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Biomedical subjects

M Morales

Publications and source records attributed to M Morales.

At least 19 recordsLinked to original sources
PubMed1992

Effects of velnacrine, tacrine and physostigmine on tetanic twitch responses at the rat neuromuscular junction.

The effects of velnacrine (1-hydroxytacrine), tacrine and physostigmine on indirectly elicited twitch at low and high stimulation frequencies were analyzed in the rat phrenic hemidiaphragm preparation. At 0.2 Hz, velnacrine and physostigmine behaved in a similar manner, the latter showing a higher potentiating effect. This potentiation was observed at 3-100 microM velnacrine, whereas a slight depression appeared at higher concentrations. When tetanic responses were studied, the drug concentrations needed to depress tetanic tension and tetanic fade were quite different in the case of velnacrine (depression of tetanic tension from 1 microM and tetanic fade from 170 microM), whereas physostigmine and tacrine were able to affect these parameters at very similar concentrations. The results suggest that some effects of velnacrine could differ from those of tacrine in spite of the chemical similarity.

Animals↗
PubMed1992

HMG-like chromosomal proteins in Trypanosoma cruzi.

HMG-like chromosomal proteins from Trypanosoma cruzi were studied. Four HMG-like proteins, designated HMG A, HMG-B, HMG-C, and HMG-E, were isolated and found to have molecular weights of 35.5 kd, 27.5 kd, 21.8 kd and 10.4 kd, respectively. Immunological relatedness was demonstrated between the mammalian HMG 1,2 and the HMG-A and HMG-B from T. cruzi. The relative amounts of HMG-C and HMG-E proteins vary in T. cruzi depending to the proliferative stage of the cells. HMG-E protein is increased in proliferating cells when compared to its level in non-proliferating cells. HMG-C is increased in the non-proliferating cells. Probably, the shifts observed in the relative amounts of HMG-like proteins are related to the proliferating cells of this flagellate. The results are consistent with those described for other lower eukaryotes where the HMG-like proteins isolated are similar but not identical to HMG proteins from vertebrates.

Animals↗
PubMed1992

Aging and the neurocytoskeleton.

It has been often demonstrated that during senescence some neurons undergo atrophic changes while others add new processes and terminals. Because microtubules form a substantial component of the dendritic and axonal cytoskeleton, we have studied the amount of tubulin and acetylated alpha-tubulin in three young (6 months) and three old (24 months) rats (Fischer 344). We have used sodium dodecyl sulfate (SDS) extracts of brain homogenates and Triton solubilized fractionated brain homogenates. With the first method we did not detect any age-related differences in total brain protein, total tubulin, or in relative amounts of acetylated alpha-tubulin. With the second method, we have observed a small systematic increase in relative amount of acetylated alpha-tubulin in the Ca2+/cold insoluble fraction. These results are similar to those reported in the literature, and they indicate a possible alteration in the cytoskeletal dynamics.

Acetylation↗
PubMed1992

Fused eyelids in the extremely premature infant: multivariate analysis of survival and outcome.

The presence of fused eyelids at birth in the extremely low birthweight infant (less than 1000 gm) is often regarded by physicians as an indication of nonviability. This is especially true for the pediatrician who does not have routine exposure to extremely premature infants and may use the presence of fused eyelids to influence the level of resuscitation afforded the infant in the first crucial minutes following birth. Unfortunately, there are scant data in the literature to guide general pediatricians with regard to this issue. The purpose of this study was to examine, with the aid of multivariate statistical analysis, the survival and combined outcome score in extremely premature infants with and without fused eyelids. The combined outcome was a composite of several outcome variables (intraventricular hemorrhage, bronchopulmonary dysplesia, and retinopathy of prematurity); survival was defined employing the standard definition of neonatal survival, that is, alive at 28 days post natal age. Combined outcome and survival were analyzed with regard to several independent variables (birthweight, gestational age, and 5-minute Apgar scores, mode of delivery, race, sex, and maternal age). A regression analysis was performed to determine the effect of the independent variables on the combined outcome. A separate multivariate logistic regression analysis was employed to determine the effect of the same independent variables on neonatal survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1992

Bioavailability of energy, nitrogen, fat, zinc, iron and calcium from rural and urban Mexican diets.

