Primary cultures of rat cortical microglia treated with nicotine increases in the expression of excitatory amino acid transporter 1 (GLAST) via the activation of the α7 nicotinic acetylcholine receptor.

Although the clearance of glutamate from the synapse under physiological conditions is performed by astrocytic glutamate transporters, their expression might be diminished under pathological conditions. Microglia glutamate transporters, however, might serve as a back-up system when astrocytic glutamate uptake is impaired, and could have a prominent neuroprotective function under pathological conditions. In the current study, the effect of nicotine, well known as a neuroprotective molecule, on the function of glutamate transporters in cultured rat cortical microglia was examined. Reverse transcription polymerase chain reaction and pharmacological approaches demonstrated that, glutamate/aspartate transporter (GLAST), not glutamate transporter 1 (GLT-1), is the major functional glutamate transporter in cultured cortical microglia. Furthermore, the α7 subunit was demonstrated to be the key subunit comprising nicotinic acetylcholine (nACh) receptors in these cells. Treatment of cortical microglia with nicotine led to a significant increase of GLAST mRNA expression and (14)C-glutamate uptake in a concentration- and time-dependent manner, which were markedly inhibited by pretreatment with methyllycaconitine, a selective α7 nACh receptor antagonist. The nicotine-induced expression of GLAST mRNA and protein is mediated through an inositol trisphosphate (IP3) and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) depend intracellular pathway, since pretreatment with either xestospongin C, an IP3 receptor antagonist, or KN-93, a CaMKII inhibitor, blocked GLAST expression. Together, these findings indicate that activation of nACh receptors, specifically those expressing the α7 subunit, on cortical microglia could be a key mechanism of the neuroprotective effect of nACh receptor ligands such as nicotine.

Pancreatic transection using ultrasonic dissector in pancreatoduodenectomy.

BACKGROUND: Pancreatoenterostomic leakage after pancreatoduodenectomy may be caused partly by pancreatic juice leakage from transected branch pancreatic ducts on the pancreatic cut surface that do not drain into the main pancreatic duct after pancreatectomy. METHODS: We devised a new technique of pancreatic transection using an ultrasonic dissector followed by duct-to-mucosa pancreatojejunostomy, in order to prevent pancreatoenterostomic leakage after pancreatoduodenectomy in patients with a soft pancreas and a small main pancreatic duct. During pancreatic transection, branch pancreatic ducts and blood vessels are adequately skeletonized and securely ligated. The pancreatic duct is anastomosed to the full thickness of the jejunum with four to six interrupted sutures. RESULTS: Ten patients with a nondilated pancreatic duct (2 to 3 mm) underwent pancreatoduodenectomy by the present method. During pancreatic transection, 24 to 35 ducts including the pancreatic ducts and blood vessels were skeletonized and ligated. Postoperatively, no patients developed pancreatojejunostomic leakage. The present method may prevent pancreatoenterostomic leakage after pancreatoduodenectomy.

Pancreatic carcinoma associated with anomalous pancreaticobiliary junction.

Anomalous pancreaticobiliary junction often leads to biliary tract carcinoma but only rarely to pancreatic carcinoma. We report three cases of pancreatic carcinoma associated with anomalous pancreaticobiliary junction. All three were female with a mean age of 68 years. Carcinomas were located in the pancreatic head (n = 2) or body (n = 1). None had choledochal cyst and one had experienced recurrent acute pancreatitis. All carcinomas were at an advanced stage with a poor prognosis. No unique imaging or histologic findings of the carcinomas could be identified. Attention should be paid to the possibility of pancreatic carcinoma in patients with anomalous pancreaticobiliary junction, particularly in aged patients. Early diagnosis and treatment of anomalous pancreaticobiliary junction may prevent development of pancreatic carcinoma.

Molecular cloning and genomic structure of human frizzled-3 at chromosome 8p21.

WNT receptors encoded by the Frizzled genes are implicated in carcinogenesis as well as in embryonic development. Human Frizzled-3 (FZD3) gene, encoding seven-transmembrane receptor with the N-terminal cysteine-rich domain, has been cloned and characterized. Expression of the FZD3 mRNAs was investigated by using three FZD3 specific probes: HF3S1, corresponding to the 5'-UTR and a part of the coding region; HF3S2, corresponding to a part of the coding region; HF3S3, corresponding to the 3'-UTR. HF3S1 and HF3S2 hybridized to the 14.0-, 9.0-, 4.0- and 1.8-kb FZD3 mRNA, while HF3S3 hybridized to the 14.0-, 9.0-, and 4.0-kb FZD3 mRNA. The 14. 0-kb FZD3 mRNA was the major transcript in fetal brain and adult cerebellum, while the 1.8-kb FZD3 mRNA was the major transcript in adult pancreas, and many cancer cell lines examined. The 1.8-kb FZD3 mRNA, alternatively polyadenylated by the internal AATAAA signal in the coding region, is predicted to encode the truncated FZD3 protein lacking the region through the second extracellular loop to the C-terminal tail, and might function as the transmembrane-type antagonist for WNTs. The FZD3 gene consists of 8 exons, and has been mapped to human chromosome 8p21.

Is percutaneous cholecystostomy the optimal treatment for acute cholecystitis in the very elderly?

