Nano-dimensional CeO2 nanorods for high Ni loading catalysts: H2 production by autothermal steam reforming of methanol reaction.

CeO2 nanorods were synthesized by a hydrothermal method and used as the support for preparing a series of Ni/CeO2 nanorod catalysts. The surface area of the catalysts decreased when the Ni percent over the CeO2 nanorods was increased. SEM results showed that the CeO2 is formed by nanorods approximately 1 µm in length. TEM and HREM revealed that the width of the nanorods is about 8 nm and it grew along the [1 1 1¯] axis. The catalytic activity of the catalysts was improved as the Ni was loaded onto CeO2 nanorods. The exposed planes of the CeO2 nanorod structure along the zone axis [0 1 1] for Ni impregnation were (1¯ 1¯ 1), (1 1 1¯), (1 1¯ 1), (1¯ 1 1¯), (2 0 0) and (2¯ 0 0) and they were more reactive for methanol conversion than (2¯ 2¯ 0), (2¯ 0 2¯), (0 2 2¯), (0 2¯ 2), (2 0 2) and (2 2 0) planes from the [1 1 1¯] axis (growth direction of the nanorod). This finding is mainly ascribed to the synergistic effect of the CeO2 nanorods and the Ni.

Acute effects of soft drink intake on calcium and phosphate metabolism in immature and adult rats.

OBJECTIVE: To test the acute effects of the intake of a phosphoric acid containing soft drink on acid-base balance and on calcium and phosphate metabolism. MATERIAL AND METHODS: We studied 14 young adult male Sprague-Dawley rats aged 90 days, and 14 immature animals aged 30 days. Half of the animals in each group were randomly assigned to receive either tap water (controls), or Coca-Cola ad libitum for seven days. After this period, the rats were individually placed in metabolic cages to collect 24 hours urine, and they were exsanguinated by aortic puncture. Immediately, pH and ionized calcium were measured in whole blood. Creatinine, phosphate and total calcium were determined in the urine and plasma. Plasma levels of PTH, 1 alpha, 25 (OH)2 D3 and 25 OH D3 were measured by IRMA and RIA commercial kits. RESULTS: The animals receiving the soft drink, both adults and immature, developed significant hypercalciuria and hyperphosphaturia. In immature animals, the plasma pH dropped from 7.45 +/- 0.04 to 7.33 +/- 0.02 (p < 0.05) but did not change in adult animals. Ionized calcium dropped significantly from 1.06 +/- 0.04 to 0.80 +/- 0.06 meq/L (p < 0.05) in immature animals but not in the adult animals. Only immature rats developed significant reduction of 1 alpha, 25 (OH)2 D3 and 25 OH D3, whereas only the adult rats developed significant hyperparathyroidism. Immature animals showed more severe derangement of calcium and phosphate metabolism related to soft drink intake.

[Diagnosis of breast tumors by scintigraphy versus mammography]. / Diagnóstico de tumores mamarios por centelleografía versus mastografía.

OBJECTIVE: To compare the efficacy of the breast scintigraphy with 99mTc-MIBI in the detection of breast lesions versus mammography. DESIGN: Cross sectional study. SETTING: A concentration oncologic hospital in Mexico City. PATIENTS: 56 women with a biopsy performed due to radiologic suspicion of mammary cancer were included as well as 10 normal women. MAIN PROCEDURES: Mammography, breast scintigraphy with 99mTc-MIBI, and biopsy were performed. RESULTS: Sensitivity of breast scintigraphy was 100% specificity 94.6%, PPV 90% and NPV 100%; sensitivity of the mammography was 100%, specificity 54% PPV 52.7%, and NPV 100%. CONCLUSIONS: Breast scintigraphy with 99mTc-MIBI showed a higher sensitivity and specificity than those of mammography. It was highly reliable for the diagnosis of mammary gland malignant lesions.

[Soft-drinks and health]. / Los refrescos y la salud.

OBJECTIVE: To analyze published papers about soft drinks use, and to describe possible health benefits, risks, and damages related to soft drink consumption. INFORMATION SOURCE: A search was done in the MEDLINE compact disks, from January 1970 to January 1997, with the keywords soft drink, beverages, carbonated beverages, cola, Coca-Cola and sweetening-agents. STUDY SELECTION: Ninety nine papers reporting health-related damages or benefits in clinical or experimental studies were reviewed. DATA EXTRACTION: All articles with a clear description of at least one beneficial or harmful effect related to soft drink consumption were considered. RESULTS: There were reports on 25 harmful effects and of 7 possibly beneficial effects. Data are classified in prophylactic and therapeutic uses, dental caries and other dental disorders, mineral metabolism disorders, acid-peptic disease, neoplasm, risk factors for cardiovascular disease, effects on central nervous system, reproduction, allergy, and miscellaneous. CONCLUSIONS: High prevalence of exposure and excessive consumption of soft drinks may represent a public health problem in Mexico. Data analysis shows that soft drink consumption may not be as harmless as generally believed. Many of the reports are anecdotal, without a suitable methodological design. A wide field for research is present in this area.

