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Biomedical subjects

B Suarez

Publications and source records attributed to B Suarez.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Non surgical reduction of false aneurysms of the femoral artery with echo-Doppler control].

The authors report four cases of repair of femoral pseudoaneurysms under pulsed (1 case) and colour Doppler (3 cases) guidance, performed between January and October 1992 and compare the results with previously published reports of this new technique. They obtained 3 complete successes without complications and 1 failure with complications and a contraindication to the method. A review of the literature and the personal experience of the authors are described. This effective and usually complication-free technique should be proposed as an alternative to surgery. It should be undertaken as early as possible and remains a long and fastidious procedure poorly adapted to present nomenclature of medical procedures. It should be systematically proposed in cases of pseudo-aneurysms complicating the implantation of endoarterial prostheses.

Aged↗
PubMed1993

Resistance to methicillin and virulence of Staphylococcus aureus strains in bacteriemic cancer patients.

OBJECTIVE: To estimate the relation between resistance to methicillin and virulence in strains of Staph. aureus by estimating the survival at day 30. DESIGN: Case control analysis. SETTING: Inpatients at a major Cancer Referral Center. PATIENTS: 21 patients with methicillin-resistant Staph. aureus (MRSA) bactaeremia and 45 patients with methicillin-susceptible Staph. aureus (MSSA) bactaeremia, all treated with vancomycin. MEASUREMENTS AND MAIN RESULTS: Fewer MRSA than MSSA patients were neutropenic (p = 0.04), but more MRSA patients were hospitalized in intensive care units (p = 0.03), had had surgical episodes (p = 0.06). MRSA patients also had more microbiological samples cultured (p = 0.007). The outcome of the bacteriemic episodes in 14 MRSA and 14 MSSA patients matched for these four factors showed that blood cultures from MRSA patients remained positive significantly longer (p = 0.04), but that survival and length of hospital stay were not significantly different. CONCLUSIONS: These results do not indicate that methicillin-resistance in Staph. aureus is associated with increased virulence.

Adolescent↗
PubMed1987

Unfractionated human thymocytes have a lower proliferative capacity than CD3-4-8- ones but have a similar capacity for expression of interleukin 2 receptors and production of interleukin 2.

CD3-4-8- and unfractionated thymocytes were compared for their capacity to proliferate, to express interleukin 2 (IL-2) receptor, and to secret IL-2. Phorbol ester and Ca2+ ionophore were used as mitogens. CD3-4-8- thymocytes responded vigorously when stimulated with phorbol ester in the presence of IL-2 or in combination with Ca2+ ionophore. In contrast, unfractionated thymocytes responded weakly when stimulated with either of these mitogens. Surprisingly, however, the stimulation of these populations with either phorbol ester plus IL-2 or phorbol ester plus ionophore induced a high and similar level of IL-2 receptor expression in both thymocyte populations. A similar level of IL-2 secretion in both populations was also obtained when they were stimulated with a combination of phorbol ester plus ionophore. These results suggest that during the maturation process, the majority of thymocytes lose their capacity to be activated by some mitogens, although they maintain their capacity to secrete IL-2 and to express the IL-2 receptor.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1985

Correlation of serum immunoglobulin subclass concentrations with antibody responses of children to immunization with Haemophilus influenzae type b polysaccharide-pertussis vaccine.

Children less than 24 months of age respond poorly to immunization with the capsular polysaccharide of Haemophilus influenzae type b. Because human antibodies to polysaccharide antigens are relatively restricted to IgG2, a late-maturing subclass, we examined the relationship between serum subclass concentrations and anticapsular antibody responses of 41 healthy children, 9 to 38 months of age, following immunization with type b polysaccharide mixed with pertussis vaccine. Both total and IgG anticapsular antibody responses correlated significantly with preimmune serum concentrations of IgG2 but not with those if IgG1. This correlation was age dependent, however, and after the effect of age was removed by partial correlation, the correlation between anticapsular antibody responses and serum IgG2 concentrations was no longer significant. These findings indicate that the ability to respond to this vaccine coincides with maturation of the ability to secrete immunoglobulin of the IgG2 subclass; however, individual variation in IgG2 that is independent of age does not correlate with antibody response to the type b polysaccharide.

Age Factors↗
PubMed1985

Relation of age, race, and allotype to immunoglobulin subclass concentrations.

