Rate measurements of the hydrolysis of complex organic macromolecules in cold aqueous solutions: implications for prebiotic chemistry on the early Earth and Titan.

Organic macromolecules ("complex tholins") were synthesized from a 0.95 N(2)/0.05 CH(4) atmosphere in a high-voltage AC flow discharge reactor. When placed in liquid water, specific water soluble compounds in the macromolecules demonstrated Arrhenius type first order kinetics between 273 and 313 K and produced oxygenated organic species with activation energies in the range of approximately 60+/-10 kJ mol(-1). These reactions displayed half lives between 0.3 and 17 days at 273 K. Oxygen incorporation into such materials--a necessary step toward the formation of biological molecules--is therefore fast compared to processes that occur on geologic timescales, which include the freezing of impact melt pools and possible cryovolcanic sites on Saturn's organic-rich moon Titan.

Development of ion source with a washer gun for pulsed neutral beam injection.

A new type of economical neutral beam source has been developed by using a single washer gun, pulsed operation, and a simple electrode system. We replaced the conventional hot filaments for arc-discharge-type plasma formation with a single stainless-steel washer gun, eliminating the entire dc power supply for the filaments and the cooling system for the electrodes. Our initial experiments revealed successful beam extraction up to 10 kV and 8.6 A, based on spatial profile measurements of density and temperature in the plasma source. The system also shows the potential to control the beam profile by controlling the plasma parameters in the ion accumulation chamber.

A short-term in vitro assay for promoter substances using human lymphoblastoid cells latently infected with Epstein-Barr virus.

We designed a short-term in vitro assay for detecting tumor promoters, utilizing the activation of Epstein-Barr virus (EBV) expression in EBV genome-carrying human lymphoblastoid cells. This system is composed of EBV-non-producer Raji cells as the indicator, n-butyrate as the EBV-inducer, and the test substance. After addition of the latter 2 components to the culture medium, the cells are cultivated for 48 h at 37 degrees C and the ratio of EBV early antigen (EA)-expressing cells was assessed using immunofluorescence. This assay system allows for a rapid detection of the activity of the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and its related compounds and also of the Euphorbiaceae plant extracts containing such active principles. Among several microbial products tested, teleocidin, an indole-alkaloid produced by a Streptomyces species, was also detected and had an activity level comparable to that of TPA. Other promoters, such as anthralin, phenol, Tween 60 and 80 and the carcinogenic ("initiator") substances including benzopyrene, did not react with the system. The test is simple to perform, reproducible and should be applicable for mass-screening of promoter substances in the environment.

Hypoplastic left heart syndrome associated with congenital right-sided diaphragmatic hernia and omphalocele.

Congenital diaphragmatic hernia (CDH) is associated with a variety of cardiac anomalies. However, its association with hypoplastic left heart syndrome (HLHS) is rare. We treated a female newborn with CDH, HLHS, and omphalocele. The operation for omphalocele and the diaphragmatic defect was successful, although the patient died of cardiac failure after Norwood's operation for HLHS. To our knowledge, this is the first reported case with a combination of these three major anomalies: CDH, HLHS, and omphalocele.

Performance characteristics of bilevel pressure ventilators: a lung model study.

Bilevel pressure ventilators are being used increasingly to provide noninvasive ventilatory support in the management of obstructive sleep apnea, chronic ventilatory failure, and acute respiratory failure. However, the ability of these ventilators to respond to inspiratory demand without imposing expiratory loads has not been evaluated extensively. We evaluated the performance of nine bilevel pressure ventilators in a lung model, as compared with the Nellcor Puritan-Bennett 7200ae adult critical care ventilator. All ventilators were set to provide pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP) at a rate of 10 breaths/min with an inspiratory time of 1.0 s. Simulated pleural pressure, airway pressure, and flow at airway opening were continuously monitored. We studied the effects of three PSV levels (5, 10, and 15 cm H2O) with 5 cm H2O PEEP at two lung compliances (50 and 80 mL/cm H2O) and four peak inspiratory flow demands (20, 40, 60, and 80 L/min) on seven dependent variables: inspiratory delay time (D-I), inspiratory trigger pressure (P-I), inspiratory area percent (Area I%), expiratory delay time (D-E), supraplateau expiratory pressure change (P-E), expiratory area (Area E), and ventilator peak flow (VPF). Most ventilators performed as well as or significantly (p<0.05) better than the 7200ae in all studied variables. Compliance did not significantly affect ventilator performance. Increasing inspiratory flow demand significantly (p<0.05) increased D-I, P-I, P-E, and VPF and decreased Area I% with most ventilators. As ventilatory demand increased, D-E and Area E significantly (p<0.05) changed. With some units, D-E and Area E increased, while with others they decreased. Most bilevel pressure ventilators evaluated were able to respond to high ventilatory demands and outperformed the Nellcor Puritan-Bennett 7200ae ventilator.

