Search PubMed⌕ Search

Biomedical subjects

J Cameron

Publications and source records attributed to J Cameron.

At least 73 records · Page 4Linked to original sources
PubMed1994

Outcome five years after percutaneous transluminal coronary angioplasty or coronary artery bypass grafting for significant narrowing limited to the left anterior descending coronary artery.

Percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) are both used widely for angina but information about their comparative efficacy is limited. This study compared the outcome of 358 consecutive patients undergoing initial revascularization for significant narrowing of the left anterior descending artery (LAD) by PTCA (n = 254) or CABG (n = 104) from 1987 to 1989. PTCA was successful in 93% but complicated by urgent CABG in 3%. A left internal mammary graft was used in 88% of those having elective CABG. There was 1 perioperative death. Follow-up data were obtained after a median interval of 5.5 years (maximum 7.1). Rates for freedom from death (97% PTCA vs 93% CABG, p = 0.06) were similar, but CABG patients had greater rates for freedom from chest pain recurrence (74% CABG vs 48% PTCA, p < 0.0001), myocardial infarction (98% vs 92%, p = 0.04), and from need for further revascularization (99% vs 67%, p < 0.0001). Both groups achieved similar status, with 81% of PTCA and 90% of CABG patients having angina no worse than functional class I. Quality-of-life index was high for both groups (0.983 +/- 0.034/1.000 vs 0.987 +/- 0.032/1.000, p = 0.3). Both PTCA and CABG result in excellent survival, functional ability, and quality of life, but patients undergoing PTCA require more procedures to achieve this.

Adult↗
PubMed1994

Percutaneous transluminal coronary angioplasty: clinical and quality of life outcomes one year later.

BACKGROUND: The quality of life status of patients prior to and following percutaneous transluminal coronary angioplasty (PTCA) has not been comprehensively investigated. AIM: This study was carried out to determine the effect that PTCA has on patients' quality of life. METHODS: Data on 209 patients were collected one day pre-PTCA and at a mean of two and 11 months post-PTCA. Data on symptomatic status, functional capacity, life satisfaction and psychological well-being were analysed quantitatively. Clinical outcomes, patient perception of PTCA and employment status wee analysed by descriptive statistics. RESULTS: Highly significant improvement in all quality of life measures was found at the early follow-up (p < .001). This improvement was sustained at the late follow-up. At the late follow-up, 58% of patients felt that PTCA had been very beneficial to their health and well-being, and 79% of workers had returned to work. PTCA was primarily successful in 91% of vessels dilated. There were no procedural-related deaths, 12 patients (6%) developed acute occlusion and three patients (1.5%) experienced myocardial infarction (MI). A symptomatic restenosis rate of 16% was found, including 19 patients (9%) requiring repeat PTCA and 14 (7%) undergoing coronary artery bypass grafting (CABG). CONCLUSION: These findings suggest that, after PTCA, the majority of patients experienced improved quality of life which was sustained one year later.

Angioplasty, Balloon, Coronary↗
PubMed1994

Experience with the Gianturco-Roubin stent for abrupt vessel closure complicating percutaneous transluminal coronary angioplasty.

BACKGROUND: Emergency coronary artery bypass grafting (CABG) has previously been the only option in the treatment of refractory abrupt vessel closure complicating percutaneous transluminal coronary angioplasty (PTCA), and has been associated with high rates of morbidity and mortality. Intracoronary stenting now provides an alternative to emergency CABG. AIM: To assess our initial experience with emergency coronary artery stenting as a new technique. METHODS: Retrospective case study review with clinical and angiographic follow-up. RESULTS: The Gianturco-Roubin (GR) stent was deployed in 13 patients in whom PTCA was complicated by abrupt vessel closure refractory to standard balloon techniques. Indications for PTCA were unstable angina (six), stable angina (six) and acute myocardial infarction (MI) (one). The arteries stented included left anterior descending (LAD) artery lesions (eight) and right coronary artery lesions (five). Two patients required urgent CABG, one due to failed stent deployment and one for inadequate control of vessel dissection. In seven of the stented patients the creatine kinase rose to greater than twice the upper limit or normal. Three patients had subacute thrombotic occlusion at seven to 19 days post stent deployment, managed with intravenous thrombolysis or repeat PTCA. At seven months follow-up, 11 patients were free of angina, two patients had Canadian Heart Association class II angina and there were no deaths. Eleven patients had repeat angiography at mean six months post stent. Five patients had evidence of restenosis managed with repeat PTCA in four and CABG in one. CONCLUSIONS: The GR stent is an effective alternative to urgent CABG in the treatment of refractory abrupt vessel closure complicating PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1994

The effect of vitamin A on the proliferation of oral epithelium in the rat.

