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Biomedical subjects

A Gonzalez

Publications and source records attributed to A Gonzalez.

At least 181 records · Page 10Linked to original sources
PubMed1993

Hepatitis C virus markers in patients with acute post-transfusion hepatitis treated with interferon alfa-2b.

This trial was undertaken to establish the long term biochemical and serological outcome of patients with acute post-transfusion hepatitis C virus infection after treatment with interferon alfa-2b. After 12 months, 12 patients (eight treated, four controls) had self limited disease and 16 patients (seven treated, nine controls) had chronic disease. After a total mean 31 months of follow up in 23 patients, nine (six treated, three controls) had self limited disease while 14 (five treated, nine controls) developed chronic liver disease; all patients with spontaneous or self limited hepatitis C (HCV) infection maintained normal serum alanine amino-transferase activity and absence of HCV-RNA, and tended to lose anti-HCV antibodies.

Acute Disease↗
PubMed1993

Estrogen carcinogenesis in the hamster kidney: role of cytotoxicity and cell proliferation.

Both natural and synthetic estrogens are capable of inducing renal neoplasms in Syrian hamsters with an incidence approaching 100%. Neither the sequence of events nor the mechanisms involved in estrogen carcinogenesis in this model have been established. Results presented here indicate that estrogen induces renal tubular damage in the hamster kidney that is progressive and cumulative. Tubular injury was evident both as abnormal or lost microvilli, accumulation of cytoplasmic lipid droplets, vacuolization, and increases in secondary and tertiary lysosomes after 1.5 months of diethylstilbestrol (DES) treatment. Increasing tubular damage was evidence by the detachment of tubular cells, cell debris, and occluded renal tubular lumens. In an effort to repair proximal tubular damage in the hamster kidney elicited by estrogens, a 4.0-fold increase in proximal tubule BrdU labeling was evident at 4 months of DES or 17 beta-estradiol (E2) treatment and in earlier estrogen treatment periods (1-3 months). During this period, there was a significant increase in aneuploid cells in the hamster kidney, the near diploid frequency increased more than 6.0-fold, and the near tetraploid frequency increased at least 3.0-fold between 1.5 and 3.5 months of estrogen treatment. Based on these data, the early sequence of events leading to estrogen-induced renal neoplastic transformation in the hamster is presented.

Aneuploidy↗
PubMed1993

Body composition and lipid abnormalities in hispanic and black patients on continuous ambulatory peritoneal dialysis.

Cardiovascular disease is the leading cause of death in patients undergoing maintenance dialysis. This study was undertaken to evaluate the lipid abnormalities and body composition by bioelectrical impedance in patients receiving continuous ambulatory peritoneal dialysis (CAPD). The patients were between the ages of 28 and 77 and had been on dialysis for periods ranging from 6-48 months. Body composition studies performed by electrical impedance showed that the CAPD patients generally had elevated levels of body fat. Most of these patients had waist-to-hip fat ratios of more than 1.0, and lean tissue was decreased. Serum chemistries showed that most of the patients had albumin levels less than 3.5 g/dL. The most frequent lipid abnormalities found were: hypertriglyceridemia; hypercholesterolemia; decreased HDL levels; elevated cholesterol/HDL and apoproteins (Apo B/A-1); and elevated lipoprotein [Lp(a)] levels. Cardiovascular disease was prevalent in the patients studied. Ten had a positive history of angina, with three documented myocardial infarction and two documented cardiovascular disease. In conclusion, standard CAPD treatment may increase the risk of cardiovascular disease.

Adult↗
PubMed1992

Functional interactions between putative intramembrane charged residues in the lactose permease of Escherichia coli.

