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Biomedical subjects

S Jones

Publications and source records attributed to S Jones.

At least 415 records · Page 23Linked to original sources
PubMed1993

Simian immunodeficiency virus (mac 251-32H) transmembrane protein sequence remains conserved throughout the course of infection in macaques.

Two cynomolgus macaques were infected with a genetically complex challenge stock of simian immunodeficiency virus (SIVmac251-32H). The polymerase chain reaction (PCR) was used to amplify the env gp41, rev, and nef overlapping coding sequences from provirus present in the blood of both animals at 1, 6, and 15 months post infection (p.i.). The predominant, env sequences found in both animals at the three time points were very similar to that found in the original 11/88 challenge stock. The functionally important hydrophobic fusion and membrane-spanning domains within gp41 remained conserved throughout the course of infection. Nucleotide variation within the region corresponding to the REV response element (RRE) was limited to four positions, none of which were predicted to cause any significant disruption to the secondary structure of the RRE. Very little genetic variation was observed in and around the cluster of potential glycosylation sites of the external portion of gp41. However, the existence of a previously assigned variable region elsewhere in the cytoplasmic domain of gp41 was confirmed. The three gene loci (env, rev, and nef) examined varied independently. All changes in the predominant protein sequences were brought about by single nucleotide substitutions only. After 15 months of infection with SIV, 1 animal was sick from SIV-induced disease whereas the other remained healthy. In-frame stop codons within the transmembrane protein occurred with a much greater frequency in the healthy animal.

Amino Acid Sequence↗
PubMed1993

Can effluent hyaluronic acid or creatine kinase predict sinusoidal injury severity after cold ischemia?

It is well recognized that current selection criteria used to assess liver grafts before implantation are inaccurate and correlate poorly with graft outcome. A bench or laboratory-based test that could indicate the extent of liver injury immediately before implantation would be a valuable adjunct to clinical assessment. Hyaluronic acid (HA) and creatine kinase (BB component; CK-BB) levels in the caval effluent after liver perfusion have been suggested as indicators of preservation injury. Our objective was to investigate the relevance of preserved liver effluent HA and CK-BB as a predictor of early graft function. Perfused liver effluent HA and CK-BB levels were measured. Graft function was measured in terms of peak serum aspartate transaminase and its level on day 5 postoperatively as well as peak bilirubin level and prothrombin time. The cold ischemia time (CIT) was recorded. Statistical comparisons were made among HA level, CK-BB level, CIT, and graft function parameters. The study was conducted at The Liver and Hepatobiliary Unit, Queen Elizabeth Hospital, Birmingham, United Kingdom. Fifty patients undergoing OLT were studied. HA level was measured in 50 patients and CK-BB level in 30 patients. The main outcome measures were graft function and graft outcome. The graft function data are grouped according to effluent HA levels above or below 400 micrograms/L. Thirteen patients (26%) had a level below 400 micrograms/L and the remaining 37 (74%) were above this threshold. There were no significant differences between the groups for these indicators of graft function. There was no difference between the 2 groups for CIT. The overall median HA level was 1212 micrograms/L (range 39-4000 micrograms/L). The median total CK activity in the perfusate was 302 IU/L (range 118-1155 IU/L). The proportion of CK-BB activity from this total was 146 IU/L (8-641 IU/L), or 48% of the total CK activity. In a multiple regression analysis with CK-BB activity as the dependent variable, there was no demonstrable numerical relationship to graft function. In a separate multiple regression analysis similar results were obtained for HA. We conclude that the level of HA or CK-BB levels should not be used in determining the suitability for implantation of a harvested hepatic allograft.

Adolescent↗
PubMed1993

Cognitive screening in mild brain injury.

A study of patients with mild traumatic brain injuries was performed to determine if cognitive screening in the acute care setting can identify patients who will have cognitive dysfunction following discharge to home. While still hospitalized, 166 patients were assessed with a cognitive screening tool. After discharge, telephone follow-up contacts were made by a nurse to assess for subjective reports of cognitive difficulties. A subsample (N = 39) received additional comprehensive cognitive evaluation after discharge. Statistically significant results were noted between cognitive screen and cognitive evaluation results (chi-square = 24.28, p < .0000) and between cognitive screen results and follow-up findings (chi-square = 6.7, p = .0350). Study results support the use of cognitive screening in the acute care setting to identify patients with mild traumatic brain injury who are likely to experience residual cognitive deficits after discharge so appropriate intervention may be planned.

Adolescent↗
PubMed1993

Evaluation of syringe-exchange for HIV prevention among injecting drug users in rural and urban areas of Wales.