This study assessed the effect of topical and systemic 13-cis-retinoic acid on rat palatal epithelial proliferation with bromodeoxyuridine labelling and silver stained nucleolar organizer regions. Sixty male Wistar rats were assigned randomly to a control group or treatment groups of topical orabase, RA in orabase, 5 times/week or twice weekly systemic doses of 12 mg RA in coconut oil. The rats were treated for 1, 2, 4 or 8 weeks and killed 1 h post-injection of 40 mg/kg BrdUrd. The palatal mucosae were processed, using immunoperoxidase staining or silver stain to visualize BrdUrd utilization or AgNORs, respectively. The number of BrdUrd positive nuclei/mm overlying epithelium and number and area of AgNORs in the basal cells were assessed using image analysis. ANOVA indicated there was no significant effect of treatment on LN/mm or the numbers or areas of AgNORs. The LN/mm for the 8 w group (29.5) was significantly lower than the other groups. RA did not influence rat palatal epithelial proliferation, but across all groups increased age was associated with decreased proliferation. It would appear that the proliferation of normal oral mucosa may not be subject to altered proliferation when treated with therapeutic doses of topical or systemic RA.

Administration, Oral↗
PubMed1994

Identification of a mutation at codon 65 in the IKKK motif of reverse transcriptase that encodes human immunodeficiency virus resistance to 2',3'-dideoxycytidine and 2',3'-dideoxy-3'-thiacytidine.

The technique of in vitro selection was used to generate variants of the human immunodeficiency virus type 1 that are resistant to 2',3'-dideoxycytidine (ddC). Most of the pol regions of such viruses, including the complete reverse transcriptase open reading frame and portions of flanking protease and integrase genes, were cloned and sequenced, using PCR-based procedures. Mutations were variously detected at amino acid site 65 (Lys-->Arg; AAA-->AGA) and at a previously reported codon, site 184 (Met-->Val; ATG-->GTG). We introduced the site 65 mutation into the pol gene of infectious, cloned HxB2-D DNA by site-directed mutagenesis in order to confirm by viral replication assay the importance of this site in conferring resistance to ddC. The recombinant virus possessed greater than 10-fold resistance against this compound in comparison with parental HxB2-D. Cross-resistance of approximately 20- and 3-fold, respectively, was detectable against the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine and 2',3'-dideoxyinosine but not against 3'-azido-3'-deoxythymidine. Combinations of the site 65 and 184 mutations did not yield levels of resistance higher than those attained with the site 65 mutation alone. The presence of the site 65 mutation was confirmed by PCR analysis of peripheral blood mononuclear cells from patients on long-term ddC therapy in 4 of 11 cases tested. Viruses that possessed a ddC resistance phenotype were isolated from subjects whose viruses contained the site 65 mutation in each of four instances. Four of these clinical samples were also demonstrated to possess the Met-184-->Val mutation, and one of them possessed both the Lys-65-->Arg and Met-184-->Val substitutions. Direct cloning and sequencing revealed the site 65 mutation in viruses isolated from these individuals.

Amino Acid Sequence↗
PubMed1994

Prediction of reproductive status in women with bulimia nervosa by past high weight.

It is not understood why disturbed menstrual function occurs in as many as 50% of women with bulimia nervosa who are at normal weight. The authors measured luteinizing hormone (LH), estradiol, and progesterone in 13 women with bulimia nervosa who were at normal weight and six normal comparison subjects. They found that the women with bulimia nervosa were likely to have abnormal 24-hour luteinizing hormone (LH) secretion if their current weight was less than 85% of their past high weight.

Adolescent↗
PubMed1994

EFFECT OF THE EXTERNAL CONCENTRATION OF CALCIUM ON THE POSTMOULT UPTAKE OF CALCIUM IN BLUE CRABS (CALLINECTES SAPIDUS)

The rate of calcium uptake in blue crabs (Callinectes sapidus Rathbun) acclimated to 2 sea water with a calcium concentration of 1.4 mmol l-1 was dependent on the magnitude and direction of the electrochemical gradient for calcium. When transferred to water with a high calcium concentration (6 mmol l-1), the electrochemical gradient for calcium favoured diffusive influx, and calcium uptake and apparent H+ excretion increased by approximately 50 %. When transferred to water with a low calcium concentration (0.10 mmol l-1), where the electrochemical gradient for calcium strongly favoured diffusive efflux, calcium uptake ceased but apparent H+ excretion continued at a reduced rate. Crabs regulated the free calcium concentration in their blood at approximately 8 mmol l-1 when the external concentration of calcium was 1.4 mmol l-1 or higher, but the concentration of free calcium in the blood decreased to 5.6 and 4.6 mmol l-1, respectively, at external concentrations of calcium of 0.25 and 0.10 mmol l-1. Crabs transferred to water with 0.10 mmol l-1 calcium for the first 2 days after moult accumulated only 2.5 g calcium kg-1 wet mass, about one-quarter of the mass normally accumulated. Seawater-acclimated crabs transferred to 2 salinity at 1 day postmoult took up calcium at a reduced rate, indicating that a period of acclimation is necessary for a component of the active transport system to increase its capacity, for diffusive efflux to be reduced, or for both to occur.

