PubMed Health⌕ Search

Biomedical subjects

J Vargas

Publications and source records attributed to J Vargas.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Usefulness of Helicobacter pylori antigen detection in stools in the diagnosis of infection and confirming eradication after treatment].

BACKGROUND: A new immunoassay to detect H. pylori antigen in stool (HpSA) has been developed. We started this study to know the sensitivity and specificity of this test as diagnostic tool of H. pylori infection and eradication control. PATIENTS AND METHODS: Forty patients were recruited to study H. pylori infection. At endoscopy, biopsy samples were taken for culture, histology and urease test. Stool specimens were tested by HpSA and serum sample for serology. Patients were defined as H. pylori positive if histology, urease test or culture were positive. Forty-two patients treated with omeprazole based triple therapy were screened 8 weeks after treatment for eradication control using urea breath test, HpSa and serology. Patients with UBT negative were defined as eradicated. RESULTS: As diagnostic tool: 34 out of 40 patients were infected (85%). HpSA was positive in 31 out of 34 patients, and achieve 3 false negative and 1 false positive (sensitivity: 91%, specificity: 84%). IgG anti-H. pylori was positive in 31 out of 34 infected patients, with 3 false positive and 3 false negative (sensitivity 91%, specificity 50%). In eradication control (n = 42), HpSA was negative in 33/38 successfully eradicated patients, and positive in all four non-eradicated patients. Five patients eradicated showed positive HpSA (specificity 87%, positive predictive value: 87%, negative predictive value: 100%). IgG serology was negative in only a third of eradicated patients. CONCLUSIONS: The stool assay was an accurate tool for diagnosis of H. pylori infection and eradication control.

Adult↗
PubMed2000

Native extracellular matrix induces a well-organized bipolar outgrowth pattern with neurite extension and retraction in cultured neurons.

Cultured anterior pagoda (AP) neurons from the leech develop characteristic outgrowth patterns that depend on the molecular composition of the substrate. This article analyzes how native substrates from the central nervous system (CNS), such as the extracellular matrix (ECM) inside the capsules that enwrap the ganglia, determine the outgrowth patterns of AP neurons. When plated on the internal side of ganglion capsules, the remaining primary portion (stump) of AP neurons sprouted two main branches in opposite directions with bifurcations. This T-shaped pattern was distinctive for AP neurons and was different from the patterns of the same cell type plated on the external side of the capsule or on leech laminin extracts, in which they generated multiple neurites and branching points. AP neurons plated on tritonized CNS homogenates reproduced the outgrowth pattern displayed on ganglion capsules, in terms of the number of primary neurites, their length, their orientation, and the number of branch points. The development of the T-shaped outgrowth pattern of AP neurons on ganglion capsules and CNS homogenates started by the sprouting of one branch that later bifurcated, followed by a second branch in the opposite direction after a lag of several hours. Extension of the second branch and retraction of secondary neurites of the first were synchronous and contributed to refine the T-shaped pattern. These results suggest that during development or regeneration of the CNS, particular sets of ECM proteins have multiple effects regulating the number, direction, extension, and retraction of neurites.

Animals↗
PubMed2000

Displacement currents associated with the insertion of Alzheimer disease amyloid beta-peptide into planar bilayer membranes.

