Search PubMed⌕ Search

Biomedical subjects

M Ortiz

Publications and source records attributed to M Ortiz.

At least 127 records · Page 7Linked to original sources
PubMed1990

Tumor necrosis factor production by Kupffer cells requires protein kinase C activation.

Tumor necrosis factor (TNF) has been proposed as a primary inflammatory mediator of septic shock. In vitro and in vivo studies indicate that endotoxin- or lipopolysaccharide (LPS)-activated macrophages are a principle source of TNF; however, membrane signal transduction and intracellular pathways by which LPS triggers TNF production in macrophages are unclear. Recent evidence indicates that specific protein phosphorylation via activation of protein kinase C (PKC) is an early, critical step in the signaling of macrophage TNF production by phorbol esters. We hypothesize that PKC activation is also required in LPS-signaled Kupffer cell (KC) TNF production. Murine KCs were obtained by liver perfusion and digestion and then stimulated with LPS (Escherichia coli O111:B4) or LPS in the presence of H-7, a selective PKC inhibitor. Conditioned media was collected at 3 hr for assay of TNF utilizing the L929 cytolysis bioassay standardized to murine-rTNF-alpha. We found that H-7 inhibited significantly LPS signaled TNF release at a concentration of 10 microM, while H-8 (a cyclic nucleotide specific inhibitor) had no effect. The effect of H-7 was dose dependent and present at varying concentrations of LPS. Down regulation of PKC activity by preincubation of KCs with phorbol myristate acetate (PMA, a direct activator of PKC) also resulted in significantly reduced TNF release after LPS stimulation. The inhibitor H-7 (10 microM) also significantly inhibited LPS signaled prostaglandin E2 release in Kupffer cells. Total and specific intracellular protein phosphorylation was determined by trichloroacetic acid precipitation and SDS-polyacrylamide gel electrophoresis after labeling stimulated Kupffer cells with 32Pi. Total protein phosphorylation was not significantly altered by LPS stimulation; however, autoradiograms from PMA- and LPS-stimulated KCs demonstrate enhanced phosphorylation of a 40-kDa protein (2.7 +/- 0.9-fold) and a 33-kDa protein (3.1 +/- 1.0-fold) which were inhibited by H-7. We conclude that activation of PKC and protein phosphorylation are required steps in the signal transduction pathway of LPS-stimulated TNF production in Kupffer cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Simple disturbance of the dam in the neonatal period can alter haloperidol-induced catalepsy in the adult offspring.

Three experiments were performed to determine whether apparently minimal disturbances of dams and litters would influence haloperidol-induced akinesia. In Experiment I, Long-Evans hooded rats (a) were left unmanipulated, (b) received nestcage relocation and observation, (c) received nestcage relocation/observation and maternal separation, or (d) received nestcage relocation/observation and pup handling. The male adult offspring received open-field testing and later received forepaw-on-dowel catalepsy testing following saline, morphine (20 mg/kg), or haloperidol (2 mg/kg). In Experiment II, hooded rats received (a) no manipulation, (b) nestcage relocation, (c) maternal separation, or (d) pup handling. At weaning, dams were tested in the open-field. Activity wheel locomotion of the offspring was assessed following saline or haloperidol for 3 days/week for 3 weeks; then, 5 and 7 days later, rats received haloperidol (0.5 mg/kg) and catalepsy testing. In both experiments, manipulations involving the dam reduced the offsprings' haloperidol-induced catalepsy, but, in Experiment II, a history of haloperidol administration distinguished between the effects of nestcage relocation and maternal separation. In Experiment III, Swiss albino mice received (a) no treatment, (b) nestcage relocation and maternal separation, (c) relocation/separation and mild cold stress of pups, (d) relocation/separation and pup handling, or (e) relocation/separation and severe cold stress of pups. Adult male mice received saline or haloperidol (2.5 mg/kg) and inclined grid catalepsy testing. Mice receiving relocation/separation and mice receiving relocation/separation and severe cold stress showed enhanced catalepsy versus control mice. Thus, it was concluded that seemingly innocuous events in infancy can influence the intensity of extrapyramidal side effects of neuroleptics in adulthood.

Animals↗
PubMed1990

Hepatic acute phase protein synthesis is indirectly regulated by tumor necrosis factor.

It has been proposed that tumor necrosis factor (TNF) is a direct regulator of postinjury hepatic protein synthesis. To test this hypothesis we investigated the total protein and specific acute phase protein synthesis response of murine hepatocytes to stimulation with mu-rTNF-alpha in vivo and in vitro. Total hepatocyte secretory protein synthesis was assessed by incorporation of [35-S] methionine into TCA-precipitated protein; and acute phase protein synthesis was assessed by induction of a 23-kD acute phase protein marker and by suppression of albumin synthesis determined by SDS-PAGE and autoradiography. We found that rTNF in vivo (8,000 units, IP injection) was associated with reduced total hepatocyte secretory protein synthesis (29 +/- 10%), increased synthesis of the 23-kD acute phase reactant (4.1 +/- 1.6-fold), and decreased albumin synthesis (0.68 +/- 0.2-fold) compared to saline-injected control animals. The in vitro stimulation of cultured murine hepatocytes directly with rTNF failed to demonstrate changes in total secretory protein synthesis or 23-kD protein; however, it did result in significant suppression of albumin synthesis (0.82 +/- 0.1-fold). In additional experiments, hepatocytes:nonparenchymal cell co-cultures stimulated with lipopolysaccharide (LPS) demonstrated protein synthesis changes similar to the in vivo TNF response including increased 23-kD protein and decreased albumin synthesis. These co-cultures demonstrated TNF production; however, addition of TNF antiserum during LPS stimulation had no effect on either 23-kD protein or albumin synthesis, despite the complete neutralization of TNF activity in the co-culture supernatants.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Proteins↗
PubMed1990

[Post-traumatic hemobilia caused by arteriobiliary fistula. A case report and review of the literature].

