Calcium regulation of skeletal muscle thin filament motility in vitro

Using an in vitro motility assay, we have investigated Ca2+ regulation of individual, regulated thin filaments reconstituted from rabbit fast skeletal actin, troponin, and tropomyosin. Rhodamine-phalloidin labeling was used to visualize the filaments by epifluorescence, and assays were conducted at 30 degrees C and at ionic strengths near the physiological range. Regulated thin filaments exhibited well-regulated behavior when tropomyosin and troponin were added to the motility solutions because there was no directed motion in the absence of Ca2+. Unlike F-actin, the speed increased in a graded manner with increasing [Ca2+], whereas the number of regulated thin filaments moving was more steeply regulated. With increased ionic strength, Ca2+ sensitivity of both the number of filaments moving and their speed was shifted toward higher [Ca2+] and was steepest at the highest ionic strength studied (0.14 M gamma/2). Methylcellulose concentration (0.4% versus 0.7%) had no effect on the Ca2+ dependence of speed or number of filaments moving. These conclusions hold for five different methods used to analyze the data, indicating that the conclusions are robust. The force-pCa relationship (pCa = -log10[Ca2+]) for rabbit psoas skinned fibers taken under similar conditions of temperature and solution composition (0.14 M gamma/2) paralleled the speed-pCa relationship for the regulated filaments in the in vitro motility assay. Comparison of motility results with the force-pCa relationship in fibers suggests that relatively few cross-bridges are needed to make filaments move, but many have to be cycling to make the regulated filament move at maximum speed.

Vascular endothelial growth factor/vascular permeability factor augments nitric oxide release from quiescent rabbit and human vascular endothelium

BACKGROUND

Vascular endothelial growth factor (VEGF)/ vascular permeability factor (VPF) is an endothelial cell (EC) mitogen. This feature is considered central to the documented role of VEGF/VPF in promoting angiogenesis. More recent evidence suggests that VEGF/VPF may also serve a "maintenance" function, modulating various aspects of EC biology. In the present study, we sought to determine the extent to which VEGF/VPF may stimulate the release of NO from normal ECs.

METHODS AND RESULTS

VEGF/VPF produced a dose-dependent rise in NO concentration ([NO]) from vascular segments of rabbit thoracic aorta, pulmonary artery, and inferior vena cava. In comparison to stimulation with acetylcholine, the onset of increased [NO] after administration of VEGF/VPF was slower, reaching a maximum value after 8 minutes. Preincubation of the aortic segments with L-arginine raised by twofold both baseline [NO] and [NO] stimulated by addition of 2.5 micrograms/mL VEGF/VPF. Removal of CaCl2 from the Krebs solution, disruption of the endothelium, and administration of NG-monomethyl-L-arginine abrogated the stimulatory effect of 10 micrograms/mL VEGF/VPF. Similar findings were documented with an NO-specific polarographic electrode to measure NO released from cultured human umbilical vein ECs.

CONCLUSIONS

VEGF/VPF stimulates production of NO from rabbit and human ECs. This finding (1) constitutes inferential evidence for the presence of functional VEGF/VPF receptors on quiescent endothelium of the adult rabbit as well as human ECs and (2) supports the notion that putative maintenance functions of VEGF/VPF may include regulation of baseline synthesis and/or release of EC NO.

[A primary observation of the active immune prevention effects against dental caries using the streptococcus mutans surface protein P1 in rats]

To observe the anti-caries effects of a small dose of the surface protein antigen P1. The SD rats were immunized with P1-CTB and P1-PCG through IN (intranasal immunization) and IG (intragastric immunization). The results showed that caries was reduced heavily. There was no obvious difference between IN and IG. P1-CTB and P1-PCG can be used as an antigen to prevent the dental caries, but much further research work still need to do.

[An animal model for the mucosal immunization with the surface protein antigen P1 from streptococcus mutans and immune enhancement of cholera toxin]

To study the immune enhancement of cholera toxin by developing an mucosal immune animal model, SD rats were immunized using different antigen composition through intragastric route (I.G). The results showed that the effects of immunization became stronger after P1 was conjugated to cholera toxin B subunit (CTB) or procholeragenoid (PCG). Even microgram dose of P1 could induce the rising of anti-P1 SIgA antibodies in the rat's saliva, but the antibodies risied little without this adjuvant. These implayed that the conjugation was much necessary in IG immunization. The immune enhancement of PCG was greater than that of CTB.

[Conjugation and identification of the surface protein antigen P1 from streptococcus mutans MT6R with the cholera toxin B subunit and procholeragenoid]

To make an effective antigen to prevent dental caries, the surface protein antigen P1(Ag I/II) was purified and identified by the rabbit anti-Ag I/II serum and was covalently conjugated to CTB and PCG by SPDP respectively. GM1-ELISA showed that both the conjugated P1-CTB and P1-PCG possess the ability to bind GM1 specifically without losing the antigenicity of P1. This results showed that the conjugated antigens could be used in the immune prevention against dental caries.

[The correlation between expression of oncogene protein products p53, p21, p185 and cell differentiation and prognosis in rhabdomyosarcoma]

OBJECTIVE

To study the correlation between expression of oncogene protein products p53, P21, p185 and histological type, cell differentiation and prognosis in rhabdomyosarcoma (RMS).

METHODS

41 RMS cases which had follow-up material were selected for this study. Expression of protein products of oncogene p53, p21 and p185 were synchronously detected and compared by immunohistochemical ABC method.

RESULTS

The positive rates for p53, p21 ras and P185 c-erbB-2 were 72%, 68% and 60% respectively. Positive expression did not relate to age, sex or RMS histological type, but related to the degree of RMS differentiation. The positive rate of p53 ad p21 ras in well differentiated cases were 42.9% and 28.6% while that of the poorly differentiated group was 85% and 80% respectively (P < 0.05). The psoitive rate of p53 in the RMS group with metastasis was 86.6%, significantly higher than that of the non-metastasized group, which was 66.7% (P < 0.05). There was a significant difference between those with one year survival, whose p52 positive rate was 86.7% and those who survived for more than 3 years, whose p53 positive rate was 47.1% (P < 0.05).

CONCLUSION

The results suggest that the irregular expressions of p53 and p21 were related to tumor differentiation and the degree of malignancy. p53 positivity may indicate a poor prognosis.

Actin-binding protein-280 binds the stress-activated protein kinase (SAPK) activator SEK-1 and is required for tumor necrosis factor-alpha activation of SAPK in melanoma cells

SEK-1, a dual specificity protein kinase that serves as one of the immediate upstream activators of the stress-activated protein kinases (SAPKs), associates specifically with the actin-binding protein, ABP-280, in vitro and in situ. SEK-1 binds to the carboxyl-terminal rod segment of ABP-280, upstream of the ABP carboxyl-terminal dimerization domain. Activation of SEK-1 in situ increases the SEK-1 activity bound to ABP-280 without changing the amount of SEK-1 polypeptide bound. The influence of ABP-280 on SAPK regulation was evaluated in human melanoma cells that lack ABP-280 expression, and in stable transformants of these cells expressing wild type ABP, or an actin-binding but dimerization-deficient mutant ABP (ABPDeltaCT109). ABP-280-deficient cells show an activation of SAPK in response to most stimuli that is comparable to that seen in ABP-280-replete cells; ABP-280-deficient cells, however, fail to show the brisk tumor necrosis factor-alpha (TNF-alpha) activation of SAPK seen in ABP-replete cells and have an 80% reduction in SAPK activation by lysophosphatidic acid. Expression of the dimerization-deficient mutant ABP-280 fails to correct the defective SAPK response to lysophosphatidic acid, but essentially normalizes the TNF-alpha activation of SAPK. Thus, a lack of ABP-280 in melanoma cells causes a defect in the regulation of SAPK that is selective for TNF-alpha and is attributable to the lack of ABP-280 polypeptide itself rather than to the disordered actin cytoskeleton that results therefrom. ABP-280 participates in TNF-alpha signal transduction to SAPKs, in part through the binding of SEK-1.

