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Biomedical subjects

M Schwartz

Publications and source records attributed to M Schwartz.

At least 721 records · Page 40Linked to original sources
PubMed1981

Immunocytochemical localization of (Na+, K+)-ATPase in the goldfish optic nerve.

Antiserum to the catalytic subunit of goldfish brain (Na+, K+)-ATPase has been employed at the electron microscopic level by means of the peroxidase-antiperoxidase immunohistochemical method. In optic nerve, antigenic sites are restricted to the nodes of Ranvier. No reaction product is detected in underlying internodal neurolemma. Outgrowing neurites for cultured retinal explants devoid of glial ensheathment exhibit a continuous distribution of the enzyme subunit. Antibodies against eel electroplax (Na+, K+)-ATPase cross-react with the goldfish brain enzyme and show a similar immunocytochemical distribution pattern.

Animals↗
PubMed1981

Origins of positive potential difference of frog gastric mucosa in Cl--free solutions.

Experiments were performed on gastric mucosae of Rana pipiens with an in vitro method. Bathing both sides of the mucosae in Cl--free solutions resulted in an inverted potential difference (PD) (i.e., nutrient negative). Cimetidine in a concentration of 10(-4) or 10(-3) M in the nutrient solution gave a positive PD when the H+ secretory rate was zero or near zero and confirmed that the PD versus H+ rate was linear. the origins of the positive PD were examined by ion replacement, e.g., choline for Na+ in both solutions. When both solutions had 25 mM HCO(-)3 (i.e., no HCO(-)3 gradient), the difference in PD between choline sulfate and Na2SO4 solutions indicated a possible small active transport of Na+ from the secretory to nutrient side. Similar experiments indicated no active K+ transport. A residual PD occurred without Na+. With H+ rate zero, 100% O2, and no HCO(-)3, a base secretion of about 0.4 mueq.h-1.cm-2 was obtained in a direction to contribute to the positive PD. Active SO2(-)4 transport may occur.

Animals↗
PubMed1981

Male pseudohermaphroditism secondary to an abnormality in Leydig cell differentiation.

We present the first case of a prepubertal male with an abnormality in Leydig cell differentiation resulting in male pseudohermaphroditism. There was no plasma androgen response to im administration of hCG. Leydig cells were not apparently by either light or electron microscopy in tissue obtained from a biopsy of the right testis 96 h after the last dose of hCG. In addition, LH-hCG saturation analyses performed on membrane preparations from the testicular tissue revealed no binding. An expanded classification for male pseudohermaphroditism is presented.

Cell Differentiation↗
PubMed1981

The papaverine test for blood flow potential of the profunda femoris artery.

In reconstructive surgery of the arteries, the inflow tract is as important as the distal runoff. Since information about the hemodynamic significance of either cannot be obtained from an arteriogram , accurate assessment of flow within the arterial segment to be reconstructed must be obtained by other means. A functional pharmacologic test, consisting of the intra-arterial injection of 30 milligrams of papaverine hydrochloride which, under normal circumstances, can usually induce a 100 per cent increase, or more, in basal blood flow has been used to define theoretic maximum flow capacity by means of a linear quantitative relationships. The test also can unmask any undetected lesions in the inflow tract or technical errors occurring at the time of operations. From the results of this study, it is apparent that the use of a pharmacologic test for flow rate has demonstrated that profundaplasty makes a significant contribution to relieving symptoms of ischemia in the lower limb. This, in turn, brings about the resolution of certain types of tissue necrosis distally and safely improves the quality of life.

Aged↗
PubMed1981

Explanation of the effects of imidazole, aminopyrine, and thiocyanate on gastric secretion.

On the basis of the model of figure 9 and its equivalent circuit of figure 10, explanations have been presented for the inhibition of the SCN type of inhibitors and the reversal of their inhibition by the weak bases, imidazole and aminopyrine. On the basis of the model, we have presented explanations for the changes in PD and resistance associated with the SCN type of inhibitors. Explanations of the other effects of the SCN type inhibitors and the effects of the weak bases are possible on the basis of the model. However, these explanations involve some lengthy analysis beyond the scope of the present paper. The model supplies the conceptual basis for a considerable number of further substantive experiments.

