A comparative study of human immunodeficiency virus culture, polymerase chain reaction and anti-human immunodeficiency virus immunoglobulin A antibody detection in the diagnosis during early infancy of vertically acquired human immunodeficiency virus infection

Asynchrony of delivered and spontaneous breaths in mechanically ventilated infants may impair gas exchange and prolong the need for assisted ventilation. We conducted a randomized, controlled trial of a patient-triggered, flow-synchronized ventilator on 30 preterm infants with respiratory distress syndrome who weighed between 1100 and 1500 gm at birth. Entry criteria included radiographic evidence of respiratory distress syndrome and the need for mechanical ventilation and surfactant replacement therapy. Patients were assigned to either conventional time-cycled, pressure-limited ventilation or patient-triggered, flow-synchronized ventilation in an assist/control mode. Otherwise clinical management was identical. Time to extubation was the primary outcome measure. Patients treated with flow-synchronized ventilation were weaned more rapidly and had a significantly shorter mean time to extubation than those treated with time-cycled, pressure-limited ventilation, 119 versus 271 hours, p = 0.0152. In addition, there was no difference in the rate of complications between the two groups. There were, however, considerable reductions in patient charges of $4344 per patient in the flow-synchronized ventilation group.     

Time course of coronary endothelial healing after injury due to ischemia and reperfusion

BACKGROUND: Although it has been demonstrated in short-term preparations that ischemia with early reperfusion results in coronary vascular injury manifested by abnormal endothelium-dependent relaxation and increased permeability to plasma proteins, it has not been clear whether these abnormalities are permanent or reversible. METHODS AND RESULTS: In a canine model, regional coronary ischemia was accomplished by 1 hour of left anterior descending coronary artery ligation, and follow-up studies were performed after reperfusion for 1 hour, 48 hours, 2 weeks, or 9 weeks. Vasorelaxation was measured in vitro with preconstricted epicardial coronary artery rings subjected to increasing concentrations of the endothelium-dependent vasodilator ADP and the endothelium-independent vasodilator nitroprusside. At 1 and 48 hours of reperfusion, relaxation of rings from the ischemic reperfused artery to ADP was blunted, but relaxation to nitroprusside was normal. At 2 weeks there was a nonsignificant trend toward a blunted response to ADP in the ischemic/reperfused rings, and at 9 weeks a completely normal response to ADP was observed. Coronary microvascular permeability was assessed by measurement of protein leak index (PLI), by using a double-isotope technique with autologous radiolabeled transferrin and erythrocytes. At 1 and 48 hours of reperfusion there were substantial increases in PLI in the previously ischemic regions, indicative of increased extravascular transferrin. There was a small increase in PLI at 2 weeks but a completely normal measurement at 9 weeks. Electron microscopy of ischemic/reperfused vessels demonstrated endothelial cell swelling and other abnormalities in epicardial arteries and the microcirculation at 48 hours of reperfusion but normal endothelium at 2 weeks of reperfusion. CONCLUSIONS: After 1 hour of regional coronary ischemia, coronary endothelial injury occurs early in reperfusion with abnormalities in epicardial coronary artery endothelium-dependent relaxation, coronary microvascular permeability, and both epicardial coronary artery and microvascular histology. This pattern of injury persists for at least 48 hours, but there is partial functional and complete histological recovery within 2 weeks and complete functional recovery within 9 weeks.     

Craniofacial computer-assisted surgical planning and simulation

Computer-assisted planning and simulation of craniofacial surgery has progressed from development, through validation, and into clinical use. CT scans are transferred from the radiology department to a graphics workstation in the surgeon's office or laboratory, where data postprocessing and visualization for anatomic evaluation and surgical simulation are performed. Quantitative and qualitative comparative analyses between the plan/simulation and the actual postoperative result provide the feedback that validates or refutes the preoperative assessment and simulated intervention. The optimum surgical solution can be chosen from many possibilities. Interactive computer-assisted surgical simulation is also useful for morbidity-free training of inexperienced surgeons.     

The phosphorylation state of phosducin determines its ability to block transducin subunit interactions and inhibit transducin binding to activated rhodopsin

Heterotrimeric GTP-binding proteins (G-proteins) serve many different signal transduction pathways. Phosducin, a 28-kDa phosphoprotein, is expressed in a variety of mammalian cell types and blocks activation of several classes of G-proteins. Phosphorylation of phosducin by cyclic AMP-dependent protein kinase prevents phosducin-mediated inhibition of G-protein GTPase activity (Bauer, P. H., Müller, S., Puzicha, M., Pippig, S., Obermaier, B., Helmreich, E. J. M., and Lohse, M. J. (1992) Nature 358, 73-76). In retinal rods, phosducin inhibits transducin (Gt) activation by binding its beta gamma subunits. While rod phosducin is phosphorylated in the dark and dephosphorylated after illumination (Lee, R.-H., Brown, B. M., and Lolley, R. N. (1984) Biochemistry 23, 1972-1977), the significance of these reactions is still unclear. The data presented here permit a more precise characterization of phosducin function and the consequences of its phosphorylation. Dephosphophosducin blocked binding of the Gt alpha 1 subunit to activated rhodopsin in the presence of stoichiometric amounts of Gt beta gamma, whereas phosphophosducin did not. Surprisingly, the binding affinity of phosphophosducin for Gt beta gamma was not significantly reduced compared with the binding affinity of dephosphophosducin. However, the association of phosducin with Gt beta gamma in a size exclusion column matrix was dependent on the phosphorylation state of phosducin. Moreover, the ability of phosducin to compete with Gt alpha for binding to Gt beta gamma was also dependent on the phosphorylation state of phosducin. No interaction was found between phosducin and Gt alpha. These data indicate that phosducin decreases rod responsiveness by binding to the beta gamma subunits of Gt and preventing their interaction with Gt alpha, thereby inhibiting Gt alpha activation by the activated receptor. Moreover, phosphorylation of phosducin blocks its ability to compete with Gt alpha for binding to Gt beta gamma.     

