Biomedical subjects

T J Nevalainen

Publications and source records attributed to T J Nevalainen.

At least 19 recordsLinked to original sources

PubMed1992

Renal tubular cell injury and serum phospholipase A2 activity in acute pancreatitis.

Early diagnosis of threatening renal complication is essential for the adequate treatment of acute pancreatitis. Deposition of phospholipase A2 (PLA2) in rat renal proximal tubular cells has been observed in experimentally induced acute pancreatitis. The value of measuring the catalytic activity of PLA2 in serum as an early warning of developing renal tubular cell injury was therefore investigated in a prospective study of 31 consecutive patients suffering from acute pancreatitis. A positive correlation was found (r = 0.66, P < 0.001) between the highest serum PLA2 activity, as measured early in the course of acute pancreatitis, and the highest N-acetyl-beta-glucosaminidase (NAG):creatinine ratio in the urine. The correlation between the highest serum concentration of immunoreactive pancreatic PLA2 and the highest urinary NAG:creatinine ratio was weaker (r = 0.36, P < 0.05). These results indicate that the measurement of the catalytic activity of PLA2 in serum early in acute pancreatitis may provide a simple test for the detection of threatening renal complication.

Acetylglucosaminidase↗

PubMed1992

Pancreatic phospholipase A2 in proximal tubules of rat kidney in experimental acute pancreatitis and after intravenous injection of the enzyme.

Kinetics and distribution of i.v. human pancreatic phospholipase A2 (h-PLA2) were determined in intact and nephrectomized rats, and tissue localization of rat pancreatic PLA2 (r-PLA2) was studied by immunohistochemistry in experimental acute pancreatitis. The concentration of h-PLA2 and the catalytic activity of phospholipase A2 in plasma decreased exponentially in intact and nephrectomized animals after the injection. The initial 15-min half-life was considerably longer in nephrectomized animals, and higher h-PLA2 concentrations and PLA2 catalytic activities were found in plasma. h-PLA2 was localized in endocytotic vesicles and apical cytoplasmic vacuoles in proximal tubule cells of the kidney. The intensity of the immunoreaction decreased considerably between 15 and 50 min in these cells. No signs of tubular damage were seen by light microscopy. Neither immunoreactive h-PLA2 nor PLA2 catalytic activity was found in urine. r-PLA2 was observed in proximal tubule cells 15 min after an injection of sodium taurocholate (necrotizing pancreatitis group) or saline (edematous pancreatitis group) into the pancreatic duct. Signs of tubular damage were present in necrotizing pancreatitis, but tubular morphology was normal in the animals with edematous pancreatitis. We conclude that the proximal tubule cells of the kidney participate in the metabolism of circulating pancreatic PLA2, and considerably higher PLA2 levels persist in plasma in nephrectomized animals. Endogenous pancreatic PLA2 is detected in kidneys in acute pancreatitis.

Acute Disease↗

PubMed1992

Immunohistochemical characterization of an amphicrine mucinous islet-cell carcinoma of the pancreas. Case report.

Immunohistochemical characteristics of a mucinous islet-cell carcinoma of the pancreas are described. The tumour presented with jaundice in a 59-year-old male. It consisted of polygonal atypical cells forming a reticular pattern, and invaded the common bile duct. In DNA flow cytometry, the tumour cells showed a clear-cut aneuploid peak. Intercellular mucin was abundant. A panel of antisera and monoclonal markers was applied in the immunohistochemical analysis. In addition to general epithelial and endocrine markers, the tumour cells showed a focal positive immunoreaction with anti-glucagon, anti-insulin, anti-vasoactive intestinal polypeptide, anti-pancreatic secretory trypsin inhibitor and anti-phospholipase A2 antigen. At the ultrastructural level, mucous and neuroendocrine granules were demonstrated in the same tumour cells.

Adenoma, Islet Cell↗

PubMed1992

Standards of morphological evaluation and histological grading in experimental acute pancreatitis.

