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Biomedical subjects

M Morales

Publications and source records attributed to M Morales.

At least 163 records · Page 9Linked to original sources
PubMed1994

Percutaneous insertion of Hickman catheters while the patient is in bed: a simplification of the technique.

Central-venous long-term catheters are an important tool for patients undergoing anticancer chemotherapy. To circumvent dependence on the surgical department and their waiting lists, catheters were placed while the patient was in bed in the ward of a general oncology unit. A total of 84 single-lumen Hickman catheters were inserted with aseptic technique, percutaneously in this setting. The complication rate after the insertion was low, with only 1 case of pneumothorax (1.2%) and 7.1% of patients suffering arterial puncture. The placement of Hickman catheters while the patient is in bed is a safe procedure that can save hospitalization costs and permits the insertion at the optimum time in the care of the patient.

Adolescent↗
PubMed1994

Use of acute peritoneal dialysis catheters for intraperitoneal chemotherapy instead of the semipermanent/permanent Tenkhoff catheters.

Intraperitoneal chemotherapy was administered to 13 patients with peritoneal carcinomatosis, using acute peritoneal dialysis catheters immediately before the administration of the chemotherapy. A total of 59 cycles were administered, with insertion of the corresponding catheter. There were no inflow or outflow problems and no insertion-related complications. With the removal of the catheter after its use, there is no risk of abdominal infections.

Adult↗
PubMed1994

Extracorporeal circulation in the management of severe tricyclic antidepressant overdose.

Extracorporeal circulation is a technique that provides precise control of circulation, oxygenation, temperature, and blood composition in patients suffering from cardiopulmonary failure. The investigators present the case of a near fatal tricyclic antidepressant overdose that failed to respond to standard therapy but was resuscitated using extracorporeal circulation.

Adult↗
PubMed1994

Effects of electrical stimulation on lymphatic flow and limb volume in the rat.

BACKGROUND AND PURPOSE: The mechanism by which electrical stimulation affects edema has not been elucidated. The purpose of this study was to determine whether subcontraction high-voltage stimulation (SC-HVS) (ie, electrical stimulation that did not elicit a visible contraction) applied to the right hind limbs of rats would (1) alter the rate of lymphatic uptake of injected albumin labeled with Evans blue dye (AL-EBD) and (2) affect experimentally induced edema. SUBJECTS AND METHODS: The paws of 28 anesthetized Sprague-Dawley rats (mean weight = 263 g, SD = 48 g) were injected with AL-EBD. The experimental group (n = 13) received 1 hour of SC-HVS, and the control group (n = 15) received sham treatment consisting of the same treatment administered to the experimental group but without the SC-HVS. Blood samples and volume measurements were obtained at intervals over a 7-hour period. RESULTS: Analysis of variance and post hoc testing indicated that higher amounts of AL-EBD were taken up by the lymph of the experimental group animals as compared with the control group animals at each time period following the treatment. The experimental group's AL-EBD reached significance immediately after treatment, whereas the control group required an additional 4 hours. There was no significant reduction in limb volume in either group. CONCLUSION AND DISCUSSION: The SC-HVS significantly increased the uptake of AL-EBD by lymphatic vessels, but it did not cause a significant decrease in the induced edema. The results of this study indicate that SC-HVS has the potential to reduce edema by increasing lymphatic uptake of proteins.

Albumins↗
PubMed1994

[Cardiovascular response to exercise at high altitude in workers chronically exposed to intermittent hypobaric hypoxia].

The isotonic work performance was assessed in 34 workers aged 35 +/- 5.8 years old that had working shifts of four days at 4500 m over the sea level and resting periods of other four days at the sea level during at least two years. Subjects were assessed in one occasion at the sea level, and at the first and fourth day of the working shift at 4500 m over the sea level. Resting arterial oxygen saturation in these three periods was 97 +/- 1.1, 88 +/- 18 and 91 +/- 1.1% respectively (p < 0.01), and markedly decreased during maximal and submaximal exercise at 4500 m over the sea level. Exercise duration in the three periods was 931 +/- 210, 775 +/- 105 and 778 +/- 105 seg respectively (p < 0.001). Heart rate in the resting period was at least 10% higher and maximal and submaximal rates were lower at high altitude. No differences in blood pressure or packed red cell volume were observed. Exercise duration correlated inversely with age (r = -0.49 p = 0.03) and directly with maximal heart rate (r = 0.44 p = 0.009) at the sea level. No correlation between aerobic capacity and other measured parameters was observed. These results show no differences in the cardiovascular response to exercise between the first and fourth day of stay at high altitude in workers chronically exposed to intermittent hypobaric hypoxia.

