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Biomedical subjects

D L Kaminski

Publications and source records attributed to D L Kaminski.

At least 37 records · Page 2Linked to original sources

The effect of trinitrobenzene sulfonic acid (TNB) on colonocyte arachidonic acid metabolism.

In previous studies we found that luminal perfusion of the isolated left colon of the rabbit with the hapten, trinitrobenzene, resulted in the production of an acute inflammatory process associated with alterations in eicosanoid metabolism. As the colitis was attenuated by cyclooxygenase inhibitors it is possible that the inflammation was mediated by arachidonic acid metabolites. In the present study it was intended to evaluate the effect of trinitrobenzene on eicosanoid metabolism in transformed human colonic cells by exposing Caco-2++ cells to various doses of trinitrobenzene. Cell injury was evaluated by measuring lactate dehydrogenase levels and cyclooxygenase and lipoxygenase activity was evaluated by measuring prostanoid and leukotriene production. In separate experiments resting and trinitrobenzene stimulated cells were treated with indomethacin and dexamethasone. Trinitrobenzene produced increased prostaglandin E2 and 6-keto prostaglandin F1alpha++ and increased lactate dehydrogenase levels. Leukotriene B4 was significantly increased compared to control values at the highest TNB concentration administered. Indomethacin inhibited the lactate dehydrogenase and prostanoid changes, suggesting that the inflammatory changes produced were mediated by the prostanoids. Dexamethasone administered for 1 hr prior to trinitrobenzene decreased the 6-keto prostaglandin F1alpha but did not alter trinitrobenzene produced changes in lactate dehydrogenase concentrations. Exposure of Caco-2 cells to dexamethasone for 24 hr decreased the trinitrobenzene produced lactate dehydrogenase and eicosanoid changes. The results suggest that trinitrobenzene produces an acute injury to Caco-2 cells that may be mediated by the cyclooxygenase enzymes.

Arachidonic Acid↗

Ischemic colitis.

Ischemic colitis represents the most common form of gastrointestinal ischemia. The presumed etiologies are numerous; however, it typically develops "spontaneously," in the absence of major vasculature occlusion, and in the presence of viable intestine elsewhere. It is most usefully classified into gangrenous and nongangrenous forms, the latter of which may be subdivided into transient and chronic types. Ischemic colitis may develop in people who are otherwise healthy, although a variety of clinical settings, such as shock, predispose to its occurrence. It usually presents as an acute abdominal illness with bloody diarrhea. Diagnosis is confirmed by colonoscopy. Therapy and outcome are dependent on the severity of disease. Nongangrenous colonic ischemia usually requires only medical management and is associated with a good prognosis. The chronic subtype may lead to the sequelae of persistent segmental colitis or colonic strictures, occasionally requiring surgery. Urgent operative intervention and a high morbidity and mortality are the hallmarks of gangrenous colonic ischemia. Special considerations must be given to those patients in whom ischemic colitis develops in the context of colon carcinoma or obstructing colon lesions, after abdominal aortic surgery, and following cardiopulmonary bypass. This review will discuss the clinical spectrum of ischemic colitis.

Colitis, Ischemic↗

Role of cytokines and platelet-activating factor in inflammatory bowel disease. Implications for therapy.

BACKGROUND: Platelet-activating factor (PAF) and cytokines, such as interleukins, tumor necrosis factor, and others, are thought to play a role in the inflammatory process involving gastrointestinal disorders such as Crohn's disease, ulcerative colitis, ischemic colitis, or antibiotic-associated colitis. PURPOSE: This study was undertaken to review the latest literature on the role of PAF and cytokines in the genesis of inflammatory bowel disease and implications for therapy and management. RESULTS: PAF is an endogenous phospholipid involved in hypersensitivity and inflammatory reactions such as platelet and neutrophil aggregation, vasodilation, increased vascular permeability, and leukocyte adhesion, which have been associated with inflammatory processes. Cytokines are peptides that regulate and coordinate inflammatory and immunologic responses. Increased production of cytokines has been reported during Crohn's disease and ulcerative colitis and is correlated with disease activity. CONCLUSIONS: Because PAF and cytokines may have an important role in the pathogenesis of inflammatory bowel disease, their inhibition by specific antagonists, mediators, or other agents such as steroids may have a potential therapeutic benefit in treatment and management of these inflammatory diseases in the near future.

