Effects of porcine epidemic diarrhea virus infection on Toll-like receptor expression and cytokine levels in porcine intestinal epithelial cells

To explore the role of Toll-like receptors (TLRs) and interferon (IFN) in the innate immunity against porcine epidemic diarrhea virus (PEDV), we detected the expression of TLR genes in PEDV-infected IPEC-J2 cells by real-time PCR. We also detected the level of interferon α (IFN-α) and interferon γ (IFN-γ) by enzyme-linked immunosorbent assay (ELISA). Results showed that IPEC-J2 cells exhibited a clear pathological change after PEDV infection at 24 h. In addition, TLR7, TLR9 and TLR10 expressions were significantly upregulated in PEDV-infected IPEC-J2 cells at 24 h. Interestingly, the expression patterns of TLR2 and TLR4 were consistent at different stages of PEDV infection. The expression level of TLR3 decreased significantly with the increase of infection time, but the expression levels of TLR5 and TLR8 genes at 6 h and 12 h were significantly lower than those in the control group (p⟨0.01). There were significant correlations among the expression levels of TLR genes (p⟨0.05). Cytokine detection showed that the secretion level of IFN-α in the PEDV-infected group was significantly higher than that in the control group (p⟨0.01), and IFN-γ at 6 h and 12 h after PEDV infection was significantly higher than that in control group (p⟨0.01). Therefore, our results suggest that PEDV infection can induce innate immune responses in intestinal porcine jejunum epithelial cells, leading to changes in the expression of Toll-like receptors, and can regulate the resistance to virus infection by affecting the release levels of downstream cytokines.

Effects of porcine epidemic diarrhea virus infection on tight junction protein gene expression and morphology of the intestinal mucosa in pigs

Tight junction proteins are important for the maintenance and repair of the intestinal mucosal barrier. The present study investigated relationships among tight junction protein gene expression, porcine epidemic diarrhea virus (PEDV) infection, and intestinal mucosal morphology in piglets. We compared the expression of six tight junction proteins (ZO-1, ZO-2, Occludin, Claudin-1, Claudin-4, and Claudin-5) between seven-day-old piglets infected with PEDV and normal piglets, as well as in PEDV-infected porcine intestinal epithelial cells (IPEC-J2). We also evaluated differences in mucosal morphology between PEDV-infected and normal piglets. The expression of six tight junction protein genes was lower in PEDV-infected piglets than in the normal animals. The expression of ZO-1, ZO-2, Occludin, and Claudin-4 in the intestine tissue was significantly lower (p⟨0.05) in PEDV-infected than in normal piglets. The expression of Claudin-5 in the jejunum was significantly lower in PEDV-infected piglets than in the normal animals (p⟨0.01). The expression of Claudin-1 and Claudin-5 genes in the ileum was significantly higher in PEDV-infected piglets than in normal piglets (p⟨0.01). Morphologically, the intestinal mucosa in PEDV-infected piglets exhibited clear pathological changes, including breakage and shedding of intestinal villi. In PEDV-infected IPEC-J2 cells, the mRNA expression of the six tight junction proteins showed a downward trend; in particular, the expression of the Occludin and Claudin-4 genes was significantly lower (p⟨0.01). These data suggest that the expression of these six tight junction proteins, especially Occludin and Claudin-4, plays an important role in maintaining the integrity of the intestinal mucosal barrier and resistance to PEDV infection in piglets.

Robotic pancreatectomy for solid pseudopapillary tumors in the pancreatic head: A propensity score-matched comparison and analysis from a single center

BACKGROUND

Robotic surgery is the most advanced minimally invasive technique for the treatment of complicated solid pseudopapillary tumors (SPT). The aim of this study is to evaluate feasibility of robotic surgery for the treatment of SPTs in the pancreatic head.

METHODS

A retrospective analysis of the clinical data of 83 SPTs in pancreatic head was conducted. Clinical characteristics were extracted and propensity score matching (PSM) was used to compare and evaluate mid-term outcomes of the two techniques.

RESULTS

Pancreaticoduodenectomy (PD), duodenum-preserving partial pancreatic head resection (DPPHR-P) and tumor enucleation (En) were performed in 51, 24, and 8 patients, respectively. The robotic approach was associated with a significantly lower volume of blood loss, lower need for transfusion, and faster time to post-surgery recovery. Major complications and costs were comparable for both techniques.

