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Biomedical subjects

J Quesada

Publications and source records attributed to J Quesada.

At least 19 recordsLinked to original sources
PubMed2000

When obesity is desirable: a longitudinal study of the Miami HIV-1-infected drug abusers (MIDAS) cohort.

Despite widespread nutrient deficiencies, a substantial proportion of the MIDAS cohort exhibits obesity, which has been linked to immune dysregulation in other clinical settings. Herein, the effects of obesity on immune function, disease progression, and mortality were evaluated longitudinally in 125 HIV-1-seropositive drug users, with comparison measures in 148 HIV-1-seronegative controls. Data were collected at a community clinic from 1992 to 1996, before administration of highly active antiretroviral therapy. Results indicated that overweight/obesity, defined as body mass index (BMI; kg/m2) > or =27, was evident in 18% of the HIV-1-seropositive patients and 29% of the seronegative patients. At baseline, no significant immunologic differences were observed among lean, nonobese, and obese groups. Over an 18-month period, 60.5% of the nonobese HIV-1-seropositive patients exhibited a 25% decline in CD4 cell count, compared with 18% of the obese patients (p<.004). During the follow-up period, 38% of the lean and 13% of the nonobese study subjects died of HIV-1-related causes. Measurements of BMI were inversely associated with progression to death, independent of CD4 count <200 cells/mm3 (p<.02). These data suggest that mild-to-moderate obesity in HIV-1-infected chronic drug users does not impair immune function and is associated with better HIV-1-related survival.

Adult↗
PubMed1999

Ontogeny of renal renin in congenital hypothyroid rats.

In the present study we have found age-related differences between the renal renin activity (RRA) and the immunoreactive renal renin (IRR) profiles during the neonatal development of the rat. RRA was markedly greater in newborn rats than in adult ones, while IRR was low at birth and progressively increased until adulthood. These observations suggest the existence of a control mechanism operating either at the level of the translation of the template or at a post-translational level which varies throughout the development. Since thyroid hormones have been demonstrated to affect several renin-angiotensin components, the neonatal RRA and IRR profiles in congenital hypothyroid rats were evaluated to determine whether renal renin activity or its synthesis could be endogenously regulated by thyroid hormones in the early stages of life. Although significant differences were observed in the RRA profiles of congenital hypothyroid and control rats, no changes were found in the relative amount of immunoreactive protein. These findings indicate that thyroid hormone deficiency does not directly affect renal renin expression during the critical period of the normal morpho-functional development of the newborn.

Aging↗
PubMed1998

Ozonation Products of Organosolvolytic Extracts from Vegetal Materials.

The ozonation of lignin in an organic solution was used to produce oxyaromatic compounds. Corn (Zea mays) stalk and poplar (Populus deltoides) wood lignin solutions (organosolvolytic juices) obtained from their respective autohydrolyzed materials and an organosolv lignin were treated with ozone, and the time course trend of the identified reaction products was studied. GC/MS and GC/FID were used to identify and quantify (internal standard method) the reaction products. The following acids were identified: glycolic, oxalic, malic, glyceric, p-hydroxybenzoic, and vanillic. In addition, p-hydroxybenzaldehyde, vanillin, syringaldehyde, and hydroquinone were also identified. All the oxyaromatic aldehydes reached maximum yields at short reaction times (between 1 and 8 min). These results were used to determine the ratio between the different phenylpropane units of their constitutive lignins. The ratio of p-hydroxyphenyl:guaiacyl:syringyl units for corn stalk, poplar wood, and organosolv lignins was 5.3:2:1, 0.1:1:1.1, and 0:1:1.1, respectively.

Journal Article↗
PubMed1998

Suffering child: an embodiment of war and its aftermath in post-Sandinista Nicaragua.

This article considers how the ripple effects of war and its aftermath are embodied and lived even after being mediated by time, space, and social status. Through a case study of a Nicaraguan boy and his natal family, I argue that the legacy of war, structural violence, and endemic poverty are chronic and lingering and emerge from internationally and locally produced traumatogenic social relations. I use a phenomenological approach to distress to minimize the clinical tendency to pathologize individual sufferers, and to illuminate the destructive capacities of politically and historically produced conditions of social "normal abnormality." The continuum of lived experience of social suffering is poignantly articulated by a member of one of society's most vulnerable sectors, a ten-year-old child.

