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Biomedical subjects

M A Sanchez

Publications and source records attributed to M A Sanchez.

At least 37 records · Page 2Linked to original sources
PubMed1995

The intrinsic transmission dynamics of tuberculosis epidemics.

In developed countries the major tuberculosis epidemics declined long before the disease became curable in the 1940s. We present a theoretical framework for assessing the intrinsic transmission dynamics of tuberculosis. We demonstrate that it takes one to several hundred years for a tuberculosis epidemic to rise, fall and reach a stable endemic level. Our results suggest that some of the decline of tuberculosis is simply due to the natural behaviour of an epidemic. Although other factors must also have contributed to the decline, these causal factors were constrained to operate within the slow response time dictated by the intrinsic dynamics.

Disease Outbreaks↗
PubMed1995

Comparative analgesic efficacy of patient-controlled analgesia with ketorolac versus morphine after elective intraabdominal operations.

We conducted a randomized, double-blind trial to compare analgesia and side effects produced by ketorolac and morphine during postoperative patient-controlled analgesia (PCA). Fifty-one patients (ASA classes I and II) undergoing elective intraabdominal procedures were assigned to one of two groups. When postoperative pain first increased to 4/10 (by visual analog scale [VAS]), patients were randomly assigned to one of two groups. Group 1 (n = 25) received up to two intravenous (IV) boluses of 5 mg of morphine followed by IV morphine PCA, whereas those in Group 2 (n = 26) received up to two IV boluses of 30 mg ketorolac, then IV ketorolac PCA. Up to two rescue doses of morphine (5 mg per dose, subcutaneously) were given in either group when pain during deep inhalation exceeded 5/10 on VAS. Ten patients from Group 1 required rescue doses of morphine compared to 22 patients from Group 2 (P < 0.0011). Two and 16 patients from Groups 1 and 2, respectively, were withdrawn because of inadequate analgesia (P < 0.01). Mean pain scores were less in Group 1 than in Group 2 at each time, but only significantly so at 15 min (P < 0.0021), 30 min (P < 0.0336), and 24 h (P < 0.0358) after starting PCA. Time to acceptance of oral liquids was equivalent in Groups 1 and 2 (22 h and 21 h, respectively). IV ketorolac PCA, although well tolerated, has limited effectiveness as the sole postoperative analgesic after intraabdominal operations.

Abdomen↗
PubMed1995

Histological changes in the uterus during postpartum in the mare.

An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reaction with neutrophils and phagocitic cells. On day 7 postpartum, the histology of the endometrium was similar to the normal proestrus with cuboidal luminal epithelium and an oedematous stromal tissue. The changes are usually completed within days 9 and 10 postpartum with the histologically typical appearance of estrus in mares.

Animals↗
PubMed1995

Immunocytochemical study of type IV collagen and laminin in canine mammary tumours.

We performed an immunohistochemical study of the basement membrane (BM) proteins laminin and type IV collagen in 35 canine mammary tumours, histologically classified according to the World Health Organization's suggested classification. Laminin and type IV collagen were seen in extracellular locations but only laminin was present in epithelial and myoepithelial cells and chondrocytes. The BM was always continuous in adenomas and fibroadenomas. In the 20 malignant tumours studied, the basement membrane was continuous in one, discontinuous in five, and virtually absent in 14. When present, the BM of malignant tumours varied in width and distribution in the same area. The benign and malignant mixed tumours did not have BM separating epithelial and newly-formed mesenchymal structures. In areas of abundant myoepithelial cells in complex and mixed tumours, both benign and malignant, there were groups of BM fragments which differed in length and thickness and occasionally formed tangles. We have called these 'membranous thickets'. Our results indicate that myoepithelial cells are the main source of the BM proteins laminin and type IV collagen in canine mammary tumours.

Adenocarcinoma↗
PubMed1994

Expression of fibronectin and its integrin receptor alpha 5 beta 1 in canine mammary tumours.

Fibronectin and its integrin receptor alpha 5 beta 1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the alpha 5 beta 1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of alpha 5 beta 1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of alpha 5 and beta 1 was diminished in metastatic tumours but there were some alpha 5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of alpha 5 beta 1 and the expression of fibronectin in canine mammary tumours.

Animals↗
PubMed1994

New translocations [t(6;15)(p25;q22) and t(6;19)(q16;q13.3)] with t(9;22)(q34;q11) in a Ph-positive chronic myelogenous leukemia.

