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Biomedical subjects

C F Garcia

Publications and source records attributed to C F Garcia.

18 recordsLinked to original sources
PubMed2006

Structural characterization of the lipovitellin from the shrimp Macrobrachium borellii.

In oviparous species, proteins and lipids are found in the vitellus forming lipoproteins called lipovitellins. They are an important energy source for embryos development and larvae growth and survival. We have previously isolated and partially characterized the sole egg cytosolic lipovitellin from the freshwater shrimp Macrobrachium borellii. It is a native protein of 440 kDa, composed of two subunits of 94 and 112 kDa. In the present work we studied size, shape and structure of M. borellii lipovitellin using electron microscopy, crosslinking reagents, MALDI-TOF, circular dichroism, fluorescence and partial proteolysis. The results showed that lipovitellin has a quasi spherical morphology with an estimated diameter of 18.5+/-3.5 nm. It appears to be composed of two subunits of 94 kDa, and one of 112 kDa. The larger subunit is more susceptible to trypsinolysis, indicating that it is less compactly folded and/or more exposed to the aqueous medium than the 94 kDa subunits. The hetero-trimer is held together by non-covalent interactions. Peptide mass fingerprinting by MALDI-TOF, produced 42 polypeptides matching to a vitellogenin of a related species (Macrobrachium rosenbergii). Circular dichroism indicated that this protein contains 35.7% alpha-helix, 16.6% beta-sheet and 20% turns. Tryptophan fluorescence emission, at a maximum of 334 nm, indicated that the environment polarity of these aromatic residues is similar to that of other crustacean lipoproteins.

Amino Acid Sequence↗
PubMed2002

Effect of fenitrothion on the physical properties of crustacean lipoproteins.

The effect of the liposoluble organophosphorus insecticide fenitrothion (FS) on lipid packing and rotation of two crustacean plasma HDL was investigated. These lipoproteins, HDL-1 and HDL-2, differed in their lipid composition, but their lipid/protein ratios were similar. The rotational behavior of the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and 3-(p-(6-phenyl)-1,3,5-hexatrienyl) phenylpropionic acid (DPH-PA) was used to obtain information about the lipid dynamics in the outer and inner regions, respectively, of the lipid phase of the lipoproteins. Fluorescent steady-state anisotropy (r(s)), lifetime (tau), rotational correlation time (tau(r)), and the limiting anisotropy (r(infinity)) of these probes were measured in the lipoproteins exposed to different concentrations of FS in vitro. The results showed the penetration of FS into both plasma lipoproteins, altering the lipid dynamics of the inner as well as the outer regions. The overall effect of the insecticide was to induce an increase in the lipid order in a concentration-dependent fashion. DPH and DPH-PA fluorescence-lifetime shortening indicated that FS increased the polarity of the probe environment, suggesting an enhanced water penetration into the lipoprotein lipid phase, may be due to the induction of failures in the lipid packing. Even in the absence of FS, a higher ordering of the lipid phase was found in HDL-2 compared to HDL-1, a fact that might be attributed to a higher percentage of sphingomyelin in HDL-2.

Animals↗
PubMed1999

Monocytes affect cell-cycle progression but not baseline frequency of sister chromatid exchanges of pig lymphocytes.

The effect of pig monocytes (MNs) on the baseline frequency of sister chromatid exchanges (SCEs) and cell-cycle progression of pig lymphocytes was studied in plasma leukocyte (PLCs) and whole blood leukocyte cultures (WBCs). No variation in SCE frequency was observed between control WBC and PLC, nor did the addition of pig MNs to PLCs modify the baseline frequency of SCEs. Cell proliferation was slower in PLCs than in WBCs. Variations in cell-cycle progression of pig lymphocytes from PLC were observed both in the absence and presence of adherent cells in the culture. In MN-free cultures, lymphocytes proliferated foster than in parallel PLC cultures. However, when MNs were seeded into the cultures, cell-cycle progression gradually slowed as a function of the concentration of adherent cells present in the cultures. This finding shows that pig MNs modulate the in vitro cell-cycle progression of pig lymphocytes in a dose-dependent manner and that the low baseline SCE frequency of pig lymphocytes is independent of the presence or absence of MNs in the culture.

