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J Hochman

Publications and source records attributed to J Hochman.

At least 55 records · Page 3Linked to original sources
PubMed1980

Cell substrate adhesiveness in S49 mouse lymphoma.

A new variant subline was selected from S49 mouse lymphoma cells grown in suspension culture. These cells, designated S49-Adh, demonstrate increased adhesiveness to their substratum. This, in turn, allows them to grow as a monolayer. Once a dense monolayer is formed, daughter cells develop as a suspension borne population while still retaining their substrate adhesiveness. Cell substrate adhesiveness is a stable genetic trait insofar as submitting S49-Adh cells to both extended periods of in vitro cultivation in culture medium, or in vivo selection through passage in nude mice didn't change their substrate-adhesive phenotype.

Animals↗
PubMed1978

Relaxin.

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Amino Acid Sequence↗
PubMed1978

Relaxin bioactivity and immunoactivity in human corpora lutea.

Relaxin-like activity in extracts of corpora lutea (CL) from pregnant and non-pregnant women was determined by radioimmunoassay and by guinea pig pubic symphysis palpation assay. The biologically determined activity paralled the immunoactivity of extracts of CL of pregnancy. The relaxin content of CL of non-pregnant women was too low for detection by the bioassay.

Animals↗
PubMed1978

Distribution of relaxin in women during pregnancy.

The purpose of this study was to determine by RIA the concentrations of relaxin in various compartments and tissues in pregnant women. Ten pairs of maternal venous and cord blood were studied. The mean relaxin concentrations, in immunoreactive equivalents of porcine relaxin, were 0.683 ng/ml in maternal serum and 0.009 ng/ml in cord serum. Relaxin was undetectable in 8 of 9 samples of amniotic fluid. Mean concentrations of relaxin in pg immunoreactive equivalents of porcine hormone per mg protein, from maternal tissues at term pregnancy were as follows: fat 96 (N = 5), myometrium 47 (N = 4), skin 62 (N = 5), placenta 51 (N = 9), and corpus luteum 13,000 (N = 8). These data suggest that little relaxin crosses the placenta and little is produced in the fetus. Contrary to prior suggestions that relaxin may also be a placental product, relaxin appears to be solely produced in the corpus luteum, making it the only peripherally measured hormone that can be used as an index of luteal activity in pregnancy.

Amniotic Fluid↗
PubMed1977

Subunit interaction in cyclic AMP-dependent protein kinase of mutant lymphoma cells.

We have previously selected and characterized mutant S49 mouse lymphoma cells that possess an adenosine 3':5'-cyclic monophosphate (cAMP)-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) with an increased apparent affinity constant (Ka) for activation by cAMP. The Ka lesion in one such mutant clone has been shown to result from a structural mutation involving the kinase holoenzyme's regulatory (R) subunit. The present report examines the interaction of R and catalytic (C) subunits of the kinases in extracts of the mutant cells and the normal "wild type" (WT) parental line. Subunit recombination experiments were performed, by using purified WT and mutant R subunits, and C subunits purified from WT cells. As compared to WT R subunits, only 1/6 as much mutant R subunit was required to reassociate with and suppress 50% of C subunit activity, at equilibrium. NaSCN activates cAMP-dependent kinase of both cell types by causing the holoenzyme to dissociate. In comparison with WT, a 2-fold higher concentration of NaSCN is required to maximally activate the kinase in mutant extracts. Both the reassociation result and the increased resistance of the mutant enzyme to a nonspecific dissociating agent strongly suggest that the mutant R subunit binds C subunit more tightly than does the WT R subunit. This interpretation raises the possibility that increased R-C subunit binding affinity in the mutant cell is responsible for the increased Ka for activation by cAMP of the mutant holoenzyme, and thus for the decreased potency of cAMP in regulating intact mutant cells.

Cell Line↗
PubMed1977

Induction of an LH surge with estradiol benzoate in a patient with incomplete testicular feminization syndrome.