Vaccination with a multi-epitopic recombinant allergen induces specific immune deviation via T-cell anergy

Prophylactic vaccination has recently emerged as a major paradigm toward the prevention and therapy of allergies and asthma; however, the immunological basis of this approach remains to be elucidated. We examined the potential and mechanism of prophylaxis of allergic response in B6D2F1 mice with a multi-epitopic recombinant allergen, rKBG8.3 (MERA-8.3), which represents a major group of allergens of grass pollens, used herein as a model of MERA vaccine. Vaccination (subcutaneous) with soluble MERA-8.3, prior to immunization with the MERA-8.3 in alum, led to suppression of the IgE antibody response and a concomitant increase in IgG2a antibody response specific to the MERA-8.3 in a dose-dependent manner. Analysis of cytokine patterns in spleen and lymph node cells revealed a marked decrease of interleukin-2 (IL-2) and IL-4 production and to a lesser extent a decrease of interferon-gamma (IFN-gamma) synthesis, resulting in an increased ratio of IFN-gamma: IL-4 in vaccinated-immunized mice compared with untreated-immunized control mice. Furthermore, splenocytes of mice treated with the MERA-8.3 alone proliferated to MERA-8.3 in vitro with reduced capacity compared with the splenocytes of MERA-8.3-alum immunized mice, owing to a markedly reduced level of IL-2 production in the former. Collectively, these results suggest that vaccination with the MERA-8.3 induces T-cell anergy, which is pivotal to deviation of specific immunity from Th2- to Th1-like, and may serve as an important approach to prevention and therapy of allergic disorders.

An intact Raf zinc finger is required for optimal binding to processed Ras and for ras-dependent Raf activation in situ

The function of the c-Raf-1 zinc finger domain in the activation of the Raf kinase was examined by the creation of variant zinc finger structures. Mutation of Raf Cys 165 and Cys 168 to Ser strongly inhibits the Ras-dependent activation of c-Raf-1 by epidermal growth factor (EGF). Deletion of the Raf zinc finger and replacement with a homologous zinc finger from protein kinase C gamma (PKC gamma) (to give gamma/Raf) also abrogates EGF-induced activation but enables a vigorous phorbol myristate acetate (PMA)-induced activation. PMA activation of gamma/Raf does not require endogenous Ras or PKCs and probably occurs through a PMA-induced recruitment of gamma/Raf to the plasma membrane. The impaired ability of EGF to activate the Raf zinc finger variants in situ is attributable, at least in part, to a major decrement in their binding to Ras-GTP; both Raf zinc finger variants exhibit decreased association with Ras (V12) in situ upon coexpression in COS cells, as well as diminished binding in vitro to immobilized, processed COS recombinant Ras(V12)-GTP. In contrast, Raf binding to unprocessed COS or prokaryotic recombinant Ras-GTP is unaffected by Raf zinc finger mutation. Thus, the Raf zinc finger contributes an important component to the overall binding to Ras-GTP in situ, through an interaction between the zinc finger and an epitope on Ras, distinct from the effector loop, that is present only on prenylated Ras.

Capacitive function of the heart: influence of acute changes in heart volume on mean right atrial pressure

Net transfer of blood volume into or out of the cardiac chambers should have the same effect on central venous pressure as does transfer of an equal volume of blood to or from peripheral organs (e.g., spleen, or liver). We studied five pentobarbital sodium-anesthetized open-chest pigs (20-23 kg) to determine whether a reduction in the time-averaged volume of blood contained in the heart, induced by rapid atrial pacing, can raise right atrial pressure. A central premise of our study is that the mean value of right atrial pressure is acutely governed by the volume of blood that distends the central veins, and that atrial contractions primarily determine how atrial pressure varies about its mean value. To prevent changes in cardiac output from altering central blood volume and pressure, cardiac output during rapid pacing (2.36 +/- 0.18 l/min) was made to equal the resting output (2.35 +/- 0.16 l/min). This was achieved by selecting a rate of pacing at which the tendency for more frequent cardiac contractions to raise cardiac output was counterbalanced by the decrease in stroke volume induced by rapid pacing. Autonomic reflex mechanisms were attenuated by pharmacological blockade. Mean arterial pressure was minimally affected in the transition from a normal sinus rhythm (89 +/- 6 beats/min) to rapid atrial pacing (165 +/- 7 beats/min) in four pigs. Mean right atrial pressure rose abruptly from 2.8 +/- 0.5 mmHg during normal sinus rhythm to 3.5 +/- 0.5 mmHg (P = 0.015) at the onset of rapid pacing in these four pigs, presumably owing to decreased cardiac blood volume and a reciprocal expansion of central venous volume. In the fifth pig, a reduction in cardiac output induced by tachycardia led to a larger rise in mean right atrial pressure than did a reduction in cardiac output induced by bradycardia, presumably because tachycardia reduces cardiac blood volume whereas bradycardia raises cardiac volume. We conclude that the heart may play an important role in maintaining or raising its own filling pressure when heart rate rises.

Identification of multiple rabbit flavin-containing monooxygenase form 1 (FMO1) gene promoters and observation of tissue-specific DNase I hypersensitive sites

We have cloned and partially characterized the rabbit FMO1 gene as a first approach to understanding mechanisms controlling its tissue-specific expression. The isolated clones contain 14 kb of 5' flanking information and approximately 30 kb of the structural gene, but do not include the 3'-end. Two upstream exons were defined, both encoding 5' leader information. The first exon, termed exon 0, contains information not previously reported. The second exon, termed exon 1, contains information previously reported for the rabbit FMO1 cDNA. Protein coding information begins seven nucleotides from the start of exon 2. A single transcription start site was localized in exon 1, while a cluster of sites were defined in exon 0, consistent with two alternative promoters. Transcripts initiating in exon 0 do not contain exon 1 information due to alternative processing and represent the major FMO1 mRNA. Neither promoter contains a TATA box or GC islands, although the exon 1 promoter does share some sequence identity with initiator-type elements. Homologous sequences to several known transcription factor binding sites were found in the upstream region of the FMO1 promoters. Both promoters were active in directing luciferase expression when transiently transfected into human HepG2 cells, although the data are consistent with both requiring upstream enhancer sequences. Consistent with this observation, DNase I hypersensitive sites were mapped to a 600-bp region immediately upstream of exon 0 using liver nuclei. No such sites were detected with nuclei from lung. Differential DNA methylation also was not observed between these two tissues.

