Temperature control of biotin binding and release with A streptavidin-poly(N-isopropylacrylamide) site-specific conjugate

The many laboratory and diagnostic applications utilizing streptavidin as a molecular adaptor rely on its high affinity and essentially irreversible interaction with biotin. However, there are many situations where recovery of the biotinylated molecules is desirable. We have previously shown that poly(N-isopropylacrylamide) (PNIPAAm), a temperature-sensitive polymer, can reversibly block biotin association as the polymer's conformation changes at its lower critical solution temperature (LCST). Here, we have constructed a streptavidin-PNIPAAm conjugate which is able to bind biotin at room temperature or lower and release bound biotin at 37 degrees C. The conjugate can repeatedly bind and release biotin as temperature is cycled through the LCST. A genetically engineered streptavidin mutant, E116C, which has only one cysteine residue, was conjugated site specifically via the sulfhydryl groups with a PNIPAAm that has pendent sulfhydryl-reactive vinyl sulfone groups. The conjugation site is near the tryptophan 120 residue, which forms a van der Waals contact with biotin that is important in generating the large binding free energy. The temperature-induced conformational change of the polymer at position 116 may lead to structural changes in the region of tryptophan 120 that are responsible for the reversible binding between biotin and the conjugated streptavidin.

Effects of Curcuma Longa on proliferation of cultured bovine smooth muscle cells and on expression of low density lipoprotein receptor in cells

OBJECTIVE

To investigate the inhibitory effects of aqueous turmeric extract (AqT) and serum of rats orally treated with ethanol extract of turmeric (SeT) on proliferation of vascular smooth muscle cells (VSMC) and its effects on the expression of low density lipoprotein receptor (LDL-R) antigen on the surface of smooth muscle cells.

METHODS

Enzyme-linked immunosorbent assay (ELISA) for the expression of LDL-R protein and thiazolyl blue (MTT) assay for the proliferation of VSMC were used in this study.

RESULTS

Both aqueous turmeric extract (AqT) and serum of rats orally treated with ethanol extract of turmeric (SeT) could inhibit 10% serum activated proliferation of VSMC. The inhibition shown in both experiments was dose-dependent with an inhibitory rate of 18.9% at 20 mg/ml AqT and rate of 20.1% at 10% SeT respectively. AqT up-regulated the expression of LDL-R protein with a highest rate at 5 mg/ml AqT in 3% lipoprotein deficient serum (LPDS). SeT did not show significant effect on the expression of LDL-R on the surface of VSMC.

CONCLUSION

The extracts of turmeric may be extended to decrease the risk of atherosclerosis (AS).

Method for measuring in vivo oxygen transport rates in a bioartificial organ

Oxygen transport is crucial for the proper functioning of a bioartificial organ. In many cases, the immunoisolation membrane used to protect the transplanted cells from the host's immune system can be a significant barrier to oxygen transport. A method is described for measuring the in vitro and in vivo oxygen transport characteristics of a planar immunoisolation membrane. The in vitro oxygen permeability of the membrane was found to equal 9.22 x 10(-4) cm/sec and was essentially the same as the in vivo value of 9.51 x 10(-4) cm/sec. The fact that the in vitro and in vivo membrane permeabilities are identical indicates that any fibrotic tissue adjacent to the immunoisolation membrane did not present a significant resistance to the transport of oxygen. The measured oxygen permeability was also found consistent with the solute permeabilities obtained in a previous study for larger molecules. Based on the oxygen permeability results, theoretical calculations for this particular membrane indicate that about 1,100 islets of Langerhans/cm2 of membrane area can be sustained at high tissue densities and only 660 islets/cm2 can be supported at low tissue densities.

Attenuating the decline in ATP arrests the exercise training-induced increases in muscle GLUT4 protein and citrate synthase activity

