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Biomedical subjects

G Collins

Publications and source records attributed to G Collins.

At least 37 records · Page 2Linked to original sources
PubMed1995

Awareness detection during caesarean section under general anaesthesia using EEG spectrum analysis.

This study examined the relationship between the EEG (spectral edge frequency 90-SEF90) and the occurrence of awareness defined for the purpose of this study as responsiveness to verbal commands. Fifty women undergoing general anaesthesia for elective Caesarean section were examined. Responsiveness to verbal commands was detected every minute in the period from the induction of anaesthesia to the delivery of the newborn using the Tunstall isolated forearm technique and correlated with the SEF90 value. The patients were assigned by a randomized code to receive either thiopentone (4 mg.kg-1) or ketamine (1 mg.kg-1) for induction of anaesthesia. Before the administration of succinylcholine a tourniquet was applied to the free arm, and inflated to 200 mmHg, to maintain motor function to one arm. The EEG recordings started five minutes before induction and were recorded throughout anaesthesia. The incidence of responsiveness to verbal commands was lower in the ketamine group (24%) where the average SEF90 was 12.0 +/- 3 Hz, than in the thiopentone group (52%), where the average SEF90 was 18.09 +/- 3 Hz (P = 0.01). The results suggest that SEF values of < or = 8.6 Hz were sufficient to avoid responsiveness to verbal commands.

Adult↗
PubMed1995

The influence of patient positioning on the hemodynamic changes in TURP patients with severe coronary disease.

Hemodynamic changes were studied in 10 patients with severe coronary disease during routine transurethral prostatectomy (TURP) when performed in the lithotomy position with and without elevation of the legs. The patients undergoing the procedure in the lithotomy position with elevation of the legs exhibited significant hemodynamic changes as compared with those undergoing the procedure without elevation of the legs. This leads us to conclude that performing TURP in the lithotomy position without elevation of the legs benefited the patient by stabilizing hemodynamic factors.

Aged↗
PubMed1994

Phenotypic characterization of collagen gel embedded primary human breast epithelial cells in athymic nude mice.

We have developed a method to characterize the phenotypes and tumorigenicity of dissociated human breast epithelial cells. The dissociated cells were first embedded in collagen gels and subsequently transplanted subcutaneously in vivo in athymic nude mice. The transplantation of dissociated epithelial cells from reduction mammoplasties, presumed to be normal, always resulted in normal histomorphology. Epithelial cells were arranged as short tubular structures consisting of lumina surrounded by epithelial cells with an occasional more complex branching structure. These outgrowths were surrounded by intact basement membrane and were embedded in collagen gel that, at termination, contained collagenous stroma with fibroblasts and blood vessels. In contrast, transplantation of dissociated breast epithelial cells from breast cancer specimens resulted in outgrowths with an invasive pattern infiltrating the collagen gel as well as frank invasion into vascular space, nerves and muscles. These observations were made long before the subsequent palpable stage which resulted if left in the mouse for a long enough time. The dissociated human breast epithelial cells thus retained their intrinsic property to undergo morphogenesis to reflect their original phenotype when placed in a suitable environment, the collagen gel.

Adolescent↗
PubMed1994

Modification of rejection by polyethylene glycol in small bowel transplantation.

The use of polyethylene glycol (PEG) in preservation solutions has been associated with a decreased incidence of rejection in clinical and experimental organ transplantation. In this study, we examined the effect of PEG with different molecular configurations on rejection of small bowel allografts in the rat. Male ACI and LEW rats were used as donors and recipients, respectively. Orthotopic small bowel transplantation was performed using the following preservation solutions: lactated Ringer's solution (n = 7), University of Wisconsin solution (n = 7), University of Wisconsin solution without hydroxyethyl starch (sUW; n = 7), sUW with PEG20M (n = 9), sUW with PEG8000 (n = 6), and sUW with PEG20L (n = 7). No immunosuppression was given. In orthotopic small bowel transplantation, only groups with a high molecular weight PEG, PEG20M and PEG20L, demonstrated longer survival (P < 0.01 and P < 0.001, respectively) and delayed onset of unkempt appearance (P < 0.05 and P < 0.001, respectively). In heterotopic small bowel transplantation, sUW was compared with sUW with PEG20L. Rejection occurred later and its progression was slower in the sUW with PEG20L than in the sUW alone. Our observations suggest that the onset and progression of rejection after small bowel transplantation were influenced by the molecular weight and configuration of the PEG molecule. The mechanism is unclear, but high molecular weight PEG appears to reduce or change the immunogenicity of the small bowel allograft.

