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Biomedical subjects

A Benito

Publications and source records attributed to A Benito.

At least 109 records · Page 6Linked to original sources
PubMed1993

Enhanced production of pL-controlled recombinant proteins and plasmid stability in Escherichia coli RecA+ strains.

Overexpression of pL-controlled foot-and-mouth disease virus recombinant proteins was studied in Escherichia coli RecA+ strains and in a recA mutant. Higher protein yield and extractable plasmid DNA amounts were found in wild type cells, in absence of detectable RecA proteolytic activity. Minor but still significant differences in pBR322 DNA amounts were also detected between RecA+ and its recA13 and lexA1 derivatives. These data should be seriously considered to select expression systems and to design production processes for recombinant proteins, specially if they are expected to be toxic for Escherichia coli cells.

Aphthovirus↗
PubMed1993

Resistance of Plasmodium falciparum to antimalarial drugs in Equatorial Guinea.

One hundred and sixty-six children from Equatorial Guinea, all under 10 years of age and with acute uncomplicated falciparum malaria, were randomly allocated to four groups and treated with one of the following regimens: chloroquine or amodiaquine (25 mg base/kg body weight over 3 days), quinine (8 mg/kg every 8 h for 3 or 5 days), and sulphadoxine-pyrimethamine (25-1.25 mg/kg, in one dose). The parasite clearance rates up to day 14 were 28% with chloroquine, 74% with amodiaquine, and 95% with quinine or sulphadoxine-pyrimethamine. The times required to clear asexual blood forms of Plasmodium falciparum in sensitive cases were 64, 70, 73 and 65 h, respectively. Although quinine and sulphadoxine-pyrimethamine are equally effective, quinine is recommended for treatment of multidrug-resistant malaria in paediatric patients, essentially because of the risk of serious reactions to sulpha drugs. Health providers are, however, encouraged to keep supplies of sulphadoxine-pyrimethamine as an option and to refer patients quickly, if required.

Amodiaquine↗
PubMed1993

Baseline entomological data for a pilot malaria control program in Equatorial Guinea.

Entomological studies conducted on the island of Bioko and the mainland province, Río Muni, in Equatorial Guinea provided baseline data for a pilot malaria control program. The main species collected resting in houses at low density were Anopheles gambiae s.l. Giles and Anopheles funestus Giles. An. gambiae s.l. density increased during the rainy season, whereas An. funestus populations remained stable during both dry and wet seasons. Both species tended to be endophilic and were not collected resting or biting outdoors. Overall, delayed sporozoite rates were about 10% for both species and were highest in the dry season. An. gambiae s.l. from the mainland showed resistance to 4% DDT, but the island population was still susceptible. All populations were completely susceptible to 5% malathion and 0.025% deltamethrin.

Animals↗
PubMed1993

Fine regulation of cI857-controlled gene expression in continuous culture of recombinant Escherichia coli by temperature.

The expression at different temperatures of the lacZ gene, which is controlled by the lambda pL and pR tandem promoters and the cI857 temperature-sensitive repressor, was studied in Escherichia coli continuous cultures. At temperatures between 30 and 42 degrees C, beta-galactosidase activity behaved according to an exponential equation. By inducing a culture at a temperature within this range, predefined, nearly constant submaximal levels of gene expression and recombinant product yield can be obtained.

Escherichia coli↗
PubMed1987

[A case of chloroquine-resistant malaria of type R3 originating in Cameroon].

World areas with chloroquine-resistant falciparum malaria are progressively spreading, in Africa from East to West. We are reporting here a new case of resistance, grade III, from Cameroon, carried out in vitro by the WHO standard macrotest. Resistance is determined by the ability of trophozoites to develop into schizonts when therapeutic doses of chloroquine have been administered.

Africa, Western↗
PubMed1984

[Normal blood pressure values in Spanish children].

Authors study 2,953 children with a range of age between 2 and 14 years, of both sexes, from schools in Madrid, Zaragoza, Lugo, Andújar, Archena and in rural areas of Guadalajara and Segovia. Blood pressure was measures three times in every child according to recommendations of the Expert Committee of WHO in respect to the method. Results are expressed in percentiles according to age and sex. Their findings indicate that both diastolic and systolic blood pressures were lower than those reported by Task Force (USA), Cassimos (Greece) and Andre (France) (p less than 0.001) with higher differences being present in the diastolic blood pressure.

