PubMed Health⌕ Search

Biomedical subjects

C Peña

Publications and source records attributed to C Peña.

At least 91 records · Page 5Linked to original sources
PubMed1993

Inhibition of volume regulation and efflux of osmoregulatory amino acids by blockers of Cl- transport in cultured astrocytes.

Regulatory volume decrease (RVD) in astrocytes was inhibited by the Cl- exchanger blockers 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), dipyridamole and niflumic acid but not by the Cl- channel inhibitors diphenylamine-2-carboxylate (DPC) and anthracene-9-carboxylate (9-AC). The volume activated efflux of [3H]taurine and [3H]D-aspartate (as marker for glutamate) was similarly affected by these compounds. However, neither RVD nor osmolyte fluxes were significantly reduced by removal of external Cl-, suggesting that an anion exchanger activity is not required for the volume regulatory process. Alternatively, these results suggest that the anion exchanger molecule may function as an unidirectional Cl- channel possibly permeable also to amino acids.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

[Endocarditis due to penicillin-sensitive and -resistant pneumococci: the current perspectives on the disease].

BACKGROUND: To evaluate the clinic characteristics and therapeutic aspects of endocarditis by Streptococcus pneumoniae sensitive and resistant to penicillin. METHODS: Twelve cases of pneumococcal endocarditis evaluated in 4 Spanish hospitals over the last 10 years were studied, analyzing their clinical characteristics and the existence of resistance to penicillin. The features were compared with a series of 98 cases found in a review of the literature. RESULTS: All the patients were males, most being alcoholics. The course of the disease was acute (2 weeks) in all the cases and evolved with great aggressivity: cardiac failure (9 patients), myocardial abscess (7 patients), multiple arterial embolisms (5 patients), septic arthritis (4 patients). Three patients had simultaneous pneumococcal meningitis but only one had pneumonia. The valve most affected was the aortic (9 cases). Three cases were due to strains of Streptococcus pneumoniae with moderate resistance to penicillin (CMI 0.5-1 micrograms/ml). Global mortality was 42%. All the patients receiving inadequate antibiotic treatment died. Vancomycin and cefotaxime appear to be effective in the treatment of cases produced by strains of pneumococcus with intermediate sensitivity to penicillin. There were no apparent differences in mortality between the cases of endocarditis by pneumococcus sensitive or moderately resistant to penicillin. CONCLUSIONS: Pneumococcal endocarditis continues to condition a high mortality similar to that produced in previously made series. The classic relation with meningitis and pneumonia is infrequent today. The appearance of strains resistant to penicillin may increase the incidence of this infection and further worsen prognosis.

Adult↗
PubMed1993

Heterologous humoral immune response in patients treated with human growth hormone from different sources.

The existence of homologous anti-human growth hormone (anti-hGH) and heterologous anti-bovine growth hormone (anti-bGH) humoral immune responses in hypopituitary patients under hGH therapy has been reported previously. In order to study the influence of the hormone source, both responses were compared by radiobinding assays performed with [125I]hGH or [125I]bGH as tracers. Fifty-seven hypopituitary patients treated with extractive hGH, recombinant methionyl hGH or authentic recombinant hGH were studied. A very low incidence of heterologous antibodies was found in patients under recombinant hGH therapy, contrary to the high incidence observed in patients treated with extractive hGH preparations. In addition, immunochemical studies performed with a synthetic peptide (hGH 44-128) indicated that this peptide exhibited, in the anti-bGH/[125]bGH radioimmunoassay system, higher reactivity than the native hGH, suggesting that such a fragment resembled an altered conformation of the hormone. The high heterologous response elicited only by the extractive hGH along with the behaviour of the hGH 44-128 fragment supports the fact that the extraction and purification procedures in extractive preparations may alter slightly the structure of the hGH molecule and trigger a heterologous immune response.

Adolescent↗
PubMed1993

An alpha D-globin fragment from Triatoma infestans hindgut stimulates Trypanosoma cruzi adenylyl cyclase and promotes metacyclogenesis.

