Pharmacokinetics of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist. 3rd communication: metabolism in rats, rabbits, dogs and monkeys, and effects on hepatic drug-metabolizing enzyme activities in rats after repeated administration

The metabolism of NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoro-methanesulfonanilide++ + hydrochloride, CAS 137431-04-0), a phenethylamine class alpha 1A-adrenoceptor agonist, was investigated in rats, rabbits, dogs, and monkeys after single intravenous or oral administration of 14C-NS-49 or unlabeled NS-49. The N-acetylated form, the only metabolite was identified in the urine of all the species tested by thin layer chromatography and mass spectrometry. The unchanged drug and N-acetylated form accounted for almost all the radioactivity in the urine. The order of the percentage of the N-acetylated form in the urinary radioactivity after oral administration was monkeys (66%) > rabbits (22%) > rats (14%) > dogs (1.3%). There were no marked differences between the intravenous and oral routes in the percentages of NS-49 and its N-acetylated form for the rats, rabbits, and dogs, indicative of negligible first-pass metabolism. In the monkeys, however, the percentage of NS-49 in the urinary radioactivity after oral administration was about half that after intravenous injection due to first-pass metabolism, and the N-acetylated form showed an inverse relation. The N-acetylated form also was the only metabolite in the plasma and tissues (liver, kidney, heart, and lung) 1 and 4 h after the oral administration of 14C-NS-49 to rats. NS-49 and its N-acetylated form accounted for more than 80% of the radioactivity in the plasma and the four tissues. The percentages of NS-49 and its N-acetylated form in the total radioactivity did not differ markedly among the plasma and tissues. Repeated oral administrations of 1, 10, and 100 mg/kg of NS-49 to male rats once a day for 7 days had no effects on their hepatic drug-metabolizing enzyme activities.

Characterization of a novel giant scaffolding protein, CG-NAP, that anchors multiple signaling enzymes to centrosome and the golgi apparatus

A novel 450-kDa coiled-coil protein, CG-NAP (centrosome and Golgi localized PKN-associated protein), was identified as a protein that interacted with the regulatory region of the protein kinase PKN, having a catalytic domain homologous to that of protein kinase C. CG-NAP contains two sets of putative RII (regulatory subunit of protein kinase A)-binding motif. Indeed, CG-NAP tightly bound to RIIalpha in HeLa cells. Furthermore, CG-NAP was coimmunoprecipitated with the catalytic subunit of protein phosphatase 2A (PP2A), when one of the B subunit of PP2A (PR130) was exogenously expressed in COS7 cells. CG-NAP also interacted with the catalytic subunit of protein phosphatase 1 in HeLa cells. Immunofluorescence analysis of HeLa cells revealed that CG-NAP was localized to centrosome throughout the cell cycle, the midbody at telophase, and the Golgi apparatus at interphase, where a certain population of PKN and RIIalpha were found to be accumulated. These data indicate that CG-NAP serves as a novel scaffolding protein that assembles several protein kinases and phosphatases on centrosome and the Golgi apparatus, where physiological events, such as cell cycle progression and intracellular membrane traffic, may be regulated by phosphorylation state of specific protein substrates.

Pharmacokinetics of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist. 2nd communication: Absorption and excretion in rabbits, dogs and monkeys after a single administration of 14C-NS-49

