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Biomedical subjects

J Benitez

Publications and source records attributed to J Benitez.

At least 37 records · Page 2Linked to original sources
PubMed1997

Correlation between mutations in p53 gene and protein expression in human lymphomas.

A discordance between p53 protein overexpression and the presence of mutations in the gene has been observed in many types of tumors, including human lymphomas. To probe this finding, we have studied a large series of 94 lymphomas of different pathologic types and histologic differentiation. Analyzing exons 5-9, we have found mutations in the p53 gene in 7 of 94 cases distributed in different subtypes: 4/12 (33%) high-grade B-cell non-Hodgkin's lymphomas (B-NHLs), in 1 of 5 (20%) high-grade mucosa-associated lymphomas (MALT), in 1 of 22 (4.5%) anaplastic large cell lymphoma (ALCL), and in 1 of 24 (4%) T-cell NHLs. Immunostaining with anti-p53 antibody DO-7 was possible in 87 lymphomas, and overexpression of p53 protein was observed in 16 cases (18%). A discrepancy between the results of SSCP and immunostaining was detected on 18 tumor samples. Two cases with mutations in the gene showed no altered protein expression and 16 cases overexpressed p53 protein had no point mutations. In these cases, the possibility that mutations occur outside the exons studied has been tested and the entire coding sequence analyzed. Only one case showed a mutation in exon 10, and we found two cases carrying a polymorphism in exon 4 and in intron 10. We conclude that mutations in p53 occur mainly in high-grade B-cell NHLs. Although not limited to a specific subtype of lymphoma, they may be rare in Hodgkin's disease and in low-grade lymphomas. The discrepancies between overexpression and presence of mutations suggest (1) the existence of another mechanism to stabilize the p53 protein, and (2) that the immunohistochemistry cannot be used to predict mutations in the gene.

Antibodies, Monoclonal↗
PubMed1997

Aerobic degradation of olive mill wastewaters.

The degradation of olive mill wastewater by aerobic microorganisms has been investigated in a batch reactor, by conducting experiments where the initial concentration of organic matter, quantified by the chemical oxygen demand, and the initial biomass were varied. The evolution of the chemical oxygen demand, biomass and the total contents of phenolic and aromatic compounds were followed through each experiment. According to the Contois model, a kinetic expression for the substrate utilization rate is derived, and its biokinetic constants are evaluated. This final predicted equation agrees well with all the experimental data.

Aerobiosis↗
PubMed1997

Cytogenetic and molecular studies of siblings with ataxia telangiectasia followed for 7 years.

We present cytogenetic, immunologic, and molecular data obtained over 7 years from a family with ataxia telangiectasia (AT) including 2 affected children and their unaffected sibling, and their obligate heterozygous parents. In a period of 3 years, the T lymphocytes from both AT patients showed clonal rearrangements of chromosomes 7 and 14 at specific bands (7p13, 7q35, 14q12, and 14q32), where loci for the Ig and TCH genes are located. A molecular study was carried out on peripheral blood and bone marrow samples from both patients using Southern blot and PCR for Ig and TCR genes. A monoclonal population for TCR gamma was observed in one of the two affected children, but only in peripheral blood.

Adolescent↗
PubMed1997

Hypermethylation of a 5' CpG island of p16 is a frequent event in non-Hodgkin's lymphoma.

Hypermethylation of a 5' CpG island of p16 gene has been recently described as a possible way of inactivation of this tumor suppressor gene, alternative to deletions and mutations. We have investigated if hypermethylation of a 5' CpG island of p16 occurs in non-Hodgkin's lymphoma (NHL) and normal lymphoid tissue. A total of 82 NHLs were examined for p16 methylation by Southern blot and PCR analysis. Hypermethylation was detected in approximately 20% of B cell lymphomas of both low and high grade and in 15% of T cell NHL. The highest rate of p16 gene methylation in tumors was found among MALT (mucosa-associated lymphoid tissue) lymphomas in which the percentage of cases with p16 gene methylation reached 67%. However, normal lymphoid tissue was always unmethylated at p16 locus. These results indicate that p16 gene methylation is a frequent event in NHLs, mainly in MALT lymphomas, and suggest that it could be an important mechanism of inactivation of this gene.

