Regulation of PDGF-B in endothelial cells exposed to cyclic strain

The present study was designed to examine the regulation by cyclic strain of endothelial cell (EC) platelet-derived growth factor-B chain (PDGF-B) expression. We demonstrate in this study that bovine aortic ECs subjected to 10% (but not 6%) average strain resulted in a 2.6-fold increase in PDGF-B steady state mRNA and immunoreactive protein. Nuclear runoff transcription assays confirmed the induction of PDGF-B transcripts. To address the regulation of PDGF-B gene expression by cyclic strain, we transfected bovine aortic ECs with a construct containing 450 bp of human PDGF-B promoter sequence coupled to chloramphenicol acetyltransferase (CAT), and found that subjecting these cells to 10% average strain resulted in a twofold increase in CAT activity by 4 hours. Analysis of nested 5' deletions of the promoter transfected into ECs demonstrated a 55% drop-off in activity between position -313 and -153, with no induction of activity with the - 101-bp minimal promoter. Since a shear stress response element (SSRE) is located at position -125, we tested the hypothesis that the SSRE site was necessary and/or sufficient for induction of PDGF-B activity with strain. Electromobility shift assays revealed that nuclear proteins from ECs exposed to strain for short intervals (30 minutes) bound to the PDGF-B SSRE. However, transfection of ECs with hybrid promoter constructs containing the SV40 sequence promoter downstream of the SSRE or the -153 PDGF-B promoter sequence bearing a mutation in the SSRE demonstrated that the SSRE was not necessary for inducible reporter gene expression in ECs exposed to cyclic strain.

[Serological survey of human T lymphotropic virus type I (HTLV-1) IgG antibody in south region of Xinjiang]

Human T lymphotropic virus type-1 (HTLV-1) is endemic in southwestern Japan, Seychelles Islands, Caribbean basin, Brazil, and Sub Saharan Africa. Recently, the prevalence of HTLV-1 of domestic source has been reported from Beijing, Fujian and so forth. The object of our study is to know whether the prevalence of HTLV-1 is present in Xinjiang. We collected 2642 serm samples of various ages and different nationalities (Uigur, Han and Khalkhas) from south region of Xinjiang and tested for determination of HTLV-1 IgG antibody by IFA. The results showed that the total positive rate of HTLV-1 IgG was 0.34% (9/2642), of which Uigur nationality was 0.74% (8/1082), Khalkhas nationality was 0.21 (1/471), Han nationality was zero (0/1089). This data indicated that there are HTLV-1 infection among the population of Xinjiang and especially in Uigur and Khalkhas. Why did the minority nationalities have relatively high frequency of HTLV-1 infection? This needs to be studied further.

Regulation of tPA in endothelial cells exposed to cyclic strain: role of CRE, AP-2, and SSRE binding sites

We have previously reported that exposure of cultured bovine aortic endothelial cells (EC) to 10% average strain resulted in an increase in tissue plasminogen activator (tPA) mRNA, immunoreactive tPA protein, and tPA activity in the medium. The present study was designed to examine the regulation of tPA gene expression in EC by cyclic strain. We performed a functional analysis of the tPA promoter by transfecting bovine aortic EC with a 1.4-kilobase (kb) construct of the human tPA promoter coupled to chloramphenicol acetyltransferase. We found that subjecting the EC to 10% average strain (and not 6% average strain) resulted in a 2.6-fold increase in activity of the 1.4-kb tPA promoter by 4 h. Analysis of deletion mutants of the promoter transfected into EC demonstrated a 60% drop-off in activity between position -145 and -105. Deoxyribonuclease I protection analysis of the segment downstream of position -196 suggested involvement of activator protein-2 (AP-2) and adenosine 3',5'-cyclic monophosphate-responsive element (CRE)-like binding sites, which was confirmed by electrophoretic mobility shift assays. Site-directed mutants of either the AP-2 or CRE-like regions resulted in a 65% decrease in activity compared with the wild type. Double mutations abolished basal transcription and any strain-induced activity. A shear stress responsive element (SSRE) binding site is present at -945, but site-directed mutants did not show any drop in activity compared with wild type by cyclic strain. These studies demonstrate that cyclic strain regulates tPA gene transcription in bovine aortic EC and that this transcriptional activation is dependent on factors that are similar to those activated with phorbol ester.

Harmaline competitively inhibits [3H]MK-801 binding to the NMDA receptor in rabbit brain

Harmaline, a beta-carboline derivative, is known to produce tremor through a direct activation of cells in the inferior olive. However, the receptor(s) through which harmaline acts remains unknown. It was recently reported that the tremorogenic actions of harmaline could be blocked by the noncompetitive NMDA channel blocker, MK-801. This study examined whether the blockade of harmaline's action, in the rabbit, by MK-801 was due to a pharmacological antagonism at the MK-801 binding site. This was accomplished by measurement of [3H]MK-801 binding in membrane fractions derived from tissue containing the inferior olivary nucleus and from cerebral cortex. Harmaline completely displaced saturable [3H]MK-801 binding in both the inferior olive and cortex with apparent IC50 values of 60 and 170 microM, respectively. These IC50 values are consistent with the high doses of harmaline required to produce tremor, e.g., 10-30 mg/kg. Non-linear curve fitting analysis of [3H]MK-801 saturation experiments indicated that [3H]MK-801 bound to a single site and that harmaline's displacement of [3H]MK-801 binding to the NMDA receptor was competitive as indicated by a shift in Kd but not in Bmax. In addition, a Schild plot gave a slope that was not significantly different from 1 indicating that harmaline was producing a displacement of [3H]MK-801 from its binding site within the NMDA cation channel and not through an action at the glutamate or other allosteric sites on the NMDA receptor. These findings provide in vitro evidence that the competitive blockade of harmaline-induced tremor by MK-801 occurs within the calcium channel coupled to the NMDA receptor. Our hypothesis is that harmaline produces tremor by acting as an inverse agonist at the MK-801 binding site and thus opening the cation channel.

Transplantation in patients with multiple myeloma: a multicenter comparative analysis of peripheral blood stem cell and allogeneic transplant

We performed a multicenter comparative analysis of autologous peripheral blood stem cell transplantation (PBSCT) and allogeneic bone marrow transplantation (alloBMT) in multiple myeloma. Forty-eight consecutive patients received either PBSCT (24 patients) or alloBMT (24 patients) at one of three institutions in the study group. Preparatory regimens consisted of melphalan and total body irradiation (TBI) or melphalan alone in the PBSCT group. The alloBMT group received one of four regimens: cyclophosphamide and TBI; cyclophosphamide, VP-16 and 1,3-bis(2-chloroethyl)-1-nitrosourea (CVB); busulfan and cyclophosphamide (BU/CY) and total marrow irradiation (TMI); or melphalan and TBI. Procedure-related mortality was 12.5% for the PBSCT group and 25% for the alloBMT group. With a median follow-up for survivors in the PBSCT and alloBMT groups of 11 months (range, 4-46) and 15 months (range, 2-84 months), respectively, there was no significant difference in median overall survival (33.5 versus 38.6 months, p = 0.7637) or event-free survival (16.7 versus 31 months, p = 0.8450). There was, however, a plateau in survival at 40% in the alloBMT group. No plateau in survival was seen in the PBSCT group. Clinical relapses occurred as late as 39 months posttransplant. Patients have survived up to 28 months postrelapse.