In elderly patients emergent cholecystectomy for acute cholecystitis is a high risk procedure. We prospectively assessed the value of percutaneous cholecystostomy for acute cholecystitis in 38 consecutive elderly (> or = 80 years) patients. All 38 underwent percutaneous transhepatic cholecystostomy under ultrasonographic and fluoroscopic guidance for acute cholecystitis (25 calculous, 13 acalculous). Eight (21%) patients had acute severe medical problems, such as shock and respiratory distress. Thirty-one (82%) patients had chronic severe underlying diseases, including cardiovascular and neurologic diseases. Cholecystostomy was successful in all 38 patients. Prompt clinical improvement was obtained in 36 (95%) patients. Morbidity and mortality rates were 3% and 3%, respectively. After cholecystostomy, 10 patients with cholelithiasis underwent elective cholecystectomy without serious complications. Two patients underwent percutaneous cholecystolithotomy, which produced complete resolution of symptoms. Four of 12 patients with and none of 12 without cholelithiasis had recurrent cholecystitis after catheter removal during a mean follow-up of 1.8 years. A second cholecystostomy was successful in these four patients. Elderly patients are often poor surgical candidates because of severe cholecystitis or concomitant medical problems. Percutaneous cholecystostomy is a safe, effective treatment for acute cholecystitis even in elderly patients. For calculous cholecystitis, cholecystostomy can be followed by elective surgery, if possible, or by nonsurgical treatment or expectant conservative management in high-risk patients. Cholecystostomy may be a definitive treatment for acalculous cholecystitis.

Molecular cloning of human Frizzled-6.

The Frizzled genes encode receptors for WNTs, secreted glycoproteins implicated in development as well as in carcinogenesis. In this paper, we report molecular cloning of Hfz6, the human homologue of Mfz6. Nucleotide sequence analysis showed that the Hfz6 gene encodes the 706 amino-acid protein with seven transmembrane domains, a cystein-rich domain in the N-terminal extracellular region, two N-linked glycosylation sites, and two cystein residues in the second and third extracellular loops. Hfz6 mRNA 4.4-kb in size was detected in various normal adult and fetal tissues, and a larger amount of Hfz6 mRNA was detected in both fetal lung and fetal kidney. The Hfz6 gene has been mapped to human chromosome 8q22.3-q23.1. In conclusion, we have cloned Hfz6, which encodes a seven-transmembrane receptor with the cystein-rich domain in the N-terminal extracellular region, but without the Ser/Thr-X-Val motif in the C-terminus.

Human T-cell leukemia virus type 1 Tax activates transcription of the human fra-1 gene through multiple cis elements responsive to transmembrane signals.

We have shown that Tax1 of human T-cell leukemia virus type 1 stimulates the expression of several cellular immediate-early genes (M. Fujii, T. Niki, T. Mori, T. Matsuda, M. Matsui, N. Nomura, and M. Seiki, Oncogene 6:1023-1029, 1991). In this study, the 5'-flanking region of the human fra-1 gene, which is a Tax1-inducible fos-related gene, was isolated and Tax1 or serum-responsive cis elements were analyzed to obtain further insight into the mechanism of Tax1 action. The 62-bp sequence starting 46 nucleotides upstream from the translation initiation site showed 71% homology with the sequence surrounding the TATA box of the c-fos promoter. Regulatory motifs identified in the c-fos promoter, such as an Ets-binding site, E boxes, a CArG box, c-fos AP-1 sites, and two retinoblastoma control elements, were also found upstream of the c-fos homology region. A 502-bp fragment containing these motifs mediated transcriptional activation by Tax1 or by serum in a transient transfection assay. Three independent Tax1-responsive regions (TRRs) were identified, and mutations in each revealed that one of the retinoblastoma control elements in TRR1 and the c-fos AP-1 sites in TRR2 and TRR3 were essential for the activation. Although TRR2 contains a CArG box-like sequence, it was a weak binding site for p67SRF, if it bound at all, and was not required for activation. All three TRRs could also mediate the signals stimulated by serum. Thus, Tax1 appears to activate fra-1 gene expression by means of a part of the cellular machinery similar to that which mediates growth signals.

Isolation of human fos-related genes and their expression during monocyte-macrophage differentiation.

cDNA clones of human fos-related genes fra-1 and fra-2 were isolated by screening human c-DNA libraries with human fos DNA as a probe. We obtained human fra-1 cDNA clones that can code for a protein of 271 amino acid residues with a calculated molecular weight of 29,413 and showed 90% similarity with rat fra-1 protein. A new fos-related gene, fra-2, has one long open reading frame of 326 amino acids, and can code for a protein with a calculated molecular weight of 35,193. Two regions, a leucine zipper domain and C-terminal region, are conserved in the fos gene family. The fra-2 gene also harbors these two regions. Transcription of the fos, fra-1 and fra-2 genes was induced by phorbol ester (TPA) stimulation of U937 human monocytic cells. On TPA stimulation, the transcriptions of fos, fra-1 and fra-2 were detectable after 30, 60 and 120 min and maximum after 60, 90 and 240 min, respectively. These findings suggest that expression of the fos gene family is regulated by an orderly mechanism.