A new matrix for affinity chromatography and its application in the separation of a human monoclonal antibody

A method for the preparation of a p-aminobenzene sulphonyl ethyl containing crosslinked Sepharose 4B (ABSE-Sepharose 4B-CL) is described, trypsin, bovine serum albumin (BSA) and concanavalin A (Con A) were immobilized onto this matrix by diazotization. Conditions for the coupling reaction were investigated. The activity of immobilized trypsin reached 1.4 x 10(4) U/g, and 25 mg BSA can be coupled onto 1 g ABSE-Sepharose 4B-CL under the optimal conditions. An affinity medium with immobilized Con A as ligand was prepared by this method, and was used in the separation of a human monoclonal antibody.

Role of topical phospholipids in the prophylaxis of silicone elastomer-associated infection in the abdominal cavity

The present study evaluated the influence of phospholipids (phosphatidyl choline and phosphatidyl inositol) on the prevention of abdominal biomaterial-associated infection. Phospholipid-impregnated silicone elastomer (SE) fragments were either intraperitoneally implanted in rats or immersed in serum for 0, 4, and 14 days, and 3 x 10(9) cfu of 3H-labeled, live Escherichia coli were added in the peritoneal cavity or in vitro incubation medium. Three hours after incubation, the adherence of bacteria significantly decreased to phospholipid-impregnated SE fragments, which had been immersed/implanted for 0 and 4 days. However, the number of adhering bacteria did not differ between the impregnated and unimpregnated SE fragments after 14 days of immersion/implantation. A significantly lower number of adhering bacteria was noted on all unimpregnated SE fragments when phospholipid was supplemented in the peritoneal cavity or in vivo medium, compared with fragments with no supplement. The rate of bacterial DNA synthesis decreased significantly after incubation with phospholipid 2 h or more. Phospholipids did not further influence peritoneal morphology. Thus topical administration of phospholipids by impregnation to the surface of SE fragments or supplement in the incubation medium prevented bacterial adherence onto the SE fragments. This implies that the use of phospholipids might be a mode of preventing biomaterial-associated infections.

Prevention of esophageal cancer: the nutrition intervention trials in Linxian, China. Linxian Nutrition Intervention Trials Study Group

In Linxian China, the esophageal/gastric cardia cancer mortality rates are among the highest in the world. There is suspicion that the population's chronic deficiencies of multiple micronutrients are etiologically involved. We conducted two randomized, placebo-controlled nutrition intervention trials to test the effects of vitamin and mineral supplements in lowering the rates of esophageal/gastric cancer. In the first trial, the dysplasia trial, 3318 adults with a cytological diagnosis of esophageal dysplasia received daily supplementation with 26 vitamins and minerals in doses typically 2-3 times the United States Recommended Daily Allowances, or placebos, for 6 years. The second trial, the general population trial, involved 29,584 adults and used a one-half replicate of a 2(4) factorial experimental design which tested the effects of four combinations of nutrients: A, retinol and zinc; B, riboflavin and niacin; C, vitamin C and molybdenum; and D, beta-carotene, vitamin E, and selenium. Doses for these daily supplements ranged from 1 to 2 times the United States Recommended Daily Allowances, and the different vitamin/mineral combinations or placebos were taken for a period of 5.25 years. As part of the general population trial, and end-of-intervention endoscopy survey was carried out in a small (1.3%) sample of subjects to see if supplementation affected the prevalence of dysplasia and early cancer. Herein we review the methods of these trials and the results of the endoscopic survey. Fifteen esophageal and 16 gastric cancers were identified in endoscopic biopsies from the 391 subjects evaluated from two villages, and nearly all were asymptomatic. No significant reductions in the prevalence of esophageal or gastric dysplasia or cancer were seen with any of the four supplement groups. However, the prevalence of gastric cancer among participants receiving retinol and zinc was 62% lower than those not receiving those supplements (P = 0.09), while participants receiving beta-carotene, vitamin E, and selenium had a 42% reduction in esophageal cancer prevalence (0.34). We have reported separately that cancer mortality over the entire 5.25-year period was significantly reduced among those receiving beta-carotene, vitamin E, and selenium. The findings from the overall trial and the endoscopic sample offer a hopeful sign and should encourage additional studies with these agents in larger numbers of subjects.

