Efficacy and safety of bicyclol for treating patients with antituberculosis drug-induced liver injury

BACKGROUND: Bicyclol was used for treating idiosyncratic acute drug-induced liver injury (DILI) in a phase II trial. This study was aimed at evaluating the efficacy and safety of bicyclol 25 and 50 mg thrice a day (TID) for treating acute DILI caused by anti-TB drugs in the light of the trial results.METHODS: We analysed clinical data of patients with TB drug-induced DILI in the trial database. The primary endpoint was reduction in serum alanine aminotransferase (ALT) levels after 4 weeks of treatment compared to baseline.RESULTS: Overall, 148 patients were included, with respectively 48, 52 and 48 patients included in the control (456 mg polyene phosphatidylcholine TID), high-dose (50 mg bicyclol TID) and low-dose (25 mg bicyclol TID) groups. ALT levels decreased by respectively â-"149.0 (IQR â-"299.3 to â-"98.3 (), â-"225.5 (IQR â-"309.3 to â-"181.8 ) and â-"242.5 (IQR â-"364.8 to â-"153.8) U/L in the control, high-dose and low-dose groups (P < 0.001). The ALT normalisation rates at weeks 1, 2, 4, 6 and 8 were higher in the high- and low-dose groups, while adverse events and serious adverse events were similar across groups.CONCLUSIONS: Bicyclol (25 and 50 mg TID) is effective and safe in treating anti-TB DILI, and bicyclol 50 mg TID showed higher efficacy.

Corrigendum: Pharmacokinetics and bioequivalence study of esomeprazole magnesium enteric-coated tablets 20 mg in healthy Chinese subjects under fasting and fed conditions

[This corrects the article DOI: 10.3389/fphar.2023.1169103.].

Pharmacokinetics and bioequivalence study of esomeprazole magnesium enteric-coated tablets 20 mg in healthy Chinese subjects under fasting and fed conditions

Objective: The main purpose of this study was to evaluate the pharmacokinetics, bioequivalence, and safety properties between a new generic and a brand reference formulation of esomeprazole enteric-coated tablets 20 mg in healthy Chinese subjects under fasting and fed conditions. Methods: The fasting study was an open-label, randomized, two-period crossover study conducted in 32 healthy Chinese volunteers, and the fed study was a four-period crossover study conducted in 40 healthy Chinese volunteers. Blood samples were collected at the specified time points and determined to obtain the plasma concentrations of esomeprazole. The primary pharmacokinetic parameters were calculated using the non-compartment method. Bioequivalence was analyzed by the geometric mean ratios (GMRs) of the two formulations and the corresponding 90% confidence intervals (CIs). The safety of the two formulations was assessed. Results: The fasting and fed study showed that the pharmacokinetics of the two formulations was similar. Under the fasting condition, the 90% CIs of GMRs of the test-to-reference formulation were 87.92%-104.36% for C_max, 87.82%-101.45% for AUC_0-t, and 87.99%-101.54% for AUC_0-∞; under the fed condition, the 90% CIs of GMRs of the test-to-reference formulation were 80.53%-94.95% for C_max, 87.46%-97.26% for AUC_0-t, and 87.46%-97.16% for AUC_0-∞. The 90% CIs of GMRs fall within the bioequivalence range of 80.00%-125.00%. The two formulations had good safety and were well-tolerated, and no serious adverse events occurred. Conclusion: According to relevant regulatory standards, esomeprazole enteric-coated generic and reference products exhibited bioequivalence and good safety in healthy Chinese subjects. Clinical Trials Registration: http://www.chinadrugtrials.org.cn/index.html, identifier CTR20171347 and CTR20171484.

The effect of food on the pharmacokinetics of WXFL10203614, a potential selective JAK1 inhibitor, in healthy Chinese subjects

Objective: This study was performed to investigate the effect of food on the pharmacokinetics (PK) of WXFL10203614 in healthy Chinese subjects. Methods: This was a randomized, open-label, single-dose, two-treatment (fed vs fasted), two-period, two-sequence, crossover study. 14 eligible subjects were averagely randomized into 2 sequences and then received 10 mg WXFL10203614 under fasted or fed condition. In each period, the blood samples were collected from 0 h (pre-dose) and serially up to 72 h post-dose, and plasma concentrations were detected using the high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. The effect of food on the PK profile and safety of WXFL10203614 were assessed. Results: 70 subjects were screened, and 14 subjects (10 male and 4 female) were enrolled and completed the study. Under the fasted condition, WXFL10203614 was absorbed rapidly with a T_max of 0.98 h. The absorption rate was slower, T_max delayed by 2.98 h, and the C_max decreased by 16.3% when WXFL10203614 administered after the high-fat and high-calorie diet, other PK parameters were not affected. The 90% confidence intervals (CIs) for the ratio (fed/fasted) of geometric means of the C_max, AUC_0-t and AUC_0-∞ were 0.73-1.01, 0.90-1.03 and 0.90-1.03, indicating that the high-fat and high-calorie diet might impact the absorption process of WXFL10203614. Although the C_max was slightly decreased, there was no significant difference in the C_max under fasted and fed conditions. Thus, it was not considered clinically significant owing to the small magnitude of changes in C_max. All Treatment-emergent adverse events (TEAEs) were mild and resolved spontaneously without treatment. Conclusion: Food had no clinically relevant effects on drug system exposure of WXFL10203614. It was well tolerated under fasted and fed conditions in healthy Chinese subjects, so WXFL10203614 could be administered orally with or without food. Clinical Trial Registration: http://www.chinadrugtrials.org.cn/index.html, identifier CTR20191636.

Safety, tolerability and pharmacokinetics of WXFL10203614 in healthy Chinese subjects: A randomized, double-blind, placebo-controlled phase Ⅰ study

Objective: This study was conducted to investigate the safety, tolerability and pharmacokinetics (PK) of WXFL10203614 after single and multiple oral doses in healthy Chinese subjects.

