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Biomedical subjects

G Garcia

Publications and source records attributed to G Garcia.

At least 55 records · Page 3Linked to original sources

Jejunostomy: techniques, indications, and complications.

Jejunostomy is a surgical procedure by which a tube is situated in the lumen of the proximal jejunum, primarily to administer nutrition. There are many techniques used for jejunostomy: longitudinal Witzel, transverse Witzel, open gastrojejunostomy, needle catheter technique, percutaneous endoscopy, and laparoscopy. The principal indication for a jejunostomy is as an additional procedure during major surgery of the upper digestive tract, where irrespective of the pathology or surgical procedures of the esophagus, stomach, duodenum, pancreas, liver, and biliary tracts, nutrition can be infused at the level of the jejunum. It is also used in laparotomy patients in whom a complicated postoperatory recovery is expected, those with a prolonged fasting period, those in a hypercatabolic state, or those who will subsequently need chemotherapy or radiotherapy. As a sole procedure it is advised for neurologic and congenital illnesses, in geriatric patients who pose difficult care demands, and for patients with tumors of the head and neck. The complications seen with jejunostomy can be mechanical, infectious, gastrointestinal, or metabolic. The rate of technical complications of the Witzel longitudinal technique is 2.1%, for the transverse Witzel up to 6.6%, for the Roux-en-Y 21%, for open gastrojejunostomy from 2%, and for the needle catheter technique from 1.5% with 0.14% mortality. The percutaneous endoscopic procedures have as much as a 12% complication rate; no figures exist for laparoscopy. The complications are moderate and severe: tube dislocation, obstruction or migration of the tube, cutaneous or intraabdominal abscesses, enterocutaneous fistulas, pneumatosis, occlusion, and intestinal ischemia. The infectious complications are aspiration pneumonia and contamination of the diet. The gastrointestinal complications are diarrhea 2.3% to 6.8%, abdominal distension, colic, constipation, nausea, and vomiting. The metabolic complications are hyperglycemia 29%, hypokalemia 50%, water and electrolyte imbalance, hypophosphatemia, and hypomagnesemia. These complications are secondary to inadequate selection of nutrition relative to the characteristics of the patient, to inadequate management of the mixture, and to deficient clinical care. The ideal jejunostomy technique depends on the material resources but more importantly on the experience of the surgeon. The benefits of jejunostomy justify the risks.

Aged↗

Environmental tobacco smoke interference in the assessment of the health impact of a municipal waste incinerator on children through urinary thioether assay.

The urinary elimination of thioethers urinary thioethers (UT) was studied in 83 schoolchildren living in two different areas of the city of Mataró, with special attention paid to the influence of a waste incinerator and of the smoking habits of their parents. The mean UT values were 8.79+/-3.23 and 7.52+/-3.23 mmol/mol creatinine in the area close to the incinerator (A1) and in the area far away from it (A2) respectively (statistically n.s.). Children exposed to environmental tobacco smoke (ETS) at home presented increased levels of UT (8.60+/-3.11 vs 5.93+/-3.22 mmol/mol creatinine; P=0.002). Considering the two exposures together (waste incinerator and ETS), no differences were found between the two areas studied (A1 and A2) in non-exposed (ETS) children, whereas slight differences were found when comparing highest ETS exposed children from the two areas (10. 18+/-2.70 vs 8.00+/-3.42 mmol/mol creatinine; P=0.04). Exposure to ETS could affect health more than pollutants from a waste incinerator and may interfere with non-selective assays such as urinary thioethers.

Air Pollutants↗

Does Asian race affect hepatitis B virus recurrence or survival following liver transplantation for hepatitis B cirrhosis?

To assess whether Asian race is an independent variable affecting survival and hepatitis B virus (HBV) recurrence after liver transplantation, the results of 27 consecutive liver transplants performed between June 1994 and April 1997 for HBV cirrhosis were analysed. In the group of 13 Asians, 38% had associated hepatocellular carcinoma and 62% had positive hepatitis B virus early antigen (HBeAg) or elevated HBV-DNA before transplant. Prophylactic hepatitis B immunoglobulin (HBIG) was administered perioperatively and long term at 4-6 weekly interval. Four patients with elevated HBV-DNA received lamivudine before transplantation. The 3 year actuarial patient survival rate was 100% in both Asian and non-Asian patients. Twenty-six patients remained seronegative for hepatitis B virus surface antigen after transplantation. The incidence of post-transplant HBV recurrence was similar: 0% in Asians compared with 7% in non-Asians. There was no recurrence in the group of 12 patients who were HBV-DNA or HBeAg negative pretransplant.