One new case of post-traumatic hematobilia due to an arteriobilary fistula is reported. This etiology is relatively rare, and its diagnosis is sometimes difficult if the three signs: pain, bleeding and jaundice are not observed. The most effective paraclinical examination still is selective arteriogrpahy, which makes the diagnosis possible, accurately locates the fistula and sometimes allows hyperselective embolization, as it did in this case. The use of embolization for the treatment of post-traumatic hematobilia due to an arteriobiliary fistula reduces operative mortality for this disease, which still has a poor prognosis.

Adult↗
PubMed1989

Kinetic diversity of Na+ channel bursts in frog skeletal muscle.

Individual Na+ channels of dissociated frog skeletal muscle cells at 10 degrees C fail to inactivate in 0.02% of depolarizing pulses, thus producing bursts of openings lasting hundreds of milliseconds. We present here a kinetic analysis of 87 such bursts that were recorded in multi-channel patches at four pulse potentials. We used standard dwell-time histograms as well as fluctuation analysis to analyze the gating kinetics of the bursting channels. Since each burst contained only 75-150 openings, detailed characterization of the kinetics from single bursts was not possible. Nevertheless, at this low kinetic resolution, the open and closed times could be well fitted by single exponentials (or Lorentzians for the power spectra). The best estimates of both the open and closed time constants produced by either technique were much more broadly dispersed then expected from experimental or analytical variability, with values varying by as much as an order of magnitude. Furthermore, the values of the open and closed time constants were not significantly correlated with one another from burst to burst. The bursts thus expressed diverse kinetic behaviors, all of which appear to be manifestations of a single type of Na+ channel. Although the opening and closing rates were dispersed, their average values were close to those of alpha m and 2 beta m derived from fits to the early transient Na+ currents over the same voltage range. We propose a model in which the channel has both primary states (e.g., open, closed, and inactivated), as well as "modes" that are associated with independent alterations in the rate constants for transition between each of these primary states.

Animals↗
PubMed1989

Vitamin and mineral supplementation practices of adults in seven western states.

Seven western states (Arizona, California, Idaho, Nevada, New Mexico, Oregon, and Wyoming) were surveyed in 1986 to determine the extent of vitamin/mineral supplementation and dosage levels of single supplements. Questionnaires were mailed to 3,500 individuals. A 57.8% response rate was obtained from the deliverable surveys, with a sample size of 1,730. The sample consisted of 54% women and 46% men and was predominantly white (88.9%). Fifty-four percent of the sample consumed some type of supplement; multiple vitamin/minerals were consumed with the greatest frequency. For single supplements, vitamin C was reported with the greatest frequency (23.1%), followed by some type of calcium supplement (22.5%) and vitamin E (11.1%). More than 80% of the vitamin C users indicated a dosage of 250 mg/day. Most respondents consumed calcium dosages of less than 1,000 mg/day. For vitamin E, 75% of the users consumed more than 200 IU/day. The data suggest that the potential for toxicity due to excess supplementation levels exists in the western states studied.

Adolescent↗
PubMed1988

Social factors influence haloperidol-induced catalepsy in rat.

This study employed manipulations which presumably influence social interactions in rats: (1) paired housing with a heavier conspecific and (2) exposure to the odors of other rats. The dependent variable was the akinetic state induced by haloperidol, a neuroleptic and dopamine antagonist. In Experiment 1, adult male Long-Evans hooded rats were matched by weight and caged alone or in pairs with one rat 30 g heavier than its cagemate. All rats received haloperidol (1.5 mg/kg) and catalepsy testing. Heavy rats showed more catalepsy than the lighter member of pairs or weight-matched, singly housed controls. In Experiment 2, adult male rats were left unrecaged or were recaged into cages with bedding recently soiled by females or other adult males. After haloperidol (1.0 mg/kg), the rats exposed to bedding soiled by other adult males showed more catalepsy than did the control groups. Thus, the results of both experiments indicated that social factors can influence the akinesia induced by dopamine antagonists.

Animals↗
PubMed1987

glnA mutations conferring resistance to methylammonium in Escherichia coli K12.

Cells of Escherichia coli K12 were sensitive to 100 mM-methylammonium when cultured under nitrogen limitation, and resistant when grown with an excess of either NH4Cl or glutamine. Glutamine synthetase activity was required for expression of the methylammonium-sensitive phenotype. Mutants were isolated which were resistant to 100 mM-methylammonium, even when grown under nitrogen limitation. P1 bacteriophage transduction and F' complementation analysis revealed that the resistance-conferring mutations mapped either inside the glnA structural gene and/or elsewhere in the E. coli chromosome. Glutamine synthetase was purified from the wild-type and from some of the mutant strains. Strains carrying glnA-linked mutations that were solely responsible for the methylammonium-resistant phenotype yielded an altered enzyme, which was less active biosynthetically with either ammonium or methylammonium as substrate. Sensitivity to methylammonium appeared to be due to synthesis of gamma-glutamylmethylamide by glutamine synthetase, which was synthesized poorly, if at all, by mutants carrying an altered glutamine synthetase enzyme.

Drug Resistance, Microbial↗
PubMed1987

[A case of chloroquine-resistant malaria of type R3 originating in Cameroon].

World areas with chloroquine-resistant falciparum malaria are progressively spreading, in Africa from East to West. We are reporting here a new case of resistance, grade III, from Cameroon, carried out in vitro by the WHO standard macrotest. Resistance is determined by the ability of trophozoites to develop into schizonts when therapeutic doses of chloroquine have been administered.

Africa, Western↗