A topogenic role for the oncogenic N-terminus of TLS: nucleolar localization when transcription is inhibited

TLS (FUS) and the related gene EWS encode the N-terminal portion of many fusion oncoproteins involved in human sarcomas and leukemia. TLS is an RNA-binding nuclear protein that is identical to hnRNP P2 and may be implicated in mRNA metabolism. When RNA polymerase II is inhibited, TLS immunostaining in the nucleus is dramatically altered, from its normal diffuse nucleoplasmic pattern to accumulation in dense nuclease-resistant aggregates. Co-immunostaining with antibodies to fibrillarin or p80 coilin and immunoelectron microscopy revealed that the TLS aggregates are associated with the nucleolus and are distinct from other known structures such as the coiled body or the interchromatin granule. Injection of cells with an oligodeoxynucleotide that disrupts splicing does not result in redistribution of TLS, indicating that the event is specific to inhibition of transcription. Oncoproteins that contain the N-terminal domain from either TLS, EWS or their Drosophila homologue, SARFH (CAZ), are also targeted to the same structure. These findings suggest a correlation between the topogenic and transforming activities of TLS and EWS N-termini and imply the existence of cellular targets that are shared by the germ-line encoded proteins and their oncogenic derivatives.

Pharmacokinetics and pharmacodynamics of ranitidine in renal impairment

OBJECTIVE

The pharmacodynamics and pharmacokinetics of ranitidine were examined in subjects with varying degrees of renal function to determine the effect of this condition on acid-antisecretory activity.

METHODS

Subjects with creatinine clearances (Ccr) ranging from 0 to 213 m1.min-1 received single 50-mg and 25-mg i.v. doses of ranitidine. This was followed by determination of serum and urine ranitidine concentrations, and continuous gastric pH monitoring for 24 h.

RESULTS

Serum ranitidine concentrations were described by a two-compartment model linked to a sigmoidal Emax model describing gastric pH. Ranitidine renal clearance, ranging from 0 to 1003 m1.min-1, correlated with CPAH (r2 = 0.707), while non-renal clearance was unaltered. Steady-state volume of distribution decreased by half in severe renal impairment. No changes in the effective concentration at half-maximal response (EC50), maximal response (Emax), or basal response (E0) were observed. Thus, renal elimination of ranitidine declined in parallel with renal function, while sensitivity to the pharmacologic effect (gastric pH elevation) was unaltered. Ranitidine was cell tolerated in these renally impaired subjects.

CONCLUSION

These data indicate that the current recommendation for renal impairment dose reduction (by two-thirds when Ccr < 50 m1-min-1) might result in under-treating moderately impaired patients, and suggests a less conservative dose reduction (by half when Ccr < 10 m1.min-1) to avoid therapeutic failure while remaining within the wide margin of safety for this drug.

[Treatment of nerve root avulsion of brachial plexus by nerve transfer]

The results of nerve transposition for root avulsion of brachial plexas in 21 cases were reported. The methods of the nerve transposition were divided into four groups as followings: By transfer of phrenic nerve, accesory nerve, the motor branches of cervical plexus and intercostal nerves in cease; By transfer of phrenic nerve, accessory nerve and the motor branches of cervical plexus in 6 cases; By transfer of phrenic nerve and accessory nerve in 9 cases, and by transfer of phrenic nerve or the motor branches of cervical plexus or intercostal nerve in 5 cases. During operation, in 1 cases variation of the brachial plexus was found. Injury to the subclavian artery occurred in 4 cases and they were repaired, which is good for the blood circulation of the upper arm and nerve regeneration. Nineteen cases were followed up with good results. The overall excellent and good rate was 73.7%. It was considered that transposition of nerve should be a routine operation for the treatment of root avulsion of brachial plexus and the accompanied arterial injury should be repaired at the same time during operation, and the latter would be advantageous to enhance functional recovery of nerve.

