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Biomedical subjects

M Santos

Publications and source records attributed to M Santos.

At least 145 records · Page 8Linked to original sources
PubMed1994

Antiphospholipid antibodies in predicting adverse pregnancy outcome. A prospective study.

OBJECTIVE: To determine if the presence of antiphospholipid antibody (aPL) in healthy pregnant women is associated with adverse pregnancy outcome, including 1) intrauterine fetal loss, 2) maternal pregnancy complications, 3) low birth weight, and 4) low 5-minute Apgar scores. DESIGN: Prospective cohort study in women with normal pregnancies. SETTING: Obstetrics clinic at the University of Colorado Health Sciences Center. PATIENTS: Eligible patients included 451 low-risk, nulliparous pregnant women who came to the obstetrics clinic before 25 weeks gestation; 408 were enrolled and 389 had blood drawn at the first prenatal visit and completed clinical follow-up. MEASUREMENTS: Blood for six aPL measures was drawn at the first prenatal visit and for 239 patients at delivery. RESULTS: Ninety-five patients (24.4%) had elevated aPL levels by one or more measures at the first prenatal visit: 15.8% of the aPL-positive and 6.5% of the aPL-negative patients experienced fetal loss (relative risk, 2.44; 95% CI, 1.29 to 4.62). However, an elevated IgG anticardiolipin antibody level at the first prenatal visit was the only aPL measurement that was significantly associated with fetal loss (relative risk, 3.5; CI, 1.56 to 8.07). Adjustment for confounding variables decreased the relative risk of aPL for fetal loss slightly, but the difference remained statistically significant. Neither a positive aPL result at the initial visit nor a positive result at delivery was associated with maternal complications of pregnancy, low birth weight, or low Apgar scores. CONCLUSIONS: Patients with elevated aPL levels at their initial prenatal visit had an increase in fetal loss but no increase in maternal pregnancy complications, low birth weight, or low Apgar scores. Immunoglobulin G anticardiolipin antibody was the only single test of aPL significantly associated with fetal loss.

Abortion, Spontaneous↗
PubMed1994

Direct screening of a mitochondrial DNA deletion valuable for Amerindian evolutionary research.

A rapid, simple restriction isotyping method is described for the direct screening of a previously characterized Amerindian mitochondrial DNA (mtDNA) marker consisting of a 6-bp "Huetar" deletion. In a sample of 31 maternally non-related Chibchan Amerindian Bribri from Costa Rica, this deletion was present in 74%, arguing for the usefulness of this private polymorphism for Amerindian taxonomic research.

Base Sequence↗
PubMed1994

Gene-environment interaction for body size and larval density in Drosophila melanogaster: an investigation of effects on development time, thorax length and adult sex ratio.

We measured the effect of larval density on thorax length, development time, sex ratio and a measure of total fitness, using strains of Drosophila melanogaster artificially selected for increased thorax length, control lines otherwise cultured in an identical way, and the base stock from which the lines had been derived. We used the addition experimental design (Mather & Caligari, 1981). No genotype-environment interaction was observed when comparing the reduction in thorax length of 'large' and 'control' lines with increasing larval density for any culture series, i.e. rank ordering of genotypes and additive genetic variances remained the same in all the environments tested. In contrast, the reduction in thorax length for the base stock as density increased was proportionally smaller than that of the 'large' and 'control' lines. Development time increased more rapidly with larval density in the 'large' lines than in the 'controls' or base stock. Sex ratio was unaffected by larval density but thorax length and the development time of females were more affected than those of males by increasing larval density. The estimate of total fitness showed clear evidence of gene-environment interaction for the effect of body size on fitness, with genetically large individuals at an increasing disadvantage with increasing larval density.

Animals↗
PubMed1994

Stereotactic radiosurgery of the foramen magnum region and upper neck lesions: technique modification.

A modification of the stereotactic radiosurgical procedure to permit treatment of lesions in the foramen magnum and upper cervical regions is described. The modification consists of placing the frontal pins of the stereotactic head ring in the zigoma bone, with no changes in the position of the occipital pins, so the final BRW head ring is oblique to the orbito-meatal plane. In this new position there is room enough in the posterior part of the guide for the support scrubs. This is unhampered by the patient's shoulders and the lesion is far enough to permit setting the axial coordinate sufficiently above the head ring plane.

