cDNA cloning of the CEPUS, a secreted type of neural glycoprotein belonging to the immunoglobulin-like opioid binding cell adhesion molecule (OBCAM) subfamily

GP55 is a family of glycoproteins distributed predominantly in the nervous system, and its previously characterized members, including the GP55A (EMBL Y08170) and E19S (EMBL Y08171) reveal a typical glycosyl phosphatidyl inositol (GPI)-anchored pattern for membrane proteins. CEPUS identified in this study appeared to represent the third member of GP55. This 3.2 kb long complete cDNA clone from the chicken brain exhibited 3 Ig-like domains. The open reading frame of CEPUS contains 313 amino acids, which can encode a 31.7 kDa core protein (pI 5.75) for the mature form. The signal peptide cleavage site was predicted at Gln25. The structural features of the CEPUS cDNA sequence represented a soluble counterpart to the recently identified cerebellar Purkinje cell specific antigen, CEPU-1. The sequence difference between CEPU-1 and CEPUS was only found in the C-terminus in which the CEPUS lacked the GPI-anchored binding site. It displays significant sequence homology to GP55-related molecules, including OBCAM, GP55A, E19S/LAMP, neurotrimin, and CEPU-1, which are all membrane attached types. The absence of the hydrophobic tail sequence in CEPUS may, therefore, suggest that CEPUS would represent the first identified secreted member in this group of genes. We defined that this molecule forms the opioid-binding cell adhesion molecule (OBCAM) subfamily in the molecular phylogeny. Structurally, these molecules represent acidic proteins (pI 5.47-6.09). Six cysteins, as well as 5 Asn-linked potential glycosylation sites were evolutionary-conserved, suggesting that this OBCAM subfamily resembles immunoglobulin-like and highly glycosylated molecules. The presence of CEPUS would probably suggest to us that the spatial/local expression of the CEPU gene may provide a favorable route for migrating CEPU-positive population of neurons to generate a neuron-specific guidance in developing neurons in vivo.

GABA-mediated representation of temporal information in rat barrel cortex

Temporal sequences of inputs to the rat whiskers are thought to be important to recognize the environment of the rat. In this study, we applied combined stimulations to neighboring whiskers D1 and D2, and the cortical activities evoked in the rat barrel cortex were measured using the intrinsic optical imaging technique. The timing of stimulation to neighboring whiskers affected the evoked cortical activities: the cortical activity evoked by in-phase stimulation to D1 and D2 was significantly stronger than that evoked by out-of-phase stimulation. In order to elucidate the mechanism underlying this phenomenon, the effect of blockade of cortical inhibitory circuits was examined. Iontophoretic application of bicuculline or saclofen (GABA-A or GABA-B antagonist) increased the evoked cortical activities and diminished the difference in activities obtained with in-phase and anti-phase stimulation. These results suggest that local inhibitory circuits play a critical role in coding temporal information of whisker stimulation.

The effect of warfarin therapy on the charge properties of urinary prothrombin fragment 1 and crystallization of calcium oxalate in undiluted human urine

