blood of intravenously injected unsaturated [1-14C]arachidonic acid ([14C]AA) and [1-14C]docosahexaenoic acid ([14C]DHA), and of saturated [9,10-3H]palmitic acid ([3H]PA), into visual and nonvisual brain areas of awake adult Long-Evans hooded rats. Regional cerebral metabolic rate for glucose (rCMRglc) values also were assessed with 2-deoxy-D-[1-14C]glucose ([14C]DG). One day after unilateral enucleation, an awake rat was placed in a brightly lit visual stimulation box with black and white striped walls, and a radiolabeled fatty acid was infused for 5 min or [14C]DG was injected as a bolus. [14C]DG also was injected in a group of rats kept in the dark for 4 h. Fifteen minutes after starting an infusion of a radiolabeled fatty acid, or 45 min after injecting [14C]DG, the rat was killed and the brain was prepared for quantitative autoradiography. Incorporation coefficients k* of fatty acids, or rCMRglc values, were calculated in homologous brain regions contralateral and ipsilateral to enucleation. As compared with ipsilateral regions, rCMRglc was reduced significantly (by as much as -39%) in contralateral visual areas, including the superior colliculus, lateral geniculate body, and layers I, IV, and V of the primary (striate) and secondary (association, extrastriate) visual cortices. Enucleation did not affect incorporation of [3H]PA into contralateral visual regions, but reduced incorporation of [14C]AA and of [14C]DHA by -18.5 to -2.1%. Percent reductions were correlated with percent reductions in rCMRglc in most but not all regions. No effects were noted at any of nine non-visual structures that were examined. These results indicate that enucleation acutely reduces neuronal activity in contralateral visual areas of the awake rat and that the reductions are coupled to reduced incorporation of unsaturated fatty acids into sn-2 regions of phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Reduced fatty acid incorporation likely reflects reduced activity of phospholipases A2 and/or phospholipase C.

Animals↗
PubMed1994

Effects of pentobarbital on incorporation of plasma palmitate into rat brain.

BACKGROUND: Barbiturates are reported to reduce brain oxidative metabolism and brain free fatty acid release during ischemia by mechanisms that are as yet unclear. To elucidate their action on brain lipid metabolism, an in vivo method was used to quantify the effect of pentobarbital on the incorporation of radiolabeled palmitic acid from blood into lipids of the rat brain. METHODS: [9,10(-3)H]-Palmitate was infused intravenously in an awake rat or in a rat lightly anesthetized or made comatose by pentobarbital. Twenty minutes after infusion was begun, the rat was killed and non-3H2O radioactivity in individual brain lipid compartments was determined. Incorporation coefficients (k*) were calculated by dividing the lipid compartment radioactivities by the integrated plasma radioactivity to 20 min. RESULTS: Net brain k* for [9,10(-3)H]-palmitate was reduced by 36-40% in pentobarbital-anesthetized rats. This reduction was unrelated to depth of anesthesia or to the presence of hypercapnia and acidosis, because breathing 7.5% CO2 had no effect on k* in awake rats. Anesthesia reduced radiolabel incorporation into phospholipids by 46-53% and into neutral lipids by 20-26% but did not change the distribution of radiolabel among phospholipid or neutral lipid classes. CONCLUSIONS: Pentobarbital has a profound effect on brain lipid metabolism. It reduces incorporation of plasma palmitate into brain, more so into phospholipids than into neutral lipids, independently of changes in cerebral blood flow. Reduced incorporation likely reflects reduced turnover of palmitate within brain lipids (mainly phosphatidylcholine), consistent with evidence that barbiturates also reduce release of free fatty acids during brain ischemia.

Animals↗
PubMed1994

Fluorescent light activates the immunomodulator cis-urocanic acid in vitro: implications for patients with systemic lupus erythematosus.