Foramen Magnum↗
PubMed1994

[Cytogenetic studies of Chilean children with acute lymphoblastic leukemia].

Acute lymphoblastic leukemia (ALL) is the most frequent childhood cancer. The leukemic cells of ALL patients show several well defined numeric and structural chromosomal abnormalities which are universally known for its prognostic implications. We studied a group of 44 children with ALL, to investigate the incidence of chromosome aberrations in ALL, its lymphocyte lineage and some clinical feature associations, and the finding of non previously described aberrations. A high proportion of patients (79.5%) showed chromosomal abnormalities. Most of them had a pseudodiploid karyotype (46 chromosomes), characterized mainly by a translocation. In relation to chromosome number, 27% of them were hyperdiploid with more than 50; 9% hyperdiploid between 47-50 and 7% hypodiploid (less than 46). Among structural aberrations found, were the following recurrent translocations: t (1; 19), t (4; 11), t (9; 22) in 6.8%, 9.1% and 2.3% of cases respectively, all related to an early B immunophenotype. Other translocations found, compromised regions 7q22, 9p21 - 24. Two new translocations in ALL were found: t (1; 5)(q23; q33), apparently balanced, and t (13; 21)(q14; q22), unbalanced. Other recurrent structural changes found were: deletion (6q), (7q), (9p), (11q), (12p), inversion (3q), isochromosome (7q), maker chromosomes and double minutes. The distribution of chromosome abnormalities in this group of patients was in agreement with previous reports from other investigators.

Adolescent↗
PubMed1994

mtDNA variation in the Chibcha Amerindian Huetar from Costa Rica.

The genetic variation in a Chibcha-speaking Amerindian tribe from lower Central America, the Huetar, was analyzed using nucleotide sequences of the hypervariable segments of the mitochondrial DNA (mtDNA) control region, the frequencies of 10 Amerindian-specific mtDNA haplotypes, and the regional distribution of private protein polymorphisms. The sequencing of 713 base pairs (bp) in the control regions of 27 individuals revealed 11 distinct lineages. These were defined by 24 variable sites and a 6-bp deletion between nucleotide pairs (np) 106 and 111. The 6-bp deletion is a new mtDNA marker that will be valuable for Amerindian taxonomic research. Control region sequences and mtDNA haplotype analyses reveal that Huetar mtDNAs are distributed in "Amerindian clusters" A, B, and D. A maximum-likelihood phylogenetic tree suggests a single origin for the 6-bp Huetar deletion in the sample. mtDNA haplotype analysis and the presence of previously characterized private protein variants (PEPA*F, TF*DCHI, and the absence of DI*A) show that the Huetar harbor polymorphisms of considerable antiquity, suggesting an early divergence from the regional founder gene pool for this population. The data also reflect a drastic constriction in population size, an evolutionary event with a proposed central effect on Huetar genetic structure.

Base Sequence↗
PubMed1993

Biliary lipid secretion: immunolocalization and identification of a protein associated with lamellar cholesterol carriers in supersaturated rat and human bile.

Feeding a 0.5% diosgenin plus 0.02% simvastatin diet to rats increases biliary cholesterol concentration and saturation to levels generally found in human native supersaturated bile. By using preparative ultracentrifugation, gel filtration chromatography, and electron microscopy, we isolated, purified, and identified lamellar structures (unilamellar vesicles and multilamellae) as a major biliary cholesterol transport in supersaturated human and rat bile. It was estimated that more than 60% of biliary cholesterol is transported in these lamellar carriers, which were identified by transmission electron microscopy as unilamellar vesicles and multilamellar bodies within bile canaliculi of rats with cholesterol supersaturated bile. By SDS-PAGE, a characteristic and constant protein profile was found associated to the purified lamellar carriers. One of these proteins, a 130-kDa protein, was isolated from human biliary lamellae and used for preparation of a rabbit polyclonal antibody, which cross-reacted with the homologous rat protein. By Western blotting, it was established that the purified low density fraction of bile-Metrizamide gradients, containing lamellae, was enriched with the 130-kDa protein. The 130-kDa protein was characteristically detected at the canalicular membrane by Western blotting of hepatic subcellular fractions and by immunohistochemistry of rat and human liver biopsies. Amino acid sequencing of the amino terminus of the 130-kDa protein demonstrated a complete identity with aminopeptidase N, a canalicular transmembrane hydrophobic glycoprotein. These studies show that biliary lipids may acquire an ordered multilamellar structure that is present in the canaliculi of rats with supersaturated bile. These biliary lamellae are similar to lamellar bodies and surfactant-like material frequently found in other epithelia, suggesting common biogenetic, structural, and functional properties. The identification of aminopeptidase N associated with biliary lamellae is consistent with the involvement of the canalicular membrane in the secretory mechanism of biliary lipids.