[Research on effects of taurine on the transplanted tumor of mice]

With the same forage to the mice, three experiments were done. The control group took water and experimental group took 1% taurine. 1. After the mice were vaccinated with S180 sarcoma, every group was further divided into two groups, one treated with cytoxan (CTX), another one treated with nothing. The survival period, weight of the tumor and the tumor inhibition rate were investigated. The result shows: The survival period of the group fed with taurine was (35.75 +/- 23.7) days longer than that of the control group (18.7 +/- 5.6) days, and the tumor inhibition rate was 42.26%. The mice fed with taurine and treated with CTX survived to 61 days with no death, and no tumor could be seen grossly, so the tumor inhibition rate is 100%. The survival period and weight of the tumor were not different between the CTX treated and control groups. 2. Tumor cell membrane fluidity was observed after the mice were vaccinated with Erlish ascitic tumor. The result shows: in the taurine group, the fluorescence polarization (p) is 0.108 +/- 0.020, the viscosity (eta) is 0.618 +/- 0.140 and in the control group p is 0.139 +/- 0.20, eta is 0.874 +/- 0.150, respectively. Thus the cell membrane fluidity of the taurine group is also obviously better than that of the control group (P < 0.01). 3. The immune functions of the two groups were determined by carbon clearance test and capacity of serum hemolysin. The immune function of the taurine group is also obviously higher than that of control group (P < 0.01). All the results described above show:taurine is functioning for tumor inhibition, and has obvious synergic effect while treated with CTX as chemotherophy. It is considered that the tumor inhibit function of taurine may be related to its effects of immune enhancing and membrane profecting.

The clinical significance of p21(WAF1/CIP-1) and p53 expression in pancreatic adenocarcinoma

BACKGROUND

Wild-type p53 protein activates the WAF1/CIP-1 (p21) gene, leading to G1 arrest after DNA damage. The authors investigated the relation of p21 and p53 expression in pancreatic adenocarcinomas to disease stage, overall patient survival, and survival when chemotherapy or radiation therapy was given.

METHODS

Paraffin embedded tissue sections of 75 ductal adenocarcinomas of the pancreas were immunostained for p53 and p21. Nuclear expression was scored as absent, focal (<10%), moderate (10-50%), or strong or diffuse (>50%).

RESULTS

The median survival of patients whose pancreatic tumors expressed the p21 protein (43 of 75 cases, 57%) was better than that for patients whose tumors were p21 negative (32 of 75 cases, 43%) (median survival, 13.5 vs. 9.8 months, respectively; P = 0.23). No difference in survival was found with regard to p53 protein expression (43 of 75 cases, 57%); however, strong p53 expression was significantly associated with advanced disease stage (70% in Stage IV vs. 13-28% in lower stages). Expression of p21 correlated with earlier clinical stage. Stage specific comparisons showed a trend toward increased survival among p21 positive tumor patients diagnosed at clinical Stages I and III but not among those diagnosed at Stage IV. Adjuvant chemotherapy or radiation improved survival significantly if tumors expressed p21 or no p53.

CONCLUSIONS

Expression of p21 is significantly associated with earlier clinical stage in pancreatic adenocarcinoma, perhaps accounting for the better survival observed in this patient group than among those whose tumors were p21 negative. Improved survival with either chemotherapy or radiation therapy was observed for patients whose tumors were p21 positive or p53 negative.

The clinical significance of p21(WAF1/CIP-1) and p53 expression in pancreatic adenocarcinoma

BACKGROUND

Wild-type p53 protein activates the WAF1/CIP-1 (p21) gene, leading to G1 arrest after DNA damage. The authors investigated the relation of p21 and p53 expression in pancreatic adenocarcinomas to disease stage, overall patient survival, and survival when chemotherapy or radiation therapy was given.

METHODS

Paraffin embedded tissue sections of 75 ductal adenocarcinomas of the pancreas were immunostained for p53 and p21. Nuclear expression was scored as absent, focal (<10%), moderate (10-50%), or strong or diffuse (>50%).

RESULTS

The median survival of patients whose pancreatic tumors expressed the p21 protein (43 of 75 cases, 57%) was better than that for patients whose tumors were p21 negative (32 of 75 cases, 43%) (median survival, 13.5 vs. 9.8 months, respectively; P = 0.23). No difference in survival was found with regard to p53 protein expression (43 of 75 cases, 57%); however, strong p53 expression was significantly associated with advanced disease stage (70% in Stage IV vs. 13-28% in lower stages). Expression of p21 correlated with earlier clinical stage. Stage specific comparisons showed a trend toward increased survival among p21 positive tumor patients diagnosed at clinical Stages I and III but not among those diagnosed at Stage IV. Adjuvant chemotherapy or radiation improved survival significantly if tumors expressed p21 or no p53.

CONCLUSIONS

Expression of p21 is significantly associated with earlier clinical stage in pancreatic adenocarcinoma, perhaps accounting for the better survival observed in this patient group than among those whose tumors were p21 negative. Improved survival with either chemotherapy or radiation therapy was observed for patients whose tumors were p21 positive or p53 negative.

[Synthesis and degradation of type IV collagen in rat experimental liver fibrosis]

OBJECTIVE

To investigate the synthesis and degradation of type IV collagen in CCl4-induced SD rat liver fibrosis.

METHODS

Dynamic changes and relationships among the tissue alpha 1 (IV) procollagen mRNA, type IV collagen (Col IV) and serum 7S polypeptide fragment of Col IV in fibrotic livers induced by CCl4 with choline difficiency diet were studied using immunohistochemistry, Northern analysis, in situ hybridization and serum RIA techniques.

RESULTS

The transcription of alpha 1 (IV) procollagen mRNA in fibrotic liver and the content of serum 7S polypeptide fragment derived from tissue Col IV degradation was enhanced promptly and obviously in earlier stage of experiment, but not synchronous afterwards. In the early stage of experiment, alpha 1 (IV) procollagen mRNA transcripts was localized in sinusoid Ito cells and endothelial cells. In the mid and late stage, alpha 1 (IV) procollagen mRNA transcripts was localized in myofibroblasts (MFs), fibroblasts (Fbs) and endothelia of small blood vessels in fibrotic septa.

CONCLUSIONS

The change of serum 7S polypeptide fragment could reflect the motabolic state of Col IV and the degree of tissue injury in fibrogenesis and might have some clinical significance in identifying the activiation of the liver fibrosis. The "Ito cell-myofibroblast-fibroblast" effective cell system and sinusoid endothelia were the Col IV producing cells during fibrogenesis, in which sinusoid endothelia, as another source of Col IV production, participated in the capillization of liver sinusoids.

