The buffering capacity of caecal digesta exceeds that of rumen digesta from sheep fed pasture or roughage diets

The buffering capacities of caecal and rumen digesta of sheep on different diets were determined by titration with lactic, acetic, and hydrochloric acids, and certain factors affecting the buffering capacity of rumen digesta were studied. Both rumen and caecal digesta had maximal buffering capacity at pH 6·5–6·0. The buffering capacity of caecal digesta was nearly double (P < 0·001) that of rumen digesta. The rumen digesta from sheep fed oaten chaff had a buffering capacity 21% higher (P < 0·05) than that of sheep grazing green pasture. This was reduced (P < 0·05) by one-third following ruminal infusions of glucose, lactic, or acetic acid to induce acidosis. Diet did not significantly affect the buffering capacities of rumen and caecal digesta. However, the buffering capacities of rumen and caecal digesta from pasture-fed sheep that had been fasted for 24 h were significantly greater (P < 0·001) than those for sheep that had not been fasted (62 and 18%). The buffering capacity determined using HCl was always less than that for lactic or acetic acid. This may be due to the lower pKa for HCl and the fact that there is no evidence that HCl undergoes inter-conversion through fermentation that the organic acids may undergo. The addition of carbonate or phosphate buffer significantly increased (P < 0·05) the buffering capacity of rumen and caecal digesta. The sodium bicarbonate and sodium carbonate (NaHCO3 and Na2CO3) system played a more effective buffering role than the sodium dihydrogen orthophosphate and disodium hydrogen orthophosphate (NaH2PO4 and Na2HPO4) system in the rumen digesta.

Superresolution with an apodization film in a confocal setup

We put forward the idea of implementing a confocal setup to suppress the large sidelobes spreading all through the field outside the central core. They are produced when an apodization film is imposed on an ordinary lens. Furthermore, this avoids the imaging quality degradation caused by nonaxial points and non-Gaussian-plane points. Also a configuration for achieving three-dimensional superresolution is depicted and discussed.

Interaction of exercise training and clenbuterol on GLUT-4 protein in muscle of obese Zucker rats

Chronic administration of clenbuterol, a beta 2-adrenergic agonist, attenuates the exercise training-induced improvement in muscle insulin resistance of the obese Zucker rat. The present study was conducted to determine whether clenbuterol also attenuates the increase in muscle GLUT-4 protein that occurs with exercise training and whether the action of clenbuterol is related to its ability to downregulate the beta-adrenergic receptors. Female obese Zucker rats were randomly assigned to one of the following four groups: control (CON, n = 7), clenbuterol (CL, n = 8), exercise training (TR, n = 8), and clenbuterol with exercise training (CL+TR, n = 8). Rats assigned to the training groups were run on a rodent motor-driven treadmill for 6-7 wk. Rats receiving clenbuterol were intubated with 0.8 mg/kg body weight 30 min before running each day. Red quadriceps (RQ) and white quadriceps (WQ) GLUT-4 protein concentrations of TR rats were significantly greater than those of CON and CL+TR rats. The RQ GLUT-4 protein concentration of the CL+TR rats was significantly greater than that of CON rats, but this difference did not occur in the WQ. GLUT-4 protein concentrations were not different between the CON and CL rats. The patterns of RQ and WQ GLUT-4 mRNA were similar to those of their respective GLUT-4 proteins. Rats receiving daily injections of propranolol (30 mg/kg body wt), a beta-adrenergic receptor antagonist, demonstrated no increase in GLUT-4 protein in RQ or WQ after 6 wk of exercise training. These results indicate that 1) clenbuterol can attenuate the increase in muscle GLUT-4 protein associated with exercise training and 2) this effect is likely mediated by a downregulation of the beta-adrenergic receptors.

