LB0002 A FIRST IN CLASS THERAPEUTIC NANOPARTICLE FOR SPECIFIC TARGETING OF ANTI-CITRULLINATED PROTEIN ANTIBODY AMELIORATES SERUM TRANSFER AND COLLAGEN INDUCED ARTHRITIS

Background:

Rheumatoid arthritis (RA) is an immune mediated inflammatory disease with autoimmune features, including antibodies to citrullinated proteins and peptides (ACPAs). Several in vitro studies have suggested a pathogenic role of ACPAs in RA. However, in vivo proof of this concept has been hampered by the lack of therapeutic strategies to reduce or deplete ACPA in serum and synovial fluid. Previously, we constructed a chitosan-hyaluronic acid nanoparticle formulation with the ability to use neutrophil recruitment as a delivery mechanism to inflamed joints. Specifically, nanoparticles got phagocytosed and then released to synovial fluid upon death of the short-lived neutrophils

Objectives:

We hypothesized that reducing ACPA levels would have a therapeutic effect by blocking cytokine production. In this study, we prepared and tested a series of therapeutic nanoparticles for specific targeting of ACPA in synovial fluid.

Methods:

Nanoparticles were prepared by the microdroplet method and then decorated with synthetic cyclic citrullinated peptide aptamer PEP2, PEG/hexanoic acid and fluorophore (Cy5.5). Nanoparticles were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM) and high-performance liquid chromatography (HPLC). Nanoparticles were then used in a series of in vitro assays, including cell uptake with flow cytometry (FACS) detection, and in vivo studies including disease activity scores, cytokine measurements and near-infrared imaging.

Results:

We screened a series of citrullinated peptide epitopes and identified a fibrinogen-derived 21-amino-acid-long citrullinated peptide showing high selectivity toward autoantibodies in RA samples. We incorporated this aptamer in the chitosan-hyaluronic acid nanoparticle formulation previously described. Average nanoparticle size was 230 nm ± 10 nm by DLS and SEM; z potential was -0.0012. Purity by HPLC was over 95%. Attachment efficiency of the aptamer was 92% by HPLC. FACS study showed selective uptake of Cy5.5 labelled aptamer-nanoparticle conjugates by neutrophils in the concentration range 0.5-4 nM. Similar to previous studies,1there was no apparent immunogenicity for this nanoparticle formulation measured by cytokine secretion from human peripheral blood leukocytes. In vivo, over 50% reduction of disease activity was achieved in three weeks treatment using as little as 1 nM drug candidate (dosed every 48 hours) in the collagen-induced (CIA) mouse model of RA (N=30; p<0.001 for treated vs placebo). Same was observed in the serum transfer model (N=10). The aptamer-nanoparticle conjugate significantly reduced IL-6 and TNFα levels in the mouse sera (p<0.01). The effects were not inferior to tocilizumab treated controls (N=30). To confirm mode of action, we applied Cy5.5-labelled aptamer-nanoparticles in the collagen-induced mouse model (N=10) and analyzed the resulting uptake by near-infrared imaging. We confirmed over 6-fold higher signal accumulation in inflamed vs healthy joints (p<0.01), which strongly supports the fact that the aptamer is highly specific to the inflammatory process.

Conclusion:

Overall, we have designed a first-in-class therapeutic nanoparticle drug for specific targeting of anti-citrullinated protein antibodies. The marked effect of this nanoparticle observed in vivo holds promise for targeting ACPAs as a therapeutic option in RA.

References:

[1]Khatri S, Hansen J, Mendes AC, Chronakis IS, Hung S-C, Mellins ED, Astakhova K. Bioconjug Chem. 2019 Oct 16;30(10):2584–259

Disclosure of Interests:

Sangita Khatri: None declared, Jonas Hansen: None declared, Mads Hartvig Clausen Shareholder of: iBio Tech ApS, Tue Wenzel Kragstrup Shareholder of: iBio Tech ApS, Consultant of: Bristol-Myers Squibb, Speakers bureau: TWK has engaged in educational activities talking about immunology in rheumatic diseases receiving speaking fees from Pfizer, Bristol-Myers Squibb, Eli Lilly, Novartis, and UCB., Shu-Chen Hung: None declared, Elisabeth Mellins: None declared, Kira Astakhova: None declared

Radiation doses of cerebral blood volume measurements using C-arm CT: A phantom study

BACKGROUND AND PURPOSE

Parenchymal blood volume measurement by C-arm CT facilitates in-room peritherapeutic perfusion evaluation. However, the radiation dose remains a major concern. This study aimed to compare the radiation dose of parenchymal blood volume measurement using C-arm CT with that of conventional CTP using multidetector CT.

MATERIALS AND METHODS

A biplane DSA equipped with C-arm CT and a Rando-Alderson phantom were used. Slab parenchymal blood volume (8-cm scanning range in a craniocaudal direction) and whole-brain parenchymal blood volume with identical scanning parameters, except for scanning ranges, were undertaken on DSA. Eighty thermoluminescent dosimeters were embedded into 22 organ sites of the phantom. We followed the guidelines of the International Commission on Radiation Protection number 103 to calculate the effective doses. For comparison, 8-cm CTP with the same phantom and thermoluminescent dosimeter distribution was performed on a multidetector CT. Two repeat dose experiments with the same scanning parameters and phantom and thermoluminescent dosimeter settings were conducted.

RESULTS

Brain-equivalent dose in slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 52.29 ± 35.31, 107.51 ± 31.20, and 163.55 ± 89.45 mSv, respectively. Variations in the measurement of an equivalent dose for the lens were highest in slab parenchymal blood volume (64.5%), followed by CTP (54.6%) and whole-brain parenchymal blood volume (29.0%). The effective doses of slab parenchymal blood volume, whole-brain parenchymal blood volume, and CTP were 0.87 ± 0.55, 3.91 ± 0.78, and 2.77 ± 1.59 mSv, respectively.

CONCLUSIONS

The dose measurement conducted in the current study was reliable and reproducible. The effective dose of slab parenchymal blood volume is about one-third that of CTP. With the advantages of on-site and immediate imaging availability and saving procedural time and patient transportation, slab parenchymal blood volume measurement using C-arm CT can be recommended for clinical application.

Can iterative reconstruction improve imaging quality for lower radiation CT perfusion? Initial experience

BACKGROUND AND PURPOSE

Initial results using IR for CT of the head showed satisfactory subjective and objective imaging quality with a 20-40% radiation dose reduction. The aim of our study was to compare the influence of IR and FBP algorithms on perfusion parameters at standard and lowered doses of CTP.