Animals↗
PubMed1990

Chronic cholestasis, paucity of bile ducts, red cell aplasia, and the Stevens-Johnson syndrome. An ampicillin-associated case.

The unique case of severe chronic cholestasis with paucity of bile ducts accompanied by pure red cell aplasia and the Stevens-Johnson syndrome in a 35-year-old woman after ampicillin ingestion is presented. The patient improved gradually and is asymptomatic 4 years later. Sequential histological and clinical follow-up substantiate the course of her disease.

Adult↗
PubMed1990

HIV-1, sexual practices, and contact with foreigners in homosexual men in Colombia, South America.

From October 1985 to November 1987, a sample of 294 Colombian homosexual men volunteered to answer a questionnaire on sexual practices and consented to HIV-1 testing. Testing for HIV-1 was performed using an ELISA and those positive were confirmed with envelope- and core-specific ELISAs. Statistical methods for data analysis included Mantel-Haenszel methods on contingency tables. The overall seropositivity rate was 21.1%. Subjects who reported a receptive role (either as predominantly receptive or as mixed receptive-insertive intercourse) had a seropositivity rate of 23.7%, which was significantly higher than the 10.3% found in those reporting predominantly insertive intercourse (RR = 2.30, 95% C.I. = 1.16-4.57). For subjects reporting receptive intercourse, sexual contact with foreign visitors was a significant risk factor for HIV-1 infection (RR = 1.84, 95% C.I. = 1.13-3.00). Factors of borderline significance included having had more than ten homosexual partners in the preceding year (RR = 1.53) and a history of international travel (RR = 1.43). These associations did not hold for those reporting predominantly insertive intercourse. The data indicate the need to monitor the spread of HIV-1 at the international level and provide information on subgroups of high transmission rates.

Adult↗
PubMed1987

Quantitation and estimation of lymphocyte subsets in tissue sections. Comparison with flow cytometry.

A quantitation method for lymphocyte subsets in immunoperoxidase-stained frozen tissue sections was compared with flow cytometry in 23 cases of non-Hodgkin's lymphoma. Close correlations were obtained, demonstrating the accuracy of the technic. Weak intensity of fluorescence and fragility of the tumor cells during the fluorescence-activated cell sorter (FACS) analyses were the most likely explanations for a number of the discrepancies observed. The tissue quantitation method was precise, particularly at low values, where it was better than the FACS. A simpler and faster estimation method employing categories within 10 percentage units was also tested in this study; this method correlated as well with the FACS as the quantitation method and gave the best interobserver correlations.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Expression of Tac antigen by non-Hodgkin's lymphomas.

Anti-Tac is a monoclonal antibody that appears to recognize the interleukin-2 receptor. With the use of a frozen-section immunoperoxidase technic, a large series of non-Hodgkin's lymphomas were investigated for the presence of Tac-antigen on neoplastic cells. Approximately one-fourth of cases expressed the Tac antigen, including 27% of B-lineage lymphomas, 6% of the T-lineage lymphomas, and three of four cases of Ki-1-expressing lymphoma. The B-lineage lymphomas with the highest incidence of Tac antigen expression were the large cell lymphomas, both diffuse and follicular, where about one-half of cases expressed the Tac antigen. All major categories of lymphoma expressed Tac except plasma-cytoma/myeloma, small noncleaved cell (Burkitt's and non-Burkitt's), and lymphoblastic malignancies.

Antibodies, Monoclonal↗
PubMed1987

Expression of the Leu-8 antigen by B-cell lymphomas.

