Voltage sensitivity of inhibitory postsynaptic current in Aplysia buccal ganglia

A single consistent luteolytic dose of 10 IU PMSG given on day 5 of pregnancy caused complete resorption of foetuses and placentae associated with a polyfollicular ovarian state in rats. Concomitant treatment with progesterone or prolactin given concurrently with PMSG was found to overcome the antifertility efficacy of PMSG and maintained the endocrine balance favouring pregnancy maintenance. It was postulated that the PMSG-induced ovarian polyfolliculogenesis might be responsible for luteolysis of the corpus luteum gravidarum.     

Naturally acquired immunity to influenza type A: a clinical and laboratory study

After type A influenza virus had undergone major antigenic change in mid 1968, it was noted that individuals previously infected by strains of the old subtype (Asian), especially late strains, appeared to be unexpectedly resistant to clinical attack by the new subtype (Hong Kong). Prospective studies have since shown that, during the A/England/42/72 influenza epidemic of 1972, in which the incidence was approximately 7% in the community, clinical influenza due to this virus was not found in 229 subjects previously confirmed as having had A/Hong Kong/1/68 influenza, even though vaccine which had been effective against A/Hong Kong/1/68 was ineffective against A/England/42/72. During the A/Port Chalmers/1/73 influenza epidemic of 1974, clinical influenza resulting from Port Chalmers virus was not found in a closely monitored group of 176 unvaccinated subjects previously infected by A/Hong Kong/1/68 or A/England/42/72, although laboratory studies demonstrated Port Chalmers infection in five of these (2-8%). By contrast, among 99 subjects who had no such history of earlier infection, 22 developed laboratory-proven Port Chalmers influenza and most of them had typical illness.     

The role of the costo-clavicular compression syndrome within the framework of fibrinolytic therapy of deep arm-vein thrombosis

Eight patients with upper extremity deep-vein thrombosis were treated with thrombolytic agents. The role of a compression syndrome of the costo-clavicular space (found in 5 out of 7 cases) as a probably thrombogenetic factor is discussed. The complications of the therapy were considerable, despite frequent laboratory controls. In one thrombosis of more than 6 months' standing the treatment was ineffective. In the other 7 cases the early clinical results were good. At follow-up 14 to 57 months after thrombolytic therapy, 5 out of 7 cases had residual symptoms (rethrombosis in 2 cases). This may be due to the fact that the compression syndrome was not initially treated, with resultant persistence of the chronic trauma to the vein. Better results can be expected from fibrinolytic therapy in combination with surgical correction of any anatomical narrowing.     

A 50-picosiemens anion channel of the chloroplast envelope is involved in chloroplast protein import

Single channel recordings were used to investigate the changes on the pea chloroplast envelope during protein import. In the inside-out patch configuration a 50-picosiemens (pS) anion channel of the chloroplast envelope membrane was identified. The open time probability of the channel was decreased by the addition of the wild type precursor protein of ferredoxin (wt-prefd) to the pipette-filling solution in the presence of 0.5 mM ATP. In the absence of ATP or in the presence of 50 microM ATP, wt-prefd did not affect the open time probability of the channel. A deletion mutant of prefd, Delta6-14-prefd, which is inactive in in vitro import, was also unable to affect the open time probability of the 50-pS anion channel. In the presence of 100 microM ATP, wt-prefd decreased the open time probability of the channel to a lesser extent, as did the transit peptide alone. It is concluded that the 50-pS anion channel could be part of the protein import machinery of the inner membrane. In addition the precursor protein under import conditions induced burst-like increases of the envelope conductivity. The implication of both responses for the chloroplast protein import process are discussed.     

Dietary salt regulates expression of Tamm-Horsfall glycoprotein in rats

BACKGROUND: Tamm-Horsfall glycoprotein (THP) is a unique protein that is produced exclusively by cells of the thick ascending limb of Henle's loop (TALH). This study examined whether dietary salt altered renal THP production. METHODS: Male Sprague-Dawley rats were examined on days 1, 4, and 15 following placement in metabolic cages on diet that contained 0.3%, 1.0% or 8.0% NaCl. THP expression was quantified using Northern hybridization and Western blotting analysis. RESULTS: An increase in dietary salt produced sustained increases in relative steady-state mRNA and protein levels of THP in the kidney. Addition of furosemide, but not chlorothiazide, to animals on the 8.0% NaCl diet further augmented steady-state mRNA levels of THP. CONCLUSIONS: An increase in dietary salt and the loop diuretic, furosemide, increased expression of THP in the rat. The data support the involvement of this unique protein in the function of the TALH during changes in dietary salt. These findings also suggest that restriction of dietary salt may be beneficial in cast nephropathy in multiple myeloma and recurrent nephrolithiasis, two diseases in which THP can play an important pathogenetic role.     