The absorption and excretion of NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, CAS 137431-04-0), a phenethylamine class alpha 1A-adrenoceptor agonist, were studied in male rabbits, dogs, and monkeys after intravenous or oral administration of 14C-NS-49. After single oral administration of 14C-NS-49 (1 mg/kg) to rabbits and dogs, the plasma concentrations of radioactivity and NS-49 reached maximums at about 2 h, then decreased triexponentially. In monkeys, both maximums were reached 3 h after administration, and both concentrations decreased biexponentially. Most of the plasma radioactivity was due to unchanged NS-49 in the rabbits and dogs, indicating poor metabolism of this drug. In the monkeys, however, the percentage of unchanged NS-49 in the plasma radioactivity was low, about 20%, during a 24-h period after oral administration. After intravenous and oral administrations of 14C-NS-49, radioactivity was primarily excreted in the urine in all the species tested. The absorption rates found by comparing the urinary excretions of radioactivity after both routes of administration were 71% for rabbits, 92% for dogs, and 95% for monkeys. The percentages of NS-49 in the radioactivity excreted in the urine after intravenous and oral administrations, respectively, were 77% and 68% for rabbits, 96% and 96% for dogs, and 57% and 29% for monkeys. The systemic availability calculated from the unchanged drug excreted in the urine was similar to the absorption rates for rabbits and dogs. This indicates that first-pass metabolism of this drug is very limited in both species. The systemic availability for monkeys, however, was about half the absorption rate due to the first-pass effect. Renal clearance accounted for most of the total clearance for rabbits and dogs, but only about half that for monkeys.

Renal excretion mechanism of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist

Renal handling of NS-49, which is an organic cation and a chiral compound, was investigated in rats, rabbits and dogs. Renal clearance (Cl(re)) of NS-49 was 3.4-fold the glomerular filtration rate (GFR) in the rat in vivo study. The clearance ratio (Cl(re)/GFR) approached unity during cimetidine infusion. Change in the urine flow rate or urinary pH did not affect the Cl(re) of NS-49. The stop-flow patterns of NS-49 in the rabbits and dogs showed a secretion peak in the proximal tubules. On concomitant administration of cimetidine, the secretion peak disappeared, the stop-flow pattern showing neither a secretion nor reabsorption peak. These findings indicate that in these species NS-49 undergoes glomerular filtration and extensive proximal tubular secretion, but little reabsorption. A transport mechanism study of NS-49 in brush-border membrane vesicles (BBMVs) isolated from rat kidney cortex showed that it is transported via the carrier-mediated H(+)/organic cation antiport system. In the rat renal clearance studies (in vivo) tubular secretion of NS-49 was significantly inhibited by quinine (p<0.01) but not by quinidine. Transport studies done with rat BBMVs (in vitro) also showed quinine to be more potent than quinidine in inhibiting NS-49 uptake. These results indicate that stereoselective interaction occurs in active renal tubular secretion.

Pharmacokinetics of NS-49, a phenethylamine class alpha 1A-adrenoceptor agonist. 1st communication: absorption and excretion in rats after a single administration of 14C-NS-49

The absorption and excretion of NS-49 ((R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, CAS 137431-04-0), a phenethylamine class alpha 1A-adrenoceptor agonist, were studied in rats after a single administration of 14C-NS-49. In addition, the protein binding of this drug was investigated in vivo and in vitro. After oral administration of 14C-NS-49 (1 mg/kg) to male rats, the radioactivity concentrations in the blood and plasma reached maximums within 1 h, then decreased biexponentially with respective elimination half-lives of 25.4 and 11.9 h. Most of the plasma radioactivity was due to unchanged NS-49, indicating of the poor metabolism of this drug in rats. The results of the in situ absorption study using the intestinal loop method showed that 14C-NS-49 was well absorbed from the small intestine. Systemic availability was high (86%), as determined by a comparison of the areas under the plasma concentration-time curves of unchanged NS-49 for oral and intravenous administrations. Food affected the absorption of NS-49. There were no significant sex-related differences in the plasma concentration profiles after the intravenous administration of 14C-NS-49 (p > 0.05). NS-49 was primarily eliminated by renal excretion, 76% and 62% of the dose being excreted unchanged in the urine after intravenous and oral administrations, respectively. The absorption rate, determined on the basis of the urinary excretion of radioactivity, was 83%, being almost the same as the systemic availability. First-pass metabolism of NS-49, therefore, is considered to be very limited in rats. The excretion of radioactivity in the bile within 48 h after the oral administration of 14C-NS-49 (1 mg/kg) was 5.9% of the dose, and the excretion of radioactivity in the exhaled air after the intravenous administration (0.2 mg/kg) was negligible. The percentage of 14C-NS-49 bound to serum proteins in vitro was less than 15% in all the animal species tested. The percentage of radioactivity bound to rat serum proteins after the oral administration of 14C-NS-49 (1 mg/kg) was 16-21%.