Orally administered phospholipids inhibit abdominal rubber-drain-induced bacterial translocation in the rat

In order to determine the influence of phospholipid on abdominal biomaterial-induced bacterial translocation (BT), phsophatidylcholine (PC) or phosphatidylinositol (PI) was administered orally or intraperitoneally in rats with intraperitoneal implantation of 7-cm2 rubber drain pieces. Two days after surgery, the incidence of translocation to mesenteric lymph nodes and liver significantly decreased, the adherence of 3H-labeled Escherichia coli to the ileal mucosa was significantly inhibited and the phagocytic and bactericidal capacity of peritoneal macrophages increased in animals with PC or PI administered orally, but not intraperitoneally, as compared with rats without phospholipid administration. Scanning electron microscopy revealed a coating layer on the surface of the intestinal mucosa in phospholipid-gavaged rats. Thus, the results in the present study imply that oral, but not intraperitoneal, PC of PI administration reduces enteric BT induced by intraperitoneal drain implantation.

Repair of pectus deformities with sternal support

During the past 25 years, 252 children underwent repair of pectus deformities. There were 195 male and 57 female patients, of whom 227 had pectus excavatum and 25 had pectus carinatum. Of the 252 patients, 113 underwent repair at between 2 and 5 years of age. Exercise limitation was reported by 51%, and 32% had frequent respiratory infections or asthma. Repair was performed through a transverse incision with subperiosteal resection of the lower four or five costal cartilages, from sternum to costochondral junction bilaterally. A transverse wedge osteotomy was made through the anterior table of the sternum, with fracture but no displacement of the posterior table. For children younger than 5 years (n = 108), the periosteal sheath of the fifth rib from each side was sewn together behind the sternal tip. For older patients (n = 136), a thin steel strut was used for sternal support for 6 months. There were no deaths within the first year. Complications included seroma (16), atelectasis (12), pneumothorax (three), and recurrent chest depression (three). More than 98% of patients had improvements in exercise tolerance, endurance, respiratory symptoms, and cosmetic appearance; these improvements were considered excellent results. Operation at an early age with routine use of substernal support with minimal preoperative and postoperative testing has provided excellent results at a low cost.

Phospholipid impregnation of abdominal rubber drains: resistance to bacterial adherence but no effect on drain-induced bacterial translocation

In order to evaluate the effect of surface modification of biomaterials on bacterial adherence and bacterial translocation after intraperitoneal biomaterial implantation, phosphatidylcholine- or phosphatidylinositol-impregnated rubber drain pieces, which had been intraperitoneally implanted in the rat for 2 and 7 days, or unimplanted, were incubated in vitro with 3H-labelled Escherichia coli and Enterobacter cloacae. As compared with unimpregnated pieces, the adherence of bacteria significantly decreased to phosphatidylcholine- and phosphatidylinositol-impregnated rubber drain pieces that were either unimplanted or implanted for 2 days, but not for 7 days. The supplementation of albumin in the medium reduced the adherence of bacteria to the unimplanted, unimpregnated drain pieces, but did not further decrease adherence of bacteria to the unimplanted, phospholipid-impregnated brain pieces. Bacterial growth was inhibited after incubation in nutrient broth supplemented with phospholipids. The incidence of enteric bacterial translocation induced by intraperitoneal drain implantation did not differ between phospholipid-impregnated and unimpregnated drain pieces. Scanning electron microscopy revealed a large amount of biofilm and fibrous deposition on the surface of the implanted, phospholipid-impregnated rubber drain pieces. Thus, phospholipid impregnation of rubber drains reduces bacterial adherence and inhibits bacterial growth, without influencing the incidence of bacterial translocation.

cis-elements involved in alternative splicing in the rat beta-tropomyosin gene: the 3'-splice site of the skeletal muscle exon 7 is the major site of blockage in nonmuscle cells