The availabilities of nutrients from a representative rural Mexican diet (RMD) and a representative urban Mexican diet (UMD) were evaluated by balance experiments in sixteen Mexican women. Compared with UMD, the plant-based RMD led to a higher number of defaecations and higher faecal excretion of dry matter, fat, nitrogen and energy. Apparent digestibility of N from RMD was only 67% compared with 90% from UMD. N balance was 0.4 and 2.6 g/d with RMD and UMD respectively (P < 0.001). Apparent digestibility of energy was 89 and 95% from RMD and UMD respectively (P < 0.001). Calculation of the metabolizable energy (ME) using Atwater's (Atwater & Bryant, 1900) general factors overestimates the determined ME in RMD by 8%. The Food and Agriculture Organization/World Health Organization/United Nations University (World Health Organization, 1985) recommended factors for correction of digestibility of fibre intake overestimate energy and protein absorption from RMD. The diets provided similar amounts of zinc, and its apparent absorption from RMD was 0.5 mg/d (4.6%) and its balance was 0.1 mg/d. This compared with values for UMD of 1.6 mg/d (16%) and 1.2 mg/d respectively. Iron intake was higher from RMD (17.4 v. 11.6 mg/d; P < 0.01), but apparent absorption was 17 v. 35% and balance was 2.7 and 3.8 mg/d (P < 0.001) for RMD and UMD respectively. RMD also contained more calcium (745 v. 410 mg/d) but apparent absorption from RMD was negative (-136 v. 15 mg/d) and balance was more negative (-197 v. -77 mg/d; P < 0.05). Thus, the content of these minerals is not low in the rural diet but their bioavailabilities are poor.

Adolescent↗
PubMed1992

Release of soluble Fc gamma RII/CD32 molecules by human Langerhans cells: a subtle balance between shedding and secretion?

Freshly isolated human Langerhans cells (LC) express two forms of Fc gamma RII: a membrane-associated form detected by monoclonal antibody (MoAb) anti-CD32, which recognize an extracytoplasmic epitope of the molecule, and a soluble secreted form, whose existence is suggested by reverse transcriptase-polymerase chain reaction (RT-PCR) experiments. Indeed, RT-PCR performed on total LC RNA reveals the presence of two Fc gamma RIIA mRNA, one encoding the FC gamma RIIA with a transmembrane region (membranous form) and the other without this region (soluble form). Densitometry studies performed on the two PCR products reveal that the ratio between the membranous form and the soluble secreted form is about 1.5. LC maintained in culture for 24-48 h lose the major part of their membrane Fc gamma RII expression (shown by flow cytometry) and release soluble Fc gamma RII molecules (revealed by dot-blot assay), but maintain the same ratio of the two Fc gamma RIIA mRNA. The disappearance of the membrane-associated Fc gamma RII may be explained either by modification of its recycling pathway or by proteolytic cleavage of the receptor at the cell surface. Thus, soluble Fc gamma RII molecules generated during LC culture may result from proteolytic cleavage of the cell-surface receptor and/or secretion of a soluble form derived from the translation of an alternate spliced mRNA. Interestingly, addition of TNF-alpha (10 ng/ml) to the culture medium i) maintains the expression of the membranous form, which can be detected on the LC surface at the same level as on freshly isolated LC, and ii) reverses the ratio (to 0.6) of the two Fc gamma RII mRNA, the mRNA encoding the soluble form becoming predominant. Thus, TNF-alpha seems to modify the expression of the Fc gamma RII at the mRNA level, favoring the secretion of soluble Fc gamma RII molecules, and changes the fate of the membranous Fc gamma RII.

Humans↗
PubMed1992

A new variant of Glanzmann's thrombasthenia (Strasbourg I). Platelets with functionally defective glycoprotein IIb-IIIa complexes and a glycoprotein IIIa 214Arg----214Trp mutation.

We describe a new variant of Glanzmann's thrombasthenia (variant Strasbourg I). The patient (M.S.) showed an absence of platelet aggregation to ADP, thrombin, and collagen, and a decreased clot retraction. Platelet fibrinogen was approximately 20% of normal levels. ADP-stimulated platelets bound markedly reduced amounts of soluble fibrinogen and platelet adhesion to surface-bound fibrinogen was defective. Normal to subnormal amounts of glycoprotein (GP) IIb-IIIa (alpha IIb beta 3) complexes, the platelet fibrinogen receptor, were revealed by SDS-PAGE, crossed immunoelectrophoresis, and antibody binding. However, the complexes were unusually sensitive to dissociation with EDTA at room temperature. Furthermore, flow cytometry showed that the platelets failed to bind the activation-dependent monoclonal antibody, PAC-1, after stimulation. In contrast, an RGDS-containing peptide induced significant binding of the anti-ligand-induced binding site antibody, D3GP3, suggesting the presence of a functional RGD binding domain on the patient's GPIIb-IIIa complex. Sequence analysis was performed after polymerase chain reaction amplification of selected patient's GPIIIa exons, and of the patient's platelet GPIIb and GPIIIa mRNAs. A point mutation (C to T) was localized in exon D (iv) of GPIIIa that resulted in an 214Arg to 214Trp amino acid substitution. The defect has been inherited from the parents who are heterozygous for the same mutation. This substitution points to an essential amino acid in a region of GPIIIa involved in the binding of fibrinogen and influencing the Ca(2+)-dependent stability of the GPIIb-IIIa complex.

