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Biomedical subjects

M Jimenez

Publications and source records attributed to M Jimenez.

At least 109 records · Page 6Linked to original sources
PubMed1989

Normal or early development of puberty despite gonadal damage in children treated for acute lymphoblastic leukemia.

To determine the timing of pubertal development and the frequency of gonadal dysfunction in children who survive acute lymphoblastic leukemia, we assessed pubertal status and the plasma levels of sex steroids, gonadotropin, and inhibin in 45 children (20 girls and 25 boys) who had received combination chemotherapy along with 24 Gy of irradiation to the cranium (modified LSA2L2 protocol). We also reexamined testicular biopsy specimens, obtained at the time of the cessation of chemotherapy, for the presence of germ cells. Germ-cell damage, indicated by marked elevations in the plasma level of follicle-stimulating hormone (P less than 0.001 for the comparison with normal children), was evident in both sexes and was confirmed in the boys by the absence of germ cells in the testicular biopsy specimens and by the small size of the testes for pubic-hair stage. Only 44 percent of the pubertal girls had measurable plasma inhibin levels, as compared with more than 93 percent of normal pubertal girls. Although plasma sex-steroid levels were normal, the secretion of luteinizing hormone in response to stimulation with gonadotropin-releasing hormone was elevated in the pubertal children (P less than 0.01 for the comparison with normal controls)--a finding that suggests compensation for decreased gonadal function. Despite clear evidence of gonadal damage, girls had early menarche at a mean age (+/- SD) of 11.95 +/- 0.91 years, as compared with the Australian standard of 12.98 +/- 1.11 years (P less than 0.01). Thus, in girls, puberty was early despite primary gonadal damage. Thirteen of 23 boys reached puberty at a mean age of 12.36 +/- 0.73 years. We conclude that treatment for acute lymphoblastic leukemia may lead to primary gonadal damage in both sexes, regardless of the age at treatment, but that the secondary characteristics of puberty develop at a normal age or, in girls, relatively early.

Adolescent↗
PubMed1989

Echocardiographic and angiographic findings in superior-inferior cardiac ventricles.

The anatomy of superior-inferior ventricles was studied in 17 patients, aged 1 day to 22 years, using echocardiography and angiography. In all patients, the right ventricle was located superiorly and the left ventricle inferiorly. The right ventricular sinus was underdeveloped in 14 of the 17 patients. Conversely, the right ventricular outflow tract was normally developed in all 17 patients. The visceroatrial situs was solitus in all patients, and it was associated with a concordant D-loop in 9 patients and with a discordant L-loop in 8. There was a high incidence of associated transposition of the great arteries (9 patients) or double-outlet right ventricle (5). Segmental combination was unpredictable, D-loop being associated with L-position of the great arteries in 4 of 8 patients and L-loop being associated with D-position of the great arteries in 4 of 9. There were only 3 concordant ventriculoarterial connections. Frequently associated anomalies included ventricular septal defect (17 patients), atrioventricular valve malformations (17) subaortic conus (14) and pulmonary outflow tract stenosis or atresia (11). Criss-cross hearts were present in only 7 patients.

Adult↗
PubMed1989

Pulmonary artery to the left atrium fistula as an unusual cause of cyanosis in the newborn.

A fistula between the pulmonary artery (PA) and the left atrium (LA) is a rare form of congenital heart disease, 34 cases having been described in the literature, all from the right pulmonary artery (RPA). Only six cases were diagnosed in the newborn period. We report such a case, diagnosed at 1 day of age by Doppler echocardiography, with an unusual site of the fistula.

Cyanosis↗
PubMed1989

Age influence on digestive transit time of particulate and soluble markers in broiler chickens.

The gastrointestinal transit-time of two markers, Cr-mordanted bran, a solid marker, and Cr-EDTA, a soluble marker, have been studied in chickens (Gallus gallus) at 1, 2, and 3 wk of age. Mean retention time of the particular marker decreased as chicks grew. The excretion of Cr-EDTA took longer as birds grew; this soluble marker was retained in the ceca of the fowl. It was postulated that the ceca are not fully functional until total resorption of the yolk sac content occurs.

