Rheumatoid arthritis associated with myelodysplastic syndrome: a case report

Myelodysplastic syndromes (MDS) are a group of refractory anemias resulting from a clonal stem cell disorder often associated with cytogenetic abnormalities. There is increasing recognition of immunological abnormalities in patients with MDS, including defective B- and T-cell function, hyper- or hypogammaglobulinemia and monoclonal gammopathy. MDS have been associated with Sjögren's syndrome, polymyalgia rheumatica, relapsing polychondritis and systemic lupus erythematosus. Although there may be various rheumatologic features, including acute arthritis in MDS, chronic inflammatory arthritis is uncommonly combined. There have been a few reports that described cases of rheumatoid arthritis (RA) concurrent with MDS, but advanced rheumatoid arthritis with typical joint deformities has rarely been reported. We report a case of rheumatoid arthritis with atlantoaxial subluxation combined with refractory anemia in a 31-year-old woman.

Mechanical loading of bovine pericardium accelerates enzymatic degradation

Bioprosthetic heart valves fail as the result of two simultaneous processes: structural deterioration and calcification. Leaflet deterioration and perforation have been correlated with regions of highest stress in the tissue. The failures have long been assumed to be due to simple mechanical fatigue of the collagen fibre architecture; however, we have hypothesized that local stresses-and particularly dynamic stresses-accelerate local proteolysis, leading to tissue failure. This study addresses that hypothesis. Using a novel, custom-built microtensile culture system, strips of bovine pericardium were subjected to static and dynamic loads while being exposed to solutions of microbial collagenase or trypsin (a non-specific proteolytic enzyme). The time to extend to 30% strain (defined here as time to failure) was recorded. After failure, the percentage of collagen solubilized was calculated based on the amount of hydroxyproline present in solution. All data were analyzed by analysis of variance (ANOVA). In collagenase, exposure to static load significantly decreased the time to failure (P < 0.002) due to increased mean rate of collagen solubilization. Importantly, specimens exposed to collagenase and dynamic load failed faster than those exposed to collagenase under the same average static load (P = 0.02). In trypsin, by contrast, static load never led to failure and produced only minimal degradation. Under dynamic load, however, specimens exposed to collagenase, trypsin, and even Tris/CaCl2 buffer solution, all failed. Only samples exposed to Hanks' physiological solution did not fail. Failure of the specimens exposed to trypsin and Tris/CaCl2 suggests that the non-collagenous components and the calcium-dependent proteolytic enzymes present in pericardial tissue may play roles in the pathogenesis of bioprosthetic heart valve degeneration.

Utility of the resistance index ratio in differentiating obstructive from nonobstructive hydronephrosis in children

PURPOSE

We assessed the utility of the resistance index ratio (RIR) in distinguishing between obstructive and nonobstructive upper urinary tract dilatation in children.

METHODS

Twenty-three children (7 days-14 years old) with unilateral dilated collecting systems and a contralateral normal kidney were prospectively evaluated by duplex Doppler sonography. We measured the resistance index (RI) of the intrarenal arteries and calculated the RIR. Ninety-six normal kidneys in 48 controls were also evaluated.

RESULTS

Twelve kidneys were proved to be obstructed at the ureteropelvic junction, and 11 were found by renal scintigraphy with furosemide and/or by surgery to have nonobstructive dilatation. The mean RIR differed significantly between the obstructed and dilated nonobstructed kidneys (1.16+/-0.04 versus 1.04+/-0.04, respectively; p < 0.01). After surgical correction of ureteropelvic junction obstruction, the obstructed kidneys showed significant drops in the RIR (1.18+/-0.03 to 1.07+/-0.03, p < 0.01). The RIR showed no statistically significant relationship with age (r = -0.268, p > 0.01); however, the RI declined with increasing age (r= -0.414, p < 0.01). An RIR cut-off value of > or = 1.10 provided a good discriminatory level, resulting in a sensitivity of 92%, a specificity of 97%, a positive predictive value of 85%, and a negative predictive value of 97%.

CONCLUSIONS

An RIR cut-off value of > or = 1.10 appears to be an effective parameter for evaluation and follow-up of unilateral obstructive hydronephrosis in children.

Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow

PURPOSE

To find any differential magnetic resonance (MR) imaging findings between septic arthritis and transient synovitis in pediatric patients.

MATERIALS AND METHODS

The MR imaging findings in nine pediatric patients with septic arthritis and 14 with transient synovitis were retrospectively studied. The diagnoses were made by means of joint aspiration with bacteriologic study, arthrotomy, and clinical evaluation. MR imaging findings were analyzed with emphasis on the grade of joint effusion and alterations in signal intensity in the soft tissue and bone marrow of the affected hip joint.

RESULTS

Signal intensity alterations in bone marrow (i.e., low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted spin-echo images and high signal intensity on fat-suppressed T2-weighted fast spin-echo images) were seen in eight of nine patients with septic arthritis. These signal intensity alterations consisted of mild juxtaarticular changes in six patients without osteomyelitis and extensive changes in the femoral head and neck in two patients with coexistent osteomyelitis. Signal intensity alterations in bone marrow were not seen in the 14 patients with transient synovitis.

CONCLUSION

Signal intensity alterations in the bone marrow of the affected hip joint are useful in the differentiation of septic arthritis from transient synovitis.

Treatment options for Helicobacter pylori infection when proton pump inhibitor-based triple therapy fails in clinical practice

BACKGROUND

The effectiveness of Helicobacter pylori eradication regimens has not been extensively investigated in the clinical practice setting. The optimal treatment choice after an initial failed eradication attempt has not been determined.

AIMS

To evaluate proton pump inhibitor-based triple therapies as first-line eradication regimens in clinical practice, and to establish the efficacy of second-line regimens in the context of an initial failed eradication attempt.

METHODS

Three hundred and eight patients with dyspepsia and evidence of H. pylori at endoscopy were recruited. As first-line therapy, 116 patients received omeprazole 20 mg b.d. in combination with amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. (OAC) while 192 patients received omeprazole 20 mg b.d. in combination with metronidazole 400 mg b.d. and clarithromycin 250 mg b.d. (OMC). H. pylori status was reassessed at least 4 weeks after therapy (25 patients failed to attend for further testing). Of 52 patients with an initial failed eradication attempt, 20 patients received a 1 week quadruple therapy regimen incorporating omeprazole 20 mg b.d., tripotassium dicitrato bismuthate 120 mg q.d.s., tetracycline 500 mg q.d.s. and metronidazole 400 mg t.d.s., 20 patients received a 2-week proton pump inhibitor-based triple therapy regimen as described, and 12 patients received a further 1-week proton pump inhibitor-based triple therapy regimen.

RESULTS

Including 308 patients, the intention-to-treat (ITT) eradication rates for OAC and OMC as first-line regimens were 72% (95% CI: 63-80%) and 73% (95% CI: 67-79%) respectively. A per protocol (PP) analysis on the 283 patients who completed follow-up gives an initial eradication rate of 78% (95% CI: 69-86%) for OAC and 79% (95% CI: 73-85%) for OMC. There were 60 patients (21%; 95% CI: 17-26%) in whom the initial eradication attempt was unsuccessful. With second-line therapy, H. pylori was successfully eradicated in a further 35/52 (67%; 95% CI: 58-73%) patients. The eradication rates with the quadruple regimen and 2-week triple therapy regimens were 75% (95% CI: 56-94%) and 80% (95% CI: 63-98%) respectively (P = 0. 71). The eradication rate with a repeat 1-week regimen was 33% (95% CI: 7-60%).

CONCLUSIONS

The eradication rates achieved in this 'in practice' study with recommended first-line 1-week proton pump inhibitor-based triple therapy regimens were lower than the rates achieved with similar regimens in the clinical trial setting. A repeat 1-week proton pump inhibitor-based triple therapy regimen was not successful as a salvage therapy. Both the 2-week proton pump inhibitor-based triple therapy regimen and the 1-week quadruple therapy regimen were successful second-line treatments in >/=75% of patients.

p53 regulates a G2 checkpoint through cyclin B1

The p53 tumor suppressor controls multiple cell cycle checkpoints regulating the mammalian response to DNA damage. To identify the mechanism by which p53 regulates G2, we have derived a human ovarian cell that undergoes p53-dependent G2 arrest at 32 degrees C. We have found that p53 prevents G2/M transition by decreasing intracellular levels of cyclin B1 protein and attenuating the activity of the cyclin B1 promoter. Cyclin B1 is the regulatory subunit of the cdc2 kinase and is a protein required for mitotic initiation. The ability of p53 to control mitotic initiation by regulating intracellular cyclin B1 levels suggests that the cyclin B-dependent G2 checkpoint has a role in preventing neoplastic transformation.