Jet flow-regulated expiratory resistance to maintain constant CPAP during the entire respiratory phase.

We have developed a new continuous positive airway pressure (CPAP) device that consists of a microcomputer, a pressure transducer, and a pair of electronic interface valves. One of these valves creates the inspiratory demand flow, and the other creates the opposing jet flow by acting as an expiratory valve to maintain a constant CPAP. By controlling the two electronic interface valves, the airway pressure can be kept constant during the entire respiratory cycle. We compared our device with CPAP systems supplied with commercially available ventilators: the Puritan-Bennett 7200a, the Bear 5, the Servo 900C, and the CV 2000. A two-chambered spring loaded model lung was used to simulate inspiration and a piston pump model lung to simulate active exhalation. We compared both the inspiratory triggering work (WWIt) and expiratory flow-resistive work (WE) of each ventilator while in CPAP mode by calculating the corresponding areas of the pressure-volume loops using electrical integration. The WWIt of our apparatus and demand-flow ventilators was much smaller than that of the CV 2000. In our device, WE was also much smaller than those of the others. These results indicate that our device can be used for CPAP without causing airway pressure fluctuation, and therefore, without imposing an extra workload on the patient.

Capnometry during high-frequency oscillatory ventilation.

We used capnometry during high-frequency oscillatory ventilation (HFOV), and compared CO2 measurements at the distal and proximal ends of an endotracheal tube with arterial CO2 values. Ten white rabbits (mean weight, 2.00 +/- 0.2 [SD] kg) underwent tracheostomy under anesthesia with pentobarbital. The trachea was intubated with an endotracheal tube with a second lumen for sampling respiratory gas at the distal tip. Capnometry was performed through the lumen (CO2d) and the proximal end of the endotracheal tube (CO2p). The internal carotid artery was cannulated to sample blood for measuring arterial blood gases. The differences between CO2d, CO2p, and PaCO2 were measured. Only the relation between CO2d and PaCO2 was good (r = 0.915). We concluded that capnometry can be used during HFOV to estimate PaCO2 provided that respiratory gas is sampled from the distal tip of the endotracheal tube.

Effects of nitric oxide inhalation after pulmonary thromboendarterectomy for chronic pulmonary thromboembolism.

STUDY OBJECTIVES: To examine the hypothesis that nitric oxide (NO) inhalation improves hemodynamics and gas exchange in patients with chronic pulmonary thromboembolism after pulmonary thromboendarterectomy. DESIGN: Prospective crossover clinical study. SETTING: : Surgical ICU in a national education and research hospital. PATIENTS: : Seven patients (mean age +/- SD, 54 +/- 11 years) who underwent elective pulmonary thromboendarterectomy for chronic pulmonary thromboembolism. INTERVENTIONS: Patients breathed 20 parts per million of NO gas for 30 min at 12-h intervals until extubation of the trachea. MEASUREMENTS AND RESULTS: Hemodynamics and arterial blood gas levels were analyzed before, during, and after NO inhalation. Waveform of pulmonary artery pressure (PAP) was evaluated using fractional pulse pressure (PPf): (systolic PAP - diastolic PAP)/mean PAP. After surgery, pulmonary vascular resistance decreased, PPf decreased, and cardiac index increased significantly. At the first trial, NO inhalation resulted in a slight improvement in arterial oxygen tension (from 173 +/- 33 to 196 +/- 44 mm Hg; p < 0.05), while hemodynamics did not change significantly. Twelve hours later, NO inhalation decreased pulmonary vascular resistance index (from 312 +/- 98 to 277 +/- 93 dyne.s. cm(-5)/m(2); p < 0.01), while the change in oxygenation was not significant. CONCLUSIONS: Immediately after pulmonary thromboendarterectomy for chronic pulmonary thromboembolism, NO inhalation improved oxygenation; at 12 h after surgery, NO inhalation resulted in decreased pulmonary vascular resistance, although both changes were small.

