Áron Vincze

Growth factors in ulcer healing: lessons from recent studies.

Growth factors such as epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and more recently vascular endothelial growth factor (VEGF) have been used extensively to heal experimental gastric, duodenal and colonic ulcers in animal models. Encouraging results have been reported in clinical trials with EGF and bFGF. Since our laboratory has been involved with the initial ulcer healing studies with bFGF, PDGF and VEGF, we summarize here the major lessons from these studies and from literature data. These conclusions relate to the role of: 1) gastrointestinal (GI) secretion; 2) epithelial versus vascular components of the healing; 3) efficacy in the upper and lower GI tract; 4) quality of ulcer healing; as well as 5) the endogenous origin; and 6) molar potency of growth factors. Namely, among these growth factors only EGF inhibits gastric acid and stimulates duodenal bicarbonate secretion, while chronic administration of bFGF slightly enhances gastric secretion and PDGF has no effect demonstrating that potent ulcer healing can be achieved without influencing acid base and mucus secretion. This might be related to the fact that these growth factors stimulate with varying potency virtually all the cellular elements needed for ulcer healing, e.g., epithelial cell proliferation and migration by EGF > bFGF > PDGF, fibroblast proliferation by bFGF > PDGF and angiogenesis by VEGF > bFGF >> PDGF >> EGF. Conceptually, the most interesting results were obtained recently with VEGF which is virtually specific for angiogenesis, illustrating that stimulation of vascular factors is sufficient for ulcer healing because epithelial cells apparently spontaneously proliferate and migrate over a dense granulation tissue to complete the healing process. Since these growth factors directly stimulate the cell components of ulcer healing, it is probably not surprising that they are active in both upper and lower GI tract lesions, produce good quality of ulcer healing in comparison with spontaneously healed duodenal ulcers which are hypovascular and muscle regeneration is not part of natural healing. Contrary to other antiulcer drugs, these growth factors are endogenously derived and play a role in the natural history of ulcer healing, and since these relatively large peptides (18-45 kDa) are active in ng quantities, their molar potency is 2-7 million times superior to cimetidine-like drugs. Thus growth factors are endogenously derived very potent antiulcer drugs which act independently of GI secretion, are active in upper and lower GI lesions, and since they stimulate virtually all the cells of the healing process, they produce an excellent quality of ulcer healing.

Decrease of serum carotenoids in Crohn's disease

Crohns disease (CD) is frequently complicated by various nutritional disturbances. Although it is important to correct these disturbances, the nutritional status of CD patients has been poorly documented, especially concerning vitamin status. The aims of this study were (a) to measure the serum concentrations of vitamin A and six other carotenoids (lutein, zeaxanthin, alpha-, beta-carotene, alpha-, beta-cryptoxanthin) in patients with CD and to compare them with those in healthy controls and (b) to follow the changes of serum carotenoid levels in CD patients during treatment. Twenty-eight patients with CD and 23 healthy persons were included in this study. The results of twelve patients were followed up through one year. The patients were free of any nutritional treatment. The serum concentrations of carotenoids were measured with high-pressure liquid chromatography (HPLC). The serum concentrations of five carotenoids were significantly lower in the patients than in the controls (vitamin A, zeaxanthin: P < 0.001; alpha-, beta-carotene: P < 0.01; lutein: P < 0.05). The carotenoid status of the followed patients advanced to the normal range, but this increase was not significant. These findings suggest that there is a deficiency of vitamin A and its provitamins in Crohn s disease prior to treatment. However, because we did not evaluate the vitamin intake in this study, we could not conclude which of the factors--poor intake, increased requirement, or malabsorption--was more important in decreasing of carotenoid levels.

Four response stages of capsaicin-sensitive primary afferent neurons to capsaicin and its analog: gastric acid secretion, gastric mucosal damage and protection.

Abstract Capsaicin is the active component of red hot peppers, which modifies specifically the capsaicin‐sensitive sensory afferent nerves. The action of capsaicin is an initial short‐lasting stimulation, which is followed by desensitization to capsaicin itself, and to other stimuli of afferent sensory nerves. Four response stages of capsaicin‐sensitive primary afferents exist to capsaicin, depending on the dose and duration of exposure to the drug. These are excitation, a sensory blocking effect, long‐term selective neurotoxic impairment, and irreversible cell destruction. The possible roles of four stages of capsaicin‐sensitive primary afferents can be evaluated in relation to gastric acid secretion, and to the details of the defensive side of gastric mucosa against different chemicals, physical agents, drugs and other pathological stress. Capsaicin inhibited the gastric acid secretion in pylorus‐ligated rats when it was given intragastrically at a dose of 0.4–1.8 μg/kg. Small doses of capsaicin (up to 800 μg, i.g.) produced a dose‐dependent inhibition (ID50 = 400 μg), and its inhibitory effect was exerted for 1 h in healthy human subjects. While a small dose (5 μg/kg) of capsaicin caused inhibition, a high dose (50–100 mg/kg) enhanced the gastric mucosal lesions productivity by causing hyperacidity in pylorus‐ligated animals. Capsaicin and its analog inhibited the development of different chemically induced gastric mucosal damage in various experimental models if they were given intragastric doses (μg/kg). The final effects of capsaicin depend on the dosage and timing. The different effects are excitation, a sensory‐blocking effect, long‐term selective neurotoxic impairment and irreversible cell destruction.