Methods: A single-center, randomized, double-blind, placebo-controlled phase Ⅰ study was performed on healthy Chinese subjects. In the single-dose study, Subjects were randomized into 7 dose levels of WXFL10203614 (1 mg group, n = 2; 2, 5, 10, 17, 25 and 33 mg groups with placebo, 8 subjects per group, 2 of them given placebo). In the multiple-dose study, subjects received 5 or 10 mg WXFL10203614 once daily (QD), 5 mg twice daily (BID) or placebo for 7 consecutive days. Safety, tolerability and PK of WXFL10203614 were all assessed.

Results: A total of 592 subjects were screened, 50 subjects were enrolled in the single-dose study and 30 in the multiple-dose study. All adverse events (AEs) were mild or moderate and resolved spontaneously. No Serious Adverse Events (SAEs) or deaths were reported during the study. WXFL10203614 was absorbed rapidly after dosing with Tmax of 0.48–0.98 h, Cmax, AUC0-t and AUC0-∞ were all increased in a dose-related manner over the range of 1–33 mg. Renal excretion was the major route of elimination of WXFL10203614. Steady-state PK parameters (Cmax,ss, AUC0-t,ss and AUC0-∞,ss) were elevated after once-daily administration of 5–10 mg WXFL10203614 and non- and weak drug accumulations were observed, whereas moderate drug accumulation occurred in the 5 mg BID group.

Conclusion: WXFL10203614 exhibited good safety, tolerability and favorable PK profiles in healthy Chinese subjects, supporting further clinical development in patients with rheumatoid arthritis.

Clinical Trials Registration Number:http://www.chinadrugtrials.org.cn/index.html, #CTR20190069 and CTR20200143.

Comparative Pharmacokinetics, Safety, and Immunogenicity Study of the Prefilled Syringe and Lyophilized Formulation of a Recombinant Human Tumor Necrosis Factor-α Receptor II:lgG Fc Fusion Protein in Healthy Chinese Male Subjects

This study aimed to compare the pharmacokinetics, safety, and immunogenicity of the prefilled syringe (PFS) with lyophilized (LYO) recombinant human tumor necrosis factor-α receptor II:lgG Fc fusion protein (rhTNFR:Fc) in healthy Chinese male subjects. A single-center, randomized, open-label, 2-period, crossover study was performed in healthy Chinese male subjects. Subjects were randomly assigned into 2 sequences and received a subcutaneous injection of 25 mg rhTNFR:Fc PFS or rhTNFR:Fc LYO (Anbainuo), with a 35-day washout between the 2 periods. Blood samples were collected at specified time intervals, and then serum concentrations of rhTNFR:Fc were analyzed by enzyme-linked immunosorbent assay. The maximum serum concentration, area under the concentration-time curve (AUC) from time 0 to the last quantifiable concentration, and AUC from time 0 to infinity were all calculated and evaluated. Meanwhile, safety and immunogenicity were also assessed. A total of 82 subjects completed the study, and six subjects withdrew for various reasons. The 90%CIs for geometric mean ratios of maximum serum concentration, AUC from time 0 to the last quantifiable concentration, and AUC from time 0 to infinity were all within the equivalence range of 80% to 125%. Safety was comparable between the 2 formulations with low immunogenicity. rhTNFR:Fc PFS exhibited similar pharmacokinetic and safety profiles of rhTNFR:Fc LYO (Anbainuo) in healthy Chinese male subjects.

No apparent pharmacokinetic interactions were found between henagliflozin: A novel sodium-glucose co-transporter 2 inhibitor and glimepiride in healthy Chinese male subjects

WHAT IS KNOWN AND OBJECTIVE

Henagliflozin is a novel selective sodium-glucose co-transporter 2 (SGLT2) inhibitor with similar inhibitory effect to ertugliflozin. Glimepiride is widely used to treat type 2 diabetes mellitus (T2DM) with few cardiovascular side effects. In the present study, we aimed at evaluating the pharmacokinetic (PK) interactions between henagliflozin and glimepiride.

METHODS

An open-label, single-centre, single-arm, 3-period, 3-treatment, self-control study was conducted in twelve healthy Chinese male subjects. During each study period, subjects received a single oral dose of glimepiride 2 mg, multiple oral doses of henagliflozin 10 mg or a combination of the two drugs. Serial blood samples were collected 24 h post-dosing for PK analyses. Finger-tip blood glucose was also tested for safety evaluation.

RESULTS AND DISCUSSION

Co-administration of henagliflozin with glimepiride did not affect their plasma PK profiles. For henagliflozin, the 90% confidence intervals for the geometric mean ratio (GMR) for the maximum plasma concentrations at steady-state (C_{max ss} ) and the area under the plasma concentration-time curve during a dosing interval at steady-state (AUC_{τ, ss} ) of combination therapy to henagliflozin alone were 1.00 (0.93-1.08) and 1.00 (0.98-1.02), respectively. For glimepiride, the corresponding values of combination therapy to glimepiride alone were 1.00 (0.88-1.13) for maximum plasma concentrations (C_max ), 0.91 (0.84-0.99) for the area under the plasma concentration-time curve from 0-24 h (AUC_0-24h ) and 0.91 (0.83-1.00) for the plasma concentration-time curve from 0 h to infinite (AUC_0-inf ), respectively. All values fell within the equivalence range of 0.8-1.25. All monotherapies and combination therapy led to no serious adverse events and were well tolerated.

WHAT IS NEW AND CONCLUSION

Multiple doses of henagliflozin did not exert a significant change on glimepiride PK profiles and a single dose of glimepiride had little effect on henagliflozin blood concentration. Thus, henagliflozin can be co-administered with glimepiride without dose adjustment of either drug.

