A material sensitivity study on the accuracy of deformable organ registration using linear biomechanical modelsa)

Model-based deformable organ registration techniques using the finite element method (FEM) have recently been investigated intensively and applied to image-guided adaptive radiotherapy (IGART). These techniques assume that human organs are linearly elastic material, and their mechanical properties are predetermined. Unfortunately, the accurate measurement of the tissue material properties is challenging and the properties usually vary between patients. A common issue is therefore the achievable accuracy of the calculation due to the limited access to tissue elastic material constants. In this study, we performed a systematic investigation on this subject based on tissue biomechanics and computer simulations to establish the relationships between achievable registration accuracy and tissue mechanical and organ geometrical properties. Primarily we focused on image registration for three organs: rectal wall, bladder wall, and prostate. The tissue anisotropy due to orientation preference in tissue fiber alignment is captured by using an orthotropic or a transversely isotropic elastic model. First we developed biomechanical models for the rectal wall, bladder wall, and prostate using simplified geometries and investigated the effect of varying material parameters on the resulting organ deformation. Then computer models based on patient image data were constructed, and image registrations were performed. The sensitivity of registration errors was studied by perturbating the tissue material properties from their mean values while fixing the boundary conditions. The simulation results demonstrated that registration error for a subvolume increases as its distance from the boundary increases. Also, a variable associated with material stability was found to be a dominant factor in registration accuracy in the context of material uncertainty. For hollow thin organs such as rectal walls and bladder walls, the registration errors are limited. Given 30% in material uncertainty, the registration error is limited to within 1.3 mm. For a solid organ such as the prostate, the registration errors are much larger. Given 30% in material uncertainty, the registration error can reach 4.5 mm. However, the registration error distribution for prostates shows that most of the subvolumes have a much smaller registration error. A deformable organ registration technique that uses FEM is a good candidate in IGART if the mean material parameters are available.

Properties of pyrolytic chars and activated carbons derived from pilot-scale pyrolysis of used tires

Used tires were pyrolyzed in a pilot-scale quasi-inert rotary kiln. Influences of variables, such as time, temperature, and agent flow, on the activation of obtained char were subsequently investigated in a laboratory-scale fixed bed. Mesoporous pores are found to be dominant in the pore structures of raw char. Brunauer-Emmett-Teller (BET) surfaces of activated chars increased linearly with carbon burnoff. The carbon burnoff of tire char achieved by carbon dioxide (CO2) under otherwise identical conditions was on average 75% of that achieved by steam, but their BET surfaces are almost the same. The proper activation greatly improved the aqueous adsorption of raw char, especially for small molecular adsorbates, for example, phenol from 6 to 51 mg/g. With increasing burnoff, phenol adsorption exhibited a first-stage linear increase followed by a rapid drop after 30% burnoff. Similarly, iodine adsorption first increased linearly, but it held as the burnoff exceeded 40%, which implied that the reduction of iodine adsorption due to decreasing micropores was partially made up by increasing mesopores. Both raw chars and activated chars showed appreciable adsorption capacity of methylene-blue comparable with that of commercial carbons. Thus, tire-derived activated carbons can be used as an excellent mesoporous adsorbent for larger molecular species.

Interaction of EVI1 with cAMP-responsive element-binding protein-binding protein (CBP) and p300/CBP-associated factor (P/CAF) results in reversible acetylation of EVI1 and in co-localization in nuclear speckles

EVI1 is a very complex protein with two domains of zinc fingers and is inappropriately expressed in many types of human myeloid leukemias. Using reporter gene assays, several investigators showed that EVI1 is a transcription repressor, and recently it was shown that EVI1 interacts with the co-repressor carboxyl-terminal binding protein 1 (CtBP1). Earlier, we showed that the inappropriate expression of EVI1 in murine hematopoietic precursor cells leads to their abnormal differentiation and to increased proliferation. Using biochemical assays, we have identified two groups of transcription co-regulators that associate with EVI1 presumably to regulate gene expression. One group of co-regulators includes the CtBP1 and histone deacetylase. The second group includes the two co-activators cAMP-responsive element-binding protein-binding protein (CBP) and p300/CBP-associated factor (P/CAF), both of which have histone acetyltransferase (HAT) activity. All of these proteins require separate regions of EVI1 for efficient interaction, and they divergently affect the ability of EVI1 to regulate gene transcription in reporter gene assays. Confocal microscopy analysis shows that in the majority of the cells, EVI1 is nuclear and diffused, whereas in about 10% of the cells EVI1 localizes in nuclear speckles. However, in the presence of the added exogenous co-repressors histone deacetylase or CtBP1, all of the nuclei have a diffuse EVI1 staining, and the proteins do not appear to reside together in obvious nuclear structures. In contrast, when CBP or P/CAF are added, defined speckled bodies appear in the nucleus. Analysis of the staining pattern indicates that EVI1 and CBP or EVI1 and P/CAF are contained within these structures. These nuclear structures are not observed when CBP is substituted with a point mutant HAT-inactive CBP with which EVI1 also physically interacts. Finally, we show that the interaction of EVI1 with either CBP or P/CAF leads to acetylation of EVI1. These results suggest that the assembly of EVI1 in nuclear speckles requires the intact HAT activity of the co-activators.