Animals↗
PubMed1993

Body weight change, all-cause mortality, and cause-specific mortality in the Multiple Risk Factor Intervention Trial.

OBJECTIVE: To evaluate the relation between weight variability and death in high-risk, middle-aged men participating in the Multiple Risk Factor Intervention Trial (MRFIT). DESIGN: Cohort study with 3.8 years of follow-up. SETTING: Multicenter, collaborative, primary prevention trial conducted at 22 clinical centers in the United States. PARTICIPANTS: Men (n = 10,529) who were 35 to 57 years old at baseline and who were in the upper 10% to 15% of risk for coronary heart disease because of smoking, high blood pressure, and elevated cholesterol level. Participants were seen at least annually for 6 to 7 years for medical evaluations in study clinical centers. MEASUREMENTS: Death from cardiovascular disease (228 deaths) and from all causes (380 deaths). RESULTS: The primary measure of weight variability was the intrapersonal standard deviation of weight (ISD), which was calculated from measured weights obtained at clinic visits during a 6- to 7-year period. All-cause death rates per 1000 person-years of follow-up across ISD quartiles were 8.28, 8.25, 10.57, and 11.07 from the first to fourth quartiles, respectively. After adjusting for baseline risk factors associated with weight change, the relative risk for all-cause mortality in the fourth compared with the first quartile was 1.64 (95% CI, 1.21 to 2.23). Cardiovascular death and ISD showed a similar pattern. The association between weight change and death was not observed in the heaviest men. CONCLUSION: Greater weight variability was associated with a greater risk for cardiovascular disease and all-cause mortality in some types of high-risk men.

Adult↗
PubMed1993

A model for implementing Healthy People 2000 objectives in African-American communities in California.

Using Healthy People 2000 as the source document, regional task forces were formed at the request of the Health Promotion Section of the California Department of Health Services to set health promotion objectives and recommendations for the state's ethnic populations. The topics chosen by regional African-American task forces were (1) violence and abusive behavior, (2) physical activity and fitness, (3) nutrition, (4) tobacco, (5) educational and community-based programs, (6) cancer, and (7) heart disease and stroke. Objectives were expanded, linked together, and revised to meet felt needs. The regional task forces presented the first draft of the document for review at the Multiethnic Health Promotion Conference held in Sacramento, California, June 11 through 13, 1991. The expanded task force, including conference participants, amended the recommendations and ranked the topic areas in order of priority. The group also responded to the challenge of developing implementation strategies for the recommendations. We discuss the early stages of dissemination and implementation of the agenda among California African-American communities. American Indian, Asian/Pacific Islander, and Latino Task Forces have prepared similar documents, and each document will be used to prepare the Multiethnic Health Promotion Agenda for California. We summarize the process by which the papers were developed and provide detailed analysis of the African-American process.

Black or African American↗
PubMed1992

Frequency of late potentials on signal-averaged electrocardiograms during thallium stress testing in coronary artery disease.

Late potentials detected by signal-averaged electrocardiography (SAECG) are an important noninvasive indicator identifying patients with previous myocardial infarction at risk for developing ventricular tachycardia. The role of myocardial ischemia in the development of late potentials is undefined. This study attempts to determine if late potentials on SAECG can be produced during scintigraphically proven ischemia. A signal-averaged electrocardiogram was obtained before and immediately after single-photon emission computed tomography thallium exercise testing in 51 patients. Reversible ischemia was documented in 25 cases with no significant changes in the parameters of SAECG; patients with previous myocardial infarction (n = 10) also had no significant changes from baseline. Multivariate analysis with respect to reversible ischemia and previous myocardial infarction was unrevealing. Patients with late potentials at baseline (n = 10) who developed reversible ischemia (n = 5) had a shorter QRS duration than those with late potentials at baseline and no reversible ischemia. The data indicate that exercise-induced scintigraphically proven ischemia does not alter SAECG even in the presence of previous myocardial infarction. Patients with late potentials at baseline may actually have a shortened QRS duration during reversible ischemia as opposed to the expected lengthening of the QRS.

Coronary Disease↗
PubMed1992

Antigen binding properties of highly purified bispecific antibodies.

