Biomedical subjects

P Salinas

Publications and source records attributed to P Salinas.

At least 19 recordsLinked to original sources

PubMed2004

An immunocytochemical mapping of methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem.

Using an indirect immunoperoxidase technique, we studied the distribution of immunoreactive fibers and cell bodies containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the adult human brainstem. Immunoreactive cell bodies were found in the reticular formation of the medulla oblongata (in which we observed the highest density of immunoreactive cell bodies) and the pons, the solitary nucleus, the hypoglossal nucleus, the medial and spinal vestibular nuclei, the lateral cuneate nucleus, the nucleus prepositus, the central gray of the pons and mesencephalon, the central and pericentral nuclei of the inferior colliculus, the superior colliculus, ventral to the superior olive and in the midline region of the pons and mesencephalon. The highest density of immunoreactive fibers containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) was found in the spinal trigeminal nucleus, the central gray and the reticular formation of the medulla oblongata, pons and mesencephalon, the solitary nucleus, the spinal vestibular nucleus, the dorsal accessory olivary nucleus, the raphe obscurus, the substantia nigra and in the interpeduncular nucleus. The widespread distribution of immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) in the human brainstem indicates that this neuropeptide might be involved in several physiological mechanisms, acting as a neurotransmitter and/or neuromodulator.

Aged↗

PubMed2003

Identification and analysis of Escherichia coli proteins that interact with the histidine kinase NtrB in a yeast two-hybrid system.

In this work we used the yeast two-hybrid (Y2H) system to deepen our understanding of protein-protein interactions that are involved in the nitrogen regulatory network in Escherichia coli. Three different genes, encoding GlnB, GlnK and AspA, respectively, were found among 64 positive clones identified from E. coli Sau3AI Y2H libraries using the nitrogen regulator NtrB as bait. Structural and functional analysis of the prey clones provided information on library features and the degree of saturation achieved in the screens. Further analysis revealed that the C-terminal kinase domain of NtrB is required for the interaction with GlnK, while AspA(91-312) interacts specifically with the conserved histidine phosphotransfer domain of NtrB, thus providing additional evidence for the involvement of the conserved transmitter module of the histidine kinase NtrB in input sensory functions.

Escherichia coli↗

PubMed2003

Clinical graft evolution of lymphocytes, polymorphonuclear cells, and antigen expression in tubular renal cells in the urine sediment of 20 renal allograft recipients.

Urinary samples from 20 kidney transplant recipients were studied to determine the cellular composition of the sediments using an immunocytological (IC) technique. The expression of HLA class I (A, B, C) and class II (DR, DQ, DP), CD2, CD3, CD4, CD8, and interleukin (IL)-2 receptor (IL-2R) on lymphocytes was assessed using a panel of monoclonal antibodies. The results were correlated with graft function and with the number of episodes of acute renal graft rejection (AR) during a period of 6 months posttransplantation. The cellular infiltration of lymphocytes (LC) and polymorphonuclear cells (PMNC) also was studied using a standard cytology (SC) technique. During this period, 17 of 30 episodes of graft dysfunction due to AR occurred in 12 patients: 8 to acute tubular necrosis (ATN) (n = 8); 4 to cyclosporine (CsA) toxicity (n = 4) and 1 to amphotericin toxicity (n = 1). The diagnosis of AR was made clinically by 3 independent observers, using biopsy in some cases. The immunocytology showed a significantly increased expression of HLA-DR, DO, and DP namely, greater than 20% positivity in 10% of samples on the tubular epithelial cells (TEC) of patients presenting with versus without AR (P < or =.001). In addition, a high correlation was observed between the expression of IL-2R and the presence of AR (p < or =.002). The standard cytology results showed a significantly increased percentage of LC and decreased percentage of PMNCs in samples obtained 2 days prior to the clinical manifestations of patients who developed AR (P =.001). A greater level of expression of antigen determinants was observed prior to AR. These results suggest that immunocytology of urinary sediments, which is a noninvasive technique, has enormous clinical potential for the differential diagnosis of AR, ATN, and CsA toxicity. In our study, the use of HLA class IL-specific monoclonal antibodies (Abs) gave a 100% specificity, 95% sensitivity, and 95% predictability. Although our results also indicate a potential value in the increased IL-2R expression, these findings must be confirmed by further studies. Furthermore, the combination of both immunologic and SC techniques in urinary sediments allows early detection of AR and is cost effective and simple features that could be used routinely for follow-up of renal transplant recipients.

