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Biomedical subjects

J Arias

Publications and source records attributed to J Arias.

At least 91 records · Page 5Linked to original sources
PubMed1994

Behavior of nucleolar organizer regions in the different hepatic lobes after end-to-side portacaval shunt in the rat.

Protein synthesis activity in the hepatic lobes in control and end-to-side portacaval shunt rats was studied by assaying one of the argyrophilic components (Ag-NOR) of the hepatocytic nucleolus. The differences found in the area and number of Ag-NOR for each nucleus and in the percentage of Ag-NOR area to nucleus area in each hepatic lobe in control rats as well as in the end-to-side portacaval shunt rats suggest that there are interlobular differences in the control rats related to this parameter that are indicative of protein synthesis and cell proliferation. Furthermore, the changes that occur in these parameters after the deprivation of portal flow produced by an end-to-side portacaval shunt make it possible to hypothesize on the existence of a hepatic lobular functional heterogeneity in the rat liver.

Animals↗
PubMed1994

Hemorrhagic gastroesophageal ulceration by pulmonary infection in extrahepatic cholestatic pigs.

We developed a biliary and pulmonary microbiologic study in 22 Large-White pigs that underwent bile-duct ligation in order to demonstrate that sepsis has a biliary and pulmonary origin which may be involved in the gatroesophageal pathology. All the pigs died at 18.2 +/- 8.9 days of the post-operative period. The cause of death was hemorrhagic ulceration of the gastroesophageal region in 36.3% (n = 8) of the animals that also presented multiple bilateral miliary lung abscesses. High infestation rates with intestinal germs were found in the bile and lung. In conclusion, the experimental model of extrahepatic cholestasis in the Large-White pig could be useful for the study of etiopathogenic mechanisms by which the pulmonary infection produces a hemorrhagic gastroesophageal ulceration considered as stress ulcer.

Animals↗
PubMed1993

A model of cholestasis in the rat, using a microsurgical technique.

An experimental model of extrahepatic cholestasis in the rat, using a microsurgical technique, is described. Sixteen days postoperatively all of the animals (n = 10) were alive and had hepatomegaly, splenomegaly, jaundice, and hyperbilirubinemia. The use of this technique prevents the development of hepatic cysts and other complications inherent in the surgical techniques of cholestasis, such as hepatopneumonic abscesses.

Animals↗
PubMed1992

Cytoprotective effect of somatostatin in a rat model of hepatic ischemic reperfusion.

To evaluate the possible cytoprotective effect of somatostatin in hepatic ischemic reperfusion injury we used 75 adult male Wistar rats randomly separated into four groups. The rats in group 1 underwent sham operations, and those in group 2 underwent resection of the median and left lateral lobes. The rats in group 3 underwent a 90-min period of ischemia of the right lateral lobe, which we induced by temporarily occluding the right portal vein and the hepatic artery. On restoration of flow to the right lateral lobe, the median and left lateral lobes (about 80% of total liver mass) were excised (and later assayed for thymidine kinase basal activity). The rats in group 4 were given the same treatment as group 3 rats except that a saline solution of somatostatin was infused at a rate of 2 micrograms/min starting at laparotomy and lasting 24 hr. The rats in groups 1, 2 and 3 were infused with saline. Rats in groups 2, 3 and 4 were randomly assigned to two subgroups; one of these subgroups was observed until spontaneous death, and rats in the other group were killed 24 hr after the procedure for obtaining peripheral blood and liver samples. Somatostatin infusion improved the animals' survival rates from 0% (group 3) to 60% (group 4) (p < 0.05) and decreased bilirubin levels (0.78 +/- 0.17 mg/dl, n = 15 [group 4] vs. 1.69 +/- 0.04 mg/dl, n = 15 [group 3]; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Further studies on the topography of the N-terminal region of human platelet glycoprotein IIIa. Localization of monoclonal antibody epitopes and the putative fibrinogen-binding sites.