A case with typical features of chronic myelogenous leukemia (CML) with two complex aberrations in addition to the standard t(9;22) is reported. Cytogenetic evaluation of the patient's bone marrow cells (BMC) showed 46,XX,t(6;19)(q16;p13.3),t(9;22)(q34;q11) in 60% of the mitotic cells and 46,XX,idem, t(6;15)(p25;q22) in the remaining 40% dividing cells. The patient's peripheral blood smear exhibited the usual differential observed in chronic-phase CML and was clinically indistinguishable from patients with the t(9;22) as the only translocation. We performed Southern blotting on BglII-digested DNA with the Trans-Probe (OSI) and in addition to the 4.8-, 2.3-, and 1.1-kilobase (kb) germline fragments, we detected an additional fragment at 7 kb. This probe spans the entire 5.8-kb M-breakpoint cluster region (BCR), and a single breakpoint in this region will appear as either one or two additional fragments. Because only one additional fragment was observed, both cell lines apparently share the same breakpoint in the ABL/BCR gene. Apparently the second aberrant cell line with the additional t(6;15) represents clonal evolution of the original abnormal clone.

Adult↗
PubMed1993

A variable DNA region of Entamoeba histolytica is expressed in several transcripts which differ in genetically related clones.

A highly variable DNA region (EhVR1), isolated from Entamoeba histolytica clone A, strain HM1:IMSS, is transcribed into several transcripts, which differ in genetically related clones. EhVR1 (3.5 kb) is composed of two contiguous fragments; one of these 1.9 kb long, at the 3' end, identified similar transcripts in clones A, L6 and C2 (all derived from strain HM1:IMMS), the other of 1.6 kb, at the 5' end, detected 0.5, 0.6 and 0.7 kb transcripts only in clone A. Variability of the 1.6 kb fragment was found even within the same clone maintained under different conditions. EhVR1 was localized to 1.3 and 1.4 Mb linear chromosomes and also found in circular molecules. The sequence of the 1.6 kb fragment revealed the presence of a large number of different repeats, including inverted and palindromic repeats. A p145 sequence, previously detected in episomal DNA of the amoeba, was found at the 5' end of EhVR1. The presence of EhVR1 in linear and circular molecules, its high number of repeats, and its variability in genetically related clones suggest the existence of DNA regions that undergo dynamic non-reciprocal recombination between circular episomes and linear chromosomes, and may thus contribute to variability in the trophozoite genome.

Animals↗
PubMed1993

The cutaneous lesion in American leishmaniasis: leukocyte subsets, cellular interaction and cytokine production.

Interactions between immunocompetent cells require the participation of T cell antigen receptor (TCR) and the integrin lymphocyte function-associated molecule-1 (LFA-1, CD11a/CD18). These interactions are mediated by interlinking cytokines, which are important in determining the type of immune response. In the present study, we have shown that in American cutaneous leishmaniasis (ACL) lesions, most infiltrating T cells expressed the alpha beta TCR including those selectively migrating to the epidermis. In contrast, gamma delta T cells were abundant in localized (LCL) and scarce in muco-cutaneous (MCL) and diffuse (DCL) cutaneous leishmaniasis, suggesting a role in effective granulomas. There were differences in the expression of LFA-1 alpha and beta subunits, with most cells expressing LFA-1 beta. The ratio LFA-1 beta/LFA-1 alpha was higher in LCL (11.8:1) than in MCL (3.3:1) and DCL (2.4:1). Similar results were observed in Leishmania mexicana-infected C57BL/6 mice. DCL lesions showed a higher proportion of LFA-1 alpha+ cells than MCL and LCL lesions. A reverse-transcriptase polymerase chain reaction (RT-PCR) analysis of the cytokine profiles showed that most T cells present in the MCL and DCL lesions secrete a mixture of Type 1 and Type 2 cytokine patterns, but in DCL granulomas predominate the Type 2 cytokines. In LCL the cytokine patterns show a preponderance of INF gamma over IL-4, and low levels of IL-5 and IL-10, suggesting a Type 1 cytokine profile.

Animals↗
PubMed1992

Immunocytochemical identification of a bovine peritoneal mesothelioma.

Peritoneal mesotheliomas are uncommon among cows although there has been an increase in the frequency of diagnosis of this neoplasia in the past few years. The case of a 2 year old cow is described. On post-mortem examination, several nodules of variable size were found in the peritoneal cavity. These nodules fused together, but they did not go deep into the organs. Histologically, such nodules were formed by a population of fusiform cells of malignant morphological character and sarcomatous appearance. Immunocytochemical study, using P.A.P. techniques, showed a highly positive reaction towards vimentin and a negative reaction towards wide-spectrum cytokeratins, hence suggesting a mesenchymal origin of the neoplasia. According to the histopathological study, a multifocal peritoneal mesothelioma of sarcomatous appearance was identified.

