Identification of a functional mutation in pp32r1 (ANP32C)

No mutations or polymorphisms have previously been reported in pp32r1 (ANP32C; GenBank: AF008216.1). pp32r1 is part of the highly conserved ANP32 family, some of whose members are associated with control of histone acetylation, mRNA stability, and specialized forms of apoptosis. Although 87.6% identical at the protein level, pp32r1 is functionally distinct from pp32 (ANP32A) in its failure to suppress oncogenesis in in vitro transformation systems and its tumorigenicity in in vivo assays. The present study found that pp32r1 expression levels vary among human tumor cell lines, with the highest levels found in prostatic adenocarcinoma cell lines. pp32r1 also appears to be polymorphic at nucleotide g.4520 and nucleotide g.4664 in human tobacco-associated oral mucosal lesions, human fibroblast cell lines, and several carcinoma cell lines. PC-3 human prostatic adenocarcinoma cells likewise appear to be polymorphic at these loci, but additionally contain a g.4870T>C transversion mutation. The mutation results in a p.Tyr140His substitution, which lies in a functionally important region of the molecule. In the PC-3 prostate cancer line, the mutation is either homozygous, or hemizygous accompanied by loss of heterozygosity. ACHN cells stably transfected with pp32r1 containing this mutation showed a markedly increased rate of growth. The pp32r1 mutation could thus be causally associated with the neoplastic growth properties of PC-3, and be of potential clinical significance.     

A small-conductance charybdotoxin-sensitive,apamin-resistant Ca2+-activated K+ channel in aortic smooth muscle cells (A7r5 line and primary culture)

A small conductance K⁺ channel was identified in smooth muscle cells of the rat aortic cell line A7r5 and also in rat aortic smooth muscle cells in primary culture, using conventional single-channel recording techniques. The single-channel conductance shows no rectification, either in the range –70 to +40 mV under asymmetrical conditions (9.1 pS), or in the range –100 to +50 mV in symmetrical 150 mM K⁺ (37 pS). Channel activity is reversibly inhibited by extracellular application of charybdotoxin, with a concentration of 8 nM producing half-maximal inhibition. It is unaffected by apamin or scyllatoxin. Channel activity depends on the presence of free Ca²⁺ on the cytosolic face of the membrane, with an activation zone between 0.1 and 1 M. This small-conductance, charybdotoxin-sensitive, Ca²⁺-regulated K⁺ channel is activated by vasoconstrictors such as vasopressin and endothelin.     

The effect of denervation of Merkel cells in cats

The morphology of Merkel cells in sinus hair follicles of the upper lip (vibrissae with a circular blood sinus), and in touch domes of the glabrous skin of the nose, was investigated in cats up to 12 weeks after resection of the infraorbital nerve. Even 12 weeks after denervation there was neither an ultrastructural alteration of Merkel cells nor a reduction of their number in sinus hair follicles. Also in touch domes the Merkel cells did not disappear.     

Use of λgt11 and monoclonal antibodies to map the gene for the 60,000 dalton glycoprotein of infectious laryngotracheitis virus

To localize the gene encoding the 60 kD glycoprotein (gp60) of infectious laryngotracheitis virus (ILTV), a library of the ILTV genome was constructed in the gt11 expression vector. Twelve recombinant bacteriophages expressing gp60 epitopes as fusion products with -galactosidase were detected by immunoscreening with monoclonal antibodies specific for gp60. The ILTV DNA sequence contained in one of these recombinants 24-4 was used as a hybridization probe for mapping the insert sequence on the viral genome. The gene for the gp60 was located at map unit 0.72–0.77 in the unique long region (U_L) of the ILTV genome. The DNA sequence of the 1.2 kb insert of 24-4 containing the gp60 epitope was determined. The majority of deduced gp60 amino acid sequence has no homology with any of the known alphaherpesvirus glycoproteins.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number X 121209.     