Prenylation of RhoB is required for its cell transforming function but not its ability to activate serum response element-dependent transcription

Rho regulates cytoskeletal actin structure and integrin-mediated cell adhesion. Rho also has a role in cell growth regulation and is required for cell transformation by oncogenic Ras. Recently, it has been demonstrated that Rho can activate transcription from the c-fos serum response element (SRE). This raised the possibility that functions required for Rho-mediated cell transformation might overlap with those involved in transcriptional regulation. Here we show that RhoB can activate the SRE and can synergize in cell transformation with constitutively activated Raf-CAAX. Significantly, unprenylated forms of RhoB that are biologically inert and unable to transform cells can still activate SRE-dependent transcription. This finding suggests that transcriptional activation by Rho may be separable from its cell transforming functions.

Relationship of family cancer history to the expression of p53, p21WAF-1, HER-2/neu, and K-ras mutation in pancreatic adenocarcinoma

CONCLUSION

In our series of 81 cases, a history of family cancer was present in 52% of patients (42/81) with pancreatic cancer. Nine percent (7/81)had a family history of pancreatic cancer. Our studies suggest a possible relationship of family cancer history to the expression of p53 and p21WAF in pancreatic tumors, but show no relationship to the expression of HER-2/neu or to the prevalence of K-ras mutations. A lower incidence of p53 expression observed in patients with a family history of cancer suggests normal p53 protein is present in a majority of patients who develop pancreatic tumors related to other--as yet unidentified-inherited or familial risk factors. There was no significant difference in survival of pancreas cancer patients with and without a family history of cancer. However, survival in pancreas cancer patients may be influenced (improved) by p21WAF-1 expression.

BACKGROUND

Pancreas cancer is the fifth leading cause of cancer deaths (27,800 deaths/yr) in the United States. Various risk factors, including cigarette smoking, high-fat diet, DDT exposure, chronic pancreatitis, and diabetes mellitus, have been associated with pancreatic carcinoma. A few studies have suggested a genetic predisposition or increased risk for pancreatic cancer within families, but the exact etiology is largely unknown. In a series of 81 patients with pancreatic carcinoma, we analyzed the status of K-ras gene mutations and the expression of P21WAF-1, p53, and HER-2/neu protein to identify possible molecular associations in pancreas cancer cases of these molecular markers to family histories of cancer and pancreas cancer.

METHODS

Paraffin-embedded tissue sections from 81 cases of pancreatic adenocarcinoma were used for DNA extraction and immunohistochemical staining. K-ras mutation was studied by single-stranded conformation polymorphism (SSCP) and slot-blot allele-specific oligonucleotide (ASO) hybridization of PCR-amplified DNA product. Overexpression (aberrant expression) of p53, p21WAF-1, and HER-2/neu was documented by scoring nuclear localized p53, p21WAF-1 protein and cell membrane expression of HER-2/neu after immunostaining with gene product-specific monoclonal antibodies (MAbs).

RESULTS

Forty-two (42) of 81 patients studied in this series had a history of cancer in their families (52%). Seven of those 42 had a history of pancreatic carcinoma (17% or 9% of total cases). The incidence of K-ras mutation and the expression of p21WAF-1 and HER-2/neu in patient groups with and without a family history of cancer was not statistically different (83 vs 74%, p = 0.416; 57 vs 41%, p = 0.184; and 83 vs 81%, p = 1.000, respectively). However, the incidence of p53 expression was significantly lower in patients with a family history of cancer (40 vs 72%, p = 0.007). There was no statistical difference in survival of patients with a family history of cancer in relation to either K-ras mutation, p53 expression, p21, or HER-2/neu expression. However, patients lacking a family history of cancer showed improved survival trends in relation to p21 expression (median survival of 16 vs 8 mo, p = 0.029).

[Effect of processing on reducing the toxicity in sulfur]

The content of arsenic in sulfur before and after processing was determined. The result shows that the content in raw materials is 8-15 times higher than that of the processed product, which implies that the toxicity of sulfur is obviously reduced by processing.

Prevalence and clinical significance of combined K-ras mutation and p53 aberration in pancreatic adenocarcinoma

CONCLUSION

This study could not attribute survival differences to the coincident acquisition of two common genetic alterations, K-ras mutation and p53 overexpression in pancreatic adenocarcinoma patients. Additionally, our data indicate the converse to be true: Those patients lacking both K-ras mutation and aberrant p53 expression showed the shortest survival when compared with cases showing either alteration or both. This study also showed the negative effect of K-ras mutation and p53 expression on pancreas cancer patients' survival after treatment with either radiation therapy or chemotherapy.

BACKGROUND

Mutations of the oncogene K-ras at codon 12 are reported to be the most common genetic alteration in pancreatic carcinoma, whereas either overexpression or mutation of the tumor suppressor p53 gene is considered the most common genetic alteration in neoplasia of all types. p53 overexpression has been attributed to survival differences in pancreatic carcinoma, but such association is still controversial. No studies have fully documented the combined incidence of K-ras and p53 alterations in pancreatic adenocarcinoma, or their combined effect on patient survival in a large case series. The influence of radiation or chemotherapy in groups showing both, either, or neither mutation is also undocumented.

METHODS

Paraffin-embedded tissue sections from 76 cases of pancreatic adenocarcinoma were cut for DNA extraction for K-ras analysis and immunohistochemical staining for aberrant p53 expression. K-ras mutation was determined by single-strand conformation polymorphism (SSCP) and slot-blot allele-specific oligonucleotide (ASO) hybridization of PCR-amplified DNA product p53 expression was scored on the basis of percent nuclear staining with the MAb DO7.

RESULTS

Sixty-four of 76 cases (84%) showed K-ras mutation, p53 expression, or both, K-ras was mutated in 55 of 76 cases (72%). p53 was expressed in 33 of 76 cases (43%). Twenty-four of 76 cases (31%) showed both K-ras mutation and p53 expression. The presence of both alterations was not related to significant differences in tumor grade, stage, or survival compared to either alteration alone. A sizable subset (16% of cases) lacked either alteration, and surprisingly, this group showed the shortest median survival compared to those with K-ras mutation, p53 expression, or both (p = 0.024). Patients whose tumors were K-ras-negative showed the greatest difference in median survival with radiation therapy (median survival 30.8 mo vs 7.8 mo with no radiation, p = 0.005).

HER-2/neu expression in pancreatic adenocarcinoma: relation to tumor differentiation and survival

HER-2/neu expression in pancreatic adenocarcinoma has been inconsistently reported and has not been fully evaluated with respect to histologic grade and tumor grade heterogeneity. We studied HER-2/neu expression in a series of 79 primary pancreatic carcinomas using immunohistochemical methods, with expression scored for each histologic grade represented in each tumor. We found significantly lower expression of HER-2/neu in poorly differentiated (PD) portions of tumors-those areas lacking glandular differentiation-compared to well-differentiated (WD) and moderately differentiated (MD) portions of tumors. Forty-two of 68 (62%) invasive tumors with WD or MD glands showed moderate or strong expression of HER-2/neu in WD/MD areas; only 6 of 32 (19%) invasive tumors with PD areas showed similar expression in PD. In mutually exclusive patient sets, we also found a statistically different prevalence of HER-2/neu expression in patients with PD (6/32 cases; 19%) and without PD (29/47 cases; 62%) tumors (p < 0.001). Twenty-three cases had directly comparable areas of PD versus MD or WD. In 19 of 23 cases HER-2/neu expression was graded comparatively lower (or negative) in areas of PD than in MD or WD. Overall 46 of 79 cases (58%) showed moderate to strong HER-2/neu expression inclusive of all histologic grades, and 63 of 79 (80%) cases were HER-2/neu positive, if including weak or focal staining. There was no significant difference in the survival of patients with HER-2/neu-positive versus-negative tumors or in patients with versus without PD tumors. We have confirmed that although HER-2/neu gene expression is common to many pancreatic carcinomas, it is not common to tumors lacking glandular differentiation. HER-2/neu gene expression could not be related to survival differences--perhaps due to overall poor survival within adenocarcinomas of the pancreas--but the pattern of HER-2/neu expression suggests a relationship to glandular differentiation and early oncogenesis.

