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Biomedical subjects

J Garrido

Publications and source records attributed to J Garrido.

At least 73 records · Page 4Linked to original sources
PubMed1985

Peroxisomal organization in normal and cerebrohepatorenal (Zellweger) syndrome fibroblasts.

The reported absence of morphologically detectable peroxisomes in liver and kidney tissue cells from patients affected by the autosomic recessive, inherited metabolic disease known as cerebrohepatorenal, or Zellweger, syndrome was studied in fibroblasts, assuming it to be a generalized defect. Normal cultured fibroblasts were shown to contain peroxisomes according to morphological, biochemical, and subcellular fractionation criteria: particle-bound catalase and fatty acyl-CoA oxidase copurify in subcellular fractionation by differential centrifugation or isopycnic equilibrium in continuous density gradients and peroxidase-positive organelles of approximately equal to 0.1 micron in diameter are detected in the cytoplasm. In Zellweger cultured fibroblasts, these peroxisomal enzymes are present; however, they behave as cytosolic enzymes in the different subcellular fractionation procedures employed and peroxisomes are not detected cytochemically. These findings support the hypothesis that the lack of peroxisomes in this genetic disease is the consequence of a defect in the assembly of the peroxisomal constituents. Furthermore, the value of fibroblasts for subcellular analysis of peroxisomal defects is illustrated.

Acetylglucosaminidase↗
PubMed1985

Anchorage of collagen-tailed acetylcholinesterase to the extracellular matrix is mediated by heparan sulfate proteoglycans.

Heparan sulfate and heparin, two sulfated glycosaminoglycans (GAGs), extracted collagen-tailed acetylcholinesterase (AChE) from the extracellular matrix (ECM) of the electric organ of Discopyge tschudii. The effect of heparan sulfate and heparin was abolished by protamine; other GAGs could not extract the esterase. The solubilization of the asymmetric AChE apparently occurs through the formation of a soluble AChE-GAG complex of 30S. Heparitinase treatment but not chondroitinase ABC treatment of the ECM released asymmetric AChE forms. This provides direct evidence for the vivo interaction between asymmetric AChE and heparan sulfate residues of the ECM. Biochemical analysis of the electric organ ECM showed that sulfated GAGs bound to proteoglycans account for 5% of the total basal lamina. Approximately 20% of the total GAGs were susceptible to heparitinase or nitrous acid oxidation which degrades specifically heparan sulfates, and approximately 80% were susceptible to digestion with chondroitinase ABC, which degrades chondroitin-4 and -6 sulfates and dermatan sulfate. Our experiments provide evidence that asymmetric AChE and carbohydrate components of proteoglycans are associated in the ECM; they also indicate that a heparan sulfate proteoglycan is involved in the anchorage of the collagen-tailed AChE to the synaptic basal lamina.

Acetylcholinesterase↗
PubMed1984

The electric organ of Discopyge tschudii: its innervated face and the biology of acetylcholinesterase.

An ultrastructural, histochemical, and biochemical study of the electric organ of the South American Torpedinid ray, Discopyge tschudii, was carried out. Fine structural cytochemical localization of acetylcholinesterase (AChE) indicated that most of the esterase was associated with the basal lamina. Electron microscopy indicated no marked differences in the electrocyte ultrastructure between Discopyge and Torpedo californica. Discopyge electric organ possessed three molecular forms, two asymmetric forms (16 S and 13 S) and one globular hydrophobic form (6.5 S). The asymmetric 16 S AChE form was solubilized by heparin, a sulfated glycosaminoglycan, suggesting that heparin-like macromolecules are involved in the binding of the enzyme to the basal lamina. Our results show that cell-free translated AChE peptides, synthesized using Discopyge electric organ poly(A+) RNA, correspond to a main band of 62,000 daltons which probably represents the catalytic subunit of the asymmetric AChE.

Acetylcholinesterase↗
PubMed1984

Gastric bezoars: treatment and prevention.

Gastric bezoars may occur in the normal stomach as a result of ingestion of various objects which do not pass through the pylorus. Most gastric bezoars occur as a complication of previous gastric surgery in which there is a loss of normal pyloric function, hypoperistalsis, and low gastric acidity. They may also occur as a complication of cimetidine therapy. Symptoms include epigastric fullness, regurgitation, nausea and vomiting, and epigastric pain. A simple treatment utilizing an ordinary Teledyne Water Pik jet stream through a gastroscope is described to break up a large phytobezoar. This method is probably the treatment of choice and should be used more widely.

Adult↗
PubMed1983

Effects of diterpene forskolin on the release reaction and protein phosphorylation of human platelets.

The effects of diterpene forskolin on the human platelet release reaction and on platelet protein phosphorylation were studied. This drug is shown to have the same effects as other agents which increase cAMP levels, namely, it inhibits the secretory response to diverse agonists and causes changes in the phosphorylation of several specific proteins. An increase of the 32P content is seen in the MW 47 000, 24 000 and 21 000 polypeptides while a decrease is observed in the MW 41 000 and 27 000 and 20 000 species. Forskolin also inhibits the changes in protein phosphorylation pattern induced by the powerful platelet secretagogue, thrombin. Our results relate the effects of antagonists of platelet secretion such as prostaglandins more closely to changes in cAMP levels and in protein phosphorylation than to other possible effects of the receptor-ligand interaction, which is by-passed by the use of forskolin. Our results also provide additional evidence involving these changes in the mechanisms which regulate the secretory process in platelets.

