Intraduodenal neuropeptide levels,but not plasma levels,vary in a cyclic fashion with the migrating motor complex

The neurohormonal control of the migrating motor complex (MMC) is not fully understood. The hypothesis of the present study was that neuropeptide levels might vary with the different phases of the MMC and that a similar variation might be found in the secretions of the gastrointestinal tract. Thus, plasma and intraduodenal concentrations of vasoactive intestinal peptide (VIP), somatostatin (SOM), substance P (SP) and neurokinin A (NKA) were determined by radioimmunoassay every 10 min during two complete MMC cycles in eight male subjects. For comparison, plasma motilin (MOT) concentrations were measured. Plasma concentrations of MOT (mean peak value ± SEM; 39 ± 6 pmol L^?1), but none of the neuropeptides studied, showed a cyclic variation in plasma with the different phases of the MMC. Peak intraduodenal concentrations of VIP (79 ± 23 pmol L^?1),?SOM (2437 ± 432 pmol L^?1) and SP (718 ± 326 pmol L^?1) occurred at or at the time point before the onset of phase III of the MMC. No such correlation was observed for NKA. These results demonstrate that intraduodenal but not plasma concentrations of the neuropeptides VIP, SOM and SP show an association with phase III of the MMC. The biological relevance of this finding is yet unclear, but the results raise the possibility that gut neuropeptides may regulate fasting motility through a luminal release.     

Effect of prostaglandin E2 on agonist-stimulated cAMP accumulation in the distal convoluted tubule isolated from the rabbit kidney

The effects of calcitonin, vasoactive intestinal peptide (VIP), parathyroid hormone (PTH) and isoprenaline on intracellular cAMP accumulation were determined in the distal tubule (DCT) microdissected from collagenase-treated rabbit kidney. In DCTb (the initial bright portion) calcitonin (10 ng/ml) elicited a highly reproducible response 203.7±19.1 fmol cAMP mm^–1 4 min^–1 (SE, N=13) whereas VIP-induced cAMP accumulation was less and more variable from one experiment to another (1 M, 97.2±17.8 fmol mm^–1 4 min^–1, SE, N=12). When used in combination, these two agonists were non-additive, indicating stimulation of a single pool of cAMP in DCTb. In DCTg, (granular) which consists of at least two cell types, PTH (100 nM) elicited a marked, reproducible accumulation of cAMP (154.3±27.0 fmol mm^–1 4 min^–1; SE, N=5). Isoprenaline (1 M) and VIP (1 M) induced much smaller increases in cAMP levels 20.9±2.7 and 29.4±4.1 fmol mm^–1 4 min^–1 (SE, N=5) respectively, and, when used in combination, were non-additive, demonstrating that VIP and isoprenaline are active on the same cell type. In DCTb, prostaglandin E₂ (PGE₂) inhibited both calcitoninand VIP-stimulated cAMP accumulation (calcitonin 57.8±2.7% inhibition, SE, N=16; VIP, 80.6±2.1% inhibition, SE, N=5). The EC₅₀ values for calcitonin were 1.21±0.33 ng/ml and 1.83±0.25 ng/ ml (SD, N=3) in the absence and presence of PGE₂ (300 nM) respectively with an IC₅₀ for PGE₂ of 26.3±6.3 nM (SE, N=4). In contrast, no effects of PGE₂ were seen in DCTg vis à vis PTH, isoprenaline or VIP. The percentage inhibition of calcitonin-stimulated cAMP accumulation by PGE₂ was of the same order in the presence of isobutylmethylxanthine (an inhibitor of all types of phosphodiesterase), Ro 20-1724 (inhibitor of low-K _m cAMP-specific phosphodiesterase) or in the absence of inhibitor. Preincubation of DCTb with pertussis toxin for up to 8 h in different experimental conditions did not relieve the inhibition by PGE₂. Protein kinase C activation by phorbol ester did not attenuate calcitonin responses. These data demonstrate that the inhibition by PGE₂ of cAMP production is restricted to the initial portion (DCTb) of the distal convoluted tubule and is effective on both calcitonin and VIP responses. When tested in the presence of Ro 20-1724, ionomycin, A₁-adenosine, ₂-adrenergic and muscarinic agonists were without effect on calcitoninand PTH-stimulated cAMP accumulation in DCTb and DCTg respectively.     