CONCLUSION

A robotic approach provides an alternative to open surgery for SPTs in the pancreatic head without increasing the incidence of clinically relevant pancreatic fistula (CRPF) or other major complications and with good patient outcomes.

Manipulation of group-velocity-locked vector dissipative solitons and properties of the generated high-order vector soliton structure

Details of various composites of the projections originated from a fundamental group-velocity-locked vector dissipative soliton (GVLVDS) are both experimentally and numerically explored. By combining the projections from the orthogonal polarization components of the GVLVDS, a high-order vector soliton structure with a double-humped pulse profile along one polarization and a single-humped pulse profile along the orthogonal polarization can be observed. Moreover, by de-chirping the composite double-humped pulse, the time separation between the two humps is reduced from 15.36 ps to 1.28 ps, indicating that the frequency chirp of the GVLVDS contributes significantly to the shaping of the double-humped pulse profile.

Detection of QTLs controlling fast kernel dehydration in maize (Zea mays L.)

In order to understand the effect of grain moisture of inbred lines at the silking and physiological maturity stages on kernel dehydration rate, 59 maize inbred lines from six subgroups were selected. Grain moisture was measured and QTLs associated with kernel dehydration were mapped. A rapid dehydration evaluation and association analysis revealed eight inbred lines with faster dehydration rate, including Yuanwu 02, K36, Zhonger/O2, Lo1125, Han 49, Qi 319, Hua 160, and PH4CV. A single sequence repeat analysis using 85 pairs detected five QTLs with phenotypic variation contribution ≥10% in the permanent F2 generation populations Zheng 58 x S1776 and Chang 7-2 x K1131, which had LOD threshold values ≥ 3 in both 2013 and 2014. The chromosome region of qFkdr7b had not previously been reported and is preliminarily identified as a new major QTL. A false positive field verification of grain dehydration rate of 53 inbred lines indicated that the screening result of the rapid dehydration inbred lines by specific amplification with marker Phi114 was most similar to the field assessment result, followed by markers Phi127 and Phi029. The rapid dehydration lines selected based on primer Phi114 amplification were also similar to the field dehydration rate and can thus be used for molecular marker-assisted selection. A significant effort is needed to improve stress resistance and shorten the growth period via fast kernel dehydration in intermediate materials of the inbred lines K36, Zhonger/ O2, Lo1125, Han 49, Hua 160, and PH4CV, and further using the selected lines for new combinations.

Genetic analyses of the major and minor locus groups of bacterial wilt resistance in tobacco using a diallel cross design

Tobacco germplasm samples with various levels of resistance to bacterial wilt were selected to construct F1 combinations of parental inbred lines and orthogonal diallel crosses using samples collected in 2009 (15 germplasms), 2010 (15 germplasms), and 2011 (16 germplasms). A total of 1/2P (P + 1) experimental materials were used for analysis. Based on the analyses of major and minor locus groups, genetic effects on the incidence rate and index of bacterial wilt in tobacco were investigated on the 15th and 25th day during the early stage. Significant effects were observed in major locus groups, but not in minor locus groups. Specifically, adjacent major locus groups (J1 = 13,056 and J1 = 13,055; J1 = 14,080 and J1 = 14,079) were detected in both the first and second analyses with considerable effects. Based on the additive effects of minor locus groups on the rate and index of bacterial wilt, the effects on the incidence rates of Yunyan 85, DB101, and RG11 as well as the effects on the disease index of the latter two germplasms reached the maximum. This was consistent with the disease resistance indicators of these tobacco varieties in the field (corresponding broad heritability >20%). Genetic homozygous dominant loci (+ +) increased the rate of bacterial wilt (susceptible), whereas homozygous recessive loci (- -) reduced the index of bacterial wilt (resistant) with considerable additive effects and low dominant effects, suggesting that the inheritance of the bacterial wilt rate and index in tobacco mainly relies on additive inheritance.