[Studies on separation, purification and chemical structure of polysaccharide from Atractylodes macrocephala]

Separation and purification were done by column chromatographic fractionation; HPLC and 13C-NMR were used to determine the chemical structure of polysaccharide from Atractylodes macrocephala Koidz;, The molecular weight of the polysaccharide was estimated to be 1.36 x 10(5) (PSAM-1) and 1.04 x 10(5) (PSAM-2).

Anti-CD11a ameliorates disease in the human psoriatic skin-SCID mouse transplant model: comparison of antibody to CD11a with Cyclosporin A and clobetasol propionate

The present study assesses the applicability of human skin-SCID (severe combined immunodeficiency) mouse chimeras in testing antipsoriatic therapeutics. Three agents were examined: (1) a monoclonal antibody to the alpha subunit of leukocyte function associated antigen-1 integrin (CD11a); (2) Cyclosporin A; and (3) clobetasol propionate (Temovate), a potent topical corticosteroid used clinically in the treatment of psoriasis. Skin transplanted to SCID mice from normal human volunteers or from psoriatic lesional skin was allowed to heal for 3 to 5 weeks before application of test reagents. During this period, psoriatic skin, which was 3.8-fold thicker than the corresponding normal skin before transplantation, maintained its phenotype (ie, increased epidermal thickness, rete ridges with blunted ends, and intralesional presence of T lymphocytes). Transplanted normal human skin, however, underwent a hyperplastic response during this period, resulting in a 2.4-fold increase in epidermal thickness. After the healing period, animals transplanted with normal or psoriatic skin were treated for 14 days by daily intraperitoneal injection of either Cyclosporin A or a monoclonal antibody to human CD11a, or by topical application of clobetasol propionate. At the end of the treatment period, the mice were killed and the tissue evaluated morphometrically for changes in epidermal thickness and immunohistologically for the presence of T lymphocytes. Both Cyclosporin A and anti-CD11a reduced the epidermal thickness of transplanted psoriatic skin, whereas neither reagent significantly reduced the thickness of transplanted normal skin. T lymphocytes were detected in the skin from treated animals; there did not seem to be any reduction in the number of T lymphocytes. Clobetasol propionate reduced the epidermal thickness of both normal and psoriatic skin. These data indicate that, in this model, therapies directed against pathophysiologic mechanisms that contribute to psoriasis can be distinguished from treatments that block epidermal hyperplasia occurring as a consequence of xenografting. Our observations provide evidence for the activity of anti-CD11a in an animal model of human psoriasis.

Negative regulation of Gcn4 and Msn2 transcription factors by Srb10 cyclin-dependent kinase

The budding yeast transcriptional activator Gcn4 is rapidly degraded in an SCF(Cdc4)-dependent manner in vivo. Upon fractionation of yeast extracts to identify factors that mediate Gcn4 ubiquitination, we found that Srb10 phosphorylates Gcn4 and thereby marks it for recognition by SCF(Cdc4) ubiquitin ligase. Srb10 is a physiological regulator of Gcn4 stability because both phosphorylation and turnover of Gcn4 are diminished in srb10 mutants. Gcn4 is almost completely stabilized in srb10Delta pho85Delta cells, or upon mutation of all Srb10 phosphorylation sites within Gcn4, suggesting that the Pho85 and Srb10 cyclin-dependent kinases (CDKs) conspire to limit the accumulation of Gcn4. The multistress response transcriptional regulator Msn2 is also a substrate for Srb10 and is hyperphosphorylated in an Srb10-dependent manner upon heat-stress-induced translocation into the nucleus. Whereas Msn2 is cytoplasmic in resting wild-type cells, its nuclear exclusion is partially compromised in srb10 mutant cells. Srb10 has been shown to repress a subset of genes in vivo, and has been proposed to inhibit transcription via phosphorylation of the C-terminal domain of RNA polymerase II. We propose that Srb10 also inhibits gene expression by promoting the rapid degradation or nuclear export of specific transcription factors. Simultaneous down-regulation of both transcriptional regulatory proteins and RNA polymerase may enhance the potency and specificity of transcriptional inhibition by Srb10.

[Experimental and mechanism analyses on HCl emission control during PVC combustion in fixed beds]

Incineration of chloridated plastic (PVC) in solid wastes contributes much to HCl pollutant in air environment. The characteristics of HCl emissions and reduction during PVC combustion were conducted in a nearly isothermal, externally heated, horizontal quartz-tube reactor. With increasing temperature from 700 to 900 degrees C, the conversion of HCl increased leniently from 82.5% to 88.3%. High excess air factor enhanced a small amount of HCl existing in form of Cl2. The calcium-based sorbents including CaCO3, Ca(OH)2, Ca(CH3COO)2 exhibited high HCl capture efficiencies from 68% to 79%, while magnesium-based sorbent less than that of 3%. Influences of operational variables, i.e., size of sorbent, Ca/Cl molar ratio and combustion fume compositions, on the HCl reduction were discussed. From a point of view of equilibrium constant of dechloridization reaction the experimental results were explained in detail.

