Search PubMed⌕ Search

Biomedical subjects

L Jones

Publications and source records attributed to L Jones.

At least 199 records · Page 11Linked to original sources
PubMed1996

Purification and characterization of a (R)-3-hydroxybutyrate dehydrogenase deletion mutant. Evidence for C-terminal involvement in enzyme activation by lecithin.

(R)-3-Hydroxybutyrate dehydrogenase (BDH; EC 1.1.1.30) is a lipid-requiring enzyme with a specific requirement of phosphatidylcholine for optimal function. The purified enzyme, devoid of lipid, can be reactivated with soluble lecithin or by insertion into phospholipid vesicles containing lecithin. In order to obtain insight into the mechanism of lipid activation, a C-terminal deletion mutant was constructed which contained 18 amino acids less than BDH. The purified deletion mutant had low, but detectable catalytic activity in the absence of phospholipid. However, the addition of either soluble lecithin or phospholipid vesicles containing lecithin had no effect on enzymatic function. Further experiments were conducted to determine if the deletion mutant had also lost its ability to bind to phospholipid vesicles and natural membranes. Our findings indicate that the mutant enzyme binds to both liposomes and rat liver microsomes. These results suggest that the binding of BDH to the phosphatidylcholine head group is independent of its interaction with the apolar core of the phospholipid bilayer.

Animals↗
PubMed1996

Management cost of acute limb ischaemia.

The cost of attempting limb salvage in patients who presented with acute lower limb ischaemia was recorded prospectively for 20 months. Seventy-five patients were admitted during the study; 45 were treated primarily by radiological intervention and 18 had primary surgery. The remainder were treated conservatively. Patients who had primary surgery required fewer visits to the operating theatre than those who had primary thrombolysis, but there was no difference in the total time that the theatre or radiology suite was occupied: median 2.3 (10th centile range 1.5-5.0) h and 3.0 (2.0-5.0) h respectively. Median (range) cost of disposables for performing surgery was Pounds 82 (58-169) and for thrombolysis was Pounds 407 (252-596). When the costs of using the theatre or radiology suite were included, the costs of both treatments were similar: surgery Pounds 683 (309-1438) and lysis Pounds 861 (611-1244). Median (10th centile range) inpatient stay for surgical patients was 9 (3-18) days and for those having thrombolysis 11 (2-29) days. Median (10th centile range) costs for bed occupancy were similar in both groups: surgery Pounds 2497 (643-9115) and lysis Pounds 2189 (902-6020). Mean cost for attempting limb salvage by surgery was Pounds 3429 (1094-10065) compared with Pounds 3230 (1543-8353) for thrombolysis.

Acute Disease↗
PubMed1996

Silicone does not potentiate development of the scleroderma-like syndrome in tight skin (TSK/+) mice.

Several reports have implicated an association between the development of connective tissue disorders and exposure to silicone in breast implant patients. These connective tissue disorders include local or systemic scleroderma-like syndrome and have been characterized by fibrosis as well as the presence of circulating autoantibodies. Whether silicone does potentiate the development of a scleroderma-like syndrome is still to be defined. The purpose of the present study was to determine the effect of silicone on the tight skin (TSK/+) mouse which develops a scleroderma-like syndrome and on its normal pa/pa TSK/- littermate. Groups of six TSK and five of their normal pa/pa littermates were injected subcutaneously with low molecular weight silicone (LMW-PDMS), high molecular weight silicone gel (HMW-PDMS), incomplete Freunds' adjuvant (IFA) or Hank's balanced salt solution (HBSS) in the dorsal neck area and ventrally in the upper chest region. Serum was obtained prior to and 1 month after injection of silicone, IFA, or control HBSS. Antibody levels to bovine serum albumin (BSA), RNA polymerase (RNAP) and topoisomerase I were determined. Mice were then euthanized and strips of skin from the injection sites as well as samples of kidney and liver were studied histologically. No significant pathological changes were observed in TSK/- mice 1 month following injection with HBSS, LMW-PDMS or HMW-PDMS. Skin samples from TSK/+ mice which received LMW-PDMS showed hyperplasia of the dermis and peri-panniculus carnosus tissue and infiltrates of macrophages containing lipid-like vacuolated materials. Lipid vacuoles were observed throughout the deeper dermis as multiple loculated vacuoles. TSK mice which received HMW-PDMS showed similar thickening of the dermis and the peri-panniculus carnosus connective tissue. There were no significant differences in the histologic characteristics of the silicone-injected TSK/+ mice compared to those that received HBSS or IFA. No detectable changes in the kidney, spleen, or liver samples taken from TSK/+ or TSK/- mice injected with HBSS, IFA or silicone (LMW-PDMS, HMW-PDMS) preparations were noted. Baseline circulating antibody levels to BSA, RNAP and topoisomerase were significantly higher in TSK/+ mice compared to the control TSK/- littermates. Administration of silicone (LMW-PDMS or HMW-PDMS) did not significantly alter circulating antibody levels to BSA, RNAP and topoisomerase in either the TSK/+ or the TSK/- mice. The results of this study indicate that silicone administration does not potentiate the development of the scleroderma-syndrome characterized by skin lesions and presence of circulating antibodies in the TSK/+ model.