[A study on type I, III and IV collagen production in CCl4 induced rat liver fibrosis]

OBJECTIVE

To study the dynamic changes of alpha 1 (I), alpha 1 (III) and alpha I (IV) procollagen mRNA and collagen-producing cells during CCl4 induced SD rat liver fibrogenesis (20 weeks).

METHODS

The investigations were performed using Northern blot analysis, in situ hybridization and immunohistochemical techniques.

RESULTS

The increased expression of alpha 1 (III) procollagen mRNA during fibrogenesis by Northern blot analysis was the most predominant among the three mRNAs studied. However, the increase of alpha 1 (IV) procollagen mRNA expression occurred earlier, while the expression of alpha 1 (I) mRNA did not increase until the middle stage of the experiment. Desmin positive and/or smooth muscle actin positive Ito cells and myofibroblasts (MFs) in and around the necrotic areas expressed alpha 1 (I), alpha 1 (III) and alpha 1 (IV) procollagen mRNA signals detected by in situ hybridization during the early stage of the experiment. All the three procollagen mRNAs were mostly localized in fibroblasts (Fbs) and MFs in the septa during the mid and late stages of fibrosis.

CONCLUSIONS

Fbs and MFs were considered as important Col I, Col III and Col IV producing cells in liver fibrosis. Sinusoid endothelia were involved in Col IV synthesis in the fibrotic liver.

Effect of pressure ulcers on the survival of long-term care residents

BACKGROUND

Past studies have emphasized that patients with pressure ulcers are at high risk of dying. However, it remains unclear whether this increased risk is related to the ulcer or to coexisting conditions. In this study we examined the independent effect of pressure ulcers on the survival of long-term care residents.

METHODS

We evaluated all 19,981 long-term care residents institutionalized in Department of Veterans Affairs (VA) long-term care facilities as of April 1, 1993. Baseline resident characteristics and survival status were obtained by merging data from five existing VA data bases. Survival experience over a 6-month period was described using a proportional hazards model.

RESULTS

Pressure ulcers were present in 1,539 (7.7%) long-term care residents. Residents with pressure ulcers had a relative risk of 2.37 (95% CI = 2.13, 2.64) for dying as compared to those without ulcers. After adjusting for 16 other measures of clinical and functional status, the relative risk associated with pressure ulcers decreased to 1.45 (95% CI = 1.30, 1.65). No increased risk of death was noted for residents with deeper ulcers.

CONCLUSIONS

Pressure ulcers are a significant marker for long-term care residents at risk of dying. After adjusting for clinical and functional status, however, the independent risk associated with pressure ulcers declines considerably. The fact that larger ulcers are not associated with greater risk suggests that other unmeasured clinical conditions may also be contributing to the increased mortality associated with pressure ulcers.

Strain activation of bovine aortic smooth muscle cell proliferation and alignment: study of strain dependency and the role of protein kinase A and C signaling pathways

Smooth muscle cell (SMC) phenotype can be altered by physical forces as demonstrated by cyclic strain-induced changes in proliferation, orientation, and secretion of macromolecules. However, the magnitude of strain required and the intracellular coupling pathways remain ill defined. To examine the strain requirements for SMC proliferation, we selectively seeded bovine aortic SMC either on the center or periphery of silastic membranes which were deformed with 150 mm Hg vacuum (0-7% center; 7-24% periphery). SMC located in either the center or peripheral regions showed enhanced proliferation compared to cells grown under the absence of cyclic strain. Moreover, SMC located in the center region demonstrated significantly (P < 0.005) greater proliferation as compared to those in the periphery. In contrast, SMC exposed to high strain (7-24%) demonstrated alignment perpendicular to the strain gradient, whereas SMC in the center (0-7%) remained aligned randomly. To determine the mechanisms of these phenomena, we examined the effect of cyclic strain on bovine aortic SMC signaling pathways. We observed strain-induced stimulation of the cyclic AMP pathway including adenylate cyclase activity and cyclic AMP accumulation. In addition, exposure of SMC to cyclic strain caused a significant increase in protein kinase C (PKC) activity and enzyme translocation from the cytosol to a particulate fraction. Further study was conducted to examine the effect of strain magnitude on signaling, particularly protein kinase A (PKA) activity as well as cAMP response element (CRE) binding protein levels. We observed significantly (P < 0.05) greater PKA activity and CRE binding protein levels in SMC located in the center as compared to the peripheral region. However, inhibition of PKA (with 10 microM Rp-cAMP) or PKC (with 5-20 ng/ml staurosporine) failed to alter either the strain-induced increase in SMC proliferation or alignment. These data characterize the strain determinants for activation of SMC proliferation and alignment. Although strain activated both the AC/cAMP/PKA and the PKC pathways in SMC, singular inhibition of PKA and PKC failed to prevent strain-induced alignment and proliferation, suggesting either their lack of involvement or the multifactorial nature of these responses.

Activation of the adenylyl cyclase/cyclic AMP/protein kinase A pathway in endothelial cells exposed to cyclic strain

The aim of this study was to assess the involvement of the adenylyl cyclase/cyclic AMP/protein kinase A pathway (AC) in endothelial cells (EC) exposed to different levels of mechanical strain. Bovine aortic EC were seeded to confluence on flexible membrane-bottom wells. The membranes were deformed with either 150 mm Hg (average 10% strain) or 37.5 mm Hg (average 6% strain) vacuum at 60 cycles per minute (0.5 s strain; 0.5 s relaxation) for 0-60 min. The results demonstrate that at 10% average strain (but not 6% average strain) there was a 1.5- to 2.2-fold increase in AC, cAMP, and PKA activity by 15 min when compared to unstretched controls. Further studies revealed an increase in cAMP response element binding protein in EC subjected to the 10% average strain (but not 6% average strain). These data support the hypothesis that cyclic strain activates the AC/cAMP/PKA signal transduction pathway in EC which may occur by exceeding a strain threshold and suggest that cyclic strain may stimulate the expression of genes containing cAMP-responsive promoter elements.

