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Biomedical subjects

M Alonso

Publications and source records attributed to M Alonso.

At least 19 recordsLinked to original sources
PubMed1998

High-affinity binding sites to the vitamin D receptor DNA binding domain in the human growth hormone promoter.

The regulation of the human growth hormone (hGH) gene by 1,25(OH)2D3 is a mechanism which is poorly understood. The objective of this study was to investigate whether the hGH gene has DNA recognition elements for the DNA binding domain of the vitamin D receptor. Using gel retardation assays and footprinting techniques, two high-affinity binding sites, denominated F1 and F2, were identified in the 5'-flanking sequence of hGH. The distal site, F1, located at -59 bp is made up of an imperfect direct repeat separated by 3 bp and showed a high degree of similarity with other known vitamin D response elements (VDREs). The proximal site, F2, located at -36 bp showed a single 7-bp sequence, which is different from other known VDREs. The location of both sites (F1 near the GHF-1/Pit-1 response element, F2 contacting the TATA box) suggests that the vitamin D receptor by itself or through interference with other transcriptional factors may modulate hGH expression.

Binding Sites↗
PubMed1998

Muscarinic toxin selective for m4 receptors impairs memory in the rat.

The selectivity of the muscarinic toxin MT3 from green mamba snake venom was corroborated by inhibition of the binding of [3H]NMS, a classical muscarinic radioligand, to native and cloned muscarinic receptors, showing 214-fold higher affinity for m4 than for m1 subtype, without significant binding to the others. The highest concentrations of MT3 sites (putative m4 receptors) in the rat brain were found in striatum and olfactory tubercle, intermediate concentration in dentate gyrus and CA1, and lower but still conspicuous levels in CA3 and frontal cortex. MT3 caused retrograde amnesia of an inhibitory avoidance task, when injected into the dorsal hippocampus of rats after training, suggesting a positive role of these MT3 sensitive sites, which are probably m4 muscarinic receptors, in memory consolidation of this task.

Animals↗
PubMed1998

Local increase level of chondroitin sulfate induces changes in the rhombencephalic neural crest migration.

Numerous studies suggest that chondroitin sulfate proteoglycan (CSPG) inhibits neural crest cells (NCC) migration at the trunk level. However, its action on the cephalic neural crest is not clear. To determine this action, we have microinjected 0.5 nl of different concentrations of chondroitin sulfate (CS) at the anterior rhombencephalon level in 9 stage chick embryos, as well as subgerminally administering beta-D-xyloside to 8 stage chick embryos. Beta-D-xyloside disrupts CSPG synthesis, producing an increase in CS free chains in several embryonal anlages. Chondroitin sulfate microinjected embryos and beta-D xyloside treated embryos were reincubated until attaining 12 stage. Results obtained for both experimental groups were similar. Immunoreactivity with HNK-1 antibody revealed that NCC did not migrate, remaining near the rhombencephalon dorsal wall; in addition, several NCC did not separate from the neural fold, becoming invaginated towards the rhombencephalon cavity. Our findings indicate that an increase in CS free chains in cephalic neural crest migratory routes not only disrupts their migration, but also impedes delamination and detachment of the rhombencephalic neuroepithelium NCC. These data suggest that the inhibitory action upon the neural crest migration attributed to CSPG may rest on its glycosaminoglycan (GAG). We cannot, however, rule out the possibility that increases in other GAGs apart from CS, may produce similar effects on neural crest migration.

Animals↗
PubMed1998

[Wiktor coronary stent for elective placement with an antiaggregation regimen. WINE study. WINE Group Study].

INTRODUCTION AND OBJECTIVES: The main problems associated with coronary stent implantation are subacute thrombosis and vascular and hemorrhagic complications due to the intensive anticoagulant regime. We studied the complications and the six-month restenosis rate after the elective implantation of a Wiktor stent in patients treated only with antiplatelet drugs. PATIENTS AND METHODS: The WINE study is an open, observational, multicenter study that included 368 patients (380 lesions) from 11 Spanish hospitals. All patients were treated with aspirin (125-325 mg/day) and ticlopidine (250 mg/12 h for 4 weeks). After hospitalization, a clinical control and clinical and angiographic controls were performed at one and six months respectively. RESULTS: 27 patients were excluded after the procedure because of failed delivery of the stent (5 cases), suboptimal angiographic result (15 cases) or lack of adherence to the antithrombotic regime (7 cases). Among the 341 patients with an adequate result most lesions (76.2%) were type B, including 39.1% type B2 and 8.5% type C. Subacute stent occlusion occurred in two patients (0.6%). Seven patients (2.1%) had vascular complications related to the arterial puncture. No major hemorrhagic complications needing transfusion were found. At six months 64 patients (19.8%) showed angiographic restenosis. CONCLUSIONS: When the angiographic result after Wiktor stent placement is adequate, the therapy with aspirin and ticlopidine is associated with a very low stent thrombosis rate as well as with a low rate of vascular complications and 6 month angiographic restenosis.

