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J Alvarado

Publications and source records attributed to J Alvarado.

At least 19 recordsLinked to original sources
PubMed2001

[Hypothalamic hamartoma causing precocious puberty: A case report].

Hypothalamic hamartomas are non neoplastic lesions that may cause precocious puberty with or without complex seizures, personality disorders and mental retardation. We report a 14 years old male that had a precocious puberty at the age of 11 and a prolonged episode of altered sensorium with automatism, that was diagnosed as a complex seizure. Physical examination showed a sexual development classified as Tanner stage III-IV, a height of 168 cm and a weight of 61 kg. Neurological examination was normal. A CAT scan showed a 13 x 13 x 9 mm mass in the suprasellar cistern, between the infundibulum and the brain stem, without exerting a mass effect over adjacent structures. It was diagnosed as an hypothalamic hamartoma.

Adolescent↗
PubMed1998

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela: present situation of human and canine infections.

The report of a new autochthonous case of human American Visceral Leishmaniasis (AVL) in 1992 in the village of Guayabita, Aragua State, Venezuela (10 degrees 16'N, 67 degrees 28'W; 500 m asl), led us to undertake an epidemiological study in this locality. A demographic survey was conducted using a structured questionnaire in which data was collected regarding sex, age, occupation, length of residence in the area and migratory history. A leishmanin skin test (LST) was applied and samples of venous blood for counter immunoelectrophoresis (CIEP) and immunofluorescent antibodies (IFAT) tests were drawn. The prevalence of positive LST was 11.4%. The positivity was highest among males and increased with age. Young males seemed to be more exposed to infection than females. Since occupation per se did not seem to account for this association, it may be explained as a gender-associated behavior, leading to different degrees of exposure to sand flies. The canine population was also screened for leishmanial infection. One dog was shown to be parasitologically infected with Leishmania sp. Four out of 71 dogs (5.6%) were positive for FG, CIEP, IFAT and Western Blot and 11 (15.5%) were positive for CIEP. These results suggest that after almost 30 years of epidemiological silence, American visceral leishmaniasis has re-emerged in this focus.

Adolescent↗
PubMed1998

Effect of dietary oils, cholesterol and antioxidant vitamin supplementation on liver microsomal fluidity and xenobiotic-metabolizing enzymes in rats.

This study was undertaken to compare the effects of four oils: corn (C), olive (O), hazelnut (H) or fish (F), and the intake of two supplements: cholesterol, 1% (Ch) or dl-alpha-tocopherol acetate, 500 mg/kg, and beta-carotene, 30 mg/kg (V), on liver microsomal fluidity, cyt P450 content and aniline hydroxylase (AH), aminopyrine-N-dimethylase (AND) and UDP-glucuronyltransferase (UDP-GT) activities. Male Sprague-Dawley rats (n = 6/group) were fed semipurified diets containing 15% oil, without or with Ch or V, for 20 days. Dietary intake and feed efficiency were lower in rats fed F. Relative liver weight was higher in animals fed F, similar in O and H, and lower in the group fed C. The intake of V increased feed intake in C+V group and decreased the relative liver weight of F+V group, which also decreased with the intake of F+Ch. Ch intake increased the relative liver weight in all groups consuming vegetable oils. Cyt P450 content was higher in rats fed F. Decreased cyt P450 content was observed in C+Ch and F+Ch groups, while it augmented in H+Ch group. Mixture V increased cyt P450 in rats fed C+V, F+V and O+V. The highest membrane fluidity was observed in rats fed F. Fluidity was also higher in group H versus O or C. The intake of Ch decreased microsomal fluidity in all groups, while V induced an increase in microsomal fluidity in group O+V. Rats fed F exhibited higher enzyme activities. AND activity increased with V only in rats fed H+V, while AH activity increased with V intake in groups F+V and O+V. In the C+V group, fluidity was not affected by V, while the cyt P450 content and UDP-GT activity increased. The O+V group exhibited lower UDP-GT activity and higher fluidity and cyt P450 content. The activity of AH decreased in groups F+Ch and C+Ch. UDP-GT activity was higher in rats fed F. It diminished after the intake of Ch in H+Ch and F+Ch. These results indicate that although AH and AND act in the same microsomal metabolic pathway, their localization into the membrane may be determinant of their activity and the response to dietary lipids. It is shown that F intake exerts the most significant effects upon liver microsomal properties, e.g. higher fluidity, cyt P450 content and enzymatic activities, an effect that prevails over the intake of the supplements tested.

Animals↗
PubMed1997

The cellular basis of aqueous outflow regulation.

This review begins with an introduction to the concept of the cellular regulation of aqueous outflow, current methods used for its study, and the cell types that are known to participate in this process. Current research in the field is divided into work on cell properties, cell products and extracellular matrix, cytoskeletal and structural changes, and drug interactions.

