A novel normalized retention factor in micellar electrokinetic chromatography.

Characteristic properties of the expression k'' = (t(m)-t(o))/(t(mc)-t(o)) and its applicability in micellar electrokinetic capillary chromatography (MEKC) were compared to the previous expression, k' = (t(m)-t(o))/t(o)(1-t(m)/t(mc)), introduced by Terabe. It was proved with theoretical calculations (curve shape analysis) that the properties of function k'' are in full accordance with the properties of the MEKC system and k'' could be applied advantageously to characterize hydrophobicity of the analytes. This conclusion is now supported by experimental data obtained with homolog series of alkylbenzenes and alkylphenones as well as with hydrophobic protected peptides. Migration times, k', k'' values, and software-calculated hydrophobicity data are summarized and analyzed in the present study. Since k'' is a normalized parameter, good relationships between the migration time, the software-calculated hydrophobicity, and the k'' values were obtained. Differences in hydrophobicity of the analytes could be estimated in a more realistic way with the aid of function k'' than by using function k'. Hydrophobicity data estimated on the basis of the k'' values proved to be in good accordance with the expectations based on the migration times and on the chemical structures of the compounds investigated.

Analysis of polyanionic macromolecular carrier poly-(N-vinylpyrrolidone-co-maleic acid) and its bioconjugats by capillary electrophoresis.

Anionic carrier poly(N-vinylpyrrolidone-co-maleic acid) and its conjugates, prepared with coupling of 2-cyano-3-hydroxy-5-amino-2-pentenoyc(4-trifluoromethyl anilide) or (6', 7'-dimethyl-l'-quinoxalinyl)-4-(2' amino) acetanilide to the carrier, were analyzed by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) in the following buffers: 0.25 N triethylammonium phosphate (TEAP); sodium dodecyl sulfate (SDS; 25-150 mM) in TEAP (pH 2.25-6.30); 0.1 N Na-borate buffer (pH range 7-11) and SDS (25-150 mM) in Na-borate buffer (pH range 7-11). The presence of strong carboxyl groups (dissociated even at pH 2.25) on the polymer chain was proved by the CZE method. It was also proved by potentiometric titration that carboxyls with a wide range of acidity were on the polymer chain. CZE was able to differentiate among the analytes possessing carboxyl groups of different acidic strengths at pH 2.25. These components were not distinguished by CZE at high pH values (11.0). Interaction between the analyte and SDS affected the separation at this pH, and hence good resolution was obtained by MEKC. Informative separations were achieved both for the carrier and the conjugates in TEAP buffer at pH 2.25 by the CZE method. Optimal separation was achieved in borate buffer containing 75 mM SDS at pH 11.0 for the carrier and at pH 7.7 for the conjugates in MEKC.

Gluconeogenesis from ascorbic acid: ascorbate recycling in isolated murine hepatocytes.

Ascorbic acid synthesis and breakdown were investigated in isolated hepatocytes prepared from fasted mice. Stimulation of gluconeogenesis by alanine or xylitol led to ascorbate synthesis. On the other hand, ascorbate or dehydroascorbate addition resulted in concentration-dependent glucose production and elevation of the pentose phosphate pathway intermediate xylulose 5-phosphate. Stimulation of ascorbate oxidation and/or the inhibition of dehydroascorbate reduction increased glucose formation. Inhibition of the pentose phosphate pathway decreased glucose production from dehydroascorbate with increased accumulation of xylulose 5-phosphate. These results suggest that ascorbate can be recycled by a novel way involving intermediates of the pentose phosphate pathway, gluconeogenesis and hexuronic acid pathway.

T-cell receptor-gamma delta association with lymphocyte populations in sheep intestinal mucosa.