Adult↗
PubMed1997

Vitamin D receptor gene expression in human pituitary gland.

1,25-dihydroxyvitamin D3 has important physiological effects such as calcium transport and cell growth and differentiation. These biological effects are mediated by their binding to specific intracellular receptor termed vitamin D receptor (VDR). VDR mRNA expression has been demonstrated in several tissues, but to date, there is no information about its presence in the human pituitary gland. In this report, we demonstrate VDR mRNA expression using the reverse transcription-polymerase chain reaction (RT-PCR), as well as the cellular expression of VDR by immunohistochemistry, both in the human pituitary gland. These results suggest the possibility that, like in the rat pituitary, VDR may regulate the human pituitary gene expression and hormone secretion.

Adult↗
PubMed1997

Immunofluorometric assay of pepsinogen C and preliminary clinical applications.

We developed mouse monoclonal antibodies (Abs) against pepsinogen C with highly purified antigen isolated from gastric mucosa. The Abs were used to construct a two-site sandwich-type assay for pepsinogen C with time-resolved fluorometry as a detection technique. The assay has a detection limit of 0.1 microgram/L and is precise (within-run and day-to-day CVs < 11%). We used this assay to measure pepsinogen C in seminal plasma, breast cyst fluid, amniotic fluid, male and female serum, serum from patients with prostate cancer, urine, breast tumor cytosolic extracts, breast milk, and cerebrospinal fluid. Highest pepsinogen C concentrations were in seminal plasma, followed by breast cyst fluid and amniotic fluid. We found no correlation between prostate-specific antigen concentrations and concentrations of pepsinogen C in serum of prostate cancer patients, and concluded that this marker is not useful for either diagnosing or monitoring prostatic carcinoma. The availability of a highly sensitive, reliable, and convenient method for quantifying pepsinogen C will allow investigations into the possible diagnostic value of this analyte in various clinical conditions, including benign breast diseases, breast cancer, fertility, and pregnancy.

Amniotic Fluid↗
PubMed1997

Infected abdominal aortic aneurysm: in situ replacement with cryopreserved arterial homograft.

Infected aortic aneurysms are a rare (1.3% of all abdominal aortic aneurysms) but life-threatening disease. At present controversy continues about the specific diagnosis and the best surgical management. We present one case of infected aortic aneurysm treated with in situ reconstruction with cryopreserved arterial homograft. He was a 50-year-old man with recent history of pneumococcal meningitis who is readmitted because he suffered a stroke and during physical examination a pulsatile abdominal mass was discovered. Blood cultures were done and the result was repeatedly negative. Radiological studies were performed: the abdominal CT scanning showed a non ruptured 5 cm infrarenal aortic aneurysm with irregular wall and in the aortography it appeared eccentric, multilobulated with a clear neck in an otherwise normal size aorta but with some arteriosclerotic lesions. The diagnosis of infected aneurysm was suspected and the patient received antibiotic therapy and was operated on: aneurysm resection with wide debridement of surrounding tissues and in situ aortic replacement with aortobifemoral cryopreserved arterial homograft. Cultures of the aneurysm wall and contents were negative but aneurysm wall biopsy suggested an infected aortic aneurysm. The postoperative course was uneventful and antibiotics were continued for 6 weeks. The patient is doing well 7 months after surgery without signs of recurrent infection and normal appearance of the cryopreserved arterial homograft. We conclude that specific diagnosis of infected aortic aneurysms is essential for correct treatment but may be difficult, in these cases a history of infection supported by radiologic findings and aneurysm wall biopsy are of great value. Cryopreserved arterial homografts constitute a good alternative to prosthetic grafts for in situ reconstructions in the treatment of infected aortic aneurysms, decreasing the risk of re-infection or septic complications.

Aneurysm, Infected↗
PubMed1997

HLA-DQA1*0501 and DQB1*02 homozygosity and disease susceptibility in Spanish coeliac patients.

Coeliac disease (CD) susceptibility is strongly associated with HLA-DQA1*0501 and DQB1*02 alleles. There are discordant reports on whether homozygosity increases the risk. We genotyped HLA-DQA1*0501 and DQB1*02 in 50 CD patients, 100 parents, and 50 controls. Most patients (96%) were positive for DQA1*0501 (RR = 18.07, p < 0.001), 94% for DQB1*02 (RR = 17.55, p < 0.001), and 92% for both alleles together (RR = 31.82, p < 0.001). DQA1*0501 was found in 52% of controls, DQB1*02 in 44%, and only 24% had both alleles. Patients homozygosity or heterozygosity was estimated by assessing-in each case-whether one or both parents were carriers of the allele of risk. The frequencies of parents both positive for DQA1*0501 (58%) and for DQB1*02 (53.1%) were higher than expected by the fact that the proband is a carrier. These findings suggest that the frequency of homozygosity is increased among CD patients, and therefore, homozygosity for either DQA1*0501 or DQB1*02 represents a risk factor added to the fact of being a carrier.