Measurement of functional residual capacity during high-frequency oscillatory ventilation (HFOV) by argon washout method without interruption of HFOV.

A modified indicator gas washout method was developed to measure functional residual capacity (FRC) during high-frequency oscillatory ventilation (HFOV) without interruption of HFOV. A hot-wire flowmeter and medical gas analyzer measured the flow rate and argon concentration, respectively, at the expiratory end of the respiratory circuit. Upstream of the hot-wire flowmeter, two heat-and-moisture exchangers for resistance and a rubber balloon for capacitance were placed to convert the oscillating expiratory flow to an almost continuous flow. This made it possible to measure FRC during HFOV without interrupting HFOV. To measure the volume of the entire respiratory circuit, a 10 percent argon in 90 percent oxygen gas mixture was initially used as a bias flow, and after equilibration, the test gas was switched to 100 percent oxygen. By electrical integration of the product of the expiratory flow rate and argon concentration, the total amount of argon equilibrated in the entire respiratory circuit was calculated. The volume of the circuit was calculated by dividing the total amount of argon by the initial argon concentration. Functional residual capacity plus the volume of the respiratory circuit was similarly calculated and the difference was estimated as FRC. The accuracy and reproducibility of our method were evaluated by using a one-compartment lung model. There was a high correlation between the volume setting of the model lung and the estimated FRC. This method can be used to estimate FRC in a one-compartment lung model during HFOV, and it is potentially useful in clinical situations.

Mechanism of gravity-dependent atelectasis. Analysis by nonradioactive xenon-enhanced dynamic computed tomography.

RATIONALE AND OBJECTIVES: The physiologic mechanism of gravity-dependent atelectasis (GDA), a common finding identified during anesthesia, is not well understood. The purpose of this study was to determine whether an inherent reduction in alveolar volume or a reduction in alveolar ventilation is the more important causative factor for the development of GDA in an experimental animal model. METHODS: After uniform reduction of lung volume in ten rabbits by artificially induced pneumoperitoneum, dynamic inhalation computed tomography (CT) was performed using 50% nonradioactive xenon in oxygen. Time-CT attenuation value curves were fitted to an exponential function, CT value = a - b x e(-kt), and K value, which is proportional to the alveolar ventilation/alveolar volume ratio, was calculated by regression analysis. RESULTS: Gravity-dependent atelectasis occurred only in 5 of 10 rabbits. In this group, K values in the dorsal regions increased before the appearance of GDA. No significant change in K values in the ventral regions was observed. CONCLUSION: One mechanism of GDA may be a preferential reduction in alveolar volume without small airway collapse rather than alveolar volume loss secondary to decreased ventilation.

Gravity-dependent atelectasis. Radiologic, physiologic and pathologic correlation in rabbits on high-frequency oscillation ventilation.

The authors identify the radiologic features of progressive atelectasis induced under conditions of reduced lung volume. Control (n = 5) and experimental (n = 7) animals were placed on high-frequency oscillation (HFO) ventilation (mean airway pressure: 3 cm H2O) for 6 hours. In the experimental animals, lung volume was artificially reduced by pneumoperitoneum during HFO ventilation. Computed tomography scans and chest radiographs were obtained every hour, and arterial blood gases analyzed. No changes were detected in the control animals. In the experimental animals, in which hypoxemia developed, homogeneous opacity in the dependent lung was found on CT images, and chest radiographs showed a diffuse homogenous shadow with loss of lung volume. Study of pathologic sections from the lung showed that the roentgenographic findings represented atelectasis. The lung was divided into three zones, from dependent to nondependent regions: severe atelectasis, mild atelectasis, and normal lung. Hyperinflations eliminated atelectasis seen on the CT images and alleviated hypoxemia; however an undesirable effect that causes barotrauma also was observed.