Urinary prothrombin fragment 1 (UPTF1) is the principal protein in calcium oxalate (CaOx) crystals precipitated from human urine and is a potent inhibitor of CaOx crystallization, a property that should depend, at least in part, upon the extent of gamma-carboxylation of the 10 glutamic residues in its N-terminal region. Warfarin therapy limits full gamma-carboxylation of vitamin K-dependent proteins, including UPTF1. The aims of this study were to determine the effect of warfarin therapy on UPTF1, its occlusion into CaOx urinary crystals, and its influence on the crystallization of CaOx in undiluted human urine. In the first part of the study, urines were collected from six men prior to cardiac surgery and after stabilization on long-term warfarin treatment. Proteins in the urines and in the matrix of CaOx crystals precipitated from them were analyzed by two-dimensional SDS-PAGE and Western blotting. In urine, at least two charge variants of UPTF1 with low isoelectric point (pI) values were detected before and during warfarin therapy, but additional higher pI forms of the protein were also seen during anticoagulation. Nonetheless, the majority of UPTF1 was present in the more fully gamma-carboxylated state. CaOx crystals precipitated from the same urine samples contained only low pI forms of UPTF1. The effect of warfarin treatment on CaOx crystallization in urine was tested by collecting two consecutive 24-h urine samples from 16 men prior to cardiac surgery and during subsequent warfarin treatment. CaOx crystallization was induced in each sample by the addition of sodium oxalate. The size and volume of the particles deposited were determined using a Coulter counter, and the crystals were examined by scanning electron microscopy (SEM). There were no significant differences between the urinary metastable limits before or during warfarin treatment or in the total volume of crystals precipitated. A slight increase in the mean diameter of the crystalline particles precipitated from the urines during anticoagulant therapy was not significant. SEM showed little evidence of changes in overall particle size, although individual crystals of CaOx tended to be larger during warfarin treatment. It was concluded from these studies that the binding of UPTF1 to CaOx crystal surfaces is related to the degree of gamma-carboxylation of its Gla domain, which would also influence the protein's inhibitory effects on CaOx crystallization. However, during warfarin therapy the majority of UPTF1 exists in a highly charged state, indicating that it is completely, or almost completely, gamma-carboxylated, which would explain the lack of any difference between CaOx crystallization parameters in the urine of subjects before and during warfarin administration. We conclude that physiologically significant reductions in the inhibitory potency of UPTF1 would be likely to occur only as a result of proscription of gamma-carboxylation more extensive than that induced by warfarin.

Evaluation of the completeness of cancer case ascertainment in the Seoul male cohort study: application of the capture-recapture method

Since the completeness of case ascertainment is directly related to the validity of a study, the evaluation of completeness is an essential feature of a cohort study. To estimate the completeness of cancer case ascertainment during a three year period (Jan. 1, 1993, to Dec. 31, 1995) in which the Seoul Male Cohort was followed up, we applied capture-recapture method. Data were obtained from the cancer registries, medical records and death certificates, with cases identified from each source numbering 103, 105, and 38, respectively. After eliminating duplicate cases, the total number was 141, and by using a log-linear model, the number of cases not detected by any of the three data sources was estimated to be 16. For all cancers, the estimated completeness of follow-up was 89.9%.

New near-nerve needle nerve conduction technique: differentiating epicondylar from cubital tunnel ulnar neuropathy

At the elbow, the ulnar nerve is compressed most commonly either in the epicondylar groove or at the cubital tunnel. While conventional electrodiagnosis may localize an ulnar neuropathy to the elbow, separating epicondylar syndrome (tardy ulnar nerve palsy) from cubital tunnel syndrome is more difficult. We describe a new method using a near-nerve needle technique for distinguishing these two types of ulnar neuropathy at the elbow. We placed three active needle electrodes across the elbow: the first was 4 cm above, and the second and third were 1.5 cm and 6 cm below the medial epicondyle, respectively. The latter two points were chosen because of the presence of the cubital tunnel in this segment. Sensory, motor, and mixed nerve conduction studies (NCS) were performed on these two segments (elbow segment and cubital tunnel segment) in 26 normal nerves and normal data were established. We also present 7 cases of epicondylar ulnar nerve palsy and 1 case of cubital tunnel syndrome in which we were able to confirm the diagnosis with the present method. In 3 cases of epicondylar ulnar nerve palsy, the present method accurately localized the lesion when other methods failed. We believe that this method will be helpful in distinguishing cubital tunnel syndrome from epicondylar ulnar nerve palsy, especially in early ulnar neuropathy in which only sensory fibers are involved.

