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Biomedical subjects

B Lewis

Publications and source records attributed to B Lewis.

At least 163 records · Page 9Linked to original sources
PubMed1987

Ancrod enhances the thrombolytic effect of streptokinase and urokinase.

Since thrombi continue to incorporate fibrin during lysis we tested the effect of pretreatment with ancrod, a defibrinating agent from Malaysian pit viper venom, on thrombolysis with urokinase and streptokinase. Thrombi were induced by copper-coils in the carotid arteries of the dogs, weighed after 1 hour and inserted into the femoral arteries of the same animals. They were then exposed for 15 min to iv boluses of streptokinase 10,000 U/kg, urokinase 10,000 U/kg and urokinase 25,000 U/kg with or without pretreatment with ancrod. Ancrod depleted fibrinogen within 5 min and enhanced the lytic effect of streptokinase from 25 +/- 8% to 59 +/- 13% (p less than .05), urokinase 10,000 U/kg from 16 +/- 11% to 66 +/- 18% (p less than .01) and urokinase 25,000 U/kg from 27 +/- 17% to 85 +/- 8% (p less than .001) of the initial thrombus weight. Ancrod itself did not activate plasminogen to plasmin. We conclude that ancrod enhances thrombolysis probably by depleting fibrinogen and preventing new fibrin incorporation into the thrombus during lysis.

Ancrod↗
PubMed1987

A method for quantifying lipoprotein flux rates between plasma and arterial intima in vivo.

A new method is proposed for measuring in vivo the rates of transfer of plasma lipoprotein into and out of arterial intima in man. The technique requires the injection of a lipoprotein which can be labelled with two different tracers, followed by a single arterial sample during elective surgery. The feasibility of the method was tested by computer simulation and it was found that measurement uncertainties of the order of those likely in practice produced uncertainties of 7% SD in the calculated influx and 16% SD in the calculated efflux rates. The principal assumption, that lipoprotein in arterial intima can be modelled as a single compartment system, was tested in a preliminary study in an anaesthetised dog: reasonable evidence of monocompartmental behaviour was obtained. The new method was used in a preliminary study of three patients undergoing elective arterial surgery. Low density lipoprotein (LDL) labelled with 125I was injected about 24 h before surgery, followed by 131I-labelled LDL 4 to 6 h before surgery. The radioactivities of washed extracts of arterial intima were then measured in a gamma counter. LDL flux rates were higher in atherosclerotic specimens than in less seriously diseased or normal tissue, and were highest in the most hyperlipidaemic patient.

Animals↗
PubMed1987

Familial renal abnormalities associated with the oligohydramnios tetrad secondary to renal agenesis and dysgenesis.

Thirty-four families of index cases with the oligohydramnios tetrad secondary to renal agenesis/dysgenesis were screened for renal abnormalities using Real Time ultrasonography. The index cases were separated into two groups. Group 1 consisted of cases of perinatally lethal renal disease and Group 2 of cases of renal dysgenesis secondary to the urethral obstruction malformation. Renal ultrasound screenings of 23 families in Group 1 demonstrated two previously unidentified cases of unilateral renal agenesis in siblings. Screening of 11 families in Group 2 revealed one sibling with a hydronephrotic kidney and one parent with an ectopic pelvic kidney. There is a recurrence risk of 3.5-5% in families with perinatal lethal renal disease and an increased risk of silent renal anomalies in first degree family members. The recurrence risk is low in families of infants with renal dysgenesis secondary to the urethral obstruction malformation, but immediate family members are at increased risk of structural and functional urinary anomalies. Routine renal ultrasound screening of first degree relatives of infants with lethal renal agenesis and dysgenesis is recommended.

Amniotic Fluid↗
PubMed1987

Plasma lipid concentrations: the concept of "normality" and its implications for detection of high cardiovascular risk.

The relation between serum cholesterol concentrations and the incidence of coronary heart disease is continuous and curvilinear; there is neither epidemiological nor biological evidence to support the existence of a threshold value. There is a clinical need, however, for an acceptable definition of action limits and desirable ranges, based on the evidence that raised cholesterol concentrations are causally related to atherosclerotic heart disease. The European Atherosclerosis Society has proposed a set of cut off points, which, together with age and the presence of other risk factors, direct the clinician to an appropriate level of treatment. Because the changes of serum cholesterol during adult life appear unphysiological, these action limits do not require adjustment for age. The distribution of serum cholesterol in the United Kingdom population is such that a case finding strategy is required to identify the many persons at very high risk of coronary disease. Measurements of triglyceride, high density lipoprotein, apolipoproteins, and the investigation of hyperlipoproteinemia are informative but less mandatory.

