Small nucleolar RNP scleroderma autoantigens associate with phosphorylated serine/arginine splicing factors during apoptosis

OBJECTIVE

Proteins that are phosphorylated during apoptosis are commonly precipitated by autoantibodies found in the sera of patients with systemic lupus erythematosus. We sought to determine whether scleroderma autoantigens such as small nucleolar RNPs (snoRNP) also associate with phosphoproteins in response to various cellular stressors.

METHODS

We screened a panel of monoclonal antibodies derived from mice exposed to mercury, a well-characterized murine model of the anti-snoRNP autoimmune response, for the ability to selectively precipitate phosphoproteins from radiolabeled lysates prepared from Jurkat T cells subjected to stressful stimuli.

RESULTS

Monoclonal antibodies reactive with snoRNPs precipitated a phosphoprotein complex (pp42, pp34, and pp23) from lysates prepared from apoptotic cells. Several novel phosphoproteins (pp62 and pp18) were also observed. The phosphorylation and/or recruitment of these proteins to the snoRNP complex is induced by multiple apoptotic stimuli (e.g., Fas ligation, anisomycin, or ultraviolet irradiation), an effect that is blocked by overexpression of Bcl-2. We were unable to demonstrate an association of the phosphoprotein complex with snoRNPs in cells treated with the xenobiotic agent mercury. The snoRNP-associated phosphoprotein complex is composed of serine/arginine (SR) splicing factors, including SRp40.

CONCLUSION

The association of phosphorylated SR proteins with snoRNPs in cells undergoing apoptosis suggests that the immune response to fibrillarin that characterizes a subset of patients with scleroderma may be related to cell death induced by apoptotic stimuli (e.g., Fas ligation, irradiation, or chemical toxins), or by exposure to mercury.

Active properties of the urinary bladder: in vitro comparative studies between adult and neonatal rats

OBJECTIVE

To determine, using in vitro comparative studies, developmental aspects associated with the active properties of the urinary bladder in neonatal and adult rats.

MATERIALS AND METHODS

Urinary bladders were removed from neonatal (1-3 days old) and adult (15 weeks old) male Sprague-Dawley rats. Anterior longitudinal muscle strips were obtained from each group and isometric tensions recorded. Nerve-mediated contractions elicited by electrical field stimulation (0.8 ms pulse) or carbachol-induced contractile responses in neonatal and adult bladder strips were compared. Contractile tensions were normalized using the wet weight of the bladder strip or by using the percentage contraction induced by 60 mmol/L KCl.

RESULTS

Nerve-mediated contractile responses showed that the muscarinic component predominated in the neonatal rat bladder, which contrasted with the predominant purinergic components in adult bladder. The pattern of spontaneous activity and carbachol-induced contraction differed in the two groups. Small spontaneous contractions in the basal state occurred in adult bladder strips, while short-lived large spontaneous contractions were present in neonatal strips. The amplitude of carbachol-induced contractions generated in the neonatal bladder was larger than that in the adult bladder. In addition, the time to achieve peak contraction elicited by carbachol (5 micromol/L) was shorter in the neonatal bladder. Repetitive carbachol applications induced an attenuation of the contractile response (desensitization), but the neonatal bladder was more resistant to desensitization than the adult bladder.

CONCLUSIONS

These results show that nerve-mediated or agonist-induced contractile patterns, and spontaneous activity, in the neonatal bladder differ from those of the adult bladder in rats. The results suggest that in addition to neural immaturity, there are functional differences between the bladders of adult and neonatal rats.

Standard short-course chemotherapy for drug-resistant tuberculosis: treatment outcomes in 6 countries

CONTEXT

No large-scale study has investigated the impact of multidrug-resistant tuberculosis (TB) on the outcome of standard short-course chemotherapy under routine countrywide TB control program conditions in the World Health Organization's (WHO) directly observed treatment short-course strategy for TB control.

OBJECTIVE

To assess the results of treatment with first-line drugs for patients enrolled in the WHO and the International Union Against Tuberculosis and Lung Disease's global project on drug-resistance surveillance.

DESIGN AND SETTING

Retrospective cohort study of patients with TB in the Dominican Republic, Hong Kong Special Administrative Region (People's Republic of China), Italy, Ivanovo Oblast (Russian Federation), the Republic of Korea, and Peru.

PATIENTS

New and retreatment TB cases who received short-course chemotherapy with isoniazid, rifampicin, pyrazinamide, and either ethambutol or streptomycin between 1994 and 1996.