Surgeons' decision making in patients with chronic wrist pain: role of bilateral three-compartment wrist arthrography--prospective study

PURPOSE

To determine if wrist arthrography changes surgeons' diagnoses and treatment plans for patients with chronic wrist pain.

MATERIALS AND METHODS

Bilateral, three-compartment wrist arthrography was performed in 64 patients. Prospective questionnaires evaluated surgeons' diagnoses and management plans at three stages: before arthrography, after arthrography of the symptomatic wrist, and after arthrography of the asymptomatic wrist.

RESULTS

Surgeons tended to plan more conservative management after receiving the results of arthrography. The number of patients for whom the reported treatment plan included surgery dropped from 28 of 64 patients (44%) to 19 of 64 patients (30%) after review of the arthrography results (P = .05). The number of patients for whom the treatment plan included treatment of any kind dropped from 55 of 64 patients (86%) to 49 of 64 patients (77%) after review of the arthrography results (P = .09). An overall change in treatment plan occurred in 29 of 64 patients (45%).

CONCLUSION

Wrist arthrography influences surgeons' decision making. After reviewing the results of arthrography, surgeons tended to change treatment plans toward more conservative, less invasive treatment.

Pharmacokinetics of bismuth and ranitidine following single doses of ranitidine bismuth citrate

1. The pharmacokinetics of bismuth and ranitidine derived from ranitidine bismuth citrate given in single oral doses ranging from 200 mg to 1600 mg were evaluated in healthy subjects. 2. Bismuth was only minimally absorbed (< 0.5% of the amount dosed) after administration of ranitidine bismuth citrate, and peak plasma concentrations never exceeded 33 ng ml-1 in any subject. Plasma concentrations and urinary recoveries of bismuth at doses up to and including 800 mg were relatively constant and not proportional to dose. Bismuth absorption was increased more than proportionally with the dose at 1600 mg. 3. The pharmacokinetics of ranitidine after administration of ranitidine bismuth citrate were dose-proportional and consistent with previous observations for ranitidine administered alone. 4. Ranitidine bismuth citrate was well-tolerated in single oral doses of up to 1600 mg.

[Finite element stress analysis of stress distribution endodontic posts at shoulder]

The objective of the present resarch is the comparative stress distribution of various design for post-core at shoulder. The purpose of this study was to analyse the stress distribution and concentration in the dentin of paralled-sided and taped posts by different shoulder designs with finite elements stress analysis method. It was found that stress tended to concentrate under the core shoulder with vertical force. When the force applied from the linqual side. The stress concentrated at the buccal side. The 90 degrees shoulder angles exhibited more even stress distribution than sharp shoulder angles. The analysis revealed that sharp angle should be avoided as occlusal shoulder in clinical practice because this design are less resistant to forces applied on them and are susceptible to fractures in the dentin.

Incomplete factorial and response surface methods in experimental design: yield optimization of tRNA(Trp) from in vitro T7 RNA polymerase transcription

We have studied the yield of Escherichia coli tRNA(Trp) obtained from in vitro T7 RNA polymerase transcription using incomplete factorial and response surface methods. Incomplete factorial experiments were first used to estimate the relative impact of six variables on the yield of tRNA(Trp). Fifteen trials were performed according to a balanced and randomized design. The correlation between observed yield and all experimental variables was identified by stepwise multiple linear regression analysis. The concentrations of T7 RNA polymerase, DNA template, NTP and MgCl2 proved to be significantly correlated with the yield of tRNA(Trp). We then optimized the yield with respect to each of these four variables simultaneously with a designed, response surface experiment based on the Hardin-Sloane minimum prediction variance algorithm. Twenty experiments were performed, in duplicate, to sample the quadratic surface relating the yield to the four significant variables. Coefficients of the quadratic function with all two-factor interactions were evaluated by stepwise regression using least squares, and significant coefficients were retained. Partial differentiation of the resulting quadratic model showed it to possess an optimum. Transcription performed at the corresponding conditions yielded 6-fold more tRNA(Trp) than the initial conditions, confirming the predictive value of the experimentally determined response surface.

