Search PubMed⌕ Search

Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 505 records · Page 28Linked to original sources
PubMed1986

Factors associated with microhematuria in asymptomatic young men.

The prevalence of asymptomatic microhematuria (two to four or more erythrocytes per high-power field) in 1341 male Air Force personnel was 5.4%. The most powerful predictor of microhematuria (nearly 15-fold increased prevalence) was a history of recurrent microhematuria during the previous five years. Recurrent microscopic hematuria was present in 14.5% (8/55) of men with a history of urethritis, accounting for 26% (8/31) of the cases of recurrent microscopic hematuria. The prevalence of microhematuria was not affected by physical exercise, flight duty, or sexual intercourse during the 24 h preceding the urinalysis.

Adolescent↗
PubMed1986

Systolic blood pressure in fighter pilots after 12-15 years service.

Systolic blood pressure (SBP) was measured at entry and after 12-15 years in 112 fighter pilots and compared to 112 transport and helicopter pilots. The pilots were 20-24 years old on entry into the study. Mean SBP +/- 1 S.D. on entry was 122 +/- 12 mm Hg in fighter pilots and 124 +/- 12 mm Hg in transport and helicopter pilots. After 12-15 years follow-up the mean SBP was 118 +/- 12 mm Hg in both groups. We conclude that the stress of flying fighter aircraft for 12-15 years is not associated with an increased risk of hypertension.

Adult↗
PubMed1985

Evidence that the primary effect of phosphorylation of eukaryotic initiation factor 2(alpha) in rabbit reticulocyte lysate is inhibition of the release of eukaryotic initiation factor-2.GDP from 60 S ribosomal subunits.

The phosphorylation of eukaryotic initiation factor (eIF) 2 alpha that occurs when rabbit reticulocyte lysate is incubated in the absence of hemin or with poly(I.C) causes inhibition of polypeptide chain initiation by preventing a separate factor (termed RF) from promoting the exchange of GTP for GDP on eIF-2. When lysate was incubated in the presence of hemin and [14C] eIF-2 or [alpha-32P]GTP, we observed binding of eIF-2 and GDP or GTP to 60 S ribosomal subunits that was slightly greater than that bound to 40 S subunits and little binding to 80 S ribosomes. When incubation was in the absence of hemin or in the presence of hemin plus 0.1 microgram/ml poly(I.C), eIF-2 and GDP binding to 60 S subunits was increased 1.5- to 2-fold, that bound to 80 S ribosomes was almost as great as that bound to 60 S subunits, and that bound to 40 S subunits was unchanged. Our data indicate that about 40% of the eIF-2 that becomes bound to 60 S subunits and 80 S ribosomes in the absence of hemin or with poly(I.C) is eIF-2(alpha-P) and suggest that the eIF-2 and GDP bound is probably in the form of a binary complex. The accumulation of eIF-2.GDP on 60 S subunits occurs before binding of Met-tRNAf to 40 S subunits becomes reduced and before protein synthesis becomes inhibited. The rate of turnover of GDP (presumably eIF-2.GDP) on 60 S subunits and 80 S ribosomes in the absence of hemin is reduced to less than 10% the control rate, because the dissociation of eIF-2.GDP is inhibited. Additional RF increases the turnover of eIF-2.GDP on 60 S subunits and 80 S ribosomes to near the control rate by promoting dissociation of eIF-2.GDP but not eIF-2(alpha-P).GDP. Our findings suggest that eIF-2.GTP binding to and eIF-2.GDP release from 60 S subunits may normally occur and serve to promote subunit joining. The phosphorylation of eIF-2 alpha inhibits polypeptide chain initiation by preventing dissociation of eIF-2.GDP from either free 60 S subunits (thus inhibiting subunit joining directly) or the 60 S subunit component of an 80 S initiation complex (thereby blocking elongation and resulting in the dissociation of the 80 S complex).

Animals↗
PubMed1985

Expression of Plasmodium falciparum circumsporozoite proteins in Escherichia coli for potential use in a human malaria vaccine.

The circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum may be the most promising target for the development of a malaria vaccine. In this study, proteins composed of 16, 32, or 48 tandem copies of a tetrapeptide repeating sequence found in the CS protein were efficiently expressed in the bacterium Escherichia coli. When injected into mice, these recombinant products resulted in the production of high titers of antibodies that reacted with the authentic CS protein on live sporozoites and blocked sporozoite invasion of human hepatoma cells in vitro. These CS protein derivatives are therefore candidates for a human malaria vaccine.