Mechanisms of action of retinoids in gastrointestinal mucosal protection in animals, human healthy subjects and patients

UNLABELLEDnRetinoids prevent chemically induced gastric mucosal damage without inhibiting gastric acid secretion (nutritional gastric cytoprotection). The gastroprotective effects of retinoids do not depend on 1) vitamin A activity; 2) number of unsaturated double bonds; 3) the presence of a characteristic chemical structure of their terminal components; however, they depend on 1) intact vagal nerve and 2) adrenals in experimental animals. The gastric cytoprotective effect of retinoids produces a dose-dependent inhibition of ATP-transformation into ADP. It also increases the transformation of ATP into cAMP. Other features of these gastric cytoprotective effects of retinoids include: 1) The retinoid-induced gastric mucosal protection differs from that of PGs; 2) The cAMP is an intracellular signal in the development of gastric mucosal damage produced by chemicals (e.g., ethanol, HCl, indomethacin) and in the protection of gastric mucosa induced by retinoids (but not by PGs); 3) The gastric mucosal protection induced by retinoids and gastric mucosal permeability can be separated in time. The existence of gastric mucosal protection can be demonstrated in healthy persons (against indomethacin treatment), in patients with gastric ulcer (GU) and duodenal ulcer (DU) without any inhibition of gastric acid secretion. The serum levels of vitamin A and zeaxanthin were significantly decreased in patients with chronic gastrointestinal (GI) inflammatory diseases (e.g., terminal ileitis, ulcerative colitis), colorectal polyposis, and different (e.g., esophageal, gastric, pancreatic, hepatocellular and colorectal) malignant diseases. The serum levels of vitamin A provitamins were unchanged and their GI mucosal protective effects do not depend on vitamin A activity.nnnCONCLUSIONSn1) Abundant experimental and human observations clearly proved the defensive role of retinoids in the GI tract; 2) There is a correlation between the a) scavenger properties of retinoids vs. intact vagal nerve; b) scavenging properties vs. intact adrenals. 3) The GI mucosal protective effect of retinoids is correlated with biochemical changes in the GI mucosa.

13C-Urea breath test is superior in sensitivity to detect Helicobacter pylori infection than either antral histology or rapid urease test.

There is no single technique which fulfils the criterion for a reference method to detect Helicobacter pylori (Hp) infection. The aim was to compare the results of antral histology (H), rapid urease test (U) and urea breath test (UBT) from antral biopsy samples in patients having gastric or duodenal lesions during upper GI endoscopy. We used the following methods: 1) biopsy specimens for histology (Warthin-Starry staining); 2) rapid urease test; and 3) 13C-urea breath test with infrared spectrometry. The total number of patients was 166 examined by H, U, and UBT. H, U and UBT were negative (-) in 64 patients and positive (+) in 51. The true positivity and false negativity (%, number of patients in parentheses) of each method based upon the positivity of the other two tests were: H+, U+ (54): UBT+, 94.4% (51) and UBT-, 5.6% (3); H+, UBT+ (57): U+, 89.5% (51) and U-, 10.5% (6); U+, UBT+ (65): H+, 78.5% (51) and H-, 21.5% (14). If Hp infection is considered to be positive when at least two tests detect the presence of Hp, UBT shows the highest sensitivity in comparison to histology of biopsy specimens and urease test. UBT is highly recommended as a screening test for Hp infection in patients presenting upper GI endoscopic alterations.

Radiation-induced enterocolitis: Basic and applied science

We adapted and introduced in our laboratory a simplified animal model of radiation-induced enterocolitis. After a shielding of the parenchymatous organs, our dose-response studies revealed that 20 Gy x-ray radiation resulted in about 20% mortality and reproducible lesions in the terminal ileum and proximal colon. These changes are optimal for pharmacologic studies since they may be decreased or aggravated by drugs. Sucralfate dose-dependently decreased the clinical signs of enterocolitis (e.g., lethargy, diarrhea) as well as the number and area of ileal and colonic erosions and ulcers. The wet weight of the ileum and colon were also decreased by sucralfate. bFGF at the small doses used exerted a beneficial effect only on a few of the parameters of enterocolitis. Thus sucralfate, and maybe bFGF, might decrease the severity and accelerate the healing of radiation-induced enterocolitis.