Interaction of the small G protein RhoA with the C terminus of human phospholipase D1

Mammalian phosphatidylcholine-specific phospholipase D1 (PLD1) is a signal transduction-activated enzyme thought to function in multiple cell biological settings including the regulation of membrane vesicular trafficking. PLD1 is activated by the small G proteins, ADP-ribosylation factor (ARF) and RhoA, and by protein kinase C-alpha (PKC-alpha). This stimulation has been proposed to involve direct interaction and to take place at a distinct site in PLD1 for each activator. In the present study, we employed the yeast two-hybrid system to attempt to identify these sites. Successful interaction of ARF and PKC-alpha with PLD1 was not achieved, but a C-terminal fragment of human PLD1 (denoted "D4") interacted with the active mutant of RhoA, RhoAVal-14. Deletion of the CAAX box from RhoAVal-14 decreased the strength of the interaction, suggesting that lipid modification of RhoA is important for efficient binding to PLD1. The specificity of the interaction was validated by showing that the PLD1 D4 fragment interacts with glutathione S-transferase-RhoA in vitro in a GTP-dependent manner and that it associates with RhoAVal-14 in COS-7 cells, whereas the N-terminal two-thirds of PLD1 does not. Finally, we show that recombinant D4 peptide inhibits RhoA-stimulated PLD1 activation but not ARF- or PKC-alpha-stimulated PLD1 activation. These results conclusively demonstrate that the C-terminal region of PLD1 contains the RhoA-binding site and suggest that the ARF and PKC interactions occur elsewhere in the protein.

Intermolecular and interdomain interactions of a dynamin-related GTP-binding protein, Dnm1p/Vps1p-like protein

Dnm1p/Vps1p-like protein (DVLP) is a mammalian member of the dynamin GTPase family, which is classified into subfamilies on the basis of the structural similarity. Mammalian dynamins constitute the dynamin subfamily. DVLP belongs to the Vps1 subfamily, which also includes yeast Vps1p and Dnm1p. Typical structural features that discriminate between members of the Vps1 and dynamin subfamilies are that the former lacks the pleckstrin homology and Pro-rich domains. Dynamin exists as tetramers under physiological salt conditions, whereas under low salt conditions, it can polymerize into spirals that resemble the collar structures seen at the necks of constricted coated pits. In this study, we found that DVLP is also oligomeric, probably tetrameric, under physiological salt conditions and forms sedimentable large aggregates under low salt conditions. The data indicate that neither the pleckstrin homology nor Pro-rich domain is required for the self-assembly. Analyses using the two-hybrid system and co-immunoprecipitation show that the N-terminal region containing the GTPase domain and a domain (DVH1) conserved across members of the dynamin and Vps1 subfamilies, can interact with the C-terminal region containing another conserved domain (DVH2). The data on the interdomain interaction of DVLP is compatible with the previous reports on the interdomain interaction of dynamin. Thus, the self-assembly mechanism of DVLP appears to resemble that of dynamin, suggesting that DVLP may also be involved in the formation of transport vesicles.

The role of PKN in the regulation of alphaB-crystallin expression via heat shock transcription factor 1

We previously reported that PKN, a fatty acid-activated serine/threonine protein kinase, translocates from the cytosol to the nucleus by stresses such as heat shock, sodium arsenite, and serum starvation. To clarify the role of PKN under heat stress, we examined whether PKN regulates the expression of heat shock proteins. Co-expression of heat shock transcription factor 1 (HSF1) and the catalytically active fragment of PKN induced the accumulation of alphaB-crystallin but not HSP27 and HSP70 in HeLa S3 cells. The expression of the reporter gene for alphaB-crystallin promoter was activated by co-expression of HSF1 and the catalytically active fragment of PKN, and this activation was dependent on the protein kinase activity of PKN. Deletion analysis of the alphaB-crystallin promoter region revealed that both the proximal and the distal heat shock elements were necessary for the transactivation. These results raise the possibility that there is a signal transduction pathway mediating stress signals for the accumulation of alphaB-crystallin by HSF1 and PKN.

