Molecular characterization of a major autoantibody-associated cross-reactive idiotype in Sjogren's syndrome

Primary Sjogren's syndrome is an autoimmune disorder characterized by lymphocytic infiltration of the salivary and lacrimal glands, producing associated dry eyes (keratoconjunctivitis sicca), dry mouth, and intermittently swollen salivary glands. A high proportion of the infiltrating B lymphocytes express surface and cytoplasmic Ig bearing a kappa-L chain-associated CRI defined by reactivity with the murine mAb, 17.109. To determine the structural basis for CRI expression in this disease, we generated CRI+ lymphoblastoid cell lines and a cDNA library from lymphocytes extracted from Sjogren's syndrome patients' salivary gland biopsy specimens. Nucleic acid sequence analyses of the mRNA of one such 17.109-CRI+ lymphoblastoid cell line (NOV) reveals the expressed kappa light chain variable region gene (V kappa gene) to be homologous to Humkv325, a conserved V kappa gene used at relatively high frequency in certain B cell malignancies. In addition, synthetic oligonucleotides, corresponding to the first and third frameworks and the second complementarity determining region of the Humkv325 gene, were used to identify and isolate clones from a cDNA library generated from SS salivary gland lymphocytes. Clones annealing specifically with one or more of these oligonucleotide probes contained kappa light chain cDNA. The sequences corresponding to the variable region of two clones (Taykv320 and Taykv306) were homologous to Humkv325. The V kappa genes of four other cDNA clones (Taykv322, Taykv310, Taykv308, and Taykv312) most likely were generated somatically from the rearranged Humkv325 gene through a limited number of nucleic acid base substitutions. Our results suggest that the high frequency of 17.109-CRI expression in Sjogren's syndrome patients results from a multiclonal expansion of B cells using Humkv325, and that the expressed Humkv325 may undergo somatic diversification in an apparent Ag-driven response.     

Sodium and calcium currents in action potentials of rat somatotrophs: their possible functions in growth hormone secretion

We report that both Na+ and Ca2+ currents are involved in the action potentials and in the hormone release from rat somatotrophs in primary culture. Single somatotrophs were identified by reverse hemolytic plaque assay (RHPA) and transmembrane voltage and currents were recorded using the whole-cell mode of the patch-clamp technique. Somatotrophs displayed a mean resting potential of -80mV and an average input resistance of 5.7G omega. Most of the cells showed spontaneous or evoked action potentials. Single action potentials or the initial spike in a burst were characterized by their high amplitude and short duration. Tetrodotoxin (TTX, 1 microM) blocked single action potentials and the initial spikes in a burst, whereas action potentials of long duration and low amplitude persisted. Cobalt (2 mM) plus TTX (1 microM) blocked all the action potentials. Voltage-clamp experiments confirmed the presence of both a TTX-sensitive Na+ current and Co2(+)-sensitive Ca2+ currents. TTX or Na(+)-free medium slightly decreased the basal release of GH but did not markedly modify hGRF-stimulated GH release. However, Co2+ (2 mM), which partially decreased the basal release, totally blocked hGRF-stimulated release. We conclude that (1) Na+ currents which initiate rapid action potentials may participate in spontaneous GH release; (2) Ca2+ currents, which give rise to long duration action potentials and membrane voltage fluctuation, are probably involved in both basal and hGRF-stimulated GH releases.     

The effect of etorphine on nicotine- and muscarine-induced catecholamine secretion from perfused rat adrenal glands

The effect of etorphine on nicotine and muscarine-mediated catecholamine (CA) release from isolated perfused rat adrenal glands was investigated. Nicotine increased CA secretion at the low concentration of 0.5 micrograms while higher concentrations of muscarine (5 micrograms) were required. Moreover, muscarine released primarily epinephrine (EP) from rat adrenal glands while nicotine released norepinephrine (NE) and Ep. Etorphine inhibited NE and EP release evoked by nicotine to the same extent, whereas, muscarine-mediated release of NE and EP was not affected. Mecamylamine and verapamil inhibited nicotine but not muscarine-induced CA secretion. Our results suggest that etorphine preferentially interacts with nicotinic receptors on rat adrenal chromaffin cell membranes.     

Polysaccharide Fraction from Higher Plants which Strongly Interacts with the Cytosolic Phosphorylase Isozyme : I. Isolation and Characterization

From leaves of Spinacia oleracea L. or from Pisum sativum L. and from cotyledons of germinating pea seeds a high molecular weight polysaccharide fraction was isolated. The apparent size of the fraction, as determined by gel filtration, was similar to that of dextran blue. Following acid hydrolysis the monomer content of the polysaccharide preparation was studied using high pressure liquid and thin layer chromatography. Glucose, galactose, arabinose, and ribose were the main monosaccharide compounds. The native polysaccharide preparation interacted strongly with the cytosolic isozyme of phosphorylase (EC 2.4.1.1). Interaction with the plastidic phosphorylase isozyme(s) was by far weaker. Interaction with the cytosolic isozyme was demonstrated by affinity electrophoresis, kinetic measurements, and by ¹⁴C-labeling experiments in which the glucosyl transfer from [¹⁴C]glucose 1-phosphate to the polysaccharide preparation was monitored.     

