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J A Porto

Publications and source records attributed to J A Porto.

13 recordsLinked to original sources
PubMed2005

Transmission of light through a single rectangular hole.

We show that a single rectangular hole in a metallic film exhibits transmission resonances that appear near the cutoff wavelength of the hole waveguide. For light polarized with the electric field pointing along the hole's short axis, it is shown that the normalized-to-area transmittance at resonance is proportional to the ratio between the long and short sides, and to the dielectric constant inside the hole. Importantly, this resonant transmission process is accompanied by a huge enhancement of the electric field at both entrance and exit interfaces of the hole.

Journal Article↗
PubMed1992

Effect of cutaneous cell-mediated immune response to rIFN gamma on Mycobacterium leprae viability in the lesions of lepromatous leprosy.

1. Studies were carried out to determine the effect of intra-dermal injections of recombinant human interferon-gamma (rIFN gamma) on the viability of Mycobacterium leprae. Twenty-three untreated and 4 treated multibacillary patients, 12 with lepromatous leprosy (LL) and 15 with borderline lepromatous leprosy (BL), were selected for intradermal administration of rIFN gamma or PPD. Treated patients (LL and BL) had received multi-drug therapy according to the recommendations of the World Health Organization, i.e., rifampicin (600 mg/month), dapsone (100 mg/day) and clofazimine (50 mg/day and 300 mg/month) for 1-4 months. Three daily doses of 10 or 30 micrograms rIFN gamma induced local induration and mononuclear leucocyte accumulation. Bacteria isolated from a punch biopsy of the site 21 days after lymphokine administration were injected into mouse foot pads and evaluated for viability and growth. 2. The local response to rIFN gamma (specific activity 2 x 10(7) units/mg protein) induced a delay or total inhibition of M. leprae growth in the mouse foot pad, indicating that the cellular response to the antigen reduced local M. leprae viability. The extent of reduction in viability depended on the dose of rIFN gamma injected and the extent of local induration induced by the lymphokine. With a vigorous cell-mediated immune response growth was fully inhibited. 3. A similar but less extensive effect on M. leprae viability was observed in response to the local injection of 5 units in 0.1 ml of purified protein derivative of tuberculin (PPD).

Animals↗
PubMed1988

[Correlation of skin tests and the production of gamma-interferon in leprosy patients].

The responsiveness of 25 leprosy patients to an in vitro correlate of cell-mediated immunity to M. leprae antigen, (the production of Y-IFN by peripheral blood mononuclear cells) was compared to their response to skin tests routinely used to evaluate cell-mediated immunity to a number of antigens including M. leprae. The results indicate that among the polar lepromatous patients (LL) there was a clear correlation between low responses in the in vitro assay (Y-IFN production), negative skin test to the specific antigen (Mitsuda reaction) and low responses to skin tests to a related antigen (PPD). There was no correlation in the other clinical groups with skin tests to other unrelated antigens.

Antigens, Bacterial↗
PubMed1988

[Malignant histiocytosis. Apropos of a case].

The authors report a case of malignant histiocytosis occurring in a 39 year old female patient who presented an ulcerated cutaneous lesion which was the only clinical manifestation for one year and then widespread systemic involvement took place and death ensued. They emphasize the rarity of the condition and point out that erythrophagocytosis in the histopathological examination may be a valuable finding for the diagnosis of malignant histiocytosis.

Adult↗
PubMed1988

[Ashy dermatosis. Review of the literature and report of a case].

The authors make a review of the epidemiologic, etiopathogenic, clinical, laboratory and therapeutic aspects of ashy dermatosis, described in 1957 by Ramírez in El Salvador, of which more than 150 cases have been described up to now in different continents. The disease is exclusively cutaneous, presents peculiar clinical features with a lichenoid tissue reaction, and has no specific treatment or known etiology. The authors report a case in a Brasilian man, followed up for three years. The treatment of a T. trichiura infestation did not change the cutaneous features, as opposed to what has been reported.

Adult↗
PubMed1987

Cord serum gamma glutamyltransferase in newborns.

