Cysteinyl methyl ester of AVP(4-8), a potent agonist on the maintenance of passive avoidance in rats

A series of short AVP analogs with D- or L-arginine forming the C-terminal was synthesized, and their peripheral effects, i.e., vasoconstrictor and antidiuretic activities, and behavioral effects in enhancing retention in passive avoidance in rats were evaluated. We found that: 1) AVP(4-8) and its cysteinyl methyl ester were more potent in the behavioral response than its D-Arg homologs; 2) the methyl ester derivative was the most effective analog in this behavioral test among the peptides we synthesized, with a potency 40 times as high as AVP; 3) neither the D- nor the L-Arg short derivatives of AVP showed any peripheral effects up to a dose thousands of times greater than AVP. The results support the contention that arginine in the short analogs plays an important role in their behavioral response associated with a relatively steady peptide conformation.

[Facilitation of arginine-vasopressin analogs on learning and memory in rats]

Adult rats were trained in a maze for brightness discrimination (BD) or in a shuttle box for active avoidance. It was found that the pretreatment of 1-desamino-8-D-arginine-vasopressin (DDAVP) enhanced the retention of brightness discrimination and retarted the extinction of avoidance response. Neonatal daily administration for 14 d of both 9-desglycylamide-DDAVP (DGDDAVP) or 2-destyrosyl-3-desphenylalanyl-9-desglycylamide-AVP (AVP4-8), but not D-arginine-AVP4-8 (DAVP4-8) showed significant facilitation on acquisition and subsequent maintenance of BD in adult rats. The results indicate that some of synthetic arginine-vasopressin analogs may directly act on CNS and consequently affect learning behaviors in rats.

Expression in yeast of the T-urf13 protein from Texas male-sterile maize mitochondria confers sensitivity to methomyl and to Texas-cytoplasm-specific fungal toxins

The mitochondrial gene T-urf13 from maize (Zea mays L.) with Texas male-sterile (T) cytoplasm codes for a unique 13 kd polypeptide, T-URF13, which is implicated in cytoplasmic male sterility and sensitivity to the insecticide methomyl and to host-specific fungal toxins produced by Helminthosporium maydis race T (HmT toxin) and Phyllosticta maydis (Pm toxin). A chimeric gene coding for T-URF13 fused to the mitochondrial targeting peptide from the Neurospora crassa ATP synthase subunit 9 precursor was constructed. Expression of this gene in the yeast Saccharomyces cerevisiae yielded a polypeptide that was translocated into the membrane fraction of mitochondria and processed to give a protein the same size as maize T-URF13. Methomyl, HmT toxin and Pm toxin inhibited growth of yeast cells expressing the gene fusion on medium containing glycerol as sole carbon source and stimulated respiration with NADH as substrate by isolated mitochondria from these cells. These effects were not observed in yeast cells expressing T-URF13 without a targeting peptide. The results show that T-URF13 is sufficient to confer sensitivity to methomyl and the fungal toxins in a heterologous eukaryotic system, and suggest that mitochondrial localization of T-URF13 is critical for these functions.

Angiotensin binding sites in rabbit anterior uvea and human ciliary epithelial cells

Angiotensin binding sites in membrane homogenates of rabbit iris/ciliary body and human nonpigmented ciliary epithelial (NPE) cells grown in culture were characterized using radioligand binding assays with (125I)-sarcosine1-isoleucine8-angiotensin II [(125I)-SARILE]. Scatchard analysis of the binding of (125I)-SARILE yielded linear plots with a Kd value of 0.55 +/- 0.1 nM and a Bmax of 98 +/- 23 fmol/mg protein in rabbit iris/ciliary body, and a Kd value of 0.63 +/- 0.1 nM, and a Bmax of 36.2 +/- 24 fmol/mg protein in NPE cells. Studies of the inhibition of the binding of (125I)-SARILE in rabbit iris/ciliary body were performed with a series of competing ligands, including the angiotensin receptor antagonist SARILE and the agonists angiotensin I, angiotensin II and angiotensin III. Inhibition curves for the antagonist resulted in Hill coefficients of approximately 1, consistent with the presence of a single class of binding sites with high affinity for (125I)-SARILE. Competition for the binding of (125I)-SARILE to binding sites with each of the agonists resulted in inhibition curves with Hill coefficients significantly less than 1 in the absence of GTP. However, in the presence of 100 microM GTP the Hill coefficients increased to approximately 1. The order of potencies of these agents was consistent with the pharmacologic profile of angiotensin II receptors. Thus rabbit iris/ciliary body homogenates, which include vascular tissue, contain a homogeneous population of angiotensin binding sites coupled to a guanine nucleotide binding protein. The presence of binding sites in cultured NPE cells indicates that at least some are located on the cells thought to be responsible for aqueous humor secretion.