Adolescent↗

Resection versus transplantation for hepatocellular carcinoma.

Hepatocellular carcinoma is responsible for more than 1 million deaths per year worldwide and thus remains a challenging medical problem. It causes few or no symptoms and the tumour frequently reaches an enormous size by the time of diagnosis in countries where screening is seldom used. It is generally resistant to commercially available anti-neoplastic agents and radiation therapy. The principal treatment continues to be resection, either partial or complete, with liver transplantation. However, less than one-third of patients are surgical candidates for either resection or transplantation at the time of clinical presentation. This review will address the results observed following resection or transplantation for hepatocellular carcinoma.

Carcinoma, Hepatocellular↗

Intoxication by non-protein nitrogen compounds in rat feed.

Last year our white rats (Wistar origin) showed acute behavioral and physiological changes followed by death in 70% of the animals. We detected that the malfunctions could be attributed to the new batch of laboratory rat pellets provided two weeks before. High levels of urea (260 mg/kg) and ammonia (540 mg/kg) were found in the feed while usual values in other similar feed were 48 mg/kg and 82 mg/kg respectively. Suspecting an ammonia intoxication, concentrations of ammonia and urea were determined in blood, brain and liver. Brain neurotransmitters and blood tryptophan and serotonine (5-HT) were also determined. Blood ammonia in rats fed the contaminated feed was about 100% higher than those fed the normal feed while liver and brain ammonia were three and four fold high respectively. Liver and brain urea were four to five fold and about 100% higher in the exposed group than in the group fed the control diet respectively. Blood 5-HT increased 62.33% in females and 99% in males whereas brain 5-HT increased 83.13% in females and 70.47% in males. But, we detected a 59.8% decrease in brain dopamine levels in females and a 38.65% decrease in males. Liver histology showed small droplets of fat stores mainly in centrolobular hepatocyte. No differences in blood or liver cholesterol concentrations were observed whereas liver triacylglycerides were significantly higher in intoxicated females. This study illustrates a problem of food borne intoxication that justifies the need for exhaustive analyses of even not usual compounds in every feed batch; moreover, it is demonstrated that rat behavior appears to be the earliest biomarker of ammonia exposure.

Ammonia↗

Allograft rejection after liver transplantation for autoimmune liver diseases.

Autoimmune liver diseases (AILD) may progress to liver failure, requiring liver transplantation as definitive therapy, and these immune-mediated disorders may predispose the patient to more frequent graft rejection. The objective of this study was to determine the effect of preexisting AILD on the incidence of allograft rejection after liver transplantation. Sixty-three patients who underwent liver transplantation between March 1988 and December 1994 for AILDs that included autoimmune hepatitis (AIH; n = 33) and primary biliary cirrhosis (PBC; n = 30) were retrospectively compared with 47 patients who underwent liver transplantation for alcoholic cirrhosis during the same time period. There was a lower incidence of acute allograft rejection in patients with AILD who received tacrolimus-based compared with cyclosporine-based immunosuppression (50% v 85.5%; P = .02). However, patients with AILDs overall had a higher incidence of acute rejection than patients with alcoholic cirrhosis (81% v 46.8%; P < .001), regardless of the type of immunosuppression. In addition, steroid-resistant rejection occurred more frequently in patients with AILDs than in patients with alcoholic cirrhosis (38.1% v 12.8%; P = .003). There was also a trend toward a higher incidence of chronic rejection in patients with AILDs compared with patients with alcoholic cirrhosis (11.1% v 2.1%), but this difference did not reach statistical significance. Patient and graft survivals at 1 and 3 years were similar between patients with AILDs and alcoholic liver disease. Compared with alcoholic cirrhosis, preexisting AILDs are associated with a higher incidence of acute allograft rejection and a trend toward more frequent chronic rejection.

Adult↗

Clinical significance of serum and urine prolactin levels in lupus glomerulonephritis.