Adult↗

PubMed2001

Two-hybrid analysis of domain interactions involving NtrB and NtrC two-component regulators.

Signal transduction by two-component regulatory systems involves phosphorylation of the receiver domain of a response regulator by the transmitter domain of the cognate histidine kinase. In the NtrBC system, phosphorylation of NtrC by NtrB results in transcriptional activation of nitrogen-regulated genes. We have used the yeast two-hybrid system to probe interactions between domains of the NtrB and NtrC proteins from Klebsiella pneumoniae. We constructed fusions from each of a series of proteins or protein domains to the activation and the DNA-binding domains of GAL4 and analysed expression of GAL1:lacZ and GAL1:HIS3 reporters in yeast. The DNA-binding domain of NtrC and the so-called sensor domain of NtrB appeared to provide the major determinants for dimerization of the fusion proteins. A strong and specific interaction was also shown between NtrB and NtrC, localized to the HN region of the NtrB transmitter module and to the NtrC receiver domain, whereas other domains of these proteins do not appear to contribute to the recognition specificity. The results presented here indicate that communication between two-component partners also involves protein-protein interactions that can be detected in vivo, suggesting that the yeast two-hybrid system is a powerful genetic tool for identifying functional partners of prokaryotic signal transduction pathways.

Bacterial Proteins↗

PubMed2001

Treatment of Trypanosoma cruzi-infected children with nifurtimox: a 3 year follow-up by PCR.

Patients suffering from Chagas' disease, as determined by positive serological results, were tested for further evidence of Trypanosoma cruzi infection by xenodiagnosis and PCR. The patients included 67 children aged from 0 to 10 years and 75 adults. All children were positive by PCR on their pre-therapy sample, while only 69% of the seropositive adults and none of the 78 seronegative control adults were PCR positive. Xenodiagnosis was positive in 79% of the children, but only in 21% of the adults. A group of 66 children was treated with nifurtimox, and followed up every 3 months during the first year and every 6 months during the second and third year post-therapy, by PCR, xenodiagnosis and serology. We concluded that PCR was the most effective test to monitor children for 3 years post-chemotherapy, when all the cases converted from positive to negative. Conventional serology, however, remained positive after that period in most cases. In contrast, conversion to negative xenodiagnosis occurred very early after treatment.

Adult↗

PubMed2001

Cloning and characterization of the cDNA coding for the catalytic alpha subunit of CK2 from tobacco.

We have previously reported the participation of the protein kinase CK2 in the mechanism by which salicylic acid activates transcription of genes, such as those coding for glutathion S-transferases, in tobacco. With the purpose of further studying the participation of CK2 in this signal transduction pathway, we isolated and sequenced the cDNA from the NtCK2A gene, coding for the catalytic alpha subunit of CK2 from tobacco. The NtCK2A cDNA was isolated by screening of a tobacco cDNA library with a heterologous probe from Arabidopsis thaliana, followed by 3' RACE to obtain the 3' region. Sequence analysis of the NtCK2A cDNA showed a high level of identity between this CK2alpha protein sequence and the corresponding sequences of other plant species such as Arabidopsis and maize (92-95% identity), or those of animal species such as human and Xenopus laevis (75% identity). The expression of the NtCK2A gene in different tissues from tobacco plants was analyzed by Northern blot. High levels of expression of this gene were observed in proliferating tissues such as shoot and root apical meristems. A recombinant CK2alpha protein was obtained after expression of the NtCK2A cDNA in Escherichia coli. The ability of this recombinant CK2alpha subunit to phosphorylate casein was inhibited by heparin and stimulated by the CK2beta subunit from Xenopus laevis.

Amino Acid Sequence↗

PubMed2000

Ultrastructural evidence of the protective effect of Na+/H+ exchange inhibition on the in vitro damage induced by ischaemia reperfusion in the interventricular septum of the rabbit heart.