[Luteolin has a significant protective effect against cadmium-induced injury in lung epithelial Beas-2B cells]

OBJECTIVE

To investigate the protective effect of luteolin against cadmium (Cd)-induced injury in human lung epithelial Beas-2B cells.

OBJECTIVE

Beas-2B cells were treated with different concentrations of luteolin (0-160 μmol/L) or Cd (0-40 μmol/L) for 24 h, and the cell viability was examined using MTT assay. After treatment with luteolin (0.25, 0.5 and 0.75 μmol/L) with or without Cd (5 μmol/L) for 24 h, the cells were examined for viability, lactate dehydrogenase (LDH) activity and morphological changes of the cell nuclei using Hoechst fluorescent staining. The levels of ROS, SOD, GSH and MDA in the treated cells were detected, and the expression levels of Akt, p-Akt and nuclear factor E2-related factor 2 (Nrf2) proteins were determined using Western blotting.

OBJECTIVE

Luteolin within the concentration range of 0-80 μmol/L did not significantly affect the survival rate of Beas-2B cells (P>0.05), but Cd at 5 μmol/L significantly decreased the cell viability (P < 0.05) with an IC₅₀ of 24.6 μmol/L. In Cd-treated cells, treatment with luteolin significantly mitigated the decrease of cell viability, reduced LDH release and cell apoptosis, enhanced SOD activity and GSH content, and inhibited the production of MDA and ROS (all P < 0.05). Luteolin also significantly up-regulated the expression levels of p-Akt and Nrf2 protein in Cd-treated Beas-2B cells (P < 0.05).

OBJECTIVE

Luteolin has a significant protective effect against Cd-induced injury in Beas-2B cells, and the effects are probably mediated, at least in part, by promoting the activation of Akt and Nrf2.

A Randomized, Double-Blind, Single-Dose Study Comparing the Biosimilarity of HOT-1010 With Bevacizumab (Avastin®) in Chinese Healthy Male Subjects

Objective: This study was conducted to compare the pharmacokinetics, safety and immunogenicity of HOT-1010 with bevacizumab (Avastin®) in Chinese healthy male subjects.

Methods: A single-center, randomized, double-blind, single-dose, parallel trial was performed in 84 Chinese healthy male subjects who randomly (1:1) received a single intravenous infusion of 1 mg/kg HOT-1010 or Avastin® for 90 min and followed up for 85 days. Serum concentrations of bevacizumab were analyzed by enzyme-linked immunosorbent assay. Primary pharmacokinetic parameters, C_max, AUC_0-t and AUC_0-∞, were calculated and evaluated the bioequivalence between HOT-1010 and Avastin®, the safety and immunogenicity of investigational drugs were also assessed.

Results: A total of 82 subjects completed the study. The 90% Confidence Intervals for geometric mean ratios of C_max, AUC_0-t and AUC_0-∞ were 91.81–103.64%, 85.19–95.39% and 85.04–95.36%, which were all within the bioequivalence margin. Treatment-emergent adverse events were reported in 27 (65.9%) subjects in HOT-1010 group and 23 (56.1%) subjects in Avastin® group. Most TEAEs were mild or moderate. No TEAEs, Serious Adverse Events or deaths leading to discontinuation was reported. Subjects were all tested negative for Anti-drug Antibody.

Conclusion: HOT-1010 exhibited the similar pharmacokinetics, safety and immunogenicity profiles of bevacizumab (Avastin®) in Chinese healthy male subjects.

Clinical Trial Registration:http://www.chinadrugtrials.org.cn/index.html, CTR20181610.

Identification of human uridine diphosphate-glucuronosyltransferase isoforms responsible for the glucuronidation of 10,11-dihydro-10-hydroxy-carbazepine

OBJECTIVES

To determine the kinetics of the formation of 10,11-dihydro-10-hydroxy-carbazepine (MHD)-O-glucuronide in human liver microsomes (HLMs), human intestine microsomes (HIMs), human kidney microsomes (HKMs) and recombinant human UDP-glucuronosyltransferase (UGTs), and identify the primary UGT isoforms catalyzing the glucuronidation of MHD.

METHODS

The kinetics of the glucuronidation of MHD was determined in HLMs, HIMs as well as HKMs. Screening assays with 13 recombinant human UGTs, inhibition studies and correlation analysis were performed to identify the main UGTs involved in the glucuronidation of MHD.

KEY FINDINGS

MHD-O-glucuronide was formed in HLMs, HIMs as well as HKMs, HLMs showed the highest intrinsic clearance of MHD. Among 13 recombinant human UGTs, UGT2B7 and UGT1A9 were identified to be the principal UGT isoforms mediating the glucuronidation of MHD, while UGT1A4 played a partial role. In addition, inhibition studies and correlation analysis further confirmed that UGT2B7 and UGT1A9 participated in the formation of MHD-O-glucuronide.

CONCLUSIONS

MHD could be metabolized by UGTs in the liver, intestine and kidney, and the hepatic glucuronidation was the critical metabolic pathway. UGT2B7 and UGT1A9 were the primary UGT isoforms mediating the formation of MHD-O-glucuronide in the liver.

Acarbose bioequivalence: Exploration of eligible protocol design

WHAT IS KNOWN AND OBJECTIVE

Acarbose is a poorly absorbed α-glucosidase inhibitor that acts locally in the intestinal tract. Therefore, the evaluation of its bioequivalence (BE) should be based on pharmacodynamic (PD) rather than pharmacokinetic (PK) endpoints. Currently, there is no consensus on the best method for acarbose BE evaluation. The optimal protocol design regarding dosing time/dose and PD parameters requires further exploration. The aim of the study was to identify an optimum protocol for establishing acarbose BE in healthy Chinese volunteers using PD endpoints.