Animals↗
PubMed1985

Demonstration and characterization of 1,25-dihydroxyvitamin D3 receptors in basal cells of epidermis of neonatal and adult mice.

Nuclear and cytosolic receptors for 1,25-dihydroxycholecalciferol [1,25(OH)2D3] were demonstrated in the epidermis of neonatal and adult mice. The macromolecular binding protein sedimented at 3.5 S (sucrose density gradient) and was distinct from the 6.0 S binding protein for 25-hydroxycholecalciferol [25(OH)D3]. Analysis at different ionic strengths suggested the presence of unoccupied nuclear receptors. Digestion with proteases or nucleases, respectively, and inactivation with alkylating agents demonstrated that the binding macromolecule is a protein with SH groups at the active site. Binding of 1,25(OH)2D3 was specific and reversible. In neonatal mice KD was 1.6 X 10(-10) M for both cytosolic and nuclear fractions, binding capacity was 54 fmol/mg protein in the cytosolic and 108 in the nuclear fractions, respectively. The phenotypic expression of the 1,25(OH)2D3 receptor (dissociation constant, binding capacity) was identical in neonatal and adult epidermis. Half maximal displacement of 1,25(OH)2D3 was achieved with an 80-fold and 200-fold molar excess of 25(OH)D3 and 1-alpha-hydroxycholecalciferol [1(OH)D3], respectively. Using Percoll density gradient centrifugation, 1,25(OH)2D3 receptors could be localized in the basal cell fraction. DNA cellulose chromatography with 1,25(OH)2D3 receptor elution from DNA at 0.25 M KCl (linear gradient) points to a possible role in gene transcription. In mouse primary epidermal cell cultures, 1,25(OH)2D3, but not 25(OH)D3, 24,25(OH)2D3, and 1(OH)D3 influenced [3H]thymidine incorporation (at physiological concentrations); the magnitude of change depending on the concentration of 1,25(OH)2D3 and the time of incubation. These data demonstrate that skin is a target organ for the active vitamin D secosterol.

Animals↗
PubMed1985

Leukotriene C4 production by murine mast cells: evidence of a role for extracellular leukotriene A4.

The glutathione-containing leukotriene C4 (LTC4) is a major mediator of smooth muscle contraction and is released by mast cells when antigen interacts with cell-bound IgE. Antigen-stimulated mast cells undergo phospholipase activation. We report a pathway of LTC4 production by mast cells that does not require phospholipase activation but depends on the interaction of activated neutrophils with unstimulated mast cells, using as an intermediate extracellular leukotriene A4 (LTA4). The epoxide LTA4 is released by neutrophils and, together with leukotriene B4 and 5-hydroxyeicosatetraenoic acid, constitutes the major lipoxygenase metabolites found in supernatants of stimulated neutrophils. Five minutes after activation of neutrophils by calcium ionophore A23187 we measured 136 pmol of extracellular LTA4 per 10(7) neutrophils (range 40-300, n = 7) by trapping the epoxide with alcohols. Therefore, we conclude that LTA4 is not just an intracellular leukotriene precursor but is released as a lipoxygenase metabolite. LTA4 is known to be stabilized by albumin and is efficiently converted by mast cells into LTC4 even at low LTA4 concentrations. The LTA4 complexed to albumin is converted into LTC4 rapidly and completely within 10-15 min. More than 50% of the LTA4 presented to mast cells is metabolized to LTC4 at concentrations of LTA4 between 0.2 and 2 nmol of LTA4 per 10(7) mast cells. This observation establishes a potential physiologic role for extracellular LTA4. Therefore, interactions between various cell types that release or utilize LTA4 may provide an important metabolic pathway for the production of leukotrienes.

Animals↗
PubMed1985

Purification and characterization of human H-ras proteins expressed in Escherichia coli.

