Comparative effects of dietary nucleoside-nucleotide mixture and its components on endotoxin induced bacterial translocation and small intestinal injury in protein deficient mice

BACKGROUND

Nucleoside-nucleotide mixture has been shown to improve gut morphology and reduce the incidence of bacterial translocation in protein deficient mice.

AIMS

To compare the reparative effect of nucleoside-nucleotide mixture and their individual components on maintenance of gut integrity and bacterial translocation based on their differential metabolism and utilisation.

METHODS

ICR (CD-1) mice were randomised into eight groups of 10 animals each and fed 20% casein diet (control), protein free diet, or protein free diet supplemented with 3 M cytidine, uridine, thymidine, inosine, guanosine monophosphate, or nucleoside-nucleotide mixture for four weeks. On the fourth week, each mouse was injected lipopolysaccharide intraperitoneally (50 micrograms/500 microliters) and the incidence of bacterial translocation, caecal bacterial populations, and the ileal histology, noted 48 hours later.

RESULTS

The death rate in the control group was 40% compared with 10% in the nucleoside-nucleotide mixture and 20% each in the individual components groups, respectively. Bacterial translocation to the mesenteric lymph node did occur in 100% of the surviving mice fed the control diet in comparison with 44% (nucleoside-nucleotide), 50% (cytidine), 75% (thymidine), 75% (uridine), 63% (inosine), and 63% (guanosine monophosphate). Histologically, the damage to the gut was more distinct in the protein free diet group. Villous height, crypt depth, and wall thickness in the nucleoside-nucleotide mixture group mean (SEM) (5.01 (0.34); 0.87 (0.14); 0.33 (0.10)), were respectively, higher compared with the protein free diet (3.34 (0.34); 0.61 (0.03); 0.18 (0.04)) group. In the cytidine group, crypt depth (0.86) (0.08)), and wall thickness (0.30 (0.002)) were higher. The same measurements in the components groups tended to be higher than the protein free diet group. Caecal bacterial populations were, however, similar in all groups.

CONCLUSIONS

These results suggest that dietary nucleosides and nucleotides are essential nutrients for intestinal repair; nucleotides or cytidine provide a better response.

[Mutations of hMSH2 gene and hMLH1 gene in human colovectal carcinomas]

Mutations of the hMSH2 and hMLH1 mismatch repair system genes in hereditary non-polyposis colorectal cancer (Lynch) syndrome as well as sporadic colorectal cancers with microsatellite instabilities are overviewed. Alterations of genes involved in DNA repair would be the cause of genetic instability, increase of mutation rate as well as elevation of cancer risk. In addition, the recent topics of frequent association of TGF-beta type II receptor gene insertion/deletion mutation and replication error positive colorectal cancers are also discussed.

Phylogenetic analysis of Acinetobacter strains based on the nucleotide sequences of gyrB genes and on the amino acid sequences of their products

Partial nucleotide sequences of the gyrB genes (DNA gyrase B subunit genes) of 15 Acinetobacter strains, including the type and reference strains of genomic species 1 to 12 (A. calcoaceticus [genomic species 1], A. baumannii [genomic species 2], Acinetobacter genomic species 3, A. haemolyticus [genomic species 4], A. junii [genomic species 5], Acinetobacter genomic species 6, A. johnsonii [genomic species 7], A. lwoffii [genomic species 8], Acinetobacter genomic species 9, Acinetobacter genomic species 10, Acinetobacter genomic species 11, and A. radioresistens [genomic species 12]), were determined by sequencing the PCR-amplified fragments of gyrB. The gyrB sequence homology among these Acinetobacter strains ranged from 69.6 to 99.7%. A phylogenetic analysis, using the gyrB sequences, indicates that genomic species 1, 2, and 3 formed one cluster (87.3 to 90.3% identity), while genomic species 8 and 9 formed another cluster (99.7% identity). These results are consistent with those of DNA-DNA hybridization and of biochemical systematics. On the other hand, the topology of the published phylogenetic tree based on the 16S rRNA sequences of the Acinetobacter strains was quite different from that of the gyrB-based tree. The numbers of substitution in the 16S rRNA gene sequences were not high enough to construct a reliable phylogenetic tree. The gyrB-based analysis indicates that the genus Acinetobacter is highly diverse and that a reclassification of this genus would be required.

