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Biomedical subjects

J R Garcia

Publications and source records attributed to J R Garcia.

At least 19 recordsLinked to original sources
PubMed2001

Macrophages transfer [14C]-labelled fatty acids to pancreatic islets in culture.

Macrophages are able to produce, export, and transfer fatty acids to lymphocytes in culture. The purpose of this study was to examine if labelled fatty acids could be transferred from macrophages to pancreatic islets in co-culture. We found that after 3 h of co-culture the transfer of fatty acids to pancreatic islets was: arachidonic >> oleic > linoleic = palmitic. Substantial amounts of the transferred fatty acids were found in the phospholipid fraction; 87.6% for arachidonic, 59.9% for oleic, 53.1% for palmitic, and 36.9% for linoleic acids. The remaining radioactivity was distributed among the other lipid fractions analysed (namely polar lipids, cholesterol, fatty acids, triacylglycerol and cholesterol ester), varying with the fatty acid used. For linoleic acid, a significant proportion (63.1%) was almost equally distributed in these lipid fractions. Also, it was observed that transfer of fatty acids from macrophages to pancreatic islets is time-dependent up to 24 h, being constant and linear with time for palmitic acid and remaining constant after 12 h for oleic acid. These results lead us to postulate that in addition to the serum, circulating monocytes may also be a source of fatty acids to pancreatic islets, mainly arachidonic acid.

Animals↗
PubMed2001

Corneal disease in patients with chronic renal insufficiency undergoing hemodialysis.

PURPOSE: To evaluate alterations of the corneal endothelium in patients undergoing hemodialysis for renal insufficiency. METHODS: Sixty-six patients undergoing hemodialysis received a complete ophthalmologic examination. The state of the endothelium was assessed using pachymetry and specular microscopy. The group of patients undergoing dialysis was divided according to the time of dialysis, aluminum, product of calcium and phosphate in blood, and parathyroid hormone to analyze the influence of these factors. The possible presence of iron and aluminum in the aqueous humor of patients who underwent and those who did not undergo hemodialysis was also estimated. RESULTS: Patients undergoing hemodialysis did not have significant corneal edema. Cell density was significantly lower in patients undergoing dialysis than in patients not undergoing dialysis; this reduction appeared to be associated with length of dialysis and was unrelated to serum aluminum and calcium levels. Patients undergoing dialysis did not have cell polymorphism or polymegethism, although there was a tendency toward increased polymegethism with length of dialysis. Aluminum and iron were not increased in the aqueous humor of patients undergoing dialysis. CONCLUSIONS: The alteration of the endothelium that we found is not related to the elements studied. It is possibly the result of another product dissolved in the anterior chamber or to the alterations of the anterior segment that these patients are known to have.

Adult↗
PubMed1995

Protein reverse staining: high-efficiency microanalysis of unmodified proteins detected on electrophoresis gels.

A methodology is presented for efficiently gaining structural information from electrophoresed proteins after on-gel detection by imidazole-sodium dodecyl sulfate-zinc reverse staining. As a consequence of reverse staining, (a) protein bands arise transparent against a deep white-stained background, limits of detection being in the femtomole range; (b) there is no loss of image when the gel is kept in distilled water (even during years); and (c) protein bands result immobilized, i.e., they do not diffuse upon gel storage. To recover reverse-stained proteins or fragments thereof from the gel, the immobilization of bands must first be abrogated by chelating the zinc ions from stain (protein mobilization). We had originally described mobilization at low pH by using citric acid. Here, we improve this procedure regarding the protein electrotransfer. We demonstrate that mobilization is efficiently done at neutral to alkaline pH by short-term (5 to 10 min) incubation of the gel in a buffer containing glycine or dithiothreitol prior to transfer. Moreover, mobilization was most simply performed by just adding the zinc chelating agent to the transfer buffer. Reverse staining and the new mobilization procedure made electrotransferring single protein bands from gel onto small-sized (13 x 5 mm2) PVDF membrane pieces in mini sandwich-like assemblies practical. Equipment is described for the protein electroblotting in such minisandwiches. Microsequence analysis of the electroblotted proteins showed initial yields in the range of those achieved when the transfer was done from unstained control gels. Protein bands kept in the reverse-stained gel for prolonged time periods (even for as long as 2 years) could be similarly analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophoresis, Polyacrylamide Gel↗
PubMed1995

Value of SPECT imaging of the thoracolumbar spine in cancer patients.