Adult↗
PubMed1987

Strut fracture and other events after valve replacement with the 60 degree convexoconcave Björk-Shiley prosthesis.

A total of 688 patients received 808 Björk-Shiley prostheses during a 5 year span. Cumulative duration of follow-up totaled 1175.4 patient-years (1368 valve-years). Linearized rates in percent per patient-year for valve-related events (95% confidence limits) were: strut fracture, 0.5 (0.00 to 1.03); infective endocarditis, 0.94 (0.39 to 1.49); thromboembolism, 2.2 (1.37 to 3.052); valve impingement, 0.3 (0.00 to 0.77); and anticoagulant-related hemorrhage, 3.1 (2.15 to 4.14). No valve thrombosis occurred. Actuarial patient survival, including in-hospital mortality, was: aortic valve replacement, 79.8 +/- 3.4%; mitral valve replacement, 71.7 +/- 4.9%; double valve replacement, 59.8 +/- 7.5%. Incremental risk factors for death were age over 65 (p = .001), preoperative infective endocarditis (p = .04), and associated procedures (p = .0002). Although this prosthesis carries a low risk of infective endocarditis and thromboembolism, concern has been raised regarding its structural integrity.

Actuarial Analysis↗
PubMed1986

Reducing the risks of coronary heart disease in individuals and in the population.

Since moderately elevated levels of risk factors for coronary heart disease (CHD) are very common in the UK, a population strategy is the only practicable means of reducing risk in the large numbers of people affected. Even the most effective use of such a strategy is likely to leave a substantial minority of the population at high risk of CHD due to genetic and diet-resistant hyperlipidaemia. Hence the application of a high-risk strategy is equally essential and involves case-finding by widespread use of serum cholesterol measurement, followed by individual medical care. The two strategies are interdependent and additive and should be introduced in parallel to lessen the burden of CHD in the population as a whole and in the very-high-risk minority within the population. There will be a need for more lipid clinics, in addition to the introduction of population measures to combat CHD.

Adult↗
PubMed1986

Home support of patients with end-stage malignant bowel obstruction using hydration and venting gastrostomy.

Palliative terminal care of patients with malignant bowel obstruction is a major clinical and ethical challenge. These patients are often mentally alert and ambulatory, but are kept in the hospital for hydration, nasogastric suction, and pain control. Parenteral nutrition requires frequent metabolic monitoring, is expensive, and is ethically questionable. We have used an alternative method of home management for 27 patients who met the following criteria: inoperable bowel obstruction due to untreatable cancer, an estimated life expectancy of between 2 weeks and 3 months, and understanding of the goals and limits of therapy. Hydration was provided by 10 percent dextrose and electrolyte solutions administered as overnight infusions through long-term central venous catheters. Thirteen patients with complete bowel obstruction required a venting gastrostomy which, when connected to passive drainage, relieved nausea and vomiting. The mean duration of survival was 64 days (range 9 to 223 days). Acceptance by patients and families was excellent, although most acknowledged increased costs due to limited insurance coverage for outpatient care. Seven patients returned to the hospital for terminal care (average stay 3.2 days), and 20 chose to die at home. The mean daily expense for fluids and supplies was +73.50, with an overall cost decrease of $900,000 compared with inpatient care. Home support with fluids and gastric venting is a humane, cost-effective alternative to in-hospital care for selected patients.

Abdominal Neoplasms↗
PubMed1986

The single-parent family. How an understanding physician can help.

Families who have become separated from one of the parents by death or divorce face much stress and adjustment. In addition to carrying the extra burdens of parenting and running a household alone, the single parent may feel isolated from friends and family. Loneliness, depression, and confusion can manifest themselves in various physical and emotional ways. At the beginning of an office visit, the physician should try to ascertain whether any important changes have occurred in the patient's life and should record this information in the patient's chart. Once single parenthood is determined, the importance to the patient and the circumstances of the separation should be obtained. Children in different age-groups often demonstrate specific regressive disorders when a life crisis occurs, and a perceptive physician may spot such behavior and counsel both the parent and the child. Possibly the most effective treatment in such a situation is understanding, reassurance, and listening.