The precise localization of the epitopes for six monoclonal antibodies specific for the N-terminal region of human platelet glycoprotein IIIa (GPIIIa) was determined. The epitope for P37, a monoclonal antibody that inhibits platelet aggregation, was found at GPIIIa 101-109, flanked by the epitopes for P23-3 (GPIIIa 16-28), P23-4 (GPIIIa 83-91), P23-5 (GPIIIa 67-73), P23-7 (GPIIIa 114-122) and P40 (GPIIIa 262-302), and very close to the early chymotryptic cleavage site of GPIIIa in whole platelets (Phe-100). When the amino acid sequence of GPIIIa was searched for peptide sequences hydropathically complementary to the fibrinogen gamma-chain C-terminal (gamma 400-411) and A alpha-chain RGD-containing peptides, none was found for the gamma 400-411, two (GPIIIa 128-132 and 380-384) were found complementary to fibrinogen A alpha 571-575 and two (GPIIIa 109-113 and 129-133) were found for A alpha 94-99. Two of these putative fibrinogen-binding sites overlap with each other, and a third one overlaps with the epitope for P37. These findings reinforce the earlier suggestion that the N-terminal region of GPIIIa is involved in fibrinogen binding, and suggest the existence in GPIIIa of either multiple or alternative RGD-binding sites or one RGD-binding domain with several moieties. Finally, early chymotryptic cleavage of GPIIIa in whole platelets liberates to the soluble fraction the peptide stretch Ser-101-Tyr-348, which carries the epitope for P37 and the putative binding sites for fibrinogen. The rest of the molecule, together with the GPIIb-resistant moiety, remains membrane-bound. This leads us to propose that the fibrinogen-binding domain of GPIIIa is not involved in the binding to GPIIb to form the Ca2(+)-dependent GPIIb-GPIIIa complex.

Amino Acid Sequence↗
PubMed1991

Further studies on the topography of human platelet glycoprotein IIb. Localization of monoclonal antibody epitopes and the putative glycoprotein IIa- and fibrinogen-binding regions.

Glycoprotein IIb (GPIIb) is a major glycoprotein of the human platelet plasma membrane, which together with glycoprotein IIIa (GPIIIa) forms a Ca2(+)-dependent heterodimer, GPIIb/IIIa, which serves as the major fibrinogen receptor in activated platelets. The precise localization of the epitopes for six anti-GPIIb monoclonal antibodies (M1-M6) has been determined by a combination of enzymic and chemical cleavage procedures, peptide isolation, N-terminal sequence analysis, peptide synthesis and enzyme immunoassay. The following localizations were found: M1, beta 1-16-36, beta 2-4-24; M2, alpha 747-755; M alpha 2, alpha 837-843; M3, alpha 849-857; M4, alpha 143-151; M5, alpha 550-558; M6, alpha 657-665. Besides considerations of the degree of exposure of these epitopes, several remarkable features are readily apparent. The earliest and main chymotryptic cleavage site of GPIIb in whole platelets is between alpha cysteine-545 and alpha phenylalanine-551. The epitope for M3 was located within the same sequence (alpha 842-857) as is the epitope for PMI-1 [Loftus, Plow, Frelinger, D'Souza, Dixon, Lacy, Sorge & Ginsberg (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 7114-7118] in spite of the fact that the exposure of the latter in whole platelets is EDTA-dependent whereas that in the former is not. The epitope for M5 shares full homology with the 540-548 peptide stretch of the alpha-subunit of the vitronectin receptor, and this antibody cross-reacts with endothelial cells. The M6 epitope is located in the 25 kDa membrane-bound fragment of GPIIb, which is most epitope is destroyed at an early stage of chymotrypic digestion. This suggests that this region of GPIIb, somewhere between the epitope for M5 (alpha 550-558) and the epitope for M2 (alpha 747-755), may carry the surface of interaction of GPIIb with GPIIIa in the GPIIb/IIIa heterodimer. Finally, the sequence where the epitope for M6 has been located (alpha 657-667) was the only one found to be hydropathically complementary to the gamma 402-411 peptide of fibrinogen within the amino acid sequence of both GPIIb and GPIIIa. This complementariness, the EDTA- or thrombin-dependence of the exposure of the alpha 657-665 stretch in whole platelets to M6 and the ability of this antibody to inhibit platelet aggregation led us to postulate that this peptide stretch is a putative binding site for fibrinogen in the platelet receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1991

Fluoroquinolones in the treatment of typhoid fever and the carrier state.