Adult↗
PubMed1994

[Hepatitis B and C virus infections in children with congenital coagulation disorders].

The prevalence of hepatitis B and C virus infections, transmitted by blood transfusions, was studied in 79 children with congenital coagulation disorders. Twenty nine percent had evidences of hepatitis B virus infection and 52% evidences of hepatitis C virus infection. Older children and those with the higher number of transfusions had the highest rates of infections. It is concluded that children with congenital coagulation disorders constitute a high risk group for hepatitis B and C virus infections.

Adolescent↗
PubMed1994

[A new substrate for the detection of antimitochondrial antibodies in human serum].

This work describes a new method to detect antimitochondrial antibodies using indirect immunofluorescence on mouse sperm as substrate. As controls conventional substrates and mitochondrial protein immunoblots were used. An intense fluorescent reaction was visualized in the mitochondrial sheet of mouse sperms allowing a straightforward diagnosis of positive sera. Sera coming from 10 patients with progressive systemic sclerosis, 12 patients with systemic lupus erythematosus and 17 patients with primary biliary cirrhosis were tested with this method, confirming results obtained with conventional tests that use indirect immunofluorescence and rat frozen kidney slices as substrate. The new method is simpler, more accurate and has a lower margin of error.

Animals↗
PubMed1994

Aggregation of vasopressin mRNA in a subset of axonal swellings of the median eminence and posterior pituitary: light and electron microscopic evidence.

The mRNA encoding vasopressin has recently been documented within the magnocellular hypothalamo-neurohypophyseal projections of the rat such as the median eminence (ME) and the posterior pituitary (PP), suggesting the possibility of its axonal transport. To address the origin of this mRNA and to investigate the functional significance of this unexpected axonal transport of mRNA, we have examined its subcellular localization within both magnocellular perikarya and their axonal projections. For this purpose, we have used nonradioactive in situ hybridization techniques in order to localize the vasopressin mRNA with precision at the ultrastructural level in magnocellular perikarya, dendrites, and axons from control, salt-loaded, and lactating rats. This approach permitted us to demonstrate directly the axonal localization of vasopressin mRNA. Moreover, we were able to obtain novel information concerning vasopressin mRNA compartmentation within both perikarya and axons. At both light and electron microscopic levels, we observed vasopressin mRNA-containing cells in the hypothalamic magnocellular cell body groups, but not in the ME or in the PP. When vasopressin mRNA was detected in medium-size dendrites, it was always associated with the rough endoplasmic reticulum (RER). Within the labeled magnocellular perikarya, the abundant vasopressin mRNA was mainly associated with discrete areas of the RER. However, vasopressin mRNA was never detected in the Golgi apparatus or in association with neurosecretory granules, in perikarya or axons. These data suggest that vasopressin mRNA translation is restricted to certain segments within the RER, and that axonal transport of vasopressin mRNA does not involve the classical neurosecretory pathway, via the Golgi apparatus and the neurosecretory granules, as has been proposed. Within the magnocellular neuron axons, vasopressin mRNA could be detected only in a subset of axonal swellings, all of which were confined to the internal layer of the ME and the PP. The mRNA-containing swellings were numerous in 7 d salt-loaded animals, less abundant in lactating animals, and almost undetectable in control animals. In all groups of animals, no vasopressin mRNA was detectable in any other region of the magnocellular neuron axons, including undilated axonal segments or varicose swellings. These results strongly suggest that, under physiological activation such as chronic salt loading, axonal vasopressin mRNA is increased and becomes aggregated in a selected subset of swellings of the ME and the PP. Furthermore, these data indicate that along the magnocellular neuron axons, the swellings may differ in their biochemical and functional features. Further analysis focused on the mRNA-accumulating swellings may illuminate the function of RNA within the axonal compartment.

Animals↗
PubMed1993

Cloning and characterization of the gene encoding the human platelet glycoprotein V. A member of the leucine-rich glycoprotein family cleaved during thrombin-induced platelet activation.

