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M Carballo

Publications and source records attributed to M Carballo.

At least 73 records · Page 4Linked to original sources
PubMed1995

A point mutation in the RDS-peripherin gene in a Spanish family with central areolar choroidal dystrophy.

The RDS-peripherin gene encodes a photoreceptor-specific protein that is localized in the outer segment disc membranes of both rods and cones. We screened a Spanish family with central areolar choroidal dystrophy for mutations in candidate genes. A base substitution was identified in the RDS-peripherin gene of one patient and DNA sequencing revealed a C-to-T transition in codon 172, arginine being substituted by tryptophan. The mutation was also detected in two asymptomatic family members who showed irregular pigmentation in the retinal pigment epithelium (RPE). The phenotype is similar to other macular dystrophies caused by mutation in the RDS-peripherin gene.

Adult↗
PubMed1995

Retinitis pigmentosa in Spain. The Spanish Multicentric and Multidisciplinary Group for Research into Retinitis Pigmentosa.

Retinitis pigmentosa is a term commonly given to a group of inherited and progressive disorders which affect the photoreceptors of the retina. As part of an ongoing research programme throughout Spain, clinical, epidemiological, and genetic studies have been carried out on these diseases. Here, we report the relative frequencies of the different genetic types in 503 non-syndromic and 89 syndromic RP families of Spanish origin. The most frequent syndromic RP forms were Usher syndrome type 1 (20/89 families = 30%) and Usher syndrome type 2 (44 families = 49%). Among non-syndromic RP forms, 12% were autosomal dominant, 39% autosomal recessive and 4% X-linked. Forty-one percent were isolated or simplex cases and in 4% the genetic type could not be established.

Female↗
PubMed1994

Mutagenic bioassay of certain pharmacological drugs: III. Metronidazole (MTZ).

The genotoxic activity of MTZ was evaluated in vitro with the anaphase-telophase test in a CHO cell line, chromosomal aberration and micronucleus test in lymphocyte cultures, and in vivo using the micronucleus test in mouse bone marrow cells. The In vivo test was performed using clinical trial doses (23, 70 and 160 mg/kg). A significant increase in micronucleated cells (p < 0.02) was observed in the three assayed doses with a linear dose response (r = 0.91). In vitro studies showed a significant increase in the percentage of abnormal anaphases (p < 0.05), in chromosome aberrations (p < 0.01) and in the frequency of micronuclei (p < 0.02) at all the concentrations assayed (0.1, 1 and 10 micrograms/ml). These findings demonstrate the clastogenic effect of this drug which should be taken into account considering its wide human consumption.

Anaphase↗
PubMed1994

Detection of the tetM determinant in Neisseria gonorrhoeae using a non-radioactively labelled oligonucleotide probe.

Three oligonucleotide probes, complementary to tetM sequences, were labelled non-radiometrically using the DIG-oligonucleotide tailing kit and evaluated for their specificity for the detection of plasmid mediated tetracycline resistance in Neisseria gonorrhoeae. Only Probe 3, 5'-GCT CAA CAA TTC TGT TCC AGC-3', was specific for tetM. It hybridized with the tetM-containing 25.2-MDa plasmids from all of the 232 TRNG and the 130 PP/TRNG isolates used in the study. Its sensitivity, determined by dot-blot hybridization, was 0.1 pg of pJ13 plasmid DNA or 10(4) cells. It did not hybridize with the DNA from non-PPNG, CMRNG and tetracycline susceptible isolates from seven other Neisseria species (N. meningitidis, N. subflava, N. cinerea, N. lactamica, N. sicca, N. mucosa, and N. flavescens), Moraxella spp. and Haemophilus influenzae. Probe 3 also hybridized to DNA of three tetracycline resistant P. magnus (MIC = 16 micrograms ml-1) isolates which presumptively carried the tetM determinant. Therefore, probe 3 can be used by reference laboratories as a confirmatory test for TRNG, as well as isolates from other genera containing the tetM determinant.

Base Sequence↗
PubMed1994

Identification of a novel rhodopsin mutation (Met-44-Thr) in a simplex case of retinitis pigmentosa.

Retinitis pigmentosa (RP) is a group of genetically heterogeneous retinal degenerations that can be autosomal dominant (ADRP), autosomal recessive (ARRP), or X-linked. Approximately 30% of ADRP patients show point mutations or small deletions in the rhodopsin gene. However, over 50% of the RP patients are simplex cases (sporadic). Screening for mutations in the rhodopsin gene of 33 patients with simplex RP by denaturing gradient gel electrophoresis (DGGE) was carried out. One patient, with D-type (diffuse) RP and consanguineous parents, showed an altered electrophoretic pattern for the 5' half of exon 1. Direct sequencing revealed a new mutation ATG to ACG in codon 44; this predicts a change of Met-44-Thr in rhodopsin. The position and amino acid substitution suggest that this mutation causes the RP phenotype. Implications for genetic counselling are discussed.