Association between polymorphisms in exons 4 and 10 of the BPI gene and immune indices in Sutai pigs

The bactericidal/permeability-increasing protein (BPI) gene has been identified as a candidate gene for disease-resistance breeding. We evaluated whether polymorphisms in exons 4 and 10 of the BPI gene are associated with immune indices [interleukin-2 (IL-2), IL-4, IL-6, interferon-b (IFN-b), IL-10, and IL-12]. In this study, we identified one mutation (C522T) in the BPI exon 4 site and two mutations (A1060G and T1151G) in the BPI exon 10 site. Correlation analysis revealed that in the Sutai pig population, the effect of genotypes at the BPI exon 4 site on the level of IL-6 was significant (P < 0.05), with an effective genotype of CD; moreover, the effect of genotypes at the BPI exon 10 site on the level of IL-12 was significant (P < 0.05), and the effective genotype was AB. The optimal combined genotype was CD-AB, which was more effective regarding the IL-6 and IL-12 levels compared to the other combined genotypes (P < 0.05). These results indicate that single nucleotide polymorphisms and the combined genotypes of BPI exons 4 and 10 affect immune indices in Sutai pigs. Therefore, these genotypes should be further examined as effective markers for disease-resistant breeding of pigs.

Identification of BPI protein produced in different expression system and its association with Escherichia coli F18 susceptibility

The super antibiotic bactericidal/permeability-increasing (BPI) protein is a member of a new generation of proteins that have been implicated as endotoxin-neutralizing agents. In this study, recombinant porcine BPI protein was obtained by generating porcine BPI encoding prokaryotic, eukaryotic, and yeast expression vectors. Recombinant protein expression was detected in yeast GS115, Escherichia coli, and 293-6E cells by gel electrophoresis and Western blotting. Escherichia coli F18 is the primary Gram-negative bacteria in the gut and the main pathogen leading to diarrhea and edema dis-ease in weaning piglets. Therefore, E. coli F18-resistant and -sensitive Sutai piglets were used to test differential expression of BPI protein by Western blotting and to investigate the potential correlation between BPI protein expression and E. coli F18-susceptibility. Recombinant porcine BPI protein expression was not detected in the prokaryotic and yeast expression systems; however, soluble protein was detected in the eukaryotic expression system. These data indicate the strong bacterio-static action of the BPI protein and confirm the feasibility of obtaining large amounts of recombinant porcine BPI recombinant protein using this eukaryotic expression system. In addition, the BPI protein expres-sion levels in the E. coli F18-resistant group were significantly higher than those in the sensitive group, indicating that high BPI protein ex-pression is associated with resistance to E. coli F18. Our findings pro-vide a basis for further investigations into the development of a drug designed to confer resistance to E. coli F18 in weaning piglets.

Age-dependent expression of the BPI gene in Sutai piglets

We compared and analyzed the expression of the BPI gene of Sutai piglets ranging from newborn to post-weaning days 8, 18, 30, and 35 by the real-time PCR method, in order to determine if it is involved in protection against disease caused by ETEC F18. There was a significant difference between 18 and 35-day expression in the jejunum. There were also significant differences between 35-day expression and expression at the other development stages in the duodenum. There were no significant differences in expression at 8, 18, and 30 days in the jejunum. We conclude that the porcine BPI gene may be the direct factor that resisted the ETEC F18 in weaning piglets, and that the resistance to ETEC F18 in weaning piglets is related to up-regulation of mRNA expression of BPI gene to a certain extent.

Mode-dependent effect of high-frequency electrical stimulation of the anterior thalamic nucleus on amygdala-kindled seizures in rats

Deep brain stimulation (DBS) is an emerging treatment of epilepsy. Anterior nucleus of the thalamus (ANT) is considered to be an attractive target due to its close connection to the limbic structures and wide regions of neocortex. The present study aimed to investigate the effects of high frequency stimulation (HFS) targeting the ANT on amygdala-kindled seizures in Wistar rats in two different stimulation modes i.e. pre-treatment and post-treatment stimulations, mimicking the scheduled and responsive stimulations in clinical use respectively. When fully-kindled seizures were achieved by daily amygdala kindling (1 s train of 1 ms pulses at 60 Hz), HFS (15 min train of 100 μs pulses at 150 Hz and 450-800 μA) was applied in two modes for 10 days. Bilateral post-treatment with HFS reduced the incidence of generalized seizures and the mean behavioral seizure stage and shortened average afterdischarge duration (ADD) and generalized seizure duration (GSD), while bilateral pre-treatment with HFS resulted in a similar but much weaker inhibition of seizures. On the other hand, we also found the two stimulation modes both increased the afterdischarge threshold (ADT) and the differences of current intensity between ADT and generalized seizure threshold (GST) i.e. Δ(GST-ADT). However, Δ(GST-ADT) increased by at least 20 μA in bilateral post-treatment group, while less in bilateral pre-treatment group. Additionally, unilateral post-treatment with HFS failed to inhibit seizures. Our data show that anti-epileptic effect of bilateral post-treatment with HFS of ANT is much stronger than that of bilateral pre-treatment HFS, indicating bilateral responsive stimulation might be more appropriate for clinical anti-epileptic treatment of ANT HFS.

