Search PubMed⌕ Search

Biomedical subjects

F Alvarez

Publications and source records attributed to F Alvarez.

At least 145 records · Page 8Linked to original sources
PubMed1995

Effect of cyclophosphamide administration on the activity and relative content of hepatic P4502D1 in rat.

1. The effects of the administration of the anticancer and immunosuppressive drug, cyclophosphamide, to the rat on hepatic P4502D1 activity and content in the microsomal fraction have been examined. 2. Liver microsomes were obtained from male Hooded Wistar rats administered a single dose (i.p.) of saline or cyclophosphamide (200 mg/kg). Rats receiving cyclophosphamide were killed 1, 4, 7, 10 or 14 days after cyclophosphamide administration. The O-demethylation of dextromethorphan to dextrorphan was used to monitor 2D1 activity. 3. The mean Vmax for dextrorphan formation was reduced significantly (p < 0.0001) 7, 10 and 14 days after cyclophosphamide administration compared with the control group (control, 0.32 +/- 0.07; 7-day, 0.20 +/- 0.08; 10-day, 0.11 +/- 0.02; and 14-day group, 0.15 +/- 0.02 nmol/mg/min). 4. Western blotting revealed that there was a significant reduction (p < 0.0005) in the microsomal relative 2D1 content 10 days after cyclophosphamide administration compared with the control group (control, 1.25 +/- 0.44; and 10-day group, 0.65 +/- 0.14). 5. The activity of reduced nicotinamide adenine dinucleotide phosphate P450 reductase was significantly reduced (p < 0.0001) 7, 10 and 14 days following cyclophosphamide administration (control, 215 +/- 24; 7-day, 102 +/- 20; 10-day, 59 +/- 4 and 14-day group, 76 +/- 8 nmol/mg/min). Cytochrome b5 content was significantly reduced (p < 0.0001) 7 and 10 days following cyclophosphamide administration (control, 0.46 +/- 0.13; 7-day, 0.28 +/- 0.07 and 10-day group, 0.20 +/- 0.03 nmol/mg). 6. The significant reductions in the activity of rat hepatic microsomal 2D1 following cyclophosphamide administration, as seen by the alterations in mean Vmax for dextrorphan formation, do not appear to be due to a single factor, but may result from a combination of several events, including reductions in relative 2D1 content, reduced nicotinamide adenine dinucleotide phosphate P450-reductase activity and cytochrome b5 content.

Animals↗
PubMed1995

[Prevalence of digestive symptoms in normal adult women and its association with cholelithiasis].

The aim of this work was to study the prevalence of biliary diseases and digestive symptoms in normal adult women. Four hundred nineteen women were chosen; of these 145 were discarded due to previous gastrointestinal diseases (20), previous gastrointestinal complaints (38) and previous cholecystectomy (85). Two hundred seventy six women were subjected to abdominal ultrasound examination; of these 53 had cholelithiasis and in three a gallbladder cancer was suspected (and confirmed by surgery). Considering women with previous cholecystectomy, cholelithiasis and gallbladder cancer, a 33.6% prevalence of biliary diseases can be inferred. An interrogation about gastrointestinal symptoms was performed to women subjected to ultrasound examinations, by 2 professionals unaware of ultrasound results. A high frequency of pyrosis, food intolerance and constipation was found, not observing differences between women with or without cholelithiasis. However, these last women had a higher frequency of upper abdominal pain. Both groups had also a high rate of previous surgical procedures.

Adult↗
PubMed1995

[Airway continuous positive pressure in acute respiratory failure caused by Pneumocystis carinii pneumonia].

