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Biomedical subjects

N Wright

Publications and source records attributed to N Wright.

At least 73 records · Page 4Linked to original sources
PubMed1988

The cell cycle time in intestinal crypts by simulation of FLM experiments.

A computer program is developed that permits simulation of the dynamic behaviour of cells in intestinal crypts (Meinzer & Sandblad, 1985). Here we present the simulation of FLM data which is compared with the experimental findings of Al-Dewachi et al. (1974). The phase durations and total cycle times of cells in the jejunal crypts of rats were calculated. Additionally, the influence of various control parameters on the simulation output is discussed, e.g. the standard errors of phase times and the grain dilution at mitosis.

Animals↗
PubMed1988

Dialyzer re-use--a multiple crossover study with random allocation to order of treatment.

A multiple crossover research study was used to evaluate the effect of dialyzer re-use on fever, blood leaks, serum urea and creatinine values and symptoms. Each of 6 crossover periods consisted of 4 weeks on either single-use or re-use, 1 week washout, 4 weeks on the alternative treatment and 1 week washout. The re-use consisted of 6 uses of each dialyzer and the washout weeks consisted of 3 single-use sessions. Analysis of paired observations within rather than between patients showed no effects of time (i.e. among crossover periods 1 through 6) or number of re-uses (i.e. among uses 1 through 6). There was no significant difference for temperature change during dialysis, blood leak rate, or the serum urea and creatinine values before the first dialysis of each washout period. There were no differences for symptoms of pruritus, cramps, nausea, headache, chest pain, backache or fatigue. There were no clinical advantages or disadvantages associated with dialyzer re-use.

Cellulose↗
PubMed1988

Clinical effects of electromagnetic stimulation as an adjunct to periodontal therapy.

The clinical effects of electromagnetic stimulation (EMS) on periodontal soft tissues and alveolar bone level were studied among 23 patients. The sides of the arch to receive EMS were randomly selected and exposed for a period of eight weeks following periodontal surgery. The contralateral control sides received surgery only. The electromagnetic signal was a multiple pulse signal with 21 asymmetrical quasirectangular pulses per burst and a burst frequency of 16.9 Hz. The peak magnetic field strength reached 0.46 Gauss. Changes from baseline in clinical attachment level, probing depth, and radiographic alveolar bone level were assessed at six, 12, and 18 months postsurgically. A greater gain of clinical attachment level following EMS was observed only for pockets with initial depth of 1 to 3 mm. There were no consistent differences between test (EMS) and control sides in the change of clinical attachment level or probing depth for pockets deeper than 4 mm. Radiographically, the test sides demonstrated statistically significant gain of alveolar bone level compared with the control sides at six months following surgery. Hereafter, the rates of change were similar in the stimulated and unstimulated sides, and the total gain of alveolar bone level remained greater in the test side throughout the observation period. Within the limitations of this study, it was concluded that electromagnetic stimulation does not promote gains in clinical attachment or alveolar bone level to the extent that it can be recommended as an adjunct to conventional periodontal therapy.

Adult↗
PubMed1987

Risk-factor changes in wives with husbands at high risk of coronary heart disease (CHD): the spin-off effect.

This study of 220 wives of participants from four of the 22 clinics in the Multiple Risk Factor Intervention Trial (MRFIT) addresses the question of whether spouses of men exposed to a continuous coronary heart disease (CHD) risk-factor intervention program (SI group) make changes in their own risk status compared to wives of men who did not receive the intervention program (UC group). Total serum cholesterol and low-density lipoprotein (LDL) cholesterol were significantly lower for the SI wives. These differences were found for both hypertensive and normotensive wives, although the magnitudes were much greater for the hypertensive wives. There were also significant differences between the two groups of wives in the food-record rating and in dietary-knowledge scores, indicating that the probable mechanism for the beneficial effect of the intervention with respect to cholesterol levels was the change in the family diet. Although not statistically significant, differences indicating a lower risk for SI wives were found for diastolic blood pressure. There was also a greater mean reduction in cigarettes per day for SI wives who smoked.

Attitude to Health↗
PubMed1987

Evaluation of a preferred provider organization.