Intraobserver and interobserver reliability in assessment of neonatal cranial ultrasounds.

Intraobserver and interobserver reliability in assessing neonatal cranial ultrasounds for periventricular-intraventricular hemorrhage (PVH-IVH) is not well studied; therefore, studies were designed to address this. For intraobserver reliability 180 cranial ultrasounds (360 hemispheres) were randomly selected from greater than 2000 ultrasounds and read twice by one radiologist in a blinded fashion. Ninety-eight percent were interpreted identically; of the 2% reinterpreted differently, all were initially abnormal but normal on the second reading. The least agreement occurred when interpreting ventricular size. Only four infants (1.1%) were placed in an unfavorable prognostic category (grades III and IV) on the first reading and a favorable prognostic category on the second interpretation (no bleed, grades I and II). To determine interobserver reliability, 20 sonograms were interpreted by eight independent observers representing five institutions. Using the multiple rater kappa kappa statistic, we determined interobserver agreement on overall impression (normal vs. abnormal), presence and extent of PVH-IVH (i.e. grade), presence of residual cyst, and ventricular dilatation. Greatest degree of agreement occurred when determining normal vs. abnormal, residual cyst, no bleed, and grades III and IV PVH-IVH. Poorest agreement occurred when reading grades I and II PVH-IVH and ventricular dilatation. After condensing interpretations of cranial ultrasounds into two prognostic categories, i.e. favorable (no bleed, grades I and II) and unfavorable (grades III and IV), there was excellent agreement among the observers.

Neonatal intracranial hemorrhage: I. Changing pattern in inborn low-birth-weight infants.

Many reports of the occurrence of periventricular-intraventricular hemorrhage (PVH-IVH) are biased by the inclusion of both inborn and outborn infants. To obviate this selection bias we examined a large inborn population of low-birth-weight infants to determine if the incidence of PVH-IVH changed over a 3-year interval from March, 1982 through February, 1985. Serial cranial ultrasonography was performed in 463 consecutive infants of birth weight less than or equal to 1500 g who survived for more than 8 h. The incidence of PVH-IVH decreased from 31.5% and 29.3% in years 1 and 2, respectively, to 23.7% in year 3 (P less than 0.05). The latter reflected a fall in the incidence of grades III and IV PVH-IVH, but no change in the incidence of grades I and II. This observation was not attributable to changes in mortality, the distribution of infants by birth weight and estimated gestational age in each year of the study, or infants excluded from the analysis. Contrary to most reports, 21.9% of all PVH-IVH during the 3 years were first diagnosed after 14 days postnatal age and were predominantly grade I. These results document not only a change in the epidemiology of PVH-IVH in an inborn population, but also the importance of serial cranial ultrasonography beyond the first week of life.

Neonatal intracranial hemorrhage: II. Risk factor analysis in an inborn population.

The ability to predict the occurrence of neonatal periventricular-intraventricular hemorrhage (PVH-IVH) would be useful in the design of clinical trials to prevent its occurrence. Therefore, data were collected from 463 consecutive infants less than or equal to 1500 g birth weight delivered between March 1, 1982 and February 28, 1985. This large population made it feasible to divide the infants into two groups, using one group to develop a model predictive of ICH and the second group to test the validity of the model. Infants were randomly grouped by sex, race, gestational age, birth weight, month of birth, mortality, and incidence and grade of worst PVH-IVH. In Group A (n = 232), respiratory distress syndrome, ventilator therapy, PaCO2 greater than or equal to 60 mmHg, PO2 less than or equal to 40 mmHg greater than or equal to 2 h, lower 1- and 5-min Apgar scores, lower pediatric estimation of gestational age, and pneumothorax were significantly associated with PVH-IVH by univariant analyses (chi 2, P less than 0.03). Multivariant discriminant analysis performed on Group A revealed that pneumothorax, cesarean section, PaCO2, and ventilator therapy were most predictive of PVH-IVH, but sensitivity was 55% and specificity 78%. Applying the model to Group B, sensitivity decreased to 21% while specificity rose to 93%. Logistic regression, which takes into account non-normally distributed variables, did not improve predictability.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrostomy and Nissen fundoplication in neurologically impaired children.

We report our experience with 90 neurologically impaired children treated with gastrostomy and Nissen fundoplication. Malnutrition was the main problem, followed by aspiration, recurrent pneumonia, and vomiting. The symptomatology was caused by swallowing incoordination and gastroesophageal reflux. The diagnosis of gastroesophageal reflux was confirmed by upper gastrointestinal series and pH probe. Nissen fundoplication was performed following a standard technique with preservation of the vagus nerves and its branches, repair of the diaphragmatic crura, reconstruction of the angle of His, and a 360 degree wrap. A gastrostomy and pyloroplasty or pyloric dilatation were part of the operative procedure. There were no deaths and few complications related to the surgical procedure. Marked nutritional improvement was seen in most cases with an average weight gain of 3.2 kg/patient 3 months following surgery. There was also improvement in milestones and seizure control. The majority of parents were very satisfied and would recommend the procedure to other parents with similar problems.

