Serotonin and superior mesenteric artery resistance index

Evaluation of gallbladder contractility and Doppler findings in patients with irritable bowel syndrome; a case-control study

BACKGROUND

Irritable Bowel Syndrome (IBS) is a common gastrointestinal disorder causing abdominal pain, altered bowel habits and bloating without structural issues. Gallbladder dysfunction may be linked to IBS due to disrupted cholecystokinin release. This study aims to assess gallbladder function and related hemodynamic parameters using Doppler ultrasound in IBS before and after meals.

METHOD

In this case-control study, we investigated gallbladder function differences between constipation-predominant IBS (C-IBS) patients and healthy volunteers. Participants underwent ultrasonography to measure gallbladder parameters before and after consuming a predefined meal. Gallbladder volume, wall thickness and resistance index (RI) of cystic and superior mesenteric arteries (SMA) were assessed. Student t-test and paired t-test were used to compare case and control groups and pre- and post-meal data, respectively.

RESULTS

A total of 34 people (18 C-IBS and 16 healthy control) were included. The mean (Standard deviation) of gallbladder fasting volume was measured 24.74 (8.85) and 29.73 (9.65) cubic millimeter for case and controls, respectively. Postprandial volume was 11.34 (5.66) and 16.9 (6.16) cubic millimeter for case and controls respectively. We observed a statistically significant difference in emptying fractions (EF) between groups (p value = 0.009). IBS patients had a smaller fasting SMA RI (p value = 0.016) but the fraction of change after meal was not significant (p value = 0.10). The cystic artery RI did not reach statistical significance between the fasting and post-meal values (p value = 0.067).

CONCLUSION

IBS patients have a higher emptying fraction and lower change in SMA RI compared to healthy controls. Further studies with larger sample size, inclusion of patients with different coexisting conditions and subtypes of IBS and combining colon transit study with gallbladder ejection fraction evaluation can be used to further provide more meaning to this study.

Serotonin, calcitonin and calcitonin gene-related peptide in acute pancreatitis

OBJECTIVE

The aim of this study was to investigate plasma levels of serotonin, calcitonin and calcitonin gene-related peptide (CGRP) in the course of acute pancreatitis (AP) taking organ failure, etiology and severity into consideration.

MATERIAL AND METHODS

Sixty consecutive patients with alcohol- or gallstone-induced AP were included over a 15-month period. Patients were treated according to a standardized algorithm and monitored for organ specific morbidity and mortality. Organ functions and blood samples were assessed on days 0, 1, 2 and 14 after hospital admission. Twenty healthy volunteers, matched for age and gender, comprised the reference group.

RESULTS

Lower levels of serotonin were observed in patients at admission compared to healthy volunteers (p = .021). Serotonin levels increased from day 2 to 14 (p < .001), but with no relation to severity, etiology or organ failure. No difference in calcitonin levels was found in patients at admission compared to healthy volunteers. However, calcitonin levels decreased over time (p < .001) and higher levels were found in patients with respiratory failure (p = .039). No difference was observed in relation to severity or etiology. CGRP levels in patients at admission did not differ from healthy volunteers, nor did CGRP change over time or show any relationship to severity, etiology or organ failure.

CONCLUSION

Our data suggest serotonin and calcitonin levels to be associated to time-course of AP, and calcitonin levels to organ dysfunction. We hypothesize that serotonin plays a pathogenic role in the compromised pancreatic microcirculation, and calcitonin a role as a biomarker of severity in AP.

Zolmitriptan: a novel portal hypotensive agent which synergizes with propranolol in lowering portal pressure

OBJECTIVE

Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol.

METHODS

ZOLMITRIPTAN, PROPRANOLOL OR BOTH WERE TESTED IN TWO RAT MODELS OF PORTAL HYPERTENSION: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan.

RESULTS

In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of β2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by β2-agonists.

CONCLUSION

Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combination therapy deserves consideration for patients with portal hypertension failing to respond to non-selective beta-blockers.