Simulation study and implementation of the tests based on weighted Turnbull's estimators for interval-censored data

Several tests for comparing k groups of interval-censored data based on Turnbull's estimator of a survival function are compared by a Monte Carlo simulation study. The tests under consideration include the IWD test proposed by Petroni and Wolfe, the score test derived by Finkelstein, and a logrank type test suggested by Sun. With a large sample size and in a two-sample comparison, simulation results suggest that the IWD test is applicable for early and crossing hazard difference alternatives, whereas Finkelstein's score test, Sun's test and the logrank test are slightly more powerful than the IWD tests under late hazard difference alternatives. The IWD test is designed for the two-sample testing problem. With a large sample size and in a k-sample comparison, Finkelstein's score test is slightly better than the other tests under a proportional hazards model, while Sun's test and the logrank test are slightly better than the score test under early and crossing hazard difference alternatives. However, none of the test statistics is uniformly better than the others for the alternatives considered in this paper with both non-overlapping and overlapping interval-censored data.

15N NMR relaxation studies of free and ligand-bound human acidic fibroblast growth factor

15N NMR relaxation data have been used to characterize the backbone dynamics of the human acidic fibroblast growth factor (hFGF-1) in its free and sucrose octasulfate (SOS)-bound states. (15)N longitudinal (R(1)), transverse (R(2)) relaxation rates and (1H)-(15)N steady-state nuclear Overhauser effects were obtained at 500 and 600 MHz (at 25 degrees C) for all resolved backbone amide groups using (1)H- detected two-dimensional NMR experiments. Relaxation data were fit to the extended model free dynamics for each NH group. The overall correlation time (tau(m)) for the free and SOS-bound forms were estimated to be 10.4 +/- 1.07 and 11.1 +/- 1.35 ns, respectively. Titration experiments with SOS reveals that the ligand binds specifically to the C-terminal domain of the protein in a 1:1 ratio. Binding of SOS to hFGF-1 is found to induce a subtle conformational change in the protein. Significant conformational exchange (R(ex)) is observed for several residues in the free form of the protein. However, in the SOS-bound form only three residues exhibit significant R(ex) values, suggesting that the dynamics on the micro- to millisecond time scale in the free form is coupled to the cis-trans-proline isomerization. hFGF-1 is a rigid molecule with an average generalized parameter (S(2)) value of 0.89 +/- 0.03. Upon binding to SOS, there is a marked decrease in the overall flexibility (S(2) = 0.94 +/- 0.02) of the hFGF-1 molecule. However, the segment comprising residues 103-111 shows increased flexibility in the presence of SOS. Significant correlation is found between residues that show high flexibility and the putative receptor binding sites on the protein.

Nuclear-specific degradation of Far1 is controlled by the localization of the F-box protein Cdc4

Far1 is a bifunctional protein that is required to arrest the cell cycle and establish cell polarity during yeast mating. Here we show that SCF(Cdc4) ubiquitylates Far1 in the nucleus, which in turn targets the multi-ubiquitylated protein to 26S proteasomes most likely located at the nuclear envelope. In response to mating pheromones, a fraction of Far1 was stabilized after its export into the cytoplasm by Ste21/Msn5. Preventing nuclear export destabilized Far1, while conversely cytoplasmic Far1 was stabilized, although the protein was efficiently phosphorylated in a Cdc28-Cln-dependent manner. The core SCF subunits Cdc53, Hrt1 and Skp1 were distributed in the nucleus and the cytoplasm, whereas the F-box protein Cdc4 was exclusively nuclear. A cytoplasmic form of Cdc4 was unable to complement the growth defect of cdc4-1 cells, but it was sufficient to degrade Far1 in the cytoplasm. Our results illustrate the importance of subcellular localization of F-box proteins, and provide an example of how an extracellular signal regulates protein stability at the level of substrate localization.

Differential response of obese gene expression from fasting in bovine adipose tissues

To understand the molecular mechanism for intramuscular fat deposition, the expression of the obese gene was examined in response to fasting. Food deprivation for 48 h induced a decrease in the level of obese mRNA in pooled adipose tissues (abdominal, perirenal, subcutaneous, intermuscular and intramuscular). The expression of obese mRNA was examined for individual adipose tissue from several fat depots. It was highly expressed in perirenal adipose tissue, but fasting did not affect its expression level in this tissue. Moderate levels were detected in subcutaneous and intermuscular adipose tissues, and a fasting-induced decrease in obese mRNA was apparent in these tissues. The expression level of the obese gene in intramuscular adipose tissue was very low and did not respond to fasting.

[Experimental study on polyphenol anti-plaque effect in human]

OBJECTIVE

To evaluate anti-caries effect of Chinese green tea's polyphenol.

METHODS

150 volunteers are randomly divided into 3 groups: A, B test group and contrast group, 50 persons in each. People in test groups were given polyphenol's tablet, placebo was given in contrast group, a tablet three times a day. After 3 weeks, group A was given placebo and group B continued polyphenol for 6 weeks.

RESULTS

After using polyphenol's tablet for 2 weeks, the plaque index of test groups were evidently lower than the contrast group (P < 0.01). After stopping use of polyphenol tablet, the effect was still kept for 3 weeks.

CONCLUSION

It can be concluded that polyphenol tablet from Chinese green tea has evident anti-plaque effect.