OBJECTIVE: To evaluate the efficiency of continuous positive airway pressure through a face mask in acute respiratory insufficiency (ARI) secondary to Pneumocystis carinii pneumonia. DESIGN: Prospective study. SETTING: Multidisciplinary ICU. PATIENTS: Fifteen patients with ARI secondary to Pneumocystis carinii pneumonia were studied. INTERVENTIONS: Initially al patients received high flow oxygen therapy through a face mask for 60 minutes (Pre-CPAP phase); then CPAP through a face mask, with identical FiO2 and for a similar period of time (Pst-CPAP phase). At the end of each phase the following parameters were evaluated: respiratory rate, heart rate, arterial gases, acid-base balance, and respiratory muscle motility. MEASUREMENTS: After oxygen therapy all fifteen patients had similar variables. After 60 minutes with CPAP through a face mask, significant improvements were noted for respiratory rate, heart rate, muscular effort, PaO2, SaO2, and PaO2/FiO2 (p < 0.001) in eleven patients, who survived after a mean stay of 8.5 days in the ICU with no evidence of major complications. In contrast, CPAP failed in four patients as respiratory rate, heart rate and vigorous muscle effort remained unchanged and, although PaO2 and SaO2 increased, the obtained values were significantly lower than in the remaining patients. Consequently, they underwent intubation and mechanical ventilation and after a mean stay of fourteen days with this ventilatory option died. CONCLUSIONS: These results confirm that CPAP through a face mask is an effective means to improve oxygenation in patients with Pneumocystis carinii pneumonia who develop hypoxemic respiratory insufficiency. Its early introduction in hospital protocols can help improving the prognosis in certain patients with severe PCP and avoid their admission to ICU, which would be thus preserved for those patients requiring mechanical ventilation.

Acute Disease↗
PubMed1995

[Noninvasive ventilator support in patients with chronic obstructive pulmonary disease. A comparison of 2 methods].

The external high frequency oscillation around a negative baseline (EHFO-NB) is a new mode of non-invasive ventilatory support which could replace or complement nasal intermittent positive pressure ventilation (NIPPV) for treatment of patients with chronic obstructive pulmonary disease, both in the decompensation phases and as preventive measure in intercrisis periods. This was a prospective study in which tolerance and short term effects on acid-base balance and gas interchange of both NIPPV and EHFO-NB in twenty patients with severe chronic obstructive pulmonary disease were compared. With both methods similar decrease in PaCO2 and increases in pH were observed, with decrease and increase in respiratory frequency when using NIPPV and EHFO-NB, respectively; the latter in association with the high oscillation frequencies used. While an improvement of SaO2 and no changes in PaO2 and intrapulmonary shunt were observed on NIPPV, a decrease was observed in the SaO2 and an increase in the shunt on EHFO-NB. Comfort of patients, improvement of perceived sensation of dyspnea, and the absence of complications were similar with both methods. While on NIPPV, 75 per cent of patients required a short period of training and continuous supervision.

Aged↗
PubMed1995

Evaluation of the left ventricular performance through equilibrium radionuclide angiocardiography.

In patients with severe heart failure due to acute myocardial infarction (AMI) breathing with PEEP can be of additional therapeutic value. This study was designed to assess the effects of CPAP through face mask with 15 cm H2O on left ventricular performance in AMI patients, using equilibrium radionuclide angiocardiography (ERA). In response to lung inflation, high levels of PEEP have been shown to decrease heart rate and stroke volume. The sum of the TPF pathological prolongation and the Mean-FR reduction suggests a decrease in the left ventricular compliance determined by the restriction imposed by the positive pressure. The global systolic performance is preserved.

Adult↗
PubMed1994

Outcome of ABO-incompatible liver transplantation in children with no specific alloantibodies at the time of transplantation.

The shortage of suitable liver donors for children has motivated the use of ABO-incompatible (ABO-I) grafts for transplantation in urgent situations. However, survival after ABO-I liver grafts has been reported at about 30% as compared with 80% in cases of ABO-identical or -compatible liver grafts. This difference has been attributed to antibody-mediated, hyperacute or chronic liver rejection, due to preformed ABO antibodies (alloantibodies). In this study, we report our results with ABO-I livers in children without alloantibodies at the time of transplantation. From January 1988 to June 1993, 143 OLT were performed in 122 children. Eight children received 8 ABO-I liver grafts. Of these, 7 patients were included in the study. All 7 were alloantibody free before OLT. Five children were spontaneously alloantibody free, while in 2 children, the plasma alloantibodies were eliminated before and after transplantation using intravenous infusion of specific blood group antigens of the donor blood group (soluble antigens). Immunosuppression consisted of a triple-drug treatment combining CsA, AZA, and steroids. The follow-up period was between 10 and 48 months. One child died from a surgical complication. Six children survived, but 1 died 10 months later from intestinal obstruction. There were no graft losses and no episodes of hyperacute or chronic rejection. The graft and patient survival rate was 71%. There was a 28% incidence of rejection, but all were mild (requiring steroid boluses only). Our results suggest that the absence of ABO alloantibodies at the time of and after transplantation can protect ABO-I liver grafts against antibody-mediated rejection, whether hyperacute or chronic, and that soluble antigens are effective in eliminating alloantibodies in children.

