Search PubMed⌕ Search

Biomedical subjects

L Kessler

Publications and source records attributed to L Kessler.

At least 73 records · Page 4Linked to original sources
PubMed1991

In vitro and in vivo studies of the properties of an artificial membrane for pancreatic islet encapsulation.

Encapsulation of pancreatic islets with an artificial membrane has been proposed as a means of immunoprotection after transplantation. Such a membrane should be biocompatible, nondegradable, and should allow the passage of insulin and glucose while preventing that of antibodies and lymphocytes. Thus, we have studied in vitro and in vivo, the characteristics of an acrylonitrile membrane (AN69, HOSPAL, Sweden) for islet encapsulation. The AN69 membrane composed of a fiber network with a porous structure, allowed a satisfactory passage of glucose (75% of the initial amount within one hour) but not of insulin (only 7%). The morphological state of rat islets cultured on membranes under both conditions for 2 weeks was similar to that of islets cultured on dishes; in addition rat fibroblasts retracted after a 3-day culture. Finally, the membrane was unaltered after a 12 month implantation in the peritoneal cavity of rats. When the surface properties of the AN69 membrane were changed by adsorption of a hydrophilic copolymer or by protein coating, the permeability of the membrane was modified. Glucose and insulin diffusion were significantly decreased after protein-coating, whereas glucose diffusion was preserved and that of insulin doubled after adsorption of a copolymer onto the membrane. In addition, after a 12-month implantation in the rat, the membrane surface treated by the copolymer was altered leading to the adhesion of macrophages. In conclusion, the AN69 acrylonitrile membrane may be useful for pancreatic islet encapsulation; its insulin permeability should be increased by a surface treatment aimed at increasing its hydrophilic properties. However the stability of this treatment seems to be an important factor in preserving the biocompatibility of the membrane.

Acrylonitrile↗
PubMed1990

Rise in prostatic cancer incidence associated with increased use of transurethral resection.

We examined the association between prostatic cancer incidence rates and the rates of transurethral prostatectomy to explore reasons for the nationally reported dramatic increases in incidence rates of prostatic cancer from 1973 through 1986. There was a strong correlation between both incidence of all stages of prostatic cancer combined and of localized disease and the increasing use of transurethral resection, a common surgical procedure usually performed to relieve urinary obstruction due to benign enlargement of the prostate. Our analyses suggest that increased detection of existing tumors via transurethral resection was the primary reason for the observed increase in incidence rates of prostatic cancer. However, analyses of mortality trends, particularly among nonwhites, and laboratory studies of the histologic nature of clinically asymptomatic tumors suggest that part of the increase may reflect changes in the real risk of prostatic cancer.

Age Factors↗
PubMed1990

Analysis of the costs of a large prevention trial.

Total direct costs of the Women's Health Trial (WHT), a large multicenter prevention trial, were reduced by more than 50% by means of research cost analysis conducted during the trial design phase. The unit costs of specific trial activities were estimated so that total direct costs of the trial could be predicted from design parameters. The relative costs of screening, treatment, and follow-up, and the fixed costs associated with each clinical center in a multicenter prevention trial were taken into account. Direct costs of the WHT were reduced from +195 million to +95 million by refinement of the trial protocol, selection of an efficient design, and consideration of trial logistics. The analyses suggest several ways to reduce costs in a prevention trial. Use of the case-cohort approach can reduce costs substantially when the protocol includes collection of specimens or data that are costly to process. When establishing and maintaining a clinical center represents a significant proportion of a clinical center's costs, use of a smaller number of larger clinical centers offers important cost savings. Because restrictive eligibility requirements reduce the recruitment potential of each clinical center, use of high-risk participants may not improve the efficiency of a prevention trial; its favorable impact on sample size may fail to compensate for its cost in terms of additional clinical centers and higher recruitment costs.

Aged↗
PubMed1989

A dietary and risk factor questionnaire and analysis system for personal computers.

The authors report the adaptation of a dietary and risk factor questionnaire and analysis system for use with IBM (or compatible) personal computers. This system includes a flexible computer-assisted interview program which may be modified to suit investigator needs while preserving a standard output format. It also includes a nutrient analysis program for calculation of usual dietary intake. Each of these two major components has its own set of utilities and options, so that investigators may tailor the system to particular research areas. The nature and capabilities of the two main programs are described, as well as the development of the underlying system and the general flow of data in the system.

Data Collection↗
PubMed1988

The elderly population. Opportunities for cancer prevention and detection.