Alleles↗
PubMed1996

A regulatory role for cAMP-dependent protein kinase in protein traffic along the exocytic route.

The influence of protein kinase A activity on transport of newly synthesized vesicular stomatitis virus G glycoprotein along the exocytic pathway was examined. Transport of vesicular stomatitis virus G glycoprotein to the cell surface was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), a selective inhibitor of protein kinase A. This block occurred at the exit of the Golgi complex, whereas transport through the Golgi compartments or from the endoplasmic reticulum to the Golgi was decreased in the presence of H-89. As judged by immunofluorescence endoplasmic reticulum to Golgi transport was accelerated in cells incubated with activators of protein kinase A such as isobutylmethylxanthine (IBMX) or forskolin (FK). Treatment with IBMX and FK also increased transport from the trans-Golgi network to the cell surface. During incubation with IBMX and FK, the organization of the Golgi complex was altered showing intercisternae fusion and miscompartmentalization of resident proteins. These structural changes affected both the kinetics of acquisition of endoglycosidase H resistance and transport activities. These data support a differential regulatory role for protein kinase A in different transport steps along the exocytic pathway. In particular, transport from the trans-Golgi network to the cell surface was dependent on protein kinase A activity. In addition, the results suggest the involvement of this enzyme on the maintenance of the Golgi complex organization.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Degradation of aggrecan precursors within a specialized subcompartment of the chicken chondrocyte endoplasmic reticulum.

Chicken chondrocytes in culture synthesize aggrecan proteoglycan as a 370 kDa precursor that is glycosylated and secreted into the medium with a half-life of 30 min. In metabolic studies the 370 kDa precursor was shown to render a degradation intermediate of 190 kDa, which appeared with no measurable lag phase; it was dependent on temperature ( > 20 degrees C) and inhibited by certain serine and serine/cysteine protease inhibitors such as leupeptin and PMSF. By contrast, degradation was unaffected by treatment of the cells with brefeldin A or with lysosomotropic agents. Aggrecan precursors were detected by immunofluorescence analysis within a subcompartment of the endoplasmic reticulum (ER), previously characterized as a smooth-membrane-bound subregion [Vertel, Velasco, LaFrance, Walters and Kaczman-Daniel (1989) J. Cell Biol. 109, 1827-1836]. Analysis of the subcellular fractions derived from chondrocytes indicated that the degradation intermediate was concentrated in the ER subcompartment. Degradation was dependent on the Ca2+ concentration and the redox state in the ER. Treatment of the cells with agents or conditions that alter the degradation rate of aggrecan precursors, such as protease inhibitors, decreased temperature or dithiothreitol, also modified the retention of these molecules in the ER subcompartment, as seen by immunofluorescence. These results indicate that a fraction of the 370 kDa aggrecan precursor is targeted to a smooth ER subcompartment where it undergoes degradation.

Aggrecans↗
PubMed1996

Usefulness of the secondary probe pTBN12 in DNA fingerprinting of Mycobacterium tuberculosis.

A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the insertion sequence IS6110 and those produced with the polymorphic GC-rich repetitive sequence contained in the plasmid pTBN12. A total of 302 M. tuberculosis isolates from the prison system in Madrid, Spain, and the Denver Public Health Department (Denver, Colo.) were analyzed with the two probes. Both probes identified the same isolates in the same clusters when the fingerprints had six or more copies of IS6110. Analysis of isolates with unique IS6110 fingerprints demonstrated that they were unique with pTBN12. The pTBN12 probe had greater discriminating power in isolates having five or fewer copies of IS6110. Forty-seven isolates from Denver having fewer than five copies of IS6110 which were grouped in 11 clusters with identical fingerprint patterns were subdivided into 35 different patterns by pTBN12. Isolates with IS6110 fingerprints with more than six copies of IS6110 that differed from one another by only one or two hybridizing bands were analyzed with pTBN12. Most of these sets of isolates demonstrated identical patterns with pTBN12. However, some exceptions were observed, suggesting that those having nearly identical IS6110 patterns should not necessarily be included in the same cluster. Since IS6110 provides more polymorphism in the fingerprint, it is most useful in identifying isolates with unique fingerprint patterns and those in clusters in which the isolates contain six or more copies of the insertion. However, it is necessary to employ a secondary probe, such as pTBN12, to discriminate isolates with five or fewer copies of IS6110 and those with similar but not identical IS6110 patterns.

