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M Ramon

Publications and source records attributed to M Ramon.

13 recordsLinked to original sources
PubMed2002

HLA polymorphism in a Majorcan population of Jewish descent: comparison with Majorca, Minorca, Ibiza (Balearic Islands) and other Jewish communities.

'Chueta' was the name given to the Catholic descendants of Jewish victims of the last Spanish Inquisition process in Majorca Island in the western Mediterranean. We have studied the allele distribution of HLA-A, -B, -Cw, -DRB1 and -DQB1 loci of 103 random, healthy, unrelated individuals belonging to the ancient Majorcan Jewish community, known locally as Chuetas, and 589 individuals from the Balearic population selected because of their typical Balearic - Majorca, Minorca or Ibiza - lineages and according to their ancestor's place of birth. Our aim was to establish the genetic relationship between Majorcan Chuetas, and Balearic and other Jewish and Mediterranean populations. Our results have shown that, to a remarkable extent, they have retained their biological identity, with a unique pattern, in terms of gene and haplotype frequencies, separate from the other populations of Majorca. The Chuetas were found to be more related to Moroccan and Libyan Jews than other Majorcans. Characteristic Jewish haplotypes, A26-B38-DRB1*13, A24-B38-DRB1*11, A1-B52-DRB1*15/16, were found in our study. Some peculiarities were observed in the distribution of common haplotypes among the three main Balearic Islands. The Ibizan population was genetically different from the other Balearic populations, with a high frequency of some haplotypes, for example, A29-Cw*16-B44-DRB1*07-DQB1*03; A1-Cw*07-B8-DRB1*03-DQB1*02. We also found a new haplotype, A25-Cw*12-B39-DRB1*11-DQB1*03(3.5%), in Ibizans and a more limited variability in the HLA alleles that were expressed, perhaps because of genetic isolation. The genetic diversity of the populations from Majorca and Minorca were similar and more related to the mainland Spanish population.

Alleles↗
PubMed1999

The genetic structure of Drosophila subobscura populations from the Islands of Majorca and Minorca (Balearic Islands, Spain) based on allozymes and mitochondrial DNA.

The genetic structure of seven populations of Drosophila subobscura from different locations on Majorca and Minorca (Balearic Islands, Spain) was studied using two types of markers: allozyme and mitochondrial DNA restriction analyses. Both markers showed congruent results. In the allozyme data, when the Acph-1 locus was excluded from the joint FST statistics, only three out of 21 comparisons were statistically significant, lending support to the hypothesis of low genetic differentiation. The mtDNA restriction analyses showed two haplotypes at a high frequency (more than 40% each), irrespective of the location considered, and a number of endemic haplotypes at very low frequencies (not higher than 2% each). The analyses of the genetic structure yielded a pattern similar to the allozymes. The cytonuclear disequilibrium analyses showed the difficulty of detecting cytonuclear associations in natural populations because they are mainly transient.

Alleles↗
PubMed1998

Atrichia with papular lesions maps to 8p in the region containing the human hairless gene.

Atrichia with papular lesions (APL) (OMIM 209500) is a hereditary form of alopecia. Hair loss occurs soon after birth and is followed years later by the development of a diffuse papular eruption. Its mode of transmission is still uncertain. A related but clinically distinct form of alopecia, known as alopecia universalis (OMIM 203655), has recently been found to be associated with a mutation in the human hairless gene. The present report describes the largest consanguineous kindred of APL reported to date and provides strong evidence for autosomal recessive inheritance of this rare disorder. On the basis of a linkage analysis of this kindred using six microsatellite markers spanning the human hairless gene region, we found that the APL locus maps to chromosome region 8p12 in a 5 cM interval between marker D8S560 and marker D8S1739. A maximum lodscore of 3.7 was obtained with marker D8S1786, at a recombination fraction of 0. Our results suggest phenotypic variability at the hairless locus although they do not rule out the existence of a gene cluster associated with hair disorders in the same region.

Alopecia↗
PubMed1998

Mitochondrial DNA: a tool for populational genetics studies.

Mitochondria are cellular organelles that have the function of the oxidative phosphorilation and the formation of ATP. In humans, the mtDNA is a double-stranded, circular, covalent closed molecule of 16.5 kb. The mtDNA is inherited as a haploid from the mother and heteroplasmy has been found rarely. From a populational perspective, it could be considered as a system of small, sexually isolated demes, or clonal lineages, with an evolutionary rate 5 to 10 times faster than the nuclear genome. All these characteristics make this molecule ideal for evolutionary studies. We present two applications of this molecule in genetical studies. One of these is referred to the Balearic Islands populations, Majorca, Minorca, Ibiza, and Chuetas. The other example is the populational dynamics of the different mitochondrial haplotypes in Drosophila subobscura. We also discuss the importance of nuclear markers to complete these studies as well as the study of the Y chromosome to compensate the bias produced by the study of only the mtDNA.

Animals↗
PubMed1997

Delayed postburn blisters: an immunohistochemical and ultrastructural study.

