Renal responsiveness to parathyroid hormone in a case of nonfamilial hypophosphatemic osteomalacia

Summary Plasma immunoreactive parathyroid hormone level, urinary excretion of adenosine cyclic 3,5-monophosphate (cyclic AMP) and the sensitivity of the renal tubule to calcium infusion and to parathyroid extract were investigated in a patient with nonfamilial hypophosphatemic osteomalacia. Plasma immunoreactive parathyroid hormone concentration was normal and basal urinary excretion of cyclic AMP was increased. Renal cortical adenylate cyclase, as measured by urinary cyclic AMP excretion, was certainly as sensitive to exogenous parathyroid extract as in normal subjects. After a previous calcium infusion, a greater parathyroid-hormone-sensitive component of phosphorus transport in the kidney was present than in two control subjects. Our results indicate that in nonfamilial hypophosphatemic osteomalacia the renal tubule could be hyperresponsive to parathyroid hormone.This work was supported by a grant (n^o 20,463) from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

Comparison of the 5′ Leader Sequences of North American Isolates of Reference and Field Strains of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)

The 5 leader is documented to be an important regulatory element in many (+) ssRNA virus genome. To understand the significance of the 5 leader RNA of PRRSV, we determined the complete leader sequences of fifteen different North American strains of PRRSV and predicted their secondary structures. Viruses analysed included three reference strains and nine field strains originating from different geographic locations. To further examine the leader region, one of the field strains was adapted to grow in tissue culture, and three clones were isolated. We also predicted the secondary structures of two European strains based on their published sequences. The predicted RNA secondary structures of the leader sequences suggested the existence of three conserved domains formed by the 5 region of the leader among the North American strains, two of which were conserved in the European strains. A variable structural domain was predicted from the 3 region of the leader sequences of the North American strains, where all tissue culture-adapted isolates were characterized by a stem-loop while field isolates were characterized by an internal bulge within the stem-loop.     

Cyclische Nucleotide als intracelluläre Überträgerstoffe bei Hormonwirkungen

Zusammenfassung Hormone dienen als extracelluläre Informationsüberträger zwischen ihrem Bildungsort, einer endokrinen Drüse, und den Zellen, deren Funktion sie regulieren. Durch die Reaktion des Hormons mit den an der Zellmembran gelegenen Receptoren wird die Aktivität der mit diesen eng verknüpften Adenyl-Cyclase beeinflußt. Die meisten Hormone erhöhen in ihrem Zielorgan die Aktivität dieses Enzyms und führen hierdurch zu einem raschen Anstieg der intracellulären Konzentration von Adenosin-3:5-monophosphat (Ado-3:5-P). Dieses cyclische Nucleotid wird durch eine spezifische Phosphodiesterase zu Adenosin-5-monophosphat abgebaut. Auch die Aktivität dieses Enzyms bestimmt die intracelluläre Ado-3:5-P-Konzentration, die im Vergleich zu der anderer Nucleotide sehr gering ist.Ado-3:5-P beeinflußt als zweiter, intracellulärer Überträgerstoff die Aktivität zahlreicher Schlüsselenzyme. Die Ado-3:5-P-Konzentration bestimmt hierdurch das Gleichgewicht verschiedener Stoffwechselwege zueinander und damit die Reaktion einer Zelle auf eine hormonale Stimulierung. An einer Reihe von Enzymen wird die durch Ado-3:5-P bedingte Aktivitäts-Änderung durch einen gleichartigen Mechanismus bewirkt. Das cyclische Nucleotid stimuliert Proteinkinasen, die eine Phosphatgruppe des ATP auf verschiedene Proteine übertragen und hierdurch deren Eigenschaften verändern können. So steigt bei Phosphorylierung durch eine Ado-3:5-P-stimulierbare Proteinkinase die Aktivität der Triglyceridlipase und der Glykogen-Phosphorylase-b-kinase an, dagegen nimmt die Aktivität der Glykogen-Synthetase ab; durch Phosphorylierung von Histonen kann deren Repressorcigenschaft vermindert und die Synthese von Enzymen gesteigert werden.In manchen tierischen Geweben wurde auch eine spezifisch durch Guanosin-3:5-monophosphat (Guo-3:5-P) stimulierbare Proteinkinase nachgewiesen. Dieses cyclische Nucleotid kommt wie Ado-3:5-P in allen Säugerorganen vor. Die Bildung von Guo-3:5-P aus GTP wird durch die Guanyl-Cyclase katalysiert, ein Ferment, das im Gegensatz zur Adenyl-Cyclase zum großen Teil nicht an die Zellmembranen gebunden ist. Die Konzentration von Guo-3:5-P in verschiedenen Geweben, im Blutplasma und im Urin wird durch Hormone beeinflußt. Es ist noch nicht bekannt, welche hormonalen Regulationen durch Guo-3:5-P vermittelt werden; dagegen ist bei vielen, rasch einsetzenden Hormonwirkungen die Beteiligung von Ado-3:5-P nachgewiesen worden.