T cells expressing T-cell receptor (TcR)-gamma delta and CD8 represent a significant population in mouse and chicken intra-epithelial lymphocytes (IEL) but represent a minor population in human IEL. We examined the TcR-gamma delta usage and co-expression of CD5, CD4, CD8 and major histocompatibility complex (MHC) class II on isolated sheep IEL and lamina propria lymphocytes (LPL), and compared them with the TcR-gamma delta + cells in peripheral blood, intestinal lymph and jejunal Peyer's patches (PP). There were a number of notable differences. TcR-gamma delta + cells comprised 18% of IEL and 10% of LPL. Among the population of TcR-gamma delta + IEL, 24% were CD8+ and 54% were CD5+, which contrasts with the TcR-gamma delta + cells in blood and intestinal lymph that were universally CD5+ CD4- CD8-. A notable feature of the IEL was the presence of distinct CD8+ and TcR-gamma delta + populations that lacked CD5. Also a high percentage of IEL and LPL were CD2+ and MHC class II+. Analysis of the expression of MHC class II on T-cell subsets, as an indicator of activation, showed that 60-95% of the various IEL and LPL subsets were MHC class II+ compared with only 5-40% in jejunal PP, lymph nodes, spleen and blood. Therefore, it is possible that the circulating TcR-gamma delta + and CD8+ cells that localize in the gut epithelium might become activated and stop the expression of CD5 under the influence of the local microenvironment. These cells appear not to emigrate while still expressing the TcR-gamma delta + (CD8+) CD5- MHC class II+ phenotype. Our data, together with those from other studies, show that there is much heterogeneity in the use of TcR-gamma delta and accessory T-cell molecules by IEL.

Copper deficiency and microcytic anemia resulting from prolonged ingestion of over-the-counter zinc.

Isolated copper deficiency occurred in a 57-yr-old man who had ingested massive quantities of zinc for more than 18 months. The patient presented with microcytic anemia and had normal gastrointestinal function with no evidence of occult blood loss. Dietary zinc in large doses leads to copper deficiency by antagonizing copper absorption. With discontinuance of zinc, the anemia and hypocupremia promptly corrected. The relationship between zinc, copper deficiency, and iron metabolism is reviewed.

Large colorectal polyps: colonoscopy, pathology, and management.

Between 1984 and 1987, we reviewed all large (greater than or equal to 3.0 cm) colorectal polyps to determine the efficacy of colonoscopic polypectomy from both an oncologic and technical viewpoint. Forty-eight polyps greater than or equal to 3.0 cm were identified in 46 patients. Twenty polyps were entirely benign, 20 polyps contained noninvasive carcinoma, and invasive carcinoma was present in eight polyps. Four of the invasive cancers were associated with residual adenoma; the remaining four were polypoid carcinomas. Among the eight cases of invasive carcinoma, four had tumors that did not extend through the submucosa. Invasive cancer was more prevalent in left-side sessile lesions but was absent in all 10 right-sided polyps. Thirty-two polyps were removed by colonoscopic polypectomy. Four patients required colectomy after polypectomy for the following reasons: incomplete excision (N = 1), presence of invasive carcinoma at the resection margin (N = 1), and inability to define the level of carcinoma on pathologic examination (N = 2). Two polyps with cancer confined to the submucosa were successfully excised colonoscopically. Complications of polypectomy included three cases of minor hemorrhage. Sixteen polyps (the majority located in the right colon) were removed by primary surgical colectomy. We conclude that colonoscopic polypectomy is oncologically and technically successful for most large colorectal polyps. A minority of large polyps require colectomy because of incomplete removal or the presence of invasive cancer that is not curable with colonoscopic excision.

Transformation of hepatic cell adenoma to hepatocellular carcinoma due to oral contraceptive use.

