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Biomedical subjects

M Maldonado

Publications and source records attributed to M Maldonado.

At least 73 records · Page 4Linked to original sources
PubMed1992

Effects of growth hormone in patients receiving total parenteral nutrition following major gastrointestinal surgery.

The purpose of the present study was to determine whether the administration of a biosynthetic human growth hormone was capable of enhancing the efficacy of total parenteral nutrition. Patients (n = 38) who had undergone major gastrointestinal surgery were randomly divided into two groups. Group I (n = 20) treated only with PN, and Group II (n = 18) treated as in Group I plus human growth hormone (4 IU daily). Our study shows that the administration of human growth hormone produces a statistically significant increase in serum levels of growth hormone, somatomedin-C, transferrin, albumin and total proteins. It also causes a positive nitrogen balance from the first 24 hours onward. These findings suggest that the administration of human growth hormone produces an increase in protein synthesis, perhaps through somatomedin-C as mediator.

Adult↗
PubMed1990

Oxygen-derived free radicals mediate the cutaneous necrotizing vasculitis induced by epinephrine in endotoxin-primed rabbits.

To assess the possible role of oxygen-derived free radical in the pathogenesis of cutaneous necrotizing vasculitis (Thomas reaction) induced by epinephrine in endotoxin-primed rabbits, animals were treated with superoxide dismutase (intraperitoneal or local), catalase, allopurinol, or ibuprofen 2 h before inducing the reaction. This is done by an earlobe intravenous injection (10 micrograms) of endotoxin followed by an intradermal injection (100 micrograms) of epinephrine in the shaved abdomen; 18-24 h later, a hemorrhagic-necrotic lesion can be observed at the site of the epinephrine injection. The reaction was completely inhibited by superoxide dismutase, catalase, and ibuprofen, while allopurinol afforded only partial protection. Thus, oxyradicals seem to participate in the pathogenesis of this reaction.

Animals↗
PubMed1989

Oral controlled-release morphine sulfate. Analgesic efficacy and side effects of a 100-mg tablet in cancer pain patients.

Fifty-one cancer pain patients with limited opioid exposure participated in a randomized, double-blind, repeated-dose, parallel-group comparison of two dosage strengths of the controlled-release morphine preparation, MS Contin tablets (The Purdue Frederick Company, Norwalk, CT). The patients were first stabilized on immediate-release oral morphine 30 mg every 4 hours, with 15 mg available every 2 hours as needed for breakthrough pain ("rescue" dose). Each patient then received either one 100 mg MS Contin tablet or three 30-mg MS Contin tablets every 12 hours, with rescue medication as needed, for 3 days. Analysis of study power revealed sufficient sensitivity to detect clinically relevant differences in pain intensity and use of rescue medication. The two tablet strengths yielded similar pain relief, use of rescue medication, and frequency of side effects. In addition, pain and use of rescue medication did not change from the beginning to the end of the 12-hour dosing intervals in either group. In the study population as a whole, pain intensity was lower and total morphine intake higher during the period on controlled-release morphine. These data establish comparable analgesic efficacy and side effect potential of these two dosage strengths and confirm a 12-hour duration of effect for both. The improved analgesia on the controlled-release morphine may be attributable to increased consumption of drug resulting from improved compliance.

Administration, Oral↗
PubMed1989

Sadness, depression and social reciprocity in highland Ecuador.

Pena or llaqui in the Quechua area of Ecuador refers to a state of sadness and depression experienced following a variety of life events. This paper tries to explain why there is an elaborate discourse on such feelings in this culture. It is argued that the Quechuas stress the ideal of social reciprocity in human encounters and are accordingly sensitive to disturbances in social relationships. We observe that they pay a great deal of attention to the victim of pena and that they try to improve relationships with the social network and the family. The indigenous theory on pena also points to the importance of bodily elements closely associated to the psychological conditions. We conclude that knowledge of status relationships are important to understand the emotions experienced when loss occurs.

Body Image↗
PubMed1989

Cardiomyopathy in Cebus apella monkeys experimentally infected with Trypanosoma cruzi.