This study was performed in an attempt to further elucidate the pathogenesis of delayed postburn blistering. Two cases were studied ultrastructurally and immunohistochemically, 1 with blisters on the recipient site of autologous split-thickness skin grafts and the other on the donor site. Ultrastructurally, the basement membrane was on the roof of the blisters in both cases, except for a single small blister in the first case where it was on the dermal floor. In the blister roofs, the basement membrane showed small or marked segments of discontinuity. In the adjacent non-blistered healed skin, the basement membrane was usually continuous, and anchoring fibrils were present. Immunoperoxidase staining on frozen sections, using antibodies to laminin, laminin 5, collagen IV, and collagen VII, showed a mostly continuous linear pattern in the adjacent non-blistered skin, which often became discontinuous near the blisters and markedly discontinuous in the blister roofs. In the blister floors, weakly stained linear or granular deposits of some of these components were sometimes also present. The results of this study support discontinuity of the basement membrane as the main anomaly in delayed postburn blistering. Disturbance in the reassembly or local breakdown of the basement membrane components might be the underlying defect.

Adult↗
PubMed1996

An immunohistochemical study of p53 protein expression in classical Kaposi's sarcoma.

The present study was performed to determine the frequency of p53 protein immunoreactivity in classical Kaposi's sarcoma (KS) as a whole and in relation to the histological subtypes which are considered to correspond to the developmental stages of the tumor. The accumulation of p53 protein was studied immunohistochemically using monoclonal antibody BP53-12 on formalin-fixed paraffin-embedded sections of 36 KS lesions, of which 14 were classified histologically as early type and 22 as spindle-cell or mixed type. No positive immunoreactivity was detected in any of the 14 early-type lesions. Among the 22 spindle-cell and mixed variants, positive staining was detected in 5-10% of the tumor cells in one lesion, 1-5% of the cells in six lesions, and in < 1% of the cells in two lesions. These very small percentages of positively stained cells in less than half of the cases of the spindle-cell and mixed variants do not support a significant role for p53 in tumor progression and evolution in KS.

Adult↗
PubMed1992

Human pharmacokinetics of N-L-leucyl-doxorubicin, a new anthracycline derivative, and its correlation with clinical toxicities.

A pharmacokinetic study of N-L-leucyl-doxorubicin, a new derivative of doxorubicin, has been undertaken during a phase I trial in 19 patients with advanced cancer after intravenous bolus administration at doses ranging from 30 to 240 mg/m2. The pharmacokinetics of N-L-leucyl-doxorubicin was linear with a total body clearance of 41.3 +/- 25.7 L/hr/m2. N-L-leucyl-doxorubicin was extensively metabolized into doxorubicin, which appeared in plasma immediately after N-L-leucyl-doxorubicin infusion. The mean molar doxorubicin/N-L-leucyl-doxorubicin area under the curve (AUC) ratio was 0.49 +/- 0.22 and was independent of the administered dose. A relationship has been established between the doxorubicin AUC (r = 0.74; p less than 0.001) and the surviving factor in white blood cell counts. Other toxic side effects (thrombocytopenia or stomatitis) did not correlate with any pharmacokinetic parameter. These findings suggest that the degree of metabolization of N-L-leucyl-doxorubicin into doxorubicin may be responsible for the toxicity, that is, N-L-leucyl-doxorubicin may simply represent a pro-drug for doxorubicin.

Dose-Response Relationship, Drug↗
PubMed1983

Population screening for glucose-6-phosphate dehydrogenase deficiency on the Baleares.

Two thousand people on the Isles of the Baleares were screened for glucose-6-phosphate dehydrogenase deficiency using a commercially available kit. Among the thousand males tested, five were found deficient; of the thousand women, one had low enzyme activity according to this test. Diagnosis of glucose-6-phosphate dehydrogenase deficiency could be verified using hair follicle analysis on mailed hair samples. The same technique also allowed heterozygotes to be identified unequivocally.

Female↗
PubMed1982

Human hair follicles may be used for population screening of heterozygotes of glucose-6-phosphate dehydrogenase deficiency.

The carrier status for glucose-6-phosphate dehydrogenase deficiency can still be detected with the use of hair follicles after a period up to 10-14 days after plucking, even under conditions of temperature and humidity that are encountered in tropical countries, where the disease is most common. Furthermore, it is shown that the hair colour or age of the donor has no influence on the enzyme activity. As a consequence, the hair follicle is indeed suitable for screening in rural areas since mailing to existing medical centres is possible.

Adult↗
PubMedDate not supplied

[Nyctohemeral variations of cyclosporine administered orally in renal transplant patients].

The circadian intraindividual variations of cyclosporin blood concentrations were studied in nine renal transplant patients at steady state. The cyclosporin was administrated orally twice a day (9 a.m. and 21 p.m.). Blood concentrations were analysed by H.P.L.C. AUC = area under the drug concentration versus time curve, Cmax = maximum blood concentration, Cmin = minimum blood concentration, Tmax = Time to maximum concentration. Statistical analysis (t, Wilcoxon) shows: AUC, Cmax and Tmax are not significantly modified, Cmin (21) less than Cmin (9) (p less than 0.02). This phenomenon seems to be rather a cyclosporin metabolism variation than an absorption alteration.

Administration, Oral↗