Imaging of pelvic insufficiency fractures

Insufficiency fractures of the pelvis are being increasingly recognized as a major cause of low back pain in elderly women with osteoporosis. Fractures in the sacrum are difficult to diagnose, as plain radiographic findings are either unhelpful or misleading. Bone scintigraphy is very sensitive for the detection of fractures in the sacrum, with demonstration of the H-shaped (or butterfly) sacral pattern or the combination of concomitant sacral and parasymphyseal uptake being considered as characteristic of insufficiency fractures. Computed tomography (CT) is helpful for confirming the presence of fractures in cases with atypical scintigraphic patterns, particularly in those with a known primary malignant neoplasm. CT is especially useful in the further evaluation of parasymphyseal and pubic rami lesions. The majority of patients respond well to periods of enforced bed rest and administration of analgesics. Recognition of the spectrum of imaging findings for this entity should lead to its correct identification and the institution of appropriate treatment.

Induction of apoptosis by c-Fos protein

The role of c-Fos in apoptosis was examined in two Syrian hamster embryo cell lines (sup+I and sup-II) and a human colorectal carcinoma cell line (RKO), using the chimeric Fos-estrogen receptor fusion protein c-FosER. As previously reported, contrasting responses were observed when these two cell lines were placed under growth factor deprivation conditions; sup+I cells were highly susceptible to apoptosis, whereas sup-II cells were resistant. In this report, we show that the activated c-FosER protein induces apoptosis in sup-II preneoplastic cells in serum-free medium, indicating that c-Fos protein can induce apoptotic cell death in these cells. c-Fos-induced apoptosis was not blocked by the protein synthesis inhibitor cycloheximide, suggesting that the c-Fos transcriptional activation activity is not involved. This conclusion was further supported by the observation that overexpression of v-Fos, which is highly proficient in transcriptional activation but deficient in the transcriptional repression activity associated with c-Fos, did not induce apoptosis. Constitutively expressed Bcl-2 delayed the onset of low-serum-induced apoptosis in sup+I cells and enhanced survival in sup-II cells. Further, coexpression of Bcl-2 and c-FosER in sup+I or sup-II cells protected the cells from c-FosER-induced apoptosis. The possibility that c-FosER-induced apoptosis requires a p53 function was examined. Colorectal carcinoma RKOp53+/+ cells, which do not normally undergo apoptosis in serum-free medium, showed apoptotic DNA fragmentation upon expression and activation of c-FosER. Further, when the wild-type p53 protein was diminished in the RKO cells by infection with the papillomavirus E6 gene, subsequent c-FosER-induced apoptosis was blocked. The data suggest that c-Fos protein plays a causal role in the activation of apoptosis in a p53-dependent manner. This activity does not require new protein synthesis and is blocked by overexpression of Bcl-2 protein.

Cantor network, control algorithm, two-dimensional compact structure and its optical implementation

A compact integrating module technique for packaging a optical multistage Cantor network with a polarization multiplex technique is suggested. The modules have a unique configuration, which is the solid-state combination of a polarization rotator, double birefringent slabs, and a 2 × 2 switch array. The design and the fabrication of an eight-channel optical nonblocking Cantor network are demonstrated, and a fast-setup control algorithm is developed. The network systems are easy to assemble and insensitive to environment disturbance.