Animals↗
PubMed1988

Odor and taste aversions conditioned in anesthetized rats.

Conditioned flavor aversions (CFA) are acquired by anesthetized rats but effects of various anesthetics on acquisition of aversions for separate odor and taste components are unknown. In Experiment 1, rats drank tomato juice and then were tranquilized with "Innovar-Vet" or "Rompun" before receiving injections of lithium chloride. Neither drug interfered with acquisition of aversions. Innovar-Vet alone produced no aversions; Rompun alone produced mild aversions but did not enhance aversions when combined with lithium. In Experiments 2 and 3, rats received a compound odor/taste cue as they drank and then were anesthetized with pentobarbital before lithium injections. Anesthesia alone produced negligible aversions but facilitated taste-lithium aversions. During odor tests, odor aversions were weaker than taste aversions. These data extend previous work and suggest that CFA does not result from ordinary classical conditioning. A tripartite notation that unites CFA and classical conditioning is discussed.

Anesthetics↗
PubMed1988

Infections caused by central venous catheters in patients with acquired immunodeficiency syndrome.

We assessed infectious complications of long-term percutaneous central venous catheterization in patients with acquired immunodeficiency syndrome (AIDS). We evaluated 98 consecutive patients, accounting for 6,298 catheter days. Catheter-associated bacteremia occurred in 3% of patients, a rate of 0.128%/patient-catheter day. Only bacterial pathogens--Pseudomonas, Serratia, and Staphylococcus species--were isolated. Five patients had infection at the catheter exit site. The length of time catheters were indwelling was not significantly different in patients with and those without infections. Percutaneous, multiple-use central venous catheters are safe and well accepted by patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Analysis of DNA distribution in Kaposi's sarcoma in patients with and without the acquired immune deficiency syndrome.

While Kaposi's sarcoma in patients with the acquired immune deficiency syndrome (AIDS) may present as a multicentric disease with progressive organ involvement, the classic form of Kaposi's sarcoma is an indolent tumor seldom affecting extracutaneous areas and almost never responsible for the patient's demise. An attempt was made to correlate these clinical differences with the nuclear DNA content of tumor cells in histologic sections from 15 patients (9 with AIDS and 6 without AIDS). All tumors showed a similar DNA distribution pattern, with most cells appearing diploid, indicative of a low malignant potential. These findings indicate that Kaposi's sarcoma of both AIDS and non-AIDS patients is a tumor of intrinsically low malignancy and that lack of immune surveillance is most probably responsible for its aggressive biologic behavior in many AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1978

Gastritis polyposa in a gastroenterostomy anastomosis.

Review of the literature finds a strong point made for polyps of the stomach to be considered as "sentinels" of malignancy. The controversy over the transformation of gastric polyps into malignant tumors is coming to an end. Apparently, everyone agrees with a high incidence of malignant transformation in adenomatous polyps. The recent case report by Papp and Joseph of a hyperplastic polyp with malignant changes, seems to demonstrate that all polyps can undergo neoplastic transformation. We believe that every gastrectomized patient should be gastroscoped once a year, even with an absence of symptoms or lack of x-ray findings. Any polyp, adenomatous or hyperplastic, should be removed endoscopically and studied histopathologically for possible association with or development of carcinoma.

Adult↗
PubMedDate not supplied

Fine needle aspiration diagnosis of intramuscular bacillary angiomatosis. A case report.

BACKGROUND: Bacillary angiomatosis (BA) is a localized infectious process that affects primarily patients with the acquired immunodeficiency syndrome. The microorganisms implicated in the pathogenesis of this disease belong to the Rickettsiaceae family. CASE: A 43-year-old, human immunodeficiency syndrome-positive male presented with diffuse swelling in the right deltoid area. A neoplastic process was considered in the differential diagnosis. Fine needle aspiration biopsy showed proliferation of blood vessels lined with plump endothelial cells, and the interstitial space was occupied by neutrophilic infiltrate, leukocytoclastic debris and clumps of characteristic amphophilic, granular material. Warthin-Starry stain demonstrated clusters of bacilli diagnostic of bacillary angiomatosis. CONCLUSION: The diagnosis of this entity, made by fine needle aspiration cytology (as the only diagnostic procedure), was instrumental in preventing further surgical manipulation and in initiating appropriate and immediate antibiotic therapy.

AIDS-Related Opportunistic Infections↗