MAIN OUTCOME MEASURE

Treatment response according to WHO treatment outcome categories (cured; died; completed, defaulted, or failed treatment; or transferred).

RESULTS

Of the 6402 culture-positive TB cases evaluated, 5526 (86%) were new cases and 876 (14%) were retreatment cases. A total of 1148 (20.8%) new cases and 390 (44.5%) retreatment cases were drug resistant, including 184 and 169 cases of multidrug-resistant TB, respectively. Of the new cases 4585 (83%) were treated successfully, 138 (2%) died, and 151 (3%) experienced short-course chemotherapy failure. Overall, treatment failure (relative risk [RR], 15.4; 95% confidence interval [CI], 10.6-22.4; P<.001) and mortality (RR, 3.73; 95% CI, 2.13-6.53; P<.001) were higher among new multidrug-resistant TB cases than among new susceptible cases. Even in settings using 100% direct observation, cases with multidrug resistance had a significantly higher failure rate than those who were susceptible (9/94 [10%] vs 8/1410 [0.7%]; RR, 16.9; 95% CI, 6.6-42.7; P<.001). Treatment failure was also higher among patients with any rifampicin resistance (n=115) other than multidrug resistance (RR, 5.48; 95% CI, 3.04-9.87; P<.001), any isoniazid resistance (n=457) other than multidrug resistance (RR, 3. 06; 95% CI, 1.85-5.05; P<.001), and among patients with TB resistant to rifampicin only (n=76) (RR, 5.47; 95% CI, 2.68-11.2; P<.001). Of the retreatment cases, 497 (57%) were treated successfully, 51 (6%) died, and 124 (14%) failed short-course chemotherapy treatment. Failure rates among retreatment cases were higher in those with multidrug-resistant TB, with any isoniazid resistance other than multidrug resistance, and in cases with TB resistant to isoniazid only.

CONCLUSIONS

These data suggest that standard short-course chemotherapy, based on first-line drugs, is an inadequate treatment for some patients with drug-resistant TB. Although the directly observed treatment short-course strategy is the basis of good TB control, the strategy should be modified in some settings to identify drug-resistant cases sooner, and to make use of second-line drugs in appropriate treatment regimens. JAMA. 2000;283:2537-2545

Inhibitory effect of nitric oxide on voltage-dependent calcium currents in rat dorsal root ganglion cells

The effect of nitric oxide (NO) on calcium current (I(Ca)) and intracellular calcium concentration ([Ca(2+)](i)) in primarily cultured dorsal root ganglion (DRG) neurons was investigated from neonatal rats. I(Ca) and [Ca(2+)](i) were simultaneously recorded using perforated-patch technique in combination with fluorescence measurement from single DRG neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), inhibited I(Ca) in small-diameter neurons without significant change in voltage-dependence of activation and activation time constants. SNP and SNAP also reduced the transient [Ca(2+)](i) peak accompanied by I(Ca). Inhibition by NO was reproducible, but gradually desensitized. In some DRG neurons, SNP and SNAP increased basal [Ca(2+)](i) in concentration of 10 microM with little effect on NO-induced inhibition of I(Ca). 8-Br-cGMP, a permeable cGMP analog, mimicked the effects of SNP and SNAP. These results suggest that, in DRG neurons, NO has inhibitory effect on I(Ca), which is independent of NO-induced increase of basal [Ca(2+)](i), through cGMP-dependent pathway.

Retinoic acid and its receptors repress the expression and transactivation functions of Nur77: a possible mechanism for the inhibition of apoptosis by retinoic acid

Nur77 (NGFI-B) is an orphan nuclear receptor that has been implicated in activation-induced T-cell apoptosis. Retinoids, potent immune modulators, were shown to inhibit the activation-induced apoptosis of immature thymocytes and T-cell hybridomas. To illustrate the mechanism of the inhibition, we examined the effects of retinoic acid (RA) on the expression and transactivation functions of Nur77 in the human peripheral blood mononuclear cells and the human T-cell leukemia, Jurkat. All-trans-RA remarkably repressed the DNA binding and transcriptional induction of Nur77. Among the two potential trans-acting factors that activate Nur77 gene promoter, i.e., AP-1 and related serum response factor (RSRF), all-trans-RA repressed DNA binding and reporter gene activity of AP-1 but not that of RSRF, suggesting that the inhibition may be mediated through AP-1. We also demonstrated a posttranscriptional regulation of Nur77 function by retinoid receptors by showing that transactivation activity of Nur77 was significantly inhibited by cotransfection of RARalpha or RXRalpha. Nur77 bound RARalpha or RXRalpha in both yeast and mammalian two-hybrid tests, suggesting that direct protein-protein interaction between these receptors may mediate the inhibition. Taken all together, we demonstrated that RA repressed Nur77 function through multiple mechanisms that may provide the basis for RA inhibition on the apoptosis of activated T-lymphocytes.