We have been using the rat beta-tropomyosin (beta-TM) gene as a model system to study the mechanism of alternative splicing. The beta-TM gene spans 10 kb with 11 exons and encodes two distinct isoforms, namely skeletal muscle beta-TM and fibroblast TM-1. Exons 1-5, 8, and 9 are common to all mRNAs expressed from this gene. Exons 6 and 11 are used in fibroblasts, as well as in smooth muscle cells, whereas exons 7 and 10 are used exclusively in skeletal muscle cells. Our previous studies localized the critical elements for regulated alternative splicing to sequences within exon 7 and the adjacent upstream intron. We also demonstrated that these sequences function, in part, to regulate splice-site selection in vivo by interacting with cellular factors that block the use of the skeletal muscle exon in nonmuscle cells (1). Here we have further characterized the critical cis-acting elements involved in alternative splice site selection. Our data demonstrate that exon 7 and its flanking intron sequences are sufficient to regulate the suppression of exon 7 in nonmuscle cells when flanked by heterologous exons derived from adenovirus. We have also shown by both in vivo and in vitro assays that the blockage of exon 7 in nonmuscle cells is primarily at its 3'-splice site. A model is presented for regulated alternative splicing in both skeletal muscle and nonmuscle cells.

Nutrition intervention trials in Linxian, China: multiple vitamin/mineral supplementation, cancer incidence, and disease-specific mortality among adults with esophageal dysplasia

BACKGROUND

A number of vitamins and minerals have been shown to influence carcinogenesis in experimental animals. In humans, epidemiologic evidence suggests that intake of fruits and vegetables may reduce risk of esophageal and other cancers. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian, China, have persistently low intake of multiple nutrients and exhibit one of the world's highest rates of esophageal/gastric cardia cancer, with an exceptionally high risk of esophageal dysplasia.

PURPOSE

To determine whether supplementation with multiple vitamins and minerals may reduce esophageal/gastric cardia cancer among persons with esophageal dysplasia, we conducted a 6-year prospective intervention trial in Linxian.

METHODS

Mortality and cancer incidence were ascertained from May 1985 through May 1991 for 3318 persons with cytologic evidence of esophageal dysplasia who were randomly assigned to receive, throughout that period, daily supplementation with 14 vitamins and 12 minerals or placebo. Doses were typically two to three times U.S. Recommended Daily Allowances. Compliance was assessed by counting unused pills monthly for all trial participants and by assaying nutrient levels in blood collected from samples of individuals randomly selected without replacement every 3 months throughout the trial. Cancers were identified through routine surveillance and by special cytology and endoscopy screenings after 2 1/2 years and 6 years.

RESULTS

A total of 324 deaths occurred during the 6-year intervention period; 167 occurred in the control (placebo) group and 157 occurred in the supplement group. Cancer was the leading cause of death (54% of all deaths); 18% were due to cerebrovascular diseases and 29% to other causes. Cumulative esophageal/gastric cardia death rates were 8% lower (relative risk [RR] = 0.92; 95% confidence interval [CI] = 0.67-1.28) among individuals receiving supplements rather than placebo, a nonsignificant (P > .10) difference. Risk of total mortality was 7% lower (RR = 0.93; 95% CI = 0.75-1.16; P > .10), total cancer 4% lower (RR = 0.96; 95% CI = 0.71-1.29; P > .10), cerebrovascular disease 38% lower (RR = 0.62; 95% CI = 0.37-1.06; P = .08), and other diseases 12% higher (RR = 1.12; 95% CI = 0.74-1.69; P > .10) among the treated group. Cumulative cancer incidence rates were nearly the same in the two groups.

CONCLUSIONS

No substantial short-term beneficial effect on incidence or mortality for this type of cancer occurred following daily supplementation with multiple vitamins and minerals among adults with precancerous lesions of the esophagus.

IMPLICATIONS

Although no statistically significant short-term benefits were observed, longer follow-up should be more informative about the effectiveness of this 6-year supplementation on cancer and other diseases among individuals with esophageal dysplasia.