ABO Blood-Group System↗
PubMed1994

Possible implications of CpG avoidance in the flatworm Schistosoma mansoni.

We report the analysis of the biases of CpG, TpG, and CpA of all the DNA sequences data from the Trematode Schistosoma mansoni. Our results show CpG avoidance whereas TpG and CpA frequencies are over the expected values. These characteristics are similar to the biases displayed by methylated genomes, but in platyhelminths 5mC has not been detected by biochemical methods. The possible implications of this CpG shortage are discussed.

Animals↗
PubMed1994

Autoimmune cholangiopathy: the result of consecutive primary biliary cirrhosis and autoimmune hepatitis?

Autoimmune cholangiopathy is a recently proposed entity that describes a specific group of patients presenting overlapping features of primary biliary cirrhosis and autoimmune hepatitis, i.e., clinical and/or biochemical cholestasis, high titer antinuclear antibody, negative antimitochondrial antibody, and elevated immunoglobulin G. Liver histology shows primary biliary cirrhosis coexisting with varying degrees of parenchymal inflammation. In addition, these patients achieve remission on corticosteroid therapy. The patient in this report fulfilled the above criteria. However, preceding the autoimmune cholangitis stage, a typical antimitochondrial antibody-positive primary biliary cirrhosis was documented with favorable response to ursodeoxycholic acid treatment. Twenty months later, the patient developed autoimmune hepatitis with elevated aspartate aminotransferase and immunoglobulin G and high titer antinuclear antibody as well as corticosteroid dependency, whereas the antimitochondrial antibody disappeared. The patient's sera initially showed reactivity to three mitochondrial proteins, the 74-, 64-, and 56-kilodalton autoantigens of the 2-oxo acid dehydrogenase complexes, which was characteristic of primary biliary cirrhosis. After developing autoimmune hepatitis, reactivity to the 74- and 64-kilodalton antigens disappeared, whereas reactivity to the 56-kilodalton antigen decreased to low levels. Autoimmune cholangitis and probably other forms of the overlap syndrome may result from the association of two diseases: primary biliary cirrhosis and autoimmune hepatitis.

Antibodies, Antinuclear↗
PubMed1994

Dinucleotide biases in the platyhelminth Schistosoma mansoni.

The analysis of dinucleotide biases in coding and flanking regions, introns, rDNA and repetitive sequences, in the flatworm Schistosoma mansoni is reported. Except for rDNA, all regions display CpG avoidance and TpG plus CpA excess, which might be evidence of the presence of 5mC. The distribution and hierarchies of dinucleotides differ from the data published for invertebrate and vertebrate coding sequences.

Animals↗
PubMed1994

Application of spheroid culture to human hepatocytes and maintenance of their differentiation.

Human hepatocytes cultured with a hormonally defined medium on non-adherent poly-(2-hydroxyethyl methacrylate)-coated surface were able to form spheroids. The maintenance of liver-specific functions was assessed by following secretion of albumin, transferrin and alpha 1-antitrypsin that were still detectable after 4 months of spheroidal culture. Moreover, cytochrome P-450 IA was induced by methylcholanthrene for up to 2 weeks. This cell system is very promising for long-term in vitro studies of human hepatocyte functions.

Albumins↗
PubMed1994

Multiplicative contexts in associative memories.

A system of networks, consisting of a first net that constructs the Kronecker product between two vectors and then sends it to a second net that sustains a correlation memory, defines a context-dependent associative memory. In the real nervous system of higher mammals, the anatomy of the neural connections surely exhibits a considerable amount of local imprecision superimposed on a regular global layout. In order to evaluate the potentialities of the multiplicative devices to constitute plausible biological models, we analyse the performances of a context-dependent memory when the multiplicative net, responsible of the construction of the Kronecker product, presents an incomplete connectivity. Our study shows that a large dimensional system is able to support a considerable amount of incompleteness in the connectivity without a great deterioration of the memory. We establish a scaling relationship between the degree of incompleteness, the capacity of the memory, and the tolerance threshold to imperfections in the output. We then analyse some performances that show the versatility of this kind of network to represent a variety of functions. These functions include a context-modulated novelty filter, a network that computes logical modalities and an adaptive searching device.

Animals↗
PubMed1994

Long-term follow-up of growth in height after successful liver transplantation.

