Blood gas profiles of fetuses with abnormal Doppler flow in the umbilical artery

This study was designed to show how accurately the pulsed Doppler fetal blood flow velocimetry reflects fetal blood gas values. Abnormal Doppler umbilical artery (UA) velocimetry was defined when the value deviated from the 95% confidence interval of the normal fetuses. Fetal acidemia, hypoxemia, or hypercapnia was defined when the fetal blood gas taken by funipuncture during pregnancy deviated from the 95% confidence interval of the standard. Positive predictive values of abnormal UA Doppler with acidemia, hypoxemia, and hypercapnia were 26.3, 29.2, and 25.4%, respectively. When an absence or reversal of diastolic flow was observed, positive predictive values of absence or reversal of UA Doppler were 71.4 for acidemia, 71.4 for hypercapnia, and 71.4 for hypoxemia. In conclusion, although it is difficult to presume the fetal blood gas profile by Doppler velocimetry alone, we have to recognize the deterioration of the fetal blood gas profile when we observe the absence or reversal in diastolic flow in the UA.

Contribution of sustained Ca2+ elevation for nitric oxide production in endothelial cells and subsequent modulation of Ca2+ transient in vascular smooth muscle cells in coculture

To elucidate the intracellular Ca2+ (Ca2+i ) transient responsible for nitric oxide (NO) production in endothelial cells (ECs) and the subsequent Ca2+i reduction in vascular smooth muscle cells (VSMCs), we administrated four agonists with different Ca2+i-mobilizing mechanisms for both cells in iso- or coculture. We monitored the Ca2+i of both cells by two-dimensional fura-2 imaging, simultaneously measuring NO production as NO2-. The order of potency of the agonists in terms of the peak Ca2+i in ECs was bradykinin (100 nM) > ATP (10 microM) > ionomycin (50 nM) > thapsigargin (1 microM). In contrast, the order in reference to both the extent of Ca2+i reduction in cocultured VSMCs and the elevation in NO production over the level of basal release in ECs completely matched and was ranked as thapsigargin > ionomycin > ATP > bradykinin. Treatment by NG-monomethyl-L-arginine monoacetate but not indomethacin or glybenclamide restored the Ca2+i response in cocultured VSMCs to the isoculture level. In ECs, when the Ca2+ influx was blocked by Ni2+ or by chelating extracellular Ca2+, all four agonists markedly decreased NO production, the half decay time of the Ca2+i degenerating phase, and the area under the Ca2+i curve. The amount of produced NO hyperbolically correlated to the half decay time and the area under the Ca2+i curve but not to the Ca2+i peak level. Thus, the sustained elevation of Ca2+i in ECs, mainly a result of Ca2+ influx, determines the active NO production and subsequent Ca2+i reduction in adjacent VSMCs. Furthermore, L-arginine but not D-arginine or L-lysine at high dose (5 mM) without agonist enhanced the NO production, weakly reduced the Ca2+i in ECs, and markedly decreased the Ca2+i in VSMCs, demonstrating the autocrine and paracrine effects of NO (Shin, W. S., Sasaki, T., Kato, M., Hara, K., Seko, A., Yang, W. D., Shimamoto, N., Sugimoto, T., and Toyo-oka, T. (1992) J. Biol. Chem. 267, 20377-20382).

[Shear stress and vascular formation]

Blood flow plays important roles in the morphogenesis of blood vessels. For instance, increases in blood flow induce dilatation of the blood vessels, while decreases in blood flow cause reduction of vessel diameter. Blood flow also stimulates angiogenesis. In these blood flow-dependent phenomena, wall shear stress generated by flowing blood that acts on vascular endothelial cells works as a key factor. Numerous in vivo and in vitro studies have demonstrated that mechanical forces, shear stress, actually modulate the morphology and many functions of endothelial cells, and these forces also alter their gene expression. More recently, a cis-acting shear stress responsive element was identified in the promoters of endothelial genes that respond to shear stress, suggesting a common mechanism linking biomechanical forces to gene expression. Details of the process in which shear stress-mediated changes in endothelial cell functions lead to vascular remodeling and angiogenesis, however, are not entirely clear. Elucidation of this problem will give us not only a better understanding of the morphogenesis of blood vessels but also new therapies that can help manage or prevent cardiovascular diseases including atherosclerosis.

