The origin and ultrastructural characteristics of corticotropin-releasing factor (CRF)-immunoreactive nerve fibers in the posterior pituitary of the rat

Summary A fine network of corticotropin-releasing factor (CRF)-immunopositive fibers was found in the posterior lobe of the pituitary of the rat. The intermediate and distal lobes were free of CRF-immunoreactivity. Varicose, terminal-like axons were frequently observed around capillary vessels. Surgical isolation of the paraventricular nuclei resulted in a complete disappearance of CRF-immunoreactive fibers from the posterior lobe. CRF-immunopositive fibers show the general characteristics of peptidergic axons. These ultrastructural observations support the idea that CRF is secreted into capillary vessels.     

Bronchodilatory properties of 2-decarboxy-2-hydroxymethyl prostaglandin E1

We evaluated in a double-blind study the bronchodilatory properties of 2-decarboxy-2-hydroxymethyl prostaglandin E₁ (PGE₁-carbinol), described recently as a nonirritant bronchodilator in animals. Fifteen asthmatic patients received by inhalation single doses of 1, 10, and 30 μg PGE₁-carbinol, 55 μg PGE₂, and placebo (10% ethanol in normal saline, which was also used as diluent for the PGs). Such pulmonary function tests as forced expiratory volume in 1 second, forced vital capacity, and maximal expiratory flow were monitored during 2 hours following inhalation of each compound. 10 and 30 μg PGE₁-carbinol produced significant but short-acting bronchodilation, similar to that caused by 55 μg PGE₂. One-third of the patients reported mild cough and throat irritation during and shortly after inhalation of 30 μg PGE₁-carbinol or 55 μg PGE₂. Placebo and 1 μg PGE₁-carbinol produced minimal side effects, but neither agent caused bronchodilation. In an adjunctive, unblinded trial, the same patients received 400 μg fenoterol. Fenoterol caused greater bronchodilation 15 and 30 minutes after inhalation than did the PGs in the double-blind study.     

Negative transfer of heart rate control following biofeedback training: A partial replication

Ability to raise and lower heart rate (HR) on instruction was tested before and after unidirectional biofeedback training in two groups of 10 male volunteers. Instructional control was assessed in 2-min trials before training, and after 5 and 10 biofeedback trials of increasing (Group I) and decreasing (Group D) HR. The magnitude of HR elevations produced by Group D diminished following training, while modifications in Group I were unchanged. This negative transfer effect is discussed in relation to whether voluntary speeding and slowing HR reflect distinct capacities.     

The phytosociology of British sea-cliff vegetation with special reference to the ecophysiology of some maritime cliff plants

The major factors thought to control the distribution of associations on the sea cliffs in Britain are discussed in relation to the zonation of cliff vegetation, and some experiments to investigate the effects of these factors are described.The seeds of the maritime cliff species are able to germinate in higher salinities than those of closely related inland species.Relative growth rates of maritime cliff species indicate stimulation at low salinities over non-saline conditions, and less reduction in growth at higher salinities than those of closely related inland species.Increasing salinity reduces both photosynthesis and dark respiration in Lavatera arborea. Mesophyll and stomatal resistances are increased while transpiration is reduced.The distribution of ions within Lavatera arborea grown at different salinities indicates differential accumulation between young leaves, old leaves and roots.Nomenclature follows Clapham, Tutin & Warburg (1962).     

Membrane adhesion in photosynthetic bacterial membranes. Light harvesting complex I (LHI) appears to be the main adhesion factor

We have reconstituted pigment-protein complexes isolated from Rhodopseudomonas palustris photosynthetic membranes into phospholipid liposomes. The various complexes were tested for their ability to promote adhesion of the liposome membrane in the presence and absence of Mg²⁺ ions. Samples containing a reaction center (RC)/light-harvesting I (LHI) complex appeared to stack in a manner resembling control thylakoids in 2 and 5 mM Mg²⁺. We also tested for the effects of Mg²⁺ on detergent extractablity of pigment-protein complexes from intact membranes. Mg²⁺ sharply reduced the amount of LHI solubilized from membranes, while having little effect on the extractability of the light harvesting II complex (LHII) and the RC. Based on these results we suggest that LHI is the principal adhesion factor of R. palustris thylakoids.Abbreviations LHC light harvesting complex - OG octyl glucoside - RC reaction center This paper is dedicated to Professor G. Drews on the occasion of his 60th birthday     

Efficacy of chlorhexidine cleansing in reducing contamination of bagged urine specimens

To determine the effectiveness of precleansing with chlorhexidine gluconate-cetrimide in reducing the contamination rate of bagged urine specimens, 62 infants admitted to a children''s hospital were randomly assigned to either receive (32 infants) or not receive (30) cleansing before bag application. Perimeatal swabs were taken before bag application and, in the treated group, after cleansing. Of the specimens from the treated group 69% were found to be contaminated, compared with 73% of those from the no-cleansing group. Chlorhexidine was ineffective in eliminating the perimeatal flora in 75% of the infants. The same organisms were present on the perimeatal swab and in the urine specimen in 95% of the infants in the treated group and 96% of those in the no-cleansing group. To estimate the contamination rate of urine specimens routinely cultured in the laboratory, 200 consecutive specimens (142 midstream and 58 bagged) were cultured. The contamination rate of the midstream urine specimens was 15%, compared with 66% for the bagged speciments. The cost of laboratory processing of contaminated bagged urine specimens at the hospital in 1983 may have been as high as $13 365. Chlorhexidine cleansing does not appear to be cost-effective. Further randomized controlled studies are needed to evaluate the effectiveness of other cleansing agents in reducing the contamination rate of bagged urine specimens.     

