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Biomedical subjects

J R Jones

Publications and source records attributed to J R Jones.

At least 37 records · Page 2Linked to original sources
PubMed1999

Spontaneous abortion in the British semiconductor industry: An HSE investigation. Health and Safety Executive.

BACKGROUND: The UK Health and Safety Executive (HSE) conducted a study to examine the risk of spontaneous abortion (SAB) in British female semiconductor industry workers, following reports from the USA which suggested an association between risk of SAB and work in fabrication rooms and/or exposure to ethylene glycol ethers. METHODS: A nested case-control study based on 2,207 women who had worked at eight manufacturing sites during a 5-year retrospective time frame was established; 36 cases were matched with 80 controls. RESULTS: The overall SAB rate in the industry was 10.0%. (65 SABs/651 pregnancies) The crude odds ratio (OR) for fabrication work was 0.65 (95% CI 0.30-1.40). This was essentially unchanged after adjustment for a range of potential confounding factors in the first 3 months of pregnancy and was reduced to 0.58 (95% CI 0.26-1.30) after adjustment for smoking in the previous 12 months. There were no statistically significantly elevated ORs for any work group or any specific chemical or physical exposure in the industry. CONCLUSIONS: There is no evidence of an increased risk of SAB in the British semiconductor industry. Am. J. Ind. Med. 36:557-572, 1999. Published 1999 Wiley-Liss, Inc.

Abortion, Spontaneous↗
PubMed1999

Epithelial P2X purinergic receptor channel expression and function.

P2X purinergic receptor (P2XR) channels bind ATP and mediate Ca(2+) influx--2 signals that stimulate secretory Cl(-) transport across epithelia. We tested the hypotheses that P2XR channels are expressed by epithelia and that P2XRs transduce extracellular ATP signals into stimulation of Cl(-) transport across epithelia. Electrophysiological data and mRNA analysis of human and mouse pulmonary epithelia and other epithelial cells indicate that multiple P2XRs are broadly expressed in these tissues and that they are active on both apical and basolateral surfaces. Because P2X-selective agonists bind multiple P2XR subtypes, and because P2X agonists stimulate Cl(-) transport across nasal mucosa of cystic fibrosis (CF) patients as well as across non-CF nasal mucosa, P2XRs may provide novel targets for extracellular nucleotide therapy of CF.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Isolation and partial characterization of an opioid-like 88 kDa hibernation-related protein.

Previous studies show that infusion of hibernating woodchuck albumin (HWA) induces hibernation in summer-active ground squirrels and results in profound behavioral and physiological depression in primates. These effects are reversed by the administration of opiate antagonists, suggesting that the putative hibernation induction trigger (HIT) may act through opioid receptors. We have demonstrated that both HIT-containing plasma and the synthetic alpha opioid D-Ala2-D-Leu5-enkephalin (DADLE), which mimics the activity of HIT in hibernators, extend tissue survival time of a multi-organ autoperfusion system by 3-fold. In this study we present the first data showing biological activity with a much more highly purified plasma fraction from hibernating woodchucks, identified as the hibernation-related factor (HRF). Both the HRF and DADLE show opiate-like contractile inhibition in the mouse vas deferens (Mvd) bioassay. We also have preliminary evidence in an isolated rabbit heart preparation indicating that the HRF and DADLE act similarly to restore left ventricular function following global myocardial ischemia. Furthermore, we have partially sequenced an alpha 1-glycoprotein-like 88 kDa hibernation-related protein (p88 HRP) present in this fraction, which may prove to be the blood-borne HIT molecule.

Amino Acid Sequence↗
PubMed1998

Susceptibility testing of Klebsiella spp.--an international collaborative study in quality assessment.

In order to compare the prevalence of antibiotic resistance in different geographical areas, it is necessary to ensure agreement between laboratories on the assignment of strains to 'susceptible' and 'resistant' categories. An international quality assessment was performed to investigate the performance of susceptibility testing of Klebsiella spp. Ninety-five strains of klebsiellae were selected from clinical isolates at the London Hospital Medical College (LHMC). These included strains with a diversity of susceptibility profiles to amoxycillin/clavulanate, piperacillin, ceftazidime, cefuroxime, ciprofloxacin, gentamicin and trimethoprim. The strains were sent to 13 participating laboratories in Europe and the USA and laboratories were asked to test the susceptibility of these strains to these antibiotics by their usual methods. They were also asked to provide details of the method used to test susceptibility. Several different standard recommended testing methods were used. Reporting of susceptibilities was generally accurate, but a number of anomalies were noted. Discrepancies of reporting between the LHMC and the participating laboratories was more marked for resistant strains, particularly in the detection of resistance to cefuroxime and ciprofloxacin, as well as the assignment of susceptibility and resistance to piperacillin and amoxycillin/clavulanate. Some discrepancies could be attributed to the use of different breakpoints, leading to differing assignment of susceptibility. Methodological variations including disc content, inoculum and failure to measure and interpret zone sizes consistently also led to anomalies. This quality assessment programme has helped to identify problems in susceptibility testing which should be investigated further.