MATERIALS AND METHODS

Forty patients with unilateral carotid stenosis post-carotid stent placement referred for follow-up CTP were divided into 2 groups (tube currents were 100 mAs in group A and 80 mAs in group B). Datasets were reconstructed with IR and FBP algorithms; and SNRs of gray matter, white matter, and arterial and venous ROIs were compared. CBF, CBV, and MTT means and SNRs were evaluated by using linear regression, and qualitative imaging scores were compared across the 2 algorithms.

RESULTS

The mean effective radiation dose of group B (2.06 mSv) was approximately 20% lower than that of group A (2.56 mSv). SNRs for ROIs in the dynamic contrast-enhanced images were significantly higher than those for the FBP images. Correlations of the SNRs for CBF, CBV, and MTT across the 2 algorithms were moderate (R² = 0.46, 0.23, and 0.44, respectively). ROIs in gray matter rather than the IR algorithm predicted increasing SNRs in all CBF, CBV, and MTT maps. Two cases of significant restenosis were confirmed in both algorithms. CBV, CBF, and MTT imaging scores did not differ significantly across algorithms or groups.

CONCLUSIONS

Lower dose CTP (20% below normal dose) without IR can effectively identify oligemic tissue in poststenting follow-up. IR does not alter the absolute values or increase the SNRs of perfusion parameters. Other methods should be attempted to improve SNRs in settings with low tube currents.

Monitoring peri-therapeutic cerebral circulation time: a feasibility study using color-coded quantitative DSA in patients with steno-occlusive arterial disease

BACKGROUND AND PURPOSE

Intracranial hemodynamics are important for management of SOAD. This study aimed to monitor peri-stent placement intracranial CirT of patients with SOAD.

MATERIALS AND METHODS

Twenty-five patients received stent placement for extracranial ICA stenosis, and 34 patients with normal CirT were recruited as controls. Their color-coded DSAs were used to define the Tmax of selected intravascular ROI. A total of 20 ROIs of the ICA, OphA, ACA, MCA, FV, PV, OV, SSS, SS, IJV, and MCV were selected. rTmax was defined as the Tmax at the selected region of interest minus Tmax at the cervical segment of the ICA (I1 on AP view and IA on lateral view). rTmax of the PV was defined as intracranial CirT. Intergroup and intragroup longitudinal comparisons of rTmax were performed.

RESULTS

rTmax values of the normal cohorts were as follows: ICA-AP, 0.12; ICA-LAT, 0.10; A1, 0.28; A2, 0.53; A3, 0.81; M1, 0.40; M2, 0.80; M3, 0.95; OphA, 0.35; FV, 4.83; PV, 5.11; OV, 5.17; SSS, 6.16; SS, 6.51; IJV, 6.81; and MCV, 3.86 seconds. Before stent placement, the rTmax values of arterial ROIs, except A3 and M3, were prolonged compared with values from control subjects (P < .05). None of the rTmax of any venous ROIs in the stenotic group was prolonged with significance. After stent placement, the rTmax of all arterial ROIs shortened significantly, except A1and M3. Poststenting rTmax was not different from the control group.

CONCLUSIONS

Without extra contrast medium and radiation dosages, color-coded quantitative DSA enables real-time monitoring of peri-therapeutic intracranial CirT in patients with SOAD .

First Report of Group 16SrXII Phytoplasma Associated with Papaya Yellows in Taiwan

Phytoplasmas have been reported to cause various disorders in papaya (Carica papaya L.), including dieback, mosaic, and yellow crinkle in Australia, Nivun Haamir dieback in Israel, and bunchy top-like disease in Cuba (1). Papaya is an economically important crop in Taiwan, and therefore, is monitored for viral infections. In 2005, papaya plants showing chlorosis, yellows and shriveling of leaves, dieback and lateral growth of branches, bending of apical branches, latexosis of fruits, and brown necrosis in phloem tissues were observed in southern Taiwan. Examination by an electron microscope revealed the presence of pleomorphic phytoplasma cells in sieve tubes of the phloem of petioles and leaf veins of diseased plants. Total DNA was extracted individually from at least three diseased plants at each location with a commercial DNA preparation kit (Axygen Scientific, Union City, CA) and used for amplification of the phytoplasma 16S rRNA gene in PCR with universal primer pairs P1 and Tint (3). The full-length 16S rRNA gene has been amplified and cloned. Sequence analysis revealed that the fragment was 1,581 bp long (GenBank Accession No. AJ919994) and shared 99.6% sequence identity with that of the 'Candidatus Phytoplasma solani' reference strain (GenBank Accession No. AF248959). A virtual restriction fragment length polymorphism analysis of the 16S rDNA sequence amplified from the R16F2n/R16R2 primers (2) was performed with iPhyClassifier (4) and pDRAW32. In silico restriction analysis identified the studied papaya phytoplasma as a subgroup 16SrXII-A strain. The sequence had 97 to 98% sequence identity with papaya phytoplasmas of the 16SrXII group in Australia (GenBank Accession No. Y10095), Israel (GenBank Accession No. AY903951), and Cuba (GenBank Accession No. AY725234). The disease incidence was 30 to 35% during the 2006 to 2010 growing seasons, and field surveys indicated that the disease has spread to central Taiwan with sporadic occurrence in recent years. To our knowledge, this is the first report of phytoplasma associated with papaya yellows in Taiwan. References: (1) Y. Arocha et al. Int. J. Syst. Evol. Microbiol. 55:2451, 2005. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) C. D. Smart et al. Appl. Environ. Microbiol. 62:2988, 1996. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Catechin stimulates osteogenesis by enhancing PP2A activity in human mesenchymal stem cells

SUMMARY

Using human mesenchymal stem cells, we identified catechin from a panel of herbal ingredients and Chinese traditional compounds with the strongest osteogenic effects. Catechin increased alkaline phosphatase activity, calcium deposition, and mRNA expression of Runx2 and osteocalcin. We further clarified the signaling pathway that catechin mediated to stimulate osteogenesis.

INTRODUCTION

Human mesenchymal stem cells (hMSCs), useful as a species specific cell culture system for studying cell lineage differentiation, were examined as a tool to identify novel herbal ingredients and Chinese traditional compounds for enhancing osteogenesis.

METHODS

Immortalized and primary hMSCs were induced in osteogenic induction medium in the presence of a variety of herbal ingredients and Chinese traditional compounds and osteogenic differentiation was evaluated by histochemical assays and quantitative RT-PCR.