This paper considers the prevention of HIV in rural and urban areas among both opiate and non-opiate drug injectors. A 2-year study evaluated specialist and community based syringe-exchange provision in Wales. Numbers of clients and patterns of attendance at eight syringe-exchange schemes were monitored together with comparative cross-sectional studies of attenders (n = 152) and non-attenders (n = 176) from the population of drug injectors in 1990 and 1991. A total of 1171 clients made 7553 visits in the 2-year period, 110,000 syringes were issued and 80% of needles and syringes were returned. There were few demographic differences between attenders and non-attenders, but large and significant differences in HIV risk behaviour; only 9% of attenders had recently shared syringes in 1990 (10% in 1991) compared to 41% of non-attenders (39% in 1991). The catchment areas of specialised services were limited (5 miles or less) and insufficient in rural areas. Alternative community approaches to syringe distribution and exchange are examined.

Cross-Sectional Studies↗
PubMed1993

Annual variations in grass pollen seasons in London 1961-1990: trends and forecast models.

The record of daily average grass pollen concentrations monitored at St Mary's Hospital, Paddington, London, U.K. since 1961 is the longest duration pollen data set in Europe. Analysis of the results identifies the trends and characteristics of grass pollen seasons over three decades. During this time seasonal allergic rhinitis has increased significantly in Britain. The annual start dates, length of season and severity are examined in relation to the main meteorological variables of cumulated temperatures above 5.5 degrees C and precipitation measured at one site within London and two in the surrounding rural areas. Land-use changes are also considered. Significant decreases have taken place in both the duration and severity of the seasons, particularly between the 1960s and the early 1970s but also through the last 20 yr. This is largely a result of a decrease in pollen abundance in the region. The decline in pollen counts has slowed in recent years due to the increase in flowering grasses caused by the set-aside policy and by uncut verges. Grass pollen seasons have tended to start later over the last two decades, despite an increase in the cumulated temperature profiles during late winter and spring. Empirical models have been developed using multiple regressions to incorporate meteorological and pollen data for the last 20 yr in order to forecast the start dates, duration and severity of the grass pollen seasons. These models were applied successfully using the data for 1991 and 1992. Predictions of the main characteristics of the pollen seasons can be obtained relatively early in the year through the use of these models by employing the monthly weather forecasts in conjunction with long-term average weather profiles.

Air↗
PubMed1993

Heparin skin necrosis--an important indicator of potentially fatal heparin hypersensitivity.

Skin necrosis at injection sites is a rare complication of heparin therapy. In this report, we describe only the second case of the even rarer complication of skin necrosis occurring at sites distant to those of subcutaneous heparin injections. The patient had also suffered systemic thrombotic events due to heparin-dependent platelet activation prior to the development of the skin necrosis, although these had not been recognized as such at the time. The development of heparin-induced skin necrosis should result in the immediate cessation of heparin therapy in order to prevent potentially fatal thrombotic events. This is in contrast to warfarin-induced skin necrosis, where therapy may be continued or restarted at a lower dose.

Aged↗
PubMed1993

Total atrial paralysis after permanent dual chamber cardiac pacing.

A 73 year old woman with known ischaemic heart disease and ischaemic ventricular tachycardia underwent temporary dual chamber pacing as part of the treatment to suppress tachycardia. Insertion of a permanent dual chamber system seven days later was uncomplicated. Total atrial paralysis, with inability to pace the atrium or obtain an atrial electrocardiogram from four atrial sites, developed within 24 hours of the permanent system being implanted. Atrial electrical and mechanical function recovered over several weeks.

Aged↗
PubMed1993

Neural network feature detector for real-time video signal processing.

The application of artificial neural networks to real-time image processing tasks requires the use of dedicated, high performance hardware. A linear array processor called HANNIBAL has been developed which implements the backpropagation neural learning algorithm on-chip. This paper considers the design of a complete neural system which integrates HANNIBAL into an existing image processing environment. The goals for the design of the system have been set partly by the primary application, namely feature recognition, but mainly by the desire for a flexible, high performance hardware tool for the study and evaluation of range of neural image processing applications.

Algorithms↗
PubMed1993

Ventricular stroke work and efficiency both remain nearly optimal despite altered vascular loading.

