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Biomedical subjects

B Gonzalez

Publications and source records attributed to B Gonzalez.

72 records · Page 4Linked to original sources
PubMed1987

Acquired loss of red cell Kell antigens.

A 19-year-old patient with a long history of idiopathic thrombocytopenic purpura developed a potent antibody against a high-incidence antigen in the Kell blood group system. The direct antiglobulin test on his red cells was negative. His cells exhibited profound depression of Kell blood group antigens, but antigens of other blood groups were normal. Transfusion of incompatible blood was well tolerated and differential agglutination tests, using selected Rh antisera, showed in vivo survival of the transfused red cells for more than 8 weeks. However, the transfused red cells also showed acquired loss of Kell antigens. Five months after the initial findings, Kell-related antibody disappeared and Kell antigens reappeared on his red cells. The patient's serum stored from the initial investigation now reacted with his freshly collected red cells. These data suggest that an environmental agent in the patient's plasma was responsible for the temporary loss of Kell antigens from red cells in his circulation.

Adult↗
PubMed1987

Actin synthesis in cultured cardiac myocytes: comparative effects of doxorubicin, dactinomycin, and plicamycin.

Cultured neonatal rat myocardial cells (CMC) were incubated with 10(-8) to 10(-5) mol/L doxorubicin (ADR), dactinomycin (ACT), and plicamycin (MIT), respectively, in medium containing 35 mu Ci sulfur 35-labeled methionine to determine comparative effects on myocardial contractile protein synthesis. Cells were harvested in 2 mmol/L Tris buffer with 0.1% Triton X-100, homogenized, and fractionated by centrifugation. Aliquots of the extracts containing equivalent amounts of protein were applied to 8% to 15% gradient sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Similar aliquots were subjected to isoelectric focusing and to gel electrophoresis in the second dimension. All electrophoretic gels were autoradiographed. A concentration-dependent effect of ADR, ACT, and MIT on protein and on actin synthesis was found in cultured myocytes with decreased density of radiolabeled actin band in CMC exposed to either 10(-5) mol/L ADR, or from 10(-8) to 10(-5) mol/L ACT, or from 10(-7) to 10(-5) mol/L MIT. Autoradiographs of two-dimensional gels focused actin isoforms but showed substantial decreases of all actin isoforms in CMC extracts from 10(-7) mol/L ACT. ACT and MIT each decreased CMC protein synthesis by 20% at 10(-8) mol/L. At 10(-6) mol/L ADR, synthesis of alpha-actin was diminished preferentially compared with beta and gamma. Synthesis of all actin isoforms was diminished at 10(-5) mol/L ADR. The effect of MIT and ACT on CMC actin and protein synthesis in heart cells is not as specific as the effect of ADR on CMC actin and protein synthesis.

Actins↗
PubMed1987

Actin isoform synthesis by cultured cardiac myocytes. Effects of doxorubicin.

Cultured neonatal rat myocardial cells (CMC) were incubated with 10(-10) M to 10(-5) M doxorubicin (adriamycin, ADR) and [35S]methionine to determine incorporation of radiolabeled methionine into myocardial contractile proteins. Cells were harvested after 24 hours homogenized, and subjected to centrifugation. Equivalent amounts of extracted protein were applied to 8 to 15% gradient sodium dodecylsulfate polyacrylamide gel electrophoresis. Similar aliquots were subjected to isoelectric focusing and to 2-dimensional gel electrophoresis. Electrophoretic gels were autoradiographed. Polypeptide bands on sodium dodecylsulfate polyacrylamide gel electrophoresis and autoradiograms were quantitated densitometrically. No effect of ADR on CMC actin or protein synthesis was seen from 10(-10) M to 10(-7) M ADR. ADR decreased protein synthesis in CMC by 31% at 10(-6) M and by 59% at 10(-5) M ADR. Autoradiograms of two-dimensional gels showed decreased radiolabeling of alpha-actin at 10(-6) M ADR compared to beta and gamma. Decreased CMC actin synthesis initiated at 10(-6) M ADR resulted in selective decrease in synthesis of the alpha-isoform. This in vitro observation may relate to poor contractility in ADR heart muscle disease.

Actins↗
PubMed1986

Cardiac actin interactions with doxorubicin in vitro.

Purified bovine cardiac G-actin was interacted with doxorubicin (Adriamycin, ADR), in absence of potassium or magnesium to study ADR's effects on actin polymerization. Actin with ADR (10(-6) M) was incubated with polylysine-coated polystyrene beads and filaments formed were visualized by negative staining electron microscopy (NSEM). ADR-induced actin polymerization was assessed biochemically by ultracentrifugation and analysis of protein content of the supernatant solution. Kinetic assays of turbidity of actin were performed which showed that ADR induced formation of stubby actin polymers which bound to the beads and differed ultrastructurally from the longer actin filaments induced by KCl + MgCl2. Actin content in the supernatant solution decreased after centrifugation (0.8 mg/ml in G-actin to 0.45 mg/ml in actin incubated with 10(-4) M ADR). ADR (10(-4) M) caused increased turbidity of actin of similar magnitude to that induced by actin + KCl + MgCl2. Data support the hypothesis that ADR induces polymerization of cardiac actin in vitro but this polymerization has characteristics which are different from actin polymerization induced by salts.