Internet resources related to drug action and human response: a review

It has been demonstrated that numerous proteins interact with drugs or their metabolites. Knowledge of these proteins is necessary to understand the mechanisms of drug action and human response. Progress in modern genetics, molecular biology, biochemistry and pharmacology is generating a comprehensive mechanistic understanding of drug-target interaction on the molecular level. This is valuable for researchers and pharmaceutical companies in their efforts to improve the efficacy of existing drugs and to discover new ones. Most recently, the integration of a systems biology approach into drug discovery processes calls for more holistic knowledge and easily accessible resources of the proteins that are important in drug action and human response. We have reviewed many publicly accessible internet resources of these proteins, according to their roles in drug action and human response, such as therapeutic effect, adverse reaction, absorption, distribution, metabolism and excretion.

Membrane bioreactor process of organic wastewater from brassylic acid manufacturing plant

The wastewater treatment from brassylic acid manufacturing plant using membrane bioreactor (MBR) was studied. The membrane bioreactor consisted of batch-operation biological aeration tank and ultrafiltration evaluation tank. The content of test included the affection of variation operation conditions on ultrafiltration separation, the general characteristics of MBR process, and the difference comparing with the conventional biological treatment. The results are as follows: (1) among the test membrane material, polyether sulphone (PES) membrane is more suitable for the wastewater treatment; (2) when the cutoff molecular weight is among 10,000-50,000, the higher the cutoff molecular weight, the bigger the water flux is in the test; (3) under the operation pressure, water flux increases accompanying with the increasing of operation pressure; (4) the paper filtered COD concentration has more affection on the water flux than the suspended solid concentration; (5) as the volume loading of MBR increases, the accumulation of high molecule organic substance and colloid increases, the membrane permeate COD concentration and paper filtered COD concentration increase too, meanwhile the water flux reduces; (6) when the sludge retention time of activated sludge of MBR increases, the accumulation of high molecule organic substance and colloid reduces, the membrane permeate COD concentration and paper filtered COD concentration reduce too, and the water flux increases; (7) comparing with the conventional biological process, the microbial activity is higher, but the microbial species is less.

Gene structure for adenosine kinase in Chinese hamster and human: high-frequency mutants of CHO cells involve deletions of several introns and exons

The structure for the adenosine kinase (AK) gene has been determined from Chinese hamster (CH) and human cells. The AK gene in CH is comprised of 11 exons ranging in length from 36 to 765 nt, with the majority <100 nt. The exact lengths of the intervening introns have not been determined, but most of them are indicated to be very large (>15 kb). A 6.6-kb fragment from human cells was also sequenced, and it contained only a single exon corresponding to exon 10 in CH. The BLAST searches of the subsequently released draft human genome sequence have revealed that the AK gene structure in human is identical to that in CH. In the human genome, the AK exons are distributed over four genomic clones totaling 752 kb, providing direct evidence that the AK gene in mammalian species is unusually large. In contrast to CH and human, the AK genes from several other eukaryotic organisms whose complete genomes are now known are quite small (between 1.2 and 2.5 kb) and either contain no introns (Saccharomyces cerevisiae and Schizosaccharomyces pombe) or various numbers of introns (Drosophila melanogaster [2], Caenorhabditis elegans [4], Arabidopsis thaliana [10]). Some of the intron-exon junctions in these species are in the same positions as in mammals. The AK gene in CH and human, as well as mouse, is linked upstream in a head-to-head fashion with the gene for the clathrin adaptor mu3 protein (or beta 3A subunit of the AP-3 protein complex), which is affected in type 2 Hermansky-Pudlak syndrome. These two genes are separated by <200 nt, and it is possible that they have a common or overlapping promoter(s). We have also determined the nature of the genetic alterations in two of the class A AK(-) mutants of CHO cells, which are obtained at a very high spontaneous frequency (10(-3)-10(-4)) in this cell line. Both mutants contained large deletions within the AK gene and greatly shortened AK transcripts. The cloning and sequencing of the transcripts from these mutants showed that the deletion in one of them led to the loss of exons 5 through 8, whereas in the other, all exons from 2 through 8 are deleted. The endpoints of these deletions lie in the large introns within the AK gene.

