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Biomedical subjects

J Perkins

Publications and source records attributed to J Perkins.

At least 73 records · Page 4Linked to original sources
PubMed1993

Bone surface preparation in cemented joint replacement.

We studied the effects of nine techniques of bone surface preparation on cement penetration and shear strength at the cement-bone interface in a standard model of bovine cancellous bone. In unprepared bone the mean penetration was 0.2 mm and the mean shear strength of the interface was 1.9 MPa, less than that of the underlying bone. Brushing with surface irrigation gave mean penetrations of 0.6 to 1.4 mm and mean shear strengths of 1.5 to 9.9 MPa. In 50% of specimens the interface was weaker than the underlying bone. The use of pressurised lavage resulted in mean penetrations of 4.8 to 7.9 mm and mean shear strengths of 26.5 to 36.1 MPa, which were greater than those of the cancellous bone in all specimens. Pressurised lavage was equally effective alone or in combination with brushing, and its efficacy was not altered by using pulsed or continuous jets, or by changing the temperature of the solution from 21 degrees C to 37 degrees C.

Animals↗
PubMed1993

The platelet-refractory bone marrow transplant patient: prophylaxis and treatment of bleeding.

Refractoriness to platelet transfusions remains a significant problem for oncology patients, occurring in 30% to 70% of multiply transfused recipients with bone marrow failure. Nonimmune causes are often present and include disseminated intravascular coagulation, concurrent use of amphotericin B, infection, presence of palpable spleen, use of antibacterial antibiotics, bleeding, veno-occlusive disease, and fever. Immune causes are also commonly responsible for refractoriness, with HLA alloimmunization dominating the list of immune factors. HLA antibodies can be identified in 25% to 30% of transfused leukemia patients and can be present in as many as 80% of aplastic anemia patients. Developing a consistent approach to managing these refractory patients is essential to preventing and treating bleeding manifestations. An HLA type should be obtained for all patients anticipated to have chronic transfusion requirements. Screening for lymphocytotoxic antibodies can confirm suspected HLA alloimmunization. Histocompatible platelets (cross-match compatible and HLA matched) should be provided for all patients with HLA antibodies. A number of other therapeutic modalities have been used in an effort to manage the alloimmunized patient; most of these methods have had little or no proven benefit. When bleeding develops in the alloimmunized patient, there are few therapeutic choices. If histocompatible platelets are unavailable or unsuccessful, massive platelet transfusions of pooled platelet concentrates are commonly used, although this practice is of no proven benefit. While antifibrinolytic agents have been available for over 30 years, they are only recently being applied to control bleeding in chronic thrombocytopenia. We have successfully managed bleeding episodes in thrombocytopenic bone marrow transplant recipients with the use of epsilon aminocaproic acid. A number of these patients were platelet refractory with demonstrable platelet antibodies. Platelet refractoriness continues to plague multiply transfused oncology patients. While preventative measures may ultimately benefit some patients, this problem will continue to manifest itself. A consistent approach to transfusion support needs to be implemented to best manage this challenging patient population.

Aminocaproic Acid↗
PubMed1992

How much should we tell them? Patient education for people with diabetes.

Patient education assumes that by giving people with diabetes information about their condition, they will take steps to prevent potential complications. Not all clients, however, are willing to follow advice or are prepared to make short-term sacrifices for long-term gains. Informing clients about the potential for complications, however, enables them to share responsibility for the outcome.

Diabetes Mellitus↗
PubMed1992

Parenteral ondansetron for the treatment of chemotherapy- and radiation-induced nausea and vomiting.

Ondansetron hydrochloride dihydrate is a 5-hydroxytryptamine (5-HT3) antagonist that was recently approved by the Food and Drug Administration for the treatment of chemotherapy-induced emesis. The mechanism of action is thought to be due to competitive inhibition of specific serotonin receptors in the central nervous system and gastrointestinal tract. In clinical trials with cisplatin-induced emesis, ondansetron resulted in complete control of vomiting (0-2 episodes) in 55-87% of patients during the first 24 hours of chemotherapy administration. It was significantly more effective than metoclopramide in comparative trials. Ondansetron is also being investigated for the treatment of radiation- and anesthesia-associated nausea and vomiting. Studies in animals demonstrate potential efficacy in the treatment of anxiety, drug withdrawal, and schizophrenia. The drug is generally well tolerated, with no reported extrapyramidal reactions.