Aging↗
PubMed1989

[Calculation of the pulmonary to systemic flow ratio using echo-Doppler in septal defects--correlation with oximetry].

OBJECTIVE: 1. local validation of a protocol of measurement of pulmonary to systemic flow ratio (QP/QS) by echo-Doppler in children with septal defects; 2. to assess continuous wave Doppler efficacy mainly in those patients where peak pulmonary flow velocity was beyond the Nyquist limit of pulsed Doppler. DESIGN: To correlate QP/QS ratio determined by echo-Doppler with that obtained by cardiac catheterization (oximetric method) performed within 48 hours, in children with isolated septal defects. MATERIAL AND METHODS: The QP/QS ratio was evaluated by pulsed and or continuous wave echo-Doppler in 50 children who were submitted within 48 hours to cardiac catheterization. All children had an intracardiac shunt (12 atrial septal defects--ASD; 26 ventricular septal defects--VSD and 12 atrio ventricular septal defects--AVDS). Identical measurements were performed in a group of 20 children without cardiac malformation--control group. To test inter-observer variability, all the measurement in 31 patients were repeated by a second observer. Pulmonary and aortic flow was calculated as: Q = A x V x ET x CF where, A is the valvular orifice area (cm2), V the mean flow velocity (cm/sec), ET the ejection time (sec) and CF the cardiac frequency (cycles/min). The Doppler beam-flow direction angle in the pulmonary (P) artery and ascending aorta (Ao) was less than 20 degrees. Results were correlated with those obtained by catheterization (oximetric method). RESULTS: We obtained a fairly good correlation with both pulsed wave Doppler (n = 43; r = 0.88; p less than 0.001; y = 0.84x + 0.40) and continuous wave Doppler (n = 50; r = 0.91; p less than 0.001; y = 0.86x + 0.35) or with pulsed wave Doppler in the P artery and continuous wave Doppler in the Ao (n = 43; r = 0.92; p less than 0.001; y = 0.86x + 0.27). In the control group, QP/QS ratio was evaluated by echo-Doppler: pulsed wave Doppler at 1.05 +/- 0.15 (mean +/- DS); continuous wave Doppler at 1.05 +/- 0.12 and, pulsed wave Doppler in the P artery and continuous wave Doppler in the Ao at 1.03 +/- 0.12. There was no significant difference in all three groups to the normal range of 1.00 (p less than 0.01). Inter-observer variability was less than 5.5% (p less than 0.001). CONCLUSION: Pulsed and/or continuous wave echo-Doppler measurements are a reliable noninvasive method in evaluating QP/QS ratio in children with isolated septal defects.

Adolescent↗
PubMed1988

Growth and growth hormone therapy of children treated for leukaemia.

A total of 37 children (24 male, 13 female) who had been treated for leukaemia with chemotherapy and 24 Gy cranial irradiation, and who were disease free for at least 18 months, were commenced on somatrem at a mean of 7.6 years (range, 4.8-12.1 years) after leukaemia diagnosis because of growth rate below the 25th centile for bone age. Peak GH response to provocation (exercise, arginine, insulin hypoglycaemia) was less than 20 milliunits/litre in 27 children (deficient group) and 20 milliunits/litre or more in 10 children (non-deficient group). The mean height SD decrease from diagnosis of leukaemia to commencement of somatrem was 1.98, 86% of the children decreasing by more than 1 SD. Those who were tall for age at leukaemia diagnosis and females were more severely affected. Mean (+/- SD) height velocity increased on somatrem from 2.7 +/- 1.1 to 6.6 +/- 2.2 cm/year during the first 6 months (n = 25), and to 6.0 +/- 1.7 cm/year during the first 12 months (n = 19). No difference in growth response was seen between the sexes or between the deficient and non-deficient groups. Catch-up growth occurred for the first 6 months only. It is concluded that children with a low growth rate after treatment of leukaemia should be considered for GH therapy irrespective of the results of GH provocative tests.

Adolescent↗
PubMed1988

[Evaluation of aortic to pulmonary blood flow ratio by Doppler echocardiography in septal defects].

