Isolation and composition of the subunits of spinach chloroplast coupling factor protein.

A more convenient method for preparing large amounts of spinach chloroplast coupling factor is described, in which centrifugation of the EDTA-extracted chloroplasts is replaced by batchwise adsorption on DEAE-cellulose followed by filtration through Miracloth. Methods have been developed to purify the subunits from coupling factor dissociated by sodium dodecyl sulfate, involving hydroxylapatite chromatography followed by gel filtration with the detergent still present. The amino acid composition of the subunits purified by these methods was determined, with some differences noted in values for cysteine, tyrosine, phenylalanine, and methionine compared to previously published values. The stoichiometry of the subunits was estimated as 2:2:1:1:2 from their relative adsorption of dye after gel electrophoresis, compared to dye adsorbed by known amounts of the purified subunits. Estimates of subunit stoichiometry are rounded off to nearest whole numbers; actual preparations of coupling factor usually show less than complete amounts of the two smallest subunits.     

Fibronectin decreases the stimulatory effect of fibrin and fibrinogen fragment FCB-2 on plasmin formation by tissue plasminogen activator.

Fibronectin is a dimeric glycoprotein (Mr 440,000) involved in many adhesive processes. During blood coagulation it is bound and cross-linked to fibrin. Fibrin binding is achieved by structures (type I repeats) which are homologous to the "finger" domain of tissue plasminogen activator. Tissue plasminogen activator also binds to fibrin via the finger domain and additionally via the "kringle 2" domain. Fibrin binding of tissue plasminogen activator results in stimulation of its activity and plays a crucial role in fibrinolysis. Since fibronectin might interfere with this binding, we studied the effect of fibronectin on plasmin formation by tissue plasminogen activator. In the absence of fibrin, fibronectin had no effect on plasminogen activation. In the presence of stimulating fibrinogen fragment FCB-2, fibronectin increased the duration of the initial lag phase (= time period until maximally stimulated plasmin formation occurs) and decreased the rate of maximal plasmin formation which occurs after that lag phase mainly by increasing the Michaelis constant (Km). These effects of fibronectin were dose-dependent and were similar with single- and two-chain tissue plasminogen activator. They were also observed with plasmin-pretreated FCB-2. An apparent Ki of 43 micrograms/ml was calculated for the inhibitory effect of fibronectin when plasminogen activation by recombinant single-chain tissue plasminogen activator was studied in the presence of 91 micrograms/ml FCB-2. When a recombinant tissue plasminogen activator mutant lacking the finger domain was used in a system containing FCB-2, no effect of fibronectin was seen, indicating that the inhibitory effect of fibronectin might in fact be due to competition of fibronectin and tissue plasminogen activator for binding to fibrin(ogen) via the finger domain.     

Relationship between DNA cycle and growth rate in Synechococcus sp. strain PCC 6301.

Flow cytometry was used to examine cell cycle regulation in Synechococcus sp. strain PCC 6301 under a variety of growth conditions. The DNA frequency distributions of exponentially growing and dark-blocked populations confirmed that this cyanobacterium contains multiple chromosome copies even at very slow growth rates. Furthermore, the presence of major peaks corresponding to other than 2" chromosome copies strongly suggests that DNA replication is initiated asynchronously. Although this suggestion is at odds with the standard formulation of the procaryotic cell cycle model, it is similar to recent observations of asynchrony in Escherichia coli replication mutants.     

Study of experimental vaccine protection using a statistical method to compare survival curves

A statistical method using the chi 2 distribution of variable was studied for survival data about experimental disease on S. typhimurium C5S infected mice via oral administration, and about vaccinal protection with S. typhimurium mutants. Our results showed that Ra Rc and Re S. typhimurium mutants were good experimental vaccines.     

Two pathways of electron transfer in quinol-mediated cyclic phosphorylation in spinach chloroplasts