RESULTS

Using immortalized hMSCs, we first identified catechin, 18β-glycyrrhetinic acid, baishao, and danggui with osteogenic properties, which enhanced calcium deposition at the dose without significant cytotoxic effects. Primary hMSCs were then applied for confirming the osteogenic effects of catechin, which increased alkaline phosphatase activity, calcium deposition, and mRNA expression of Runx2 and osteocalcin. We further found the extracellular signal-regulated kinase (ERK) pathway was downregulated upon stimulation with catechin. Catechin increased the level and activity of protein phosphatases 2A (PP2A) that dephosphorylates ERK kinase (MEK) and ERK. Further, PP2A inhibitor, okadaic acid, abolished the effect of catechin-mediated inactivation of ERK and stimulation of osteogenesis. The blocking effect of okadaic acid on osteogenesis was further reversed by PD98059, a specific inhibitor of MEK. Co-immunoprecipitation revealed the association of PP2A to both MEK and ERK.

CONCLUSIONS

These studies propose catechin enhanced osteogenesis by increasing the PP2A level that inhibits the MEK and ERK signaling in hMSCs. These results prove the concept of using hMSCs as a convenient tool for rapid and consistent screening of the osteogenic herbal ingredients and traditional Chinese compounds.

White-light electroluminescence from ZnO nanorods/polyfluorene by solution-based growth

We report bright white-light electroluminescence (EL) from a diode structure consisting of a ZnO nanorod (NR) and a p-type conducting polymer of poly(fluorine) (PF) fabricated using a hydrothermal method. ZnO NRs are successfully grown on an organic layer of PF using a modified seeding layer. The EL spectrum shows a broad emission band covering the entire visible range from 400 to 800 nm. White-light emission is possible because the ZnO-defect-related emission from the ZnO NR/PF heterostructure is enhanced to become over thousand times stronger than that from the usual ZnO NR structure. This strong green-yellow emission associated with the ZnO defects, combined with the blue PF-related emission, results in the white-light emission. Enhancement of the ZnO-defect emission is caused by the presence of Zn(OH)(2) at the interface between the ZnO NRs and PF. Fourier transform infrared spectroscopy reveals that the absorption peaks at 3441, 3502, and 3574 cm(-1) corresponding to the OH group are formed at the ZnO NR/PF heterostructure, which confirms the enhancement of defect emission from the ZnO NR/PF heterostructure. The processing procedure revealed in this work is a convenient and low-cost way to fabricate ZnO-based white-light-emitting devices.

Epstein-Barr virus nuclear antigen 1 activates transcription from episomal but not integrated DNA and does not alter lymphocyte growth

By binding to a cis-acting element (oriP) in the Epstein-Barr virus (EBV) genome, EBV nuclear antigen 1 (EBNA1) enables persistence and enhances transcription from EBV episomes. To investigate whether EBNA1 also directly affects cell gene transcription, we conditionally expressed a Flag-tagged dominant negative EBNA1 (FDNE) in an EBV immortalized lymphoblastoid cell line, in which the EBV genome is integrated into cell DNA. FDNE induction inhibited expression from an EBNA1-dependent oriP reporter plasmid by more than 90% in these cells but did not affect expression from integrated EBV or oriP reporter DNA. FDNE induction also did not alter expression of more than 1,800 cellular mRNAs. Lymphoblastoid cell line growth under a variety of conditions was unaffected by FDNE induction. Although Gal4-VP16 and EBNA1 strongly activated and coactivated a Gal4-VP16- and oriP-dependent promoter that was on an episome, only Gal4-VP16 activated the promoter when it was integrated into chromosomal DNA. These data indicate that EBNA1 is specifically deficient in activation of an integrated oriP enhancer and does not affect cell growth or gene expression through an interaction with cognate chromosomal DNA.

Characterization of the oxygenated intermediate of the thermophilic cytochrome P450 CYP119

Using UV-Vis, resonance Raman, and EPR spectroscopy we have studied the properties of the oxygenated ferrous cytochrome P450 from Sulfolobus solfataricus, (CYP119). The recently determined crystal structure of CYP119 is compared with other available structures of P450s, and detailed structural and spectroscopic analyses are reported. With several structural similarities to CYP102, such as in-plane iron position and a shorter iron-proximal ligand bond, CYP119 shows low-spin conformation preference in the ferric form and partially in the ferrous form at low temperatures. These structural features can explain the fast autoxidation of the oxyferrous complex of CYP119. Finally, we report the first UV-Vis and EPR spectra of the cryoradiolytically reduced oxygenated intermediate of CYP119. The primary reduced intermediate, a hydroperoxo-ferric complex of CYP119, undergoes a 'peroxide shunt' pathway during gradual annealing at 170-195 K and returns to the low-spin ferric form.

Thiamine deficiency and unexplained encephalopathy in hemodialysis and peritoneal dialysis patients

Patients with end-stage renal disease undergoing regular dialysis are prone to encephalopathy, but the cause is often unclear. Dialysis patients are at risk for thiamine deficiency, which may mimic many uremic complications, including encephalopathy. To determine whether unexplained encephalopathy in regular dialysis patients is associated with thiamine deficiency, we conducted a prospective study that enrolled 30 consecutive dialysis patients with altered mental status admitted to a referred hospital during a 1-year period. A complete history, physical and neurological examinations, laboratory investigations, and computed tomographic scans or magnetic resonance imaging of the brain were obtained for each subject. In 10 of the 30 patients, diagnoses remained obscure after the initial workup. Manifestations included confusion, chorea, acute visual loss, rapidly progressive dementia, myoclonus, convulsions, and coma. Intravenous thiamine was administered to these 10 patients. All 10 patients had thiamine deficiency confirmed by a marked response to thiamine supplementation and/or a low serum thiamine concentration (35.3 +/- 6.0 nmol/L; normal, >50 nmol/L). Nine patients recovered, but one patient failed to respond because of delayed treatment. We conclude that in regular dialysis patients, unexplained encephalopathy can be mainly attributed to thiamine deficiency. This condition is fatal if unrecognized and can be successfully treated with prompt thiamine replacement.

Structural, magnetic and catalytic properties of a self-recognized mu-oxo-bridged diiron(III) bis(benzimidazole) complex

The inherent nonplanarity and C(2) symmetry of the dimethyl-substituted bis(benzimidazole) ligand (Me(2)BBZ) results in two distinct atropisomers that, when separated, have been suggested to have potential for chiral recognition and catalysis. Here is reported the synthesis and characterization of a diiron mu-oxo-bridged bis(benzimidazole) complex, 1, that provides indirect support for this hypothesis. Dimerization of a racemic solution of iron-Me(2)BBZ monomers via the mu-oxo bridge yields (+,+) and (-,-) diastereomers whose complementary association can be attributed to the inherent sidedness of the metal-Me(2)BBZ interaction surface, and to the differences in the torsional angles of the phenyl(benzimidazole) units (34 degrees) and the Schiff base linkages (54 degrees). These results highlight the steric differences between the phenyl(benzimidazole) and Schiff-base portions of the ligand, features that could be important in the chiral recognition of ligands and in differentiating substrate trajectories as required for asymmetric catalysis. For completeness, studies of 1 in the catalytic epoxidation of styrene are also reported.

