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Biomedical subjects

B Friedman

Publications and source records attributed to B Friedman.

At least 145 records · Page 8Linked to original sources
PubMed1985

Hospital expenses in a sector model.

This review summarizes the capabilities and contributions of quantitative sector models for understanding trends in hospital expenses and the effects thereon of various public policies. After some brief historical notes on the use of analogous models in other policy areas, the general classes of national, partial, and narrow health sector models are introduced with special attention to method of validation and behavioral structure. Fourteen published models, described and critically reviewed with regard to these criteria, are assessed for their individual application to important policy and behavioral issues. Suggestions are offered for improvements and new initiatives in the use of sector models both in forecasting and in the study of procompetitive policies and reimbursement rule changes.

Economic Competition↗
PubMed1985

Injured neurons in the olfactory bulb of the adult rat grow axons along grafts of peripheral nerve.

Certain neurons in the central nervous system (CNS) of adult mammals extend axons for several cm along peripheral nerve grafts inserted into the brain or spinal cord. It is not clear, however, if these nerve cells constitute a special population or are examples of a general capacity of the injured mammalian CNS to regrow processes under these experimental conditions. Furthermore, because the new axons could originate by collateral sprouting from uninjured neurons, it is important to prove that the interruption of a central axonal projection can be followed by extensive fiber regrowth from the damaged neurons. In this anatomical study, we examined whether: (1) nerve cell type; and (2) axotomy, influence CNS axon regrowth along peripheral nerve grafts. For this purpose, we grafted segments of sciatic nerve into the olfactory bulb (OB) of adult rats and used combinations of neuroanatomical tracers (horseradish peroxidase and the fluorescent dyes True Blue and Nuclear Yellow) to investigate axonal regrowth from the different neurons that normally populate the OB. We demonstrate that OB axons extending along peripheral nerve grafts originate from mitral and tufted cells near the graft tip, rather than from the smaller OB neurons (periglomerular, short axon, and granule cells). Most of the mitral and tufted cells that extend new axons in grafted peripheral nerve segments lose their normal projections through the lateral olfactory tract because of axotomy at the time of grafting. Neuronal type, damage, and proximity to the graft appear to be prerequisites of this regenerative response from the OB.

Animals↗
PubMed1984

Diacylglycerol modulates binding and phosphorylation of the epidermal growth factor receptor.

Tumor promoters cause a variety of effects in cultured cells, at least some of which are thought to result from activation of the Ca2+-phospholipid-stimulated protein kinase C. One action of tumor promoters is the modulation of the binding and phosphorylation of the epidermal growth factor (EGF) receptor in A431 cells. To determine if these compounds act on the EGF receptor by substituting for the endogenous activator of C kinase, diacylglycerol, we compared the effects of the potent tumor promoter 12-O-tetradecanoyl phorbol 13-acetate (TPA) with those of the synthetic diacylglycerol analog 1-oleyl 2-acetyl diglycerol (OADG). When A431 cells were treated with TPA, the subcellular distribution of C kinase activity shifted from a predominantly cytosolic location to a membrane-associated state; OADG also caused the disappearance of cytosolic C kinase activity. The shift in the subcellular distribution of C kinase, caused by TPA or OADG, correlated with changes in binding and phosphorylation of the EGF receptor. OADG, like TPA, caused loss of binding to an apparent high affinity class of receptors, blocked EGF-induced tyrosine phosphorylation of the EGF receptor, and stimulated phosphorylation of the EGF receptor at both serine and threonine residues. No difference between the phosphopeptide maps of receptors from cells treated with OADG or TPA was observed. Thus, it appears that tumor promoters can exert their effects on the EGF receptors by substituting for diacylglycerol, presumably by activating protein kinase C. Further, these results suggest that endogenously produced diacylglycerol may have a role in normal growth regulatory pathways.

Amino Acids↗
PubMed1984

Fiber systems in the olfactory bulb and cortex: a study in adult and developing rats, using the timm method with the light and electron microscope.