Relationship between the geometry and quantitative morphology of the left anterior descending coronary artery

The well established 'systemic' risk factors for atherosclerosis can explain only half of the variability in its occurrence. To account for some of the remaining variability, it was suggested that certain geometric features of atherosclerosis-prone segments ('geometric risk factors') can increase the likelihood of disease locally through their influence on the hemodynamic environment of the vessel wall. Since this mediation might elicit early morphological changes in the artery, relationships were sought between the histomorphometry and axial geometry of the left anterior descending (LAD) coronary arteries of 15 angiographically lesion-free human hearts obtained at autopsy. Geometric variables were quantified by image processing of multiplane angiograms of the hearts, and morphometry was obtained from transverse histologic sections at 91 sites. The results show that: (1) total intimal and medial area are negatively correlated with the distance from the site to the origin of the LAD; (2) the angle of the branch immediately proximal to the site is positively correlated with most of the intimal and medial variables, and appears to have a major influence on the intima; (3) the area ratio of the immediately proximal branch is correlated primarily with medial variables; and (4) local curvature is correlated only with the maximum thickness of the intima and media. These observations suggest that there are significant relationships between arterial geometry and vascular morphology prior to the development of frank disease.

Reduction of Saccharomyces cell adhesion by liquid mechanical vibration

The effect of liquid mechanical vibration on the adhesion of Saccharomyces cerevisiae cells to the internal glass surface of a pipette was studied using a 25 Hz vibration source. The maximum vibration amplitude was 1.06 mm (peak to peak) along the pipette direction. Relative movements between the pipette and yeast suspension in it were produced by vibration and reduced the cell adhesion. The reduction in adhesion was affected by both vibration amplitude and suspension pH. Analysis showed that in routine cell counts, cell adhesion to the pipette wall was a significant error source. The construction of a vibration device for routine cell count work appears feasible.

[Correction of the secondary deformity of reduction mammaplasty--the inframammary fold advancement]

The high position of the nipple-areola is one of the complications of reduction mammaplasty. The technique of lower thoracic advancement flap reestablishes a new inframammary fold. The edge of the advanced inferior flap is sutured to the chest wall and the rib cage. The advantages of the technique is that the scar is hidden in the depth of the inframammary fold and is usually fairly in-conspicuous. The technique gives an increasingly natural looking of the breast. The operation is appealingly easy and safe. Figures illustrate the effectiveness of this technique.

Inhibitory effects of isoproterenol on PAF-induced endothelial cell permeability and morphological changes

Using a model to study vascular permeability under hydrostatically perfused bovine pulmonary artery endothelial cell (EC) monolayers and a software to automatically analyse cell morphological parameters in a computer image workstation, the effects of isoproterenol (IPN) on platelet-activating factor (PAF)-induced changes in EC monolayer permeability and cell morphological parameters were studied. Albumin has the fortifying effect on endothelial barrier function. After treatment of EC monolayer with 10(-8) mol/L PAF, trans-monolayer permeability increased, cell surface area decreased, and intercellular space enlarged. As pretreatment with 10(-4) mol/L IPN, PAF-induced EC permeability increment and morphological changes were blocked. The results suggest that EC contraction and intercellular gap expansion are important mechanisms for PAF-induced high vascular permeability. IPN inhibits the effects of PAF via stabilization of EC morphology and prevention of intercellular gap formation.

Synthesis and purification of thermally sensitive oligomer-enzyme conjugates of poly(N-isopropylacrylamide)-trypsin

Using chain-transfer polymerization, we have synthesized oligomers of poly(N-isopropylacrylamide) [poly(NIPAAm)] with one carboxyl group at the end of each oligomer chain. The lower critical solution temperature (LCST) of the oligomers is very close to that of homo-poly(NIPAAm) lacking the end carboxyl group. The carboxyl groups were activated in methylene chloride using N,N'-dicyclohexyl-carbodiimide (DCC) and N-hydroxysuccinimide (NHS). A conjugate of trypsin with the preactivated oligomer has been prepared. We studied the effect of oligomer to enzyme (O/E) ratio in the feed on the O/E ratio of the conjugate (the average number of oligomer chains conjugated to one trypsin molecule), assuming that only the primary amino groups of lysine residues and the amino terminal of trypsin would react. The O/E ratio of the conjugate was estimated by determination of the remaining primary amine groups on the trypsin molecule. More than 95% of the conjugate can be recovered by thermally induced precipitation.

