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Biomedical subjects

C Medina

Publications and source records attributed to C Medina.

At least 55 records · Page 3Linked to original sources
PubMed1993

A non-hemorrhagic manifestation of vasa previa: a clinicopathologic case report.

BACKGROUND: The rare entity of vasa previa occurs when fetal vessels lying between the amniotic and chorionic membranes cross the cervical os. This report presents a case that was associated with vessel compression and concomitant adverse effects on fetal hemodynamics. CASE: A 23-year-old nulliparous woman at 36 weeks' gestation developed persistent, progressive severe variable decelerations several hours after spontaneous rupture of the membranes, resulting in a decision to perform a cesarean. At delivery, fetal vessels were noted in the membranes near the cervical os, leading into a marginally inserted cord. The decelerations were attributed to compression of the unprotected umbilical arteries by the fetal head. CONCLUSION: Vasa previa often results in fetal death and may be associated with fetal hemorrhage, but lack of bleeding does not exclude the existence of vasa previa. Altered fetal hemodynamics from varying degrees of vessel compression by the presenting part during labor may result in hypoxia and acidosis. A high index of suspicion is necessary to make the diagnosis and institute proper, timely management.

Adult↗
PubMed1992

[Suitability of the practice of recording only the main health problem in primary care].

OBJECTIVE: To analyse if recording only the main health problem (P) can reflect in a valid way the totality of health problems (P+S) cared for and all the actions generated by a consultation. DESIGN: Using a representative sample of the patients seen at the centre over a three-month period, information on P+S was gathered, P was identified and the actions generated by each one of the problems were recorded. Health problems were codified through CIPSAP-2-D and grouping diagnoses. SITE. General Medicine service in a Primary Care Centre. PATIENTS AND OTHERS PARTICIPANTS: All the General Medical physicians at the Centre took part in the study by collecting data on the consultations established by the sampling. MAIN MEASUREMENTS AND RESULTS: Frequency and order among the first 25 P+S and P problems were compared, as was the percentage of secondary problems encountered. Out of 559 consultations examined, Diabetes, Dislepemia and an irritated? Colon stood out as under-represented. Acute infections of the Upper Respiratory Tract, Conjunctivitis and ??Queratitis were over-represented. As for the activity generated, 83.1% corresponded to P, although there was great variability among the problems according to the percentage of secondary problems according to the percentage of secondary problems. CONCLUSIONS: Recording only the main health problem can be a valid instrument for providing an initial view of problems seen.

Evaluation Studies as Topic↗
PubMed1992

Extremely divergent histone H4 sequence from Trypanosoma cruzi: evolutionary implications.

Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indirect evidence shows that one of these histones, named e, corresponds to H4 in other species. We present evidence that histone e is H4 by sequencing its amino terminal end. The amino terminal of T. cruzi histone H4, unlike that of other H4s examined thus far is not blocked. Moreover, this protein presents two variants. This partial amino acid sequence of T. cruzi histone H4 differs greatly from homologous sequences of human, yeast, or Tetrahymena. Since the conservatism of the core histones (H2A, H2B, H3, and H4) is clearly illustrated by comparative sequence analyses, the data shown here demonstrates that T. cruzi histone H4 is the most divergent reported. Quantitative analysis of the data suggests that the rate of substitutions in the histone H4 amino terminal sequence varies among different lineages. We postulate a slow-down in the evolutionary rate of histone H4 amino terminal domain in the metazoa branch related perhaps to the appearance of a novel function for this domain.

Amino Acid Sequence↗
PubMed1992

Severe Silver-Russell syndrome and translocation (17;20) (q25;q13)

An 8-year-8-month-old girl with Silver-Russell syndrome (SRS) and a paternally inherited balanced t(17;20)(q25;q13) is described. This observation suggests that an SRS gene(s) maps on chromosome 17 or 20 and that the patient phenotype resulted from either unmasking of heterozygosity or genomic imprinting via paternal disomy.

Abnormalities, Multiple↗
PubMed1992

Effects of G-6-PD deficiency, experimentally induced or genetically transmitted, on the sorbitol pathway activity. In vitro and in vivo studies.