Acute vasorelaxant effects of metformin and attenuation by stimulation of sympathetic agonist release

We recently discovered 1) that intravenous injection of the antidiabetic drug metformin in the rat rapidly reduces arterial pressure elevations maintained by the alpha-adrenoceptor agonist phenylephrine (PE) and 2) that direct administration of metformin to isolated rat tail arterial tissue rings rapidly relaxes PE-induced contractions. To further characterize this potential direct vasodilator action, we examined effects of metformin on contractions induced not only by PE but also by norepinephrine (NE) and by nonadrenergic agonists (5-hydroxytryptamine, 5HT; arginine vasopressin, AVP). Also, because the rat tail artery contains abundant adrenergic nerve endings we conducted these tests not only in arterial rings with nerve endings intact but in rings in which they had been removed by pretreatment with 6-hydroxydopamine. In intact rings, metformin at levels from approximately 0.2 to 20 mmol/L rapidly relaxed half-maximal contractions induced by PE and NE similarly and to a markedly greater degree than contractions induced by 5-HT (p<0.05). Metformin did not relax AVP-induced contractions. In addition, removal of adrenergic nerve endings facilitated metformin's relaxant effects (p<0.05). Thus, the acute vasodilator action of metformin appears 1) to be selectively more powerful on arterial smooth muscle contractions induced adrenergically versus nonadrenergically and 2) to be buffered by a possible metformin-induced release of endogenous NE from adrenergic nerve endings. Such results were not seen during relaxation produced by either the calcium channel inhibitor nifedipine or the nitrovasodilator nitroprusside suggesting that metformin's effects are mediated by other mechanisms.

Molecular analysis of HLA-DR gene expression induced by IFN-gamma in malignant melanoma cell lines

Human leukocyte antigen (HLA) class II molecules are polymorphic cell surface glycoproteins that are crucial for the cellular interaction in immune response. The expression of class II molecules is regulated in a tissue-specific and cytokine-inducible manner, and is mainly restricted to the antigen presenting cells. However, some tumor cells also express class II molecules, and in some class-II-negative tumor cells, class II expression is inducible by interferon (IFN)-gamma. However, their expression varies, even though the tumor cells originate from the same histological origin; some tumor cells show strong expression, others show weak or no expression. To determine whether this differential expression of class II molecules on tumor cells is transcriptionally regulated, FACS analysis and Northern hybridization were performed using a panel of melanoma cell lines, IGR3, Malme-3M, SK-Mel-24, and SK-Mel-28 to analyze the cell surface expression and mRNA transcription rate of HLA-DR before and after treatment with IFN-gamma. FACS analysis showed that before IFN-gamma treatment, IGR3 and Malme-3M cells barely expressed HLA-DR. On the contrary, almost all of the SK-Mel-24 cells (> 90%) and a relatively high rate (> 50%) of SK-Mel-28 cells expressed HLA-DR. After IFN-gamma treatment, HLA-DR expression was induced in Malme-3M cells and SK-Mel-28 cells which displayed elevated levels of HLA-DR expression in a time-dependent manner. However, IGR3 cells never responded to IFN-gamma. Northern analysis showed that treatment with IFN-gamma led to the steady-state mRNA augmentation of the HLA-DR gene in Malme-3M and SK-Mel-28, whereas in IGR3, IFN-gamma did not augment the transcriptional rate of the HLA-DR gene. To further clarify this differential modulation, sequencing analysis of PCR product of the HLA-DR proximal promoter region was done, since the transcription rate of the class II gene is controlled by the well-conserved proximal promoter region. Six independent clones from PCR products of the HLA-DRA proximal promoter region and 16 clones from PCR products of the HLA-DRB proximal promoter region were isolated from the above cell lines and sequenced. Comparison of the nucleotide sequences of all 6 clones of DRA promoter showed that the sequences are extremely similar in both regulatory sequences and their intervening sequences. Sixteen clones of HLA-DRB promoter showed sequence variations such as substitution and insertion/deletion, and these 16 clones could be further grouped into 6 homologues with sequence homology. These data established that the melanoma cell lines studied here showed a differential susceptibility to IFN-gamma on the modulation of HLA-DR molecules, that this modulation is transcriptionally regulated, and that the difference in promoter activity by sequence variation might contribute to such a differential transcriptional regulation at the promoter level.