Involvement of p21cip-1 and p27kip-1 in the molecular mechanisms of steel factor-induced proliferative synergy in vitro and of p21cip-1 in the maintenance of stem/progenitor cells in vivo

Steel factor (SLF) is a hematopoietic cytokine that synergizes with other growth factors to induce a greatly enhanced proliferative state of hematopoietic progenitor cells and factor-dependent cell lines. Even though the in vivo importance of SLF in the maintenance and responsiveness of stem and progenitor cells is well documented, the molecular mechanism involved in its synergistic effects are mainly unknown. Some factor-dependent myeloid cell lines respond to the synergistic proliferative effects of SLF plus other cytokines in a manner similar to that of normal myeloid progenitor cells from bone marrow and cord blood. We show here that SLF can synergize with granulocyte-macrophage colony-stimulating factor (GM-CSF) to induce an enhanced phosphorylation of the retinoblastoma gene product and a synergistic increase in the total intracellular protein level of the cyclin-dependent kinase inhibitor, p21cip-1, which is correlated with a simultaneous decrease in p27kip-1 in the human factor-dependent myeloid cell line, M07e. Moreover, these cytokines synergize to increase p21cip-1 binding and decrease p27kip-1 binding to cyclin-dependent kinase-2 (cdk2), an enzyme required for normal cell cycle progression; these inverse events correlated with increased cdk2 kinase activity. It is also shown that exogenous purified p21cip-1 can displace p27kip-1 already bound to cdk2 in vitro. These data implicate increased p21cip-1 and decreased p27kip-1 intracellular concentrations and their stoichiometric interplay in the enhanced proliferative status of cells stimulated by the combination of SLF and GM-CSF. In support of these findings, it is shown that hematopoietic progenitor cells from mice lacking p21cip-1 are defective in SLF synergistic proliferative response in vitro. Moreover, the cycling status of marrow and spleen progenitors and absolute numbers of marrow progenitors were significantly decreased in the p21cip-1 -/-, compared with the +/+ mice. We conclude that the cdk threshold regulators p21cip-1 and p27kip-1 play a critical role in the normal mitogenic response of M07e cells and murine myeloid progenitor cells to these cytokines and particularly in the SLF synergistic proliferative response that is important to the normal maintenance of the stem/progenitor cell compartment.

RASSE: a new method for structure-based drug design

A novel method, RASSE, has been developed to suggest reasonable structures which can fit well to the binding sites of receptors. Molecules are generated by an iterative growing procedure in which atoms are added to existing fragments. Potential ligands are then picked out by special scoring rules. This atomgrowing based method is characterized by combinatorial searching of atom types and conformations. To some extent, it is the computer simulation of combinatorial chemistry. This method has been applied to the design of inhibitors for E. coli dihydrofolate reductase and human phospholipase A2. The results demonstrate that this program is capable of generating reasonable structures, thus proving its power in drug design.

A method for co-localization of tubular lysosomes and microtubules in macrophages: fluorescence microscopy of individual cells

Routinely used procedures for chemical fixation often fail to preserve delicate membrane-bounded tubular structures in a variety of cell types. Fixation procedures commonly employed in immunocytochemical studies for localization of structural proteins, such as those found in cytoskeletal elements, may also degrade these tubular structures. Here we describe a procedure that preserves the elaborate tubular lysosome system found in stimulated macrophages and allows the subsequent immunofluorescence localization of microtubules in the same cells. Use of this methodology permits the assessment of the spatial relationship between tubular lysosomes and microtubules in macrophages.

Oligomerization activates c-Raf-1 through a Ras-dependent mechanism

The c-Raf-1 proto-oncoprotein is a Ras-GTP-regulated protein kinase that associates in situ with 14-3-3 proteins, which are naturally dimeric. In COS cells, recombinant Raf is found in oligomeric assemblies. To examine whether induced oligomerization can alter Raf kinase activity, sequences encoding the FK506-binding protein FKBP12 were fused to the amino terminus of c-Raf-1, introducing a binding site for FK506. Oligomerization of recombinant FKBP-Raf in situ, induced by the addition of the dimeric FK506 derivative FK1012A, activated Raf kinase activity at least half as well as epidermal growth factor (EGF). As with EGF, activation of FKBP-Raf by FK1012A is entirely Ras-GTP dependent. Thus oligomerization of Raf per se promotes Raf activation through a Ras-dependent mechanism.

Induction of acetylcholine receptor gene expression by ARIA requires activation of mitogen-activated protein kinase

Transcription of genes encoding nicotinic acetylcholine receptor (AChR) subunits (alpha, beta, gamma or epsilon, and delta) is highest in nuclei localized to the synaptic region of the muscle, which contributes to maintain a high density of AChRs at the postjunctional membrane. ARIA (AChR inducing activity) is believed to be the trophic factor utilized by motor neurons to stimulate AChR synthesis in the subsynaptic area. To elucidate the signaling mechanism initiated by ARIA, we established stable C2C12 cell lines carrying the nuclear lacZ gene under the control of the mouse epsilon subunit promoter or chicken alpha subunit promoter. ARIA stimulated tyrosine phosphorylation of erbB proteins in these C2C12 cells within 15 s with a peak at 5 min. Immediately following tyrosine phosphorylation of erbB proteins, mitogen-activated protein (MAP) kinase was activated which occurred within 30 s and peaked at 8 min after ARIA stimulation. Concomitantly, expression of AChR genes was induced by ARIA. ARIA-induced AChR subunit transgene expression was observed only in differentiated myotubes and not in myoblasts, suggesting that downstream signaling component(s) are regulated in a manner dependent on the myogenic program. Inhibition of the MAP kinase activity by using a specific MAP kinase kinase inhibitor or by overexpressing dominant negative mutants of Raf or MAP kinase kinase attenuated or abolished the ARIA-induced activation of AChR alpha and epsilon subunit gene expression. These results indicate that regulation of AChR gene expression by ARIA in C2C12 cells requires activation of the MAP kinase signaling pathway.

[The experience in applying bovine pericardial patch in the correction of tetralogy of Fallot]

From January 1982 to December 1994, 432 patients with tetralogy of Fallot underwent the corrective operation. We extended the right ventricular outflow tract (RVOT) in 271 of the patients by using bovine pericardial patch treated by glutaraldehyde. The results were satisfactory. We emphasize that bovine pericardial patch is good material for extending RVOT, because it has many merits including high intensity, satisfied suture, no leakage, and abundant supply. Long-term follow up (maximum 12 years and 3 months) showed no ventricular aneurysm due to the degeneration of bovine pericardial patch.

Role of an upstream open reading frame in mediating arginine-specific translational control in Neurospora crassa

The Neurospora crassa arg-2 transcript contains an upstream open reading frame (uORF) specifying a 24-residue leader peptide and is subject to a novel form of negative translational regulation in response to arginine. The role of the arg-2 uORF in arginine-specific negative regulation was investigated by using translational fusions of wild-type and mutant arg-2 sequences to the Escherichia coli lacZ reporter gene specifying beta-galactosidase. The wild-type uORF conferred Arg-specific regulation on the reporter gene in N. crassa, but mutated or truncated uORFs did not, as determined by measurements of beta-galactosidase activity produced in N. crassa strains expressing arg-2-lacZ fusion genes. All effects on reporter gene expression were posttranscriptional, as determined by measurement of RNA levels. Both sequence-dependent and sequence-independent effects of uORFs were observed. Genes containing the wild-type uORF or a 21-codon mutated uORF showed reduced translation in comparison with that of a gene lacking a uORF. Both uORF-containing transcripts showed reduced association with polysomes relative to transcripts lacking a uORF, but only the transcript with the wild-type uORF showed a reduced average number of ribosomes associated with it in response to arginine addition. Direct translational fusions between uORF sequences and lacZ sequences indicated that the uORF is translated. Overlapping the uORF with the lacZ initiation codon indicated that ribosome reinitiation at a downstream start codon is not integral to uORF-mediated, Arg-specific translational regulation. These studies provide direct biochemical evidence for arg-2 uORF function in translational control.

[Regenerating axons selectively reinnervate their target organs after the peripheral nerves were tubulated]

This study investigated target specificity during axonal regeneation of a mixed motor and sensory nerve after the canine tibial nerves were tubulated. 10mm gap of tibial nerve was connected by silicone tube. Three months later, the second operation was performed by spinal dorsal root ganglion (DRG) resection at the experimental side. Five months later, histalogical analysis results reveal that the regenerating motor nerve fibre of mixed nerve selectively grew into motor branches. The mean number of regenerated motor nerve fibers grew into its motor branches was 1199, and the number of that into its sensory branch was only 21. This result suggests that regenerating motor and sensory axons of mixed nerve can across 10-mm silicone chamber and be able to select their distal target organs exectly.