Detection of adenoviruses and enteroviruses in tap water and river water by reverse transcription multiplex PCR

A reverse transcription (RT) multiplex polymerase chain reaction (PCR) assay was developed to simultaneously detect adenoviruses and enteroviruses, both of which have attracted much attention as molecular indices of viral pollution in environmental samples. The method involves a reverse transcription step, followed by a multiplex nested PCR in which the combination of primers amplifies cDNA from enteroviruses and adenoviruses. The sensitivity of this assay was found to be similar to that of each monoplex PCR or RT-PCR assay, and to be consistent regardless of relative concentrations of adenoviruses and enteroviruses. To assess suitability and environmental application of the RT multiplex PCR assay, a total of 12 river water samples and 4 tap water samples were analyzed by RT multiplex PCR, each monoplex PCR or RT-PCR, and cell culture assay on the Buffalo Green Monkey kidney cell line. The sensitivity of the RT multiplex PCR was also found to be similar to that of each monoplex PCR in environmental samples. This suggests the RT multiplex PCR assay could be applied to the routine monitoring of viral pollution in environmental waters.

Exclusive mutations related to isoniazid and ethionamide resistance among Mycobacterium tuberculosis isolates from Korea

SETTING

The single base change at the 94th codon of inhA has been referred to as the event that confers resistance on the drugs isoniazid (INH) and ethionamide (ETH) in Mycobacterium smegmatis and M. bovis. From this observation, it has been anticipated that some of the INH-resistant clinical isolates of M. tuberculosis would carry missense mutations in the same region of the gene. However, few polymorphisms have been identified in this region among INH-resistant isolates.

OBJECTIVE

To understand the molecular basis for M. tuberculosis resistance to INH and ETH.

DESIGN

The sequence polymorphism at the 94th codon of inhA among M. tuberculosis isolates from Korea was analyzed by polymerase chain reaction (PCR) cloning and sequence analysis.

RESULTS

No nucleotide change at the 94th codon of inhA was detected in any of the 24 INH-resistant isolates analyzed in this study. On the other hand, a point mutation was found exclusively at the regulatory region flanking a putative ribosome-binding site of the inhA locus in 14 isolates. Interestingly, all the mutations were of the same kind, which substitutes C to T. Among 14 isolates, 12 were resistant to INH as well as to ETH, while two were resistant to INH only.

DISCUSSION

It seems that mutations previously found at the 94th codon of inhA have no particular relationship with the mechanism involved in the resistance of M. tuberculosis to INH and/or ETH. On the other hand, the resistance mechanism of M. tuberculosis to INH/ETH may involve an altered level of InhA, an expression which may have been influenced by the sequence change in the regulatory region of the inhA locus.

Interleukin 8 expression regulates tumorigenicity and metastases in androgen-independent prostate cancer

Interleukin 8 (IL-8) is mitogenic and chemotactic for endothelial cells. Within a neoplasm, IL-8 is secreted by inflammatory and neoplastic cells. The highly metastatic PC-3M-LN4 cell line overexpresses IL-8 relative to the poorly metastatic PC-3P cell line. We evaluated whether IL-8 expression by human prostate cancer growing within the prostate of athymic nude mice regulates tumor angiogenesis, growth, and metastasis. PC-3P cells were transfected with the full-length sense IL-8 cDNA, whereas PC-3M-LN4 cells were transfected with the full-sequence antisense IL-8 cDNA. Control cells were transfected with the neomycin resistance gene (Neo). In vitro, sense-transfected PC-3P cells overexpressed IL-8-specific mRNA and protein, which resulted in up-regulation of matrix metalloproteinase 9 (MMP-9) mRNA, and collagenase activity, resulting in increased invasion through Matrigel. After antisense transfection of the PC-3M-LN4 cells, IL-8 and MMP-9 expression, collagenase activity, and invasion were markedly reduced relative to controls. After orthotopic implantation, the sense-transfected PC-3P cells were highly tumorigenic and metastatic, with significantly increased neovascularity and IL-8 expression compared with either PC-3P cells or controls. Antisense transfection significantly reduced the expression of IL-8 and MMP-9 and tumor-induced neovascularity, resulting in inhibition of tumorigenicity and metastasis. These results demonstrate that IL-8 expression regulates angiogenesis in prostate cancer, in part by induction of MMP-9 expression, and subsequently regulates the growth and metastasis of human prostate cancer.