Glycolipid-dependent interaction between human migration-inhibitory factor and mononuclear phagocytes

It has been previously established in the guinea pig that the response of peritoneal macrophages to migration inhibitory factor (MIF) is enhanced by a macrophage glycolipid and that gangliosides reversibly bind MIF. This suggests that glycolipids function as cell surface receptors for MIF. In this report, it is demonstrated that the response of human peripheral blood monocytes to human MIF is augmented by preincubation of these cells with glycolipidenriched material extracted from the human macrophage-like cell line U937 or human peripheral blood monocytes and with a purified glycolipid from guinea pig peritoneal macrophages. In addition, a mixed ganglioside preparation from bovine brain shows the same effect. In contrast, the pure gangliosides, G_M1 and G_D1a, and glycolipids from the HL-60 cell line, which is a MIF-unresponsive cell line, were not able to enhance the response to human MIF. The specificity of enhancement by particular glycolipids could not be attributed to an increased uptake of only enhancing glycolipids since there was no significant difference between the association of monocytes with radioactive liposomes containing biologically active or inactive glycolipids. Pronase treatment did not affect the enhancing activity of the U937 glycolipidenriched material. Incubation of cells with glycolipids results in enhancement only if done at 37 °C and not at 4 °C. Therefore, the association of lipid with the monocyte surface appears to be dependent on temperature.Further evidence for the receptor nature of these enhancing glycolipids is provided by experiments involving affinity purification experiments. Coupling of bovine brain mixed gangliosides to agarose resulted in a matrix capable of reversibly binding MIF. G_D1a-agarose was inactive in this respect.     

Receptor specificity of Ia-restricted T lymphoblasts activated against trinitrobenzene sulfonate-coupled spleen cells: recognition of distinct trinitrophenyl and Ia moieties

The receptor specificity of H-2-restricted T lymphoblasts activated against trinitrobenzene sulfonate (TNBS)-coupled spleen cells was examined using an antigen binding assay. A population of Lyt-1+,2-T lymphoblasts acquired syngeneic Ia determinants during 4 days of primary culture with hapten-coupled stimulator cells. Syngeneic Ia was not reexpressed after trypsin treatment of the T cells, but was found after incubation with soluble Ia shed from lipopolysaccharide-activated blasts. Self-Ia binding was specific in that Lyt-1+,2- but not Lyt-1-,2+ cells acquired the antigen, and in that self-Ia bound more effectively than allogeneic Ia material. To determine the relationship of self-Ia binding to the recognition of foreign antigen, the binding of trinitrophenyl (TNP)-coupled plasma membrane vesicles by TNP-specific T cells was studied. TNP-vesicle binding occurred via TNP and H-2(Ia) molecules on the vesicles in that binding was inhibited with antibodies against TNP or H-2(Ia) molecules but not non-major histocompatibility complex (e.g., Ly-6.2) molecules on the vesicles. Complete inhibition of TNP-vesicle binding by an Iak-restricted TNP-specific T-cell line occurred with soluble TNP-lysine, but not an unrelated hapten, N-iodoacetyl-N-(5-sulfonic-1-naphthyl)ethylenediamine (I-AED)-cysteine. Conversely, I-AED-cysteine, but not TNP-lysine, inhibited binding of I-AED-coupled B6 vesicles by B6 anti-I-AED T cells. Significant, but weak inhibition of TNP-vesicle binding by the anti-TNP line was observed with glycoprotein preparations containing partially purified self-Ia molecules. However, inhibition was specific for I-Ak molecules, in that inhibition was lost after removal of I-Ak molecules from the glycoprotein preparation, and very little inhibition occurred with soluble glycoproteins prepared from thymocytes which contained very little Ia material or from LPS blasts of an unrelated H-2 haplotype. These results suggest a recognition model in which TNP and Ia determinants are recognized by neighboring receptor combining sites.     

Appearance of a State 1 – State 2 transition during chloroplast development in the wheat leaf: Energetic and structural considerations

The ability of developing chloroplasts to dynamically regulate the distribution of excitation energy between photosystem 1 and photosystem 2, and thus perform a State 1 – State 2 transition, was examined from analyses of chlorophyll fluorescence kinetics in 4- and 8-day-old Triticum aestivum L. cv. Maris Dove leaves grown under a diurnal light regime. Chloroplasts at all stages of development in the two leaf systems could undergo a State 1 – State 2 transition, except those found in the basal 0.5 cm of the 4-day-old leaf. The ability to physiologically modify the excitation energy distribution between the chlorophyll matrices of the two photosystems developed after the development of mature, fully photochemically competent photosystem 2 units and the appearance of excitation energy transfer between photosystem 2 and photosystem 1. Also, changes in the degree of energetic interaction between the two photosystems, in vivo rates of electron transport and the chlorophyll a/b ratio could not be correlated with the appearance of a State 1 – State 2 transition. Ultrastructural studies demonstrated a 32% increase in the degree of thylakoid appression in chloroplasts at the base of the 8-day-old leaf compared to the situation in the basal 0.5 cm of the 4-day-old leaf. This difference in thylakoid stacking can account for the differing abilities of these two tissues to perform a State 1 – State 2 transition when considered in the context of the distribution of the two photosystems within appressed and non-appressed regions of thylakoid membranes.