Journal Article↗
PubMed1994

MECHANISM OF THE NET UPTAKE OF WATER IN MOULTING BLUE CRABS (CALLINECTES SAPIDUS) ACCLIMATED TO HIGH AND LOW SALINITIES

Blue crabs (Callinectes sapidus Rathbun) acclimated to a salinity of 2 approximately doubled in wet mass (excluding carapace) during the period from 10 h before moult to 2 h after moult. Both in blue crabs acclimated to 2 salinity and in crabs acclimated to 28 salinity, the drinking rate increased from approximately 0.4 ml 100 g-1 h-1 at 1 day prior to moult to approximately 8 ml 100 g-1 h-1 during the first hour after moult. The drinking rate had decreased 1 day after moult in both salinities, but was significantly higher in crabs acclimated to high salinity (1.84&plusmn;0.16 ml 100 g-1 h-1) than in crabs acclimated to low salinity (0.26&plusmn;0.04 ml 100 g-1 h-1). Drinking accounted for two-thirds of the weight gain during the first hour after moult at both acclimation salinities, indicating that water enters the body at moult primarily through the gut rather than through the gills. [14C]polyethylene glycol, added as a tracer in the bath water, was concentrated in the midgut gland rather than in the stomach, implicating the midgut gland as the primary site of water absorption. The rate of water efflux was significantly greater in crabs acclimated to 30 salinity (66.4&plusmn;9.0 ml 100 g-1 h-1) than in crabs acclimated to 2 salinity (34.0&plusmn;4.7 ml 100 g-1 h-1). The osmotic uptake of water is equal at both salinities as a result of the decreased water permeability at low salinity. The rate of urine formation was estimated to be between 0.5 and 1 ml 100 g-1 h-1 during the first hour after moult in crabs acclimated to both low and high salinities, suggesting that the antennal gland plays a relatively small role in water regulation during this period.

Journal Article↗
PubMed1993

Building a city wide service for exchanging needles and syringes.

How best can injecting drug misusers obtain clean injecting equipment in a city where drug injecting is widespread? An exchange service for needles and syringes throughout Glasgow has been established in health centres and clinics in the evening. Over the past four years seven new exchanges have been opened and over 2700 injecting drug misusers have attended. Attendances rose from under 1000 in 1988 to 28,000 in 1992. The exchanges also provide a wide range of other health and social services. Public hostility to the exchanges has abated. During the same period equipment sharing in the city diminished and the observed prevalence of HIV among injecting drug misusers stabilised at around 1%.

Community Health Services↗
PubMed1993

Modification of the peripheral nerve disturbance in ciguatera poisoning in rats with lidocaine.

Electrophysiological studies were performed on the ventral tail nerve of adult rats following intraperitoneal injection of a crude extract of ciguatoxin from known toxic fish flesh. Ciguatoxin induced significant slowing of both mixed and motor nerve conduction velocities and also significant reductions in both motor and mixed nerve amplitudes. Both absolute and supernormal periods were significantly prolonged together with an increase in the magnitude of the supernormal response. These electrophysiological disturbances were modified or blocked by intraperitoneal lidocaine. These findings suggest that lidocaine may have a potential therapeutic application in the treatment of the neurological disturbance in acute ciguatera poisoning in humans.

Action Potentials↗
PubMed1993

Reference accuracy in the emergency medicine literature.

STUDY OBJECTIVE: To determine the incidence and nature of errors in the citation and quotation of references contained in the emergency medicine literature. DESIGN: A retrospective analysis of a random sample of articles and references found in the three major emergency medicine journals. SETTING: A university/county hospital. METHODS: We examined single issues of three emergency medicine journals: Annals of Emergency Medicine, Journal of Emergency Medicine, and American Journal of Emergency Medicine. INTERVENTIONS: None. MEASUREMENTS: Four independent reviewers assessed 145 references from 46 referring authors for citational and quotational accuracy. MAIN RESULTS: Major and minor citation errors were found in 10.3% and 17.2% of reference listings, respectively. Qualitative quotational errors were found in 35.2% of references. Eighty-two percent of these errors were considered to be major. Quantitative quotational errors were found in 47% of references reviewed. Secondary rather than primary reference sources were used in 41.4% of references reviewed. CONCLUSION: This study demonstrates a substantial error rate in the citation and quotation of reference sources in the emergency medicine literature. In addition, verification of primary source material was not done by a large percentage of the authors reviewed. Recommendations for improving the accuracy of the emergency medicine literature are offered.