Gliosarcoma: a case with unusual epithelial feature

Astrocytic tumors, particularly gliosarcoma, may contain epithelial features in the form of trabecular, adenoid, papillary arrangement, and squamous metaplasia. A case of gliosarcoma with unusual epithelial feature is described. The patient was a 60-year-old male with frequent seizures. The mass was 4 cm and in the left frontal lobe. Trabecular or rarely adenoid arrangement of neoplastic astrocytes was present in the mucinous stroma, and there was a distinctive transition between the trabecular area and typical anaplastic astrocytoma. The tumor cells in the trabecular area showed positive immunostain for glial fibrillary acidic protein, but did not react with various kinds of cytokeratin. The sarcomatous area was undifferentiated and was not labeled by factor-VIII, desmin, and anti-smooth muscle actin. Occurrence and histogenesis of epithelial features in gliosarcoma are reviewed. The importance to recognize the existence of epithelial feature in malignant astrocytic tumor is emphasized.

Distribution of proteoglycans in the human trabecular meshwork: histochemical electron microscopic findings with cuprolinic blue

The distribution of sulfated proteoglycans (PGs) in the normal human trabecular meshwork was studied by histochemical electron microscopy using the cationic dye, cuprolinic blue (CB).. The trabecular meshwork was obtained from human enucleated eyes and incubated for three days. After incubation, they were stained with 0.2% CB at a critical electrolyte concentration and prepared for histochemical electron microscopy. Ultrastructurally, PG-CB complexes were found as small punctate or filamentous structures, and were associated with collagen fibrils in the cores of the trabecular beams and the basal laminae of trabecular endothelial cells. In addition, large filamentous PG-CB complexes were mainly associated with areas of amorphous extracellular matrix between the collagen fiber bundles and in the fine fibrillar material near the basal laminae of endothelial cells of Schlemm's canal. This investigation resulted in an illustration of the ultrastructural distribution of PGs in the human trabecular meshwork. Further studies will be needed to specify the nature of PGs and their role in the aqueous outflow system.

Acyl-CoA: cholesterol acyltransferase inhibitory activity of ginseng sapogenins, produced from the ginseng saponins

Ginseng sapogenins were produced from ginseng saponins, isolated from Korean ginseng roots. Ginseng saponins very mildly inhibited acyl-CoA:cholesterol acyltransferase (ACAT) in vitro, however, the sapogenins showed strong inhibitory activity on microsomal ACAT. Therefore, the sapogenins will be one of key ingredients of ginseng affected a lowering of the serum total cholesterol level.

A new experimental model of obstructive hydrocephalus in the rat: the micro-balloon technique

We used three types of specialized micro-balloons 0.7-1.35 mm in outer diameter instead of kaolin to develop a reproducible rat model of hydrocephalus with a low experimental mortality. The micro-balloon was inserted 6 mm deep into the cisterna magna via a burr hole immediately behind the lambda. The angle of introduction was 50 degrees. We also set up kaolin-induced hydrocephalic models in 25 rats as controls. The kaolin model revealed 52% mortality with an 80% induction rate of hydrocephalus, while the balloon model showed 9% mortality with a 60% induction rate. Balloon-induced hydrocephalus was maximal at 1 week and tended to decrease after 2-3 weeks. The pathological findings were not different between the two models. We concluded that the micro-balloon model for hydrocephalus is an easily reproducible model with low experimental mortality.

Preparation of amino acid conjugates of betulinic acid with activity against human melanoma

Betulinic acid has been coupled with a series of amino acids at C-28 carboxylic acid position and the toxicity of the derivatives has been evaluated against cultured human melanoma (MEL-2) and human epidermoid carcinoma of the mouth (KB) cell lines. A number of amino acid conjugates of betulinic acid showed improved water solubility as well as selective cytotoxicity. This investigation demonstrates that amino acid conjugates of betulinic acid can produce potentially important derivatives, which may be developed as antitumor agents.