The EEG and prognosis in status epilepticus

PURPOSE

To examine the relation between specific EEG features and clinical outcome, determine whether a predictable sequence of EEG patterns exists during status epilepticus (SE), and examine the relation between periodic epileptiform discharges (PEDs) and SE.

METHODS

EEG records of 50 patients with SE admitted to Graduate Hospital between January 1990 and July 1995 were reviewed. Ictal EEGs were available in 72%; 28% had only postictal EEGs. Poor outcome was defined as death or persistent vegetative state, and good outcome as all others. Fisher's Exact test, chi2, and t tests were performed for data analysis.

RESULTS

Of 50 patients, 72% had a good outcome and 28%, a poor outcome. If PEDs were present at any time during or after SE, outcome tended to be worse (p = 0.053). With PEDs, eight (44%) of 18 had a poor outcome; without PEDs, six (19%) of 32 had a poor outcome. Etiologies for SE did not substantially differ in patients with or without PEDs, and structural abnormalities were not more associated with the presence of PEDs. PEDs were seen both early and late, during and after SE. Other EEG characteristics (lateralized vs. bilateral symmetric ictal EEG, discrete vs. continuous ictal activity, and postictal focal slowing) did not relate to outcome. No predictable sequence of EEG changes was found during SE.

CONCLUSIONS

PEDs are the only EEG feature related to outcome in SE and are associated with poor outcome independent of etiology.

Error analysis of a direct current electromagnetic tracking system in digitizing 3-dimensional surface geometries

The direct current electromagnetic tracking device has seen increasing use in biomechanics studies of joint kinematics and anatomical surface geometry. In these applications, a stylus is attached to a sensor to measure the spatial location of three-dimensional landmarks. Stylus calibration is performed by rotating the stylus about a fixed point in space and using regression analysis to determine the tip offset vector. Measurement errors can be induced via several pathways, including; intrinsic system errors in sensor position or angle and tip offset calibration errors. A detailed study was performed to determine the errors introduced in digitizing small surfaces with different stylus lengths (35, 55, and 65 mm) and approach angles (30 and 45 degrees) using a plastic calibration board and hemispherical models. Two-point discrimination errors increased to an average of 1.93 mm for a 254 mm step size. Rotation about a single point produced mean errors of 0.44 to 1.18 mm. Statistically significant differences in error were observed with increasing approach angles (p < 0.001). Errors of less than 6% were observed in determining the curvature of a 19 mm hemisphere. This study demonstrates that the "Flock of Birds" can be used as a digitizing tool with accuracy better than 0.76% over 254 mm step sizes.

Age and species-dependent differences in the neurokinin B system in rat and human brain

Neurokinin B and its cognate neurokinin-3 receptor are expressed more in the forebrain than in brain stem structures but little is known about the primary function of this peptide system in the central processing of information. In general, few studies have specifically addressed age-related changes of tachykinins, notably the changes in number and/or distribution of the neurokinin B-expressing and neurokinin-3 receptor-bearing neurons. Data on functions and changes of neurokinins in physiological aging are limited and apply mainly to the substance P/neurokinin-1 receptor system. In the present study, we analyzed neurokinin B/neurokinin-3 receptor system in young (5 months) versus middle aged (15 months) and old rats (23-25 months) and also in aging human brains. For the majority of the immunohistochemically examined regions of the rat brain, there was no statistically significant change in neuronal number and size of the neurokinin B and neurokinin-3 receptor staining. In the adult human brain, there was no age-associated change of the number or size of neurokinin-B-positive neurons. However, we found a major decline in number of neurokinin-3 receptor-expressing neurons between young/middle aged (30 years to 69 years) versus old (70 years and older) adults. Interestingly, numbers of neurokinin-3 receptor-positive microglia increased whereas the neurokinin-3 receptor-positive astrocytes remained unchanged in both aging rat and human brains. Finally, in addition to assessing the morphological and quantitative changes of the neurokinin B/neurokinin-3 receptor system in the rat and human brain, we discuss functional implications of the observed interspecies differences.