Adult↗
PubMed1986

Clinical results after bioprosthetic aortic valve replacement in patients with and without coronary artery disease: value of concomitant myocardial revascularization.

The present study analyzes a 7-year experience of two concurrent groups of patients, one with and one without coronary artery disease. These groups underwent aortic valve replacement within the same time frame. They had the same method of myocardial protection and type of valve substitute, and there was no postoperative anticoagulant therapy. There was no statistically significant difference in hospital and late mortality, or in actuarial survival of the two groups after 4 years. Bypass grafting in patients with coronary artery disease undergoing aortic valve replacement reverts these groups of patients to the longterm prognostic level of patients with isolated aortic valve disease undergoing aortic valve replacement.

Journal Article↗
PubMed1986

Lipid peroxidation of low density lipoprotein by human endothelial cells modifies its metabolism in vitro.

Low density lipoprotein (LDL) undergoes qualitative changes when incubated with endothelial cells. Changes in LDL induced by cultured human endothelial cells were associated with release of substances reacting to thiobarbituric acid; they were prevented by addition of EDTA. Modification of LDL by human endothelium, therefore, appears to involve lipid peroxidation. Proneness of LDL to this process was indicated by its occurrence, to a smaller extent, on incubation in the absence of endothelium. Lipid peroxidation of LDL altered its electrophoretic mobility. Modified LDL, but not native LDL, was readily catabolised by human macrophages. Conditioning by human endothelium increased the rate of fractional catabolism of LDL in rabbits. If lipid peroxidation of LDL takes place in vivo it may promote conversion of macrophages to lipid-laden foam cells in the developing atheromatous plaque.

Animals↗
PubMed1986

Insulin pump therapy in the very low birth weight infant.

Ten critically ill, very low birth weight infants less than 30 weeks' gestation were treated with exogenous insulin administered through a continuous insulin infusion pump (Betatron II, Cardiac Pacemaker, Inc). Infants were hyperglycemic to dextrose infusions greater than 6 mg/kg/min. The blood glucose concentration became normal in all infants within two to four hours, with varying requirements for continued insulin treatment. Tolerance to intravenous dextrose increased from a mean of 7.4 mg/kg/min to 11.2 mg/kg/min with glycosuria. Energy intake increased from 49.5 calories/kg/d prior to insulin pump therapy to 70.4 calories/kg/d afterward (P less than .01) with weight gain changed from -23 g/d to +13 g/d (P less than .01). One unexpected observation was the apparent normalization of blood glucose homeostasis on higher dextrose doses among some infants after only one three- to six-hour treatment with insulin. The continuous insulin infusion pump is a flexible tool that allows insulin infusion rates to be changed as dictated by blood glucose values without altering other parenteral infusions.

Acute Disease↗
PubMed1986

Prednimustine in refractory non-Hodgkin's lymphoma: a phase II study of the Northern California Oncology Group.

Fifty-six patients with advanced non-Hodgkin's lymphoma (NHL) were entered into a phase II study of prednimustine, an ester of chlorambucil and prednisolone. All patients were refractory to extensive prior combination chemotherapy. Therapy with prednimustine, 100 mg/m2/day orally, was given for three consecutive days every 2 weeks. The overall response rate in 43 evaluable patients was 30% (13/43), with 9% (4/43) achieving complete response (CR) and 21% (9/43) achieving partial response (PR). In the favorable histology subgroup (23 patients), the response rate was 39% (9/23), with 4% (1/23) achieving CR and 35% (8/23) achieving PR. In the unfavorable histology subgroup (20 patients), responses were seen in 20% (4/20) with 15% (3/20) achieving CR, all in heavily pretreated diffuse histiocytic lymphoma. Toxicity of this regimen was mild, with leukopenia below 3,000/mm3 in 22% and thrombocytopenia below 90,000/mm3 in 16% of patients. A positive correlation was observed between response and hematologic toxicity, indicating the potential for a dose-escalation schedule in future trials. These data confirm activity of prednimustine in NHL refractory to standard treatment. In view of its relatively mild toxicity, we conclude that prednimustine is an appropriate agent to test in combination chemotherapy regimens in this group of lymphomas.

Adult↗