Animals↗
PubMed1996

Development of scleroderma-like syndrome in Tsk/+ mice is not enhanced by silicone administration.

The possible role of silicone in the pathogenesis of a scleroderma-like syndrome is still unresolved. It has been proposed that silicone escaping from breast implants potentiates the progression of the disease. To clarify whether silicone enhances development of fibrotic skin lesions and autoantibodies, we tested its effect on tight skin (TSK/+) mice. TSK/+ mice spontaneously develop skin fibrosis and characteristic autoantibodies which resemble human scleroderma. The results of the present study indicate that silicone administration does not enhance development of skin fibrosis nor synthesis of autoantibodies to RNA polymerase and topoisomerase in TSK/+ mice.

Animals↗
PubMed1996

Normal adult swallowing of liquid and viscous material: scintigraphic data on bolus transit and oropharyngeal residues.

Scintigraphic data are provided for 20 normal control subjects, 39-65 years of age. Each subject swallowed 10 cc of water and 10 cc of a more viscous material (1,100 centipoise) consisting of apple juice thickened with Thick-It, a commercial food thickener. The test substances were combined with 2.5 mCi Tc-99m sulfur colloid. Scintigraphic data were acquired in dynamic mode for 10 sec at 25 frames/sec as the subject swallowed. Time-activity (TA) data were used to compute transit times, percentage residues in the mouth and pharynx, percent ingested, and a derived swallow efficiency score. The liquid was ingested in a single swallow by all subjects, and 9 cc was actually transferred to the esophagus. In contrast, for the viscous material, 11/20 subjects performed a second clearing swallow within the 10-sec interval. On the first swallow with the viscous substance, an average of 7 cc was transferred to the esophagus. Scintigraphy offers an excellent technique for determining natural and preferred volumes for swallowing a variety of bolus consistencies, since it can quantify the volume of each swallow or partial swallow. In this group of subjects the oral discharge time was shorter with the viscous material than with the water, but the pharyngeal transit times were not significantly different for the two bolus consistencies. Numerical efficiency scores were lower for the viscous material, indicating that such a measure is bolus dependent.

Adult↗
PubMed1996

An unusual presentation of intestinal lymphangiectasia.

Intestinal lymphangiectasia is a rare disorder, usually presenting with protein-losing enteropathy leading to oedema and ascites. We describe a case that presented as an acute surgical emergency with pain and a mass in the right iliac fossa, which was successfully treated by resection of the involved segment of ileum.

Abdomen, Acute↗
PubMed1996

Neovascularisation is the principal cause of varicose vein recurrence: results of a randomised trial of stripping the long saphenous vein.

OBJECTIVES: To determine whether routine stripping of the long saphenous vein reduces recurrence after varicose vein surgery. DESIGN: Randomised controlled trial. All operations done by a consultant vascular surgeon. Two year follow-up. MATERIALS AND METHODS: One hundred patients with primary long saphenous varicose veins (133 legs) were randomised. Two year follow-up in 81 patients (113 legs) with questionnaire, clinical examination and Duplex scanning. RESULTS: Some 89% remained satisfied with the results of their surgery, though 35% had recurrent veins on clinical examination. Recurrence was reduced from 43 to 25% in patients who had their long saphenous vein stripped (p = 0.04, chi 2). Neovascularisation (serpentine tributaries arising from the ligated saphenofemoral junction) was detected in 52% of limbs and was the commonest cause of recurrence. Most tributaries were less than 3 mm in diameter and only caused recurrence if the long saphenous vein or a major thigh vein was intact. Twelve patients had tributaries greater than 3 mm diameter and all had recurrent varicose veins. CONCLUSIONS: Recurrence is common after varicose vein surgery and in this study was caused principally by neovascularisation at the ligated saphenofemoral junction. Clinical recurrence is reduced by routine stripping of the long saphenous vein.

Adult↗
PubMed1996

Human saphenous vein organ culture: a useful model of intimal hyperplasia?

