Spontaneous and α-adrenoceptor-induced contractility in human collecting lymphatic vessels require chloride.

Human lymphatic vessels are myogenically active and respond to sympathetic stimulation. The role of various cations in this behavior has recently been investigated, but whether the anion Cl- is essential is unclear. With ethical approval and informed consent, human thoracic duct and mesenteric lymphatic vessels were obtained from surgical patients. Spontaneous or norepinephrine-induced isometric force production from isolated vessels was measured by wire myography; the transmembrane Cl- gradient and Cl- channels were investigated by substitution of extracellular Cl- with the impermeant anion aspartate and inhibition of Cl- transport and channels with the clinical diuretics furosemide and bendroflumethiazide as well as DIDS and 5-nitro-2-(3-phenylpropylamino)benzoic acid. The molecular expression of Ca2+-activated Cl- channels was investigated by RT-PCR, and proteins were localized using immunoreactivity. Spontaneous and norepinephrine-induced contractility in human lymphatic vessels was highly abrogated after Cl- substitution with aspartate. About 100-300 µM DIDS or 5-nitro-2-(3-phenylpropylamino)benzoic acid inhibited spontaneous contractile behavior. Norepinephrine-stimulated tone was furthermore markedly abrogated by 200 µM DIDS. Furosemide lowered only spontaneous constrictions, whereas bendroflumethiazide had nonspecific inhibitory effects. Consistent expression of transmembrane member 16A [TMEM16A (anoctamin-1)] was found in both the thoracic duct and mesenteric lymphatic vessels, and immunoreactivity with different antibodies localized TMEM16A to lymphatic smooth muscle cells and interstitial cells. The significant change in contractile function observed with inhibitors and anion substitution suggests that Cl- movement over the plasma membrane of lymphatic myocytes is integral for spontaneous and α-adrenoceptor-evoked contractility in human collecting lymphatic vessels. Consistent detection and localization of TMEM16A to myocytes suggests that this channel could play a major functional role. NEW & NOTEWORTHY In this study, we report the first observations of Cl- being a critical ionic component of spontaneous and agonist-evoked contractility in human lymphatics. The most consistently expressed Ca2+-activated Cl- channel gene in the human thoracic duct and mesenteric lymphatic vessels appears to be transmembrane member 16A, suggesting that this channel plays a major role.

Voltage-gated sodium channels contribute to action potentials and spontaneous contractility in isolated human lymphatic vessels.

Voltage-gated sodium channels (VGSC) play a key role for initiating action potentials (AP) in excitable cells. VGSC in human lymphatic vessels have not been investigated. In the present study, we report the electrical activity and APs of small human lymphatic collecting vessels, as well as mRNA expression and function of VGSC in small and large human lymphatic vessels. The VGSC blocker TTX inhibited spontaneous contractions in six of 10 spontaneously active vessels, whereas ranolazine, which has a narrower VGSC blocking profile, had no influence on spontaneous activity. TTX did not affect noradrenaline-induced contractions. The VGSC opener veratridine induced contractions in a concentration-dependent manner (0.1-30 µm) eliciting a stable tonic contraction and membrane depolarization to -18 ± 0.6 mV. Veratridine-induced depolarizations and contractions were reversed ∼80% by TTX, and were dependent on Ca(2+) influx via L-type calcium channels and the sodium-calcium exchanger in reverse mode. Molecular analysis determined NaV 1.3 to be the predominantly expressed VGSC isoform. Electrophysiology of mesenteric lymphatics determined the resting membrane potential to be -45 ± 1.7 mV. Spontaneous APs were preceded by a slow depolarization of 5.3 ± 0.6 mV after which a spike was elicited that almost completely repolarized before immediately depolarizing again to plateau. Vessels transiently hyperpolarized prior to returning to the resting membrane potential. TTX application blocked APs. We have shown that VGSC are necessary for initiating and maintaining APs and spontaneous contractions in human lymphatic vessels and our data suggest the main contribution from comes NaV 1.3. We have also shown that activation of these channels augments the contractile activity of the vessels.

Human lymphatic vessel contractile activity is inhibited in vitro but not in vivo by the calcium channel blocker nifedipine.