[The usefulness of MRCP in the initial diagnosis of the biliary and pancreatic diseases compared with ERCP]

The purpose of this study was to determine the effectiveness and the limitation of the MR cholangiopancreatography (MRCP) in the initial diagnosis for the biliary and pancreatic diseases compared with the image of Endoscopic retrograde cholangiopancreatography (ERCP). MRCP showed higher performance toward the discovery of the choledocholithiasis of a diameter 4 mm and more. Furthermore, MRCP reflected a malignant tumor at the constrictive part and the dilated proximal part of the biliary and pancreatic duct in 23 example all. An advantage of ERCP was the ability to carry out biopsies and therapeutic procedures, such as biliary drainage and sphincterotomy, while MRCP was an important diagnostic modality in the work-up of the biliary and pancreatic diseases and could help in planning treatment. MRCP would become the examination method first used, and it would be popularized all the more from now on.

Event-related potentials during mental imagery

Event-related potentials(ERPs) were measured while subjects were constructing mental images of a letter of the alphabet. Following presentation of an uppercase letter, subjects were asked to form a mental image of the same letter in lower case, and determine whether or not it had an ascending or descending stroke (ascender or descender). ERPs were measured in a passive condition and then compared with the ERPs recorded while the subjects performed the discrimination task. During the discrimination task, negative potentials were observed in left frontal, central and parietal areas around 220 ms after the stimulus onset. These early negative potentials were dominant in the left hemisphere and are probably related to working memory processes in mental image formation.

Proteolytic activation of PKN by caspase-3 or related protease during apoptosis

PKN, a fatty acid- and Rho-activated serine/threonine kinase having a catalytic domain highly homologous to protein kinase C (PKC), was cleaved at specific sites in apoptotic Jurkat and U937 cells on Fas ligation and treatment with staurosporin or etoposide, respectively. The cleavage of PKN occurred with a time course similar to that of PKCdelta, a known caspase substrate. This proteolysis was inhibited by a caspase inhibitor, acetyl-Asp-Glu-Val-Asp-aldehyde. The cleavage fragments were generated in vitro from PKN by treatment with recombinant caspase-3. Site-directed mutagenesis of specific aspartate residues prevented the appearance of these fragments. These results indicate that PKN is cleaved by caspase-3 or related protease during apoptosis. The major proteolysis took place between the amino-terminal regulatory domain and the carboxyl-terminal catalytic domain, and it generated a constitutively active kinase fragment. The cleavage of PKN may contribute to signal transduction, eventually leading to apoptosis.

A protein kinase, PKN, accumulates in Alzheimer neurofibrillary tangles and associated endoplasmic reticulum-derived vesicles and phosphorylates tau protein

A possible role for a protein kinase, PKN, a fatty acid-activated serine/threonine kinase with a catalytic domain homologous to the protein kinase C family and a direct target for Rho, was investigated in the pathology of Alzheimer's disease (AD) using a sensitive immunocytochemistry on postmortem human brain tissues and a kinase assay for human tau protein. The present study provides evidences by light, electron, and confocal laser microscopy that in control human brains, PKN is enriched in neurons, where the kinase is concentrated in a subset of endoplasmic reticulum (ER) and ER-derived vesicles localized to the apical compartment of juxtanuclear cytoplasm, as well as late endosomes, multivesicular bodies, Golgi bodies, secretary vesicles, and nuclei. In AD-affected neurons, PKN was redistributed to the cortical cytoplasm and neurites and was closely associated with neurofibrillary tangles (NFTs) and their major constituent, abnormally modified tau. PKN was also found in degenerative neurites within senile plaques. In addition, we report that human tau protein is directly phosphorylated by PKN both in vitro and in vivo. Thus, our results suggest a specific role for PKN in NFT formation and neurodegeneration in AD damaged neurons.