Animals↗

Role of protein kinase A in human hepatocyte DNA synthesis.

The cellular mechanisms associated with the replicative response of hepatocytes to growth factor simulation is incompletely understood. Murine hepatocyte DNA synthesis is altered by cyclic AMP, suggesting that protein kinase A is involved in the cellular mechanisms associated with liver growth. The purpose of this study was to evaluate the role of protein kinase A in human hepatocyte DNA synthesis. human hepatocytes were isolated and maintained in primary culture on rat tail collagen. DNA synthesis was evaluated by determining [3H] thymidine incorporation. Human hepatocytes between 24 and 96 hr following harvest increased DNA synthesis in response to epidermal growth factor but not in response to glucagon, a stimulant of adenyl cyclase, or dibutyryl cyclic AMP. Mitogen-stimulated DNA synthesis was decreased by dibutyryl cyclic AMP. Cyclic AMP isomers that block or stimulate the effect of cyclic AMP on protein kinase A did not significantly alter resting or mitogens-stimulated human hepatocyte DNA synthesis. The results suggest that increased protein kinase A activity does not produce human hepatocyte replicative DNA synthesis.

Cell Culture Techniques↗

Prospective comparison of helium versus carbon dioxide pneumoperitoneum.

BACKGROUND: During prolonged laparoscopic operations with carbon dioxide (CO2) pneumoperitoneum (PP), hypercapnia with significant acidosis has been reported to occur in some patients with pulmonary dysfunction. An alternate inert insufflation gas like helium (He) could avoid this problem. METHODS: This prospective, IRB-approved study compared the cardiopulmonary response in 20 patients with both CO2 and He PP. With the minute ventilation held constant, baseline arterial blood gases and ventilatory and cardiac parameters were obtained after anesthetic induction but prior to CO2 PP. All values were repeated at 20 to 30 and 40 to 60-minute intervals after the insufflation of CO2 PP, then again during He PP. Values were compared by a paired t test analysis. RESULTS: Patients experienced significant hypercapnia during CO2 PP when compared with baseline arterial blood gases, but all values returned to baseline levels during He PP. CONCLUSIONS: He PP is an effective alternative to CO2 PP for a laparoscopic cholecystectomy avoiding CO2 retention and subsequent acidosis. Carbon dioxide retention may be dangerous in patients with pulmonary dysfunction who undergo laparoscopy.

Blood Gas Analysis↗

The effect of prostanoids on hepatic bile flow in dogs with normal liver and bile duct cell hyperplasia.

Bile flow rates and composition are subject to a wide variety of neural, endocrine and paracrine influences. The effects of these multiple factors may be different in the diseased liver compared to the response produced in the normal liver. As prostanoids may have a therapeutic role in liver disease it was intended to evaluate the effects of two principal therapeutic prostanoids, prostaglandin E2 and prostacyclin, on bile flow in dogs with a normal liver and in dogs with hepatotoxin-induced liver injury. Initially, in awake animals with chronic biliary and gastric fistulas the bile flow response to prostaglandin E2 and prostacyclin was evaluated and compared to the response produced by bile salt infusion alone and to that produced by the standard choleretic hormones, secretin and glucagon. The animals were then fed alpha-naphthylisothiocyanate (ANIT) and the studies repeated. ANIT is a hepatoxin that produces bile duct cell hyperplasia which was confirmed in dogs by demonstrating that ANIT increased [3H]thymidine incorporation by isolated canine bile duct cells. In normal dogs, the prostanoids, secretin, and glucagon increased hepatic bile flow. 10 days of ANIT feeding produced a hypercholeresis. While secretin was able to stimulate the hyperplastic biliary epithelium and increase bile flow over values produced by the hyperplastic biliary epithelium alone, neither prostaglandin E2, prostacyclin, or glucagon appeared to stimulate the hyperplastic biliary epithelium. As ANIT produced evidence of cholestasis and hepatocellular damage, only secretin would seem to have a potential therapeutic role in increasing bile flow in cholestatic liver disorders associated with bile duct cell hyperplasia.

1-Naphthylisothiocyanate↗

Substrates of human hepatic cytochrome P450 3A4.