Calcium channel blockers (CCB) are widely prescribed anti-hypertensive agents. The commonest side-effect, peripheral oedema, is attributed to a larger arterial than venous dilatation causing increased fluid filtration. Whether CCB treatment is detrimental to human lymphatic vessel function and thereby exacerbates oedema formation is unknown. We observed that spontaneous lymphatic contractions in isolated human vessels (thoracic duct and mesenteric lymphatics) maintained under isometric conditions were inhibited by therapeutic concentrations (nanomolar) of the CCB nifedipine while higher than therapeutic concentrations of verapamil (micromolar) were necessary to inhibit activity. Nifedipine also inhibited spontaneous action potentials measured by sharp microelectrodes. Furthermore, noradrenaline did not elicit normal increases in lymphatic vessel tone when maximal constriction was reduced to 29.4 ± 4.9% of control in the presence of 20 nmol l(-1) nifedipine. Transcripts for the L-type calcium channel gene CACNA1C were consistently detected from human thoracic duct samples examined and the CaV1.2 protein was localized by immunoreactivity to lymphatic smooth muscle cells. While human lymphatics ex vivo were highly sensitive to nifedipine, this was not apparent in vivo when nifedipine was compared to placebo in a randomized, double-blinded clinical trial: conversely, lymphatic vessel contraction frequency was increased and refill time was faster despite all subjects achieving target nifedipine plasma concentrations. We conclude that human lymphatic vessels are highly sensitive to nifedipine in vitro but that care must be taken when extrapolating in vitro observations of lymphatic vessel function to the clinical situation, as similar changes in lymphatic function were not evident in our clinical trial comparing nifedipine treatment to placebo.

The contribution of K(+) channels to human thoracic duct contractility.

In smooth muscle cells, K(+) permeability is high, and this highly influences the resting membrane potential. Lymph propulsion is dependent on phasic contractions generated by smooth muscle cells of lymphatic vessels, and it is likely that K(+) channels play a critical role in regulating contractility in this tissue. The aim of this study was to investigate the contribution of distinct K(+) channels to human lymphatic vessel contractility. Thoracic ducts were harvested from 43 patients and mounted in a wire myograph for isometric force measurements or membrane potential recordings with an intracellular microelectrode. Using K(+) channel blockers and activators, we demonstrate a functional contribution to human lymphatic vessel contractility from all the major classes of K(+) channels [ATP-sensitive K(+) (KATP), Ca(2+)-activated K(+), inward rectifier K(+), and voltage-dependent K(+) channels], and this was confirmed at the mRNA level. Contraction amplitude, frequency, and baseline tension were altered depending on which channel was blocked or activated. Microelectrode impalements of lymphatic vessels determined an average resting membrane potential of -43.1 ± 3.7 mV. We observed that membrane potential changes of <5 mV could have large functional effects with contraction frequencies increasing threefold. In general, KATP channels appeared to be constitutively open since incubation with glibenclamide increased contraction frequency in spontaneously active vessels and depolarized and initiated contractions in previously quiescent vessels. The largest change in membrane voltage was observed with the KATP opener pinacidil, which caused 24 ± 3 mV hyperpolarization. We conclude that K(+) channels are important modulators of human lymphatic contractility.

Comparable Effects of Sleeve Gastrectomy and Roux-en-Y Gastric Bypass on Basal Fuel Metabolism and Insulin Sensitivity in Individuals with Obesity and Type 2 Diabetes.

