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Biomedical subjects

M Perez

Publications and source records attributed to M Perez.

At least 19 recordsLinked to original sources
PubMed1994

Intense vascular sprouting from rat femoral vein induced by prostaglandins E1 and E2.

The formation of new capillaries from the rat femoral vein was specifically explored to assess whether venous vessels of this caliber may participate in the process of angiogenesis. Prostaglandins of the E series (PGE1 and PGE2) were administered into the soft connective tissue surrounding the rat femoral vessels as angiogenic inducers. In these conditions, between 2 and 7 days, a great number of new capillaries were observed in the media of the femoral vein, arising from the endothelial cells (EC) in the intima. The events of the capillary growth from the femoral vein included EC activation, local degradation of the basal membrane followed by migration and proliferation of EC, solid sprout formation with posterior canalization, development of a new basal membrane, and appearance of pericytes around the new capillary. Although numerous vascular buds were also observed arising from the small venules and capillaries in the periadventitial tissues, they were separated at first from those in the media of the femoral vein by the venous adventitia. Later, connections were observed between both newly formed microcirculations. The present study shows the capacity of PGE1 and PGE2 in the extravascular position of inducing capillary sprouting from veins. Furthermore, the observations provide greater evidence that vessels with characteristics similar to those of the rat femoral vein may contribute to angiogenesis, on occasion with an intense neovascularization. This fact may be of interest for the establishment of a functional circulation after angiogenesis by anastomoses of the new capillaries with those arising from pre-existing vessels of greater caliber than the venules.

Alprostadil↗
PubMed1992

Epidemiology and long-term consequences of hepatitis delta virus infection in the Yucpa Indians of Venezuela.

To define better the epidemiology and clinical impact of hepatitis delta virus (HDV) infection among hepatitis B virus (HBV) carriers in less developed countries, the authors prospectively studied a cohort of 216 Yucpa Indian HBV carriers in Venezuela. HBV carriers were followed regularly between 1983 and 1988 by physical examination, laboratory testing for liver enzymes and HBV and HDV markers, and epidemiologic history. Among the cohort, 74 (34%) were initially positive for HDV infection, and 35 additional persons became infected during the study. Risk factors for new HDV infection included living in southern Yucpa villages; being young adults (15-19 years) or young children (1-9 years), and living in a household with a person with acute HDV infection. Persons with HDV infection were at high risk of developing chronic liver disease; 56% of HDV-infected persons had moderate-to-severe chronic liver disease at the end of the study compared with none of the HBV carriers without HDV infection. Mortality rates were 6.9% and 8.8% per year, respectively, among initially HDV-positive HBV carriers and those with new HDV infection, because of rapidly progressive chronic liver disease and fulminant hepatitis; mortality was significantly lower in HBV carriers without HDV infection and in non-HBV carriers. HDV superinfection is a devastating disease in HBV carriers in tropical South America. Prevention of HBV infection with hepatitis B vaccine is the best available tool to reduce the impact of this problem.

Acute Disease↗
PubMed1992

Development and hormonal regulation of mast cells in the Harderian gland of Syrian hamsters.

The morphological features and relative number of mast cells per mm2 were studied in the Harderian glands of male and female Syrian hamsters (Mesocricetus auratus) under different experimental conditions. The structural and ultrastructural characteristics of Harderian mast cells corresponded to those of connective tissue mast cells. The Harderian glands from female hamsters contained more mast cells than those of male hamsters. A subcutaneous implant of testosterone (2 mg/24 mg beeswax) resulted in a rapid decrease in the number of recognizable mast cells 6 h after the implantation. Neither orchidectomy nor ovariectomy significantly altered the relative number of mast cells. However, the daily subcutaneous injection of 20 IU of human chorionic gonadotropin during 20 days resulted in a significant decrease of identifiable mast cells. The administration of another steroid such as progesterone or the induction of states of hypo- and hyperthyroidism did not alter the distribution of mast cells in the Harderian glands of female Syrian hamsters.

Age Factors↗
PubMed1992

Correlations of unique clinical, immunotypic, and histologic findings in cutaneous gamma/delta T-cell lymphoma.