Child↗
PubMed1995

Immunoglobulin E levels in relationship to HIV-1 disease, route of infection, and vitamin E status.

Our recent studies have demonstrated that in early HIV-1 infection, elevation of plasma immunoglobulin E (IgE) levels precedes the decline of CD4 cell count and is influenced by vitamin E status. In order to further investigate the role of IgE elevation in HIV-1 infection, we determined IgE levels in HIV-1-seropositive and -seronegative intravenous drug users (IDUs) (n = 38), in relationship to cellular and humoral immune function, liver enzymes, and vitamin E status. To examine the possible impact of the route of HIV-1 infection on IgE levels, comparisons between the cohorts of the HIV-1-seropositive and -seronegative IDUs and homosexual men (n = 45) were also conducted. All HIV-1-seropositive participants had significantly higher (P = 0.003) IgE levels than the HIV-1-seronegative subjects. The HIV-1-seropositive IDUs, moreover, demonstrated significantly higher (P = 0.01) IgE levels than HIV-1-seropositive homosexual men, despite similar CD4 cell counts. Stepwise regression analysis was used to evaluate the possible variables contributing to the IgE variation. HIV-1 status (P = 0.0009), intravenous drug use (P = 0.014), CD8 cell counts (P = 0.0001), plasma level of vitamin E (P = 0.006), and alcohol intake (P = 0.047) were significant, accounting for 71% of the IgE elevation. These findings suggest that IgE may serve as a sensitive marker to reflect the evolution of HIV-1 disease in individuals from different risk groups.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Charge heterogeneity of the AT1 angiotensin II receptor subtype in the rat lung.

In order to obtain more information on the molecular structure of the angiotensin II (Ang II) binding sites from whole rat lung membranes these were characterized by isoelectric focusing (IEF) and SDS-PAGE. Whereas a single population of Ang II receptor sites was identified (Kd = 2.2 +/- 0.3 nmol/l; Bmax = 203.9 +/- 15.8 fmol/mg protein) by Scatchard analysis, using IEF three Ang II binding isoforms were observed; a major band which migrated to isoelectric point (pI) 6.7, and two minor bands with pI values of 6.5 and 6.3. Specific binding of 125I-Ang II to rat lung membrane preparations was sensitive to Losartan, a non-peptide AT1 receptor subtype antagonist, but was unaffected by the AT2 receptor subtype antagonist CGP42112A. Immunoblotting analyses on SDS gels, using a monoclonal antibody specific to the AT1 receptor, showed two immunoreactive protein species of 45 and 48 kDa. Enzymic deglycosylation using recombinant N-glycanase did not alter the molecular weight patterns of the AT1 receptor subtype. The results of the present study demonstrated that the Ang II receptor population in the whole rat lung consists solely of the AT1 receptor subtype and that the AT2 receptor subtype is absent. In addition, the data showed the existence of charge heterogeneity of the AT1 receptor subtype, and suggest that glycosylation probably does not contribute to its charge heterogeneity.

Angiotensin II↗
PubMed1995

HIV/AIDS in Costa Rica: epidemiological and sociological features, 1993.

Acquired immunodeficiency syndrome (AIDS) was first detected in Costa Rica in 1983. For four years most known cases were in hemophiliac men. Thereafter, AIDS in homosexual and bisexual men predominated. By December 31 of 1993, 563 persons had been diagnosed with the syndrome, 71% of them homosexual and bisexual men, 10% heterosexual men and women, 6% hemophiliacs, 2% intravenous drug abusers (IVDA's), 2% women and men who had blood transfusions, 1.4% infants born to HIV-infected mothers and 7% unknown. The epidemics in homosexual/bisexual men and in heterosexual women and men are rising; cases in infants and in persons who received blood or coagulation factors, are stagnant. The steady increase in AIDS among women is linked to exposure to bisexual partners. The moderate nature of the national epidemic reflects, in part, the low incidence of IVDA, the universal screening of blood donors for antibodies to the human immunodeficiency virus (HIV) since 1985, and the prompt banning of unsafe coagulation factors. The projection of AIDS for the year 2000 is 2,304 cases (606 accumulated incidence per million inhabitants). A national educational campaign, radio and television programs and other preventive actions, apparently did not influence the rate of receptive anal intercourse without condom (about 80%) during 9 years of the epidemic. Persons with HIV/AIDS often are deprived of social and medical benefits or are subjected to harassment and exploitation by the health sector. More efficient prevention must target children, adolescents and adults in reproductive age, to promote safer lifestyles, through education and counseling effected through primary health care.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Effect of low-iodine diet and propylthiouracil on glycolytic enzymes in brain areas of adult rats.