A matrix attachment region (MAR)-binding activity due to a p114 kilodalton protein is found only in human breast carcinomas and not in normal and benign breast disease tissues

A M(r) 114,000 protein (p114) that specifically binds to nuclear matrix attachment DNA (matrix attachment region, MAR) from a breast carcinoma cell line SK-BR-3 was purified to near homogeneity. p114 strongly binds to a wild-type A+T-rich MAR probe with high unwinding propensity with a dissociation constant (Kd) of 10(-9), while it exhibits substantially reduced binding to a mutated A+T-rich non-MAR probe, which lacks unwinding propensity. This binding specificity and affinity is similar to the previously cloned thymocyte-associated MAR-binding protein SATB1. By Southwestern blot analysis, the MAR-binding activity of p114 is detectable in human breast carcinomas but is undetectable in normal breast tissues, benign breast diseases, and immortalized epithelial MCF-10A cells. Thus, the MAR-binding activity of p114 is not merely reflecting cell proliferation, but it strongly associates with breast carcinomas. The p114 MAR-binding activity was found in all 43 human breast carcinoma specimens tested, without exception. Much stronger p114 MAR-binding activity was detected in poorly differentiated than well-differentiated carcinomas. p114 may be a reliable diagnostic and possibly prognostic marker for breast cancer.

Flow-dependent regulation of gene expression in vascular endothelial cells

Vascular endothelial cells are constantly exposed to wall shear stress generated by blood flow. Endothelial cells act as mechanoceptors sensing and responding to shear stress, and play a role in flow-dependent phenomena such as angiogenesis, vascular remodeling and atherosclerosis. Numerous recent studies have demonstrated that endothelial cell functions change in response to shear stress, and that the responses are often accompanied by changes in related gene expression. More recently there has been evidence that genes known to be regulated by shear stress may have a common cis-element (shear stress responsive element; SSRE) in their promoter regions. A molecular mechanism for endothelial cell responses to mechanical stress is close to being elucidated. In this paper, shear-stress-mediated regulation of endothelial gene expression is reviewed.

[Immunoglobulin and LST in RA patients treated with bucillamine]

In 79 RA patients treated with Bucillamine (Bu) we monitored IgG, A, M and total protein concentration x gamma-globulin% (Ig) before and after Bu. All of these four were lowered after Bu in both groups with and without adverse reaction. In the group with adverse reactions the serum level of IgG, A and Ig was significantly lower after Bu treatment than in the group without adverse reactions. The decreases of IgG and IgA were statistically significantly greater in the group with adverse reactions than those in the group without adverse reaction. The serum level of IgM after Bu in the effective group was significantly lower than that in the non-effective group. We also examined lymphocyte stimulation test (LST) in 44 RA patients treated with Bu. In the effective group Bu inhibited lymphocyte proliferative response to PPD more significantly than in the non-effective group. Bu also inhibited lymphocyte proliferative response after stimulation with PPD in the non-effective group doseresponsively. We concluded that the considerable decreases of IgG and IgA might correlate with the adverse reactions of Bu. The decrease of IgM and inhibition of LST with Bu might correlate with the efficacy of Bu.

Flow stimulates ICAM-1 expression time and shear stress dependently in cultured human endothelial cells

Human umbilical vein endothelial cells were subjected to controlled levels of shear stress in a flow-loading apparatus, and changes in the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were measured by flow cytometry. Application of shear stress (15 dynes/cm2) increased the cell surface expression of ICAM-1 2.7 times the control level 4 hr after the onset of flow, while it caused no change in VCAM-1 expression. The increase of ICAM-1 expression by shear stress was time- and force-dependent and reversible. Flow loading using perfusates with different viscosity revealed that the increase in ICAM-1 was shear-stress- rather than shear-rate-dependent. Reverse transcriptase/polymerase chain reaction analysis showed upregulation of ICAM-1 mRNA levels by shear stress, whose time course closely paralleled that of the cell surface protein. These results suggest that shear stress generated by blood flow acts as a regulator of cell adhesion molecule expression on vascular endothelial cells.