Actin Cytoskeleton↗
PubMed1986

Comparative growth of natural bacterial isolates on various lignin-related compounds.

Bacterial strains were isolated on the basis of their ability to proliferate in a minimal medium containing one of a series of lignin-related compounds as the sole carbon and energy source. These included the aromatic monomers guaiacol, vanillic and coumaric acids, a dimer and a trimer possessing the arylglycerol-beta-aryl ether linkage, anisoin, and both the ether-soluble and -insoluble fractions of kraft lignin. The growth of the strains on each of these compounds was measured. The results showed that the metabolic properties of the strains varied according to the structure of the carbon sources used for their selection. Spectrophotometric tracings of the culture medium during the log phase of growth of one of the strains on the beta-O-4 dimer revealed decomposition with the release of guaiacol.

Journal Article↗
PubMed1986

Anthracycline effects on actin and actin-containing thin filaments in cultured neonatal rat myocardial cells.

Adriamycin (ADR, Doxorubicin) effects on actin and other proteins in cultured neonatal rat cardiac myocytes were investigated. Heart cells were exposed to ADR in doses of 10(-8) M to 10(-5) M for 24 hours. Cells were harvested in 2 mM of Tris buffer containing Triton X-100, homogenized and centrifuged in a microfuge. Parallel dishes of cultured cardiac myocytes were washed in buffered saline and were fixed at 4 degrees C in Karnovsky's fixative. The supernatant solutions were dialyzed and then incubated with pancreatic DNAase I to quantify actin by enzyme inhibition. In parallel studies, both cell supernatant solutions and pellets were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis and the stained polypeptide bands were quantified by densitometry. Results showed that heart cells exposed to 10(-6) M of ADR for 24 hours had unpolymerized actin levels reduced to 7.7 micrograms/10(6) cells (as measured by DNAase I inhibition or by sodium dodecyl sulfate polyacrylamide gel electrophoresis along with densitometry) compared to 11.0 micrograms/10(6) cells in untreated culture heart cells. When ADR concentration was 10(-7) or 10(-8) M, unpolymerized actin levels were similar to the levels of untreated heart cells. Protein content of extract solutions of untreated and ADR-treated myocytes were 1.2 mg/ml and 0.8 mg/ml, respectively. Gel densitometry of electrophoretograms showed actin to account for 12 to 16% of total density of bands on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Comparative densitometry of ADR-treated cells treated with 10(-6) M of ADR show depolymerized actin to account for 77% of total actin. Ultrastructural results show a large clear cytoplasmic zone of disorganized 12 to 14-nm filaments in cultured myocytes exposed to 10(-6) M ADR. Little change in myocyte ultrastructure was seen at 10(-7) M or 10(-8) M ADR exposure. Data support ADR as a cellular disruptor with toxic effects on cardiac cytoplasmic and contractile proteins and filaments. This ADR effect on heart cells in culture is dose-related.

Actins↗
PubMed1984

Electron microscopy mapping of Escherichia coli RNA polymerase-binding sites on plasmids from thermophilic bacteria.

The binding sites of Escherichia coli RNA polymerase to plasmid DNA from extremely thermophilic bacteria have been mapped by electron microscopy. Templates used in these studies included plasmids pTF62 (from Thermus flavus AT62) and pTT8 (from T. thermophilus HB8) and also hybrid molecules constructed by ligation of these plasmids to pBR322. Although the affinity of the enzyme for heterologous DNA was about one-third of that for pBR322, it was possible to localize preferred binding sites on pTF62 and pTT8. Six binding sites were identified in pTT8, mapping close to 7, 28, 47, 61, 65, and 81 map units (one unit being equal to 1% of the length of the DNA). Seven such regions located at 3, 27, 48, 60, 67, 81, and 86 map units were found in pTF62. RNA polymerase binding sites found in pBR322 coincided with promoters identified previously by electron microscopy analysis of transcriptional complexes prepared in vitro. These data indicate that E. coli RNA polymerase binds preferentially to specific sequences in plasmids from thermophilic bacteria, suggesting possible promoter locations in these plasmids.

Base Sequence↗
PubMed1983

Purification and characterization of a calmodulin-dependent kinase from rat brain cytosol able to phosphorylate tubulin and microtubule-associated proteins.

