Fed-batch cultivation of methanobacterium formicicum and its fluorometric monitoring

Fed-batch cultivation of Methanobacterium formicicum Z-281 was performed under substrate limiting conditions. Specific rate of culture growth amounted to 0.041 h^?1, cell yield related to substrate was 0.6 mg proteine/mM formate. Significant increase of coenzyme F₄₂₀ content in cells depending on time of cultivation was observed. Increase of the fluorescence intensity of the medium was also observed with the accumulation of biomass. These parameters were suggested for tracking culture growth. The possibility of application of fluorescent factors for methanogenic population control in the anaerobic digester is discussed.     

Inhibitor of protein synthesis blocks longterm behavioral sensitization in the isolated gill-withdrawal reflex of Aplysia

To study the effect of protein synthesis inhibition on long-term sensitization of the gill- and siphon-withdrawal reflex of Aplysia, we have developed an isolated reflex preparation in which we could expose the inhibitor to only that part of the central nervous system involved in mediating the reflex and not to the other parts of the animal's central nervous system, thus minimizing the possible systemic side effects. We have found that long-term sensitization can be obtained in the isolated gill reflex, and that this long-term process, but not the short-term process, is blocked selectively by anisomycin, a reversible inhibitor of protein synthesis. Moreover, to obtain this blockade of long-term sensitization, this drug need only be applied during the training procedure.     

Coagulation and fibrinolysis in acute mountain sickness and beginning pulmonary edema

To examine whether intravascular coagulation and/or decreased fibrinolysis precedes high-altitude pulmonary edema (HAPE) we examined 25 male mountaineers (median age 40 yr) at low altitude (550 m) and after 6, 18, and 42 h at an altitude of 4,559 m, which was climbed in 24 h. In 14 subjects, 2 of whom showed radiological evidence of HAPE after 42 h, symptoms of acute mountain sickness (AMS) were mild or absent. Eleven subjects suffered from AMS, six of whom developed radiologically documented HAPE after 18 or 42 h. In the absence of AMS there were no significant changes at high altitude, with the exception of a decrease in bleeding time from 246 +/- 18 to 212 +/- 13 (SE) (P less than 0.05). In AMS, partial thromboplastine time decreased from 34.2 +/- 0.8 to 31.1 +/- 0.5 s (P less than 0.001) and factor VIII procoagulant activity and von Willebrand factor antigen were increased by 57 +/- 12 and 70 +/- 13%, respectively (P less than 0.001), whereas there were no significant changes in beta-thromboglobulin (BTG), fibrinopeptide A (FPA), and fibrin fragment B beta 15-42. In subjects with HAPE, BTG, FPA, and B beta 15-42 were normal before and in beginning HAPE. Preceding HAPE, euglobulin clot lysis time declined at high compared with low altitude from 289 +/- 48 to 201 +/- 42 min without venous occlusion (VO) and from 107 +/- 36 to 86 +/- 31 min after VO (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Heterozygotes for cystic fibrosis: models for study of airway and autonomic reactivity

Airway reactivity to cold air and methacholine, alpha-adrenergic and cholinergic reactivity measured as pupillary responses to phenylephrine and carbachol, respectively, and beta-adrenergic reactivity assessed by lymphocyte adenosine 3',5'-cyclic monophosphate (cAMP) response to isoproterenol were compared in 108 parents of patients with cystic fibrosis (CF) and 133 healthy adult controls. No differences were found between CF parents and controls in airway response to cold air or methacholine or in lymphocyte cAMP response to isoproterenol. Significant differences were found, however, in the response of the pupils to both phenylephrine and carbachol. Heterozygotes for CF have more reactive pupils; i.e., they require smaller doses of agonist for a 10% change in pupil size. In control subjects, the response of the pupils to phenylephrine and carbachol is highly correlated (r = 0.45, P less than 0.001), whereas in CF heterozygotes, the correlation is not significantly different from zero (r = -0.02). In controls, the pupil response to carbachol has a significant negative correlation with cold air response (r = 0.39, P less than 0.05), indicating that those whose pupils were most sensitive to carbachol had the greatest airway reactivity to cold air, but in CF heterozygotes the correlation is not significant (r = 0.10). A significant correlation exists between lymphocyte cAMP response and airway cold air response in CF heterozygotes (r = -0.32, P less than 0.05) (those whose beta-adrenergic responsiveness is low have greater airway reactivity), but not in controls. The CF parents with the most reactive airways tend to have lower beta-adrenergic responses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Respiratory epithelial permeability after cigarette smoke exposure in guinea pigs

The purpose of this study was to determine the pathology of cigarette smoke-increased permeability at the bronchioalveolar junction of the guinea pig. After exposure to either smoke or room air, guinea pigs were anesthetized and fluorescein isothiocyanate-dextran (FITC-D, mol wt 10,000) was aerosolized into their lungs. Blood samples taken through a carotid arterial cannula were analyzed by gel chromatography and spectrofluorometry for the presence of FITC-D. The results confirmed that, after smoke exposure, increased amounts of intact FITC-D molecules with a reported Einstein-Stokes radius of 22.2 A crossed the respiratory epithelium into the vascular space. Transmission electron-microscopic studies showed that the FITC-D diffused across damaged type I pneumocyte membranes and cytoplasm to reach the basal lamina and entered the alveolar capillaries through endothelial tight junctions. Damage to the alveolar epithelium was more frequent for the smoke-exposed animals than the room air-exposed animals (P less than 0.05). We conclude that smoke exposure damages type I cells and that inhaled FITC-D crosses the epithelial barrier at damaged type I cells of the bronchioloalveolar junctions.     