Crude protein content and amino acid composition in Taiwanese human milk

Breast milk provides the essential nutrients for infants in readily available form. The content of nitrogen in human milk is of great importance because it relates to the growth of infants in the early stage, and the composition of nitrogenated compounds varies according to the lactational stage. Three-hundred-and-three human milk specimens were obtained from 240 healthy mothers living in two different districts in Taiwan, and 264 specimens were used for the analysis. The crude protein content, total and free amino acid compositions as well as urea content were evaluated using pooled milk samples according to different lactational stages and geographical location. The crude protein content decreased sharply from colostrum (2.51 g/100 mL) to mature milk (1.25 g/100 mL). Total amino acids account for 80-85% of the crude protein throughout the whole lactation period. Crude protein also contained 30 to 35 mg/ 100 mL urea and 41 to 48 mg/ 100 mL free amino acids as non-protein nitrogen components. The ratio of essential to non-essential amino acids remained constant throughout the lactation period in spite of a decline in amino acid content. The amino acid composition per 1 g of nitrogen varied during the lactation period. The differences of these lactational changing patterns of individual amino acids were probably reflected by variation of the protein composition during lactation. The sum of free amino acid content ranged from 43 to 50 mg/100 mL in Taipei and 40 to 45 mg/100 ml, in Kaohsiung. Although the variations of free amino acids during the lactation period differed among amino acids, glutamic acid predominated in mature milk while phosphoethanolamine was predominant in colostrum.

Cloning and some novel characteristics of mitochondrial Hsp70 from Chinese hamster cells

The cDNA for Chinese hamster mitochondrial Hsp70 (mHsp70) was cloned and sequenced using a polymerase chain reaction probe based on conserved regions in the Hsp70 family of proteins. The encoded protein consists of 679 amino acids which includes a N-terminal mitochondrial targeting sequence of 46 amino acids. The mHsp70 protein contains several sequence signatures that are characteristics of prokaryotic and eukaryotic organellar Hsp70 homologs. In a phylogenetic tree based on Hsp70 sequences, it branches with the gram-negative proteobacteria, supporting the endosymbiotic origin of mitochondria from this group of prokaryotes. The mHsp70 cDNA was transcribed and translated in vitro and its import into isolated rat heart mitochondria was examined. The precursor mHsp70 was converted into a mature form of lower molecular mass (approximately 71 kDa) which became resistant to trypsin digestion. The import of mHsp70 into mitochondria was not observed in the presence of an uncoupler of energy metabolism or when the N-terminal presequence was lacking. The cDNA for mHsp70 was expressed in Escherichia coli and a polyclonal antibody to the purified recombinant protein was raised. The antibody shows no cross-reactivity to recombinant cytosolic Hsp70 protein and in 2-D gel blots it reacted specifically with the mHsp70 protein only. In immunofluorescence experiments, the antibody predominantly labeled mitochondria, and the observed labeling pattern was identical to that seen with a monoclonal antibody to the mitochondrial Hsp60 chaperonin. The affinity-purified antibody to mHsp70 was also employed to examine the subcellular distribution of the protein by cryoelectron microscopy and the immunogold-labeling technique. In these experiments, in addition to mitochondria, labeling with mitochondrial Hsp70 antibody was also observed on the plasma membrane and in unidentified cytoplasmic vesicles and granules. These studies raise the possibility that similar to the Hsp60 chaperonin and a number of other mitochondrial proteins, mHsp70 may have an extramitochondrial role.