A 31-year-old patient with incomplete testicular feminization syndrome characterized by a 46, XY karyotype in a phenotypic female with absent müllerian structures, marked clitoromegaly, testes and wolffian duct structures, partial labioscrotal fold fusion, and male levels of circulating androgens is described. She was challenged with estradiol benzoate (EB) to simulate the preovulatory surge of estradiol seen in cycling women. This EB challenge resulted in a negative feedback response for FSH but an LH surge similar to that induced with EB in cycling women. This suggests that in the incomplete testicular feminization syndrome there is hypothalamic or pituitary resistance to the blocking effects of androgens on LH surge production.

Adult↗
PubMed1976

Ultrastructural immunohistochemical localization of vasopressin in the hypothalamic-neurohypophysial system of three murids.

Vasopressin was immunohistochemically localized at the electron microscopic (EM) level in the hypothalamic-neurohypophysial system (HNS) of three murids. Antiserum to vasopressin was produced in rabbits injected with lysine vasopressin (LVP) conjugated to egg albumin (EA), anti-EA being precipitated prior to staining. Sternberger's unlabeled antibody peroxidase technique was employed, immunoreactivity being designated by peroxidase-anti-peroxidase (PAP) molecules and electron opacity. Immunoreactive neurosecretory granules (NSG) were found in the perikarya of the supraoptic nucleus (SON) in all three murids investigated, although far more profusely in the two wild strains. Immunoreactive axonal NSG were observed in the inner and outer zones of the median eminence (ME), and within most of the axons and terminals in the neurohypophysis. The concentration of primary serum effective for staining the SON (1:10-1:50) was far higher than that required for the ME and the neurohypophysis (1:500-1:1,200). Anti-LVP also induced electron opacity of granules in cells of the pars intermedia (PI). Discussion centers of the significance of immunoreactive NSG in the neurosecretory (NS) perikarya, on the possibility of an extragranular pool of hormone, and on speculation about the electron opacity of the PI granules.

Animals↗
PubMed1976

Folding and interaction of subunits at the antibody combining site.

The Fv fragment derived from mouse myeloma protein 315 possessing anti-dinitrophenyl (DNP) activity, is composed of two subunits, the peptide chain VL and VH. In 8 M urea there is a complete dissociation of VL and VH and an approximately twofold increase in the fluorescence emission of Fv with a characteristic red shift of 11 nm. Upon dilution of Fv from 8 M urea into neutral buffer full regain of activity was observed, concomitant with regain of native fluorescence spectrum. The decrease in fluorescence upon dilution from 8 M urea was used to follow the renaturation process of Fv. At relatively high protein concentration (2.5 x 10(-6) M) two steps were observed during renaturation: a fast one, which is completed in less than 30 s, and a slower step, which proceeds for approximately 20 min. The fast process represents the refolding and association of VL and VH to form an active FV, whereas the slow step is attributed to the formation of "incorrect" associates between VL and VH which slowly reshuffle to the thermodynamically stable active FV. Indeed, at low protein concentration (1.5 x 10(-8 M) only the fast step is observed and renaturation is completed in less than 30s. The presence of hapten does not affect the rate of renaturation of FV. Reoxidation of FV completely reduced in 8 M urea was also found to yield a fully active Fv. Since either VL or VH have only one intrachain disulfide bond, reoxidation was performed at high protein concentration (3 mg/ml) in 8 M urea followed by dilution into neutral buffer. This demonstrates that variable domains not only exist in immunoglobulin structure but can also fold correctly independent of the rest of the peptide chains.

Animals↗
PubMed1976

Catecholamine secretion by isolated adrenal cells.

Isolated adrenal cells were prepared by collagenase digestion of guinea pig adrenal glands. Acetylcholine stimulates the secretion of catecholamines by these isolated adrenal cells. Acetylcholine-stimulated catecholamine secretion is inhibited by cholinergic blocking agents (atropine and hexamethonium) and by local anaesthetics (tetracaine), and is dependent upon the concentration of Ca2+ in the incubation medium. In the presence of Ca2+, catecholamine secretion is also stimulated by two divalent cation ionophores, A23187 and X-537A. Cyclic nucleotides and 5'-nucleotides cause a small, non-specific stimulation of catecholamine secretion. These results indicate that isolated adrenal cells are a useful system in which to study catecholamine secretion, and support the hypothesis that increased Ca2+ entry into chromaffin cells is a sufficient stimulus for catecholamine secretion.

Acetylcholine↗