Computer-stimulated test fitting of an implantable hearing aid using implantable hearing aid using three-dimensional CT scans of the temporal bone: preliminary study

In preparation for future implantation of the implantable middle ear transducer in patients, a method was sought for preoperatively test fitting a model of the device, using computer generated three-dimensional (3-D) temporal bone images derived from spiral computed tomography (CT) data. A 3-D model of the implantable middle ear transducer was designed using NIH Image software on a Macintosh computer. High resolution human temporal bone CT scans were obtained using a spiral CT scanner (Siemens Somatom Plus S). The 3-D transducer model was superimposed onto 3-D reconstructions of the temporal bone using ANALYZE software on a computer graphics workstation (Sun SPARCstation 10), showing the transducer "implanted" in the temporal bone. Measurements were validated using a cadaver temporal bone. This process produced images demonstrating the "fit" of the current transducer design in the mastoid region of the adult temporal bone. It permitted assessment of the proximity of surrounding structures such as the external auditory meatus, dura, or sigmoid sinus. Preliminary cadaver validation measurements confirmed the accuracy of this method. Three-dimensional CT is a feasible method for preoperative planning of the surgical implantation of devices in the temporal bone. This method of 3-D test fitting will be used in the future to determine optimum orientation and size limitations for human implantable devices.     

Stair-step artifacts in three-dimensional helical CT: an experimental study

We describe 3 sibs, their father, and paternal grandfather with amelogenesis imperfecta. In 2 sibs and the father the defect is associated with a neurological syndrome which has a wide range of phenotypic variability. The proposita has ataxia, EEG abnormalities, moderate dementia, and enamel hypoplasia. This case and the affected relatives are discussed in relation to Kohlschütter-T?nz syndrome and neuroectodermal diseases. The syndrome described here, characterized by the association of a genetic enamel defect and neurological impairment, may be of considerable interest in advancing genetic and clinical knowledge on ectodermal tissues and their development.     

Chloroplast and nuclear gene sequences indicate late Pennsylvanian time for the last common ancestor of extant seed plants

We have estimated the time for the last common ancestor of extant seed plants by using molecular clocks constructed from the sequences of the chloroplastic gene coding for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and the nuclear gene coding for the small subunit of rRNA (Rrn18). Phylogenetic analyses of nucleotide sequences indicated that the earliest divergence of extant seed plants is likely represented by a split between conifer-cycad and angiosperm lineages. Relative-rate tests were used to assess homogeneity of substitution rates among lineages, and annual angiosperms were found to evolve at a faster rate than other taxa for rbcL and, thus, these sequences were excluded from construction of molecular clocks. Five distinct molecular clocks were calibrated using substitution rates for the two genes and four divergence times based on fossil and published molecular clock estimates. The five estimated times for the last common ancestor of extant seed plants were in agreement with one another, with an average of 285 million years and a range of 275-290 million years. This implies a substantially more recent ancestor of all extant seed plants than suggested by some theories of plant evolution.     

The misrepresentation of the human pelvis

A representative series of illustrations of the human bony pelvis dating from the sixteenth century to the present is used to demonstrate the persistent misrepresentation in the orientation of the pelvis and in the nomenclature. Early erroneous concepts were probably strongly reinforced by publications of the Belgian anatomist Vesalius in the sixteenth century. In mounting the vertebrae on a vertical iron rod, he erased much of the sacral curvature and, as a consequence, the orientation of the rest of the pelvis was distorted. True versions of the pelvis were executed by Leonardo da Vinci before the time of Vesalius but these drawings were apparently among those that were lost for many years. A relatively small number of similarly accurate depictions of the bony pelvis have appeared down through the centuries and some of these are also included. A persistent error in many anatomical textbooks used today presents a modified inferior view of the pelvis as the "front view" and a nearly accurate front view as a "view from above." No definitive conclusion can be reached concerning the reason(s) for the remarkably long persistence of this error. The figures referenced are presented in the Gallery immediately following this article.     

Molecular cloning and sequence comparison of the S1 glycoprotein of the Gray and JMK strains of avian infectious bronchitis virus

The nucleotide sequences of S1 glycoprotein genes of the Gray and JMK strains of avian infectious bronchitis virus (IBV) were determined and compared with published sequences for IBV. The IBV Gray and JMK strains had 99% nucleotide sequence similarity. The overall nucleotide sequence similarity of the Gray and JMK strains compared with other IBV strains was between 82.0% and 87.4%. The similarity of the predicted amino acid sequence for the S1 glycoproteins of the Gray and JMK strains was 98.8%. Six of the 10 differences in the amino acid sequence were found between residues 99 and 127, suggesting a possible role for that region in the tissue trophisms of the viruses. The S1 glycoprotein of the Gray and JMK strains had 79.5%-84.6% amino acid similarity with the published sequence of other IBV strains. Serine instead of phenylalanine was observed in the protease cleavage site between the S1 and S2 glycoprotein subunits for the Gray and JMK strains, which was similar to the published sequence for the Ark99 and SE17 strains. The significance of that amino acid change is not known. Based on the nucleotide sequence of the Gray and JMK strains, the BsmAI restriction enzyme was selected by computer analysis and was used in restriction fragment length polymorphism analysis to differentiate the two strains.