Nutrition intervention trials in Linxian, China: supplementation with specific vitamin/mineral combinations, cancer incidence, and disease-specific mortality in the general population

BACKGROUND

Epidemiologic evidence indicates that diets high in fruits and vegetables are associated with a reduced risk of several cancers, including cancers of the esophagus and stomach. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian County, China, have one of the world's highest rates of esophageal/gastric cardia cancer and a persistently low intake of several micronutrients.

PURPOSE

We sought to determine if dietary supplementation with specific vitamins and minerals can lower mortality from or incidence of cancer as well as mortality from other diseases in Linxian.

METHODS

Individuals of ages 40-69 were recruited in 1985 from four Linxian communes. Mortality and cancer incidence during March 1986-May 1991 were ascertained for 29,584 adults who received daily vitamin and mineral supplementation throughout this period. The subjects were randomly assigned to intervention groups according to a one-half replicate of a 2(4) factorial experimental design. This design enabled testing for the effects of four combinations of nutrients: (A) retinol and zinc; (B) riboflavin and niacin; (C) vitamin C and molybdenum; and (D) beta carotene, vitamin E, and selenium. Doses ranged from one to two times U.S. Recommended Daily Allowances.

RESULTS

A total of 2127 deaths occurred among trial participants during the intervention period. Cancer was the leading cause of death, with 32% of all deaths due to esophageal or stomach cancer, followed by cerebrovascular disease (25%). Significantly (P = .03) lower total mortality (relative risk [RR] = 0.91; 95% confidence interval [CI] = 0.84-0.99) occurred among those receiving supplementation with beta carotene, vitamin E, and selenium. The reduction was mainly due to lower cancer rates (RR = 0.87; 95% CI = 0.75-1.00), especially stomach cancer (RR = 0.79; 95% CI = 0.64-0.99), with the reduced risk beginning to arise about 1-2 years after the start of supplementation with these vitamins and minerals. No significant effects on mortality rates from all causes were found for supplementation with retinol and zinc, riboflavin and niacin, or vitamin C and molybdenum. Patterns of cancer incidence, on the basis of 1298 cases, generally resembled those for cancer mortality.

CONCLUSIONS

The findings indicate that vitamin and mineral supplementation of the diet of Linxian adults, particularly with the combination of beta carotene, vitamin E, and selenium, may effect a reduction in cancer risk in this population.

IMPLICATIONS

The results on their own are not definitive, but the promising findings should stimulate further research to clarify the potential benefits of micronutrient supplements.

Molecular organization and motions of cholesteryl esters in crystalline and liquid crystalline phases: a 13C and 1H magic angle spinning NMR study

Cholesteryl esters are a major lipid constituent of plasma lipoproteins and atherosclerotic lesions. Crystalline and liquid crystalline phases of several cholesteryl esters [oleate (C18:1, omega-9), erucate (C22:1, omega-9), hexanoate (C6:0), decanoate (C10:0), undecanoate (C11:0), myristate (C14:0), palmitate (C16:0), and stearate (C18:0)] have been studied by natural abundance 13C NMR with magic angle spinning (MASNMR) at 75 MHz (7.05 T). Spectra obtained with magic angle spinning, high-power proton decoupling, and cross-polarization transfer were highly resolved for crystalline cholesteryl esters. Acyl chain carbons had narrower lines than protonated steroid ring carbons, reflecting differential motions in the crystal (specifically, more rapid motions in the acyl chain than in the steroid ring). Esters which crystallize into the monolayer type II structure, in which all molecules are equivalent, gave rise to a single resonance for each carbon; esters of the monolayer type I and bilayer structures, in which there are two types of nonequivalent molecules in the unit cell, had two resonances (equal intensity and line width) for several carbons, such as the carbonyl and the steroid ring C5 and C6. Spectra for liquid crystalline phases did not show inequivalence of signals for the same carbon and were not enhanced by cross-polarization transfer. These changes are a result of increased molecular motions in the liquid crystals, which average the nonequivalent environments and reduce the dipolar interactions. Cholesteric and smectic liquid crystalline phases were distinguished by the broader C = O, C5, and C6 signals for the cholesteric compared with the smectic phase. In the smectic phase, chemical shifts of corresponding carbons of all cholesteryl esters are similar and are close to those for crystalline esters with a monolayer II structure, which suggests that the smectic phase has structural features resembling the monolayer II crystal structure. 13C MASNMR is thus a powerful approach for examining structure and motions of crystalline and liquid-crystalline cholesteryl esters. 1H MASNMR spectra did not give as detailed information on the molecular level but were unique for each phase and provided a simple and quick method for distinguishing the solid, smectic, cholesteric, and isotropic phases.