OBJECTIVE: Erythemagenic (295-305 nm) ultraviolet-B (UVB) radiation is toxic to patients with systemic lupus erythematosus (SLE). Cool white fluorescent lamp emissions produce a similar toxicity even though the UVB radiation emitted is primarily at the relatively non-erythemagenic wavelength of 313 nm. The purpose of this study was to determine if fluorescent light, presumably acting predominantly along the 313 nm wavelength, exhibits photochemical activity sufficient to account for toxicity. METHODS: The photochemical activity of fluorescent light was assessed by testing its capacity to activate urocanic acid, a plentiful and potent epidermal immunological mediator normally activated by polychromatic UVB radiation but activated maximally at 313 nm. Irradiation-induced isomerisation of trans-urocanic to cis-urocanic acid was quantitated by UV spectroscopy after separation of the isomers by high performance liquid chromatography. RESULTS: Fluorescent light irradiation of solutions containing the photoreceptor trans-urocanic acid produced a cumulative conversion of trans-to-cis-urocanic acid. This photochemical activity was compared with that of erythemagenic sunlamps, high in polychromatic UVB emissions. When normalised for UVB irradiance, the accumulation of cis-urocanic acid produced by both light sources was essentially equivalent. Conventional acrylic diffusers that absorb UVB emissions eliminated the fluorescent light-induced reaction. CONCLUSION: The results indicate that radiation from fluorescent lamps possesses substantial photoimmunological capability, sufficient to activate a potent, potentially dangerous, disease-modifying, immunomodulatory pathway and that poorly erythemagenic, primarily monochromatic UVB photons are responsible.

Humans↗
PubMed1992

Invasive Haemophilus influenzae infection in the Australian Capital Territory region.

OBJECTIVE: To investigate the pattern of invasive Haemophilus influenzae disease in the Australian Capital Territory (ACT) region with a view to assessing the possible benefits of vaccination in this community. SETTING AND DESIGN: The microbiology department of Royal Canberra Hospital processes all specimens from the three public hospitals in the ACT. Together these hospitals provide all paediatric medical and approximately 80% of adult inpatient beds available in the ACT. We identified all laboratory isolates of H. influenzae obtained from normally sterile sites from 1984 to 1990, and reviewed the clinical records of these patients. Also included in this analysis were all cases of acute epiglottitis identified in hospital discharge summaries, intensive care and coroners' records. Epidemiological, clinical and microbiological data were gathered and assessed. RESULTS: We identified 138 cases of infection. Forty per cent (36 of 66 cases of meningitis, 5 of 44 cases of epiglottitis, 10 of 12 cases of cellulitis) occurred in children aged less than 18 months. Meningitis (48%), epiglottitis (32%), cellulitis (9%) and primary bacteraemia (4%) were the most common syndromes seen. The annual incidence of invasive H. influenzae disease in Canberra was 63.2 per 100,000 children aged under five years. Approximately 1 in 225 children under five years of age and resident in Canberra developed invasive H. influenzae disease. Ninety-eight per cent of isolates serotyped were type b. CONCLUSION: A vaccination program effective in preventing H. influenzae type b infection, completed in infants before 6 months of age, could prevent upwards of 80% of invasive H. influenzae disease in our population. Such a program should be cost effective although precise assessment is hampered by the lack of accurate data on the acceptance rate, costs and efficacy of the current childhood vaccination schedule in our region.

Bacteremia↗
PubMed1992

A national collaborative study of resistance to antimicrobial agents in Haemophilus influenzae in Australian hospitals. The Australian Group for Antimicrobial Resistance (AGAR).

An Australia-wide survey of the prevalence of resistance to antimicrobial agents among Haemophilus influenzae was conducted on clinically significant isolates collected between July 1988 and September 1990. Laboratories from the capital cities of each Australian state and territory participated. Nine hundred and seventy clinical isolates were examined for beta-lactamase production and the MICs of ampicillin, coamoxiclav, chloramphenicol, cefaclor, ceftriaxone, cefotaxime, tetracycline, rifampicin, trimethoprim, sulphamethoxazole and co-trimoxazole were determined using the NCCLS agar dilution method with Haemophilus Test Medium. A smaller number of isolates were tested against penicillin V, penicillin G, ciprofloxacin, piperacillin and erythromycin in addition. The proportion of beta-lactamase producing strains was higher among invasive strains (21.6%) than non-invasive strains (14.2%) and varies considerably between states. The highest prevalence of ampicillin resistance was found in invasive strains from Canberra (40.8%), the lowest in non-invasive strains from Adelaide (5.1%). Paradoxically, in non-invasive strains, although beta-lactamase production was less common, resistance to other antimicrobials was commoner than in invasive strains and also varied between states.