Adult↗
PubMed1992

[Treatment of patients with panic disorder and an elevated urinary excretion of MHPG using imipramine or clonazepam].

The response to treatment with imipramine or clonazepam was evaluated in patients with panic disorder. These patients had a high urinary 3-methoxy-4-hydroxy-phenylglycol 24 h-excretion and normal plasma lactate levels. Both drugs were efficient as anti-panic agents, but clonazepam resulted more efficacious than imipramine by the scores of Hamilton Anxiety or Depression Scales. Moreover, clonazepam also reduced the anticipatory anxiety.

Adult↗
PubMed1991

Distribution of acetylated alpha-tubulin in brain. In situ localization and biochemical characterization.

We studied the solubility properties of brain acetylated alpha-tubulin, as well as the localization of this tubulin in brain tissue. Endogenous unpolymerized tubulin and cytoskeletal tubulin were fractionated after brain Triton-solubilization. Using the immunoblotting technique, we found that acetylated alpha-tubulin was recovered in the cytoskeletal fraction, and that most (92%) of the acetylated microtubules of this fraction were depolymerized by cold/Ca2+ treatment. In another set of experiments, axonal and soma-dendritic preparations were found to have equivalent amounts of acetylated alpha-tubulin. By immunogold electron microscopy, we established that acetylated microtubules are widely distributed in dendrites of the central nervous system.

Acetylation↗
PubMed1991

Fiber digestibility and breath-hydrogen excretion in subjects consuming rural and urban Mexican diets.

Apparent digestibility of dietary fiber and its effect on breath-hydrogen excretion and gastrointestinal symptoms were determined in 16 subjects consuming a plant-based rural Mexican diet (RMD) and a more refined urban Mexican diet (UMD). Neutral-detergent-fiber intake and digestibility were 40.2 and 22.7 g/d (56%) for the RMD and 12.1 and 8.9 g/d (70%), respectively, for the UMD. Apparent digestibilities of hemicellulose, cellulose, and lignin were 40%, 63%, and 53% from the RMD and 73%, 75%, and 58%, respectively, from the UMD. Total breath-hydrogen excretion during 10 postprandial h was similar after both diets, showing that the breath-hydrogen test is of limited value for comparing carbohydrate fermentation from mixed diets. Mouth-to-colon transit time was 5.7 and 6.5 h for the RMD and UMD, respectively (P less than 0.05). There were significantly more gastrointestinal symptoms with the RMD (P less than 0.01); however, neither diet caused symptoms indicative of serious gastrointestinal discomfort.

Adolescent↗
PubMed1991

The computerized Tower of Hanoi: a new form of administration and suggestions for interpretation.

A computerized version of the Tower of Hanoi with a new form of administration was administered to two different groups, 15 men and 22 women, who were university students reporting normal psychological histories, and 24 traumatically brain-injured patients (20 men and 4 women). Scores on this test for both groups can be interpreted as an index of ability to solve problems and of learning strategies. Men and women scored differently on the task, i.e., women used different strategies than men to solve problems.

Adolescent↗
PubMed1979

Sulfatide content and (Na+ + K+)-ATPase activity of skin and gill during larval development of the Chilean frog, Calyptocephalella caudiverbera.

The sulfatide content, phospholipid concentration, and (Na+ + K+)-ATPase activity from skin and gills of different stages of larval development of Calyptocephalella caudiverbera (a Chilean frog) were analyzed. Additionally, the short-circuit current in skin was studied. When skin and gills, depending on the stage of larval development, present (Na+ + K+)-ATPase activity, they have a high ratio of sulfatide to amount of membrane and the phosphatidylserine concentration remains unchanged. Sulfatide content and (Na+ + K+)-ATPase activity in skin are in direct relationship with the level of sodium flux present during development. The specific enzymatic hydrolysis of sulfatide with partially purified arylsulfatase of pig kidney inhibits 100% of the ouabain-sensitive (Na+ + K+)-ATPase. The ouabain-insensitive ATPase remains virtually unchanged with the treatment, even with a high concentration of arylsulfatase or with ouabain present in the medium. These experiments strongly suggest a role of sulfatides in the (Na+ + K+)-ATPase activity and, as a consequence, in sodium ion transport.

Animals↗