Analysis of Tcrvb8, Il4, and Ifg as genetic predisposition factors for atopic IgE response in a murine model

Allergen-induced synthesis of lgE Abs in genetically predisposed individuals constitutes the hallmark of allergic diseases; however, the molecular basis of this genetic predisposition remains unknown. T cell cytokines lL-4 and IFN-gamma reciprocally regulate lgE synthesis and are potential genetic factors governing atopy. To examine the inheritance patterns of IgE responsiveness and address the role of these cytokines as genetic predisposition factors, in this study we established a MHC-identical mouse colony comprising crosses between two inbred strains of mouse, A.SW and SJL, respectively representing high and low IgE responder phenotypes. Segregation analysis with 149 [(A.SW x SJL)F1 x SJL] backcross and 148 [(A.SW x SJL)F1 x F1]F2 mice suggested that persistent high IgE responsiveness was inherited as a simple Mendelian dominant trait under the control of a single non-MHC, autosomal gene of major effect in these strains. Since SJL lacked Tcrvb8 genes, we examined the possibility of Tcrvb8 as a candidate gene for IgE responsiveness. The results suggested association of neither the Tcrvb8 gene nor its expression with allergen-induced IgE phenotype. Furthermore, microsatellite marker and gene sequencing analyses revealed that neither of the ll4 and lfg genes was associated with IgE phenotype. Moreover, correlation studies between IgE and cytokine levels in splenocyte cultures indicated that IgE levels were moderately to poorly correlated with IL-4 and IFN-gamma levels. It is concluded that even though expression of Tcrvb8, II4, and Ifg genes may play pivotal roles in IgE regulation, these genes per se do not contribute to genetic predisposition of allergen-induced IgE hyperresponsiveness in these strains of mice.

Analysis of Tcrvb8, Il4, and Ifg as genetic predisposition factors for atopic IgE response in a murine model

Allergen-induced synthesis of lgE Abs in genetically predisposed individuals constitutes the hallmark of allergic diseases; however, the molecular basis of this genetic predisposition remains unknown. T cell cytokines lL-4 and IFN-gamma reciprocally regulate lgE synthesis and are potential genetic factors governing atopy. To examine the inheritance patterns of IgE responsiveness and address the role of these cytokines as genetic predisposition factors, in this study we established a MHC-identical mouse colony comprising crosses between two inbred strains of mouse, A.SW and SJL, respectively representing high and low IgE responder phenotypes. Segregation analysis with 149 [(A.SW x SJL)F1 x SJL] backcross and 148 [(A.SW x SJL)F1 x F1]F2 mice suggested that persistent high IgE responsiveness was inherited as a simple Mendelian dominant trait under the control of a single non-MHC, autosomal gene of major effect in these strains. Since SJL lacked Tcrvb8 genes, we examined the possibility of Tcrvb8 as a candidate gene for IgE responsiveness. The results suggested association of neither the Tcrvb8 gene nor its expression with allergen-induced IgE phenotype. Furthermore, microsatellite marker and gene sequencing analyses revealed that neither of the ll4 and lfg genes was associated with IgE phenotype. Moreover, correlation studies between IgE and cytokine levels in splenocyte cultures indicated that IgE levels were moderately to poorly correlated with IL-4 and IFN-gamma levels. It is concluded that even though expression of Tcrvb8, II4, and Ifg genes may play pivotal roles in IgE regulation, these genes per se do not contribute to genetic predisposition of allergen-induced IgE hyperresponsiveness in these strains of mice.

[A study on the effective way and dosage of intravas deferens injection of HFMC for male contraception]

To investigate the effective way and dosage of intravas deferens injection of HFMC for male contraception, Teflon tubes of 1 mm caliber were used to imitate intravas injection of HFMC. We injected HFMC first, then the precipitant; thus HFMC could adhere to the walls and blend with the precipitant to precipitate. Eight adult male rabbits, exposed reproductive ducts were injected with dyed HFMC in opposite directions (upward and downward), HFMC flowed out of the distal end of the vas easily when its volume was more than that of the vas. 14 adult rabbits were used for the comparison of sperm density and fertility index between upward and downward injections of HFMC, and between the dosage of HFMC (50 microliters and 100 microliters) injected upward. The results show that it is difficult to attain contraception by intravas injection of HFMC downward, but contraception is quite possible by intravas injection of HFMC upward providing the volume is enough. The result also suggest that HFMC should be injected into vas deferens upward first; its volume should be 3 time as much as the natural volume of the vas from the injecting point to the epididymal end. Then a little precipitant is injected into the vas.

[Clinicopathologic analysis of ependymoma in childhood]

A review of the clinicopathologic features of 23 ependymomas in children was made, of which 17 were male and 6 female, the male:female ratio being 2.8:1. Their average age was 8.8 years. Seven of the 23 ependymomas were supratentorial, 16 were infratentorial. The mean duration of symptoms prior to operation in the two groups was 5.3 and 3 months respectively. Histologically, the tumor could be classified into three types: papillary (or myxopapillary), epithelial and cellular. According to the degree of differentiation, the tumor could be divided into typical ependymoma and anaplastic ependymoma. Immunohistochemically, 17 of the 23 cases were positive for glial fiber acid protein (GFAP) and the remaining 6 cases were negative. The clinicopathologic features of childhood ependymomas, factors influencing prognosis and histologic classification are discussed.

Antioxidant and iron-chelating agents in cerebral vasospasm

Prior work in our laboratory showed that the perivascular application of deferoxamine (an antioxidant and iron-chelating agent) inhibited delayed arterial narrowing after chronic blood exposure in a rat femoral artery model of vasospasm. To determine which of these mechanisms was operant in vasospasm, we compared deferoxamine with two agents (ascorbic acid and U74389F) that have antioxidant but not iron-chelating capacity. For the systemic application of drugs in 23 rats, whole blood encased in a silastic cuff was applied to the right femoral artery of each rat; whole-blood serum (lacking erythrocytes) was similarly applied to the left femoral artery. Deferoxamine (30 mg/kg/d), ascorbic acid (1000 mg/kg/d), U74389F (30 mg/kg/d), or pH-matched control vehicle was administered three times daily by intraperitoneal injection for 7 days. After exposure to whole blood, arteries treated with intraperitoneal vehicle showed an 85% reduction in the lumen, compared with vessels exposed to erythrocyte-free serum (P < 0.001). Intraperitoneal ascorbic acid and U74389F produced moderate amelioration in arterial narrowing (53 and 61% decrease, respectively, in the lumen versus controls; P < 0.05 versus vehicle); deferoxamine had no significant effect when administered intraperitoneally. To test the efficacy of these agents by the perivascular application of drugs, whole blood was applied to both femoral arteries in each of 25 rats. Solutions of deferoxamine (10 mg/ml), ascorbic acid (50 or 100 mg/ml), or U74389F (15 or 30 mg/ml) were directly applied to the perivascular thrombus surrounding the femoral arteries, compared with vehicle applied to contralateral vessels. The perivascular application of 50 mg of ascorbic acid (36% reduction, P < 0.05), 100 mg of ascorbic acid (31% reduction, P < 0.01), or 10 mg of deferoxamine (41% reduction, P < 0.05) significantly inhibited arterial narrowing, compared with vehicle. The application of U74389F at a dose of 15 or 30 mg directly into the perivascular thrombus produced nonsignificant reduction in arterial narrowing. These data suggest that mechanisms other than direct iron toxicity, such as generation of cytotoxic free radicals, may play an important role in cerebral vasospasm. In addition, the route of administration and concentration of drugs in the perivascular region adjacent to the thrombus may be critical to their efficacy.

