Biomedical subjects
Publications and source records attributed to R de Pablo.
We have isolated the complete coding region of HLA-B*39 from a Spanish Caucasoid, using a new PCR primer for its 5' untranslated region. The cDNA matched partial genomic sequences of B*3924, an allele whose distribution appears to be restricted to Mediterranean and Arabian Caucasoids. A single amino acid change exclusive to B*3924 (threonine-98) distinguishes it from B*3903.
The novel HLA-B*3704 allele was identified by polymerase chain reaction with sequence specific oligoneucletides (PCR-SSO) in a Spanish Caucasoid individual whose T-lymphocytes showed an ambiguous HLA-B phenotype. The nucleotide sequence of B*3704 was determined after reverse transcription-polymerase chain reaction (RT-PCR) amplification and molecular cloning of its complete coding region. B*3704 differs from B*3701 by a single nucleotide replacement that induces the substitution of histidine for tyrosine 171. Residue 171 is located in the alpha-helix of the alpha-2 domain, lining the A pocket of the peptide-binding site. Therefore, the His171 substitution seen in HLA-B*3704 is likely to affect its antigen-presenting properties and is probably responsible for the differentiated serological phenotype of this allele in comparison with B*3701.
The identification of a growing number of novel Mendelian disorders and private mutations in the Roma (Gypsies) points to their unique genetic heritage. Linguistic evidence suggests that they are of diverse Indian origins. Their social structure within Europe resembles that of the jatis of India, where the endogamous group, often defined by profession, is the primary unit. Genetic studies have reported dramatic differences in the frequencies of mutations and neutral polymorphisms in different Romani populations. However, these studies have not resolved ambiguities regarding the origins and relatedness of Romani populations. In this study, we examine the genetic structure of 14 well-defined Romani populations. Y-chromosome and mtDNA markers of different mutability were analyzed in a total of 275 individuals. Asian Y-chromosome haplogroup VI-68, defined by a mutation at the M82 locus, was present in all 14 populations and accounted for 44.8% of Romani Y chromosomes. Asian mtDNA-haplogroup M was also identified in all Romani populations and accounted for 26.5% of female lineages in the sample. Limited diversity within these two haplogroups, measured by the variation at eight short-tandem-repeat loci for the Y chromosome, and sequencing of the HVS1 for the mtDNA are consistent with a small group of founders splitting from a single ethnic population in the Indian subcontinent. Principal-components analysis and analysis of molecular variance indicate that genetic structure in extant endogamous Romani populations has been shaped by genetic drift and differential admixture and correlates with the migrational history of the Roma in Europe. By contrast, social organization and professional group divisions appear to be the product of a more recent restitution of the caste system of India.
We have studied the allele distribution of DRB1, DQB1 and DPB1 loci in 80 unrelated Gypsies living in different eastern areas of the Andalusian province of Granada (southern Spain). The frequency distribution of HLA class II alleles and the genetic distance of Andalusian Gypsies from several Caucasian populations indicate a marked similarity - but not total - of the former with the Gypsy population previously studied in Madrid (central Spain), which suggests that both groups migrated together out of India. In terms of genetic distance, both Gypsy groups are more like the Czech Gypsies and the Northern Indian groups than their neighbouring Caucasian non-Gypsy populations. In summary our data support the hypothesis of a common anthropological origin of all three European Gypsy groups, which probably split up after their arrival in Europe.
Unrelated Bubi, native to the island of Bioko (Equatorial Guinea), were previously typed by low-resolution polymerase chain reaction using sequence-specific primers (PCR-SSP) and serology for HLA-A, -B and -C. HLA-B*44 was found frequently and associated with Cw*07. We have studied the HLA subtypes of 20 B*44pos/Cw*07pos Bubi individuals. HLA-B and -C were typed by sequencing exons 2 and 3. To distinguish the alleles Cw*1701/02/03, Cw*07011/012/06 and Cw*1801/02 additional sequencing of exon 1 or 5 was performed. All 20 B*44pos/Cw*07pos individuals of the Bubi population were typed Cw*0706 positive. Nineteen of them carried the B*44032 allele and one B*4407. In addition, 19 B*44neg/ Cw*07pos Bubi individuals were typed for HLA-C and none of them proved Cw*0706 positive. To determine whether the association between Cw*0706 and B*44032 was limited to the Bubi, 19 individuals from Dutch Caucasian families were typed in which B44 and Cw7 segregated on one haplotype. None of these individuals showed the presence of B*44032 or Cw*0706. The haplotypes found in the Dutch Caucasians were B*4402-Cw*0704, B*44031-Cw*07011 and B*44031-Cw*0702. The present observation indicates a strong association between B*44032 and Cw*0706 in the Bubi population.