Angiogenesis and Growth Factors in Ulcer Healing

Angiogenesis, i.e., endothelial-cell proliferation and tube formation in postembryonic tissue, is a crucial element in granulation tissue production. The formation of granulation tissue, i.e., angiogenesis followed by proliferation of fibroblasts and deposition of collagen, on the other hand, is a rate-limiting step in the repair of major tissue injury (e.g., after the loss of cardiac or smooth muscle). Only in certain organs such as the liver, adrenal and renal cortex, the regeneration involves the proliferation of original parenchymal cells that fast replace the lost tissue.

Meta-analysis of the long term success rate of different interventions in benign biliary strictures

Background Benign biliary stricture is a rare condition and the majority of the cases are caused by operative trauma or chronic inflammation based on various etiology. Although the initial results of endoscopic, percutaneous and surgical treatment are impressive, no comparison about long term stricture resolution is available. Aims The goal of this study was to compare the long term disease free survival in benign biliary strictures with various etiology after surgery, percutaneous transhepatic—and endoscopic treatment. Methods PubMed, Embase, and Cochrane Library were searched by computer and manually for published studies. The investigators selected the publications according to the inclusion and exclusion criteria, processed the data and assessed the quality of the selected studies. Meta-analysis of data of 24 publications was performed to compare long term disease free survival of different treatment groups. Results Compared the subgroups surgery resulted in the highest long term stricture resolution rate, followed by the percutaneous transhepatic treatment, the multiple plastic stent insertion and covered self-expanding metal stents (SEMS), however the difference was not significant. All compared methods are significantly superior to the single plastic stent placement. Long term stricture resolution rate irrespectively of any therapy is still not more than 84%. Conclusions In summary, the use of single plastic stent is not recommended. Further randomized studies and innovative technical development are required for improving the treatment of benign biliary strictures.

Pancreatic Cancer: Multicenter Prospective Data Collection and Analysis by the Hungarian Pancreatic Study Group.

BACKGROUND AND AIMSnPancreatic cancer is a devastating disease with poor prognosis. There is very limited information available regarding the epidemiology and treatment strategies of pancreatic cancer in Central Europe. The purpose of the study was to prospectively collect and analyze data of pancreatic cancer in the Hungarian population.nnnMETHODSnThe Hungarian Pancreatic Study Group (HPSG) organized prospective, uniform data collection. Altogether 354 patients were enrolled from 14 Hungarian centers.nnnRESULTSnChronic pancreatitis was present in 3.7% of the cases, while 33.7% of the patients had diabetes. Family history for pancreatic cancer was positive in 4.8%. The most frequent presenting symptoms included pain (63.8%), weight loss (63%) and jaundice (52.5%). The reported frequency of smoking and alcohol consumption was lower than expected (28.5% and 27.4%, respectively). The majority of patients (75.6%) were diagnosed with advanced disease. Most patients (83.6%) had a primary tumor located in the pancreatic head. The histological diagnosis was ductal adenocarcinoma in 90.7% of the cases, while neuroendocrine tumor was present in 5.3%. Biliary stent implantation was performed in 166 patients, 59.2% of them received metal stents. Primary tumor resection was performed in 60 (16.9%) patients. Enteral or biliary bypass was done in 35 and 49 patients, respectively. In a multivariate Cox-regression model, smoking status and presence of gemcitabine-based chemotherapy were identified as independent predictors for overall survival.nnnCONCLUSIONnWe report the first data from a large cohort of Hungarian pancreatic cancer patients. We identified smoking status and chemotherapy as independent predictors in this cohort.

Meta-analysis of early nutrition: The benefits of enteral feeding compared to a nil per os diet not only in severe, but also in mild and moderate acute pancreatitis

The recently published guidelines for acute pancreatitis (AP) suggest that enteral nutrition (EN) should be the primary therapy in patients suffering from severe acute pancreatitis (SAP); however, none of the guidelines have recommendations on mild and moderate AP (MAP). A meta-analysis was performed using the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P). The following PICO (problem, intervention, comparison, outcome) was applied: P: nutrition in AP; I: enteral nutrition (EN); C: nil per os diet (NPO); and O: outcome. There were 717 articles found in Embase, 831 in PubMed, and 10 in the Cochrane database. Altogether, seven SAP and six MAP articles were suitable for analyses. In SAP, forest plots were used to illustrate three primary endpoints (mortality, multiorgan failure, and intervention). In MAP, 14 additional secondary endpoints were analyzed (such as CRP (C-reactive protein), WCC (white cell count), complications, etc.). After pooling the data, the Mann–Whitney U test was used to detect significant differences. Funnel plots were created for testing heterogeneity. All of the primary endpoints investigated showed that EN is beneficial vs. NPO in SAP. In MAP, all of the six articles found merit in EN. Analyses of the primary endpoints did not show significant differences between the groups; however, analyzing the 17 endpoints together showed a significant difference in favor of EN vs. NPO. EN is beneficial compared to a nil per os diet not only in severe, but also in mild and moderate AP.