Geranyl 6-O-beta-D-xylopyranosyl-beta-D-glucopyranoside isolated as an aroma precursor from tea leaves for oolong tea

A new geranyl glycoside, geranyl 5-O-beta-D-xylopyranosyl-beta-D-glucopyranoside was isolated as an aroma precursor from tea leaves (Camellia sinensis var. sinensis cv Shuixian) for oolong tea. The isolation was guided by a two-phase acid hydrolysis and/or an enzymatic hydrolysis followed by GC and GC-MS analyses.

Genomic scanning for expressed sequences in Xp21 identifies the glycerol kinase gene

Rapid genomic scanning methods are required to identify expressed sequences and we report an efficient, sensitive and specific approach which relies upon hybridization of an amplified, labeled cDNA library to digested cosmid DNA. We identified expressed sequences within a cosmid in the glycerol kinase (GK) "critical region" of Xp21 that had impressive similarity to prokaryotic GKs. We used this genomic sequence information to clone the human hepatic GK cDNA. Independent confirmation of the identity of this gene was obtained by functional complementation of GK deficient E. coli mutants with a construct containing the complete human X-linked GK coding sequence.

1H-NMR studies on thymopoietin-type oligopeptides--assignment of the proton resonances and investigation of conformational preferences

The thymopoietin-type tripeptides TP3 (HArg-Lys-AspOH), TP(D-Asp)3(HArg-Lys-D-AspOH) and tetrapeptide TP4 (HArg-Lys-Asp-ValOH) were studied by one- and two-dimensional, 500 MHz 1H-NMR spectroscopy in H2O and D2O solutions at four different pH values. All proton resonances of the three oligopeptides were assigned by two-dimensional phase-sensitive TOCSY experiments at pH 12.2, 9.1, 5.9 and 3.6. At these pH-values well-defined stages of protonation and concomitant molecular charges exist, allowing different possibilities for intra-molecular and inter-residual orientations. Conformation-sensitive rotating frame nuclear Overhauser enhancement (ROESY) two-dimensional experiments were also performed at the above pH values. These experiments indicated no definite solution conformation of any of the molecules at any pH. Standard one-dimensional experiments were also carried out and three-bond coupling constants were measured for the NH--CH and the Asp CH--CH moieties. The coupling constants provided evidence that non-statistical orientations of the functional groups exist which are changed upon protonation of the basic sites.

Effect of intraperitoneal prosthetic materials on reticuloendothelial function in the rat

The effect of different intraperitoneal prosthetic biomaterials on reticuloendothelial system (RES) function and bacterial translocation were studied in the rat. Rubber drains, knitted dacron (KD), or silicone elastomer (SE) with surface areas of either 3 or 10 cm2 were implanted into the lower right part of the abdominal cavity under aseptic conditions. RES function, expressed as the phagocytic index and the uptake of 125I-labeled Escherichia coli (cpm/g tissue) in systemic organs (liver, spleen, lungs, and kidneys) and in gut-associated lymphoid tissues [GALT; i.e., mesenteric lymph nodes (MLN), jejunum, ileum, and colon], was measured 1 day after implantation/sham operation. A significant elevation of the phagocytic index was noted in all implanted groups, except the group with 3 cm2 of SE, as compared with controls. The uptake of 125I-labeled E. coli significantly increased in the liver (rubber, 10 cm2), spleen (rubber, 10 cm2), lungs (rubber, 10 cm2; KD, 3 and 10 cm2; SE, 3 and 10 cm2) and kidneys (rubber, 10 cm2), but significantly decreased in the MLN and jejunum in all implanted groups, in ileum (KD, 10 cm2; SE, 3 cm2), and colon (rubber, 10 cm2; KD, 3 and 10 cm2; SE, 3 cm2). The percentage uptake significantly increased in the systemic organs and decreased in the GALT in most of the implanted groups. Indigenous bacterial translocation to the MLN, liver, spleen, lungs, and kidneys occurred simultaneously. A size-dependent fashion in influence on RES function and incidence of bacterial translocation was observed. The results suggest that intraperitoneal prosthetic biomaterials alter host RES function with concomitant bacterial translocation.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological response of the peritoneum and spleen to intraperitoneal biomaterials

