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Biomedical subjects

M S Schwartz

Publications and source records attributed to M S Schwartz.

At least 19 recordsLinked to original sources
PubMed1992

The effect of parity, tumor latency and transplantation on the activation of int loci in MMTV-induced, transplanted C3H mammary pre-neoplasias and their tumors.

Mouse mammary tumor virus (MMTV) infection of mammary glands results in proviral insertion into host DNA and activation of cellular genes. Clonal expansion of cells bearing insertional mutations results in hyperplastic alveolar nodules (HAN) and tumors. HAN, transplanted into epithelium-cleared mammary fat pads, form hyperplastic alveolar outgrowths (HOGs). Previous work indicates the commonly MMTV-activated genes wnt-1 and int-2 are rarely affected in HOGs and HOG-derived tumors. To determine the basis of the dichotomy between the frequency of wnt/int gene activation in HOG-derived tumors and tumors from breeders of the identical inbred mouse strain, we compared the activation of wnt-1, int-2 and int-3 in tumors from virgin and breeding C3H mice, in consecutive primary tumors arising in individual C3H breeders and in C3H HOGs at early passages. Activation of wnt-1 or int-2 was rare in HOG-derived tumors (6% and 0%) compared with primary tumors in breeders (52% and 14%). int-3 was never found to be activated. wnt-1 was activated in the same percentage of primary tumors from virgins as from breeders. int-2 was activated only in tumors from breeders. wnt-1 activation also did not correlate with shorter tumor latency in multiple tumors from individual breeders. wnt-1 RNA was not detected in HOGs at early transplant generations, however, low levels of wnt-1 RNA were variably found in the epithelium of virgin mammary glands. We cannot explain why C3H HOGs and their derivative tumors develop without wnt-1 expression when the majority of C3H primary mammary tumors possess an MMTV-activated wnt-1 gene.

Animals↗
PubMed1992

Comparative pharmacokinetics of lovastatin, simvastatin and pravastatin in humans.

Twelve healthy male volunteers received single market-image 40-mg oral doses of lovastatin and simvastatin (both lactone prodrugs), or pravastatin (a beta-hydroxyacid) at 1 week intervals in a three-way crossover study to quantify HMG-CoA reductase inhibitors in plasma. Multiple plasma samples were collected up to 24 hours after the dose and assayed for active and total HMG-CoA reductase inhibitors. After equal oral doses, higher plasma concentrations of HMG-CoA reductase inhibitory activity after pravastatin than after either lovastatin of simvastatin (2-3 fold greater area under the concentration-time curve) suggest a greater potential availability of pravastatin-related inhibitory activity to peripheral tissues.

Administration, Oral↗
PubMed1992

Fiber density in acute and chronic inflammatory demyelinating polyneuropathy.

The fiber density in the deltoid, extensor digitorum communis, and first dorsal interosseous muscles was measured using SFEMG in 11 patients with acute and chronic inflammatory demyelinating polyneuropathy. The fiber density was increased in 58% of the muscles studied. The deltoid muscle was the most abnormal of the 3 muscles studied. There was no correlation with the clinical syndrome, with conduction block or slowed motor conduction, or with the distribution of weakness. Changes were noted even in patients studied within 3 weeks of presentation, suggesting that reinnervation begins soon after the onset of the disease.

Adult↗
PubMed1992

Epilepsy as the presenting feature of neuroacanthocytosis in siblings.

A brother and sister developed epilepsy at the age of 28 and 30 years respectively, and were subsequently found to have neuroacanthocytosis. The brother developed tics, and a tendency to self-mutilate a year later, but his sister had not developed any movement disorder in the 5 years since the onset of epilepsy. In families with epilepsy, the diagnosis of neuroacanthocytosis should be considered, particularly when one family member has tics or other involuntary movements.

Adult↗
PubMed1992

What do we really know about amyotrophic lateral sclerosis?

