Search PubMed⌕ Search

Biomedical subjects

J Figueroa

Publications and source records attributed to J Figueroa.

At least 37 records · Page 2Linked to original sources
PubMed1999

Transcription factor pit-1 expression is modulated upon seasonal acclimatization of eurythermal ectotherms: identification of two pit-1 genes in the carp.

A second Pit-1 gene in carp (Cyprinus carpio), including the complete structural gene and 1.1 kb of promoter region, was identified and completely sequenced. The exon-intron structure was determined, and reverse transcription-polymerase chain reaction (RT-PCR) experiments suggest that only one Pit-1 splice variant is present in carp pituitary. The effect of seasonal acclimatization on the extent of Pit-1 gene expression was studied in summer- and winter-acclimatized carp. Quantitative RT-PCR analysis revealed a clear increase of Pit-1 mRNA in the pituitaries from summer-acclimatized carp compared with the winter-adapted fish. In situ hybridization of pituitary gland sections with riboprobes representing the complete 5'-transactivating region of carp Pit-1 depicted a significantly higher Pit-1 mRNA level in the rostral pars distalis of the summer-acclimatized fish where prolactin is expressed in a manner that resembles the seasonal increase observed in the proximal pars distalis and the pars intermedia. The cell- and temporal-specific transcription of Pit-1 supports its role in the molecular mechanisms that underly the acclimatization process undergone by eurythermal fish as a result of the physical effects of seasonal changes on their habitat.

Amino Acid Sequence↗
PubMed1999

Azaftig, a urinary proteoglycan from a cachectic cancer patient, causes profound weight loss in mice.

Cachexia is a complex medical condition characterized by significant weight loss associated with decreased body fat and protein; the condition may present itself with or without anorexia. We have isolated and partially characterized a proteoglycan (azaftig) from the urine of cancer and AIDS patients experiencing weight loss. When given to mice, the purified azaftig resulted in a significant decrease in body weight and body fat without any effect on appetite. The results of these studies show that azaftig may be one of the many factors participating in the emergence of the cachectic state.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Renal hemodynamic effects of nabumetone, sulindac, and placebo in patients with osteoarthritis.

We assessed the effects of nabumetone, sulindac, and placebo on renal function and renal excretion of vasodilatory prostaglandins in older female patients (age >50 years) with osteoarthritis and normal renal function. Using a prospective, crossover design, we compared the effects of nabumetone 2000 mg/d and sulindac 400 mg/d with placebo on glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary excretion of prostaglandin E2 and 6-keto-prostaglandin F1alpha in 12 patients. Urinary excretion of vasodilatory prostaglandins was not decreased after 14 days of treatment with either nabumetone or sulindac. Likewise, treatment with nabumetone or sulindac did not significantly alter renal function compared with placebo. There were no differences in mean changes in GFR or RPF from baseline after treatment with nabumetone or sulindac compared with placebo. The mean (+/- SD) changes in GFR from baseline were 0%+/-8% in patients receiving nabumetone, -8%+/-15% in patients receiving sulindac, and -7%+/-15% in patients receiving placebo. The results of this study demonstrate that treatment with nabumetone or sulindac caused no deterioration in renal function in older female patients with osteoarthritis and normal renal function.

6-Ketoprostaglandin F1 alpha↗
PubMed1999

APH-1, a POU homeobox gene expressed in the salt gland of the crustacean Artemia franciscana.

We characterized the first POU-homeoprotein in a crustacean (designated APH-1 for Artemia POU-Homeoprotein, EMBL Y15070). The amino acid sequence of the APH-1 POU-domain is identical, except for two residues, to that of the two class III POU proteins Cf1-a (Drosophila) and POU-M1 (Bombyx mori). Southern blot analysis suggests that crustaceans have only one class III POU gene. RT-PCR and whole-mount in situ hybridization show that APH-1 mRNA is present in larvae specifically in the salt gland, an organ which is involved in osmoregulation, and disappears in the adult.

Amino Acid Sequence↗
PubMed1999

Limited genetic diversity of Plasmodium falciparum in field isolates from Honduras.