Twenty four Cebus apella monkeys were studied as a biological model for the cardiac chronic form of Chagas' disease. Twelve were inoculated with Trypanosoma cruzi trypomastigotes, seven with the Brazilian Y strain and five with the Argentinian RA strain. Twelve monkeys were uninfected controls. The following parameters were studied: body weight, body temperature, direct parasitemia, xenodiagnosis, specific antibodies by IFA, clinical chemistry, hematology, ECG and chest X-ray. Three monkeys infected with Y strain were sacrificed at 4 months and 4 monkeys at 12 months after inoculation. Monkeys inoculated with RA strain were sacrificed at 48 months. Direct parasitemia was positive within a week after inoculation in all monkeys. Xenodiagnosis was positive until 49.0 +/- 3.0 and 79.0 +/- 6.0 weeks p.i. for Y and RA strains, respectively. In all inoculated monkeys an increase in antibody titers was detected within 3 weeks after inoculation. In all monkeys inoculated with the Y strain and 3/5 with the RA strain abnormal ECGs were observed within 1 or 2 weeks p.i., becoming more severe in the chronic phase. Y strain inoculated monkeys sacrificed at 4 months presented only a slight concentric hypertrophy of the heart left ventricle. Those sacrificed at 12 months had concentric left ventricle hypertrophy and 3/4 had an aneurism of the apex. Four out of 5 RA strain inoculated monkeys had an enlarged, flaccid heart; 3/5 aneurism of the apex and 2/5 concentric hypertrophy of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Adaptive regulation of hepatic bile salt transport. Effect of prolonged bile salt depletion in the rat.

Exposure of the liver to increased bile salt flux can increase the bile salt maximum secretory rate (SRm), presumably through the induction of new transport sites. The converse, i.e., the down-regulation of SRm upon bile salt deprivation, has not been demonstrated. We examined the effects of bile salt depletion for 24 h and 48 h on taurocholate SRm and bromsulphalein (BSP) SRm, and on [14C]taurocholate binding to isolated liver surface membranes in unrestrained external biliary fistula rats. Taurocholate SRm was significantly decreased by 35% and 51% in 24-h-depleted and 48-h-depleted rats, respectively, compared with control, sham-operated rats. Maximal taurocholate concentration in bile was also significantly lower in bile salt-deprived rats. In contrast, BSP SRm was not significantly different between depleted animals and controls. Bile salt depletion for 24 h and 48 h did not significantly alter liver surface membrane protein recovery and membrane enzyme specific activity, including Na+ + K+-ATPase. Specific [14C]taurocholate binding to liver surface membranes was significantly decreased by 25% in 24-h-depleted rats compared with control rats. In contrast to taurocholate SRm, bile salt depletion for 48 h did not result in further reduction of specific taurocholate binding sites. This study demonstrates that taurocholate SRm progressively decreased in 24-h- and 48-h-bile salt-depleted rats, this being consistent with adaptive down-regulation of hepatic bile salt transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Acute Chagas' disease in non-human primates. 1. Chronology of clinical events, clinical chemistry, ECG, radiology, parasitemia, and immunological parameters in the Cebus apella monkey.

Forty Cebus apella monkeys free from Chagas' disease were subcutaneously infected with 3 x 10(5) trypomastigotes of the Ypsilon strain of T. cruzi and followed-up for 6 months. Seventeen monkeys were controls. Body weight, temperature, direct parasitemia (DP), IgM and IgG were determined weekly. Hematology was performed weekly up to day 40 p.i. and monthly thereafter. Clinical chemistry was performed every two weeks up to day 33 p.i. and monthly thereafter. ECG was performed weekly up to day 47 p.i. and at 2,3, and 6 months p.i. Chest X-ray was done at 45 days, 4 and 6 months p.i. Xenodiagnosis was only performed after two negative DP. All infected monkeys developed fever, beginning 6.0 +/- 0.6 day p.i. and lasting 21.9 +/- 6.7 days, and lost 14% of their body weight the first month, 11% the third month and 7% the 6th month. DP was already detected 4.4 +/- 0.29 days after infection and it was detectable in all monkeys up to 96.0 +/- 6.9 days p.i. Cyclical peaks of parasitemia were observed throughout the study. IgM and IgG titers which permitted a diagnosis of T. cruzi infection occurred at 33.0 +/- 2.9 days p.i., respectively. Fifty-seven percent of infected monkeys presented ECG alterations one week after inoculation reaching a maximum of 86% at the third week. A normocytic, normochromic anemia was observed in all monkeys being significantly (p less than 0.02) more severe in the infected animals. No effects of T. cruzi on the clinical chemistry were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Body measurements, hematology, and serum chemistry values of the adult Cebus apella monkey.

