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Biomedical subjects

J Medina

Publications and source records attributed to J Medina.

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

Cloning of cDNA, expression, and chromosomal location of genes encoding the three types of subunits of the barley tetrameric inhibitor of insect alpha-amylase.

Three cDNA clones from barley developing endosperm, corresponding to proteins BTAI-CMa, BTAI-CMb and BTAI-CMd, which are the three types of subunits of the tetrameric inhibitor of insect alpha-amylases, have been identified and sequenced. The deduced amino acid sequence of BTAI-CMb corresponds to the CM16/CM17 type of subunit in wheat (92/90% identical residues) and has one putative N-glycosylation site (NLT) and a possible kinase-C phosphorylation site (SCR). The BTAI-CMa sequence differs at four amino acid residues from a previously reported one from cv. Bomi and the sequence deduced for BTAI-CMd completes (11 N-terminal residues) and confirms previously available data. The gene for BTAI-CMa (Iat1) is located in the beta arm of barley chromosome 7H (syn.1), while genes for both BTAI-CMb (Iat2) and BTAI-CMd (Iat3) are in the long arm of chromosome 4H. The three genes are expressed in endosperm and their mRNAs are not detected in the other tissues tested, except Iat1, which seems to be expressed at a low level in coleoptile and roots, where it is switched off by 50 microM methyl jasmonate.

Amino Acid Sequence↗
PubMed1993

Developmentally regulated herpesvirus plaque formation in arterial smooth muscle cells.

Previous studies of age-related susceptibility to viral infection have focused largely on the effects of aging on the immune response. Little attention has been given to age-related changes in the infectivity of target cells. We show here a fourfold greater plating efficiency of herpes simplex virus type 1 (HSV-1) for cultured vascular smooth muscle cells derived from adult rats compared with cells from genetically identical pup rats. The difference in plating efficiency appeared to be due to differences in initial attachment of the virion to the cell surface. There were no differences in the rate of viral entry or the efficiency of viral replication at high multiplicities of infection and no resistant "subpopulation" of pup cells. The pup cells did not release a soluble inhibitor of infection. Infection in both cell types was inhibited similarly by basic fibroblast growth factor (bFGF). Although adult cells exhibited a more vigorous mitogenic response to bFGF than did pup cells, binding studies did not demonstrate significant differences in the binding of bFGF to the cell surface, suggesting that differential expression of high-affinity FGF receptors could not be correlated with the difference in infectivity. We speculate that differences in the distribution of heparan sulfate in the cell surface, which serves as the initial attachment site for HSV-1, may explain the observed differences in plating efficiency. Since age is a risk factor for the development of atherosclerosis, these results have potential implications for susceptibility of the vasculature to herpesviral infections as a function of the development of the vessel wall.

Age Factors↗
PubMed1993

Tumor necrosis factor-induced contraction of cultured rat mesangial cells: interaction with angiotensin II.

The role of tumor necrosis factor alpha in the regulation of renal function, particularly glomerular filtration rate, has not been completely defined. This study was designed to assess the intrinsic role of this cytokine on glomerular filtration rate by analyzing its short-term effect on the degree of contraction in cultured rat mesangial cells, not only directly but also in the presence of angiotensin II. Contraction was evaluated both morphologically--by measuring planar cell surface area of cultured rat mesangial cells and glomerular cross-sectional area of isolated rat glomeruli--and biochemically--by analyzing myosin light-chain phosphorylation in cells. Tumor necrosis factor alpha significantly decreased planar cell surface area in a dose-dependent and time-dependent manner, an effect completely abolished by preincubation of the cells with platelet-activating factor receptor antagonists BN 52021 and alprazolam. This effect was also observed in the presence of angiotensin II, whether tumor necrosis factor alpha was added before or after angiotensin II, increasing the reduction in planar cell surface area induced by angiotensin II in both cases. Changes in planar cell surface area were evident not only when the absolute values of this parameter were considered but also when the percentage of contracted cells (cells with a planar cell surface area reduction > 10%) was analyzed. Tumor necrosis factor alpha also induced a significant reduction of glomerular cross-sectional area in isolated rat glomeruli. The results of the morphologic studies were supported by myosin light-chain phosphorylation experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

[Epidemiological data on chronic myeloid leukemia in Asturias, 1972-1986].