Quantitative assessment of growth in height during the long-term follow-up of children who underwent orthotopic liver transplantation was done to allay concerns related to the progress of the children in terms of normal relationships with peers. Height curves were constructed for 119 children who received transplants at Bicêtre and Cochin Hospitals and were followed for more than 1 year. Poor linear growth was observed during the first 6 months after transplantation, during which time children received corticosteroids daily. The onset of catch-up growth was observed between 6 and 24 months after transplantation, and its magnitude did not differ between male and female patients. Both boys and girls underwent a normal pubertal growth spurt and normal development of secondary sexual characteristics. All adolescent girls had regular menstrual cycles, and one delivered a normal infant 6 years after transplantation. Patients who received transplants before the age of 2 years had poor average growth velocity by the third year after transplantation. Linear growth improved in almost all children and was not affected by the cause of the liver disease that existed before the liver transplantation except that fulminant hepatic failure was associated with poor growth. Long-term improvement of growth in height usually is obtained after liver transplantation in most children with chronic liver diseases. The use of low doses of corticosteroids, administered on an alternate-day basis, contributes to this improvement. Young age of the patient, but not the cause of the chronic liver disease, appears to influence the long-term outcome of linear growth.

Adolescent↗
PubMed1994

Evolution of codon usage and base contents in kinetoplastid protozoans.

In this study we analyze and compare the trends in codon usage in five representative species of kinetoplastid protozoans (Crithidia fasciculata, Leishmania donovani, L. major, Trypanosoma cruzi and T. brucei), with the purpose of investigating the processes underlying these trends. A principal component analysis shows that the G+C content at the third codon position represents the main source of codon-usage variation, both within species (among genes) and among species. The non-Trypanosoma species exhibit narrow distributions in codon usage, while both Trypanosoma species present large within-species heterogeneity. The three non-Trypanosoma species have very similar codon-usage preferences. These codon preferences are also shared by the highly expressed genes of T. cruzi and to a lesser degree by those of T. brucei. This leads to the conclusion that the codon preferences shared by these species are the ancestral ones in the kinetoplastids. On the other hand, the study of noncoding sequences shows that Trypanosoma species exhibit mutational biases toward A + T richness, while the non-Trypanosoma species present mutational pressure in the opposite direction. These data taken together allow us to infer the origin of the different codon-usage distributions observed in the five species studied. In C. fasciculata and Leishmania, both mutational biases and (translational) selection pull toward G + C richness, resulting in a narrow distribution. In Trypanosoma species the mutational pressure toward A + T richness produced a shift in their genomes that differentially affected coding and noncoding sequences. The effect of these pressures on the third codon position of genes seems to have been inversely proportional to the level of gene expression.

Animals↗
PubMed1994

Serpentine aneurysm: regrowth after a superficial temporal artery-middle cerebral artery bypass and internal carotid artery ligation: case report.

Giant serpentine aneurysms (GSAs) are infrequent. We present a 37-year-old patient with a giant serpentine aneurysm of the left middle cerebral artery that was treated with a superficial temporal artery to middle cerebral artery bypass and ligature of the left internal carotid artery. After 2 years, the patient presented new symptoms of neurological deterioration and the computed tomographic scan and arteriography showed regrowth of the aneurysm, which was excised. Enlargement of a giant serpentine aneurysm once it has been treated with ipsilateral carotid ligation and/or bypass anastomosis is rare, and only two cases have been described previously.

Adult↗
PubMed1994

Anti-rat liver microsomal and cytosolic antibodies in hepatitis C virus infection.

In order to assess the frequency of autoimmunity markers in hepatitis C virus infection, 229 RIBA 2 HCV positive individuals were tested by ELISA and Immunoblot assay using as antigen rat liver microsomal and cytosolic proteins. Twenty-one out of 229 individuals (9%) showed anti-rat liver microsome antibodies by ELISA, but the titre was low (1:100 to 1:1,600). In Immunoblot, only 5 of these 21 ELISA positive sera recognized also rat liver microsomal proteins (MW between 30 to 64 kDa). Antibodies against rat liver cytosolic proteins were found by ELISA in 14 out of 229 individuals (6%). Three of them showed a reactivity in Immunoblot to 42 kDa or 55 kDA proteins. In conclusion, HCV infection could induce an autoimmune response against rat liver microsomal and cytosolic proteins in a small number of subjects; the titre of antibodies being lower and the pattern of reactivity different in respect to patients with autoimmune hepatitis.

Animals↗