Aldose reductase catalyzes the NADPH-linked reduction of hexoses to their respective sugar-alcohols, which are involved in the pathogenesis of "sugar-cataracts". In the lenses, the reaction catalyzed by G-6-PD is the source of NADPH supply blocking sugar-alcohol formation and consequently prevents or delays the onset of "sugar-cataracts". We have investigated the effect of G-6-PD deficiency, either experimentally induced or genetically transmitted, on the sorbitol accumulation in whole cells incubated in high glucose media and on the "sugar-cataracts" formation in a galactosemic rat model. We also screened 31 Negro male adults with diabetes mellitus for red cell G-6-PD deficiency. G-6-PD deficiency produced a significant inhibition on sorbitol accumulation in rat lenses and human red cells incubated in 50 mM glucose. In the galactosemic rat model G-6-PD deficiency experimentally induced with acetaminophen delayed the development of cataracts. Finally, two diabetic individuals were G-6-PD deficient and did not show cataracts whereas cataracts were identified in six other diabetic patients.

Acetaminophen↗
PubMed1990

Hematological and biochemical studies in children with Down syndrome.

Eighty-three children with Down syndrome were submitted to hematological and biochemical studies; 69 normal children were included as controls. The variables analyzed were: HbF, HbA2, serum B12 vitamin (B12), folates, total iron and iron binding capacity, hematic cytology, and the red blood cell enzymes adenosine deaminase (ADA), glucose-6-phosphate dehydrogenase (G6PD) and superoxide dismutase (SOD). The most relevant results were: macrocytosis, normal leucocytes, HbF, B12 and folates, as well as high levels of the enzymes ADA and G6PD. An indirect association between macrocytosis, ADA and G6PD is discussed.

Blood Cell Count↗
PubMed1990

Tandem duplication of proximal 5q.

A 3.5-year-old boy with a de novo tandem duplication 5q11.1----5q15 is reported. Since the physical stigmata of seven liveborn cases with 5q proximal duplications are variable and inconspicuous, a recognizable syndrome could not be delineated. On the contrary, the associated developmental delay seems to be severe in duplications extending into 5q22 and mild in duplications 5q11----q13.

Child, Preschool↗
PubMed1990

Increased adenosine deaminase activity in a patient with cartilage-hair hypoplasia.

A boy aged 9 years presenting short stature and recurrent respiratory-tract infections was studied. The clinical and roentgenological pictures allowed the diagnosis of cartilage-hair hypoplasia (metaphyseal chondrodysplasia, McKusick type). Biochemical studies disclosed a four-fold increase in adenosine deaminase activity, but without evidence of anemia. Immunological evaluation showed abnormal cellular but normal humoral immunity.

Abnormalities, Multiple↗
PubMed1990

[Effect of gene dosage on the glyceraldehyde-3-phosphate dehydrogenase enzyme (GAPD) in partial 12p13.3 pter trisomy].

A family with three brothers presenting 12p trisomy due to an adjacent-1 segregation of a paternal translocation (1;12) (q44;p12.2) is described. The patient's phenotype was compatible with the chromosomal imbalance including the gene dosage effect of the glyceraldehyde-3-phosphate dehydrogenase. The importance of the genetic counseling in these families is stressed.

Abnormalities, Multiple↗
PubMed1990

Photosensitive epilepsy. Electrophysiological aspects.

Intermittent light stimulation (ILS) is more effective to trigger electroencephalographic paroxysms when the patient remains with his eyes closed. In order to evaluate the relative value of the different factors involved, 9 patients of matched age and sex were studied. EEG with ILS, electroretinogram and visual evoked potentials with a flash stimulus were performed under different conditions: open eyes with white, red and blue light, closed eyes and diffusing screen. Analysed in toto, results obtained in the different studies suggest that (a) the factor with greater capability to produce alterations in photosensitive epilepsy is the diffusion of light encompassing a bigger area of the stimulated retina and (b) not only the brain structures but also the retina itself would be involved in the mechanisms underlying the phenomenon of photosensitivity in these patients.

Adolescent↗
PubMed1989

Reduced levels of uridine diphosphate glucose pyrophosphorylase activity in fetal and neonatal human and guinea pig liver.

