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Biomedical subjects

M Alonso

Publications and source records attributed to M Alonso.

At least 91 records · Page 5Linked to original sources
PubMed1999

Monte Carlo estimation of absorbed dose to organs in diagnostic radiology.

A method to estimate the absorbed dose to organs in diagnostic radiology was developed. The method is based on Monte Carlo techniques and has been prepared as a tool that can be adapted to any type of examination or view and which is readily available since it is used in a personal computer and not as a list of numerical results. It has been developed with the EGS4 system for static examinations in diagnostic radiology. A study was made of the absorbed doses to different parts of the head during a conventional x-ray examination. Simulation was performed for different arrangements (monoenergetic beam, spectrum, different number of histories, different size of cells, etc.). The method is capable of estimating doses in agreement with those measured experimentally and those obtained by other authors.

Computer Simulation↗
PubMed1999

Ribosomal RNA gene loci and silver-stained nucleolar organizer regions associated with heterochromatin in Alaskan char Salvelinus malma and chum salmon Oncorhynchus keta.

Nucleolus-forming 5.8S, 18S and 28S ribosomal RNA gene (rDNA) loci were assigned by fluorescence in situ hybridization (FISH) to the distal half of the short arms of a large-sized submetacentric pair in the Alaskan char (Salvelinus malma) and to the distal region of the long arms of a medium-sized submetacentric pair in the chum salmon (Oncorhynchus keta), respectively. In each species, heteromorphic FISH signals, spanning whole satellite region and secondary constriction, imply an intraspecific variation in the size of rDNA loci. Size variation of silver-stained nucleolar organizer regions (AgNORs) was also apparent between or within the assigned rDNA loci in each species, suggesting a possible inter- or intralocus inactivation of rDNAs. C-band positivity of assigned rDNA loci and AgNORs unequivocally showed their association with heterochromatin in these species.

Animals↗
PubMed1999

Lemierre's syndrome (necrobacillosis).

Lemierre's syndrome or postanginal septicaemia (necrobacillosis) is caused by an acute oropharyngeal infection with secondary septic thrombophlebitis of the internal jugular vein and frequent metastatic infections. Fusobacterium necrophorum is the most common pathogen isolated from the patients. The interval between the oropharyngeal infection and the onset of the septicaemia is usually short. The most common sites of septic embolisms are the lungs and joints, and other locations can be affected. A high degree of clinical suspicion is needed to diagnose the syndrome. Computed tomography of the neck with contrast is the most useful study to detect internal jugular vein thrombosis. Treatment includes intravenous antibiotic therapy and drainage of septic foci. The role of anticoagulation is controversial. Ligation or excision of the internal jugular vein may be needed in some cases.

Fusobacterium Infections↗
PubMed1999

3D electron microscopy of the interaction of kinesin with tubulin.

We have studied the structure of microtubules decorated with kinesin motor domains in different nucleotide states by 3D electron microscopy. Having docked the atomic coordinates of both dimeric ADP.kinesin and tubulin heterodimer into a map of kinesin dimers bound to microtubules in the presence of ADP, we try to predict which regions of the proteins interact in the weakly binding state. When either the presence of 5'-adenylyimidodiphosphate (AMP-PNP) or an absence of nucleotides puts motor domains into a strongly-bound state, the 3D maps show changes in the motor domains which modify their interaction with beta-tubulin. The maps also show differences in beta-tubulin conformation compared with undecorated microtubules or those decorated with weakly-bound motors. Strongly-bound ncd appears to produce an identical change.

Adenosine Diphosphate↗
PubMed1999

Thyroid autoimmunity in children and adolescents with Type 1 diabetes mellitus.