The Measurement of Platelet-Poor Plasma Serotonin: A Systematic Review of Prior Reports and Recommendations for Improved Analysis

BACKGROUND

Recent reports of new and important roles for serotonin (5-hydroxytryptamine, 5-HT) in the periphery have substantially increased interest in measuring peripheral serotonin. Nearly all circulating serotonin is found within platelets and this pool has been assessed by measuring serotonin in whole blood or in platelet-rich plasma. Measurement of the much smaller but potentially critically important pool of human free plasma serotonin in platelet-poor plasma (PPP) has proven much more difficult, with a wide range of reference values reported.

CONTENT

To characterize the available data we carried out a systematic literature search of previous reports of PPP serotonin and attempted to determine the best estimate of true PPP serotonin concentration in humans. A total of 101 published reports that included PPP serotonin values in healthy controls were found and included in the summary statistical analyses. The distribution of PPP serotonin values demonstrated high skewness (+1.98), and the reported values ranged from 0.6 to 179 nmol/L, with a mean of 31.6 nmol/L, an SD of 38.9 nmol/L, and a median of 14.8 nmol/L.

SUMMARY

Reported concentrations for human PPP or free plasma serotonin were highly discrepant, with most reports giving erroneously high values that should be disregarded. Inherent difficulties in selectively measuring the extremely low concentrations of serotonin present in PPP and in preparing PPP without contamination from platelet-derived serotonin contributed to the problem, as did the failure of researchers to compare their results with those from prior studies. There is a clear and pressing need for reference materials for the measurement of plasma (PPP) serotonin.

Are splanchnic hemodynamics related to the development of gastrointestinal symptoms in Ironman triathletes? A prospective cohort study

OBJECTIVE

To determine if prerace to postrace changes in superior mesenteric artery (SMA) and coeliac artery hemodynamics were related to the development of gastrointestinal (GI) symptoms during a triathlon.

DESIGN

Prospective cohort study.

SETTING

Field study at an international Ironman Triathlon.

PARTICIPANTS

Fifty-nine Ironman triathletes of whom 59% (n = 35) reported GI symptoms (GI group) during the race and 41% (n = 24) remained asymptomatic (CON group).

ASSESSMENT OF RISK FACTORS

Prerace questionnaire (personal details, racing and training history, personal general medical history, and medication) and splanchnic hemodynamics.

MAIN OUTCOME MEASURES

Prerace and postrace measurements of splanchnic hemodynamics [artery diameter, systolic velocity, diastolic velocity, and resistive index (RI) of the SMA and coeliac artery] using duplex Doppler ultrasound.

RESULTS

There was a significant decrease in the diameter of the SMA after the race (P = 0.003) and a significant decrease in the RI of the SMA and coeliac artery (P < 0.001) in both the GI and CON groups, but there were no significant differences between the groups. The only significant risk factor for the development of GI symptoms was younger age (P = 0.041). Other risk factors, including high-intensity exercise, poorly trained athlete, and medication use, were not associated with the development of GI symptoms.

CONCLUSIONS

The hypothesis that altered blood flow is related to the development of GI symptoms in endurance athletes is not supported by the results of this study. Other mechanisms for GI symptoms associated with endurance exercise should be investigated.

Hepatic nodular regenerative hyperplasia in a patient with advanced carcinoid tumor

Nodular regenerative hyperplasia (NRH) of the liver is a rare disease that is characterized by multiple regenerative nodules in the hepatic parenchyma that may lead to noncirrhotic portal hypertension. The exact pathogenesis of NRH has not been established, but it has been suggested that a primary vascular abnormality causing local ischemia may initiate the nodular transformation. It is also known that this condition is associated with autoimmune disease, hematological disease, and some chemotherapy agents in which vasculopathy is a prominent feature. The patients with NRH are usually asymptomatic unless they develop complications related to portal hypertension. We report a case of a middle-aged female patient with florid carcinoid syndrome, speculating that vasoactive hormones including serotonin secreted by the tumor caused intrahepatic microcirculatory disturbances that eventually induced NRH. This association has not been reported earlier.