The role of endogenous amyloid beta-peptides as causal factors of neurodegenerative diseases is largely unknown. We have previously reported that interactions between Alzheimer's disease A beta P[1-40] peptide in solution and planar bilayer membranes made from anionic phospholipids lead to the formation of cation-selective channels. We now find and report here that the spontaneous insertion of free A beta P[1-40] across the bilayer can be detected as an increase in bilayer capacity. To this end we recorded the displacement currents across planar bilayers (50 mM KCl on both sides) in response to sudden displacements of the membrane potential, from -300 to 300 mV in 20-mV increments. To monitor the A beta P[1-40]-specific displacement currents, we added A beta P[1-40] (1-5 microM) to the solution on either side of the membrane and noted that the direction of the displacement current depended on the side with A beta P[1-40]. The size of the A beta P[1-40]-specific charge displaced during a pulse was always equal to the charge returning to the original configuration after the pulse, suggesting that the dipole molecules are confined to the membrane. As a rule, the steady-state distribution of the A beta P[1-40]-specific charges within the bilayer could be fit by a Boltzmann distribution. The potential at which the charges were found to be equally distributed (V(o)) were approximately -135 mV (peptide added to the solution in the compartment electrically connected to earth) and 135 mV (peptide added to the solution connected to the input of the amplifier). The A beta P[1-40]-specific transfer of charge reached a maximum value (Q(max)) when the electrical potential of the side containing the amyloid beta-protein was taken to either -300 or 300 mV. For a circular membrane of 25-microm radius ( approximately 2000 microm(2)), the total A beta P[1-40]-specific charge Q(max) was estimated as 55 fC, corresponding to some 170 e.c./microm(2). Regardless of the side selected for the addition of A beta P[1-40], at V(o) the charge displaced underwent an e-fold change for a approximately 27-mV change in potential. The effective valence (a) of the A beta P[1-40] dipole (i.e., the actual valence Z multiplied by the fraction of the electric field chi acting on the dipole) varied from 1 to 2 electronic charges. We also tested, with negative results, the amyloid peptide with the reverse sequence (A beta P[40-1]). These data demonstrate that A beta P[1-40] molecules can span the low dielectric domain of the bilayer, exposing charged residues (D(1), E(3), R(5), H(6), D(7), E(11), H(13), and H(14)) to the electric field. Thus the A beta P[1-40] molecules in solution must spontaneously acquire suitable conformations (beta-pleated sheet) allowing specific interactions with charged phospholipids. Interestingly, the domain from residues 676 to 704 in the APP(751) is homologous with the consensus sequence for lipid binding found in other membrane proteins regulated by anionic phospholipids.

Amyloid beta-Peptides↗
PubMed2000

A role for SSeCKS, a major protein kinase C substrate with tumour suppressor activity, in cytoskeletal architecture, formation of migratory processes, and cell migration during embryogenesis.

SSeCKS is a major protein kinase C substrate which has tumour suppressor activity in models of src- and ras-induced oncogenic transformation. The mitogenic regulatory activity of SSeCKS is likely manifested by its ability to bind key signalling proteins such as protein kinases C and A and calmodulin, and to control actin-based cytoskeletal architecture. Rat SSeCKS shares extensive homology with human Gravin, an autoantigen in myasthenia gravis that encodes kinase scaffolding functions and whose expression pattern in fibroblasts and nerves suggests a role in cell motility. Here, we analyse the expression of SSeCKS and Gravin in rodent and human fibroblast and epithelial cell lines using antibodies specific or crossreactive for SSeCKS or Gravin. SSeCKS expression was then analysed in developing mouse embryos and in adult tissues. In the foetal mouse, early SSeCKS protein expression (E10-11) is focused in the loose mesenchyme, luminal surface of the neural tube, notochord, early heart and pericardium, urogenital ridge, and dorsal and ventral sections of limb buds. In later stages (E12-14), SSeCKS is widely expressed in mesenchymal cells but is absent in the spinal ganglia. By E15, SSeCKS expression is ubiquitous, although the staining pattern varies from being striated within smooth muscle sarcomeres to filamentous in mesenchymal and select epithelial cells. In the adult mouse, SSeCKS staining is relatively ubiquitous, with highest expression in the gonads, smooth and cardiac muscle, lung, brain and heart. High expression is also detected in fibroblasts and nerve fibres as well as in more specialized cells such as glomerular mesangial cells and testicular Sertoli cells. SSeCKS expression in the rat testes correlates with the induction of puberty, and in mature mouse spermatozoa, SSeCKS is found in peripheral acrosome membranes and in a helix-like winding pattern within the midsection. Periodic enrichments of SSeCKS are found in sperm midsections and in developing axons, suggesting a role in architectural infrastructure. As with Gravin, high SSeCKS expression is absent in most epithelial cells; however, in contrast to Gravin, SSeCKS is expressed in Purkinje cells, cardiac muscle, macrophages and hepatic stellate cells, indicating overlapping yet distinct patterns of tissue expression in the SSeCKS/Gravin family. The data suggest roles for SSeCKS in the control of cytoskeletal and tissue architecture, formation of migratory processes and cell migration during embryogenesis.