Cutaneous T-cell lymphoma is a malignancy of T cells that express a clone-specific heterodimer T-cell receptor for antigen. The second recognized case of an epidermotropic malignancy of T-cells expressing gamma/delta T-cell receptor-expressing cells is reported. The immunophenotype of the malignant T-cells was CD3+, CD2+, CD7+, gamma/delta T-cell receptor+, CD4-, CD8-, and alpha/beta T-cell receptor-. The clinical features were remarkable for extreme epidermotropism with a scant dermal lymphomatous infiltrate. Profound keratinocyte necrosis occurred in areas of malignant skin infiltrates. Despite cutaneous lesions covering more than 50% of the skin surface of the patient, no adenopathy or splenomegaly was detected. The intense epidermotropism of this patient's gamma/delta T-cell receptor-expressing cells and the putative cytolytic properties of CD4- CD8- gamma/delta contributed to the destruction of epidermis. Remission was induced with a combination of electron beam and extracorporeal photochemotherapy.

Antigens, CD↗
PubMed1992

Treatment of erythrodermic cutaneous T-cell lymphoma with extracorporeal photochemotherapy.

BACKGROUND: This original cohort of patients with erythrodermic cutaneous T-cell lymphoma (CTCL) was reported to have clinical improvement with photopheresis during the 12 months of the original study. No long-term follow-up data have been available to examine the impact of this therapy on the disease. OBJECTIVE: Our purpose was to provide long-term follow-up on the original 29 erythrodermic CTCL patients treated with photopheresis and to compare these results with historical controls. METHODS: Files of patients from the original photopheresis study centers were reviewed and their current status was documented. RESULTS: The median survival of the treated patients was 60.33 months from the date of diagnosis and 47.9 months from the date of the start of photopheresis therapy. A complete remission has been maintained in four of the six patients who achieved complete responses in the original study. The best responses were seen in patients with a lower CD4/CD8 ratio in the peripheral blood at the start of therapy. CONCLUSION: Photopheresis can influence the natural history of erythrodermic CTCL by inducing remissions and prolonging survival with minimal toxicity.

CD4-CD8 Ratio↗
PubMed1992

Effects of a single oral dose of desipramine on postoperative morphine analgesia.

Drugs that block norepinephrine reuptake offer promise as opioid potentiators, because norepinephrine mediates opioid analgesia but not side effects such as sedation or nausea. In a two-by-two factorial design, we randomized 62 inpatients with pain following major surgery to receive either desipramine, 50 mg by mouth, or placebo at 6 a.m. on the first day after surgery. At their first request of pain medication after 8 a.m., they were given intravenous morphine, either 0.033 mg/kg or 0.10 mg/kg. Pain relief and side effects were assessed for 4 hr; peak relief on the visual analog scale (VAS) was the primary outcome variable. Pain relief, side effect scores, and time to remedication were significantly greater with the higher dose than with the lower dose of morphine, verifying assay sensitivity, but desipramine pretreatment did not significantly enhance morphine analgesia. The mean increase in peak VAS relief score after desipramine pretreatment, relative to placebo, was 6%; the 95% confidence interval for this estimate ranged from a 21% reduction to a 34% increase in pain relief. These results differ from a previous report that 1 week of pretreatment with desipramine, 75 mg per day, potentiated postoperative morphine analgesia. We conclude that if desipramine potentiation of opioid analgesia occurs in humans, its demonstration may require higher doses or chronic treatment.

Administration, Oral↗
PubMed1992

New Granada Medium for detection and identification of group B streptococci.

A methotrexate-containing medium for the detection of beta-hemolytic group B streptococci from clinical specimens on the basis of detection of pigment is described. The medium contained peptone, starch, serum, MgSO4, glucose, pyruvate, methotrexate (as pigment enhancer), phosphate-morpholine-propanesulfonic acid buffer, and selective agents. The recovery of beta-hemolytic group B streptococci was comparable to that obtained with selective broth.

Bacteriological Techniques↗
PubMed1992

Bronchoconstriction in helminthic infection.

In order to determine whether infection by helminthic parasites can be associated with a state of bronchoconstriction, we evaluated the response to the inhalation of a bronchodilator before and after long-term anthelmintic treatment of children in a urban slum of Caracas, Venezuela. In untreated children, a direct association was found between the degree of helminthic infection and the increase in peak expiratory flow rates caused by the bronchodilator. The elimination of the infections was accompanied by a significant decrease in response to the bronchodilator. These results indicate that helminthic infection could contribute to the development of asthmatic conditions in areas where these parasites are endemic.

Albuterol↗
PubMed1992

Patterns of basement membrane laminin distribution in nonneoplastic and neoplastic thyroid tissue.