Body measurements, hematology, and serum chemistry values were studied in 40 captured male and female Cebus apella monkeys. Some significant dimorphism with male predominance was found. Significant differences were also found for hemoglobin and red cell volume between males and females. Differential white blood cell counts indicated a marked predominance of lymphocytes and high values of gamma globulin in both sexes.

Animals↗
PubMed1985

Ethnicity and life event cognitive appraisals and experiences.

This study compared the cognitive appraisals and incident ratings of urban American Indians (N = 50), Anglo-Americans (N = 50), and Hispanics (N = 47) on a revised version of the Social Readjustment Rating Scale (SRRS). Results indicated no overall significant differences among the three ethnic groups. However, on comparison of individual life events items, the groups differed significantly on the cognitive appraisal of 8 items and on the incidence of 10 items. Of these items, only 2 overlapped between cognitive appraisals and actual incidence. Results are discussed in terms of potential use of the revised SRRS with these ethnic groups in future research on the relationship between life events and physical and psychological disorders.

Adult↗
PubMed1985

Anchorage of collagen-tailed acetylcholinesterase to the extracellular matrix is mediated by heparan sulfate proteoglycans.

Heparan sulfate and heparin, two sulfated glycosaminoglycans (GAGs), extracted collagen-tailed acetylcholinesterase (AChE) from the extracellular matrix (ECM) of the electric organ of Discopyge tschudii. The effect of heparan sulfate and heparin was abolished by protamine; other GAGs could not extract the esterase. The solubilization of the asymmetric AChE apparently occurs through the formation of a soluble AChE-GAG complex of 30S. Heparitinase treatment but not chondroitinase ABC treatment of the ECM released asymmetric AChE forms. This provides direct evidence for the vivo interaction between asymmetric AChE and heparan sulfate residues of the ECM. Biochemical analysis of the electric organ ECM showed that sulfated GAGs bound to proteoglycans account for 5% of the total basal lamina. Approximately 20% of the total GAGs were susceptible to heparitinase or nitrous acid oxidation which degrades specifically heparan sulfates, and approximately 80% were susceptible to digestion with chondroitinase ABC, which degrades chondroitin-4 and -6 sulfates and dermatan sulfate. Our experiments provide evidence that asymmetric AChE and carbohydrate components of proteoglycans are associated in the ECM; they also indicate that a heparan sulfate proteoglycan is involved in the anchorage of the collagen-tailed AChE to the synaptic basal lamina.

Acetylcholinesterase↗
PubMed1985

Antiemetic efficacy of high-dose dexamethasone versus placebo in patients receiving cisplatin-based chemotherapy: a randomized double-blind controlled clinical trial.