PIP: Unlike the proven causal association between oral contraceptive (OC) use and hepatic cell adenoma, the link between OCs and hepatocellular carcinoma remains speculative. The case history of a 53-year-old US woman suggests, however, that hepatic cell adenomas may transform into hepatocellular carcinoma. The patient, who had used Ovral continuously since 1966, presented in 1985 with vague abdominal pain and a palpable right upper quadrant mass. Computed tomography revealed a 12 x 8 cm mass in the right hepatic lobe and 2 small lesions in the left lobe. Serum alpha-fetoprotein and ferritin levels were normal and tests for hepatitis B were negative. A needle biopsy of the right lobe mass indicated benign hepatic adenoma. OC use was discontinued and the patient was examined at bimonthly intervals. Although she continued to report vague pain, there were no significant changes in radiologic findings or levels of alpha-fetoprotein over the next 18 months. At the 18-month follow-up visit, the alpha-fetoprotein level showed an increase to 227 mcg/L and had risen to 2300 mcg/L by the 30-month follow-up visit. At this time, computed tomography showed slight enlargement of the right lobe mass and inhomogeneity, while biopsy revealed sclerosing hepatocellular carcinoma. This is the 3rd case reported in the literature in which there is evidence of a transformation of hepatic cell adenomas into hepatocellular carcinoma in longterm OC users. Thus, the premalignant potential of hepatic cell carcinomas in OC users should be considered by physicians who follow such cases.^ieng

Multiple gastric adenomas.

Gastric adenomas are uncommon, and multiple gastric adenomas are rare. We report an instance of three gastric adenomas found in an elderly man. Of the two polyps that contained histologic changes of malignancy, one measured 8 cm in length. The radiographic and pathologic findings are presented with a pertinent review of the literature.

Pyogenic liver abscess. Diagnostic and therapeutic strategies.

A retrospective review of 26 adult patients admitted to University of California, Davis, Medical Center (UCDMC) with pyogenic liver abscess (1980-1986) was performed to ascertain the impact of rapid diagnosis and percutaneous drainage. Ultrasonographic examinations and computed tomography (CT) scans were highly sensitive and noninvasive imaging modalities. Sixteen patients had solitary abscesses and seven had multiple microscopic abscesses. The median time interval from admission to diagnosis and therapy was 2 and 3 days, respectively. Origin of the abscess was determined in 22 patients, the biliary tree being the most common source. Medical therapy was successful in three patients with microabscesses but failed in two. Nine patients had percutaneous drainage; two required repetitive percutaneous catheter placement, and two proceeded to surgical drainage. Twelve patients had surgical drainage; one required repetitive surgical drainage. Postdrainage complications were minimal in all groups. Overall mortality role was 11.5% (two patients). Deaths were related to delay in diagnosis, gram-negative sepsis at presentation, and biliary origin of the abscess.

Liposome-cell interactions. A study of the interactions of liposomes containing entrapped anti-cancer drugs with the EMT6, S49 and AE1 (transport-deficient) cell lines.

A study has been made to determine if the cytotoxicity observed when cells in culture were exposed to liposome-entrapped cytotoxic drugs was liposome mediated or resulted from leakage of drug from the liposomes with subsequent uptake of free drugs by the cells. In preliminary experiments with the EMT6 cell line in monolayer culture, the cytotoxicity observed when the cells were exposed to a range of concentrations of liposome-entrapped methotrexate, actinomycin D and cytosine arabinoside for a variety of liposome compositions was somewhat less than that observed when the cells were exposed to similar concentrations of free drug. We suspected that the cytotoxicity was mediated via uptake of free drug leaked from liposomes. This was confirmed in experiments involving the EMT6 and S49 cell lines in monolayer or suspension culture, respectively, in the absence and presence of the nucleoside transport inhibitor, 6-(4-nitrobenzyl)thio)-9-beta-D-ribofuranosylpurine. Additional experiments were performed in a transport-deficient mutant of the S49 cell line, the AE1 cell line. No evidence for liposome-mediated cell death could be found in these cell lines when tubercidin 5'-monophosphate was entrapped in either large or small unilamellar liposomes composed of egg phosphatidylcholine/cholesterol (2 : 1), bovine brain phosphatidylserine/egg phosphatidylcholine/cholesterol (8 : 2 : 5) or egg phosphatidylcholine/stearylamine/cholesterol (10 : 1 : 5). Considerable toxicity due to empty liposomes of a variety of compositions was observed in the S49 cell line at high lipid concentrations.