A peptide from hindguts of the Triatoma infestans, the hematophagous Chagas' insect vector, activates adenylyl cyclase activity in Trypanosoma cruzi epimastigote membranes and stimulates the in vitro differentiation of epimastigotes (proliferative and non-infectious forms) to metacyclic trypomastigotes (non-proliferative and infectious forms). The peptide was purified from hindguts of insects fed two days before with chicken blood. After purification, the peptide showed upon SDS-PAGE a single band of about 10 kDa. The sequence for 20 residues of the amino terminus of this peptide was: H2N-Met-Leu-Thr-Ala-Glu-Asp-Lys-Lys-Leu-Ile-Gln-Gln-Ala-Trp-Glu-Lys-Ala- Ala-Ser-His. This sequence corresponds to the amino terminus of chicken alpha D-globin. A synthetic peptide with the sequence of the 40 amino acids corresponding to the amino terminus of alpha D-globin, also stimulated T. cruzi adenylyl cyclase activity and promoted metacyclogenesis.

Adenylyl Cyclases↗
PubMed1993

[Nosocomial bacteremia caused by Enterobacter spp.: epidemiology and prognostic factors].

BACKGROUND: The aim of this study was to establish the clinical and epidemiologic features of nosocomial bacteremia by Enterobacter spp. and to analyse its prognostic factors. METHODS: A prospective study of the episodes of nosocomial bacteremia by Enterobacter spp. with clinical significance, detected in a third level university hospital from January 1984 to December 1990 was performed. RESULTS: During the study period, 226 episodes of bacteremia by Enterobacter spp., of which 184 (81%) were of nosocomial origin (8.1% of all the nosocomial bacteremias), while 14% were polymicrobial. An increasing trend was observed in the number of episodes (1984 vs 1990) from 0.9 vs 1.8 episodes per 1,000 admissions, respectively. The mean age was 57 years and the male/female relation was 2.4/1. The most frequent focus of origin was infection of the vascular catheter (43%), followed by intraabdominal catheter (21%), urinary tract (14%), and other foci (17%). Fifty-four percent of the patients had received antibiotics prior to the episode of bacteremia. Most of the cases were detected in the Intensive Care Units (ICU) (41%) and in the gastrointestinal surgery area (24%). Global mortality was 23%. Logistic regression analysis selected an entry site other than infection of the vascular catheter (odds ratio 6.1; CI [95%)] 2.0-18.4), shock (odds ratio, 6; CI [95%], 1.6-21.9) and immunosuppressive treatment (odds ratio, 5; CI [95%], 1.5-16.2) as independent variables of bad prognosis. CONCLUSIONS: Enterobacter spp. is an important nosocomial pathogen taking fourth place in the ranking of nosocomial bacteremia by gram negative bacilli. It predominantly affects a population of patients admitted in the ICU and surgery. The intravascular catheter is a frequent entry site for nosocomial bacteremia by Enterobacter spp.

Adult↗
PubMed1992

Benzodiazepines in the brain. Their origin and possible biological roles.

Great progress has been made in the last 5 yr in demonstrating the presence of benzodiazepines (BDZs) in mammalian tissues, in beginning studies on the origin of these natural compounds, and in elucidating their possible biological roles. Many unanswered questions remain regarding the sources and biosynthetic pathways responsible for the presence of BDZs in brain and their different physiological and/or biochemical actions. This essay will focus on recent findings supporting that: (1) BDZs are of natural origin; (2) mammalian brain contains BDZs in concentrations ranging between 5 x 10(-10)-10(-8) M; (3) dietary source of BDZs might be a plausible explanation for their occurrence in animal tissues, including man; (4) the formation of BDZ-like molecules in brain is a possibility, experimentally supported; (5) BDZ-like molecules including diazepam and N-desmethyldiazepam are elevated in hepatic encephalopathy; and (6) natural BDZs in the brain are involved in the modulation of memory processes. Future studies using the full range of biochemical, physiological, behavioral, and molecular biological techniques available to the neuroscientist will hopefully continue to yield exciting and new information concerning the biological roles that BDZs might play in the normal and pathological functioning of the brain.

Animals↗
PubMed1992

Two polypeptides from Dendroaspis angusticeps venom selectively inhibit the binding of central muscarinic cholinergic receptor ligands.