Acute pancreatitis is characterized morphologically by edema, hemorrhages, parenchymal necrosis and fat necrosis. The inflammation is accompanied by infiltration of polymorphonuclear leukocytes. According to the absence or presence of necrosis the disease can be divided into interstitial (or edematous) pancreatitis and hemorrhagic-necrotizing pancreatitis. The severity of disease can be graded in the histological sections either by giving scores to the different types of morphological alterations or by determining the proportion of necrotic tissue of the total lobular parenchyma. The former method is based on subjective assessment of histological slides and is suitable for the evaluation of both edematous and necrotizing pancreatitis. Histometric measurement of necrotic parenchyma can be used only in the necrotizing forms of experimental pancreatitis, e.g. in those induced by intraductal injection of bile, bile salts or digestive enzymes, and in the dietary ethionine-induced pancreatitis. Grading of the tissue damage is essential when the effects of different therapies are evaluated.

Acute Disease↗

PubMed1992

Cholinergic hypothesis of alcoholic pancreatitis.

Chronic alcohol intake interferes especially with the two main pathways regulating exocrine pancreatic secretion: the cholinergic and the pancreozymin pathway. Recently, a new theory of the pathogenesis of alcoholic pancreatitis was proposed emphasizing disordered agonist-receptor interaction at the level of pancreatic acinar cells. Accordingly, alcohol-induced alterations in the control of exocrine pancreatic secretion result in hyperstimulation of pancreatic acinar cells and their muscarinic receptors, mimicking the mechanism of acute pancreatitis caused by scorpion sting, intoxication with an anti-acetylcholinesterase-containing insecticide or supramaximal doses of secretagogues. The present review emphasizes the role of these alcohol-induced secretory alterations in the pathogenesis of alcoholic pancreatitis.

Acetylcholine↗

PubMed1992

Increased concentrations of synovial-type phospholipase A2 in serum and pulmonary and renal complications in acute pancreatitis.

The most important fatal complications of acute pancreatitis are respiratory dysfunction and anuria. Phospholipase A2 has been postulated to be associated with pathologies of various diseases, such as acute pancreatitis, septic shock and multiple injuries. We have recently developed immunoassays for the measurement of pancreatic and nonpancreatic synovial-type phospholipase A2. The present prospective study on 35 consecutive patients with acute pancreatitis indicated that the concentration of synovial-type phospholipase A2, the catalytic activity of phospholipase A2 and the concentration of C-reactive protein in serum were significantly higher in those patients suffering from acute pancreatitis who needed respirator treatment than in those who managed with spontaneous breathing, while there was no difference between these groups in the concentration of pancreatic phospholipase A2. The only significant difference between patients whose highest creatinine concentration rose up to 140 mumol/l and those whose highest creatinine concentration remained below this cutoff value was in their synovial-type phospholipase A2 values. The increased concentration of nonpancreatic synovial-type phospholipase A2 in serum was associated with pulmonary and renal complications. These results emphasize the role of synovial-type phospholipase A2 in the pathophysiology of acute pancreatitis.

C-Reactive Protein↗

PubMed1992

Characterization of two phospholipases A2 in serum of patients with sepsis and acute pancreatitis.

Pancreatic phospholipase A2 and non-pancreatic ascitic phospholipases A2 were studied in sera of healthy individuals and of patients suffering from sepsis or acute pancreatitis. In gel filtration experiments, immunoreactive ascitic phospholipase A2, as determined in serum by a time-resolved fluoroimmunoassay, eluted either unassociated with an apparent M(r) of 10,000-14,000 or associated with proteins of high molecular mass. Catalytically active ascitic phospholipase A2 was associated with high molecular weight proteins. In acute pancreatitis the catalytically active and immunoreactive pancreatic phospholipase A2 eluted mainly as a protein of M(r) of 14,000. The results of the gel filtration experiments indicate that pancreatic phospholipase A2 is not associated with other proteins in human serum, whereas ascitic phospholipase A2 is associated with protein(s) of relative high molecular weight, or exists in different polymeric forms. We also purified phospholipase A2 from sera of healthy individuals by ion exchange chromatography and HPLC. The enzyme was homogenous, displayed an M(r) of approximately 13,500 as judged by SDS-polyacrylamide gel electrophoresis, and reacted with an antibody raised against ascitic phospholipase A2.

Acute Disease↗

PubMed1992

Immunochemical detection of group I and group II phospholipases A2 in human serum.

