Biomedical subjects

S Dobrowolski

Publications and source records attributed to S Dobrowolski.

13 recordsLinked to original sources

PubMed2006

Does the septic shock interfere experimental acute pancreatitis in rats?

INTRODUCTION: Acute pancreatitis is a disease involving pro-inflammatory mediators. Two complex and multifactorial pathogenetic ways lead to edematous or necrotizing pancreatitis. The course of the disease is thought to be the consequence of an acute inflammatory response. AIM: The authors examined the impact of Escherichia coli LPS on the acute cerulein pancreatitis in rats. METHODS: The study was performed on rats using the ceruleine pancreatitis model. The activation status of polymorphonuclear cells, blood IL-6 concentration, oxidative stress parameters, pancreatic enzymes concentration and microscopic alterations were determined at 5th and 9th h observations. RESULTS: In acute pancreatitis and acute pancreatitis with LPS groups, the peripheral polymorphonuclear cells activity was lower than in control one. Authors noticed the same neutrophil activation in acute pancreatitis after lipopolysaccharide administration although the peripheral blood polymorphonuclear cells count was significantly higher at the 9th h observation. LPS neither changed the oxidative stress within pancreatic gland, nor amylase or serum lipase activity. LPS given to acute pancreatitis animals resulted in significant increase of serum IL-6 concentration at 5th observation turning normal after 9th h. CONCLUSIONS: Collected data supports thesis of early polymorphonuclear cells involvement in acute pancreatitis and oxidative stress evidence in pancreatic parenchyma. However, results did not reveal that administration of LPS amplified inflammatory response during the course of acute pancreatitis.

Acute Disease↗

PubMed2004

Organ microcirculatory disturbances in experimental acute pancreatitis. A role of nitric oxide.

Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis (AP). The aim of the study was to investigate an influence of L-arginine (nitric oxide substrate) and N(G)-nitro-L-arginine (L-NNA, nitric oxide synthase inhibitor) on organ microcirculation in experimental acute pancreatitis induced by four consecutive intraperitoneal cerulein injections (15 microg/kg/h). The microcirculation of pancreas, liver, kidney, stomach, colon and skeletal muscle was measured by laser Doppler flowmeter. Serum interleukin 6 and hematocrit levels were analyzed. AP resulted in a significant drop of microperfusion in all examined organ. L-arginine administration (2 x 100 mg/kg) improved the microcirculation in the pancreas, liver, kidney, colon and skeletal muscle, and lowered hematocrit levels. L-NNA treatment (2 x 25 mg/kg) caused aggravation of edematous AP to the necrotizing situation, and increased IL-6 and hematocrit levels. A further reduction of blood perfusion was noted in the stomach only. It is concluded that L-arginine administration has a positive influence on organ microcirculatory disturbances accompanying experimental cerulein-induced AP. NO inhibition aggravates the course of pancreatitis.

Acute Disease↗

PubMed2004

Prophylactic submucosal saline-adrenaline injection in colonoscopic polypectomy: prospective randomized study.

BACKGROUND: Endoscopic polypectomy is a standard method of treatment of gastrointestinal polyps, but is associated with substantial risk of complications. The most common is hemorrhage, the rate of which varied between 0.3%, and 6%. Various prophylactic techniques have been used to reduce this incidence. The aim of this study was to establish whether the prophylactic injection of adrenaline-saline solution reduces the risk of postpolypectomy bleeding in colonoscopic polypectomy. METHODS: Between May 2000 and June 2002, patients with colorectal polyps of size > or =1 cm were randomized to receive submucosal epinephrine injection (group A) or no injection (group B). The polypectomies were carried out using the conventional method. In group A, epinephrine (1/10,000) was injected into the stalk or base of the polyp. The patients were observed for complications. RESULTS: A total of 69 patients with 100 polyps were enrolled in this study: n = 50 in group A, and n = 50 in group B, according to randomization. There were a total of nine episodes of postpolypectomy hemorrhage, one in the epinephrine group and eight in the control group (1/50 vs 8/50, p < 0.05). The bleeding correlated with the size of the polyps and the diameter of the stalks. CONCLUSIONS: Epinephrine injection prior to colonoscopic polypectomy is effective in preventing bleeding.

Adenocarcinoma↗

PubMed2001

[Appendico-ileo-caecal intussusception as a cause of mechanical ileus].