A Kinase Anchor Proteins↗
PubMed2000

Evaluation of the use of botulinum toxin in children with achalasia.

BACKGROUND: Achalasia is rare in children. Recently, injection of botulinum toxin into the lower esophageal sphincter has been studied as an alternative to esophageal pneumatic dilatation or surgical myotomy as treatment for achalasia. In the current study, the effects of botulinum toxin were investigated in the largest known series of children with achalasia. METHODS: Treatment for achalasia was assessed in 23 pediatric patients who received botulinum toxin from June 1995 through November 1998. Those who continued to receive botulinum toxin and did not subsequently undergo pneumatic dilatation or surgery were considered repeat responders. Results were compared with those of published studies evaluating the use of botulinum toxin in adults with achalasia. RESULTS: Nineteen patients initially responded to botulinum toxin. Mean duration of effect was 4.2 months +/- 4.0 (SD). At the end of the study period, three were repeat responders, three experienced dysphagia but did not receive pneumatic dilatation or surgery, three underwent pneumatic dilatation, eight underwent surgery, three underwent pneumatic dilatation with subsequent surgery, and three awaited surgery. Meta-analysis shows that, in the current study group, the data point expressing time of follow-up evaluation versus percentage of patients needing one injection session without additional procedures (botulinum toxin injection, pneumatic dilatation, or surgery) falls within the curve for those in studies on adult patients receiving botulinum toxin for achalasia. CONCLUSIONS: Botulinum toxin effectively initiates the resolution of symptoms associated with achalasia in children. However, one half of patients are expected to need an additional procedure approximately 7 months after one injection session. The authors recommend that botulinum toxin be used only for children with achalasia who are poor candidates for either pneumatic dilatation or surgery.

Adolescent↗
PubMed2000

Intravenous eradication therapy for bleeding gastroduodenal ulcer associated with Helicobacter pylori infection.

OBJECTIVE: To evaluate the efficacy of an ultrashort intravenous triple therapy against Helicobacter pylori infection in patients with bleeding peptic ulcer. METHODS: Thirty patients with bleeding peptic ulcer were studied prospectively. At endoscopy, two corpus and antrum biopsies were obtained for urease testing and culture. If H. pylori infection was found (positive urease test), the patient was treated with omeprazole 40 mg bid, metronidazole 500 mg tid and ampicillin 2000 mg fid for three days and then with ranitidine 150 mg bid for 2 months until eradication. In all patients a [13C]urea breath test was done at 2-month intervals, and in patients with gastric ulcer an endoscopy was also done and biopsies for culture and urease testing were obtained. RESULTS: Eradication efficacy (intention-to-treat) was 86.6% (26 out of 30). All schedules were administered in full and no patient had any adverse reactions. No patients had rebleeding. CONCLUSIONS: Ultrashort three-day triple therapy can achieve an eradication rate greater than 80%, with good acceptance and compliance, and without adverse events.

Adult↗
PubMed2000

[Incidence of genitourinary infection caused by Chlamydia trachomatis in a STD center calculated by direct antigen detection].