The Leu-8 antigen is found on the surface of many hematologic cells, including many T- and B-lymphocytes. With the use of a frozen-section immunoperoxidase technic, 152 B-cell non-Hodgkin's lymphomas were examined for Leu-8 expression. Of these lymphomas, 53% expressed Leu-8. Subclassification of the lymphomas with the use of the International Working Formulation showed that most small lymphocytic, intermediate lymphocytic, and diffuse large cell lymphomas and about half of diffuse small cleaved, diffuse mixed, and follicular lymphomas expressed Leu-8. In contrast, all 17 cases of small noncleaved cell (Burkitt's) lymphoma and 9 of 10 cases of multiple myeloma/plasmacytoma were Leu-8 negative. These results indicate that Leu-8 is expressed on a wide variety of B-cell lymphomas and that differences in Leu-8 expression may be useful in the diagnostic separation of small lymphocytic lymphoma with plasmacytoid features from multiple myeloma/plasmacytoma, and diffuse large cell lymphoma from Burkitt's lymphoma.

Antibodies, Monoclonal↗
PubMed1987

Studies on B lymphoid tumors treated with monoclonal anti-idiotype antibodies: correlation with clinical responses.

Monoclonal anti-idiotype antibodies can be made which are exquisitely specific for B lymphocytic malignancies. We have conducted a clinical trial in which some patients' tumors regressed after infusion of such antibodies. Here, we evaluated characteristics of the antibodies, the tumors, and the patients to determine which features best correlated with the clinical response. Neither the isotype of the murine antibodies, nor their avidity were predictive of clinical outcome. The specific epitope to which the antibodies bound was characterized by immunochemical techniques. Reactivity with a heavy-light chain combinatorial determinant correlated somewhat with clinical effect. Variations in the characteristics of the individual tumors such as antigen sites per cell and ability to modulate the surface immunoglobulin were not predictive of response. In one patient with prolymphocytic leukemia the anti-idiotype antibody had a direct antiproliferative effect on tumor cells in vitro. This patient's tumor response was explainable by such a direct mechanism. In the other patients, who had lymphomas, therapeutic outcome correlated with the number of host nontumor cells infiltrating the tumor. The vast majority of these nontumor cells were mature T lymphocytes of the Leu 4, Leu 3 (T3, T4) phenotype. Thus, a preexistent host-tumor interaction seems to be important in the in vivo effect of anti-idiotype antibodies in B cell tumors.

Antibodies, Anti-Idiotypic↗
PubMed1986

Small noncleaved cell lymphoma: an immunophenotypic study of 18 cases and comparison with large cell lymphoma.

Eighteen cases of small noncleaved cell lymphoma (SNCL) were studied with a large panel of monoclonal antibodies applied to tissue frozen sections and compared with 18 cases of immunoglobulin-expressing diffuse large cell lymphoma (DLCL). Immunoglobulin expression was seen in all cases of SNCL, with a predominance of cases showing lambda light chain restriction. Expression of mu and delta heavy chains was common, but gamma and alpha chain expression was uncommon. In the cases of SNCL T015, B1, B2, 41H, BA-1, BA-2, Ia, CALLA, and OKT10 were generally expressed, and a large percentage of cells expressed Ki-67. Only rare expression of T05, Leu-8, and Leu-9 was seen, and in no case was reactivity with anti-Tac antibodies observed. In contrast, the immunoglobulin-expressing DLCLs showed the typical predominance of cases of kappa light chain restriction, a lower proportion of cases with mu or delta expression, and a higher proportion of cases with gamma expression. A lower incidence of Leu-8, T05, and Tac expression and a higher incidence of BA-1, CALLA, Ki-67 and OKT10 were seen in the SNCLs as compared with the DLCLs. It is concluded that immunologic studies may be of considerable aid in the differential diagnosis of SNCL and DLCL.

Abdominal Neoplasms↗
PubMed1986

The immunohistology of the persistent generalized lymphadenopathy syndrome (PGL).