We investigated the effects of the Na+/H+ antiporter inhibitor, dimethylamiloride, on myocardial injury after 1 h global ischaemia and 30 min. reperfusion in the isolated arterially perfused interventricular septum of the rabbit heart. After ischaemia and reperfusion challenge, dimethylamiloride significantly increased the recovery of developed tension in a dose-dependent manner, and significantly decreased the maximal increase in resting tension. Ultrastructural analysis of myocytes submitted to the experimental in vitro model supported functional maintenance of physiologically-like conditions. Where myocardial portions were submitted to ischaemic conditions and reperfusion, myocyte cell damage reached usual characteristics of infarct-like induced lesions. Intracellular oedema, severe disruption of myofibrils with loss of muscle striation and both swelling and fragmentation of mitochondria were the main characteristics observed. Dimethylamiloride treatment clearly modifies ultrastructural findings towards the normalization of cell shape and structure, only a slight-middle intracellular oedema and contraction bands were found. On the basis of the present results, we suggest that the protective effects exhibited by dimethylamiloride on the ischaemic myocardium are compatible with its Na+/H+ antiporter inhibition properties, they diminish Na+ accumulation and then either Ca2+ overload or non-exocytotic noradrenaline release during the ischaemia and reperfusion challenge.

Amiloride↗

PubMed1997

Cat carotid body chemosensory responses to non-hypoxic stimuli are inhibited by sodium nitroprusside in situ and in vitro.

We studied the effects of sodium nitroprusside, a nitric oxide donor, on the chemosensory responses to cyanide and nicotine in the cat carotid body. In situ, sodium nitroprusside infusion reduced the cyanide-evoked responses in a dose-dependent manner. In vitro, Tyrode containing nitroprusside reversibly reduced the cyanide- (by 59%) and nicotine-induced (by 45%) chemosensory responses. The present results suggest that chemosensory responses induced by cyanide and nicotine are reduced by increased nitric oxide content, similarly to the hypoxic chemosensory responses.

Animals↗

PubMed1996

[Renal transplantation in patients with neurogenic bladder].

BACKGROUND: Renal transplantation can be done in patients with neurogenic bladder and clean intermittent self catheterization maintains renal function AIM: To retrospective assess the results of renal transplantation in patients with neurogenic bladder. PATIENTS AND METHODS: The medical records of seven patients aged 10 to 22 years old (3 female) followed during 7 to 32 months were reviewed. All patients had urinary tract infection, prior to transplantation, were instructed on self catheterization and received tri-associated immunosuppression. RESULTS: Grafts came from alive related donors in 5 patients and from cadavers in two. Prior to transplantation, three patients were subjected to nephrectomy and three to bladder enlargement, leaving a pigtail catheter. After transplantation, one lymphocele was drained, one uretherostomy due to an impacted lithiasis and one nephrectomy plus vesical enlargement due to intravesical pressures over 40 cm H2O, were done. One uretheral stricture was treated with dilatation. Seven episodes of pyelonephritis, 19 urinary tract infections and 77 asymptomatic bacteriurias were documented. Serum creatinine at the end of follow up ranged from 0.7 to 2.1 mg/dl. There were 0.7 acute rejection episodes per patient and all grafts survived. CONCLUSIONS: Renal transplantation in patients with neurogenic bladder is feasible, performing a vesical enlargement. There is however a high frequency of infectious episodes.

Acute Disease↗

PubMed1996

[Medullary cancer of the thyroid. Experience at the Hospital de Valdivia].

BACKGROUND: Medullary carcinoma of the thyroid is an infrequent type of thyroid tumor. AIM: To retrospectively study all cases of medullary carcinoma of the thyroid diagnosed at a regional hospital. PATIENTS AND METHODS: The charts and pathological studies of eight patients with medullary carcinoma of the thyroid, among 75 with thyroidal cancer, were reviewed. RESULTS: Solitary nodules were the presenting sign in seven patients and cachexia in one. Five patients were subjected to total thyroidectomy, five to cervical lymph node dissection and four to complementary radiotherapy. Pathological diagnosis was made with the surgical piece in seven patients and by aspiration cytology in one. Five of the eight patients are alive after 50 months of follow up as a mean, one patient with bone metastasis. CONCLUSIONS: The small sample size precludes conclusions on the prognosis and treatment of the disease.

Adolescent↗

PubMed1995

Lack of platelet-activating factor release on acute myocardial ischemia in the isolated interventricular septum of rabbit heart.

