A supramolecular polymer-collagen microparticle slurry for bone regeneration with minimal growth factor

Recombinant bone morphogenetic protein-2 (BMP-2) is a potent osteoinductive growth factor that can promote bone regeneration for challenging skeletal repair and even for ectopic bone formation in spinal fusion procedures. However, serious clinical side effects related to supraphysiological dosing highlight the need for advances in novel biomaterials that can significantly reduce the amount of this biologic. Novel biomaterials could not only reduce clinical side effects but also expand the indications for use of BMP-2, while at the same time lowering the cost of such procedures. To achieve this objective, we have developed a slurry containing a known supramolecular polymer that potentiates BMP-2 signaling and porous collagen microparticles. This slurry exhibits a paste-like consistency that stiffens into an elastic gel upon implantation making it ideal for minimally invasive procedures. We carried out in vivo evaluation of the novel biomaterial in the rabbit posterolateral spine fusion model, and discovered efficacy at unprecedented ultra-low BMP-2 doses (5 μg/implant). This dose reduces the growth factor requirement by more than 100-fold relative to current clinical products. This observation is significant given that spinal fusion involves ectopic bone formation and the rabbit model is known to be predictive of human efficacy. We expect the novel biomaterial can expand BMP-2 indications for difficult cases requiring large volumes of bone formation or involving patients with underlying conditions that compromise bone regeneration.

Correlation of polyp grading scales with patient symptom scores and olfaction in chronic rhinosinusitis: a systematic review and meta-analysis

BACKGROUND

Various nasal polyp (NP) scoring systems have been proposed and used in the literature. However, no single system has been identified as superior. Correlations between NP scoring systems and patient symptoms, quality of life (QOL) or olfaction vary widely.

METHODS

A systematic search of PubMed, CINAHL, Scopus, and Cochrane Library was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline. Any study examining endoscopy scores and symptom, QOL or olfaction measures in cross sectional manner or after therapeutic intervention were included.

RESULTS

This review identified 55 studies for a pooled meta-analysis of Lund-Kennedy (LK-NP) polyp scores (N = 6), Meltzer scores (N = 6), Nasal polyp scores (NPS; N = 19), Total polyp score (TPS; N=8) Lilholdt scores (N = 8), Olfactory cleft endoscopy score (OCES; N =4), Discharge, inflammation, polyp/edema score (DIP; N = 2), and Perioperative sinus endoscopy score (POSE; N = 2). Meta-regression assessed correlations between NP grading systems and SNOT-22, nasal congestion scores, total nasal symptom scores (TNSS), and Smell Identification Test-40 (SIT40). None of the NP grading systems correlated significantly with any symptom, QOL or olfactory metric. In intervention studies of surgery or monoclonal antibody treatment, changes in NPS scores did not correlate with any patient reported outcome measure (PROM) or olfactory outcomes.

CONCLUSION

Current NP endoscopic scoring systems are not associated with PROMs such as SNOT-22, nasal congestion scores, and TNSS as well as objective measures of olfaction. NP grading systems with improved clinical utility are needed.

Recombinant soluble apyrase APT102 inhibits thrombosis and intimal hyperplasia in vein grafts without adversely affecting hemostasis or re-endothelialization

Essentials New strategies are needed to inhibit thrombosis and intimal hyperplasia (IH) in vein grafts (VG). We studied effects of apyrase (APT102) on VGs and smooth muscle and endothelial cells (SMC/EC). APT102 inhibited thrombosis, SMC migration, and IH without impairing hemostasis or EC recovery. Apyrase APT102 is a single-drug approach to inhibit multiple processes that cause VG failure.