Using a lactose permease mutant devoid of Cys residue ("C-less permease"), we systematically replaced putative intramembrane charged residues with Cys. Individual replacements for Asp-237, Asp-240, Glu-269, Arg-302, Lys-319, His-322, Glu-325, or Lys-358 abolish active lactose transport. When Asp-237 and Lys-358 are simultaneously replaced with Cys and/or Ala, however, high activity is observed. Therefore, when either Asp-237 or Lys-358 is replaced with a neutral residue, leaving an unpaired charge, the permease is inactivated, but neutral replacement of both residues yields active permease [King, S. C., Hansen, C. L. & Wilson, T. H. (1991) Biochim. Biophys. Acta 1062, 177-186]. Remarkably, moreover, when Asp-237 is interchanged with Lys-358, high activity is observed. The observations provide a strong indication that Asp-237 and Lys-358 interact to form a salt bridge. In addition, the data demonstrate that neither residue nor the salt bridge plays an important role in the transport mechanism. Thirteen additional double mutants were constructed in which a negative and a positively charged residue were replaced with Cys. Only Asp-240-->Cys/Lys-319-->Cys exhibits significant activity, accumulating lactose to 25-30% of the steady state observed with C-less permease. Replacing either Asp-240 or Lys-319 individually with Ala also inactivates the permease, but double mutants with neutral substitutions (Cys and/or Ala) at both positions exhibit essentially the same activity as Asp-240-->Cys/Lys-319-->Cys. In marked contrast to Asp-237 and Lys-358, interchanging Asp-240 and Lys-319 abolishes active lactose transport. The results demonstrate that Asp-240 and Lys-319, like Asp-237 and Lys-358, interact functionally and may form a salt bridge. However, the interaction between Asp-240 and Lys-319 is clearly more complex than the interaction between Asp-237 and Lys-358. In any event, the findings suggest that putative transmembrane helix VII lies next to helices X and XI in the tertiary structure of lactose permease.

Amino Acid Sequence↗
PubMed1992

Effect of MHC class-I transfection on local tumor growth and metastasis in an H-2-negative clone derived from a chemically induced fibrosarcoma.

GR9 is a chemically induced fibrosarcoma composed of clones with different H-2 class-I expression. These clones differ with respect to local growth and spontaneous metastasis. The B9 clone (H-2 negative) is highly tumorigenic (local growth) but of low metastatic potential (spontaneous metastasis assay). We have analyzed the effect that transfection of H-2Dd and H-2Kd genes on this clone have upon local growth, lung colonization after i.v. injection and ability to form spontaneous metastases. The results showed that the effect on local growth of transfection of the Kd-gene was stronger than that of the Dd gene. In addition, B9 co-transfected with H-2Kd and Dd genes showed the highest immunogenic properties in syngeneic BALB/c mice. Interestingly, the pSV2-neo transfected clone gave almost the same result as that obtained with Dd transfection. Lung colonization after i.v. injection of the different clones (experimental metastasis), paralleled the results obtained for local growth: the number of lung nodules followed the cadence KdDd less than Kd less than Dd less than pSV2. Survival of mice was always inversely correlated with local growth, e.g., all mice injected with 5 x 10(5) B9 H-2KdDd transfected cells survived. In contrast, no mice injected with the B9 control did. These differences were abrogated in irradiated and nude BALB/c mice. Finally, all transfected clones remained non-metastatic in a spontaneous metastasis assay, behaving as the control, non-transfected B9 cells.

Animals↗
PubMed1992

Evaluation of anti-HCV positive blood donors identified during routine screening.

Of 30,231 donors tested, 368 (1.2%) were anti-HCV positive. Of these, 254 have been evaluated, with the following results: only 25% have a history of parenteral risk, seroprevalence increases with age and approximately 80% of those that are anti-HCV positive in our population are probably infected with HCV. In addition, an unexpectedly large number of these persons have chronic and/or severe liver disease and will require combined diagnostic approaches for accurate evaluation.

Age Factors↗
PubMed1992

Mouse monoclonal antibodies to swine blood group antigens.

Eight mouse hybridomas with haemagglutination capacity to swine blood group antigens were obtained, three of them producing antibodies capable of being used as blood group reagents. Two detected the Ba factor and another the Fa factor. The others gave non-specific and weak reactions or cross-reaction with antigens present in more than one system. We conclude that mouse monoclonal antibodies are also suitable for use in swine as a complement of polyclonal reagents.

Animals↗
PubMed1992

Comprehensive evaluation of acute immunological changes induced by cuprophane and polysulfone membranes in a patient on chronic hemodialysis.

We have investigated the acute changes in cytokine gene expression patterns and immune status in vivo and ex vivo in a patient on chronic hemodialysis with cuprophane membranes before and after two hemodialysis sessions with either cuprophane or polysulfone membranes. Results show that both dialyzer membranes have differential acute effects on the immune system and that the concomitant use of reverse-transcriptase-coupled polymerase chain reaction, solid-phase and radioimmunoassays, and flow-cytometric analysis may be useful in the longitudinal assessment of patients on chronic hemodialysis.

