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Biomedical subjects

R Youlton

Publications and source records attributed to R Youlton.

At least 19 recordsLinked to original sources
PubMed1990

[Growth patterns in height and weight in children aged 0 to 17 years and cranial circumference in children aged 0 to 2 years from medium-high and high socioeconomic status in Santiago. Comparison with growth in children from medium-low and low status in the Northern area of Santiago].

The results of a semi-longitudinal growth study of children from an upper socioeconomic stratum (SES), 0 to 17 years of age, are reported. Medical records of 6,000 boys and girls who were seen in the pediatric outpatient department of Clínica Las Condes, Santiago, during the period January 1983-December 1987 were reviewed. Data of height (H), weight (W) and head circumference (HC) of 4,800 normal children were obtained; the totals of recorded measurements were 13,000 for H, 13,000 for W and 5,800 for HC. The information is presented in 13 Tables and 32 Figures and it was compared to that from a longitudinal study in children of lower SES in Northern Metropolitan Santiago. Females of the upper stratum are taller at all ages, but W for H ratio is higher in girls of the low stratum. H and W for age values are higher in boys of the upper stratum, but W for H ratio is similar in both socioeconomic groups. The age of peak height velocity is the same in both groups for both sexes. We conclude that the stated differences in growth and weight gain between these two socioeconomic groups are better explained by genetic than by nutritional factors.

Adolescent↗
PubMed1989

[Cytogenetic study of acute and chronic leukemias].

From 1983 to 1987 we studied 30 patients with leukemia searching for chromosomal alterations. Cytogenetic studies of bone marrow showed an abnormal karyotype in 19 (67%). Seven out of 14 cases of acute leukemia presented different chromosomic alterations. The Philadelphia chromosome was found in 11 patients with chronic myeloid leukemia and 3 patients with chronic lymphatic leukemia; a Pseudo-Philadelphia chromosome was present in one patient, this being the first such finding in Chile. Thus, the karyotype is a valuable complementary study not only in chronic myeloid leukemia but also in chronic lymphatic leukemia and the acute lymphoblastic and non-lymphoblastic varieties.

Adolescent↗
PubMed1989

[Idiopathic hypoparathyroidism, a syndrome with various clinical expressions: analysis of 10 cases].

We report 10 patients with primary hypoparathyroidism. Age at onset varied from 7 months to 52 years (mean 28); 7 were female. Diagnosis was established at a mean of 4.1 years after the appearance of clinical manifestations. Unexplained hypocalcemia (mean 5.3 mg/dl) and hyperphosphatemia (mean 6.4 mg/dl) were present in all patients. Prevalent symptoms included tetany (9 patients), seizures (5) and hypocalcemic cataracts (4). Clinical manifestations may be grouped into 5 types 1) tetany; 2) seizures; 3) other neurologic disorders (basal ganglia calcification, pseudotumor of the brain, ataxia, nystagmus, hypertonus, paresis); 4) disorders of the lens including fully developed cataracts and 5) skin alterations like psoriasis and others. Some of these run on acute course (seizures, tetany), others a subacute one (skin alterations) while others are rather chronic (cataract and other neurologic disorders). Seizures and electroencephalographic disorders predominate in younger patients while tetany is more prevalent in older subjects.

Adult↗
PubMedDate not supplied

[Genetic study in twins].

During the period june 1987-January 1988, 35 consecutive pairs of twins born at two maternity hospitals in the northern area of Santiago were studied to search evidence of genetic or other factors which could eventually favour twinning. Sixteen of these pairs were considered to be monozygotic (MZ) after studying five blood group systems (ABO, Rh, MNSs, Duffy and Kidd) applying the method of Smith and Penrose. Maternal age was higher in dizygotic twins (DZ) than in the MZ group (average 30.1 yrs. v/s 26.8 yrs. respectively (p < 0.05). Family history of twinning was positive in 73% of the MZ and in 82% of the DZ twins. The Duffy and Kidd systems were not in Hardy-Weinberg equilibrium due to a deficit of heterozygotes in MZ as well as in DZ twins. There was a significant increase in MS and Ms haplotypes in both groups of twins respect to the Chilean general population (p = 0.01). These results suggest the presence of a genetic determinant that favors the production of twinning of DZ as well as MZ type. A larger number of cases will be required to test this hypothesis.

Blood Group Antigens↗
PubMedDate not supplied

[Clinical and cytogenetic analysis of 257 cases of Down's syndrome].

Among 257 patients with clinical diagnosis of Down's syndrome, 56.4% of male gender, in whom cytogenetic studies were performed, 14 (5.4%) had normal karyotypes and 243 (94.6%) had 21 trisomy. Of these last, 225 (92.6%) had free 21 trisomy, 10 (4.1%) showed mosaics, 8 (3.3%) had translocations. Average maternal age of this sample was significantly higher than that of patients attending the same maternity wards (32.14 vs. 24.85 years) and 41% of Down syndrome's patients came from mothers aged 36 years or more, even though only 9.7% of this country's deliveries proceed from women of that age group. As to seasonal occurrence, the proportions of births which happened in summer almost doubled that of winter (33.1% vs. 16.9%). The frequency of characteristic clinical signs of Down's syndrome was somewhat different than that described for patients from some other countries, for instance: epicanthus, short neck and widening of the space between 1st. and 2nd. toe were more frequent, while Brushfield's spots, depressed occiput, dental anomalies, heart malformations and fissured tongue seemed less frequent. The importance of cytogenetic studies for diagnosis and genetic counseling is stressed.

Chile↗