The effects of platelet-activating factor (PAF) on myocardial injury after 1 h global ischemia-30 min reperfusion were investigated in isolated arterially perfused interventricular septum of rabbit heart. PAF did not significantly affect developed tension, +/- dT/dtmax, resting tension and the times of active state in non-ischemic septa. The recovery of developed tension was significantly reduced by PAF (100 nM), after an ischemia-reperfusion challenge, from the control value of 20.9 +/- 3.5% to 10.5 +/- 1.8%, without a change in the resting tension (15.7 +/- 2.8 vs. 15.6 +/- 1.3 g). BN 52021 (20 microM), alone did not modify either parameter of ischemic damage, but antagonized the aggravating effect of PAF. Evidence of PAF activity was not found in any of the samples of the effluent perfusate obtained from ischemic control experiments. On the basis of the present results, we suggest a direct role for PAF in aggravating the myocardial damage induced by ischemia, and discard heart cells as the source of PAF in this state.

Acute Disease↗

PubMed1995

Infusional chemotherapy (EPOCH) in patients with refractory or relapsed lymphoma.

Seventeen patients with refractory (7 cases) or relapsed (10 cases) lymphoma were treated with a continuous infusion of etoposide, vincristine, and doxorubicin, in addition to cyclophosphamide (bolus) and prednisone (regimen EPOCH). Six patients (4 with Hodgkin's disease) achieved a complete response (CR) (35%; 95% CI: 14-62%). However, 5 of 6 patients had achieved a CR with their initial therapy. Myelosuppression was the most serious effect (29% of patients with grade IV leukopenia after the first course). There were two treatment-related deaths. Doses were lower than originally reported (median: 68%). Infusional therapy with EPOCH is an active regimen in these heavily pretreated patients, particularly in relapsed Hodgkin's disease. It seems a useful protocol to prove chemosensitivity before bone marrow transplantation. However, the true role of infusional treatment has to be determined in clinical trials.

Adult↗

PubMed1995

[Parasitic and viral marker detection in pregnant adolescents and their newborn infants at risk].

We have investigated the prevalence of antibodies against Toxoplasma gondii, Trypanosoma cruzzi, Hepatitis B virus, cytomegalovirus, rubella virus, and human immunodeficiency virus in 139 adolescent pregnant women and in their high risk newborn children. The methods employed were the Sabin and Feldman reaction, complement fixation reaction, ELISA, and xenodiagnostic 30.9% of the pregnant group were seropositive for T. gondii, both mothers and newborns were IgM-negative. Two mothers (1.4%) presented anti T. cruzii antibodies, and one newborn child had circulating parasites. Related to the virological studies, 93.5% of the population were anti CMV antibodies positive and all their newborns were IgM (-) 90.6% of the adolescents were rubella positive and one was seropositive to VIH. We conclude that the prevalence found in this group of adolescent pregnant women are not significantly different to the one reported for the general pregnant women population.

Adolescent↗

PubMed1995

[Breast cancer in males. Report of 4 cases].

Breast cancer is infrequent in men. We report four men with breast cancer seen at a surgical service in Valdivia. Their presentation form, histological diagnosis and evolution are described. An updated revision of the literature is also presented.

Aged↗

PubMed1994

[Health education for mothers in the catchment area of the El Llano ambulatory center, Merida, Venezuela].

OBJECTIVE: To determine whether it is possible to achieve substantial changes in mother's knowledge and attitude, with respect to breast feeding, to feeding during the first year of life, to immunisation and other aspects that have to do with the normal growth and overall development of the child. DESIGN: Controlled, non-random, forward-looking study. SETTING: Primary Health Care. PATIENTS AND OTHER PARTICIPANTS: Study group of 20 mothers, and control group of 17 mothers. INTERVENTIONS: Monthly meetings were held with the study group for 7 months, in which they were given leaflets and talks on health education, with the respective questionnaires before and after the talks. The same questionnaires were given to the control group, when their children were a year old. MEASUREMENTS AND MAIN RESULTS: All the children of the mothers in the study group were having their children at the right time, compared with 70.6% of those in the control group, a statistically very significant result (chi 2 = 6.8 p < 0.01). The study group gave correct answers 85% out of total, compared with the control group's 37.5%, which is statistically significant (chi 2 = 8.6 p < 0.01). CONCLUSIONS: There was a significant change of attitude with regard to immunisation and feeding in the first year of life and a change in knowledge regarding breast feeding, immunisation and other aspects, in the study group as compared to the control group.