Activation of diacylglycerol in cultured endothelial cells exposed to cyclic strain

Confluent bovine aortic endothelial cells (EC) were grown on flexible membranes and subjected to 10% average strain at 60 cycles/min for up to 500 s. A biphasic increase in diacylglycerol (DAG) occurred, with an initial transient peak at 10 s followed by sustained elevation to 500 s. The early peak corresponded to the transient formation of inositol 1,4,5-trisphosphate, demonstrating hydrolysis of L-alpha-phosphatidylinositol (PI) by PI-specific phospholipase C. To determine the origin of the sustained DAG phase, we incubated confluent bovine aortic EC with 1 microCi/ml [14C]myristate overnight and subjected them to cyclic strain. There was a decrease in phosphatidylcholine (PC) and a corresponding increase in DAG at 10 s and 250 s, suggesting PC hydrolysis with the generation of DAG at both an early (10 s) and a late (250 s) phase. [14C]phosphatidylethanol, a specific product of phospholipase D (PLD) in the presence of 1% ethanol, was measured in EC preincubated with [14C]myristate. Cyclic strain led to an immediate and sustained activation of PLD. Increased ethanol concentration led to a consistent decrease in DAG. Furthermore, when EC were pretreated with 1% ethanol, the strain-induced proliferative response was attenuated.

Harmaline-induced tremor and impairment of learning are both blocked by dizocilpine in the rabbit

Harmaline is known to produce tremors and retard acquisition of the rabbit's nictitating membrane response. These actions have been demonstrated to depend on the ability of harmaline to activate the inferior olive which gives rise to climbing fibers that project directly onto Purkinje cells in cerebellar cortex. However, the precise receptor systems involved in harmaline's actions remains unknown. This study examined the role of the NMDA receptor in harmaline's actions. Harmaline (10 mg/kg, s.c.) produced intense tremors and impaired the acquisition of conditioned responses. Both of these effects of harmaline were significantly blocked by the prior administration of the noncompetitive NMDA channel blocker, dizocilpine (0.01 mg/kg, s.c. given 20 min prior to the administration of harmaline). This dose od dizocilpine had no effect on acquisition of conditioned responses when given alone. A higher dose of dizocilpine (0.1 mg/kg s.c.) completely blocked the tremorogenic effects of harmaline (10 mg/kg, s.c.). Dizocilpine had no effect on motor behavior when given alone. It was suggested that the blockade of harmaline's actions by dizocilpine may be occurring at NMDA channels within the inferior olive. Regardless of the site of action, these data demonstrate that harmaline's ability to activate the interior olivary nucleus depends on the normal activity of the NMDA receptor.

Gene regulation by mechanical forces

Endothelial cells are subjected to various mechanical forces in vivo from the flow of blood across the luminal surface of the blood vessel. The purpose of this review was to examine the data available on how these mechanical forces, in particular cyclic strain, affect the expression and regulation of endothelial cell function. Studies from various investigators using models of cyclic strain in vitro have shown that various vasoactive mediators such as nitric oxide and prostacyclin are induced by the effect of mechanical deformation, and that the expression of these mediators may be regulated at the transcription level by mechanical forces. There also seems to be emerging evidence that endothelial cells may also act as mechanotransducers, whereby the transmission of external forces induces various cytoskeletal changes and second messenger cascades. Furthermore, it seems these forces may act on specific response elements of promoter genes.

The nitric oxide synthesis inhibitor L-NAME facilitates associative learning

1. Nitric oxide has been suggested to play an important role in synaptic plasticity and in learning. 2. The authors examined the effects of NW-nitro-L-arginine methyl ester, a competitive and enantiomeric specific inhibitor of nitric oxide synthase, on classical conditioning of the rabbit's nictitating membrane response. 3. It was found that L-NAME significantly enhanced the acquisition of conditioned responses. 4. The enhanced conditioned responses were not due to a sensitization of the conditioned and unconditioned reflexes or to changes in baseline levels of responding. 5. The dose and route of administration of L-NAME employed in this study had no effect on blood pressure. 6. These results suggest that nitric oxide normally functions as a tonic inhibitory modulator of associative learning and that procedures aimed at decreasing its production may provide a novel approach for improving learning.

Isolation and sequence of the Drosophila virilis 60 A gene, a transforming growth factor-beta superfamily member related to vertebrate bone morphogenetic proteins

The complete protein-coding region of the Drosophila virilis 60 A gene, a member of the transforming growth factor-beta superfamily, was isolated and sequenced. The mature domain of the protein-coding region is 99% identical to the Drosophila melanogaster 60 A gene and 73% identical to human bone morphogenetic protein 5. In the pro-domain, a number of large blocks of amino acids are also highly conserved, indicating an important functional role for this portion of the protein as well. In the putative 5' and 3' untranslated regions, several short sequence motifs are conserved between D. virilis and D. melanogaster.

Ectopic expression of dE2F and dDP induces cell proliferation and death in the Drosophila eye

The deregulation of E2F activity is thought to contribute to the uncontrolled proliferation of many tumor cells. While the effects of overexpressing E2F genes have been studied extensively in tissue culture, the consequences of elevating E2F activity in vivo are unknown. To address this issue, transgenic lines of Drosophila were studied in which ectopic expression of dE2F and dDP was targeted to the developing eye. The co-expression of dDP or dE2F disrupted normal eye development, resulting in abnormal patterns of bristles, cone cells and photoreceptors. dE2F/dDP expression caused ectopic S phases in post-mitotic cells of the eye imaginal disc but did not disrupt the onset of neuronal differentiation. Most S phases were seen in uncommitted cells, although some cells that had initiated photo-receptor differentiation were also driven into the cell cycle. Elevated expression of dE2F and dDP caused apoptosis in the eye disc. The co-expression of baculovirus p35 protein, an inhibitor of cell death, strongly enhanced the dE2F/dDP-dependent phenotype. These results show that, in this in vivo system, the elevation of E2F activity caused post-mitotic cells to enter the cell cycle. However, these cells failed to proliferate unless rescued from apoptosis.

Requirements for dE2F function in proliferating cells and in post-mitotic differentiating cells

The transcription factor E2F is a target of the retinoblastoma tumor suppressor protein (pRB) and may mediate pRB regulation of S phase entry in mammalian cells. The recent identification of mutant alleles of the Drosophila E2F gene (dE2F) has shown that dE2F is required for embryogenesis. dE2F-mutant embryos lack a co-ordinated program of gene expression which accompanies S phase entry and DNA synthesis declines to levels that are barely detectable. We have investigated the role of the dE2F gene at later stages of development. dE2F is expressed in several larval tissues and is required for cell proliferation in the eye imaginal disc. Surprisingly, dE2F expression persists in post-mitotic cells of the eye disc of third-instar larvae. The loss of dE2F function in these cells causes a novel phenotype, characterized by loss of photoreceptors and abnormal rhabdomere cell morphology. These results show that dE2F is required at multiple stages of development and suggest that E2F may have an important function in post-mitotic cells in addition to its role during cell proliferation.

Variations in the management of acute myocardial infarction. Importance of clinical measures of disease severity

OBJECTIVE

To determine the extent to which resource use for patients hospitalized with acute myocardial infarction varies with clinical status, and to see if an observed difference in resource use between two states can be explained by clinically detailed risk adjustment.

DESIGN

Retrospective review of the clinical characteristics and resource use of 342 patients hospitalised in two states with acute myocardial infarction.