Two new polypeptides were isolated and purified from the venom of the snake Dendroaspis angusticeps, which also contains other neuroactive peptides such as Dendrotoxins and Fasciculins. The amino acid composition of the peptides was determined and the first 10 amino acids from the MTX2 N-terminal fragment were sequenced. The so-called muscarinic toxins (MTX1 and MTX2) have been shown to inhibit the specific binding of [3H]QNB (0.15 nM), [3H]PZ (2.5 nM) and [3H]oxoM (2 nM) to bovine cerebral cortex membranes by 60, 88 and 82% respectively. In contrast, they caused only a 30% blockade of the [3H]QNB specific binding to similar membrane preparations from the brainstem. The Hill number for the [3H]PZ binding inhibition by the putative muscarinic toxin MTX2 was 0.95 suggesting homogeneity in the behaviour of the sites involved. The data from [3H]oxoM binding gave a Hill number of 0.83. The decreases in the specific binding involved increases in KD for the three different ligands (8-fold for [3H]QNB, 4-fold for [3H]PZ and 3.5-fold for [3H]oxoM) without significant changes in Bmax, except for a slight decrease in the [3H]oxoM binding sites (-19%); such results suggest that there may be a competitive inhibition between the MTXs and these ligands. The Ki for MTX2/[3H]PZ was 22.58 +/- 3.52 nM; for MTX2/[3H]oxoM, 144.9 +/- 21.07 nM and for MTX2/[3H]QNB, 134.98 +/- 18.35 nM. The labelling of MTX2 with 125I allowed direct demonstration of specific and saturable binding to bovine cerebral cortex synaptosomal membranes. In conclusion, the results reported in this study strongly support the hypotheses that the two polypeptides isolated from D. angusticeps venom selectively inhibit specific ligand binding to central muscarinic receptors, in a competitive manner at least for the antagonist [3H]PZ and that the MTX2 specifically binds to a central site that is suggested to be a muscarinic receptor of the M1 subtype.

Amino Acids↗
PubMed1991

Formation of benzodiazepine-like molecules in rat brain.

The possible biosynthetic origin of benzodiazepine-like molecules was investigated in mammalian tissue. Rat brain homogenates or cortical slices incubated under physiological conditions showed a 4 to 7 fold increase in the content of BZD-like compounds as compared with control non incubated or boiled tissue. The quantitative analysis was performed by a radioimmunoassay with a specific monoclonal antibody. The active fraction eluting just before diazepam exhibited a Mr lower than 1300 and inhibited the [3H]flunitrazepam binding to the central benzodiazepine receptor. No activity was measured in the absence of tissue. These data suggest that under our experimental conditions, low molecular weight substances similar to benzodiazepines are formed in rat brain.

Animals↗
PubMed1991

Naturally occurring benzodiazepines in human milk.

The presence of benzodiazepine-like molecules was detected radioimmunologically in the plasma and milk of 12 women and in the plasma of 9 men. All subjects were non-users of benzodiazepines. The concentration of these biological materials expressed as diazepam equivalents per mL amounted to 2.54 +/- 0.74 ng in male plasma; to 2.20 +/- 0.35 ng in female plasma and to 1.91 +/- 0.54 ng in milk. Further investigation of the active compounds in milk permitted the unequivocal identification of diazepam, both free and bound to a presumably protein carrier and, at least, three more benzodiazepine-like molecules. Their origin either from dietary sources or as a result of endogenous biosynthesis is still unclear.

Benzodiazepines↗
PubMed1991

Psychiatric aspects of multiple sclerosis.

A consecutive sample of 50 patients with a diagnosis of definite multiple sclerosis was evaluated by means of the Clinical Interview Schedule (CIS) and other psychopathological instruments. A global prevalence of psychopathology of 54% was found, with the prevalence of depression being 22%. Moreover, 46% of the sample presented signs indicative of neuropsychological deterioration in the Benton Visual Retention Test. The association between the presence of psychopathology and the social and neurological characteristics of the sample was also investigated, with results of low significance.

Adolescent↗
PubMed1991

AIDS heterosexual predominance in the Dominican Republic.

