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Biomedical subjects

J Vargas

Publications and source records attributed to J Vargas.

At least 55 records · Page 3Linked to original sources
PubMed1998

Long-term results of pediatric liver transplantation: an analysis of 569 transplants.

OBJECTIVE: To analyze a single center's 13-year experience with 569 pediatric orthotopic liver transplants for end-stage liver disease. SUMMARY BACKGROUND DATA: Despite advances in medical therapy, liver replacement continues to be the only definitive mode of therapy for children with end-stage liver disease. Innovative surgical techniques and improved immunosuppression have broadened the application of liver replacement for affected children. However, liver transplantation in the child remains challenging because of the scarcity of donor organs, complex surgical technical demands, and the necessity to prevent long-term complications. METHODS: The medical records of 440 consecutive patients younger than 18 years of age undergoing orthotopic liver transplantation for end-stage liver disease from March 20, 1984, to November 15, 1997, were reviewed. Results were analyzed using Cox multivariate regression analysis to determine the statistical strength of independent associations between pretransplant covariates and patient and graft survival. Actuarial patient and graft survival rates were determined at 1, 3, 5, and 10 years. The type and incidence of posttransplant complications were determined, as was the quality of long-term allograft function. The median follow-up period was 4.1 years. RESULTS: Biliary atresia was the most common cause (50.4%) of endstage liver disease in this patient population. The median recipient age was 2.4 years; 239 patients (54%) were younger than 3 years of age and 1 11 patients (25%) were younger than 1 year of age. There were 471 whole organs, 29 were ex vivo reduced size, 33 were living-related donor, and 36 were in situ split-liver allografts. Three hundred forty-three (78%) patients underwent a single allograft, whereas 97 patients required retransplantation; hepatic artery thrombosis was the most common indication for retransplantation (55 patients). The 1-, 3-, 5-, and 10-year actuarial patient survival rates were 82%, 80%, 78%, and 76%, respectively; allograft survival rates were 68%, 63%, 60%, and 54%. Long-term liver function remains excellent: current median follow-up values for total bilirubin and aspartate aminotransferase were 0.5 mg/dl and 54 IU/L, respectively. Cox multivariate regression analysis demonstrated that pretransplant patient age, the era of transplantation, and the number of allografts performed significantly and independently predicted patient survival rates, whereas allograft type and pretransplant diagnosis did not. CONCLUSIONS: Liver transplantation in the pediatric patient is a durable procedure that provides excellent long-term survival. Although there have been overall improvements in patient outcome with increased experience, the effect is most pronounced for patients younger than 1 year of age. Retransplantation, although effective in a meaningful number of patients, continues to carry a progressive decrement in survival with the number of allografts performed. Use of living-related and in situ split-liver allografts has dramatically reduced waiting times for small children and has improved patient survival.

Actuarial Analysis↗
PubMed1998

[Predictive value of the ergometric test stress parameters for myocardial ischemia according to SPECT thallium-201 scintigraphy].

BACKGROUND: Exercise EKG is used as the test of choice in the diagnosis of coronary artery disease. Classical parameters are angor and ST depression representing myocardial ischemia. AIM: To correlate exercise EKG parameters with SPECT 201Thallium to know their likelihood ratios for ischemia. PATIENTS AND METHODS: Two hundred seventy four patients (171 men), aged 58 years old as a mean, were studied. Of these, 23% had a prior myocardial infarction. The likelihood ratios for the presence of ischemia of ST depression, failure to increase blood systolic pressure, the presence of angor and its duration during stress testing were calculated according to the results of SPECT 201Thallium. Seventy one patients were also subjected to a coronary angiography. RESULTS: Among men, likelihood ratios for the presence of angor, failure to increase systolic pressure, ST alterations and duration of angor were 6.9, 6.15, 1.77 and 1.27 respectively. Among women, the figures were 5.45, 1.77, 0.58 and 1.4 respectively. The diagnostic accuracy of SPECT 201Thallium, when correlated with the results of coronary angiography, was 85%. CONCLUSIONS: Among men, the best exercise EKG predictors for myocardial ischemia were the failure to increase systolic blood pressure and the presence of angor. Among women the only significant predictor was the presence of angor.

Coronary Angiography↗
PubMed1997

Different determinants on growth and synapse formation in cultured neurons.