The distribution of HLA-A, -B, -C, -DRB1 and -DQB1 alleles in the Peruvian population was studied and compared with those of other populations in order to provide further information about their anthropological origin. Our data are consistent with the Mestizo character of this population. In terms of genetic distance Peruvians are closest to Bolivians, which is in agreement with the geographical location and the cultural and anthropological background of the two human groups. Several HLA-B alleles originally described in genetically isolated Amerindian tribes are also present in the sample studied here. This fact and the reported finding of these alleles in several Amerindian groups suggests that they were present in the first wave of humans that populated South America (Paleoindians) before they split to give rise to the different South American tribes.
STUDY OBJECTIVES: To compare in-hospital mortality of patients with ARDS ventilated with either pressure-controlled ventilation (PCV) or volume-controlled ventilation (VCV) with a square-wave inspiratory flow. DESIGN: : Multicenter and randomized trial. SETTING: Twelve medical-surgical ICUs located in tertiary-care hospitals. PATIENTS: Seventy-nine patients having ARDS, as defined by the American-European Consensus Conference. INTERVENTIONS: Patients were randomly assigned to be ventilated with either PCV (n = 37) or VCV (n = 42). In both instances, inspiratory plateau pressure was limited to < or = 35 cm H(2)O. MEASUREMENTS AND RESULTS: There were no significant differences among the studied groups at the moment of randomization, although there was a trend toward greater renal failure in patients assigned to VCV. Ventilatory settings and blood gases did not significantly differ over time between the two groups. Patients in the VCV group had both a significantly higher in-hospital mortality rate than those in the PCV group (78% vs 51%, respectively) and a higher number of extrapulmonary organ failures (median, 4 vs 2, respectively). The development of renal failure during the study period was also significantly more frequent among VCV patients (64% vs 32%, respectively). Multivariate analysis showed that factors independently associated with an increased mortality rate were the presence of two or more extrapulmonary organ failures (odds ratio [OR], 4.61; 95% confidence interval [CI], 1.38 to 15.40) and acute renal failure (OR, 3.96; 95% CI, 1.10 to 14.28) but not the ventilatory mode used. CONCLUSIONS: The increased number of extrapulmonary organ failures developed in patients of the VCV group was strongly associated with a higher mortality rate. The development of organ failures was probably not related to the ventilatory mode.
A novel HLA-Cw*15 allele , Cw*1508, has been found in the Peruvian population. This new allele, initially detected as a polymerase chain reaction with sequence-specific primers (PCR-SSP) variant, shows greatest similarity to Cw*1502. The nucleotide sequence of Cw*1508 only differs from that of Cw*1502 at position 539; this change determines the replacement of Leu by Arg 156 in Cw*1508.
The duration of spontaneous breathing trials before extubation has been set at 2 h in research studies, but the optimal duration is not known. We conducted a prospective, multicenter study involving 526 ventilator-supported patients considered ready for weaning, to compare clinical outcomes for trials of spontaneous breathing with target durations of 30 and 120 min. Of the 270 and 256 patients in the 30- and 120-min trial groups, respectively, 237 (87.8%) and 216 (84.8%), respectively, completed the trial without distress and were extubated (p = 0.32); 32 (13.5%) and 29 (13.4%), respectively, of these patients required reintubation within 48 h. The percentage of patients who remained extubated for 48 h after a spontaneous breathing trial did not differ in the 30- and 120-min trial groups (75.9% versus 73.0%, respectively, p = 0.43). The 30- and 120-min trial groups had similar within-unit mortality rates (13 and 9%, respectively) and in-hospital mortality rates (19 and 18%, respectively). Reintubation was required in 61 (13.5%) patients, and these patients had a higher mortality (20 of 61, 32.8%) than did patients who tolerated extubation (18 of 392, 4.6%) (p < 0.001). Neither measurements of respiratory frequency, heart rate, systolic blood pressure, and oxygen saturation during the trial, nor other functional measurements before the trial discriminated between patients who required reintubation from those who tolerated extubation. In conclusion, after a first trial of spontaneous breathing, successful extubation was achieved equally effectively with trials targeted to last 30 and 120 min.
A previously unknown HLA-C variant of the Cw*12 group was identified by PCR-SSP from genomic DNA of cell NDS-JD. Molecular cloning and nucleotide sequence analysis permitted the characterization of the complete coding region of this new allele, Cw*12042. The new variant differs from the recently reported Cw*12041 by two silent changes at exons 2 and 3, and from Cw*1203 by coding changes at codons 77 and 80. Cw*1203 (Ser-Asn) and Cw*12042 (Asn-Lys) constitute the second known example of HLA-C alleles only differing at the KIR-related dimorphism of residues 77-80. The new allele is associated in cell NDS-JD with the haplotype HLA-A*2403, Cw*12042, B*51, DRB1*1502, DRB5*0102, DQB1*0601, possibly related from the evolutionary aspect to the ancestral haplotype A*2402, Cw*1202, B*5201, DRB1*1502, DRB5*0102, DQB1*0601.