DATA SOURCES

Merged data from three sources: a large, existing research database used in developing the Medicare Mortality Predictor Score, clinical data abstracted from medical charts specifically for this study, and Medicare Parts A and B claims records.

PATIENTS

A probability sample of Medicare patients hospitalized in 1986 with a diagnosis of acute myocardial infarction and residing in either Wisconsin or Washington state; patients dying within 30 days are oversampled.

MEASUREMENTS AND MAIN RESULTS

Although patients were clinically similar in the two states, there were systematic differences in resource use. Patients in Wisconsin spent more than one extra day in the intensive care unit (ICU) (2.8 vs 1.7) as well as more than one extra non-ICU day in the hospital (8.0 vs 6.5) than patients in Washington. Patients in Wisconsin were also more likely to receive an echocardiogram (35.6% vs 15.8%), nuclear ventriculogram (12.8% vs 4.1%), exercise tolerance test (21.5% vs 3.4), and Holter monitoring (5.4% vs 0%). (All p < .01.) Differences in utilization were greater for patients at lower risk of dying. The average cost of care was 20.8% higher in Wisconsin (p = .01); risk adjustment for clinical and other factors reduced this difference to 11.8%, but did not eliminate it (p = .04).

CONCLUSIONS

Patients with acute myocardial infarction vary in resource use as a function of clinical factors present at admission and occurring during the hospital stay; comparisons that do not take account of these factors may not discriminate well between providers who care for sicker patients and those who are inefficient. The greater use of resources for patients in Wisconsin is at least partially explained by differences in clinical characteristics that are not presently captured in administrative data.

RBF, a novel RB-related gene that regulates E2F activity and interacts with cyclin E in Drosophila

Genetic studies have shown that cyclin E and dE2F are critical regulators of S-phase entry during Drosophila embryogenesis. Whereas the ectopic expression of cyclin E activates dE2F-dependent transcription, it has been proposed that cyclin E does not act directly on dE2F but targets a negative regulator of E2F activity. Such a regulator might be analogous to the family of RB-related proteins (pRB, p107, and p130) that associate with E2F in humans; however, extensive efforts have failed to find such homologs in Drosophila. We have developed a two-hybrid approach that allows transcription activators to be used as bait for interacting proteins. From a screen using Drosophila E2F (dE2F and dDP) as bait, we identified a novel gene, RBF. RBF combines several of the structural features of pRB, p107, and p130, suggesting that it may have evolved from a common ancestor to the three human genes. RBF associates with dE2F and dDP in vivo and is a stoichiometric component of E2F DNA-binding complexes. RBF specifically repressed E2F-dependent transcription and suppressed the phenotype generated by ectopic expression of dE2F and dDP in the developing Drosophila eye. RBF was phosphorylated by a cyclin E-associated kinase in vitro, and loss-of-function cyclin E mutations enhanced an RBF overexpression phenotype, consistent with the idea that the biological activity of RBF is negatively regulated by endogenous cyclin E. The properties of RBF suggest that it is the intermediary factor that was proposed to allow cyclin E induction of E2F activity. These findings indicate that RBF plays a critical role in the regulation of cell proliferation in Drosophila and show that analogous pathways regulate S-phase entry in a diverse range of species.

Cyclic strain causes heterogeneous induction of transcription factors, AP-1, CRE binding protein and NF-kB, in endothelial cells: species and vascular bed diversity

Recent studies demonstrate that cyclic strain stimulates protein kinase C in bovine aortic endothelial cells (BAEC) as well as the induction of immediate early genes and the transcription factor activator protein-1 (AP-1) in human umbilical vein endothelial cells (HUVEC). The objective of this study was to determine whether transcriptional factor induction in endothelial cells (EC) exposed to strain is the same with regard to the species and vascular bed they are derived from. Evidence for a heterogeneous response for growth, orientation and prostacyclin secretion has been obtained for a variety of EC exposed to cyclic strain. In this study, we investigated cyclic strain mediated induction of transcription factors, AP-1, cAMP response element binding protein (CRE) and nuclear factor kB (NF-kB) in cultured EC from HUVEC, human aorta (HAEC), and BAEC. EC were exposed to 10% average strain at 60 cpm for up to 24 h. At varying time points, nuclear protein was extracted and analyzed for production of AP-1, CRE and NF-kB by electromobility shift assay. The results demonstrate that EC exposure to cyclic strain leads to a significant induction of AP-1, CRE and NF-kB in HAEC and HUVEC, but not in BAEC. Furthermore, these findings are in marked contrast to the previously described shear stress induced activation of AP-1 and NF-kB in BAEC. There was also a temporal difference in their response such that stretch-induced activation of AP-1 and NF-kB peaked at 4 h, whereas CRE increased in a biphasic manner at 15 min and 24 h. These results may partially explain the divergent effects of cyclic strain on EC gene expression and phenotype in EC from different vascular beds and species and underscore the difference in EC response to cyclic strain and shear stress.

Hypotensive stress retards associative learning in rabbits

This study examined the effects of hypotensive stress on classical conditioning of the rabbit's nictitating membrane response. Hypotension, consisting of an approximately 45% decrease in blood pressure, was maintained for 30 min by the i.v. infusion of sodium nitroprusside. Twenty minutes later animals were exposed to a conditioning session consisting of 60 pairings of a 200 ms tone conditioned stimulus with a 100 ms airpuff unconditioned stimulus directed at the cornea. This procedure was repeated for four consecutive days. Animals exposed to the hypotensive stress demonstrated a significantly retarded acquisition of conditioned responses as measured by their frequency and onset latency as well as by an increase in the number of trials required to reach acquisition criteria of five and 10 consecutive conditioned responses as compared with controls. A separate group of animals received a nitroprusside infusion one day after the acquisition of conditioned responses to the tone conditioned stimulus. These animals demonstrated a normal retention of conditioned responses and a normal response to varying intensities of the conditioned stimulus. Hypotensive stress also had no effect on the frequency and topography of the unconditioned response. It was concluded that a decrease in blood pressure can serve as a physiological stressor. One of the reactions to this stress consists of a retardation in the formation of associations during a learning task, without any decrease in the ability to retrieve previously learned material.

Ultrastructural cytochemistry of human gastric cancer: electron microscopic observations of five organellae marker enzymes

The distribution of ALPase, ACPase, G6Pase TPPase and CCOase of gastric cancer and normal gastric epithelium were studied ultrastructurally. The results showed that normal gastric epithelium had no ALPase reaction. The reactions of ACPase, G6Pase, TPPase and CCOase were found in the corresponding organellae which were consistent with their functions. In tubular adenocarcinoma cells, their reactions were more apparent in the corresponding organellae. Some cells of tubular adenocarcinomas showed ALPase reaction. The mucinous adenocarcinoma cells had higher ACPase and TPPase reactions. In poorly differentiated adenocarcinoma cells, the five marker enzymes showed negative or faint reactions. The biological significance and mechanisms of distribution of the five marker enzymes were discussed.