Thirty-two female Sprague-Dawley rats were assigned to one of four groups: control (CON); exercise training (TR); exercise training + clenbuterol treatment (0.8 mg kg body wt(-1) d(-1)) (TR + CL) or exercise training + clenbuterol treatment + 2% beta-guanidinoproprionic acid diet (TR + CL + beta) to examine whether alterations in the high energy phosphate state of the muscle mediates exercise training-induced increases in skeletal muscle GLUT4 protein concentration and citrate synthase activity. Exercise training consisted of running the rats 5 d week(-1) for 8 weeks on a motor-driven treadmill (32 m min(-1), 15% grade). Gastrocnemius GLUT4 protein concentration and citrate synthase activity were significantly elevated in the TR animals, but these adaptations were attenuated in the TR + CL animals. Providing beta-GPA in combination with clenbuterol enabled training to elevate GLUT4 protein concentration and citrate synthase activity, with the increase in GLUT4 being greater than that observed for the TR animals. Skeletal muscle ATP levels were reduced in the TR + CL + beta animals while ATP levels in the TR + CL animals were significantly elevated compared with CON. An acute 40-min bout of electrical stimulation of the sciatic nerve was found to lower skeletal muscle ATP levels by approximately 50% and elevate cAMP levels in all groups. No difference in post-contraction cAMP levels were observed among groups. However, post-contraction ATP levels in the TR + CL animals were significantly greater than the other groups. Collectively, these findings suggest that exercise training-induced increases in skeletal muscle GLUT4 protein concentration and citrate synthase activity are initiated in response to a reduction in the skeletal muscle ATP concentration.

Photocatalytic Properties of Titania Pillared Clays by Different Drying Methods

Photocatalysts based on titania pillared clays (TiO2 PILCs) have been prepared through a sol-gel method. Different drying methods, air drying (AD), air drying after ethanol extraction (EAD), and supercritical drying (SCD) have been employed and found to have significant effects on the photocatalytic efficiency of the resultant catalysts for the oxidation of phenol in water. Titania pillared clay (TiO2 PILC) obtained by SCD has the highest external and micropore surface area, largest amount and smallest crystallite size of anatase, and exhibited the highest photocatalytic activity. Furthermore, silica titania pillared clay (SiO2-TiO2 PILC) after SCD, titania coated TiO2 PILC (SCD) and SiO2-TiO2 PILC (SCD) were synthesized to study the key factors controlling the photocatalytic activity. It is concluded that the dispersion of nanometer-sized anatase on the surface of the PILC particles and the suspensibility of the particles are the most important factors for high photocatalytic efficiency. Copyright 1999 Academic Press.

Computer-assisted design and manufacture of posterior full crowns

OBJECTIVE

To build an experimental system for the computer-assisted design (CAD) of full crowns and to obtain data for computer-assisted manufacturing (CAM) of full crowns.

MATERIALS AND METHODS

Three steps are involved in building the system: measuring the prepared tooth, the adjacent mesial and distal teeth, and the opposing teeth by means of digital speckle correlation; reconstructing the shape of the measured teeth; and developing CAD for full crowns. The standard shape of the corresponding tooth was modified to fit the defective tooth on the basis of buccolingual and occlusal-gingival distance as well as the occlusal relationship of the defective tooth.

RESULTS

CAD for full crowns was developed and was obtained for CAM of posterior full crowns.

CONCLUSIONS

The CAD method for full crowns is convenient and economical and can be used for anterior and posterior crown design, copying, and veneer.

[Surgical treatment of aortopulmonary septal defect]

OBJECTIVE

To study the surgical treatment of aortopulmonary septal defect.

METHOD

From January 1983 to December 1996, 5 patients with aortopulmonary septal defect (APSD) (2 male and 3 female) aged from 6 to 34 years (mean 17.4 years) underwent surgical treatment. According to Mori's were classification, 5 patients belonged to type I, 2 type II and 1 type III. The diameters of the defect ranged from 1.0 to 3.0 cm. The operations were performed under moderate hypothermic cardiopulmonary bypass. Pulmonary artery incision was performed, in 3 patients while aortic incision in the other 2. All defects were repaired by Dacron patch.

RESULT

There were no operative deaths and postoperative complications. During follow-up of 10 months to 12 years, no late complications and deaths were found.

CONCLUSION

The operation should be done early as possible whenever the diagnosis is established. The surgical repair should be taken under cardiopulmonary bypass. To chose an incision on the aorta is more reasonable than on the pulmonary artery. The use the dacron patch can prevent stenosis and recanalization after operation.

Variability of the planarity of the human aortic bifurcation

The susceptibility of vascular branches to atherosclerosis is believed to be due in part to the unusual fluid dynamic environments that the vessel wall experiences in these regions. As vascular geometry is a primary determinant of the local haemodynamic environment, it is of interest to quantitate the geometric features of vascular branches and their variability. The present research focusses on branch planarity, using axial magnetic resonance images of the aortic bifurcations of 20 healthy subjects. The in vivo images were processed to obtain vector representations of the vessel axes at the bifurcation, from which the planarity of the bifurcation was derived using a novel robust definition. Three-dimensional reconstructions of the bifurcations were rendered using computer graphics techniques to demonstrate the variability of the planarity of this region of the vasculature; this variability might be related to variable predispositions to atherosclerosis at the aortic bifurcation.

