The healing and tensile strength of the gastroplasty staple line. An experimental study

Inverted and everted staple lines, with and without division of the anterior gastric wall, were performed in 15 mongrel dogs to simulate reduction gastroplasty staple line. There were no significant differences in tensile strength and healing between staple lines at different postoperative periods. The tensile strength of the inverted staple line seemed to be stronger due to breakage of the adjacent gastric tissue. However, the tensile strength of the everted stapling without division of the gastric wall, which is used clinically, was almost equal to that of normal gastric tissue. In addition, there was satisfactory healing 4 weeks postoperatively in the everted stapling without dividing the gastric wall. These results suggest that the everted staple line without division of stomach is not inherently weaker to any significant extent than if the gastric wall was divided or inverted. The reported failure rate of this procedure may be due to other factors.

Intestinal valve formation with a simple invagination technique

In 17 fully conditioned mongrel dogs, the small intestine approximately 50 cm proximal to the ileocecal valve was divided. Three centimeters of the proximal bowel was then inserted into the distal bowel and anastomosis was performed using interrupted 3-0 Dexon sutures in the seromuscular layer of the proximal end and through the entire thickness of the distal end. Two to four dogs were then sacrificed 2, 4, 6, 8, and 10 weeks postoperatively. Two dogs died 3 and 4 weeks postoperatively due to mechanical obstruction just proximal to the anastomosis by hair bezoar, and 15 survived without complications. Retrograde contrast radiologic examination of all segments showed no reflux. Microscopically, the serosal surface of the invaginated segment was found to be gradually covered with mucosa, and the whole segment formed a valvelike structure within 10 weeks time.

Electron microscopy of bacteriophage phi 6 nucleocapsid: three-dimensional image analysis

Electron micrographs of bacteriophage phi 6 nucleocapsids, negatively stained by neutralized phosphotungstate and tilted in a goniometer specimen cartridge, proved that the three distinct morphologies seen in the electron microscope are merely three different aspects of a single nucleocapsid structure and strongly suggested that this structure is dodecahedral.

Complement activation by heat-killed human kidney cells: formation, activity, and stabilization of cell-bound C3 convertases

Heat-killed kidney cells (HKKC) incubated with serum or purified C3 and factors B and D stain intensely for C3 by immunofluorescence. Binding of complement (C) did not occur if ethylenediaminetetraacetic acid (EDTA) was added to the C source or if factor B or D was omitted from the mixture of alternative pathway components. When the C-treated cells were washed, then incubated in purified C3 containing 10 mM EDTA, C3 conversion ensued, confirming the presence of a cell-bound C3 convertase. C3-reactive cells were not generated if EDTA was present during formation of the convertase. The addition of C3 nephritic factor (C3NeF) during formation of the C3 convertase from alternative pathway components greatly enhanced subsequent C3 cleavage, presumably by stabilizing labile C3bBb sites; however, binding of C3NeF did not appear to extend the half-life of the convertase, which was 35 min at 37 degrees C in each case. In contrast, little or no effect on C3 conversion could be detected after the addition of equivalent C3NeF to serum and HKKC. Thus, C activation by HKKC involves formation and activity of a cell-bound C3 convertase, which under certain circumstances can be stabilized by C3NeF.

Complement activation by heat-killed human kidney cells: formation, activity, and stabilization of cell-bound C3 convertases

Heat-killed kidney cells (HKKC) incubated with serum or purified C3 and factors B and D stain intensely for C3 by immunofluorescence. Binding of complement (C) did not occur if ethylenediaminetetraacetic acid (EDTA) was added to the C source or if factor B or D was omitted from the mixture of alternative pathway components. When the C-treated cells were washed, then incubated in purified C3 containing 10 mM EDTA, C3 conversion ensued, confirming the presence of a cell-bound C3 convertase. C3-reactive cells were not generated if EDTA was present during formation of the convertase. The addition of C3 nephritic factor (C3NeF) during formation of the C3 convertase from alternative pathway components greatly enhanced subsequent C3 cleavage, presumably by stabilizing labile C3bBb sites; however, binding of C3NeF did not appear to extend the half-life of the convertase, which was 35 min at 37 degrees C in each case. In contrast, little or no effect on C3 conversion could be detected after the addition of equivalent C3NeF to serum and HKKC. Thus, C activation by HKKC involves formation and activity of a cell-bound C3 convertase, which under certain circumstances can be stabilized by C3NeF.