Cytochrome P450 isozyme 3A4 (CYP3A4) is a major isozyme in the human liver and is known to metabolize a larger variety of xenobiotics and endogenous biochemicals. The identities of CYP3A4 substrates are summarized here. A total of 32 chemicals belonging to different structural classes have been evaluated and found to be substrates for CYP3A4. The metabolic pathways for these substrates include N-oxidation, C-oxidation, N-dealkylation, O-dealkylation, nitro-reduction, dehydration, and C-hydroxylation. While the major experimental system used to elucidate the role of CYP3A4 in the metabolic transformation of these substrates is the human liver microsome system, cultured human hepatocytes and yeast/cultured cells genetically engineered to express CYP3A4 are also employed by the different investigators. The common approaches to identify the role of CYP3A4 are also summarized, which include correlation of metabolic activity of the substrates studied with those for known CYP3A4-catalyzed substrates, correlation of activity with CYP3A4 content, inhibition of activity with CYP3A4 specific antibodies, inhibition of activity with known CYP3A4 substrates and inhibitors, induction of activity with CYP3A4 inducers and demonstration of activity with purified CYP3A4 enzyme.

Biotransformation↗

Comparative evaluation of educational methods in surgical resident education.

OBJECTIVE: To determine the influence of study methods on American Board of Surgery (ABS) examination performance. DESIGN: Performance on ABS examinations by and faculty evaluations of 54 categorical surgical residents from 1976 to 1992 were correlated with the residents' use of commonly available educational methods (textbooks, Selected Readings in General Surgery, grand rounds, preceptor guidance, clinical surgery review courses, surgical science review courses, Surgical Education and Self-Assessment Program [SESAP], and continuing medical education lectures) in early, late, and after residency. SETTING: An average-sized midwestern US university surgical residency. RESULTS: Residents who consistently scored above the 33rd percentile on ABS examinations had used texts early, Selected Readings later, and SESAP after residency more frequently than those with ABS In-Training Examination scores in the lower one third. Selected Readings and clinical review courses were associated with significant increases in ABS percentile scores when used in late or after residency and, along with SESAP, were used when residents improved their low ABS In-Training Examination scores. CONCLUSIONS: Independent study methods are the most effective pathway to successful ABS examination performance. Formal surgical review courses may help improve the ABS examination scores of residents at a higher risk of failure.

Clinical Competence↗

Evidence for a colonic PAF receptor.

We sought to determine the effect of exogenously administered platelet-activating factor (PAF) on eicosanoid release from the left colon of the rabbit. Using an isolated buffer-perfused rabbit left colon preparation, 1.0- or 5.0-micrograms doses of PAF were infused into the inferior mesenteric artery. Effluents from the inferior mesenteric vein and colonic lumen were collected and the concentrations of the eicosanoids, prostaglandin E, 6-ketoprostaglandin F1 alpha, thromboxane B2, and leukotriene B4 (LTB4), were measured by ELISA. During PAF infusion there was a significant increase of all prostanoids, but not LTB4 into the venous effluent and colonic luminal perfusate when compared to control experiments. Additional studies were performed by pretreating the colons with the PAF antagonists WEB-2170 or alprazolam prior to PAF infusion. Both venous and luminal effluent prostanoid release was effectively blocked by WEB-2170, but not by alprazolam. Colons pretreated with WEB-2170 prior to PAF had markedly diminished tissue injury when compared to colons treated with PAF alone. Inhibition of PAF-stimulated prostanoid release by WEB-2170 suggests that a PAF-sensitive receptor is present in rabbit colonic tissue which may induce eicosanoid-mediated tissue injury.

Animals↗

Gallbladder mucosal protein secretion during development of experimental cholecystitis.