Lack of functional retinoblastoma protein mediates increased resistance to antimetabolites in human sarcoma cell lines

Growth inhibition assays indicated that the IC50 values for methotrexate (MTX) and 5-fluorodeoxyuridine (FdUrd) in HS-18, a liposarcoma cell line lacking retinoblastoma protein (pRB), and SaOS-2, an osteosarcoma cell line with a truncated and nonfunctional pRB, were 10- to 12-fold and 4- to 11-fold higher, respectively, than for the HT-1080 (fibrosarcoma) cell line, which has wild-type pRB. These Rb-/- cell lines exhibited a 2- to 4-fold increase in both dihydrofolate reductase (DHFR) and thymidylate synthase (TS) enzyme activities as well as a 3- to 4-fold increase in mRNA levels for these enzymes compared to the HT-1080 (Rb+/+) cells. This increase in expression was not due to amplification of the DHFR and TS genes. Growth inhibition by MTX and FdUrd was increased and DHFR and TS activities and expression were correspondingly decreased in Rb transfectants of SaOS-2 cells. In contrast, there was no significant difference in growth inhibition among these cell lines for the nonantimetabolites VP-16, cisplatin, and doxorubicin. A gel mobility-shift assay showed that parental SaOS-2 cells had increased levels of free E2F compared to the Rb-reconstituted SaOS-2 cells. These results indicate that pRB defective cells may have decreased sensitivity to growth inhibition by target enzymes encoded by genes whose transcription is enhanced by E2F proteins and suggest mechanisms of interaction between cytotoxic agents and genes involved in cell cycle progression.

Three-compartment wrist arthrography: direct comparison of digital subtraction with nonsubtraction images

PURPOSE

To determine the diagnostic value of digital subtraction and fluoroscopic spot images in wrist arthrography, alone and in combination.

MATERIALS AND METHODS

Randomized selective bilateral three-compartment wrist arthrography was performed in 64 patients. The fluoroscopic spot and digital subtraction images were read separately by two radiologists without knowledge of the clinical data.

RESULTS

One hundred twenty communicating defects were found in 69 wrists in 42 patients. Fluoroscopic spot radiographs alone depicted defects in all 69 wrists, but precise localization was not possible in 10 defects. Subtraction images alone demonstrated 59 defects. The defects not seen with digital subtraction imaging were identified after wrist motion. Digital subtraction images demonstrated defects earlier during the joint injection and demonstrated the exact site of the 10 defects not localized on the nonsubtracted images.

CONCLUSION

Digital subtraction and fluoroscopic spot images are complementary in wrist arthrography and, when used in combination, increase the ability to localize the sites of defects, although the value added by the subtraction technique is small.

Time-dependent phenomena in plasma-assisted chemical vapor deposition of rugate optical films

The plasma-assisted chemical vapor deposition technique was used to produce thin-film structures with both sinusoidally and stepwise varying refractive-index profiles. The refractive index of the SiO(x)N(y) system used in the fabrication was found to be time dependent following a stepwise change in reactant gas flows or initiation of the plasma. This time dependence has been quantified using in situ ellipsometry and was found to have components with exponential and linear dependences. The time dependence of water vapor partial pressure in the system was identified as the cause of the linear dependence. Allowance for the time-dependent effects has improved the agreement between the calculated spectral response and the measured result for a broadband high-reflectance mirror consisting of an arithmetic progression of discrete layers.

[Peripheral anterior synechiae overlying the haptics of posterior chamber lenses]

To study the changes of the anterior chamber angle after intraocular lens implantation, 111 patients (130 eyes) with posterior chamber intraocular lens implantation at different post-operative periods were examined by gonioscopy. Peripheral anterior synechia overlying the position of the lens haptic (lens haptic PAS) was observed in up to 50.8% of eyes implanted with haptics vaulted anteriorly by 10%. The lens haptic PAS is easy to be identified, it is a broad based forward displacement of the peripheral iris adhesive to the anterior wall of the anterior chamber angle. The size of the PAS was of half to one o'clock position and occasionally it was of one and a half to two o'clock position. The differences between the rates of occurrence of lens haptic PAS were not significant at different post-operative periods (P > 0.05). 55.9% of the sulcus fixated and 42.3% of the capsular fixated eyes had lens haptic PAS (P > 0.05). There were more lens haptic PAS in eyes with horizontally oriented lens haptics (62.7%) than with lens haptics at vertical position (41.4%, P < 0.05). Regular gonioscopy for posterior chamber lens implantation was recommended.