Concentrations of IgG1, IgG2, and total IgG were measured by a solid phase radioimmunoassay in sera from 36 healthy adults and 114 healthy children. As expected, IgG2 and total IgG had a positive correlation with age in children. In addition to age, several other factors were associated with significant differences in serum subclass concentrations. Female children had higher concentrations of IgG1 than males, and black subjects had significantly higher concentrations of IgG1, IgG2, and total IgG than whites. Although Km(1) and Gm(23) immunoglobulin allotypes had no relation to subclass concentrations when tested as single factors, the Km(1) allotype interacted significantly with race so that Km(1)-positive black children had higher IgG2 concentrations than other subjects. Our findings may explain, in part, recent observations of an association of the Km(1) allotype with altered immune responses of blacks to certain vaccines containing bacterial polysaccharides. In addition, our data indicate the need to control factors such as sex, race, and allotype in studies of subclass concentrations or immune responses.

Adolescent↗
PubMed1984

Response to immunization with Haemophilus influenzae type b polysaccharide-pertussis vaccine and risk of Haemophilus meningitis in children with the Km(1) immunoglobulin allotype.

In experimental animals, immune responses to certain antigens are regulated by immunoglobulin allotype-linked genes. In an effort to detect such genes in humans, we examined the antibody responses of 74 healthy children with different Km(1) or Gm(23) allotypes to a Haemophilus influenzae type b vaccine (type b polysaccharide capsule-pertussis vaccine). The anticapsular antibody responses of black or white children with the Km(1) allotype were 4.6- to 9.5-fold higher than those of children who lacked this determinant (P less than 0.004). No significant differences were found in antibody response with respect to the Gm(23) allotype. The frequencies of Km(1) and Gm(23) also were examined in 170 patients with Haemophilus meningitis, 71 patients with epiglottitis, and 173 control children. Km(1) was detected less frequently in black patients with meningitis (38%) than in those with epiglottitis (81%, P less than 0.002) or in controls (66%, P less than 0.0007). The relative risk of meningitis thus was 3.2-fold lower among black children with the Km(1) allotype than in those who lacked this allotype (odds ratio = 0.3, 95% confidence interval 0.2 to 0.6). However, the risk of meningitis was not decreased in white children with the Km(1) allotype (odds ratio = 1.0). There were no significant differences in the frequency of Gm(23) among the patient groups and controls. The Km(1) allotype but not the Gm(23) thus defines a subpopulation of children of both races who are high responders to this vaccine, and black children but not white children with the Km(1) allotype are at decreased risk of developing Haemophilus meningitis. These data indicate that in blacks, genes associated with Km(1) may affect immune response to a prototype type b Haemophilus vaccine, and perhaps interact with another factor related to race to affect susceptibility to Haemophilus meningitis.

Antibodies, Bacterial↗
PubMed1983

Siblings of patients with Haemophilus meningitis have impaired anticapsular antibody responses to Haemophilus vaccine.

Siblings of patients with type b Haemophilus influenzae meningitis are at increased risk of developing Haemophilus disease. We immunized 26 healthy siblings and 25 control subjects using a vaccine containing the type b polysaccharide capsule (10 micrograms PRP) and pertussis vaccine (4 opacity units) (Lederle Laboratories) to determine whether siblings of patients with Haemophilus meningitis had an impaired antibody response to PRP. Using two intramuscular injections one month apart, we found that the siblings had a lower response to PRP. One month after the second injection, 12 of 24 of the siblings had serum concentrations of anticapsular (PRP) antibody thought to be sufficient to confer protection against Haemophilus disease (greater than or equal to 300 ng/ml), compared with 19 of 24 of the control children tested (50% vs 79%, P = 0.035 by chi-square analysis). In comparison with the normal controls, the siblings produced significantly less IgG anti-PRP antibody but similar amounts of IgM. The impaired responsiveness to PRP was most evident among the 16 children born after their sibling had meningitis and who were not known to have been exposed to type b Haemophilus infection previously. These data indicate that siblings of some patients with type b Haemophilus meningitis have reduced ability to form IgG anti-PRP antibody, which may be associated with increased susceptibility to Haemophilus disease.

Antibodies, Bacterial↗
PubMed1982

Power of the affected-sib-pair method to defect disease susceptibility loci of small effect: an application to multiple sclerosis.

The distribution of marker locus identity-by-descent scores in affected sib pairs provides a powerful tool for detecting the presence of a linked non-Mendelian disease susceptibility locus. This basic approach is here extended to include a trio of sibs. A special type of sib trio consisting of two affected and one unaffected sib is investigated. It is shown that compared to affected-sib-pairs, trios with the above configuration are less efficient in detecting the presence of a linked disease susceptibility locus. When the generalized two-allele single locus model is fitted to sib pairs affected with multiple sclerosis, an estimate of the recombination fraction of 0.21 between the putative disease susceptibility locus and the HLA complex is obtained. However, this transmission model is deemed inadequate since a recombination fraction this large is inconsistent with the variety of HLA associations observed at the population level.