OBJECTIVES: Although cell culture techniques and animal models of intimal hyperplasia have increased our current understanding of the aetiology of vein graft stenosis, the results of such studies have been difficult to relate to the human situation. DESIGN: The present study was designed to validate an organ culture of human saphenous vein by comparing the changes occurring in cultured vein with those seen in pathological vein graft stenoses and to identify a suitable marker of cell proliferation. MATERIALS AND METHODS: Saphenous vein segments were cultured for 14 days, fixed in formalin and processed for immunohistochemistry. Freshly excised stenoses were fixed and processed similarly. A number of markers of cell proliferation were evaluated in the culture system in order to identify the one best suited to this particular model. RESULTS: Marked similarities were observed in the cellular and extracellular matrix composition, and electron microscopy revealed that both the neointima of the cultured vein and the pathological lesion contained an abundance of smooth muscle cells of a secretory phenotype. Bromodeoxyuridine proved to be the most reliable proliferation marker and revealed that early proliferation in the superficial layers of the vein intima gave rise to the formation of neointima. Both proliferation and neointimal thickness were maximal by day 14 in culture. Proliferation declined rapidly thereafter, and the neointima was maintained. CONCLUSIONS: The changes occurring in cultured vein and graft stenoses bore many similarities, thereby justifying the use of organ culture as a valuable experimental tool.

Bromodeoxyuridine↗
PubMed1996

Angiogenesis in abdominal aortic aneurysms.

OBJECTIVES: To determine the degree of neovascularisation in the wall of abdominal aortic aneurysms in comparison to atherosclerotic control aortas, and to correlate the angiogenic response with the extent of the cellular inflammatory infiltrate. DESIGN: Histopathological study. MATERIALS: Aortic samples were obtained from patients with abdominal aortic aneurysms and from atherosclerotic controls. METHODS: Samples were stained with haematoxylin and eosin, and Miller's elastin and Van Gieson stain, EVG, and a monoclonal antibody specific to human endothelial cells. Within the aortic wall three histological regions were defined, the media, the adventitia and a transition zone. The number of capillary like, thin walled vessels were measured in each region, and the cellular infiltrate was quantified. RESULTS: The number of newly formed vessels was increased in all layers of aneurysmal wall in comparison to control samples (p<0.001). The degree of neovascularisation correlated with the extent of the inflammatory infiltrate (rs=0.45, p<0.01). CONCLUSIONS: This study demonstrated that abdominal aortic aneurysms are associated with a marked angiogenic response, which is related to the degree of inflammation within the aortic wall. It is hypothesised that anti-angiogenic agents may play a role in the medical management of aortic aneurysmal disease.

Aged↗
PubMed1996

The physiologic response of exercising in the water and on land with and without the X1000 Walk'N Tone Exercise Belt.

Study of the physiological effects of exercise that decreases lower joint impact is needed. Participants (N = 18) were exposed to either land or water exercise that included or did not include wearing a belt. Physiological variables of caloric expenditure, net oxygen cost, net oxygen pulse, and heart rate were assessed. A 2 x 2 (Environment x Belt) analysis of variance (ANOVA) revealed a significant environment main effect for net oxygen cost and caloric expenditure. Water actually decreased the energy cost of the exercise. A 2 x 2 x 4 (Environment x Belt x Time) ANOVA revealed a significant environment main effect for net oxygen cost and caloric expenditure. Specifically, land heart rates increased over time, whereas water heart rates did not.

Adult↗
PubMed1996

The effect of respirator training on the ability of healthcare workers to pass a qualitative fit test.

OBJECTIVES: To determine the effect of different methods of training on the ability of hospital workers to wear respirators and pass a qualitative fit test, and to compare the direct cost of the training. DESIGN: 179 hospital employees were recruited for study and were stratified into three groups based on the type of training they received in the use of respirators. Employees in Group A received one-on-one training by the hospital's industrial hygienist and were fit tested as part of this training. Employees in Group B received classroom instruction and demonstration by infection control nurses in the proper use of respirators, but were not fit tested as part of training. Employees in Group C received no formal training. Each participant in our study underwent a subsequent qualitative fit test using irritant smoke to check for the employee's ability to adjust correctly the fit and seal of the respirator. The direct cost of each method of training was determined by accounting for the cost of trainers and the cost of employee-hours lost during training. SETTING: 775-bed Veterans' Affairs hospital. RESULTS: 94% of Group A participants (49 of 52) passed the qualitative fit test, compared to 91% of Group B participants (58 of 64) and 79% of Group C participants (50 of 63; P = .036, 2 x 3 chi-square). Group A had a significantly higher pass rate than Group C (P = .043), but Group B did not differ significantly from Group A or Group C. Location or professional status did not affect pass rate, but prior experience wearing respirators did. When the study groups were compared after stratifying for prior experience, we found no difference in pass rates, except when Groups A and B (those with any training) were combined and compared with Group C (107 of 116 versus 50 of 63, P = .05, Mantel-Haenszel chi-square). We estimate that the method of training involving individual instruction followed by fit testing took 20 minutes per employee to complete, compared to 10 minutes per six employee class for the method of classroom demonstration. The difference in direct cost between the two methods, applied to the training of 1,200 employees at our hospital, would be approximately $19,000 per year. CONCLUSION: Our study indicates that training in the proper use of respirators is important, but the method of training may not be, as the two methods we evaluated were nearly equivalent in their pass rates on fit testing (94% versus 91%). Fit testing as part of training may have enhanced the performance of our participants marginally, but was more time consuming and accounted for most of the excess cost.