[Pulmonary artery banding using expanded polytetrafluoroethylene suture]

Pulmonary artery banding (PAB) is essential for infants of complicated cardiac anomaly without pulmonary stenosis, especially those who require future Fontan type correction. In order to avoid pulmonary artery branch stenosis or uneven growth we utilize expanded polytetrafluoroethylene (E-PTFE) suture (Gore-Tex suture, CV-0) as a banding material. We performed three PABs (two newborns and one infant) with this suture. All children were doing well after the banding and no one revealed residual pulmonary hypertension or pulmonary artery distortion in the postoperative catheter study. One patient successfully underwent total cavopulmonary connection eight months after PAB. We believe E-PTFE suture is an advantageous material of PAB for newborns and young infants.

Nitric oxide induction by pertussis toxin in mouse spleen cells via gamma interferon

We examined the major pathogenic substances of Bordetella pertussis for the ability to induce nitric oxide, and important biological function of macrophages, via gamma interferon in spleen cells. B. pertussis, which produces a variety of pathogenic substances, including pertussis toxin and filamentous hemagglutinin, causes a severe respiratory disease. Nitric oxide was detected in the culture fluid of spleen cells stimulated with pertussis toxin or its B oligomer but not in the culture fluid of spleen cells stimulated with the A protomer of pertussis toxin or with filamentous hemagglutinin. Incubation of the peritoneal exudate macrophages with pertussis toxin, B oligomer, A protomer, or filamentous hemagglutinin induced little nitric oxide, whereas incubation with gamma interferon induced a significant amount of nitric oxide. The induction of nitric oxide in spleen cells stimulated with pertussis toxin was completely inhibited by anti-gamma interferon antibody. The treatment of spleen cells with anti-Thy-1.2 antibody plus complement followed by stimulation with pertussis toxin decreased the secretion of gamma interferon and nitric oxide. These results suggest that gamma interferon from T lymphocytes stimulated with pertussis toxin induces nitric oxide.

[Observation of relation between object size or length and count rate for 3D PET]

We obtained the concentration range of better S/N in 3D than 2D acquisition by measuring count rate for phantoms of different size and length. We used noise equivalent count rate (NECR) for evaluation of S/N of images. For 20 cm diameter 15 cm length cylindrical phantom, NECR of 2D was higher than that of 3D more than 1.2 microCi/ml. For 30 cm diameter 15 cm length cylindrical phantom, NECR of 2D was higher than that of 3D more than 0.7 microCi/ml. For 14 cm diameter 25 cm length cylindrical phantom, NECR of 3D was lower than that of 25 cm length phantom. With these results, though 3D is useful when administered dose is small, image quality of 2D becomes better than 3D more than a certain concentration. For the larger diameter or longer object, the advantage of 3D is diminished at lower concentration.

Effect of egg white on serum cholesterol concentration in young women

In a previous study we observed favorable effects of egg white on serum lipids in rats and mice. The present study was designed to elucidate these effects in 24 female university students with moderate hypercholesterolemia. About 30% of total protein was supplied with egg white, tofu or cheese. The experiment was conducted for a complete menstruation cycle of each subject. Lipid intake was about 30% of total energy intake. The energy intake of each subject was constant throughout the experiment. Body weight was measured every morning. Daily activity was measured by a pedometer. Blood was withdrawn after an overnight fast on the first, 15th and last days and serum lipids were measured. Body weight was measured every morning. Daily activity was measured by a pedometer. Blood was withdrawn after an overnight fast on the first, 15th and last days and serum lipids were measured. Body weight and daily activity were maintained in all the groups throughout the experiment. The egg white group showed a similar decrease in the total cholesterol (Total-C) concentration but a greater increase of high-density lipoprotein cholesterol (HDL-C) concentration as compared to the tofu group and a greater decrease in Total-C and low-density lipoprotein cholesterol (LDL-C) concentrations and a greater increase in the HDL-C concentration as compared to the cheese group (p < 0.05). The results indicate the favorable effects of egg white in the control of hypercholesterolemia.