Blue rubber bleb nevus syndrome with central nervous system involvement

An 11-month-old female patient presented with focal seizures. She was born at term with multiple scattered tiny protuberances and dark purple soft compressible nevi over her entire body. She had clumsiness and decreased muscle power in her left extremities. Magnetic resonance imaging and magnetic resonance angiography revealed cerebral atrophy of the right central area around the anomalous venous sinus and multiple small enhancing lesions throughout the brain with gadolinium-diethylenetriamine pentaacetic acid enhancement. Despite right partial neonatal seizures, she had no further seizures for 3 years while receiving carbamazepine, and no change was observed in the number and size of the nevi. At last evaluation, language and psychomotor development were normal for her age.

Absence of proximal duct apoptosis in the ventral prostate of transgenic mice carrying the C3(1)-TGF-beta type II dominant negative receptor

BACKGROUND

Prostatic epithelial cells are sensitive to the inhibitory effects of TGF-beta. However, TGF-beta signaling in the prostate is dependent on androgenic status. Under the in vivo conditions, it is difficult to dissociate the effect of TGF-beta from that of androgen on the prostate.

METHODS

The objective of the present study was to create and verify a transgenic mouse system in which epithelial cells of the ventral prostate are insensitive to the actions of TGF-beta. By using a modified prostate-specific promoter, C3(1), the TGF-beta dominant negative receptor is only expressed in the epithelial cells of the ventral prostate, and these cells are resistant to TGF-beta. Morphology of transgenic animal prostates was compared to wild-type animal prostates by immunohistochemistry and microscopy.

RESULTS

The prostate of transgenic mice exhibited an abnormal morphology with multiple layers of epithelial cells lining the proximal ducts, in contrast to the simple cuboidal monolayer of cells seen in the normal prostate. This observation was accompanied by a loss of apoptosis in this region, as seen by TUNEL assay. There was no significant difference in serum levels of testosterone between the wild-type and transgenic animals.

CONCLUSIONS

These results demonstrated that a loss of sensitivity to TGF-beta results in the accumulation of multiple layers of epithelial cells in the proximal region of the ventral prostate. This abnormal growth illustrates that TGF-beta plays an important role in regulating prostate growth. The current transgenic system can be used as an experimental model to study the functional role of TGF-beta in prostatic growth and function.

Random changes of amino acid residues with expected frequency by saturated point mutagenesis

The yeast transcriptional activator protein, Gcn4p from Saccharomyces cerevisiae binds to the specific sequence in the promoters of many amino acid biosynthetic genes for general control. A new random saturation mutagenesis method was developed to isolate Gcn4p derivatives with only one or two mutations in the DNA binding domain without using radioactive isotope. This will be used to identify the amino acids of Gcn4p involved in protein-protein interactions. Saturation mutagenesis in the DNA binding domain of Gcn4p was performed using spiked degenerate oligonucleotides containing randomized codon bases designed specifically for only one or two base changes in the mutagenized area. These oligonucleotides were synthesized to have two flanking restriction enzyme sites for cloning to the appropriate vector. The 3' ends were mutually primed after hybridization via the palindromic sequences of the restriction enzyme sites. These molecules were then converted to double stranded DNA upon treatment with DNA polymerase. Here, a library collection of 100,680 in an altered Gcn4p pool was generated by cloning a mixed-base oligonucleotide in the place of the sequence coding for the DNA binding domains. The quality of the library was examined by DNA sequencing and found to be in good agreement with the expected statistical values. Calculated mutation frequency was 66% of mutant nucleotide rate and actual sequencing data revealed 68% mutant nucleotide rates from the sequenced library. Thus, among 21 mutants, 16 had one point mutations and 5 had two point mutations. This approach appears to be an effective and general tool for creating proteins with one or two amino acid change(s) in their molecules.