Biocompatible Materials↗
PubMed1992

Evaluation of an enzyme-linked immunosorbent assay for the diagnosis of Chagas' disease using synthetic peptides.

An enzyme-linked immunosorbent assay (ELISA) has been developed to detect antibodies in human sera to synthetic peptides derived from the repeating amino acid sequence in recombinant Trypanosoma cruzi antigens. Sixty serum samples from patients with chronic Chagas' disease were used to determine the reactivity against the synthetic repeat peptides derived from clones 1, 2, 30, 36, and shed acute phase antigen (SAPA). Ninety-eight percent of the samples had detectable antibodies to one or more of the synthetic peptides at titers greater than 1:100. The percentage of reactive sera increased from 28% with peptide SAPA to 93% with peptide 2. The exposure of patients to T. cruzi was reflected in indirect immunofluorescent antibody titers to fixed epimastigotes. Comparisons between ELISA and immunoradiometric assay data indicated that both tests were of approximately equal sensitivity.

Amino Acid Sequence↗
PubMed1992

Immunodetection of antibodies in sera from symptomatic and asymptomatic Chilean Chagas' disease patients with Trypanosoma cruzi recombinant antigens.

A panel of eight Trypanosoma cruzi antigens produced by recombinant DNA techniques was used to compare the reactivity of IgG specificities in the sera from 45 chronic Chagas' disease patients with different clinical symptoms (cardiac disease, gastrointestinal lesions, and combined syndrome) with those present in the sera from 55 asymptomatic patients in Chile. All of the serum samples were first characterized for antibody to T. cruzi epimastigotes by immunofluorescence assay. All of the Chagas' disease sera were reactive, but none of five healthy controls whose sera were also tested had antibodies against the fixed parasites. A dot-blot assay was then performed to evaluate the serum reactivity against recombinant DNA clones 1, 2, 13, 26, 30, 36, 54, and SAPA (shed acute phase antigen). These recombinant antigens were recognized by a large proportion of the sera collected from the Chilean patients. Ninety-five percent of the serum samples reacted with one or more of the recombinant clones. Analysis of the reactivity with individual fusion proteins showed that 88% of these sera reacted with clones 1 and 2, and 78% reacted with clone 13. Differences in reactivity to clones number 13, 30, and SAPA were observed when symptomatic and asymptomatic patients were compared. These differences in reactivity were statistically significant (P less than 0.01) according to Fisher's exact test.

Adolescent↗
PubMed1992

An improved polymerase chain reaction assay to detect Trypanosoma cruzi in blood.

Amplification by the polymerase chain reaction of Trypanosoma cruzi satellite DNA was used to enhance sensitivity in the detection of the parasite in blood, with the ultimate goal of improving diagnosis of the chronic phase of Chagas' disease. Two contiguous oligonucleotides were synthesized corresponding to the most conserved region of the 195-basepair repeated sequence and used as primers for the amplification reaction. Nineteen femtograms of parasite DNA that was amplified in the presence of 15 micrograms of human or mouse DNA produced a visible band upon electrophoresis in agarose gels and staining with ethidium bromide. In reconstitution experiments, one parasite in 10 ml of blood could be unambiguously determined when the DNA was isolated from nuclei after the blood was treated with NP40 and centrifuged. Polymerase chain reaction assays were carried out to detect T. cruzi in chronically infected mice. Most mice were parasite-positive when organs or tissues were tested, but all were negative when total blood was tested.

Animals↗
PubMed1991

Expression of HLA class I and II antigens in bronchogenic carcinomas: its relationship to cellular DNA content and clinical-pathological parameters.