The purpose of this study was to evaluate the usefulness of SPECT bone imaging in targeting the precise location of vertebral abnormalities to ascertain whether such knowledge would help in differentiating between metastatic and benign lesions. SPECT images of the thoracolumbar spine in 50 patients were correlated with plain x-rays, CT, MRI, PET, and bone scans and 6-month clinical follow-ups. SPECT images revealed 110 lesions, 35 of which were metastases. Twenty-four of 25 lesions involving the vertebral body with extension into posterior elements were metastases, as well as 10 of 39 lesions found in the vertebral body and 1 of 4 found in the spinous process. All lesions limited to the anterior aspect of the vertebral body (13/13), facet joints (23/23), and intervertebral disk space (6/6) were benign. In conclusion, SPECT imaging of the thoracolumbar spine is helpful in determining the precise anatomic location of vertebral abnormalities, and knowledge of the location can be used to determine whether these abnormalities in cancer patients are benign entities or metastases.

Diagnostic Imaging↗
PubMed1994

The impact of HLA mismatches on the survival of first cadaveric kidney transplants.

BACKGROUND: The benefits of HLA-A, B, and DR matching of cadaveric kidney grafts and recipients remain controversial when viewed from the perspective of social equity and graft survival. METHODS: We estimated graft survival using proportional-hazards techniques, adjusting for patient and donor characteristics, for a series of 30,564 Medicare patients receiving a first cadaveric kidney transplant between 1984 and 1990. The effects of minimal achievable HLA mismatches and maximal matching on graft survival were estimated by simulated allocation of a sample of organs to a sample of 20,000 candidates for transplantation. RESULTS: The adjusted one-year graft survival was 84.3 percent for grafts with no mismatches and 77.0 percent for grafts with four mismatches. National rationing of donor organs to achieve minimal mismatching and maximal matching could potentially decrease the average number of HLA mismatches from 3.6 to 1.2, with a corresponding increase in the number of matches. As a consequence, projected five-year graft survival could potentially increase from 58.5 percent to 62.9 percent. This would be associated with a decrease in the proportion of kidneys allocated to black recipients from 22.2 to 15.0 percent. CONCLUSIONS: Under ideal circumstances, a policy of maximal matching of cadaveric renal transplants would increase five-year graft survival by a comparatively small 4.4 percentage points, but the actual benefit is likely to be smaller.

Adolescent↗
PubMed1994

Direct blotting, sequencing and immunodetection of proteins after five-minute staining of SDS and SDS-treated IEF gels with Nile red.

The non-covalent dye Nile red allows the fast and simple fluorescent staining of protein bands in sodium dodecyl sulfate (SDS)-polyacrylamide gels. This procedure has been extended to polyacrylamide isoelectric focusing gels that do not contain SDS. Unlike the current methods using Coomassie blue or silver for gel staining, Nile red staining does not preclude the direct electroblotting of protein bands onto polyvinylidene difluoride membranes, and the transferred proteins can be used directly for immunoblotting analysis and for N-terminal microsequencing.

Electrophoresis, Polyacrylamide Gel↗
PubMed1992

Isolation and identification of two neutral thyrotropin releasing hormone-like peptides, pyroglutamylphenylalanineproline amide and pyroglutamylglutamineproline amide, from human seminal fluid.

Two tripeptide amides with stuctures similar to thyrotropin releasing hormone were isolated from human seminal fluid and their amino acid sequences determined. The peptides were purified by gel exclusion from Sephadex G50 and were detected by radioimmunoassay with thyrotropin releasing hormone antibody; in addition, N-terminally extended forms were demonstrated by radioimmunoassay after trypsin digestion. Further purification of the tripeptides was by chromatography on SP-Sephadex C25 and by high performance liquid chromatography on C18 Microbondapak using an HCl/acetonitrile gradient. After exclusion from mini-columns of SP-Sephadex C25 and DEAE-Sephadex A25, two neutral peptides were obtained in homogeneous form by high performance liquid chromatography with an HCl/methanol gradient. Amino acid analysis gave the following compositions: Glu, 0.74, Phe, 1.0, Pro, 1.0; and Glu, 1.72, Pro, 1.0. Both peptides possessed a blocked N terminus, but after opening the pyroglutamyl ring the sequences Glu-Phe-Pro and Glu-Glx-Pro were demonstrated. The chromatographic properties of the endogenous peptides were identical to the properties of the corresponding synthetic peptides. The structure of pGlu-Phe-Pro (where p-indicates pyro-) amide was confirmed by fast atom bombardment mass spectrometry. The presence in human semen of three structurally related peptides, pGlu-Phe-Pro amide, pGlu-Gln-Pro amide, and the previously reported pGlu-Glu-Pro amide (Cockle, S. M., Aitken, A., Beg, F., and Smyth, D. G. (1989) J. Biol. Chem. 264, 7788-7791), suggests that this series of peptides may have evolved to fulfil complementary biological roles.