Animals↗
PubMed1997

Two distinct oncornaviruses harbor an intracytoplasmic tyrosine-based basolateral targeting signal in their viral envelope glycoprotein.

It has been clearly established that the budding of the human immunodeficiency virus (HIV-1), a lentivirus, occurs specifically through the basolateral membrane in polarized epithelial cells. More recently, the signal was assigned to a tyrosine-based motif located in the intracytoplasmic domain of the envelope glycoprotein, as previously observed on various other viral and cellular basolateral proteins. In the present study, expression of human T-cell leukemia virus type 1 (HTLV-1) or Moloney murine leukemia virus envelope glycoproteins was used for trans-complementation of an envelope-negative HIV-1. This demonstrated the potential of oncornaviral retrovirus envelope glycoproteins to confer polarized basolateral budding in epithelial Madin-Darby canine kidney cells (MDCK cells). Site-directed mutagenesis confirmed the importance of a common motif encompassing at least one crucial membrane-proximal intracytoplasmic tyrosine residue. The conservation of a similar basolateral maturation signal in different retroviruses further supports its importance in the biology of this group of viruses.

3T3 Cells↗
PubMed1996

Improvement of functional magnetic resonance images by pretreatment of data.

Functional magnetic resonance images of the brains of subjects performing the finger-tapping paradigm were made using a conventional technique. Two threshold values for the pixels were obtained by analysing pixel by pixel the distributions of the means and variances of each subject's images for 20 consecutive scans, both while performing the task and while at rest. Considerable signal improvement in the final images was achieved by removing from our data all pixels beyond these threshold values (mean < or = 16 and variance > or = 7).

Adult↗
PubMed1995

Clinical experience with the long-term use of 1% apraclonidine. Incidence of allergic reactions.

OBJECTIVE: To identify the incidence and characteristics of allergic reactions associated with the long-term use of 1% apraclonidine hydrochloride. METHODS: We undertook a retrospective analysis of 64 patients receiving long-term 1% apraclonidine therapy at the University of California-San Francisco Glaucoma Service. Patients were excluded if the duration of treatment was less than 2 weeks. Demographic data, initial intraocular pressure response, and incidence and characteristics of allergic reactions were obtained through chart review. Student's t test and chi 2 analysis were used to analyze the demographic data, and Kaplan-Meier survival analysis was used to estimate the long-term incidence of local reactions. RESULTS: Sixty-four patients met the criteria for the study. Of these, 31 (48%) developed an allergic reaction (responders) that led to discontinuation of treatment with the medication, with a mean latency of 4.7 months. Mean follow-up was 13.3 months. Patients free of local reactions (nonresponders) for at least 10 months were able to successfully continue apraclonidine use. Responders tended to be older and female. CONCLUSIONS: Our data are specific for the 1% preparation; however, physicians prescribing apraclonidine on a long-term basis should be aware of possible allergic reactions. A substantial percentage of patients developed this side effect, but most tolerated the medication for up to 4 months, and those without a local reaction after 10 months appeared to be able to continue apraclonidine use indefinitely. This allergic reaction is likely related to the adrenergic agent itself, and not to preservatives.

Adrenergic alpha-Agonists↗
PubMed1991

Determination of Cd, Cr, Cu, Pb and Zn in human semen by graphite furnace atomic absorption spectrometry after microwave sample dissolution.

Human semen samples were analyzed by graphite furnace atomic absorption spectrometry, using L'vov platforms and the method of standard additions, to determine their Cd, Cr, Cu, Pb and Zn content. The samples were analyzed directly and after conventional and microwave wet acid dissolution. Matrix modification, using magnesium and palladium nitrates and ammonium biphosphate solutions, was evaluated for the analysis of the microwave-digested samples. The best results were obtained for Cr, Cu and Zn using Pd(NO3)2, and a mixture of Mg(NO3)2 and Pd(NO3)2 solutions. The direct analysis of water-diluted semen produced inaccurate results with unacceptably high standard deviations. The results obtained for the microwave-dissolved samples showed relative standard deviation values within the range 0.63-8.4%. The analysis of spiked semen solutions showed recoveries of the added analytes ranging from 96 to 104%. The accuracy of the measurements was checked against the NIST 1,577a, bovine liver, standard reference material. Sample dissolution time was drastically reduced from 3-4 hours, using the conventional method, to approximately 8 minutes using the microwave-assisted wet acid digestion procedure.

Cadmium↗
PubMed1989

Effects of betaxolol/timolol on epinephrine stimulated cyclic-AMP levels in human trabecular meshwork cells.

