Reappraisal of bicarbonate secretion by the human oesophagus.

BACKGROUND AND AIMS: Administration of omeprazole to healthy volunteers was recently reported to increase proximal duodenal mucosal bicarbonate secretion. As human oesophagus also secretes bicarbonate, the hypothesis was tested that omeprazole may stimulate oesophageal bicarbonate secretion and thus contribute to the therapeutic efficacy of the drug in gastro-oesophageal reflux disease. SUBJECTS AND METHODS: In nine healthy volunteers, oesophageal "steady state" perfusion of a 10 cm open segment of distal oesophagus was performed twice in random order. The volunteers were pretreated with either 60 mg/day omeprazole for three days and 80 mg intravenous omeprazole before perfusion or 600 mg/day ranitidine for three days and 50 mg/h intravenously during the perfusion. Saliva and samples of aspirate from the perfused oesophagus and stomach were collected and bicarbonate concentrations were measured. RESULTS: The median rates (95% confidence intervals) of intrinsic oesophageal bicarbonate secretion, corrected for contaminating salivary and gastric bicarbonate, were 89 (33-150) and 121 (63-203) mumol/h/10 cm (p > 0.5) in omeprazole and ranitidine treated subjects respectively. Salivary and gastric bicarbonate contaminating the oesophagus accounted for 14% and 3%, respectively, of total oesophageal bicarbonate output. CONCLUSIONS: Bicarbonate secretory capacity of the human oesophagus is less than previously assumed, and the clinical relevance of intrinsic oesophageal bicarbonate for mucosal defence may be overestimated. As omeprazole and ranitidine did not affect bicarbonate secretion differently there was no evidence that omeprazole acts on bicarbonate secretory cells in the oesophageal mucosa.     

Transforming growth factor beta1 release by human adipose tissue is enhanced in obesity

The present studies examined the effect of obesity in humans on the release of transforming growth factor beta1 (TGF-beta1) by human adipose tissue. The regulation of TGF-beta1 release by adipose tissue as well as the question of whether its release is due to the adipocytes or the nonfat cells in adipose tissue was also examined. There was a statistically significant (r=0.50) correlation between the body mass index of the fat donors and the subsequent release of TGF-beta1 release by subcutaneous adipose tissue. There was also a positive correlation between total TGF-beta1 release by adipose tissue explants and body fat content (r=0.69). The question of whether tumor necrosis factor alpha (TNF-alpha) and/or interleukin 1 beta (IL-1 beta) regulate the release of TGF-beta1 was investigated by incubation of adipose tissue explants with a soluble human TNF-alpha receptor (etanercept) and a neutralizing antihuman IL-1 beta antibody. The release of TGF-beta1 over 48 hours by adipose tissue explants was significantly enhanced in the presence of both the inhibitor of TNF-alpha and of IL-1 beta. It is of interest, in view of the elevated circulating insulin in blood of morbidly obese women, that the release of TGF-beta1 by adipose tissue was enhanced in the presence of insulin. The question of whether the release of TGF-beta1 by human adipose tissue explants was primarily due to adipocytes, as is the case for leptin, or the nonfat cells present in human adipose tissue, as is the case for IL-8 and prostaglandin E(2), was examined. The release of TGF-beta1 was primarily by the nonfat cells of human adipose tissue because release by adipocytes was less than 10% of that by the nonfat cells of adipose tissue.     

The activity of PPAR gamma in primary human trophoblasts is enhanced by oxidized lipids