Anti-Bacterial Agents↗
PubMed1992

Streptococcus pneumoniae: how common is penicillin resistance in Australia?

Streptococcus pneumoniae in the past were uniformly susceptible to penicillin. Increasing levels of resistance are now seen worldwide. To define the prevalence of this resistance in Australia, a collaborative study was carried out on all pneumococcal isolates at 15 large metropolitan teaching hospitals. During 1989 details of results of penicillin testing using routine methods were recorded. Isolates found resistant to penicillin were forwarded to Woden Valley Hospital for determination of penicillin minimum inhibitory concentration (MIC). All invasive isolates from five of these hospitals were also forwarded during 1989 and 1990 for MIC testing. Of the 1822 isolates tested, 31 (1.7%) were recorded as penicillin resistant. However, only 16 of 22 resistant isolates forwarded for MIC testing had MICs of > or = 0.1 mg/L confirmed. After adjustment to account for discrepancies with different laboratory testing methods we calculated the likely penicillin resistance to be 1% of isolates. Two of 105 invasive strains tested were found to be penicillin resistant. We conclude that penicillin-resistant S. pneumoniae isolates, including isolates from invasive sites, are found in Australia. All of these isolates had an MIC between 0.1 and 1 mg/L and are thus regarded as 'intermediately' penicillin resistant isolates. No high level resistance (MIC > or = 2 mg/L) was observed. Ongoing surveillance is essential to detect changes in resistance patterns and prevalence, as this will have implications for the empiric treatment of serious disease caused by S. pneumoniae.

Australia↗
PubMed1991

Procainamide-induced pseudo-obstruction in a diabetic patient.

We report the case of a 65-year-old black man who presented to our facility with pseudo-obstruction of the bowel within two weeks of the initiation of oral sustained-release procainamide hydrochloride therapy. The syndrome continued despite conversion to intravenous procainamide and only resolved after discontinuation of the medication. We believe that the anticholinergic properties of procainamide, coupled with the patient's diabetes, contributed to severe hypomotility of the gastrointestinal tract and, subsequently, a pseudo-obstructive state. The syndrome of drug-induced pseudo-obstruction is also reviewed.

Aged↗
PubMed1990

Quantitative brain autoradiography of [9,10-3H]palmitic acid incorporation into brain lipids.

The distribution of radioactivity within brain metabolic compartments was examined following the intravenous injection of [9,10-3H]palmitate into awake rats. Brain radioactivity reached a maximum value by 15 min after [9,10-3H]palmitate injection and remained unchanged for at least 4 hr. Regional differences in radioactivity could be determined with high resolution by quantitative autoradiography, at the level of cell layers within the hippocampus and cerebral cortex, and between striosomes of the caudate nucleus. Regional brain radioactivities were converted to normalized regional radioactivities (k) by dividing them by the integrated plasma fatty acid radioactivity (integrated over the time course of the experiment). These values reflected incorporation mainly into brain phospholipids; radioactivity due to nonlipid components was minimal. Indeed, about 85% of brain radioactivity was within lipids between 5 min and 4 hr postinjection, the remainder being equally divided between protein-associated pellet and aqueous-soluble metabolites. The major lipids labeled were phospholipids, particularly phosphatidylcholine, which contained about 75% of phospholipid radioactivity. The results show that [9,10-3H]palmitate can be used to examine incorporation of plasma palmitate into individual brain regions via quantitative autoradiography. Furthermore, the tracer is a rather selective marker for phosphatidylcholine and can be used to examine turnover and synthesis of this phospholipid. [9,10-3H]palmitate has advantages over [U-14C]palmitate for autoradiographic studies of incorporation; following the 14C-tracer, significant label even at 4 hr after injection is in nonlipid compartments (glutamate and aspartate), and the long path length of 14C limits resolution at the cell layer level.

Animals↗
PubMed1990

Regulatory changes in presynaptic cholinergic function assessed in rapid autopsy material from patients with Alzheimer disease: implications for etiology and therapy.