Localization of PKN mRNA in the rat brain

Distribution of mRNA encoding PKN, a fatty acid and RhoA-activated serine/threonine protein kinase with a catalytic domain highly homologous to that of protein kinase C, was investigated in the rat brain using in situ hybridization histochemistry. PKN mRNA proved to be heterogenously distributed. The highest signals were observed in the cerebellum, in limbic systems such as olfactory bulb, hippocampal formation and limbic cortex, and in regions involved in central autonomic and neuroendocrine functions, such as hypothalamic ventromedial, dorsomedial, lateroanterior and arcuate nuclei, paraventricular hypothalamic nucleus and locus coeruleus. PKN mRNA was also highly expressed in dopaminergic neurons such as the ventral tegmental area and substantia nigra pars compacta, in serotonergic raphe neurons, and in cholinergic neurons such as nucleus diagonal band, nucleus basalis, and lateral dorsal tegmental nucleus. The distribution of PKN mRNA differed from that for PKC isoforms. As the localization of PKN mRNA is heterogeneous, PKN may have a specific role in distinct populations of nerve cells.

Differential diagnosis of mucin-producing tumors of the pancreas by intraductal ultrasonography and peroral pancreatoscopy

BACKGROUND AND STUDY AIMS

Although mucin producing tumors of the pancreas have been recently recognized as premalignant or malignant neoplasms, their diagnosis and management have been undetermined as yet. The aim of this study was to evaluate the capability of intraductal ultrasonography (IDUS) and peroral pancreatoscopy (PPS) in the differential diagnosis of mucin-producing tumors compared to that of other diagnostic tools.

PATIENTS AND METHODS

From 1986 to 1997, 31 patients with mucin-producing tumors of the pancreas underwent surgery.

RESULTS

Histologically, in patients with adenocarcinoma, papillary tumorous lesions within the pancreatic ducts were 3 mm or more in maximum height. The detection rates for such lesions were 29% with US, 21% with CT, 86% with EUS, 100% with IDUS and 83% with PPS. In patients with adenocarcinoma, PPS revealed taller papillary lesions with redness and/or capillary vessels. Biopsy and cytology during ERCP and under PPS direct vision had a sensitivity of about 60 % in the differential diagnosis between malignancy and benign diseases.

CONCLUSIONS

Mucin-producing tumors of the pancreas with papillary tumorous lesions of 3 mm or more in maximum height should be considered as adenocarcinomas. The combined use of IDUS and PPS with biopsy and cytology is now considered the best for the differential diagnosis of mucin-producing tumors of the pancreas.

PKN interacts with a paraneoplastic cerebellar degeneration-associated antigen, which is a potential transcription factor

PKN is a fatty acid-activated serine/threonine protein kinase, having a catalytic domain homologous to protein kinase C family. PKN has been recently reported to interact with a small GTP-binding protein Rho and cytoskeletal proteins such as neurofilament and alpha-actinin. To identify the new components of the PKN-signaling pathway, the yeast two-hybrid system was employed. Using the amino-terminal regulatory domain of PKN as a bait, cDNA encoding a neural antigen PCD17, which is recognized by characteristic antibodies of patients with paraneoplastic cerebellar degeneration, was isolated from a human brain cDNA library. The interaction between PKN and PCD17 was also determined by the in vitro binding analysis. PCD17 was coimmunoprecipitated with PKN from the lysate of COS7 cells transfected with both expression constructs for PKN and the amino-terminal region of PCD17. PCD17 was phosphorylated by PKN, and the extent of this phosphorylation was enhanced by addition of 40 microM arachidonic acid. The amino-terminal region of PCD17 could form a homodimer in vitro, and PCD17 fused to the Gal4 DNA binding domain showed the transcriptional transactivation of the chloramphenicol acetyltransferase reporter gene linked to 5 Gal4 binding sites and minimal promoter in rat C6 glioma cells. These results suggest the participation of PCD17 in gene expression and lead to a clue for elucidating the PKN signaling pathway from the cytosol to the nucleus.