A 9-year-old girl with a bowed right forearm 6 months after a fracture

The following case is presented to illustrate the roentgenographic and clinical findings of a condition of interest to the orthopedic surgeon. Initial history, physical findings, and roentgenographic examinations are found on the first page. The final clinical and roentgenographic differential diagnoses are presented on the following pages.

Deficiency of retinoblastoma protein leads to inappropriate S-phase entry, activation of E2F-responsive genes, and apoptosis

The retinoblastoma susceptibility gene (Rb) participates in controlling the G1/S-phase transition, presumably by binding and inactivating E2F transcription activator family members. Mouse embryonic fibroblasts (MEFs) with no, one, or two inactivated Rb genes were used to determine the specific contributions of Rb protein to cell cycle progression and gene expression. MEFs lacking both Rb alleles (Rb-/-) entered S phase in the presence of the dihydrofolate reductase inhibitor methotrexate. Two E2F target genes, dihydrofolate reductase and thymidylate synthase, displayed elevated mRNA and protein levels in Rb- MEFs. Since absence of functional Rb protein in MEFs is sufficient for S-phase entry under growth-limiting conditions, these data indicate that the E2F complexes containing Rb protein, and not the Rb-related proteins p107 and p130, may be rate limiting for the G1/S transition. Antineoplastic drugs caused accumulation of p53 in the nuclei of both Rb+/+ and Rb-/- MEFs. While p53 induction led to apoptosis in Rb-/- MEFs, Rb+/- and Rb+/+ MEFs underwent cell cycle arrest without apoptosis. These results reveal that diverse growth signals work through Rb to regulate entry into S phase, and they indicate that absence of Rb protein produces a constitutive DNA replication signal capable of activating a p53-associated apoptotic response.

Structural analysis and comparison of the C-terminal transport signal domains of hemolysin A and leukotoxin A

NMR spectroscopy was used to study the structure of the C-terminal signal sequences of the bacterial toxins, hemolysin A(HlyA) and leukotoxin A (LktA). The two signals share little sequence homology; however, both can direct toxin transport with equal efficiency. We report here that in a membrane mimetic environment both peptides form two short non-interacting alpha-helices separated by a short loop. This higher order structure may be a common feature of C-terminal signals and may be required for interaction with the membrane associated transporter complex.

The regulatory regions of the rice tungro bacilliform virus promoter and interacting nuclear factors in rice (Oryza sativa L.)

The Rice Tungro Bacilliform Virus (RTBV) promoter confers phloem-specific gene expression in transgenic rice plants. A series of promoter deletion mutants were fused with the Escherichia coli beta-glucuronidase A (uidA) reporter gene and introduced into transgenic rice plants. The RTBV promoter confers substantially stronger expression in shoots than in roots. A fragment of the promoter comprising nucleotides -164 to +45 relative to the transcriptional start site contains sufficient information for phloem-specific gene expression. Within this region, nucleotides -164 to -43 were essential for promoter function since deletion of this fragment dramatically reduced promoter activity. Gel-retardation assays identified two groups of rice nuclear factors (RNFG1 and RNFG2) that bind to the -164 to +45 promoter fragment. Competition and DNasel footprinting experiments indicated that RNFG1 bound to nucleotides -3 to +8 (Box I) while RNFG2 bound to nucleotides -53 to -39 (Box II). Interactions between the two groups of factors were observed. In addition, we found differences in the binding of nuclear factors from shoots versus from roots, in agreement with the different activities of the promoter in these two organs. It is proposed that binding of RNFG1 and RNFG2 between nucleotides -164 to +45 is essential for the tissue-specific expression of this promoter.