Adolescent↗
PubMed1994

Toxicity identification evaluations for the investigation of fish kills: a case study.

A large fish-kill was observed in the river Tajo during the Spring-Summer of 1991. The mortality was first detected between Aranjuez and Toledo, affecting several fish species. Then it was slowly going downstream, affecting only carp (Cyprinus carpio), reaching the Spanish-Portuguese border several months later. Short-term toxicity tests on Daphnia magna and in vitro cytotoxicity tests on RTG-2 cells were used as toxicity monitoring systems in water samples and different water fractions. The fish kill was associated to the outbreak of infectious diseases, spring viremia of carp and saprolegniosis, related to an increase in the fish's susceptibility due to the presence of a toxic chemical. Bioassay-directed sample fractionations allowed to detect a toxic chemical. HPLC-MS identified the compound as dehydroabietic acid, a resin acid previously described immunotoxic.

Abietanes↗
PubMed1994

AIDS risk reduction and reduced HIV seroconversion among injection drug users in Bangkok.

Human immunodeficiency virus (HIV) seroconversion was studied in a group of 173 injection drug users in Bangkok, Thailand, who had been previously tested for HIV and were interviewed and retested in the fall of 1989. Ten percent of the group had seroconverted. Two factors protected against HIV seroconversion: having stopped sharing injection equipment in response to the acquired immunodeficiency syndrome (AIDS) and having a regular sexual partner. The association between self-reported deliberate risk reduction and reduced HIV seroconversion among persons continuing to inject illicit drugs indicates that injection drug users can change their behavior in response to AIDS and will accurately report on the behavior change, and that the changes can protect against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Pulsed-field gel electrophoresis analysis of higher-order chromatin structures of Zea mays. Highly methylated DNA in the 50 kb chromatin structure.

We have investigated the presence of higher-order chromatin structures in different maize tissues. Taking advantage of the pulsed-field gel electrophoresis technique to analyse large DNA fragments from intact nuclei and cells, we have determined the size distribution of the high-molecular-weight DNA fragments obtained from chromatin degradation by endogenous nucleases in isolated nuclei. Chromatin digestion leads to the appearance of stable DNA fragments of about 50 kb in all the tissues examined, suggesting the folding of DNA in higher-order chromatin domain structures. It has been reported that such chromatin domains are formed by loops of the 30 nm fibers anchored to the nuclear matrix by a complex set of proteins, including DNA topoisomerase II. Treatment of maize protoplasts with the calcium ionophore A23187 and the antitumour drug VM-26, which specifically inhibit the religation of the cleaved DNA in the topoisomerase II reaction, also produces the 50 kb structure. Analysis of the DNA contained in the 50 kb chromatin structure shows a higher degree of methylation than in bulk maize chromosomal DNA. The role of methylated DNA in the chromatin folding is discussed.

Calcimycin↗
PubMed1993

Cellular stress by light and rose bengal in human lymphocytes.

Human lymphocyte cultures were supplemented with 10(-8)-10(-4) M Rose Bengal and irradiated with fluorescent light (Philips 40-W daylight-fluorescent lamp, 380-550 nm) and chromosomal aberrations and catalase and superoxide dismutase activities in the cells were determined. Chromosomal lesions and both enzymatic activities increased additively or synergistically in human lymphocytes after Rose Bengal supplementation and fluorescent light irradiation. Chromosomal lesions (expressed as chromosomal aberrations/cells) were (a) 0.12 +/- 0.03, (b) 0.18 +/- 0.12, (c) 1.58 +/- 0.11 and (d) 3.20 +/- 0.17 in the following conditions: (a) control; (b) after 3 h light irradiation, (c) supplemented with 10(-5) M Rose Bengal and (d) with dye treatment and light irradiation. Superoxide dismutase activity was: (a) 16.5 +/- 1.5; (b) 19.5 +/- 1.2; (c) 29.2 +/- 1.5 and (d) 35.4 +/- 2.1 U/mg protein and catalase activity was: (a) 10.3 +/- 0.5, (b) 12.8 +/- 0.7, (c) 22.4 +/- 0.5 and (d) 27.6 +/- 1.1 U/mg protein in the same experimental conditions. These findings suggest that Rose Bengal supplementation plus fluorescent light irradiation of human lymphocytes lead to the synthesis of superoxide dismutase and catalase in a manner similar to the heat-shock response. A threshold of chromosomal damage (about 2 chromosomal aberrations/cell) is apparently required to activate oxidative stress genes.

