Low-dose nitric oxide therapy for persistent pulmonary hypertension of the newborn. Clinical Inhaled Nitric Oxide Research Group

BACKGROUND: Inhaled nitric oxide improves gas exchange in neonates, but the efficacy of low-dose inhaled nitric oxide in reducing the need for extracorporeal membrane oxygenation has not been established. METHODS: We conducted a clinical trial to determine whether low-dose inhaled nitric oxide would reduce the use of extracorporeal membrane oxygenation in neonates with pulmonary hypertension who were born after 34 weeks' gestation, were 4 days old or younger, required assisted ventilation, and had hypoxemic respiratory failure as defined by an oxygenation index of 25 or higher. The neonates who received nitric oxide were treated with 20 ppm for a maximum of 24 hours, followed by 5 ppm for no more than 96 hours. The primary end point of the study was the use of extracorporeal membrane oxygenation. RESULTS: Of 248 neonates enrolled, 126 were randomly assigned to the nitric oxide group and 122 to the control group. Extracorporeal membrane oxygenation was used in 78 neonates in the control group (64 percent) and in 48 neonates in the nitric oxide group (38 percent) (P=0.001). The 30-day mortality rate in the two groups was similar (8 percent in the control group and 7 percent in the nitric oxide group). Chronic lung disease developed less often in neonates treated with nitric oxide than in those in the control group (7 percent vs. 20 percent, P=0.02). The efficacy of nitric oxide was independent of the base-line oxygenation index and the primary pulmonary diagnosis. CONCLUSIONS: Inhaled nitric oxide reduces the extent to which extracorporeal membrane oxygenation is needed in neonates with hypoxemic respiratory failure and pulmonary hypertension.     

Immunohistochemical localization of the differentiation marker E11 in dental development of rats

E11 antigen, originally characterized in a rat osteosarcoma cell line, is known to be expressed during late stages of the osteogenic cell lineage both in vitro and in vivo. The aim of the present study was to monitor the occurrence and distribution patterns of the E11 antigen using monoclonal antibodies (mAb E11 and MEP-1) during different stages of tooth germ development of new-born rats by means of immunohistochemistry. Both antibodies strongly bound to plasma membranes of ameloblasts in presecretory and secretory stages. In addition, odontoblasts and cells of the periodontium were immunoreactive for E11 and MEP-1. During maturation, the immunoreactivity of ameloblast plasma membranes decreased significantly. Our data suggest that E11 and MEP-1 might be important as markers for cell differentiation and mineralization processes during tooth germ development.     

MUC4 expression increases progressively in pancreatic intraepithelial neoplasia

Pancreatic adenocarcinoma is believed to develop from histologically identifiable intraductal lesions known as pancreatic intraepithelial neoplasias (PanINs) that undergo a series of architectural, cytologic, and genetic changes, a progression model similar to the adenoma-carcinoma sequence in the colon. The apomucin MUC4 has been implicated in invasive pancreatic adenocarcinoma. MUC4 expression is not detectable at the RNA level in normal pancreas but is detectable at high levels in invasive pancreatic adenocarcinoma. We documented the pattern of expression of MUC4 in PanINs by studying a series of 71 PanIN lesions immunohistochemically using a new monoclonal antibody to MUC4. Five (17%) of 30 PanIN-1 lesions, 10 (36%) of 28 PanIN-2 lesions, 11 (85%) of 13 PanIN-3 lesions, and 25 (89%) of 28 invasive adenocarcinomas labeled with the MUC4 antibody used in the study. In addition, afew nonneoplastic lesions labeled with the MUC4 antibody, including reactive ducts in chronic pancreatitis, atrophic ducts filled with inspissated secretions, and ducts showing squamous metaplasia. Our data help establish the patterns of MUC4 expression in neoplastic precursors in the pancreas and add further support to the progression model for pancreatic adenocarcinoma.     

Segregation of a supernumerary del(15) marker chromosome in sperm

Supernumerary marker chromosomes (SMC) can be associated with both normal and abnormal phenotypes. In addition, SMC are found at higher frequency in males with infertility. We identified a SMC, characterized as a del(15)(q11.2) chromosome, in a phenotypically normal male. Using fluorescence in situ hybridization (FISH), we examined the segregation of the del(15) chromosome in sperm from this patient. Only 6.23% of sperm nuclei showed disomy using a chromosome 15 alpha-satellite FISH probe, instead of the expected 50%. In addition, FISH analysis showed no increase for non-disjunction of chromosome 18, excluding an interchromosomal effect for this chromosome. The significant decrease in sperm bearing the del(15) may be due to tissue-specific mosaicism or a result of some form of selection against the del(15) during spermatogenesis. This finding provides a basis for the observation that SMC(15) are less likely to be inherited from a paternal carrier.     

Sleep in seasonal affective disorder patients in forced desynchrony: an explorative study

The majority of winter-type seasonal affective disorder (SAD) patients complain of hypersomnia and daytime drowsiness. As human sleep is regulated by the interaction of circadian, ultradian and homeostatic processes, sleep disturbances may be caused by either one of these factors. The present study focuses on homeostatic and ultradian aspects of sleep regulation in SAD. Sleep was recorded polysomnographically in seven SAD patients and matched controls subjected to a 120-h forced desynchrony protocol. In time isolation, subjects were exposed to six 20-h days, each comprising a 6.5-h period for sleep. Patients participated while being depressed, while remitted after light therapy and in summer. Controls were studied in winter and in summer. In each condition, the data of each subject were averaged across all recordings. Thus, the influence of the effects of the circadian pacemaker on sleep was excluded mathematically. The comparison of patients with controls and with themselves in the various conditions revealed no abnormalities in homeostatic parameters: sleep stage variables, relative power spectra and time courses of power in various frequency bands across the first three non-rapid eye movement-rapid eye movement (NREM-REM) cycles showed no differences. The data suggest that homeostatic processes are not involved in the disturbance of sleep in SAD.     