Glycolytic activity of five brain areas in the rat was studied under two hypothyroid states: (1) induced by low-iodine diet from weaning, and (2) induced by propylthiouracil. The areas studied were the anterior cortex, amygdala, hypothalamus, septum and hippocampus. A low-iodine diet induced a decrease of pyruvate kinase activity in three region and of phosphofructokinase in the hippocampus, while hexokinase increased in both the amygdala and septum. Propylthiouracil treatment produced an increase in hexokinase activity in the hypothalamus and septum, and a decrease in the anterior cortex, while phosphofructokinase decreased significantly in the hippocampus. No significant changes of lactate dehydrogenase activity were observed. The correlation between the results and type of hypothyroidism is discussed.

Animals↗
PubMed1988

Immunocytochemical and ultrastructural characterization of the cell types in the adenohypophysis of Sparus aurata L. (teleost).

The structure and immunocytochemistry of the adenohypophysis of sexually mature male specimens of Sparus aurata (gilthead sea bream) were studied. The adenohypophysis was composed of rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). In the RPD the prolactin cells were organized into follicles which occupied a very reduced area as corresponds to that in saltwater fishes; the corticotropic cells were surrounding the pars nervosa branches and the prolactin follicles. The PPD showed somatotropic, gonadotropic, and thyrotropic cells. The somatotropic cells were isolated, clustered, or surrounding the pars nervosa branches. Only one polymorphic cell type of gonadotropic cells was found in the PPD ventral and dorsal areas and around the PI. The PI was composed mainly of melanotropic cells and a PAS-positive cell layer adjacent to the neurohypophysis. The ultrastructure of the presumptive endocrine cells was reported and their distribution was discussed in relation to those of other teleosts.

Adrenocorticotropic Hormone↗
PubMed1987

Activities of glycolytic enzymes in some brain areas of thyroidectomized rats and their response to replacement therapy.

Glycolytic metabolism has been assessed by studying a set of key enzymes, in anterior cortex, amygdala, hypothalamus septum and hippocampus, in thyroidectomized rats. The reversibility of the changes induced by the thyroidectomy has been assessed by replacement therapy. In thyroidectomized rats the hexokinase activity was significantly decreased in anterior cortex and hypothalamus. The increase in phosphofructokinase and pyruvate kinase activity was probably due to an increase in cellular energy requirements. Hexokinase activity was best restored by treatment with L-thyroxine (T4) or T4+ propylthiouracil (PTU). The low response of pyruvate kinase activity in all treated animals could suggest that this metabolic step is the least reversible.

Animals↗
PubMed1986

Difluoromethylornithine and leukocyte interferon: a phase I study in cancer patients.

Difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, and human leukocyte interferon (IFN-alpha) have synergistic anti-tumor activities in vivo in B 16 melanoma and in vitro against several human cancer cell lines. We have, therefore, carried out a phase I combination study with DFMO plus alpha interferon in the following manner: DFMO was maintained at a steady dose for the first four levels, 1.5 g/m2 every 6 hr. IFN-alpha was given in 100% increments ranging from 0.4 X 10(6)U/m2 to 3.2 X 10(6)U/m2 i.m. daily. At the fifth dose level both IFN-alpha and DFMO were raised by 100 and 50% respectively. From levels one through four the combination was well tolerated with no dose interruptions required because of G.I. toxicity or myelosuppression. However, at dose level 5, one-third of the patients required dose cessation and decrease due to nausea, vomiting and diarrhea. We conclude that for phase II studies the maximal tolerated dose is 3.2 million units of IFN-alpha/m2 and 1.5 g/m2 of DFMO every 6 hr. Of 12 patients with metastatic melanoma, 2 had partial remissions lasting 58+ and 36+ weeks. Two additional patients had minor responses lasting 29 and 32+ weeks. Minor responses were observed in a patient with colon carcinoma and a patient with renal carcinoma. The clinical activity of the combination is currently being pursued in a phase II study among patients with metastatic malignant melanoma.

