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Biomedical subjects

L A Castro

Publications and source records attributed to L A Castro.

At least 19 recordsLinked to original sources
PubMed2001

[Papular acantholytic dyskeratosis].

Papular acantholytic dyskeratosis is a very rare skin disease, which shows a suprabasilar cleft with acantholytic and dyskeratotic cells, simulating the light microscopic picture of Darier disease. In this condition, the lesions are acquired without a genetic basis. We observed a 40-year-old woman with about 200 papules on the lower aspects of her legs; histological examination showed changes similar to Darier disease. Transmission electron microscopy showed a reduced number of desmosomes and perinuclear distribution of tonofilaments. The lesions were successfully treated with cryotherapy with spray technique.

Acantholysis↗
PubMed1998

Nitric oxide and peroxynitrite-dependent aconitase inactivation and iron-regulatory protein-1 activation in mammalian fibroblasts.

The reaction of reactive oxygen and nitrogen species with the [4Fe-4S]2+ cluster of mitochondrial (m-) and cytosolic (c-) aconitases leads to loss of catalytic activity and, in the case of the c-aconitase, triggers total cluster disruption to yield the iron-regulatory protein-1 (IRP-1). Herein we have studied the relative contribution and interplay of reactive oxygen species (O and H2O2), nitric oxide (*NO), and peroxynitrite in the modulation of m- and c-aconitase and IRP-1 activities in V79-M8 mammalian fibroblasts, identifying key variables that control the various reactivities at the cellular level. Extracellular production of H2O2 led to inactivation of both m- and c-aconitase and IRP-1 activation, while extracellular had no effect. However, increased intracellular production of caused a loss in m- and c-aconitase activity and IRP-1 activation. Nitric oxide released from NOC-12 had a more complex effect on aconitase and IRP-1 activities. Mitochondrial aconitase was more sensitive than c-aconitase to *NO-mediated inactivation and minimal activation of IRP-1 was observed during a 30-min exposure to the *NO donor. The action of *NO was down- or upregulated by the presence of extra- or intracelular, respectively. Extracellular decreased the *NO-mediated inactivation of aconitases, due to the preferential extracellular decomposition and the lower diffusivity of peroxynitrite compared to *NO. On the other hand, *NO exposure concomitant with enhanced intracellular fluxes lead to intracellular peroxynitrite formation as evidenced by Western blot analysis of nitrated proteins, which increased the effects observed with *NO alone. Peroxynitrite-mediated aconitase inactivation, IRP-1 activation, and cellular protein nitration were more pronounced in cells with low GSH content such as V79-M8 glutathione-depleted cells as well as in pGSOD4 cells which contain 32% of the GSH of the parental strain. Mechanistically, our results imply that the differential actions of the studied reactive species toward cellular aconitases depend on at least three critical factors: (i) their reaction rates with aconitases, (ii) the cellular compartment where they are formed, and (iii) the intracellular status of glutathione.

Aconitate Hydratase↗
PubMed1996

Continuous alcoholic fermentation process in a tower reactor with recycling of flocculating yeast.

The influence of different substrate concentrations on the performance of a continuous system of alcohol production by fermentation using a tower reactor with recycling of flocculating yeasts was investigated. All experiments were carried out using a flocculating yeast strain IR-2, isolated from fermented food, and identified as Saccharomyces cerevisiae. Cane sugar juice was used as a substrate with sugar concentrations of 160, 170, 180, 190, and 200 g/L. Constant values of dilution rate, 0.20 h-1, temperature, 30 degrees C, and pH 3.3, were used. The performance of the reactor was observed to be efficient with high substrate concentrations. Maximum productivities of 18 g/L/h 99% substrate conversion and ethanol concentrations of 90 g/L were obtained using 200 g/L of sugar in the feedstock. For substrate concentrations of 160 g/L, a maximum yield of 0.45 g of ethanol/g of sugar was observed or 90% of the theoretical value.

Biotechnology↗
PubMed1995

A corm-specific gene encodes tarin, a major globulin of taro (Colocasia esculenta L. Schott).