PURPOSE: To evaluate the incidence of CML in Asturias during the period 1972-1986, studying the variations in relation to age, sex and geographical zone. MATERIAL AND METHODS: Information relating to the date of diagnosis, name, age, sex and home address of the 108 cases (65 men and 43 women) diagnosed CML during the period 1972-1986 according to conventional criteria was collected from the hospital records of the region. For the calculations, SADEI demographic data were taken as a reference, comparing the incidence between sexes and geographical zones by means of the CHI2. RESULTS: A rate of incidence of 0.64/100,000 inhabitants/year was obtained, this being 0.8 in men and 0.5 in women (p < 0.05). The rate of incidence increased progressively with age until the 45-59 age group when it was maximum. There were no differences between the three main centres of population Gijón (0.53), Oviedo (0.55) and Avilés (0.69) nor the latter with the rest of the zones in Asturias; nor was three either any difference between coastal towns (0.56) and those of the interior (0.71) (p = NS). CONCLUSIONS: Limited incidence of CML in Asturias without significant differences in its geographical distribution within the region. The incidence, which was higher among males, increased progressively with age until reaching maximum importance in the 45-59 age group.

Adolescent↗
PubMed1992

[Evaluation of the results of the research funded by the Health Research Fund in 1988].

BACKGROUND: To analyse the scientific product of research projects funded by Fondo de Investigación Sanitaria in 1988 emphasizing its relation to money granted. METHODS: 270 out of 610 projects were evaluated in relation to the amount granted. The number of papers published to each project and the impact factor assigned to the journals where these papers were published; we also assessed the mean cost of papers and impact factor units. These projects were coded following UNESCO classifications, and papers as per ISI standards. RESULTS: A total of 95 projects out of the 270 analysed produced no papers; the other 175 projects yielded 471 articles (2.7 per project); the mean cost of each article was 1.1 million pesetas, or 0.8 million if only the productive projects were considered. These papers reached a total of 818,709 impact factor units; the mean cost of the impact factor unit is 660,796 pesetas, or 459,626 pesetas if only productive projects are considered. CONCLUSIONS: Non productive projects were those that received less funding. 33% of projects produced papers published in journals with an assigned impact factor equal or inferior to one. There are evident differences among areas of knowledge in terms of impact factor. This study must be completed with a statistical analysis of reported data.

Evaluation Studies as Topic↗
PubMed1989

Neurochemical and behavioral correlates of unilateral striatal acetylcholinesterase inhibition by fasciculin in rats.

Fasciculin 2 (FAS) an anticholinesterase peptide isolated from the venom of the Green mamba (Dendroaspis angusticeps) was injected into the right striatum of albino rats (1.5 micrograms total amount). The inhibition of acetylcholinesterase (AChE) activity was 86 and 60% 24 h and 7 days after FAS injection, respectively. The treatment with apomorphine (APO) (2 mg/kg s.c.) 24 h after FAS provoked a moderate circling towards the lesioned side that was reverted by atropine (30 mg/kg i.p.). The same dose of APO 7 days after FAS, provoked an inconstant contralateral circling. Neither dopamine nor serotonin nor their metabolites were significantly affected 24 h or 7 days after FAS injection. Radioligand binding assays of dopamine, muscarinic and benzodiazepine receptors only showed a decrease of the density of the muscarinic ones 7 days after FAS. These results are interpreted as showing that the changes provoked by FAS would be compensated but the system would remain in an unsteady state only demonstrable after pharmacological challenge. The chronic down-regulation of muscarinic receptors would compensate the increased cholinergic activity and would therefore block its behavioral expression.

Acetylcholinesterase↗
PubMed1989

[Treatment of thumb arthrosis using Swanson's trapezial silicone implant].

Complications related to silicone implants have been widely described since 1985. As trapezial replacement with a silicone implant constitutes our preferred treatment for osteoarthritis of the base of the thumb, we decided to evaluate our results by means of a retrospective critical study. Fifty records of patients operated or between 1975 and 1980 constitute an homogeneous study group as all were operated according to the same technique and by the same surgeon. Seven cases of implant instability have led us to modify our fixation technique. The results in terms of mobility, stability and pain relief are good and comparable to other published series. Only two cases presented bony changes around the implant but they both existed before surgery. Our conclusion is that trapezial resection with replacement by a silicone implant can still be recommended as elective treatment for CMC thumb osteoarthritis because of its simplicity effectiveness and reversibility.

Aged↗