Elaboration of matrix metalloproteinase inhibitors by human skin in organ culture and by skin cells in monolayer culture: relationship to invasion

Functional and immunochemical approaches were used to assess matrix metalloproteinase (MMP) inhibitors, e.g., tissue inhibitor of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2), in organ cultures of normal human skin maintained under growth factor free conditions or in medium supplemented with a combination of growth factors including epidermal growth factor, insulin, and pituitary extract. It has previously been shown that under growth factor free conditions, normal skin structure and function are maintained for several days, while in the presence of these exogenous growth factors, the epithelial cells invade the stroma [Invasion and Metastasis 1993;13:225-233]. TIMP-1 was detected in equivalent amounts in organ culture fluids under both conditions. TIMP-2 was not detected under either condition. Normal epidermal keratinocytes, normal dermal fibroblasts, and three different epithelial tumor cell lines were also examined for MMP inhibitor expression. Keratinocytes and fibroblasts produced high levels of both TIMP-1 and TIMP-2, but in neither cell type was there a significant difference between growth factor free and growth factor containing conditions. In contrast, the three epithelial tumor cell lines produced low to undetectable levels of both TIMP-1 and TIMP-2. These data suggest that acquisition of local invasive capacity is not dependent on a reduction in MMP inhibitor expression. A reduction in MMP inhibitors may accompany the transition from invasive to metastatic tumors.

Clinical evaluation of heparin-coated circuits for routine coronary artery bypass grafting surgery: a prospective randomized study

The aim of this study was to demonstrate the clinical and biological benefits of heparin-coated circuits in routine coronary artery bypass grafting (CABG). A prospective, randomized study was conducted in 80 patients undergoing routine CABG. Patients were randomized to either noncoated circuits (Group 1) or heparin-coated circuits (Group 2). A complete clinical evaluation was performed preoperatively at Days 0, 1, 2, and 3 and at discharge day and combined with extensive laboratory tests for hemostasis and inflammatory response. This study did not prove any major statistically significant clinical benefit of heparin-coated circuits in low risk patients. Postoperative bleeding, significantly less in the heparin-coated group, did not decrease significantly the number of transfused patients. Biological values were not changed significantly except for factor II and monocytes, which were higher in Group 2. Heparin-coated circuits offer minimal clinical and biological benefits for routine CABG surgery. However, they may prove beneficial for complex procedures or at-risk patients.

Troglitazone improves psoriasis and normalizes models of proliferative skin disease: ligands for peroxisome proliferator-activated receptor-gamma inhibit keratinocyte proliferation

BACKGROUND

Psoriasis is often treated with agents that activate nuclear hormone receptors for glucocorticoids, retinoids, and vitamin D. The peroxisome proliferator-activated receptor-gamma (PPARgamma) is a related nuclear hormone receptor that can be activated by its ligands, including the thiazolidinediones.

OBJECTIVE

To assess whether treatment with troglitazone, a currently available thiazolidinedione used to treat diabetes mellitus, has an effect on psoriasis in normoglycemic patients and whether ligands for PPARgamma have an effect on models of psoriasis.

DESIGN

Open-label administration of troglitazone in patients with psoriasis and evaluation of drug actions in cellular, organ, and transplant models of psoriasis.

SETTING

University and community hospital outpatient departments and university laboratories.

PATIENTS

Patients with chronic, stable plaque psoriasis and control subjects. Five patients with psoriasis received troglitazone (none withdrew); 10 different untreated patients and 10 controls provided tissue samples.

INTERVENTIONS

Oral troglitazone therapy at various dosages in patients with psoriasis; also, use of troglitazone, ciglitazone, and 15-deoxy-delta-12,14-prostaglandinJ2 in psoriasis models.

MAIN OUTCOME MEASURES

Investigator-determined clinical results in patients and cell counts and histological evidence in models.

RESULTS

All patients' psoriasis improved substantially during troglitazone therapy. Peroxisome proliferator-activated receptor-gamma was expressed in human keratinocytes; ligands for PPARgamma inhibited the proliferation of normal and psoriatic human keratinocytes in culture. Troglitazone treatment normalized the histological features of psoriatic skin in organ culture and reduced the epidermal hyperplasia of psoriasis in the severe combined immunodeficient mouse and human skin transplant model of psoriasis (P<.05 compared with untreated controls).

CONCLUSIONS

Peroxisome proliferator-activated receptor-gamma might be a useful intracellular target for the treatment of psoriasis; further study is needed to assess the clinical value of ligands for PPARgamma, including troglitazone.