The cause of amyotrophic lateral sclerosis is unknown. In this review clinical and scientific data that are pertinent to understanding this disease are reviewed. There are currently several major controversies concerning the possible role of immunological factors, genetic factors, environmental toxins, and viral infection in pathogenesis. These concepts must be considered in relation to what is known about the disease in all its aspects, including epidemiological data, information on the classical and molecular pathology of the disease, and on associated involvement of other systems, e.g., the spinocerebellar pathways and frontal dementia. Only when all this information is assimilated can full understanding of the disease and, hopefully, a logical approach to treatment and prevention, be achieved.

Amyotrophic Lateral Sclerosis↗
PubMed1991

Overexpression of oncogene products can cause tumor progression without parenchymal infiltration in the rat brain.

Tumor cell progression and parenchymal infiltration play important roles in the pathogenesis of gliomas. Using retrovirally marked rat 9L gliosarcoma cells, which when injected in the CDF rat brain form noninfiltrating tumors which grow only surrounding existing blood vessels, we were able to investigate elements of tumor growth and progression within the substance of the brain. Transfection of 9L by oncogenes associated with tumor progression and expressed in gliomas resulted in alterations in the in vivo phenotype of these cells, with the production of faster growing, well-vascularized, large solid tumors. However, diffuse infiltration was not seen. Moreover, coinjection of 9L or its transfectants together with the infiltrative C6 cell line resulted in a mixed tumor of noninfiltrating 9L cells in an environment of infiltrating C6 cells, suggesting that the infiltrative ability of C6 cells is controlled on the individual cell level.

Animals↗
PubMed1991

Asymmetrical weakness in polymyositis associated with neuropathic involvement.

Peripheral nerve involvement is rare in polymyositis and dermatomyositis. We describe a patient in whom the clinical appearance was suggestive of a markedly asymmetrical presentation of polymyositis. Nerve conduction studies, however, were consistent with multiple neuropathies and suggest that neurological involvement may have been the basis of the asymmetrical weakness. Both the muscle weakness and the neurological abnormalities resolved with corticosteroid therapy. This case illustrates a previously undescribed neurological complication of polymyositis.

Humans↗
PubMed1979

Significance of immunoglobulin deposition in peripheral nerve in neuropathies associated with paraproteinaemia.

Direct and indirect immunofluorescent studies of sural nerves were carried out in two patients with paraproteinaemia and neuropathy, in four other patients with axonal or demyelinating neuropathies, and in one normal sural nerve. IgM was demonstrated directly in the two cases of paraproteinaemia and neuropathy, and indirectly, using the serum of one of these cases, in a case of axonal neuropathy and in one case of chronic Guillain-Barré syndrome. In the latter case, IgM deposition also occurred after exposure to normal serum. These results suggest that the paraprotein itself did not directly cause neuropathy, but that immunoglobulin deposition is probably a secondary process, caused by diffusion into damaged nerves.

Aged↗
PubMed1978

Benign postinfection polymyositis.

Six patients developed persistent muscular cramps, aching pain, and fatigability after an influenza-like illness. Electromyography showed myopathic changes, although results of routine laboratory investigations were normal in all but one patient, whose serum creatine kinase concentration was slightly increased. All but one of the patients improved: three were asymptomatic within one to two years. The syndrome was probably a benign form of polymyositis.

Adult↗
PubMed1978

The significance of ragged-red fibres in neuromuscular disease.

The pathological significance of ragged-red fibres is uncertain. We have studied ragged-red fibres in the muscle biopsies of 3 adults; one with polymyositis and two with progressive external ophthalmoplegia. All the ragged-red fibres were Type 1 fibres. In two patients the mean diameter of the ragged-red fibres was significantly smaller than the unaffected Type 1 fibres. Some of these fibres showed features of regeneration, and others of degeneration. In the patient with polymyositis the mitochondria were proliferated and contained osmiophilic dense bodies; in the other two patients paracrystalline mitochondrial inclusions were prominent. These findings suggest that ragged-red fibres do not represent a single pathological process.

Adult↗
PubMed1978

Pathological stimulus-related slow wave arousal responses in the EEG.