Binding Sites↗
PubMed1996

Cryopreservation of human skin with propane-1,2-diol.

The tolerance and cryoprotective effect of propane-1,2-diol on human skin was evaluated using tetrazolium reductase enzyme activity to assess tissue viability. The tolerance of human skin was tested by exposing the skin to increasing concentrations of propane-1,2-diol (10, 20, and 40% v/v), at two permeation temperatures (4 degrees C or room temperature), in a stepwise manner, to reduce osmotically induced changes in cell volume. There was no evidence of specific toxicity attributable to the cryoprotectant during the permeation period, even at a concentration of 40%; however a significant decrease in human skin viability was observed after freezing and thawing with high concentrations of cryoprotectant. The only useful protocol was that employing a low cooling rate (-1 degree C min-1) with 10 or 20% (v/v) propane-1,2-diol at a low permeation temperature. The data suggest that propane-1,2-diol does not produced improved results when compared with other cryoprotectants used for skin cryopreservation.

Cryopreservation↗
PubMed1996

Novel rhodopsin mutation in an autosomal dominant retinitis pigmentosa family: phenotypic variation in both heterozygote and homozygote Val137Met mutant patients.

A family affected with autosomal dominant retinitis pigmentosa (RP) is presented. Two clinically affected patients (mother and daughter) were heterozygous for the same novel missense mutation (Val137Met) of the rhodopsin gene (RHO). Both heterozygous and homozygous cases were observed among their few symptomatic relatives. Wide clinical variation was exhibited among the individuals with mutations in this family. None of the controls showed this change in RHO, nor has it been previously reported in other RP families. No other RHO mutation was observed. Additional genetic or environmental factors could play a role in modulating the penetrance and clinical expression of this RHO mutation.

Base Sequence↗
PubMed1996

CYP1A2 activity, gender and smoking, as variables influencing the toxicity of caffeine.

We have investigated several factors that might be related to the occurrence of toxic effects during the performance of a urinary test with caffeine (300 mg p.o.), in 120 healthy volunteers. A total of 218 toxic effects were self-reported by eighty-two (68%) subjects. Females and nonsmokers were at the highest risk (chi-square test, P = 0.01). Furthermore, two nonsmoking females experienced a symptomatology with delirium, restlessness, muscle tremor, vomiting and wakefulness. Among females and nonsmokers, those subjects who experienced toxic effects had lower caffeine N3-demethylation index (CYP1A2 activity) compared with unaffected females (1.87 +/- 0.51 vs 1.47 +/- 0.27, P < 0.0005) and nonsmokers (1.69 +/- 0.23 vs 1.49 +/- 0.31, P < 0.02). Caffeine N1- and N7-demethylations indices were also lower among females (P < 0.0005) and nonsmokers (P < 0.02) who reported toxic symptoms. We conclude that CYP1A2 activity, gender and smoking are variables to be considered as influencing the toxicity of caffeine.

Adult↗
PubMed1996

Homozygous myotonic dystrophy: clinical and molecular studies of three unrelated cases.

We report the clinical and molecular study of three unrelated homozygous myotonic dystrophy patients. In the first family, the homozygous patient shows the classical form of the disease with two DM alleles of very different expansion sizes (1000 and 60 repeats). In the second family, the homozygous patient is mildly affected and carries a minimally expanded allele (64 repeats) and a "normal" allele (38 repeats) that increases in size when transmitted. Such an intergenerational expansion of an allele in this range of repeats has not been reported to date. The third homozygous case has late onset bilateral cataracts as the only symptom. She has two minimally expanded alleles (51 and 120 repeats) that showed different intergenerational enlargement during transmission to the next generation.

Adult↗
PubMed1995

Somatic stability in chorionic villi samples and other Huntington fetal tissues.

We have studied different tissues from two affected fetuses with Huntington's disease (HD). In the first case the analysis was performed at 11 weeks of pregnancy; CAG repeats from seven different tissues were compared with the results obtained in the chorionic villi sample (CVS). We found 42 CAG repeats in all samples. In the second case the study was done at 12 weeks; eight tissues (including brain) were studied and compared with the CVS; in all of them, 44 CAG repeats were obtained. Our results show a somatic stability in the different analyzed tissues and suggest that mitotic instability can be a secondary consequence of neuronal degeneration and gliosis. Likewise, our data show great viability in the prenatal diagnosis (PD) of Huntington's disease using samples from any tissue.

