Antibacterial activity of rufloxacin in theStaphylococcus aureus rat granuloma pouch model

The protective effects of rufloxacin againstStaphylococcus aureus-induced infections were compared with those of ciprofloxacin in the granuloma pouch model in the rat. Two strains with different in vitro sensitivity to the drugs were studied. Rufloxacin concentrations persisted longer than ciprofloxacin in the exudate in the pouch cavity and were about eight times higher. Equal doses of rufloxacin and ciprofloxacin had similar antibacterial activities. However, rufloxacin inhibitedStaphylococcus aureus bacterial growth significantly longer than did ciprofloxacin.     

Guanine nucleotide- and muscarinic agonist-dependent phosphoinositide metabolism in synaptoneurosomes from cerebral cortex of immature rats

Guanine nucleotide-, neurotransmitter-, and fluoride-stimulated accumulation of [³H]inositol phosphates ([³H]InsPs) was measured in [³H]inositol-labeled synaptoneurosomes from cerebral cortex of immature (7-day-old) and adult rats, in order to clarify the role of GTP-binding proteins (G-proteins) in modulating phosphoinositide (PtdIns) metabolism during brain development. GTP(S) [Guanosine 5-O-(3-thio)triphosphate] time- and concentration-dependently stimulated PtdIns hydrolysis. Its effect was potentiated by full (carbachol, metacholine) and partial (oxotremorine) cholinergic agonists through activation of muscarinic receptors. The presence of deoxycholate was required to demonstrate agonist protentiation of the guanine nucleotide effect. The response to GTP(S) was higher in adult than in immature rats, while the effect of cholinergic agonists was similar at the two ages examined. At both ages, histamine potentiated the effect of GTP(S), while norepinephrine was ineffective. At both ages, guanosine 5-O-(2-thio)diphosphate [GDP(S)] and pertussis toxin significantly decreased GTP(S)-induced [³H]InsPs formation. The phorbol ester phorbol 12-myristate 13-acetate (PMA), on the other hand, did not inhibit the guanine nucleotide response in synaptoneurosomes from immature rats. NaF mimicked the action of GTP(S) in stimulating PtdIns hydrolysis. Its effect was not affected by carbachol and was highly synergistic with that of AlCl₃, according to the concept that fluoroaluminate (AlF₄ ^–) is the active stimulatory species. No quantitative differences were found in the response to these salts between immature and adult animals. These results provide evidence that, in both the immature and adult rat brain, neuroreceptor activation is coupled to PtdIns hydrolysis through modulatory G-proteins.     

Site-specific recombination in Escherichia coli between the att sites of plasmid pSE211 from Saccharopolyspora erythraea

Summary pSE211 fromSaccharopolyspora erythraea integrates site-specifically into the chromosome through conservative recombination betweenattP andattB, the plasmid and chromosomal attachment sites. Integration depends on the presence ofint, an open reading frame (ORF) that lies adjacent toattP and encodes the putative integrase. Immediately upstream ofint liesxis (formerly calledorf2) which encodes a basic protein that is thought to exhibit DNA binding.xis andint were cloned in various combinations in pUC18 and expressed constitutively inEscherichia coli from thelac promoter.attP andattB were cloned inStreptomyces orE. coli plasmids containing kanamycin resistance (Km^R) or chloramphenicol resistance (Cm^R) markers. Stable Km^R Cm^R cointegrates formed byattP ×attB orattP ×attP recombination (integration) were obtained inE. coli hosts that expressedint. Co-integrates were not found in hosts expressingint+xis. Excision (intraplasmidatt site recombination) was examined by constructing plasmids carryingattL andattR or twoattP sites separating Cm^R from Km^R and by following segregation of the markers in various hosts. BothattL ×attR andattP ×attP excision depended on bothxis andint inE. coli. pSE211att site integration and excision were not affected by a deletion inhimA, the gene encoding a subunit of integration host factor.     