The effects of timolol and betaxolol were compared for blocking beta agonist stimulation of cyclic-AMP in cultured human trabecular meshwork cells. Epinephrine (10(-5) M) produced a large and rapid increase in HTM cyclic-AMP; timolol (10(-6) M), at concentrations readily achieved in the aqueous humor after 0.5% eyedrops, completely blocked this effect. Recovery from timolol treatment appeared to be relatively slow, with only a 30-40% recovery observed by 9 hours. In comparison, betaxolol (10(-6) M) produced a smaller blockade of the epinephrine effects; a rapid recovery from the betaxolol effects was observed, with a greater than half-maximal response to epinephrine observed 15 minutes after removal of this beta blocker. These findings may help to explain the clinical observations of an outflow facility effect of epinephrine when used in combination protocols with betaxolol, but not with timolol.

Betaxolol↗
PubMed1989

Characterization of beta-adrenergic receptors in cultured human trabecular cells and in human trabecular meshwork.

The characterization of beta-adrenergic receptors on cultured human trabecular cells and trabecular meshwork from human autopsy eyes was carried out by radioligand binding utilizing (125I)-iodopindolol. In cultured cells, the observed binding of (125I)-iodopindolol was of high affinity (Kd = 43 pM) and saturable. Scatchard plots were linear and revealed a Bmax of 33 +/- 7 fmol/mg of protein. Competition studies with a series of agonists and antagonists revealed that human trabecular cells contain a single class of beta-adrenergic receptors of the beta 2 subtype. Similarly, the IC50 of ICI 89,406 (176 nM) in human trabecular meshwork from autopsy eyes supports the presence of beta 2-adrenergic receptors in this tissue.

Adult↗
PubMed1989

[The development of the anti-phospholipase A2 antibody response in horses inoculated with venom for the production of polyvalent antisnake serum in Costa Rica].

The development of antibody response against phospholipase A2 activity of Bothrops asper venom was studied in a group of adult and healthy horses used in the production of the polyvalent antivenom at the Instituto Clodomiro Picado. Simultaneously, the general condition of the animals during the immunization schedule was also studied. There was a great individual variability in the immune response, although most of the horses studied reached the highest neutralizing titer after injection of doses of venom of 30 mg and 50 mg. On the other hand, in horses that had been previously immunized and were infected for a second immunization, the highest antibody titer was observed 16-22 days after inoculation. There were only mild alterations in the general condition of the horses as a consequence of venom inoculation. However, local abscesses, fistulae and fibrosis were observed at the site of venom injection. On the basis of the conspicuous individual variability observed, it is proposed that the immune response in horses used in the production of antivenom must be evaluated on individual basis, instead of working with pools of serum samples.

Animals↗
PubMed1988

The cytoskeleton of the cultured human trabecular cell. Characterization and drug responses.

To determine the organization of the three major cytoskeletal elements of cultured human trabecular meshwork cells (actin filaments, microtubules and intermediate filaments), we employed fluorescence microscopy and stereo-transmission electron microscopy of extracted, S-1 labeled and critical-point dried cells. Morphologic changes resulting from treatment with cytochalasin B, colchicine, taxol and nocodozole were also characterized. Compared with the cynomolgus monkey trabecular cell, morphologic differences in overall cell shape and orientation of both actin filaments and microtubules were noted. However, the responses to cytoskeletal active drugs were quite similar. Taxol, nocodozole and colchicine had a marked effect on microtubule organization, while nocodozole and colchicine had a marked effect on vimentin filament organization. None of these drugs produced marked changes in human trabecular cell shape. In contrast, treatment with the anti-actin drug cytochalasin B resulted in both a marked change in cell shape associated with organizational changes in all three cytoskeletal elements. These studies suggest a central role of actin filaments in determining overall cell shape and cytoskeletal organization in the cultured human trabecular cell.

Alkaloids↗
PubMed1988

Use of immunotoxin to inhibit proliferating human corneal endothelium.

Transferrin plays a central role in cellular proliferation and proliferating cells have been shown to express transferrin receptors with increased density. We examined the effect of an immunotoxin consisting of anti-transferrin receptor monoclonal antibody (454A12) conjugated to recombinant ricin A chain (rRTA) on the proliferation of human corneal endothelium (HCE) in vitro. In proliferating cultures an immunotoxin (454A12-rRTA) concentration of 50 ng/mL reduced cell counts at day 7 by at least 89%, with no effect observed at 0.01 ng/ml. In contrast, cell counts were only minimally reduced in confluent cultures, even after 7 days' exposure to high concentrations of immunotoxin. These data suggest that 454A12-rRTA may be used to prevent growth of human corneal endothelium in pathological conditions such as the iridocorneal endothelial (ICE) syndrome.

Antibodies, Monoclonal↗