SUMMARY

Background Occlusion of vein grafts (VGs) after bypass surgery, owing to thrombosis and intimal hyperplasia (IH), is a major clinical problem. Apyrases are enzymes that scavenge extracellular ATP and ADP, and promote adenosine formation at sites of vascular injury, and hence have the potential to inhibit VG pathology. Objectives To examine the effects of recombinant soluble human apyrase, APT102, on platelets, smooth muscle cells (SMCs) and endothelial cells (ECs) in vitro, and on thrombosis and IH in murine VGs. Methods SMC and EC proliferation and migration were studied in vitro. Inferior vena cava segments from donor mice were grafted into carotid arteries of recipient mice. Results APT102 potently inhibited ADP-induced platelet aggregation and VG thrombosis, but it did not impair surgical hemostasis. APT102 did not directly inhibit SMC or EC proliferation, but significantly attenuated the effects of ATP on SMC and EC proliferation. APT102 significantly inhibited SMC migration, but did not inhibit EC migration, which may be mediated, at least in part, by inhibition of SMC, but not EC, migration by adenosine. At 4 weeks after surgery, there was significantly less IH in VGs of APT102-treated mice than in control VGs. APT102 significantly inhibited cell proliferation in VGs, but did not inhibit re-endothelialization. Conclusions Systemic administration of a recombinant human apyrase inhibits thrombosis and IH in VGs without increasing bleeding or compromising re-endothelialization. These results suggest that APT102 has the potential to become a novel, single-drug treatment strategy to prevent multiple pathologic processes that drive early adverse remodeling and occlusion of VGs.

Routine transradial access for conventional cerebral angiography: a single operator's experience of its feasibility and safety

The purpose of this study is to describe a single operator's experience with the feasibility and safety of transradial access in conventional cerebral angiography. 153 patients were enrolled consecutively. Among them, 20 patients were not suitable for transradial access. A Simmons catheter was used. Haemostasis was achieved using a compressive dressing of the wrist. We analysed the success rates of the arterial puncture and the successful catheterization rate for each supra-aortic vessel as well as all complications. The arterial access was successful in 96.3%. The supra-aortic vessels were catheterized with success rates of 99.2% (127/128) for the left subclavian artery and 100% for the other arteries. The mean procedure time was 19.3 min (range 10-55 min). Haemostasis was successfully achieved in every case. The most frequent complication was arm pain which occurred in 37 patients (28.9%). In conclusion, transradial selective cerebral angiography with a reversed-angle catheter is technically feasible and safe. It might be helpful in imaging follow-up of patients with arterial stenting or coil embolisation of the cerebral aneurysms. Modification of the catheter design is required to improve the selectivity of the supra-aortic branches.

Phosphorylation of purified recombinant hepatitis B virus-X protein by mitogen-activated protein kinase and protein kinase C in vitro

The recombinant human hepatitis B virus-X protein (rhHBx) has been expressed as inclusion bodies in Escherichia coli and purified. By sequential dialysis of urea, rhHBx was folded into the native structure, which was demonstrated by both the efficacy of its transcriptional activation of the adenovirus major late promoter, fluorescence and circular dichroism (CD) analysis. The increase in CD values at 220 nm and a corresponding blue shift of the intrinsic fluorescence emission confirmed the ability of HBx to refold in lower concentrations of urea to produce the active protein. After purification and renaturation, the rhHBx protein was found to be phosphorylated by protein kinase C (PKC) and mitogen-activated protein kinase (MAPK). In vivo phosphorylation of HBx was also demonstrated. Although PKC and MAPK enhance the HBx phosphorylation in vitro, neither protein kinase A nor caseine kinase II (CKII) phosphorylate HBx protein, though there are possible substrate residues of both kinases in HBx protein. Phosphoamino acid analysis of the total acid hydrolyzed HBx showed that serine residues can be phosphorylated by PKC or MAPK.