Improved development of DNA-injected bovine embryos co-cultured with mouse embryonic fibroblast cells

The in vitro development of DNA-injected bovine zygotes, produced in vitro, was compared when cultured with or without mouse embryonic fibroblasts (MEF). The in vivo viability of the embryos produced in these in vitro culture systems was assessed by single or double transfer to recipients taken to term. For these experiments, in vitro fertilized oocytes were not injected (Experiment 1) or were injected with pBL1 gene (Experiment 2) and then cultured for 2 days in CR1aa medium supplemented with 3 mg/ml BSA at 38.5 degrees C in a humidified atmosphere of 5% CO(2) in air. Embryos that developed to the 4- to 8-cell stage at the end of this period were randomly assigned to the two cultured systems and cultured for a further 5 days in groups of 10 to 15 embryos in 0.75 ml medium. These two culture systems were CR1aa medium alone or co-culture with MEF in CR1aa medium supplemented with 10% fetal bovine serum (FBS). Every 48 h, 0.5 ml of the medium was replaced with fresh CR1aa medium and at Day 5 of culture, both media were supplemented by the addition of 5.56 mM glucose and 1x GMS-X supplement solutions. Results were assessed as morphological development of the embryos and data were analyzed by Chi-square test or Student's t-test. The development rate of in vitro fertilization (IVF)-derived embryos co-cultured with MEF (24.4%, 49/201) was significantly higher than those cultured alone (14.4%, 28/194; P<0.05) in Experiment 1. There was a similar difference between the treatments in the proportions of embryos which reached the hatching stage or hatched (10.9%, 22/201 vs. 4.1%, 8/194, respectively; P<0.05). DNA-injected embryos co-cultured with MEF (13.7%, 28/205) showed a higher developmental rate than that of the embryos cultured without MEF (6.7%, 13/193; P<0.05) in Experiment 2. Following the transfer to recipients of one or two DNA-injected blastocysts, the pregnancy rates for two culture systems were similar (MEF co-culture 27.4%, 23/84; CR1aa culture 24. 2%, 16/66). However, the numbers of calves born alive from these pregnancies were higher on the MEF co-culture group (82.6%, 19/23) than the CR1aa culture group (56.2%, 9/16). It was concluded that in vitro embryo development to the blastocyst stage and subsequent in vivo development to term of DNA-injected bovine embryos was improved in comparison to culture in CR1aa alone when the last 5 days of in vitro culture were in a MEF co-culture system.

Loss of TGF-beta signaling contributes to autoimmune pancreatitis

Recent observations suggest that immune response is involved in the development of pancreatitis. However, the exact pathogenesis underlying this immune-mediated response is still under debate. TGF-beta has been known to be an important regulating factor in maintaining immune homeostasis. To determine the role of TGF-beta in the initiation or progression of pancreatitis, TGF-beta signaling was inactivated in mouse pancreata by overexpressing a dominant-negative mutant form of TGF-beta type II receptor in the pancreas, under control of the pS2 mouse trefoil peptide promoter. Transgenic mice showed marked increases in MHC class II molecules and matrix metalloproteinase expression in pancreatic acinar cells. These mice also showed increased susceptibility to cerulein-induced pancreatitis. This pancreatitis was characterized by severe pancreatic edema, inflammatory cell infiltration, T- and B-cell hyperactivation, IgG-type autoantibodies against pancreatic acinar cells, and IgM-type autoantibodies against pancreatic ductal epithelial cells. Therefore, TGF-beta signaling seems to be essential either in maintaining the normal immune homeostasis and suppressing autoimmunity or in preserving the integrity of pancreatic acinar cells.

A disposable amperometric sensor screen printed on a nitrocellulose strip: a glucose biosensor employing lead oxide as an interference-removing agent

A new type of disposable amperometric sensor is devised by screen printing thick-film electrodes directly on a porous nitrocellulose (NC) strip. The chromatographic NC strip is then utilized to introduce various sample pretreatment layers. As a preliminary application, a glucose biosensor based on hydrogen peroxide detection is constructed by immobilizing glucose oxidase (GOx) on the NC electrode strip and by formulating a strong oxidation layer (i.e., PbO2) at the sample loading area, placed below the GOx reaction band. The screen-printed PbO2 paste serves as a sample pretreatment layer that removes interference by its strong oxidizing ability. Samples applied are carried chromatographically, via the PbO2 paste, to the GOx layer, and glucose is catalyzed to liberate hydrogen peroxide, which is then detected at the electrode surface. The proposed NC/PbO2 strip sensor is shown to be virtually insusceptible to interfering species such as acetaminophen and ascorbic and uric acids and to exhibit good performance, in terms of the sensor-to-sensor reproducibility (standard deviation, +/-0.026 - +/-0.086 microA), the sensitivity (slope, -0.183 microA/mM), and the linearity (correlation coefficient, 0.994 in the range of 0-10 mM).