OBJECTIVE: Chlamydia trachomatis is one of the most common sexually transmitted agents which causes a wide spectrum of diseases including urethritis in men and endocervicitis in women. We analyzed patients with genitourinary C. trachomatis infections evaluating risk factors and the association with other sexually transmitted infections. MATERIAL AND METHODS: We processed 1,180 specimens from 913 patients (772 women and 141 men), attended at a Sexually Transmitted Diseases (STD) Center. The diagnostic of C. trachomatis infection was made by an enzyme-linked fluorescent immunoassay, Vidas Chlamydia test (bioMérieux). RESULTS: The incidence of C. trachomatis infection was 4.8% (57 cases) and was higher in women (70.1%) than in men (29.8%). The risk groups observed were: 26 prostitute, 7 contact with prostitute or risk partner, 5 homosexual, 5 promiscuous heterosexual and 14 without risk groups. Associated with this infection we observed other: 10 bacterial vaginosis, 8 Papillomavirus infection, 3 Trichomonas vaginalis infections, 2 Neisseria gonorrhoeae infections and 2 Candidiasis. The 53.4% of these patients didn't have any symptomatology at the consult moment. CONCLUSIONS: The control of patients with risk factors is important for the diagnostic of C. trachomatis and other sexually transmitted infections, because most of them were prostitutes and asymptomatic. Within men, homosexuality, contact with prostitute or risk partner were the practices with higher risk.

Antigens, Bacterial↗
PubMed2000

[Intraoperative awakening: report of a case in pediatric surgery].

Intraoperatory awakening or awareness can be defined as recovering of conscience during general anesthesia. We report such a case happened in a 11 year-old boy during a hypospadias repair. After anesthetic education he related intraoperatory conscience without pain, anxiety, displeasing symptoms or long-term psychoconductal distress. We remark fisiopathology, diagnostic and preventive aspects of this rare event in pediatric surgery.

Anesthesia, General↗
PubMed1999

[Aortic periprosthetic abscess with extension to both atria].

The periprosthetic abscess due to infective endocarditis constitutes a severe complication of an aortic valve replacement, causing high mortality, despite combined medical and surgical treatment, especially in "early" endocarditis. Transthoracic echocardiography, and especially transesophageal study, is the election procedure for a non invasive diagnosis of vegetation and local complications. We report the aggressive and fulminant case of a 43 year old woman with aortic periprosthetic abscess and the extension to both auricles, due to Staphylococcus epidermidis.

Abscess↗
PubMed1999

Detection of loss of heterozygosity at RAD51, RAD52, RAD54 and BRCA1 and BRCA2 loci in breast cancer: pathological correlations.

Loss of heterozygosity (LOH) in loci of the 15q15.1, 12p13, 1p32, 17q21 and 13q12-13 regions may collaborate in the inactivation of RAD51, RAD52, RAD54, BRCA1, BRCA2 and possibly other genes implicated in the repair of double-stranded DNA and in DNA recombination. We investigate allelic losses in microsatellites of the RAD51, RAD52, RAD54, BRCA1 and BRCA2 regions, and their correlations with nine pathologic parameters in 127 breast carcinomas. The LOH analysis was performed by amplifying DNA by PCR, using 15 markers of the 15q15.1, 12p13.3, 1p32, 17q21 and 13q12-13 regions. LOH was found in the RAD51 region in 32% of tumours, in the RAD52 region in 16%, in RAD54 in 20% and in the BRCA1 and BRCA2 regions in 49% and 44% respectively. Significant correlations between one or more regions with concomitant LOH and pathologic parameters were observed with respect to age (P = 0.008), oestrogen receptor content (P = 0.03), progesterone receptors (P = 0.003), higher grade (P = 0.001), more advanced stage (P = 0.004) and peritumoural vessel involvement (P < 0.0001). The number of cases in which LOH was observed simultaneously in two or more regions was always higher than expected on the basis of their statistical probability, and curiously, the three patients with LOH at five regions concomitantly were under the age of 30 years. These results suggest that LOH at these regions could be related to breast cancer, and probably to a poor tumour prognosis.

Age Factors↗
PubMed1999

Involvement of the protein kinase C substrate, SSeCKS, in the actin-based stellate morphology of mesangial cells.