Effect of heat treatment on the photoluminescence of CdS nanocrystallites in cadmium-rich organic Langmuir Blodgett matrix

CdS nanocrystallites were grown within an organic layered matrix by partial sulphidation of precursor cadmium arachidate LB multilayers. The cadmium arachidate–arachidic acid composite multilayers containing CdS nanocrystallites were enriched by intercalation with Cd²⁺ ions in aqueous solution of CdCl₂ and subsequently heat treated at different temperatures up to 300 °C, in air and in vacuum. CdS nanocrystallites within the composite multilayer have been found to exhibit treatment process dependent characteristic changes in optical absorption and luminescence. The optical data obtained at different stages/conditions of processing have been analyzed by considering changes in excitonic absorption and emission as well as contributions from surface and bulk defects related emission and a suitable energy level diagram has been proposed. The composition, microstructure and surface morphology of the composite multilayers were also studied at all stages of processing to develop a comprehensive understanding of the interaction of the organic matrix with CdS nanocrystallites and the consequent influence on the optical behavior of the nanocrystallites. These studies have shown that the organic moieties encapsulating the CdS nanocrystallites tend to restrict their growth and aggregation, while the presence of cadmium in the organic matrix is responsible for the passivation of surface defects as well as the reduction of bulk defects, and these factors have significant influence on the photoluminescence of CdS nanocrystallites.     

Photoisomerization of amphiphilic azobenzene derivatives in Langmuir Blodgett films prepared as polyion complexes, using ionic polymers

Polyion complexation in mixed Langmuir and Langmuir Blodgett (LB) films of photochromic amphiphilic azobenzene carboxylic acids, 11-[4-(4-hexylphenyl)azo] phenoxyundecanoic acid, 11-(4-phenylazo)phenoxyundecanoic acid, and diamine grafted poly(methylmethaacrylate) polymers has been studied. Monolayer behaviour of the pure components and mixed films was studied through pressure–area isotherms and LB films were characterized by spectroscopic, X-ray diffraction and Atomic force microscopy techniques. Aggregation (H-type), often observed in LB films of pure amphiphilic azo acids, was partly avoided in the mixed LB films as indicated by absorption spectral studies. Photoisomerization of the polyion complexed LB films was also studied. The results altogether demonstrate that amine grafted polymer enter into a polyion complexation with azo acid carboxylate group. LB films could be obtained by transfer of the composite monolayers and these LB films exhibited different levels of aggregation of the azo acids. Reversible photoisomerization was observed in LB films with unaggregated azo acid.     

Nucleation of CdTe thin films deposited by close-space sublimation under a nitrogen ambient

The early stages of the close-space sublimation growth of CdTe/ITO (indium tin oxide) at 500°C under 26.7 kPa (200 Torr) of N₂ were investigated, the relatively high pressure being used to slow the growth. Film development was monitored over 60 mins by ex-situ AFM (atomic force microscopy), the growth being controlled by a shutter. The films formed by the ‘island’ or Volmer-Weber growth mechanism. Developments in the areal island growth rate, the island density and spatial distribution type were explained using growth mechanisms. Significant changes in these phenomena at t ≥ 10 mins were attributed to a change in growth mechanism from surface migration limited, to a regime in which island coalescence and direct impingement of vapour species on the islands became important. Since the islands are characterised by distinct crystalline facets, this indicates the growth mechanism to be uninterrupted step-flow like addition of material to each island. Arguments are given to relate the final grain size in the films to the density of nuclei that are stable to re-evaporation after t = 10 mins.     

High-power 2.0 μm InGaAsP laser diodes

Data detailing the performance of strained-layer InGaAs/InGaAsP double-quantum-well laser diodes operating at 2.0 μm are presented. The total external efficiency and maximum power achieved are 55% and 1.6-W continuous wave (CW), respectively, from a 200-μm gain-guided laser diode. Measurements on gain-guided broad area devices yield an internal efficiency of 0.73 with a distributed loss coefficient, α, of 7.5 cm^-1. The measured threshold current density is 300 A/cm² for a 2-mm-long broad area device operated CW at 25°C