Search PubMed⌕ Search

Biomedical subjects

K Lawrence

Publications and source records attributed to K Lawrence.

At least 37 records · Page 2Linked to original sources
PubMed1996

Relationship between health status and postoperative return to work.

BACKGROUND: Time back to work or normal activity is often regarded as an outcome measure of interest after surgery. It has recently been used as a way of quantifying the benefits of minimal access surgery. However, the extent to which variation in time back to normal reflects differences in health status is unclear. METHODS: The relationship was examined in 140 patients recovering from inguinal hernia repair. A multi-dimensional measure of health status, the Short Form 36 (SF-36), was administered preoperatively, and at ten days and six weeks postoperatively. The relationship between scores on the SF-36 dimensions and return to normal activity was examined using correlation statistics and stepwise regression. RESULTS: Health status dimensions measuring role limitation owing to physical restriction at 10 days and 6 weeks, and role limitation owing to mental problems at ten days were associated with time to return to normal on univariate analysis. Social class was also strongly associated. Using stepwise regression these two dimensions of health status together explained 33 per cent of the variance in time to normal. Other factors unrelated to health status clearly contributed to this outcome. CONCLUSION: Time back to normal activity postoperatively is influenced by a number of factors unrelated to health status and is an unreliable proxy for it. Time to normal is therefore, not a good outcome measure for quantifying the benefits of surgical interventions. Claims currently being made to justify investment in some minimal access interventions should be interpreted in the light of this.

Activities of Daily Living↗
PubMed1995

Randomised controlled trial of laparoscopic versus open repair of inguinal hernia: early results.

OBJECTIVE: To establish the safety, short term outcome, and theatre costs of transabdominal laparoscopic repair of inguinal hernia performed as day surgery. DESIGN: Randomised controlled trial. The control operation was the two layer modified Maloney darn. SETTING: Teaching hospital and district general hospital. SUBJECTS: 125 men randomised to laparoscopic or open repair of inguinal hernia. OUTCOME MEASURES: Morbidity, postoperative pain and use of analgesics, quality of life, and theatre costs. Outcome was assessed by questionnaires administered to patients daily for 10 days and at six weeks postoperatively and by outpatient review at six weeks. Return to normal activity was assessed by questionnaire at three months. RESULTS: One vascular complication (2%) occurred in the group that had open repair. Seven complications (12%) including vessel injury and early recurrence arose in the group that had laparoscopic repair (difference in complication rate 10% (95% confidence interval 4% to 18%; P = 0.02). Pain scores and quality of life assessed by the short form 36 showed a significant benefit to the group that had laparoscopic repair in the early postoperative period. Return to normal activity was not significantly different between the two groups. Total theatre costs were higher in the group that had laparoscopic repair (mean cost for laparoscopic repair 850 pounds (622 pounds to 1078 pounds); mean cost for open repair 268 pounds (245 pounds to 292 pounds)). CONCLUSIONS: Because of the greater complication rate and higher theatre costs for laparoscopic repair and the patient outcome preferences expressed, the results of larger trials of clinical and cost effectiveness using recurrence as the primary outcome measure should be known before laparoscopic herniorrhaphy is widely adopted.

Adult↗
PubMed1995

Sensitivity to change of health status measures in a randomized controlled trial: comparison of the COOP charts and the SF-36.

This study compared the sensitivity to change of comparable dimensions of a multi-item multi-dimensional health status measure (the SF-36) with the equivalent single item domains on the Dartmouth COOP charts. One hundred and twenty nine patients were randomized to either day case laparoscopic surgery (n = 60) or open inguinal hernia repair (n = 69). Respondents completed the SF-36 and COOP charts at baseline (prior to surgery) and at follow up at 10 days and 6 weeks. Equivalent dimensions of physical functioning, mental health/emotional condition, social activities, pain and overall condition/general health on the two questionnaires were compared. Despite slightly different pictures of change provided by the physical functioning and 'overall condition/general health' dimensions the general picture of change provided by the two instruments was similar. At 10 days, patients who underwent open surgery reported far greater levels of dysfunction than those who underwent laparoscopic surgery on both questionnaires. At 6 weeks the pain dimension of both questionnaires indicated a large improvement from baseline, whilst no other domain on either questionnaire for either group indicated such improvement. The general picture of change provided by the two measures was similar. The results suggest that both the SF-36 and the COOP charts may prove suitable for the assessment of health perception outcomes in surgical clinical trials. Differences on certain domains were caused in large measure by the nature of the questions posed. The study once again highlights the importance of checking item content to determine the suitability of any particular measure for a given study.

Adult↗
PubMed1994

Role of vif during packing of the core of HIV-1.