Serum thrombopoietin level is mainly regulated by megakaryocyte mass rather than platelet mass in human subjects

A patient with idiopathic thrombocytopenic purpura (ITP) developed T-cell lymphoma while undergoing steroid therapy. We examined the relationship between the patient's serum thrombopoietin (Tpo) level, platelet count, megakaryocyte number and CFU-Meg number during the second 5 d course of chemotherapy for lymphoma in which megakaryopoiesis switched from ITP phase to amegakaryocytic phase. The patient's platelet count was temporarily elevated but CFU-Meg numbers were markedly suppressed, and megakaryocyte numbers were decreased in this period, whereas serum Tpo level was not suppressed despite an increased platelet count, indicating that serum Tpo level is mainly regulated by megakaryocyte mass.

Effect of chronic bradykinin B2 receptor blockade on blood pressure of conscious Dahl salt-resistant rats

1. In this study 3 protocols were utilized to determine the role of endogenous kinins in the resistance of the inbred Dahl (Rapp) salt-resistant (SR/Jr) rats to high salt diet-induced blood pressure elevation. 2. The bradykinin B2 receptor antagonist, Hoe 140 (D-Arg[Hyp3, Thi5, D-Tic7, Oic8]-bradykinin) at doses of either 10-20 or 20-40 nmol day(-1) (subcutaneously (s.c), via osmotic minipumps, for either 1 or 3 weeks during a high (8%) salt diet) effectively blocked or attenuated the hypotensive responses to 100-1000 ng of bradykinin. 3. In the first protocol, 5 week old SR/Jr rats treated with Hoe 140 (10-20 nmol day(-1), n = 9, s.c., via osmotic minipumps) for 3 weeks and concomitantly fed high (8%) NaCl diet had significantly higher conscious tail cuff blood pressures (BPc) at 1 and 3 weeks when compared with rats treated with vehicle (0.9% NaCl, n = 6). The differences in BPc between the 2 groups were 13 mmHg (P < 0.001) after 1 week and 8 mmHg (P < 0.05) after 3 weeks of treatment. 4. In the second protocol, 5 week old SR/Jr rats were treated with Hoe 140 (20-40 nmol day(-1), n = 8, s.c., via osmotic minipumps) or vehicle (n = 8) for 3 weeks. During the first week of treatment the rats were fed normal (0.8%) NaCl diet. The rats were then switched to 8% NaCl for 2 remaining weeks of the protocol. The mean BPc of Hoe 140-treated rats was not significantly different from that of the vehicle-treated rats when fed 0.8% NaCl diet. In contrast, rats treated with Hoe 140 and concomitantly fed high (8%) NaCl diet had significantly increased BPc (123+/-2 vs 111 +/- 1 mmHg, P < 0.001 for the Hoe 140- and vehicle-treated rats, respectively). 5. In the third protocol, treatment with Hoe 140 (20 40 nmol day(-1), s.c., via osmotic minipumps) during high salt diet did not increase BPc in rats that were pre-exposed to the high salt diet for 2 weeks. 6. At the end of 3 weeks of study, blood pressure was measured via an arterial catheter during pentobarbitone-induced anaesthesia. Rats treated with Hoe 140 for 1 or 3 weeks had significantly lower mean arterial blood pressures than the vehicle-treated rats. 7. Our findings suggest that in SR/Jr rats, kinin activation of bradykinin B2 receptors at least partially contributes to early regulatory mechanisms that resist an increase in blood pressure following exposure to a high salt diet. The mechanism underlying the decreased blood pressure during pentobarbitone anaesthesia of SR/Jr rats chronically treated with Hoe 140 has yet to be elucidated.