The ligand-dependent nuclear receptor PPAR gamma plays an important role in murine and human trophoblast differentiation. Oxidized lipids, which are implicated in the pathophysiology of placental dysfunction, have recently been identified as ligands for PPAR gamma. We therefore hypothesized that oxidized lipids activate PPAR gamma in human trophoblasts and influence placental function. To test our hypothesis, we examined the effect of 9S-hydroxy-10E,12Z-octadecadienoic acid (9-HODE), 13S-hydroxy-9Z,11E-octadecadienoic acid (13-HODE), and 15S-hydroxy-5Z,8Z,11Z,13E-eicosatetraenoic acid (15-HETE) on PPAR gamma activity in cultured term human trophoblasts. Our results demonstrate that these lipids stimulate PPAR gamma activity and that the AF-2 fragment, which harbors the ligand-binding domain of PPAR gamma, mediates this effect. Furthermore, we assessed the consequences of PPAR gamma activation by the oxidized lipids, and we found that these lipids stimulate human CG production, a measure of trophoblast differentiation. In contrast, the expression of syncytin, a marker for syncytium formation as well as the expression of the cell cycle modulators cyclin E and p27 are unchanged by the oxidized lipids. We concluded that 9-HODE, 13-HODE, and 15-HETE activate PPAR gamma in primary human trophoblasts. These PPAR gamma ligands may play a role in placental differentiation, yet they are unlikely to contribute to trophoblast dysfunction.     

Age-dependent and age-independent human memory persistence is enhanced by delayed posttraining methylphenidate administration

Healthy human volunteers 16–82 years of age with at least 10 years of schooling were exposed to two different memory tasks. The first task involved incidental memory. The subjects were asked, as casually as possible: “Did you watch any movie on TV 2 days ago? And 7 days ago? If so, do you remember the title of the movie(s) and the name of the first two actors (actresses)?” Retention scores (maximum = 3: title, actor 1, and actor 2) were equally high (overall mean = 2.6, n = 61) in all age groups (16–20, 21–30, 31–40, 41–60, and 61–82 years) for the day 2 scores. Scores for the movie seen 7 days before decreased significantly and progressively in the three older groups in relation to age, which indicates reduced persistence of this type of memory beginning at the age of 41–50 years and becoming more extensive over the years. The other task was a formal memory procedure. Subjects were asked to study a brief text with factual information on the 1954 World Soccer Cup for 10 min. They were then exposed to 10 questions on the text 2 days and, again, 7 days later. Retention scores declined between the two tests, but in this task, the decline of persistence occurred to a similar extent in all age groups, and thus was not dependent on age. Methylphenidate (10 mg p.o.) given 12 hours after acquisition markedly enhanced persistence of the two memory types. This suggests an involvement of dopaminergic processes in persistence in the late posttraining period.     

Endoscopic fluorescence detection of low and high grade dysplasia in Barrett's oesophagus using systemic or local 5-aminolaevulinic acid sensitisation

BACKGROUND AND AIMS: Barrett's oesophagus is associated with an increased risk of cancer. As dysplasia is not visible during routine endoscopy, random biopsies in the four quadrants every 1-2 cm are recommended. Endoscopic fluorescence detection (EFD) after sensitisation with 5-aminolaevulinic acid (5-ALA) with different modes and concentrations was assessed to optimise the technique for detection of dysplasia or early cancers. 5-ALA is converted intracellularly to protoporphyrin IX which accumulates in malignant tissue and can be detected by typical red fluorescence after illumination with blue light. METHODS: In 47 patients with Barrett's oesophagus, 10 with known dysplasia, 58 fluorescence endoscopies were performed after sensitisation with different concentrations of 5-ALA given orally (5, 10, 20, 30 mg/kg) or locally (500-1000 mg) by spraying the mucosa via a catheter. EFD was performed 4-6 hours after systemic and 1-2 hours after local sensitisation using a special light source delivering white or blue light. A total of 243 biopsies of red fluorescent (n=113) and non-fluorescent areas (n=130) were taken. RESULTS: In three patients, two early cancers and dysplasia, not visible during routine endoscopy, were detected by EFD. Thirty three biopsies revealed either low or high grade dysplasia. Sensitivity for detection of dysplastic lesions ranged from 60% after local sensitisation with 500 mg to 80%, 100%, and 100% after systemic application of 5-ALA 10, 20, and 30 mg/kg, respectively. However, specificity was best for local sensitisation (70%) while systemic administration revealed values between 27% and 56%. Using 5 mg/kg, no red fluorescence in dysplastic lesions was found. No severe side effects were noted. CONCLUSION: EFD is a promising tool to detect non-visible dysplastic lesions in Barrett's oesophagus using 5-ALA sensitisation. A randomised controlled study is now indicated to compare the efficacy of EFD with the standard technique of four quadrant random biopsies.     