Type 1 diabetic children and adolescents often present with autoimmune thyroid disorders. Two hundred and four diabetic patients, less than 20 years old, were studied in order to diagnose these diseases. The prevalence of thyroid autoimmune disorders was 17.6% and, of those, chronic autoimmune thyroiditis was the most frequent. Microsomal autoantibodies correlated more accurately with the presence of chronic autoimmune thyroiditis than thyroglobulin autoantibodies. The thyroid status of most of the patients with positive markers was euthyroidism (77%), but subclinical hypothyroidism (11%), overt hypothyroidism (3%), subclinical hyperthyroidism (3%) and overt hyperthyroidism (6%) were also present. Autoimmune thyroid disorders were the most prevalent immunological processes affecting diabetic patients. No significant associations of thyroid autoimmunity and other autoimmunological disorders, such as celiac disease or presence of other autoimmune antibodies, were found.

Adolescent↗
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

Calphostin C induces selective disassembly of the Golgi complex by a protein kinase C-independent mechanism.

Intact cells incubated with calphostin C, an inhibitor of the regulatory domain of protein kinase C, showed fragmentation and dispersal of the Golgi complex by a light-dependent mechanism. At the ultrastructural level Golgi stacks were replaced by clusters of vesicles and short tubules that resembled the Golgi remnants present in control mitotic cells. Vesicle-mediated transport processes along both the exocytic and endocytic routes were also inhibited by calphostin C treatment. Golgi disassembly, however, was not due to protein kinase C inhibition since several inhibitors of the catalytic domain did not cause a similar effect. In contrast, pretreatment with phorbol 12-myristate 13-acetate partly protected the Golgi complex from disassembly by calphostin C. The in vitro effect was shown to be reversible, required both cytosol and ATP and it was inhibited by pretreatment of the Golgi membranes with trypsin but not with high salt. These results suggest the interaction of calphostin C with a structural Golgi protein containing a phorbol ester-binding domain and necessary for the stability of this organelle during interphase.

Adenosine Triphosphate↗
PubMed1998

[Ambulatory blood pressure monitoring in the aged. The EPICARDIAN study. The EPICARDIAN Work Group].

OBJECTIVE: To determine reference values for ambulatory blood pressure in a random sample of Spanish elderly population, and their correlations with office blood pressure measurements. METHODS: A representative random sample was obtained, stratified by sex and age, of 1,227 elderly subjects aged > 65 years, residents in an urban district, Barrio de Salamanca, or Madrid, Spain. In a random subsample (n = 420), two different blood pressure measurement approaches were performed: Office blood pressure and twenty-four hour ambulatory blood pressure (spacelabs 90207) were recorded, and two periods were defined: awake and sleeping, on the basis of the daily activities. Hypertension was defined if the average of casual blood pressure was > or = 140/90 mmHg or if there was current use of antihypertensive drugs. RESULTS: Among the 420 participants, 333 ambulatory blood pressure monitorings were performed, 301 with valid registers, of whom 105 were receiving antihypertensive drug treatment. Office, 24 hour, awake and sleeping pressures averaged 147/84 mmHg, 128/72 mmHg, 132/77 mmHg and 122/66 mmHg respectively. Differences between whole sample and no treated group were not significant (p = 0.2), nor between the whole sample and the treated group (p = 0.7). Office blood pressure was markedly higher than 24 hour and awake averages (20 and 15 mmHg for systolic and 12 and 7 mmHg for diastolic, respectively). The differences between clinic and awake average blood pressures were significantly higher in females (p = 0.001) and increased, in both genders, as age (p = 0.001) and clinic blood pressure values (p < 0.000) increased. Correlation coefficients between office and the average awake period of the ambulatory blood pressures were of 0.60 and 0.48 for systolic and diastolic respectively. The ambulatory blood pressure value equivalent to 140/90 mmHg when obtained by causal measurement, was 15 mmHg lower when considering the 24 h average, or 10 mmHg lower when the awake averages. CONCLUSION: Ambulatory systolic and diastolic blood pressure values in the elderly are markedly lower than office values, specially in the case of systolic blood pressure. Differences in results between the two methods increase with age and with clinic blood pressure values, and are bigger in females. The cut-off point for ambulatory blood pressure monitoring equivalent to 140/90 mmHg in the casual measurement is of 125/75 mmHg for the 24 hour average and of 130/80 mmHg for awake average.

Age Factors↗
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↗