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Biomedical subjects

C Medina

Publications and source records attributed to C Medina.

At least 73 records · Page 4Linked to original sources
PubMed1985

G-6-PD Jalisco and G-6-PD Morelia: two new Mexican variants.

Two new G-6-PD variants designated G-6-PD Jalisco and G-6-PD Morelia were identified in two unrelated Mexican families. An additional G-6-PD variant was found in each family: G-6-PD Trinacria and G-6-PD A-. In both families compound heterozygotes were identified. G-6-PD Jalisco and G-6-PD Morelia belong to Classes 3 and 4, respectively. G-6-PD Morelia is the first variant from its class with a high Km for NADP and a low Ki for NADPH.

Adult↗
PubMed1984

Sorbitol dehydrogenase deficiency in several pig tissues: potential implications for studies of experimental diabetes.

Screening for red blood cell sorbitol dehydrogenase deficiency in 12 different mammalian species was performed. A wide inter-species variability in red cell sorbitol dehydrogenase with a virtually complete deficiency in pigs was observed. Aldose reductase and sorbitol dehydrogenase activities in 12 different pig tissues also were measured. Aldose reductase activity was present in all the tissues studied, whereas organ specificity for sorbitol dehydrogenase was observed. Sorbitol dehydrogenase activity was not detectable in lenses, among other tissues, making the pig a potential model for studies in experimental diabetes, particularly for the investigation of sorbitol dehydrogenase deficiency as a risk factor in the development of cataracts.

Aldehyde Reductase↗
PubMed1984

Doxycycline prophylaxis of travelers' diarrhea in Honduras, an area where resistance to doxycycline is common among enterotoxigenic Escherichia coli.

Daily doxycycline (DX), known to be effective prophylaxis against travelers' diarrhea (TD) in areas of the world where enterotoxigenic Escherichia coli (ETEC) are sensitive to the drug, has not been extensively studied in geographic areas where antibiotic resistance is common. Therefore we studied 44 U.S. Peace Corps Volunteers during their first 5 weeks in Honduras, which is such an area. During the first 3 weeks, volunteers took daily either 100 mg DX or placebo (PL) in a double-blind, randomized fashion. All 22 taking PL developed TD during the first 3 weeks, compared to 7 of 22 (32%) taking DX (P less than 0.001; 68% protection). ETEC were isolated from 39% of episodes of TD. From the PL group, ETEC from 7 of 13 stool samples (54%) were resistant to DX, whereas from the DX group, ETEC from 10 of 11 stool samples were resistant (P less than 0.05). TD that developed in persons taking DX was also found to be less severe, as judged by length of illness (P less than 0.01) and frequency of stools (P less than 0.05). This study demonstrates that DX 1) significantly prevents TD even in areas where antibiotic resistance is common, although it does not prevent TD caused by docycycline -resistant ETEC, and 2) significantly diminishes the severity of illness.

Adult↗
PubMed1983

Paroxysmal spike and wave activity in drowsiness in young children: its relationship to febrile convulsions.

Paroxysmal rhythmic theta waves appearing during early stages of sleep have long been recognized in the EEGs of normal children. A similar pattern with intermixed spikes appears to have a different correlation. We called this pattern 'hypnagogic paroxysmal spike wave activity' or 'hypnagogic PSW.' This investigation was designed to test whether there exists a relationship between hypnagogic PSW, febrile convulsions (FC) and age. We selected 3 cohorts of children: G-1 or normal control consisted of 94 children selected with the following criteria: complete normal neurodevelopmental examination and no personal or family history of FC, epilepsy, or other neurological disorder. They all had one EEG obtained without drug induction showing a clear sequence of awake-drowsy-sleep-arousal-awake states. G-2 or pathological control group consisted of 126 children selected at random, referred to the Division of Neurophysiology at the Children's Hospital Medical Center for any problem excluding FC. At least one EEG met the criteria mentioned above. G-3 or FC group consisted of 375 children in whom the very first seizure was associated with fever without evidence of other causes for the convulsion. All met the same EEG criteria of G-1 and G-2. The medical record of 169 children of this group (40 with hypnagogic PSW and 129 without hypnagogic PSW) were reviewed.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1983

A fluorimetric method for red blood cell sorbitol dehydrogenase activity.

A new fluorimetric method for the quantification of red blood cell (RBC) sorbitol dehydrogenase is described. It is based on the oxidation of sorbitol to fructose, in presence of NAD+, catalysed by the RBC-sorbitol dehydrogenase. The quantity of NADH formed is then measured in a filter fluorimeter. Comparison with an indirect spectrophotometric assay yielded good correlation; however, the present method offers several advantages: it is more rapid, simple and inexpensive. It should be useful to screen for sorbitol dehydrogenase deficiency in large numbers of individuals, particularly patients with diabetes or cataracts.

Erythrocytes↗
PubMed1983

On the screening for inborn errors of galactose metabolism.