The genetic diversity displayed by Plasmodiumfalciparum field isolates, the occurrence of variant forms of the parasite at different frequencies in different geographic areas, and the complexity of the infections represent major obstacles for the development of effective malaria control measures. However, since most of the existing studies have been performed in regions where P. falciparum transmission is high, little is known about the diversity and complexity of parasite populations circulating in areas of low malaria endemicity. We investigated the extent of genetic polymorphism in P. falciparum field isolates from Honduras, a region where its transmission is low and seasonal. Allelic diversity was analyzed in the highly polymorphic parasite genes encoding the merozoite surface proteins- (MSP-1) and -2 (MSP-2) and the glutamate-rich protein (GLURP) by the polymerase chain reaction. Gene polymorphism was also assessed in the EB200 region derived from the highly size polymorphic Pf332 gene. Limited size polymorphism was detected in all genes analyzed, with four and three variants for the MSP-1 and MSP-2 alleles, respectively, and two size variants for the GLURP and Pf332 genes. Moreover, based on the studied genetic markers, most infections consisted of only a few genetically distinct parasite clones. These results suggest that the P. falciparum parasite populations circulating in this region are genetically homogeneous and point to an association between the extent of parasite genetic diversity and the intensity of malaria transmission.

Alleles↗
PubMed1998

A novel centromere monospecific serum to a human autoepitope on the histone H3-like protein CENP-A.

Centromere autoantibodies are commonly found in the serum of patients with some systemic autoimmune diseases. Previous studies have shown that a major human centromere autoantigen is the histone H3-like protein CENP-A. Although the human cDNA has been cloned, native CENP-A has been neither isolated nor expressed in Escherichia coli, and specific antibodies to this chromatin-associated centromere protein are not available yet. In this report, a highly charged peptide on CENP-A (residues 3-17) was used to generate a monospecific antibody that reacts by immunoblots with the 17 kDa centromeric protein. Immunofluorescence analysis showed reactivity of this anti-CENP-A serum in several but not all mammalian culture cells analyzed, suggesting that the sequence of this histone-like centromere protein could be more variable throughout evolution than originally thought. Selective extractions of human placenta nuclear proteins and immunoblot analysis indicated that CENP-A behaves in a similar way to the core histone polypeptides after nuclease digestion of chromatin. Also, immunoblot analysis demonstrated that the CENP-A peptide used as immunogen is a target region on the CENP-A molecule in several but not all CREST patients analyzed with high titers of autoantibodies to the centromere. Lastly, we found that in Jurkat cells induced to apoptosis, CENP-A remains associated with the centromere, in contrast to other human autoantigens studied during apoptosis.

Amino Acid Sequence↗
PubMed1998

Microinjection of antibodies to centromere protein CENP-A arrests cells in interphase but does not prevent mitosis.

Centromere protein CENP-A is a histone H3-like protein associated specifically with the centromere and represents one of the human autoantigens identified by sera taken from patients with the CREST variant of progressive systemic sclerosis. Injection of whole human autoimmune serum to the centromere into interphase cells disrupts some mitotic events. It has been assumed that this effect is due to CENP-E and CENP-C autoantigens, because of the effects of injecting monospecific sera to those proteins into culture cells. Here we have used an antibody raised against an N-terminal peptide of the human autoantigen CENP-A to determine its function in mitosis and during cell cycle progression. Affinity-purified anti-CENP-A antibodies injected into the nucleus during the early replication stages of the cell cycle caused cells to arrest in interphase before mitosis. These cells showed highly condensed small nuclei, a granular cytoplasm and loss of their division capability. On the other hand, microinjection of nocodazole-blocked HeLa cells in mitosis resulted in the typical punctate staining pattern of CENP-A for centromeres during different stages of mitosis and apparently normal cell division. This was corroborated by time-lapse imaging microscopy analysis of mid-interphase-injected cells, revealing that they undergo mitosis and divide properly. However, a significant delay throughout the progression of mitotic stages was observed. These results suggest that CENP-A is involved predominantly in an essential interphase event at the centromere before mitosis. This may include chromatin assembly at the kinetochore coordinate with late replication of satellite DNA to form an active centromere.

Animals↗
PubMed1998

Polysome-like structures in the chromatoid body of rat spermatids.

A procedure for isolating the chromatoid body from the testis of 40-day-old rats was developed. Electron-microscopical analysis indicated that about 70% of the isolated organelles were chromatoid bodies, while the remaining structures corresponded to dense bodies and probably to satellites. Negative staining of the isolated organelles revealed the presence of polysome-like structures in about 20% of the chromatoid bodies suggesting that the polysomes were not due to contamination with cytoplasmic polysomes. Moreover, the presence of RNA in the stroma of the chromatoid body was confirmed by RNAse-gold staining. Preliminary electrophoretic analysis of the RNA extracted from the organelles revealed the presence of a complex population of RNAs including 5.8 and 5 S ribosomal RNAs but no tRNA.