Brain regions from patients with or without Alzheimer disease (AD) were obtained within 2 hr of death and examined for indices of presynaptic cholinergic function. Consistent with loss of cholinergic projections, cerebral cortical areas involved in AD exhibited decreased choline acetyltransferase (acetyl-CoA:choline O-acetyltransferase, EC 2.3.1.6) activity. However, remaining nerve terminals in these regions displayed marked up-regulation of synaptosomal high affinity [3H]choline uptake, a result indicative of relative cholinergic hyperactivity. As choline uptake is also rate-limiting in acetylcholine biosynthesis, these findings have implications for both therapy and identification of causes contributing to neuronal death in AD.

Alzheimer Disease↗
PubMed1990

Dietary energy levels for growing-finishing pigs fed ad libitum. 1. Growth performance.

The NRC (1988) recommendations on nutrient standards for growing-finishing pigs assume a corn-based feeding regimen. However, the diets used in Western Canada are generally barley-based and consequently are usually lower in digestible energy (DE) and result in lower performance. Two experiments were therefore conducted, to evaluate the effect of DE level in relation to growth and feed conversion of pigs, by inclusion of corn and wheat in pelleted diets offered ad libitum. A total of 432 pigs was used, over the 20-98 kg live weight range. The inclusion of wheat or corn to barley-based diets during the grower period to raise the DE level resulted in more rapid and efficient growth. The faster growth obtained with the high-energy grains occurred during the grower period only, and was not observed in the finisher period. Results of including 5% of acidulated fatty acids (AFA) to raise the DE level were unfavourable.

Animal Feed↗
PubMed1990

Dietary energy levels for growing-finishing pigs fed ad libitum. 2. Carcass effects and economic model of the responses.

The NRC (1988) recommendations on nutrient standards for growing-finishing pigs assume a corn-based feeding regime. However, the diets used in Western Canada are generally barley-based and consequently are usually lower in digestible energy (DE) and result in reduced growth rate and feed efficiency. Corn and wheat can be included in the diet to raise the DE level, but since this could affect the carcass quality of pigs fed ad libitum, the influence of DE level in relation to carcass quality was measured in two experiments. An economic assessment of the data was also conducted. A total of 432 pigs was used, over the 20-98 kg live weight range. The inclusion of wheat or corn to barley-based diets during the finisher period resulted in reduced carcass quality, and there was also some evidence that increased dietary energy during the grower stage had the same effect.

Adipose Tissue↗
PubMed1990

Undernutrition and overnutrition in the neonatal rat: long-term effects on noradrenergic pathways in brain regions.

To determine whether neonatal nutrition influences development of CNS noradrenergic systems, litter sizes were manipulated at birth to produce undernutrition (16-17 pups/litter) or overnutrition (five to six pups) and compared to rats reared in normal litter sizes (10-11 pups). Studies were conducted throughout the preweaning period in which nutrition was manipulated, as well as during postweaning nutritional rehabilitation. Sparing of brain growth occurred, evidenced by much smaller changes in brain region wt than in body wt. Similarly, neonatal malnutrition produced major deficits in norepinephrine levels in peripheral sympathetic pathways, but levels in the brain remained within normal limits. Development of [3H]norepinephrine synaptosomal uptake, a biochemical index for presynaptic terminals, was unimpaired by malnutrition; indeed, higher uptake values were seen than in the control population. Nevertheless, norepinephrine turnover was severely attenuated during nutritional restriction and the effect persisted into adulthood; the deficit was greater in the cerebral cortex than in the cerebellum, despite the fact that cerebellar growth showed less sparing. Development of binding capabilities of noradrenergic receptors, particularly the alpha 2- and beta-subtypes, were also adversely affected in cerebral cortex, again suggestive of a deleterious effect on synaptic function. Animals exposed to neonatal overnutrition showed only slight effects on brain region wt or norepinephrine levels, but did display some suppression of [3H]norepinephrine synaptosomal uptake and enhancement of norepinephrine turnover; changes in receptor binding capabilities in the overnourished animals were attributable to the small alterations in brain region wt. These data indicate that neonatal nutrition alters presynaptic and postsynaptic markers of noradrenergic function that remain abnormal even when nutritional rehabilitation occurs.

Animal Nutritional Physiological Phenomena↗