Experimental study of singly placed staples for an everted intestinal anastomosis

This study was undertaken to confirm the technical feasibility and efficacy of an intestinal anastomosis created with singly placed staples in dogs. In 12 fully conditioned dogs, two end-to-end small bowel anastomoses were performed in an everted manner. In each dog, one anastomosis was performed with singly placed staples utilizing the Auto Suture 4.8 mm disposable skin stapler, and the other anastomosis was performed with a manual technique using 3-0 Dexon interrupted suture. Operation time was measured for each anastomosis. Dogs were sacrificed 2, 4, and 8 weeks postoperatively. Each anastomosis was examined grossly and microscopically, and its tensile strength was measured. All dogs survived without complications. Gross and microscopic examinations showed satisfactory healing of both types of anastomoses at different postoperative intervals. The stapled anastomosis required significantly shorter time (p less than 0.01), and had significantly greater tensile strength (p less than 0.05) when compared with manual anastomosis.

Change in membrane lipid fluidity induced by phospholipase A activation: a mechanism of endotoxic shock

The effects of endotoxin administration on the fluidity of dog liver plasma membranes and their relationship with changes in phospholipase A2 activity were studied. Endotoxin administration decreased the fluidity of liver plasma membranes and this decrease was reversible by phosphatidylcholine. The endotoxin-induced decrease in membrane fluidity could be mimicked by digesting control liver membranes with exogenous phospholipase A2. Endotoxin administration also increased the endogenous phospholipase A2 activity. Endotoxin in vitro had no phospholipase A2-like activity but it activated the hydrolytic activity of exogenous phospholipase A2. Based on these data, it is concluded that endotoxin administration decreased the fluidity of canine liver plasma membranes by acting through activation of phospholipase A2. The decrease in membrane lipid fluidity induced by endotoxin administration may play a significant role in the development of the pathophysiology of endotoxic shock at the cellular level.

Incoherent method for rotation-invariant recognition

An optodigital hybrid system using an incoherent circular correlator that has features suitable for space and industrial applications is introduced. The incoherent circular correlator uses a fiber-optics sampler and carries out the correlations in white light. The trade offs involved for efficient detection of objects are discussed. The system has been built, and experimental results on a real air photograph are presented.

Digital multiple correlation for pattern recognition

A method of digital multiple correlation for rotation-invariant recognition has been developed. It is also a computer simulation of an incoherent optodigital hybrid system previously introduced. Speed and flexibility of the digital system are investigated.

Hydrolysis of 4-methylumbelliferyl N-acetyl-chitooligosaccharides catalyzed by human lysozyme

Binding of N-acetyl-chitotetraose, 4-methylumbelliferyl chitotrioside ((GlcNAc)3-MeU), and 4-methylumbelliferyl chitotetraoside ((GlcNAc)4-MeU) to human lysozyme [EC 3.2.1.17] was studied by fluorescence measurement. Hydrolysis of (GlcNAc)3-MeU and (GlcNAc)4-MeU catalyzed by human lysozyme was studied by measuring the release of 4-methylumbelliferone fluorimetrically and the kinetic constants were determined in the pH range of 2 to 8 at 0.1 ionic strength and 42 degrees C. On the basis of binding and kinetic data, it was shown that (GlcNAc)3-MeU binds mainly to subsites A to D with the terminal MeU group bound to subsite D (nonproductive binding) and that (GlcNAc)4-MeU binds to subsites A to E (productive binding) and subsites A to D with the nonreducing sugar residue extending beyond subsite A (nonproductive binding). The pH dependences of the kinetic constants for hydrolysis of (GlcNAc)3-MeU and (GlcNAc)4-MeU were analyzed assuming that nonproductive binding occurs competitively, that an ionizable group in addition to the catalytic groups (Asp 52 and Glu 35) participates in the catalysis, and that the molecular species with ionized Asp 52 and protonated Glu 35 is active. Analyses of the kinetic constants for (GlcNAc)3-MeU and (GlcNAc)4-MeU both gave the same pK values of the catalytic groups (pK52 = 3.6(3) and pK35 = 6.6(8) at 0.1 ionic strength and 42 degrees C). These pK values were very close to the values determined previously by spectroscopic methods in our laboratory (Kuramitsu et al. (1974) J. Biochem. 76, 671-683; (1978) ibid. 83, 159-170; (1980) ibid. 87, 771-778).

