Influence of pulmonary inflations on discharge patterns of phrenic motoneurons

The purpose of this study was to assess the influence of pulmonary inflations on activities of single phrenic motoneurons. Studies were performed in decerebrate and paralyzed cats; activities of phrenic nerve and single phrenic motoneurons were recorded. Animals were ventilated with a servo-respirator which produced alterations in tracheal pressure in parallel with changes in integrated activity of the phrenic nerve. At end-tidal fractional concentrations of CO2 of 0.05, phrenic motoneurons were distributed into "early" and "late" populations, depending on time of onset of activity. During the late stages of neural inspiration, differences in levels of integrated activity of the phrenic nerve became evident between cycles with and without lung inflations. At a time approximating 90% of the inspiratory duration during inflations, integrated phrenic activity was higher for cycles with inflation. Concomitantly, with lung inflations, the discharge frequencies of early phrenic motoneurons were lower, and late motoneurons began to discharge sooner than when inflations were withheld. Similar results were obtained in hypercapnia. We conclude that reflexes activated by pulmonary inflations may produce augmentation, as well as inhibition of phrenic motoneuronal activities. Factors responsible for eliciting these reflex augmentations and inhibitions are discussed.     

Seroresponse (IgG) after Vaccination and Natural Infection of Cattle with Babesia Divergens

The antibody response against Babesia divergens in vaccinated calves and in unvaccinated sentinels on farms where vaccination had been practiced routinely, was investigated using a live vaccine. Sera were obtained before and 3 weeks after vaccination in March and April, approximately 1 month before the animals were put out on pasture. Additional blood samples were collected at the end of the grazing season and again the next spring. At that time previously unvaccinated sentinel calves were vaccinated and their antibody response was tested 3 weeks later. All sera were analysed by an IF-technique. All of the vaccinated calves (100%) were seropositive 3 weeks after vaccination. The seroresponse did not differ signifacantly between animals vaccinated before their first or second grazing season although the age difference was about 12 months. No clinical symptoms of babesiosis were seen in vaccinated animals. The titres were, however, significantly higher 3 weeks after vaccination than 6 months later. After the grazing season about 42% of the unvaccinated sentinel calves were sero–positve. Two of these calves had clinical babesiosis on pasture in July and September respectively. The number of sentinel calves which became infected on pasture showed a large farm-to-farm variation although all cattle on the farms once had been infected-/vaccinated with B. divergens. Probably the different number of calves infected was a reflection of a variation in tick density on the different pastures. All calves, which were seropositive after the grazing season, were also seropositive after 6 months indoors. The titres declined during the winter period, but they were still within the range of 2 doubling dilution steps.     

Tannic acid characterized membranes of animal cells

Summary Tannic acid affects one face of some cytoplasmic membranes causing them to appear thin in electron micrographs.Trans vesicles of Golgi apparatus, dictyosome-like-structures, headcaps and aerosomes of germ cells, and certain lysosomes all have membranes that appear thin after tannic acid fixation and, in addition, are all characterized as being acid phosphatase positive. Thus, thin membranes appear functionally related and to be associated with cellular components that have lysosome or lysosome-like character.     

A rapid, simple and reliable combined method for G-banding mammalian and human chromosomes

A simple and reliable method for G-banding chromosomes from human and mammalian cells is described. This rapid method combines hot saline and trypsin treatments and yields high quality G-bands in both bone marrow and cultured cells.     

Pharmacological profile of a novel carbacyclin derivative with high metabolic stability and oral activity in the rat