A panel of three bispecific monoclonal antibodies (bsMAbs) binding to follitropin (FSH) and to beta-galactosidase have been prepared by fusion of hybridoma cell lines resistant to oubain and neomycin. One of these bispecific antibodies contains heavy chains of the same IgG subclass, and two are composed of heavy chains of different IgG subclasses. We have investigated methods for the purification of bispecific antibodies from hybrid hybridoma supernatant fluids grown in serum-free medium. Following ammonium sulfate precipitation, bispecific antibodies can be purified in a single step by mixed mode ion-exchange HPLC on Bakerbond Abx columns. In one case, three species were resolved by ion-exchange HPLC and functional analysis showed that two peaks contained parental antibodies, and the third contained the bispecific. Ion-exchange HPLC purification of serum-free preparations from two other hybrid hybridomas resolved seven protein-containing peaks, only one of which was active in a bispecific ELISA. The equilibrium affinity constants for each of the parental antibodies for both FSH and beta-galactosidase were determined and found to be similar to those of the purified bsMAbs. Further, the association of FSH to one binding site on a bispecific antibody was shown to have no effect on the equilibrium binding constant for beta-galactosidase binding to the other site. Our results suggest that bsMAbs can be readily purified from hybrid hybridomas by a simple and rapid method, and the binding of antigen to one binding site on a bsMAb is independent of antigen binding to the second site.

Animals↗
PubMed1992

Streptozotocin-induced diabetes and the effects of endurance exercise training.

The purpose of this investigation was to determine if endurance exercise training would alter the degenerative effects of streptozotocin diabetes on cardiac function and alter the responses of streptozotocin diabetic rats to induced myocardial ischemia. Diabetic rats experienced a significant (p < 0.05) reduction in cardiac function as evidenced by left ventricular peak systolic pressure (LVPSP), maximal time rate of change of pressure (+dP/dTmax), rate pressure product (RPP), and heart rate (HR). Exercise training apparently reduced the effect of diabetes since the function of non-ischemic hearts from trained diabetic rats was not different from that of non-diabetic rats. It also was not different from the sedentary diabetic rat hearts. Training did not alter the response of the hearts of either group of diabetic rats to induced myocardial ischemia.

Analysis of Variance↗
PubMed1990

Fetal echocardiography in Manitoba: a regional perspective.

In order to investigate the impact of detailed fetal echocardiography on perinatal care at a tertiary health care centre, the records of all 29 cases referred for fetal echocardiography during the years 1987-88 were reviewed. All patients had risk factors for offspring with congenital heart disease. A family history of congenital heart disease led to fetal echocardiography in about two-thirds of the cases, while the remainder were referred on the basis of abnormal cardiac screening examinations during fetal assessment. Forty examinations were performed on patients at gestational ages of 16 to 37 weeks. Detailed fetal echocardiography did not alter the perceived severity of major structural cardiac defects previously identified by an experienced fetal assessment unit and did not change or influence intrapartum care. The value of fetal echocardiography in the diagnosis and treatment of fetal tachyarrhythmias was confirmed. Also, fetal echocardiography provided reassurance of cardiac normality in cases with familial and maternal risk factors for congenital heart disease. Fetal echocardiography appears to be an inappropriate screening tool in view of its limited availability and focus. Comprehensive fetal assessment with four chamber cardiac imaging is the appropriate first-line screening test for patients with risk factors for offspring with congenital heart disease.

Echocardiography↗
PubMed1989

A simplified method for calculating complex metabolic sensitivities by using matrix partitioning.

The matrix method for calculating the overall sensitivities (including control coefficients) of a metabolic system, described by Crabtree & Newsholme [Biochem. J. 247, 113-129 (1987)], is simplified by a preliminary partitioning of the initial matrix equation. This reduces the size of the matrix to be inverted and thereby removes a major drawback with the original method. The resulting procedure is simpler and more systematic than the alternative methods currently available, especially when the system is extensively branched.

Mathematics↗
PubMed1989

Relationship between carotenoids and cancer. The Multiple Risk Factor Intervention Trial (MRFIT) Study.

We evaluated the baseline serum levels of beta carotene, total carotenoids, vitamin A and E, and retinol-binding protein among 156 initially healthy men who participated in the Multiple Risk Factor Intervention Trial (MRFIT) and who subsequently died of cancer and 311 controls individually matched for age, smoking status, randomization group, date of randomization, and clinical center. Both total carotenoids and beta carotene levels were lower in the 66 lung cancer cases than in their matched controls. For all cancer deaths combined, there were no significant differences in total carotenoids or beta carotene between cases and controls. The relationship between lower serum carotenoid levels and lung cancer persisted after adjusting for the number of cigarettes, alcohol intake, serum thiocyanate levels, and cholesterol levels in the blood. Serum levels of retinol, alpha tocopherol, and retinol-binding protein were not related to any cancer site. The results of this study provide further evidence for a possible protective effect of beta carotene against lung cancer among cigarette smokers.

Adult↗