Oxidative and malondialdehyde modification of low-density lipoprotein: a comparative study of binding and degradation by macrophages and endothelial cells

Comparative study of oxidatively modified low-density lipoprotein (Ox-LDL) and malondialdehyde-modified low-density lipoprotein (MDA-LDL) is important for further understanding the biological properties of Ox-LDL, such as its toxic effects, immunogenicity and multiplicity of scavenger receptor binding. In this study, the characteristics of Ox-LDL and MDA-LDL binding and degradation were compared. The results show that when their degree of modification (as determined by relative electrophoretic mobility) was similar, the binding and degradation of Ox-LDL by the macrophage cell line P388D1 were greater than those of MDA-LDL. The binding and degradation of Ox-LDL by macrophages and human umbilical vein endothelial cells increased with the degree of modification. In addition, Ox-LDL or MDA-LDL could competitively inhibit binding of labelled Ox-LDL or labelled MDA-LDL to their respective macrophage receptors, and could partially inhibit each other.

Human BAG-1/RAP46 protein is generated as four isoforms by alternative translation initiation and overexpressed in cancer cells

Previously, a Bcl-2-interacting protein, BAG-1, was cloned from mouse cells and was shown to interact with several other proteins and to be important for inhibition of apoptosis. Human BAG-1 (hBAG-1) cDNA, recently isolated by us and two other groups, has been shown to be identical to a hormone receptor-binding protein, RAP46. However, different molecular masses of hBAG-1 protein products were noted by these three groups. Here we demonstrated that hBAG-1 protein was expressed as four isoforms, designated p50, p46, p33 and p29, with apparent molecular masses of 50 kDa, 46 kDa, 33 kDa and 29 kDa, respectively. Deletion, site-directed mutagenesis and in vitro transcription/translation analysis showed that the four protein products of hBAG-1 were expressed by alternative initiation from four different start codons through a leaky scanning mechanism. Furthermore, we demonstrated that the distinct forms of hBAG-1 have different subcellular localizations, suggesting that they may have distinct functions in the cells. Characterization of hBAG-1 RNA and protein also showed that hBAG-1 was overexpressed in human cervical, breast and lung cancer cell lines. Taken together, these data clarify the conflicting observations reported in the literature and suggest that hBAG-1 is expressed as four forms of protein products, which may play a differential role in apoptosis and oncogenesis of human cells.

[Chemical stability of salmon calcitonin (sCT) analogues in aqueous solution]

Calcitonin is a peptide hormone with 32 amino acids. Natural calcitonins are presumably quite unstable in solution and numerous analogues of calcitonin had been synthesized to improve the stability. In the present paper, we report the investigation of the chemical stability of salmon calcitonin (sCT) analogues [Val1, Ala7]sCT, [Val1, Ala7, Ala30]sCT and [D-Ala30]sCT in aqueous solutions by reversed phase high-performance liquid chromatography (RP-HPLC) and fast atom bombardment mass spectrometry (FAB-MS) methods. The degradation patterns of the sCT analogues showed a marked dependence on pH and temperature. Most of the degradation products in pH 9.0 solution of sCT and its analogues were identified by FAB-MS analysis. Results showed that the sCT analogues are more stable at pH 3.3 and pH 3.7 than at pH 6.0 and pH 9.0. Analogues without disulfide bridge [Val1, Ala7]sCT and [Val1, Ala7, Ala30]sCT showed higher chemical stability than sCT while [D-Ala30]sCT showed lower chemical stability than the native sCT.

[Production of purified Japanese encephalitis vaccine from Vero cells with roller bottles]

OBJECTIVE

To study the production process of purified Japanese encephalitis (JE) vaccine from Vero cells cultivated in roller bottles to improve the quality of JE vaccine.

METHODS

The 15 L roller bottles were used for propagation of Vero cells and JE virus, then the virus was inactivated, concentrated, treated by protamine sulphate, purified by sucrose gradient density centrifugation and lyophylized as final product.

RESULTS

Three batches of high quality lyophylized vaccine were produced and the quality control tests of vaccine for human use had been passed.

CONCLUSION

Using roller bottles to cultivate continuous cell line-Vero cells for JE vaccine production is feasible.

