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Biomedical subjects

S Haber

Publications and source records attributed to S Haber.

At least 19 recordsLinked to original sources
PubMed1989

Use of nonphysician providers in the Medicare program: assessment of The Direct Reimbursement of Clinical Social Workers Demonstration Project.

Rising Medicare costs and concern about inadequate access to physician services have prompted interest in extending independent practitioner status to nonphysician providers. This paper reviews the findings from a demonstration project that tested whether recognizing clinical social workers (CSWs) as independent practitioners in the Medicare program would be a cost-effective method to improve access to needed mental health services. The demonstration showed little impact on access and no clear evidence of savings, despite the lower cost of CSW services compared with those of psychiatrists. Differences between CSWs and psychiatrists in treatment patterns and treatment settings, however, suggested that for some patients CSWs might be an appropriate alternative source of care.

Aged↗
PubMed1988

Tracing intrinsic fiber connections in postmortem human brain with WGA-HRP.

Modern methods for tracing central nervous system pathways depend largely on active axonal transport mechanisms and are carried out in in vivo animal experiments. This report describes the ability to trace axons and label cell bodies in postmortem human material, using injections of wheat germ agglutinin horseradish peroxidase. Furthermore, it demonstrates the compatibility of this method with immunocytochemical techniques for localizing neurotransmitters. Thus it is possible to study the intrinsic circuitry or short connections in brain regions such as cortex in both normal and pathological material, and, using double label methods, determine the transmitter systems involved. It also raises the issue of the mechanisms which are involved in the movement of the tracer molecule.

Axonal Transport↗
PubMed1987

Anatomical relationship between the basal ganglia and the basal nucleus of Meynert in human and monkey forebrain.

Previous immunohistochemical studies have provided evidence that the external segment of the globus pallidus extends ventrally beneath the transverse limb of the anterior commissure into the area of the substantia innominata. Enkephalin-positive staining in the form of "woolly fibers" has been used as a marker for the globus pallidus and its ventral extension. Acetylcholinesterase staining of both fibers and cell bodies, frequently used as a marker for the basal nucleus of Meynert, is also found in the area of the substantia innominata. This study describes the differential distribution of enkephalin-positive woolly fibers and acetylcholinesterase staining on adjacent sections in both the monkey and human basal forebrain area in an attempt to define the relationship between the basal ganglia and the basal nucleus of Meynert. The results show that while both occupy large regions of the basal forebrain, they overlap very little. In both species investigated, dense concentrations of acetylcholinesterase-positive neurons lie, for the most part, outside the boundaries of the pallidal fibers. However, some scattered acetylcholinesterase cells do lie within the confines of the dorsal pallidum, and a more prominent group is found in the subcommissural ventral pallidum. These cells may constitute a group separate from the more densely packed acetylcholinesterase-positive cells in woolly fiber-free regions in that they may receive direct striatal input.

Acetylcholinesterase↗
PubMed1986

Fetal neuronal grafts in monkeys given methylphenyltetrahydropyridine.

Fetal substantia nigra cells of two different gestational ages were successfully transplanted into the brains of three methylphenyltetrahydropyridine-treated monkeys with severe parkinsonian motor and behavioural deficits. Functional improvement continued for 10 weeks after cell grafts into the striata of two monkeys with substantial numbers of tyrosine-hydroxylase-positive fetal neurons at necropsy. Behavioural improvement was correlated with increases in cerebrospinal fluid (CSF) homovanillic acid (HVA) concentrations after the transplants. A control monkey with inappropriately placed transplanted cells of an earlier gestational age remained severely parkinsonian and died during a similar period. CSF HVA fell slightly in this monkey from the low level seen before the transplants. Fetal dopamine neurons of two different gestational ages appear to survive transplantation in primates and have biochemical and functional effects.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1985

Antigen presentation by hapten-specific B lymphocytes. II. Specificity and properties of antigen-presenting B lymphocytes, and function of immunoglobulin receptors.