Backward movements of cross-bridges by application of stretch and by binding of MgADP to skeletal muscle fibers in the rigor state as studied by x-ray diffraction

The effects of the applied stretch and MgADP binding on the structure of the actomyosin cross-bridges in rabbit and/or frog skeletal muscle fibers in the rigor state have been investigated with improved resolution by x-ray diffraction using synchrotron radiation. The results showed a remarkable structural similarity between cross-bridge states induced by stretch and MgADP binding. The intensities of the 14.4- and 7.2-nm meridional reflections increased by approximately 23 and 47%, respectively, when 1 mM MgADP was added to the rigor rabbit muscle fibers in the presence of ATP-depletion backup system and an inhibitor for muscle adenylate kinase or by approximately 33 and 17%, respectively, when rigor frog muscle was stretched by approximately 4.5% of the initial muscle length. In addition, both MgADP binding and stretch induced a small but genuine intensity decrease in the region close to the meridian of the 5.9-nm layer line while retaining the intensity profile of its outer portion. No appreciable influence was observed in the intensities of the higher order meridional reflections of the 14.4-nm repeat and the other actin-based reflections as well as the equatorial reflections, indicating a lack of detachment of cross-bridges in both cases. The changes in the axial spacings of the actin-based and the 14.4-nm-based reflections were observed and associated with the tension change. These results indicate that stretch and ADP binding mediate similar structural changes, being in the correct direction to those expected for that the conformational changes are induced in the outer portion distant from the catalytic domain of attached cross-bridges. Modeling of conformational changes of the attached myosin head suggested a small but significant movement (about 10-20 degrees) in the light chain-binding domain of the head toward the M-line of the sarcomere. Both chemical (ADP binding) and mechanical (stretch) intervensions can reverse the contractile cycle by causing a backward movement of this domain of attached myosin heads in the rigor state.

Complete rectal prolapse: evolution of management and results

Optional treatment for complete rectal prolapse remains controversial.

PURPOSE

We reviewed our experience over a 19-year period to assess trends in choice of operation, recurrence rates, and functional results.

METHODS

We identified 372 patients who underwent surgery for complete rectal prolapse between 1976 and 1994. Charts were reviewed and follow-up (median, 64: range, 12-231 months) was obtained by mailed questionnaire (149 patients; 40 percent) and telephone interview (35 patients; 9 percent). Functional results were obtained from 184 responders (49 percent).

RESULTS

Median age of patients was 64 (11-100) years, and females outnumbered males by nine to one. One-hundred and eighty-eight patients (51 percent) were lost to follow-up; 183 patients (49 percent) underwent perineal rectosigmoidectomy, and 161 patients (43 percent) underwent abdominal rectopexy with bowel resection. The percentage of patients who underwent perineal rectosigmoidectomy increased from 22 percent in the first five years of the study to 79 percent in the most recent five years. Patients undergoing perineal rectosigmoidectomy were more likely to have associated medical problems as compared with patients undergoing abdominal rectopexy (61 vs. 30 percent, P = 0.00001). There was no significant difference in morbidity, with 14 percent for perineal rectosigmoidectomy vs. 20 percent for abdominal rectopexy. Abdominal procedures were associated with a longer length of stay as compared with perineal rectosigmoidectomy (8 vs. 5 days, P = 0.001). Perineal procedures, however, had a higher recurrence rate (16 vs. 5 percent, P = 0.002). Functional improvement was not significantly different, and most patients were satisfied with treatment and outcome.

CONCLUSIONS

We conclude that abdominal rectopexy with bowel resection is associated with low recurrence rates. Perineal rectosigmoidectomy provides lower morbidity and shorter length of stay, but recurrence rates are much higher. Despite this, perineal rectosigmoidectomy has appeal as a lesser procedure for elderly patients or those patients in the high surgical risk category. For younger patients, the benefits of perineal rectosigmoidectomy being a lesser procedure must be weighed against a higher recurrence rate.Patient satisfaction]

Value of ICAM-1 expression and soluble ICAM-1 level as a marker of activity in sarcoidosis

BACKGROUND

The natural course of sarcoidosis is variable, but no single parameter has been generally accepted as a good marker for disease activity. Adhesion molecules are required for the migration of inflammatory cells; thus, they may be markers of activity in sarcoidosis.