Antiemetics↗
PubMed1991

Effects of chronic systemic insulin delivery on insulin action in dogs.

The metabolic consequences of the prolonged systemic insulin delivery associated with human pancreas transplantation have not been precisely defined. To determine if systemic insulin delivery in the absence of immunosuppressive agents results in alterations in hepatic or extrahepatic insulin action, three groups of dogs were studied 2 months after either a sham operation or after their pancreatic venous drainage was severed and anastomosed to the inferior vena cava or portal vein (sham, peripheral and portal groups, respectively). The pattern of venous drainage was documented by measuring vena cava and portal insulin concentrations before and after glucose injection. Systemic insulin concentrations were higher (p less than 0.05) in the peripheral group than in the portal group both following a 14-h fast and after intravenous glucose. During a hyperinsulinaemic euglycaemic clamp (1 mU.kg-1.min-1), glucose utilization (measured using [6(3)H]glucose) was slightly lower (p = 0.07) in the peripheral than in the portal group. Hepatic glucose release was equal in all groups. Carbon dioxide incorporation into glucose (an estimate of gluconeogenesis) was higher in the portal than peripheral group in the fasted state but not during insulin infusion. Plasma concentrations and flux rates of fatty acids and amino acids did not differ between groups. We conclude that chronic systemic insulin delivery results in a) systemic but not portal hyperinsulinaemia, b) a minimal impairment in insulin-stimulated glucose uptake, without altering insulin-induced suppression of hepatic glucose release, and c) no effect on fatty acid or amino acid turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The effectiveness of two smoking cessation programmes for use in general practice: a randomised clinical trial.

OBJECTIVE: To evaluate a structured, behavioural change, smoking cessation intervention designed for use within general practice. DESIGN: Randomised controlled clinical trial. SETTING: General practices in Newcastle, Australia. PATIENTS: 311 Patients identified as smokers by a screening question were enrolled in the study. Of these, 101 were assigned to a structured behavioural change programme, 104 to a simple advice programme adapted from previous research, and 106 to a control group. No significant differences were found between groups for demographic and smoking related variables before the study. INTERVENTIONS: Patients in the simple advice group received a brief statement of advice from the general practitioner as well as three pamphlets; those in the structured intervention group were given strategies which included attitude and behavioural change programmes as well as techniques to aid compliance. The amount of smoking in all groups was assessed by self reports with validation by measurement of salivary cotinine concentrations. MAIN OUTCOME MEASURE: Significant increase in cessation rates. CONCLUSIONS: Significant differences between controls and the structured behavioural change group were found at the one month follow up, but only for self reported abstinence. The simple advice programme did not produce any significant differences over the control group. General practitioner evaluation of the structured programme highlighted difficulties in relation to the duration of the intervention. Overall the structured programme in its present form did not appear to be an effective programme for use within general practice.

Adolescent↗
PubMed1990

Recognition and recall of odours: the effects of suppressing visual and verbal encoding processes.

This study examines the effects on olfactory recognition and recall of the suppression of visual and verbal encoding processes. Subjects were allocated to one of four experimental conditions (no suppression, visual suppression, verbal suppression, and visual-plus-verbal suppression), presented with 15 target odours, and then tested for free recall or recognition of these odours, both within 10 minutes of presentation and one week later. Recall and recognition performance both showed a significant overall effect for level of suppression, with the 'no-suppression' group performing best in each case. Recognition performance also showed a significant overall effect for time of testing. Methodological problems, and strategies for overcoming them, are discussed.

Adolescent↗
PubMed1985

Smoking and myocardial infarction: secondary prevention.