Progressive increase in conduction velocity across human mesenchymal stem cells is mediated by enhanced electrical coupling

OBJECTIVE: The purpose of the study was to investigate the development of electrical transmission across human adult bone marrow-derived mesenchymal stem cells (hMSCs) during long-term co-incubation with cardiomyocytes (CMCs). METHODS: Neonatal rat CMCs were cultured in multi-electrode array dishes. A conduction block was induced by creating a central acellular channel, yielding two asynchronously beating CMC fields. Enhanced green fluorescent protein (eGFP)-labeled hMSCs from ischemic heart disease patients (n=8), eGFP-labeled hMSCs having RNA interference-mediated connexin43 (Cx43) knockdown (n=6), 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine (Dil)-labeled CMCs (n=6), or no cells (n=9) were seeded in the channel. Assessment of conduction velocity (CV), Cx expression and localization, gap junctional coupling, and intracellular electrical recordings were performed for up to 14 days. RESULTS: Resynchronization of the two CMC fields occurred within 24 h after seeding of hMSCs. CV across hMSCs increased from 1.4+/-0.4 cm/s at day 7 to 3.5+/-0.1 cm/s (p<0.05) at day 14. CV across seeded CMCs was 16.8+/-0.2 cm/s throughout this period. No resynchronization occurred in the absence of seeded cells. Knockdown of Cx43 in hMSCs abolished conduction across the channel completely. Time-dependent increase of CV across hMSCs was associated with increased Cx43 mRNA and protein expression resulting in increased gap junctional coupling. Intracellular recordings in coupled hMSCs showed increased conducted action potential (AP) amplitude, lower resting membrane potential, and decreased duration of conducted AP (p<0.05, day 14 versus day 1). CONCLUSIONS: CV across hMSCs increases progressively after 7 days of co-incubation with CMCs, most likely via improved electrotonic interaction. This is associated with increased Cx43 expression, increased functional gap junctional coupling, and enhanced intercellular electrical coupling between hMSCs and CMCs.     

Fungal sensitisation in severe asthma is associated with the identification of Aspergillus fumigatus in sputum

Background: Fungal sensitisation is an important factor in severe asthma, not only for allergic bronchopulmonary aspergillosis (ABPA) but also the more recently described severe asthma with fungal sensitisation (SAFS). It is not known whether these diseases are driven by the presence of airway fungal colonisation. We aimed to determine if both SAFS and ABPA were associated with airway isolation of Aspergillus fumigatus and whether the frequency of isolation changed following anti-fungal treatment. Methods: Sputum samples were collected from patients with SAFS, ABPA and a control group without fungal sensitisation. We recorded details of antifungal treatment, serum IgE and A. fumigatus specific IgE levels. In a subgroup (n = 9) we recorded serial sputum PCR measurements before and during itraconazole therapy. Results: 244 sputum samples were provided by 135 patients, 41(17%) ABPA, 168(69%) SAFS, and 35(14%) controls. Sputum Aspergillus fumigatus PCR was positive in 61 SAFS patients (70%) and 6 ABPA patients (50%) not on anti-fungal treatment at the time of the test, compared to 3 (9%) in controls (χ² = 37.90, p < 0.001). Consequently, 19 patients with SAFS who were taking antifungal treatment (23%) were significantly less likely to be PCR positive than the 61 patients not on treatment (70%) (χ² = 36.66, p < 0.001). All 9 patients assessed serially during therapy had positive sputum PCR pre-treatment and all became negative during itraconazole treatment. Conclusion: We have shown that isolation of fungus from the airway of severe asthma patients with fungal sensitisation is very common, supporting the hypothesis of a mechanistic link between fungal colonisation and sensitisation.     