Preferred provider organizations (PPOs) have emerged as a new approach to organizing health care services; the promise of melding the primary strengths of indemnity insurance with HMO plans was rapidly embraced. The performance of PPOs has not yet been measured critically, despite their growth to over 250 plans. A single, large case study of PPO design and performance is examined, revealing a mixed but hopeful picture of administrative challenges, physician response, patient use patterns, and cost reductions, PPOs offer fertile ground for future research.

Adolescent↗
PubMed1986

Changing motivation in severely suicidal patients.

While the ambiguity of suicidal patients' stated motivations has been studied in some detail, less attention has been given to the changeability of their motivations. Twenty-six patients who had taken an overdose of paraquat, a highly lethal herbicide, were questioned about their motivation at the time of admission and 24 hours and 3, 7 and 10 days later. Although 25 patients claimed that they wished to die at the time of admission, all of the 14 surviving patients wished to live at the time of discharge from hospital. Of the 12 patients who died, 6 stated that they no longer wished to die in the last interview before their death. During the following year 3 of the 14 surviving patients killed themselves. The findings emphasize the importance of thoroughly assessing all aspects of the suicidal patient's situation in determining risks. The patient's stated intentions should be but one factor considered.

Adolescent↗
PubMed1986

Are there differences in the cell cycle of normal and malignant cells? An approach to the analysis of the clonal expansion of cells in malignant epithelial proliferations in situ.

The Williams-Bjerknes model for clonal expansion of transformed cells in epithelia was used to examine a series of related questions about the growth of in situ proliferations in epidermis. Bowens disease, actinic keratosis and lentigo maligna lesions were reconstructed on a three-dimensional basis, and all were found to behave differently: the evidence supported the proposal that the 'carcinogenic advantage' enjoyed by transformed cells was proliferative in nature, and indeed varied between the three lesions. We conclude that the clonal expansion of a single cell, with different proliferative carcinogenic advantage, can explain the three-dimensional appearances of these in situ proliferations; furthermore, the well-known 'multifocality' of in situ epidermal proliferations can also be explained by the clonal expansion of a single transformed cell.

Animals↗
PubMed1985

The pharmacokinetics of cefotaxime and ceftriaxone in renal and hepatic dysfunction.

The pharmacokinetics of cefotaxime, its desacetyl metabolite and ceftriaxone were studied in 72 patients with various degrees of renal and hepatic failure. Patients with severe renal failure (creatinine clearance 3 to 10 ml/min) had a cefotaxime serum half-life of 2.6 h, a desacetyl cefotaxime serum half-life of 10 h and ceftriaxone serum half-life of 17 h. In the case of ceftriaxone, this serum half-life could be very variable--increasing to over 50 h, possibly due to co-existing hepatic dysfunction. Increases in serum half-life were found for cefotaxime in the presence of liver disease.

Adult↗
PubMed1983

Temocillin elimination in patients with varying degrees of renal failure.

Temocillin is a new penicillin combining activity against Gram-positive organisms, beta-lactamase stability and an exceptionally long half-life. In patients with normal renal function the half-life was approximately 4-6 h and this increased to 30 h in patients with severe renal failure. It is suggested that unlike other penicillins this compound may give adequate antibacterial concentration with once daily dosing in subjects with normal renal function; this will certainly require reduction in subjects with severely impaired renal function.

Half-Life↗
PubMed1983

The elimination of sulbactam alone and combined with ampicillin in patients with renal dysfunction.

Sulbactam, a beta-lactamase inhibitor, was given as a single agent to 12 subjects with varying degrees of renal dysfunction. The half-life in normal subjects was 1.1 h and increased to 21.3 h in those with terminal renal failure. Sulbactam together with ampicillin was given to a further five subjects. It was concluded that if the two agents are given together, the plasma ratio of one to the other will remain constant whatever the renal function.

Ampicillin↗
PubMed1983

Cefotetan elimination in patients with varying degrees of renal dysfunction.

The pharmacokinetics of cefotetan following a 0.5 g intravenous dose were studied in 15 patients with varying degrees of renal failure. In patients with glomerular filtration rates (GFR) greater than 50 ml/min the serum half-life was between 3 and 5 h. The half-life increased to 15 h as the GFR fell to 10 ml/min. When the GFR was less than 10 ml/min the serum clearance of cefotetan was very variable, the half-life being between 15 and 50 h. Cefotetan was eliminated almost entirely by the kidneys. It is suggested that cefotetan 0.5 g 12-hourly is appropriate for patients with GFRs greater than 20 ml/min. For patients with GFRs between 10 and 20 ml/min 0.5 g every 24 h should avoid gross accumulation.