Down-regulation of vascular adhesion molecule-1 by fluid shear stress in cultured mouse endothelial cells

This study was undertaken to determine whether blood flow modulates the adhesive property of vascular endothelial cells to lymphocytes and, if it does, what adhesion molecules are involved. Cultured mouse endothelial cells were exposed to medium flow in a parallel plate chamber, and binding assay using fluorescence-labeled lymphocytes was carried out. The adhesion rate of endothelial cells to lymphocytes, which was high in the static control state, decreased when exposed to shear stress (1.5 dynes/cm2) for 6 h. The treatment of static endothelial cells with a monoclonal antibody of vascular cell adhesion molecule-1 (VCAM-1) depressed the adhesion rate to the same extent as that caused by flow, while monoclonal antibodies of CD44 and intercellular adhesion molecule-1 had no effect on it. Flow cytometric analysis revealed that the application of flow decreased markedly the amount of VCAM-1 expressed on the cell surface. A reverse transcriptase-polymerase chain reaction of mRNA showed that flow depressed VCAM-1 mRNA levels. These results suggest that blood flow can modulate the adhesive property of endothelial cells to lymphocytes via affecting the surface expression of adhesion molecules, e.g., down-regulation of VCAM-1.

Fluid shear stress increases the expression of thrombomodulin by cultured human endothelial cells

Endothelial cells (ECs) cultured from human umbilical vein were exposed to medium flow in a flow-loading chamber, and changes in thrombomodulin (TM) expression were examined by flow cytometry and enzyme linked immunosorbent assay with monoclonal antibody. The expression of TM antigen was increased time- and shear stress-dependently by flow, and when exposed to a shear stress of 15 dynes/cm2 for 24 hr, it increased to approximately 200% of the stationary control level. Reverse transcriptase-polymerase chain reaction showed that TM mRNA levels in ECs also increased in response to flow. TM mRNA began to increase one hour after the application of shear stress of 15 dynes/cm2 and reached a maximum (approximately 330% of stationary control) after eight hours. These results, demonstrating an up-regulating effect of flow on TM expression in ECs, suggest that shear stress may be an important modulator of intravascular blood coagulation.

Exogenous nitric oxide inhibits proliferation of cultured vascular endothelial cells

Cultured bovine fatal aortic endothelial cells (BAECs) were stimulated with nitric oxide (NO)-releasing vasodilators and NO gas-saturated solution, and changes in the cell proliferation were examined. Sodium nitroprusside (SNP) and nitroglycerin (NTG) shifted the growth curve downward, and inhibited 3H-thymidine incorporation by the ECs in a dose-dependent manner. Application of NO solution also reduced 3H-thymidine incorporation. SNP, NTG and NO solution increased the intracellular cGMP in BAECs. A cGMP analog, 8-bromo-cGMP, inhibited 3H-thymidine incorporation, and a guanylate cyclase inhibitor, methylene blue, almost completely blocked the inhibitory effect of SNP and NTG on 3H-thymidine incorporation. These findings suggest that exogenous NO inhibits EC proliferation, and that intracellular cGMP is involved in the inhibitory effect of NO.

Shear stress inhibits adhesion of cultured mouse endothelial cells to lymphocytes by downregulating VCAM-1 expression