Adult↗
PubMed1993

Condom use with primary partners among injecting drug users in Bangkok, Thailand and New York City, United States.

OBJECTIVE: To determine factors associated with likelihood or failure to use condoms with primary sexual partners among injecting drug users (IDU) in two cities. DESIGN AND METHODS: Interviews were conducted with 601 IDU in Bangkok in 1989 and with 957 IDU in New York City in 1990-1991. Subjects were recruited from drug-use treatment programs and a research storefront. Informed consent was obtained and a World Health Organization standardized questionnaire about AIDS risk behaviors administered by a trained interviewer. RESULTS: A substantial minority (37%) of IDU in Bangkok and a majority (55%) of IDU in New York City reported penetrative intercourse (vaginal, anal or oral) with a primary partner in the 6 months before the interview. Of those reporting penetrative intercourse with a primary partner, only 12% in Bangkok and 20% in New York reported that they always used condoms. Parallel bivariate and multiple logistic regression analyses were conducted to distinguish between subjects who reported always using condoms and subjects who reported unsafe sexual activity with primary partners. The same two factor--knowing that one is HIV-seropositive and talking about AIDS with sexual partners--were most strongly associated with always using condoms with primary partners in both cities. CONCLUSIONS: Programs to prevent sexual transmission of HIV among IDU should provide voluntary and confidential/anonymous HIV counseling and testing, and should facilitate discussions of AIDS and sexual transmission of HIV between IDU and their sexual partners. That the same two factors were associated with always using condoms with primary partners among IDU in these two cities suggests that these factors may also be important in other groups at high risk for HIV.

Adult↗
PubMed1992

Genotoxic action of an aqueous extract of Heliotropium curassavicum var. argentinum.

Heliotropium curassavicum var. argentinum is widely employed in gout, rheumatism, neuralgias, arteriosclerotic disorders, muscular algias, phlebitis, varix and other illnesses. In order to analyze the genotoxic effect produced in vitro by this medicinal plant, chromosomal aberrations (CA), mitotic index (MI) and anaphase delay (AD) were studied in the CHO cell line, with and without the addition of S9 mix. Prepared according to the Argentine pharmacopeia 0.1, 1, 10 and 100 micrograms/ml plant decoction (aqueous extract) were assayed. One hundred cells per culture were studied for CA and AD, while MI was calculated for 2000 nuclei. The results revealed a significant increase in the percentage of abnormal metaphases (p less than 0.001) and in total aberrations (p less than 0.001). Both the MI and the AD affected the cell cycle. All results were enhanced by the addition of an S9 fraction. The toxic effect could be associated with pyrrolizidine alkaloids and their N-oxides, which through a process of in vitro metabolism become activated by microsomal oxidation and change into pyrrolic derivatives.

Analysis of Variance↗
PubMed1992

[The molecular genetics of the fragile X syndrome. Its molecular diagnosis by DNA probes].

BACKGROUND: The cytogenetic analysis of the fragile X affected shows a break point in the q27.3 region of chromosome X. However many carrier females and normal carrier males remain refractory to cytogenetic diagnosis. New DNA probes tightly linked to the fragile X point are now available allowing by the familiar RFLP analysis to detect the carrier members. METHODS: Fragile X syndrome affected families were studied cytogenetically and by the use of DNA probes flanking the fragile X region: 1A1, U6.2, VK21 in the distal region and RN1, 4D-8, cX55.7 in the proximal. RESULTS: The haplotypes from two X fragile syndrome affected families were obtained. These families were informatives for all the DNA probes used. The cytogenetic results obtained agree with the previously inheritance pattern reported. CONCLUSIONS: It is very important to detect the normal male carriers. The determination in one family of the origin of the fragile X mutation is possible by the use of DNA probes.

Chromosome Banding↗
PubMed1992

Evaluation of a urease-based confirmatory enzyme-linked immunosorbent assay for diagnosis of Neisseria gonorrhoeae.

A new urease-based enzyme-linked immunosorbent assay utilizing novel monoclonal antibodies was evaluated for the culture confirmation of Neisseria gonorrhoeae, with 270 isolates of N. gonorrhoeae, 56 isolates of diverse Neisseria spp., and 29 Moraxella isolates. The test was highly specific (100.00%) and sensitive (97.83%). No cross-reactions were observed with any of the Neisseria or Moraxella isolates tested. Fifty percent (3 of 6) of the false-negative results were obtained with isolates of serovar IA-4, a serovar rarely encountered in North America.

Antibodies, Monoclonal↗
PubMed1992

HIV testing and sexual behavior among intravenous drug users in Bangkok, Thailand.