[The effects of Salvia miltiorrhiza and polysaccharide sulphate on the adhesion of erythrocytes of the patients with cerebral thrombosis to cultured endothelial cells]

Salvia miltiorrhiza and polysaccharide sulphate are commonly prescribed for curing cerebral vascular diseases. In this study, we found that the adhesion of erythrocytes of the patients with cerebral thrombosis to cultured human umbilical vein endothelial cells was decreased in number and intensity after the erythrocytes were treated with salvia miltiorrhiza and polysaccharide sulphate in flow field. Moreover we found that polysaccharide sulphate was more effective than salvia miltiorrhiza in preventing adherence in common doses. The two drugs' effects of preventing adherence might be an important mechanism for curing the patients with cerebral thrombosis.

[Step increase in shear stress effects on releasing prostacyclin of human umbilical vein endothelial cell]

Adopting the flow chamber, we studied the effect of step increase in shear stress on prostacyclin releasing of human umbilical vein endothelial cell (HUVEC). HUVEC monolayer was exposed to step increase in shear stress levels of 1, 10 and 20 dyne/cm2 for 100 minutes. By radioimmunoassay, 6-keto-PGF1 alpha in flowing out liquid from the flow chamber was measured. The results displayed: when HUVEC was not exposed to shear stress, the PGI2 released from HUVEC was not detectable; when HUVEC was exposed to shear stress, the flow onset led to an initial burst increase of PGI2 production rate, which went down subsequently within several minutes. We noticed that the larger the step increase of shear stress became, the higher the peak value of PGI2 production rate ascended, the quicker the peak value subsequently declined, and the higher the average value of PGI2 releasing rate in 80-100 minutes stood. The results demonstrated that in vivo hemorheological factor-the shear stress of blood flowing stimulated the release of prostacyclin from HUVEC.

[Adhesion of erythrocytes of patients with cerebral thrombosis to injured endothelial cells]

Using flow chamber system, we quantitatively studied the adhesion of erythrocytes (RBCs) of patients with cerebral thrombosis (CTh) to cultured human umbilical vein endothelial cells (HUVECs) treated with H2O2. The results showed that injured HUVECs enhanced adhesion of RBCs to HUVECs in patients with CTh. There is injury of endothelial cells in the pathogenetic and pathologic process of CTh, and the adhesion of RBCs to ECs promotes vaso-occlusive and vascular damage; thus the adhesion of RBCs to injured ECs might play an important role in the pathogenesis and pathologic process of CTh.

[A preliminary study on bioactivity of orange and tangerine peel extracts against aphis and mites]

An assay was made on the bioactivity of the extracts of tangerine peel from Cinocitrus tangerina, orange peel from Citrus sinensis and mixed tangerine peel from Cinocitrus sp. against aphis Semia phis heraclei, Aphis craccivora, Uroleucon gobonis and Myzus persicae using residual film or topical method, and against mites Tetranychus viennensis and T. trancatus using slide-dip or immersion method. Test results show that these extracts have strong bioactivity against aphids and mites. The corrected mortality regression equations and LC50 (or LD50) of these extracts to pests are presented.

[Rheologic properties of the human umbilical vein endothelial cells exposed to shear stress]

The function of vascular endothelial cells has recently become a hot spot in biomedical research. This paper reports the deformation properties of cultured human umbilical vein endothelial cells exposed to shear stress with the flow chamber. The umbilical vein endothelial cells were exposed to shear stress 0.6, 3.8 and 7.5 Pa for 12 h respectively. With microvideo recording and computerized morphologic analysis, the results demonstrated that the endothelial cells were elongated as a result of exposing to shear stress 3.8 or 7.5 Pa for 12 h. Their major axes were consistent with the flow direction. Furthermore the degree of elongation and orientation of endothelial cells depended on the shear stress and shear duration. The results were compared with those of three foreign laboratories; and the causes of agreement and difference were discussed. This study is the basic word for a series of future researches.