METHODS

In 16 patients with active sarcoidosis and 11 with inactive disease (10 were male, 17 were female; mean age [-/+ SD], 39.6+/-11.0 years; mean follow-up, 21+/-16 months), the expression of adhesion molecules on cells obtained with BAL (measured by flow cytometry) and the level of soluble intercellular adhesion molecule 1 (sICAM-1) in the serum and BAL fluid (BALF) were measured at the time of diagnosis and during the follow-up. The changes in serum sICAM-1 level and ICAM-1 expression on cells obtained with BAL were compared with the clinical course of the disease.

RESULTS

In patients with active disease, the ICAM-1 on alveolar macrophage (AM) (relative linear median fluorescence intensity [RMFI], 3.21+/-1.55) and sICAM-1 levels in serum (575+/-221 ng/mL) and BALF (47.3+/-19.3 ng/mL) were higher than those for patients with inactive disease (RMFI, 1.67+/-0.66; p = 0.0034; serum, 263+/-98.5 ng/mL; p = 0.0001; BALF, 27.5+/-19.0 ng/mL; p = 0.0209). In the patients with active disease, ICAMN-1 on AM and serum sICAM-1 decreased (RMFI, 1.51+/-0.84; 284+/-118 ng/mL, respectively) after steroid therapy, but no significant change was noted in patients with inactive disease. We also found that the initial ICAM-1 on AM and serum sICAM-1 had a significant correlation with the degree of improvement in pulmonary function tests after the therapy. The disease relapsed in four patients after the discontinuation of steroids, and the serum sICAM-1 level was elevated again at the time of relapse.

CONCLUSION

Our data suggest that the serum sICAM-1 level and the ICAM-1 expression on AM may be good markers of disease activity and also a predictor of outcome in sarcoidosis.

Cloning, expression, and characterization of a cDNA encoding snake venom metalloprotease

A cDNA clone, MT-c, encoding metalloprotease was isolated from snake (Agkistrodon halys brevicadus) venom gland cDNA library. Deduced amino acid sequence indicated that MT-c is composed of a signal sequence, amino-terminal propeptide, a central metalloprotease domain, and a Lys-Gly-Asp (KGD) disintegrin domain. The partial cDNA encoding metalloprotease and disintegrin domain was subcloned and expressed in E. coli. The expressed MT-c protein was purified and successfully refolded into functional form retaining the enzyme activity. Analyses of the purified recombinant protease activity revealed that the enzyme hydrolyzes extracellular matrix proteins including type I gelatin, type IV and type V collagen, while type I, II, III collagens and fibronectin were insensitive to the proteolytic digestion. The recombinant enzyme was also able to degrade fibrinogen by specifically cleaving A alpha chain of the protein.

Stimulatory effect of leukemia inhibitory factor on ACTH secretion of dispersed rat pituitary cells

Cytokines are recognized to play an important role in modulating the immune and neuroendocrine system. We recently reported leukemia inhibitory factor (LIF) increased ACTH secretion and pro-opiomelanocortin mRNA level in the murine corticotroph tumor cell line (AtT-20). In this study, the expression of LIF in normal rat pituitary could be demonstrated by ribonuclease protection assay. LIF (1 nM) caused a slight, but significant increase in ACTH secretion (43.7% increase versus control, P<0.01), while showing statistically no significant change of growth hormone and prolactin level in dispersed rat pituitary cells. CRH (10 nM) also induced ACTH secretion 2.5-fold (P<0.01), and co-treatment of LIF and CRH exhibited 2.8-fold increase of ACTH secretion but no statistical difference from CRH treated group. These findings suggest that LIF also has same enhancing effect of ACTH secretion in primary pituitary cultured cells of rat as in AtT-20 cell and LIF acts as a paracrine or autocrine factor to modulate neuroendocrine function in the pituitary.