Functional prediction: identification of protein orthologs and paralogs

Orthologs typically retain the same function in the course of evolution. Using beta-decarboxylating dehydrogenase family as a model, we demonstrate that orthologs can be confidently identified. The strategy is based on our recent findings that substitutions of only a few amino acid residues in these enzymes are sufficient to exchange substrate and coenzyme specificities. Hence, the few major specificity determinants can serve as reliable markers for determining orthologous or paralogous relationships. The power of this approach has been demonstrated by correcting similarity-based functional misassignment and discovering new genes and related pathways, and should be broadly applicable to other enzyme families.

Drug-resistant pulmonary tuberculosis in a tertiary referral hospital in Korea

OBJECTIVES

To estimate the resistance rate and to correlate the clinical characteristics of resistant tuberculosis with the patients of pulmonary tuberculosis who were referred to the university hospital.

METHODS

We prospectively performed sensitivity tests for all patients who were diagnosed as active tuberculosis by sputum smear or sputum culture from January, 1995 to June, 1996. Patients profile, previous treatment history, patterns of drug resistance, initial chest films and other clinical findings were analysed.

RESULTS

Overall, 24(26.0%) of the 92 patients had resistance to at least one drug and 8(8.6%) had resistance to isoniazid(INH) and rifampin(RFP). Among the 66 patients without previous tuberculosis therapy, 11(16.6%) were drug-resistant and 2(3.0%) were multi-drug resistant. Among the 26 patients with previous therapy, 13(50.0%) were drug-resistant and 6(23.0%) were multi-drug resistant. For all 92, resistance to INH was most common (19.5%), followed by RFP (9.7%) and ethambutol (9.7%). Drug resistance was significantly high in previously treated patients and in cavity-positive patients. Treatment failure was also high in previously treated patients with resistant tuberculosis. In patients with primary resistance, treatment failure was not observed.

CONCLUSION

Sensitivity tests are strongly recommended in all culture positive patients with previous therapy but, in patients with primary resistance, sensitivity tests are not required. Proper combination chemotherapy should be given under careful surveillance.

Determination of serine hydroxymethyltransferase and reduced folate pools in tissue extracts

Serine hydroxymethyltransferase (SHMT) from all sources tested catalyzes the slow exchange of the pro-2S proton of glycine with solvent protons. In the presence of tetrahydrofolate (H4PteGlun) this exchange rate is increased by about three orders of magnitude. This H4PteGlun-dependent exchange has been developed into a rapid and sensitive assay for both SHMT and H4PteGlun and the one-carbon derivatives of H4PteGlun. The procedure involves incubating [2-3H]glycine, H4PteGlun, and SHMT for 3 min followed by a separation of the exchanged protons in the solvent from the substrate glycine on a small Dowex-50 cation-exchange column at pH 2. In the presence of an excess of H4PteGlun the exchange rate is proportional to nanogram levels of SHMT. In the presence of an excess of SHMT the exchange rate is directly proportional to the concentration of H4PteGlun in the 0.1 to 1 pmol range. The concentration of one-carbon derivatives of H4PteGlun is determined by a preincubation of cell extracts with enzymes that convert each derivative into H4PteGlun. A complete reduced folate pool analysis of a tissue extract can be obtained in less than 2 h once a standard curve has been prepared for H4PteGlun. The method does not distinguish between mono- and polyglutamate forms of the coenzyme.

Role of cytosolic serine hydroxymethyltransferase in one-carbon metabolism in Neurospora crassa