Animals↗
PubMed1998

Effect of seasonal acclimatization on the expression of the carp transcription factor Pit-1.

We isolated a clone comprising four exons of the carp Pit-1 gene. Using synthetic oligonucleotide probes derived from the carp Pit-1 sequence Pit-1 expression was assessed by in situ hybridization in pituitary sections from summer- and winter-acclimatized carp. Semiquantitative analyses of the hybridization signals revealed a significant higher Pit-1 expression in the proximal pars distalis (PPD) and pars intermedia (PI) of the pituitary glands from summer-acclimatized carp, compared to the winter-acclimatized fish. In both adaptive states, relative to the PPD and PI, only a basal Pit-1 expression was detected in the rostral pars distalis. Thus, during seasonal acclimatization of an eurythermal fish, Pit-1 seems to be involved in the mechanisms that underlie the compensatory response.

Acclimatization↗
PubMed1998

A randomized controlled trial comparing nonoxynol-9 lubricated condoms with silicone lubricated condoms for prophylaxis.

OBJECTIVE: We tested the effect of nonoxynol-9 (N-9) in condom lubrication on the risk of acquiring STD and genital discomfort. METHODS: The study was a triple masked, randomised controlled trial comparing N-9 lubricated condoms with plain silicone lubricated condoms among Dominican female sex workers. RESULTS: Randomisation provided two groups (313 for N-9 and 322 for plain) similar in baseline characteristics, but extensive loss to follow up occurred (56 women in each group completed the 24 week follow up). Most vaginal acts with clients were protected with condoms (99% of vaginal sex) but fewer acts with non-clients were protected (43% of vaginal sex). No significant differences occurred in rates of cervical infections (N-9 = 3.4 per 100 person months v plain = 2.8), trichomoniasis (N-9 = 2.8 v plain = 3.6), or discomfort rates (N-9 = 0.82 v plain = 0.92). CONCLUSIONS: Plain silicone lubricated condoms are as effective as N-9 lubricated condoms, cost less, have longer expected shelf life, and therefore may be the better condom to provide.

Adolescent↗
PubMed1998

Growth Hormone (GH) but not IGF-I-Secretion is Stimulated in Aged Rats by Chronic Hexarelin and GHRP-6 administration.

The present studies were designed to investigate in aged rats (22-24 months old) the effectiveness and specificity of acute hexarelin (HEXA) administration on the release of growth hormone (GH), the minimal dose of the peptide that produces the maximal GH secretion and the effects of long term treatment with HEXA or growth hormone releasing peptide (GHRP-6) on plasma levels of GH and IGF-1. To select the appropriate anesthetic to obtain serial blood samples, the GH releasing activity of HEXA (30 µg/kg i.v.) was tested in young rats anesthetized with tribromoethanol and ketamine-xylazine, and the results were compared with those obtained from conscious freely moving rats. When compared to the changes found in conscious rats, the GH-response to HEXA was increased by ketamine-xylazine anesthesia, while it was decreased by tribromoethanol. Therefore, all subsequent experiments were performed in conscious freely moving rats. To determine the minimal effective dose of HEXA and GHRP-6 in aged animals, different doses (5, 10, 20, 40, and 80 µg/kg) of either HEXA or GHRP-6 were administered subcutaneously to young and aged rats. It was found that 20 µg/kg bw of HEXA or GHRP-6 was the minimal dose producing the maximal GH response. Plasma PRL and LH determinations in the animals injected with the minimal dose showed that HEXA and GHRP-6 stimulate the GH release specifically. Based on the results obtained in the latter experiments, young and aged rats were chronically treated with s.c. injections of 20 µg/kg twice a day for 15 or 30 days. At the end of the experiments, animals were acutely tested with s.c. injection of the same dose (20 µg/kg). It was found that both young and aged animals released GH in response to the repeated administration of GH releasing peptides after 15 days of treatment. However, after 30 days of treatment plasma GH did not change when young and aged HEXA treated animals were acutely tested with such peptide, but increased significantly in the GHRP-6 treated animals when they were acutely tested with GHRP-6. In response to the long term treatment with the GH-releasing peptides, plasma IGF-I levels increased in young animals when they were acutely tested with the corresponding peptide. However, plasma IGF-I levels in aged rats were not modified by the acute administration of either HEXA or GHRP-6 after 15 or 30 days of treatment. This study showed that: 1. HEXA and GHRP-6 stimulated GH release in aged rats and the magnitude of GH responses was similar to that in young rats; 2. the minimal dose of HEXA and GHRP-6 resulting in maximal GH response was 20 g/kg and such dose of HEXA specifically stimulated GH secretion in aged rats; 3. fifteen but not 30 days treatment of aged rats with such small dose of HEXA resulted in a similar GH response to subsequent stimulation with the same peptide; 4. plasma IGF-I responses to an acute administration of HEXA or GHRP-6 in rats chronically treated with the same peptide vanished with aging.