A group of 55 patients were studied who showed in their EEGs prolonged episodes of delta activity, in response to either auditory or tactile stimuli or both. This unusual pattern occurred with states ranging from drowsiness to deep coma but never in alert patients. It was found in a variety of conditions, most commonly following head injury. The EEG phenomenon disappeared within 5 weeks and over half of the patients had a favourable outcome.

Acoustic Stimulation↗
PubMed1977

Correlation of single fibre EMG and muscle histochrmistry using an open biopsy recording technique.

Single fibre electromyographic (SFEMG) recordings were carried out during open muscle biopsy. Nine patients were studied, including 5 with Duchenne muscular dystrophy, 2 with spinal muscular atrophy and 1 each with limb-girdle dystrophy and myotonic dystrophy. Correlations were possible between the SFEMG fibre density determinations and histochemical evidence of grouping in some biopsies, particularly involving Type I fibres. This combined technique permits an improved assessment of the functional state of abnormal muscle.

Adolescent↗
PubMed1977

Adrenergic agents. 8.1 Synthesis and beta-adrenergic agonist activity of some 3-tert-butylamino-2-(substituted phenyl)-1-propanols.

Replacement of the benzylic hydroxyl group of N-tert-butylnorepinephrine with a hydroxymethyl substituent affords a propanolamine homologue which retains a high degree of beta-adrenergic agonist activity. As modification of the meta substituent of catecholic ethanolamines, such as N-tert-butylnorepinephrine, often provides compounds that exert a more pronounced effect in relaxing tracheobronchial smooth muscle (beta2-adrenergic agonist) than in stimulating cardiac muscle (beta1-adrenergic response), a series of 3-tert-butylamino-2-(3-substituted 4-hydroxyphenyl)-1-propanols was prepared. The 3-meta substituents included HOCH2 (1b), H2NCONH (1c), MeSO2NH (1d), H (le), and NH2 (1f). These phenylpropanolamine derivatives were compared with their phenylethanolamine counterparts in in vitro tests that measure the ability of these compounds to relax spontaneously contracted guinea pig tracheal smooth muscle (a measure of potential bronchodilating activity) and to increase the rate of contraction of a spontaneously beating guinea pig right atrial preparation (an indicator of potential cardiac stimulating activity). In these tests all of the propanolamine derivatives included in the study were less potent than their ethanolamine relatives. In both series replacement of the catecholic m-hydroxyl group with the indicated substituents usually resulted in compounds with increased selectivity for tracheobronchial vs. cardiac muscle.

Adrenergic beta-Agonists↗
PubMed1977

Adrenerigic agents. 7.1 Synthesis and beta-adrenergic agonist activity of several 2-pyridylethanolamines.

In a search for new selective bronchodilators, three 2-pyridylethanolamines, i.e., 2-tert-butylamino-1-(5-hydroxy-2-pyridyl)ethanol (2b), a related 6-methylsulfonylmethyl (2c), and, a 6-methyl (2d) derivative, were prepared. These compounds were examined for potential bronchodilator activity in an in vitro test for relaxation of guinea pig tracheal tissue. Potential cardiac stimulant activity was evaluated in vitro by measuring changes in the rate of spontaneously beating guinea pig right atrial muscle. Comparison of potency in the tracheal test relative to that in the atrial procedure provides a measure of selectivity. Results of this study indicate that replacement of the phenyl ring of a para-hydroxylated phenylethanolamine with a 2-pyridyl system generally results in compounds which retain a high order of potency in the tracheal test; however, selectivity for tracheobronchial vs. cardiac tissue is markedly greater for the pyridyl derivatives. The alpha-picoline, 2-tert-butylamino-1-(5-hydroxy-6-methyl-2-pyridyl) ethanol (2d), which bears labile protons at a position meta to the ethanolamine side chain, was about equipotent with the corresponding 6-unsubstituted relative 2b. The reason for the failure of these apparently appropriately located labile protons to enhance beta-adrenoreceptor agonist activity is uncertain.

Adrenergic beta-Agonists↗