We studied the presence of HLA class I antigens in 115 samples of bronchogenic carcinomas (66 frozen and 49 formalin-fixed and paraffin-embedded specimens) by the immunophosphatase alkaline and immunoperoxidase methods with antibodies against major histocompatibility complex antigens. We also studied HLA class II antigens on the 66 frozen tumor samples. Nonneoplastic lung tissue was also analyzed for purposes of comparison. Pneumocytes and epithelial respiratory cells expressed HLA class I and II antigens. The expression of class I antigens was totally lost in 29 tumors (25%). The defect in HLA gene expression affected both heavy chain and beta 2-microglobulin, as demonstrated by the null reactivity with specific antibodies. In 2 cases of 66 studied in cryostatic section, the selective loss of A locus was observed, and in three cases selective loss of B locus was detected. The expression of class I antigens was compared with clinical-pathological parameters such as histological type, degree of differentiation, and tumor stage, as well as tumoral ploidy. The absence of expression of HLA class I molecules was significantly associated with poorly differentiated and undifferentiated tumors (P less than 0.0001) and with aneuploid tumors (P less than 0.001), suggesting that some lung tumors may escape immune surveillance and become biologically more aggressive. Class II antigens were expressed in 13 cases of 66 studied (18%) in frozen specimens, and a clear relationship was observed with well-differentiated tumors (P less than 0.05).

Adenocarcinoma↗
PubMed1991

Characterization of early kidney lesions in estrogen-induced tumors in the Syrian hamster.

Syrian hamsters were treated with diethylstilbestrol (DES), a potent estrogen and kidney carcinogen, or ethinyl estradiol (EE), a strong estrogen but weak carcinogen, for 1-9 months. At monthly intervals their kidneys were studied using light, immunoperoxidase, and electron microscopic techniques. At 5 months, DES-treated animals exhibited interstitial lesions composed of small round cells with a high nuclear:cytoplasmic ratio. Immunoperoxidase and ultrastructural studies showed these cells to be similar to cells in fully formed tumors at 9 months. Early lesions in EE-treated animals (seen as early as 1 month) were dissimilar, these lesions appeared in the deep cortex adjacent to the renal pelvis, where proximal tubules underwent hyperplastic changes, showing columnar cells with large nuclei, occasional mitoses, and sloughing of apical cytoplasm. Cells in early lesions of EE-treated animals did not resemble the fully developed tumor in either immunoperoxidase or ultrastructural features; although with longer treatment these tubular lesions progressed to dysplasia (3-5 months) and severe dysplasia/carcinoma in situ (7 months), they did not form grossly visible tumors during the 9-month study. Both early lesions identified were specific, inasmuch as they were not observed in control animals and animals treated with beta-dienestrol and 17 alpha-estradiol (noncarcinogenic weak estrogens). Animals given a combination of DES and EE showed tubular hyperplasia but not interstitial lesions; this finding was of particular interest because hamsters given this combination of estrogens do not develop gross renal tumors. These results strongly implicate the primitive interstitial cell in the hamster kidney as the cell of origin of the DES-induced neoplasm.

Animals↗
PubMed1991

Comparative analysis of dopamine and tyrosine hydroxylase immunoreactivities in the brain of two amphibians, the anuran Rana ridibunda and the urodele Pleurodeles waltlii.

To gain more insight into the dopaminergic system of amphibians and the evolution of catecholaminergic systems in vertebrates in general, the distribution of dopamine and tyrosine hydroxylase immunoreactivity was studied in the brains of the anuran Rana ridibunda and the urodele Pleurodeles waltlii. In both species, dopamine-immunoreactive (DAi) cell bodies were observed in the olfactory bulb, the preoptic area, the suprachiasmatic nucleus, the nucleus of the periventricular organ and its accompanying cells, the nucleus of the posterior tubercle, the pretectal area, the midbrain tegmentum, around the solitary tract, in the ependymal and subependymal layers along the midline of the caudal rhombencephalon, and ventral to the central canal of the spinal cord. Tyrosine hydroxylase (TH) immunohistochemistry revealed a similar pattern, although some differences were noted. For example, with the TH antibodies, additional cell bodies were stained in the internal granular layer of the olfactory bulb and in the isthmal region, whereas the same antibodies failed to stain the liquor contacting cells in the nucleus of the periventricular organ. Both antisera revealed an almost identical distribution of fibers in the two amphibian species. Remarkable differences were observed in the forebrain. Whereas the nucleus accumbens in Rana contains the densest DAi plexus, in Pleurodeles the dopaminergic innervation of the striatum prevails. Moreover, cortical structures of the newt contain numerous DAi fibers, whereas the corresponding structures in the frog are devoid of immunoreactivity. The dopaminergic system in amphibians appears to share many features not only with other anamniotes but also with amniotes.

Animals↗