Recent clinical and animal studies have suggested that ventricular-vascular coupling normally operates at either optimal ventricular efficiency (EFF = stroke work/myocardial oxygen consumption) or stroke work (SW) and that efficiency in particular is compromised by cardiac dysfunction. These distinctions between coupling states at maximal work vs. efficiency are largely based on theoretical models. To date, there are few direct experimental data defining optimal conditions for each parameter, respectively, in the same heart or tests of whether changes from these conditions must produce significant declines in both parameters. Therefore, 10 isolated blood-perfused canine hearts were studied at varying contractilities, with the heart ejecting into a simulated three-element Windkessel model of arterial impedance. For a given inotropic state [indexed by the slope of the end-systolic pressure-volume relationship (Ees)], myocardial oxygen consumption and SW were measured over a broad range of afterload resistances. The latter was indexed by the effective arterial elastance (Ea) and ventricular-vascular interaction expressed by the ratio of Ea to Ees (Ea/Ees). On average, maximal SW occurred at Ea/Ees = 0.80 +/- 0.16, whereas EFF was maximal at Ea/Ees = 0.70 +/- 0.15 (P < 0.01). However, these differences were small, and both SW and EFF were > or = 90% of their respective optima over a broad overlapping range of Ea-to-Ees ratios (0.3-1.3, corresponds with ejection fractions ranging from approximately 40 to 80%). These data show that both SW and efficiency are nearly maximal under many conditions of ventricular-vascular interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Communications between medical referrers and child psychiatry staff.

Communicating in organisations is often seen as the key to good practice, good relationships and good service. A survey was conducted on what communication was wanted by medical referrers to a Department of Child and Family Psychiatry, the types of feedback preferred, and its timing and content. The main finding was that paediatricians received different and better information about referred patients than general practitioners.

Child↗
PubMed1993

A pressure ulcer prevention program.

The prevention and management of pressure ulcers often creates challenging situations requiring specialized knowledge and expert, consistent nursing care. In order to promote pressure ulcer prevention and control costs at a 350-bed community hospital, a "Pressure Ulcer Prevention Program" was developed. This program was developed upon completion of a baseline audit determining the extent of skin problems, equipment in use, and nursing documentation regarding skin care. Five months after initiation of the program, a second audit was conducted to evaluate the effectiveness of the program. An overall decrease in pressure ulcer incidence was found and the documentation of pressure ulcer prevention was improved.

Adolescent↗
PubMed1992

Neurotransmitter modulation of calcium channels is dependent on the charge carrier used in the recording of currents.

Currents through calcium channels were recorded using calcium, barium and strontium as charge carriers in NG108-15 cells. The mean normalised peak current amplitude at 0 mV was not significantly different between the charge carriers; however, the sustained component (measured at the end of the 500 ms command step) was ca. 3 times larger in barium and strontium. Further, the inhibition by acetylcholine or noradrenaline, although the same at the peak of the current envelope, was significantly greater on the sustained portion of the current for barium and strontium. Increasing internal calcium-buffering (to reduce calcium-dependent inactivation with calcium as the charge carrier) did not increase the amount of inhibition of the sustained portion of current. These results suggest a cautious approach to analysis of neurotransmitter modulation of calcium currents using other charge carriers than calcium.

Acetylcholine↗
PubMed1992

Cost implications of the British Pacing and Electrophysiology Group's recommendations for pacing.

OBJECTIVE: To compare present pacing practice with the recommendations recently published by the British Pacing and Electrophysiology Group and to assess the increase in annual budget required to implement these recommendations in a regional cardiothoracic unit. DESIGN: Retrospective analysis of pacemaker implantation for 1991 with calculation of the costs required to implement the group's recommendations based on average 1991 costs of the types of pacing generators and electrode leads used. SETTING: Regional cardiothoracic unit for South West Thames Health Authority. PATIENTS: 433 consecutive patients receiving permanent pacemaker generators: 76 (18%) with sinus node disease; 270 (62%) with atrioventricular block; 25 (6%) with both sinus node disease and atrioventricular block; 59 (14%) with chronic atrial fibrillation and atrioventricular block; and 3 (1%) with carotid sinus or malignant vasovagal syndromes. RESULTS: Only 102 (24%) patients received pacemaker generators recommended by the British Pacing and Electrophysiology Group; however, 355 (82%) patients were older than 65 years, and 264 (61%) were aged 75 or over. The cost of hardware for pacing was 462,885 pounds. Using generators as recommended would have cost 810,525 pounds for "optimal" systems (an increase of 75%) and 710,750 pounds for "alternative" systems (an increase of 54%). These increases would have been considerably reduced by limiting the use of sophisticated pacing to younger patients (aged under 75). Further savings could be made by using the least expensive pacing models available. CONCLUSIONS: Implementing these recommendations should reduce morbidity related to bradyarrhythmia but will lead to major increases in pacing costs. Age and patients' expected activity may be used to select simple pacing systems and thus to contain cost. More research is needed to determine which patient groups will benefit most from complex pacing systems.

Adult↗