The influence of substrate and target on growth and synapse formation was investigated in identified leech neurons in culture. Nociceptive neurons and annulus erector motoneurons were cultured on ganglion capsules, a substrate they encounter in the leech. Within a few hours, single nociceptive cells sprouted profusely, whereas annulus erector cells failed to grow. When annulus erector neurons were plated near a nociceptive cell on the same capsule both neurons grew, made contact and formed an electrical synapse, different from the chemical synapse they form in the ganglion, but identical to that formed when plated on Concanavalin A. These results suggest that substrate and target have complementary effects regulating growth, but fail to define the type of synapse formed.

Animals↗
PubMed1997

Delayed encephalopathy in fulminant hepatic failure in the pediatric population and the role of liver transplantation.

BACKGROUND: Liver transplantation is the therapeutic choice for fulminant hepatic failure in children. METHODS: All 66 cases of fulminant hepatic failure in the pediatric population seen at UCLA from May, 1985 to November, 1993 were reviewed to determine changes in survival rates since the advent of liver transplantation. We evaluated the clinical course and events leading to the exclusion of surgical management of nonsurvivors, who otherwise would have benefited from a liver transplant. We also compared the latter's clinical course with the nontransplant survivors to determine parameters for screening patients for liver transplantation. RESULTS: Fifty-one patient (77%) were put on the transplant list initially but eventually, only 38 (58%) patients underwent orthotopic liver transplantation (OLT) and of these 30 (79%) patients survived. Of the remaining 29 (42%) patients who did not undergo liver transplantation, only 10 (36%) patients survived. Nine patients died while waiting for a donor liver secondary to complications of hepatic failure. The majority of nonsurvivors in the OLT and no-OLT groups succumbed because of irreversible neurologic deterioration. In the no-OLT group, comparisons between survivors and non-survivors were made. There were no significant demographic differences. It took a mean of 8 days (+/-8) versus 22 days (+/-15), (p = 0.009), from onset of illness to first hospital admission for survivors and nonsurvivors, respectively. Time to reach stage II encephalopathy was a mean of 5 days (+/-5) for survivors versus 18 days (+/-16), (p = 0.05) for nonsurvivors. Nonsurvivors were transferred to the transplant center at a mean of 12.2 days (+/-12) after being first admitted elsewhere as compared to a mean of 1.9 days (+/-18) for survivors, (p = 0.02). Mean prothrombin time decreased by a mean of 13.4 s/day (+/-16) for survivors as against 2.25 s/day (+/-6) for nonsurvivors, (p = 0.06). Mean peak total bilirubin for nonsurvivors was 460 mumol/L (27 mg/dl) versus 220 mumol/L (13 mg/dl) for survivors, (p = 0.06). Nonsurvivors died at a mean of 30 days (+/-19) from onset and survivors' liver tests started to improve at a mean of 11 days (+/-9) from onset. CONCLUSIONS: From these studies, we conclude that liver transplantation remains the therapeutic choice for fulminant hepatic failure in children. Early referral and closer follow-up is necessary for timely admission to liver transplant centers to enable screening and proper preparation of these patients for liver transplantation.

Adolescent↗
PubMed1997

Changes in radioactive tracer distribution in rats after 24 hours of 45 degrees hind limb unweighting.

INTRODUCTION: Changes in radioactive tracer distribution were examined in rats after exposure to a simulated microgravity model of 45 degrees head down tilt (45HDT) or 45 degrees hind limb unweighting (45HU) for up to 24 h. METHODS: Rats were randomly assigned to either 45HDT (or 45HU) experimental groups or control groups for each time point of 0.5 h, 1 h, 2 h, 4 h, 8 h, or 24 h. The 0.5-h through 8-h experimental rats were anesthetized and placed head-down on a ramp at 45 degrees, while control rats were placed in a prone position. Non-anesthetized rats in the 24-h experimental group were tail-suspended at 45 degrees, while control rats were allowed unrestrained movement. Technetium-labeled diethylenetriamine pentaacetate (99mTcDTPA, physical half-life of 6.02 h, MW = 492 amu) and indium-labeled diethylenetriamine pentaacetate (111In DTPA, physical half-life of 3.5 d, MW = 545 amu) were used to measure body organ distributions of the radioactive tracers at the 0.5-h-8-h and 24-h time points, respectively. Major organs were harvested after each time period and measured for radioactive counts. Light and electron micrographs were examined. RESULTS: Mean 111InDTPA counts for the lungs, kidneys, and brains of the 24 h 45HU groups were significantly higher than control counts. Light and electron microscopy demonstrated the development of pulmonary edema in the alveolar septal areas after 2 h of 45HDT, and a shift in edema to the pulmonary airways and pulmonary arteries after 24 h of 45HU. CONCLUSIONS: Pulmonary edema development, accompanied by a significant increase in 111InDTPA lung, kidney, and brain counts in the 24-h 45HU groups, suggests vascular injury in the microcirculation of these organs.