Effects of guanabenz and guanfacine on postsynaptic α2-adrenoceptors in the rat submaxillary and parotid glands

Summary The effects of two ₂-agonists (guanfacine and guanabenz) on both the submaxillary and parotid gland of the rat were studied. Whereas guanfacine in doses ranging between 1,000 and 30,000 g/kg i.v. produced an immediate and persistent secretion of saliva from the submaxillary gland, guanabenz in doses as high as 40,000 g/kg did not induce measurable secretion either from the parotid or the submaxillary gland. Secretion clicited by guanfacine was not modified by yohimbine (300 g/kg) but was abolished by prazosin (100 g/kg).In both glands, low doses of either guanabenz (10 g/kg) or guanfacine (100 g/kg) markedly inhibited the secretory responses induced by noradrenaline, methacholine and substance P, but not that induced by isoprenaline. The inhibition caused by the ₂-agonists was greater for noradrenaline than for either methacholine or substance P. Blockade of ₂-adrenoceptors with yohimbine (300 g/kg) did not modify the response to noradrenaline, methacholine or substance P in either gland. However, the same dose of yohimbine injected 5 min before the ₂-agonists prevented the inhibitory effects of guanfacine and guanabenz on the response induced by either one of the three sialagogic agents. Guanabenz (10 g/kg) did not modify the increase in mean blood pressure observed after the different doses of noradrenaline employed to induce salivary secretion. Guanabenz (10 g/kg) and guanfacine (100 g/kg) did not change the time course of the secretion elicited by either noradrenaline, methacholine or substance P, since the degree of inhibition was of similar magnitude at all the periods of time analyzed.The results obtained give further support to the hypothesis that activation of ₂-adrenoceptors in the submaxillary as well as parotid gland of the rat inhibits secretory responses which are mediated by either muscarine, substance P and ₁-receptors and not those elicited by -adrenoceptors.Partially supported by grants no. 3111 k/83 CONICET and Res 40-5/4/84 SUBCYT     

Interactions of the enantiomers of 3-O-methyldobutamine with α- and β-adrenoceptors in vitro

Summary The enantiomers of 3-O-methyldobutamine, a metabolite of dobutamine, were evaluated for their - and -adrenoceptor mediated effects in vitro in a variety of isolated organs and in radioligand binding studies. Neither enantiomer of 3-O-methyldobutamine possessed ₁-adrenoceptor agonist activity in isolated guinea pig aorta. However, both enantiomers of 3-O-methyldobutamine were competitive ₁-adrenoceptor antagonists, with the (+)-enantiomer being approximately 10-fold more potent than the (-)-enantiomer as assessed either in guinea pig aorta or by displacement of ³H-prazosin binding from ₁-adrenoceptors in rat cerebral cortex. The ₁-adrenoceptor blocking activity of (+)-3-O-methyldobutamine was relatively potent and corresponded to a pA₂ of 7.33 in guinea pig aorta and a-log K _i of 7.72 in radioligand binding studies. Neither enantiomer of 3-O-methyldobutamine possessed ₂-adrenoceptor agonist activity in field-stimulated guinea pig ileum. Although (+)-3-O-methyldobutamine weakly inhibited the twitch response in field-stimulated guinea pig ileum, the response was not blocked by the selective ₂-adrenoceptor antagonist, yohimbine, and was found to result from weak anticholinergic activity (pA₂=5.06). Neither enantiomer of 3-O-methyldobutamine possessed ₁-adrenoceptor agonist activity in guinea pig atria, however the (+)-enantiomer was a weak noncompetitive antagonist at ₁-adrenoceptors. In contrast, both enantiomers of 3-O-methyldobutamine were weak ₂-adrenoceptor agonists in rat uterus, however these weak effects were not highly stereoselective, which was also confirmed in radioligand binding studies. The results of the present study indicate that 3-O-methyldobutamine is a potent and highly selective ₁-adrenoceptor antagonist, with minimal activity at ₂-, ₁- and ₂-adrenoceptors. It is hypothesized that the potent ₁-adrenoceptor antagonist activity of 3-O-methyldobutamine, which resides predominantly in the (+)-enantiomer, may play a role in the hemodynamic effects of dobutamine, by contributing, in part, to the decrease in total peripheral vascular resistance observed following administration of dobutamine.     