The development of experimental cholecystitis produced by lysophosphatidylcholine is associated with reversal of the normal absorptive characteristics of gallbladder mucosa, resulting in the intraluminal accumulation of water, glycoprotein, and protein. The purpose of the present study was to attempt to ascertain if the protein leaks into the lumen because of the cytolytic properties of lysophosphatidylcholine or if it is due to an active secretory process and to characterize the protein produced. Experiments were performed on anesthetized cats undergoing gallbladder perfusion with and without lysophosphatidylcholine. The amount of protein in the perfusate was measured and albumin clearance from blood to gallbladder lumen was calculated with and without the administration of vesicular transport inhibitors. In separate experiments, control and lysophosphatidylcholine (LPC) produced gallbladder perfusates were collected and the protein subjected to SDS-PAGE to ascertain the nature of the protein secreted. Inhibitors of both microtubular and microfilament activity decreased the protein accumulation and clearance produced by lysophosphatidylcholine. Gallbladder white blood cell accumulation and inflammation as evaluated by beta-glucuronidase and prostaglandin E levels were not significantly altered by cytochalasin or colchicine administration. Lysophosphatidylcholine also produced significant increases in perfusate LDH levels. The protein produced was primarily a 66-kDa protein. Transfer of the protein to a nitrocellulose membrane and immunoblotting with anti-albumin antibody demonstrated that the protein was albumin. The results suggest that during the development of cholecystitis, lysophosphatidylcholine produces albumin accumulation in the gallbladder primarily by inducing an active secretory process resulting in gallbladder distension.

Albumins↗

Lysophosphatidylcholine-stimulated protein and glycoprotein production by human gallbladder mucosal cells.

It has been demonstrated in experimental cholecystitis in cats produced by lysophosphatidylcholine that the development of inflammation is associated with the exsorption of a large amount of protein into the gallbladder lumen. It was subsequently demonstrated that in feline experimental cholecystitis the protein produced was albumin and that its production was decreased by vesicular transport inhibitors, suggesting an active secretory process. In the present study, the effect of lysophosphatidylcholine on protein production by fresh, isolated human gallbladder mucosal cells was evaluated. Isolated gallbladder mucosal cells were incubated with [14C]leucine for 24 hr in tissue culture medium. The cells readily incorporated the radioactive label into cellular protein, a process inhibited by cycloheximide. Exposure of the cells to lysophosphatidylcholine for 1 hr in buffer solution resulted in loss of intracellular protein into the buffer solution. Exposure of the cells for 1 hr prior to lysophosphatidylcholine administration to vesicular transport inhibitors, colchicine, and cytochalasin B and to 4 degrees C culture conditions failed to alter the lysophosphatidylcholine-produced passage of the 14C label extracellularly. SDS-PAGE evaluation of the protein produced demonstrated that human gallbladder mucosal cells continuously produced a 66-kDa protein that was not increased by increasing concentration of lysophosphatidylcholine and a 14-kDa protein that increased with increasing concentrations of lysophosphatidylcholine. Employing Western blotting with specific antibodies, the 66-kDa protein was demonstrated to not be albumin but a 66-kDa glycoprotein, and the 14-kDa protein was demonstrated to contain phospholipase A2. Human gallbladder mucosal cells produced a protein and glycoprotein in response to lysophosphatidylcholine by a mechanism not related to vesicular transport.

Carbon Radioisotopes↗

Improved outcome by identification of high-risk nonocclusive mesenteric ischemia, aggressive reexploration, and delayed anastomosis.

BACKGROUND: The factors associated with outcome of patients with nonocclusive mesenteric ischemia are poorly defined. METHODS: Over a 7-year period, 34 consecutive patients with nonocclusive mesenteric ischemia were identified. RESULTS: The mean age of the study patients was 63 years (range 31 to 94); 21 of 34 (62%) were men. The mean delay in diagnosis was 31 hours (range 7 hours to 6 days). Seven of 34 (21%) underwent preoperative visceral arteriography. Two of these 7 required surgery, and both died as a result of intestinal infarction. The remaining 27 had the diagnosis made at celiotomy. Among the 29 who were explored, 16 of 29 (55%) had intestinal infarction. Twenty-one of 29 (72%) had segmental bowel injury whereas 8 of 29 (28%) had massive injury. Among those with segmental infarction, primary anastomosis was performed in 12 of 21 patients (57%); 5 of the 12 (42%) died. Nine of 21 patients (43%) underwent delayed anastomosis; 2 of the 9 (22%) died. No patient with massive injury underwent primary anastomosis. Second-look laparotomy was performed on 22 of 29 (76%). Eleven of those 22 (50%) had a further bowel resection. Overall, 16 of 29 (55%) who underwent surgery for nonocclusive mesenteric ischemia are alive. CONCLUSIONS: Improved survival from nonocclusive mesenteric ischemia is dependent upon the identification of high-risk groups, aggressive reexploration, and delayed intestinal anastomosis.