The present study was performed to evaluate the morphological response of the peritoneum and spleen to biomaterials. Silicone elastomer, knitted dacron or rubber was implanted, respectively, into a rat's peritoneal cavity and the morphology of the peritoneum and spleen was studied at 4 hours and on the 1st, 4th, 7th and 21st day after surgery. The morphological changes were identical among groups with different implanted materials. After intraperitoneal implantation of biomaterials from 4 hours and on, an infiltration of inflammatory cells was found in the slackened edematous superficial part of the peritoneum. Also noted in the spleen were stasis, vessel dilatation and fibrin deposition. With the help of scanning electron microscopy, a marked denudation and separation of the mesothelial cells, with infiltration of inflammatory cells, were observed. Peripheral leucocytes significantly increased in number one day after intraperitoneal implantation. Three weeks after intraperitoneal implantation, the materials were completely encapsulated and the morphological aberration of the peritoneum and spleen disappeared. The findings reveal the consequence and the resolution of the host-biomaterial interaction, which could contribute to the explanation of various pathophysiological alterations, including the translocation of enteric bacteria and the development of infectious complications after intraperitoneal biomaterial implantation.

Enteric bacterial translocation after intraperitoneal implantation of rubber drain pieces

To study the kinetics and mechanisms of bacterial translocation from the gut after intraperitoneal (IP) implantation of prosthetic materials, different sizes of rubber drain pieces were intraperitoneally implanted in the rat, followed by evaluation of ileal mucosal permeability after 2 days and of the occurrence of bacterial translocation and gut oxygen extraction at various time points. Enteric bacteria translocated to mesenteric lymph nodes and disseminated to systemic organs (liver, spleen, lungs, and kidneys), the portal vein, and inferior vena cava 2, 4, and 6 h after IP implantation of rubber drain pieces with 10-, 7-, and 3-cm2 areas, respectively, and subsequently to the IP rubber drain piece and the peritoneal cavity on the 2nd postoperative day. The incidence of translocation correlated with the size of the implanted material and time after implantation. The gut oxygen extraction increased significantly after IP implantation of 7- and 10-cm2 rubber drain pieces. The ileal mucosal permeability was enhanced in the groups implanted with 7- and 10-cm2 drain pieces. Thus, bacterial translocation occurs already in the early period after IP implantation of rubber drain and increased with time. The increased gut oxygen extraction implies that the gut is susceptible to IP inflammatory stimulation, and the enhanced ileal permeability suggests that the integrity of the gastrointestinal tract is compromised, which might facilitate bacterial translocation.

Bacterial translocation and reticuloendothelial function after implantation of abdominal drainage in the rat

Bacterial translocation and reticuloendothelial system (RES) function were measured in the rat after intraperitoneal (IP) implantation of rubber drain pieces (7.5 cm2). Six hours after implantation, enteric bacterial translocation was noted to mesenteric lymph nodes (MLNs), the liver, spleen, lungs, kidneys and portal and caval vein blood. RES function was evaluated in terms of blood clearance and organ uptake of intravenously injected 125I-labelled, heat-killed E. coli. A significant elevation of corrected phagocytic index (alpha) was found 24 hours after IP implantation. Localization of 125I-labeled E. coli was significantly enhanced in systemic organs (kidneys, spleen, liver and lungs) 24 hours after IP implantation, whereas it was locally impaired (MLNs and proximal jejunum) 6 hours after IP implantation and thereafter. An inverse correlation between the localization of radiolabelled E. coli in the liver, spleen and lungs and the incidence of bacterial translocation to these organs was found. The results suggest that an association exists between alterations in RES function and bacterial translocation in the early course following IP implantation of rubber drains.