Tubulin is a major substrate for endogenous Ca2+-calmodulin-dependent phosphorylation in synaptic cytoplasm. The present study details the purification to apparent homogeneity and characterization of a brain cytosolic Ca2+-calmodulin-dependent kinase which phosphorylates tubulin and microtubule-associated proteins as major substrates. The cytosolic kinase system, purified by sequential chromatography on phosphocellulose resin, calmodulin-affinity resin, and Fractogel TSK HW-55, chromatographs as a homogeneous complex of approximately 600,000 Da on Sephacryl S-300. This calmodulin-dependent kinase possesses a group of properties which specifically characterize this enzyme system: 1) the enzyme contains two calmodulin-binding doublets, rho and sigma, of approximately 52,000 and 63,000 Da, respectively; 2) both the rho and the sigma subunits demonstrate isoelectric points between 6.7 and 7.2; 3) both the rho and sigma subunits demonstrate autophosphorylation; 4) both the rho and sigma subunits show significant homologies as assessed by tryptic peptide fingerprints; 5) in the absence of substrate, both the rho and sigma subunits manifest lower mobility autophosphorylated species; 6) the kinase phosphorylates beta-tubulin equally on threonine and serine residues. Substrate specificity, kinetic parameters, calmodulin-binding properties, subunit composition, and subunit isoelectric points clearly differentiate this enzyme from other previously reported calmodulin-dependent kinases.

Animals↗
PubMedDate not supplied

The Chilean version of the Childhood Health Assessment Questionnaire (CHAQ) and the Child Health Questionnaire (CHQ).

We report herein the results of the cross-cultural adaptation and validation into the Chilean language of the parent's version of two health related quality of life instruments. The Childhood Health Assessment Questionnaire (CHAQ) is a disease specific health instrument that measures functional ability in daily living activities in children with juvenile idiopathic arthritis (JIA). The Child Health Questionnaire (CHQ) is a generic health instrument designed to capture the physical and psychosocial well-being of children independently from the underlying disease. The Chilean CHAQ-CHQ were derived from the European Spanish version with changing of the few words whose use is different in the 2 countries. A total of 126 subjects were enrolled: 72 patients with JIA (29% systemic onset, 39% polyarticular onset, 4% extended oligoarticular subtype, and 28% persistent oligoarticular subtype) and 54 healthy children. The CHAQ clinically discriminated between healthy subjects and JIA patients, with the JIA patients having a higher degree of disability, pain, and a lower overall well-being when compared to their healthy peers. Also the CHQ clinically discriminated between healthy subjects and JIA patients, with the JIA patients having a lower physical and psychosocial well-being when compared to their healthy peers. In conclusion the Chilean version of the CHAQ-CHQ is a reliable, and valid tool for the functional, physical and psychosocial assessment of children with JIA.

Adolescent↗
PubMedDate not supplied

Altered cytoskeletal protein synthesis in rat cardiac isografts.

Adult rats underwent surgical placement of heterotopic cardiac isografts. From 14 to 60 days postoperatively, native heart and transplanted heart protein synthesis was determined. Right ventricle and left ventricle free walls from native and transplanted hearts were dissected, minced into cubes, and incubated in medium containing sulfur-35 methionine. Tissue was harvested, washed, and homogenized in buffer and fractionated centrifugally. Specific radioactivity of polypeptides from transplant isograft right and left ventricle fractions were 6.36 +/- 5.1 and 4.93 +/- 3.6 (mean +/- SD, x 10(-6) cpm/mg protein), respectively. In contrast, native isograft right and left ventricle specific radioactivity was 1.71 +/- 1.49 and 1.07 +/- 0.88 (mean +/- SD, x 10(-6) cpm/mg protein), respectively. Autoradiograms of two-dimensional electrophoretograms revealed increased radiodensity of resolved polypeptides from transplanted and native hearts, which comigrated with nonsarcomeric (beta, gamma) actins. Skeletin and tubulin were prominent on one-and two-dimensional autoradiograms from 14 to 60 days. Radiolabeling of alpha actin polypeptide maximized at 14 days and was found to decrease at 30 and 60 days in comparison with nonsarcomeric actin isoforms. Correlative myocardial microscopic sections showed no fiber hypertrophy, but fiber atrophy was found. Results suggest a relative increase in polypeptide synthesis in the heterotopic transplanted heart samples.

Abdomen↗
PubMedDate not supplied

Polypeptide composition and histopathologic changes in endomyocardial biopsies from transplanted human hearts.

Sequential postoperative samples of 43 human right ventricular endomyocardial biopsies from four heart transplant patients were evaluated histopathologically to assess microscopic parameters of rejection. Selected pieces of these myocardial biopsies were weighed and homogenized in low ionic strength buffer containing Triton X-100 to extract and to quantitate cardiac actin. Aliquots of the soluble fractions were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Residual pellets were solubilized and also underwent SDS-PAGE. Electrophoretograms were analyzed densitometrically. Actin from biopsies from transplanted human hearts accounted for approximately 40% of Triton X-100 soluble polypeptides. Actin and myosin heavy chain content in the pellet fractions was unchanged as a function of allograft duration. A polypeptide band resolved between 14,000 and 21,000 daltons in the Triton-soluble fraction of four fresh samples correlated with histopathologic changes of moderate acute allograft rejection. A similar band was noted in 11 frozen endomyocardial biopsy specimens without changes of acute rejection. Small actin differences may be found in the transplanted heart, but they do not correlate with rejection. The presence on SDS-PAGE of the polypeptide band found between 14,000 and 21,000 daltons may correlate with proteolysis of cytoplasmic proteins either from rejection or possibly from autolysis after freezing.

Actinin↗