Adult↗
PubMed1986

Initial clinical studies with copovithane.

Copovithane is a new copolymer of low molecular weight and with a significant in vivo antitumor activity in preclinical trials. The mechanism of action is unknown. Ninety-one patients with various metastatic neoplasms beyond the curable stage were treated with copovithane by weekly intravenous administration. Dose levels ranged from 1 to 33 g/m2/week. No dose-limiting toxicity was reached. Tolerance was excellent, with minor fatigue, occasional nausea, and intermittent proteinuria as the only significant side effects in less than 25% of patients. Two patients achieved a partial remission, and five patients reached minor responses during therapy. Antitumor effects were noted only in cutaneous and subcutaneous metastases. Extensive immunologic evaluation revealed some improvement in helper:suppressor T cell ratio, in vitro cytotoxicity tests, and lymphocyte blastogenic responses in patients treated at intermediate levels. The immunologic testing also suggested that the higher dose levels (22-33 g/m2 weekly) might adversely affect the immune response. The clinical relevance of these changes is uncertain. Phase II clinical trials are recommended utilizing weekly doses between 10 and 15 g/m2.

Adult↗
PubMed1986

Production of B cell growth factor(s) by neoplastic B cells from hairy cell leukemia patients.

Recent studies have shown that normal human T cells contain a high-molecular-weight (mol wt) protein exhibiting B cell growth factor (BCGF) activity. Other studies have shown that virally transformed human B cells also secrete a high-mol-wt BCGF-like molecule in vitro. We have studied neoplastic B cells from patients with untreated hairy cell leukemia (HCL) to ascertain whether such cytoplasmic BCGF activity is present in the tumor cells. Studies on HCL cells from four patients indicated that BCGF-like activity was in fact present in the cytosolic extracts when tested on autochthonous HCL cells as well as on normal BCGF-dependent human B cell lines. Chromatographic analysis indicated that the BCGF activity from HCL cells was similar in mol wt as well as function to the normal T cell-derived cytosolic BCGF activity. These studies suggest that HCL cells contain and, in some cases, secrete a high-mol-wt growth factor that can be autostimulatory and appears to resemble a similar growth factor molecule found in normal human T cells.

B-Lymphocytes↗
PubMed1985

Growth factor-mediated tumor cell proliferation in hairy cell leukemia.

Leukemic B cells from seven patients with hairy cell leukemia (HCL), six of which contained the Tac antigen, were assayed in vitro for growth factor-mediated cell proliferation. The HCL cells showed typical phenotypic profiles by monoclonal antibody analysis. The tumor cells, which do not grow spontaneously in vitro, were found to proliferate in all but one case in response to partially purified B cell growth factor (BCGF) without anti-mu or Sac activation. Recombinant interleukin 2 however produced only a marginal response and could not support leukemic cell growth in vitro. BCGF, however, did stimulate in vitro cell growth and supported the establishment of continuous (greater than 60 d in vitro) in four of the seven HCL cases.

Antigens, Neoplasm↗
PubMed1985

Effect of thyroid hormones on the glycolytic enzyme activity in brain areas of the rat.

The glycolytic metabolism through the key enzymes, hexokinase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase, have been studied in the brain areas: anterior cortex, amygdala, hypothalamus, septum and hippocampus in adult rats with pharmacologically induced hyperthyroidism. The oxidative metabolism of glucose is accelerated in most brain areas by treatment with high doses of T3, as is shown by the increase in HK activity, approaching normality on reducing the dose. This decrease can also by observed in the PFK activity through the effect of assayed doses of thyroxine. The anterior cortex is the only brain area that does not show significant variations of PK activity through the effects of treatment with thyroid hormones. On the other hand, a general inhibition of the glycolytic anaerobic pathway by treatment with T3 was observed.

Amygdala↗