Synthesis of 6-deoxy-L-idose and L-acovenose from 1,2: 5,6-di-O-isopropylidene-alpha-D-glucofuranose

A practical route toward the synthesis of 6-deoxy-L-idose and L-acovenose from 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose is described. Key steps include the stereoselective hydrogenation of 6-deoxy-1,2:3,5-di-O-isopropylidene-alpha-D-xylo-hex-5-enofuranose, regioselective protection of 6-deoxy-1,2-O-isopropylidene-beta-L-idofuranose at 0-5, and epimerisation of 6-deoxy-5-O-tert-butyldimethylsilyl-1,2-O-isopropylidene-beta-L-idofuranose at C-3.

Maintenance of Epstein-Barr virus (EBV) oriP-based episomes requires EBV-encoded nuclear antigen-1 chromosome-binding domains, which can be replaced by high-mobility group-I or histone H1

EBV-encoded nuclear antigen-1 (EBNA-1) binding to a cis-acting viral DNA element, oriP, enables plasmids to persist in dividing human cells as multicopy episomes that attach to chromosomes during mitosis. In investigating the significance of EBNA-1 binding to mitotic chromosomes, we identified the basic domains of EBNA-1 within amino acids 1-89 and 323-386 as critical for chromosome binding. In contrast, the EBNA-1 C terminus (amino acids 379-641), which includes the nuclear localization signal and DNA-binding domain, does not associate with mitotic chromosomes or retain oriP plasmid DNA in dividing cell nuclei, but does enable the accumulation of replicated oriP-containing plasmid DNA in transient replication assays. The importance of chromosome association in episome maintenance was evaluated by replacing EBNA-1 amino acids 1-378 with cell proteins that have similar chromosome binding characteristics. High-mobility group-I amino acids 1-90 or histone H1-2 could substitute for EBNA-1 amino acids 1-378 in mediating more efficient accumulation of replicated oriP plasmid, association with mitotic chromosomes, nuclear retention, and long-term episome persistence. These data strongly support the hypothesis that mitotic chromosome association is a critical factor for episome maintenance. The replacement of 60% of EBNA-1 with cell protein is a significant step toward eliminating the need for noncellular protein sequences in the maintenance of episomal DNA in human cells.

Chorea induced by thiamine deficiency in hemodialysis patients

Thiamine deficiency is mainly encountered in alcoholics or food faddists, but it may complicate chronic dialysis because of low intake and accelerated loss of thiamine in dialysis patients. We report here 2 hemodialysis (HD) patients who developed chorea induced by thiamine deficiency. We propose that thiamine deficiency, with a consequent dysfunction of the basal ganglia, may induce chorea in HD patients.

Regioselective and stereoselective benzoylation of 2-N-protected 4,6-O-ketal derivatives of D-glucosamines with 1-(benzoyloxy)benzotriazole

A highly regioelective and stereoselective benzoylation of the 2-N-protected 4,6-O-ketal derivatives of D-glucosamines with 1-(benzoyloxy)benzotriazole that affords the corresponding beta anomeric benzoates in excellent yields is described herein.

ESEEM studies of succinate:ubiquinone reductase from Paracoccus denitrificans

Electron spin-echo envelope modulation (ESEEM) spectroscopy has been performed in order to obtain structural information about the environment of the reduced [2Fe-2S] cluster (S-1 center), the oxidized [3Fe-4S] cluster (S-3 center), and the flavin semiquinone radical in purified succinate:ubiquinone reductase from Paracoccus denitrificans. Spectral simulations of the ESEEM data from the reduced [2Fe-2S] yielded nuclear quadrupole interaction parameters that are indicative of peptide nitrogens. We also observed a weak interaction between the oxidized [3Fe-4S] cluster and a peptide 14N. There was no evidence for coordination of any of the Fe atoms to 14N atoms of imidazole rings. The ESEEM data from the flavin semiquinone radical were more complicated. Here, evidence was obtained for interactions between the unpaired electron and only the two nitrogen atoms in the flavin ring.

Inappropriate antidiuresis associated with pituitary adenoma--mechanisms not involving inappropriate secretion of vasopressin

We report an unusual case of inappropriate antidiuresis with undetectable vasopressin in an elderly man presenting with confusion due to severe hyponatremia. Further investigations led to the diagnosis of non-functional pituitary macroadenoma. The patient had normal thyroid and adrenal function. The abnormal water balance resolved promptly after transsphenoidal removal of the tumor, confirmed by a repeat water loading test. We conclude that inappropriate antidiuresis in the absence of excess vasopressin secretion may implicate mass effect from an underlying pituitary tumor.

Parkinson's disease with recurrent pulmonary embolism

A patient with Parkinson's disease was admitted because of recurrent chest pain and dyspnea. Based on high clinical suspicion and a high-probability lung scan, the diagnosis of pulmonary embolism was made. Anticoagulation therapy was administered and the patient remained free of symptoms during the follow-up period of two years. Pulmonary embolism is reported as a possible adverse reaction to levodopa therapy and a frequent, but under-recognized cause of death in patients with parkinsonism. Clinicians should think of pulmonary embolism, a common yet difficult diagnosis, when a parkinsonian patient presents with chest pain and dyspnea.

Synthesis and characterization of the dimethyl-substituted bisbenzimidazole ligand and its manganese complex

Macrocycles with unique properties provide new avenues for the design of novel catalysts and materials. Here, we report, for the first time, the synthesis and characterization of the dimethyl-substituted bisbenzimidazole ligand (Me2BBZ) and its manganese complex (Mn-Me2BBZ). The Me2BBZ ligand is similar to porphyrin and phthalocyanine macrocycles in terms of its cavity size and metal-binding mode, but owing to electronic and charge differences, it exhibits properties that make it distinct from its structural counterparts. For instance, the optical spectra of bisbenzimidazoles lack transitions in the 500-900 nm region. Perhaps the most significant feature of the Me2BBZ ligand, however, is its inherent nonplanarity. Geometric restraints within this nonplanar ligand give rise to two atropisomers, which, when separated, could have potential in chiral catalysis and recognition. In addition, here we show that this nonplanarity can help to promote unusual crystal-packing interactions. Within the structure of the Mn-Me2BBZ complex, intermolecular pi-stacking interactions of the phenyl and benzimidazole groups lead to the formation of a distinct two-dimensional "staircase" lattice comprised of alternating Mn-Me2BBZ atropisomers. The potential significance of this structural arrangement is revealed by temperature-dependent magnetic studies that indicate weak antiferromagnetic coupling between the metal ions in the crystal. Fine-tuning of these long-range electronic and magnetic interactions could be useful for the design of novel molecular materials.