Blood Platelets↗
PubMed1983

RNA tumor virus production accompanies the transformed phenotype change induced by hydrocortisone hormone in rat glioma cells.

ST1, a hydrocortisone-hypersensitive variant of the C6 rat glioma cell line, produced viral particles upon treatment with this glucocorticoid hormone. The virus was identified as type C RNA tumor virus by: a) morphology; b) 3H-uridine labelling; c) banding in sucrose density gradient; d) reverse transcriptase activity. Hydrocortisone uniquely shut off ST1 cells' transformed phenotype and turned on viral particles production.

Animals↗
PubMed1982

Fibrillolysis and electrophoretic determination of actin and myosin in hypertrophied human myocardium.

Destructive myofibrillar lesions, particularly degenerative fibrillolysis in hypertrophied hearts, were studied with the electron microscope in left ventricular myocardium samples obtained from autopsies with post mortem periods not exceeding 195 min. The contractile protein composition of these samples was determined electrophoretically. 18 cases were studied, grouped as follows: Group I, composed of 5 cases showing normal hearts which were employed in the determination of normal electrophoretic values. Group II: 10 cases with hypertrophic hearts, 1 of them showing contraction bands and decreased myosin, 6 others with fibrillolytic lesions of which 3 presented a decrease in myosin and 3 possessed normal myosin values. None of the cases showed a decrease in actin values. Group III was composed of 3 cases of hearts with normal weights that showed ultrastructural alterations of the myofibrils: 1 with myofibrillar disarray and normal electrophoretic values, 1 with incomplete contraction bands and normal protein values and 1 with focal myofibrillar disgregation and myosin decrease. It is concluded that in some cases of degenerative fibrillolytic lessions a decrease of myosin occurs. The method employed does not rule out that apparently normal actin and myosin values might be due to the presence of contractile proteins in a denatured state that does not affect their electrophoretic mobility.

Actins↗
PubMed1981

Epidermal growth factor inhibits cytoskeleton-related changes in the surface of parietal cells.

The effect of epidermal growth factor (EGF) on gastric acid secretion was correlated with the morphological changes of the apical pole of rat parietal cells studied by transmission electron microscopy. Gastric acid secretion was stimulated by histamine, carbachol, pentagastrin, and insulin-induced hypoglycemia, and estimated by continuous recording of pH variations of gastric luminal perfusate. EGF inhibits acid secretion in these conditions. The action of the hormone also results in the arrest or reversal of the changes in shape undergone by parietal cells as they go into secretion. In view of the evidence involving cytoskeletal elements in the generation of these structural alterations, our observations suggest that the action of EGF on gastric acid secretion may be a consequence of a general effect of this hormone on cytoskeletal function.

Animals↗
PubMed1979

Muscle proteins and the changes in shape of avian oxynticopeptic cells in relation to secretion.

A combined ultrastructural and biochemical study of the avian oxynticopeptic cell was performed. Scanning electron microscopy demonstrates that this cell undergoes great changes in the shape of its apical pole in relation to secretory activity. These changes are confirmed by transmission electron microscopy and by freeze-fracture images. The biochemical finding of actin- and myosin-like proteins in high-speed supernatants of homogenates of these cells as well as the ultrastructural and cytochemical localization of actin-like filaments in their apical poles suggest a possible participation of these proteins in the above-mentioned changes. Thus, the study of cytoplasmic matrix elements and of their organization may be highly relevant in the search for a correlation between structure and function in these cells.

Actins↗
PubMed1979

Comparative cytology of hydrochloric acid secreting cells.

A comparative study of the oxyntic cells of the stomach of Vertebrates is presented. A system of membranous tubules which is apparently inter-convertible with the luminal plasma membrane is described as an important structural feature in all classes. In all Vertebrates with the sole exception of Mammals, this system shares a common cell with the structures involved in the secretion of zymogen. In Mammals it becomes segregated into a specialized cell type, the parietal cell, characterized in addition by the presence of a long tortuous intracellular canaliculus, which serves as its secretory pole. The hypothesis is presented and discussed that the parietal cell is capable of achieving a higher efficiency in hydrochloric acid secretion by the existence of the intracellular canaliculus which makes the immediate surroundings of the secretory pole independent of the contents of the gastic lumen. In Birds (whose gastric glands do not possess parietal cells) a corresponding effect can be achieved only by complex structures such as the compound gastric glands. An explanation is hereby offered for the unique features of the Avian stomach.

Amphibians↗
PubMed1976

Actin-like filaments amd membrane rearrangement in oxyntic cells.

The secretory pole of vertebrate oxyntic cells possesses two distinct membrane systems: the apical plasma membrane which presents numerous infoldings, microvilli and processes, and a complex tubulovesicular system located in close proximity to the plasma membrane. These two membrane systems are generally believed to be interconvertible in relation to the functional state of the cell. To determine the role that filaments may play in the interconversion process, the secretory pole of rat and toad oxyntic cells was examined by electron microscopy under conditions designed to demonstrate filamentous structures, i.e., slight cellular swelling and incubation with heavy meromyosin. Filaments 50-80 A in diameter are present in close association with the plasma membrane to which they are connected by regularly spaced bridges. Heavy meroxyosin-treated material reveals "decorated" filaments in topographically corresponding locations. No filaments are seen in association with membranes of the tubulovesicular system. These findings suggest that association with actin-like filaments is a step in the translocation of membranes from the tubulovesicular system to the plasma membrane.

Actins↗