The high mobility group protein HMG I(Y) can stimulate or inhibit DNA binding of distinct transcription factor ATF-2 isoforms

The high mobility group protein HMG I(Y) stimulates the binding of a specific isoform of the activating transcription factor 2 (ATF-2(195)) to the interferon beta (IFN-beta) gene promoter. HMG I(Y) specifically interacts with the basic-leucine zipper region of ATF-2(195), and HMG I(Y) binds to two sites immediately flanking the ATF-2 binding site of the IFN-beta promoter. Here, we show that HMG I(Y) can stimulate the binding of ATF-2(195), at least in part, by promoting ATF-2 dimerization. In addition, we report the characterization of a naturally occurring isoform of ATF-2 (ATF-2(192)) that binds specifically to the IFN-beta promoter but is unable to interact with HMG I(Y). Remarkably, HMG I(Y) inhibits the binding of ATF-2(192) to the IFN-beta promoter. Thus, the ability of HMG I(Y) to specifically interact with ATF-2 correlates with its ability to stimulate ATF-2 binding to the IFN-beta promoter. Comparisons of the amino acid sequences of the basic-leucine zipper domains of ATF-2(195) and ATF-2(192) suggest that HMG I(Y) interacts with a short stretch of basic amino acids near the amino terminus of the basic-leucine zipper domain of ATF-2(195).

Methylenedioxyamphetamine: a selective effect on cortical content and turnover of 5-HT

This study examined the effects of the hallucinogen, MDA, on brain content of monoamines and their metabolites in the rabbit. A single 1.8 mg/kg dose of MDA produced 30 to 64% increases in the 5-HT content of frontal cortex from 30 to 120 min after injection and a decrease in 5-HT turnover from 30 min to 8 h, but had no effect in hippocampus, caudate nucleus, or hypothalamus. A single 3.6 mg/kg dose of MDA also reduced the turnover of 5-HT in frontal cortex, but this was accompanied by a decrease in 5-HIAA with no increase in 5-HT. The 1.8 and 3.6 mg/kg doses of MDA had no significant or consistent effects on the contents of DA, DOPAC, HVA, and NE in any brain area examined. Chronic administration of MDA (3.6 mg/kg/day for 4 days) failed to produce any evidence of a neurotoxic action on 5-HT neurons. Higher doses could not be employed because the LD50 of MDA was approximately 5 mg/kg. This study has demonstrated that behaviorally effective and nonneurotoxic doses of MDA produce increases in the content and decreases in turnover of 5-HT in frontal cortex that resemble those of other hallucinogens such as LSD and DOM.

Polydioxanone absorbable sutures in vascular anastomoses: experimental and preliminary clinical studies

To assess the safety and efficacy of polydioxanone suture (PDS) for vascular anastomoses, bilateral carotid end-to-end anastomoses using PDSs on the left and Dacron sutures on the right in 18 dogs were performed. The anastomoses were assessed at 4, 6 and 8 weeks after surgery. A breaking-strength test (300 mmHg) did not show a significant difference between PDS and Dacron anastomoses, but partial absorption was grossly evident in the PDS group. Some 35 venous and 21 arterial reconstructive procedures were also carried out using PDS in 53 patients. At follow-up of 3-5 (mean 3.5) years, none of the patients had experienced any suture-related complications. The results indicate that PDS maintains an adequate tensile strength in anastomoses until suture-line healing occurs, suggesting that this material may be safely used in venous or small arterial anastomoses. In addition, because it is absorbable, resulting in decreased foreign-body reactions, PDS may have the potential to improve the long-term patency of venous or small arterial reconstructions.

[Experimental study and clinical application of endothelium seeded vena caval prostheses]

One hundred and eleven mongrel dogs were used for this study. Endothelial cells were harvested from jugular vein or omentum with methods of collagenase digestion and density gradient separation. Animal model of prosthetic interposition into the inferior vena cava with or without distal arteriovenous fistula was established. The complete endothelialization was established 5 to 10 days following a high density seeding. The neointimal hyperplasia was inhibited. A 100-day 100% patency of prosthesis was reached. The seeded endothelium secreted higher level of PGI2 than normal control and lower level of TXB2, hence the positive effect of distal AVF functioning for a week on the patency was demonstrated. This method used in 10 cases with Budd-Chiari syndrome resulting in good outcome after 3 to 5 years follow-up. We conclude that the endothelial seeding technique has a promising future using in the venous circuit.

Mechanisms of transcriptional synergism between distinct virus-inducible enhancer elements

The high mobility group protein HMG I(Y) and the transcription factor NF-kappa B are required for the activity of positive regulatory domain II (PRDII), a virus-inducible regulatory element of the human interferon-beta gene promoter. In this paper we provide evidence that HMG I(Y) is also required for the activity of PRDIV, a regulatory element that synergizes with PRDII. In this case, HMG I(Y) stimulates binding of activating transcription factor 2 (ATF-2) and the assembly of inducible complexes containing ATF-2 and c-Jun. Remarkably, HMG I(Y) also specifically interacts with the leucine zipper/basic region of ATF-2, and ATF-2 in turn interacts with NF-kappa B. We therefore propose that the HMG I(Y) plays a critical structural role in establishing transcriptional synergy between PRDII and PRDIV by promoting the activities and/or binding of NF-kappa B and ATF-2 and by facilitating their interaction.

Enhanced patency of venous Dacron grafts by endothelial cell sodding

The effect of microvessel endothelial cell (EC) sodding on the patency of Dacron grafts interposed in canine inferior vena cava was studied. EC were harvested enzymatically from canine omentum and isolated by density gradient centrifugation. Preclotted, knitted Dacron grafts were sodded with > 10(6) EC/cm2 surface. The results demonstrate significant improvement in patency of sodded grafts placed in the inferior vena cava as compared with control grafts (p < 0.001 in grafts with a distal arteriovenous fistula and p < 0.05 in grafts without a distal fistula). The neointima of the sodded grafts were thinner and scanning electron microscopy confirmed the presence of a confluent layer of EC. In addition, the production of prostacyclin but not thromboxane A2 was significantly enhanced in the sodded grafts as compared with controls. We conclude that microvessel EC sodding of Dacron grafts significantly improves the patency rate and inhibits neointimal thickening of the prosthesis. The mechanism is unknown but may involve a more rapid endothelialization of the graft surface with the potential of producing more prostacyclin and less thromboxane A2.

Weight loss in Alzheimer's disease

In order to determine whether weight loss is a core symptom or secondary manifestation of Alzheimer's disease, we analyzed weight change in 81 outpatients with Alzheimer's disease. During a mean 2.9 years of observation, the mean absolute weight loss was 1.9 +/- 0.8 kg, and the mean weight loss per year was 0.7 +/- 0.3 kg. Although statistically significant (P < .05), the mean absolute weight loss was only 3% of initial body weight. Data analyses revealed that weight change was significantly (P < .0001) correlated with decreased independence in self-feeding. Weight change was not related to duration of dementia, clinical measures of dementia severity, psychiatric symptoms, or medications. These observations support the view that weight loss is a consequence of Alzheimer's disease and does not reflect specific brain lesions.