Interleukin 8 expression regulates tumorigenicity and metastasis in human bladder cancer

Interleukin 8 (IL-8) is mitogenic and chemotactic for endothelial cells. Within a neoplasm, IL-8 is secreted by inflammatory and neoplastic cells. The highly tumorigenic and highly metastatic human transitional cell carcinoma (TCC) cell line 253J B-V overexpresses IL-8 relative to the nontumorigenic and nometastatic 253J-P cell line. To determine whether IL-8 expression regulates tumorigenicity and metastasis in human TCC, 253J B-V cells were transfected with the full-sequence antisense (AS) cDNA for IL-8, whereas 253J-P cells were transfected with the full-length IL-8 cDNA, and control cells for each were transfected with the neomycin resistance (Neo) gene. In vitro, sense-transfected 253J-P cells overexpressed IL-8-specific mRNA and protein, whereas both of these were markedly reduced in AS-IL-8-transfected 253J B-V cells relative to controls. Moreover, sense-transfected cells showed up-regulation in matrix metalloproteinase type 9 mRNA, collagenase activity, and increased invasiveness through Matrigel-coated filters, whereas these measures were lower in AS-transfected cells relative to controls. After implantation into the bladders of athymic nude mice, the sense-transfected 253J-P cells acquired increased tumorigenicity and metastasis, whereas the AS-transfected cells significantly inhibited tumorigenicity and metastases in the 253J B-V cell lines. This effect was accompanied by reduced IL-8 expression and microvessel density. These studies demonstrate that IL-8 expression enhances angiogenic activity through the induction of matrix metalloproteinase type 9 and subsequently regulates the tumorigenesis and production of spontaneous metastases of human TCC.

Molecular cloning and characterization of the mouse peroxiredoxin V gene

We have cloned two cDNA isoforms as well as genomic sequences of the mouse Prx V gene and characterized their molecular genetic features. Two isoforms of the mouse Prx V cDNA were identified from liver and testis. The testis-originated long transcripts had extra 1164-bp 5'-UTR sequences compared to the liver-originated short transcripts. Primer extension and sequence analyses revealed that the two isoforms were presumably transcribed at the same gene locus. The gene was composed of six exons spanning 3.2 kb. The short transcript was abundantly expressed in the kidney, liver, and heart of the adult mouse tissues and in the extra-membrane of the 10.5 dpc embryos. The long transcript of 1985 bp was abundantly detected in testis with trace amounts in other tissues. Interestingly, in testis and fetus, only mRNA expression of the long form was identified. However, the protein expression was not found in testis, implying that the long form could not properly direct the protein expression. The long Prx V cDNA has eight uORFs in the extra 5'-UTR, which proceed the major ORF. The inability of protein expression for the long-form cDNA in testis suggests that the uORFs might inhibit translation of the major ORF and thereby confer the tissue-specific regulation of the mouse Prx V gene.

Haploid loss of the tumor suppressor Smad4/Dpc4 initiates gastric polyposis and cancer in mice

The tumor suppressor SMAD4, also known as DPC4, deleted in pancreatic cancer, is a central mediator of TGF-beta signaling. It was previously shown that mice homozygous for a null mutation of Smad4 (Smad4-/-) died prior to gastrulation displaying impaired extraembryonic membrane formation and endoderm differentiation. Here we show that Smad4+/- mice began to develop polyposis in the fundus and antrum when they were over 6 - 12 months old, and in the duodenum and cecum in older animals at a lower frequency. With increasing age, polyps in the antrum show sequential changes from hyperplasia, to dysplasia, in-situ carcinoma, and finally invasion. These alterations are initiated by a dramatic expansion of the gastric epithelium where Smad4 is expressed. However, loss of the remaining Smad4 wild-type allele was detected only in later stages of tumor progression, suggesting that haploinsufficiency of Smad4 is sufficient for tumor initiation. Our data also showed that overexpression of TGF-beta1 and Cyclin D1 was associated with increased proliferation of gastric polyps and tumors. These studies demonstrate that Smad4 functions as a tumor suppressor in the gastrointestinal tract and also provide a valuable model for screening factors that promote or prevent gastric tumorigenesis.