Membrane lysis by the antibacterial peptides cecropins B1 and B3: A spin-label electron spin resonance study on phospholipid bilayers

Custom antibacterial peptides, cecropins B1 (CB1) and B3 (CB3), were synthesized. These peptides have particular sequence characteristics, with CB1 having two amphipathic alpha-helical segments and CB3 having two hydrophobic alpha-helical segments. These differences were exploited for a study of their efficacy in breaking up liposomes, which had different combinations of phosphatidic acid (PA) and phosphatidylcholine (PC), and a study of their lipid binding ability. Binding and nonbinding lysis actions of CB1 and CB3 on liposomes were examined further by electron spin resonance (ESR). The spin-labeled lipids 5'SL-PC, 7'SL-PC, 10'SL-PC, 12'SL-PC, and 16'SL-PC were used as probes. The ESR spectra revealed larger outer hyperfine splittings (2A(max)) for CB1 when the interactions of CB1 and CB3 with liposomes were compared. These observations indicate a larger restriction of the motion of the spin-labeled chains in the presence of CB1. Plots of the effective order parameter at the various probe positions (chain flexibility gradient) versus the peptide-lipid ratio further suggested that the lysis action of CB1 is related to its capacity to bind to the lipid bilayers. In contrast, there is no evidence of binding for CB3. To augment these findings, four spin-labeled peptides, C8SL-CB1, C32SL-CB1, C5SL-CB3, and C30SL-CB3, were also examined for their binding to and their state of aggregation within the lipid bilayers. Association isotherms of the peptides were measured for liposomes containing two molar fractions of PA (0.25 and 0.75). The membrane binding of the CB1 peptides exhibited a cooperative behavior, whereas the association isotherm of CB3 revealed binding to the lipid only for beta = 0.75 liposomes. To further identify the location of CB1 in the lipid bilayers, measurements of the collision rate with chromium oxalate in solution were conducted. Results from ESR power saturation measurements suggested that the NH(2)-terminal alpha-helix of CB1 is located on the surface of the lipid bilayers, whereas the COOH-terminal alpha-helix of CB1 is embedded below the surface of the lipid bilayers. These conclusions were further supported by the observed relationship between the partition distribution of peptides bound to liposomes at different PA/PC ratios and the amounts of free peptides. Based on the above observations, possible mechanisms of the bilayer lysis induced by CB1 and CB3 on liposomes of different composition are discussed.

Oncogenic stimulation recruits cyclin-dependent kinase in the cell cycle start in rat fibroblast

The rat fibroblast NRK cells are transformed reversibly by a combination of growth factors. When stimulated with serum, NRK cells rely on cyclin-dependent kinase 4 (Cdk4) for their S phase entry. However, when stimulated with serum containing oncogenic growth factors, they come to rely on either Cdk4 or Cdk6, and their S phase entry cannot be blocked unless both Cdk4 and Cdk6 are immunodepleted. Such change of dependence does not occur in the NRK cell mutants defective in an oncogenic signal pathway and, therefore, deficient in anchorage-independent cell cycle start ability, correlating Cdk6 dependence with this remarkable, cancer-associated phenotype. However, both Cdk4 and Cdk6 are activated upon serum stimulation, and neither the amounts of Cdk6, Cdk4, cyclin D1, and cyclin-dependent kinase inhibitors nor the activities or subcellular localization of Cdk6 and Cdk4 are significantly influenced by oncogenic stimulation. Thus, oncogenic stimulation invokes Cdk6 to participate in a critical step of the cell cycle start in a rat fibroblast, but by a mechanism seemingly unrelated to the regulation of the kinase. Given that many hematopoietic cells employ predominantly Cdk6 for the cell cycle start and perform anchorage-independent growth by nature, our results raise the possibility that the oncogenic stimulation-induced anchorage-independent cell cycle start of NRK is elicited by a mechanism similar to the one used for hematopoietic cell proliferation.

Massive ascites caused by peritoneal extramedullary hematopoiesis as the initial manifestation of myelofibrosis

An 83-year-old man presented with massive ascites. Cytological examination of the ascites revealed primitive hematopoietic cells. The specimen of bone marrow biopsy disclosed diffuse fibrosis, which suggested myelofibrosis with extramedullary hematopoiesis as the cause of ascites. His symptoms resolved dramatically after administration of hydroxyurea. Ascites formation in myelofibrosis is often attributed to presinusoidal portal hypertension and occurs in the context of well-established disease. This case demonstrates that myelofibrosis may manifest as massive ascites caused by peritoneal implants of myeloid tissues. Extramedullary hematopoiesis should be included in the differential diagnosis of ascites.

Remitting seronegative symmetrical synovitis with pitting edema (RS3PE syndrome)

A 63-year-old man presented with acute symmetrical polysynovitis associated with pitting edema of both the hands and feet. He was seronegative for rheumatoid factor and no radiologically evident erosion was noted in the joints of his hands and feet. Evaluation excluded congestive heart failure, nephrotic syndrome, and hypothyroidism as the cause of edema. Treatment with nonsteroidal anti-inflammatory drugs and low-dose steroids induced complete remission. The clinical manifestations of this patients were consistent with those of a distinctive, although rare, form of arthritis called remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome. This syndrome has a good prognosis in elderly patients.

Escherichia coli nusG mutations that block transcription termination by coliphage HK022 Nun protein

The Escherichia coli nusG gene product is required for transcription termination by phage HK022 Nun protein at the lambda nutR site in vivo. We show that it is also essential for Nun termination at lambda nutL. Three recessive mis-sense nusG mutations have been isolated that inhibit termination by Nun at lambda nutR. The mutations are ineffective in a lambda pL nutL fusion, even when lambda nutR replaces lambda nutL. The mutant strains support lambda growth, indicating that lambda N antitermination activity is not impaired. Transcription arrest by Nun in vitro is stimulated by NusG protein at both lambda nutR and lambda nutL. Mutant NusG protein fails to enhance transcriptional arrest by Nun at either site. The mutant protein, like the wild-type protein, suppresses transcriptional pausing by RNA polymerase and stimulates Rho-dependent termination. These results imply that the role of NusG in Nun termination may be distinct from its roles in other transcription reactions.