Circadian Rhythm of the Prokaryote Synechococcus sp. RF-1

The prokaryotic Synechococcus sp. RF-1 exhibited a nitrogen fixation circadian rhythm with characteristics remarkably similar to the circadian rhythm of eukaryotes. The rhythm had a free-running period of about 24 hours when the length of the preen-trained cycle did not differ too much from 24 hours, and it was insensitive to changes in temperature from 22°C to 33°C. Because the endogenous rhythm of nitrogen fixation was not affected by a phase-shift of its previous cycles, the circadian rhythm in Synechococcus sp. RF-1 was not considered to be controlled simply by a feedback mechanism.     

Water Content during Abscisic Acid Induced Freezing Tolerance in Bromegrass Cells

Changes in water content and dry weight were determined in control cells and those induced to cold harden in response to abscisic acid (ABA) treatment (7.5 × 10⁻⁵ molar). Bromegrass (Bromus inermis Leyss cv Manchar) cells grown in suspension culture at room temperature (23°C) for 7 days acclimated to −28°C (LT₅₀) when treated with ABA, or to −5°C when untreated. ABA significantly reduced cell growth rates at 5 and 7 days after treatment. Growth reduction was due to a decrease in cell number rather than cell size. When the cell water content was expressed as percent water (percent H₂O) or as grams water per gram dry weight (gram H₂O/gram dry weight [g DW]), the water content of hardy, ABA-treated cells decreased from 85% to 77% or from 6.4 to 3.3 g H₂O/g DW in 7 days. Control cell water content remained static at approximately 87% and 7.5 g H₂O/g DW. However, cell water content, expressed as milligrams water per million cells (milligram H₂O/10⁶ cells), did not differ in ABA-treated or control cells. The dry matter content of ABA-treated cells, expressed as milligram DW/10⁶ cells increased to 3.3 milligram/10⁶ cells in 7 days, whereas the dry weight of the control cells remained between 1.4 to 2.1 milligrams/10⁶ cells. The osmotic potential of ABA-treated cells decreased by the fifth day while that of control cells increased significantly and then decreased by day 7. Elevated osmotic potentials were not associated with increased ion uptake. In contrast to much published literature, these results suggest that cell water content does not decrease in ABA-treated cells during the induction of freezing tolerance, rather the dry matter mass per cell increased. Cell water content may be more accurately expressed as a function of cell number when accompanying changes to dry cell matter occur.     

Water-storage capacity ofThuja,Tsuga andAcer stems measured by dehydration isotherms

Water-storage capacity was measured inThuja occidentalis L.,Tsuga canadensis (L.) Carr., andAcer saccharum Marsh. during the dehydration of stem segments 1.5–2.5 cm in diameter. Stem water potential was measured with a temperature-corrected stem hygrometer and cavitations were detected acoustically. Water loss was measured by weight change. Dehydration isotherms consistently displayed three phases. The first phase, from water potential (Ψ) 0 to about −0.2 MPa, had a high capacitance (C>0.4kg water lost· (1 of tissue)⁻¹· MPa⁻¹) and we have attributed this high C to capillary water as defined by Zimmermann (1983, Xylem structure and the ascent of sap, Springer-Verlag). The second phase from Ψ=−0.5 to about −2.0 had the lowest C values (<0.02 kg·l⁻¹·MPa⁻¹) and was accompanied by a few cavitation events. This phase may have been a transition zone between capillary storage and water released by cavitation events as well as water drawn from living cells of the bark. The third phase also had a high C (about 0.07–0.22kg·l⁻¹·MPa⁻¹) and was associated with many cavitation events while Ψ declined below about −2.5 MPa; we presume the high capacitance was the consequence of water released by cavitation events. We discuss the ecological adaptive advantage of these three phases of water-storage in trees. In moist environments, water withdrawn from capillary storage may be an important fraction of transpiration, but may be of little adaptive advantage. For most of the growth season trees draw mainly on elastic storage, but stem elastic storage is less than leaf elastic storage and therefore unlikely to be important. In very dry environments, water relased by cavitation events might be important to the short-term survival of trees.     

Reconstruction of the concha of the ear using a postauricular island flap

An effective method of reconstruction of the auricular conchal cavity using a postauricular island flap containing the postauricular blood vessels is described. In this procedure, the island flap is brought in to cover the defect of the conchal cavity through a tunnel between the defect and the retroauricle. Sound anatomic and mechanical principles are introduced in this technique. Two patients underwent the operation, and good results were obtained.     

Transgenetic studies implicate interactions between homologous PrP isoforms in scrapie prion replication

Transgenic (Tg) mice expressing both Syrian hamster (Ha) and mouse (Mo) prion protein (PrP) genes were used to probe the mechanism of scrapie prion replication. Four Tg lines expressing HaPrP exhibited distinct incubation times ranging from 48 to 277 days, which correlated inversely with HaPrP mRNA and HaPrPC. Bioassays of Tg brain extracts showed that the prion inoculum dictates which prions are synthesized de novo. Tg mice inoculated with Ha prions had approximately 10(9) ID50 units of Ha prions per gram of brain and less than 10 units of Mo prions. Conversely, Tg mice inoculated with Mo prions synthesized Mo prions but not Ha prions. Similarly, Tg mice inoculated with Ha prions exhibited neuropathologic changes characteristic of hamsters with scrapie, while Mo prions produced changes similar to those in non-Tg mice. Our results argue that species specificity of scrapie prions resides in the PrP sequence and prion synthesis is initiated by a species-specific interaction between PrPSc in the inoculum and homologous PrPC.