An ATF/CREB binding site is required for virus induction of the human interferon beta gene [corrected]

We report the characterization of a distinct regulatory element of the human interferon beta (HuIFN-beta) gene promoter, which we designate PRDIV (positive regulatory domain IV). In previous studies, sequences between -104 and -91 base pairs upstream from the start site of transcription were shown to be required for maximal levels of virus induction in mouse L929 cells. We have localized the essential sequence in this region extending from -99 to at least -91, and we show that this sequence is a binding site for a protein of the activating transcription factor/cAMP response element binding protein (ATF/CREB) family of transcription factors. Mutations in PRDIV that decrease the affinity of one member of this family (ATF-2/CRE-BP1) decrease the level of virus induction in vivo. Moreover, multiple copies of PRDIV can confer both virus and cAMP inducibility upon a minimal promoter in L929 cells, while it is constitutively active in HeLa cells. We conclude that PRDIV is a distinct regulatory element of the HuIFN-beta promoter and that the signal transduction pathways involved in virus and cAMP induction may partially overlap.

In vitro microleakage at the gingival margin of porcelain and resin veneers

This in vitro study investigated the effect of dental surface treatments on the seal of porcelain and resin laminate veneers to tooth structure. Nine groups of 20 teeth were prepared for labial veneers--six groups with the apical margin of the veneer in dentin, two groups with the veneer wholly bordered by enamel, and one group with the apical margin coincident with the apical margin of a previously placed glass ionomer restoration. The teeth were treated with a variety of dentin-bonding agents prior to restoration of eight groups with porcelain veneers and one group with Visio-Gem microfilled resin veneers. After placement, the veneers were stored in water for 4 days, then subjected to thermocycling before silver staining and sectioning. Results showed no leakage around the margins of the veneers wholly bordered by enamel. Complete leakage was found around the glass ionomer restorations, and nearly total leakage was found along the resin-dentin interface of the resin veneers. The porcelain veneers that extended onto dentin showed variable but limited leakage for four of five of the dentin-bonding treatments.

Effects of aspirin, dipyridamole, and dibutyryl cyclic adenosine monophosphate on platelet-derived growth factor A chain mRNA levels in human saphenous vein endothelial cells and smooth muscle cells

Aspirin and dipyridamole have frequently failed to control intimal hyperplasia in vascular grafts in animal and clinical trials. These trials were based on the concept that the smooth muscle mitogen, platelet-derived growth factor (PDGF) released from platelets, was a major cause of intimal hyperplasia. Both endothelial and smooth muscle cells (ECs and SMCs), however, can also release PDGF-like SMC mitogens that might cause intimal hyperplasia. We therefore tested whether aspirin and dipyridamole alone or together can affect PDGF-A chain mRNA levels in cultured human saphenous vein ECs and SMCs. Cultures were exposed for 72 hours to 3 x 10(-5) mol/L aspirin and/or 5 x 10(-6) mol/L dipyridamole. Cellular RNA was then extracted, and PDGF-A chain mRNA signal levels were measured by a reverse transcription/polymerase chain reaction method. mRNA for glyceraldehyde-3-phosphate dehydrogenase was used as a constitutively expressed control RNA species. Signal strength on Southern blots of amplified polymerase chain reaction products was measured by densitometry. Neither aspirin nor dipyridamole alone or together reduced the ratio (PDGF-A chain signal/glyceraldehyde-3-phosphate dehydrogenase signal) below that of control cultures. PDGF-A chain expression was not a constitutive artifact of culture because dibutyryl cyclic AMP (5 x 10(-4) mol/L) reduced PDGF-A chain signal from a control index of 1.0 to 0.5 +/- 0.1 (mean +/- SE) (n = 3; p less than 0.05) in EC cultures and to 0.2 (mean) (n = 2) in SMC cultures. These data may explain why aspirin and dipyridamole fail to reduce intimal hyperplasia in some animal and clinical trials despite effective inhibition of platelet aggregation.

Reevaluation of limited side-to-side portacaval shunt

Although the results of limited side-to-side portacaval shunt were better than those of other shunts, postoperative encephalopathy still occurred in 10.2% of the patients. To determine the relationship between the diameter of anastomotic stoma and the development of postoperative encephalopathy, animal experiments and clinical observations were carried out. In 4 of 8 dogs in 3 months after limited side-to-side portacaval shunt and in 6 patients with postoperative encephalopathy, there was significant augmentation of the diameter of anastomotic stoma. To prevent the widening of anastomotic stoma caused by blood flow under high pressure, a limiting ring of 10 mm in diameter was put around the anastomotic site during operation in 21 patients with portal hypertension. Follow-up for 3-15 months (average 6 months) showed that there was no evidence of postoperative encephalopathy and rebleeding. A ring of same kind was put around the dilated anastomotic stoma during exploration in the 6 patients, and all their cerebral symptoms and signs disappeared completely soon after the second operation.

Rapid cellular luminal coverage of Dacron inferior vena cava prostheses in dogs by immediate seeding of autogenous endothelial cells derived from omental tissue: results of a preliminary trial

Endothelial cell seeding methods might reduce the high failure rates of venous vascular prostheses, but low flow rates in venous vascular prostheses impose a need to protect early patency and to attain early endothelial cell coverage without waiting several weeks for relatively small endothelial cell innocula from autologous veins to form confluent linings. To obtain large number of autologous endothelial cells for high-density seeding, canine omental microvascular endothelial cells were harvested by collagenase digestion and density gradient centrifugation, with yields of 1.34 +/- 0.24 (SD) X 10(6) cells/gm of omentum (N = 8 harvests). Primary culture of a subfraction from each harvest showed the cell population to be dominated by factor VIII-related antigen-positive endothelial cells with only a few nonstaining cells (estimated to be 10% or less of total cell number) visible. Freshly harvested omental cells were seeded onto double velour knitted Dacron prostheses at densities of 5 X 10(5) cells/cm2 of graft luminal surface in an autologous plasma suspension by use of prior preclotting with cell-free autologous plasma, followed by endothelial cell seeding in autologous plasma, with plasma recalcification during endothelial cell instillation. Six seeded and two control (sham-seeded) vascular prostheses 5 cm long with 10 mm inner diameter were used as inferior vena cava interposition grafts. A distal arteriovenous fistula and aspirin (300 mg) and dipyridamole (50 mg orally every day) starting 3 days before surgery were used to protect early patency of all grafts. Seeded venous vascular prostheses were explanted for study at intervals of 1,5, and 10 days after surgery (N = 2 prostheses at each time); the two control venous vascular prostheses were explanted at 10 days. All venous vascular prostheses were patent at time of removal. In seeded venous vascular prostheses, light, scanning, and transmission electron microscopy showed emergence of numerous flattened endothelial cell-like cells on the luminal surface 24 hours after surgery, followed by formation of a confluent cellular lining without adherent platelets by 5 to 10 days after surgery. Control venous vascular prostheses, in contrast, remained covered by an irregularly thickened fibrin and red cell thrombus, which sometimes encroached on the lumen. Our results suggest that (1) omental tissue can furnish endothelial cells for high-density immediate seeding of venous vascular prostheses, and (2) that the method we used to combine features of both so-called high density "seeding" and "sodding" techniques offers both more rapid prosthesis coverage than the former and shorter intraoperative times for cell attachment to prostheses than the latter.(ABSTRACT TRUNCATED AT 400 WORDS)