Genotyping of the HLA-C locus by PCR-SSP in Behçet's disease patients from southern Spain reveals a statistically significant association with Cw*1602 (OR 20.15, corrected p < 0.05). This is an uncommon allele absent from the healthy control group, which seems to confer higher relative risk than B51 in this study (OR 1.85). Stratified frequencies do not show statistically significant differences but suggest that the Cw*1602-B51 haplotype could be the main HLA marker of Behçet's disease in the analyzed population.
An almost complete and bidirectional association exists between HLA-Cw*17 and the HLA-B antigens B41 and B42. Serological and molecular analysis of an individual in which HLA-B*4101 was identified in the absence of Cw*17 provides experimental evidence to prove a previously proposed hypothesis predicting that alloantisera classified as "B41+B42" are instead specific reagents for HLA-Cw*17.
Medium chain acyl-CoA dehydrogenase (MCAD) deficiency is recognized as the most common hereditary defect of fatty acid oxidation in humans. Death is the outcome of the first attack in about 25% of cases. A point mutation (A to G [corrected] at position 985) of the MCAD gene represents more than 90% of alleles causing MCAD deficiency. The frequency of this allelic variant exhibits considerable geographical variations. In Spain, where the few diagnosed patients are mostly of Gypsy origin, the frequency is low as occurs in other Southern European countries (1 heterozygote among 200 individuals). Here we have analyzed the frequency of the G985 allele among Spanish gypsies. Heterozygotes were detected at a frequency of 1/17, with a 95% confidence interval ranging from 1/11 to 1/39. This represents the highest G985 rate described so far and calls for preventive measures, such as selective screening in this population.
Genotyping of the HLA-C locus by PCR-SSP has previously shown 100% association of B41 and B42 with a new allelic variant. Partial sequencing studies (exons 2-4) demonstrated that this PCR-SSP variant corresponded to the new allele Cw*1701. In this study we have characterized the whole coding region of Cw*1701 from a Bubi individual of Equatorial Guinea. Our results partially confirm the previously reported sequence and reveal that Cw*1701 has many new polymorphisms at several exons, including a 18-bp insertion in exon 5. Cw*1701 is thus a most unusual HLA-C molecule defining a third allelic lineage of this locus.
The HLA-Cw*1801 specificity, a Cw7/Cw4 hybrid allele, has recently been described in association with B*8101 (formerly B"DT"). In this study, the new Cw*1802 variant, differing from Cw*1801 at exon 5, is found associated with B*5703 in Bubi individuals from Equatorial Guinea. Confirmatory complete coding regions of B*5703 and B*3910 are also reported.
Two previously reported PCR-SSP variants of the HLA-B locus, B51GAC and B45v, were investigated by RT-PCR cloning and nucleotide sequence analysis of their complete coding regions. They have been shown to correspond to the new alleles B*5108 and B*5002, both of which differ from the common B*5101 and B*5001 subtypes, respectively, by amino acid replacements at their alpha-2 domain alpha-helices. The primary structure of B*5002, intermediate between those of B*4501 and B*5001, raises further concern about the current classification of B*45 as a B12 rather than as a B*50 subtype.
We determined the HLA frequency distribution in a sample of 100 Bubi individuals born on the island of Bioko (Equatorial Guinea). HLA-A, -B and -C typing was performed by serology and PCR-SSP. DRB1/3/4/5, DQB1 and DQA1 alleles were determined by PCR-SSOP. The HLA allele distribution of this population group resembles those found in other Bantu-speaking groups; however, the higher frequency of A30, A32, B44, DRB1*1301 in the Bubi with respect to other Bantu groups and the absence of DR4 deserve special mention. The cloning and sequencing of class I and II genes in this population allowed the description of five new allelic variants: B*4407, Cw*0706, Cw*1801, Cw*1802 and DQB1*0612 and five confirmatory sequences: B*3910, B*5703, B*8101, Cw*1203 and Cw*1701. The following new HLA-C,B haplotypes have been found in Bubi: Cw*08-B*57, Cw*18-B*57, Cw*0302-B*53, Cw*07-B*53 and Cw*1601-B*63. The most frequent seven-locus haplotype is: A*30-Cw*17-B*42-DRB1*1102-DRB3*0202-DQA1*05-DQB1 *0301. In terms of genetic distance, the Bubi are closer to other Bantu groups than to West African populations.
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