Aminopyrine↗
PubMed1980

The use of human menopausal and chorionic gonadotropins for induction of ovulation. Sixteen years' experience at the Sloane Hospital for Women.

Gonadotropin therapy for anovulation is highly successful: 58.6% of treated patients conceive. Better results are achieved in patients with galactorrhea-amenorrhea (77.1%) and hypogonadotropic hypogonadism (63.3%) than in patients with normal gonadotropin levels (45.4%). The spontaneous abortion rate (27.5%) is somewhat higher than that in spontaneous pregnancies. The multiple pregnancy rate is 31% and was slightly lower in cycles with preovulatory estrogen levels in the physiologic range. In patients treated with human menopausal and chorionic gonadotropins for 7 to 9 days per cycle, the multiple pregnancy rate is considerably less (12.9%) than in patients with longer treatment. The efficacy of treatment does not diminish with repeat-treatment cycles.

Amenorrhea↗
PubMed1980

A signal sequence is not sufficient to lead beta-galactosidase out of the cytoplasm.

Escherichia coli strains have been constructed in which lacZ, the gene for the cytoplasmic enzyme beta-galactosidase, is fused to lamB, the gene for an outer membrane protein. One such strain produces a beta-galactosidase which remains cytoplasmic even though it possesses the complete signal sequence of the lamB protein precursor at the amino-terminal end.

Amino Acid Sequence↗
PubMed1980

Histological localization of binding sites of alpha-bungarotoxin and of antibodies specific to acetylcholine receptor in goldfish optic nerve and tectum.

Goldfish optic nerve as well as ganglion cell neurites grown in culture selectively bind rhodamine-labeled alpha-bungarotoxin following tissue fixation. Binding is competed for by unlabeled bungarotoxin, by carbamylcholine and tubocurarine, but not by atropine. In cross-sections, the label is seen confined to axonal bundles. The binding is not detectable without prior fixation and is very faint in brain sections, even after fixation. To further establish the nature of the binding, immunocytochemical studies were performed, taking advantage of a high cross-reactivity found between goldfish brain and antibodies against eel acetylcholine receptor (AChR). Antigenic sites were detected by an indirect unlabeled antibody complexed to horseradish peroxidase. Anti-AChR antibody binding to optic nerve and neurites in culture correlated with that seen with alpha-bungarotoxin. Binding of anti-AChR was observed in the brain, and was reduced in the denervated tectum following unilateral optic nerve crush or enucleation. The results are discussed in relation to functions of receptor proteins in the retinotectal system.

Acetylcholine↗
PubMed1980

Serum zinc, serum copper, and the Cu/Zn ratio in patients with epidermoid cancers of the head and neck.

Serum zinc levels (SZL), serum copper levels (SCL), and the Cu/Zn ratio were evaluated in 50 patients with epidermoid cancer of the head and neck to treatment with respect to site and stage of disease. There was no significant difference in these parameters compared to healthy normal controls. We could not appreciate any diagnostic or prognostic value in these parameters in patients with head and neck cancer. There was, however, a sex-related difference for SZL in men with oral cavity and women with laryngeal lesions, and a trend toward decreasing SZL and increasing SCL and the Cu/Zn ratio with advanced stage of disease.

Adult↗
PubMed1980

Mutants which make more malT product, the activator of the maltose regulon in Escherichia coli.

Some of the previously described malT-lacZ fusion strains (Débarbouillé and Schwartz, 1979) produce very low amounts of beta-galactosidase activity and hence grow poorly on lactose. Spontaneous mutants growing faster on lactose have been isolated. Some of the mutations map in, or close to, the promoter of the hybrid gene. They lead to an increased production of the hybrid proteins, which then become detectable on polyacrylamide gels. This effect is cis dominant. When the mutations, called malTq, are transduced into a malT+ background the resulting transductants express the three maltose operons in a partially constitutive way. The malTq mutations therefore represent a new type of constitutive mutation. Their existence provides further evidence for the previously proposed model of positive regulation in the maltose regulon. In addition they should facilitate the purification of the malT product, and the identification of the malT promoter on the DNA.

Escherichia coli↗