Pharmacokinetics and tissue penetration of Sch 39304 in granulocytopenic and nongranulocytopenic rabbits

We studied the plasma pharmacokinetics and tissue penetration of Sch 39304 (SCH), a new antifungal triazole, in granulocytopenic [G(+)] and nongranulocytopenic [G(-)] rabbits. Five female New Zealand White G(-) rabbits were given a single oral dose of 2 mg of SCH per kg of body weight. Levels in plasma, determined by gas-liquid chromatography-electron capture, were obtained for 6 days. This procedure was repeated 2 weeks later with the same rabbits, which were induced and maintained G(+) with cytosine arabinoside. There were no significant differences between the pharmacokinetic parameters of G(+) and G(-) rabbits. Among all animals studied, the maximum concentration of the drug in plasma was 1.4 +/- 0.11 micrograms/ml at 4 +/- 0.5 h, the half-life was 25 +/- 1.4 h, the volume of distribution at steady state was 3.8 +/- 0.3 liters, and the area under the concentration-time curve was 44 +/- 3.4 micrograms.h/ml. SCH was detectable in plasma up to day 6. Levels of SCH in tissue were studied at steady state in six G(+) and six G(-) rabbits receiving 2 mg of the drug orally per kg per day for experimental disseminated candidiasis. Tissue SCH levels equalled or exceeded those in plasma (at steady state) at all sites examined, and these ratios were similar in both G(+) and G(-) rabbits. Thus, plasma pharmacokinetics of orally administered SCH were similar for G(+) and G(-) rabbits, and SCH achieved high levels of penetration into multiple tissues, including the liver and the central nervous system.

Structural changes at the myogenic cell surface during the formation of myotendinous junctions

Myotendinous junctions are sites which are morphologically and molecularly specialized for force transmission between intracellular and extracellular structural proteins. In the present investigation, the formation of these specialized junctions is studied in chicken embryos from 9 days following fertilization to 1 day posthatching, using light and electron microscopy. Observations indicate that the first discernible event in myotendinous junction formation is the appearance of basement membrane at the incipient junction at 9-10 days postfertilization, concomitant with the aggregation of fibroblasts at the junctional regions of myogenic cells. Subsequently, subsarcolemmal densities appear at sites opposite basement membrane locations by 13 days postfertilization. Myofibrils insert into subsarcolemmal densities by day 15 and invaginations of the cell membrane are initiated at those insertions. Type I collagen fibers appear at the cell surface at day 17. Junctional structure at day 17 qualitatively resembles that of adult myotendinous junctions. Changes in junctional structure following day 17 are primarily increases in the amount of subsarcolemmal densities, myofibril-membrane associations, and amount of junctional membrane folding.

Landau-Kleffner syndrome with unilateral EEG abnormalities--two cases from Beijing, China

We reported 2 cases of Landau-Kleffner syndrome from Beijing whose clinical manifestations were very similar to ones previously reported. The onset of symptoms in these 2 cases was at 3 and 4 years of age, respectively, and both were characterised by unilateral focal epileptiform EEG discharges, without remarkable clinical seizures. One patient had normal SPECT study in addition to normal CT scan, BAER and VER results; the other had a family history of epilepsy. Since this syndrome may involve a primary brain disturbance responsible for both the epilepsy and aphasia without clear structural brain lesions, we wonder whether it can be classified as one of the benign functional partial epilepsies with genetic factors.