Synthesis and biological activity of novel 1,3-benzoxazine derivatives as K+ channel openers

A new series of 1,3-benzoxazine derivatives with a 2-pyridine 1-oxide group at C4 was designed to explore novel K+ channel openers. Synthesis was carried out by using a palladium(0)-catalyzed carbon-carbon bond formation reaction of imino-triflates with organozinc reagents and via a new one-pot 1,3-benzoxazine skeleton formation reaction of benzoylpyridines. The compounds were tested for vasorelaxant activity in tetraethylammonium chloride (TEA) and BaCl2-induced and high KCl-induced contraction of rat aorta to identify potential K+ channel openers, and also for oral hypotensive effects in spontaneously hypertensive rats. An electron-withdrawing group with the proper shape at C6 and a methyl or halogeno group at C7 of the 1,3-benzoxazine nucleus were required for the development of optimal vasorelaxant and hypotensive activity. In particular, 2-(6-bromo-7-chloro-2,2-dimethyl-2H-1,3-benzoxazin-4-yl)pyridine 1-oxide (71) showed more potent vasorelaxant activity (EC50 = 0.14 microM) against TEA and BaCl2-induced contraction and longer-lasting hypotensive effects than cromakalim (1).

Time limitation of postural retrograde cerebral perfusion during cerebral hypothermic circulatory arrest. A report of an unsuccessful case

We report an unsuccessful case with ruptured aortic arch aneurysm using deep hypothermia with postural retrograde cerebral perfusion by simply elevating central venous pressure in the Trendelenburg position. Ninety-three minutes of cerebral circulatory arrest by this method caused irreversible global cerebral damage. Ninety minutes may be over the time limit of this method.

Plasminogen activator activity in the bovine oocyte-cumulus complex and early embryo

In this study fibrinolytic assay systems were used to assess the plasminogen activator (PA) potential and plasmin generating ability of oocyte-cumulus complexes isolated from preovulatory bovine follicles (2-8 mm diameter) and of fertilized oocytes from the day of fertilization up to, and including, the hatched blastocyst stage (day 12). During embryo development, the culture medium was changed every 24 hr and samples examined for PA activity. Irrespective of the stage of maturity, no plasminogen or PA could be detected in unfertilized oocytes from which the cumulus layer had been removed. Both plasminogen and PA were found in the cumulus layer indicating that this, rather than the oocyte, was the source of these proteins in the oocyte-cumulus complex. Following oocyte fertilization, no PA activity was detected in either the developing embryo or in the culture medium before day 7. When the embryos had developed to the expanded blastocyst stage, days 7-8, PA production began with activity being detected in both the embryos and their culture medium. Between days 8 and 12, when embryos had reached the hatched blastocyst stage, the PA activity had increased significantly (p<0.05). Analysis of the culture media confirmed this increase in production of PA activity and, based on zymography, it was estimated that the molecular weight of the PA was 78 k daltons.

Resistance to endotoxin shock and reduced dissemination of gram-negative bacteria in CD14-deficient mice

Endotoxin shock is the result of activation of the immune system by endotoxin/LPS, a component of Gram-negative bacteria. CD14, a GPI-anchored glycoprotein expressed strongly by monocyte/macrophages, is one of several receptors for endotoxin/LPS. The role of CD14 in bacterial-induced and LPS-induced shock was tested in CD14-deficient mice produced by gene targeting in embryonic stem cells. CD14-deficient mice were found to be highly resistant to shock induced by either live Gram-negative bacteria or LPS; however, at very high concentrations of LPS or bacteria, responses through non-CD14 receptors could be detected. Surprisingly, CD14-deficient mice also showed dramatically reduced levels of bacteremia, suggesting an unexpected role for CD14 in the dissemination of Gram-negative bacteria.