Abortion, Therapeutic↗
PubMed1995

Cerebrospinal fluid homovanillic acid is reduced in untreated Huntington's disease.

We measured homovanillic acid (HVA), 5-hydroxy indole acetic acid (5-HIAA), and tryptophan (TP) in cerebrospinal fluid (CSF) of 20 neuroleptic-free patients with Huntington's disease (HD), and compared mean values with those from four control groups including 15 normal individuals, 38 patients with dystonia, 23 untreated patients with Parkinson's disease, and 61 patients with other neurological diseases (ONDs). The mean levels of HVA in the CSF of patients with HD were reduced compared with those from normal controls (p < 0.001), dystonic patients (p < 0.005), individuals with ONDs (p < 0.0001), and even from untreated parkinsonian patients (p < 0.05). 5-HIAA and TP levels in the CSF of patients with HD were not significantly different from those in the CSF of control patients. Our data suggest a reduced dopamine neurotransmission in HD and may account for the bradykinesia observed in our patients.

Adolescent↗
PubMed1995

Genetic instability of microsatellites in hematological neoplasms.

Genetic instability has been recently related to point mutations on genes involved in DNA repair pathway of errors produced during replication. These molecular alterations have been described in hereditary and sporadic colon carcinomas and related tumors. To examine genetic instability on lympho- and myeloproliferative processes, we analyzed the behaviour of 10 microsatellite markers and one VNTR on different chromosomes in 10 patients with non-Hodgkin lymphomas (NHL), one patient with acute lymphoblastic leukemia (ALL) and 10 patients with acute myeloid leukemia (AML). Mobility shifts were found in three of those cases. One of them showed genetic instability for several markers--microsatellites and VNTR- and the other two showed differences for only one marker. As a correlation between point mutations in MSH2 gene and the presence of genetic instability in hereditary non-polyposis colon cancer (HNPCC) and related tumors has been found, we analyzed the sequence of a conversed region of this gene in the cases showing this phenomenon. We only found a polymorphism, previously described, in 669 codon from cDNA.

Burkitt Lymphoma↗
PubMed1995

Polymorphic variations in peripherin-RDS gene in the Spanish population.

The authors report a study of polymorphisms in the peripherin-RDS gene in 21 Spanish families affected with Autosomal Dominant Retinitis Pigmentosa and 56 unrelated normal individuals. We found 3 variants in first exon and nine variants in the third exon in an SSCP analysis, all corresponding to different previously described polymorphisms.

Base Sequence↗
PubMed1994

Trinucleotide (CAG) repeat expansion in chromosomes of Spanish patients with Huntington's disease.

Huntington's disease (HD) is a neurodegenerative and hereditary disease characterized by progressive movement disorders and mental and behavioral abnormalities. The HD gene is an expanding and unstable trinucleotide repeat (CAG repeat sequences). We studied 77 individuals from 38 families with HD in an attempt to obtain information for genetic counselling and differential diagnosis. Our results indicate that individuals with more than 40 repeats will be affected by the disease, whereas those with fewer than 30 will be healthy. There can be some overlap between 30 and 40 repeats, and one should be careful when interpreting these results.

Adolescent↗
PubMed1994

Clozapine disposition covaries with CYP1A2 activity determined by a caffeine test.

In a previous study we showed that the disposition of clozapine after a single oral dose is unrelated to either debrisoquine or S-mephenytoin hydroxylation polymorphism. The same 14 healthy subjects studied in that investigation were given 150 mg of caffeine. The reciprocal of plasma clozapine AUC (0,24), was correlated with an index of the N3-demethylation of caffeine (rs = 0.84; P = 0.0024), used as a measure of cytochrome P4501A2 (CYP1A2) activity. N1- and N7-demethylation indices of caffeine also reflect CYP1A2 activity and were also correlated with clozapine clearance (rs = 0.89 and 0.85; P = 0.0013 and 0.0023; respectively). No significant relationships with xanthine oxidase and N-acetyl transferase activity, also assessed by a caffeine test, were found. This study suggests that clozapine is metabolised by CYP1A2 to a major extent.

Administration, Oral↗