Translational regulation in response to changes in amino acid availability in Neurospora crassa

We examined the regulation of Neurospora crassa arg-2 and cpc-1 in response to amino acid availability.arg-2 encodes the small subunit of arginine-specific carbamoyl phosphate synthetase; it is subject to unique negative regulation by Arg and is positively regulated in response to limitation for many different amino acids through a mechanism known as cross-pathway control. cpc-1 specifies a transcriptional activator important for crosspathway control. Expression of these genes was compared with that of the cytochrome oxidase subunit V gene, cox-5. Analyses of mRNA levels, polypeptide pulse-labeling results, and the distribution of mRNA in polysomes indicated that Arg-specific negative regulation of arg-2 affected the levels of both arg-2 mRNA and arg-2 mRNA translation. Negative translational effects on arg-2 and positive translational effects on cpc-1 were apparent soon after cells were provided with exogenous Arg. In cells limited for His, increased expression of arg-2 and cpc-1, and decreased expression of cox-5, also had translational and transcriptional components. The arg-2 and cpc-1 transcripts contain upstream open reading frames (uORFs), as do their Saccharomyces cerevisiae homologs CPA1 and GCN4. We examined the regulation of arg-2-lacZ reporter genes containing or lacking the uORF start codon; the capacity for arg-2 uORF translation appeared critical for controlling gene expression.

Synergistic induction of phospholipid metabolism by granulocyte-macrophage colony stimulating factor and steel factor in human growth factor-dependent cell line, M07e

Steel factor (SLF), the ligand for the c-kit proto-oncogene tyrosine kinase receptor, synergizes with several hematopoietic growth factors to produce greatly enhanced proliferation of normal human hematopoietic progenitor cells as well as that of the human growth factor-dependent myeloid cell line, M07e. The mechanisms of this phenomenon remain unknown. In an attempt to understand the cellular processes relevant to this phenomenon, we examined the effects of SLF and granulocyte-macrophage colony-stimulating factor (GM-CSF) on induced lipid metabolism in M07e cells. We find that both GM-CSF and SLF induced increased phosphatidylcholine (PC) turnover rates (biosynthesis and degradation) as measured by increased [3H]-choline labelling, with SLF being more potent than GM-CSF after 6 h of stimulation, but equipotent at 24 h of stimulation. The labelling of aqueous intermediates of PC metabolism was also increased by cytokine stimulation, most notably phosphocholine. Simultaneous stimulation with GM-CSF plus SLF resulted in a true synergistic induction of PC, lysoPC, and phosphocholine labelling. GM-CSF and SLF each induced asymmetric labelling of various phospholipid classes as measured by incorporation of different [3H]-fatty acids. [3H]-myristic acid labelling of phosphatidylserine was most prominently induced (approximately 12-fold). Cytosolic choline kinase activity was also upregulated more than twofold over control by SLF, which might contribute to the increased phosphocholine labelling. These effects may have relevance to the intracellular mechanisms of the synergistic proliferative stimulation of SLF plus GM-CSF on M07e cells.

The time course of myosin light-chain phosphorylation in blood-induced vasospasm

The phosphorylation of an M(r) 20,000 myosin light chain (MLC20) promotes the generation of contractile force through actin-myosin adenosine triphosphatase in most agonist-mediated vascular smooth muscle cell contraction. However, the role of calcium-mediated contractile processes in sustained arterial narrowing after subarachnoid hemorrhage remains unknown. In a femoral artery model of vasospasm, whole blood was applied to arteries in 54 rats for periods of 2 to 10 days; the contralateral artery treated with platelet-rich plasma served as matched control. During the early stage of vasospasm (Days 2-5), in the media of arteries exposed to blood, MLC20 phosphorylation (including diphosphorylated forms) increased significantly (30-38%; P < 0.05); total medial MLC20 during this interval was comparable to that in controls. After 5 days, however, total MLC20 decreased markedly (> 90%; P < 0.01) compared with controls; phosphorylated MLC20 was undetectable during this interval. MLC20-mediated contractile processes may be prominent in the early stages of arterial narrowing after subarachnoid hemorrhage; later stages are associated with the loss of MLC20 and the possible persistence of arterial narrowing by other mechanisms.

Radiation inhibition of intimal hyperplasia after arterial injury

To demonstrate the effect of gamma radiation on proliferating smooth muscle cells in vivo, a standardized bilateral carotid balloon catheter arterial injury was produced in 45 rats and doses from 0-20 Gy were delivered to the right carotid artery at 24 h after injury. At 20 days after injury, cross-sectional area of intima was determined from axial histological sections. Compared to contralateral, nonirradiated balloon-injured arteries, radiation produced a significant dose-dependent reduction in intimal cross-sectional area, with a 50% decrease at 5-7.5 Gy. To determine the effect of timing of irradiation on intimal hyperplasia, 30 rats with bilateral carotid injury received unilateral cervical irradiation at doses of 1, 5 or 10 Gy administered at either 1, 3 or 5 days after injury. The radiation dose (P = 0.0002), timing of irradiation (P = 0.003) and an interaction between timing and dose (P = 0.0278) were significantly associated with reduction in neointimal cross-sectional area. To determine the effects of radiation on intimal hyperplasia at later intervals, rats irradiated with 15 (n = 5) or 20 Gy (n = 5) were euthanized at 3 months after injury. A significant persistent reduction in intimal cross-sectional area for irradiated arteries at 3 months was associated with minimal apparent radiation effects upon adjacent tissue. These data suggest that external gamma irradiation at the single doses used effectively inhibits smooth muscle proliferation and intimal hyperplasia in the rat balloon catheter injury model in a time- and dose-dependent manner.

Rainbow holography with a synthesized double slit

Rainbow holography with a synthesized double slit is proposed. Diffuse three-dimensional objects are translated uniformly in the x(0)-y(0) plane. The propagation direction of the coherent plane wave illuminating the objects is situated in the x(0)-z(0) plane. As a result of this process, a sinc function that modulates the complex-amplitude distribution of the objects is presented on the back focal plane of the lens, and the synthesized slit is formed. The central position of the synthesized slit depends on both the direction of motion of the object and the spatial frequency of the illuminating wave in the x(0) direction. Therefore the synthesized double slit is generated with a two-exposure method that has two illuminating waves of different spatial frequencies. The theoretical analysis and some experimental results are presented.