METHODS

Three pilot studies were conducted in healthy Chinese subjects. Study 1 was an open, randomized, two-period crossover study using the reference (R) drug at the dose of 1 × 50 mg. Study 1 aimed to determine appropriate dosing time by comparing the PD effect of acarbose between two administration methods. One method was concomitant administration of sucrose and acarbose, and another method was acarbose administration 10 min before sucrose. Study 2 was an open, randomized, three-period crossover study. Subjects were given the R drug at the dose of 1 × 50 mg, 2 × 50 mg or 3 × 50 mg in a random sequence. The aim of Study 2 was to identify a reasonable dose of acarbose in the BE study. Study 3 was conducted with an open, randomized, three-period crossover design using the test (T) or R drug in an R-T-R sequence at the dose of 2 × 50 mg. Study 3 aimed to compare the BE between the R and T drug and determine intra-individual variation. Twelve subjects were recruited in Study 1, Study 2 and Study 3, respectively, with a one-week washout period. Serum glucose and insulin concentrations were determined after sucrose administration (baseline) and sucrose/acarbose co-administration.

RESULTS AND DISCUSSION

In Study 1, no significant differences in PD parameters were found between the two administration methods. The results of Study 2 revealed that the optimal dose was between 1 × 50 mg and 2 × 50 mg. The comparison of PD parameters indicated that the rectifying method could distinguish between different formulations. Study 3 showed that the geometric mean ratios of C_{max, r} , AUC_{0-2 h, r} and AUC_{0-4 h, r} were 90.06%, 84.55% and 84.21%, respectively, using the rectifying method. The 90% CIs of C_{max, r} were within acceptance limits (80.00%-125.00%), whereas that of AUC_{0-2 h, r} and AUC_{0-4 h, r} were out of the range. The intra-individual variation was approximately 21% for R formulation. Based on the variation, the number of subjects needed to identify formulation differences in the pivotal study would be 55 with 90% power at the 5% level of significance.

WHAT IS NEW AND CONCLUSION

The results from our study manifested that a randomized, balanced, two-way crossover design was eligible to evaluate acarbose BE. The appropriate dosing time was concomitant administration of sucrose and acarbose, and the optimal dose was 2 × 50 mg. The rectifying method exhibited preferable sensitivity and applicability in acarbose BE evaluation. A practical sample size of the pivotal study would be 55. These results may help to provide new insights into the protocol design of acarbose BE study.

Policy infrastructure and mechanism to Promote “Health by All” Movement for Overturning Obesity

Background

Obesity is a pressing pandemic. However, major policies have targeted individual responsibility and focused on “losing weight or lowering calories”. Such approach has limited effect and overlooks the hidden obesity.

Methods

Under auspices of NHRI Forum, Taiwan; the WAKE.TAIWAN Research Team analyzed the global trends of policies, strategies, and literatures to formulate guiding principles for a total solution. 1. Defining obesity should go beyond body weight and emphasize more on healthy body composition and muscle mass, etc. 2. Effective obesity control strategy should facilitate building healthy living environments, lifestyle, and culture for natural flow of healthy behaviors. 3. All sectorial leaders should be involved in engaging and promoting healthy lifestyle culture and environment.

Results

”Guidelines for Establishing a lifestyle and Culture of Healthy Body Build” has been published as a blueprint for policy reform and strategies development, which consists of three parts. Part I emphasizes the active roles, social responsibilities, influence, and opportunities confronted the leaders and experts in all sectors and how government may facilitate these societal engagements, “Healthy by All”. The crucial sectors should include academia, NGO/NPO, industry/business, workplaces, healthcare systems, educational sectors, media and press, etc. Part II details on community spatial planning and architectural designs for healthy lifestyles. Part III proposes governmental “Health in All” infrastructure and mechanism.

Conclusions

We anticipate that the Guideline may draw out expertise and volunteering in all sectors of the society and help guide the public to take initiative in building such a culture of healthy-body-build and achieving this goal in all aspects of daily life.

Key messages

Emphasize on healthy body composition rather than body weight. Propagate 'Health by all' movement to foster building 'healthy physique' culture.

Bedaquiline in the treatment of multidrug- and extensively drug-resistant tuberculosis in China

BACKGROUND: Multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB) continues to be a challenge in China. Bedaquiline (BDQ) is associated with accelerated sputum culture conversion and favourable treatment outcomes when added to a preferred background regimen. This post-hoc study aimed to assess the outcomes of BDQ treatment in Chinese patients with MDR/XDR-TB.METHODS: Data from 51 Chinese patients who participated in a global Phase 2, open-label, single-arm study (TMC207-C209) were analysed for effectiveness and safety of the BDQ-containing regimen.RESULTS: During the 24-week BDQ treatment, adverse events (AEs) occurred in 48 patients (94.1%), with the most common AE being hyperuricemia. Drug-induced liver injury (DILI) was reported in 13 patients (25.5%); serious DILI was reported in one patient (2.0%). Seven (13.7%) AEs were considered to be possibly related to BDQ by the investigators. Only one Grade 1 QTc prolongation was reported; no QTcF >500 ms was reported. One death occurred after BDQ treatment due to progressive TB. The median time to sputum culture conversion was 85 days based on the 24-week data. The sputum culture conversion rate was 82% at 24 weeks and 78% at 120 weeks; 66% of patients achieved a cure.CONCLUSIONS: BDQ was well-tolerated and effective for treating MDR-TB among Chinese patients.