UNLABELLED: Prolactin (PRL) has been involved in the pathogenesis of systemic lupus erythematosus (SLE) and hyperprolactinemia has been connected with systemic activity. However, the clinical significance of PRL has not been investigated in lupus glomerulonephritis (GN). METHODS: We studied SLE patients (ACR criteria) with biopsy-proven renal disease. Renal histology was classified according to World Health Organization (WHO) criteria. Renal function tests, albuminuria, complement levels (nephelometry), anti-DNA antibodies (C. luciliae) and serum and urine PRL concentrations (RIA) were determined at baseline and at 4-month intervals for one year. Renal activity was defined as mild, moderate or severe according to serum creatinine, creatinine clearance, albuminuria, red blood cells (RBC), and casts. RESULTS: There were 26 patients with mean age 28.5 y and mean disease duration 47.9 months. Twenty patients had diffuse proliferative glomerulonephritis (GN), four had focal GN and two had membranous GN with proliferative changes. Renal activity was mild in ten patients, moderate in ten and severe in six. Mean serum (24.7+/-5.3) and urine (0.90+/-0.36) PRL levels were higher in patients with severe renal activity (P < 0.05 compared with mild group). PRL levels decreased after treatment, but this trend was not uniform during the follow-up period. CONCLUSION: Hyperprolactinemia was prevalent in SLE patients and high levels of PRL in the serum and urine could be related to severe renal disease.

Adolescent↗

Liver transplantation at Stanford University Medical Center.

Because of the unique demographics of our patient population, we have had the opportunity to dedicate further studies of the management of hepatitis B and hepatitis C. We have experienced a very low HBV recurrence rate with the use of HBIG in patients transplanted for hepatitis B. Investigations, including the use of new antiviral agents, and the development of approaches to minimize or abrogate disease recurrence such as lower levels of immunosuppression are ongoing. Using a standardized approach to the proper evaluation and selection of patients for liver transplantation with alcoholic liver disease or other liver diseases with coexistent alcohol abuse, we report favorable long-term results in these patients. We have reviewed our results and our approach to the management of EBV and posttransplant lymphoproliferative disorder. There is a firm commitment in our laboratories and outpatient clinics to the investigation of disease prevention, reliable detection and screening methods, and treatment modalities for EBV-related disease. We have addressed specific technical considerations to pediatric liver transplant and have discussed unique aspects of postoperative management in these patients. One-third of the transplants performed at Stanford are in children, 42% of whom are less than one year old. Results with our pediatric transplant recipients compare favorably with those of our adult recipients with patient and graft survival rates approaching 90% at one year and exceeding 80% at 46 months for both groups. As a response to the limited organ supply, we have extended our criteria for suitable donors. Most notably, we have utilized older donors and grafts with significant microsteatosis and have observed good results with these grafts as long as ischemia time is minimized. We have also successfully used reduced size grafts for our pediatric patients with good results and are continuing to expand the use of living-related partial grafts and split allografts.

Adolescent↗

A diiodo-substituted 9-anthracenone.

The central ring of the anthrone system in 1,8-diiodo-10-hydroxy-10-(3-methylbut-3-en-1-ynyl)anthrac en-9(10H)-one, C19H12I2O2, has a boat conformation and the two outer rings form a dihedral angle of 41.1 (2) degrees. The I-C bond lengths are 2.094 (4) and 2.083 (4) A. The hydroxyl and carbonyl groups form an intermolecular hydrogen bond having an O...O distance of 2.853 (4) A.

Anthracenes↗

Early activation defects in T lymphocytes from aged mice.

Aging affects both calcium signals and protein kinase cascades in mouse T lymphocytes. The decline in calcium signal development largely represents differences between naive and memory T cells; the latter are resistant to increases in calcium concentration, and are more common in aged mice. Aging leads to declines in phosphorylation of a wide range of substrates in T cells stimulated by either anti-CD3 antibodies or by substances, such as phorbol myristate acetate (PMA) or ionomycin, that act at intracellular sites, but some phosphoproteins respond only in old T cells, and others respond regardless of age. Tyrosine phosphorylation of the CD3 zeta chain declines with age, both in resting T cells and after activation, but the proportion of Zap-70 that is bound to CD3 zeta increases in T cells from old mice. Zap-70 function and phosphorylation of CD3 zeta-associated Zap-70 change only slightly after stimulation of T cells by anti-CD3 and anti-CD4, and are at similar levels in activated old and young T cells. Nonetheless, induction of Raf-1, MEK, and ERK kinase activity declines with age in CD4 T cells. The effect of aging on T-cell activation is not simply an overall decline in signal intensity, but a set of qualitative changes that differ among subsets and depend at least partly on the nature of the stimulus.

Adaptor Proteins, Signal Transducing↗

Recognition of synthetic oligopeptides from nonstructural proteins NS1 and NS3 of dengue-4 virus by sera from dengue virus-infected children.

