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Biomedical subjects

L Levitt

Publications and source records attributed to L Levitt.

54 records · Page 3Linked to original sources
PubMedDate not supplied

[Molecular mechanisms of cellular interaction in immune regulation of hematopoiesis].

Studies are reviewed, which establish a novel regulatory role for the T cell lymphokine IL2: Immunoregulation of hematopoiesis. IL2 induces a receptor-specific inhibition of early erythroid progenitors. IL2-induced inhibition of erythropoiesis is mediated by Interferon-gamma protein release preceded by Interferon-gamma mRNA accumulation. Triggering of the antigen receptor complex induces p55 IL2 receptor expression, which is a prerequisite for IL2-induced erythropoietic inhibition. P55 protein expression on the T cell surface is preceded by an increase of p55 mRNA levels. The studies demonstrate that the regulatory role of IL2 extends beyond governance of the immune system itself and can subserve to control red cell production in vitro.

Animals↗
PubMedDate not supplied

A developmental model for free vascularized bone transfers in the dog.

An autogenous free vascular bone transfer using a segment of ulna along with its periosteum and vascular pedicle was developed. The vascular pedicle, based on the common interosseous artery and vein, emerged where muscular branches from the cranial interosseous artery enter the extensor carpi ulnaris and lateral digital extensor muscles. Four autogenous heterotopic (ulna to tibia) vascular transfers by microvascular anastomosis and two avascular transfers were performed to compare the osteogenic potential and viability of free revascularized grafts with avascular bone grafts. Successful microvascular anastomosis was demonstrated in three of the four vascular transfers by early bone scanning using technetium-labeled polyphosphate. Radiographically, there was more periosteal new bone and callus formation in the successfully revascularized bone transfers than in the failed vascular transfer and the avascular controls. Histologically, viable bone with an intact medullary and periosteal vascular supply was recognized in the grafts successfully revascularized by microvascular anastomosis.

Animals↗
PubMedDate not supplied

Stroke in the Lehigh Valley: seasonal variation in incidence rates.

We investigated the seasonal pattern of stroke using the Lehigh Valley Stroke Register. This register includes all patients hospitalized with stroke or transient ischemic attack (TIA) from among the 600,000 Lehigh Valley residents. Meterological data were obtained from the National Oceanic and Atmospheric Administration. The study, which uses 18 months of data, included 1,944 cases. Using single harmonic regression analysis, the seasonal pattern of TIA and infarction, but not hemorrhage, fit a sine-cosine wavefunction with a 12-month period (R2 = 41% and 36%, respectively). For infarction, the strongest seasonal pattern was exhibited for women of all ages and for both sexes in the age groups 65-74 and 75-84, but only the sine component was significant. The peak months for TIA were June-August, while the peak months for infarcts were February-April. Correlations between ambient temperature and each type of stroke were computed. A significant positive correlation for TIA was found (r = 0.57, p = 0.01). After adjusting for a 2-month lag between the low for infarction and the peak for temperature, a significant negative correlation was found (r = -0.64, p = 0.01). No significant correlation was found for hemorrhage. Possible reasons for the opposite relations of TIA and infarct are discussed.

Age Factors↗
PubMedDate not supplied

Acute stroke, hematocrit, and blood pressure.

A population-based study of the relation between hematocrit and stroke subtype was carried out among 2,077 individuals using the Lehigh Valley Stroke Register. This register identifies all stroke patients admitted to the 8 acute care hospitals serving the Lehigh Valley area of eastern Pennsylvania-western New Jersey. The mean hematocrit was higher in patients with lacunes than with thrombotic or embolic strokes (p = 0.02). However, when blood pressure was also considered the increase in hematocrit in patients with lacunar stroke was significant only when systolic hypertension (greater than or equal to 150 mm Hg) was also present (p = 0.029); no significant difference in hematocrit was found between stroke subtypes in normotensive individuals. Therefore, we cannot exclude the possibility that hypertension interacts with hematocrit in accounting for the observed association with lacunar infarcts. There was no trend for increased in-hospital mortality for stroke patients in either the low (less than or equal to 30, 30-36%) or high (greater than or equal to 47%) hematocrit groups.

Acute Disease↗
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Understanding the managed care backlash.

This paper examines the depth and breadth of the public backlash against managed care and the reasons for it. We conclude that the backlash is real and influenced by at least two principal factors: (1) A significant proportion of Americans report problems with managed care plans; and (2) the public perceives threatening and dramatic events in managed care that have been experienced by just a few. In addition, public concern is driven by fear that regardless of how well their plans perform today, care might not be available or paid for when they are very sick.

Adult↗
PubMedDate not supplied

Does dissatisfaction with health plans stem from having no choices?

Data from a 1997 nationwide telephone survey are used to assess the relationship between choice and public opinion about managed care. We found that only a minority of the working-age population effectively control what health plan they get. Persons without choice were markedly more dissatisfied with their health plan, especially when enrolled in managed care. In multivariate analysis, how respondents rated their health plan depended as much on whether they lacked choice as on whether they were enrolled in managed care. Persons without choice also had more negative opinions about managed care in general. The results suggest that the managed care "backlash" may persist so long as consumers have little control over health insurance decisions.

Adult↗
PubMedDate not supplied

Tax subsidies for health insurance: costs and benefits.

The continued rise in the uninsured population has lead to considerable interest in tax-based policies to raise the level of insurance coverage. Using a detailed microsimulation model for evaluating these policies, we find that while tax subsidies could significantly increase insurance coverage, even very generous tax policies could not cover more than a sizable minority of the uninsured population. For example, a generous refundable credit that costs $13 billion per year would reduce the ranks of the uninsured by only four million persons. We also find that the efficiency of tax policies, in terms of the cost per newly insured, inevitably would fall as more of the uninsured were covered.

Cost-Benefit Analysis↗
PubMedDate not supplied

Job-based health insurance in 2001: inflation hits double digits, managed care retreats.

Drawing on the results of a national survey of 1,907 firms with three or more workers, this paper reports on several facets of job-based health insurance, including the cost to employers and workers; plan offerings and enrollments; patient cost sharing and benefits; eligibility, coverage, and take-up rates; and results from questions about employers' knowledge of market trends and health policy initiatives. Premiums increased 11 percent from spring 2000 to spring 2001, and the percentage of Americans in health maintenance organizations (HMOs) fell six percentage points to its lowest level since 1993, while preferred provider organization (PPO) enrollment rose to 48 percent. Despite premium increases, the percentage of firms offering coverage remained statistically unchanged, and a relatively strong labor market has continued to shield workers from the higher cost of coverage.

Cost Sharing↗
PubMedDate not supplied

Court-ordered foster family care reform: a case study.

The authors examine the implications of G. L. v. Zumwalt, a case that resulted in a far-reaching consent decree that mandates specific reforms in policy and practice to be implemented by a public social welfare agency in its delivery of services to foster children and their families.

Adolescent↗