Rapid and highly sensitive quantification of the anti-tuberculosis agents isoniazid, ethambutol, pyrazinamide, rifampicin and rifabutin in human plasma by UPLC-MS/MS

With the increased cases of multidrug- or rifampicin-resistant tuberculosis and co-infection with HIV globally, it is difficult to achieve ideal clinical responses because of poor drug absorption and drug-drug interactions. Herein, a bioanalytical UPLC-MS/MS method was developed and validated to quantify five anti-TB agents in human plasma samples for detecting blood drug concentrations to improve therapeutic effects. To overcome the matrix effects, stable isotope labeled analogue of each analyte was used for internal standardization. A simple single-step protein precipitation by acetonitrile was employed for the sample preparation, then the analytes including rifampicin, rifabutin, pyrazinamid, ethambutol, isoniazid and their isotope labeled internal standards (ILISs) were implemented on an HILIC silica column with a gradient mode. The linear range for each analyte was covering the peak drug concentration (C_max) in the 20 times diluted plasma samples. The coefficient of variation of intra- and inter-day precision was less than 17.0 %, and the accuracy ranged between 91.5 and 110.0 %. The extraction recoveries of all agents were ≥90.2 %, and the matrix effects with internal standard-normalization for all agents were 97.1-110.0 %. The optimal blood sampling time was designed basing on the results of stability validation. This UPLC-MS/MS method with a run time of 3.5 min was successfully applied to routine therapeutic monitoring of the five anti-TB agents in patient plasma.

Clofazimine improves clinical outcomes in multidrug-resistant tuberculosis: a randomized controlled trial

OBJECTIVES

We carried out a randomized multicentre study in China to investigate whether the clofazimine would improve the efficacy of the standardized regimen in patients with multidrug-resistant tuberculosis (MDR-TB).

METHODS

Patients with MDR-TB managed in 17 TB specialist hospitals in China between September 2009 and September 2011 were randomly assigned to the treatment groups at enrolment. In the intervention group, 100 mg clofazimine per day was added to the standardized regimen. The primary outcome was the proportion of patients with successful outcomes.

RESULTS

From the 156 patients that were screened, 74 were assigned to the control group and 66 to the clofazimine group. Of the 66 cases analysed for clinical outcome in the clofazimine group, 36 patients were cured, and seven completed treatment, yielding a favourable outcome rate of 65.1%. The proportion of patients with favourable outcomes receiving the control regimen was 47.3% (35/74), which was significantly lower than that in the clofazimine group (p 0.034, relative risk 0.661, 95% CI 0.243-0.949).

CONCLUSIONS

The addition of clofazimine to the standard regimen improved the treatment of MDR-TB.

Nonlinear Transition from Mitigation to Suppression of the Edge Localized Mode with Resonant Magnetic Perturbations in the EAST Tokamak

Evidence of a nonlinear transition from mitigation to suppression of the edge localized mode (ELM) by using resonant magnetic perturbations (RMPs) in the EAST tokamak is presented. This is the first demonstration of ELM suppression with RMPs in slowly rotating plasmas with dominant radio-frequency wave heating. Changes of edge magnetic topology after the transition are indicated by a gradual phase shift in the plasma response field from a linear magneto hydro dynamics modeling result to a vacuum one and a sudden increase of three-dimensional particle flux to the divertor. The transition threshold depends on the spectrum of RMPs and plasma rotation as well as perturbation amplitude. This means that edge topological changes resulting from nonlinear plasma response plays a key role in the suppression of ELM with RMPs.

Pharmacokinetic interaction of finasteride with tamsulosin hydrochloride: an open-label, randomized, 3-period crossover study in healthy Chinese male volunteers

PURPOSE

The primary aim of this study was to evaluate whether there was clinically significant pharmacokinetic (PK) interaction between finasteride and tamsulosin in healthy Chinese male subjects.

METHODS

This was an open-label, randomized, 3-period, crossover study. Subjects received single and multiple doses of 5 mg finasteride alone, single and multiple doses of 0.2 mg tamsulosin hydrochloride sustained-release capsule alone, and single and multiple doses of 5 mg finasteride with 0.2 mg tamsulosin hydrochloride, in an order determined by a computerized randomization schedule. Blood samples were collected up to 48 hours after dosing on study day 1 and up to 24 hours after dosing on study day 9 for determination of plasma concentrations with a validated LC-MS/MS method. Pharmacokinetic parameters were estimated via noncompartmental methods. Tolerability was evaluated by monitoring adverse events, laboratory assays, vital signs, and 12-lead ECG.

FINDINGS

Fifteen subjects were enrolled, and 14 completed the study. The geometric mean ratios (GMRs) (90% CIs) of AUC(τ,ss) and C(max,ss) values of finasteride at steady state between coadministration of finasteride and tamsulosin hydrochloride and finasteride alone were 1.14 (1.05-1.23) and 1.06 (0.99-1.14), respectively. The GMRs (90% CIs) for AUC(0-t) and C(max) values of finasteride for a single dose of coadministration of finasteride and tamsulosin hydrochloride and finasteride alone were 1.02 (0.94-1.11) and 1.06 (1.01-1.11), respectively. The GMRs (90% CIs) for AUC(τ,ss) and C(max,ss) values of tamsulosin at steady-state for coadministration of finasteride and tamsulosin hydrochloride and tamsulosin hydrochloride alone were 1.18 (1.05-1.33) and 1.23 (1.06-1.43), respectively. The GMRs (90% CIs) for AUC(0-t) and C(max) values of tamsulosin for a single dose of coadministration of finasteride and tamsulosin hydrochloride and tamsulosin hydrochloride alone were 1.04 (0.97-1.10) and 1.04 (0.98-1.11), respectively. Statistical analyses confirmed that the 90% CIs for these PK parameters were within the predefined not clinically significant PK drug-drug interaction effect boundaries (0.5-2.0) in this study. If comparing the findings with narrower boundaries (0.8-1.25), the conclusion may not be supportive for tamsulosin hydrochloride. During the study, a total of 4 adverse events were reported in 3 subjects including allergic reaction, abnormal findings on an ECG, a slight increase in alanine aminotransferase, and a positive result on glucose urine test.

IMPLICATIONS

Both finasteride and tamsulosin hydrochloride were well tolerated. Coadministration of finasteride and tamulosin hydrochloride seems unlikely to lead to a clinically significant PK drug-drug interaction, after a single dose and at steady state.