AIDS surveillance data from the Dominican Republic are described for 1983-89. A positive serologic test for HIV was required, and standard clinical criteria were used for defining AIDS. There were 1,202 AIDS cases (820 men, 372 women, 10 of unknown gender) reported to the Ministry of Health, for a cumulative case rate of 17 per 100,000 persons. Rapid growth of the epidemic is noted, with 43% of the total cases reported in 1989. Heterosexual exposure accounts for 53% (593) of all cases, with a male-to-female ratio of 2.2:1, resembling a World Health Organization Pattern I/II country. Prevalence is highest in and surrounding the urbanized tourist areas of Santo Domingo and Puerto Plata and in districts with a high concentration of sugar plantation barracks, where laborers from Haiti and the Dominican Republic work and live. The distribution of AIDS cases is described by transmission exposure category, age, sex, year of diagnosis, and district. The National AIDS Surveillance Program can be improved by validation of exposure transmission categories through selected case investigation and by better reporting through training of health care providers. Surveillance data will assist in targeting future public health efforts to regions and persons at highest risk.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Chrysin (5,7-di-OH-flavone), a naturally-occurring ligand for benzodiazepine receptors, with anticonvulsant properties.

Chrysin (5,7-di-OH-flavone) was identified in Passiflora coerulea L., a plant used as a sedative in folkloric medicine. Chrysin was found to be a ligand for the benzodiazepine receptors, both central (Ki = 3 microM, competitive mechanism) and peripheral (Ki = 13 microM, mixed-type mechanism). Administered to mice by the intracerebroventricular route, chrysin was able to prevent the expression of tonic-clonic seizures induced by pentylenetertrazol. Ro 15-1788, a central benzodiazepine receptor antagonist, abolished this effect. In addition, all of the treated mice lose the normal righting reflex which suggests a myorelaxant action of the flavonoid. The presence in P. coerulea of benzodiazepine-like compounds was also confirmed.

Animals↗
PubMed1990

Mental health and medical consultation in primary care settings.

This paper examines the effect of psychiatric morbidity, as measured by the GHQ-60, on the probability of being in contact with a primary care physician, and the socio-demographic factors which influenced this effect. We found that the presence of psychiatric morbidity emerged as a major determinant of primary care utilization in both sexes, and about one-sixth of consultations in men and one-fifth of consultations in women could be attributed to it. Logistic modelling was used to investigate the joint effect on general practitioner consultation of psychiatric morbidity and seven socio-demographic variables. Sex, age, and psychiatric morbidity exerted independent, but not interactive, effects on consultation.

Adolescent↗
PubMed1990

Equine growth hormone. Detection of immunoreactive sequences using poly- and monoclonal antibodies.

The immunochemical behavior of several fragments of equine growth hormone (eGH) was examined using competitive binding assays with antibodies (Abs) to eGH obtained from different sources. Antigenicity was detected within the sequences 5-72 and 73-123 by rabbit Abs to eGH and by three mouse monoclonal antibodies (MAbs) produced by using bovine growth hormone as immunogen, but showing heteroclitic properties towards eGH. The polyclonal Abs to eGH also recognized as immunoreactive two smaller peptides corresponding to the amino acid residues 52-72 and 110-123. By contrast, the heteroclitic Abs to eGH developed by hypopituitary patients therapeutically injected with human growth hormone failed to react with any eGH-derived fragment. The rabbit polyclonal Abs and the mouse MAbs scarely discriminated between native and S-carbamidomethylated eGH, while the heteroclitic human Abs detected a clear difference between the native and the modified hormone.

Amino Acids↗
PubMed1989

Benzodiazepine-like molecules, as well as other ligands for the brain benzodiazepine receptors, are relatively common constituents of plants.

The presence of benzodiazepine (BZD)-like molecules as well as of other substances with affinity for the brain BZD-receptors was explored in eight non-flowering plants known to contain biflavonoids, three flowering plants used as sedatives in folkloric medicine and one plant extensively used in Argentina, Uruguay, Brazil and Paraguay as a tea substitute. All the plants examined contained substances which bound to the central BZD-receptors and the majority of them also had BZD-like compounds detected by their specific interaction with a monoclonal antibody against BZDs. In various cases this last type of compound was present in amounts which exceeded trace levels (0.5-1.0 ng/g). The biological or clinical significance for humans of all these substances should be explored.

Antibodies, Monoclonal↗