Brainstem auditory evoked potentials in very-low-birth-weight neonates with intracranial hemorrhage.

A study was conducted in very-low-birth-weight (VLBW) neonates to correlate structural damage to the central nervous system due to intracranial hemorrhage (ICH) with electrophysiological function of the lower auditory system as measured by brainstem auditory evoked potentials (BAEP). BAEP testing of 61 VLBW neonates was completed at 36 weeks conceptional age. BAEP Wave III and V latencies significantly increased with increasing severity of ICH. Although significant at conventional levels (P less than 0.05), these correlations were of modest size. Furthermore, after adjusting for the effects of birthweight, hypoxia, lowest pH and associated pCO2 the correlation between ICH and BAEP was reduced in magnitude and no longer significant. Thus, there is little evidence that ICH shortly after birth affected functioning of the auditory brainstem pathways in VLBW neonates at 36 weeks conceptional age.

Atlanto-axial instability and spinal cord compression in children--diagnosis by computerized tomography.

Five children who were at risk for atlanto-axial instability underwent computerized tomography scanning of the cervical spine in flexion and extension to document the degree of bone instability and the presence or absence of spinal cord compression. Two patients had Morquio's syndrome, two had os odontoideum , and one had Klippel-Feil syndrome, and in all five the lateral radiographs of the cervical spine in flexion and extension were equivocal with regard to instability or were difficult to interpret because of the bone anomalies. The computerized tomography scan then provided a diagnosis by a non-invasion technique and quantitated the amount of compromise of the spinal cord by delineating flattening of the cord. The scan therefore helped the surgeon to decide if the spinal cord was at significant risk and if atlanto-axial fusion was advisable.

Measurement of bone mineral content of preterm neonates.

Although photon absorptiometry is increasingly used to evaluate bone mineral content of neonates, its reliability in this age group is unclear. The midradius or middistal radius of 12 growing preterm infants was scanned, using a Norland 278 Densitometer. Proper examiner technique and densitometer calibration were first verified. In three infants, the bone edges were not consistently discernible from soft tissue. In the remaining nine infants, apparatus variability (the percent change in bone mineral content of scans repeated without repositioning the infant) was comparable to intraexaminer and interexaminer variability (determined after the same or a different examiner repositioned the infant and repeated the scan). The variability for successive scans ranged from -73% to +60% (SD, 5% to 36%). Adequate reliability for preterm infants remains to be documented for commercially available photon absorptiometers by in vivo studies.

Angiography of intimal and intramural arterial injuries.

Fifteen patients with injuries disrupting the tunica intima and media are reviewed and 5 cases demonstrating the typical angiographic appearance of these injuries described. In all 15, the tunica adventitia remained intact and pulses were present on the initial physical examination. Injuries described include subintimal hemorrhages with and without an associated tear of the intima and a complete tear of both the tunica intima and media with the tunica adventitia intact. The authors conclude that angiography is the best preoperative diagnostic procedure for these injuries; it should be used whenever the trauma involves a site near a major vessel.

Computer reconstructed sagittal and coronal CT scans. Applications in neurological disorders of infants and children.

Recent technical advances in computed tomography (CT) allow sagittal and coronal image reconstruction by computer manipulation of data from thin-section transverse scans. Three cases are presented to illustrate this new supplementary modality in the pediatric patient. The technique, diagnostic implications and value of orthogonal plane image reconstruction are discussed.

Craniocerebral computed tomography in the neonate.

Craniocerebral computed tomography (CT) is an extremely important component of the armanentarium for diagnosis of neurological disorders in the neonate. The indications, techniques, normal anatomy, and pathologic abnormalities of CT scans in newborn infants are presented. Hydrocephalus and intracranial hemorrhage are discussed in depth.

CT diagnosis of intracranial cystic abnormalities in children.

The introduction of computed axial tomography has been of tremendous importance in the evaluation of intracranial pathology in children. The broad spectrum of cystic intracranial lesions of congenital, infectious, traumatic, vascular and neoplastic origin are discussed. Their CT findings, pathology and pathogenesis are emphasized.

Computed tomography in the evaluation of sella and parasella lesions: the value of sagittal and coronal reconstructions.

A method is described whereby contiguous, thin-section (3 mm) axial CT scans are obtained followed by computer manipulation of the data to reconstruct good quality images in sagittal and coronal planes. The application of this technique in the evaluation of sella and parasella abnormalities is discussed. In our experience, this has resulted in an increased sensitivity of CT scanning for the detection of abnormalities around the sella. In addition, it has been possible to more accurately define the true extrasella extension of pituitary tumors.