Adolescent↗
PubMedDate not supplied

Active concentration measurements of recombinant biomolecules using biosensor technology.

Whereas the concentration of a biomolecule simply refers to the amount of chemical substance per unit of volume, its active concentration refers to a relational parameter that has meaning only with respect to the molecule's ability to interact specifically with one particular ligand. When proteins are studied in a biological context, it is the biologically active concentration that is relevant, and not the total concentration of correctly and incorrectly folded molecules. Using a biosensor instrument the concentration of active biomolecules in a preparation can be measured by injecting the preparation at different flow rates onto a sensor chip surface presenting a high concentration of a specific ligand. The method can be used under conditions of partial mass transport limitation and does not require a pre-established standard curve. When the method was used to measure the active concentration of several recombinant proteins it was found that the active concentration was much lower than the nominal concentration determined by conventional methods. The active concentration also depended on the ligand used in the binding assay, reflecting the fact that active concentration can only be defined with respect to one specific probe. Such discrepancies in concentration values, if undetected, may lead to erroneous conclusions regarding the properties and behaviour of recombinant proteins tested in different assays.

Antigens, CD↗
PubMedDate not supplied

Doppler ultrasound for TIPS: does it work?

The role of transjugular intrahepatic portosystemic shunt (TIPS) in the management of complications of portal hypertension such as variceal hemorrhage and ascites is well established. However, TIPS has a limited patency due to dysfunction consisting in occlusion or stenosis of the intrahepatic tract or stenosis of the outflow hepatic vein. Timing of dysfunction cannot be predicted, so routine surveillance and percutaneous intervention are continuously required to maintain TIPS patency. Trans-shunt venography is the gold standard technique in TIPS evaluation, but it is expensive and invasive. Doppler ultrasound (DU) has been the most commonly used noninvasive tool in TIPS patency. Despite many reported series, its role remains controversial. After more than 10 years of experience with TIPS, we followed our patients with DU and trans-shunt venography to establish Doppler criteria of dysfunction and its accuracy in assessing shunt dysfunction.

Blood Flow Velocity↗
PubMedDate not supplied

Interventional therapeutic techniques in Budd-Chiari syndrome.

PURPOSE: To analyze the results obtained with percutaneous therapeutic procedures in patients with Budd-Chiari syndrome (BCHS). METHODS: Between August 1991 and April 1993, seven patients with BCHS were treated in our hospital. Three presented with a congenital web; in another three cases the hepatic veins and/or the inferior vena cava (IVC) were compromised after major hepatic surgery; one patient presented with a severe stenosis of the intrahepatic IVC due to hepatomegaly. RESULTS: One of the patients with congenital web has required several new dilatations due to restenosis; one patient required a transjugular intrahepatic portosystemic shunt procedure while awaiting a liver transplantation. The two postsurgical patients with stenosed hepatic veins did not require any new procedure after the placement of metallic endoprostheses. However, the patient with liver transplantation presented IVC restenosis after balloon angioplasty that required the deployment of metallic endoprostheses. In the patient with hepatomegaly a self-expandable prosthesis was placed in the intrahepatic portion of the IVC before (4 months) a liver transplantation. CONCLUSION: Interventional therapeutic techniques offer a wide variety of possibilities for the treatment of patients with BCHS. For IVC stenoses, the results obtained with balloon angioplasty are at least as good as those obtained with surgery.

Adult↗
PubMedDate not supplied

Limitations of percutaneous techniques in the treatment of portal vein thrombosis.

New therapeutic alternatives to portal vein thrombosis (PVT) include the percutaneous, transhepatic infusion of fibrinolytic agents, balloon dilatation, and stenting. These maneuvers have proven to be effective in some cases with acute, recent PVT. We have treated two patients with acute PVT via transhepatic or transjugular approaches and by using pharmacologic and mechanical thrombolysis and thrombectomy. Although both patients clinically improved, morphologic results were only fair and partial rethrombosis was observed. The limitations of percutaneous procedures in the recanalization of acute PVT in noncirrhotic patients are discussed.

Adult↗
PubMedDate not supplied

Genotyping of Plasmodium falciparum infections by PCR: a comparative multicentre study.