Conidiospores of wild type and two mutant strains of Neurospora crassa were grown on [3-13C]serine, [2-13C]glycine, or [13C]formate. Acid extracts of the mycelia were analyzed by 13C NMR for incorporation of the 13C label into choline, serine, and adenine. The goal was to elucidate the function of cytosolic serine hydroxymethyltransferase by comparison of a mutant strain lacking this activity and requiring formate for optimal growth (for mutant strain) to the wild-type strain and the ser3 strain which cannot convert glucose to serine. The results for both the wild-type and ser3 strains showed that the one-carbon adduct of the cytosolic pool of methylenetetrahydrofolate is formed primarily and preferably from C3 of serine. Both organisms could form methylenetetrahydrofolate from formate in the absence of serine and glycine. However, the for mutant strain was restricted in its ability to form methylenetetrahydrofolate from C3 of serine, preferring formate as the one-carbon source. All three strains had an active glycine cleavage complex and mitochondrial serine hydroxymethyltransferase. The formate requirement of the for mutant strain appears to be the result of the inability to form formate in the mitochondria from serine or glycine at a rate sufficient to sustain the biosynthetic pools of methylenetetrahydrofolate and 10-formyltetrahydrofolate in the cytosol. All three strains rapidly accumulated serine from the media to form high intracellular levels of this substrate. However, these strains did not accumulate either glycine or formate from the media at levels that could be detected by 13C NMR.

pH dependence of enzyme reaction rates and deuterium isotope effects on the reduction of a new mechanism-based substrate by dihydrofolate reductase DHFR

The enzyme kinetics of the reduction of the substrate 6,8-dimethylpterin by chicken and recombinant human dihydrofolate reductases (DHFRs) have been examined over the pH range 5.0-8.0 in the presence of NADPH or (4R)-[2H]NADPH (NADPD). The pH profiles of the catalytic constant (Vmax/[E]o or kcat) showed pH independence for chicken DHFR and little pH dependence for human DHFR. For both DHFRs, the pH profiles of the Michaelis constant (Km(substrate)) and the apparent second-order rate constant (Vmax/Km(substrate)[E]o or kcat/Km(substrate)) indicated that two ionizable groups, deduced to be the substrate and the conserved Glu carboxy group in the enzyme active site, should be ionized in their cationic and anionic forms, respectively, for formation of the enzyme-substrate complex and for catalysis. The pKa values of about 5.3 and 6.5 which were obtained from the pH profiles of Km(substrate) and kcat/Km(substrate) were assigned to the ionizations of the substrate and the enzyme carboxy group, respectively. Deuterium isotope effects on DV and d(V/K) were significant for both enzymes, approximately 3 for chicken DHFR and approximately 4 for recombinant human DHFR, and were pH independent. Thus, the rate-limiting step in the enzymic reduction of 6,8-dimethylpterin is hydride-ion transfer at acidic pHs as well as neutral pHs. The results demonstrate that, compared with dihydrofolate, 6,8-dimethylpterin is a superior substrate for mechanistic investigations as it allows direct study of the effects of both enzyme and substrate ionizations involved in the catalysis and also avoids the obscuration of the catalytic rate by product release.

A method of preparation and purification of (4R)-deuterated-reduced nicotinamide adenine dinucleotide phosphate

(4R)-Deuterated-reduced nicotinamide adenine dinucleotide phosphate, (4R)-[2H]NADPH, was prepared by reduction of NADP+ using an NADP(+)-dependent alcohol dehydrogenase (EC 1.1.1.2) from Thermoanaerobium brockii and isopropanol-d8 as substrate at 43 degrees C, pH 9. More than 80% of the product was identified as reduced cofactor by reverse-phase (ODS) HPLC, and a 1H NMR study showed that all of the reduced cofactor was (4R)-deuterated. Less than 10% of the product was oxidized cofactor, the remainder being impurities from the breakdown of the dinucleotide compound. Subsequent purification carried out by semipreparative reverse-phase HPLC with 0.1 M NaCl at pH 8.5 gave a compound of more than 96% purity. Separated (4R)-[2H]NADPH fractions were freeze-dried and the white solid was stored at 5 degrees C with desiccant.