Activation of NF-kappaB determines the sensitivity of human colon cancer cells to TNFalpha-induced apoptosis

Tumor necrosis factor alpha (TNFalpha) generates a potent cytotoxic effect, however many cancer cells are resistant to TNFalpha-mediated killing and the cause of the differential sensitivity remains to be elucidated. In this study, we demonstrated that TNFalpha induced cell death in four different human colon cancer cell lines. The degree of cytotoxic effect was different in each cell line, in that HCT-15 was relatively sensitive, while DLD-1, HT-29 and WiDr were relatively resistant. TNFalpha induced apoptotic changes such as morphological changes, DNA fragmentation and activation of caspase-3 in HCT-15, but to a lesser degree in the others. Transcriptional expression of TNFR1(p55), as well as that of FLICE, Fas, FADD, DR3, FAF, TRADD, and RIP was similar in these cell lines, indicating that the susceptibility to TNFalpha-induced apoptosis may not be determined by the constitutive expression level of these factors. Interestingly, the cytotoxic effect of TNFalpha was well correlated with the DNA binding activity of NF-kappaB in the colon cancer cell lines. Further, the overexpression of a non-phosphorylated mutant form of IkappaBalpha enhanced the cytotoxicity of TNFalpha in the resistant cell line, DLD-1, indicating that NF-kappaB activity may determine the sensitivity of colon cancer cells to TNFalpha-induced apoptosis. Thus, our results indicate that modulation of NF-kappaB activity may provide a useful tool to sensitize colon cancer cells to TNFalpha treatment.

Comparison of 1- and 2-incision posterior cruciate ligament reconstructions

This study compared the results of the 1-incision technique and the conventional 2- incision technique for the arthroscopic treatment of the posterior cruciate ligament (PCL) injury. The 2-incision technique was performed in 10 patients (group I) and the 1-incision technique in 45 patients (group II). The average duration of follow-up was 45 months in group I and 36 months in group II. Bone-patellar tendon-bone (BTB) autografts were used for all patients in group I. In group II, 34 BTB autografts and 11 BTB allografts were used. Postoperative Lysholm mean values were 90.0 in group I and 90.6 in group II. HSS mean values were 87.7 in group I and 92.6 in group II (P = .037). The Tegner activity level scales were 6.4 in group I and 6.5 in group II. The average side-to-side difference of the corrected posterior translation measured by the KT-2000 arthrometer were 2.10 mm in group I and 2.38 mm in group II. There were no statistically significant differences between the 2 groups in postoperative mean values except HSS scores. The arthroscopic PCL reconstruction using the 1-incision technique showed good results comparable with the conventional 2-incision technique. This technique needs no another incision or dissection over the medial femoral condyle.

Osseous metaplasia with functioning bone marrow in hydroxyapatite orbital implants

BACKGROUND

Bone formation within the hydroxyapatite implant has been reported in explanted spheres in humans. Bone-specific differentiation was observed to occur earlier in the pores of spherical hydroxyapatite implants enhanced with osteogenin within the rabbit socket. We observed previously unreported bone marrow formation in a coralline hydroxyapatite implant placed into the rabbit orbit after evisceration.

METHODS

One eye of each of 10 New Zealand white rabbits weighing between 2 and 3 kg was eviscerated and implanted with hydroxyapatite spheres. The explanted hydroxyapatite spheres 20 weeks after surgery were examined under the microscope.

RESULTS

Histopathologic examination of the excised implants showed the presence of trabeculae of mature bone with fatty marrow and hematopoietic elements. Scattered throughout the fatty tissue were bone marrow elements consisting of precursors of the granulocytic and erythroid series and also megakaryocytes.

CONCLUSION

The osseous metaplasia with functioning bone marrow was incidentally observed in the coralline hydroxyapatite implant without the addition of any osteogenesis-inducing agents.

Novel de novo nonsense mutation of MECP2 in a patient with Rett syndrome

Because of the recent identification of several mutations of methyl-CpG-binding protein 2 (MECP2) in patients with Rett syndrome (RTT), a patient with suspected RTT from an autism clinic was screened for mutations. She was found to have a novel heterozygous nonsense mutation, 129C>T (Q19X), which leads to the most severely truncated MECP2 protein reported to date. Sequencing of parental DNA revealed the mutation was de novo. The patient was not affected with microcephaly or hyperventilation, but had other features of Rett syndrome including severe mental retardation and symptoms of autistic disorder. Moderately skewed X-chromosome inactivation (XCI) may have contributed to her relatively mild phenotype.