Cell cycle start from quiescence controlled by tyrosine phosphorylation of Cdk4

In mammals Cdk4 (or Cdk6 in some cell types) is required for starting the cell cycle. Recently we showed that Cdk4 is regulated by tyrosine phosphorylation and dephosphorylation, and that this regulation is required for a DNA damage-induced G1 arrest. We report here that a generic anti-phosphotyrosine antibody can detect tyrosine-phosphorylated Cdk4 and that as revealed by immunoblot detection and kinase assay, this regulation is employed for DNA damage-responsive checkpoint control during cell cycle start from quiescence. In rat fibroblasts traversing G1 or arrested in G1 by deprivation of anchorage, Cdk4 does not undergo tyrosine phosphorylation. Tyrosine phosphorylation occurs only during cell's arrest in quiescence and dephosphorylation during their cell cycle start. Ultraviolet irradiation blocks dephosphorylation and concomitant activation of Cdk4, thereby preventing the start of cell cycling. Thus, unlike tyrosine phosphorylation of Cdc2, which controls phase transition in the regular cell cycle, tyrosine phosphorylation of Cdk4 is employed for controlling cell cycle start from quiescence in a rat fibroblast.

Epstein-Barr virus-transforming protein latent infection membrane protein 1 activates transcription factor NF-kappaB through a pathway that includes the NF-kappaB-inducing kinase and the IkappaB kinases IKKalpha and IKKbeta

The Epstein-Barr virus oncoprotein latent infection membrane protein 1 (LMP1) is a constitutively aggregated pseudo-tumor necrosis factor receptor (TNFR) that activates transcription factor NF-kappaB through two sites in its C-terminal cytoplasmic domain. One site is similar to activated TNFRII in associating with TNFR-associated factors TRAF1 and TRAF2, and the second site is similar to TNFRI in associating with the TNFRI death domain interacting protein TRADD. TNFRI has been recently shown to activate NF-kappaB through association with TRADD, RIP, and TRAF2; activation of the NF-kappaB-inducing kinase (NIK); activation of the IkappaB alpha kinases (IKKalpha and IKKbeta); and phosphorylation of IkappaB alpha. IkappaB alpha phosphorylation on Ser-32 and Ser-36 is followed by its degradation and NF-kappaB activation. In this report, we show that NF-kappaB activation by LMP1 or by each of its effector sites is mediated by a pathway that includes NIK, IKKalpha, and IKKbeta. Dominant negative mutants of NIK, IKKalpha, or IKKbeta substantially inhibited NF-kappaB activation by LMP1 or by each of its effector sites.

Cerebral air embolism complicating bilevel positive airway pressure therapy

A 13 yr old male with acute lymphoblastic leukaemia who received bilevel positive airway pressure ventilation via a face mask for post-transplant pneumonitis developed subcutaneous emphysema, radiographic evidence of pulmonary interstitial emphysema, pneumomediastinum and 6 h later, right hemiparesis and focal livedo reticularis. This case illustrates that severe barotrauma may complicate noninvasive bilevel positive airway pressure ventilation.

Comparison of fluorescence energy transfer primers with different donor-acceptor dye combinations

Fluorescence energy transfer (ET) primers are far superior to single dye-labeled primers as labels for DNA sequencing and polymerase chain reaction amplification. We compare here ET primers with different donor and acceptor dye combinations with respect to the relative acceptor fluorescence emission intensity and the amount of residual donor fluorescence emission. Primers with the following donor/acceptor pairs were synthesized: 6-carboxyfluorescein/6-carboxy-X-rhodamine (FAM-ROX), 3-(epsilon-carboxypentyl)-3'-ethyl-5,5'-dimethyloxacarbocyanine/ 6-carboxy-X-rhodamine (CYA-ROX), and the 4,4-difluoro-4-bora-3 alpha,4 alpha-diaza-s-indacene-3-propionic acid (BODIPY) derivatives, 5,7-dimethyl-BODIPY/5-(4-phenyl-1,3-butadienyl) BODIPY (BODIPY503/512-BODIPY581/591). Variables examined included the length of the 5'-amino linker arm, the number of base pairs between the donor and acceptor, and the excitation wavelength (488 or 514 nm). Of the primers examined, CYA-ROX primers offer the best combination of acceptor fluorescence emission intensity and spectral purity.

Infective endocarditis complicated with thalamic infarction and mycotic aneurysm rupture: a case report

A 39-year-old female with mitral valve prolapse experienced left side hemisensory disturbance four months after gastric surgery. Echocardiogram disclosed vegetation on the mitral valve and blood cultures showed growth of enterococcus. With a diagnosis of thalamic infarction complicating infective endocarditis, she was hospitalized for further treatment. After four weeks of antibiotic therapy, she developed sudden headache and obtundation. Imaging studies revealed intracerebral hemorrhage (ICH), resulting from mycotic aneurysm rupture. She survived and recovered after emergency craniotomy and evacuation of the hematoma. However, the ICH recurred six weeks later and the patient died after five days in a deep coma. Patients with mitral valve prolapse are common. Those who have systolic murmur or valvular thickening and redundancy are at particular risk of infective endocarditis and should receive antibiotic prophylaxis perioperatively as recommended by the American Heart Association. Clinical manifestations of infective endocarditis and its complications, as in our patient, are often trivial. Prompt diagnosis and intervention are crucial. In view of the poor prognosis associated with ICH due to mycotic aneurysm rupture, we suggest cerebral angiography be performed in patients presenting with focal neurologic deficits or with warning headache for early detection of accessible lesions for excision.

Influence of femoral lengthening on hip joint space in posttraumatic femoral shortening

We performed femoral lengthening for post-traumatic femoral shortening in 14 patients (10 men). The mean age was 26 (17-33) years. The callotasis method was employed using an Orthofix or Hifixator monolateral external fixator. The average length gained was 6 (3-13) cm, equal to 16 (7-36)%. The mean narrowing ratio of the hip joint space during lengthening was 9 (0-26)% and the narrowing persisted at the final follow-up. Cases with narrowing greater than 5% had a longer time between the development of the shortening and the lengthening than the others (p = 0.03). Our findings indicate that femoral lengthening for posttraumatic femoral shortening should be done as early as possible to prevent the development of joint space narrowing during the lengthening procedure.