Ionization state and pKa of pterin-analogue ligands bound to dihydrofolate reductase

The ionization state and pKa of the inhibitor 6,8-dimethyl-N5-deazapterin bound to the recombinant human dihydrofolate reductase (rhH2folate reductase) complex with NADPH was determined by a spectrofluorimetric method. The excitation spectra for bound ligand as a function of pH from 6.1 to 9.7 indicated it was the same cationic form as for unbound ligand, which is protonated on N3. However, the lower limit for the pKa of the bound form was determined to be 9.1, a value about pH 2.5 higher than that for free ligand, indicating that ligand bound to the enzyme is protonated at neutral pH. The excitation spectra for bound ligand as a function of pH were generated by computer simulation by employing corrections for the pH dependence of the proportion of bound ligand (variable Kd; ligand-dissociation constant) and taking account of the different pKa values for bound and unbound forms. A plot of Kd values against pH showed a bell-shaped curve indicating that 6,8-dimethyl-N5-deazapterin bound to rhH2folate reductase.NADPH to form a ternary complex of ionised enzyme with protonated ligand and/or protonated enzyme with unprotonated ligand; the spectrofluorimetric results are consistent with the first alternative.

pH-dependence of the structure and degradation of 8-alkyl-substituted pterins

Structures of 8-(2-hydroxyethyl)pterins (8-11) investigated using 1H- and 13C-NMR and UV/vis spectroscopies showed a complex dependence on pH, solvent and 6,7-substitution pattern. In acid, only one cation was observed for all the pterins. In neutral aqueous solution, only one neutral form, the normal quinonoid tautomer, was observed for 7-unsubstituted pterins 9 & 11, but two neutral tautomeric forms, quinonoid and 7-exo-methylene, were observed for 7-CH3 substituted pterins 8 & 10 with 70% and 92%, respectively, of quinonoid. The neutral pterins in MeOH, however, showed a different distribution of structural forms: quinonoid and a five-membered intramolecular ether forms were observed for 7-unsubstituted pterins 9 & 11 as 60% and 25%, respectively, of quinonoid, while quinonoid and 7-exomethylene forms were observed for 7-CH3 substituted pterins 8 & 10 as 10% and 50%, respectively, of quinonoid. In base, for 7-unsubstituted pterins 9 & 11 only the intramolecular ether forms were observed, while for the 7-CH3 substituted pterins 8 & 10 two anion forms, the 7-exo-methylene and intramolecular ether, were observed in the ratio 2:1. Investigation of the distinctive proton-resonance pattern of the ethanomoiety of the intramolecular ether anion of 9 using 600 MHz NMR and spectrum simulation, indicated all four protons have different chemical environments. One conformation of the cyclic-ether ring satisfying the experimental data has been deduced, and the conformational energetics of the ring studied further using AM1 semiempirical quantum chemical calculations. Structural distributions of 8-methylpterins 12-15 were also studied in base only. These showed the 7-unsubstituted pterins 13 & 15 existed solely as the hydrated anion forms, while the 7-CH3 substituted pterins 12 & 14 existed predominantly as the 7-exo-methylene anions. Spectroscopic investigations of the degradation processes of 8-(2-hydroxyethyl)pterins and 8-methylpterins in base indicated a complex pattern of oxidation, ring opening and elimination reactions as a function of time. Using authentic samples, the 7-oxo compounds 16 & 17 and ethanolamine were identified, and evidence for ring-opened forms was obtained by comparison with the relevant 2,5-diamino-6-alkyl-aminopyrimidin-4(3H)-ones 1 & 2. Characteristically different degradation pathways for 7-CH3 and 7-unsubstituted compounds were established.

[A case of paragonimiasis in the abdominal subcutaneous tissue]

A 35-year-old housewife living in Seoul complained of a recurrent palpable abdominal mass. Excisional biopsy was done. The cystic mass showed an immature worm of Paragonimus sp. in the cyst cavity. It measured 7 x 4 mm and showed well-developed oral and ventral sucker, uterus, 5-branched ovary and intestine after acetocarmine staining. But the testes and vitelline duct were not developed fully and there was no egg in the uterus. The patient has eaten raw fish. The case of ectopic paragonimiasis in the abdominal subcutaneous tissue was presented.