Anti-Bacterial Agents↗
PubMed1983

Identification of Leishmania spp. by multiple isozyme analysis.

Biochemical data as enzyme profiles which were obtained by cellulose acetate electrophoresis (CAE) are reported on 44 Leishmania isolates. These enzyme profiles contain data from 25 enzyme systems. Calculations from the CAE data on average polymorphism indicated that Leishmania species/types or groups can be expected to be about 25% polymorphic, which suggests that isolate pairs which have profiles about 75% or more identical should be considered samples from the same species/type, and isolates that are significantly less than 75% identical are therefore samples from different species/types. There were five major groupings of isolates according to enzyme profiles, which were for the most part consistent with groupings of the genus based on other criteria: braziliensis, mexicana, donovani, tropica and hertigi profiles. Within these groups there were natural subgroups of isolates among which there was 75% or more allozyme or allomorph (genetic) identity. The braziliensis profile group had two subgroups: panamensis and braziliensis or guayanensis, and the mexicana profile group had three subgroups: mexicana, amazonensis and peruviana. There was an indication that an L. d. infantum isolate might be different from the other L. donovani isolates, and that the L. tropica isolates could be samples from more than one group. The data reported here are consistent with previously reported CAE data, but suggest that isozyme analysis of Leishmania isolates leading to identification should be based on data from many enzyme systems rather than just a few.

Humans↗
PubMed1983

Epithelial changes of the vas deferens after vasectomy and vasovasostomy in dogs.

Mucosal morphology of the vas deferens was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) after vasectomy and vasectomy reversal in dogs. Morphological changes occurred in the proximal (testicular) end of the vas deferens after vasectomy. Luminal dilatation, with an increase in 70% mean diameter, occurred due to build up of pressure. This resulted in flattening of the columnar cells, loss of stereocilia and presence of interspersed microvilli. The urethral portion of the vas deferens remained unchanged. Following vasovasostomy, reappearance of normal epithelial cells occurred through squamous metaplasia. Identical changes have also been observed after vasectomy in human vas deferens. It is fair to assume that similar recovery of the vasal mucosa may occur in humans after successful vasovasostomy.

Animals↗
PubMed1983

Morphologic changes of the vas deferens after vasectomy and vasovasostomy in dogs.

The fine structure of the vas deferens was studied by SEM and TEM after vasectomy and delayed vasovasostomy in 18 dogs. Mucosal changes were observed in the testicular end of the vas deferens after vasectomy. Identical changes have been observed in the vas deferens in humans after vasectomy. Microsurgical vasovasostomy resulted in reappearance of normal epithelial cells lining the lumen of the vas deferens by means of squamous metaplasia. In six dogs, prevasectomy and postvasovasostomy sperm counts were compared. These counts returned to normal levels, but they never reached or exceeded the prevasectomy values.

Animals↗
PubMed1982

Sympathomimetic drugs stimulate the output of secretory glycoproteins from human bronchi in vitro.

1. We describe a method for supporting pieces of human bronchi in Ussing chambers, for radiolabelling the contents of the secretory cells with 35S, and for collecting radiolabelled macromolecules secreted on to the luminal aspect of the tissue. This method has previously been used to study airway secretions in animals [R. J. Phipps, J. A. Nadel & B. Davis, American Review of Respiratory Disease, (1980) 121, 359-365]. Evidence is given that the radiolabelled molecules are secretory glycoproteins, probably mucus glycoproteins. 2. Phenylephrine, an alpha-adrenoceptor agonist, increased the rate at which the bronchi secreted radiolabelled glycoproteins. Thymoxamine, an alpha-adrenoceptor antagonist, blocked this effect but propranolol, a beta-adrenoceptor antagonist, did not. 3. Dobutamine, a beta-adrenoceptor agonist, increased the rate of secretion of radiolabelled glycoproteins. Propranolol blocked this but thymoxamine did not. 4. Salbutamol, a beta 2-adrenoceptor agonist, also increased the rate of secretion of radiolabelled glycoproteins. Propranolol blocked this effect. 5. We conclude that both alpha- and beta- adrenoceptor agonists increase the rate of glycoprotein secretion in human bronchi in vitro and that this almost certainly means that they increase the rate of mucus secretion.

Autoradiography↗