Amino Acid Sequence↗
PubMed1991

The impact of nonidentical ABO cadaveric renal transplantation on waiting times and graft survival.

Blood type O recipients of cadaveric renal transplants have longer pretransplant waiting periods than blood type A, B, and AB recipients. To evaluate reasons for and consequences of this discrepancy, we studied both the frequency of various donor and recipient blood type combinations and their outcomes. Among 37,659 cadaveric renal transplants performed during 1983 through 1989, there were 2,625 transplants (7%) received by patients of compatible but nonidentical blood types. Of 18,575 type O donor organs, 16,784 were received by type O patients for a recipient to donor ratio of 0.9. The corresponding ratios were greater than 1.0 for all other blood types (1.02 for blood type A, 1.14 for type B, and 2.18 for type AB). This causes blood type O patients to have a lower access to transplantation and to have significantly longer waiting times than patients of all other blood types. This inequality of access diminished significantly (P less than 0.001) over the years, but did not resolve by 1989. Analysis of relative risk for first graft loss by multiple regression (Cox) showed that transplantation across compatible blood types had a 9.1% higher risk (P less than 0.1) than that of transplantation among identical blood types. Cadaveric renal transplantation within identical blood types optimizes access to transplantation and avoids further aggravating past disadvantages for blood type O recipients.

ABO Blood-Group System↗
PubMed1989

Genetic analysis of muscle development in Drosophila melanogaster.

The different thoracic muscles of Drosophila are affected specifically in the mutants: stripe (sr), erect wing (ewg), vertical wings (vtw), and nonjumper (nj). We have tested the extent of this specificity by means of a genetic analysis of these loci, multiple mutant combinations, and gene dosage experiments. A quantitative, rather than a qualitative, specificity is found in the mutant phenotypes. All muscles are altered by mutations in any given gene, but the severity of these alterations is muscle specific. The locus stripe seems to have a polar organization where different allelic combinations show quantitative specificity in the muscle affected. In addition to the muscle phenotypes, neural alterations are detected in these mutants. The synergism found between ewg, vtw and ewg, sr as well as the dosage effect of the distal end of the X chromosome upon the expression of ewg and sr suggests the existence of functional relationships among the loci analyzed.

Alleles↗
PubMed1989

Prevalence of multiple sclerosis in Lanzarote (Canary Islands)

In the island of Lanzarote of the Province of Las Palmas, which is part of the Spanish archipelago of the Canary Islands, the prevalence of multiple sclerosis is 15 per 100,000. The prevalence of MS in Lanzarote seems related more to ethnic conditions than to geography.

Demography↗
PubMed1989

The role of pretransplant time and therapy on kidney graft survival.

1. The delay time between onset of ESRD and first cadaver kidney transplant varies considerably across patient subgroups. It is shortest for Whites and Asian Americans and longest for Blacks. Patients with blood type O and those highly sensitized have longer delays. 2. The effect of delay time on graft survival, while real and statistically significant, is quantitatively small. 3. Based on an analysis of a large national United States sample, CAPD therapy, compared to other forms of dialysis, does not have an adverse effect on 2-year graft survival.

Databases, Bibliographic↗
PubMed1980

S-adenosylmethionine levels and protein methylation during morphogenesis of Mucor racemosus.

The intracellular level of S-adenosylmethionine increased as the yeast-phase cells of Mucor racemosus were induced to convert to hyphae. This increase correlated well with time course of the conversion in cell type and was independent of the metabolic changes caused by the shift to aerobic conditions. There was no significant change in the intracellular level of spermidine, a polyamine synthesized from putrescine and the propylamine group of S-adenosylmethionine. Spermine was not detected. An examination of protein methylation revealed an increase in the methylation of total protein during the shift in cell type and possible qualitative as well as quantitative changes in specific base proteins.

Fungal Proteins↗