Journal Article↗
PubMed1996

Location and characteristics of nitric oxide synthase in sheep spinal cord and its interaction with alpha(2)-adrenergic and cholinergic antinociception.

BACKGROUND: Nitric oxide synthase is located in the spinal cord dorsal horn and intermediolateral cell column, where it may modulate sensory and sympathetic neuronal activity. However, the biochemical characteristics of this enzyme have not been examined in these different areas in the spinal cord. Although alpha(2)-adrenergic agonists, muscarinic agonists, and nitric oxide may interact in the spinal cord to produce antinociception, these interactions have not been characterized. METHODS: Sheep spinal cord tissue was homogenized ad centrifuged at high sped to separate soluble and membrane-bound fractions. Nitric oxide synthase activity was determined by conversion of [(14)C]-L-arginine to [(14)C]-L-citrulline and its kinetic characteristics, dependency on cofactors, and sensitivity to inhibitors determined. Sheep spinal cord was stained for nicotinamide adenine dinucleotide phosphate diaphorase as a marker for nitric oxide synthase. Antinociception to a mechanical stimulus from intrathecal clonidine alone and with neostigmine was determined and the effects of L-arginine and n-methyl-L-arginine were determined. RESULTS: More than 85% of nitric oxide synthase activity was present in the soluble form and its kinetic, cofactor, and antagonist properties were similar to those of the neuronal isoform of nitric oxide synthase. Biochemical and histochemical studies localized nitric oxide synthase to the superficial dorsal horn and the intermediolateral cell column. Clonidine antinociception was enhanced by L-arginine and neostigmine, but not by D-arginine. Neostigmine's enhancement of clonidine antinociception was blocked by n-methyl-L-arginine. CONCLUSIONS: These results confirm those of previous studies demonstrating localization of nitric oxide synthase to superficial dorsal horn and intermediolateral cell column of mammalian spinal cord, and suggesting its identity as the neuronal isoform. Spinal alpha(2)-adrenergic agonist antinociception may be partly dependent on cholinergic and nitric oxide mechanisms.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1994

A PCR-based assay for the identification of the fish pathogen Renibacterium salmoninarum.

By means of a one-step one-tube extraction from less than 1 mg of tissue it is possible to identify, via the polymerase chain reaction, Renibacterium salmoninarum in salmon with bacterial kidney disease. A 149-bp DNA sequence unique to R. salmoninarum was specifically amplified and its nature confirmed by Southern hybridization using a non-isotopically labelled probe. The sensitivity of the approach allowed the detection of 22 R. salmoninarum cells. The procedure was successfully applied in the identification of the causative agent of bacterial kidney disease in kidney tissue from infected fishes.

Animals↗
PubMed1994

Prolactin gene expression and changes of prolactin pituitary level during the seasonal acclimatization of the carp.

The effect of seasonal acclimatization on the extent of prolactin (PRL) gene expression and on the content of this was studied in summer- and winter-carp (Cyprinus carpio) hormone pituitary glands. PRL content in the rostral pars distalis (RPD) was evaluated by immunocytochemistry using antibodies against a cross-linked synthetic peptide comprising the sequence of 15 amino acids which conform to the primary structure of carp PRL. To assess the level of PRL gene transcription, a 24-mer synthetic oligonucleotide probe whose sequence included nucleotides 2041-2064 located in exon V of the carp PRL gene, was used. Employing in situ hybridization assays, a high expression of PRL mRNA was observed in the RPD of summer-acclimatized carp. A negligible level of transcription was observed in tissue sections of pituitary glands from winter-acclimatized carp. Concurrently, immunodetection of the PRL-producing cells in the RPD revealed that the pituitary hormone level was significantly higher in the warm season-adapted carp.

Acclimatization↗
PubMed1994

[Cystic hygroma. Antenatal diagnosis and clinical management].

Nine cases of cystic hygroma in pregnancy diagnostic by ultrasound are presented. Chromosomal abnormalities accompany in 7 cases occurred, with, great frequency of "Turner Syndrome". The prognostic of this congenital malformation, has relation with the chromosomopaty and the difference between septal and nonseptated cystic hygroma.

Adolescent↗