Macrophage inflammatory protein-1 alpha enhances growth factor-stimulated phosphatidylcholine metabolism and increases cAMP levels in the human growth factor-dependent cell line M07e, events associated with growth suppression

The immunoregulatory C-C chemokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha) has suppressive activity on proliferation of stem cells and early subsets of myeloid progenitor cells. A receptor for C-C chemokines that binds MIP-1 alpha has been characterized, cloned, and shown to be related structurally to neuropeptide receptors that couple through G-proteins to phospholipase-C and adenyl cyclase. Yet, very little information on the intracellular mechanisms of action of MIP-1 alpha is available. We show here that the human factor-dependent cell line M07e is responsive to the cell cycle-suppressive effects of MIP-1 alpha, has specific membrane-binding sites for MIP-1 alpha, and that treatment of these cells with this chemokine increases the phosphatidylcholine (PC) and phosphocholine turnover rates in cells that are synergistically stimulated by the combination of granulocyte-macrophage colony-stimulating factor and steel factor but not these factors acting singly. Additional, MIP-1 alpha treatment induces a dose- and time-dependent increase in intracellular cAMP levels in M07e cells. Both exogenous PC and dibutyryl cAMP were found to suppress the proliferation of M07e colony-forming cells to a level similar to that of MIP-1 alpha, further implicating cAMP and PC metabolism in MIP-1 alpha-induced M07e suppression. RANTES, a related chemokine, with weak or incomplete binding to the cloned MIP-1 alpha receptor, did not suppress M07e colony-forming cells, nor did it increase intracellular cAMP levels, but it did enhance growth factor-induced PC turnover, further supporting the involvement of cAMP in MIP-1 alpha suppression while demonstrating that increased PC turnover alone is not sufficient for suppression. These findings support the idea that the human MIP-1 alpha receptor is coupled to phospholipid and cAMP metabolism in a manner similar to other 7-transmembrane, G-protein-linked receptors and suggest that a phosphatidylcholine hydrolytic cycle and an associated increase in cAMP are part of the mechanisms of action of MIP-1 alpha.

Macrophage inflammatory protein-1 alpha enhances growth factor-stimulated phosphatidylcholine metabolism and increases cAMP levels in the human growth factor-dependent cell line M07e, events associated with growth suppression

The immunoregulatory C-C chemokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha) has suppressive activity on proliferation of stem cells and early subsets of myeloid progenitor cells. A receptor for C-C chemokines that binds MIP-1 alpha has been characterized, cloned, and shown to be related structurally to neuropeptide receptors that couple through G-proteins to phospholipase-C and adenyl cyclase. Yet, very little information on the intracellular mechanisms of action of MIP-1 alpha is available. We show here that the human factor-dependent cell line M07e is responsive to the cell cycle-suppressive effects of MIP-1 alpha, has specific membrane-binding sites for MIP-1 alpha, and that treatment of these cells with this chemokine increases the phosphatidylcholine (PC) and phosphocholine turnover rates in cells that are synergistically stimulated by the combination of granulocyte-macrophage colony-stimulating factor and steel factor but not these factors acting singly. Additional, MIP-1 alpha treatment induces a dose- and time-dependent increase in intracellular cAMP levels in M07e cells. Both exogenous PC and dibutyryl cAMP were found to suppress the proliferation of M07e colony-forming cells to a level similar to that of MIP-1 alpha, further implicating cAMP and PC metabolism in MIP-1 alpha-induced M07e suppression. RANTES, a related chemokine, with weak or incomplete binding to the cloned MIP-1 alpha receptor, did not suppress M07e colony-forming cells, nor did it increase intracellular cAMP levels, but it did enhance growth factor-induced PC turnover, further supporting the involvement of cAMP in MIP-1 alpha suppression while demonstrating that increased PC turnover alone is not sufficient for suppression. These findings support the idea that the human MIP-1 alpha receptor is coupled to phospholipid and cAMP metabolism in a manner similar to other 7-transmembrane, G-protein-linked receptors and suggest that a phosphatidylcholine hydrolytic cycle and an associated increase in cAMP are part of the mechanisms of action of MIP-1 alpha.

[Antidepressant active constituents in the roots of Morinda officinalis How]

Five compounds having antidepressant activities have been isolated from the roots of Morinda officinalis, a Chinese traditional Yang-tonic drug. These compounds were identified as succinic acid (1), nystose (2), 1F-fructofuranosylnystose (3), inulin-type hexasaccharide (4) and heptasaccharide (5) by chemical and spectroscopic methods. All of the compounds are isolated from the species of genus Morinda for the first time.

Regulation of acetylcholinesterase mRNA stability by calcium during differentiation from myoblasts to myotubes

The expression of acetylcholinesterase (AChE), nicotinic acetylcholine receptors (nAChR), and their corresponding mRNAs increases dramatically during the conversion of myoblasts to myotubes in C2-C12 cells. The increase in expression of nAChR arises from transcriptional activation of the genes encoding the receptor subunits, whereas stabilization of labile transcripts is primarily responsible for enhanced AChE expression. In a search for the signaling pathways responsible for stabilization of the AChE mRNA, we found that ryanodine, synthetic ryanodine receptor antagonists and L-type, but not N-type, Ca2+ channel blockers inhibit the differentiation-induced expression of AChE mRNA, but not the nAChR mRNA. Selective inhibition of increased expression of AChE is also evident. Inhibition by ryanodine and nifedipine is additive suggesting different target sites for the two Ca2+ channel ligands. Ryanodine binding sites can be detected in both myoblasts and myotubes, but they increase substantially during differentiation. Rates of AChE gene transcription are not altered by ryanodine and nifedipine, indicating that decreased Ca2+ availability prevents stabilization of the mRNA normally seen with differentiation. Muscle cells still undergo elongation and fusion in the presence of ryanodine or L-type Ca2+ channel antagonists. Ryanodine block is fully reversible, indicating functional integrity of the cellular expression system after the drug treatment. These findings indicate that intracellular ryanodine-sensitive calcium channels and extracellular L-type Ca2+ channels link to play an important role in stabilizing AChE mRNA and suggest that transient increases in intracellular Ca2+ may be critical for the commitment of AChE expression during myogenesis.

Association of USF and c-Myc with a helix-loop-helix-consensus motif in the core promoter of the murine type II beta regulatory subunit gene of cyclic adenosine 3', 5'-monophosphate-dependent protein kinase

Previous studies showed that the core promoter of the mouse cAMP-dependent protein kinase regulatory subunit type II beta (RII beta) gene was composed of two functional elements. One element was GC rich and bound the Sp1 transcription factor. The second element contained a helix-loop-helix (HLH)-motif. Each element conferred transcriptional activity when inserted upstream of a reporter gene, chloramphenicol acetyltransferase and transfected into mouse NB2a neuroblastoma cells and Chinese hamster ovary (CHO) cells. The core promoter was further characterized by mutational analysis using electrophoretic mobility shift assays and by transfection into CHO and NB2a cells. Electrophoretic mobility shift assays showed that the HLH-consensus motif, CACGTG, present in the RII beta gene bound nuclear factors present in NB2a and CHO cells. Mutations in the HLH-core motif decreased the binding of these factors and reduced the transcriptional activity of constructs containing the chloramphenicol acetyltransferase reporter when transfected into these cells. The results showed that the central nucleotides as well as the adjacent bases were important for the interaction with the nuclear binding factors. UV cross-linking, Southwestern blot analysis, and interference of the mobility shift patterns by specific antisera directed against USF and c-Myc indicated that both of these transcription factors were forming complexes with the HLH-consensus motif. The results suggest that RII beta transcription may be regulated, in part, by USF and c-Myc in NB2a and CHO cells.

Expression and ligand specificity of acetylcholinesterase and the nicotinic receptor: a tale of two cholinergic sites

The functional design of the nAChR and AChE rather than their recognition capacities requires divergence in structure of the two binding sites. The receptor requires co-operativity to link ligand occupation to the response, rapid conformational transitions of activation, and slower transitions of desensitization. Hence, its binding sites have evolved at subunit interfaces. By contrast, AChE functions with a large kcat and a comparatively large Km. To do so, it must force acetylcholine through a low-energy transition site that features tetrahedral rather than the ground-state, trigonal conformation around the carbonyl carbon. This requires a high affinity (KD approximately 10(-17) M) for the enzyme complex of the transient transition state. Interestingly, the three-finger peptide toxins (alpha-bungarotoxin and fasciculin), though closely homologous, use different interaction sites on the receptor (the agonist recognition site) and AChE (a peripheral site). Finally, although the two proteins show co-ordinated expression during muscle differentiation, the receptor relies primarily on transcriptional control while AChE expression is post-transcriptional, being controlled by mRNA stability.