The authors present a case of 34 years old male operated on for mechanical ileus caused by intussusception of unchanged appendix, cecum and terminal part of ileum. The paper presents possible mechanism of intussusception, diagnostic difficulties determined by non-characteristic symptoms and imaging examination results.

Adult↗

PubMed1999

Optimization of an automated DNA purification protocol for neonatal screening.

CONTEXT: Collection of blood from newborns is a standard clinical procedure used for genetic screening. Typically, blood from a heel prick is absorbed onto standard collection paper and dried before analysis of metabolites, proteins, hormones, and more recently DNA. OBJECTIVE: To evaluate strategies to purify DNA for use with automated workstations. DESIGN: Two factors were used to evaluate several DNA purification protocols: residual heme contamination and amplification yield. The protocol that produced DNA with the lowest heme content and the highest amplification yield was selected. In combination with those two performance factors, the protocol with the fewest number of steps was chosen to reduce reagent use and processing time. SETTING: Industrial research and development laboratory. RESULTS: Robust amplification of DNA isolated from dried blood spots was demonstrated using both fluorescence and agarose gel-based detection methods. In addition, the samples had consistent DNA volumes and had no detectable cross-contamination. Suggested instrument settings, equipment, and supplies were included for automated processing of DNA from dried blood spots. CONCLUSION: A 4-step DNA processing protocol was developed for dried blood spots. The protocol could be performed in either a manual or automated format, making it possible to process hundreds of samples in 1 day.

Blood Chemical Analysis↗

PubMed1997

Microcirculatory disturbances of the pancreas in cerulein-induced acute pancreatitis in rats with reference to L-arginine, heparin, and procaine treatment.

Local microcirculatory dysfunction within the pancreatic gland might be an important factor in the conversion of oedematous to necrotizing pancreatitis. Therapeutic agents, improving the pancreatic blood flow, might be valuable in acute pancreatitis treatment. An influence of nitric oxide, heparin and procaine treatment on microcirculatory values in acute pancreatitis (AP) in rats was investigated. Acute pancreatitis was induced by i.p. injection of cerulein in four doses of 15 microg kg-1 each at 1-h intervals. The rats with pancreatitis were divided into five groups, 12 animals each. One group remained without treatment, four groups were treated i.p. either with NO synthase inhibitor L-NNA (2x25 mg kg-1 or heparin 2x2.5 mg kg-1 or L-arginine 2x100 mg kg-1 or procaine 2x25 mg kg-1. Five control groups, ten animals each, received saline, L-NNA, heparin, L-arginine or procaine only. Five hours after the first ceruleine injection microcirculatory values within the pancreas were measured by means of laser Doppler flowmetry. Acute pancreatitis caused a significant drop of microcirculatory value to 37% of the basal value. The L-NNA administration resulted in a further insignificant reduction of the pancreatic blood flow to 34%. An improvement of microcirculation was observed in rats with pancreatitis receiving heparin (76%) and L-arginine (72%). Procaine had no effect on microcirculatory disturbances within the pancreas in rats with pancreatitis. Cn-induced acute pancreatitis (AP) causes microcirculatory deterioration within the pancreas. Heparin and nitric oxide donor, L-arginine, might be considered as therapeutic agents, improving the diminished pancreatic tissue perfusion observed in acute pancreatitis. Procaine does not improve the pancreatic blood flow in acute pancreatitis.

Acute Disease↗

PubMed1997

[Microcirculation disorders of the pancreas in cerulein induced acute pancreatitis in rats with regard to nitrogen oxide and heparin].