Activation of the transforming potential of the human fos proto-oncogene requires message stabilization and results in increased amounts of partially modified fos protein

The requirements for activation of the transformation potential of the human c-fos proto-oncogene were investigated. Recombinant plasmids containing the Moloney murine leukemia virus long terminal repeat directing transcription of the c-fos coding region and either the authentic c-fos 3' untranslated region (UTR) or the 3' UTR from human c-myc were inefficient at inducing transformation. In contrast, a recombinant that substituted most of the c-fos 3' UTR with the 3' portion of the simian virus 40 T-antigen gene transformed cells well. This difference in transformation efficiency appeared to be due to significantly higher levels of fos mRNA and protein expressed from the transforming recombinant. This, in turn, was due to the much greater stability of its mRNA compared with those from the poorly transforming recombinants containing the c-fos or c-myc 3' UTR. Thus, the 3' UTR of the human c-fos mRNA is responsible for its rapid degradation and limits the steady-state levels of transcript and protein. Cells transformed by the activated human c-fos plasmids contained increased amounts of partially modified c-fos protein (c-Fos). This form of c-Fos turned over much more rapidly than the highly modified form of c-Fos induced by serum stimulation.

Changes of HDL subfraction concentration and particle size by intralipid in vivo

The effects of the artificial triglyceride-phospholipid emulsion (10% intralipid) on HDL subfraction were studied in vivo. After a 14-h fast, subjects received intralipid via a 4-h infusion. Serum lipoproteins were analyzed before and at 4 and 6 h after the start of the infusion. At 4-h the following acute changes by infusion were observed. Triglyceride, phospholipid, free cholesterol, and esterified cholesterol in chylomicrons and VLDL increased. HDL2 as well as triglyceride, phospholipid, free cholesterol and protein within the HDL2 increased, while HDL3 decreased. An increase in HDL3 triglyceride was observed. The masses of apo A-I and A-II in the HDL2 density interval rose while these parameters fell in HDL3. There were decreases of apo C-II and C-III in the HDL subfractions and elevations in chylomicrons and VLDL. The particle size of the HDL subfractions increased. However, most of these acute changes at 4 h tended to disappear by 6 h. These results suggest that there is exchange of lipids and reversible transfer of apo C-II and C-III between HDL subfractions and intralipid, and conversion of HDL3 to HDL2 followed by the reverse conversion of HDL2 to HDL3 as the synthetic emulsion is cleared from the plasma.

Photorefractive phase conjugation with orthogonally polarized pumping beams

We solve the undepleted-pumps photorefractive four-wave mixing equations for the case of orthogonally polarized pump beams. Advantages over the parallel-polarized-pumps case include the potential for reflectivity enhancement and easy isolation of the conjugator from the source. The phase-conjugate reflectivities for both the parallel and orthogonally polarized pump beam cases were measured with a BaTiO3 crystal, and the results support our theoretical predictions.

Photorefractive time differentiation of coherent optical images

Two-beam coupling in photorefractive BaTiO(3) is used to perform time differentiation of time-varying coherent phase and amplitude images. Differentiation of one-dimensional signals and two-dimensional images is performed.

Characterization of D-2 dopamine receptors in a tumor of the rat anterior pituitary gland

Dopamine receptors in the 7315a transplantable rat anterior pituitary tumor were characterized using radioligand binding assays with [3H]spiroperidol ([3H]SPD) and assays of adenylate cyclase activity. Scatchard analysis of the binding of [3H]SPD yielded linear plots and a Kd value of 73 pM. Studies of the inhibition of the binding of [3H]SPD were performed with a series of competing ligands, including the antagonists domperidone, (+)-butaclamol and sulpiride and the agonists dopamine, bromocriptine and N-propylnorapomorphine. Inhibition curves for the antagonists gave Hill coefficients of approximately 1, consistent with the presence of only a single class of binding sites with a high affinity for [3H]SPD. In contrast, the Hill coefficient for dopamine was significantly less than 1. When assays were carried out in the presence of 300 microM GTP, the inhibition curve for dopamine was shifted to the right and the Hill coefficient increased to approximately 1. An effect of GTP on the affinity of a receptor for agonists is consistent with the existence of at least two agonist affinity states. Inhibition of the binding of [3H]SPD by the partial agonist bromocriptine was not affected when assays were carried out in the presence of GTP. The uniform low affinity of the selective serotonin antagonist ketanserin for these sites indicated that the radioligand was not labeling serotonin-2 receptors in this tissue. A good correlation was observed between the Ki values for competing ligands measured in the tumor and in homogenates of rat striatal tissue. Dopamine was shown to inhibit forskolin-stimulated adenylate cyclase activity.(ABSTRACT TRUNCATED AT 250 WORDS)