Distribution of glycoproteins with beta-N-acetylgalactosaminylated N-linked sugar chains among bovine tissues

Only a small number of glycoproteins has been reported to contain N-linked sugar chains with GalNAcbeta1-->4GlcNAc structure. Our previous studies showed that most glycoproteins from bovine milk fat globule membranes contain beta-N-acetylgalactosaminylated N-linked sugar chains [Sato et al., J. Biochem. 114 (1993) 890-900]. In order to study how widely this glycosylation occurs, lectin blot analysis of membrane glycoproteins from 12 bovine tissues was performed using Wistaria floribunda agglutinin (WFA), which interacts with oligosaccharides terminating with N-acetylgalactosamine. The WFA-positive bands were detected in samples from most tissues except for intestine although the number and reactivity of bands to lectin varied among the tissues. Upon pretreatment of blotted filters with Bacillus beta-N-acetylgalactosaminidase or N-glycanase, no lectin binding was observed. WFA-agarose column chromatography of oligosaccharides released by hydrazinolysis from membrane glycoproteins of bovine tissues except for intestine revealed that a few to 18% of the released oligosaccharides bind and are eluted from the column with 100 mM N-acetylgalactosamine. These results indicate that many glycoproteins from a variety of bovine tissues contain N-linked sugar chains with GalNAcbeta1-->4GlcNAc structure, suggesting a wider occurrence of this glycosylation in bovine tissues.

The surgical treatment of lung lacerations and major bronchial disruptions caused by blunt thoracic trauma

The records of 16 patients who suffered blunt thoracic trauma, causing lung lacerations in 13, bronchial disruptions in 2, and lung laceration with bronchial disruption in 1, were reviewed to investigate the correlations between clinical factors and prognosis. The causes of these injuries included 14 traffic accidents and 2 construction-related accidents, and the indications for surgery were massive bleeding in 12 patients, massive air leakage in 2, both in 1, and lung abscess in 1. Of the 16 patients, 11 (68.8%) underwent thoracotomy less than 4 h after admission, 3 (18.8%) underwent thoracotomy 4 to 24 h after admission, and 2 (12.5%) underwent thoracotomy 24 h or later after admission. The operative techniques included 1 pneumonectomy, 5 lobectomies, 2 bronchoplasties, and 8 minor repairs. The mortality rate was 43.7%, which included six early deaths occurring within 72 h of the trauma, and one late death. While major bronchial disruption is usually associated with a good prognosis, univariate and multivariate analyses demonstrated that intrapleural bleeding of 300 ml/h or more from time of trauma to chest tube drainage was significantly correlated with a poor prognosis. Moreover, an injury severity score (ISS) of 36 or more showed a trend toward a correlation with poor prognosis in patients with lung lacerations. Prompt thoracotomy will decrease mortality rate of patients suffering lung lacerations resulting in intrapleural bleeding of more than 300 ml/h.

The protein kinase N (PKN) gene PRKCL1/Prkcl1 maps to human chromosome 19p12-p13.1 and mouse chromosome 8 with close linkage to the myodystrophy (myd) mutation

Protein kinase N (PKN) is a fatty acid- and Rho-activated serine/threonine protein kinase involved in the regulation of cell motility by association with cytoskeletal components such as neurofilament and alpha-actinin. We determined the chromosomal location of the human PKN gene PRKCL1 by fluorescence in situ hybridization and by radiation hybrid mapping. The corresponding mouse gene Prkcl1 was mapped by segregation analysis. We found by FISH that PRKCL1 is localized to chromosome 19p12-p13.1 and, more precisely, by radiation hybrid mapping, about 11 cR from EST WI-6344 in subband 19p12. Prkcl1 maps to mouse chromosome 8 between D8Mit6 and junb. This region of mouse Chr 8 shows a scrambled syntenic conservation to human chromosomes 4q, 8p, and 19p. As the mouse mutation myodystrophy myd has been mapped to the same region, Prkcl1 is a candidate gene for myd.