The full-length normal and T24 mutant human H-ras proteins and two truncated derivatives of the T24 mutant were expressed efficiently in Escherichia coli. The proteins accumulated to 1 to 5% of total cellular protein, and each was specifically recognized by anti-ras monoclonal antibodies. The two full-length proteins as well as a carboxyl-terminal truncated derivative (deleted for 23 amino acid residues) were soluble upon cell lysis and were purified to 90% homogeneity without the use of denaturants. In contrast, an amino-terminal truncated ras derivative (deleted for 22 amino acid residues) required treatment with urea for its solubilization. The guanine nucleotide binding activity of these four proteins was assessed by a combination of ligand binding on proteins blots, immunoprecipitation, and standard filter binding procedures. The full-length proteins showed similar binding kinetics and a stoichiometry approaching 1 mol of GTP bound per mol of protein. The showed similar binding kinetics and a stoichiometry approaching 1 mol of GTP bound per mol of protein. The carboxyl-terminal truncated protein also bound GTP, but to a reduced extent, whereas the amino-terminal truncated protein did not have binding activity. Apparently, the carboxyl-terminal domain of ras, although important for transforming function, does not play a critical role in GTP binding.

DNA, Recombinant↗
PubMed1985

Biologic activity of 3beta-D-glucopyranosides of vitamin D compounds.

Polar glycosidic conjugates of vitamin D compounds occur in the vegetable and possibly in the animal kingdom. The biologic activity of these conjugates has not been examined systematically. To obtain more information on the biological role of such sterol conjugates, we examined the biological activity of the 3beta-D-glucopyranosyl conjugates of vitamin D3 5, 25-hydroxyvitamin D3 6, 1alpha-hydroxyvitamin D3 7 and 1alpha,25-dihydroxyvitamin D3 8. When these compounds were administered i.v. we found that a dose of between 50 and 500 pmol/rat of the four glucopyranosides tested increased active intestinal calcium transport and increased bone calcium mobilization in vitamin D-deficient rats fed a low calcium diet. Under the same conditions, corresponding doses of the parent vitamin D3 compounds elicited comparable increases in both intestinal calcium transport and bone calcium mobilization. When these compounds were administered p.o. 3beta-D-glucopyranosyl vitamin D3 5 exhibited no biological activity at doses of up to 5000 pmole/rat, whereas the corresponding glycosides of 25-hydroxyvitamin D3 6, 1alpha-hydroxyvitamin D3 7 and 1,25-dihydroxyvitamin D3 8 were active at doses of 500 to 1000 pmol/rat in the intestinal calcium transport system. When the glucopyranosyl conjugates were administered i.v. to vitamin D-deficient rats, 25-hydroxyvitamin D3 and 1alpha,-25-dihydroxyvitamin D3 were detected in the serum at levels less than or equal to those noted in animals dosed with the respective free sterols.

Animals↗
PubMed1985

The surgical treatment of parosteal osteosarcoma in long bones.

The cases of twenty-five patients with Stage-I parosteal osteosarcoma were analyzed to ascertain the incidence of recurrence after forty-two various surgical procedures that produced an intracapsular, marginal, wide, or radical excisional margin. Ten intracapsular resections were followed by local recurrence in each patient. This procedure usually was done to shell-out a presumably benign lesion. Marginal excision was successful in nine of seventeen patients. When a marginal excision was knowingly done to preserve a major neurovascular bundle, the risk of recurrence was less (three of eleven) than when it was done to shell-out a presumptively benign lesion (five of six). The fourteen procedures that achieved wide margins obtained local control--that is, there was no recurrence--in each patient. There was one radical procedure without recurrence.

Adolescent↗
PubMed1985

Effects of verapamil on etoposide, vincristine, and adriamycin activity in normal human bone marrow granulocyte-macrophage progenitors and in human K562 leukemia cells in vitro.

We have examined the effects of verapamil on the cytotoxicity of etoposide, vincristine, and Adriamycin in human leukemia K562 cells as well as in normal human bone marrow granulocyte-macrophage progenitors (CFU-GM). Etoposide was 10-fold more potent against K562 cells than against normal human bone marrow CFU-GM. Similarly, vincristine cytotoxicity was about 10-fold greater against K562 cells than against human bone marrow CFU-GM. In contrast, Adriamycin exhibited little selectivity for K562 cells versus normal bone marrow CFU-GM during the 1-h incubation period of the experiments. In the presence of verapamil (2.5-10 microM), etoposide cytotoxicity was enhanced in both malignant and normal cells. Verapamil enhanced vincristine (0.1 microM) cytotoxicity in K562 cells but did not potentiate Vinca alkaloid toxicity in normal bone marrow CFU-GM. Adriamycin, on the other hand, did not display any calcium antagonist-mediated potentiation of cytotoxicity in either malignant or normal tissue. These results indicate that short-term (1 h) incubations with etoposide, vincristine, and Adriamycin yield different profiles of toxicities whether used alone or with chemosensitizing agents such as the calcium antagonists. These differences in activities are consistent with different mechanisms for intracellular disposition of these three classes of anticancer agents and are worthy of further investigation, especially with regard to combinations with calcium antagonists.