Advanced method for determination of omeprazole in plasma by HPLC

An advanced and sensitive high-performance liquid chromatographic (HPLC) method for determination of omeprazole in human plasma has been developed. After omeprazole was extracted from plasma with diethylether, the organic phase was transferred to another tube and trapped back with 0.1 N NaOH solution. The alkaline aqueous layer was injected into a reversed-phase C8 column. Lansoprazole was used as an internal standard. The mobile phase consisted of 30% of acetonitrile and 70% of 0.2 M KH2P04, pH 7.0. Recoveries of the analytes and internal standard were >75.48%. The coefficients of variation of intra- and inter-day assay were <5.78 and 4.59% for plasma samples. The detection limit in plasma was 2 ng/ml. The clinical applicability of this assay method was evaluated by determining plasma concentration-time courses of the respective analytes in 24 healthy volunteers after oral administration 40 mg of omeprazole. The present assay is considered to be simple, accurate, economical and suitable for the study of the kinetic disposition of omeprazole in the body.

Comparison of the apoptotic pathways induced by L-amino acid oxidase and hydrogen peroxide

We have found that L-amino acid oxidase (LAO) induces apoptosis in several cultured cell lines by generating H2O2 [Suhr, S.M. and Kim, D.S. (1996) Biochem. Biophys. Res. Commun. 224, 134-139]. It is demonstrated in the present work that the LAO-induced apoptotic mechanism is clearly distinguished from the one stimulated directly by exogenous H2O2. MOLT-4 cells undergo somewhat different morphological changes depending on the apoptotic inducer, LAO or H2O2. LAO-induced apoptosis can be protected by the antioxidant N-acetylcysteine or the free radical scavenger melatonin, while H2O2-induced apoptotic cell death is not protected. A caspase inhibitor, acetyl-Tyr-Val-Ala-Asp-aldehyde (ac-YVAD-aldehyde), prevents cell death when the apoptosis is induced by exogenous H2O2. On the other hand, the ac-YVAD-aldehyde tetrapeptide inhibitor that is dominantly effective on interleukin-1beta converting enzyme failed to block the apoptotic event initiated by LAO. Several lines of experimental evidence suggest that apoptotic cell death induced by LAO is not due solely to the hydrogen peroxide produced by the enzymatic reaction.

Theory of projection onto the narrow quantization constraint set and its application

Since the postprocessing of coded images using a priori information depends on the constraints imposed on the coded images, it is important to utilize constraints that are best suited to postprocessing techniques. Among the constraint sets, the quantization constraint set (QCS) is commonly used in the iterative algorithms that are especially based on the theory of projections onto convex sets (POCS). The converged image in the iteration is usually a boundary point of the QCS. But, we can easily conjecture that the possible location of the original image is inside the QCS. In order to obtain an image inside the QCS, we proposed a new convex constraint set, a subset of the QCS called narrow QCS (NQCS) as a substitute for the QCS. In order to demonstrate that the NQCS works better than the QCS on natural images, we present mathematical analysis with examples and simulations by reformulating the iterative algorithm of the constrained minimization problem or of the POCS using the probability theory. Since the initial image of the iteration is the centroid of the QCS, we reach a conclusion that the first iteration is enough to recover the coded image, which implies no need of any theories that guarantee the convergences.

The fusion gene at the ABO-secretor locus (FUT2): absence in Chinese populations

The fusion gene (se(fus)) is a null allele of the secretor type alpha (1, 2) fucosyltransferase gene (FUT2) and was first found in a Japanese population. It has not yet been reported in any other ethnic population. In the present study, we investigated the distribution of the fusion gene of the FUT2 locus in five populations from three ethnic groups in East Asia. The fusion gene was found in two additional Japanese populations with a high frequency (0.0551 in Okinawa and 0.0792 in Akita) and, for the first time outside Japan, in a Korean population, at a very low frequency (0.0063 in Seoul). In contrast, we found no fusion gene in two Chinese populations. These findings showed that the FUT2 fusion gene was ubiquitous in Japanese, but was rare in neighboring populations, suggesting that the FUT2 fusion gene had emerged from within the Japanese. Additionally, a new null allele with a C-to-T substitution at nucleotide 658 was found in one individual native of southern China.