Acute Disease↗

Rifampicin induction of lidocaine metabolism in cultured human hepatocytes.

In our laboratory, cultured human hepatocytes are being evaluated as an experimental system to study drug interactions. We report the effect of a known cytochrome P450 (CYP) inducer, rifampicin, on the metabolism of lidocaine by primary human hepatocytes. Rifampicin has been shown to induce CYP3A4, a major human hepatic CYP isozyme that is known to metabolize lidocaine to its primary metabolite, monoethylglycinexylidide. Human hepatocytes were cultured on collagen-coated plates in serum-free, hormone-supplemented Waymouth medium for a 3-day period before they were treated with rifampicin at 50 microM for 1 to 3 days. Hepatocytes isolated from five individuals were studied, and, in all cases, lidocaine metabolism was found to be induced by rifampicin, as demonstrated by a higher rate of monoethylglycinexylidide formation than concurrent controls. For three of the hepatocyte cultures, lidocaine metabolism was evaluated at various times after treatment. Induction was observed at 1 day after treatment, and reached higher levels at day 2 or 3. The level of induction was found to be approximately 100% for two hepatocyte isolations and approximately 600% for one isolation. In a separate experiment, hepatocytes were treated with rifampicin for a 2-day period. Rate of lidocaine metabolism at multiple substrate concentrations (10-120 microM) were then studied. Rifampicin induction of lidocaine metabolism (approximately 100%) was observed at all the lidocaine concentrations studied. Lineweaver-Burk plot of the data showed an increase in Vmax and a less significant change in Km. Induction of lidocaine metabolism by rifampicin (concentrations of 0.1-50 microM) was found to be dose-dependent, with significant induction observed at 1 microM and higher concentrations. (ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Glutamine transport in isolated human hepatocytes and transformed liver cells.

The transport of L-glutamine was examined in isolated adult and fetal human hepatocytes as well as in the human hepatoma cell lines HepG2 and SK-Hep. In all cells studied, glutamine uptake was at least 85% Na(+)-dependent. Kinetic analysis of the Na(+)-dependent component indicated mediation by a single transporter in three human hepatocyte preparations and in SK-Hep cells, whereas two transporters appeared to be responsible for glutamine uptake in HepG2 cells and in hepatocytes from the liver of one male patient. Amino acid inhibition analysis showed primary mediation by System N in fetal and adult hepatocytes, whereas System ASC was principally responsible for glutamine uptake in transformed cells. Similar to the rat transporter, human System N was pH-sensitive, stereospecific, and responsive to treatment with steroid hormones. Although the human carrier was less tolerant of Li(+)- for Na+ substitution, glutamine transport in primary human hepatocytes was stimulated by treatment with hypotonic buffer (cell swelling), as reported in rat parenchymal cells. In contrast, glutamine transport in hepatoma cells was relatively insensitive to changes in extracellular pH and failed to show enhanced activity in response to hypoosmotic challenge. Collectively, the data suggest that markedly distinct plasma membrane transporters mediate the concentrative uptake of glutamine in normal and transformed human hepatocytes, and that the salient properties of System N have been largely conserved from rat to man.

Adult↗

Effect of platelet-activating factor and its antagonists on colonic dysmotility and tissue levels of colonic neuropeptides.

We investigated whether platelet-activating factor (PAF) alters colonic tissue levels of substance P and vasoactive intestinal peptide (VIP), two neuropeptides that regulate colonic motility. Left colons were harvested from NZ White Rabbits and underwent vascular perfusion via the inferior mesenteric artery. Strain gauge transducers were sewn onto the serosal surface of the colon to evaluate colonic motility. Colons were perfused with either buffered saline alone or with 5.0 x 10(-5) M PAF. PAF administration increased tissue VIP and substance P levels and decreased the force of colonic contractions. Pretreatment with WEB-2170 or alprazolam decreased concentrations of both tissue neuropeptides, and decreased the force of colonic contractions and minute motility index. These results suggest that both VIP and substance P are stimulated by PAF and may participate in colonic dysmotility during inflammatory states.