The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coli RNA polymerase without abolishing its catalytic activities

Bacteriophage HK022 Nun protein blocks transcription elongation by Escherichia coli RNA polymerase in vitro without dissociating the transcription complex. Nun is active on complexes located at any template site tested. Ultimately, only the 3'-OH terminal nucleotide of the nascent transcript in an arrested complex can turn over; it is removed by pyrophosphate and restored with NTPs. This suggests that Nun inhibits the translocation of RNA polymerase without abolishing its catalytic activities. Unlike spontaneously arrested complexes, Nun-arrested complexes cannot be reactivated by transcription factor GreB. The various complexes show distinct patterns of nucleotide incorporation and pyrophosphorolysis before or after treatment with Nun, suggesting that the configuration of RNAP, transcript, and template DNA is different in each complex.

Optimization of spectroscopic and electrophoretic properties of energy transfer primers

We have synthesized and characterized the spectroscopic properties of 56 energy transfer (ET) fluorescent dye-labeled primers differing in (i) the spacing between the donor and acceptor, (ii) the nature of the spacer (either oligonucleotide or polydideoxyribose phosphate), (iii) the primer sequence (M13 (-40), M13 (-21), M13 reverse, SP6, T3, and T7 priming sequences), and (iv) the dyes chosen as the donor (6-carboxyfluorescein, F; or 3-(epsilon-carboxypentyl)-3'-ethyl-5,5'-dimethyloxacarbocyanine, C) and acceptor (F; 5 & 6-carboxyrhodamine-110, R110; 6-carboxyrhodamine-6G, G; N,N,N',N'-tetramethyl-6-carboxyrhodamine, T; and 6-carboxy-X-rhodamine, R) chromophores. This study led to the development of two significantly improved ET primer sets for multiple-color analyses. These primers are named using the convention D-N-A, where D is the donor, A is the acceptor, and N is the number of nucleotides between the donor and the acceptor. The primer set C4R110, C4G, C4T, and C4R provides acceptor emissions of high spectral purity with donor:acceptor emission ratios of < 0.002 for C4G, < 0.004 for C4T, and < 0.005 for C4R and excellent matching in the electrophoretic mobilities of single-base extension DNA fragments. The C4R110, C4G, C4T, and C4R set is valuable for diagnostic applications where minimization of crosstalk between different labels is of particular importance. The set C10R110, C10G, C10T, and C10R, which uses only rhodamine dyes as acceptors, shows significantly improved matching in the electrophoretic mobilities of single-base extension DNA fragments over the previously described set C10F, C10G, C10T, and C10R and is the best available for sequencing.

Microsatellite-based cancer detection using capillary array electrophoresis and energy-transfer fluorescent primers

The development of sensitive, rapid, and accurate methods and apparatus for high-throughput short tandem repeat (STR) analysis will be critical for the use of microsatellite alteration in cancer screening. Here we show that STR-based bladder cancer diagnosis can be performed using capillary array electrophoresis and two-color labeling with energy-transfer (ET) fluorescent primers. Rapid (< or = 35 min) separations are achieved on capillary arrays using replaceable separation matrices and the allelic ratios are quantitatively determined with a precision of +/- 10%. With this precision, a variation of 20% was considered diagnostically significant. These methods provide a significant improvement in the speed, ease, and precision of STR analyses compared to slab gel electrophoresis.

Electron paramagnetic resonance studies of succinate:ubiquinone oxidoreductase from Paracoccus denitrificans. Evidence for a magnetic interaction between the 3Fe-4S cluster and cytochrome b

Electron paramagnetic resonance (EPR) studies of succinate:ubiquinone oxidoreductase (SQR) from Paracoccus denitrificans have been undertaken in the purified and membrane-bound states. Spectroscopic "signatures" accounting for the three iron-sulfur clusters (2Fe-2S, 3Fe-4S, and 4Fe-4S), cytochrome b, flavin, and protein-bound ubisemiquinone radicals have been obtained in air-oxidized, succinate-reduced, and dithionite-reduced preparations at 4-10 K. Spectra obtained at 170 K in the presence of excess succinate showed a signal typical of that of a flavin radical, but superimposed with another signal. The superimposed signal originated from two bound ubisemiquinones, as shown by spectral simulations. Power saturation measurements performed on the air-oxidized enzyme provided evidence for a weak magnetic dipolar interaction operating between the oxidized 3Fe-4S cluster and the oxidized cytochrome b. Power saturation experiments performed on the succinate- and dithionite-reduced forms of the enzyme demonstrated that the 4Fe-4S cluster is coupled weakly to both the 2Fe-2S and the 3Fe-4S clusters. Quantitative interpretation of these power saturation experiments has been achieved through redox calculations. They revealed that a spin-spin interaction between the reduced 3Fe-4S cluster and the cytochrome b (oxidized) may also exist. These findings form the first direct EPR evidence for a close proximity (</=2 nm) of the high potential 3Fe-4S cluster, situated in the succinate dehydrogenase part of the enzyme, and the low potential, low spin b-heme in the membrane anchor of the enzyme.

Effects of continuous distraction on cartilage in a moving joint: an investigation on adult rabbits

An animal model, using distraction force on adult rabbits, was developed to study the effects of nonweight-bearing on articular cartilage in a moving joint. Histologic evaluation was used to compare the morphology of chondrocytes, safranin O intensity, cartilage thickness, and structural changes between the test and contralateral joints. At 3 and 6 weeks, the chondrocytes in superficial and intermediate zones were round, with an increase in cellular volume density and mean cell volume and with less metachromasia; the safranin O intensity and cartilage thickness were the same as in the controls. In cartilage of the 9-week group, mean cell volume decreased with cell cloning in the superficial zone, while numerical density increased and mean matrix volume per cell decreased in the superficial and intermediate zones. The cartilage, with a 34% reduction in thickness and a 53-72% decrease in safranin O intensity from the superficial to the deep zone, had superficial fibrotic proliferation, surface erosion or depression, and tidemark irregularity. Continuous distraction in a moving joint caused morphological changes in chondrocytes prior to degeneration of cartilage. These results support the hypothesis that the forces perceived by cells may dictate their shape and then stimulate alterations in cellular biochemistry and matrix metabolism.