Suicide inactivation of porcine leukocyte 12-lipoxygenase associated with its incorporation of 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid derivative

Two isozymes of arachidonate 12-lipoxygenase, platelet-type and leukocyte-type, which were distinguished by their substrate specificities and primary structures, were investigated with reference to 'suicide' inactivation. Upon reaction with arachidonic acid the leukocyte-type enzyme was inactivated rapidly during the catalysis, whereas the platelet-type enzyme did not show such a rapid inactivation. The two 12-lipoxygenase isozymes were incubated with various hydroperoxy and hydroxy products from arachidonic acid. (15S)-Hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) was found to be a unique substrate of the leukocyte-type 12-lipoxygenase as follows. (1) 15-HPETE was an active substrate for porcine leukocyte 12-lipoxygenase, and converted anaerobically to a 14,15-epoxy compound (14,15-leukotriene A4). (2) A rapid inactivation of the enzyme was observed within 2 min upon aerobic and anaerobic incubations with 15-HPETE. (3) 15-HPETE was rapidly incorporated into the enzyme in a nearly equimolar amount under both aerobic and anaerobic conditions. (4) Several findings suggested a covalent binding of 15-HPETE or its derivative to the enzyme. (5) Such a rapid and stoichiometric incorporation of 15-HPETE was not observed with the platelet-type 12-lipoxygenase. On the basis of these findings we presumed that 15-HPETE was transformed to 14,15-leukotriene A4, which was covalently bound to the leukocyte-type 12-lipoxygenase leading to the suicide inactivation of the enzyme.

[An immunohistochemical study of proliferating cell nuclear antigen (PCNA) and MIB-1 in epithelial hyperplasia and dysplasia of the vocal cords]

We investigated the proliferative activities in epithelial hyperplasia and dysplasia of the human vocal cords as precancerous lesions, using immunohistochemical staining with anti-PCNA and MIB-1 (anti-Ki-67) monoclonal antibody. The series for this study consisted of nine patients with hyperplasia, 12 with mild dysplasia, ten with moderate dysplasia, eight with severe dysplasia, eight with vocal cord polyps, and 14 with invasive squamous cell carcinoma. The following results were obtained: 1) The mean PCNA labeling index was 1.12 +/- 1.05 (MEAN +/- STD%) in polyp, 4.88 +/- 2.02 in hyperplasia, 2.76 +/- 1.76 in mild dysplasia, 3.80 +/- 2.03 in moderate dysplasia, 6.12 +/- 3.01 in severe dysplasia, and 19.07 +/- 10.37 in invasive cancer. 2) The mean MIB-1 positive rates were 5.50 +/- 2.47 (MEAN +/- STD%) in polyp, 13.08 +/- 6.86 in hyperplasia, 16.55 +/- 7.34 in mild dysplasia, 15.94 +/- 6.73 in moderate dysplasia, 21.43 +/- 8.16 in severe dysplasia, and 41.48 +/- 14.05 in invasive cancer. In cases of hyperplasia, dysplasia and invasive cancer, PCNA labeling index values and MIB-1 positive rates increased in proportion to the histological atypical grade increasing. Some lesions which recurred or progressed to cancer were found show high expression of PCNA and MIB-1. In cancer cases, there was no significant correlation between the PCNA labeling index, MIB-1 positive rates and either the degree of tumor cell differentiation or the T-classification. There was a positive correlation between the PCNA labeling index and MIB-1 positive rates among all cases. In this study, those cases showing a high PCNA labeling index and/or MIB-1 positive rates may indicate the possibility of recurrence or progression to malignancy in precancerous lesions of the vocal cords.

Spontaneous anterior interosseous nerve palsy with hourglass-like fascicular constriction within the main trunk of the median nerve

Interfascicular neurolysis was performed in nine patients with spontaneous anterior interosseous nerve palsy. In eight of these patients, an hourglass-like constriction in the fascicles forming the anterior interosseous nerve was found within the main trunk of the median nerve at 2-7.5 cm above the medial epicondyle. The clinical signs and symptoms of these eight patients were similar to those that have been described to isolated neuritis. While the etiology remains unknown, when spontaneous anterior interosseous nerve palsy is suspected to be caused by isolated neuritis, interfascicular neurolysis should be performed to confirm the lesion and to discover whether fascicular constriction is present.