Recovery of diaphragm function after laparotomy and chronic sonomicrometer implantation

If sonomicrometry transducers could be implanted permanently into the diaphragm, direct measurements of costal and crural length and shortening could be made during recovery from the laparotomy and then indefinitely in an awake, non-anesthetized mammal. We report results from six canines in which we successfully implanted transducers onto the left hemidiaphragm through a midline laparotomy and measured segmental shortening and ventilation at intervals through 22 days of postoperative recovery. After laparotomy, breathing pattern, including tidal volume, respiratory rate and mean inspiratory flow, stabilized by the 4th postoperative day (POD). Tidal shortening of costal and crural segments increased from 1.82 and 1.45% of end-expiratory length (%LFRC) on the 2nd POD to 5.32 and 8.56% LFRC, respectively, after a mean of 22 POD. Segmental shortening did not stabilize until 10 POD, and the recovery process displayed a sequence of segmental motions: lengthening, biphasic inspiratory lengthening-shortening, and increasing simple shortening. Three weeks after implantation, costal and crural segments were stable and shortening 5.32 and 8.56% LFRC, respectively, and capable of shortening 49% LFRC with maximal phrenic stimulation. In a pair of recovered animals, the initial postoperative dysfunction did not recur after a subsequent, simple laparotomy. At postmortem examination, the chronically implanted sonomicrometer transducers were found to have evoked only a thin fibrotic capsule within the diaphragm.     

Diaphragmatic plate electrode stimulation of the hamster diaphragm

We developed a new technique of diaphragmatic stimulation by apposing plate electrodes directly against the diaphragm (DPS) in adult Golden Syrian hamsters. The electrophysiological and the mechanical responses to DPS were compared with those with phrenic nerve stimulation. In four animals, evaluation of the electromyogram before and after curare demonstrated that plate electrode stimulation occurred via the phrenic nerve filaments. In four animals, similar transdiaphragmatic pressure was produced at maximal current with DPS and phrenic nerve stimulation. Using DPS increasing current beyond a certain level resulted in recruitment of muscles besides the diaphragm. In six animals, an external abdominal pressure of 15 cmH2O produced maximal transdiaphragmatic pressure, suggesting that the diaphragm was contracting near optimal position with this external abdominal pressure. In another four animals the twitch and pressure-frequency characteristics with the use of DPS were found to be reproducible over a 2-h period. We conclude that DPS is an effective method of diaphragmatic stimulation and should prove to be a valuable technique to study the diaphragm in long-term studies of small rodents.     

Short-term action of insulin on Aplysia neurons: Generation of a possible novel modulator of ion channels

In mollusks as in other animals, peptides can act as hormones, growth factors, and neurotransmitters. The presence of insulin in vertebrate brain as well as its actions on nerve cells led us to examine the electrophysiological effects of the mammalian hormone on Aplysia neurons. Application of insulin extracellularly causes hyperpolarization of L14 and L10, identified neurons of the abdominal ganglion. This hyperpolarization is associated with a decreased membrane conductance that reverses at ?35 mV. We also injected inositol phosphate glycan (IPG) into the identified neurons. This complex sugar, which was purified from rat liver and which is a putative second messenger for insulin in nonneural vertebrate cells (Saltiel and Cuatrecasas, 1986; Saltiel, Osterman, and Darnell, 1988), causes hyperpolarization with decreased membrane conductance in L14 and L10 similar to the effects of insulin. Furthermore, exposure of isolated ganglia to insulin results in the generation of IPG with a compensating decrease in its glycosyl-phosphatidylinositol precursor. We suggest that, in addition to its other roles, insulin may function as a neuropeptide transmitter using IPG as a second messenger.     

Submerged reefs and terraces on the shelf edge of the Great Barrier Reef,Australia

The morphology and distribution of seabed features on the shelf edge and upper slope adjacent to the Great Barrier Reef, Australia, has been examined using shallow seismic profiling, side-scan sonar and precision echo sounding data, supplemented by submersible investigations. The data reveal a submerged barrier reef system at different locations between 15° 45 S and 21° 00 S. At two locations, an extensive offshore platform rising above the 50 m isobath and extending for over 20 km parallel to the shelf edge is backed by a relict lagoon at an average depth of 75 m. In addition, outer shelf and upper slope terraces are found at many depths; however, only some occur consistently throughout the region while most others occur only locally. Frequency distributions indicate the greatest occurrence of features at depths of 44–46, 60–66, 72–78, 80–84, 102–106 and 146–148 m. Caution should be exercised when interpreting these features with respect to specific lower sea level stands.