DNA Fingerprinting↗
PubMed1996

Influence of iron status in the response to the deferoxamine test.

The study presented here was carried out to evaluate the possible relationship between serum iron and iron transferrin saturation with the response to the deferoxamine test in 86 chronic renal failure patients undergoing hemodialysis. The deferoxamine test was performed as a diagnostic tool for aluminum intoxication. Basal serum aluminum levels correlated with: (1) serum aluminum levels after the infusion of deferoxamine (r = 0.45; P < 0.05); (2) serum iron levels (r = -0.26; P < 0.05), and; (3) iron transferrin saturation (r = -0.33; P < 0.05). The increase in serum aluminum levels after deferoxamine administration (DAI) showed a negative relationship with serum iron levels (r = -0.23; P < 0.05) and iron transferrin saturation (r = -0.26; P < 0.05). The correlations improved when analysis of this study included only those patients with high serum iron levels or high iron transferrin saturation (r = -0.55). Patients with low probability of having aluminum overload (serum iron levels < 40 micrograms/L and DAI < 150 micrograms/L) had significantly higher values of serum iron, iron transferrin saturation, and serum ferritin levels compared with those patients with a high probability of having aluminum overload (serum aluminum levels > 40 micrograms/L and DAI > 150 micrograms/L). The study presented here suggests that patients who have indicators of iron repletion would tend to have lower increases in serum aluminum levels after the challenge with deferoxamine and presumably a higher incidence of false negative results with the deferoxamine test. These findings indicate that iron measurements must be always taken into account when interpreting the deferoxamine test.

Aluminum↗
PubMed1996

Expression of a specific subset of CD44 variant transcripts in NOD pancreatic islets.

Adhesion of lymphocytes to the endothelial venules inside the islets of Langerhans seems to initiate the infiltration of islets in NOD mice. An overexpression of the lymphocyte surface molecule CD44 in infiltrated NOD islets compared with peripheral blood lymphocytes was recently reported. The CD44 protein family includes a variety of molecules generated by alternative RNA splicing from 10 variant exons (v1-v10). By using reverse transcriptase-polymerase chain reaction followed by Southern blotting and hybridization to exon-specific cDNA probes, we investigated the expression of CD44 isoforms in highly purified islets of Langerhans from 4- and 10-week-old NOD mice. At least six CD44 isoforms were strongly overexpressed in NOD islets at 4 and 10 weeks when compared with age-matched BALB/c islets. Controls in different tissues indicate that these variants are specifically increased in the islets from the NOD strain. Islets from the NOD-scid/scid strain also expressed these variant exons. Splenocytes from BALB/c did not express CD44 isoforms, whereas splenocytes from 4-week-old NOD mice did express CD44 variants. Treatment with inflammatory mediators induced new isoforms; however, these transcripts have a different variant exon composition from that found in NOD mice islets. These results suggest that some isoforms are expressed very early in the development of insulitis by a component of the NOD islet itself and underscore a possible role of CD44 in islet infiltration.

Animals↗
PubMed1996

[Hemodynamic and electrophysiologic changes in hypertrophic cardiomyopathy].

Hypertrophic cardiomyopathy is characterized by abnormalities of the myocardium, and the activation and conduction tissues, that may have separate manifestations, but often occur together in complex clinical pictures. The subaortic gradient, although not always present, is the most classical manifestation of the disease, with its typical dynamic behavior, changing with preload, afterload and contractility. In most cases it is due to systolic motion of the mitral valve against the septum in systole, but in a few it is caused by midventricular "constriction". Alteration of diastolic ventricular function is important, and probably the main cause of heart failure, that is usually accompanied by normal systolic function. Mitral insufficiency is common in the obstructive forms, due to the abnormal mitral valve motion, but in some cases it may be due to structural abnormalities of the valve. There may be systolic constriction, or nonatherosclerotic occlusion of the intramyocardial coronary arteries, causing myocardial infarction and ventricular aneurysms, that may lead to systolic dysfunction. The electrocardiogram is rarely normal. Hypertrophy patterns, deeply inverted T waves, deep Q waves, QRS slurring suggestive of WPW syndrome without true preexcitation are the most common manifestations. Rhythm disturbances are common and include sinus node dysfunction, superconductor atrioventricular node or heart block. Atrial fibrillation is frequent and may have catastrophic consequences, including systemic embolism. Non-sustained ventricular arrhythmias are often present, but its predictive value for sudden death is unclear. Monomorphic ventricular tachycardia is infrequent, and programmed stimulation is more likely to precipitate polymorphic ventricular tachycardia of difficult clinical interpretation. Sudden death may be due to multiple mechanisms, and it is difficult to predict and prevent.

Arrhythmias, Cardiac↗