UNLABELLED: Microcirculatory disturbance may play an important role in the development of severe pancreatitis, leading the edematous form of the disease to the necrosis. The aim of this study was to investigate the impact of L-arginine (nitric oxide donor), L-NN (NO synthase inhibitor), and heparin on the pancreas microcirculation, serum interleukin-6 level and microscopic alterations of the pancreas in acute pancreatitis in rats. METHODS: Acute pancreatitis was induced in 72 rats by four intraperitoneal injections of cerulein (CN) (15 micrograms/kg body weight). Microcirculatory values was measured by means of laser Doppler flowmetry five hours after the first cerulein injection. The animals were divided into the following groups (12 rats each), according to the kind of treatment: Group 1 (CN), Group 2 (CN + L-NNA), Group 3 (CN + L-arginine), Group 4 (CN + Heparin), Group 5 (Control), Group 6 (L-NNA), Group 7 (L-arginine), Group 8 (Heparin). RESULTS: Remarkable morphologic changes in the pancreas including parenchymal necrosis, an elevation of serum IL-6 level, and significant drop of pancreatic capillary perfusion was observed in rats with NO synthase inhibition. L-arginine improved the pancreatic microcirculatory but worsened the microscopic alteration within the pancreas. Heparin had a beneficial effect on the microcirculatory values, serum IL-6 concentration, and morphologic changes. CONCLUSIONS: Acute pancreatitis causes microcirculatory disturbance within the pancreatic gland. The inhibition of NO synthase aggravates AP. L-arginine treatment improves pancreatic perfusion but potentiates morphologic alterations. Heparin has beneficial impact on AP, it improves the microcirculation and inflammatory changes within the pancreatic gland.

Analysis of Variance↗

PubMed1996

Is nitric oxide and heparin treatment justified in inflammatory bowel disease? An experimental study.

Microcirculatory disturbances of the colon may contribute to the pathogenesis of inflammatory bowel disease. The aim of the study was to investigate the alterations of rectal blood perfusion in experimental colitis with reference to nitric oxide and heparin treatment. The study was carried out on 36 rats, divided into six groups: group I, control; group II, control + NG-nitro-L-arginine (L-NNA); group III, colitis without treatment; group IV, colitis + L-arginine; group V, colitis + L-NNA; group VI, colitis + heparin treatment. Experimental colitis was induced by 4% acetic acid enema, and 48 h after the enema, besides the measurement of rectal capillary blood flow by means of laser Doppler flowmetry, the serum interleukin-6 (IL-6) level and histopathological alterations within the rectal mucosa were examined. Experimental colitis resulted in a drop in rectal wall perfusion. L-Arginine and heparin treatment improved the microcirculatory values. The highest IL-6 level and the most advanced histopathological alterations were observed in the rats treated with L-NNA. L-Arginine treatment had no influence on IL-6 concentration, however it aggravated the inflammatory changes within the rectal mucosa. Heparin administration reduced the IL-6 values and also had a positive impact on the microscopic alterations within the rectal wall. It is concluded that heparin treatment has a beneficial effect on the microcirculatory disturbances and inflammatory changes observed in experimental colitis. The inhibition of nitric oxide-synthase aggravated the course of experimental colitis. L-Arginine administration improves the rectal blood flow but aggravates the histopathological alterations within the rectal wall.

Acetic Acid↗

PubMed1995

Inhibition of cyclin-dependent kinases by p21.

p21Cip1 is a cyclin-dependent kinase (Cdk) inhibitor that is transcriptionally activated by p53 in response to DNA damage. We have explored the interaction of p21 with the currently known Cdks. p21 effectively inhibits Cdk2, Cdk3, Cdk4, and Cdk6 kinases (Ki 0.5-15 nM) but is much less effective toward Cdc2/cyclin B (Ki approximately 400 nM) and Cdk5/p35 (Ki > 2 microM), and does not associate with Cdk7/cyclin H. Overexpression of P21 arrests cells in G1. Thus, p21 is not a universal inhibitor of Cdks but displays selectivity for G1/S Cdk/cyclin complexes. Association of p21 with Cdks is greatly enhanced by cyclin binding. This property is shared by the structurally related inhibitor p27, suggesting a common biochemical mechanism for inhibition. With respect to Cdk2 and Cdk4 complexes, p27 shares the inhibitory potency of p21 but has slightly different kinase specificities. In normal diploid fibroblasts, the vast majority of active Cdk2 is associated with p21, but this active kinase can be fully inhibited by addition of exogenous p21. Reconstruction experiments using purified components indicate that multiple molecules of p21 can associate with Cdk/cyclin complexes and inactive complexes contain more than one molecule of p21. Together, these data suggest a model whereby p21 functions as an inhibitory buffer whose levels determine the threshold kinase activity required for cell cycle progression.

Binding, Competitive↗

PubMed1994

Cellular ras activity is required for passage through multiple points of the G0/G1 phase in BALB/c 3T3 cells.