Comparative effects of GTPgammaS and insulin on the activation of Rho, phosphatidylinositol 3-kinase, and protein kinase N in rat adipocytes. Relationship to glucose transport

Electroporation of rat adipocytes with guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) elicited sizable insulin-like increases in glucose transport and GLUT4 translocation. Like insulin, GTPgammaS activated membrane phosphatidylinositol (PI) 3-kinase in rat adipocytes, but, unlike insulin, this activation was blocked by Clostridium botulinum C3 transferase, suggesting a requirement for the small G-protein, RhoA. Also suggesting that Rho may operate upstream of PI 3-kinase during GTPgammaS action, the stable overexpression of Rho in 3T3/L1 adipocytes provoked increases in membrane PI 3-kinase activity. As with insulin treatment, GTPgammaS stimulation of glucose transport in rat adipocytes was blocked by C3 transferase, wortmannin, LY294002, and RO 31-8220; accordingly, the activation of glucose transport by GTPgammaS, as well as insulin, appeared to require Rho, PI 3-kinase, and another downstream kinase, e.g. protein kinase C-zeta (PKC-zeta) and/or protein kinase N (PKN). Whereas insulin activated both PKN and PKC-zeta, GTPgammaS activated PKN but not PKC-zeta. In transfection studies in 3T3/L1 cells, stable expression of wild-type Rho and PKN activated glucose transport, and dominant-negative forms of Rho and PKN inhibited insulin-stimulated glucose transport. In transfection studies in rat adipocytes, transient expression of wild-type and constitutive Rho and wild-type PKN provoked increases in the translocation of hemagglutinin (HA)-tagged GLUT4 to the plasma membrane; in contrast, transient expression of dominant-negative forms of Rho and PKN inhibited the effects of both insulin and GTPgammaS on HA-GLUT4 translocation. Our findings suggest that (a) GTPgammaS and insulin activate Rho, PI 3-kinase, and PKN, albeit by different mechanisms; (b) each of these signaling substances appears to be required for, and may contribute to, increases in glucose transport; and (c) PKC-zeta may contribute to increases in glucose transport during insulin, but not GTPgammaS, action.

Alpha helix content of G protein alpha subunit is decreased upon activation by receptor mimetics

To elucidate the mechanism whereby liganded receptor molecules enhance nucleotide exchange of GTP-binding regulatory proteins (G proteins), changes in the secondary structure of the recombinant Gi1 alpha subunit (Gi1alpha) upon binding with receptor mimetics, compound 48/80 and mastoparan, were analyzed by circular dichroism spectroscopy. Compound 48/80 enhanced the initial rate of GTPgammaS binding to soluble Gi1alpha 2.6-fold with an EC50 of 30 microg/ml. With the same EC50, the mimetic decreased the magnitude of ellipticity, which is ascribed to a reduction in alpha helix content of the Gi1alpha by 7%. Likewise, mastoparan also enhanced the rate of GTPgammaS binding by 3.0-fold and decreased the magnitude of ellipticity of Gi1alpha similar to compound 48/80. In corresponding experiments using a K349P-Gi1alpha, a Gi1alpha counterpart of the unc mutant in Gsalpha in which Pro was substituted for Lys349, enhancement of the GTPgammaS binding rate by both activators was quite small. In addition, compound 48/80 showed a negligible effect on the circular dichroism spectrum of the mutant. On the other hand, a proteolytic fragment of Gi1alpha lacking the N-terminal 29 residues was activated and showed decreased ellipticity upon interaction with the compound, as did the wild-type Gi1alpha. Taken together, our results strongly suggest that the activator-induced unwinding of the alpha helix of the G protein alpha subunit is mechanically coupled to the enhanced release of bound GDP from the alpha subunit.