An analysis of theα-adrenoceptor modulation of vasomotor tone at the level of lateral medullary pressor area (LMPA)

Summary Microinjection of noradrenaline and clonidine into lateral medullary pressor area (LMPA) of chloralose anaesthetized cats produced dose dependent decrease in blood pressure without affecting heart rate, while phenylephrine did not elicit any cardiovascular response. Selective ₂-adrenoceptor, antagonists idazoxan and piperoxan, microinjected locally, blocked the effects of the agonists but prazosin and phenoxybenzamine, which are relatively selective for ₁-adrenoceptors, failed to do so. Clonidine did not elicit any response in guanethidine pretreated cats but noradrenaline microinjected into LMPA of these animals induced a pressor response which was blocked by prazosin pretreatment. It is concluded that catecholaminergic fibres impinging upon this are inhibit the activity of the inhibitory second order baroreceptor neurone by activating ₁-adrenoceptors while ₂-adrenoceptors situated presynaptically on these inhibitory catecholaminergic nerve terminals are responsible for the manifestation of the hypotensive effect of clonidine and exogenously administered noradrenaline.     

138. Zum Krankheitsbild der primären chronischen intestinalen Pseudoobstruktion (CIPSO) im Kindesalter

Zusammenfassung Bei der primären CIPSO besteht eine Ileussymptomatik ohne mechanische Occlusion aufgrund fehlender bzw. ineffektiver Peristaltik trotz normaler Darmwandstruktur. Es werden die neonatale und adulte Form unterschieden. Die Pathogenese ist ungeklärt. Bei den neonatalen Krankheitsbildern der CIPSO (neonatale CIPSO, MMIHS, congenitales short-bowel-Syndrom) besteht ein progredienter Ileus, bei der adulten Form ein chronischer, letztlich aber auch letaler Verlauf. Anhand von 5 Kindern mit einer primären CIPSO wird die Problematik von Diagnostik und Therapie besprochen.     

Effects of pentagastrin and carbachol on the gastric histamine level in α-fluoromethylhistidine-treated mice and rats

Summary The gastric mucosal histamine level in mice increased by about 80% and 100% after fasting for 24 and 48 h, respectively. In non-fasted mice, -fluoromethylhistidine (-FMH), a specific histidine decarboxylase inhibitor, significantly decreased the histamine level, the reduction amounting to 35% and 49%, 2 h and 4 h after treatment, respectively. In mice fasted for 24 h, a significant decrease of 42% was observed 4 h after treatment. However, in mice fasted for 48 h, no significant decrease was seen even 4 h after -FMH treatment. Therefore, the histamine-releasing effect of re-feeding and drugs on the gastric mucosa was examined in vivo, using animals fasted for 48 h and subsequently treated with -FMH. Food given simultaneously with -FMH to 48-h fasted mice significantly decreased the histamine level 4 h later. Pentagastrin and carbachol administered alone (0.25–2.0 mg/kg, i.p.) had no significant effect on the histamine level. However, the combined treatment with these drugs significantly decreased the histamine level. In rats fasted for 48 h and treated with -FMH, pentagastrin (0.25 and 0.5 mg/kg, i.p.) but not carbachol (0.125 – 0.5 mg/kg, i. p.) caused a significant decrease in the mucosal histamine level. In contrast to mice, the effect of the combined treatment with pentagastrin and carbachol was not synergistic in rats. These findings suggest that gastrin acts synergistically with acetylcholine in the histamine release from the gastric mucosa in mice, whereas such synergism may not occur in rats. Send offprint requests to K. Saeki