Ambulatory Care↗

PubMed1994

Isolation and characterization of a mouse homolog of the Drosophila segment polarity gene dishevelled.

In the Drosophila embryo dishevelled (dsh) function is required by target cells in order to respond to wingless (wg, the homolog of Wnt-1), demonstrating a role for dsh in Wnt signal transduction. We have isolated a mouse homolog of the Drosophila dsh segment polarity gene. The 695-amino-acid protein encoded by the mouse dishevelled gene (Dvl-1) shares 50% identity (65% similarity) with dsh. Similarity searches of protein and DNA data bases revealed that Dvl-1 encodes an otherwise novel polypeptide. While no functional motifs were identified, one region of Dvl-1 was found to be similar to a domain of discs large-1 (dlg), a Drosophila tumor suppressor gene. In the embryo, Dvl-1 is expressed in most tissues, with uniformly high levels in the central nervous system. From 7.5 days postcoitum Dvl-1 is expressed throughout the developing brain and spinal cord, including those regions expressing Wnt-1 and En. Expression of Dvl-1 in adult mice was found to be widespread, with brain and testis exhibiting the highest levels. The majority of Dvl-1 expression in the adult cerebellum is in the granular cell layer, similar to the pattern seen for engrailed-2 (En-2). Throughout postnatal development of the brain Dvl-1 is highly expressed in areas of high neuronal cell density.

Adaptor Proteins, Signal Transducing↗

PubMed1993

Defining critical residues in the epitope for a HIV-neutralizing monoclonal antibody using phage display and peptide array technologies.

A peptide display library [Scott and Smith, Science 249 (1990) 386-390] was constructed that expressed 1.5 x 10(8) unique 20-amino-acid (aa) peptides fused to the N-terminus of the pIII coat protein of filamentous phage fd. This phage display library (PDL-20) was prepared using a degenerate oligodeoxyribonucleotide designed to minimize bias towards most aa. Characterization of the PDL-20 showed that all aa were present at the expected frequency and that there was no positional bias. Screening of this library with a HIV-1 isotype MN envelope reactive monoclonal antibody (mAb 58.2) using two different panning procedures showed that the biopanning technique was sensitive to one phage in 10(8). Analysis of peptide sequences from panning the mAb identified a core antibody recognition sequence of four aa residues (GPGR) and two preferred flanking residues on either side. This epitope occurred at various locations within the random aa segment demonstrating an absence of positional or nearest neighbor effects. Parallel panning experiments using an array of 266 synthetic peptides identified an epitope similar to that defined by the phage display library.

Amino Acid Sequence↗

PubMed1992

GABAA receptors in the amygdala: role in feeding in fasted and satiated rats.

The purpose of this study was to clarify further the site of action in the amygdala as well as functional characteristics of feeding in response to two GABA receptor agonists. Guide cannulae for microinjection were implanted stereotaxically in the rat just above the central nucleus of the amygdala (CNA). Microinjections of 0.05, 0.25, 0.5 or 1.0 nmol muscimol, a GABAA-selective receptor agonist, produced a dose- and time-dependent decrease of food intake in both the satiated and fasted rat. The bilateral injection of muscimol into the amygdala was more effective than a unilateral injection during the first 2 h, although the overall effects were similar. Microinjection of 0.1 nmol bicuculline methiodide, a GABAA receptor antagonist, into the CNA significantly blocked this inhibitory effect of 0.05 and 0.5 nmol muscimol again in both the satiated and fasted rat. Doses of 0.05, 0.5, 5.0 and 10.0 nmol of the selective GABAB agonist, baclofen, injected into homologous sites in the CNA did not alter food intake. These findings support the viewpoint that the amygdala and its central nucleus comprise a pivotal region involved in the mechanisms underlying the control of feeding behavior. Further, it is envisaged that hypophagic or anorexic responses are induced through the activation of GABAA receptors by the presynaptic release of GABA from neurons which form a component of the anatomical system for hunger and satiety.

Amygdala↗