[In vitro antimycobacterial activities of pyrazinamide analogs: results of screening tests]

Attempting to find new drugs, which are more effective than pyrazinamide against Mycobacterium tuberculosis and also active against M. avium complex (MAC), we synthesized various pyrazinamide analogs and pyrazine derivatives and assayed their antimycobacterial activities in vitro against M. tuberculosis, M. avium and M. intracellulare. As is well known, pyrazinamide is more active in acidic medium than in neutral medium, but the growth of mycobacteria in acidic media is poor and inconsistent. Our preliminary experiments revealed that the relative antimycobacterial activities of test-drugs compared with pyrazinamide were essentially the same in pH5.5 medium as in pH6.0 medium. Therefore, Middlebrook 7H9 broth adjusted to pH6.0 was used throughout the present studies. Among 39 compounds synthesized, four drugs were insoluble in any of the solvent suitable for culture experiments and could not be tested, and remaining 35 compounds were screened. The growth of mycobacteria was followed by measuring the optical density at 530 nm (OD), and the OD of the culture in the presence of 200 micrograms/ml of the test-drug (OD-TD) was compared with that in the presence of pyrazinamide (OD-PZA). Each test-drug was ranked as A, B, C, D or E according to the ratio (OD-TD/OD-PZA) x 100%, if the ratio was equal to or less than 10%, 11-20%, 21-40%, 41-60% or 61-80%, respectively. Any drugs showing the ratio above 80% were excluded from further examinations. For M. tuberculosis, 11 drugs were ranked as A and 4 more as B. For M. avium, 2 drugs were ranked as A and 2 more as B. For M. intracellulare, 5 drugs were ranked as A and 2 more as B. Among highly ranked ones, 4 compounds, namely, pyrazinoic acid noctyl ester, pyrazinoic acid pivaloyloxymethyl ester, pyrazine thiocarboxamide and N-hydroxymethyl pyrazine thiocarboxamide were ranked as A against M. tuberculosis and M. intracellulare, and ranked as A, B or C against M. avium, and considered as hopeful candidates of new antimycobacterial drugs. Their bacteriostatic and bacteriocidal activities against M. tuberculosis as well as M. avium and M. intracellulare have been studied in details and reported in a separate paper. In vivo activities against murine experimental tuberculosis of these 4 drugs is now under investigation. Further, two drugs, N-hydroxy pyrazinamide and N-hydroxy pyrazinamide-4-oxide were ranked as A against M. tuberculosis and ranked A or B against M. intracellulare, and their more precise in vitro antimycobacterial activities are now under examination.

Generation of new intercellular junctions between cardiocytes. A possible mechanism compensating for mechanical overload in the hypertrophied human adult myocardium

Intercellular dehiscence is a common cardiocytic response to pathological conditions. However, little consideration has been given to the possibility of new intercellular junctions developing between cardiocytes within developed myocardium. To examine this possibility as it may relate to useful compensation for hemodynamic overloads, changes in cardiocytic connection were evaluated by scanning electron microscopy in hypertrophied myocardium of adult human hearts. Transmural myocardium of left ventricle was obtained at autopsy from five hearts with concentric hypertrophy, five hearts with eccentric hypertrophy, and five control hearts (noncardiac death). After formalin fixation, the number of cardiocytes connected to an individual cardiocyte was counted in tissues from the middle portion of the transmural samples by scanning electron microscopy. Cardiocytic diameter and connective tissue volume fraction were measured on the transmural sections by light microscopy. In concentrically hypertrophied hearts present both increased cardiocytic diameter and connective tissue volume fraction, the number of other cardiocytes connected to an individual cardiocyte (4.60 +/- 0.10 [mean +/- SE] was significantly increased (P < .05) compared with control hearts (4.19 +/- 0.12) or eccentrically hypertrophied hearts (4.11 +/- 0.10). The increase in junctions per cardiocyte in concentrically hypertrophied hearts suggests that new connections had been generated. More junctions developing during hypertrophy could add another structural advantage to those of cardiocytic hypertrophy and connective tissue proliferation as compensatory adjustments to hemodynamic overload in concentrically hypertrophied hearts.