Inhibition of apamin-sensitive K+ current by hypoxia in adult rat adrenal chromaffin cells

The effect of hypoxia on small-conductance Ca(2+)-activated K+ current was investigated in a study of adult rat adrenomedullary chromaffin cells (AMCs), which were maintained in short-term culture. The nystatin-perforated, whole-cell patchclamp technique was used to study the effect of hypoxia with minimum perturbation of the intracellular milieu. Under voltage-clamp conditions, acute hypoxia (P(O2) approximately equal to 25 mmHg) suppressed the whole-cell outward currents of more than half the AMCs (24/46). This suppression was eliminated after application of apamin (400 nM), a selective inhibitor of small-conductance Ca(2+)-activated K+ current (I(SK)(Ca)) (n=5), suggesting that an apamin-sensitive component of whole-cell currents is suppressed during hypoxia. In contrast to I(SK)(Ca), Ca2+ current (I(Ca)) (n=10) was not affected by hypoxia. Finally, under current-clamp conditions, hypoxia reversibly depolarized the resting membrane potential of adult AMCs (34/40). Apamin, however, eliminated the hypoxia-induced depolarization (400 nM) (7/8), suggesting that hypoxic depolarization is related to the suppression of I(SK(Ca). From the above results, we conclude that adult AMCs are sensitive to hypoxia, and that I(SK)(Ca) contributes to the hypoxia-induced suppression of whole-cell outward current and depolarization of the resting membrane potential in adult AMCs.

EWS-FLI1, EWS-ERG, and EWS-ETV1 oncoproteins of Ewing tumor family all suppress transcription of transforming growth factor beta type II receptor gene

Ewing sarcoma-specific chromosomal translocations fuse the EWS gene to a subset of ets transcription factor family members, most commonly the FLI1 gene and less frequently ERG, ETV1, E1A-F, or FEV. These fusion proteins are thought to act as aberrant transcription factors that bind DNA through their ets DNA binding domain. Recently, we have shown (K-B. Hahm et al., Nat. Genet., 23: 222-227, 1999) that the transforming growth factor beta (TGF-beta) type II receptor (TGF-beta RII), a putative tumor suppressor gene, is a target of the EWS-FLI1 fusion protein. Here, we also examined effects of EWS-ETV1 and EWS-ERG on expression of the TGF-beta RII gene. We show that relative to the control, NIH-3T3 cell lines stably transfected with the EWS-FLI1, EWS-ERG, or EWS-ETV1 gene fusion express reduced levels of TGF-beta RII mRNA and protein, and that these cell lines have reduced TGF-beta sensitivity. Cotransfection of these fusion genes and the TGF-beta RII promoter suppresses TGF-beta RII promoter activity and also FLI1-, ERG-, or ETV1-induced promoter activity. These results indicate that transcriptional repression of TGF-beta RII is an important target of the EWS-FLI1, EWS-ERG, or EWS-ETV1 oncogene, and that EWS-ets fusion proteins may function as dominant negative forms of ets transcription factors.

Antiproliferative effects of retinoic acid/interferon in cervical carcinoma cell lines: cooperative growth suppression of IRF-1 and p53

Retinoids and interferons have been implicated in the growth regulation of cervical cancer cells. However, the molecular mechanisms are not fully defined. To analyze detailed mechanisms, HPV-positive (HeLa, CaSki), HPV-negative (C33A, HT-3) and non-cervical Cos-1 cell lines were treated with I microM all-trans-retinoic acid (RA) and/or 10 ng/ml interferon-gamma (IFN-gamma). The growth of RA-treated HeLa cells was less effectively suppressed than that of IFN-gamma-treated ones. A combination of RA and IFN-gamma leads to an additive antiproliferative effect on the cell growth. CaSki cell growth was also inhibited by IFN-gamma but was little stimulated by RA treatment, and the IFN effect was attenuated when IFN-gamma was combined with RA. HPV-negative C33A and HT-3 cells, which are defective in p53 and Rb, and Cos- 1 cells were weakly or not responsive to all combined treatments. The molecular mechanism underlying the differential effects of RA/IFN on HeLa and C33A cells was investigated. Combined RA/IFN-gamma treatment caused a marked increase in the level of IFN regulatory factor-1 (IRF-1) in HeLa, whereas no induction of IRF-1 was observed in C33A, consistent with the findings that IFN signaling is functional in HeLa but is defective in C33A cells. The increase of p53 in HeLa cells might account for the down-regulation of HPV-18 E6 gene expression by RA/IFN-gamma. Furthermore, RA/IFN-gamma treatment resulted in the concurrent induction of p21WAF1 CDK inhibitor and dephosphorylation of Rb protein. Transient co-expression of IRF-1 and p53 led to the cooperative activation of the p21WAF1 promoter. Our results indicate that 2 transcription factors, increased in response to RA/IFN-gamma, cooperate functionally to regulate the cell cycle through the activation of a common p21WAF1 gene in HeLa cells.