Biaxial mechanical/structural effects of equibiaxial strain during crosslinking of bovine pericardial xenograft materials

We have investigated the effect of biaxial constraint during glutaraldehyde crosslinking on the equibiaxial mechanical properties of bovine pericardium. Crosslinking of cruciate samples was carried out with: (i) no applied load, (ii) an initial 25 g ( approximately 30 kPa) equibiaxial load, or (iii) an initial 200 g (approximately 250 kPa) equibiaxial load. All loading during crosslinking was done under a defined initial equibiaxial load and subsequently fixed biaxial strain. Load changes during crosslinking were monitored. Mechanical testing and constraint during crosslinking were carried out in a custom-built biaxial servo-hydraulic testing system incorporating four actuators with phase-controlled waveform synthesis, high frame-rate video dimension analysis, and computer-interfaced data acquisition. The paired biaxial stress strain responses under equibiaxial loading at 1 Hz (before and after treatment) were evaluated for changes in anisotropic extensibility by calculation of an anisotropy index. Scanning electron microscopy (SEM) was performed on freeze-fractured samples to relate collagen crimp morphology to constraint during crosslinking. Fresh tissue was markedly anisotropic with the base-to-apex direction of the pericardium being less extensible and stiffer than the circumferential direction. After unconstrained crosslinking, the extensibility in the circumferential direction, the stiffness in the base-to-apex direction, and the tissue's anisotropy were all reduced. Anisotropy was preserved in the tissue treated with an applied 25 g load; however, tissue treated with an applied 200 g load became extremely stiff and nearly isotropic. SEM micrographs correlated well with observed extensibility in that the collagen fibre morphology changed from very crimped (unconstrained crosslinking), to straight (200 g applied load). Biaxial stress-fixation may allow engineering of bioprosthetic materials for specific medical applications.

New experimental and computational approaches to the analysis of gene expression

Public and private EST (Expressed Sequence Tag) programs provide access to a large number of ESTs from a number of plant species, including Arabidopsis, corn, soybean, rice, wheat. In addition to the homology of each EST to genes in GenBank, information about homology to all other ESTs in the data base can be obtained. To estimate expression levels of genes represented in the DuPont EST data base we count the number of times each gene has been seen in different cDNA libraries, from different tissues, developmental stages or induction conditions. This quantitation of message levels is quite accurate for highly expressed messages and, unlike conventional Northern blots, allows comparison of expression levels between different genes. Lists of most highly expresses genes in different libraries can be compiled. Also, if EST data is available for cDNA libraries derived from different developmental stages, gene expression profiles across development can be assembled. We present an example of such a profile for soybean seed development. Gene expression data obtained from Electronic Northern analysis can be confirmed and extended beyond the realm of highly expressed genes by using high density DNA arrays. The ESTs identified as interesting can be arrayed on nylon or glass and probed with total labeled cDNA first strand from the tissue of interest. Two-color fluorescent labeling allows accurate mRNA ratio measurements. We are currently using the DNA array technology to study chemical induction of gene expression and the biosynthesis of oil, carbohydrate and protein in developing seeds.