The authors employed a large panel of monoclonal antibodies to characterize and quantitate lymphoid subpopulations within the paracortex, mantle, and germinal centers of frozen sections of lymph nodes from 18 patients with the persistent generalized lymphadenopathy (PGL) syndrome and five heterosexual controls. The authors' data indicate that Leu-3+ phenotypic T-helper cells (TH) are reduced within all three compartments, while T-cytotoxic-suppressor cells (Tcs) are increased. Using the antibody 9.3, which allows dissection of the Leu-2+ Tcs subset into 9.3+ cytotoxic cells (Tc) and 9.3- suppressor cells (Ts), the authors found that the Ts subset is increased in the lymph nodes of these patients. In contrast to acquired immune deficiency syndrome (AIDS) patients, paracortical total T-cells and Leu-8+ cells appear to be preserved in patients with PGL. Study of TH and Tcs subpopulations in peripheral blood in 12 of these patients revealed inverted ratios (mean, 0.59), which did not correlate with those seen in the lymph nodes. Although the paracortical TH/Tcs ratios were significantly reduced (mean, 1.44) they were not inverted, in contrast to some other reported series. In aggregate, these data suggest that, relative to AIDS, there is preservation of the paracortical T-cell microenvironment in PGL. Clinically, this correlates with more intact cell-mediated immunity and the absence of opportunistic infections and Kaposi's sarcoma in this patient group. Follicle lysis was present in 11 patients. Increased HLA-DR+ paracortical cells, aggregates of Leu-6+ dendritic cells, decreased TAC+ cells, increased OKT-10+ plasma cells, and increased interstitial immunoglobulin were among the other features observed in these patients.

AIDS-Related Complex↗
PubMed1986

Cutaneous follicular lymphoma.

Fifteen cases of cutaneous follicular lymphoma were evaluated clinically, histologically, and immunologically. Nine of the patients presented with skin disease alone, which showed a predilection for the scalp and forehead. The six remaining cases had either concurrent or secondary cutaneous involvement. All of the cases had a nodular configuration which was evident histologically or immunologically. In many cases, the diagnostic microscopic fields were in the deep dermis or subcutis, with nonspecific inflammation in the superficial dermis. The cases consisted of five small cleaved, seven mixed, and three large cell follicular lymphomas. A senior dermatopathologist diagnosed four of the 15 cases as benign, indicating the difficulty of diagnosis by morphology alone when the biopsy is small or the inflammatory component is prominent. This underscores the importance of large, deep biopsies for accurate histologic diagnosis. Immunological studies confirmed the B cell lineage of these lesions. An unexpectedly high proportion of immunoglobulin-negative cases (eight cases) was found, especially among the primary cutaneous follicular lymphomas (six of nine cases). Immunoglobulin-expressing cases exhibited monotypic immunoglobulin light-chain staining of tumor cells. In all cases, the dendritic reticulum cell network within lymphoma follicles lacked the polytypic immunoglobulin complexes characteristic of reactive follicles. As described previously for follicular lymphomas in lymph nodes, many cases exhibited polytypic follicular mantle zones similar to reactive follicles. The low-grade nature of these lymphomas was supported by clinical follow-up. We conclude that given adequate sampling, cutaneous follicular lymphomas can usually be diagnosed by histologic criteria similar to those used for lymph nodes; however, immunohistologic studies are an important adjunct.

Adult↗
PubMed1986

Follicular large cell lymphoma. An immunophenotype study.