A comparative study on Pb2+ accumulation between Saccharomyces cerevisiae and Aureobasidium pullulans by SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-Ray) analyses

Scanning electron microscopy and energy dispersive X-ray analyses were carried out in a comparative investigation of Pb(2+) accumulation in Saccharomyces cerevisiae and Aureobasidium pullulans. In S. cerevisiae, the time required to reach an equilibrium state was shortened from 100 h to 1 h as the initial Pb(2+) concentration decreased from 96.5 mg/l to 16.0 mg/l, whereas the time was almost independent of initial Pb(2+) concentration in A. pullulans. Concomitant with the Pb(2+) accumulation, the cell surface of S. cerevisiae became rough and the amounts of potassium, phosphorus and sulfur on the cell surface decreased. However, significant increase of Pb(2+) on the cell surface after Pb(2+) accumulation was not observed due to Pb(2+) penetration into the cell interior. In contrast, the Pb(2+) accumulation had no significant effect on the surface characteristics of A. pullulans and extreme Pb(2+) accumulation was observed on the cell surface because Pb(2+) could not penetrate into the cell interior due to the existence of extracellular polymeric substances.

Respiratory and haemodynamic effects of the prone position at two different levels of PEEP in a canine acute lung injury model

This study was designed to examine whether the oxygenation response in the prone position differs in magnitude depending on the level of positive end-expiratory pressure (PEEP) applied in the supine position, and whether cardiac output (CO) increases in the prone position. In seven supine dogs, acute lung injury was established by saline lavage (arterial oxygen tension (Pa,O2)/inspiratory oxygen fraction (FI,O2) 17.8+/-9.6 kPa (134+/-72 mmHg)), and inflection point (Pflex) of the respiratory system was measured (6.6+/-1.4 cmH2O). Pa,O2/FI,O2 and CO of the supine and prone positions were obtained under the application of low PEEP and then under optimal PEEP (2 cmH2O below and above Pflex, respectively). The net increase in Pa,O2/FI,O2 by prone positioning was greater at low PEEP (27.3+/-12.0 kPa (205+/-90 mmHg)) than at optimal PEEP (4.4+/-13.0 kPa (33+/-98 mmHg)) (p=0.006). CO decreased significantly with optimal PEEP in the supine position (2.4+/-0.5 versus 3.1+/-0.4 L x min(-1) at baseline, p<0.001), and increased to 3.4+/-0.6 and 3.6+/-0.7 L x min(-1) in the prone position at 5 min and 30 min, respectively (both p=0.018). When the dogs were turned supine at optimal PEEP, CO again decreased (2.4+/-0.5 L x min(-1), p<0.001). In conclusion, the prone position augmented the effect of relatively low positive end-expiratory pressure on oxygenation, and attenuated the haemodynamic impairment of relatively high positive end-expiratory pressure in a canine acute lung injury model.

A Mg(2+)-dependent endonuclease is responsible for internucleosomal DNA fragmentation in human B lymphoblastic IM9 cells

We have identified a Mg(2+)-dependent endonuclease activity from human B lymphoblastic IM9 cell lysates and nuclei using autodigestion method and DNA-native-polyacrylamide gel electrophoresis (DNA-native-PAGE) nuclease assay system. The level of the endonuclease activity in cell lysates was significantly decreased at certain stage by treatment of the cells with cycloheximide. However, the enzyme activity consistently remained for over 12 hours in the isolated nuclei of the apoptotic IM9 cells. The Mg(2+)-dependent endonuclease isolated from the nuclei by native-PAGE elution was able to catalyze the conversion of supercoiled plasmid DNA into linear form. This particular endonuclease activity was not detected in cycloheximide treated-U937 cells. Several lines of experimental evidence suggest that the Mg(2+)-dependent endonuclease localized in the nucleus may be responsible for the DNA fragmentation of apoptotic IM9 cells.