Pulsed Doppler-echocardiography was used to measure systemic and pulmonary blood flows in 22 patients aged from 3 months to 62 years presenting with interatrial (n = 13) or interventricular (n = 9) septal defect. Calculations were based on echographic measurements of aortic and pulmonary orifice areas and on the integral of maximal aortic and pulmonary Doppler velocity curves. Section areas or the arteries, taken as being circular, were deduced from arterial diameter measurements effected above Valsalva's sinus. Doppler velocity curves were recorded at that level, looking for maximal velocities and assuming a flat velocity profile. Blood flow ratios evaluated from Doppler-echocardiography data were compared with data provided by oximetry and showed good correlations (r = 0.92; Y = 0.71x + 0.53; SEE = 0.24). Calculations by categories of lesions showed better results in patients with interatrial septal defect (r = 0.94; Y = 0.73x + 0.507; SEE = 0.22) than in patients with interventricular septal defect (r = 0.83; Y = 0.547x + 0.75; SEE = 0.25). The main difficulties encountered in measuring Doppler-echocardiography blood flow ratios concerned accurate measurement of pulmonary artery diameter, due to problems of lateral resolution, and accurate measurement of turbulent Doppler velocimetry curves. However, this new, non-invasive technique may be useful to determine the best indications for catheterization or even surgery.

Adolescent↗
PubMed1988

[Cardiac pacemakers in children. 15 years' experience].

Between 1971 and 1986, 85 pacemakers were implanted at the St Justine Hospital, Montreal, in 57 young patients (25 girls, 32 boys) then aged from one day to 23 years (mean 10.3 years). The patients were followed up for periods ranging from 15 days to 13.5 years (mean 4.5 years); 119 epicardial electrodes were positioned by thoracotomy in 52 patients and by sternotomy in 5 patients; the 85 pacemaker cases were placed in the left retroperitoneal cavity. The pacemakers were programmed in modes VVI (28), AAI (1) and DDD (28). The indications for pacemaker implantation were: complete atrioventricular block in 39 cases (postoperative 16, congenital 22, acquired 1), sinus node disease in 17 cases (postoperative 13, cardiomyopathy 3, normal heart 1) and Romano-Ward syndrome in 1 case. Operated heart diseases which required pacemaker implantation were: D-transposition of the great arteries in 17 cases (complete atrioventricular block 7, sinus node disease 10), tricuspid valve atresia in 3 cases (sinus node disease 3) and tetralogy of Fallot in 3 cases (complete atrioventricular block 3). Twenty-four patients underwent a total of 33 reoperations: 21 changes of battery, 12 changes of electrodes (6 for fibrosis, 6 for breakage). Only one patient developed infection of the pacemaker case. Altogether, the incidence of complications (infection and/or breakage) was low in this series, regardless of the pacing mode. Pacing in children is now an acceptable treatment with low risk provided the indications are well selected.

Adolescent↗
PubMed1988

[Recurrent thrombosis of an aortic valve prosthesis in a pregnant woman. Treatment with urokinase].

A 36 year old woman developed two thromboses on aortic valve prosthesis. The first thrombus at the 14th week of pregnancy was treated with urokinase (2,000 U/kg/h) plus heparin (700-1,000 U/h) over 24 hours and normal wing kinetics were obtained. The second thrombus developed at the 36 th week of pregnancy when the patient was receiving calciparin, and only transient improvement was obtained with similar doses of urokinase hourly over 72 hours. Progressive worsening resulted in higher doses (4,000 U/kg/h) being given without heparin and the thrombus then resolved. The use of urokinase for the first time in this indication allowed therefore, on two occasions and without hemorrhagic complications the cure of this recurrent thrombosis on aortic prosthesis, and the birth, by caesarean, of a healthy baby.

Adult↗
PubMed1987

Capillary column gas chromatographic identification of sugars in honey as trimethylsilyl derivatives.

A method for identifying carbohydrates (mono-, di- and trisaccharides) in honey is presented. It is based on the separate preparation of both trimethylsilyl ethers and oxime trimethylsilyl ethers of the sugars followed by their gas chromatographic separation on a fused-silica capillary column coated with OV-101 using temperature programming. From the two chromatograms, the number of peaks given by each derivatized sugar, their relative retention times and peak-area ratios are used for identification. The identities of two unidentified trisaccharide peaks are considered. Quantitative applications to honey sugar analysis are discussed.