Anti-Bacterial Agents↗
PubMed1995

Continuing increase in mesothelioma mortality in Britain.

Mesothelioma is closely related to exposure to asbestos, and mesothelioma mortality can be taken as an index of past exposure to asbestos in the population. We analysed mesothelioma mortality since 1968 to assess the current state of the mesothelioma epidemic, and to predict its future course. We found that rates of mesothelioma in men formed a clear pattern defined by age and date of birth. Rates rose steeply with age showing a very similar pattern in all five-year birth cohorts. By date of birth, rates increased from mid-1893 to mid-1948, and then fell. Relative to the 1943-48 cohort, the risk for the 1948-53 cohort is 0.79 and for the 1953-58 cohort 0.48. Despite these falls, if the age profile of rates for these cohorts follows the pattern of past cohorts, their predicted lifetime mesothelioma risks will be 1.3%, 1.0%, and 0.6%. Combining projections for all cohorts results in a peak of annual male mesothelioma deaths in about the year 2020 of between 2700 and 3300 deaths. If diagnostic trend is responsible for a 20% growth in recorded cases every 5 years--an extreme but arguable case--and if this trend has now ceased, the peak of annual male deaths will be reduced to 1300, reached around the year 2010. Analysis of occupations recorded on death certificates indicate that building workers, especially plumbers and gas fitters, carpenters and electricians are the largest high-risk group. These data indicate that mesothelioma deaths will continue to increase for at least 15 and more likely 25 years. For the worst affected cohorts--men born in the 1940s--mesothelioma may account for around 1% of all deaths. Asbestos exposure at work in construction and building maintenance will account for a large proportion of these deaths, and it is important that such workers should be aware of the risks and take appropriate precautions.

Adult↗
PubMed1995

D2-specific discriminative stimuli: parameters, blocking, and rebound.

This study characterizes the cue properties of quinpirole (LY 171555), a selective D2 agonist, and the blocking capabilities of spiperone, a selective D2 antagonist. After rats were trained to discriminate 0.025 mg/kg quinpirole from distilled water, a dose-response curve and time course of the quinpirole discriminative stimulus were determined. The effectiveness of three doses of spiperone in blocking the discriminative stimulus produced by 0.02 mg/kg quinpirole was then assessed. Finally, the time course of spiperone's blocking action was determined. Given the putative selective action of these drugs on D2 receptors and the parametric data presented here, it was predicted that following chronic treatment with spiperone, a rebound increase in quinpirole-appropriate responding would occur. Neither chronic treatment with spiperone nor chronic treatment with haloperidol produced the predicted changes. This result, however, may be confined to the specific dose and time parameters used.

Animals↗
PubMed1995

Toxicity of crude oil to the mayfly, Hexagenia bilineata (Ephemeroptera: Ephemeridae).

Effects of crude oil on survival and behavior of the mayfly Hexagenia bilineata were evaluated in laboratory studies. Mayfly nymphs were exposed to the water soluble and oil residue fractions of crude oil. Mayfly survival was not reduced by a 96-h exposure to either the water soluble fraction or the oil residue mixed with sediment. However, significant mortality did result from a 21-day exposure to oil residue mixed with sediment at concentrations as low as 500 microg g(-1). Survival was also reduced after a 21-day exposure to oil-contaminated sediments (1905 microg g(-1)) collected 6 weeks after a crude oil spill in the Chariton River, Missouri. In a behavioral test measuring habitat exclusion, organisms did not avoid contact with sediment containing oil residue (50-800 microg g(-1)). Collectively, results from these studies indicate that exposure to oil residue in sediment will reduce survival of H. bilineata in the laboratory and may reduce survival in the environment for 6 weeks or more after an oil spill.

Journal Article↗
PubMed1995

Current UK opinion on thromboprophylaxis in orthopaedic surgery: its use in routine total hip and knee arthroplasty.

We surveyed all surgically qualified members of the British Orthopaedic Association as to their views on thromboprophylaxis in routine total hip and knee replacement. The response rate was 92%. In total hip replacement, 13-15% of surgeons used no method of prophylaxis at all, 18-22% did not use a mechanical method of prophylaxis, while 26% did not use a pharamacological agent; 36% believed low-dose anticoagulant thromboprophylaxis to be a medicolegal necessity while 47% disagreed with this. In total knee replacement, 18-33% of surgeons used no method of prophylaxis at all, 20-26% did not use a mechanical method of prophylaxis, while 54-58% did not use a pharmacological agent; 12 believed low-dose anticoagulant thromboprophylaxis to be a medicolegal necessity, while 64% disagreed with this. We conclude that mechanical methods remain a popular method of thromboprophylaxis and pharmacological methods, while commonly used, are not seen as a medicolegal requirement in lower limb arthroplasty and are used less often in total knee replacement.