The hURAT1 rs559946 polymorphism and the incidence of gout in Han Chinese men

OBJECTIVES

Our previous study identified rs559946, a human urate transporter 1 (hURAT1) single nucleotide polymorphism (SNP), as being significantly associated with risk of primary hyperuricaemia (HUA) in a Han Chinese population. In the current study we aimed to identify the genetic effects of rs559946 on gout susceptibility in Han Chinese men.

METHOD

A total of 335 patients with gout and 376 healthy controls were recruited for a case-control association study. To examine the functional effect of rs559946, we performed luciferase reporter assays and an electrophoretic mobility shift assay (EMSA).

RESULTS

rs559946 was found to be significantly associated with gout susceptibility (p = 0.004), with T-allele carriers showing a decreased risk of gout [odds ratio (OR) 0.70, 95% confidence interval (CI) 0.55-0.89]. Multiple linear regression analysis identified a significant association between rs559946 genotypes and tophi. Luciferase reporter assays show increased transcriptional activity of the hURAT1 promoter with the C allele of rs559946. EMSA detected binding of nuclear proteins to both the T and C alleles, although increased binding was observed with the T allele. Cold competition assays suggest that rs559946 may bind within a glucocorticoid receptor (GR) binding motif.

CONCLUSIONS

Our study suggests that the rs559946 polymorphism is associated with increased HUA risk and may also contribute to gout development in Han Chinese men. The T to C substitution within rs559946 increased the transcriptional activity, and potentially increases gout susceptibility.

IL-8 -251T/A and IL-12B 1188A/C polymorphisms are associated with gout in a Chinese male population

OBJECTIVES

Gout is caused by monosodium urate (MSU) crystal-induced inflammation of the joints and periarticular tissues. MSU crystals activate NALP3 and mediate interleukin (IL)-1β generation from its inactive pro-form, resulting in cellular activation and an IL-8-mediated neutrophil influx into the joint. IL-8 and IL-12 are important chemokines related to the initiation and amplification of acute and chronic inflammatory processes. In this study, we investigated whether the IL-8 -251T/A and IL-12 1188A/C polymorphisms are associated with susceptibility to gout in a Chinese Han male population.

METHODS

Overall, 387 patients with gout and 576 controls were included in this study. Genotyping was performed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). An association analysis was carried out using the χ2 test. A genotype-phenotype analysis was also conducted.

RESULTS

The T allele of IL-8 -251 was associated with risk of gout [p = 0.031 (odds ratio (OR) 1.229, 95% confidence interval (CI) 1.019-1.483]. There was a clear link between the IL-12 1188 AA and AC genotypic and A allelic frequencies between gout cases and controls (p < 0.001, df = 2 by genotype; p < 0.001, OR 1.404, 95% CI 1.165-1.691 by allele).

CONCLUSIONS

Our results suggest that the IL-8 -251T/A and IL-12B 1188A/C polymorphisms may be relevant host susceptibility factors for the development of gout.

The use of high-frequency oscillatory ventilation in adult ARDS patients

Current ventilatory objectives for adults with ARDS include maximizing gas exchange while minimizing lung injury. To this end, high-frequency oscillatory ventilation (HFOV), a mechanical ventilation strategy that simultaneously avoids end-inspiratory alveolar overdistension and end-expiratory alveolar collapse, has been recommended. HFOV meets these criteria from a theoretical perspective, however, is without the benefit of a prospective randomized clinical trial of CMV versus HFOV to demonstrate that effect. This article provides an overview of high-frequency oscillation, followed by an illustration of how it was applied in the case of a 43-year-old patient who developed respiratory failure 24 hours post-Caesarean section.

Hydrophobic benzoic acids as inhibitors of influenza neuraminidase

Neuraminidase (NA) plays a critical role in the life cycle of influenza virus and is a target for new therapeutic agents. A new benzoic acid inhibitor (11) containing a lipophilic side chain at C-3 and a guanidine at C-5 was synthesized. The X-ray structure of 4-(N-acetylamino)-5-guanidino-3-(3-pentyloxy)benzoic acid in complex with NA revealed that the lipophilic side chain binds in a newly created hydrophobic pocket formed by the movement of Glu 278 to interact with Arg 226, whereas the guanidine of 11 interacts in a negatively charged pocket created by Asp 152, Glu 120 and Glu 229. Compound 11 was highly selective for type A (H2N2) influenza NA (IC50 1 microM) over type B (B/Lee/40) influenza NA (IC50 500 microM).

Potent inhibition of influenza sialidase by a benzoic acid containing a 2-pyrrolidinone substituent

On the basis of the lead compound 4-(N-acetylamino)-3-guanidinobenzoic acid (BANA 113), which inhibits influenza A sialidase with a Ki of 2.5 microM, several novel aromatic inhibitors of influenza sialidases were designed. In this study the N-acetyl group of BANA 113 was replaced with a 2-pyrrolidinone ring, which was designed in part to offer opportunities for introduction of spatially directed side chains that could potentially interact with the 4-, 5-, and/or 6-subsites of sialidase. While the parent structure 1-(4-carboxy-2-guanidinophenyl)pyrrolidin-2-one (8) was only a modest inhibitor of sialidase, the introduction of a hydroxymethyl or bis(hydroxymethyl) substituent at the C5' position of the 2-pyrrolidinone ring resulted in inhibitors (9 and 12, respectively) with low micromolar activity. Crystal structures of these inhibitors in complex with sialidase demonstrated that the substituents at the 5'-position of the 2-pyrrolidinone ring interact in the 4- and/or 5-subsites of the enzyme. Replacement of the guanidine in 12 with a hydrophobic 3-pentylamino group resulted in a large enhancement in binding to produce an inhibitor (14) with an IC50 of about 50 nM against influenza A sialidase, although the inhibition of influenza B sialidase was 2000-fold less. This represents the first reported example of a simple, achiral benzoic acid with potent (low nanomolar) activity as an inhibitor of influenza sialidase.