The viral infectivity factor gene vif of human immunodeficiency virus type 1 (HIV-1) has been shown to enhance the cell-free infectivity of HIV-1 virus particles. Previous studies have demonstrated that vif increases viral infectivity at the time of virus production, most likely by affecting viral protein processing, virus assembly, or virus maturation. The effect of vif on the assembly and maturation of HIV-1 propagated in CEM, Jurkat, and SupT1 cells was examined by electron microscopy and goniometer analysis. CEM and Jurkat cells are nonpermissive and partially permissive for the replication of vif--defective viruses, respectively, while SupT1 cells are completely permissive. In CEM and Jurkat cultures, the morphology of immature vif+ and vif- virions was similar but immature virus particles were observed at a slightly higher frequency in cultures infected with the vif- virus. At later stages of virus maturation, however, nonhomogeneous packing of the core was detected in the majority of vif- virus particles produced in CEM and Jurkat cells. In the absence of vif, the cone-shaped virus core contained dense material in its broad end but, in contrast to vif+ virions, the material inside its narrow end appeared transparent. The narrow part of the vif- virus core was surrounded by a shell and was attached to the viral envelope by a core-envelope link structure. Vif- virus particles with a lateral body of core material adjacent to the viral envelope were also observed more frequently in CEM and Jurkat cultures. In contrast, in SupT1 cultures the morphology of mature vif+ and vif- virus particles was similar. These results suggest that vif is associated with an effect during the final stages of packing of the viral nucleoprotein core. This effect may be important for the infectivity of HIV-1 virus particles.

Cell Line↗
PubMed1994

Permittivities of fresh fruits and vegetables at 0.2 to 20 GHz.

Permittivities, moisture contents, tissue densities, and total soluble solids data were determined for samples of twenty-three kinds of fresh fruits and vegetables at 23 degrees C. Permittivities were measured at 41 frequencies between 200 MHz and 20 GHz with an open-ended coaxial-line probe and a microwave network analyzer. Results of the permittivity measurements are presented graphically, and dielectric constant and loss factor values at six frequencies across the range are tabulated along with sample descriptions and moisture, density, and total soluble solids data. Although specific values differ, the dielectric constant decreases steadily with increasing frequency, dropping more rapidly at frequencies above 5 GHz. Values for the loss factor decrease as frequency increases above 200 MHz to a broad minimum in the 1- to 3-GHz region and then increase again as the frequency approaches 20 GHz. The dielectric behavior of the fruit and vegetable tissues appears to be influenced by ionic conductivity and bound water relaxations at the lower frequencies and by free water relaxation at the higher end of the frequency range.

Fruit↗
PubMed1994

The expression of proliferation-dependent antigens during the lifespan of normal and progeroid human fibroblasts in culture.

Normal human fibroblasts display a limited lifespan in culture, which is due to a steadily decreasing fraction of cells that are able to proliferate. Using antibodies that react with antigens present in proliferating cells only, in an indirect immunofluorescence assay, we have estimated the fraction of proliferating cells in cultures of normal human fibroblasts. Furthermore, we have estimated the rate of decline in the fraction of proliferating cells during the process of cellular ageing by application of the assay to normal human fibroblasts throughout their lifespan in culture. Werner's Syndrome is an autosomal recessive disease in which individuals display symptoms of ageing prematurely. Werner's Syndrome fibroblasts display a reduced lifespan in culture compared with normal human fibroblasts. Like normal human fibroblasts, the growth of Werner's Syndrome fibroblasts is characterised by a decreasing fraction of cells reacting with the proliferation-associated antibodies throughout their lifespan in culture. However, the rate of loss of proliferating cells in Werner's Syndrome fibroblasts during the process of cellular ageing is accelerated 5- to 6-fold compared with the rate determined for normal human fibroblasts.

Antigens↗
PubMed1994

Essential role of vif in establishing productive HIV-1 infection in peripheral blood T lymphocytes and monocyte/macrophages.

The role of vif during the establishment of human immunodeficiency virus type 1 (HIV-1) infection of peripheral blood T lymphocytes and monocyte/macrophages was investigated using vif mutants of three HIV-1 proviral DNAs. Vif was found to be essential for the establishment of productive HIV-1 infection in peripheral blood T lymphocytes after cell-free infection with HXB2 and DFCI-HD, a vpr-positive, vpu-positive, nef-positive derivative of HXB2. A chimeric HIV-1 provirus in which the T-cell line-tropic env sequences in DFCI-HD were replaced with the macrophagetropic env of the ADA strain was constructed for studies on the role of vif during the establishment of HIV-1 infection in primary monocyte/macrophages. These studies showed that vif is also essential for the initiation of productive HIV-1 infection in primary monocyte/macrophage cultures after cell-free virus transmission. The DFCI-HD-ADA virus was shown to replicate in the CD4+ T-cell line Molt 4 clone 8 but not in other T-cell or monocytic cell lines, as previously shown for another macrophagetropic strain YU-2 (1), suggesting that this cell line may be useful for future studies on at least some macrophagetropic strains of HIV-1. The finding that vif is essential for the establishment of productive HIV-1 infection in primary T lymphocytes and monocyte/macrophages suggests that vif may be required for HIV-1 transmission and disease pathogenesis during natural infections and thus may be a good target for prophylactic or therapeutic intervention.

Cell Line↗
PubMed1993

Detection of proopiomelanocortin-derived antigens in normal and pathologic human skin.