Immunohistochemically demonstrated variation in expression of cathepsin E between uracil-induced papillomatosis and N-butyl-N-(4-hydroxybutyl)nitrosamine-induced preneoplastic and neoplastic changes in rat urinary bladder

Expression of rat urinary bladder cathepsin E in benign papillomatosis induced by uracil and various stages of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced carcinogenesis was investigated immunohistochemically. Seven-week-old, male F344/DuCrj rats were used. In the normal urothelium of control rats, cathepsin E stained in all layers of cells, although in umbrella cells and some basal cells the reaction was relatively weak. In rats given a diet containing 3% uracil for 5 weeks immunoreactivity of cathepsin E in uracil-induced papillomatosis was consistently homogeneous in all layers, but weaker than in normal urothelium. In rats given 0.05% BBN in drinking water for 12 weeks and subsequently maintained without treatment for 48 weeks cells with little cathepsin E, never observed in normal urothelium, appeared at 5 weeks above the basement membrane in the earliest stage of BBN-induced urinary bladder cancer (simple hyperplasia). Throughout the neoplastic process, groups of cells with a little cathepsin E were randomly distributed, with expression in the urothelium being markedly unstable. Almost all areas of squamous cell proliferation in TCC were negative for cathepsin E. Instability of cathepsin E expression in rat urothelium therefore appears characteristic for carcinogenesis and offers the possibility of using this feature as an early biomarker for urinary bladder carcinogenesis.

[Proteoglycan molecules in scleral tissue of enlarged eyeball]

We studied scleral specimens from experimentally induced enlarged eyeball with axial elongation by the transmission electron microscopy following cationic dye (cuplonic blue) staining. The animal model was prepared by the injection of alpha-chymotrypsin into the posterior chamber of young albino rabbits. Cuprolinic blue staining was applied to scleral specimens obtained from equatorial lesion and portions of the scleral tissues were subjected to enzyme digestion by chondroitinase ABC, AC and B before cuprolinic blue staining. In control eyes, dermatan and chondroitin type sulfated proteoglycan filaments were identified. Large, electron dense, and abnormal by shaped proteoglycan filaments were seen in the transmission electron microscopy. Such abnormal proteoglycan filaments were susceptible to enzyme chondroitinase ABC and AC digestion but resistant to chondroitinase B, suggesting that they are chondroitin sulfate dominant proteoglycans. Our morphological data corroborated a previous biochemical report of abnormally induced proteoglycan molecules in sclera with enlarged, axially elongated eyes.

Pancreatic juice output after pancreatoduodenectomy in relation to pancreatic consistency, duct size, and leakage

BACKGROUND

A soft pancreas with a main pancreatic duct (MPD) with normal diameter has been considered a high risk for pancreatic anastomotic leakage because of a relatively high output of pancreatic juice, but data are lacking.

METHODS

An attempt was made to assess the relationship between the consistency of the pancreas, MPD diameter, pancreatic juice output, and pancreatic leakage after partial pancreatoduodenectomy. The pancreatic parenchyma was classified as of soft, intermediate, and hard consistency in 70 consecutive patients undergoing operation (groups 1, 2, and 3, respectively) by one surgeon. The MPD diameter was determined by means of endoscopic pancreatography or abdominal ultrasonography. Pancreatic juice output was measured for 21 days after operation by using a catheter inserted into the MPD. Anastomotic leakage was identified radiologically by using contrast medium.