[A preliminary study on the antenatal diagnosis and prevention of the fetus toxoplasmosis infection]

For those pregnant women with an abnormal pregnancy history, the polymerase chain reaction (PCR) technique was adopted to screening the serum toxoplasmosis DNA (TOX-DNA). Then tests were made for further evidence of TOX-DNA in the amnionic fluids TOX-DNA was examined in cases with blood TOX-DNA positive. Gamma glutamyl transpeptidase (GGT) and alpha-fetoprotein (AFP) in the amnionic fluids were measured for reference, a antenatal diagnosis of the fetal congenital toxoplasmosis infection could thus be made. In the present paper, 9 out of 92 blood specimen were TOX-DNA positive, of the 9 cases, 5 had TOX-DNA and 4 had no TOX-DNA in the amnionic fluid tests. The results of follow-up examination in the 9 cases were in conformity with the ante natal diagnosis. This is an important procedure for diagnosis and prevention of maternal-fetal vertical infection of Toxoplasmosis.

A rapid simplified purification of bovine thrombin

A rapid simplified method was developed to obtain highly pure bovine thrombin. Prothrombin was directly activated when it was enriched from bovine plasma without prior purification. The activated thrombin was isolated by a single Heparin-Sepharose affinity chromatography step. About 87% of activated thrombin was recovered and the yield was 25.1 mg of thrombin per liter of starting plasma. Specific activity of the final preparation was 4018 NIH units/mg, representing a 402 fold purification over the starting material. Comparative experiments showed that the simplified method was about six times as effective as previous two-step methods.

Vascular barrier-enhancing effect of an endogenous beta-adrenergic agonist

Exogenous catecholamines have been proved to be active in the reduction of vascular permeability induced by various inflammatory mediators via beta-adrenoceptor activation, but it is not known whether an endogenous beta-adrenergic agonist has any effect. We studied it in skin and lung vessels. The results revealed that an intravenous bolus of isoproterenol (10 micrograms/kg) attenuated platelet-activating factor- and histamine-induced Evans blue dye extravasation in rat dorsal skin, while intraperitoneal administration of beta-adrenoceptor blocker propranolol (0.1 mg/kg) significantly increased the dye extravasation. Blockade of beta-adrenoceptor by propranolol for 12 h noticeably increased wet/dry lung weight ratio, lung water content, bronchoalveolar lavage (BAL) protein concentration, leukocyte count, and lipoperoxide degradation product malondialdehyde (MDA) content. In isolated perfused lung in vitro, propranolol (2.5 micrograms/ml) had no obvious effects on lung weight gain, fluid filtration coefficient, and pulmonary vascular pressure during the 20-min perfusion compared with control. The results suggested that endogenous beta-adrenergic agonist is an important factor in the maintenance of vascular integrity and the quiescent state of leukocytes, indicating the antiinflammatory role of catecholamines in physiological states and critical illnesses.

[A morphological study of experimental corneal neovascularization]

Corneal neovascularization (CNV) was induced by alkali burn injuries in 20 rabbit corneas. The process of CNV was observed with biomicroscopy in vivo and histologically by light and electron microscopy. At 8 hours after injury, an obvious acute inflammatory response as evidenced by infiltration of neutrophils had already occurred in the pericorneal limbal area. Many neutrophils in the extravascular space contained abundant intracytoplasmic phagolysosomes. The vascular sprouts appeared 2 days after injury. The infiltration of neutrophils and their debris were visible around newly formed blood vessels in the cornea. The results suggest that there be the participation and an inductive action of neutrophils in the pathogenesis of CNV.