Collagenolytic and gelatinolytic matrix metalloproteinases and their inhibitors in basal cell carcinoma of skin: comparison with normal skin

Tissue from 54 histologically-identified basal cell carcinomas of the skin was obtained at surgery and assayed using a combination of functional and immunochemical procedures for matrix metalloproteinases (MMPs) with collagenolytic activity and for MMPs with gelatinolytic activity. Collagenolytic enzymes included MMP-1 (interstitial collagenase), MMP-8 (neutrophil collagenase) and MMP-13 (collagenase-3). Gelatinolytic enzymes included MMP-2 (72-kDa gelatinase A/type IV collagenase) and MMP-9 (92-kDa gelatinase B/type IV collagenase). Inhibitors of MMP activity including tissue inhibitor of metalloproteinases-1 and -2 (TIMP-1 and TIMP-2) were also assessed. All three collagenases and both gelatinases were detected immunochemically. MMP-1 appeared to be responsible for most of the functional collagenolytic activity while gelatinolytic activity reflected both MMP-2 and MMP-9. MMP inhibitor activity was also present, and appeared, based on immunochemical procedures, to reflect the presence of TIMP-1 but not TIMP-2. As a group, tumours identified as having aggressive-growth histologic patterns were not distinguishable from basal cell carcinomas with less aggressive-growth histologic patterns. In normal skin, the same MMPs were detected by immunochemical means. However, only low to undetectable levels of collagenolytic and gelatinolytic activities were present. In contrast, MMP inhibitor activity was comparable to that seen in tumour tissue. In previous studies we have shown that exposure of normal skin to epidermal growth factor in organ culture induces MMP up-regulation and activation. This treatment concomitantly induces stromal invasion by the epithelium (Varani et al (1995) Am J Pathol 146: 210-217; Zeigler et al (1996b) Invasion Metastasis 16: 11-18). Taken together with these previous data, the present findings allow us to conclude that the same profile of MMP/MMP inhibitors that is associated with stromal invasion in the organ culture model is expressed endogenously in basal cell carcinomas of skin.

Phosphorylation controls timing of Cdc6p destruction: A biochemical analysis

The replication initiation protein Cdc6p forms a tight complex with Cdc28p, specifically with forms of the kinase that are competent to promote replication initiation. We now show that potential sites of Cdc28 phosphorylation in Cdc6p are required for the regulated destruction of Cdc6p that has been shown to occur during the Saccharomyces cerevisiae cell cycle. Analysis of Cdc6p phosphorylation site mutants and of the requirement for Cdc28p in an in vitro ubiquitination system suggests that targeting of Cdc6p for degradation is more complex than previously proposed. First, phosphorylation of N-terminal sites targets Cdc6p for polyubiquitination probably, as expected, through promoting interaction with Cdc4p, an F box protein involved in substrate recognition by the Skp1-Cdc53-F-box protein (SCF) ubiquitin ligase. However, in addition, mutation of a single, C-terminal site stabilizes Cdc6p in G2 phase cells without affecting substrate recognition by SCF in vitro, demonstrating a second and novel requirement for specific phosphorylation in degradation of Cdc6p. SCF-Cdc4p- and N-terminal phosphorylation site-dependent ubiquitination appears to be mediated preferentially by Clbp/Cdc28p complexes rather than by Clnp/Cdc28ps, suggesting a way in which phosphorylation of Cdc6p might control the timing of its degradation at then end of G1 phase of the cell cycle. The stable cdc6 mutants show no apparent replication defects in wild-type strains. However, stabilization through mutation of three N-terminal phosphorylation sites or of the single C-terminal phosphorylation site leads to dominant lethality when combined with certain mutations in the anaphase-promoting complex.

Role of ERK and JNK pathways in regulating cell motility and matrix metalloproteinase 9 production in growth factor-stimulated human epidermal keratinocytes

Invasion is an essential cellular response that plays an important role in a number of physiological and pathological processes. Matrix metalloproteinase (MMP) production and cell movement are diverse cellular responses integral to the process of invasion. The complexity of the invasive process suggests the necessity of coordinate activation of more than one signaling pathway in order to activate specific factors responsible for regulating these cellular responses. In this report, we demonstrate that cell movement and MMP-9 production are both directly dependent on the activation of endogenous ERK signaling in hepatocyte growth factor (HGF)-or epidermal growth factor (EGF)-stimulated human epidermal keratinocytes. The kinetic profiles of endogenous MEK and ERK activity suggest that prolonged activation of these signal transducers is an underlying mechanism involved in stimulating cell motility and MMP-9 production. In support of this finding, a transient MEK/ERK signal elicited by keratinocyte growth factor (KGF) or insulin-like growth factor-1 (IGF-1) fails to stimulate these invasion-related responses. Specific inhibition of MEK leads to suppression of ERK activation, marked reduction in steady-state levels of c-Fos, and inhibition of cell movement and MMP-9 production. This occurs despite continued activation of JNK and c-Jun signaling in the presence of MEK-specific inhibition. In contrast, when JNK activity is specifically inhibited in HGF-stimulated cells, AP-1 activity is suppressed but cell motility is not affected. This evidence suggests that while ERK and JNK activity are necessary for AP-1 activation, ERK but not JNK is sufficient in stimulating cell motility.

Multiple valve replacement increases the risk of reoperation for structural degeneration of bioprostheses

BACKGROUND AND AIM OF THE STUDY

The study aim was to analyze the results of reoperations for structural degeneration of bioprostheses, and to define a high-risk population for reoperative procedures.

METHODS

A series of 524 consecutive patients who had undergone a first reoperative replacement for a failed bioprosthesis between 1978 and 1998 was reviewed retrospectively. The reoperative procedure comprised 363 single valve replacements, and 161 multiple valve replacements. During the original procedure, 648 bioprostheses had been implanted in the mitral (n = 403), aortic (n = 220) and tricuspid (n = 25) positions.