The structure of the olfactory bulb and cortex of rats is described using the Timm method, in which endogenous transition or "heavy" metals are precipitated with sulfide and then stained with silver. With the light microscope, two types of staining, a fine, "colored" reaction and a coarse, "granular" reaction, are found in the neuropil of the adult forebrain; neuronal somata, fiber tracts, and some specific areas of the neuropil are almost unstained. With the electron microscope the Timm method consists of small silver granules, which are associated with axon terminals. These granules are located over the external surface of the presynaptic membrane, facing the synaptic cleft, and over synaptic vesicles, especially the internal surface of the vesicle membrane. This localization suggests that the reactive metals are related to a membrane component which is recycled during secretion of synaptic transmitters. The colored and granular reactions seen with the light microscope appear to be correlated with different intensities of staining of different types of axon terminals. The full extent of the olfactory cortex can be delineated by a bilaminar staining pattern in layer I, which coincides with the pattern of termination of fiber systems to the cortex demonstrated by axonal tracing experiments. The superficial part of layer I is very palely stained; this corresponds precisely to layer Ia, the zone of termination of fibers from the olfactory bulb. In contrast, the deep part of the layer is stained with an intense colored reaction; this corresponds precisely to layer Ib, the zone of termination of the major association fiber system within the olfactory cortex. A prominent granular reaction, which does not correspond to any known long axon system, is found in all layers of the cortex, although it is concentrated at the superficial edge of layer Ib and in layer II. Variations in staining in the several subdivisions of the olfactory cortex are illustrated and described. In the olfactory bulb, the most prominent staining is a relatively fine, granular reaction in the glomerular formations, which apparently corresponds to the olfactory nerve terminals. In immature rats, the Timm method stains the neuropil throughout the olfactory system, although the patterns and quality of staining differ from that found in adults. Before birth, the best-differentiated reaction is seen in glomeruli of the olfactory bulb and correlates well with the pattern of olfactory nerve ingrowth.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1984

Tumor promoters block tyrosine-specific phosphorylation of the epidermal growth factor receptor.

Tyrosine-specific phosphorylation of the epidermal growth factor (EGF) receptor in hormonally stimulated A431 cells is blocked by three chemically distinct classes of tumor promoters. Tumor-promoting esters of the diterpene phorbol (phorbol 12-myristate 13-acetate, beta-phorbol 12,13-dibutyrate, and beta-phorbol 12,13-didecanoate), indole alkaloids (teleocidin and lyngbyatoxin A), and polyacetates ( aplysiatoxin and debromoaplysiatoxin ) all inhibited EGF-stimulated phosphorylation of the receptor. Non-tumor-promoting analogs (beta-phorbol, alpha-phorbol 12,13-didecanoate, and hydrolyzed teleocidin) had no effect on the levels of receptor phosphorylation. The ED50 values of the inhibitory effect (0.1-3 ng/ml) reflected the relative tumor-promoting abilities of these compounds in vivo. None of the tumor promoters tested significantly decreased the overall specific binding of 125I-labeled EGF to A431 cells. Scatchard analysis, however, revealed two apparent EGF receptors in this cell type. The dose-responses for tumor-promoter inhibition of EGF receptor tyrosine phosphorylation and high-affinity EGF binding were similar, suggesting that the same initial event is responsible for both effects. This demonstrates a correlation between modulation of EGF receptor binding and phosphorylation of tyrosine by tumor promoters. The data suggest a possible role for protein kinase C, the putative cellular receptor for these tumor promoters, in the mechanism of action.

Amino Acids↗
PubMed1984

Effect of naloxone on ventilatory control in parents of victims of sudden infant death syndrome.

To determine whether the decreased responses to CO2, hypoxia, and flow resistive loads in parents of sudden infant death syndrome (SIDS) victims are due to an effect of endogenous opioids, we tested response to these stimuli in 10 parents (5 couples) of such children after injection of saline placebo and after injection of naloxone hydrochloride (3 mg). The responses after saline were comparable to those of our previous study, i.e., lower than normal. Ventilatory response to CO2 and hypoxia, as well as airway occlusion pressure responses to flow resistive loading, were not significantly different after naloxone compared with saline. We concluded that increased endogenous opioids do not play a significant role in these subjects' reduced ventilatory drive.

Adult↗
PubMed1983

United States experience with oxprenolol in hypertension.