Anticoagulants↗
PubMed1995

Laryngeal mask airway: an alternative for the difficult airway.

The laryngeal mask airway (LMA) was invented by Dr. Archie Brain at the London Hospital, Whitechapel, in 1981. Dr. Brain's main objective for the LMA was that it would provide a better method of maintaining a patient's airway than by face mask. Also, the LMA would be less hemodynamically stressful than with insertion of an endotracheal tube. The LMA consists of a silicone rubber tube connected to a miniature silicone mask. The perimeter of the mask consists of an inflatable elliptical cuff, which forms a tip at the distal aspect of the LMA. The aperture bars in the dome of the mask lift the epiglottis away, so the lumen remains unobstructive. The LMA forms a low pressure seal around the larynx. The LMA is contraindicated in any situation where the patient is at risk for pulmonary aspiration. The LMA is not a substitute for a properly placed endotracheal tube in this situation. The American Society of Anesthesiologists' difficult airway algorithm recommends the insertion of an LMA when ventilation and/or intubation are difficult. The distal aperture of the LMA is in close approximation to the vocal cords, so a 6.0-mm internal diameter endotracheal tube can be passed over an intubating stylet or a pediatric fiberoptic bronchoscope to secure a patient's airway.

Contraindications↗
PubMed1995

Differential regulation of neuronal sodium channel expression by endogenous and exogenous tyrosine kinase receptors expressed in rat pheochromocytoma cells.

The biological activity of growth factors that act through receptor tyrosine kinases (RTKs) can differ dramatically, depending on both the properties of the RTKs and the cellular environment in which the RTKs are expressed. To determine the ability of different RTKs to elicit ras-independent responses central to neuronal differentiation, we analyzed voltage-dependent sodium (Na) channel expression in rat pheochromocytoma (PC12) cells after activation of a variety of endogenously and exogenously expressed RTKs. In PC12 cells expressing trkB (Ip et al., 1993), the increase in Na current density caused by brain-derived neurotrophic factor (BDNF) was similar to that observed upon activation of endogenous trkA by NGF. BDNF also increased type II Na channel mRNA expression, as did neurotrophin-3 in PC12 cells expressing trkC (Tsoulfas et al., 1993). In contrast, insulin did not increase type II Na channel mRNA expression or Na current density in PC12 cells, while epidermal growth factor (EGF) elicited small, yet reproducible increases in type II Na channel mRNA and Na current density when compared to NGF, even upon coexpression of an EGF receptor/p75 receptor chimera (Yan et al., 1991). Finally, in PC12 cells expressing beta-platelet-derived growth factor (PDGF) receptors (Heasley and Johnson, 1992), PDGF increased type II Na channel mRNA and Na current density to the same extent as NGF. The results show the capabilities of these RTKs in eliciting Na channel expression and the specificity arising due to differences in their intrinsic properties.

Animals↗
PubMed1994

3H-n.m.r. studies of multiple conformations and dynamic processes in complexes of folate and methotrexate with Lactobacillus casei dihydrofolate reductase.

[7,3',5'-3H3]- and [7,9-3H3]-folic acid and [7,3',5'-3H3]methotrexate (MTX) have been prepared and 3H-n.m.r. spectra obtained for their complexes with Lactobacillus casei dihydrofolate reductase (DHFR). The 3H results confirm the presence of three pH-dependent different conformational forms in the complex DHFR.NADP+.folate. The folate benzoyl ring could be shown to be in essentially the same environment in the different forms, with the major differences being associated with the pterin ring. The appearance of a single resonance for the 3',5'-tritons showed that the benzoyl ring is flipping rapidly in all three forms. In contrast, the MTX complex was shown to exist as a single conformational state with the benzoyl ring flipping rate being too low to give a single averaged signal for the 3',5'-nuclei over the temperature range 283-313 K.

Escherichia coli↗
PubMed1994

Koro: culture-bound disorder or universal symptom?

A case report is presented of koro associated with a depressive illness in a 31-year-old male Briton. The specificity or otherwise of koro as culture bound and a distinct nosological entity is discussed.

Adult↗
PubMed1992

The consequences of the isotope effect on proline dehydrogenation rates estimated by the tritium loss method.