Monolayers of endothelial cells (EC) cultured from mouse lymph nodes were exposed to controlled levels of shear stress (0-7.1 dyn/cm2) in a parallel plate flow chamber, and binding between the flow-loaded EC and mouse lymph node-derived lymphocytes was assayed. A large number of lymphocytes adhered to the stationary control EC, but in EC exposed to a shear stress of 1.5 dyn/cm2 for 6 h, the adhesion decreased to 68.8 +/- 12.8% (SD; n = 19) of control (n = 29, P < 0.001). The decrease in adhesion induced by flow loading was time and shear stress dependent and reversible. Treatment of stationary EC with a monoclonal antibody (MAb) to vascular cell adhesion molecule-1 (VCAM-1) reduced the adhesion to 70.6 +/- 11.5% (n = 19) of control (P < 0.001), whereas MAb to CD44 and to intercellular adhesion molecule-1 had no effect on it. Flow cytometric analysis revealed that the amount of VCAM-1 expressed on the cell surface was decreased to 48.5 +/- 15.8% (n = 6) of control by flow loading (P < 0.001). Flow loading experiments using two perfusates with different viscosities demonstrated that the decrease in VCAM-1 expression due to flow was shear stress rather than shear rate dependent. The detection of mRNA by reverse transcriptase-polymerase chain reaction showed that VCAM-1 mRNA levels were markedly depressed in EC exposed to flow loading.(ABSTRACT TRUNCATED AT 250 WORDS)

[Phase I study of CGS16949A--a new aromatase inhibitor. Cooperative Study Group for CGS16949A]

Phase I study of CGS16949A--a new aromatase inhibitor--was performed in postmenopausal women with advanced breast cancer who received either single oral administration of 4 and 8 mg, or multiple oral daily administration of 1, 2, 4, 8 and 16 mg for 5.5 days. No side effects were observed after single dose administration of 4 mg and 8 mg of CGS16949A. In the multiple administration, one patient received 1 mg/day for 3 days complained of abdominal pain (Grade 2), but administration of CGS16949 A was continued despite of the pain. In order to assess the causal relationship of the drug with the abdominal pain, the number of patients in 1 mg/day group was doubled from 3 to 6 patients, but no side effects were observed in the remaining five patients. In addition, no side effects, including abdominal pain, were noted in the other 2, 4, 8 and 16 mg/day groups. After multiple administration, plasma concentrations of estradiol at 5 hrs after the final dosage in the respective dose groups were reduced to 47.1 +/- 8.3%, 37.3 +/- 3.0%, 28.0 +/- 7.8%, 26.0 +/- 11.3% and 26.6 +/- 13.8% respectively. Similar tendencies were observed in estrone plasma levels and urinary estrogens levels. In this study, the reduction of plasma estrogen levels was confirmed following administration of CGS 16949A. The clinical usefulness of this new aromatase inhibitor remains to be studied further.

Laminar flow stimulates ATP- and shear stress-dependent nitric oxide production in cultured bovine endothelial cells

Based on the fact that nitric oxide (NO) production is associated with changes in intracellular cGMP levels and is selectively inhibited by N omega-methyl L-arginine (L-NME), we investigated the shear stress dependency of NO production in endothelial cells (ECs) from its cGMP responses to various shear stress loads. Cultured fetal bovine aortic ECs treated with a phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX; 1 mM), were exposed to a laminar flow of Krebs buffer solution for 5 minutes in a parallel-plate flow chamber and examined for changes in intracellular cGMP levels by radioimmunoassay using an [125I] cGMP kit. Application of flow increased the cGMP levels. The increase was significant in the presence of extracellular ATP (1 microM)(control, 286.1 +/- 43.6; flow, 506.5 +/- 44.9 fmol/10(7) cells; p < 0.001), but not in its absence (control, 256.6 +/- 60.6; flow, 301.5 +/- 91.4 fmol/10(7) cells; N.S.). The cGMP levels increased significantly as the magnitude of shear stress applied increased. Treatment of ECs with a specific inhibitor of NO production, L-NMA (200 microM), completely inhibited the flow-induced increase in cGMP, and L-arginine reversed the L-NMA-induced inhibition, indicating that the increase in cGMP was due to NO produced by the flow. The flow-induced increase in NO production was markedly suppressed when extracellular Ca++ was chelated by adding EGTA to the perfusate. These findings suggest that flow stimulates NO production to increase cGMP levels shear stress-dependently in ECs and that extracellular Ca++ and ATP modulate the effects of flow.