Structure of 3,4-dichloroisocoumarin-inhibited factor D

Factor D (D) is a serine protease essential in the activation of the alternative complement pathway. Only a few of the common serine protease inhibitors inhibit D, binding covalently to the serine hydroxyl of the catalytic triad. 3,4-Dichloroisocoumarin (DCI) is a mechanism-based inhibitor which inhibits most serine proteases and many esterases, including D. The structure of the enzyme:inhibitor covalent adduct of D with DCI, DCI:D, to a resolution of 1.8 A is described, which represents the first structural analysis of D with a mechanism-based inhibitor. The side chain of the ring-opened DCI moiety of the protein adduct undergoes chemical modification in the buffered solution, resulting in the formation of an alpha-hydroxy acid moiety through the nucleophilic substitution of both Cl atoms. The inhibited enzyme is similar in overall structure to the native enzyme, as well as to a variety of isocoumarin-inhibited trypsin and porcine pancreatic elastase (PPE) structures, yet notable differences are observed in the active site and binding mode of these small-molecule inhibitors. One region of the active site (residues 189-195) is relatively conserved between factor D, trypsin, and elastase with respect to amino-acid sequence and to conformation. Another region (residues 214-220) reflects the amino-acid substitutions and conformational flexibility between these enzymes. The carbonyl O atom of the DCI moiety was found to be oriented away from the oxyanion hole, which greatly contributes to the stability of the DCI:D adduct. The comparisons of the active sites between native factor D, DCI-inhibited factor D, and various inhibited trypsin and elastase (PPE) molecules are providing the chemical bases directing our design of novel, small-molecule pharmaceutical agents capable of modulating the alternative complement pathway.

[Controlled clinical trial on efficacy of 5-month regimens and whole course intermittent 6-month regimens in treating bacillary pulmonary tuberculosis]

OBJECTIVE

To assess the therapeutic efficacy of rifapentine (L), to reduce the duration of treatment and the frequency of drug administration, and to observe the influence on efficacy and adverse reactions of using pyrazinamide (Z) through whole-course.

METHOD

Two 5-month regimens respectively including rifampin (R) and L and two whole course intermittent regimens were designed as following: I: 2SHRZ/3R2H2Z2; II: 2SHRZ/3L1H2Z2; III: 2S3H3R3Z3/4L1H2Z2; IV: 2S3H3R3Z3/4L1H2E2. A total of 366 newly-diagnosed bacillary pulmonary tuberculosis patients were admitted and randomly allocated.

RESULTS

339 cases completed the prescribed short course chemotherapy. The sputum conversion rates at the end of the treatment of groups I, II, III and IV were 97.0%, 94.1%, 100.0% and 97.2% respectively. X-ray resolution rates were 96.0%, 97.6%, 100.0% and 94.4% respectively. Cavity-close rates of the 5-month regimens and the 6-month regimens were 77% and 76%. Comparing the results among groups, there were no statistically significant differences (P > 0.05), and no obvious side-effect was found. 305 patients have been followed up for 3 years since completion of the chemotherapy. The bacteriological relapse and bacteriological relapse with deterioration on chest X-ray in groups I, II, III and IV were seen in 2,3,6 and 3 cases respectively.

CONCLUSION

Domestic-made rifapentine is a long-acting, highly effective antituberculosis drug. It is unnecessary to use Z in continuation phase, and it is possible to shorten the duration to 5 months with the appropriate combination of essential drugs, which is worthwhile for further study.

Design and synthesis of benzoic acid derivatives as influenza neuraminidase inhibitors using structure-based drug design

A series of 94 benzoic acid derivatives was synthesized and tested for its ability to inhibit influenza neuraminidase. The enzyme-inhibitor complex structure was determined by X-ray crystallographic analysis for compounds which inhibited the enzyme. The most potent compound tested in vitro, 5 (4-acetylamino)-3-guanidinobenzoic acid), had an IC50 = 2.5 x 10(-6) M against N9 neuraminidase. Compound 5 was oriented in the active site of the neuraminidase in a manner that was not predicted from the reported active site binding of GANA (4) with neuraminidase. In a mouse model of influenza, 5 did not protect the mice from weight loss due to the influenza virus when dosed intranasally.

Preservation of intercalated cell H(+)-ATPase in two patients with lupus nephritis and hyperkalemic distal renal tubular acidosis

In patients with Sjögren's syndrome and a secretory-defect distal renal tubular acidosis (dRTA), absence of vacuolar H(+)-ATPase from collecting duct intercalated cells has been reported. The H(+)-ATPase was examined in two patients with lupus nephritis and hyperkalemic (presumed voltage defect) dRTA. Both patients had a positive urine anion gap, alkaline urine despite acidemia, no rise in urine PCO2 with alkaluria, a urine pH > 5.5, and urine potassium excretion rate not significantly increased after 80 mg of intravenous furosemide. In both patients, immunocytochemistry of renal biopsy frozen sections with an anti-H(+)-ATPase monoclonal antibody showed bright staining of the proximal tubule brush border and collecting duct intercalated cells. In one patient, routine immunofluorescence analysis of a frozen section of her kidney biopsy with antihuman IgG showed staining of the collecting duct, indicative of autoantibodies to this segment. Moreover, rat kidney sections incubated with her serum showed labeling of the intercalated cells. On immunoblots of human kidney microsomal membranes performed with serum from both patients, an immunoreactive polypeptide was observed at M(r) approximately 56 kD that was not seen with control serum. Neither patient's sera reacted with affinity-purified bovine H(+)-ATPase or with lysates from 293 cell fibroblasts in which either of both isoforms of the human H(+)-ATPase B subunit (56 kD) were expressed. These findings demonstrate that the spectrum of dRTA includes the preservation of H(+)-ATPase in intercalated cells, in patients with presumed voltage defect dRTA. Moreover, some patients may have autoantibodies to the intercalated cells that are not directed to subunits of the H(+)-ATPase.