Aim: Bariatric surgery improves insulin sensitivity and glucose tolerance in obese individuals with type 2 diabetes (T2D), but there is a lack of data comparing the underlying metabolic mechanisms after the 2 most common surgical procedures Roux-en-Y gastric bypass surgery (RYGB) and sleeve gastrectomy (SG). This study was designed to assess and compare the effects of RYGB and SG on fuel metabolism in the basal state and insulin sensitivity during a two-step euglycemic glucose clamp. Materials and Methods: 16 obese individuals with T2D undergoing either RYGB (n = 9) or SG (n = 7) were investigated before and 2 months after surgery, and 8 healthy individuals without obesity and T2D served as controls. All underwent a 2 h basal study followed by a 5 h 2-step hyperinsulinemic euglycemic glucose clamp at insulin infusion rates of 0.5 and 1.0 mU/kg LBM/min. Results: RYGB and SG induced comparable 15% weight losses, normalized HbA1c, fasting glucose, fasting insulin, and decreased energy expenditure. In parallel, we recorded similar increments (about 100%) in overall insulin sensitivity (M-value) and glucose disposal and similar decrements (about 50%) in endogenous glucose production and FFA levels during the clamp; likewise, basal glucose and insulin concentrations decreased proportionally. Conclusion: Our data suggest that RYGB and SG improve basal fuel metabolism and two-step insulin sensitivity in the liver, muscle, and fat and seem equally favourable when investigated 2 months after surgery. This trial is registered with NCT02713555.

Reconstruction using free jejunal transfer after resection of cancer of the upper oesophagus.

INTRODUCTION: Treatment of cancer of the upper part of the oesophagus is challenging. Even after intended curative treatment, less than half of the patients are alive after five years. This retrospective study evaluates all the patients who had the upper oesophagus reconstructed by use of a free jejunal transfer following cancer resection from February 2000 to May 2008 at the University Hospital of Aarhus. MATERIAL AND METHODS: Twenty patients aged 46-75 years were included. In all 20 cases, the diagnosis was squamous cell carcinoma, T3 or T4. All patients suffered from severe dysphagia prior to surgery. The median follow-up time was 23 months at 31 January 2010. RESULTS: No perioperative mortality was experienced. Thirteen patients are now dead; nine due to the cancer of the oesophagus and four due to other causes. The median survival time of the 13 diseased patients was 15.3 months. The seven patients who remain alive have a median survival time of 40.2 months. None of these patients have shown signs of recurrence of the oesophageal cancer. All the patients regained their capacity to swallow and thereby increased their quality of life. No complications were experienced in relation to the abdominal procedure of harvesting the jejunal transfer. Three patients developed a fistula and in one case this required minor surgery. Eight patients needed to have a dilatation procedure performed. CONCLUSION: Reconstruction of the oesophagus with a free jejunal transfer is a suitable treatment for selected patients with cancer in the upper oesophagus.

[Overweight and gastro-oesophageal reflux disease].

The increase in the prevalence of obesity is paralleled by an increase in gastro-oesophageal reflux disease (GERD), and several mechanisms link GERD and obesity, so weight loss is a cornerstone in the treatment of GERD. Sustained weight loss often requires surgery, and fundoplication is the first surgical choice among normal weight patients with reflux; however, reflux complications increase with increasing BMI. Therefore, patients with obesity and GERD should be treated with gastric bypass surgery. The aim of this article is to discuss the relationship between overweight and GERD and outline treatment options of this disease.

[Acute abdominal vasculitis in rheumatic diseases].

Mesenteric vasculitis is the most common abdominal manifestation of vasculitis and can present as acute abdominal pain. Mesenteric vasculitis is most frequent in systemic lupus erythematosus and polyarteritis nodosa in adulthood and immunoglobulin A-vasculitis in childhood. Involvement of other organs is also seen. The diagnosis can be challenging, but detailed clinical assessment in combination with diagnostic tests often identifies the underlying cause. Medical treatment is used, when the abdominal manifestation is considered reversible, while surgery is used in unstable patients or patients with non-reversible conditions.

[Radiology diagnostics and treatment of acute cholecystitis].

Acute cholecystitis (AC) is mainly caused by stones in the gall bladder. Although cholescintigraphy has the highest sensitivity (97%) and specificity (94%) for AC, ultrasound is the most commonly used technique in confirming the diagnosis. Laparoscopic cholecystectomy is the recom-mended treatment of choice; however, in high-risk patients percutaneous gall bladder drainage is an attractive alter-native approach to avoid lesions to the common bile duct. To avoid serious bleeding incidences, it is imperative to pause anticoagulation therapy prior to gall bladder drainage.

Spontaneous and Evoked Contractility of Human Intestinal Lymphatic Vessels.