Genetic diversity of malaria parasites represents a major issue in understanding several aspects of malaria infection and disease. Genotyping of Plasmodium falciparum infections with polymerase chain reaction (PCR)-based methods has therefore been introduced in epidemiological studies. Polymorphic regions of the msp1, msp2 and glurp genes are the most frequently used markers for genotyping, but methods may differ. A multicentre study was therefore conducted to evaluate the comparability of results from different laboratories when the same samples were analysed. Analyses of laboratory-cloned lines revealed high specificity but varying sensitivity. Detection of low-density clones was hampered in multiclonal infections. Analyses of isolates from Tanzania and Papua New Guinea revealed similar positivity rates with the same allelic types identified. The number of alleles detected per isolate, however, varied systematically between the laboratories especially at high parasite densities. When the analyses were repeated within the laboratories, high agreement was found in getting positive or negative results but with a random variation in the number of alleles detected. The msp2 locus appeared to be the most informative single marker for analyses of multiplicity of infection. Genotyping by PCR is a powerful tool for studies on genetic diversity of P. falciparum but this study has revealed limitations in comparing results on multiplicity of infection derived from different laboratories and emphasizes the need for highly standardized laboratory protocols.

Analysis of Variance↗
PubMedDate not supplied

Ammonium-mediated reduction of plasmid copy number and recombinant gene expression in Escherichia coli.

The effect of ammonium as a medium supplement on plasmid-encoded recombinant beta-galactosidase synthesis was explored in Escherichia coli cells during aerobic growth in complex medium. After induction, only doses of ammonium chloride below 1 g/L are able to transiently enhance the yield. However, the presence of nontoxic ammonium chloride concentrations of up to 10 g/L results in lower values of beta-galactosidase in a concentration-dependent fashion. A significant reduction in plasmid DNA content explains the decrease in the yield by a gene-dosage-involving mechanism.

Ammonium Chloride↗
PubMedDate not supplied

Successful unrelated umbilical cord blood transplantation in a child with Omenn's syndrome.

Omenn's syndrome is a variant of combined immunodeficiency disease (CID). Like other CID forms, it causes death unless the patient receives a bone marrow transplant (BMT). Previous reports have shown that BMTs from unrelated donors in Omenn's syndrome have very poor results, with a high rate of infections during transplantation and graft rejection, when compared with transplants from related donors or patients with other CID. This study discusses the case of a 19-month-old child with Omenn's syndrome, who received an unrelated cord blood stem cell transplant (CBT). Donor and recipient had 1 HLA-Ag mismatched on HLA-B. Symptomatology improved early after CBT. The child achieved leukocytes and platelet engraftment and was discharged on day +34. His follow-up has been uneventful and at this time, 27 months after CBT, immune functions have been recovered.

Eosinophilia↗
PubMedDate not supplied

Indications for epiphyseal preservation in metaphyseal malignant bone tumors of children: relationship between image methods and histological findings.

We compared several image methods in the evaluation of the possible physeal effect in 47 osteosarcomas and 18 Ewing's sarcomas in children. The minimal follow-up was 3 years (range, 3-17). In the histological study, the physis was affected in 53% of the cases. We correlated the histological findings and the findings from the different image methods. There were more false-positive than false-negative results, and in the computed tomography and magnetic resonance imaging (MRI) studies, there were no false negatives. The accuracy of MRI (predictive positive value plus predictive negative value) was the best (90.3%), and it is the technique that we prefer. According to these findings, we can safely preserve the epiphysis in cases of metaphyseal tumors showing no contact between the tumor and the growth plate in the MRI images. If the tumor shows contact with part of the physis, it is also possible to preserve the epiphysis.

Adolescent↗
PubMedDate not supplied

Horseshoe kidney presenting as a retroperitoneal mass. Report of a case diagnosed by fine needle aspiration cytology.

BACKGROUND: Horseshoe kidney is a renal congenital anomaly. It is the result of the fusion of either upper or lower poles of both kidneys, appearing as a horseshoe-shaped structure. This anomaly is very frequent: it can be found in about 1 of every 50-1,000 autopsies). CASE: Computed tomography performed routinely after pancreatitis in a 37-year-old female showed a retroperitoneal mass of uncertain origin. Fine needle aspiration cytology (FNAC) smears evidenced normal renal tissue. Urography confirmed the diagnosis of horseshoe kidney. CONCLUSION: This is the first reported case of horseshoe kidney diagnosed by FNAC. It demonstrates the utility of FNAC for diagnosis of retroperitoneal masses, especially if they are asymptomatic.

Adult↗