RESULTS

The mean interval between the original procedure and reoperation was 8.8 +/- 3.3 years. Tissue valve failure was revealed by recurrence of cardiac insufficiency in 70% of cases. The overall early mortality rate was 8%, but early mortality rates for elective single mitral and aortic reoperative valve replacements were only 3.9% and 4%, respectively. Early mortality following reoperation for single and multiple valve replacement was 6.0% and 12.4% respectively (p = 0.02). Other significant multivariable predictors for early mortality were old age (p = 0.003), NYHA functional class (p = 0.007), presence of ascites (p = 0.02) and reoperation performed before 1988 (p = 0.013).

CONCLUSIONS

The risk of reoperation for structural degeneration of bioprostheses is acceptable for elective single reoperative valve replacement as opposed to multiple reoperative valve replacement. This may limit the use of bioprostheses during the original procedure when multiple valve replacement is required.

Cdc53/cullin and the essential Hrt1 RING-H2 subunit of SCF define a ubiquitin ligase module that activates the E2 enzyme Cdc34

SCFCdc4 (Skp1, Cdc53/cullin, F-box protein) defines a family of modular ubiquitin ligases (E3s) that regulate diverse processes including cell cycle, immune response, and development. Mass spectrometric analysis of proteins copurifying with Cdc53 identified the RING-H2 finger protein Hrt1 as a subunit of SCF. Hrt1 shows striking similarity to the Apc11 subunit of anaphase-promoting complex. Conditional inactivation of hrt1(ts) results in stabilization of the SCFCdc4 substrates Sic1 and Cln2 and cell cycle arrest at G1/S. Hrt1 assembles into recombinant SCF complexes and individually binds Cdc4, Cdc53 and Cdc34, but not Skp1. Hrt1 stimulates the E3 activity of recombinant SCF potently and enables the reconstitution of Cln2 ubiquitination by recombinant SCFGrr1. Surprisingly, SCF and the Cdc53/Hrt1 subcomplex activate autoubiquitination of Cdc34 E2 enzyme by a mechanism that does not appear to require a reactive thiol. The highly conserved human HRT1 complements the lethality of hrt1Delta, and human HRT2 binds CUL-1. We conclude that Cdc53/Hrt1 comprise a highly conserved module that serves as the functional core of a broad variety of heteromeric ubiquitin ligases.

[Low-tensioned and "b"-like ileocystoplasty]

OBJECTIVE

To perfectly solve the urine-kept and urinary problems of the vesical cancer patients after vesicoectomy.

METHODS

We performed low-tensioned and "b"-like ileocystoplasty in 16 patients.

RESULTS

After the operation, new vesica urinaria worked well in keeping and emptying urine-urine through the urethra. Residual urine test, chemical test and urography showed that there were no disturbance of body water and electrolyte metetabolism, no reterograde urine in the ureter, no uracratia, and no damage to renal function.

CONCLUSIONS

Ileocystoplasty can be used clinically.

[Content variety of alisol B 23-acetate in Rhiozma Alismatis reaped at different time]

Alisol B 23-acetate in Rhizoma Alismatis reaped at different time was determinated by RP-HPLC. The result indicated that the content of those reaped in April is obviously higher than those reaped from Jan. to March.

Alterations in heart and kidney membrane phospholipids in hypertension as observed by 31P nuclear magnetic resonance

Abnormalities of phospholipids in hypertension have previously been described in human erythrocyte, platelet, and plasma lipoproteins. Since the heart and kidney are adversely affected by hypertension, we investigated possible alterations in their membrane phospholipids, which could play a role in the derangement of intracellular ion balance widely observed in hypertension. The phospholipid compositions of heart and kidney from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were determined by using 31P nuclear magnetic resonance (NMR) spectroscopy. Absolute contents of all phospholipids in hypertensive hearts and kidneys were significantly higher than in normotensive hearts and kidneys. Expressed as a fraction of total phospholipid, cardiolipin (CL) and phosphatidylethanolamine plasmalogen (PEp) were significantly increased in SHR hearts compared to WKY hearts (CL and PEp were 7.95+/-0.22% and 13.16+/-0.35% in SHR vs. 7.01+/-0.20% and 11.19+/-0.42% in WKY rats, P< or =0.05), but phosphatidylethanolamine (PE) and phosphatidylcholine (PC) were significantly decreased in SHR (PE and PC were 22.46+/-0.37% and 44.81+/-0.43% in SHR vs. 24.02+/-0.44% and 46.01+/-0.50% in WKY rats, P< or =0.05). In the phospholipids extracted from rat kidneys, the percentage of PE was significantly higher for SHR than for WKY rats (20.37+/-0.60% vs. 18.43+/-0.37%, P< or =0.05), while PEp and phosphatidylserine (PS) were significantly lower for SHR (PEp and PS were 10.22+/-0.36% and 8.42+/-0.28% in SHRs vs. 11.29+/-0.36% and 9.71+/-0.40% in WKY rats, P< or =0.05). The above alterations in phospholipid composition might contribute to the higher oxygen consumption in the hypertensive heart and abnormal intracellular ion concentrations and ion transport in the heart and the kidney in hypertension.