A novel carbacyclin derivative (16S)-13,14-dehydro-16,20-dimethyl-3-oxa-18,18,19,19-tetradehydro- 6a- carbaprostaglandin-I2 (3-oxa-analogue) has been synthesized in order to find chemically and metabolically stable prostacyclin-mimetics with a potency equal or even superior to PGI2. The 3-oxa-analogue was found to be stabilized against beta-oxidation, a main metabolic degradation step also for chemically stable PGI2-analogues. The compound is orally available and displays a long duration of 4.5-48 h of antiaggregatory and hypotensive action. The 3-oxa-analogue inhibits ADP-induced platelet aggregation with an IC50 of 3.0 nM. Following intravenous application the 3-oxa-analogue lowers diastolic blood pressure in a dose dependent manner, the ED20 being 0.1-0.2 micrograms/kg after injection and less than or equal to 0.05 micrograms/kg/min after infusion respectively. In vivo platelet aggregation is inhibited after i.v. infusion of the 3-oxa-analogue with an IC50 of 0.037 micrograms/kg/min. As compared to Iloprost, the 3-oxa-analogue is 5-12 fold more potent with respect to in vivo hypotensive and anti-aggregatory effects. The results of the present studies indicate that the 3-oxa-analogue has a pharmacological profile comparable to prostacyclin (PGI2) and Iloprost. Due to the fact that the 3-oxa-analogue is chemically and metabolically stable, long term oral treatment can be achieved in clinical conditions in which PGI2 and Iloprost have already been shown to be therapeutically useful principles.     

Leukotriene B3, leukotriene B4 and leukotriene B5; binding to leukotriene B4 receptors on rat and human leukocyte membranes

Specific high-affinity binding sites for [3H]-leukotriene B4 have been identified on membrane preparations from rat and human leukocytes. The rat and human leukocyte membrane preparations show linearity of binding with increasing protein concentration, saturable binding and rapid dissociation of binding by excess unlabelled leukotriene B4. Dissociation constants of 0.5 to 2.5 nM and maximum binding of 5000 fmoles/mg protein were obtained for [3H] leukotriene B4 binding to these preparations. Displacement of [3H]-leukotriene B4 by leukotriene B4 was compared with displacement by leukotriene B3 and leukotriene B5 which differ from leukotriene B4 only by the absence of a double bond at carbon 14 or the presence of an additional double bond at carbon 17, respectively. Leukotriene B3 was shown to be equipotent to leukotriene B4 in ability to displace [3H]-leukotriene B4 from both rat and human leukocyte membranes while leukotriene B5 was 20-50 fold less potent. The relative potencies for the displacement of [3H]-leukotriene B4 by leukotrienes B3, B4 and B5 on rat and human leukocyte membranes were shown to correlate well with their potencies for the induction of the aggregation of rat leukocytes and the chemokinesis of human leukocytes.     

Ultrastructure and Host Specificity of Bacteriophages of Streptococcus cremoris, Streptococcus lactis subsp. diacetylactis, and Leuconostoc cremoris from Finnish Fermented Milk "Viili"

"Viili," a fermented milk product, has a firm but viscous consistency. It is produced with traditional mesophilic mixed-strain starters, which have various stabilities in dairy practice. Thirteen morphologically different types of phages were found in 90 viili samples studied by electron microscopy. Ten of the phage types had isometric heads with long, noncontractile tails, two had elongated heads with long, noncontractile tails, and one had a unique, very long elongated head with a short tail. Further morphological differences were found in the tail size and in the presence or absence of a collar, a baseplate, and a tail fiber. To find hosts for the industrially significant phages, we examined the sensitivities of 500 bacterial isolates from starters of the viili. Seven of the phages attacked Streptococcus cremoris strains, three attacked S. lactis subsp. diacetylactis strains, and four attacked Leuconostoc cremoris strains. Some phages differed only in their host specificity. Hosts were not found for 4 of the 13 morphological types of phages.     

Vasoactive intestinal peptide (VIP) binding to solubilized material from rat liver plasma membranes

A non-ionic detergent such as Lubrol-PX extracts in soluble form the VIP-binding structures of rat liver plasma membranes. Detergent-solubitized proteins bind specifically [¹²⁵I]VIP and the complex tracer-protein is identified by the use of Sepharose 6B columns. The interaction is only possible in the absence of detergent (below 0.001%) and is inhibited by native peptide. A molecular weight of about 80,000 was estimated for VIP-binding proteins by reference to a series of globular markers of proteins. Binding to VIP soluble proteins is specific and dependent on time as studied by the Hummel and Dreyer (Biochim. Biophys. Acta 63:530–532, 1962) assay.     

Antigenic probes locate the myosin subfragment 1 interaction site on the N-terminal part of actin

The interaction of two different anti-actin antibody populations with the myosin subfragment 1-F-actin rigor complex has been studied. In contrast with the 1–7 sequence, the 18–28 sequence appears to be strongly implicated in the contact area of the myosin head on the actin polypeptide chain.