Is liquid ventilation a reasonable alternative?

Liquid breathing has been in medical literature for nearly 80 years and has been proposed as a means of improving gas exchange in critically ill infants since the 1970s. Extensive laboratory experience with perfluorochemical liquid ventilation has lead to clinical trials in infants, children, and adults. This article discusses the process and physiologic response to liquid breathing in neonates, and reviews some of the factors that need clarification prior to approval as a routine clinical therapy.     

High resolution sonographic determination of the normal dimensions of the intracranial extraaxial compartment in the newborn infant

Prominence of the extraaxial space occasionally is encountered in infants referred for ultrasonography to exclude hydrocephalus. The interpretation of this finding can be problematic. We examined the width of the extraaxial compartment in 82 normal newborn infants. Scanning technique was optimized for viewing the near field, and the extraaxial space was measured over the cerebral convexities. Correlation was made with demographic variables. Measurements varied from 0 to 3.3 mm (mean, 1.6 mm), with slight negative linear relationship to gestational age. We conclude that small amounts of extraaxial fluid, up to 3.3 mm in width on scans, are common and normal in newborn infants.     

A new assay for tRNA aminoacylation kinetics

An improved quantitative assay for tRNA aminoacylation is presented based on charging of a nicked tRNA followed by separation of an aminoacylated 3'-fragment on an acidic denaturing polyacrylamide gel. Kinetic parameters of tRNA aminoacylation by Escherichia coli AlaRS obtained by the new method are in excellent agreement with those measured by the conventional method. This assay provides several advantages over the traditional methods of measuring tRNA aminoacylation: (1) the fraction of aminoacyl-tRNA is measured directly; (2) data can be obtained at saturating amino acid concentrations; and (3) the assay is significantly more sensitive.     

Further delineation of spondylo-meta-epiphyseal dysplasia, short limb-abnormal calcification type, with emphasis on diagnostic features

Further delineation of a generalized bone dysplasia which we call spondylo-meta-epiphyseal dysplasia, short limb-abnormal calcification type is presented. This dwarfing condition has several serious complications, with the most common cause of death being spinal cord damage secondary to atlantoaxial instability. It is a heritable condition with an autosomal recessive mode of transmission. Radiologic diagnostic criteria are developed on the basis of studies in 8 patients with the oldest being between 4 and 5 years old. The condition is clinically and radiographically apparent neonatally or in early infancy, and it is probable that all or almost all affected individuals will come to medical attention in the age range screened by this study.     

Amorphous metals for hard-tissue prosthesis

Owing to a unique atomic structure lacking microstructural defects, glassy metals demonstrate certain universal properties that are attractive for load-bearing biomedical-implant applications. These include a superb strength, which gives rise to very high hardness and a potential for minimizing wear and associated adverse biological reactions, and a relatively low modulus, which enables high elasticity and holds a promise for mitigating stress shielding. There are, however, other non-universal properties specific to particular amorphous metal alloys that are inferior to presently used biometals and may be below acceptable limits for hard-tissue prosthesis. In this article, features of the performance of amorphous metals relevant to hard-tissue prosthesis are surveyed and contrasted to those of the current state of the art, and guidelines for development of new biocompatible amorphous metal alloys suitable for hard-tissue prosthesis are proposed.     

Retrospective analysis of alternate-day prednisone maintenance therapy for Crohn''s disease

INTRODUCTION: Clinical, microbiological, therapeutic and prognostic characteristics of brain abscesses were analyzed as well as the influence of CT in their evolution. MATERIALS AND METHODS: Retrospective study of 59 patients with the diagnosis of brain abscess of bacterial source before (group A) and after (group B) the introduction of CT (25 and 34 patients, respectively). RESULTS: The most common symptom was headache (76.3%) and the most common abnormality in physical examination was a decrease in the level of consciousness (61%) and this abnormality was associated with a higher mortality rate (13% versus 41.6%; p < 0.05) and also a higher proportion of neurologic sequelae (50% versus 85.7%; p < 0.05). The diagnosis was obtained earlier in group B. The hematogenous source predominated (32.2%); an adjacent source was identified in 28.8% and an apparent source was not recognized in 27.2% (40% in group A versus 17.6% in group B). Anaerobic and microaerophilic streptococci were the bacteria recovered most frequently. Gram-negative aerobic bacteria were the most common in otogenic abscesses. The use of corticosteroids had no influence upon mortality, but it was associated with a lower percentage of neurological sequelae (40% versus 14%; p < 0.05). The introduction of CT decreased mortality (40% in group A versus 23.5% in group B, although this difference was not significant) and also sequelae (86.6% in group A versus 57.6% in group B; p < 0.05). Leaving apart cases of bacterial endocarditis, in which death was due to the underlying heart disease and a systemic sepsis picture, mortality attributed to brain abscess was 20.3%. CONCLUSIONS: The introduction of CT has meant a significant breakthrough for the diagnosis, treatment and follow-up of these patients and has contributed to improvement in survival. In our series, the diagnosis of brain abscess was obtained earlier and the number of brain abscesses with no apparent source has decreased since the introduction of CT. Moreover, CT sensitivity is really good for locating multiple abscesses. Overall, the prognosis of these patients has improved since the introduction of this technique. Nevertheless, brain abscess is still associated with a relevant morbi-mortality rate.     

Experimental and theoretical investigation of the regenerativecapabilities of electrooptic and all-optical interferometric wavelengthconverters

An experimental and theoretical investigation of the regenerative capabilities of electrooptic (E/O) and all-optical (A/O) interferometric wavelength converters is presented. We show that both the E/O and A/O regeneration scheme exhibit a 5-dB noise suppression capability. Furthermore, we demonstrate that by cascading two A/O-converters after an erbium-doped fiber amplifier (EDFA), the performance is further improved resulting in a total noise suppression of 8 dB. Our detailed model, which accounts for the redistribution of a signal in the converters, shows good agreement with the experiments and predicts a significant increase in the number of EDFAs that can be cascaded with interferometric wavelength converters in the link     

Dependence of the AlN-Layer growth rate on source-substrate clearance for the sublimation growth method

The proposed study is devoted to investigating the growth conditions of AlN thick layers and bulk crystals in the sublimation sandwich method. For the first time, the dependences of the layer-growth rate on source-substrate clearance are experimentally obtained for this material at two nitrogen-pressure values in the reactor: 0.3 and 0.6 bar. The obtained results point to the fact that the basic mechanism of the transport of components of the source to the substrate is diffusion. The contribution of kinetic effects becomes appreciable at the smallest clearance of 0.3 mm, especially, at a lower nitrogen pressure of 0.3 bar.