Response of constrained and unconstrained bubbles to lithotripter shock wave pulses

The Gilmore formulation for spherical bubble dynamics [F. R. Gilmore, The Growth or Collapse of a Spherical Bubble in a Viscous Compressible Liquid (California Institute of Technology, Pasadena, CA, 1952), Rep. No. 26-4] is used to investigate the response of air bubbles to a variety of lithotripter shock waveforms. A modification of the Gilmore model is proposed to account for partial constraint of the bubble expansion that can be caused by bubble coatings (such as in echo contrast agents) and by tissues or vessels surrounding bubbles in vivo. In the modified formulation, a viscoelastic membrane is assumed to exist at the bubble interface to include the possible effects of the nonlinear elasticity and strain rate dependent viscosity on the bubble response. The stress induced in the membrane is assumed to be an exponential function of the bubble radius, which tends to restrict the bubble expansion. The viscosity is assumed to increase with the strain rate. In the absence of the membrane, the maximum bubble wall pressure induced by a negative (tensile) pulse is much larger than that induced by a positive (compressive) pulse of the same pressure waveform and amplitude. This difference increases with decreasing initial bubble radius. The addition of the viscoelastic membrane significantly decreases the predicted maximum bubble pressure and the difference in response between the positive and negative pulses. The effect of the time delay between double pulses (positive followed by negative or negative followed by positive) is also investigated for unconstrained bubbles.

Purification and properties of cow splenic biliverdin reductase

Biliverdin reductase was purified from cow spleen. The specific activity of the final enzyme preparation was 24.01 u/mg, representing 686-fold purification as measured with NADPH. The yield was 3 grams of enzyme per 100 grams of cow spleen. The purified enzyme was a monomeric protein with an apparent molecular weight of about 34,000 and an isoelectric point of about 6.2. The biliverdin reductase was specific for biliverdin and reduced IX alpha faster than the biliverdin isomers IX beta, IXr, or IX delta. The purified enzyme could utilize both NADH and NADPH, but the kinetic properties of the NADH-dependent and the NADPH-dependent enzyme activities were different: the time course of the NADPH-dependent reaction displayed a sigmoidal curve, whereas that of the NADH-dependent reaction did not. Km for biliverdin IX alpha was 4 x 10(-4) mM in the NADPH system, while it was 1.5 x 10(-3) mM in the NADH system. Both enzyme activities were inhibited by excess biliverdin, but the inhibition of the NADPH-dependent enzyme activity was more pronounced. The pH optimum was 7.0 with NADH, and 6.8 with NADPH.

Suppression by isoproterenol of endothelial cell morphology and barrier function changes induced by platelet-activating factor

Using a model to study vascular permeability on hydrostatically perfused bovine pulmonary artery endothelial cell (EC) monolayers and software to analyze cell morphological parameters automatically in a computer image workstation, we studied the effects of isoproterenol (IPN) on platelet-activating factor (PAF)-induced changes in EC monolayer permeability and cell morphological parameters. Albumin has fortifying effects on endothelial barrier function. As albumin concentration in the perfusate increased (0, 1, 5, 10, 20 mg/ml), EC monolayer hydraulic conductivity (Lp) decreased gradually while Lp of the filter membranes did not change. After treatment of the EC monolayer with PAF 10(-8) mol/liter for 30 min, transmonolayer fluid flow, protein clearance rate, and Lp value increased noticeably. At the same time, cell area decreased and intercellular distance and percentage of intercellular space area in total cell monolayer increased. Pretreatment with 10(-4) mol/liter IPN blocked PAF-induced EC permeability and morphological changes, suggesting that EC contraction and intercellular gap formation are important mechanisms for PAF-induced high vascular permeability. IPN inhibits the effects of PAF via stabilization of EC morphology, protection of intercellular junction, and blockade of intercellular gap formation.