Unusual properties of thermally sensitive oligomer-enzyme conjugates of poly(N-isopropylacrylamide)-trypsin

Reversible soluble-insoluble oligomer-enzyme conjugates have been prepared by conjugating a thermally sensitive oligomer, poly(N-isopropylacrylamide) [poly(NIPAAm)] to trypsin. The conjugates can catalyze enzymatic reactions in solution and then may be separated from the solution by thermal precipitation. One special feature of the conjugates is that every poly(NIPAAm) chain has only one end attachment to the enzyme, so that the loss of enzymatic activity due to steric hindrance should be minimized. Conjugates with various numbers of oligomer chains per trypsin molecule were prepared. Surprisingly, the conjugates increased in enzymatic activity with increasing oligomer conjugation to the native trypsin. The trypsin active sites in the conjugates were accessible to large molecules, such as soybean trypsin inhibitor (MW = 21,500). The enzyme conjugates were more stable than native trypsin, both in solution and in the precipitated phase. On the other hand, the conjugates lost enzymatic activity faster than native trypsin when the temperature was repeatedly cycled through the lower critical solution temperature (LCST) of the poly(NIPAAm). The recovery of the conjugates by thermal precipitation in each cycle was over 95% even after 14 cycles through the LCST.

Glutamate receptors on postganglionic sympathetic axons

The present study demonstrates that approximately 36% of postganglionic sympathetic axons in gray rami express receptors for the N-methyl-D-aspartate receptor 1 subunit of the N-methyl-D-aspartate receptor and 10% express the glutamate receptor 1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. If these receptors are active, glutamate released from primary afferent terminals could activate these receptors resulting in the release of noradrenaline and other substances from postganglionic sympathetic neurons. This interaction would constitute a non-synaptic, sensory-sympathetic, peripheral reflex that might be important in local vascular control and in pain states that have a sympathetic component.

Relation between the structural asymmetry of coronary branch vessels and the angle at their origin

The relationship between the geometry of branch points on the left anterior descending coronary artery, and the morphometry of the proximal portions of the daughter vessels, was examined. The geometry at 23 branch points on 15 human hearts was derived from multiplane contrast angiograms, and the morphometry at 29 sites along the daughter vessels was obtained from transverse sections using computerized techniques. The angle of the branch at which the daughter originated was positively correlated with the maximum thicknesses of the intima and media, and with their circumferential asymmetry. The results suggest that large branch angles may favor eccentric intimal thickening, a phenomenon which may predispose to lipid accumulation and atherosclerosis.

Coronary hemodynamics in endothelial NO synthase knockout mice

For the specific analysis of endothelial NO synthase (eNOS) function in the coronary vasculature, we generated a mouse homozygous for a defective eNOS gene (eNOS-/-). Western blot as well as immunohistochemical staining revealed the absence of eNOS protein in eNOS-/- mice. Aortic endothelial cells derived from eNOS-/- mice displayed only background levels of NOx formation compared with wild-type (WT) cells (88 versus 1990 pmol NOx x h-1/mg protein-1). eNOS-/- mice were hypertensive (mean arterial pressure, 135 +/- 15 versus 107 +/- 8 mm Hg in WT) without the development of cardiac hypertrophy. Coronary hemodynamics, analyzed in Langendorff-perfused hearts, showed no differences either in basal coronary flow or in maximal and repayment flow of reactive hyperemia. Acute NOS inhibition with Nomega-nitro-L-arginine methyl ester (L-NAME) in WT hearts substantially reduced basal flow and reactive hyperemia. The coronary response to acetylcholine (ACh) (500 nmol/L) was biphasic: An initial vasoconstriction (flow, -35%) in WT hearts was followed by sustained vasodilation (+190%). L-NAME significantly reduced vasodilation in WT hearts (+125%) but did not alter the initial vasoconstriction. In eNOS-/- hearts, the initial vasoconstriction was augmented (-70%), whereas the ACh-induced vasodilation was not affected. Inhibition of cyclooxygenase with diclofenac converted the ACh-induced vasodilation into vasoconstriction (-49% decrease of basal flow). This effect was even more pronounced in eNOS-/- hearts (-71%). Our results demonstrate that (1) acute inhibition of eNOS reveals a role for NO in setting the basal coronary vascular tone as well as participation in reactive hyperemia and the response to ACh; (2) chronic inhibition of NO formation in eNOS-/- mutant mice induces no changes in basal coronary flow and reactive hyperemia, suggesting the activation of important compensatory mechanisms; and (3) prostaglandins are the main mediators of the ACh-induced vasodilation in both WT and eNOS-/- mice.