The utility of a simplified diagram of procedures for screening specimens for genetic disorders in galactose metabolism is stressed. Both, early detection and institution of the dietetic treatment are imperative since these inherited disorders have clinical and pathological consequences which can be very severe in galactose-1-phosphate uridyltransferase and uridine diphosphate galactose-4-epimerase deficiencies.

Carbohydrate Epimerases↗
PubMed1982

Red blood cell sorbitol dehydrogenase deficiency in a family with cataracts.

Sorbitol dehydrogenase (SORD) was quantitatively assayed in a family in which four out of five brothers and their father had bilateral cataracts. Three sibs (two of them with cataracts) and both their father and paternal grandfather had SORD activity of about 25% of the reference values; of the other two affected sibs one had about 50% and the other had 75%; the mother and two paternal uncles had about 75%. These results do not define a clear cataract-SORD deficiency etiopathogenic relationship, nevertheless, they strongly suggest activity polymorphism in human red cell SORD, which would be highly relevant not only to the study of cataracts but of other major complications in diabetes.

Cataract↗
PubMed1982

Screening for inborn errors of the erythrocyte metabolism in Northwestern Mexico.

Data from a program aiming to the detection of inborn errors of the erythrocyte metabolism (IEEM) in Northwestern Mexican populations are presented. 5,998 individuals were studied and divided in 5 groups: a) 1,022 full-term newborns without jaundice; b) 872 randomly selected full-term newborns; c) 3,243 full-term newborns with jaundice; d) 54 patients with hemolytic anemia, and e) 807 professional blood donors. In groups b, c and d screening for 9 out of 14 IEEM clearly associated with hemolysis was carried out by means of enzymatic fluorescent procedures. In groups a and e only G-6-PD deficiency was investigated. The results suggest that 0.34%, 0.77%, 24% and 0.37% of the individuals from groups b, c, d and e, respectively, have an IEEM. The frequency of G-6-PD deficiency was 0, 0.43%, 1.1%, 30.3% and 0.37% in the males from groups a, b, c, d and e, respectively. The IEEM as a cause of neonatal jaundice seem not to be a public health problem in the studied populations. Systematic screening for: 1) G-6-PD deficiency in newborns with jaundice and 2) IEEM in patients with hemolysis, is recommended.

Anemia, Hemolytic↗
PubMed1981

Biweekly prophylactic doxycycline for travelers' diarrhea.

A double-blind study to determine the efficacy of biweekly oral doxycycline in the prevention of travelers' diarrhea was conducted among 46 Peace Corps volunteers during their first six weeks in Honduras. The volunteers took either 100 mg of doxycycline per dose or a placebo for three weeks and were observed for an additional three weeks. There was no significant difference in the number of persons with travelers' diarrhea in the two groups (eight of 24 in the doxycycline group and 10 of 22 in the placebo group) in the three weeks when the drug was taken. However, significantly fewer episodes (P less than 0.05) of travelers' diarrhea occurred in the doxycycline group than in the placebo group at the end of the second, third, and fourth weeks. Enterotoxigenic Escherichia coli (ETEC) was the most common pathogen identified. ETEC from 13 (62%) of 21 stool samples were resistant to doxycycline. Biweekly doxycycline was only marginally effective in preventing travelers' diarrhea and did not prevent diarrhea secondary to doxycycline-resistant ETEC.

Adult↗
PubMed1981

A simple screening procedure for glucose phosphate isomerase, phosphofructokinase, aldolase and glyceraldehyde-3-phosphate dehydrogenase deficiencies.

A simple screening procedure for the detection of glucose-phosphate isomerase (GPI), phosphofructokinase (PFK), aldolase (AL) and glyceraldehyde-3-phosphate dehydrogenase (GAPD) deficiencies in blood, is described. These enzymes catalyze the second, third, fourth, and sixth reactions in the Embden-Meyerhof pathway. The procedure is based on the conversion of glucose-6-phosphate to 1,3-diphosphoglycerate (1,3-DPG) which is catalyzed by the sequential action of the GPI, PFK, AL and GAPD. The presence of the enzyme activities is visually estimated by the reduction of NAD+ (non-fluorescent) to NADH (fluorescent) which occurs when 1,3-DPG is formed. Absence of fluorescence indicates the deficiency of anyone of the four enzymes, which are specified by using separately the PFK, AL and GAPD respective substrates.

Anemia, Hemolytic, Congenital↗
PubMed1981

A screening test for phosphoglycerate kinase deficiency.

A simple screening test for the detection of X-linked recessive phosphoglycerate kinase (PGK) deficiency in blood is described. It is based on the conversion of 3-phosphoglycerate to 1,3-diphosphoglycerate catalyzed by the PGK whose activity is visually estimated by the oxidation of NADH (fluorescent) to NAD+ (non-fluorescent) in a coupled reaction with the enzyme glyceraldehyde 3-phosphate dehydrogenase. The disappearance of fluorescence indicates PGK activity in the sample, while the contrary could be due to PGK deficiency. The utility of this test for the study of males with hereditary hemolytic anemia is stressed.