Laminin, a major basement membrane component, is typically absent or partially lost around the epithelial elements of most invasive carcinomas. To evaluate the distribution of laminin in both primary and metastatic thyroid tumors, we studied 14 benign thyroid lesions (eight adenomas, two Graves' disease, two Hashimoto's thyroiditis, one adenomatous hyperplasia, one nodular goiter), 20 carcinomas (seven papillary, six tall cell variant, four follicular, three Hürthle), and eight metastases (five tall cell variant, three follicular) utilizing a polyclonal antibody against highly purified, nidogen-free laminin. All benign lesions showed positive, linear immunostaining along basement membranes. Partial loss or absence of laminin was seen in the solid areas of all types of thyroid carcinomas examined; well-differentiated papillary and follicular tumors, as well as papillary and follicular areas of more poorly differentiated neoplasms, maintained linear laminin immunostaining in the papillary cores beneath the epithelial cells and around follicles. A similar correlation between laminin deposition and architectural organization was seen in metastatic lesions. Hürthle cell carcinomas had a unique fragmented, pericellular immunostaining pattern around individual tumor cells, suggesting uncontrolled laminin synthesis. Our findings suggest that preservation of laminin production in thyroid tumors reflects their degree of differentiation and that absence of laminin correlates with lack of structural organization rather than reflecting invasive and metastatic potential.

Basement Membrane↗
PubMed1992

Bitter cassava poisoning in eight children: a case report.

Bitter cassava poisoning in 8 children is reported. The incidence of bright cherry-red blood is emphasized. These patients were in bad condition, but they survived although they received different therapies. Four of them were treated with sodium nitrite and thiosulfate and the remainder with hydroxocobalamin alone. This latter drug may be useful in less severe circumstances.

Antidotes↗
PubMed1991

Inhibition of antiskin allograft immunity induced by infusions with photoinactivated effector T lymphocytes (PET cells). Is in vivo cell transferrable?

We previously reported producing donor-specific tolerance to alloantigens by intravenous exposure to pretreated antidonor T cells. The current study extends that work by adoptively transferring the donor-specific tolerance into naive syngeneic recipients. Eight days after BALB/c mice received histoincompatible CBA/j skin grafts, their splenocytes which included an expanded population of cells mediating rejection were treated with 100 ng/ml 8-methoxypsoralen (8-MOP) photoactivated by 1 Joule/cm2 of ultraviolet A (UVA) light prior to infusion into naive BALB/c recipients. Whereas 8-MOP itself is biologically inert, photoactivated 8-MOP crosslinks DNA by covalently binding to pyrimidine bases. Recipient BALB/c mice which had been previously demonstrated to be hyporesponsive to CBA/j alloantigens in mixed leukocyte culture (MLC), cytotoxicity (CTL) and in vivo delayed type hypersensitivity (DTH) assays were the donors of spleen cells for the adoptive transfer experiments. Fifty to one hundred million viable spleen cells from these pretreated BALB/c mice were transferred into naive syngeneic recipients which then were tested for DTH response and allograft survival to the relevant and irrelevant antigens. The radiosensitivity of this transferrable suppression was evaluated by exposing the adoptively transferred cell population to 3200 rads of C-irradiation prior to cell transfer. The phenotype of the cells transferring this suppressive response was performed by depleting specific populations of cells with monoclonal antibodies prior to cell transfer. In vivo the DTH response of the pretreated BALB/c mice was specifically suppressed to the relevant alloantigen, correlating with retention of CBA/j skin grafts for up to 42 days post engraftment without visual evidence of rejection, in comparison to control mice complete rejection of the skin graft in less than 8 days. In vitro, splenocytes from BALB/c recipients of pretreated syngeneic splenocytes containing large numbers of BALB/c anti-CBA/j T cells proliferated less in MLC and generated lower cytotoxic T cell responses to CBA/j alloantigens than did controls and suppressed the naive and sensitized BALB/c MLC and CTL responses to CBA/j alloantigen. This specific suppressive response to alloantigen was optimally transferred into syngeneic naive recipients when the adoptive transfer was performed on the sixth day after the last infusion received by the spleen cell donor mice. The adoptive transfer of this suppressive response was abrogated by the prior X-irradiation of the donor spleen cells and significantly abolished by the depletion of Thy-1+, Lyt-2+, L3T4- T lymphocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Antigen-specific tolerance induced by autoimmunization with photoinactivated syngeneic effector cells.