The antiemetic effect of short courses of high-dose dexamethasone was compared with that of placebo in 64 patients receiving cisplatin-based cancer chemotherapy, in a double-blind randomized clinical trial. All patients were receiving cisplatin for the first time. Dexamethasone was given intravenously (IV) at a dose of 20 mg, two hours before and 3, 6, 9, and 12 hours after chemotherapy. Patients were crossed over to dexamethasone on the second cycle of chemotherapy if they experienced unacceptable gastrointestinal (GI) toxicity after initial treatment with placebo. Nine of 32 patients receiving dexamethasone and seven of 32 patients receiving placebo did not vomit. The median duration of nausea was significantly shorter (one-half hour) for the dexamethasone-treated group compared with that of placebo (31/2 hours). The number of patients who experienced unacceptable GI toxicity was significantly greater (53%) for the placebo patients than for those treated with dexamethasone (25%). Patients crossing over to dexamethasone after initially receiving placebo had a median duration of nausea of 11/2 hours and 24% did not vomit, results comparable to the first treatment group. We conclude that high-dose dexamethasone is only minimally effective as an antiemetic agent in patients receiving cisplatin-based chemotherapy.

Adult↗
PubMed1984

The electric organ of Discopyge tschudii: its innervated face and the biology of acetylcholinesterase.

An ultrastructural, histochemical, and biochemical study of the electric organ of the South American Torpedinid ray, Discopyge tschudii, was carried out. Fine structural cytochemical localization of acetylcholinesterase (AChE) indicated that most of the esterase was associated with the basal lamina. Electron microscopy indicated no marked differences in the electrocyte ultrastructure between Discopyge and Torpedo californica. Discopyge electric organ possessed three molecular forms, two asymmetric forms (16 S and 13 S) and one globular hydrophobic form (6.5 S). The asymmetric 16 S AChE form was solubilized by heparin, a sulfated glycosaminoglycan, suggesting that heparin-like macromolecules are involved in the binding of the enzyme to the basal lamina. Our results show that cell-free translated AChE peptides, synthesized using Discopyge electric organ poly(A+) RNA, correspond to a main band of 62,000 daltons which probably represents the catalytic subunit of the asymmetric AChE.

Acetylcholinesterase↗
PubMed1984

Age-related responses of skeletal muscle after ectopic innervation, with particular reference to 16S acetylcholinesterase, in adult rats.

The formation of ectopic junctions between the foreign fibular nerve and the soleus muscle of young (35-day-old) and mature (200-day-old) adult rats was induced by severing the normal nerve 4 weeks after implanting the foreign nerve. The various molecular forms of acetylcholinesterase (AChE) were studied both at the implanted region and at the original denervated endplates. The velocity of contraction was also studied. In young rats the 16S form was first detected in the ectopic junctions around day 5 after reinnervation; this form rapidly increased during the following weeks, reaching a plateau by day 20. By contrast, in mature rats the appearance of the 16S AChE was dramatically delayed; in fact, it could not be observed before day 80 after reinnervation. (The 16S AChE form appeared at day 20 after reinnervation in the original denervated endplates of young rats; however, at the same time, no effect was observed in mature animals.) The original, slow muscle fibers of the soleus became faster upon reinnervation; this change occurred also much earlier in younger than in mature rats. Our results indicate a loss of plasticity in the skeletal muscle of mature rats. We suggest caution in the use of the ectopic innervation model to study development in mature adult rats.

Acetylcholinesterase↗
PubMed1982

Gastricsin and cathepsin D in normal and hypertrophic human prostates.

The relative contents of gastricsinogen, the inactive zymogen precursor of gastric gastricsin (EC 3.4.23.3), and cathepsin D (EC 3.4.23.5) in normal and benign hyperplasia of the prostate gland have been determined. Gastricsinogen levels are significantly lower (0.116 +/- 0.02 U/gm. wet tissue) in the hyperplastic than in normal prostates (0.65 +/- 0.06 U/gm.). Conversely, cathepsin D levels are higher in the diseased (0.705 +/- 0.17 U/gm.) as opposed to normal prostatic tissue (0.39 +/- 0.12 U/gm.). The average gastricsin-cathepsin D differences between the 2 tissues (0.26 +/- 0.025 for normal prostates and -0.59 +/- 0.057 SEM for hyperplastic tissue) are also significantly different (p less than 0.001). It is suggested that the simple determination of these 2 acid proteinases in prostate homogenates could be used as alternative and complementary marker enzymes for the study of the physiopathologic status of the prostate gland.

Acid Phosphatase↗