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Abkürzungen Ado-3:5-P Adenosin-3:5-monophosphat - dAdo-3:5-P Desoxy-adenosin-3:5-monophosphat - Guo-3:5-P Guanosin-3 : 5-monophosphate - Nuc-3:5-P Nucleosid-3:5-monophosphat - NTP Nucleosidtriphosphat - NMP Nuclcosid-5-monophosphat - dATP Desoxyadenosintriphosphat - P_i anorganisches Phosphat - PP_i anorganisches Pyrophosphat - DNS Desoxyribonucleinsäure - RNS Ribonucleinsäure - r-RNS ribosomale RNS - m-RNS Boten-RNS - Glykogen-Synthetase UDP-Glucose--1,4-glucan--4-glucosyltransferase - ICSH interstitial-cell-stimulating hormone     

Inhibition by somatostatin of adenosine-3′,5′-monophosphate stimulated hepatic ribosomal protein synthesis

Summary Somatostatin which inhibits the secretion of various pituitary and intestinal hormones has been suspected to exert these effects by inhibiting adenosine-3,5-monophosphate accumulation in the respective endocrine gland. Our results, obtained by cell free protein synthesis and by sedimentation through sucrose gradients of ribosomes, prepared from rat liver after incubation with cyclic AMP and/or somatostatin also suggest this antagonism between somatostatin and cyclic AMP. In addition, they indicate that this antagonism is not restricted to endocrine tissues.Supported by a grant (M2-2777) of the Österreichischer Fonds zur Förderung der wissenschaftlichen Forschung     

Activation of respiration of liver mitochondria in various metabolic states by cyclic 3′,5′-AMP

Cyclic 3,5-AMP (10^–6M) activates respiration of the liver mitochondria in all metabolic states and neither changes nor increases the rate of phosphorylation during oxidation of saturating concentrations of isocitrate and succinate. For the effect to be manifested, preincubation of the mitochondria or liver homogenate with cyclic AMP is necessary. The fifth fraction of serum albumin and EDTA do not abolish the effect. Noradrenalin (NA) increases mitochondrial respiration only on incubation with the homogenate. Effects of NA and cyclic AMP do not undergo summation, and the effect of the former is probably mediated by cyclic AMP. The results do not confirm the decisive role of uncoupling of respiration and phosphorylation or accumulation of the oxidation substrate, but instead they suggest activation of mitochondrial enzymes.Department of Biochemistry and Central Research Laboratory, Krasnoyarsk Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. S. Debov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 3, pp. 291–294, March, 1978.     

Negative inotropic effect of cyclic GMP in cardiac fiber fragments

Summary The force of spontaneously beating cardiac cellular fragments obtained from mice heart by homogenization was recorded in presence of cyclic guanosine –3.5-monophosphate (cGMP) and cyclic 8-bromguanosine –3.5-monophosphate in concentrations of 3×10^–6 M –33×10^–6 M. The nucleotide decreased the force and reduced the rate of spontaneity. Eventually the preparation became quiescent. It is thought that this nucleotide either reduces the capacity to sequester calcium or affects its release from the sarcotubular system.     