Responses of blood glucose and C-peptide to five Chinese starchy foods

Forty-nine patients with non-insulin-dependent diabetes mellitus (NIDDM) were randomly divided into four groups (10-18 patients per group) to compare the responses of blood glucose and C-peptide to some Chinese starchy foods. Ten healthy subjects were used as controls. After an overnight fast, the blood samples were drawn at fasting and 30, 60, 120, 180 minutes postprandially to measure plasma glucose and serum C-peptide levels. Bun, which was made from refined wheat flour and similar to white bread, was used in the assessment as the reference food. Other test foods included rice, lotus seed, seed of gordon euryale, and rhizome of common yam. There was only one kind of food in each test meal, and each serving contained 50 g of carbohydrate. With both glycaemic index (GI) and C-peptide index (CI) of bun set as 100 in this study, the GI and CI respectively were: rice 89 and 91; lotus seed 62 and 72; seed of gordon euryale 102 and 102; rhizome of common yam 103 and 95. The GI and CI of lotus seed were significantly lower than those of other test foods. It appears that lotus seed may have a beneficial effect in NIDDM patients, and may be one of the more appropriate foods for diabetic patients.

The production of medical audiovisual teaching materials--Chinese style

The production of medical audiovisual material for the advancement of medical education in China is a problem requiring an urgent solution. To achieve faster, better and more economical results, the production of audiovisual material must be undertaken with careful planning and efficient management. A systematic approach is essential to control production. The procedures described are: leadership and management; choice of subject and medium; production; distribution and evaluation.

[The effects of chlorine disinfection on the resistance of E. coli in water]

Under defined conditions E. coli were subjected to repeated chlorine disinfections 10 times. The survival E. coli at 30 s (A10), and the survival E. coli at 10 min (B10) had no difference in resistance to chlorine to their original strain (A0). However, the compound E. coli (C10) survived at various contact time showed an increased resistance than their original strain (A10), the degree of increased resistance varying with different conditions of disinfection. E. coli C1(0) lost its increased resistance after it has been passaged 10 times on nutrient agar.

[The effects of chlorine disinfection on the resistance of bacteriophage f2 in water]

Under defined conditions, E. coli bacteriophage f2 was subject to repeated disinfection by chlorine 10 times. The survival bacteriophage f2 was compared with its original strain in resistance to chlorine. Experimental results showed that bacteriophage f2 increased its resistance after chlorine disinfection. The increased resistance varied under different conditions. The higher the pH, the greater the increased resistance. The survival bacteriophage f2 maintained its increased resistance though it was passaged 10 times in nutrient broth. The reason for the increased resistance of bacteriophage f2 after chlorine disinfection was probably the chlorine-induced mutation or spontaneous chlorine-resistant mutation.

Determination of enantiomeric purity of ephedrine and pseudoephedrine by high-performance liquid chromatography with dual optical rotation/UV absorbance detection

A reversed-phase high-performance liquid chromatography (HPLC) method with dual optical rotation/UV absorbance detection has been developed for the determination of enantiomeric purity of ephedrine hydrochloride and pseudoephedrine hydrochloride using an achiral column. The method gave a correlation coefficient of 0.9997 for the plot of log(optical rotation response) versus log (concentration) over the range of 0.06-10 mg ml(-1) of (+)-ephedrine hydrochloride (20 microliters injection). The limit of detection was 1.0 micrograms. Enantiomeric purity is shown to be most readily determined by measuring optical rotation, alpha, and absorbance, A, responses for standard and unknown samples, and using the equation (alpha/A)u/(alpha/A)s = (2xu - 1)/(2xs - 1), where x is the mole fraction of one of the enantiomers and subscripts s and u refer to standard and unknown, respectively. In blind trials using unknown mixtures of (+)- and (+/-)-ephedrine hydrochloride and a (+)-ephedrine hydrochloride standard, enantiomeric purities were determined to +/- 0.4% (95% confidence level) with five or six replicate 50 micrograms injections. The method has also been applied to the determination of the enantiomer mole fraction of (+)-pseudoephedrine hydrochloride in a cough linctus, giving xu = 0.99 +/- 0.01 with seven replicate injections of 20-fold diluted linctus samples containing 7.5 micrograms of the chiral compound being assayed. Unlike conventional polarimetry, the method does not require chemically-pure samples and can be orders of magnitude more economical in material.