Animals↗
PubMed1995

A randomized prospective trial of steroid withdrawal after liver transplantation.

The safety of steroid withdrawal in orthotopic liver transplant (OLT) recipients has been studied in a prospective trial with a comparison control group. Sixty-four recipients of ABO-compatible grafts (42 adults, 22 children) were randomized into a steroid withdrawal (SW) group and a control group. Inclusion criteria included survival > one year post-OLT and no rejection > six months after OLT. Exclusion criteria included previous graft loss secondary to rejection, > two episodes of documented rejection, patients transplanted for autoimmune hepatitis, and patients unable to receive azathioprine. Target HPLC cyclosporine levels in both groups were 100-200 ng/ml. Thirty-three patients entered the SW group and 31 the control group at a mean of 3.5 years after OLT; follow-ups were 592 and 527 days, respectively. Two patients in each group developed biopsy-proven rejection. In the SW group one patient rejected at three months, the other at nine months. Both rejection episodes resolved with only reinstitution of oral prednisone. Of the two patients who rejected in the control group (one at 7 months, one at 11 months) one required conversion to tacrolimus and the other intravenous steroids. There were no significant differences between the two groups for prednisone, azathioprine, cyclosporine doses, cyclosporine levels, liver function tests, and white blood cell counts at base line compared with 12 months. Fasting serum cholesterol in the SW group decreased from 194 +/- 44 mg/dl at baseline to 175 +/- 37 mg/dl at one year, whereas in the control group cholesterol rose from 180 +/- 48 mg/dl to 193 +/- 44 mg/dl. In pediatric patients no significant difference in age-adjusted height velocities over one year was seen between the two groups. We concluded that dual therapy with cyclosporine and azathioprine in stable long-term liver allograft recipients is not associated with an increase in rejection incidence. Prednisone withdrawal may be associated with an improvement in lipid profiles.

Adult↗
PubMed1995

The treatment of intractable rejection with tacrolimus (FK506) in pediatric liver transplant recipients.

We report our experience in 17 pediatric orthotopic liver transplant (OLT) patients converted from cyclosporine (CsA) to FK506 for intractable acute and chronic rejection. FK506 was initiated orally at a dose of 0.3 mg/kg/day in most patients; the dose was then adjusted to achieve serum levels of 0.5-1.5 ng/ml. Azathioprine was discontinued and low-dose prednisone maintained. The median time between liver transplantation and FK506 conversion was 41 months. Patients have been treated for an average of 14.8 +/- 9.6 months. Six patients were converted for acute rejection and 11 for chronic rejection, i.e., vanishing bile duct syndrome (VBDS). After FK506 conversion, the actual patient and graft survival was 88% and 82%, respectively, in the group as a whole. Two patients died, one of chronic active hepatitis C and the other of lymphoma. Three patients, all with VBDS, did not respond to FK506 and therefore required retransplantation. The serum bilirubin is currently normal in 14 patients and the serum transaminases < 100 IU/ml in 12. The mean bilirubin pre-FK506 of patients successfully converted to FK506 was 4.2 mg/dl compared to 11.8 mg/dl in patients who failed conversion. Major complications included nephrotoxicity, neurotoxicity, and lymphoma. The mean glomerular filtration rate (GFR) of 97 +/- 29 mls/min/1.73m2 prior to FK506 conversion dropped to 51 +/- 20 mls/min/1.73m2 (p = 0.0001) after a mean of 13.6 months of FK506 therapy. Three patients have developed B-cell lymphomas; two of them responded to decreased immunosuppression and one died. We conclude that intractable liver graft rejection in children is most successfully reversed if FK506 is instituted before cholestasis becomes pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

The value of portal vein pulsatility on duplex sonograms as a sign of portal hypertension in children with liver disease.