Response of the human oesophagus to d-tubocurarine and atropine

Intraluminal manometric studies of normal swallowing activity fail to distinguish between the peristaltic response of striated and smooth muscle. Studies were performed to determine if the two types of musculature differ in their response to pharmacological stimulation. After the administration of d-tubocurarine, peristaltic amplitude in the striated muscle segment decreased by 26 to 51%, while amplitude in the smooth muscle portion was not significantly affected. The administration of atropine, on the other hand, abolished or diminished smooth muscle peristalsis without altering striated muscle activity. The injection of neostigmine restored peristaltic amplitude toward normal in both striated and smooth muscle portions. These studies demonstrate that although the striated and smooth muscle segments are indistinguishable during normal oesophageal peristalsis, they do differ markedly in their pharmacological response. Pharmacologically, oesophageal striated muscle responds like other striated muscle and oesophageal smooth muscle responds like smooth muscle elsewhere.     

Storage mite sensitisation is associated with early life village residence in Turkey

BackgroundStorage mites (SMs) occur in house-dust and the rate of sensitisation to them is high. We aimed to investigate if past and current living conditions are associated with the risk of SM sensitisation.MethodsIn total, 321 patients (70% females) aged 33.6 ± 11.9 years (range: 14–68 years) were studied at our allergy unit between September 2009 and December 2010. Patients with persistent or intermittent rhinitis and/or asthma were included in the study. Skin prick tests (SPTs) for SMs (Lepidoglyphus destructor, Tyrophagus putrescentiae, and Acarus siro) and other common aeroallergens were performed. Demographic data and characteristics of the patients’ homes were assessed via a questionnaire.ResultsIn all, 102 (31.8%) patients were sensitised to ≥1 SM, of whom 43.1% were also sensitised to Dermatophagoides pteronyssinus. Comparison between the SPT-negative group (n = 129) and the SM-positive only group (n = 33) showed that having lived in a village during the first years of life was associated with SM sensitisation. Current place of residence was not significantly associated with any of the study variables.ConclusionsLiving conditions have been changing and SM sensitisation may be associated with a history of village residence. The high rate of SM sensitisation observed in the study population might indicate the necessity of including those mite species in SPT panels, but the clinical relevance of sensitisation remains unclear. The clinical importance of SM sensitisation in urban areas should be investigated further.     

Nitrinergic and peptidergic innervation of the human oesophagus.

The distribution, colocalisation, and interconnections of nitrinergic and peptidergic neurons and nerves in the human oesophagus were examined. Cryosections of surgically resected tissues from eight subjects were studied with indirect immunofluorescence for the presence of 11 neuropeptides and neuron specific enolase. After immunohistochemistry, nitric oxide synthase was shown on the same sections with the beta nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemical reaction. The histochemical findings were verified immunohistochemically on other sections with an antiserum against nitric oxide synthase. Most myenteric neurons (55%) were nitrinergic. Most (96%) received terminations positive for vasoactive intestinal polypeptide (VIP), calcitonin gene related peptide (CGRP) (80%), and galanin (59%). The neuronal somata of 14% also contained VIP, while 10% had galanin. Of the NADPH-diaphorase containing fibers seen in the muscle layers, many had closely associated VIP and galanin, but only rarely CGRP and substance P. Thus, despite abundant representation of both peptidergic and nitrinergic systems in oesophageal smooth muscle, only VIP and galanin colocalised to any significant extent with the nitrinergic elements. These findings provide morphological support for the role of nitric oxide as the non-adrenergic non-cholinergic inhibitory mediator in the human oesophagus and for its possible interactive role with the peptidergic system.     

Monocyte-mediated killing of human leukaemia is enhanced by administration of granulocyte-macrophage colony stimulating factor following chemotherapy