Chi-Square Distribution↗
PubMed1996

Spoilation and clinical performance of monthly vs. three monthly Group II disposable contact lenses.

Twelve subjects were fitted with a high water content, nonionic contact lens (Pilkington Barnes-Hind "Precision UV"), which was either replaced every month for 3 months or worn for 3 consecutive months before replacement occurred. Visual quality, high and low contrast acuity, and comfort were unaltered with either replacement schedule, but overall satisfaction was significantly greater with the shorter replacement schedule (p = 0.04). Front surface wettability revealed a large amount of intersubject variability and was reduced at the 3-month visit with the longer replacement period lenses (p = 0.003). Visible deposits also increased with longer replacement times (p < 0.05). Laboratory-based analytical results showed that both gross lipid and gross extractable protein significantly increased in the 3-month lenses compared with the 1-month lenses, with 44% less lipid accumulation and 60% less protein deposition occurring with the shorter replacement time. The results support the replacement of high water content lenses on a monthly basis.

Adult↗
PubMed1996

Self-medication in acute surgical wards.

Self-medication of oral drugs is not current practice on surgical wards. We have introduced a system for suitable patients in which they give to themselves all their oral medication while in hospital. This was introduced in stages to gain the confidence of staff. Many patients wish to self-medicate; this system allows better use of the drugs that they bring into hospital from home; more appropriate timing when in hospital and speed up discharge procedures, as the patient is already familiar with, and has a supply of, their drugs to take home.

Clinical Nursing Research↗
PubMed1996

Mother's own expressed breast milk: guide-lines for storage.

Guide-lines for milk collection and storage must aim to provide human milk with a composition as similar as possible to that stored within the human breast. The way in which milk is collected and stored has a significant effect on milk composition. Polyethylene storage bags should not be used to store milk for hospitalized infants. Glass containers fitted with an air-tight seal maintain immunoglobulin stability, and minimise fat loss.

Breast Feeding↗
PubMed1996

Which smokers are helped to give up smoking using transdermal nicotine patches? Results from a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Nicotine replacement therapy is effective in helping people to give up smoking. The three forms now available--transdermal patches, chewing gum and nasal spray--deliver nicotine at different rates and to different levels. Therefore, it might be expected that smokers with different characteristics, and at different levels of nicotine dependence, will be helped more by one or other method. AIM: The aim of the study was to examine whether the effectiveness of transdermal patches is related to nicotine dependence or to other smoker characteristics and to investigate factors predicting smoking cessation using patches. METHOD: Data from a randomized, double-blind, placebo-controlled trial of nicotine transdermal patches were analysed retrospectively. The trial, conducted in 1990-1992, involved 1686 patients recruited from 19 general practices in Oxfordshire. The main outcome measure was continuous smoking cessation from 8 to 52 weeks after the start of patch use, biochemically validated at 12, 24 and 52 weeks. The effectiveness of the patches was measured by the relative odds of sustained cessation using nicotine patches compared with placebo patches. RESULTS: Nicotine transdermal patches were more effective in smokers with moderate nicotine dependence [odds ratio (OR) 1.94; 95% confidence interval (CI) 1.24-3.04] than in mildly or highly dependent smokers (OR 0.98; 95% CI 0.58-1.65) (difference in ORs P < 0.05) and more effective in those aged 24-49 years (OR 1.89; 95% CI 1.24-2.87) than in older smokers aged 50-65 years (OR 0.88; 95% CI 0.49-1.59) (difference in ORs P < 0.05). Abstinence from smoking in the first week of the trial was the strongest predictor of sustained cessation and was more common among smokers using nicotine patches than those using placebo patches (33% of 842 compared with 22% of 844; P < 0.001). Of first-week abstainers, 25 and 28% of 277 and 182 in the nicotine and placebo groups, respectively, achieved sustained cessation compared with 4% of 565 and 2% of 662 first-week smokers. CONCLUSION: Nicotine transdermal patches were most effective for smokers with moderate nicotine dependence and for younger smokers. Early abstinence from smoking was the strongest predictor of sustained cessation. A week's trial of the patch proceeding to longer term use if abstinence is achieved may be an effective policy.

Administration, Cutaneous↗