Recovery of diaphragmatic function in awake sheep after two approaches to thoracic surgery.

Video-assisted thoracoscopic surgery (VATS) is replacing thoracotomy, but no study has addressed the extent or duration of VATS-induced diaphragmatic alteration. We hypothesized that VATS would impair diaphragmatic function less and return diaphragmatic function faster than thoracotomy. In eight sheep, sonomicrometers were randomly implanted on the right costal diaphragm via VATS or thoracotomy. Diaphragmatic resting length, shortening fraction, and respiratory function were measured weekly during quiet breathing (QB) and CO2 rebreathing for 4 wk. For VATS, shortening fraction was smallest on postoperative days 1 (POD 1) (6.4 +/- 3.4 and 12.9 +/- 8.7% during QB and 10% CO2 rebreathing, respectively) and 7 (6.3 +/- 3.4 and 16.9 +/- 4.0% during QB and 10% CO2 rebreathing, respectively) and recovered by 3 wk (13.2 +/- 1.8 and 28.9 +/- 8.0% during QB and 10% CO2 rebreathing, respectively). For thoracotomy, shortening fraction at 10% CO2 rebreathing was smaller on PODs 1, 7, 14 (15.9 +/- 7.1, 13.6 +/- 5.4, and 19.0 +/- 6.9%) than on POD 28 (29.9 +/- 8.2%), but not during QB on POD 1 or 7 (7.5 +/- 3.8 and 3.4 +/- 2.6%) compared with POD 28 (10.7 +/- 8.7%). Shortening fraction did not differ between surgeries. There was no group difference in minute ventilation, respiratory rate, transdiaphragmatic pressure, or esophageal and gastric pressures. In conclusion, although shortening fraction recovered faster for VATS, this translated into insignificant functional differences.

In vitro selection of aptamers that act with Zn2+.

An in vitro selection was carried out with Zn2+ to isolate novel RNA molecules, zinc-dependent aptamers, that bind to HIV-1 Tat protein. RNAs bound to Tat were collected by using a nitrocellulose filter from a library of random RNAs and regenerated to the next generation of the RNA library by subsequent reverse transcription, polymerase chain reaction, and transcription. Sequences of the selected RNAs were determined after 6 and 12 rounds of the selection. The control clones after normal selection procedure with Mg2+ had a consensus UUG that resembled essential sequences of TAR or Arg aptamers. On the other hand, many unique sequences were revealed from a library selected with Zn2+ and the RNA with most abundant sequence (clone 31) bound to Tat tightly only when Zn2+ existed. The secondary structure of clone 31 RNA was predicted by using a computational prediction with our thermodynamic parameters and enzymatic scission of the RNA. Several model RNAs were prepared and the binding property of these RNAs to Tat were investigated. As a result, all the model RNAs did not reproduce the binding property of clone 31. Therefore, the Tat aptamer that acts with Zn2+ should require a relatively longer region of the sequence which is able to offer tertiary cooperation of several motifs for the binding.

Biosynthesis of bicyclomycin. II. Biosynthetic conditions and incorporation of radioactive precursors into bicyclomycin by washed mycelium.

The biosynthesis of bicyclomycin by Streptomyces sapporonensis was studied using suspensions of washed mycelium. Nicotinamide and Fe2+ were found to be essential cofactors in the biosynthesis. Production of bicyclomycin was enhanced most effectively in the presence of equal moles of L-leucine and L-isoleucine, which in experiments with radioactively labeled compounds were found to be incorporated into bicyclomycin at equivalent rates. These facts strongly suggest that bicyclomycin biosynthesis involves coupling of equal moles of these two amino acids.

Biosynthesis of bicyclomycin. I. Appearance of aerial mycelia negative strains (am-).