Activation of protein kinase C is a key signal transduction event in mesangial cell dedifferentiation and proliferation, yet little is known about downstream substrates or their roles in normal or diseased glomeruli. SSeCKS, a novel protein kinase C substrate originally isolated as a src-suppressed negative mitogenic regulator in fibroblasts, controls actin-based cytoskeletal architecture and scaffolds key signaling kinases such as protein kinase C and protein kinase A. Based on the morphologic similarity between SSeCKS-overexpressing fibroblasts and stellate mesangial cells, we hypothesized that SSeCKS might play a role in mesangial cell morphology in a protein kinase C-dependent manner. Immunoblotting, in situ staining and northern blotting detected abundant expression of SSeCKS in human and rodent mesangial cells and glomerular parietal cells but not in renal tubular epithelia. Immunofluorescence analysis showed enrichment of SSeCKS in mesangial cell podosomes and along a cytoskeletal network distinct from F-actin. Activation of protein kinase C by phorbol ester resulted in a rapid serine phosphorylation of SSeCKS and its subsequent translocation to perinuclear sites, coincident with the retraction of stellate processes. These effects were blocked by concentrations of bis-indolylmaleimide that selectively inhibit protein kinase C. Finally, ablation of SSeCKS expression using retroviral anti-sense vectors induced (1) an elongated, fibroblastic cell morphology, (2) production of thick, longitudinal stress fibers and (3) repositioning of vinculin-associated focal complexes away from the cell edges. These data suggest a role for SSeCKS as a downstream mediator of protein kinase C-controlled, actin-based mesangial cell cytoskeletal architecture.

A Kinase Anchor Proteins↗
PubMed1999

Response to 45 degrees head-down tilt as measured by organ weight/body weight ratios and spiral computed tomography.

BACKGROUND: Exposure to microgravity or simulated microgravity causes significant shifts in body fluids which may initiate physiological adaptations to the microgravity stressor. It is imperative to understand the physiological adaptations to microgravity in order to develop appropriate countermeasures to the deleterious aspects (i.e., muscle and bone wasting) of long-term spaceflights. HYPOTHESIS: The significant shifts in body fluids by 45 degrees head-down tilt can be measured by changes in organ weight/body weight (OW/BW) ratios and non-invasively by spiral computed tomography. METHODS: In a previous study (14), rats were weighed and exposed to either 45 degrees head-down tilt (45HDT) or a prone control position for one of the following experimental times: 0.5 h, 1 h, 2 h, 4 h, 8 h, or 24 h. A radioactive tracer was injected intramuscularly immediately prior to the start of the experimental time periods. At the end of the experiment, the major organs were harvested, weighed, and measured for gamma radiation levels. We used the organ weights from this previous study to calculate OW/BW ratios for the present study. Additionally, in the present study, rats in the 14-d experimental groups were weighed, lightly anesthetized to facilitate placement in the 45HDT position, and placed in a specially designed 45HDT cage (45HDT group) or left unrestrained in the cages (control group). At the end of the 14-d experimental time period, the rats were anesthetized and their lung densities measured with spiral computed tomography. RESULTS: The OW/BW ratios for the liver, kidneys, and spleen of 24 h 45HDT rats were significantly lower (p<0.05) than control values while at 1 h the 45HDT rats had a higher kidney OW/BW ratio. Lung density from the 14-d 45HDT rats was 24.4% greater than control rats' values. CONCLUSIONS: The physiological change due to the 45HDT position to simulate microgravity begins as early as 1 h, and the kidney appears to be the first organ affected. Spiral computed tomography may offer a viable method of non-invasively measuring organ densities in the 45HDT model. The OW/BW data generated in the present study does not correlate with the changes in radioactive tracer distribution data from our previous study.

Adaptation, Physiological↗
PubMed1998

[Influence of pregnancy in chronic hepatitis C virus infection].