The studies described in this paper were designed to examine the ability of hapten-binding murine B lymphocytes to present hapten-protein conjugates to protein antigen-specific, Ia-restricted T cell hybridomas. BALB/c B cells specific for TNP or FITC presented hapten-modified proteins (TNP-G1 phi, TNP-OVA, or FITC-OVA) to the relevant T cell hybridomas at concentrations below 0.1 microgram/ml. Effective presentation of the same antigens by B lymphocyte-depleted splenocytes, and of unmodified proteins by either hapten-binding B cells or Ig spleen cells, required about 10(3)-to 10(4)-fold higher concentrations of antigen. The use of two different haptens and two carrier proteins showed that this extremely efficient presentation of antigen was highly specific, with hapten specificity being a property of the B cells and carrier specificity of the responding T cells. The presentation of hapten-proteins by hapten-binding B lymphocytes was radiosensitive and was not affected by the depletion of plastic-adherent cells, suggesting that conventional APCs (macrophages or dendritic cells) are not required in this phenomenon. Antigen-pulsing and antibody-blocking experiments showed that this hapten-specific antigen presentation required initial binding of antigen to surface Ig receptors. Moreover, linked recognition of hapten and carrier determinants was required, but these recognition events could be temporally separated. Finally, an antigen-processing step was found to be necessary, and this step was disrupted by ionizing radiation. These data suggest a role for B cell surface Ig in providing a specific high-affinity receptor to allow efficient uptake or focusing of antigen for its subsequent processing and presentation to T lymphocytes.

Animals↗
PubMed1982

The distribution of enkephalin immunoreactive neuronal cell bodies in the monkey brain: preliminary observations.

The distribution of enkephalin immunoreactive cell bodies was studied in the central nervous system of colchicine-treated monkeys. They followed a distribution pattern similar to enkephalin immunoreactive nerve fibers and terminal fields, and were found throughout much of the spinal cord and brain. Large numbers of enkephalin immunoreactive cell bodies were seen in the brainstem, hypothalamus and in telencephalic nuclear areas. In most regions, the distribution of enkephalin immunoreactive cell bodies in the monkey brain was similar to that reported for the rat.

Animals↗
PubMed1982

The distribution of enkephalin immunoreactive fibers and terminals in the monkey central nervous system: an immunohistochemical study.

Using immunohistochemical techniques, the distribution of met-enkephalin fibers and terminals was studied in the central nervous system of adult old-world monkeys. Areas which showed the greatest density of immunoreactivity included substantia gelatinosa, nucleus tractus solitarius, nucleus parabrachialis, substantia nigra, median eminence, globus pallidus (external segment), patches within the striatum and the region of nucleus accumbens and the olfactory area. Striking and discrete zones of enkephalin immunoreactive fibers and terminals which did not conform to known nuclear boundaries were observed in the latter areas. The distribution of enkephalin in the monkey is compared to what has been described in the rat central nervous system. In general, the two species are similar, however, differences were observed in some areas including the hypoglossal nucleus, substantia nigra and in the region of the nucleus accumbens and olfactory area. The results are discussed with regard to the possible functional significance of enkephalin localization in regions related to regulation of pain, mood, and autonomic function.

Animals↗
PubMed1981

A primate analogue of amphetamine-induced behaviors in humans.

The effects of amphetamine on individual and social behaviors were studied in two colonies of rhesus monkeys. After an initial base-line period, each animal, in turn, received low chronic drug administration for 3 weeks. Between each drug period new base-line data were collected. During amphetamine administration, there was a significant increase in the following behaviors: time spent in "sit tense" postures, frequency of orienting, and frequency of agonistic behaviors. In addition, significant changes were seen in the time spent in proximity with other members of the group. The results are discussed both in terms of across-animal changes as well as with regard to social factors, rank in the hierarchy, and affiliative relationships.

Agonistic Behavior↗
PubMed1980

Recent biosynthetic studies on beta-lactam antibiotics.

Recent experimental observations on the cell-free formation of penicillins and cephalosporins in protoplast lysates from C. acremonium are described. Conversion of radiolabelled penicillin N into deacetoxycephalosporin C is described. A proposal is made about the general types of mechanism involved in these conversions.

Acremonium↗