Amino Acid Sequence↗
PubMed1993

[Pure autonomic failure].

We present the case of a 64-year-old woman who, in the past 5 years, complained of constipation/diarrhea, hyposudoresis, xerostomia and xerophthalmia, dysuria and orthostatic hypotension. Cardiovascular reflexes analysis revealed sympathetic and parasympathetic failure. Norepinephrine was markedly reduced, both lying and after tilt. Norepinephrine infusion determined a significant rise in blood pressure, allowing the diagnosis of denervation hypersensitivity. The diagnosis of pure autonomic failure was made. Therapy with 9 alpha fludrocortisone and metoclopramide was initiated with marked and sustained symptomatic effect.

Autonomic Nervous System Diseases↗
PubMed1992

Presence and coding properties of 2'-O-methyl-5-carbamoylmethyluridine (ncm5Um) in the wobble position of the anticodon of tRNA(Leu) (U*AA) from brewer's yeast.

The unknown modified nucleoside U* has been isolated by enzymatic and HPLC protocols from tRNA(Leu) (U*AA) recently discovered in brewer's yeast. The pure U* nucleoside has been characterized by electron impact mass spectroscopy, and comparison of its chromatographic and UV-absorption properties with those of appropriate synthetic compounds. The structure of U* was established as 2'-O-methyl-5-carbamoylmethyluridine (ncm5Um). The yeast tRNA(Leu) (U*AA) is the only tRNA so far sequenced which has been shown to contain ncm5Um. The location of such a modified uridine at the first position of the anticodon restricts the decoding property to A of the leucine UUA codon.

Anticodon↗
PubMed1992

Treatment of children with chronic hepatitis C with recombinant interferon-alpha: a pilot study.

Twelve children with chronic non-A, non-B hepatitis were entered in a pilot trial of recombinant interferon-alpha. Although all the children had hepatitis C virus RNA in serum, only five had antibodies against this virus. Children received 3 MU/m2 body surface area interferon-alpha 3 times/wk for 6 mo; they were followed for 24 mo, including the therapy period. One child was dropped from the study, so the results are from the 11 children who completed the study. At the end of the therapy period, 36% of the children had normal ALT levels; this percentage increased to 90% at mo 15 of follow-up. Thereafter, relapse occurred in five children; thus ALT normalization was observed in 5 of 11 children at the 24th month. Moreover, two different ALT patterns were found: HCV antibody-negative children had significant peaks of ALT levels with respect to the basal samples (p less than 0.05) until the third month of the therapy; these levels later decreased. In contrast, HCV antibody-positive children had slight fluctuations of ALT until normal levels were reached. At the end of treatment, three children had HCV RNA; one demonstrated a rebound in ALT levels. Finally, histological activity had decreased significantly in the second liver biopsy specimen in all children. In summary, interferon treatment in children with chronic hepatitis C may be helpful, although these results should be confirmed in controlled trials.

Adolescent↗
PubMed1992

Correlation between cytogenetic and molecular analysis of t(14;18) in follicular lymphomas.

A comparison between cytogenetic and molecular results of t(14;18) has been performed in 12 patients with follicular lymphomas: five nodular and seven diffuse. Ten cases showed cytogenetic alterations with different markers, including a 14q+ in eight: in four it was the result of a t(14;18). Molecular analysis by Southern blotting with bcl2 probes from major and minor cluster regions, and PCR with primers from major and minor regions showed differences versus the cytogenetic results. The correlation found between cytogenetic and molecular results suggests other factors, such as geographical differences or different pathogenetic mechanisms, more than methodologic aspects, to explain the different frequencies of this marker among countries.

Adult↗