Alveolar capillary dysplasia with misalignment of the pulmonary veins and hypoplastic left heart sequence caused by an in frame deletion within FOXF1

Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACDMPV) is a rare, autosomal dominant disorder of interstitial lung development, leading to pulmonary hypertension, and death in infancy. Associated features include malformations of the heart, gastrointestinal tract, and genitourinary system. ACDMPV is caused by heterozygous variants in the FOXF1 gene or microdeletions involving FOXF1. We present a male infant with ACDMPV, hypoplastic left heart sequence (HLHS), duodenal atresia, and imperforate anus due to a de novo, in frame deletion in FOXF1: c.209_214del (p.Thr70_Leu71del). Previous reports have suggested that microdeletions involving FOXF1 are associated with ACDMPV with congenital heart defects, including HLHS, gastrointestinal atresias, and other anomalies; whereas likely pathogenic variants within FOXF1 have not been reported with ACDMPV and HLHS. This is the first patient reported with ACDMPV, HLHS, imperforate anus, and duodenal atresia associated with a likely pathogenic variant in the FOXF1 gene.     

Induction and persistence of local rotavirus antibodies in relation to serum antibodies

The induction and persistence of local rotavirus antibodies, including stool IgA, jejunal IgA, and jejunal neutralizing antibody, were evaluated in 14 adult volunteers infected with the CJN strain of human rotavirus. In addition, the relationships between local rotavirus IgA and serum rotavirus IgA, IgG, and neutralizing antibody were determined. Both stool and serum rotavirus IgA appeared to have similar kinetics. Both antibodies peaked by days 14-17 after inoculation in all subjects, then decreased rapidly. By days 26-28, titers had fallen to 13% and 30% of their respective peaks. Serum rotavirus IgG peaked somewhat later, occurring in five subjects on days 26-28. Serum neutralizing antibody peaked on days 26-28 in all but three subjects. Both serum IgG and neutralizing antibodies also declined more slowly than rotavirus IgA. Although all antibody concentrations had decreased to only a fraction of their peak responses by days 270-365 after rotavirus inoculation they remained higher than baseline levels. For example, stool rotavirus IgA concentrations were 13.5-fold higher than baseline, while jejunal rotavirus IgA and neutralizing antibody were 8.9- and 4.3-fold above baseline, respectively. Similarly, serum antibodies remained 3.7- to 11.2-fold higher than baseline at 270-365 days after rotavirus inoculation. These studies imply that serum rotavirus IgA is a good indicator of local antibody responses. Furthermore, although both serum and local antibody titers peaked within 2-4 weeks after infection, these antibodies persisted at above baseline concentrations for at least 9-12 months after infection.     

Intestinal Spirochetosis and Acquired Immunodeficiency Syndrome: Ultrastructural Studies of Two Cases

Two cases of intestinal spirochetosis (IS) with acquired immunodeficiency syndrome are reported. In case 1, a 48-year-old homosexual black man presented with a 1-month history of alternating watery diarrhea and constipation, which dissipated following the removal of two colonic hyperplastic polyps containing IS. In case 2, a 26-year-old homosexual black man presented with a 3-month history of persistent bloody diarrhea and was found to have chronic shigellosis and IS. Pathologic findings of IS were similar in both cases. Basophilic fringes typical of IS covered the surfacing colonic epithelium and consisted of dense growths of spirochetes adherent to and oriented perpendicular to the plasma membranes of the surfacing epithelium. The spirochetes measured 3 to 5 μm in length and 0.2 (im in width, contained four to eight axial fibrils, and closely resembled Brachyspira aalborgi ultrastructurally. These cases are notable because the histopathologic changes of IS were more extensive than generally described. There was involvement of both the right colon and rectum by IS in case 2, and in both cases there was extension of the IS down into the crypts of Lieberkiihn, spirochetal invasion of the colonic mucosa, and a conspicuous inflammatory response by macrophages in the underlying lamina propria.     