Intracellular calcium response to directly applied mechanical shearing force in cultured vascular endothelial cells

We studied the responses of cultured endothelial cells to mechanical shearing force directly applied to those cells in vitro to determine changes in the concentration of intracellular calcium ion (Ca++), one of the factors that transfers information within the cell. Cultured bovine fetal aortic endothelial cells containing the Ca++ fluorescence indicator, Fura-2, were rubbed with a latex balloon in a specially designed system, and changes in the fluorescence of Fura-2 caused by this shear stimulation were determined by photometric fluorescence microscopy. Immediately after shear stimulation, the concentration of Ca++ in the cells was increased and reached a peak (511 +/- 165 nM, n = 12) within 15 seconds after stimulation. After the peak, the concentration was gradually restored to the resting level (55 +/- 17 nM, n = 12). The magnitude of the Ca++ response was dependent on the intensity of the shear force applied. Analysis of fluorescence images of Fura-2 revealed that the cells showed this Ca++ reaction without being injured or desquamated, although there were slight differences in the degree and duration of reaction among cells. This reaction appeared even when the cells were placed in the air with no contact with the fluid. This result suggests that neither the fluid flow associated with the balloon movement nor chemical substances in the fluid are involved in the reaction, but that pure physical force alone is responsible for the Ca++ reaction. Further, it suggests that endothelial cells have the ability to perceive such physical stimulation as shear force and to transfer this information to the interior of the cell via changes in the intracellular Ca++ concentration.

[Treatment of advanced colorectal cancer with long-term continuous infusion of 5-fluorouracil]

The purpose of the study was to evaluate the efficacy of long-term continuous administration of 5-fluorouracil (5-FU) in ambulatory patients with colorectal cancer. Nineteen patients with advanced colorectal cancer were treated with continuous intravenous infusion of 5-FU (500 mg/day). The minimum duration of therapy was projected to be four weeks. In some patients 4 weeks interval therapy was selected and in other patients the duration of therapy was open-ended. A portable pump was used to deliver 5-FU continuously into the venous system at home. The pump had a subcutaneously placed port connected to a central venous catheter. In 19 patients, the duration of 5-FU infusion was 56 to 427 days (median: 139 days), and cumulative doses of 5-FU ranged from 28 to 173.5 g (median 69.5 g). Five patients achieved partial response (response rate: 26.3%), and the response lasted 80 to 339 days (median: 204 days). The fifty-percent survival time was 17 months. In 16 patients whose serum CEA level was elevated, there was a decrease to less than 50% among 11 patients (69%). Dose limiting toxicity was stomatitis in 4 patients and hand-foot syndrome in one, but they recovered after interruption of the infusion. Hematological toxicity was generally mild. No infusion-system related complication was encountered. Patients were able to be discharged and live at home during 82% of their survival period, while receiving this therapy. We concluded that this treatment is effective with tolerable toxicity and can be conducted at home.

[Role of hemodynamic factors in atherogenesis]

Since atherosclerotic lesions are apt to occur at specified regions in the blood vessels, hemodynamic factors, such as shear stress generated by blood flow, have been considered to play a role in atherogenesis. Atheroma, which is characterized by the localized accumulation of lipid and the proliferation of smooth muscle cells in the intima, appears at branching or curving sites of blood vessels, where both geometrical shape and blood flow change suddenly. In such sites, both stagnant and turbulent blood flow can occur and the direction and intensity of shear stress, acting on the vascular wall, changes transiently. Recent studies using cultured endothelial cells (EC) and flow-loading apparati have demonstrated that shear stress modulates various EC functions. Shear stress alters EC macromolecular permeability and affects the production of growth factors, by the EC, which stimulate smooth muscle cell proliferation. Shear stress also exerts an influence on EC turnover, which might be involved in the transport of low-density lipoproteins via leaky junctions. Furthermore, shear stress modulates the interaction between leukocytes and EC by changing the expression or functions of adhesion molecules. It is very likely that changes in EC functions induced by shear stress are involved in atherogenesis, but direct evidence demonstrating the role of shear stress in the initiation of atherosclerotic disease processes is still lacking. Further studies are needed to clarify the role of hemodynamic factors in atherogenesis.