Double-blind, randomized, parallel-group studies have confirmed that oxprenolol, either alone or in combination with a thiazide, is effective in reducing elevated blood pressure. In 2 of 3 comparisons with placebo, the blood pressure reduction was significantly more effective with oxprenolol; in 1 study, even though the placebo response was pronounced, oxprenolol was still more effective than placebo. In 2 studies propranolol reduced blood pressure by about 2 mm Hg more than oxprenolol. In the larger, longer-term study this difference was significant at the end of the dose-titration period, but there were no significant differences between the 2 treatment groups at study end. Moreover, oxprenolol reduced heart rate less and was associated with fewer side effects. Oxprenolol effectively lowered blood pressure when given once daily and was well tolerated, even in large doses. Blood pressure was reduced less with oxprenolol than with hydrochlorothiazide, -14/-11 versus -20/-13 mm Hg. The mean reduction with oxprenolol was less for black patients than for white. In a 1-year safety study, 86% of the patients continued to have a diastolic pressure of less than 90 mm Hg at study end.

Blood Pressure↗
PubMed1983

A double-blind study of oxprenolol once and twice daily in hypertensive patients.

In a randomized double-blind study of 175 patients with mild-to-moderate hypertension, oxprenolol hydrochloride (160-480 mg) given once daily was compared with the same drug given twice daily for efficacy, safety, and tolerability. Of these patients, 123 (58 receiving the once daily regimen and 65 receiving the twice daily regimen) were included in the analysis of efficacy. Both groups showed similar significant (p less than 0.01) reductions in mean blood pressure during the 6-week titration period and for the remainder of the trial. A comparison of mean standing diastolic blood pressure and supine systolic and diastolic blood presses showed no significant difference between groups during the fixed dosage period. The number of patients reporting adverse experiences was not significantly different for the two regimens. Plasma triglycerides increased in both groups, but there were no other laboratory abnormalities related to treatment. This study shows that oxprenolol given once daily is effective, safe, and well tolerated in the treatment of mild-to-moderate hypertension.

Adult↗
PubMed1983

A new approach to hospital cost functions and some issues in revenue regulation.

An important aspect of hospital revenue regulation at the State level is the use of retroactive allowances for changes in the volume of service. Arguments favoring non-proportional allowances have been based on statistical studies of marginal cost, together with concerns about fairness toward non-profit enterprises or concerns about various inflationary biases in hospital management. This article attempts to review and clarify the regulatory issues and choices, with the aid of new econometric work that explicitly allows for the effects of transitory as well as expected demand changes on hospital expense. The present analysis is also novel in treating length of stay as an endogenous variable in cost functions. We analyzed cost variation for a panel of over 800 hospitals that reported monthly to Hospital Administrative Services between 1973 and 1978. The central results are that marginal cost of unexpected admissions is about half of average cost, while marginal cost of forecasted admissions is about equal to average cost. We obtained relatively low estimates of the cost of an "empty bed." The study tends to support proportional volume allowances in revenue regulation programs, with perhaps a residual role for selective case review.

Costs and Cost Analysis↗
PubMed1982

A program for parents of children with sensory integrative dysfunction.

The pilot parent program described in this article is based on literature that suggested greater parental acceptance of a child would help the child make gains in self-esteem. Six parents of children with sensory integrative dysfunction were seen individually for 6 weeks in order to enhance the parents' understanding of their children's sensory integrative problems and to discuss ways to help build their child's self-esteem. Using the Porter Parental Acceptance Scale as a pre- and post-program measure, the results were not significant; however, the parents' subjective evaluations indicated that the program helped them to increase their understanding of their children's problems and improved their ability to relate constructively to their children.

Adult↗
PubMed1982

Economic aspects of the rationing of nursing home beds.

State governments, with federal subsidies under the Medicaid program, are the source of the largest share of expenditures to support patients in the long-term institutional nursing care. A major state policy tool that has been evolving is the authority to approve or deny expansions in bed capacity. This paper is an analysis of how the behavior of physicians and nursing homes operates, given present reimbursement policies, could determine the allocation of beds among patients. Both general evidence of inefficient allocation and the detailed experience in the State of Rhode Island before and after a period of rapid expansion of bed capacity lend support to the conceptual model of home-operator behavior. Some alternative structural reforms in Medicaid and in the rationing of beds are suggested in the final section.

Bed Occupancy↗