Distribution of vasoactive intestinal peptide-sensitive adenylate cyclase activity along the rabbit nephron

The effect of vasoactive intestinal peptide (VIP) upon adenylate cyclase (AC) activity has been determined in defined microdissected renal tubules isolated from collagenase-treated rabbit kidneys. In the presence of 10 M GTP, 1 M VIP gave marked stimulations of AC over basal values in the bright portion of the distal convoluted tubule (DCTb) (10.1-fold), and in the collecting tubule isolated from the inner stripe of the outer medulla (OMCTi, 7.8-fold). Less pronounced effects of VIP were found in the medullary collecting tubule isolated from the outer stripe (2.5-fold) and in the granular portion of the distal convoluted tubule (2.0-fold). VIP stimulation of AC activity in these segments amounted to 25 to 40% of the effect elicited by other agonists (arginine vasopressin, calcitonin or parathyroid hormone) in their respective target segments. A low response to VIP was observed in the cortical thick ascending limb (1.8-fold) which represented less than 5% of the calcitonin-stimulated AC activity. In the thin descending limb VIP produced a slight and variable stimulation of AC. VIP was without effect upon AC in the convoluted and straight portions of the proximal tubule, the medullary thick ascending limb and the cortical collecting tubule. Halfmaximal stimulation of AC by VIP was observed at 26±10 nM (n=3) in OMCTi and at 19 nM (n=2) in DCTb. Related peptides glucagon, secretin and PHI gave lower stimulations of AC compared to VIP in OMCTi. Conversely for rat OMCTi, under identical conditions, glucagon was much more effective than VIP.     

Expression profiles of the duplicated matrix metalloproteinase-9 genes suggest their different roles in apoptosis of larval intestinal epithelial cells during Xenopus laevis metamorphosis.

Matrix metalloproteinases (MMPs) play a pivotal role in development and/or pathogenesis through degrading extracellular matrix (ECM) components. We have previously shown that Xenopus MMP-9 gene is duplicated. To assess possible roles of MMP-9 and MMP-9TH in X. laevis intestinal remodeling, we here analyzed their expression profiles by in situ hybridization and show that their expression is transiently up-regulated during thyroid hormone-dependent metamorphosis. Of interest, MMP-9TH mRNA is strictly localized in the connective tissue and most highly expressed just beneath the larval epithelium that begins to undergo apoptosis. On the other hand, cells expressing MMP-9 mRNA become first detectable in the connective tissue and then, after the start of epithelial apoptosis, also in the larval epithelium. These results strongly suggest that MMP-9TH is responsible in the larval epithelial apoptosis through degrading ECM components in the basal lamina, whereas MMP-9 is involved in the removal of dying epithelial cells during amphibian intestinal remodeling.     

Increased spontaneous secretion of rheumatoid factor by intestinal lamina propria mononuclear cells from Crohn's disease but not ulcerative colitis patients.

Increased levels of rheumatoid factors (RF) have been observed in the serum of Crohn's disease but not ulcerative colitis patients, and have been proposed to relate to an increased state of intestinal lymphocyte activation. We have therefore examined the spontaneous in vitro secretion of RF by intestinal lamina propria mononuclear cells (MNC) isolated from specimens from control and inflammatory bowel disease (Crohn's disease, ulcerative colitis) patients. Normal intestinal lamina propria MNC spontaneously secrete rheumatoid factors of different isotypes during 14 days of in vitro culture (9.7 ng/ml IgA RF, 11.6 ng/ml IgM RF and 64.6 ng/ml IgA anti-Fc (IgG)). In matched studies intestinal MNC isolated from normal large bowel exhibited significantly greater levels of RF synthesis and secretion in vitro than normal small bowel intestinal MNC. A large increase in spontaneous RF secretion was observed from Crohn's disease intestinal MNC (21.4 ng/ml IgA RF, 21.4 ng/ml IgM RF, and 108.15 ng/ml IgA anti-Fc (IgG)), when compared with normal controls. The amount of RF secreted was dependent on the amount of inflammatory activity of the bowel specimens, from which the MNC were isolated (198.3 ng/ml of IgA anti-Fc(IgG) from involved versus 50.0 ng/ml from matched non-involved tissue). Ulcerative colitis MNC released decreased amounts of RF (7.1 ng/ml IgA RF, 6.2 ng/ml IgM RF, and 42.3 ng/ml IgA anti-Fc(IgG)). These observations using isolated intestinal MNC may explain the findings of RF changes in the sera of inflammatory bowel disease patients. Our observations support the hypothesis of a heightened state of activation in normal intestinal lamina propria MNC, which is further increased in active Crohn's disease. The dissimilarities observed between Crohn's disease and ulcerative colitis may indicate fundamental differences in disease pathophysiology and will lead to further studies exploring intestinal immunoregulatory properties of RF.