Carbohydrates↗
PubMed1987

The pH dependence of the hydrolysis of chromogenic substrates of the type, Lys-Pro-Xaa-Yaa-Phe-(NO2)Phe-Arg-Leu, by selected aspartic proteinases: evidence for specific interactions in subsites S3 and S2.

Variation in the kinetic parameters, kcat and Km, with pH has been used to obtain evidence for significant acid-dissociation processes in the hydrolysis of octapeptide substrates by three aspartic proteinases. These substrates are all cleaved at the peptide bond between a Phe (P1) and a p-nitroPhe (P1') residue resulting in a shift in absorbance at 300 nm that facilitates kinetic measurements. The substrates differ in the amino-acid residues present in the P3 and the P2 positions. Porcine pepsin, calf chymosin, and the aspartic proteinase from Endothia parasitica all show pH dependencies that imply that favorable or unfavorable interactions can occur with the S3 or S2 areas of the enzyme-active site. Examination of the crystallographically determined structure of the E. parasitica proteinase and consideration of the amino-acid sequence differences between the three enzymes suggests that the origin of the pH effects arises from favorable interactions between Glu-13 (COO-) of pig pepsin and Thr (OH) or His (ImH+) in P3 of a substrate. Similarly, Lys-220 (NH3+) of chymosin and a Glu (COO-) in P2 of a substrate may produce a favorable interaction and Asp-77 (COO-) of E. parasitica proteinase and a Glu (COO-) in P2 of a substrate may produce an unfavorable interaction. These results lead to possible explanations for subtle specificity differences within a family of homologous enzymes, and suggest loci for study by site-directed mutagenesis.

Amino Acid Sequence↗
PubMed1987

Duodenal ulceration: review of 110 cases.

This paper describes 110 cases of childhood duodenal ulcer, which were diagnosed over 26 years: 63 were diagnosed by barium meal examination; 47 by upper gastrointestinal endoscopy. The mean age at diagnosis was 11.2 years, with symptoms reported in 46% before 10 years and in 15% before 6 years of age. There was often a considerable delay in diagnosis, particularly in the younger age group. Nocturnal pain (61%) and a close family history of duodenal ulcer disease (62%) were the most valuable pointers to the diagnosis. Fifteen children had required surgery for persistent symptoms. Thirty four had received treatment with an H2 receptor antagonist, and all but four had had a satisfactory initial response. Seventy per cent relapsed within six months of discontinuing treatment, and long term maintenance treatment may therefore be necessary.

Adolescent↗
PubMed1987

Kinetic characterization of dopamine as a suicide substrate of tyrosinase.

A kinetic study of the inactivation of frog epidermis tyrosinase by a suicide substrate dopamine hydrochloride is described. The kinetic parameters and constants which characterize this reaction have been determined and the effects of pH and the stoichiometric inhibition by chloride have been considered.

Animals↗
PubMed1987

[Anomalous origin of the left coronary artery. The form in infants].

Twenty-four cases of anomalous origin of the left coronary artery from the pulmonary artery are reported. These cases were collected over 27 years divided into three 9-year periods according to the years of the initial studies. The clinical aspects and diagnostic investigations (notably echocardiography, myocardial radioisotope imaging and various angiographic procedures) are reviewed; aortography seems to be, even now, the best exploratory method. Treatment is analyzed according to the periods of observations. From the earliest cases it may be concluded that ligation proved ineffective in infants and medical treatment often failed. Progressively, medical treatment with digitalis (now better controlled), potassium-sparing diuretics and vasodilators has become more effective. On the other hand, direct reimplantation of the left coronary artery onto the aorta has become the preferred surgical procedure. Among the 8 most recent cases (seen between 1977 and 1986), 4 were cured by medical treatment under the age of 3 and subsequent reimplantation. In the other 4 patients asystolia responded to medical treatment, and these children are now awaiting reimplantation.

Coronary Angiography↗