Mechanism of human alpha-1,3-fucosyltransferase V: glycosidic cleavage occurs prior to nucleophilic attack

alpha-1,3-Fucosyltransferase V (FucT V) catalyzes the transfer of 1-fucose from the donor sugar guanosine 5'-diphospho-beta-1-fucose (GDP-Fuc) to an acceptor sugar. A secondary isotope effect on the fucosyltransfer reaction with guanosine 5'-diphospho-[1-2H]-beta-1-fucose (GDP-[1-2H]-Fuc) as the substrate was observed and determined to be Dv = 1.32 +/- 0.13 and DV/K = 1.27 +/- 0.07. Competitive inhibition of FucT V by guanosine 5'-diphospho-2-deoxy-2-fluoro-beta-1-fucose (GDP-2F-Fuc) was observed with an inhibition constant of 4.2 microM which represents the most potent inhibitor of this enzyme to date. Incubation of GDP-2F-Fuc with FucT V and an acceptor molecule prior to the addition of GDP-Fuc had no effect on the potency of inhibition, indicating that GDP-2F-Fuc is neither an inactivator nor a slow substrate. Both the observed secondary isotope effect and the inhibition by GDP-2F-Fuc are consistent with a charged, sp2-hybridized, transition-state structure. A convenient and efficient synthesis of GDP-[1-2H]-Fuc and GDP-2F-Fuc and a nonradioactive, fluorescence assay for fucosyltransferase activity have been developed.

Cyanine dyes with high absorption cross section as donor chromophores in energy transfer primers

Energy transfer (ET) fluorescent primers are significantly superior to single dye-labeled primers for DNA sequencing and multiplex genetic analyses (Ju, J., Glazer, A. N., and Mathies, R. A. (1996) Nature Med. 2, 246-249). We describe here ET primers in which a donor chromophore with a large absorption cross section but a low fluorescence quantum yield is exploited to increase the Stokes-shifted fluorescence emission of acceptor dyes. The new ET primers have 3-(epsilon-carboxy-pentyl)-3'ethyl-5,5'-dimethyloxacarbocyanine (CYA; epsilon M488nm 142,000 M-1 cm-1) at the 5' -end as a common energy donor, and fluorescein or rhodamine derivatives (FAM, R6G, TAMRA, and ROX), attached to a modified thymidine 10 bases away within the primer sequence, as acceptors. With 488-nm excitation, the fluorescence emission intensity of these four ET primers is 1.4- to 24-fold stronger than that of the corresponding primers labeled only with the single acceptor dye. When compared with the corresponding ET primers with a fluorescein derivative (FAM; epsilon M488nm 60,000 M-1 cm-1) as donor, the fluorescence emissions of primers with CYA as donor and FAM, R6G, TAMRA, and ROX as acceptors are respectively 0.8-, 1.0-, 1.7-, and 1.7-fold as intense. The low fluorescence quantum yield of the CYA donor resulted in distinct fluorescence signals for the DNA-sequencing fragments with much lower crosstalk between the four detection channels than that seen with ET primers based on a FAM donor. With single-stranded M13mp18 DNA as the template, the CYA ET primers provided DNA sequences on a four-color capilary sequencer with 100% accuracy in the first 500 bases.

Narrowing of the joint space of the hip after traumatic shortening of the femur

Femoral lengthening has been associated with narrowing of the joint space at the hip. We have studied the joint space before lengthening in 20 patients with a short femur due to a femoral-shaft fracture (15) or distal femoral epiphyseal injury (5). Their mean age at injury was 16 years (3 to 27) and the mean shortening was 5.4 cm (1.1 to 14). We found that the hip joint space of the shortened femur was significantly narrower (p < 0.001) than that on the normal side, with a mean narrowing ratio of 15.5% (-5 to +43). The narrowing ratio was directly related to the period spent non-weight-bearing (p < 0.001), but not to the amount of femoral shortening. We have shown that the joint space of the hip in patients with post-traumatic femoral shortening was narrowed even before femoral lengthening had been started.

Energy transfer primers with 5- or 6-carboxyrhodamine-6G as acceptor chromophores

Energy-transfer (ET) fluorescent primers for DNA sequencing and multiplex genetic analysis (Ju, J., Ruan, C., Fuller, C. W., Glazer, A. N., and Mathies, R. A. (1995) Proc. Natl. Acad. Sci. USA 92, 4347-4351) are named according to the convention D-N-A, where D is the donor, N is the number of bases between the donor and the acceptor, and A is the acceptor. Thus, a primer that carries 6-carboxyfluorescein (FAM) at the 5'-end and 6-carboxy-4', 5'-dichloro-2',7'-dimethoxyfluorescein (JOE) attached to a modified thymidine 10 bases away is designated F10J. We describe here new ET primers, with 5- or 6-carboxyrhodamine-6G (G5 or G6) as acceptors (with FAM as the donor) in place of JOE, with improved match in the electrophoretic mobilities of the DNA fragments extended from the ET dye-labeled primers, and less overlap in the fluorescence emission of the various labeled DNA fragments. This reduced spectral overlap is most likely due to the narrower emission from G5 or G6 in F10G compared to that from JOE in F10J. With single-stranded M13mp18 DNA as the template, a typical run with F10G6 and three other ET primers on a capillary sequencer provided DNA sequences with 99% accuracy in the first 620 bases.

Callus formation in femur and tibia during leg lengthening: 7 patients examined with DXA

We examined the callus formation during leg lengthening in 7 achondroplastic patients who underwent 3 bilateral femoral and 4 bilateral tibial lengthenings. Bone mineral content and bone mineral density (BMD) in the lengthened callus space were evaluated every 1 or 2 weeks for 10 weeks after the start of distraction using dual energy X-ray absorptiometry. The mean rate of callus mineralization in femurs (0.64 g/wk) was higher than in tibias (0.22 g/wk). The mean BMD at 10 weeks after the start was 0.35 g/cm2 in the femur and 0.14 g/cm2 in the tibia. Different rates of callus formation in different kinds of long tubular bones have not been reported previously.

Effects of ultraviolet light irradiation in biotreatment of organophosphates

Excess biomass accumulation in reactor biodegradation processes is undesirable: it increases the disposal cost and upsets the operation of biological reactors if not properly controlled. In this study, we investigated the feasibility of using ultraviolet (UV) light irradiation to reduce biomass accumulation and increase the specific biodegradation activity. UV irradiation has been widely used to introduce DNA damage in bacteria. Here we apply this technology to the biodegradation of organophosphates by recombinant Escherichia coli strains that contain a recA mutation and a cloned organophosphate hydrolase gene. We show that the recA negative strains after UV irradiation reduce the growth rate but increase the specific organophosphate hydrolase activity. This increase in specific enzyme activity is not owing to continued protein synthesis from the plasmid after the damage of chromosomal DNA by UV irradiation. Rather, it is likely to be caused by an increase in membrane permeability to the substrate. Kinetic analysis suggests that the membrane transport of paraoxon is the rate-limiting step in its biodegradation.