Chromosome Mapping↗
PubMed1980

Conditional concordance in monozygotic twins.

Twin concordance rates are usually reported without reference to the number of parents affected, apparently because the simple demonstration that monozygotic (MZ) twins are more concordant than are dizygotic (DZ) twins is the goal of most twin studies. Depending on the underlying mechanism, however, twin concordance rates can vary widely when conditioned on the number of parents affected. For the generalized single-locus model it is shown that conditional concordance rates in monozygotic twins, along with an estimate of the disorder's prevalence in the population, uniquely specify the underlying parameters of this important model. Knowledge of the exact parameter set is essential for competent genetic counseling.

Female↗
PubMed1979

Is juvenile diabetes determined by a single gene closely linked to HLA?

The transmission behavior of insulin-dependent juvenile diabetes mellitus (JDM) has been studied with respect to its frequency in the relatives of JDM probands and its possible linkage to the HLA complex. Mathematical analysis shows that under a single locus hypothesis a very restricted range of incidence rates is possible in the full siblings of probands once the concordance rate in monozygotic (MZ) twins is specified. Specifically, for a given population prevalence of the disease, high concordance rates in MZ twins require high incidence rates in siblings, and low rates require low incidence rates, if a single locus model is th be valid. Moreover, if these rates do conform to a single locus model, then they give additional information about possible linkage between the purported JDM susceptibility gene and the HLA complex. By using observations on the identity by descent scores at the HLA locus of sibling pairs, both of whom are affected with JDM, it is shown that tight linkage of a disease susceptibility locus is possible only when the MZ twin and sibling incidence rates are low, whereas high rates support loose linkage. If the single locus model is rejected, then an alternative hypothesis, involving epistasis between a JDM susceptibility locus and genes in (or close to) the HLA complex can be suggested as a mechanism whereby JDM would appear to be linked to HLA within families while maintaining an association with HLA at the population level.

Diabetes Mellitus, Type 1↗
PubMed1978

A note on the essential parameters of the two-allele autosomal locus model.

A resolution of the parameter problem for the two-allele autosomal locus (TAAL) model has been presented. It was shown that three are four essential parameters which describe the model, by examination of the joint probability for sibs with specified parental phenotypes. This equation together with previously derived prevalence relationships uniquely specifices all parameters of the model except for the singular case VA = 0.

Alleles↗
PubMed1978

A robust method for the detection of linkage in familial disease.

A nonparametric method for the detection of critical genes associated with familial disease was presented. The method involves the detection of deviations from expected identity by descent distributions at polymorphic marker loci for affected sib pairs. The method thus avoids the difficulties arising from incomplete penetrance, variable age of onset and other complications present in other forms of linkage analysis. The theoretical properties of method were worked out in detail for two important cases -- that of an incompletely penetrant recessive or incompletely penetrant dominant critical autosomal gene linked to a codominant marker locus. An easily implementable decision rule for the detection of linkage was proposed, and its operating characteristics for a variety of alternative hypothesis were obtained.

Genes, Dominant↗
PubMedDate not supplied

Interactive effect of genes associated with immunoglobulin allotypes and HLA specificities on susceptibility to Haemophilus influenzae disease.

Genes associated with immunoglobulin (Ig) allotype determinants are important in regulation of immune responses to bacterial polysaccharides. Furthermore, loci associated with Ig allotypes have been reported to interact with those associated with the major histocompatibility complex and affect susceptibility to certain diseases. In the present study we determined the frequencies of certain Gm phenotypes in patients with Haemophilus meningitis or epiglottitis and in controls. HLA-A, -B and -DR specificities had previously been determined in the majority of these subjects. Although no Ig phenotype was associated with increased or decreased relative risk of disease, the frequencies of several combinations of HLA specificities and Ig phenotypes were significantly different from those of controls. Thus, for subjects with the Gm phenotype (1, 3, 17; 23; 5, 13, 21), the risk of Haemophilus meningitis or epiglottitis was lower in individuals with HLA-B5 than in those without this specificity (odds ratio less than 0.1, P less than 0.004). In contrast, for subjects with the closely related Gm phenotype differing only by the absence of Gm(23), (1, 3, 17; ; 5, 13, 21), the risk of disease was higher in those with HLA-DR3 than in individuals who lacked DR3 (odds ratio = 11.0, P = 0.02). Although the present data require confirmation in an independent sample, they suggest that complex interactions between genes at two independent loci controlling HLA and Ig allotypes, respectively, may affect susceptibility to Haemophilus disease.

Child↗