The relationships between previous HIV counseling and testing and sexual behavior were examined among injecting drug users in Bangkok. Six hundred one i.v. drug users (IVDUs) were recruited from drug treatment programs in November of 1989. A standardized interview on AIDS risk behavior was administered and a blood sample was collected for HIV testing of the 601 people. Fifty-six percent reported that they had not been previously tested (NPT), 15% had previously tested positive (PT+), and 29% had previously tested negative (PT-). Previous testing was associated with higher levels of safer sex and contraception with primary partners: 56% of the PT+ people with regular partners reported using condoms at least some of the time with that partner, compared with 28% of the PT- and only 20% of the NPT people. Similarly, 89% of the PT+ and 72% of the PT- people, compared with 59% of the NPT people, reported practicing some form of contraception with regular partners. The results strongly support the utility of HIV counseling and testing as a method of reducing heterosexual and perinatal HIV transmission among IVDUs in Bangkok.

AIDS Serodiagnosis↗
PubMed1991

Characterization of topoisomerase I and II activities in nuclear extracts during callogenesis in immature embryos of Zea mays.

We have characterized the topoisomerase I and II activities in nuclear extracts from immature embryos of Zea mays and the effect of the treatment with 2,4-dichlorophenoxyacetic acid (2,4-D) and abscisic acid (ABA). These extracts were shown to be essentially devoid of protease and nuclease activities and they were tested for their ability to relax supercoiled DNA, unknotting P4 DNA and catenate circular duplex DNA under catalytic conditions. Unknotting and catenation reactions are strictly magnesium- and ATP-dependent, but not the relaxation of circular supercoiled DNA allowing the detection of both topoisomerase I and II activities. Two cytotoxic drugs, camptothecin, a plant alkaloid that inhibits eukaryotic topoisomerase I, and epipodophyllotoxin VM-26 (teniposide) that inhibits topoisomerase II, have been assayed in our extracts showing similar inhibitory effects on topoisomerase enzymes. Alkaline phosphatase treatment of nuclear extracts abolishes both topoisomerase activities. Nuclear extracts from embryos treated with 2,4-D showed 200% increase on topoisomerase II activity as compared with untreated ones, but only residual activity was detected in ABA-treated embryos. Nuclear extracts from hormone-treated and untreated embryos showed similar topoisomerase I activity with deviations of less than 25%. These differences are discussed in terms of possible post-translational modifications of the enzymes associated with the increase in proliferation activity of calli.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1991

Risk factors and HIV seropositivity among injecting drug users in Bangkok.

Bangkok experienced an extremely rapid spread of HIV infection among drug injectors in 1987 and 1988. This study examines risk factors for HIV infection and deliberate risk-reduction efforts by drug injectors. Two subsamples of injecting drug users were recruited in November 1989, a group in drug-use treatment (n = 342) and a group new to the treatment system (n = 259). Subjects were interviewed about AIDS risk behavior, and a blood sample was collected for HIV testing. Seroprevalence was 39 and 27% in the in-treatment sample and the new-to-treatment sample, respectively. The in-treatment sample seroprevalence rate is similar to rates observed 6 and 12 months earlier. Three factors were independently associated with HIV infection: subsample, having been in prison, and sharing injection equipment with two or more individuals in the previous 6 months. Deliberate risk reduction was reported by 92% of individuals, with 59% reporting that they had stopped sharing injection equipment. It appears that large-scale risk reduction has greatly slowed HIV transmission among drug injectors in Bangkok.

Adult↗
PubMed1991

Effect of sublethal concentrations of four chemicals on susceptibility of juvenile rainbow trout (Oncorhynchus mykiss) to saprolegniosis.

The effects of sublethal concentrations of a variety of chemicals on the susceptibility of rainbow trout (Oncorhynchus mykiss) juveniles to Saprolegnia parasitica infection was examined. Sublethal concentrations of un-ionized ammonia (0.05 mg/liter) and nitrite (0.12 mg/liter) increased fish susceptibility after 10 days of exposure to the toxin, this increase being higher for ammonia (75% and 20% morbidity) than for nitrite (20% and 0% morbidity, respectively) with inoculum doses of 1.4 x 10(6) and 9.5 x 10(5) zoospores per liter, respectively. Sublethal concentrations of copper (0.05 mg/liter) or cyanide (0.05 mg/liter) did not show enhancement of infection by S. parasitica, even though the toxin exposure was for 21 days and the inoculum doses were higher than those for the experiments with the nitrogen compounds (4 x 10(6) and 3.2 x 10(6) zoospores per liter. However, infections began to appear in control animals.

Ammonia↗