Determinants of differential liver-colonizing potential of variants of the MCA-38 murine colon cancer cell line

We investigated factors that might contribute to the differing liver tumor colonizing potentials of MCA-38 colonic cancer cell line variants injected into the ileocolic veins of C57Bl/6J mice. Non-colonizing (MCA-38 CD) cells were sensitive to lysis by hepatic natural killer (NK) cells in vitro (51Cr-release assay) and cells with high liver-colonizing potential (MCA-38 LD) were resistant. Following abrogation of NK activity by treatment with anti-asialoGM1, liver-colonizing ability to LD cells but not CD cells was enhanced. MCA-38 CD cells were, however, capable of initial liver colonization after ileocolic vein injection. Differing patterns of membrane sialylation may have contributed to the contrasting hepatic tumorigenicities of LD and CD cells; beta-galactoside alpha 2,6-sialyltransferase mRNA levels and activity were approximately four-fold higher in LD than CD cells and qualitative and quantitative differences existed between their ganglioside profiles. In the MCA-38 model outlined, tumor cell susceptibility or resistance to NK lysis was a relatively unimportant determinant of liver-colonizing potential.

High-performance liquid chromatographic analysis of synthetic peptides using derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate

A series of synthetic prothrombin leader sequences (ANKGFLEEX), each having a different C-terminal amino acid, was derivatized with the novel fluorescent-derivatizing agent 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and analyzed by HPLC. Essentially quantitative yields of derivatized peptides could be routinely obtained with a fast, simple derivatizing procedure. The response was linear over a concentration range of 0.176 to 88.0 nM. Peptides labeled with this highly sensitive derivatizing agent exhibited a mass detection limit in the femtomole range and a concentration detection limit in the picomolar range. Amino acid content of hydrolyzed peptides was carried out using the same reagent in order to evaluate the amino acid composition and to detect any deletion sequences.

The use of clozapine in a mentally retarded and aggressive population

BACKGROUND

Clozapine has proven efficacy in the management of treatment-resistant schizophrenia. Additional use in patients with mood and schizoaffective disorders, Parkinson's disease with psychosis, and brain injury has been reported. Preclinical data have suggested its possible utility in treating self-injurious behavior in patients with mental retardation.

METHOD

The use of clozapine in six patients with moderate-to-profound mental retardation is described. The issue of diagnosing psychosis in such individuals and its impact on choice of pharmacotherapy is considered.

RESULTS

Clozapine in these individuals may have led to a significant reduction in aggression, self-injurious behavior, and psychotic symptoms. Side effects were minimal and similar to those seen in the schizophrenic population.

CONCLUSION

These case reports illustrate that clozapine may be useful and well tolerated in the treatment of aggression in patients with moderate-to-profound mental retardation.

Comparison of amino acid analyses by phenylisothiocyanate and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate precolumn derivatization

An extensive retrospective comparison was conducted of the long-term repeatability and consistency of amino acid analyses using phenylisothiocyanate and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) precolumn derivatization. Amino acid standards were analyzed more than 130 times on more than 60 independent occasions by each of these two precolumn derivatization methodologies, during routine amino acid analysis procedures. Similar coefficients of variation were seen only when very freshly prepared derivatives were analyzed. When realistic aging for < 20 h was taken into account, the extreme stability of the AQC derivatives stood out. Chromatography of AQC derivatives using HPLC solvents prepared on a large scale provided the lowest coefficients of variation. The superiority of AQC over PTC methodology was clearly apparent.

Stent-guided sphincterotomy

Performing sphincterotomy when either Billroth II gastrectomy or complicated periampullary diverticula are present may increase the risk of complications. In addition a sphincterotomy on the main pancreatic sphincter or the papilla of Santorini presents complicated problems. Stent-guided sphincterotomy has been utilized in 229 patients presenting to our institution from 1983 through 1992. They were performed in 67 patients who had undergone Billroth II gastrectomy, 23 with periampullary diverticula, 57 with pancreas divisum, and 82 with a history of recurrent pancreatitis. To prevent ductal injury or perforation, a stent is first inserted into the biliary or pancreatic duct to guide the sphincterotomy incision. The sphincterotomy is performed using electrocautery current delivered through a "needle knife" sphincterotome. Pancreatitis occurred in 19 patients (8.3%). It was mild in 17 and moderate in two patients. One patient experienced severe hemorrhage requiring surgery. No mortality or perforations occurred. The stent-guided needle knife sphincterotomy approach is an effective technique. It has a low complication rate even in these difficult anatomic conditions. It assures that the incision precisely follows the duct when performing pancreatic sphincterotomy.

Endoscopic sphincterotomy for biliary pancreatitis: an alternative to cholecystectomy in high-risk patients

Recurrent biliary pancreatitis frequently is associated with an intact gallbladder containing stones. This condition has been effectively treated by removing the gallbladder, but there is evidence that endoscopic sphincterotomy might obviate the need for cholecystectomy in some patients. We performed prophylactic sphincterotomy in 49 patients who presented with biliary pancreatitis more than once and who were considered at risk for surgery. The majority (39 patients) were treated electively after resolution of pancreatitis, while the remainder (10 patients) were treated urgently during their index admission because of continuing symptoms. No patient experienced recurrent pancreatitis over a mean follow-up period of 48 months. No mortality occurred in this endoscopic series, and no significant morbidity was experienced. Based on our results, we advocate performing sphincterotomy in the aged patient or younger patients considered at high risk for surgery who present with a history of recurrent pancreatitis and cholelithiasis.

Endoscopic management of cholangitis: critical review of an alternative technique and report of a large series

OBJECTIVE

To assess the outcome of endoscopic techniques as the solitary treatment modality for the complete management of ascending, bacterial cholangitis, compared with results of radiological and surgical methods as historical controls.