[National epidemiological study on obesity of children aged 0-7 years in China 1996]

OBJECTIVE

To study on obesity of children aged 0-7 years in 11 cities in 1996.

METHODS

The sampling size was 208, 513. The children were divided into 9 groups: birth-, 1 mo-, 6 mo-, 1 yr, 2 yr-, 3 yr, 4 yr-, 5 yr-, 6-7 yr.

RESULTS

The prevalence of overweight was 4.2% (M4.2%, F4.2%); and of obesity, 2.0%(M2.2% F1.9%). The obesity to overweight ratio (ORR) was 2.1%(M1.9%, F2.2%). The adiposity rebound age (ARA) was 5 years. The adiposity rebound ratio (ARR) was 3.2 for ARR1 (M2.9%, F.5%) and 2.0 for ARR2 (M1.7%, F2.4%) in obese children and 3.5 for ARR1 (M 3.5, F3.5) and 2.5 for ARR2 (M2.8, F2.8) in overweight children respectively. The secular trend of prevalence of childhood obesity during 1986-1996 showed that the prevalence of obesity increased annually at 9.1% (M10%, F8.7%).

CONCLUSION

The obesity has already been a severe health and social problem of preschool children in China. The increment of prevalence of obesity during 1986-1996 has been out of control. The earlier of ARA and the larger of OOR is an important risk factor of increasing of obesity. 1 year and 5 years after birth, predicted by ARR, are two critical periods of obesity control in preschool children in China.

No lactic acid absorbed from the caecum and rumen of sheep

A comparative study of the absorption of lactic acid, volatile fatty acids (VFA), glucose, and ammonia from caecal and rumen pouches was undertaken in anaesthetised sheep. Test solutions varying in pH, osmolarity, lactic acid concentration, and with fixed concentrations of VFA, ammonia, and glucose (100, 7, and 4 mmol/L, respectively) were introduced into the clean, surgically sealed pouches. Studies were undertaken in 9 sheep, each with 2 pouches in the caecum and 1 in the rumen. Samples were taken at 10-min intervals for 50 min to determine rate of absorption. Neither L-lactic acid nor D-lactic acid was absorbed from the caecal or rumen pouch and there was a slight increase in both isomers of lactic acid (0·39%/min of L-lactic acid and 0·24%/min of D-lactic acid averaged for the caecum and rumen values) which was presumably due to conversion of propionic acid and tissue metabolism during the experiment. The rate of increase per unit area in the caecum (0·06 µmol/cm2·min) was much greater than that in the rumen (0·015 µmol/cm2·min) based on the average of L- and D-lactic acid. The absorption rates of acetic, propionic, and butyric acids from the caecum (0·49, 0·17, and 0·08 µmol/cm2 ·min, respectively) and the rumen (0·48, 0·16, and 0·08 µmol/cm2· min, respectively), based on absorptive surface area of the pouches, were very similar. Glucose was apparently absorbed from rumen pouches (0·18 µmol/cm2 ·min), but not from caecal pouches (-0·01 µmol/cm2·min). The mean absorption rate of ammonia from caecal pouches (0·60 µg N/cm2·min) was 2·5 times greater than that from rumen pouches (0·24 µg N/cm2·min) (P < 0·0001). The mean absorption rate of ammonia for the caecal and rumen pouches was about 2·6 times higher at pH 6·5 (0·99%/min) than that at pH 4·5 (0·38%/min) (P < 0·0001) at the same osmolarity and lactic acid concentration. A decrease in pH, osmotic pressure, or the concentration of lactic acid resulted in corresponding increases in the absorption of VFA.

A sulfatide receptor distinct from L-selectin is involved in lymphocyte activation

Sulfatide induces leukocyte activation, which is thought to be mediated via L-selectin. Here we demonstrate that lymphocytes express a receptor for sulfatide distinct from L-selectin and that this receptor is involved in sulfatide-induced cell activation. While cell surface L-selectin expression was abolished by phorbol 12-myristate 13-acetate (PMA), lymphocytes retained the ability to bind sulfatide in liquid phase as well as in immobilized solid phase. The novel sulfatide receptor obtained from PMA-treated lymphocytes showed a molecular size of 65 kDa. Stimulation through this receptor triggered cytosolic free Ca2+ elevation and intercellular aggregation.