This article reports correlations among gamma-glutamyltransferase (GGT), fetal haemoglobin (fH), alpha-fetoprotein, 5'-nucleotidase, ceruloplasmin, and direct, indirect, and total bilirubin in the serum of blood taken from the umbilical cords of 128 newborns delivered after 37-42 weeks of gestation. GGT was significantly correlated with alpha-fetoprotein, but not with direct bilirubin, indirect bilirubin, total bilirubin, fH, or %fH. Neither fH nor %fH were correlated with alpha-fetoprotein, but there was highly significant negative correlation between both fH and %fH on the one hand, and gestational age and weight at birth on the other. The %fH was also correlated negatively with ceruloplasmin, which in turn exhibited negative correlation with alpha-fetoprotein. The predominant forms of GGT in umbilical cord and adult sera were, respectively, those with alpha 1 and alpha 2 mobility. In cord sera, delipidation with n-butanol brought about loss of GGT activity and a shift from an alpha 1 to an alpha 2 position, whereas no significant effect of this kind was observed in adult sera. Affinity chromatography through Concanavalin A-Sepharose showed cord sera to contain a proportion of bound-GGT (68.5 +/- 5.5%) that was significantly greater (p less than 0.001) than that found in adult sera (59.8 +/- 10.2%). It is concluded that the high GGT activity of cord sera is probably due to hepatic immaturity rather than maternal sources, enzymatic induction or microsomal lesions; that the predominant form of GGT in cord serum may be a complex with HDL and less sialized than the adult enzyme; and that, of the factors examined, the best indicator of neonatal maturity is fetal haemoglobin.

5'-Nucleotidase↗
PubMed1987

Cellular responses to the intradermal injection of recombinant human gamma-interferon in lepromatous leprosy patients.

The local response to a single intradermal injection of 10 micrograms recombinant gamma-interferon (rIFN gamma) has been studied in 17 patients with lepromatous leprosy. Of these, 2 patients additionally received two intradermal injections of 10 micrograms rIFN gamma at another site. The results were compared with those of 3 patients who received three injections of the same dose at a single site in an earlier study. One to 7 days after lymphokine administration 4-mm punch biopsies were obtained and examined for cellular alterations in the dermis and epidermis. This allowed a kinetic analysis of mononuclear cell infiltration, keratinocyte proliferation and differentiation, and Langerhans cell redistribution. At 24 hours, the migration of large numbers of helper T cells and monocytes was already prominent and associated with induration. Mononuclear cell accumulation peaked at 72 hours but then persisted for 5-7 days. Only small numbers (one-third or less of total T cells) of suppressor/cytotoxic T cells were present at any time, and granulocytes were absent. Two daily injections of rIFN gamma led to a more intense accumulation of cells. Ten micrograms of rIFN gamma resulted in enhanced keratinocyte proliferation, Ia expression, and thickening of the epidermis. At 24-48 hours major histocompatibility Class II (Ia) antigen was first noted on the dividing cells of the basal layer. By 72-96 hours the entire epidermis exhibited strong expression of Ia antigen on cell surfaces. Repeated doses of lymphokine accentuated these changes and resulted in a more prompt keratinization and sloughing of this layer. Whereas a single dose of rIFN gamma resulted in the upward movement of T6+ Langerhans cells (LCs) in the epidermis, two injections led to a 50% reduction in their numbers and three doses were associated with an almost total loss of detectable T6+ LCs from the epidermis. These are probably sloughed along with keratinocytes. In contrast to the situation with a delayed immune response in the skin (purified protein derivative), no LCs accumulated in the dermis in association with helper T cells.

Animals↗
PubMed1985

[Genuine cutaneous amyloidosis. Natural course].

A case of primary localized cutaneous amyloidosis followed up during 35 years is reported. The initial lesions and the pruritus disappeared after years of evolution and new lesions appeared in other areas. These findings confirm previous observations of the author who reported on 24 patients with primary localized cutaneous amyloidosis followed up for 20 to 30 years. In seven of them amyloid was demonstrated in areas where clinical lesions had disappeared. In most patients either the clinical lesions the pruritus, or both had disappeared and in many patients other clinical lesions had appeared in other locations.

Amyloid↗
PubMed1985

[Distribution of Langerhans cells in the skin of patients with Hansen's disease].

Intra-epidermal OKT+ and OKla+ cells were identified and counted in 25 cases of Leprosy (7 lepromatous, 7 bordeline, 8 tuberculoid and 3 indeterminate). No significant variations were found in the number of Langerhans cells (OKT6+) in the clinical forms of the disease, nor marked variations were determined in the relation of OKT6+/OKla+ intra-epidermal cells. Nevertheless significant variation in the number of Langerhans cells were noted in several cases independently of the clinical form of the disease.

Antibodies, Monoclonal↗
PubMed1984

Effect of treatment on the cellular composition of cutaneous lesions in leprosy patients.

We report on the cellular composition of the cutaneous lesions of 38 leprosy patients prior to and after 12-18 months of chemotherapy. All of the patients with tuberculoid (TT) disease had OKT4/OKT8 ratios that exceeded 1.0. In the indeterminate patients, the ratio varied depending upon the immune status of the individual. A low ratio of OKT4/OKT8 cells (0.25) was found in the LL patients as previously reported. The low ratio of OKT4/OKT8 in the lesions of lepromatous patients did not undergo significant changes after treatment in spite of a marked reduction in the number of intracellular bacilli.

Humans↗