Development of a protocol that could invoke specific suppression of an undesired immune response, while sparing normal immune competence, would be of great clinical value. This report demonstrates that multiple infusions of splenocytes sensitized in vivo to sheep red blood cells (SRBC) and photoinactivated in vitro with 8-methoxypsoralen and ultraviolet A light can render a syngeneic recipient selectively unresponsive to subsequent challenge with this antigen. Mice treated in this fashion did not develop a T cell-mediated delayed type hypersensitivity (DTH) reaction to SRBC. In contrast, control mice exposed to nonimmune splenocytes pretreated in an identical manner developed a normal DTH response to SRBC, thereby demonstrating that drug and light in the absence of effector T cells were not suppressive. Inhibition of the DTH response was antigen specific, since animals rendered unresponsive to SRBC developed a normal DTH response to chicken red blood cells. Cell transfer experiments demonstrated that unprimed recipients of splenocytes from mice rendered unresponsive to SRBC could not mount a DTH reaction when challenged. Moreover, this procedure can also suppress established immunity to that antigen. The use of photoinactivated syngeneic antigen-reactive effector cells as immunosuppression agents suggests that this method may be clinically useful in inhibiting pathogenic antigen-specific immunologic reactions.

Animals↗
PubMed1991

Nucleotide sequence and expression of the human gene encoding apolipoprotein H (beta 2-glycoprotein I).

Human apolipoprotein H (ApoH), also called beta 2-glycoprotein I, is a 50-kDa serum glycoprotein whose function is not clearly defined. We have cloned and sequenced ApoH cDNAs both from human liver and from a human hepatoma cell line (HepG2). Both cDNA sequences predict a protein 345 amino acids (aa) in length. This sequence includes a 19-aa hydrophobic, N-terminal signal sequence which is not present in the mature protein [Lozier et al., Proc. Natl. Acad. Sci. USA 81 (1984) 3640-3644]. It differs from this previously reported aa sequence at two positions, both of which strengthen the conservation among the four short consensus repeats within the ApoH molecule. COS-1 cells transiently transfected with the ApoH cDNA in a eukaryotic expression vector produced a single species of ApoH mRNA and secreted in the ApoH protein. The level of ApoH mRNA expressed by HepG2 cells is downregulated by incubation with inflammatory mediators, implying that ApoH is a negative acute-phase protein.

Acute-Phase Reaction↗
PubMed1991

[Recurrent inguinal hernia].

Inguinal hernias that recur after parietal herniorraphy are still frequent, the mean recurrence figures obtained from a review of the literature being 7.3, 5.2 and 1.1 percent respectively after the Bassini, Mc Vay and Shouldice repair techniques. The variability of bibliographical data and the factors which facilitate recurrence are analyzed; the choice of the approach route and of the most reliable repair technique is discussed. Although the present tendency is increasingly towards the use of preperitoneal prostheses, there is still room for reoperative surgery by the inguinal route, combining herniorraphy with hernioplasty, and without prosthesis.

Epidemiology↗
PubMed1991

Abnormal proteolytic degradation of von Willebrand factor after desmopressin infusion in a new subtype of von Willebrand disease (ID).

We describe two members of a single family, father and son, with mild factor XII deficiency associated to von Willebrand disease (vWD) with aberrant structure in whom distinct multimeric abnormalities and an abnormal proteolytic processing of von Willebrand factor (vWF) after desmopressin (DDAVP) administration were present. They had a mild bleeding history, low levels of vWF-related activities, and a prolonged bleeding time. Low-resolution agarose gel electrophoresis showed a vWF with all size multimers in plasma and platelets. Higher-resolution agarose gels demonstrated that the main band was present, but the relative proportion of the satellite bands was markedly reduced. The smallest oligomer was not increased. After the infusion of DDAVP to the father, a transient increase in the relative proportion of the satellite bands was seen, as described in normal individuals. No difference in the structure of vWF was observed when blood was collected with proteinase inhibitors. The analysis of native subunits of vWF and their proteolytic derived fragments, after DDAVP administration, showed a temporary augmentation of the 176 kDa fragment, as seen in normal subjects, as well as an increase of the 189 kDa fragment. This finding had not been reported previously either in normal individuals or in patients with vWD.

Adult↗
PubMed1991

Endocytosis of the TCR/CD3 complex and the class-I major histocompatibility complex in a human T cell line.

We investigated the expression of the T cell receptor (TCR)/CD3 complex on a CD4-positive human T cell lymphoma cell line treated with phorbol myristate acetate (PMA) and/or CA2+ ionophore using fluorescence flow cytometry and fluorescence microscopic analysis. PMA induced a significant decrease in the expression of the CD3 complex on the cell membranes. Fluorescence microscopy confirmed that the down regulation is due to internalization of the antigens. Ca2+ ionophore treatment had no effect on the internalization of the CD3 complex. Double staining revealed that the vesicles containing the internalized CD3 complex and those containing intra-cytoplasmic class I major histocompatibility complex antigen had similar distribution in the PMA-stimulated cells, implying coexistence of these two antigens in a cytoplasmic perinuclear distribution.

Antigens, Differentiation, T-Lymphocyte↗