Time-resolved fluoroimmunoassay was developed for the detection of synovial-type phospholipase A2 (s-PLA2) in human serum. This solid-phase, sandwich assay uses a polyclonal rabbit antibody raised against synovial-type group II PLA2 produced in Escherichia coli. No cross-reactions were detected between s-PLA2 and PLA2 from human or porcine pancreas, human ascitic fluid, or bee or cobra venom. In healthy individuals, the average concentration of s-PLA2 is 3.7 micrograms/L, with a 95% reference interval from 1.3 to 10.8 micrograms/L. We investigated pancreatic PLA2, which is a group I PLA2, and synovial-type group II PLA2 in sera of patients with hematological malignancies and septic fever. The concentration of s-PLA2 was increased in patient sera and correlated significantly with the catalytic activity of PLA2 and the concentration of C-reactive protein. No correlation with the concentration of pancreatic PLA2 was found. The results suggest that the increased catalytic activity of PLA2 in sera of patients with septic fever results from synovial-type group II PLA2.

Adult↗

PubMed1991

Phospholipase A2 in human ascitic fluid. Purification, characterization and immunochemical detection.

A phospholipase A2 (PLA2, EC 3.1.1.4) was purified from human cell-free ascitic fluid (a-PLA2) by ion-exchange chromatography and h.p.l.c. on a reverse-phase column to apparent homogeneity. The enzyme had an Mr of approx. 10,000 as determined by SDS/PAGE. Polyclonal antibodies raised in a rabbit were specific to a-PLA2, as judged by immunoblotting. A time-resolved fluoroimmunoassay (TR-FIA) for measuring the concentration of a-PLA2 in various body fluids was developed. The detection limit of the assay was about 6 ng/ml. The antiserum did not cross-react with pancreatic secretory phospholipase A2 as measured by TR-FIA. The enzyme content was studied in various samples, including normal human serum, buffy-coat leucocytes, synovial fluid, and pancreas and spleen homogenates.

Antibodies↗

PubMed1991

The role of phospholipase A2 in pancreatic acinar cell injury.

The integrity of rat pancreatic acinar cells under the influence of human phospholipase A2 (PLA2) was studied. Isolated pancreatic acini showed no increased discharge of aspartylaminotransferase (ASAT) when incubated either in solutions containing human pancreatic PLA2 or the bile salt sodium deoxycholate (DEC), the latter in concentrations that augment PLA2 activity but have no destructive detergent effect. When human pancreatic PLA2 was injected into the rat pancreatic duct, uneven distribution was observed at 15 min and 3 h in immunohistochemical sections. Edema and a mild inflammatory reaction were the main changes in the pancreas. The necrotic areas seen by light and electron microscopy were quite small and located mostly at the periphery of lobules corresponding the spread of the injected material. Necrosis was of the coagulation type and showed equal extent after the injection of PLA2 with or without DEC. Internalized human pancreatic PLA2 was present already 15 min after the injection in the cytoplasm of some intact acinar cells, indicating a functioning protective mechanism. It was concluded that pancreatic acinar cells are quite resistant to PLA2-catalyzed hydrolysis of membrane phospholipids in vitro, but additional trauma, e.g., pressure caused by intraductal injection, and tissue related factors, such as the mediators of the inflammatory reaction, make acinar cells susceptible to the effect of PLA2.

Acute Disease↗

PubMed1991

Early acinar cell changes in caerulein-induced interstitial acute pancreatitis in the rat.

Early ultrastructural and immunohistochemical changes caused by supramaximal secretory stimulation with caerulein were studied in the rat pancreas. The morphological basis for the earlier reported decrease of pancreatic juice secretion after supramaximal caerulein was the appearance of swollen and irregular zymogen-like material containing structures with short segments of budding bristle-coated membranes in the apical parts of acinar cells. Images of exocytosis of zymogen granules were only few. Later, marked vacuolization and signs of autophagocytosis are seen in the basal cytoplasm. Immunohistochemistry showed that the large zymogen containing structures were intensively labelled for trypsin at the early stages of the experiment (4-30 min). Later (1-2 h), the vacuoles were empty or contained occasional, small-labelled granules only. The pancreozymin-receptor antagonist proglumide as well as cycloleucine that inhibits protein synthesis by inhibiting the synthesis of S-adenosylmethionine, effectively prevented the caerulein induced acinar cell changes. The irregular zymogen containing structures with coated pits on their surface indicate disturbed zymogen granule formation leading to the accumulation of large lakes of zymogen material and finally to marked autophagocytosis in acinar cells. The effects of caerulein are receptor-mediated and depend on the process of methylation in the formation of zymogen granules.