Hydrolysis of 4-methylumbelliferyl N-acetyl-chitotetraoside catalyzed by hen lysozyme

Binding of 4-methylumbelliferyl chitotetraoside ((GlcNAc)4-MeU) to hen lysozyme [EC 3.2.1.17] was studied by measuring changes in fluorescence at 375 nm. Hydrolysis of (GlcNAc)4-MeU catalyzed by lysozyme was studied by measuring the release of 4-methylumbelliferone from (GlcNAc)4-MeU fluorimetrically, and the kinetic constants were determined in the pH range of 2 to 8 at 0.1 ionic strength and 42 degrees C. The binding and kinetic data showed that (GlcNAc)4-MeU binds to subsites A to E (productive binding) and subsites A to D with the nonreducing sugar residue extending beyond subsite A (nonproductive binding). The fraction of the productive complex was 0.77 at pH 8.5. The pH dependence of the kinetic constants was analyzed assuming that the molecular species with ionized Asp 52 and protonated Glu 35 is active and Asp 101 participates in the binding (Phillips (1966) Sci. Am. 215, 78-90; Blake et al. (1967) Proc. Roy. Soc. B167, 378-388), and the pK values of these groups were determined. The pK values of Asp 52, Glu 35, and Asp 101 were 3.60, 6.20, and 4.20, respectively, for free lysozyme, 3.40, 6.55, and 3.40, respectively, for the productive complex, and 3.95, 6.55, and 3.30, respectively, for the nonproductive complex. The pK values for free lysozyme were in excellent agreement with those obtained by analysis of the kinetic constants for (GlcNAc)3-MeU (Yang & Hamaguchi (1980) J. Biochem. 87, 1003-1014). The free energy of activation was 24 kcal mol-1 at pH 5.2. Comparison with the corresponding value obtained for hydrolysis of (GlcNAc)6 (Banerjee et all (1975) J. Biol. Chem. 250, 4355-4367) suggests that the interactions of GlcNAc residues with subsites E and F in the transition state are important in lysozyme catalysis. Hydrolysis of (GlcNAc)2-MeU catalyzed by lysozyme was also studied, and the Kcat/Km values for (GlcNAc)2-MeU, (GlcNAc)3-MeU, and (GlcNAc)4-MeU were compared.

Hydrolysis of 4-methylumbelliferyl N-acetyl-chitotrioside catalyzed by hen and turkey lysozymes. pH dependence of the kinetics constants