Serum from women with preeclampsia partially corrects the abnormal in vitro prostacyclin secretion of preeclamptic villous cytotrophoblasts but not that of prostaglandin E2 or endothelin-1

OBJECTIVE

This study was conducted (1) to determine in vitro placental villous cytotrophoblast secretion of prostacyclin, prostaglandin E2, and endothelin-1, (2) to examine the effect of serum from normal and preeclamptic women on secretion of these vasoactive substances, and (3) to determine whether responses to these sera by cytotrophoblasts from preeclamptic pregnancies are different from those of normal pregnancies.

STUDY DESIGN

Cytotrophoblasts isolated from human placentas collected at cesarean section from normal and preeclamptic women were incubated for 20 hours in 20% (vol/vol) sera from preeclamptic or gestational age-matched normal pregnant women. Levels of prostacyclin (measured as 6-keto-prostaglandin F1alpha), prostaglandin E2, and endothelin-1 were measured in cytotrophoblast supernatants.

RESULTS

In normal pregnancy sera preeclamptic cytotrophoblasts secreted significantly lower amounts of prostacyclin and prostaglandin E2 but higher amounts of endothelin-1 than did normal cytotrophoblasts. In preeclamptic sera the abnormality of prostacyclin secretion by preeclamptic cytotrophoblasts was partially corrected, but there was no effect on prostaglandin E2 or endothelin-1 secretion. Preeclamptic sera had no effect on secretion by normal cytotrophoblasts.

CONCLUSIONS

The differences between normal and preeclamptic cytotrophoblasts in prostacyclin, PGE2, and endothelin-1 secretion and in response to preeclamptic serum suggest altered arachidonic acid metabolism in preeclampsia.

Oxidative and malondialdehyde modification of low-density lipoprotein: a comparative study

Low-density lipoprotein (LDL) was modified with copper ions (Cu2+) and malondialdehyde (MDA), and the differences were compared. The results show that both oxidative and MDA modification produce a decrease in free amino groups in LDL and enhance its electrophoretic mobility on agarose gel, and that these observations are linked. However, differences produced by the two forms of modification were observed. Oxidative modification of LDL involves free radical-mediated lipid peroxidation which produces large amounts of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes. In addition, vitamin E was reduced considerably and cholesterol lowered, and apolipoprotein B (apo B) fragmentation and aggregation were seen. Similar changes were not seen with MDA modification which does not involve lipid peroxidation. Fluorescence emission spectra of both forms of modified LDL show that emission intensity increases gradually as the modification progresses, but maximum emission wavelength and spectrum patterns are not the same. These findings may be of some significance in the study of the antigenicity, scavenger receptor multiplicity and toxic effects of modified LDL.

Influence of the geometry of the left main coronary artery bifurcation on the distribution of sudanophilia in the daughter vessels

The proximal portions of the left anterior descending (LAD) and left circumflex (LCx) coronary arteries are among the sites most predisposed to atherosclerotic disease. This predisposition might be a consequence of their location immediately distal to the left main (LM) coronary artery bifurcation, which may increase the susceptibility of these segments by promoting an adverse fluid dynamic environment within them. The detailed geometry of the bifurcation influences this environment and would therefore affect the susceptibility of the proximal daughter vessels to disease. This hypothesis was tested by examination of the relationship between the geometry of the LM bifurcation and the distribution of sudanophilia in the proximal portions of the LAD and LCx. The geometric parameters at the LM bifurcation, including all three angles and LM length, were obtained from multiangle photographs of 17 vascular casts by use of objective computer-based algorithms. A robust index, the relative proximal involvement (RPI), was developed to measure the localization of disease to the proximal portions of the daughter vessels. The RPI of the LAD segment correlated best with an interaction term that included the planarity of the LM bifurcation and the LCx-LAD branch angle (P = .013). In addition to supporting the concept of geometric risk factors, these observations also suggest that interactions between the hemodynamic influences of multiple geometric variables may play a role in the mediation of tissue susceptibility by geometric factors.

Nitric oxide is not involved in vascular nociception of noxious physical stimuli in humans

We tested the hypothesis that nitric oxide (NO) is involved in vascular nociception of physical stimuli in humans. Vascularly isolated hand vein segments of six healthy volunteers were pretreated with the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME; 10(-7)-10(-4) M) and repeatedly subjected to noxious thermal (2 degrees C, 52 degrees C) or mechanical stimuli (balloon distention) and, for control, to the endogenous algetic bradykinin (10(-6) M). L-NAME prevented in a concentration-related manner the algesic action of bradykinin, but had no effect on pain evoked by heat, cold, or stretch. NO is therefore not a general chemical link in nociception.

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.