Chaotic and periodic heart rate dynamics in uncomplicated intrauterine growth restricted fetuses

We studied how chaotic and periodic heart rate dynamics differ between normal fetuses (n = 192) and uncomplicated intrauterine growth restricted fetuses (n = 86), aged 31-42 weeks of gestation. We analyzed each fetal heart rate time series for 25 min. We quantified the chaotic dynamics of each fetal heart rate time series by correlation dimension. The periodic dynamics were analyzed by power spectral analysis. The correlation dimension and, therefore, the complexity, of the heart rate dynamics of the uncomplicated intrauterine growth restricted fetuses was significantly lower than that of the normal fetuses, which was marked at 38-42 weeks of gestation. The low-frequency (0.04-0.15 Hz) component and, therefore, the periodicity of the low-frequency range was significantly higher than that of the normal fetuses during all the gestational weeks. These results mean that, although the intrauterine growth restricted fetuses are not severely compromised, the overall integrity of their cardiovascular control is impaired, especially at term; and sympathetic modulation is increased, both of which may contribute to increased perinatal mortality.

Epstein-Barr virus infection and its gene expression in gastric lymphoma of mucosa-associated lymphoid tissue

The role of Epstein-Barr virus (EBV) in the pathogenesis of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) has not been well understood. The aim of the study was to investigate EBV infection and its gene expression in this tumor in order to understand its role in the pathogenesis. EBV infection was screened by in situ hybridization for EBV-encoded non-polyadenylated RNA (EBER ISH) in 79 cases of gastric MALT lymphoma of nonimmunocompromised patients. The expression of EBV proteins [LMP1 (latent membrane protein 1), EBNA2 (EBV nuclear antigen 2), ZEBRA (switch protein encoded by BZLF1 gene)] was studied by immunohistochemistry in EBER-positive cases. EBV was detected with EBER ISH in 15 (19%) of the 79 cases. EBV was found in virtually all tumor cells in 2 cases of high-grade MALT lymphoma (2.5%) (EBV-associated), and was found only in occasional large or small lymphoid cells in 13 cases (16.5%). False positive EBER signal was detected in the mucinous glandular epithelial cells of gastric antrum with FITC-labeled oligonucleotide probe but not with digoxigenin or 35S-labeled riboprobes. Type II latency (EBER+LMP1+ EBNA2-) was detected in both EBV-associated cases. Type III latency (EBER+LMP1+EBNA2+) was also identified in one EBV-associated case besides latency II. Double labeling showed coexpression of LMP1 and EBNA2 in a small number of tumor cells, indicating the presence of type III latency in single cell level. In cases with only occasional EBER-positive large or small lymphoid cells, LMP1 and EBNA2 were not detected. ZEBRA was negative in all the cases. These findings suggest that EBV may contribute to the pathogenesis of a small proportion of high-grade MALT lymphoma, where virtually all tumor cells harbored EBV and the oncogenic viral protein LMP1 was expressed. Moreover, latency III of EBV infection may exist in nonimmunocompromised patient.

Increased glyceraldehyde-3-phosphate dehydrogenase gene expression in human cervical cancers

OBJECTIVE

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a classical glycolytic protein. A higher level of GAPDH mRNA was found in lung, pancreas, and prostate cancers, but in cervical carcinoma there have not been any reports about the level of GAPDH gene expression. So, we tried to investigate the GAPDH gene expression patterns in cervical carcinomas compared to normal cervical tissues, and the relationships between the expression levels of this gene and conventional clinicopathological parameters were evaluated.

MATERIALS AND METHODS

In this study, 25 normal exocervical tissues, 35 primary untreated cervical cancer tissues, 2 cervical cancer cell lines, and 2 post-nude-mouse-derived cervical cancer cell lines were subjected to Northern blot analyses for GAPDH gene expression.

RESULTS

Northern blot analyses revealed that the levels of GAPDH gene expression were elevated in 34 of 35 (97%) cervical carcinoma tissues and all of the 4 cervical cancer cell lines compared to normal cervical tissues. The levels of GAPDH gene expression were more prominent in rapidly proliferating cervical carcinoma cells. The levels of the GAPDH gene expressions in cervical cancer tissues were not associated with conventional clinicopathological parameters including clinical stage, histological type, and degree of differentiation.

CONCLUSION

These results suggest that increased GAPDH gene expression is characteristic of human cervical carcinomas and that rapidly proliferating carcinoma cells express more enhanced GAPDH gene. Future gene therapy using antisense oligodeoxynucleotide directed against GAPDH mRNA might be another therapeutic tool for human uterine cervical carcinoma.