Loss of tritium from a substrate is often used to estimate the rate of dehydrogenation. However, loss of 3H may be much slower than loss of H because of the tritium isotope effect. In order to assess the impact of the tritium isotope effect, loss of 3H from the C-5 position of proline during dehydrogenation by rat liver mitochondria and bacteroids from soybean (Glycine max [L.] Merrill) nodules was compared with appearance of 14C in products of [14C]proline dehydrogenation. Incubations were carried out in the presence of o-aminobenzaldehyde (added to trap the initial product, delta 1-pyroline-5-carboxylate). The fraction of total 14C products trapped by o-aminobenzaldehyde varied from 0.07 to 0.75 depending upon experimental conditions. With rat liver mitochondria, dehydrogenation of [14C]proline was between 3.27 and 9.25 times faster than dehydrogenation of 3H proline, depending upon assay conditions. Soybean nodule bacteriods dehydrogenated [14C]proline about 5 times faster than [3H]proline. We conclude the following: (i) the rate of proline dehydrogenation may be greatly underestimated by the tritium assay because of the tritium isotope effect, and (ii) the 14C assay may underestimate the rate of proline dehydrogenation if it is assumed that o-aminobenzaldehyde quantitatively traps delta 1-pyrroline-5-carboxylate under all conditions. The simplicity of the tritium assay makes it attractive for routine use. However, its use requires determination of the tritium isotope effect, under the specific conditions of the assay, in order to correct the results. The considerations discussed here have broad applicability to any dehydrogenase assay employing tritium loss.

Animals↗
PubMed1992

The effects of amphetamine on body weight and energy expenditure.

Although there is evidence suggesting that, in addition to suppressing food consumption, amphetamine reduces body weight by increasing energy expenditure, there is little consistency among the few studies examining that factor. In this experiment, the effect of amphetamine on daily energy consumption, within-day body weights, and hourly measures of metabolic rate (MR) and respiration quotient (RQ) were assessed. Daytime drug injections decreased total energy consumption, produced biphasic changes over time in MR, and persistently lowered RQ values. In contrast, nighttime injections of drug had little effect on energy consumption and MR but did reduce RQ for the first 4 postinjection hours. These effects show that amphetamine effects interact with the circadian organization of behavior and suggest that rodent studies of anorectic agents have more relevance for humans if drugs are given during the night, when rats are normally awake and eating. From this study, it seems clear that amphetamine reduces body weight by altering metabolic rate and fat metabolism in rats when the drug is given during the day.

Animals↗
PubMed1992

Effects of amphetamine on food intake and weight: timing of injections and food access.

Although the effects of amphetamine on food consumption and body weight in nondeprived animals are of interest for theoretical and clinical reasons, there are only a few studies on this topic in the literature. In Experiment 1, independent groups of nondeprived rats were given daily injections of 0, 1, 2, 5, or 10 mg/kg d-amphetamine sulfate shortly after light onset for 30 days. While drug treatment did not affect food consumption, all amphetamine-treated groups lost weight over the initial 12 days and then, over the final 18 days of treatment, gained weight at the same rate as controls. Experiment 2 assessed whether the effects of amphetamine on these measures are influenced by the timing of the daily injections relative to the light-dark cycle. As in Experiment 1, injections of amphetamine at light onset again produced weight loss while not affecting food consumption, whereas injections of the drug at light offset did not reliably affect either measure. Experiment 3 showed that the relationships among variables observed in nondeprived animals remain the same in animals restricted to 12 h of access to food each day and replicated the amphetamine-induced hyperphasia observed earlier by Jones and Caul (9).

Animals↗
PubMed1992

Occupational exposures in California wildland fire fighting.

Industrial hygiene measurement of exposures to wildland fire fighters was conducted in northern California during three consecutive fire seasons (1986-1989) in conjunction with three separate health effects studies. Chemicals that were monitored included carbon monoxide, total and respirable particulates, polyaromatic hydrocarbons (PAHs), crystalline silica, aldehydes, and benzene. Measurements were taken at both wildland fires and prescribed (planned) burns. A variety of collection methods were employed--colorimetric detector tubes and a CO monitor were used for direct-reading area measurements; colorimetric diffusion tubes, filter cassettes, sorbent tubes, and passive vapor monitors were used for determining personal time-weighted average exposures. A new screening method (National Institute for Occupational Safety and Health Method 2539) was used to identify the presence of specific aldehydes. Results show that wildland fire fighters may at times be exposed to concentrations of carbon monoxide, total or respirable particulates, or silica at levels near or higher than recommended occupational exposure limits, although group means were generally well below the limits. Time-weighted average formaldehyde levels, measured in a few instances above 0.37 mg/m3 (0.3 ppm), indicate a potential for formaldehyde-induced eye or respiratory irritation under these conditions. Certain characteristics of the work such as high altitude, temperature, and breathing rate; extended work shifts; and additional off-shift exposures suggest that adjustment of 8-hr exposure limits may be necessary to provide adequate protection. In part, because of the rigors of performing industrial hygiene measurements under fire fighting conditions, data are limited and could not be considered representative of the full range of exposures fire fighters may encounter.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