The binding constants of 4-methylumbelliferyl-beta-glycosides of (GlcNAc)2 ((GlcNAc)2-MeU) and of (GlcNAc)3 ((GlcNAc)3-MeU) to hen lysozyme [EC 3.2.1.17] were determined by measuring changes in the fluorescence at 375 nm. It was shown that (GlcNAc)2-MeU and (GlcNAc)3-MeU bind mainly at subsites B, C, and D, and A, B, C, and D, respectively, with the terminal MeU group bound at subsite D. The rate of hydrolysis of (GlcNAc)3-MeU catalyzed by hen and turkey lysozymes was determined at 0.1 ionic strength and 42 degrees C in the pH range of 2 to 8. The release of 4-methylumbelliferone was followed fluorimetrically. The pH dependences of kcat, kcat/Km, and Km were analyzed assuming that that nonproductive binding occurs competitively and that the molecular species with ionized Asp 52 and protonated Glu 35 is active. Comparison of the pH dependences of the kinetic constants for hen lysozyme with those for turkey lysozyme, in which Asp 101 of hen lysozyme is replaced by Gly, made it possible to determine the pK values of Asp 52, Glu 35, and Asp 101. The pK values of Asp 52 and Glu 35 were 3.60 and 6.20, respectively, for hen and turkey lysozymes and 3.95 and 6.55, respectively, for their nonproductive complexes. The pK value of Asp 101 of hen lysozyme was 4.20 for the free enzyme, 3.30 for the nonproductive complex, and 3.95 for the productive complex. These pK values, except for the pK value of Asp 52 of the nonproductive complex, are in excellent agreement with those determined by spectroscopic methods in our laboratory (Kurasmitsu et al. (1974) J. Biochem. 76, 671--683; (1975) ibid. 77, 291--301; (1977) ibid. 82, 585--597; (1978) ibid. 83, 159--170). This demonstrates that lysozyme-catalyzed hydrolysis can be fully explained in terms of the proposal based on the X-ray data (Blake et al. (1967) Proc. Roy. Soc. B167, 378--388), with regard to the participation of Asp 52 and Glu 35.

Interactions of alpha- and beta-N-acetyl-D-glucosamines with hen and turkey lysozymes

The binding constants of alpha- and beta-GlcNAc to hen and turkey lysozymes [EC 3.2.1.17] were determined at various pH's using the method proposed by Ikeda and Hamaguchi (1975) J. Biochem. 77, 1-16). The pH dependence of the binding of beta-GlcNAc to hen lysozyme was essentially the same as that for turkey lysozyme. The pH dependence curves of the binding constants of beta-GlcNAc to hen and turkey lysozymes were interpreted in terms of the participation of Glu 35 (pK 6.0), Asp 52 (pK 3.5), Asp 48 (pK 4.5), and Asp 66 (pK 1.5). The binding constants of alpha-GlcNAc to hen and turkey lysozymes were the same below pH 3.5 but were different above this pH. The main participant residues in the binding of alpha-GlcNAc were Glu 35, Asp 48, and Asp 66 for hen lysozyme and Glu 35 and Asp 66 for turkey lysozyme. The results obtained here were well explained by the following assumptions: (1) above about pH 4, alpha-GlcNAc binds to hen lysozyme in both alpha- and beta-modes, which correspond to the binding orientation of alpha-GlcNAc and that of beta-GlcNAc, respectively, as determined by X-ray crystallographic studies, but it binds predominantly in the beta-mode below about pH 4, (2) beta-GlcNAc binds to hen and turkey lysozymes predominantly in the beta-mode above about pH 4 and in both alpha- and beta-modes below pH 4, and (3) alpha-GlcNAc binds to turkey lysozyme predominantly in the beta-mode over the whole pH range studied.

Interactions on 3-deoxy and 6-deoxy derivatives of N-acetyl-D-glucosamine with hen lysozyme

The interactions of deoxy derivatives of GlcNAc, 6-deoxy-GlcNAc, and 3-deoxy-GlcNAc with hen egg-white lysozyme [EC 3.2.1.17] were studied at various pH's by measuring the changes in the circular dichroic (CD) band at 295 nm. It was shown that 6-deoxy-GlcNAc and 3-deoxy-GlcNAc bind at subsite C of lysozyme and compete with GlcNAc. The pH dependence of the binding constant of 6-deoxy-GlcNAc was the same as that of GlcNAc. On the other hand, the binding constants of 3-deoxy-GlcNAc were 3--10 times smaller than those of GlcNAc in the pH range from 3 to 9. X-ray crystallographic studies show that O(6) and O(3) of GlcNAc at subsite C are hydrogen-bonded to the indole NH's of Trp 62 and Trp 63, respectively, but the above results indicate that Trp 63, not Trp 62, is important for the interaction of GlcNAc with lysozyme.