Uridine diphosphate glucose pyrophosphorylase (UDPGPP) is the first enzyme in the bilirubin conjugation pathway. A study aiming to screen for red blood cell UDPGPP deficiency in newborns with hyperbilirubinemia was carried out. No individuals with severe UDPGPP deficiency were found, however, levels of UDPGPP in premature and at term newborns were lower than in adults. These findings led to the study of UDPGPP in human fetal, neonatal and adult liver, using guinea pig tissues as a parallel control. UDPGPP activities in fetal and neonatal samples were also significantly lower than in adult ones in both species. Therefore, it is postulated that the reduced levels of UDPGPP in fetal and neonatal liver could be a factor which contributes to the pathogenesis of the physiologic jaundice in human newborns.

Animals↗
PubMed1989

De novo dir dup (1)(q3200----4200) in an adult. Further delineation of the pure 1q trisomy syndrome.

An adult male patient with a "de novo" pure trisomy 1q32---q42 was studied. Literature review of 33 cases with 1q trisomy allowed singling out a distinctive phenotype by eliminating clinical features of concomitant aneusomies. It is concluded, however, that the clinical pictures of the "pure" and "impure" 1q trisomies are similar and that the critical segment includes bands q32 and q41.

Adult↗
PubMed1989

Screening for thermostability and electrophoretic red blood cell sorbitol dehydrogenase (E.C.1.1.1.14) variants.

A screening for both thermostability and electrophoretic red blood cell sorbitol dehydrogenase (RBC-SORD) variants in blood donors was performed. SORD activity in standard conditions (unheated samples) in 274 individuals was 198 +/- 38.6 mIU/g Hb. The ratio of enzymatic activity after heating (H) to the activity in controls (C) before heating (H/C ratio) was 0.39 +/- 0.10. H/C ratios minor than 0.1 in 3 out of 274 blood donors and higher than 0.9 in 1 were observed. In 208 individuals, four electrophoretic phenotypes were observed: I) Three bands, named a, b and c, with cathodic mobility in 163 individuals (78.36%); II) Two bands a and c in 25 individuals (12.02%); III) Two bands b and c in 14 (6.73%); and IV) One band, c in 6 (2.88%). Studies carried out to characterize the three bands suggest that they are isozymes of the same locus with the observation of an interchange of the bands as a normal phenomena.

Electrophoresis, Disc↗
PubMed1987

Screening for red blood cell sorbitol dehydrogenase deficiency in patients with diabetes or cataracts.

Quantitative screening for red blood cell sorbitol dehydrogenase (RBC-SORD) deficiency in 111 patients with juvenile onset diabetes, 92 patients with adult onset diabetes, 42 patients with idiopathic cataracts and 192 professional blood donors was performed. A wide variability in RBC-SORD activity in controls and patients was observed. No significant differences in SORD activity either between patients with diabetes and patients with idiopathic cataracts or between diabetics with and without cataracts were observed. Whether or not there were carriers for either amorphous or hypomorphous alleles of the SORD locus in the population studied could not be defined in terms of enzymatic activity levels.

Cataract↗
PubMed1987

The evolution of hexokinases.

Recent advances in the knowledge of the structural and functional aspects of the enzymes catalyzing sugar phosphorylation by ATP are reviewed. Hexokinases may exist, mainly in prokaryotes, as sugar-specific kinases (glucokinase, fructokinase, mannokinase) or as ubiquitous hexose-kinases which are relatively unspecific for the natural hexoses. Enzymes presenting intermediate specificity (e.g. mannofructokinases) have been also described. With a few exceptions, the molecular mass of a variety of hexokinases may be either 25 kDa, 50 kDa or 100 kDa. The smaller hexokinases have been found in some microorganisms whereas the 50 kDa enzymes are found (with only one exception) in most invertebrates and in a particular isozyme from vertebrates (hexokinase D). The 100 kDa enzymes are restricted to vertebrates (hexokinases A, B and C). These facts have led to the speculation that gene duplication events have played an important role in the evolutionary development of the hexokinases from present day organisms. The fact that the 100 kDa hexokinases are allosterically inhibited by the product, glucose 6-P, may indicate that a duplicated active site has evolved to a regulatory binding site. Comparisons of the amino acid sequence of a few peptides from hexokinase C are presented to support the gene duplication hypothesis. Also, partial sequence comparisons of vertebrate hexokinases with the sequences of two hexokinase isozymes from yeast show strong similarities suggesting a rather slow amino acid substitution rate of homologous genes.

Allosteric Regulation↗