Acute Disease↗

PubMed1991

Application of a new monoclonal antibody for time-resolved fluoroimmunoassay of human pancreatic phospholipase A2.

A monoclonal antibody, designated 2E1, against human pancreatic phospholipase A2 was produced by hybridization of myeloma cells with spleen cells of immunized BALB/c mice. The hybridomas were screened for antibody production by time-resolved fluoroimmunoassay (TR-FIA). The antibody was found to belong to subclass I of murine IgG. The specificity of the antibody was confirmed by immunohistochemistry of pancreatic and other tissues, by immunoblotting of a crude aqueous extract of human pancreas and purified human pancreatic phospholipase A2 and by TR-FIA. A solid-phase time-resolved fluoroimmunoassay was developed by using the monoclonal anti-phospholipase A2 antibody as the catching antibody and a polyclonal sheep anti-phospholipase A2 antibody labelled with europium as the detecting antibody. The validity of the new TR-FIA of human pancreatic phospholipase A2 was confirmed by using it to measure the phospholipase A2 concentrations in serum samples from healthy subjects and from patients suffering from acute pancreatitis.

Acute Disease↗

PubMed1990

Increased serum phospholipase A2 activity in schizophrenia: a replication study.

Phospholipase A2 (PLA2) is a key enzyme in the metabolism of phospholipids. Because a disordered phospholipid metabolism has frequently been reported in schizophrenia, we investigated the PLA2 activity in serum from 14 drug-free paranoid schizophrenic patients, 20 healthy controls, and 8 nonschizophrenic psychiatric patients. Schizophrenics showed significantly higher PLA2 activity than healthy controls and nonschizophrenic patients. The increment in schizophrenics was not due to increased concentration of pancreatic secretory PLA2, as concerning pancreatic PLA2 no differences were found among the 3 proband groups. The present findings confirm the results of our previous study and suggest that increased serum PLA2 activity might reflect an increment in the intracellular enzyme activity in schizophrenia. In the brain the activation of intracellular PLA2 results in changes in neuronal activity due to alterations in receptor sensitivity and in neurotransmitter metabolism. The possibility that such PLA2-induced mechanisms are involved in the pathogenesis of schizophrenia should be investigated in further experiments.

Adult↗

PubMed1990

Clinical significance of nuclear DNA content in pancreatic carcinoma.

The nuclear DNA content of 62 pancreatic adenocarcinomas was analysed by flow cytometry from paraffin-embedded material. Radical surgery could be performed in 12 of the 24 cases with diploid carcinoma, but only in 3 of the 38 cases with a non-diploid tumour (P = 0.0002); the radically resected carcinomas also had a lower fraction of cells in the S-phase (P = 0.009). Non-diploid nuclear DNA content (38 cases, 61 per cent) was associated with advanced stage (P = 0.002), poor histological differentiation (grade II or III, P = 0.004), and primary tumour site in the body or the tail as compared with the head (P = 0.01). The median survival time of the patients with diploid carcinoma was 13 +/- 3 (SE) months, and that of the patients with non-diploid carcinoma 3 +/- 1 months (P = 0.0001). The DNA index with the cutoff value 1.4 was a slightly more powerful prognostic factor than DNA ploidy, and it was the most important independent prognostic factor in Cox's multivariate analysis (P less than 0.001) followed by histological grade (P less than 0.03). We conclude that diploid pancreatic carcinomas are associated with a longer survival than the non-diploid ones, and that radically operable carcinomas form a special subgroup with frequent diploidy and less aggressive biological behaviour.

Adenocarcinoma↗

PubMed1990

Pancreatic acinar cell necrosis with intact storage of digestive enzymes in selenomethionine treated rats.

Morphological and biochemical changes were observed in the pancreas and serum of rats after the intraperitoneal administration of selenomethionine, sodium selenite and methionine. Selenomethionine caused rapidly developing acinar cell necrosis. The first pathological changes were mitochondrial swelling and flocculent densities, and dilatation of cisternae of the endoplasmic reticulum. Zymogen granules appeared disrupted only in disintegrated acinar cells. Signs of autodigestive pancreatic inflammation with fat necrosis, elevation of pancreatic phospholipase A2 and serum amylase activities, as well as pulmonary oedema were present. Sodium selenite caused similar histologic changes to those produced by selenomethionine, but no changes were seen after methionine administration. Destruction of pancreatic acinar cells by an intraductal oleic acid injection that resulted in exocrine atrophy did not prevent systemic selenomethionine toxicity. Our results show that selenomethionine causes pancreatic acinar cell necrosis and that intracellular transport and storage of digestive enzymes is not primarily altered by this chemical.