Bone Marrow↗
PubMed1985

[Vitamin A in the serum of healthy probands and clinical groups].

The estimation of vitamin A in serum of patients suffering from different diseases (M. Crohn, Hypothyroidism, Hyperthyroidism, Liver cirrhosis, Renal insufficiency, Carcinoma of Prostate, ENT-Carcinomas) and healthy controls by means of a recent developed method (HPLC) is reported. Decreased and increased vitamin A serum levels had been reported in literature during different diseases but we could not reveal identical results in all cases. Significantly lowered values were only estimated in patients suffering from liver cirrhosis whereas increased vitamin A serum levels were determined during renal insufficiency. In hypo- or hyperthyroidism there was no difference from healthy persons. In patients with Crohn's disease the distribution of vitamin A concentrations in serum was bimodal, probably depending on extension and localization of the process. Patients with carcinoma of the prostate had only minor deviations from the normal value, whereas patients with tumors of the larynx had in part very low vitamin A concentrations with a bimodal distribution. Causes for the deviations and consequences for the assessment of the vitamin A status of patients under intravenous alimentation are discussed.

Contraceptives, Oral, Hormonal↗
PubMed1984

Isolation and characterization of two forms of Met-tRNAf deacylase from rabbit reticulocyte ribosomes.

We have separated and purified two forms of Met-tRNAf deacylase (or two separate enzymes), an activity that mediates in part the suppression of polypeptide chain initiation that occurs in heme deficiency or with double-stranded RNA, 1000-fold from the 0.5 M KCl wash of rabbit reticulocyte ribosomes. Deacylase I is a minor activity with an S20,w of 5.9, D20,w of 4.9 and Mr of 110 000, while deacylase II is the major activity with an S20,w of 3.3, D20,w of 7.1 and Mr of 43 000. Both convert crude reticulocyte or pure yeast, wheat germ, and E. coli [35S]Met-tRNAf to [35S]methionine and tRNAfMet and have no effect on reticulocyte [35S]fMet-tRNAf, [3H]Ala-tRNA or [3H]Lys-tRNA. However, while deacylase I has similar activity throughout the pH range of 6.1-8.1, deacylase II has a sharp pH optimum at 7.9 and is almost completely inactive at 6.1. In addition, deacylase II shows a much greater affinity for pure Met-tRNAf than deacylase I (Km of 1.5-3 nM vs. 100 nM), and, while deacylase II is selectively inhibited by tRNAfMet, deacylase I is inhibited similarly by any added tRNA.

Acyltransferases↗
PubMed1984

Isoleucyl initiator tRNA does not initiate eucaryotic protein synthesis.

Initiator tRNA from yeast (tRNAMeti) was quantitatively misaminoacylated with L-isoleucine using isoleucyl-tRNA synthetase from Escherichia coli. Surprisingly the misaminoacylated Ile-tRNAMeti neither participates in nor inhibits the initiation of globin synthesis in a rabbit reticulocyte lysate, whereas Met-tRNAMeti readily initiates protein synthesis in the same system. The incompetent behavior of Ile-tRNAMeti may be related to the observation that in vitro it does not form a stable complex with eucaryotic initiation factor 2 (eIF-2) and GTP, under conditions which lead to a stable eIF-2 X GTP X Met-tRNAMeti ternary complex. This indicates that eIF-2 can discriminate between the side chains of the aminoacyl adducts of the tRNAMeti during ternary complex formation, the first essential step in initiation of eucaryotic protein synthesis.

Animals↗
PubMed1984

[Occurrence and analysis of the mycotoxin emodin].

Besides other mould species, Aspergillus wentii Wehmer is assumed to form the hydroxyanthraquinone derivative emodin which has toxic and gene mutagenic properties. As a pectinase producer this fungus is used for the industrial isolation of pectinolytic enzymes for the food industry so that a contamination of such preparations by emodin cannot be excluded. However, preliminary thin-layer chromatographic studies of extracts of the corresponding pectinolytic enzyme preparations and Aspergillus wentii Wehmer did not point to a detectable toxin formation or contamination (the limit of detection lay at 5 mg emodin/kg substrate or 0.3 mg emodin/kg enzyme).

Animals↗