BACKGROUND: Mesenteric lymphatic vessels (MLVs) from various animal species have been intensively studied. We aimed to establish the viability and basic contractile characteristics of human MLVs maintained in vitro and to determine the reactivity of MLVs with norepinephrine (NE) and substance P (SP) and to compare with the thoracic duct (TD). METHODS AND RESULTS: Isolated human lymphatic vessels were mounted on a wire myograph under isometric conditions and tension was recorded. The diameter-tension characteristics for MLVs were generated by stretching the vessels and stimulating with a 125 mM K+ solution containing 10 µM NE. The diameter-tension data generated for MLVs from two separate surgical patient groups were found to be similar: maximum active tension for MLVs occurred when the passive stretch corresponded to a transmural pressure of 22 mmHg. Subsequent experiments on human MLVs were performed by normalization with 22 mmHg as the equivalent target pressure. The majority of MLVs were responders (spontaneous activity and/or reactivity with 10 µM NE or 125 mM K+ solution). Nonresponders (16% of vessel segments) had significantly smaller inner diameters. MLVs responded consistently to NE (1 nM-10 µM) but the responsiveness of MLVs and TD to SP (0.1 nM-10 µM) was poor: TD reacted only with 10 µM SP, whereas MLVs were sensitive to nanomolar concentrations and the contractile response declined with higher concentrations. CONCLUSIONS: Under in vitro isometric conditions, human MLVs generate maximum tension when stretched to a passive level corresponding to 22 mmHg, and the majority of MLVs are responsive when normalized to this pressure. MLVs respond to NE and SP though NE produces a more consistent response in the concentration range tested.

Laparoscopic minimally invasive total gastrectomy with linear stapled oesophagojejunostomy--experience from the first thirty procedures.

BACKGROUND: There are only few reports on total gastrectomy by a laparoscopic surgical approach. One explanation is the fear of complications due to anastomotic dehiscence in oesophagojejunal anastomosis known to carry high morbidity and mortality. The introduction of staplers have contributed to making anastomosis safer and easier to perform and has facilitated more advanced laparoscopic surgery. In open surgery, most surgeons use a circular stapler for oesophagojejunal anastomosis or a hand sutured technique. Both techniques are difficult to use in laparoscopic surgery, especially if the oesophagus is narrow. To facilitate the creation of oesophagojejunal anastomoses, we have adopted a technique with a linear stapled anastomosis. Our method is based on a stapling technique where the oesophagus is divided above the gastric cardia followed by a oesophagojejunostomy performed with Covidien's new Endo GIA-60™ Ultra Universal stapler. The residual opening is closed with a 3-0 re-absorbable suture. PATIENTS AND METHODS: From June 2009 to May 2012, 14 men and 16 women (median age=66 years, range=39-84 years) underwent laparoscopic total gastrectomy due to gastric cancer. RESULTS: One patient died during hospital stay; corresponding to a postoperative mortality of 3,3%. Leakage in the oesophagojejunal anastomosis occurred in three patients (10%). Two of the patients with leakage in the oesophagojejunal anastomosis had an additional duodenal bulb leakage, which might have caused anastomotic dehiscence. The patients had a median postoperative hospital stay of six days (range=3-156 days). Six patients had a re-operation due to complications, including one endoscopic stent application in the anastomosis. CONCLUSION: Even though a leakage rate of 10% can be considered high, this study describes a simple method for performing oesophagojejunostomy after gastrectomy by a laparoscopic approach independently of the width of the oesophagus. This study also shows that laparoscopic gastrectomy can be performed in more advanced stages of gastric cancer.

[Large fibrovascular polyp in the oesophagus]. / Stor fibrovaskulær polyp i øsofagus.

We describe a 45 year-old man with a fibrovascular polyp attached to the entrance of the oesophagus. The patient had a history with regurgitation of polypose foreign body 4-5 years ago with spontaneous remission. Later the patient developed dysphagia, chest pain and weight loss. Gastroscopy revealed a large polyp in the oesophagus and biopsies showed no malignancy. Excision was intended to be performed endoscopically, but due to size, risk of bleeding and recurrence the operation was changed to a transcervical procedure. After one week the patient could eat and drink normally.