Functional evidence for the presence of cholinergic nerve endings in the colonic mucosa of the rat

Uptake of [3H]choline and the subsequent synthesis and release of [3H]acetylcholine was studied in a preparation of rat colonic mucosa in vitro. [3H]Choline uptake was inhibited by hemicholinium-3. Release of synthesized [3H]acetylcholine was increased significantly over base line by 50 mM K+ and 100 microM veratridine. K+-evoked release was inhibited by 83% in tissue preincubated (during [3H]choline uptake) in Na+-free media. The effect of K+ was also blocked in Ca++-free media by 15 mM Mg++ and 0.1 mM verapamil. Release from the longitudinal and circular muscle of the colon evoked by K+ and veratridine was greater than release from the mucosa. Tetrodotoxin (0.2 microM) did not affect K+-induced release of [3H] acetylcholine but significantly blocked veratridine-induced release from the mucosal (by 63%) and muscle (by 68%) preparations. The data confirm that functional cholinergic nerve endings exist in close proximity to colonic epithelial cells.

Release of [3H]norepinephrine from nerves in rat colonic mucosa: effects of norepinephrine and prostaglandin E2

Release of [3H]norepinephrine ([3H]NE) from noradrenergic nerves innervating rat colonic mucosa was studied by superfusion of a muscle-stripped preparation of rat colon. After a period of incubation with [3H]NE, the tissue was superfused with different releasing agents. Depolarization of the tissue with a medium containing 50 mM K+ evoked the release of [3H]NE. Veratridine (5 X 10(-5) M) also stimulated the efflux of [3H]NE; this was blocked by tetrodotoxin (2 X 10(-7) M). Tyramine, which releases NE by a nondepolarizing mechanism, also evoked [3H]NE release from the colonic mucosal preparation, and this release was not decreased in the absence of calcium. Exogenous NE (10(-7) M) inhibited the high K+-evoked release by 50% in the presence of desmethylimipramine, a NE uptake inhibitor. In addition, prostaglandin E2 (1 X 10(-7) M) significantly reduced the K+-evoked release to less than 50% of control. Pretreatment with 6-hydroxydopamine, which selectively destroys NE neurons, reduced the K+-evoked release of [3H]NE to 40% of control. This study suggests that colonic mucosa of the rat contains noradrenergic nerves that function in a manner characteristic of the noradrenergic nerves in other tissues.

Functional properties of noradrenergic nervous system in rat colonic mucosa: uptake of [3H]norepinephrine

The accumulation of exogenous [3H]norepinephrine ([3H]NE) by rat colonic mucosa was studied. Uptake was linear for 10 min and reached a maximum after 90 min. The process was concentration dependent and saturable, having a Km of 1.67 X 10(-6) M and Vmax of 0.57 nmol.g-1.min-1. The inhibitor of specific norepinephrine uptake, desmethylimipramine (DMI), inhibited uptake in a concentration-dependent manner; the maximum inhibition was 81% at 10 microM. Normetanephrine also inhibited uptake at 100 microM. Reserpine, at concentrations ranging from 10(-7) to 10(-5) M, prevented the accumulation of [3H]NE, with maximum inhibition being 47% of control. Accumulation by mucosa obtained from rats sympathectomized with 6-hydroxydopamine was only 33% of control; DMI did not further reduce this uptake. Colonic epithelial cells were isolated and were found to also accumulate [3H]NE, but this accumulation was not affected by DMI. It is concluded that rat colonic mucosa contains noradrenergic neurons capable of accumulating exogenously administered norepinephrine by a specific and high-affinity process. The presence of a functional noradrenergic neural network in close association with the epithelium suggests that this system may play a physiological role in modulating colonic mucosal function.

Effects of pancreatic polypeptide and vasoactive intestinal polypeptide on rat ileal and colonic water and electrolyte transport in vivo

Two gastrointestinal peptides, vasoactive intestinal polypeptide (VIP) and pancreatic polypeptide, suspected of being associated with symptoms of WDHA syndrome (pancreatic cholera) were tested on the rat small and large intestine for their effects on water and electrolyte transport. Intravenous infusion of VIP (14.3 microgram/kg/hr) inhibited net absorption of water and electrolytes in the ileum and reversed net absorption to net secretion in the colon. In contrast, bovine pancreatic polypeptide (52 microgram/kg/hr) did not inhibit absorption or stimulate secretion. These data indicate VIP causes colonic secretion in vivo, an effect previously shown only in vitro, and that bovine pancreatic polypeptide (at this dose) is not a secretagogue in the small or large intestine of the rat. Thus, while consistent with VIP being a contributory agent to the secretion of pancreatic cholera, the data do not support the notion that pancreatic polypeptide might be a causative agent in this syndrome.