Search PubMed⌕ Search

Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 523 records · Page 29Linked to original sources
PubMed1984

Detection of mycoplasmas infecting cell cultures by DNA hybridization.

Infection of cell cultures by mycoplasmas can be detected and the mycoplasma identified by Southern blot hybridization of the Eco RI-digested DNA of the suspected cell cultures with a nick-translated probe consisting of cloned ribosomal RNA genes of Mycoplasma capricolum. The probe does not hybridize with eukaryotic DNA. The hybridization pattern with mycoplasmal DNA is species specific, enabling the identification of the four most prevalent mycoplasma contaminants, Mycoplasma orale, Mycoplasma hyorhinis, Mycoplasma arginini, and Acholeplasma laidlawii. The test is also very sensitive and can detect as little as 1 ng of mycoplasmal DNA, roughly equivalent to the DNA content of 10(5) mycoplasmas.

Animals↗
PubMed1984

Microinjection of the oncogene form of the human H-ras (T-24) protein results in rapid proliferation of quiescent cells.

Using an E. coli expression-vector system we have efficiently produced, purified, and characterized the full-length, nonfused, protooncogenic and oncogenic (T-24) forms of the human H-ras gene product. These purified ras proteins have been introduced by microinjection into a variety of somatic cells in an effort to examine their function. Within several hours after injection of the oncogenic form of the human H-ras protein into quiescent cells, we observe dramatic morphological changes followed by transient proliferation of the cells. In contrast, microinjection of the normal, protooncogenic form of the ras protein at the same level appears to have only little effect on the cells. Additional experiments indicate that the effect of the ras protein requires entry into the cells, is temporary, is inhibited by cycloheximide or actinomycin D, and is seen only in established cell lines. This experimental approach demonstrates that the bacterially derived and purified human H-ras proteins retain their ability to function when put back into mammalian cells and furthermore, provides a novel assay for transformation induced in established cells by the human H-ras oncogene protein.

Animals↗
PubMed1984

Osteopenia in hypoestrogenic young women with anorexia nervosa.

Replacement estrogen therapy for premenopausal women with secondary hypogonadism (exercise/weight loss amenorrheas) remains controversial. In a group of 14 women with anorexia nervosa, amenorrhea, and no evidence of other endocrinopathy or protein-calorie malnutrition, significant osteopenia was demonstrated as assessed by cortical thickness of carpal bones. The degree of bone thinning was related to the duration and age at onset of amenorrhea as well as abnormalities of pubertal milestone progression. In the young women with "constitutionally delayed" menarche, or with secondary amenorrhea and hypogonadism, significant osteopenia may also be present. For those women with (1) hypoestrogenism and amenorrhea of over 36 months' duration, (2) pubertal delay, and (3) early onset of secondary amenorrhea, evaluation of osteopenia radiographically, and serious consideration for estrogen replacement, is important.

Adolescent↗
PubMed1984

Immunohistological differential diagnosis of inflammatory colonic diseases.

Immunohistological investigations were carried out on human colonic tissue from, I healthy mucosa, 2 slightly inflamed mucosa, 3 mucosa with ulcerative colitis, 4 mucosa with Crohn's colitis, using antibodies against immunoglobulins and complement components. All our antibodies, including F(ab')2 fragments, demonstrated a progressive increase of labelled cells from healthy mucosa through slightly inflamed mucosa to mucosa with ulcerative colitis, in contrast to a complete absence of labelled cells in cases of Crohn's disease. The results are discussed with regard to their pathogenesis and their clinical significance for the differentiation of ulcerative colitis and Crohn's colitis.

Colitis↗
PubMed1983

Equilibration of methionine into the Met-tRNA pool of rabbit reticulocyte lysates. Additional evidence that deacylation of ribosomal subunit-bound Met-tRNAf does occur in heme-deficiency.

We have measured the rate of equilibration of [35S]methionine into the Met-tRNA pool of rabbit reticulocyte lysate as in [FEBS Lett. (1982) 143, 301-305]. Our results indicate that hemin-deficiency inhibits the equilibration of methionine into the tRNA pool much less than protein synthesis or the equilibration of alanine into the tRNA pool, whereas cycloheximide inhibits these processes similarly. This finding is consistent with our previous data and supports the hypothesis that with hemin-deficiency much of the Met-tRNAf that becomes bound to 40 S subunits subsequently undergoes enzymatic deacylation.

Animals↗
PubMed1983

Differential effect of Mn2+ on the hemin-controlled translational repressor and the double-stranded RNA-activated inhibitor.