Microinjection experiments demonstrated a requirement for cellular ras activity late in G1. In this study, we used two separate methods to identify an additional requirement for cellular ras activity early in the G0/G1 phase of the cell cycle. Quiescent BALB/c cells were injected with anti-ras antibody prior to stimulation with serum. The cells would therefore be inhibited in progression through the cell cycle at the earliest point requiring ras function. Alternatively, cells were inhibited in late G1 as in previous studies by injecting anti-ras several hours after serum addition to quiescent cells. The injected cultures were then treated with chemical cell cycle inhibitors known to function in mid-G1. Cells injected with anti-ras prior to serum stimulation were retained at a point of ras requirement prior to the execution point of the chemical inhibitor, while cells injected 3 to 5 h after serum stimulation were retained at a point of ras requirement downstream of the execution point of the chemical inhibitor. To confirm these results, quiescent BALB/c cells were injected with anti-ras antibody prior to or several hours following serum addition. In this case, however, second injections of oncogenic ras or adenoviral E1A protein were performed to overcome the inhibitory effects of the anti-ras antibody. Cells injected prior to serum addition were clearly inhibited at an early point of Ras requirement since they required 5 or 6 h longer to enter S phase than cells injected with anti-ras antibody after serum addition.

3T3 Cells↗

PubMed1992

Catalytic properties, tissue and intracellular distribution of neurofibromin.

The neurofibromatosis type 1 (NF1) gene encodes a protein, neurofibromin, that shows homology with members of the GTPase-activating protein (GAP) family. To study neurofibromin, rabbit polyclonal antisera were raised against two synthetic peptides. These antisera immunoprecipitated a specific protein of about 240 kDa in lysates of adult murine and rat tissues both in the soluble (S100) and to a lesser degree in the particulate (P100) fractions. The neurofibromin immunoprecipitated from the lysates of several murine organs stimulated the intrinsic GTPase activity of p21 c-Ha-ras protein. Based on immunoblotting, immunoprecipitation and GTPase assays, neurofibromin appears to be at least 10-fold more abundant in the brain than in the other murine organs. The GTPase-stimulatory activity of full-length neurofibromin, like the catalytic GAP-related domain, is inhibited by arachidonic acid and the detergent dodecyl maltoside, while phosphatidic acid, containing arachidonic and stearic acid, is non-inhibitory. Immunofluorescence analysis with anti-neurofibromin sera in NIH3T3 cells suggests that at least some of the cellular protein associates with cytoplasmic structures that are distinct from actin or tubulin filaments.

Amino Acid Sequence↗

PubMed1991

The GTPase stimulatory activities of the neurofibromatosis type 1 and the yeast IRA2 proteins are inhibited by arachidonic acid.

Three proteins, GTPase activating protein (GAP), neurofibromatosis 1 (NF1) and the yeast inhibitory regulator of the RAS-cAMP pathway (IRA2), have the ability to stimulate the GTPase activity of Ras proteins from higher animals or yeast. Previous studies indicate that certain lipids are able to inhibit this activity associated with the mammalian GAP protein. Inhibition of GAP would be expected to biologically activate Ras protein. In these studies arachidonic acid is shown also to inhibit the activity of the catalytic fragments of the other two proteins, mammalian NF1 and the yeast IRA2 proteins. In addition, phosphatidic acid (containing arachidonic and stearic acid) was inhibitory for the catalytic fragment of NF1 protein, but did not inhibit the catalytic fragments of GAP or IRA2 proteins. These observations emphasize the biochemical similarity of these proteins and provide support for the suggestion that lipids might play an important role in their biological control, and therefore also in the control of Ras activity and cellular proliferation.

Arachidonic Acid↗

PubMed1991

Ras GTPase-activating protein physically associates with mitogenically active phospholipids.

The physical interaction between GTPase-activating protein (GAP) and lipids has been characterized by two separate analyses. First, bacterially synthesized GAP molecules were found to associate with detergent-mixed micelles containing arachidonic but not with those containing arachidic acid. This association was detected by a faster elution time during molecular exclusion chromatography. Second, GAP molecules within a crude cellular lysate were specifically retained by a column on which certain lipids had been immobilized. The lipids able to retain GAP on such columns were identical to those which were shown previously to be most active in blocking GAP activity. The association between lipids and GAP was dependent upon magnesium ions. Lipids unable to inhibit GAP activity were also unable to physically associate with GAP. The tight association of GAP with these lipids was predicted by and helps to rationalize their ability to inhibit GAP activity.

Animals↗