RESULTS

The mean (SD) pancreatic juice output during a period of 10 days (postoperative days 5 to 14) was 1554 (1073) ml in group 1 (n = 29), 1513 (1060) ml in group 2 (n = 13), and 187 (220)ml in group 3 (n = 28) (groups 1 and 2 versus group 3, p < 0.0001). The MPD diameter was 3.0 (1.6) mm in group 1, 5.9 (2.5) mm in group 2, and 6.6 (2.6) mm in group 3 (group 1 versus groups 2 and 3, p = 0.0001). Anastomotic leaks occurred in four (14%) patients in group 1, three (23%) in group 2, and none in group 3 (p < 0.05).

CONCLUSIONS

Patients with a pancreatic parenchyma with an intermediate or normal consistency produced more pancreatic juice and had a higher leak rate.

[Suspension of ventilation during extracorporeal membrane oxygenation with veno-venous by pass in dogs]

We studied whether extracorporeal membrane oxygenation with a veno-venous bypass would allow withdrawal of mechanical ventilation. Three mongrel dogs were anesthetized with intravenous pentobarbital. A Swan-Ganz catheter was placed via the left jugular vein into the main pulmonary artery, and an extra-long total volume catheter was placed in the right femoral artery. The animals were placed in the lateral position, and cannulas (15 Fr.) were placed in the inferior vena cava and the superior vena cava via the right jugular vein and the right femoral vein. These cannulas were connected to a pump and a membrane oxygenator. When the pump flow was almost the same as the previous cardiac output, the partial pressure of oxygen in the pulmonary artery, was high enough to allow ventilation to be suspended. All dogs survived. This suggests that extracorporeal membrane oxygenation with a veno-venous bypass can allow mechanical ventilation to be suspended during tracheocarinal operations such as tracheocarcinal resection.

Modulation of pump function by mutations in the first transmembrane region of Na(+)-K(+)-ATPase alpha 1-subunit

The Cys in the first transmembrane region of the Na(+)-K(+)-adenosinetriphosphatase (ATPase) alpha 1-subunit has been shown to be a critical determinant of cardiac glycoside binding. To study the role of this Cys on ion transport activity, we measured pump currents in HeLa cells expressing wild-type or mutant alpha 1-subunit cDNAs. The endogenous ouabainsensitive Na(+)-K(+)-ATPase was selectively inhibited by growing the cells in 0.1 microM ouabain. A Cys-to-Tyr substituted mutant exhibited decreased sensitivity to digitoxin but not digoxin compared with wild type. The decreased affinity for digitoxin was due to a faster dissociation rate. In contrast, the Cys-to-Ala substitution did not significantly alter the sensitivity to digitoxin or digoxin. Both wild-type and mutant cells displayed marked external K(+)-dependent pump currents; however, the affinity for K+ was reduced by the mutations. The decrease in K+ affinity was due to a slower association rate. The results show that the Cys that interacts with cardiac glycosides also participates in the sensitivity of the pump to external K+.

Effective isolation of MPB64 from a large volume of culture filtrate of Mycobacterium bovis BCG Tokyo

MPB64, a secretory protein of Mycobacterium bovis BCG Tokyo, was isolated from a culture filtrate of the bacteria in Sauton synthetic medium harvested on day 8. The protein was isolated by five steps; (i) concentration of the culture filtrate by cutting the molecules smaller than 5 kDa with the Millipore Pellicon Cassette system, (ii) affinity separation by a Phenyl Sepharose CL-4B column, (iii) separation with a DEAE-Sepharose CL-6B column with 3 M urea, (iv) separation with a Sephacryl S200HR column, and (v) separation with a DEAE-Sepharose column without urea. MPB64 in each fraction was determined by comparing the band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with that of standard MPB64. The specificity of isolated MPB64 was tested by immunoblotting with anti-MPB64 antibody. The potency of isolated MPB64 in eliciting skin reaction in the BCG-sensitized guinea pigs was the same to that of standard MPB64. The method described herein is an improved one for isolating MPB64 from a large volume of culture filtrate of M. bovis BCG Tokyo. The technique should be applicable to isolation of other mycobacterial secretory proteins.