The nonselective cation channel in the basolateral membrane of rat exocrine pancreas

Nonselective Ca²⁺-sensitive cation channels in the basolateral membrane of isolated cells of the rat exocrine pancreas were investigated with the patch clamp technique. With 1.3 mmol/l Ca²⁺ on the cytosolic side, the mean openstate probabilityP _o of one channel was about 0.5. In insideout oriented cell-excised membrane patches the substances diphenylamine-2-carboxylic acid (DPC), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC) were applied to the cytosolic side. These compounds inhibited the nonselective cation channels by increasing the mean channel closed time (slow block). 100 mol/l of NPPB or DPC decreasedP _o from 0.5 (control conditions) to 0.2 and 0.04, respectively, whereas 100 mol/l of DCDPC blocked the channel completely. All effects were reversible. 1 mmol/l quinine also reducedP _o, but in contrast to the abov mentioned substances, it induced fast flickering. Ba²⁺ (70 mmol/l) and tetraethylammonium (TEA⁺; 20 mmol/l) had no effects. We investigated also the stilbene disulfonates 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid (SITS), 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) and 4,4-dinitro-2,2-stilbenedisulfonate (DNDS). 10 mol/l SITS applied to the cytosolic side increasedP _o from 0.5 to 0.7 and with 100 mol/l SITS the channels remained nearly permanently in its open state (P _o1). A similar activation of the channels was also observed with DIDS and DNDS. These effects were poorly reversible. The stilbene disulfonates acted by increasing the channel mean open time. When the channel was inactivated by decreasing bath Ca²⁺ concentration to 0.1 mol/l, addition of 100 mol/l of SITS had no effect. Similarly, reducing bath Ca²⁺ concentration from 1.3 mmol/l in presence of 100 mol/l SITS (channels are maximally activated) to 0.1 mol/l, inactivated the channels completely. These results demonstrate, that SITS can only activate the channels in the presence of Ca²⁺. SITS had no effects, when applied to the extracellular side in outside out patches. In summary, the substances DPC, NPPB and DCDPC inhibit nonselective cation channels, where DCDPC has the most potent and NPPB the smallest effect; whereas SITS, DIDS and DNDS activate the channel when applied from the cytosolic side in the presence of Ca²⁺ ions.     

A conserved sequence motif at the 5′ terminus of the Southampton virus genome is characteristic of the Caliciviridae

We have determined the 5 terminal cDNA sequence for the genome of Southampton virus, a recently characterized, human, small round-structured virus (SRSV). Genomic RNA was extracted directly from a stool sample and amplified by RT-PCR by homopolymer tailing of the 3 terminus of the cDNA. The additional sequence increases the overall length of the Southampton virus genome by 12 nucleotides, resulting in a significant change to the genome organization by extending the first large open reading frame (ORF) by 51 amino acids. The 5 terminal bases pGpT and the presence of conserved genome and putative subgenomic RNA terminal motifs are now prominent features shared between the human SRSV Southampton virus and the animal caliciviruses rabbit hemorrhagic disease virus and feline calicivirus.     

Synchronizing action of cyclic AMP on the mitotic cycle of ehrlich's ascites carcinoma cells

The number of mitoses and of DNA-synthesizing cells in an Ehrlich's ascites carcinoma was studied during the 24 h after injection of dibutyryl cyclic 3,5-adenosine monophosphate. As a result of preprophase inhibition and, probably, of stimulation of entry of the cells into the synthetic period, a large number of cells commences mitosis simultaneously 8 h after the injection. The resulting synchronization of mitosis in the cell population of the tumor is evaluated.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 66–68, January, 1976.     