Interest in the elderly population, persons 65 years of age or older, as a target group for cancer control has not been great. Age recommendations rarely are made for prevention and early detection of cancer for elderly persons. However, cancer incidence and mortality rates are known to rise rapidly with increasing age. This paper takes a long-term public-health perspective to look toward the year 2030 to discuss the challenges of organizing and implementing prevention and early detection incentives for our nation's current and future elderly population. Cancer prevalence estimates in the context of the geriatric imperative of the 21st century are provided for three cancers--breast, prostate, and lung and bronchus. The sheer magnitude of numbers created by the aged population expansion can greatly increase the number of cancer survivors and newly diagnosed cases. Current efforts in cancer prevention and early detection should anticipate the health-care demands of the elderly in the first three decades of the next century.

Adult↗
PubMed1987

Dietary fiber intake in the US population.

Twenty-four hour recall data from adults interviewed in the Second National Health and Nutrition Examination Survey, NHANES II, were used as the basis to estimate total dietary fiber intake in the United States. Food fiber values were calculated for the 2500 foods in NHANES II in two ways: 1) using fiber values compiled from the literature by NCI and 2) values based on the Southgate methodology. Mean dietary fiber intake in the US adult population (greater than 19 y of age) is 11.1 g/d using the first set of values and 13.3 g/d according to Southgate values. On a per 1000 kcal basis, women consume more dietary fiber (6.5 g/1000 kcal) than men (5.5 g/1000 kcal) at every age. Fiber intake by geographic region, age, race, and sex is discussed. Our study indicates that dietary fiber intake in the United States is considerably lower than that previously reported.

Adult↗
PubMed1986

The prevalence of cancer. Estimates based on the Connecticut Tumor Registry.

Cancer incidence and mortality do not fully reflect the effect of cancer. To estimate the number of persons alive who have a history of cancer, we derived prevalence rates based on data from the Connecticut Tumor Registry. We did not attempt to distinguish between people who had been cured of cancer and those who still had the disease. In 1982 the age-adjusted prevalence rates of cancer among males and females were 1,789 and 2,222, respectively, per 100,000. Age-specific prevalence rates were highest among the elderly; 12 percent of men and 11 percent of women over 70 had previously been given a diagnosis of cancer. Breast cancer in females and prostate cancer in males were the two most prevalent malignant diseases. We estimate that about 5 million persons alive in the United States today have at one time received a diagnosis of cancer.

Adult↗
PubMed1985

The 'offset effect' of mental health treatment on ambulatory medical care utilization and charges. Month-by-month and grouped-month analyses of a five-year study.

The five-year ambulatory medical care experience of 400 patients with mental disorders was studied to test the "offset" hypothesis that patients receiving timely mental health specialist treatment have lower subsequent utilization of, and charges for, care than patients not receiving such specialist treatment. Specialist treatment was associated with significant offset savings in utilization and charges for the non-psychiatric medical care of treated patients with either severe or less severe mental disorders. However, the visits and charges for such specialist treatment boosted the overall (nonpsychiatric plus mental health specialist) care utilization and charges of the specialist-treated patients above those of patients treated solely by their nonpsychiatric physicians; this overall increase was especially pronounced for patients with severe mental disorders. The findings suggest the need for randomized prospective offset studies comparing utilization, cost, and clinical outcomes.

Ambulatory Care↗
PubMed1984

Separate mechanisms for behavioral, cardiovascular, and hormonal responses to dextroamphetamine in man.

The neurochemical specificity of physiological, biochemical, and psychological responses to dextroamphetamine was tested by pretreating volunteers with haloperidol (0.014 mg/kg IM), propranolol (0.1 mg/kg IV), thymoxamine (0.1 mg/kg IV), or placebo prior to 0.3 mg/kg IV amphetamine. Healthy volunteers (N = 12) participated in the studies, but not all volunteers received each drug combination. Haloperidol prevented dextroamphetamine-induced behavioral excitation, but did not significantly affect plasma norepinephrine or pressor responses, whereas propranolol inhibited norepinephrine and pressor responses without influencing excitation or other behavioral responses. Thymoxamine did not affect any of the responses measured. None of the agents significantly affected plasma cortisol or growth hormone responses. The prolactin rise following dextroamphetamine was potentiated by haloperidol. The results are consistent with the hypothesis that behavioral excitation after dextroamphetamine occurs through a dopaminergic mechanism, and pressor responses through a noradrenergic mechanism.

Adult↗
PubMed1984

[Genetically determined hearing defects in childhood].

20-60% of all hearing disturbances are of genetic origin (own investigations: 30%). The genetically determined hearing disorders are mainly monogen (in most cases autosomal recessive). The detection of heterozygous carriers with normal hearing is very important for optimal genetic counselling. We tried to develop an audiological test for detecting the heterozygous status in autosomal recessive deafness.

Child↗