Fluorescence↗
PubMed1981

Detection of inborn errors of metabolism in 1,117 patients studied because of suspected inherited disease.

Results of screening tests for the detection of inborn errors of metabolism in 1,117 consecutive patients are reported in this work; patients came for a second consultation to the Departamento de Genética, Centro Médico de Occidente, IMSS. Simple qualitative test were made that revealed the presence of abnormal metabolites (amino-acids, sugars, organic acids and mucopolysaccharides) in urine and blood as well as identification tests for variant proteins. Results were positive in 138 patients and test for confirmation and/or specificity were made in all patients; in 35 the following diagnosis and incidence were established: classic galactosemia, 2; glucose-6-phosphate dehydrogenase deficiency, 20; essential pentosuria, 1; hyperphenylalaninemia, 5; blue diaper syndrome, 1; cistinuria 1, and type 1 mucopolysaccharidosis, 5.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

Post-pubertal female psychosexual orientation in incomplete male pseudohermaphroditism type 2 (5 alpha-reductase deficiency).

An 18 year-old 46,XY female-reared patient with incomplete male pseudohermaphroditism type 2 (5 alpha-reductase deficiency) was studied. She had a male habitus, Wolffian ducts derivatives, normal testes and small phallus; there were no Mullerian duct derivatives nor gynaecomastia. Clinical and genetic data were typical of the diagnosis which was corroborated by endocrinological studies. Normal LH, FSH, testosterone (T) and oestradiol and decreased dihydrotestosterone (DHT) plasma levels before and after hCG administration were found; the T:DHT ratio was highly increased. The histopathological studies of a testis biopsy showed a normal adult male pattern, and the meiotic chromosomes were interpreted as normal. After assessment of her psychosexual orientation, successful surgical and medical therapy to maintain and improve her femaleness was effectuated. The post-pubertal gender role switch commonly observed in these female-reared patients is discussed.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1980

A simple screening procedure for adenylate kinase, hexokinase and glucose-6-phosphate dehydrogenase deficiencies.

A simple screening procedure for the detection of adenilate kinase (AK), hexokinase (Hx) or glucose-6-phosphate dehydrogenase (G6PD) deficiencies in blood, is described. It consists of two assays : in the first, the ATP formed by blood AK is coupled to Hx and G6PD, and in the second, the glucose-6-phosphate formed by blood Hx is coupled to G6PD. The enzyme activities are visually estimated by the reduction of NADP+ (non-fluorescent) to NADH (fluorescent). The appearance of fluorescence in the first assay indicates that the three enzyme activities are present. The absence of fluorescence could be due to the deficiency of any one of the three enzymes; in this case the second assay used in combination with the Beutler's screening test for G6PD permits the detection of the specific enzymatic deficiency.

Adenylate Kinase↗
PubMed1980

A simple assay for uridine diphosphate galactose 4-epimerase activity.

A simple fluorescent test for the activity of blood uridine diphosphate galactose 4-epimerase which converts uridine diphosphate galactose to uridine diphosphate glucose is described. The enzyme activity is visually estimated by to reduction of NAD+ (non fluorescent) to NADH (fluorescent) in a coupled reaction with uridine diphosphate glucose dehydrogenase. The appearance of fluorescence indicates that epimerase activity is present in the sample. The usefulness of this test in newborn screening programs for inborn errors of galactose metabolism is stressed.

Carbohydrate Epimerases↗
PubMed1979

A simple rapid fluorescent assay for adenosine deaminase activity.

A simple, rapid (2 hours), fluorescent test for the activity of blood adenosine deaminase (ADA) is described. The test which can be performed on both heparinized and dried blood, is based on the conversion of adenosine to inosine and ammonium in the presence of ADA. The enzyme activity is visually estimated by the oxidation of NADH (fluorescent) to NAD+ (non-fluorescent) in a coupled reaction with glutamate dehydrogenase. The disappearance of fluorescence indicates ADA activity in the sample. The advantages are discussed of the use of this test for the study of the autosomal recessive severe combined immunodeficiency.

Adenosine Deaminase↗
PubMed1979

Hemolytic anemia caused by glucose-6-phosphate dehydrogenase deficiency.

Results are reported concerning quantitation of glucose -6- phosphate dehydrogenase (G6PD) enzyme activity where in one of the members of a family a clinical diagnosis of acute hemolytic anemia due to G6PD deficiency had been established. In the propositus, G6PD levels were found to be less than 10 per cent thus confirming diagnosis; the same enzymatic deficiency was identified in one of the siblings without a history of hematologic pathology and in a maternal cousin with a history of neonatal jaundice as well as two obliged carriers. Electrophoretical enzyme phenotype was similar to A variant in three affected males. Advantages of prevention and medical care possible with early diagnosis of G6PD deficiency are discussed.

Adolescent↗