We studied the capacity of recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) to modulate monocyte anti-leukaemic activity when administered to patients following myelosuppressive chemotherapy. The leukaemic cell lines K562, U937 and KG-1 were used as models of human leukaemia as they exhibit differential sensitivity to cell-mediated or TNF-mediated cytotoxicity. Monocyte tumouricidal activity was augmented by rhGM-CSF or lipopolysaccharide (LPS) alone in vitro against leukaemic blasts, whereas granulocyte-colony stimulating factor (rhG-CSF) was without effect. rhGM-CSF and LPS exhibited an additive effect in stimulating the cytotoxic effect of monocytes against K562 blasts compared with either agent alone ( P  < 0.001). Both cell-mediated and soluble TNF-mediated killing of leukaemic blasts was augmented by rhGM-CSF administration to patients following chemotherapy. This effect persisted for up to 4 weeks after cessation of GM-CSF therapy. The administration of rhGM-CSF significantly increased the anti-leukaemic activity of monocytes against leukaemic targets that were resistant to secreted TNF, probably via a transmembrane TNF-dependent mechanism. Therapy with rhG-CSF exhibited a minimal effect. We conclude that administration of rhGM-CSF, but not rhG-CSF, augments the tumouricidal properties of the monocyte-macrophage system, particularly during recovery from myelosuppressive chemotherapy. Moreover, the killing mechanism is direct and not mediated by an antibody-dependent cellular cytotoxic (ADCC) mechanism. Killing of TNF-resistant leukaemic cells in particular may be augmented via cell-to-cell contact.     

Measurement of bicarbonate output from the intact human oesophagus.

Injury of the oesophageal mucosa can result from exposure to refluxed gastric acid and pepsin. Competence of the lower oesophageal sphincter and peristaltic activity serve to reduce contract time between luminal acid and oesophageal mucosa, but intraluminal neutralisation of residual acid by bicarbonate may also be important in preventing oesophageal mucosal injury. Whereas swallowed saliva contains bicarbonate, recent experiments have also demonstrated alkali secretion from the mammalian oesophagus. Bicarbonate secretion from the human oesophagus was therefore examined with an intubation technique and perfusion of the oesophagus with a non-absorbable marker. Saliva, gastric, and oesophageal aspirates were collected and bicarbonate concentrations determined by measurements of pH and pCO2 or by back titration. In 32 normal subjects (17 women, 15 men) median basal oesophageal bicarbonate secretion determined by a pH/pCO2 method was 416 (range 139-1050) mumol/hour/10 cm. In a subgroup of 15 experiments median oesophageal bicarbonate output was 489 (range 157-1033) mumol/hour/10 cm (pH/pCO2 method) compared with a median alkali output of 563 (range 135-799) mumol/hour/10 cm as determined by back titration. The difference was not significant. Salivary contamination of the oesophagus accounted for 25% of all bicarbonate measured within the oesophagus and refluxed gastric bicarbonate accounted for 2.5%. Bicarbonate secretion from the normal human oesophagus may, in combination with swallowed salivary bicarbonate, play a part in preventing oesophageal mucosal damage due to refluxed gastric acid and pepsin.     

Presence of bile in the oesophagus is associated with less effective oesophageal motility

BACKGROUND/AIMS: Reflux of bile to the oesophagus has been shown to be of importance in the development of gastro-oesophageal reflux disease. This study aims to assess oesophageal motility patterns in relation to acid and bile reflux to the oesophagus. METHODS: Forty-nine subjects with and without reflux disease underwent 24-hour ambulatory recordings of oesophageal pH, bile and 3-channel manometry. Gastroscopy was performed to assess severity of oesophagitis. The percentage of effective peristaltic contractions (oesophageal contractions with a peristaltic pattern and a pressure >30 mm Hg) were correlated to the degree of acid and bile reflux. Ten subjects were re-evaluated within 2 years post-fundoplication. RESULTS: Acid and bile reflux were associated with fewer effective contractions (R(2) = 0.07, p = 0.06 and R(2) = 0.21, p = 0.008, respectively). However, in a multivariate model including acid, bile, age and gender dependency, only bile could show a systematic effect on the variation in percentage of effective peristaltic contractions (R(2) = 0.22, p = 0.001). One year after laparoscopic fundoplication, 24-hour oesophageal motility was unchanged. CONCLUSION: Reflux of duodenal juice to the oesophagus is associated with less effective oesophageal motility, which in turn can perpetuate the disease by less effective oesophageal clearance of bile and acid. The reduced oesophageal motility is not reversed by fundoplication.