A gene encoding a globulin from a major taro (Colocasia esculenta L. Schott) corm protein family, tarin (G1, ca. 28 kDa) was isolated from a lambda Charon 35 library, using a cDNA derived from a highly abundant corm-specific mRNA, as probe. The gene, named tar1, and the corresponding cDNA were characterized and compared. No introns were found. The major transcription start site was determined by primer extension analysis. The gene has an open reading frame (ORF) of 765 bp, and the deduced amino acid sequence indicated a precursor polypeptide of 255 residues that is post-translationally processed into two subunits of about 12.5 kDa each. The deduced protein is 45% homologous to curculin, a sweet-tasting protein found in the fruit pulp of Curculigo latifolia and 40% homologous to a mannose-binding lectin from Galanthus nivalis. Significant similarity was also found at the nucleic acid sequence level with genes encoding lectins from plant species of the Amaryllidaceae and Lilliaceae families.

Amino Acid Sequence↗
PubMed1993

[Alzheimer's disease. Relationship between time of disease and its staging].

Forty-nine patients with clinical diagnosis of Alzheimer's disease were submitted to neuropsychological evaluation for staging the disease. The time of the initial symptoms was correlated to the stage of the disease. The evolution was protracted in 28.5% of the patients with only insidious memory deterioration. For another group of patients (12.2%) the evolution was serious since the beginning of the disease, with apraxo-agnosic signs. For the 34 patients with apraxo-agnosic impairment, in 50% this manifestation began in the first two years of the disease. Data suggest the occurrence of two subgroups. In the first the evolution of the disease is rapid, and in the second it is protracted. Also, they suggest that the evolution in the first two years is critical for characterizing the severity of progression in the clinical manifestations of Alzheimer's disease.

Aged↗
PubMed1986

Pharmacokinetics of rifampin given as a single oral dose in foals.

Six foals from 6 to 8 weeks of age were given a single oral dose of rifampin at a dosage of 10 mg/kg of body weight. Serum rifampin concentrations were measured serially during a 24-hour period. The mean peak serum rifampin concentration was 6.7 micrograms/ml at 4 hours after treatment. The concentration decreased slowly, and at 24 hours the mean value was 2.7 micrograms/ml. The elimination half-life was 17.5 hours, and the elimination rate constant was 0.04/hr.

Administration, Oral↗
PubMed1985

[Cytomegalovirus infection after kidney transplantation--importance of the primary infection].

Even though for many reasons (shortage of organs, histocompatibility, lack of time to await the results) an organ transplantation from a sero-positive donor to a sero-negative recipient will not be unavailable, CMV-serology should be checked as early as possible, if possible even before transfusions or their donors since the virus remains infectious over several weeks in the leucocytes. The prophylactic use of hyperimmunoglobulin is justified in cases where organs or blood from sero-positive donors are given to sero-negative immunosuppressed patients because complications arising from the infection can be life-threatening in these patients.

Antibodies, Viral↗
PubMed1985

[Combined immunosuppression (cyclosporin, azathioprine, methylprednisolone) in patients at immunological risk after kidney transplantation].

Animal experiments have demonstrated a synergistic immunosuppressive effect when using the combination of ciclosporin (CS) and azathioprine (AZA) as immunosuppressant. On this basis these drugs were used in patients considered to be at high risk for immunological complications. Group I (immunological risk patients) consisted of 63 patients with a second or third graft and/or elevated cytotoxic antibodies above 30% against the test panel. In addition to the basic immunosuppressive therapy (CS) and methylprednisolone (MP), AZA was given in the first 2 weeks following transplantation. Group II (historical control) summarized immunological risk patients with conventional immunosuppressive therapy (AZA/MP). The IIIrd group with 28 patients on the above mentioned immunological risk were treated with CS and MP only. The results revealed a 2-year actuarial graft survival rate of 68% (groups I) versus 40% (group II) versus 52% (group III). There were no differences in WBC and platelet counts or in infectious complications. No malignancy was noticed.

Azathioprine↗
PubMed1984

[Cutaneous nodular Kaposi sarcoma following kidney transplantation and immunosuppression].

Five months after renal transplantation and an immunosuppressive trial with azathioprine and methylprednisolone, a black African female developed a cutaneo-nodular Kaposi's sarcoma that occurred symmetrically on the lower legs, thighs and forearms. Intensive search for visceral involvement was negative. Histologically, the nodes consisted of spindle cells; there were many new vessel formations with proliferation of atypical endothelial cells. After therapy with cytostatica and x-rays there was a time-limited disappearance of the Kaposi's sarcoma; 1 year later a relapse developed on the left lower leg. Field radiotherapy with accelerated electrons in a single dose of 8 Gy was successful. There is a greater incidence, in the literature, of Kaposi's sarcoma in immunosuppressed patients with organ transplants. Treatment with immunosuppressive substances is probably significant in the development of the Kaposi's sarcoma in those patients.

Adult↗