This prospective study examines the question 'Is it too late to stop smoking cigarettes once you have had a myocardial infarction?' One hundred and nineteen cigarette smokers (90 men, 29 women) who survived their first myocardial infarction for one month were followed for five years or until their death if earlier. The age corrected mortality rate of men who continued to smoke cigarettes was 2.2 times the age corrected mortality rate of those who stopped smoking after their infarct. The women who continued to smoke had 2.4 times the age corrected mortality of those who stopped smoking. The age and sex corrected mortality rates for the combined group of men and women show that those who stopped smoking after their infarction have 55% of the mortality of those who continued to smoke (P less than 0.05). These results suggest that smoking is not merely a 'risk factor' for myocardial infarction but is also a causal factor whose effects can be avoided by both men and women after an initial myocardial infarction.

Adult↗
PubMed1984

Exocrine pancreatic function in diabetes mellitus.

An investigation of serum immunoreactive trypsin concentration and pancreatic isoamylase activity in patients with diabetes mellitus has shown that exocrine pancreatic deficit is maximal in insulin dependent diabetics, intermediate in those controlled with sulphonylureas, and absent in patients controlled with biguanides or diet or both. A significant correlation between the serum concentrations of both these pancreatic enzymes and C peptide was found. Serum pancreatic enzyme concentrations were not related to glycosylated haemoglobin concentrations, the dosage of insulin, or the age of onset of diabetes. The concentration of immunoreactive trypsin was found to be low in most of the insulin dependent diabetics in whom this enzyme was measured at the time of the clinical onset of diabetes. Thus exocrine pancreatic deficit in diabetes closely parallels the endocrine beta cell deficit and occurs concurrently with, or antedates, the clinical presentation of type I diabetes. It is therefore possible that in type I diabetes similar mechanisms are entailed in the pathogenesis of impaired endocrine and exocrine pancreatic function.

Biguanides↗
PubMed1983

Renal dysfunction in cadmium smelters: relation to in-vivo liver and kidney cadmium concentrations.

Biochemical indicators of renal dysfunction have been compared with liver and kidney cadmium levels measured by neutron activation analysis in a group of 37 cadmium smelters. Higher than normal concentrations of cadmium in the liver reflect past exposure; they were associated with evidence of renal dysfunction in workers exposed to cadmium for more than 10 years. A small group of 6 workers exposed to cadmium for only a short time (mean = 4.6 years) had high hepatic cadmium concentrations but normal renal function. Longitudinal studies are required to establish the natural history of renal dysfunction following cadmium accumulation in industrial workers.

Cadmium↗
PubMed1983

Characteristics of a calcitonin-responsive cell line derived from a human osteosarcoma.

Although the primary cell type in human osteosarcoma is usually a neoplastic osteoblast, numerous other mesenchymal cell types may coexist in the same tumor. Previously described cloned, long-term osteosarcoma cell lines have had an osteoblastic phenotype. In this report, we describe a nonosteoblastic, long-term cell line derived from an osteosarcoma in a patient with Paget's disease. The cell line (FM-2) is nontransformed in having a low saturation density and anchorage-dependent growth, and it is nontumorigenic in nude mice. Important features of its fine structure include numerous elongated mitochondria, abundant Golgi and lysosomes, and a poorly developed rough endoplasmic reticulum. The line has high levels of lysosomal enzymes (acid phosphatase and N-acetylglucosaminidase) and low levels of alkaline phosphatase. It lacks numerous macrophage markers (lysozyme, C3, Fc receptors, and M1 antigen). The FM-2 line had a dose-dependent cyclic AMP response (7-fold increase) following treatment with calcitonin but not with parathormone. In 125I-calcitonin-binding experiments, we calculated approximately 5.3 +/- 0.2 X 10(3) receptor sites/cell with a kd of 1.8 +/- 0.1 X 10(-9) M. Conditioned medium from the FM-2 line was a potent stimulator of calcium release as assayed in a 45Ca-labeled fetal rat bone organ culture. This activity was not prostaglandin, vitamin D, parathormone, or epidermal growth factor, which are known stimulators of bone resorption. The FM-2 line does not appear to be derived from an osteoblast, macrophage, or fibroblast and may represent a calcitonin-responsive bone stem cell.

Animals↗