Alprazolam↗

Hyperbilirubinemia without common bile duct abnormalities and hyperamylasemia without pancreatitis in patients with gallbladder disease.

OBJECTIVE: To determine the incidence of jaundice and hyperamylasemia in the absence of common bile duct abnormalities or clinical pancreatitis in patients undergoing cholecystectomy. DESIGN: A continuous, prospective analysis of a consecutive case series was performed on all patients undergoing cholecystectomy. SETTING: An urban, tertiary care university hospital. PATIENTS: Adult patients with gallbladder disease. INTERVENTION: All patients underwent cholecystectomy. MAIN OUTCOME MEASURES: The presence or absence of common bile duct abnormalities was evaluated by cholangiography, and pancreatitis was identified by clinical signs, imaging studies, and direct visual inspection during cholecystectomy. RESULTS: All patients (N = 1746) undergoing cholecystectomy were prospectively categorized as having chronic calculous (n = 1410), acute calculous (n = 217), chronic acalculous (n = 70), or acute acalculous (n = 49) gallbladder disease. It was uncommon for patients with chronic calculous cholecystitis to have an elevated bilirubin level with no choledocholithiasis and a normal common bile duct or to have hyperamylasemia without pancreatitis. Twenty-five percent of the patients with acute calculous cholecystitis had a serum bilirubin level between 34 and 86 mumol/L (2.0 and 5.0 mg/dL) with no common bile duct abnormality and 4% had hyperamylasemia without pancreatitis. Over one third of the patients with acute acalculous cholecystitis had an elevated bilirubin level with a normal common bile duct or an elevated amylase level without pancreatitis. CONCLUSION: Jaundice and hyperamylasemia can be produced by gallbladder disease alone.

Acute Disease↗

Laparoscopic cancer surgery. Lessons from gallbladder cancer.

Laparoscopic cholecystectomy (LC) may inhibit the discovery of unsuspected gallbladder cancer, and the effect of LC on the prognosis of gallbladder cancer is unknown. We present two cases of unsuspected gallbladder cancer removed laparoscopically and report the discovery of peritoneal tumor implantation at the umbilical port site 21 days after LC. Although gallbladder carcinoma flow cytometry has been reported to be of prognostic value by Japanese investigators, this technique did not distinguish herein between an invasive adenocarcinoma and carcinoma in situ. A cellular doubling time of 56 h was calculated from one tumor. When unsuspected invasive gallbladder cancer is found after LC, laparoscopic port sites should be inspected at reoperation and, at a minimum, the port site through which the gallbladder was removed should be widely excised. This demonstration of cancer recurrence in laparoscopic port sites may limit the application of laparoscopy to elective cancer resection.

Adenocarcinoma↗

The effect of Clostridium difficile toxin on colonocyte prostanoid activity.

Antibiotic-associated colitis is caused by Clostridium difficile toxin. However, the pathophysiology of this entity is poorly understood. The aim of this study was to determine the effects of C. difficile toxin on colonocyte cyclooxygenase and phospholipase A2 (PLA2) activity. A transformed colonocyte cell line (Caco-2) was grown to confluency on 6 well plates. The cells were stimulated with graded concentrations of C. difficile toxin. In separate experiments, the cells were pretreated for one hour prior to stimulation with the cyclooxygenase inhibitor, indomethacin, or the glucocorticoid, dexamethasone. The culture media was collected one hour following C. difficile stimulation. Prostaglandin E2 (PGE2), 6-keto prostaglandin F1 alpha (6KPGF), thromboxane B2 (TxB2) and leukotriene B4 (LTB4) levels were determined in the media by an ELISA. Platelet activating factor (PAF) concentration was determined by a RIA. C. difficile toxin stimulated PGE2 and 6KPGF levels in a dose dependent fashion but failed to stimulate TxB2, LTB4 or PAF. Prostanoid production was inhibited by indomethacin dose dependently but was not inhibited by dexamethasone. The presence of indomethacin resulted in production of PAF. Our results show that the effects of C. difficile toxin on colonocytes are mediated by cyclooxygenase activity. The increase in PAF formation associated with indomethacin administration suggests that the prostanoids modulate PLA2 activity and inhibit PAF formation.

6-Ketoprostaglandin F1 alpha↗