[Immunoglobulin decrease accompanying adverse reactions with bucillamine]

Forty-two RA patients treated with Bucillamine (B) were divided into two groups with (n = 26) and without (n = 16) adverse reactions, and IgG, M, A and total protein concentration x globulin ratio (Ig) before and after B were compared. IgG did not differ before B administration, but was significantly lower in the adverse reactions group after B, and in each group it was significantly lower after B treatment with a much greater decrease demonstrated in the adverse reactions group. IgA before B did not differ either between the two groups or between before and after B administration in the non-adverse reaction group, but was significantly lower only after B in the adverse reaction group. IgM did not differ either before or after B treatment between the two groups, and was significantly lower following B administration in both groups. Ig showed results similar to IgA. In the adverse reaction group, IgG, A, M and Ig recovered following suspension of administration. It is concluded that the adverse reaction brought on by B administration might occur with the decrease in immunoglobulin.

The effect of flow on the expression of vascular adhesion molecule-1 by cultured mouse endothelial cells

Adherence of leukocytes to vascular endothelial cells (ECs) is known to be sensitive both to blood flow and adhesive proteins on EC surface. To elucidate the effect of blood flow on the surface expression of adhesive proteins, cultured ECs derived from mouse lymph nodes were exposed to different levels of wall shear stress in a flow-loading chamber, and changes in the expression of vascular adhesion molecule-1 (VCAM-1) and CD44 were evaluated by immunostaining with monoclonal antibodies and flow cytometry. Both proteins were expressed on non-activated cultured ECs. When exposed to flow with shear stress of 1.5 dynes/cm2 for 24 hr, VCAM-1 nearly disappeared on fluorescence micrographs, while CD44 showed no change. Flow cytometric analysis showed that the mean channel fluorescence of VCAM-1 was decreased about 75% by application of flow for 24 hr (p < 0.001), but that of CD44 remained unchanged. VCAM-1 expression began to decrease around 1 hr after the initiation of flow and became markedly reduced with time, reaching a minimum after 24 hr. When the cells subjected to flow for 24 hr were returned to stationary state, the reduced VCAM-1 expression was almost completely restored in 72 hr, indicating that the change was reversible. The magnitude of the reduction of VCAM-1 expression was also dependent on the intensity of the wall shear stress applied, ranging from 0 to 7.2 dynes/cm2. These results, demonstrating an explicit down-regulating effect of flow on VCAM-1 expression of cultured ECs, suggested preferential adhesion of leukocytes to ECs at low shear regions at the vascular wall.

Close correlation between cytoplasmic Ca++ levels and release of an endothelium-derived relaxing factor from cultured endothelial cells

We studied whether there is a quantitative relationship between free cytosolic Ca++ levels and the release of an endothelium-derived relaxing factor (EDRF) from cultured fetal bovine aortic endothelial cells (EC). EC pretreated with indomethacin were stimulated by the agonists adenosine triphosphate (ATP), bradykinin (BKN), acetylcholine (ACh) and calcium ionophore (A23187) in various concentrations (10(-8)-10(-5) M), and the amount of EDRF released was determined on the basis of endothelium-free rabbit aortic ring relaxation and cultured smooth muscle cell cGMP content. Changes in intracellular Ca++ concentration ([Ca++]i) in response to the same stimuli were determined by photometric fluorescence microscopy using the fluorescent calcium indicator Fura-2. EC stimulation by ATP and A23187 induced dose-dependent increases in both [Ca++]i and the amount of EDRF released. BKN increased both [Ca++]i and EDRF release upon initial exposure (10(-8)M), but there were no further changes at higher concentrations. ACh induced no significant changes in either [Ca++]i or EDRF release. There was a close quantitative correlation between agonist-induced changes in [Ca++]i and the amount of EDRF released (relaxation response in aortic rings and cGMP levels.) (p < 0.001) Removal of extracellular Ca++ eliminated continuous elevation in both [Ca++]i and the amount of EDRF induced by ATP (10(-5)M), BKN (10(-8)M) and A23187 (10(-6)M). These findings suggest that intracellular Ca++ levels are directly linked to the amount of EDRF released, and that extracellular Ca++ is essential for EDRF release because its influx is involved in the continuous elevation of [Ca++]i.