OBJECTIVE: The purpose of this study was to determine the significance of portal vein pulsatility on duplex Doppler waveforms in children with end-stage hepatic failure undergoing liver transplantation. SUBJECTS AND METHODS: Thirty-eight children with end-stage hepatic decompensation were examined with color-assisted spectral Doppler waveform analysis of the hepatic artery and the portal vein. Correlation was made with age, duration of illness, clinical and pathologic diagnosis, and presence of portal hypertension. Findings were compared with those for six patients with acute viral hepatitis and 12 healthy control subjects. RESULTS: Portal vein pulsatility was noted in all 36 patients in whom portal vein flow was detected by Doppler imaging. The majority of these (34) had clinical or sonographic evidence of portal hypertension. In two patients, no portal vein flow was identified in the liver hilum; both had a large portosystemic shunt through collaterals or surgical graft. Significantly increased pulsatility of the hepatic artery waveform (resistive index [RI] = 0.89 +/- 0.15, p < .0001) was seen in patients with end-stage liver disease. In contrast, no portal vein pulsatility and normal hepatic artery pulsatility (RI = 0.60 +/- 0.11) was noted in all patients with acute hepatitis and control subjects. CONCLUSION: Portal vein waveform pulsatility is 94% sensitive and 90% specific for portal hypertension in end-stage liver disease.

Acute Disease↗
PubMed1995

[Perineal endometriosis. Clinical experience with 8 patients].

We report our experience with 8 women with perineal endometriosis managed in a period of 20 years. All were multiparae women presenting with cyclical perineal painful masses related to menstrual periods. Symptomatology started 6 months to 16 years after last delivery. Three patients had partial involvement of the anal sphincter. The endometriosis area was locally resected in all women. There were no complications and no problems with anal continence. Two patients had local recurrences. The different lapses between delivery and symptomatic presentation can be related to the amount of endometrial basal cells implants in the episiotomy. The treatment is always surgical. All endometrial implants must be resected and sphincteric structures must be repaired posteriorly.

Adult↗
PubMed1995

[Reactive arthritis caused by Yersinia enterocolitica and Chlamydia trachomatis].

We studied the clinical course, microbiological investigations and laboratory parameters in 10 patients with reactive arthritis (ReA). The number of patients with arthritis included was 10. Triggering agents were: seven patients had positive agglutinating antibody against Yersinia enterocolitica. Three cases had positive antibody test against Chlamydia trachomatis. In all patients antibody test were recovered. The clinical finding were: 4 patients with polyarthritis, 4 mono-oligoarthritis and two cases sacroileitis. The mean of index active joints were 6 (1-14). More frequent pattern were episodes of arthritis with lower limbs joints involvement. Outcome were of 12.1 (2-24) months. All of culture were negative. The laboratory parameters were unremarkable, except ESR were higher, HLA B-27 were positive in 70% of patients. The radiological signs and synovial biopsy studies were not conclusive. Eight patients were treated with antibiotics, not did antibiotics affect over duration of ReA.

Adult↗
PubMed1995

[Paternity study applying DNA polymorphism: evaluation of methods traditionally used in Chile].

Simultaneous detection of several VNTR loci using a single DNA probe is the basis of the technique called "DNA fingerprint" (DNAfp) of increasing application in parenthood identification. According to the data gathered by different laboratories worldwide, father exclusion can be made in a larger number of cases when compared with the customary tests based on erythrocyte antigens. The question could then be whether DNAfp will completely replace erythrocyte antigens tests. We report here our experience in applying DNAfp to 92 samples corresponding to 34 paternity cases and comparing these with the results obtained with the antigens of the systems ABO, Rh, MNSs, Duffy and Kidd. Most of the HaeIII/digested DNA samples produced 13 to 16 bands larger than 4.3 Kb (average 14,0761 +/- 2,205). Average band sharing between pairs of unrelated individual was 1,9107 +/- 1,083. Two cases presenting an a posteriori probability of being the father of 80.7% and 76.5% by erythrocyte antigens were clearly excluded by DNAfp. All exclusions made by antigens were confirmed by DNAfp. In the cases reported as father "rather probable" (28 cases) by DNAfp, these shared with the child 6,7407 +/- 1.7 bands on average. Because of time, cost and simplicity we favor a procedure starting with the antigens test and continuing with DNAfp only when an exclusion is not possible. Economy will increase as the number of exclusions increases.

Blood Grouping and Crossmatching↗