Analysis of the role of the NUC1 endo/exonuclease in yeast mitochondrial DNA recombination

Mitochondrial DNA recombination was reduced in an yeast mutant lacking the NUC1 endo/exonuclease. Between linked markers in either the or cob region the frequency of recombination decreased nearly 50% compared to wild-type. Gene conversion frequencies in the var1 gene and in the region were also lower in the mutant strain. In particular, the gradient of gene conversion at was most affected by the absence of the NUC1 nuclease. In crosses between nuclease-deficient and wild-type strains, gene conversion frequencies at were reduced only when the ₊ allele was contributed to the zygote by the nuclease-deficient parent. We propose that the 5 exonuclease activity of the NUC1 nuclease functions during recombination to enlarge heteroduplex tracts following a double-strand break in DNA. In crosses between nuclease-deficient and wild-type strains, the anisotropy in gene conversion frequencies at is hypothesized to be due to the slow mixing of parental motochondrial membranes as they fuse in the zygote.     

Nitric oxide mediated modulation of free radical generation response in the rat polymorphonuclear leukocytes: A flowcytometric study

Nitric oxide (NO) synthesis and free radical generation from polymorphonuclear leukocytes (PMNs) play an important role in several pathological conditions. It is therefore important to understand the regulatory mechanisms of free radical generation from PMNs. Flowcytometry can be used to assess generation of reactive oxygen and nitrogen species from PMNs by using fluorescent probes. In the present study regulation of NO synthesis in the control and lipopolysaccharide (LPS) treated rat PMNs has been investigated. Free radical generation was assessed by flow cytometry using a dye, 27-dichlorodihydrofluorescein diacetate (DCFDA), dihydrorhodamine-123 (DHR) and 4,5-diaminofluorescein diacetate (DAF). Superoxide dismutase (SOD), and catalase significantly attenuated the arachidonic acid (AA, 1 × 10^–6 M) induced free radical generation, while 4-aminobenzoicacid hydrazide (ABH), myeloperoxidase (MPO) inhibitor had no significant effect. Intracellular and extracellular calcium levels also modulated FR generation. AA induced free radical generation from PMNs was also enhanced significantly after LPS treatment. NO synthase (NOS) inhibitors, aminoguanidine (AG) and 7-nitroindazole (NI) inhibited arachidonic acid induced free radical generation from LPS treated PMNs, while in control PMNs NOS inhibition had no effect. Augmentation of free radical generation from rat PMNs following LPS treatment seems to be regulated by NO.     

Variations with age of immunoreactive serum trypsin: Higher reference ranges in “Healthy” elderly people

Summary According to the literature, the mean values of immunoreactive serum trypsin (IRT) (RIA-gnost Hoechst) in controls vary considerably between 150 and 283 ng/ml. The reasons for these variations are unknown. The purpose of the present investigation was to study the variations of IRT in relation to age in adults. We studied 124 hospital controls, who were without evidence of pancreatic disease or renal insufficiency and who varied in age between 17 and 84 years. Utilizing the kit of Hoechst, IRT was determined in fasting serum specimens. The mean (±SD) in patients over 60 years was 469.6±197.4 ng/ml, in contrast to 309.1±118.9 ng/ml (30–59 years) and 209.7±80.7 (<30 years). Of cases over 60 years 36.5% had elevated IRT levels above 500 ng/ml. In 25 cases over 60 years no correlation was found between IRT levels and creatinine clearance and in eight of ten cases of this group with high IRT (>500 ng/ml) the serum pancreatic isoamylase levels were normal. The data indicate that in the diagnosis of pancreatic disease the higher reference ranges in the elderly people have to be taken into account. The age-related higher reference ranges seem not to be due to subclinical renal disease nor to clinically evident pancreatic disease.The RIA-gnost Trypsin was kindly supplied by Hoechst Pharma, Frankfurt/M, and the Isoamylase Test by Pharmacia, Uppsala     

Effect of benzodiazepines in 5′-nucleotidase activity of rat brain

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