We investigated the presence of proopiomelanocortin (POMC) products in sections of skin from normal subjects and patients with neoplastic and non-neoplastic cutaneous disorders. Antibodies specific against adrenocorticotropin, beta-melanotropin, and beta-endorphin were used for detection and characterization of cell types bearing POMC peptides. POMC products were not observed in sections of normal skin from the corporal (non-scalp) areas (six cases), whereas the hair follicles of scalp skin exhibited positive immunostains that were readily apparent (four cases). POMC products were frequently detected in corporal skin affected by diseases (13 of 26 cases), for example, psoriatic keratinocytes, the inflammatory infiltrate in scarring alopecia, nevocytes, the epithelial cell nests of basal cell carcinoma, and melanoma cells. Further tests were performed in keloids, a primary reactive skin disorder, to evaluate whether POMC accumulation represented a disease-related phenomenon or an expression of normal cutaneous reactivity. POMC products were consistently detected (10 of 11 cases) in the keratinocytes and mononuclear cells at keloid lesions. Thus these observations indicate that POMC products may accumulate locally in lesional skin representing, presumably, a novel cutaneous response to injury. The broad spectrum of POMC products detected suggests that these arise from production in situ (expression of the POMC gene itself) by human skin.

Adrenocorticotropic Hormone↗
PubMed1992

Role of vif in replication of human immunodeficiency virus type 1 in CD4+ T lymphocytes.

The viral infectivity factor gene vif of human immunodeficiency virus type 1 has been shown to affect the infectivity but not the production of virus particles. In this study, the effect of vif in the context of the HXB2 virus on virus replication in several CD4+ T-cell lines was investigated. vif was found to be required for replication in the CD4+ T-cell lines CEM and H9 as well as in peripheral blood T lymphocytes. vif was not required for replication in the SupT1, C8166, and Jurkat T-cell lines. The infectivity of vif-defective viruses depended on the cell type in which the virus was produced. In CEM cells, vif was required for production of virus capable of initiating infection in all cell lines studied. vif-defective virus produced by SupT1, C8166, and Jurkat cells and the monkey cell line COS-1 could initiate infection in multiple cell lines, including CEM and H9. These results suggest that vif can compensate for cellular factors required for production of infectious virus particles that are present in some cell lines such as SupT1, C8166, and Jurkat but are absent in others such as CEM and H9 as well as peripheral blood T lymphocytes. The effect of vif was not altered by deletion of the carboxyl terminus of gp41, a proposed target for vif (B. Guy, M. Geist, K. Dott, D. Spehner, M.-P. Kieny, and J.-P. Lecocq, J. Virol. 65:1325-1331, 1991). These studies demonstrate that vif enhances viral infectivity during virus production and also suggest that vif is likely to be important for natural infections.

Amino Acid Sequence↗
PubMed1991

Ethanol-induced inhibition of carbachol-stimulated uptake of calcium in PC12 pheochromocytoma cells.

Using a rapid-quench technique the effects of ethanol on the uptake of 45Ca2+ into PC12 pheochromocytoma cells were studied in suspension. At concentrations achieved during acute intoxication in man (25-100 mM), ethanol inhibited both the carbachol-stimulated and K(+)-induced uptake of calcium. Inhibition of carbachol-stimulated uptake of Ca2+ occurred rapidly, within seconds at 27 degrees C, whereas inhibition of K(+)-induced uptake of Ca2+ developed more slowly. This disparity between the kinetics of these ethanol-induced inhibitions was unexpected, because the uptake of Ca2+, evoked by either stimulus, is thought to occur predominantly through a common pathway, namely voltage-sensitive Ca2+ channels. This difference may reflect differential effects of ethanol on multiple carbachol-activated pathways for entry of Ca2+. Alternatively, carbachol may facilitate the inhibitory action ethanol on voltage-dependent channels. This apparent facilitation was manifested principally by a more rapid onset of inhibition, although the extent of inhibition by ethanol, in the presence of carbachol, was also increased. In preincubation experiments, ethanol did not enhance the apparent agonist-induced desensitization of carbachol-evoked uptake of Ca2+. Nevertheless, an acute interaction between cholinergic agonists and ethanol, affecting homeostasis of Ca2+ may play a role in the pathophysiology of alcohol intoxication.

Calcium↗
PubMed1991

Platelet [3H]imipramine and alpha 2-adrenoceptor binding in normal subjects during desipramine administration and withdrawal.

The effect of desipramine 150 mg daily on platelet [3H]imipramine and alpha 2-adrenoceptor binding sites was studied over a 6-week period and for 6 weeks after withdrawal. Modest (10%) increases in [3H]imipramine binding site densities during treatment were noted with a decrease between 1 and 4 weeks after withdrawal. No effect was found on alpha 2-adrenoceptors. Time of day appeared to have some effect on the results found. None of the [3H]imipramine binding site effects of desipramine, on treatment or following withdrawal, was comparable in magnitude to trait differences that were also found between subjects.

Adult↗