Inhibition of the transthylakoid gradient of electrochemical proton potential by the local anesthetic dibucaine

The effects of the local anesthetic dibucaine on coupling between electron transport and ATP synthesis-hydrolysis by the coupling-factor complex (CF₀CF₁ ATPase) were investigated in thylakoid membranes from Spinacia oleracea L. cv. Monatol. Evidence is presented that inhibition of ATP synthesis was produced by a specific uncoupling mechanism which was based on dibucaine-membrane surface interactions rather than on the interaction of dibucaine with the ATPase complex. Dibucaine reduced the osmotic space of thylakoid vesicles. At low pH of the medium it stimulated ATP hydrolysis beyond the rates obtained with optimum concentrations of ‘classical’ uncouplers. After addition of dibucaine, there was displacement of membrane-bound Mg²⁺ and strong thylakoid stacking in the presence of only low Mg²⁺ concentrations. Inhibition of ATP synthesis and transmembrane pH gradient increased with medium pH. Hydrolysis of ATP by isolated CF₁ and the CF₀CF₁ complex was only slightly affected by dibucaine. The data are discussed assuming the involvement of localized proton channels on the membrane surface in protonic coupling of electron transport and ATP synthesis. A hypothesis for the mechanisms of action of local anesthetics at the thylakoid membrane is presented.     

Role of vasopressin in the modifications of renal function during aging]

In the course of aging, the renal concentrating ability is markedly reduced. This defect may result from an inappropriate synthesis of antidiuretic hormone in the central nervous system or may be due to an impaired renal response to vasopressin. The two hypotheses have been studied in vivo in rats and in vitro in mice. The results of these studies indicated that: 1) dehydration induces a comparable release of vasopressin along the hypothalamo-hypophysial axis in 10, 20 and 30 month-old rats; 2) there is no change with age of the number of nephrons, single nephron filtration rate or transport capacity of Henle's loop of cortical nephrons which could account for an impaired renal response to vasopressin; 3) the reduced concentrating ability of the kidney appears to be linked to a decreased response of the medullary thick ascending limb of Henle's loop which in part is responsible for the cortico-papillary gradient of solutes within the kidney.     

Effect of potassium humate on apple cv. ‘Golden Delicious’ cultured in vitro

The effects of humic substances on in vitro culture of Golden Delicious apple are reported. Potassium humate (KH) when used in proliferation showed a negative interaction with BA while it enhanced rooting when IBA was not present in the culture medium. In the presence of IBA, KH increased root number and reduced root growth. The highest concentration tested, 500 mg l^-1, caused a drastic reduction in root system development. 50 mg l^-1 KH hastened rooting and plants grew more rapidly when transferred to soil.     

Isolation and characterization of a methyl chloride utilizing,strictly anaerobic bacterium

From sludge obtained from the sewage digester plant in Stuttgart-Möhringen a strictly anaerobic bacterium was enriched and isolated with methyl chloride as the energy source. The isolate, which was tentatively called strain MC, was nonmotile, gram-positive, and occurred as elongated cocci arranged in chains. Cells of strain MC formed about 3 mol of acetate per 4 mol of CH₃Cl consumed, indicating that the organism was a homoacetogenic bacterium fermenting methyl chloride plus CO₂ according to: The organism grew with 2–3% methyl chloride in the gas phase at a doubling time of near 30 h. Dichloromethane was not utilized. The bacterium also grew on carbon monoxide, H₂ plus CO₂, and methoxylated aromatic compounds. Optimal growth with methyl chloride was observed at 25°C and pH 7.3–7.7. The G+C-content of the DNA was 47.5±1.5%. The methyl chloride conversion appeared to be inducible, since H₂ plus CO₂-grown cells lacked this ability. From the morphological and physiological characteristics, the isolate could not be affiliated to a known species.     