The degeneration of bicyclomycin-producing strains of Streptomyces sapporonensis resulted in sharply depressed bicyclomycin formation in a large scale fermentation. Degenerated strains, whose productivities were only 1/30 to 1/100 of normal strains, could not form aerial mycelia on glucose-BENNETT's agar; they were aerial mycelia negative strains (am-). Repeated transfers of culture, treatment of mycelia with acriflavin, mechanical agitation shock on mycelia or higher growth conditions stimulated the degeneration of producing strains, suggesting the involvement of extrachromosomal elements or plasmids in biosynthesis of bicyclomycin. Shake flask fermentation inoculated with a mixture of a normal high-producing strain and a degenerated low-producing strain resulted in sharply depressed bicyclomycin formation in proportion to the increase of low-producing strain added. It appears that the low-producing strain outgrew the high-producing strain.

Enterocin, a new antibiotic taxonomy, isolation and characterization.

Enterocin is a new antibiotic isolated from cultures of two strains of Streptomyces, which were given the names Streptomyces candidus var. enterostaticus WS-8096 and variant M-127 of Streptomyces viridochromogenes. Its elementary analysis and mass spectroscopic measurement suggest the molecular formula is C22H20010. The ultraviolet absorption gave two maximal peaks at 250 nm and 283 nm in methanol. Enterocin has static activities against gram-positive and gram-negative bacteria and no activity against fungi and yeast.

Streptomyces auranticolor Sp. Nov., a new anticoccidial antibiotics producer.

A new species of Streptomyces is described and designated Streptomyces auranticolor (FERM-P No. 5365) which produces new anticoccidial antibiotics, designated as WS-5995 A and WS-5995 B. The organism is characterized by gray spore mass color, spiral spore chain with smooth spores, non-chromogenic reaction, soluble pigment, and carbon utilization characteristics. It differs from previously described streptomycetes on the basis of carbon utilization, and pigment production.

Studies on new phosphonic acid antibiotics. II. Taxonomic studies on producing organisms of the phosphonic acid and related compounds.

A new species of Streptomyces which produces a new cell wall-inhibitory antibiotic, FR-900098 containing phosphonic acid in its molecule, is named and described. The species name proposed, Streptomyces rubellomurinus, refers to the aerial mass color. Streptomyces rubellomurinus subsp. indigoferus also produces FR-900098 and the related compound FR-33289. FR-900098 related compounds, FR-32863 and FR-31564 are produced by Streptomyces lavendulae.

Mechanism of action of bicyclomycin.

Microscopic examination of cultures of Escherichia coli exposed to bicyclomycin revelaed elongated or spheroplast-like cells. At the lethal level, bicyclomycin was shown to inhibit the synthesis of RNA and protein in the growing cells of E. coli 15 THU, whereas DNA and lipid synthesis were not significantly affected. However, the antibiotic did not block RNA and protein synthesis in vitro. Bicyclomycin was observed to inhibit the synthesis of envelope proteins more markedly than that of cytoplasmic proteins. The synthesis of two major envelope proteins was more sensetive to bicyclomycin than that of the other envelope proteins. One (peak I), which was inhibited to the greatest extent, seemed to be identical with a bound form of lipoprotein, and the other (peak V) with a free form of lipoprotein. Bicyclomycin exhibited inhibitory effects on the exclusive biosynthesis of the lipoprotein in histidine-starved cells of E. coli 15 THU. The biosynthesis of the bound form of lipoprotein was more profoundly inhibited by bicyclomycin than that of the free form. These results indicate that the primary action of bicyclomycin may be due to the interference with the biosynthesis of lipoprotein, and its assembly to peptidoglycan.

Biphenomycin C, a precursor of biphenomycin A in mixed culture.

A precursor of biphenomycin A in mixed culture of Streptomyces griseorubiginosus No. 43708 with Pseudomonas maltophilia No. 1928 was isolated and characterized. The structure of the precursor, designated biphenomycin C was determined to be a peptide which is composed of biphenomycin A and arginylserine residue (Fig. 1), on the basis of chemical and spectroscopic evidence.