Self-activation of N-phosphoamino acids and N-phosphodipeptides in oligopeptide formation

N-Phosphorylamino acids and N-phosphoryldipeptides can self-activate to give the oligopeptide. An intramolecular mixed anhydride intermediate might exist during the self-activating process. A peptide bond was formed from the N-terminus to the C-terminus by the '1 + n' mechanism, which was similar to the rRNA-peptide biosynthesis pathway.

Expression of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in Escherichia coli

Chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase was expressed in E. coli by using a pET3a T7 RNA polymerase-based expression system and was purified to homogeneity. The kinase and bisphosphatase of the expressed bifunctional enzyme had kinetic properties identical to those of the native chicken liver enzyme. However, the kinase activity of the chicken liver enzyme was 7-fold higher, while the bisphosphatase activity was 50 percent lower than those of the rat liver enzyme. Cys-256 of the rat liver bisphosphatase domain is not conserved in the chicken liver enzyme. A site-directed mutation was engineered at Cys-256 of the rat liver enzyme and the results indicate that the variation of this residue is not responsible for the difference in fructose-2,6-bisphosphatase activity between the rat and chicken liver enzymes. It is postulated that the difference in the kinase/bisphosphatase activity ratios of these two enzymes results from differences in their NH2-terminal regions.

Secretion and circular dichroism analysis of the C-terminal signal peptides of HlyA and LktA

The secretion of the 107 kDa hemolysin A (HlyA) from Escherichia coli is mediated by membrane proteins hemolysin B (HlyB) and hemolysin D (HlyD). The signal for transport has been mapped to the C-terminal 60 amino acids of the HylA molecule. We have shown previously that the C-terminal 70 amino acids of leukotoxin (LktA) from Pasteurella hemolytica can substitute functionally for the HlyA signal sequence. This 70 amino acid peptide contains little primary sequence similarity to the HlyA signal sequence, and we have hypothesized that these signal sequences assume a similar higher-order structure which is recognized by the HlyB/D transporter. In the present study, we have expressed and purified small peptides containing the C-terminal 61 amino acids of HlyA and the C-terminal 70 amino acids of LktA. We show that these signal peptides are sufficient for secretion from E. coli in a HlyB/D dependent manner. Circular dichroism analyses show that both molecules exhibit common biophysical properties. In aqueous solution, they appear to be mainly unstructured, but in a membrane mimetic environment they assume a helical secondary structure. The conformational change observed for both peptides going from an aqueous to a membrane mimetic environment may be an important feature of these signal sequences necessary for their recognition and transport.

Mutations in rpoB gene of rifampicin resistant clinical isolates of Mycobacterium tuberculosis in Japan

In Mycobacterium tuberculosis, involvement of alterations of the RNA polymerase beta subunit in resistance to rifampicin has been described by Telenti et al. To determine if the same correlation could be observed between the mutation of the rpoB gene and clinically isolated M. tuberculosis of the rifampicin-resistant phenotype in Japan, 47 strains of M. tuberculosis of the rifampicin-resistant phenotype, 17 of the rifampicin-susceptible phenotype, and 4 type strains were examined. A 411-base pair (bp) rpoB fragment was amplified by the polymerase chain reaction and subjected to solid phase direct sequencing. By comparing the nucleotides, mutation involving 8 conserved amino acids were identified in 44 of the 47 (93.6%) rifampicin-resistant isolates, but in none of the 17 sensitive isolates and 4 type strains. All mutations found were clustered within a region of 23 amino acids. Thus, similar to the results reported by Telenti et al., substitution of a limited number of highly conserved amino acids encoded by the rpoB gene appears to be the molecular mechanism responsible for resistance to rifampicin in Japanese clinical isolates of M. tuberculosis. Our results suggest that direct DNA sequencing of the rpoB gene may be a reliable method for identifying rifampicin-resistant M. tuberculosis strains among Japanese clinical isolates.