Water-soluble ethylhydroxyethyl cellulose prevents bacterial translocation induced by major liver resection in the rat

Enteric bacteria might act as pathogens, translocating across the intestinal barrier to extraintestinal sites after major liver resection. In the current study, water-soluble ethylhydroxyethyl cellulose (EHEC) was administered before hepatectomy to evaluate the influence on bacterial translocation induced by major liver resection, phagocytic capacity by visceral and circulating macrophages, enteric bacterial population, and bacterial adherence on the intestinal surface in rats subjected to sham operation or to 70% or 90% hepatectomy. Oral or intravenous (IV) administration of EHEC reduced the incidence of bacterial translocation to mesenteric lymph nodes (MLN) and blood after major liver resection. Oral EHEC appeared more effective than IV administration in protecting against bacterial translocation to MLN in animals with 90% hepatectomy. Ethylhydroxyethyl cellulose (oral and IV) significantly diminished intestinal macrophage uptake capacity of 125I-labeled, heat-killed Escherichia coli as compared with animals without EHEC administration. Overgrowth or colonization of enteric bacteria after major liver resection could be prevented by oral or IV EHEC. Adherence of 14C-labeled, alive E. coli on the intestinal mucosa decreased after EHEC treatment in animals subjected to major liver resection. Systemic arterial pressure and intestinal blood flow markedly decreased from 1 hour and on after 90% hepatectomy. Intravenous administration of EHEC did not improve these alterations. Bacterial hydrophobicity and surface negative charge were significantly reduced 1 hour after bacterial culture with EHEC. Thus, EHEC appears to be a potent agent preventing translocation of enteric bacteria from the gut after major liver resection, by altering the surface characters of enteric bacteria, balancing the enteric microflora, inhibiting bacterial attachment onto the intestinal surface, and blocking phagocytosis by intestinal macrophages.

Binding of Escherichia coli to Penrose rubber drains--an in vitro study

Ten different isolates of Escherichia coli were used to compare bacterial attachment to Penrose rubber drains at different temperatures and to investigate a possible relation with cell surface hydrophobicity and charges, as well as the capacity of autoaggregation. Penrose rubber drain pieces of 1 cm2 were incubated with 4.8 x 10(6) E. coli cells for 1 h at 22, 37 and 42 degrees C, respectively. After rinsing with phosphate buffered saline (PBS), the number of adhering bacteria on the drain pieces was calculated by measuring cellular ATP (adenosine triphosphate) bioluminescence. Bacterial cell surface properties at different temperatures were determined by two-phase partitioning and autoaggregation was determined by arbitrary scoring under the dissecting microscope. For most strains of E. coli, the number of adherence to Penrose rubber drain was higher at 22 degrees C than at 37 degrees C and 42 degrees C. Bacterial cell-surface properties and autoaggregation capacity were influenced by the growth temperature, but without correlation to bacterial ability to attach to rubber drains. Thus, the present study demonstrates that attachment of E. coli to Penrose rubber drains was significantly influenced by temperature, but bacterial cell-surface hydrophobicity and charge as well as autoaggregation capacity had no influence on bacterial attachment ability.

Conformational study of two substance P hexapeptides by two-dimensional NMR

The conformation of two substance P (SP) related hexapeptides. Glp-Phe-Phe-(L-Pro)-Leu-Met.NH2 (I) and Glp-Phe-Phe-(D-Pro)-Leu-Met.NH2 (II), in two solvents, chloroform-d and trifluoroethanol(TFE)-d3/H2O, was studied by two-dimensional NMR methods, including COSY, TOCSY, ROESY and HMQC. The study shows that these two peptides exist predominantly in the extended form in TFE/H2O, but in general exhibit a reverse-turn structure in chloroform. I is clearly less ordered than II in both solvents. Furthermore, extensive Phe3-Pro4 cis<==>trans isomerization was found in I but not in II. The differences in the conformational behavior of these two peptides, which are selective agonists for neurokinin NK1 and NK2 receptors, respectively, are discussed.