The inhibition of protein synthesis that occurs when rabbit reticulocyte lysate is incubated in the absence of hemin is due to the activation of a protein kinase termed the hemin-controlled translational repressor, and that occurring when reticulocyte lysate is incubated with a low level of double-stranded RNA is mediated by the activation of a separate protein kinase termed the double-stranded RNA-activated inhibitor. Both the hemin-controlled translational repressor and the double-stranded RNA-activated inhibitor act by phosphorylating the Mr = 35,000 (alpha) subunit of eIF-2. MnCl2 (0.5 mM) partly reverses the inhibition of protein synthesis produced by hemin deficiency but not that induced by double-stranded RNA. In addition, Mn2+ reverses the inhibition of binding of [35S]Met-tRNAf to reticulocyte ribosomal components, isolated on Sepharose 6B, produced by the hemin-controlled translational repressor but not by the double-stranded RNA-activated inhibitor. The effect of Mn2+ is mediated at the level of activation and eIF-2 alpha kinase activity of these two regulatory protein kinases. Specifically, Mn2+ inhibits activation of the hemin-controlled translational repressor in the absence of hemin and the phosphorylation of eIF-2 alpha by pre-activated translational repressor. In contrast, the phosphorylation of eIF-2 alpha by the double-stranded RNA-activated inhibitor is not suppressed by Mn2+, and the activation and autophosphorylation of this inhibitor is enhanced by Mn2+. Finally, while the activation and inactivation of the hemin-controlled translational repressor does not appear to be mediated by autophosphorylation and dephosphorylation, the activation of the double-stranded RNA-activated inhibitor does appear to require autophosphorylation.

Animals↗
PubMed1983

Molecular cloning and nucleotide sequence of the type I beta-lactamase gene from Bacillus cereus.

The gene for the type I beta-lactamase from Bacillus cereus has been cloned in Bacillus subtilis and Escherichia coli. In B. subtilis, penicillinase activity is detected and the enzyme is secreted. In E. coli, the gene confers ampicillin resistance. The cloned insert is 4.3 kb in length and DNA sequencing has revealed the location of the gene, its promoter and signal peptide.

Amino Acid Sequence↗
PubMed1983

The effect of sex steroids and hormonal contraceptives upon thymus and spleen on intact female rats.

In view of a possible influence on oral contraceptives upon the immune system, the effect of chronic treatment of intact adult female rats with sex steroids and contraceptive preparations upon the thymus and the spleen was investigated. Daily injections with 10 micrograms estradiol, estradiol benzoate, or diethyl stilbestrol for 2 weeks resulted in a marked but reversible involution of the thymus, while the spleen was not affected. Androgens exerted a significant effect at a dose of 0.3 mg, and progestogens only when 2 mg were given. When various contraceptive preparations were injected for 4 weeks, there was a total involution of the thymus which persisted even 2 weeks after cessation of treatment. The effect appeared to be mainly due to the estrogenic component. Progestogens intensified the reduction of thymic weight only at higher doses. Histological examinations revealed that estrogen treatment alone resulted in a reduction of the cortex and a depletion of lymphocytes. When contraceptive preparations were administered, the medulla was also reduced, and both cortex and medulla were replaced by reticular and adipose tissue. The estrogen receptors of thymus cytosol showed dissociation constants between 0.34 and 0.49 nM in diestrous rats, progesterone-treated rats and ovariectomized rats, and binding capacities between 6.5 and 2.6 fmoles/mg protein. It remains, however, to be shown whether the estrogen-induced involution of the rat thymus may lead to an impairment of immune responses.

Androgens↗
PubMed1983

Effect of phenoxybenzamine on cardiovascular and plasma catecholamine responses to clonidine.

To determine whether the alpha-adrenergic antagonist phenoxybenzamine would alter cardiovascular or plasma catecholamine response to the alpha-adrenergic agonist clonidine, six patients with pheochromocytomas and eight with labile hypertension were studied. Clonidine, 0.3 mg, was given with and without 48 hr pretreatment with 30 mg/day phenoxybenzamine. The response to 10 mg diazepam was also observed in seven of the subjects who had labile hypertension. In the hypertensive patients, clonidine alone induced a fall in supine blood pressure from 137 +/- 21/91 +/- 14 to 109 +/- 18/76 +/- 17 mm Hg and, with phenoxybenzamine, clonidine reduced blood pressure from 141 +/- 22/89 +/- 10 to 107 +/- 21/72 +/- 11 mm Hg. Plasma norepinephrine fell from 179 +/- 60 to 107 +/- 79 pg/ml without phenoxybenzamine and from 229 +/- 159 to 95 +/- 46 pg/ml with phenoxybenzamine in hypertensive subjects. Responses with phenoxybenzamine did not differ from those without phenoxybenzamine and diazepam induced no cardiovascular or plasma catecholamine changes. Clonidine did not lower plasma catecholamines in patients with a pheochromocytoma in the presence or in the absence of phenoxybenzamine. Blood pressure tended to decline after clonidine in pheochromocytoma patients not taking phenoxybenzamine, but it was not reduced by clonidine when these patients were taking phenoxybenzamine. Phenoxybenzamine does not inhibit reduction in blood pressure and plasma catecholamines induced by clonidine in patients with essential hypertension or interfere with the clonidine suppression test in patients with pheochromocytomas.

Blood Pressure↗
PubMed1983

Scoliotic spinal anthropometry.

Three-dimensional spinal data were collected from AP and lateral spinal radiographs of 24 female adolescent idiopathic scoliotics. Vertebral body end-plate eccentricity (AP vertebral body width divided by lateral vertebral body width) was measured and found to be minimized at the apex of the scoliotic curve in approximately 70 percent of the subjects. Measurement of end-plate eccentricity is suggested as a possible method for assessment of vertebral body rotation in scoliotic subjects.

Adolescent↗