Bias↗
PubMed1993

The same mutation that encodes low-level human immunodeficiency virus type 1 resistance to 2',3'-dideoxyinosine and 2',3'-dideoxycytidine confers high-level resistance to the (-) enantiomer of 2',3'-dideoxy-3'-thiacytidine.

Variants of human immunodeficiency virus type 1 that display 500- to 1,000-fold resistance to the (-) enantiomer of 2'-deoxy-3'-thiacytidine and approximately 4- to 8-fold resistance to 2',3'-dideoxycytidine and 2',3'-dideoxyinosine have been generated through in vitro selection with the former compound. The polymerase regions of several of these resistant viruses shared a codon alteration at site 184 (ATG-->GTG; methionine-->valine), a mutation previously associated with low-level resistance to 2',3'-dideoxycytidine. The biological relevance of this mutation for the (-) enantiomer of 2'-deoxy-3'-thiacytidine was confirmed by site-directed mutagenesis with the HXB2-D clone of human immunodeficiency virus type 1.

Antiviral Agents↗
PubMed1993

The effect of test protocol instructions on the measurement of muscle function in adult women.

Consideration of the anatomy of the nervous system and events (ie., age, physical training, motor learning) that invoke changes in neural regulatory mechanisms and other bodily systems renders the impact of the type of instruction used to elicit a maximal effort in the assessment of muscle function across age, among different muscle groups, and for different parameters of muscle function tenuous. Hence, the efficacy and effect of using two types of instructions (rate vs. strength) on the assessment of the isometric functional capacity of six muscle groups were examined in women (N = 143) aged 25-74 years. The subjects were categorized by age into 10, 5-year groups. Measures of maximal force (MF), maximal rate of force increase (MR), total impulse (TI), time to MF (MFT), time to MR (MRT), and plateau time (PLT, time between 90% MF and MF) were obtained from the force-time recordings of maximal voluntary isometric contractions of the finger flexors, thumb extensors, elbow flexors and extensors, and ankle dorsiflexors and plantar flexors. Repeated measures analyses of variance indicated that instruction type influenced (p < .05) the magnitude and pattern of the force-time recordings, with the degree of difference dependent upon the muscle group and parameter of muscle function examined. Use of the rate instruction yielded greater MRs (40.9-541.0 N/sec) than the strength instruction. The strength instruction elicited greater MFs (6.4-326.7 N), longer MFTs (0.72-1.50 sec), MRTs (0.05-0.15 sec) and PLTs (0.31-0.79 sec), and greater TIs (25.1-1,079.8 N-sec) than the rate instruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The basis of the paradoxical disturbance of temperature perception in ciguatera poisoning.

The basis of the paradoxical reversal of temperature perception commonly described in ciguatera poisoning has never been defined. The sensations experienced are described as tingling, burning, "dry ice-like", smarting, and "electric". Studies have demonstrated that these types of sensations are generated in C-polymodal nociceptor fibers in skin and deep structures and the intensity of these sensations depends on the intensity of discharge in these fibers. Ciguatoxin causes persistent sodium channel opening in nerve membrane resulting in oscillations in membrane potentials and runs of spontaneous discharges. Studies on ciguatera victims in which their hands were immersed in water baths ranging from 0 degree C to 50 degrees C, suggest the paradoxical sensory discomfort experienced is, most likely, a result of an exaggerated and intense nerve depolarization occurring in peripheral small A-delta myelinated and in particular, C-polymodal nociceptor fibers. Gross temperature perception was found to be intact in ciguatera poisoning and reversal of temperature does not occur.

Abdominal Pain↗
PubMed1992

Homodimer formation of retinoid X receptor induced by 9-cis retinoic acid.

Retinoid response pathways are mediated by two classes of receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). A central question is whether distinct response pathways are regulated by these two classes of receptors. The observation that the stereoisomer 9-cis-retinoic acid binds with high affinity to RXRs suggested that this retinoid has a distinct role in controlling RXR activity, but it was almost simultaneously discovered that RXRs function as auxiliary receptors for RARs and related receptors, and are essential for DNA binding and function of those receptors. Hence, although RARs seem to operate effectively only as heterodimeric RAR/RXR complexes, RXRs themselves apparently function predominantly, if not exclusively, as auxiliary receptors. Here we report that 9-cis-retinoic acid induces RXR homodimer formation. Our results demonstrate a new mechanism for retinoid action by which a ligand-induced homodimer mediates a distinct retinoid response pathway.

Animals↗