Alterations in membrane fatty acid unsaturation and chain length in hypertension as observed by 1H NMR spectroscopy

Alterations in fatty acids of membrane phospholipids in essential hypertension may account for altered membrane ion transport, elasticity, and contractility properties of hypertensive tissues. To investigate the abnormalities in membrane fatty acids in essential hypertension, the degree of fatty acid unsaturation ([-CH=CH-]/[-CH3]), the average carbon chain length, ratio of glycerol to fatty acyl chains, ratio of phosphatidylcholine to fatty acyl chains, and the ratio of free and acylated cholesterol to fatty acyl chains in fatty acid fractions of membrane phospholipids of aorta, kidney, and heart were determined in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats by 1H nuclear magnetic resonance (NMR) spectroscopy. The degrees of fatty acid unsaturation in the aorta and the kidney membranes were significantly lower in SHR than in WKY rats (aorta, 0.53+/-0.01 v 0.63+/-0.01, n = 5, P = .01; kidney, 0.70+/-0.01 v 0.84+/-0.03, n = 10, P = .01). No significant difference could be detected in fatty acid unsaturation in heart membranes between these two strains. For aorta, kidney, and heart membranes, the average carbon chain lengths of fatty acid fractions of membrane phospholipids were significantly shorter for SHR than for WKY rats (aorta, 15.1+/-0.2 v 18.3+/-0.7, n = 5, P = .02; kidney, 14.5+/-0.2 v 16.4+/-0.4, n = 10, P = .01; heart, 17.3+/-0.5 v 18.8+/-0.6, n = 10, P = .05). The lower unsaturated fatty acid content in membrane phospholipids of the aorta and the kidney, with concomitant reduction in average chain length, may arise from increased oxidation of fatty acid double bonds in hypertensive tissues and may account, in part, for the increased aortic stiffness and abnormal kidney function associated with essential hypertension. Whether the lower unsaturated fatty acid content and decreased carbon chain length of phospholipid membranes in the aorta and the kidney are a cause or a consequence of the high blood pressure, however, remains unknown.

Chronic nitric oxide inhibition with L-NAME: effects on autonomic control of the cardiovascular system

To determine whether increased sympathetic activity contributes to the hypertension induced by chronic exposure to moderate nitric oxide synthase (NOS) inhibition, various indexes of autonomic function were measured in rats given the NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/100 ml, approximately equal to 16 mg.kg-1.day-1) in the drinking water. One week of treatment raised blood pressure (139 +/- 3 vs. 106 +/- 1 mmHg; P < 0.01) and lowered heart rate (319 +/- 4 vs. 379 +/- 6 beats/min, P < 0.01). L-NAME had no effect on cardiac sympathetic tone, but elevated cardiac parasympathetic tone (-73 +/- 4 vs. -56 +/- 7 beats/min; P < 0.05). Depressor responses to ganglionic blockade were greater in L-NAME-treated rats (-50 +/- 5 vs. -34 +/- 5 mmHg; P < 0.05), whereas resting plasma, renal, and adrenal catecholamine values did not differ between groups. Treated rats also showed evidence of reduced baroreflex sympathetic stimulation of heart rate during hypotension and reduced parasympathetic activation during hypertension. Together, these data provide only very limited, indirect evidence that sympathetic stimulation contributes to the hypertension associated with moderate NOS inhibition.

A low rate of reinfection following effective therapy against Helicobacter pylori in a developing nation (China)

BACKGROUND & AIMS

In developed countries, reinfection after successful eradication of Helicobacter pylori appears unusual. High prevalences of H. pylori in developing countries may result in high reinfection rates. The aim of this study was to determine the rate of reinfection and ulcer recurrence in Chinese patients cured of H. pylori and duodenal ulcer disease.

METHODS

One hundred eighty-four patients with duodenal ulcer disease shown by endoscopic examination (1 month) and 14C-urea breath test (3 months) after termination of treatment to have cleared their H. pylori were investigated. Patients were followed up by endoscopy (12 and 24 months) and breath test (6, 9, 12, 18, and 24 months). H. pylori status at endoscopic examination was determined by rapid urease, histology, and culture. In reinfected patients, random amplification of polymorphic DNA fingerprinting was used to compare isolates before and after therapy.

RESULTS

Four patients were reinfected with H. pylori over 24 months (3 within 6 months and 1 at 24 months; average annual recurrence rate, 1.08%). Fingerprinting of isolates from 3 patients showed 1 patient (6 months) to have identical strains and the remainder to have nonidentical strains before and after treatment. Ulcer relapse occurred in 6 patients (4 H. pylori positive).

CONCLUSIONS

Reinfection with H. pylori is rare in developing countries where treatment is effective.