Wall shear stress rather than shear rate regulates cytoplasmic Ca++ responses to flow in vascular endothelial cells

Recent evidence suggests that the vascular endothelial cell (EC) can sense the flow-rate over its surface and according to the information, regulates not only its own morphology and functions but also those of the surrounding smooth muscle and other tissues. There is now a discussion over which of the following mechanisms actually initiates the signal-transacting response of EC against flow: the mechanical shear deformation of the cell due to flow-oriented wall shear stress (tau), or the diffusional accumulation of vasoactive agonists on the cell surface modulated by wall shear rate (gamma) or both. To identify the relative importance of each mechanism, we examined quantitative changes in the cytoplasmic free Ca++ concentration ([Ca++]i) in cultured EC in the presence of the Ca++ mobilizing agonist ATP, i.e., a second messenger response of the internal signalling system, following the perfusion of two buffers with different viscosities (mu), which relates these factors as tau = mu gamma. The results of in vitro fluorescence photometry in EC with Fura-2 showed that the [Ca++]i level was enhanced with increase in the shear rate but to a greater extent with higher viscosity, and that the [Ca++]i levels at the same calculated level of shear stress were virtually identical, regardless of difference in shear rate and viscosity. This quantitative one-to-one relationship between the shear stress and the second messenger response suggests that wall shear stress rather than wall shear rate is the principal physical factor eliciting EC responses to flow.

The effects of two EFL (English as a foreign language) teaching approaches studied by the cotwin control method: a comparative study of the communicative and the grammatical approaches

The present study compared two different types of English-language teaching approaches, the grammatical approach (GA) and the communicative approach (CA), by the cotwin control method. This study has two purposes: to study the effects of teaching approaches and to estimate genetic influences upon learning aptitudes. Seven pairs of identical twins (MZ) and 4 pairs of fraternal twins (DZ) participated in the experiment along with 68 other nontwin fifth graders. Each cotwin was assigned to the GA and CA respectively and received 20 hours of lessons over a 10-day period. The behavioral similarities between MZ cotwins were statistically and descriptively depicted. No major effect of either teaching approach was noted, but the genetic influence upon individual differences of learning achievement was obvious. Furthermore, an interesting interaction between the teaching approaches and intelligence was found, that is, that the GA capitalises on and CA compensates for intelligence. This interactional pattern could be interpreted as an example of genotype-environment interaction. The relationship between genetic factors and learning aptitudes is discussed.

Synthesis and antitumor activity of tropolone derivatives. 7. Bistropolones containing connecting methylene chains

Bistropolone derivatives (4-12) containing differing lengths of linkage between the two tropolone rings were prepared and examined for their antitumor activity in in vitro (KB cell) and in vivo (leukemia P388 in mice) systems. Parent compound 3, related compounds previously prepared, and the new compounds 4-12 were evaluated for inhibitory activity against ribonucleotide reductase by indirect means to measure their effects on the dNTP pool imbalance. Present structure-activity relationship results would suggest that potently active bistropolones in vivo inhibit intracellular ribonucleotide reductase through chelating with the two irons at the two active sites of the enzyme.

Flow effects on cultured vascular endothelial and smooth muscle cell functions

Cultured vascular endothelial cells were exposed to fluid shear stress by means of a rotary-disc shear-loading device, and the physiological effects of the conditioned medium (CM) and the homogenate (HM) of the cells on migration, adhesion and growth of endothelial cells (EC) or smooth muscle cells (SMC) were studied. Effects of shear stress on the production and secretion of collagen, one of the extracellular matrices of EC, were also studied. CM stimulated the adhesion and growth of SMC, but not of EC themselves. The ability to stimulate SMC adhesion and growth was similar in CM obtained from the static and shear-loaded cells. HM of the shear-loaded EC stimulated SMC migration. Further, HM of the shear-loaded EC contained increased amounts of collagen compared with the static EC. These results suggest that: 1) EC produce and secrete accelerators for the adhesion and growth of SMC, 2) EC react to the physical stimulus of fluid shear stress to produce stimulators of SMC migration, and 3) EC produce collagen, the production of which is enhanced by fluid shear stress.