The nonstructural proteins NS1 and NS3 from dengue virus are involved in the immune response during natural infection in humans. To analyze the immunogeneity of some epitopes present in NS1 and NS3 proteins from dengue virus type-4, six oligopeptides were synthesized; five from NS1 (NS1.1, NS1.2, NS1.3, NS1.4, and NS1.5) and one from NS3 (NS3.1). Peptides NS1.1, NS1.2, NS1.3, NS1.5, and NS3.1 were recognized by sera from dengue virus-infected children, suggesting that they represent exposed epitopes during natural dengue virus infection.

Adolescent↗

Characterization of SR 121463A, a highly potent and selective, orally active vasopressin V2 receptor antagonist.

SR 121463A, a potent and selective, orally active, nonpeptide vasopressin V2 receptor antagonist, has been characterized in several in vitro and in vivo models. This compound displayed highly competitive and selective affinity for V2 receptors in rat, bovine and human kidney (0.6 < or = Ki [nM] < or = 4.1). In this latter preparation, SR 121463A potently antagonized arginine vasopressin (AVP)-stimulated adenylyl cyclase activity (Ki = 0.26+/-0.04 nM) without any intrinsic agonistic effect. In autoradiographic experiments performed in rat kidney sections, SR 121463A displaced [3H]AVP labeling especially in the medullo-papillary region and confirmed that it is a suitable tool for mapping V2 receptors. In comparison, the nonpeptide V2 antagonist, OPC-31260, showed much lower affinity for animal and human renal V2 receptors and lower efficacy to inhibit vasopressin-stimulated adenylyl cyclase (Ki in the 10 nanomolar range). Moreover, OPC-31260 exhibited a poor V2 selectivity profile and can be considered as a V2/V1a ligand. In normally hydrated conscious rats, SR 121463A induced powerful aquaresis after intravenous (0.003-0.3 mg/kg) or oral (0.03-10 mg/kg) administration. The effect was dose-dependent and lasted about 6 hours at the dose of 3 mg/kg p.o. OPC-31260 had a similar aquaretic profile but with markedly lower oral efficacy. The action of SR 121463A was purely aquaretic with no changes in urine Na+ and K+ excretions unlike that of known diuretic agents such as furosemide or hydrochlorothiazide. In addition, no antidiuretic properties have been detected with SR 121463A in vasopressin-deficient Brattleboro rats. Thus, SR 121463A is the most potent and selective, orally active V2 antagonist yet described and could be a powerful tool for exploring V2 receptors and the therapeutical usefulness of V2 blocker aquaretic agents in water-retaining diseases.

Adenylyl Cyclases↗

Cloning of rat 92-kDa type IV collagenase and expression of an active recombinant catalytic domain.

A full-length cDNA for rat 92-kDa type IV collagenase was isolated and sequenced. RNase protection assay revealed tissue specific differential expression of the 92-kDa type IV collagenase in the rat during development. Natural and modified forms of the 92-kDa type IV collagenase were expressed. One active protein, 92-CD, contained only the putative catalytic domain. Large quantities of the 92-CD were expressed in Escherichia coli, extracted from inclusion bodies, purified, and refolded to an active form. This recombinant protein was able to cleave denatured and native collagen and was inactivated by known MMP inhibitors.

Amino Acid Sequence↗

A filter elution assay for the simultaneous detection of DNA double and single strand breaks.

This paper reports a gravity-flow filter elution assay that permits the simultaneous detection of DNA double strand breaks (DSBs, as neutral elutable DNA) and DNA single strand breaks (SSBs, as alkaline elutable DNA). This assay is based on a modification of a conventional gravity-flow alkaline elution procedure. The elution fraction resulting from cell lysis before the application of the alkaline elution buffer provides an estimate of DNA DSBs, while the fraction eluted by the alkaline buffer (pH 12.3) measures the extent of DNA SSBs. Data show that, in addition to its good detection sensitivity for SSBs, this method provides a sensitive measure of DNA DSBs. As an illustration of its specificity, this method unambiguously distinguished DNA SSBs induced by X-irradiation of mouse leukemia L1210 cells from DNA DSBs occurring in cells undergoing nucleosomal DNA fragmentation and apoptosis. The neutral elution fraction is a good predictor of loss of cell viability induced either by selenite at pharmacological levels or by growth factor depletion. The filter elution method reported is more specific and informative than a nick translation assay for the detection of DNA strand breaks.

Animals↗