Low potential quinones are mediators of cyclic phosphorylation in washed spinach thylakoid membranes if they are prereduced to provide the proper redox poise. Cyclic phosphorylation catalyzed by different quinols varies in its sensitivity to the electron transfer inhibitor 2-iodo-6-isopropyl-3-methyl-2′,4,4′-trinitrodiphenyl ether (DNPINT), which is thought to inhibit electron flux from the bound plastoquinone (B) to the plastoquinone pool (Trebst, A., Wietoska, H., Draber, W. and Knops, H.J. (1978) Z. Naturforsch. 33c, 919–927). Cyclic phosphorylation catalyzed by uncharged quinols is extremely sensitive to DNPINT, whereas cyclic phosphorylation catalyzed by negatively charged quinols is approximately two orders of magnitude less sensitive. Many quinols have pK₁ values in the physiological range (pH 7–9). Increasing the concentration of the deprotonated quinol either by raising the assay pH, increasing the mediator concentration, or increasing the fractional reduction of the quinone results in a decrease in the sensitivity of cyclic phosphorylation to DNPINT. At very high DNPINT concentrations, cyclic phosphorylation catalyzed by all quinols (and ferredoxin) is inhibited, but not phenazine methosulfate catalyzed cyclic phosphorylation.These data suggest that the deprotonated form of the quinol can donate electrons directly to the plastoquinone pool, whereas the uncharged quinol most obligately transfer electrons through the bound plastoquinone ‘B’. A second site of DNPINT action after the plastoquinone pool is also observed, which requires much higher DNPINT concentrations for inhibition of phosphorylation.     

Examen de personas histoplasmino-positivas del radio de actividad del hospital amazónico „Albert Schweitzer” en el curso medio del rio Ucayali

Resumen 1) Se analizan las historias clínicas de 100 personas histoplasmino-positivas. 61% de ellas son histoplasmino-positivas y tuberculinonegativas, 39% histoplasmino y tuberculino-positivas.2) Se habían sacado radiografías de los pulmones a 38 de los 100 pacientes, encontrándose calcificaciones en 22, sea en un 58% de ellos.3) Se describen 4 casos: 3 de ellos con una historia y con signos radiológicos que hacen evidente que han tenido una histoplasmosis; un caso es consideredo como una histoplasmosis en evolución.4) En todos los casos se trata de formas benignas de histoplasmosis.

---

Summary 1) Analysis of the clinical histories of 100 histoplasmin-positive reactors: 61% are histoplasmin-positive and tuberculin-negative, 39% histoplasmin- and tuberculin-positive.2) Lung X-rays have been taken of 38 of the 100 patients. In 22 X-rays (58%) calcifications are present.3) 4 cases are described: 3 of them with a history and with radiological symptoms, that make it evident, that they have had a histoplasmosis; one case is considered as a histoplasmosis in evolution.4) All cases are benign forms of histoplasmosis.

---

Zusammenfassung 1) Die Krankengeschichten von 100 histoplasmin-positiven Patienten werden analysiert. 61% davon sind histoplasmin-positiv und tuberkulin-negativ, 39% histoplasmin- und tuberkulin-positiv.2) Von 38 der 100 Patienten wurden Lungenroentgenbilder aufgenommen. In 22 Aufnahmen (58%) fanden sich Verkalkungen.3) 4 Fälle werden beschrieben: bei dreien machen es Krankengeschichte und Roentgenbefund evident, dass sie eine Histoplasmose durchgemacht haben; ein Fall wird als akute Histoplasmose angesehen.4) Bei allen Fällen handelt es sich um eine gutartige Form der Histoplasmose.

---

---

Read in the meeting of the First Congress of the International Society for Tropical Dermatology, Naples, June 8–13, 1964.     

Involvement of adenosine A1 and A2A receptors on guanosine-mediated anti-tremor effects in reserpinized mice

Parkinson’s disease (PD) signs and symptoms regularly include tremor. Interestingly, the nucleoside guanosine (GUO) has already proven to be effective in reducing reserpine-induced tremulous jaw movements (TJMs) in rodent models, thus becoming a promising antiparkinsonian drug. Here, we aimed at revealing the mechanism behind GUO antiparkinsonian efficacy by assessing the role of adenosine A₁ and A_2A receptors (A₁R and A_2AR) on GUO-mediated anti-tremor effects in the reserpinized mouse model of PD. Reserpinized mice showed elevated reactive oxygen species (ROS) production and cellular membrane damage in striatal slices assessed ex vivo and GUO treatment reversed ROS production. Interestingly, while the simultaneous administration of sub-effective doses of GUO (5 mg/kg) and SCH58261 (0.01 mg/kg), an A_2AR antagonist, precluded reserpine-induced TJMs, these were ineffective on reverting ROS production in ex vivo experiments. Importantly, GUO was able to reduce TJM and ROS production in reserpinized mouse lacking the A_2AR, thus suggesting an A_2AR-independent mechanism of GUO-mediated effects. Conversely, the administration of DPCPX (0.75 mg/kg), an A₁R antagonist, completely abolished both GUO-mediated anti-tremor effects and blockade of ROS production. Overall, these results indicated that GUO anti-tremor and antioxidant effects in reserpinized mice were A₁R dependent but A_2AR independent, thus suggesting a differential participation of adenosine receptors in GUO-mediated effects.