Hepatocyte-specific expression of the hepatitis B virus core promoter depends on both positive and negative regulation

The core promoter of hepatitis B virus shows hepatocyte specificity, which is largely dependent on an upstream regulatory sequence that overlaps with viral enhancer II. Footprint analyses by numerous groups have shown binding by cellular proteins over a large stretch of DNA in this region, but the identity of these proteins and their role in core promoter function remain largely unknown. We present data showing that the transcription factor HNF-4 is one such factor, as it activates the core promoter approximately 20-fold via a binding site within the upstream regulatory sequence. Since HNF-4 is enriched in hepatocytes, its involvement at least partially explains the hepatocyte specificity of this promoter. In addition, however, we have found a region upstream of the HNF-4 site that suppresses activation by HNF-4 in HeLa cells but not in hepatoma cells. Therefore, the cell type specificity of the core promoter appears to result from a combination of activation by one or more factors specifically enriched in hepatocytes and repression by some other factor(s) present in nonhepatocytes, and it may provide a convenient model system for studying this type of tissue-specific transcriptional regulation in mammalian cells.

Correlations of colon cancer mortality with dietary factors, serum markers, and schistosomiasis in China

To determine correlates of the geographic variation in colon cancer mortality within China, dietary variables, biochemical markers, and other factors from an ecological survey in 49 Chinese rural counties were examined. High consumption of animal foods, salt-preserved vegetables, and beer was associated with increased mortality of colon cancer, whereas the rates were significantly inversely related with intake of green vegetables. Serum levels of total cholesterol, urea nitrogen, and lipid peroxide were positively correlated with colon cancer mortality, after adjustment for each other and for other blood nutrients. No appreciable associations, however, were found between colon cancer and serum levels of beta-carotene, alpha-tocopherol, vitamin C, and selenium. In addition, prevalence of schistosomiasis was significantly correlated with increased colon cancer mortality. This ecological study indicates that observations from earlier analytic investigations in Western societies may apply to a Chinese rural population and suggests that schistosomiasis and dietary factors may contribute to the remarkable geographic variation of colon cancer in China.

Polypyrimidine tract binding protein interacts with sequences involved in alternative splicing of beta-tropomyosin pre-mRNA

Previous studies of alternative splicing of the rat beta-tropomyosin gene have shown that nonmuscle cells contain factors that block the use of the skeletal muscle exon 7 (Guo, W., Mulligan, G. J., Wormsley, S., and Helfman, D. M. (1991) Genes & Dev. 5, 2095-2106). Using an RNA mobility-shift assay we have identified factors in HeLa cell nuclear extracts that specifically interact with sequences responsible for exon blockage. Here we present the purification to apparent homogeneity of a protein that exhibits these sequence specific RNA binding properties. This protein is identical to the polypyrimidine tract binding protein (PTB) which other studies have suggested is involved in the recognition and efficient use of 3'-splice sites. PTB binds to two distinct functional elements within intron 6 of the beta-tropomyosin pre-mRNA: 1) the polypyrimidine tract sequences required for the use of branch points associated with the splicing of exon 7, and 2) the intron regulatory element that is involved in the repression of exon 7. Our results demonstrate that the sequence requirements for PTB binding are different than previously reported and shows that PTB binding cannot be predicted solely on the basis of pyrimidine content. In addition, PTB fails to bind stably to sequences within intron 5 and intron 7 of beta-TM pre-mRNA, yet forms a stable complex with sequences in intron 6, which is not normally spliced in HeLa cells in vitro and in vivo. The nature of the interactions of PTB within this regulated intron reveals several new details about the binding specificity of PTB and suggests that PTB does not function exclusively in a positive manner in the recognition and use of 3'-splice sites.