Thermomechanical analysis of collagen crosslinking in the developing ovine thoracic aorta

We have used hydrothermal isometric tension (HIT) techniques in a sheep model to assess collagen crosslink stability and its contribution to the mechanical properties of the ovine thoracic aorta during perinatal and postnatal development. Aortic tissue was studied from fetal sheep, lambs, and adult sheep. Strips of tissue were loaded under isometric tension and heated to a 90 degrees C isotherm which was sustained for 3 hours. The decrease in load at this temperature is associated with collagen peptide bond hydrolysis and chain slippage, and the rate of this decrease is an inverse indicator of collagen crosslinking. The half-time of load decay (t1/2) was computed before and after tissue was treated with NaBH4 which stabilizes immature, reducible crosslinks. We observed a two-fold increase in t1/2 of untreated tissue from the lamb to the adult, indicating that aortic collagen crosslinking increased during postnatal development. Furthermore, the t1/2 of NaBH4-stabilized lamb tissue was similar to that of the untreated adult tissue, suggesting that much of the immature crosslinking in the lamb is stabilized during postnatal development. These observations suggest (a) increased crosslinking occurs during postnatal development and (b) that this increase is largely due to a conversion of immature crosslinks into their mature heat stable form.

Antitumor activity of 7-[2-(N-isopropylamino)ethyl]-(20S)-camptothecin, CKD602, as a potent DNA topoisomerase I inhibitor

We developed a novel water-soluble camptothecin analogue, CKD602, and evaluated the inhibition of topoisomerase I and the antitumor activities against mammalian tumor cells and human tumor xenografts. CKD602 was a nanomolar inhibitor of the topoisomerase I enzyme in the cleavable complex assay. CKD602 was found to be 3 times and slightly more potent than topotecan and camptothecin as inhibitors of topoisomerase, respectively. In tumor cell cytotoxicity, CKD602 was more potent than topotecan in 14 out of 26 human cancer cell lines tested, while it was comparable to camptothecin. CKD602 was tested for the in vivo antitumor activity against the human tumor xenograft models. CKD602 was able to induce regression of established HT-29, WIDR and CX-1 colon tumors, LX-1 lung tumor, MX-1 breast tumor and SKOV-3 ovarian tumor as much as 80, 94, 76, 67, 87% and 88%, respectively, with comparable body weight changes to those of topotecan. Also the therapeutic margin (R/Emax: maximum tolerance dose/ED58) of CKD602 was significantly higher than that of topotecan by 4 times. Efficacy was determined at the maximal tolerated dose levels using schedule dependent i.p. administration in mice bearing L1210 leukemia. On a Q4dx4 (every 4 day for 4 doses) schedule, the maximum tolerated dose (MTD) was 25 mg/kg per administration, which caused great weight loss and lethality in < 5% tumor bearing mouse. This schedule brought significant increase in life span (ILS), 212%, with 33% of long-term survivals. The ex vivo antitumor activity of CKD602 was compared with that of topotecan and the mean antitumor index (ATI) values recorded for CKD602 were significantly higher than that noted for topotecan. From these results, CKD602 warrants further clinical investigations as a potent inhibitor of topoisomerase I.

Inhibition of p53-dependent apoptosis by the KIT tyrosine kinase: regulation of mitochondrial permeability transition and reactive oxygen species generation

The KIT protein is a receptor tyrosine kinase of the platelet derived growth factor (PDGF) receptor family which regulates haematopoiesis, melanogenesis and gut and germ cell development. KIT regulates these diverse processes, at least in part, by inhibiting apoptosis. We have previously found that KIT can suppress p53-mediated apoptosis. The mechanism by which KIT suppresses apoptosis is, however, uncharacterized. Neither is it clear how p53 induces apoptosis. In this report we find that p53-dependent apoptosis proceeds through a pathway involving depolarization of the mitochondrial electropotential gradient (delta(psi)m) and the generation of reactive oxygen species (ROS). KIT activation suppresses p53-induced apoptosis in the mouse DP16 Friend erythroleukemia cell line by preventing delta(psi)m depolarization and ROS generation. Thus, the KIT kinase prevents apoptosis by regulating mitochondrial function and cellular redox state.