Typhoid fever remains an important public health problem throughout the world with a higher morbidity and mortality rate in the developing countries. Early establishment of the diagnosis and prompt initiation of treatment with chloramphenicol, ampicillin or trimethoprim-sulfamethoxazole is not necessarily followed by complete resolution of the infection. Between 1% and 6% of patients with typhoid fever become chronic biliary carriers of Salmonella typhi. These carriers are potential factors in the continued transmission of the disease. The increasing emergence worldwide of strains showing multiple resistance to the agents traditionally used in therapy has encouraged investigators to seek alternatives such as third generation cephalosporins and recently the new 4-quinolones, which have greater activity against Salmonella typhi including multi-resistant strains. The fluoroquinolones seem to be the treatment of choice in those regions where resistant strains of Salmonella typhi are prevalent.

4-Quinolones↗
PubMed1991

Preliminary experience with the Berger neurobiopsy device for ultrasound guided aspiration and biopsy of intracranial lesions.

Our preliminary experience is presented in the use of the Berger neurobiopsy device for ultrasound localization and biopsy of intracranial lesions through a burr hole. The apparatus and technique are described, along with the results of its use in the first 49 patients. In these patients 43 tumours were biopsied, all except one successfully. Three abscesses were aspirated, two intraventricular shunt catheters were sited and in one patient the diagnosis of postradiation gliosis was confirmed and tumour excluded. The advantages and limitations of the technique are discussed. It is advocated as a simple and time-saving alternative to CT stereotactic biopsy in many cases.

Adolescent↗
PubMed1990

Heterotopic auxiliary liver transplantation with portal flow. Gradual development of the collateral circulation.

One of the causes of auxiliary liver transplantation failure is the inter-liver competition between the host liver and the graft for the hepatotrophic factors of the portal blood. We have developed an experimental model of heterotopic partial (30%) liver isotransplant using Wistar rats so as to study this competition. Splenoportography and dissection demonstrate the existence of collateral circulation. The collaterals at 90 days post-transplant (PT) consisted of veins from the portal vein to the host liver (PR), paraesophageal veins (PE) and splenorenal veins (SR). At 60 days P.T., PR and SR veins but not PE ones appeared, and at 30 days P.T., there were only PR veins. Graft atrophy at 90 days P.T. was associated with a severe degree of bile duct proliferation. The gradual development of portal hypertension causes porto-systemic collateral circulation and the graft loses the portal hepatotrophic factors. The late development of the portal hypertension and the biliary proliferation could be caused by the hepatic arterial ischemia in this experimental model. Thus, as has been described in the orthotopic liver transplantation, the heterotopic one might require a double vascularization, both portal and arterial.

Animals↗
PubMed1990

[A clinical and biological study of 33 cases of polycythemia vera].

The clinical, analytical, evolutive and therapeutic aspects of 33 cases of polycythemia vera which were diagnosed according to the Polycythemia Vera Study Group criteria, are described. Mean age was 65 years with a slight predominance of females (54.5%). Hemorrhagic manifestations were the most frequent (67%) with a great number of patients with digestive manifestations consisting of GI hemorrhage, abdominal pain, portal or suprahepatic veins thrombosis. Splenomegaly was the most frequently found sign upon examination (73%). The mean hemoglobin leukocyte, and platelet levels were 18 g/dl, 16,000 mm3 and 738,000 mm3 respectively. It is note worthy the value of the erythropoietin for the differential diagnosis of secondary erythrocytosis as well as the value of the bone marrow histologic study which should be included in the diagnostic criteria of the disease. The evolution of the process is favorably altered by bleedings and chemotherapeutic cytoreduction which are often performed simultaneously.

Adult↗
PubMed1990

[Critical Care Surgery Unit in general and digestive system surgery].

In a 5-bed Critical Care Surgery Unit (UQCC) where surgeons are in charge of care, 126 patients admitted over 5 consecutive months were divided into 4 groups according to the treatment given: Group I (n = 49): elective gastrointestinal surgery; Group II (n = 52): emergency gastrointestinal surgery; Group III (n = 15): non-gastrointestinal surgery; Group IV (n = 10): medical treatment. The mean stay of all patients in the Surgical Critical Care Unit was 6 +/- 7.7 days and the global mortality was 7.9% (n = 10). The mean age of the patients who died was 71.5 +/- 7.3 years and 70% of the deaths corresponded to Group II. Forty percent of the patients who died had systemic candidiasis. Among the factors implicated in the mortality acute gastrointestinal pathology per se, the coexistence of chronic systemic disease and advanced age were prominent. We discuss the need for typifying the role of Surgical Critical Care Units in General and Gastrointestinal Surgery.

Adolescent↗