A peptide C-terminal to the second Zn finger of human vitamin D receptor is able to specify nuclear localization

A peptide of 27 amino acids, VDR(102-76), representing residues 76-102 immediately C-terminal to the second Zn finger of human vitamin D receptor (hVDR) was conjugated to fluorescein-labelled IgG using a bifunctional coupling reagent, m-maleimidobenzoyl n-hydroxysuccinimide. Upon microinjection into the cytoplasm of human osteosarcoma MG-63 cells, the chimeras accumulated in the nuclei. This transport was arrested by chilling or energy depletion. Two other peptides, VDR(80-67), spanning the N-terminal part of VDR(102-76), and VDR(108-97), spanning the C-terminal part of VDR(102-76), were not able to target the linked proteins to the nuclei. SV40(135-112), a peptide containing a well-characterized nuclear localization sequence (amino acids 112-135) of simian virus 40 (SV40) large T-antigen, caused complete nuclear accumulation under the same conditions. Wheat germ agglutinin, which inhibits SV40(135-112) transport, also inhibited the nuclear accumulation of VDR(102-76) as did energy depletion.

[Therapeutic effectiveness of zuzhongping on patients with arteriosclerostic cerebral infarction]

Forty-six patients with acute arteriosclerostic cerebral infarction were randomly divided into two groups: control group and treatment group. Each of them included 23 patients respectively. The patients in the control group were given Dextran-40 but the ones in the treatment group were given the mixture of Zuzhongping. The course of treatment was 3 weeks. It was found that there was a significant difference (P < 0.01) in the score percentage, before and after treatment of neurological defects, between the control group and the treatment group, and the former (29.70 +/- 33.52) was much lower than the latter (45.40 +/- 27.60). The total curative rate of the treatment group (87.0%, 20/23) was significantly higher than that of the control group (60.9%, 14/23). There was an obviously prolonged KPTT (kaolin partial thromboplastin time) value and a decreased Fb (fibrinogen) level in the treatment group. Before treatment they were 32.43 +/- 4.03 sec and 6.18 +/- 1.77 g/L respectively, but after treatment, 52.96 +/- 10.50 sec and 4.5 +/- 0.95 g/L respectively. The authors suggest that the significant therapeutic efficacy of Zuzhongping in the patients with acute arteriosclerostic cerebral infarction is related to its action of anticoagulation, modification of PGI2 and TXA2 level in the body, decreased blood Fb level, hyperglycemia, etc.

Structural determinants of cytochrome P450 2B1 specificity: evidence for five substrate recognition sites

Twelve site-directed mutants of rat cytochrome P450 2B1 distributed over seven positions and four putative substrate recognition sites (SRS) were constructed and expressed in COS cells. Function was examined using androstenedione and testosterone as substrates. Substitutions at positions 303, 360, and 473 did not markedly affect the regio- or stereoselectivity of androgen metabolism, whereas mutants in positions 206 (SRS-2), 302 (SRS-4), and 363 and 367 (SRS-5) exhibited markedly different steroid metabolite profiles compared with parental P450 2B1. In particular, the Phe-206-->Leu substitution conferred androgen 6 alpha- and testosterone 7 alpha-hydroxylase activities, and the Thr-302-->Ser substitution suppressed androgen 16 beta-hydroxylation in favor of androstenedione 16 alpha- and testosterone 15 alpha-hydroxylation. Replacement of Val-363 or Val-367 with Ala conferred androgen 15 alpha-hydroxylase and 6 beta-hydroxylase activities, respectively, and suppressed susceptibility to mechanism-based inactivation by the P450 2B1-selective chloramphenicol analog N-(2-p-nitrophenethyl)chlorofluoroacetamide. The Val-367-->Ala mutant was also resistant to chloramphenicol itself. The Leu mutant at position 363 exhibited increased specificity for androstenedione and testosterone 16 beta-hydroxylation, whereas the Leu mutant at position 367 exhibited decreased stereospecificity. Most interestingly, the size of key residues identified plays a critical role in governing steroid hydroxylation from the alpha-face or beta-face and hydroxylation on the D-ring or the B-ring.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of zuzhongping on ischemic volume in the rat model of middle cerebral artery occlusion]

Using the middle cerebral artery occlusion model, we studied the effects of Zuzhongping on experimental focal cerebral ischemia. Twenty-eight adult male Wistar rats were randomly divided into three groups: (1) Zuzhongping group (n = 9), (2) Saline control group (n = 10), and (3) Blank control group (n = 9). Group 1 and group 2 received via a gastric tube 1 1ml/kg/day of Zuzhongping and normal saline, respectively. The cerebral middle arteries on the right side of 28 rats were occluded with a bipolar electro-coagulater at sites 1-2 mm from the right olfactory nerve tract. Ischemic volumes were measured by an image analytic system when the cerebral ischemia had lasted 24 h. The results showed that the ischemic volume of Zuzhongping group was significantly smaller than that of group 2 and group 3, suggesting a protective effect of Zuzhongping.

Role of residues 363 and 206 in conversion of cytochrome P450 2B1 from a steroid 16-hydroxylase to a 15 alpha-hydroxylase

Four double and four triple site-directed mutants of cytochrome P450 2B1 were constructed, expressed in COS cells, and assayed for androstenedione and testosterone hydroxylation. The mutants combined a Val-363-->Ala substitution with an Ile-114-->Val or Ala substitution and/or a Gly-478-->Ala or Ser substitution. Each of the individual mutations enhances androgen 15 alpha-hydroxylation, and the appropriate combination of Val or Ala at position 114 with Ala or Ser at position 478 has recently been shown to convert P450 2B1 from an androstenedione and testosterone 16 beta-hydroxylase to a 15 alpha-hydroxylase (Halpert, J. R., and He, Y.-A. (1993) J. Biol. Chem. 268, 4453-4457). All eight mutants containing the Val-363-->Ala substitution preferentially hydroxylated androstenedione and testosterone in the 15 alpha-position and thus functionally resemble mouse P450 2A4. However, unlike P450 2A4, various single and multiple 2B1 mutants at positions 114, 363, and 478 mainly hydroxylated progesterone in the 16 alpha- rather than 15 alpha-position. By combining the Ile-114-->Ala substitution with a Phe-206-->Leu mutation (corresponding to Ala-117 and Leu-209 in P450 2A4), P450 2B1 was converted to a progesterone 15 alpha-hydroxylase with retention of testosterone 15 alpha-hydroxylase activity. These studies document the importance of residues 363 and 206 in determining the substrate specificity of P450 2B1 and strongly support the hypothesis that the judicious combination of a small number of discrete mutations can be used to confer new specificities on P450 enzymes.

Steel factor and granulocyte-macrophage colony stimulating factor act together to enhance choline-lipid turnover during synergistically stimulated proliferation of the human factor dependent cell line, M07E

The hematopoietic growth factors granulocyte-macrophage colony stimulating factor and steel factor have been shown to synergize in the stimulation of proliferation of the human factor-dependent cell line M07e. We investigated the possible involvement of lpid-mediated signaling in granulocyte-macrophage colony stimulating factor and steel factor induced proliferative synergism. It was found that treatment of M07e cells with these factors alone stimulates choline lipid metabolism and that they cooperate to further enhance this effect. Therefore a choline lipid signal transduction pathway may operate as part of the series of events leading to synergistic growth induced by the combination of granulocyte-macrophage colony stimulating factor and steel factor.