Glycoprotein V (GPV) is a major platelet membrane 82-kDa glycoprotein, missing in the Bernard-Soulier syndrome, that is cleaved when platelets are treated with thrombin. We report the cloning and sequencing of the GPV cDNA and gene obtained by a combination of polymerase chain reaction amplification of platelet mRNA and genomic library screening. The single-copy gene for GPV is contained within 6.5 kilobase pairs (kb) of genomic sequence and has a simple structure with a single intron of 958 base pairs in the 5'-untranslated sequence; the coding sequence is contained within a single exon. The promoter region contains a canonical TATA box, and putative GATA, Ets-1, and Sp1 cis-acting elements. Reverse transcription-polymerase chain reaction analysis on RNAs from cells of different hematopoietic origins revealed that GPV was specifically transcribed from platelets and from cells of the megakaryocytic lineage (megakaryocytes, HEL cells). A single transcript of 4.5 kb for GPV was detected in human platelets by Northern blot analysis. The entire amino acid sequence of GPV was deduced from the cDNA and genomic sequences. Mature GPV was composed of 544 amino acids which contained a single transmembrane domain, a short cytoplasmic domain (16 residues), and a large extracellular domain with 8 potential N-glycosylation sites. Analysis of the extracellular domain revealed the presence of 15 tandem Leu-rich repeats of 24 amino acids with homology to GPIb alpha and identified a cleavage site for thrombin near the COOH terminus with similarity to the A alpha chain of fibrinogen, but no hirudin-like sequence was found.

Amino Acid Sequence↗
PubMed1993

Comparative effects of velnacrine, tacrine and physostigmine on the twitch responses in the rat phrenic-hemidiaphragm preparation.

1. Cholinesterase inhibitors potentiated twitch responses induced by nerve stimulation, with physostigmine more potent than tacrine and velnacrine. However, at higher concentrations, tacrine decreased twitch responses in a concentration-dependent manner. 2. Tacrine strongly depressed directly-induced twitch responses, whereas the other drugs had minimal effects. 3. Physostigmine was the most potent drug in reversal of tubocurarine-induced blockade, but its antagonism index was similar to those obtained with tacrine and velnacrine at higher concentrations. When evaluating their ability to reverse neomycin-induced blockade, all drugs exhibited a similar effect. 4. It is concluded that tacrine and velnacrine are less potent than physostigmine in potentiating skeletal neuromuscular transmission. Additionally, the blocking effects of tacrine could limit its therapeutic efficacy.

Animals↗
PubMed1993

Pharmacological sensitivity of the articular capsule of the primary spines of Eucidaris tribuloides.

1. This paper describes the effects of several cholinergic agonists and antagonists, and of beta-phenylethylamine (PEA) and some of its derivatives, on the articular capsule, or ligament, of the primary spines of Eucidaris tribuloides. 2. Carbamylcholine (CCh), methacholine (MeACh), nicotine, and muscarine exert a stiffening effect similar to that of acetylcholine (ACh), although the time course of their actions varies widely. 3. Atropine induced stiffening and blocked and responses to muscarine and MeACh. The responses to MeACh were blocked also by 4-diphenylacetoxy-N-methylpiperidine, suggesting the presence in the ligament of type M3 muscarinic receptors, in addition to nicotinic ones. d-Tubocurarine induced stiffness of the ligament and failed to block the responses to ACh and nicotine. 4. While ACh induced only a slight desensitization, CCh caused a long-lasting blockade of the stiffening effects of the cholinergic agonists. This shows that the receptors for ACh have a site or sites that recognize the ester moieties of these molecules. 5. Eserine and neostigmine potentiate the responses to acetylcholine, indicating the presence of acetylcholinesterase in the ligament. 6. beta-Phenylethylamine, epinephrine, norepinephrine, and dopamine induce diphasic responses; usually a brief softening followed by a slow and irreversible stiffening of the ligament. 7. In contrast to the above, tyramine and octopamine elicit a simple softening of ligaments which are stiff as a result of handling or by exposure to cholinergic agonists. However, tyramine and octopamine do not soften ligaments which become stiff as a result of exposure to adrenergic agonists.

Acetylcholine↗
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↗