BACKGROUND: There is scarce information about the influence of pregnancy in patients with chronic hepatitis C virus infection is little know. PATIENTS AND METHODS: 6,556 pregnant women were screened for anti-HCV (ELISA II). We determine ALT, HCV-RNA by PCR (Amplicor Roche) and HCV viraemia (Amplicor-HCV-Monitor Roche) in the third trimester of pregnancy and after 6 months of delivery. HBsAg, anti-HIV and HCV serotype (Murex 1-3) were also determined. STATISTICAL ANALYSIS: Fisher test, paired-t and U Mann Whitney. RESULTS: Anti-HCV was positive in 59 out of 6,556 (0.9%). Mean (SD) age: 27 (9) years (range, 18-40). Drug users: 34 (57%), post-transfusion: 10 (18%) and unknown: 15 (25%). HIV positive 11 (19%). Serotype 1, 30 (51%), setotype 3, 7 (20%), and nontypeable, 22 (37%). We studied HCV-RNA before and after delivery in 35 women, 8 out of 35 (23%) had HCV-RNA negative in both analysis. ALT was normal in 88% of women during pregnancy and in 42% after delivery. ALT levels in pregnancy were 32.6 (39.5) and in postpartum 64.5 (53.4) U/l (p < 0.005). 6 women were RNA-VHC negative during pregnancy and positive in postpartum. HCV viraemia during pregnancy and postpartum was 503 (1,203) and 1,014 (1,907) thousand copies/ml (p < 0.05). No relation was found among ALT or HCV viraemia with risk factors, serotype or coinfection with HIV. CONCLUSIONS: The prevalence of anti-HCV in pregnant women is 0.9%. ALT is usually normal in pregnancy. A quarter of women were HCV-RNA negative in pregnancy and positive after delivery. The viraemia was lower in pregnancy than after delivery, which is consistent with the fact of the low mother-to-infant HCV transmission rate.

Adolescent↗
PubMed1998

De novo hepatitis C in children after liver transplantation.

BACKGROUND: We describe the incidence, results of interferon therapy, and outcome of hepatitis C virus (HCV) hepatitis occurring de novo after pediatric orthotopic liver transplantation (OLT). METHODS AND RESULTS: Of children undergoing OLT between 1984 and September 1996, 321 children survived for more than 1 year. Of these, 13 (4.0%) developed previously undiagnosed HCV disease, as suggested by HCV antibody testing and HCV polymerase chain reaction and confirmed by liver biopsy. Of the 117 children who received transplants before HCV screening of blood products or donors, 10.2% developed de novo HCV disease. The mean age at diagnosis of HCV hepatitis was 13.2+/-5.0 years, and the mean time to diagnosis after OLT was 8.1 years (range, 4-11 years). The mean alanine aminotransferase (ALT) level at diagnosis was 108 IU/ml, and the liver biopsy specimen showed chronic active or chronic persistent hepatitis in 11 children, cirrhosis in 1 child, and nonspecific changes in 1 child. Twelve children were treated with interferon-2alpha; children who weighed > or =20 kg received 3 x 10(6) units every other day, and those who weighed <20 kg received 1.5 x 10(6) units every other day. Four patients developed rapidly progressive liver failure while receiving interferon therapy and required urgent re-transplantation. Three of the four children again developed histologic evidence of recurrent HCV 4-6 months after the second OLT, and all three subsequently died of HCV-induced liver failure. One patient remains alive and well with no evidence of HCV recurrence and a negative HCV RNA. Of the remaining eight children treated with interferon, only two have had a sustained response (normal ALT) and one is now HCV RNA negative. HCV RNA levels did not correlate with outcome or disease severity. HCV antibody levels were unreliable, with two patients having negative HCV antibody but a positive HCV RNA at diagnosis. Six patients were able to be genotyped: four were la and two were 1b. CONCLUSION: Overall mortality for de novo HCV hepatitis was 23%. Seventy-five percent of children who received a second transplant for HCV hepatitis had early histologic recurrence that led to liver failure and death. Interferon therapy resulted in a sustained improvement in ALT in only 15% of children. The time to onset and progression of clinical disease both in the original graft and the retransplant graft were accelerated compared with nonimmunosuppressed individuals.

Adolescent↗