METHODS

Endoscopic techniques were used to decompress bile ducts obstructed by stones (898 patients) or stenosis (49 patients). Endoscopic sphincterotomy (ES) was performed in 839 patients, and either 7-Fr straight stents (79), or nasobiliary tubes (29), were utilized as initial therapy in 108 patients. Of these latter patients, 68 subsequently underwent ES and stone removal, 17 had ES, lithotripsy, and stone removal, 18 were left with stents in place, and 5 were lost to follow-up. Follow-up was conducted by direct patient contact, by telephone, or through the referring physicians.

RESULTS

All patients were managed by endoscopic techniques. There were four deaths (0.42%) in the first 30 days (none before 2 wk); no deaths were related to the procedures but were attributed to intercurrent medical problems. Two patients underwent surgery: one pancreatitis, one perforation. Complications were infrequent, occurring in 6% of patients. Bleeding occurred in 3%, pancreatitis in 2.8%, and perforation 0.2%.

CONCLUSIONS

Endoscopic management of cholangitis is as effective as surgical or radiological methods for managing bacterial cholangitis, a potentially fatal syndrome, but ERCP and ES have been shown to be safer. Endoscopy is the preferred index technique both for establishing a definitive diagnosis and providing therapy.

Endoscopic treatment of laparoscopic bile duct injuries

Laparoscopic technique has become the norm for cholecystectomy, one of the most commonly performed operations. Unfortunately, the advent of laparoscopic cholecystectomy has been accompanied by a significant increase in bile duct injuries and a new set of postsurgical problems when compared with traditional, open cholecystectomy. Endoscopic retrograde cholangiopancreatography (ERCP) has emerged as a central method for diagnosis and treatment of bile duct injuries and other problems arising after laparoscopic cholecystectomy. The most common biliary problems include bile leaks from the cystic duct remnant or one of the main ducts; ductal injury, such as disruption or strictures; retained common bile duct stones; or postoperative biliary-pancreatic pain. Building on the success of endoscopic treatment of biliary complications of traditional surgery, ERCP, in cooperation with radiological and surgical intervention, can facilitate definitive diagnosis and treatment of bile leaks and simple strictures. Complex strictures and complete disruptions are not amenable to endoscopic therapy and should be treated surgically. As experience in laparoscopic cholecystectomy increases, the incidence of bile duct injuries should decline; ERCP, however, will remain a valuable adjunctive modality.

Applications of amino acid derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Analysis of feed grains, intravenous solutions and glycoproteins

Primary and secondary amines are rapidly labelled by 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate to form highly fluorescent asymmetric urea derivatives which are readily amenable to analysis by liquid chromatography. Derivatization consists of a simple, one-step procedure, and the resulting labelled amines can be analyzed without further cleanup. The adducts are extremely stable with no discernible loss in response after storage for one week at room temperature, making the reagent an ideal candidate for pre-column amino acid analysis. Chromatographic methods for protein hydrolysates have been developed for the analysis of samples containing many unusual amino acids including a number of cysteine derivatives, collagen hydrolysates containing hydroxyproline and hydroxylysine, performic acid oxidized samples and glycoprotein hydrolysates containing glucosamine and galactosamine. Samples with potentially interfering matrix components such as hydrolyzed feed grains and intravenous solutions are readily analyzed and are quantified with average per cent relative standard deviations in the 1-2% range. Comparative data on these samples are in good agreement with either ion-exchange amino acid analysis or label information.

Analysis of derivatized peptides by capillary electrophoresis

Thirteen synthetic prothrombin leader peptides differing only in C terminus were analyzed by capillary electrophoresis. These peptides were derivatized using the novel, fluorescent derivatizing agent, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Derivatized peptides were detected using fluorescence and ultraviolet absorption signals, and underivatized peptides were detected using ultraviolet absorbance at 185 nm. Data are presented which compare the analysis of the derivatized and underivatized peptides.

Endoscopic management of primary sclerosing cholangitis: review, and report of an open series

Of the multiple treatment options available to physicians managing patients with primary sclerosing cholangitis (PSC), no single form of therapy has proven to be efficacious or to improve the clinical outcome of affected patients. Surgical and radiological methods require multiple procedures which are associated with increased morbidity, the most serious being sepsis. Endoscopic therapy is safer and easier to perform, and has been shown to provide symptomatic as well as objective improvement in affected patients. It, too, is associated with some complications, although less serious than other alternative treatments, but it is not effective in protracted disease. The potential of overlooking or missing cholangiocarcinoma is more apparent when nonsurgical techniques are employed. In this review we will discuss the various endoscopic treatment modalities utilized in PSC disease, and include the results that have been obtained with these techniques since they were incorporated into our armamentarium in 1983.

The potent free radical scavenger alpha-lipoic acid improves memory in aged mice: putative relationship to NMDA receptor deficits

alpha-Lipoic acid (alpha-LA) improved longer-term memory of aged female NMRI mice in the habituation in the open field test at a dose of 100 mg/kg body weight for 15 days. In a separate experiment, no such effect could be found for young mice. alpha-LA alleviated age-related NMDA receptor deficits (Bmax) without changing muscarinic, benzodiazepine, and alpha 2-adrenergic receptor deficits in aged mice. The carbachol-stimulated accumulation of inositol monophosphates was not changed by the treatment with alpha-LA. These results give tentative support to the hypothesis that alpha-LA improves memory in aged mice, probably by a partial compensation of NMDA receptor deficits. Possible modes of action of alpha-LA based on its free radical scavenger properties are discussed in relation to the membrane hypothesis of aging.