Enhanced secretion of endothelin by endothelial cells in response to hemoglobin

Confluent cultures of bovine aortic endothelium in serum-free medium were exposed to increasing concentrations (10(-6)-10(-4) M) of freshly prepared erythrocyte lysates (primarily hemoglobin). Hemoglobin increased endothelin-1 secretion into the medium in a dose-dependent manner after 24 hours. The enhanced secretion of endothelin-1 in response to hemoglobin was sustained for 72 hours, suggesting active production and secretion of endothelin-1 rather than release from intracellular pools. Secreted endothelin-1 in the medium was characterized by high-performance liquid chromatography coupled with radioimmunoassay. Endothelin-1, a potent and long-lasting vasoconstrictor, may be one of the causative factors of cerebral vasospasm after subarachnoid hemorrhage. Oxyhemoglobin, derived from periarterial clot, may play an important role in the secretion of endothelin-1 in cerebral vasospasm.

Basic fibroblast growth factor and transforming growth factor beta-1: synergistic mediators of angiogenesis in vitro

We investigated the relative roles of basic fibroblast growth factor (bFGF) and transforming growth factor beta-1 (TGF-b) on bovine aortic endothelial cell mitogenesis and morphogenesis using two-dimensional Petri dish cultures and a three-dimensional hydrated collagen gel. bFGF alone stimulated endothelial cell proliferation with an EC50 of 0.5 ng/ml. At bFGF levels greater than 2.5 ng/ml, morphologic alterations in confluent monolayers predominated; cells changed from a cobblestone morphology to an elongated cell pattern and showed enhanced migration into a denuded area of a Petri dish. In the three-dimensional model, exposure of endothelial cell monolayers to high bFGF levels stimulated minor cell migration directly under the monolayer but no invasion into the gel matrix. In combination with bFGF, heparin potentiated morphogenic changes, but not mitogenesis. bFGF modification of the antiproliferative effect of TGF-b in confluent cultures was evidenced by induction of endothelial cell sprouting in response to 0.5 ng/ml TGF-b and 10-20 ng/ml bFGF in two-dimensional cultures. On collagen gels, endothelial cells migrated into the deep layers of the gel in a dose-dependent manner: invasion was maximal at 0.3-0.7 ng/ml TGF-b with decreased invasion at higher concentrations. The optimal collagen concentration that supported cell invasion was 0.075% collagen with the number of invading cells decreasing with increasing collagen gel density. By scanning electron microscopy, invading endothelial cells assumed a fibroblast-like appearance with slender cell extensions. We concluded that bFGF and TGF-b had independent effects on endothelial cell morphology and mitogenesis in culture. In combination at specific doses, these agents stimulated sprouting in the two-dimensional model and cell invasion in a collagen gel model. Morphogenic changes may be the primary event in determining angiogenesis.

Filament overlap affects TnC extraction from skinned muscle fibres

Recent studies on calcium regulation of muscle contraction selectively extract troponin C (TnC) from skinned skeletal muscle fibres with a low ionic strength rigor solution containing a Ca2+/Mg2+ chelator. As previous results from this laboratory and others demonstrate a crossbridge effect, especially rigor, on many of the properties of TnC, the effects of filament overlap on TnC extraction from skinned rabbit psoas muscle fibres were investigated. Tension-pCa relationships at a sarcomere length of 2.7 microns were determined before and after a 5 min TnC extraction at sarcomere lengths of 2.3, 2.5, 2.7, 3.1, 3.3 or 3.5 microns with 20 mM Tris, pH 7.8, 5 mM EDTA. The decrease in the post-extraction maximum Ca2+ activated tension, an indicator of the amount of TnC extracted, was linearly related to the overlap of the thick and thin filaments with decreases in tension being associated with a decrease in filament overlap. The smaller fibre diameter at the longer sarcomere length could facilitate diffusion of TnC from fibre segments. However, the wide range of measured diameters, 40-120 microns, accounted for only 14% of the observed tension decrement and shrinking the fibre with polyvinylpyrrolidone did not increase the tension decrement. Increasing the sarcomere length before extraction was also found to decrease the TnC content of fibre segments along with the post-extraction maximum tension. Thus, TnC appears to be preferentially extracted from non-overlap than overlap regions of the sarcomere. These results further indicate that rigor crossbridges affect TnC other than through increased Ca2+ binding and that under the conditions used here, they retard its extraction.

Phosphorylation of the regulatory subunit of type II beta cAMP-dependent protein kinase by cyclin B/p34cdc2 kinase impairs its binding to microtubule-associated protein 2

Subcellular localization of type II cAMP-dependent protein kinase is determined by the interactions of the regulatory subunit (RII) with specific RII-anchoring proteins. By using truncated NH2-terminal RII beta fusion proteins expressed in Escherichia coli and the mitotic protein kinase p34cdc2 isolated from HeLa cells or starfish oocytes, we investigated the in vitro phosphorylation of RII beta by these kinases. The putative site for phosphorylation by the mitotic kinases is Thr-69 in the NH2-terminal domain of RII beta. This phosphorylation site matches the consensus sequence X(T/S)PX(K/R) for p34cdc2 recognition and belongs to a well-conserved sequence found in all RII beta sequences known to date. In contrast to phosphorylation by casein kinase II or the cAMP-dependent protein kinase catalytic subunit, phosphorylation of RII beta by mitotic kinases impaired its interaction with a well-known RII-anchoring protein, the neuronal microtubule-associated protein 2. The potential regulatory significance of the phosphorylation of this site on the interaction with microtubule-associated protein 2 and other RII-anchoring proteins and the physiological relevance of this cyclin B/p34cdc2 kinase-catalyzed modification of RII beta (or phosphorylation by other proline-directed protein kinases) are discussed.

[Memory function of patients with cerebral arteriosclerosis evaluated by Rivermead behavioural memory test]

Using Rivermead behavioural memory test, we examined 142 patients with cerebral arteriosclerosis. The results showed that the rate of anomalies of screening score in patients with cerebral arteriosclerosis were significantly higher than that of the control group (P < 0.01). The patients and control scores were significantly different (P < 0.05) in all items except the picture and face recognition. Comparing the screening score with brain CT scan, we found a relationship between brain damage and behavioural memory declination. Also, many persons of control group got low scores with behavioural memory test, suggesting that the Rivermead behavioural memory test be sensitive to memory declination. With its simplicity and sensitivity the Rivermead behavioural memory test may have some practical value in China.

Sequestration and secretion of insulin-like growth factor-I by bovine aortic endothelial cells

Endothelial cells elaborate growth promoting activities in culture medium that support limited smooth muscle cell and fibroblast growth in vitro in the absence of serum. We investigated whether insulin-like growth factor-I (IGF-I) was synthesized and secreted by bovine aortic endothelial cells in vitro. Subconfluent endothelial cell cultures in serum-free medium secreted severalfold higher IGF-I levels than confluent cultures by acid-sizing chromatography and IGF-I radioimmunoassay. The IGF-I secretory level was not sustained during a second serum-free incubation. In contrast, secretion of IGF binding proteins persisted and was maintained at constant levels throughout the same observation periods. Analysis of poly(A+)RNA by northern blots revealed hybridization of an IGF-I cDNA to a 7.5- to 7.0-kb transcript and superinduction of the 7.5-7.0-kb mRNA by the translational inhibitor, cyclohexamide. However, no endogenously labeled IGF-I was detected in conditioned media after incubation of cultures with [35S]cysteine or [3H]leucine. When cultures were incubated in the presence of serum supplemented with IGF-I, subconfluent cultures sequestered and released more IGF-I than confluent cultures. We concluded that the majority of IGF-I secreted in vitro was sequestered from serum.