Frequency dependence of spike timing reliability in cortical pyramidal cells and interneurons

Pyramidal cells and interneurons in rat prefrontal cortical slices exhibit subthreshold oscillations when depolarized by constant current injection. For both types of neurons, the frequencies of these oscillations for current injection just below spike threshold were 2--10 Hz. Above spike threshold, however, the subthreshold oscillations in pyramidal cells remained low, but the frequency of oscillations in interneurons increased up to 50 Hz. To explore the interaction between these intrinsic oscillations and external inputs, the reliability of spiking in these cortical neurons was studied with sinusoidal current injection over a range of frequencies above and below the intrinsic frequency. Cortical neurons produced 1:1 phase locking for a limited range of driving frequencies for fixed amplitude. For low-input amplitude, 1:1 phase locking was obtained in the 5- to 10-Hz range. For higher-input amplitudes, pyramidal cells phase-locked in the 5- to 20-Hz range, whereas interneurons phase-locked in the 5- to 50-Hz range. For the amplitudes studied here, spike time reliability was always highest during 1:1 phase-locking, between 5 and 20 Hz for pyramidal cells and between 5 and 50 Hz for interneurons. The observed differences in the intrinsic frequency preference between pyramidal cells and interneurons have implications for rhythmogenesis and information transmission between populations of cortical neurons.     

Cloning and expression of the major secreted cathepsin B-like protein from juvenile Fasciola hepatica and analysis of immunogenicity following liver fluke infection

The functions of the cathepsin B-like proteases in liver flukes are unknown and analysis has been hindered by a lack of protein for study, since the protein is produced in small amounts by juvenile flukes. To circumvent this, we isolated and characterized a cDNA encoding the major secreted cathepsin B from Fasciola hepatica. The predicted preproprotein is 339 amino acids in length, with the mature protease predicted to be 254 amino acids long, and shows significant similarity to parasite and mammalian cathepsin B. Only one of the two conserved histidine residues required for cathepsin B exopeptidase activity is predicted to be present. Recombinant preproprotein was produced in yeast, and it was shown that the recombinant proprotein can undergo a degree of self-processing in vitro to the mature form, which is active against gelatin and synthetic peptide substrates. The recombinant protein is antigenic in vaccinated rats, and antibodies to the protein are detected early after infection of rats and sheep with F. hepatica. The kinetics of the response to cathepsin B and cathepsin L after infection of sheep and rats confirm the temporal expression of these proteins during the life cycle of the parasite.     

Paradoxical effect of QX-314 on persistent inward currents and bistable behavior in spinal motoneurons in vivo

Spinal motoneurons can exhibit bistable behavior, which consists of stable self-sustained firing that is initiated by a brief excitatory input and terminated by brief inhibitory input. This bistable behavior is generated by a persistent inward current (I(PIC)). In cat motoneurons with low input conductances and slow axonal conduction velocities, I(PIC) exhibits little decay with time and thus self-sustained firing is long-lasting. In contrast, in cells that have high input conductances and fast conduction velocities, I(PIC) decays with time, and these cells cannot maintain long duration self-sustained firing. An alternative way to measure bistable behavior is to assess plateau potentials after the action potential has been blocked by intracellular injection of QX-314 to block sodium (Na(+)) currents. However, QX-314 also blocks calcium (Ca(2+)) currents and, because I(PIC) may be generated by a mixture of Ca(2+) and Na(+) currents, a reduction in amplitude of I(PIC) was expected. We therefore systematically compared the properties of I(PIC) in a sample of cells recorded with QX-314 to a control sample of cells without QX-314, which was obtained in a previous study. Single-electrode voltage-clamp techniques were applied in spinal motoneurons in the decerebrate cat preparation following administration of a standardized dose of the noradrenergic alpha1 agonist methoxamine. In the sample with QX-314, the average value of I(PIC) was only about half that in the control sample. However, the reduction of I(PIC) was much greater in cells with slow as compared with fast conduction velocities. Because a substantial portion of I(PIC) originates in dendritic regions and because conduction velocity covaries with the extent of the dendritic tree, this result suggests that QX-314 may fail to diffuse very far into the dendrites of the largest motoneurons. The analysis of the decay of I(PIC) and plateau potentials in cells with QX-314 also produced an unexpected result: QX-314 virtually eliminated time-dependent decay in both I(PIC) and plateau potentials. Consequently, I(PIC) became equally persistent in high and low input conductance cells. Therefore the decay in I(PIC) in high input conductance cells in the absence of QX-314 is not due to an intrinsic tendency of the underlying inward current to decay. Instead it is possible that the decay may result from activation of a slow outward current. Overall, these results show that QX-314 has a profound effect on I(PIC) and thus plateau potentials obtained using QX-314 do not accurately reflect the properties of I(PIC) in normal cells without QX-314.