The authors investigated 17 cases of follicular large cell lymphoma using monoclonal antibodies applied to frozen sections. The neoplastic cells in 11 cases (65%) showed evidence of immunoglobulin expression similar to the reported percentage of immunoglobulin expressing diffuse large cell lymphomas and lower than seen in low grade follicular lymphomas. All cases showed expression of the B lineage markers T015, B1, and 4G7, and HLA-DR. CALLA was present in all but 1 case, similar to that reported for follicular lymphomas, and much higher than reported for diffuse large cell lymphoma. Approximately one-half of the cases showed weak expression of Tac, 5 cases expressed B2 (C3d), and 3 cases expressed T05 (C3b). Variable expression was seen for the Ki-67 antigen. A CR4/23+, B2+, T05+ dendritic population was identified in all cases. An interfollicular host T-cell infiltrate was noted, mainly phenotypic helper cells. This study demonstrates that follicular large cell lymphoma has immunologic similarities to both diffuse large cell lymphoma and the low grade follicular lymphomas.

Cell Line↗
PubMed1985

Differences in "host infiltrates" among lymphoma patients treated with anti-idiotype antibodies: correlation with treatment response.

To correlate treatment responses with numbers and types of "host cell infiltrates," lymphoid tissues from 10 patients with low-grade B cell malignancies were stained before, during, and after anti-idiotype therapy with a panel of monoclonal antibodies applied to frozen sections. Tissue penetration by the anti-idiotype antibodies was confirmed in five patients by these immunoperoxidase methods. Large numbers of phenotypic T helper cells were the main component of the "host infiltrate" in most patients. Two patients showed a complete and a near-complete clinical remission, four others had partial responses, and four did not respond to therapy. The two patients that developed clinical remission demonstrated the largest number of T cells, T helper cells, TAC+ cells, Leu-7+ cells, and in general the smallest number of proliferating cells as measured by the Ki-67 antibody. Other major differences in host cells were not evident among the patients. These preliminary data suggest that the type and amount of "host infiltrate" in low-grade B cell lymphomas may predict which patients will respond to anti-idiotype therapy.

Animals↗
PubMed1985

The immunohistology of follicle lysis in lymph node biopsies from homosexual men.

Follicle lysis is a characteristic alteration of B cell follicles described recently in lymph node biopsies from homosexual men. It consists of disruption of germinal centers by aggregates of small mature lymphocytes variably associated with erythrocyte extravasation. We studied the immunohistology of follicle lysis identified in lymph node biopsies from 11 homosexual men. The results indicate that follicle lysis has two principal immunohistologic features: (1) intrafollicular aggregates of small lymphocytes predominantly of polytypic mantle B cell phenotype (T015+/Leu-8+/mu+/delta+/k+ or lambda+), and (2) disruption of the normal, unified follicular meshwork of R4/23+ dendritic reticulum cells by these B cell aggregates. These structural alterations may affect the functional integrity of the germinal center as it pertains to the abnormal B cell effector function and the increased prevalence of B cell lymphoma recently documented in the acquired immunodeficiency syndrome and related disorders. Because dendritic reticulum cells weakly express the Leu-3 (T4) antigen, which is known to be an essential component of the receptor for human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) retrovirus infection, it is possible that retroviral infection of dendritic reticulum cells may play a role in the pathogenesis of follicle lysis.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Metered-dose inhaler technique and quality of life with airways disease: assessing the value of the Vitalograph in educational intervention.

The efficacy of delivering medicines by metered-dose inhaler (MDI) is well established, and the patient's technique with MDIs is related directly to achieving the desired clinical outcome. The present study was designed to assess and improve MDI technique by using a Vitalograph Aerosol Inhalation Monitor (VAIM) in an airways disease education programme. Baseline measurements were made immediately prior to educational intervention incorporating feedback from a VAIM unit. At 6 weeks' follow-up, MDI technique was found to have regressed to the sub-optimal measures recorded at baseline prior to educational intervention. However, patients reported a significant improvement in physical function between baseline and follow-up as measured by the Rand 36-Item Health Survey (SF-36), Version 1.0. The results reinforce the need for a longitudinal educational programme for patients prescribed medications delivered by MDI. The VAIM unit provided health educators and patients with both a visual and a quantitative assessment of patients' MDI technique, and was thus of positive value as part of the intervention process.

Adult↗