Animals↗

PubMed1990

[Possible involvement of phospholipase A2 in the pathogenesis of schizophrenia].

Phospholipase A2 (PLA2) is a key enzyme in the metabolism of phospholipids. PLA2 is enriched in neuronal membranes and plays an essential role in the functioning of membrane structures in the brain. Because a disordered phospholipid metabolism has been postulated in schizophrenia we started in 1985 a series of exploratory studies in an attempt to clarify the role of PLA2 in schizophrenic disorders. Our results can presently be summed up as follows: 1. Drug-free schizophrenics showed significantly higher PLA2 activity in serum and in plasma as compared with healthy controls as well as with nonschizophrenic psychiatric patients; the latter did not differ from the control group with regard to PLA2 activity. These findings suggest that increased PLA2 activity might be specific for schizophrenia. 2. The possibility that increased PLA2 activity is an artifact due to prior neuroleptic treatment could be ruled out as improbable by the findings that a) neuroleptic treatment significantly reduced PLA2 activity, and b) increased PLA2 activity was also found in first-onset, never-treated schizophrenic patients. 3. Increased PLA2 activity in schizophrenic patients was not caused by the entry of pancreatic enzyme into circulation. Our findings in serum rather suggest that the increment reflects increased intracellular enzyme activity. We speculate that our results might reflect an increment of the intraneuronal PLA2 activity in the brain. The activation of PLA2 in the brain was found to result in changes in neuronal function due to alterations in receptor sensitivity as well as in neurotransmitter metabolism. The possibility that such PLA2-induced mechanisms are involved in the pathology of schizophrenia should be investigated in further experiments.

Adult↗

PubMed1990

DNA ploidy in pancreatic neuroendocrine tumors.

The nuclear DNA content of 17 pancreatic neuroendocrine tumors was measured from paraffin-embedded tissue with flow cytometry. The tumors were classified by immunostaining with antisera for synaptophysin, insulin, gastrin, glucagon, pancreatic polypeptide, somatostatin, and vasoactive intestinal polypeptide. Eight (47%) of the 17 tumors were aneuploid, and two (12%) were multiploid (had two aneuploid stemlines of cells). Seven of the eight insulinomas, one of the four gastrinomas, and two of the four nonspecified neuroendocrine tumors had an abnormal nuclear DNA content. The DNA indices of the aneuploid and multiploid cases ranged from 1.13 to 1.93, and three cases had a DNA index greater than 1.50. During the follow-up for up to 16 years (mean, 7 years), one patient with diploid nonspecified tumor died of the disease, another patient with a multiploid gastrinoma had metastatic disease develop, and a third patient with a multiploid nonspecified tumor was alive with the disease. The authors conclude that many neuroendocrine tumors of the pancreas have an abnormal nuclear DNA content as measured by DNA flow cytometry. DNA multiploid pancreatic neuroendocrine tumors may be associated with a less favorable clinical course, but this needs to be confirmed in additional studies.

Adult↗

PubMed1990

Serum phospholipase A2 in patients with multiple injuries.

Catalytic phospholipase A2 activity (CA-PLA2) and the concentration of immunoreactive pancreatic PLA2 (IR-PLA2) were measured in serum samples from 12 patients with multiple injuries (median Injury Severity Score: 41). CA-PLA2 was increased in all patients and positive correlations were found between the extent of the increase of CA-PLA2, mortality, and impairment of pulmonary function. IR-PLA2 values were slightly increased in the serum of nine patients with multiple injuries. Of these nine patients, eight had an additional blunt abdominal trauma. On the other hand, no relationship was found between IR-PLA2 and CA-PLA2 values. This finding was confirmed by immunoadsorption experiments with an antiserum to human pancreatic PLA2, which demonstrated that the increased serum levels of IR-PLA2 were not responsible for the increased CA-PLA2 values. The results suggest the existence of at least two immunologically different phospholipase A2 enzymes in sera of patients with multiple injuries.

Adolescent↗