Phosphorylation- and ubiquitin-dependent degradation of the cyclin-dependent kinase inhibitor Far1p in budding yeast

Cyclin-dependent kinase inhibitors (CKIs) play key roles in controlling the eukaryotic cell cycle by coordinating cell proliferation and differentiation. Understanding the roles of CKIs requires knowledge of how they are regulated both through the cell cycle and in response to extracellular signals. Here we show that the yeast CKI, Far1p, is controlled by ubiquitin-dependent proteolysis. Wild-type Far1p was stable only in the G1 phase of the cell cycle. Biochemical and genetic evidence indicate that its degradation required the components of the G1-S ubiquitination system, Cdc34p, Cdc4p, Cdc53p, and Skp1p. We isolated a mutant form of Far1p (Far1p-22) that was able to induce cell cycle arrest in the absence of alpha-factor. Cells that overexpress Far1-22p arrested in G1 as large unbudded cells with low Cdc28p-Clnp kinase activity. Wild-type Far1p, but not Far1-22p, was readily ubiquitinated in vitro in a CDC34- and CDC4-dependent manner. Far1-22p harbors a single amino acid change, from serine to proline at residue 87, which alters phosphorylation by Cdc28p-Cln2p in vitro. Our results show that Far1p is regulated by ubiquitin-mediated proteolysis and suggest that phosphorylation of Far1p by the Cdc28p-Clnp kinase is part of the recognition signal for ubiquitination.

Na(+)-H+ and Na(+)-Li+ exchange are mediated by the same membrane transport protein in human red blood cells: an NMR investigation

Na(+)-H+ exchange is a transport system present in erythrocytes which plays an important role in the regulation of intracellular pH, cellular volume, and transmembrane ion transport. Na(+)-Li+ exchange has received much attention and has been investigated in more detail than have any of the other ion transport systems, because of its high reproducibility. Both red blood cell (RBC) Na(+)-H+ and Na(+)-Li+ exchange are elevated in essential hypertensive patients relative to normotensive individuals. RBC Na(+)-Li+ exchange may be a mode of operation of Na(+)-H+ exchange. Amiloride and its analogue, 5-(N,N-hexamethylene)amiloride (HMA), are well-known inhibitors of Na(+)-H+ exchange, whereas phloretin strongly inhibits Na(+)-Li+ exchange. In this study, we tested the effects of amiloride, HMA, and phloretin on Na(+)-Li+ exchange activity in intact RBCs by using atomic absorption. We investigated by using 7Li nuclear magnetic resonance (NMR) spectroscopy the effects of HMA and phloretin inhibition on Li+ efflux across resealed H(+)- and Li(+)-loaded RBC ghosts in the absence and presence of pH gradients. Amiloride inhibitory activities on both Na+ and Li+ binding to exposed RBC membranes under different pH conditions were also studied by 23Na and 7Li NMR relaxation time measurements. We found that Na(+)-Li+ exchange activity was inhibited by amiloride, HMA, and phloretin in suspensions of intact RBCs and of resealed RBC ghosts. Li+ efflux rates across resealed H(+)- and Li(+)-loaded RBC ghosts were significantly lower when a pH gradient was present, presumably because of the competition between Li+ and H+ for transport by the same transport protein. Amiloride had similar inhibitory constants on both Na+ and Li+ binding to RBC membranes (1021 +/- 48 M-1 vs 964 +/- 40 M-1 at pH 8.0; 731 +/- 147 M-1 vs 716 +/- 27 M-1 at pH 7.0). These results suggest that Na(+)-H+ exchange and Na(+)-Li+ exchange are mediated by the same RBC membrane transport protein.

Correlations of Na+-Li+ exchange activity with Na+ and Li+ binding and phospholipid composition in erythrocyte membranes of white hypertensive and normotensive individuals: a nuclear magnetic resonance investigation

Enhanced Na+-Li+ exchange activity has been reported in red blood cells (RBCs) of white patients with essential hypertension compared with RBCs of normotensive individuals. To understand the factors responsible for this finding, we applied novel and conventional spectroscopic and kinetic methods to blood samples from 10 hypertensive and 10 normotensive individuals. We measured the kinetic parameters (V std, V max, and K m) for RBC Na+-Li+ exchange by atomic absorption spectrophotometry and used 23Na and 7Li nuclear magnetic resonance relaxation methods to measure Na+ and Li+ binding to RBC membranes as well as 31P nuclear magnetic resonance spectroscopy to measure membrane phospholipid compositions. We found significant differences between the two groups for the affinity of Na+ for the RBC membrane (0.202 +/- 0.054 mmol/L-1 for hypertensive patients versus 0.296 +/- 0.071 mmol/L-1 for normotensive subjects, P<.005). The kinetic parameters of RBC Na+-Li+ exchange (V std, V max, and K m) were 0.32 +/- 0.09 and 0.66 +/- 0.17 mmol Li+/L cell.h and 160 +/- 62 mmol/L, respectively, for hypertensive patients versus 0.21 +/- 0.06 and 0.32 +/- 0.14 mmol Li+/L cell.h and 86 +/- 69 mmol/L for normotensive subjects (P<.05). The fractions of phosphatidylserine and phosphatidylethanolamine were 0.153 +/- 0.009 and 0.294 +/- 0.016 for hypertensive patients versus 0.138 +/- 0.013 and 0.325 +/- 0.018 for normotensive subjects (P<.05). The Na+ binding constants were negatively correlated with the Km values for both the hypertensive (r=-.61, P=.01) and normotensive (r=-.43, P=.04) groups. Changes in lipid-protein interactions in the RBC membranes of hypertensive patients appear to be responsible for weaker Na+ binding to the membrane and for the faster rates of RBC Na+-Li+ exchange.