Growth of Wolinella succinogenes with polysulphide as terminal acceptor of phosphorylative electron transport

Polysulphide was formed according to reaction (1), when tetrathionate was (1) $${\text{S}}_4 {\text{O}}_6^{2 - } + {\text{HS}}^ - \to 2{\text{S}}_2 {\text{O}}_3^{2 - } + {\text{S(O)}} + {\text{H}}^ + $$ added to an anaerobic buffer (pH 8.5) containing excess sulphide. S(O) denotes the zero oxidation state sulphur in the polysulphide mixture S _infn ^sup2- . The addition of formate to the polysulphide solution in the presence of Wolinella succinogenes caused the reduction of polysulphide according to reaction (2). The bacteria grew in a medium containing formate and sulphide, (2) $${\text{HCO}}_2^ - + {\text{S(O)}} + {\text{H}}2{\text{O}} \to {\text{HCO}}_3^ - + {\text{HS}}^ - + {\text{H}}^ + $$ when tetrathionate was continuously added. The cell density increased proportional to reaction (3) which represents the sum of reactions (1) and (3) $${\text{HCO}}_2^ - + {\text{S}}_{\text{4}} {\text{O}}_6^{2 - } + {\text{H}}2{\text{O}} \to {\text{HCO}}_3^ - + 2{\text{S}}_{\text{2}} {\text{O}}_3^{2 - } + 2{\text{H}}^ + $$ (2). The cell yield per mol formate was nearly the same as during growth on formate and elemental sulphur, while the velocity of growth was greater. The specific activities of polysulphide reduction by formate measured with bacteria grown with tetrathionate or with elemental sulphur were consistent with the growth parameters. The results suggest that W. succinogenes grow at the expense of formate oxidation by polysulphide and that polysulphide is an intermediate during growth on formate and elemental sulphur.     

The Nutrimentary Egg Development of the Mite,Varroa jacobsoni (Acari,Arachnida), an Ectoparasite of Honey Bees

The fine structure of the female gonad of Varroa jacobsoni is described. There are two components: the ovary proper and the so-called lyrate organ. The ovary is the place where oocytes mature, embedded in a supporting tissue composed of two cell types: somacells 1 and somacells 2. The lyrate organ has a nutrimentary function and is comprised of two components: supporting cells and nutritive tissue. The supporting cells are similar to the somacells 2 in that they contain abundant microtubules. The nutritive tissue is an extensive syncytium. It is connected with the oocytes via intercellular bridges, the nutritive cords. Oocytes and nutritive tissue are thought to have derived from common stem cells. From fine structural evidence it is concluded that ribosomes are one of the most important components to be transported via the nutritive cords into the oocytes. However, an increase in number of mitochondria in the middle-stage oocytes may also be a consequence of transport of these organelles from the nutritive tissue into the oocytes. Further characteristics make plausible that the interdependences of oocytes and nutritive tissue are comparable to those found in meroistic ovarioles of insects. The somatic components do not seem to be as important as the follicle cells of insects, however. It is assumed that the evolution of a nutrimentary oogenesis speeds up embryogenesis. Thus, the differentiation of the female gonad of Varroa jacobsoni may have facilitated the species' adaptation to a development completed in a short and limited time within the shelter of the covered brood cell of the bee.     

Blast cell activity in mice infected with Hymenolepis nana, H. diminuta and Trichinella spiralis: in vivo uptake of 125IUdR in lymphoid tissues and gut

The kinetics of the lymphoblast response in mice during the course of a primary infection with Hymenolepis nana was measured by the in vivo uptake of 125IUdR. The response was most marked in tissues local to the site of infection, involving the nodes draining the small intestine but not other areas, e.g., inguinal lymph nodes. A close correlation between these responses and the course of infection was observed. Uptake of 125IUdR was greatest in the mesenteric lymph node (MLN) but the peak reached in this organ was later than that in Peyer's patches (PP), small intestine (SI) and spleen (S). The increase in lymphoblast activity of the MLN was similar with Trichinella spiralis; no significant blast cell response to infection with H. diminuta was found till day 9 after injection, the results being similar to those obtained when H. nana infections were established using cysticercoids rather than eggs. It has been shown that the increase in lymphoblast activity was closely correlated with the presence of cells which are most effective in adoptive transfer immunity. A dose-dependent effect was detected in blast cell activity of MLN in different infection levels with T. spiralis and H. nana.