Guanidinobenzoic acid inhibitors of influenza virus neuraminidase

The active site of influenza virus neuraminidase (NA) is formed by 11 universally conserved residues. A guanidino group incorporated into two unrelated NA inhibitors was previously reported to occupy different negatively charged sites in the NA active site, A new inhibitor containing two guanidino groups was synthesized in order to utilize both sites in an attempt to acquire a combined increase in affinity. The X-ray crystal structures of the complexes show that the expected increase in affinity could not be achieved even though the added guanidino group binds to the negatively charged site as designed. This suggests that the ligand affinity to the target protein is contributed both from ligand-protein interactions and solvation/conformation energy of the ligand.

Structure of Diisopropyl Fluorophosphate-Inhibited Factor D

Factor D (D) is a serine protease, crucial for the activation of the alternative complement pathway. Only a limited number of general serine protease inhibitors are known to inhibit D, most of which covalently bind to the serine hydroxyl of the catalytic triad. The structure of the first enzyme:inhibitor covalent adduct of D with diisopropyl fluorophosphate (DIP:D) to a resolution of 2.4 A is described. The inhibited enzyme is similar in overall structure to the native enzyme and to trypsin, yet exhibits notable differences in the active site. One region of the active site is conserved between D and trypsin with respect to amino-acid sequence and to conformation. Another reflects the amino-acid substitutions and conformational flexibility between these enzymes. The active-site histidine residue is observed in the gauche+ conformation, not the normal gauche- orientation seen in the classic catalytic triad arrangement required for enzymatic activity in serine proteases. Comparisons of the active sites between native D, the DIP:D adduct, and DIP-inhibited trypsin have provided fundamental insights currently being employed in the design of novel small-molecule pharmaceutical agents capable of modulating the alternative complement pathway.

Serum CA-125 level in end-stage renal disease patients maintained on chronic peritoneal dialysis or hemodialysis: the effect of continuous presence of peritoneal fluid, peritonitis, and peritoneal catheter implantation

Serum Ca-125, an ovarian tumor marker, is used to screen and follow up patients with overian cancer. Normal values (< 35 U/ml) have been reported in patients with end-stage renal disease and patients maintained on chronic hemodialysis (HD). Non-malignant ascites has been associated with high serum levels of CA-125, suggesting that the presence of fluid in the peritoneal cavity may stimulate its release. We studied 38 HD and 43 chronic ambulatory peritoneal dialysis (CAPD) patients with regard to serum CA-125 levels. In the HD patients, the mean +/- SE serum CA-125 level was 10.1 +/- 1.7 U/ml (range < 5-39) with 8% of the patients having serum levels of > 35 U/ml. In the CAPD patients, the mean serum CA-125 level in all samples collected (n = 68) was 17.7 +/- 2.7 U/ml (range < 5-101, p < 0.01 vs. HD) with 16% of the sera showing levels of > 35 U/ml. The high serum CA-125 levels in the CAPD patients were from sera obtained within 2 months of diagnosis of peritonitis, peritoneal dialysis (PD) catheter implantation, or intra-abdominal surgery. When serum samples from this 2-month period were excluded, the mean serum CA-125 level was 8.9 +/- 1.5 U/ml (p = NS vs. HD) and only 1 patient had an abnormal level. Peritoneal dialysate CA-125 levels during an episode of peritonitis were significantly higher than at the baseline (69.1 +/- 14.2 vs. 21 +/- 2.5, p = 0.004) and both were significantly higher than the serum levels (p < 0.0001). Serum CA-125 levels were also the same in both sexes and races. In conclusion, it was found that while the serum CA-125 level is within normal limits in the majority of HD and stable CAPD patients, it is not uncommon that it is elevated in CAPD patients within 2 months of peritonitis, PD catheter placement, or intra-abdominal surgery, particularly when peritoneal exchanges are temporarily on hold in the latter two. The serum CA-125 level should be interpreted with caution in the CAPD patients as it may be a non-specific marker of peritoneal irritation. It was also found that there was a significant removal of CA-125 by the peritoneal fluid which markedly increased during episodes of peritonitis.

Chemical and enzymatic degradation of ganciclovir prodrugs: enhanced stability of the diadamantoate prodrug under acid conditions

We report the chemical and enzymatic hydrolysis of two hydrophobic prodrugs of ganciclovir (3 = dipropionate ester; 4 = diadamantoate ester). Both prodrugs undergo hydrolysis showing a pH dependence of kobs = kH+aH+ + ko + kHO-aHO- and a pH of maximum stability near pH 5. Only 4 exhibited a shelf life (t90) greater than 2 years. Compound 4 reacts significantly slower than ganciclovir in acidic media, even though the adamantyl esters provide additional reaction sites (which would be expected to increase the rate of degradation) that are distally removed from the guanine ring system, offering negligible steric or electronic substituent effects. Both 3 and 4 hydrolyzed in tissue homogenate, where kobs followed liver greater than intestine much greater than skin. Based on these findings of chemical stability, lipophilicity, and acceptable rate of enzymatic cleavage by skin esterases, 4 meets several of the criteria required for the topical sustained delivery of ganciclovir.

Bioavailability improvement of mycophenolic acid through amino ester derivatization

The potential bioavailability improvement of mycophenolic acid (MPA), 1, through ester derivatization was evaluated in monkeys at a dose of 20 mg/kg in this study. The acetyl solketal ester 3 was found to have excellent partition properties but poor aqueous solubility. Thus, even though it can be converted rapidly to MPA by plasma and liver enzymes, it showed poor oral bioavailability (56% of MPA) in monkeys. The bioavailability of the morpholinoethyl ester 4 and the acetyl morpholinoethyl ester 5, on the other hand, was found to be 236 and 150% that of MPA, respectively. Since ester 5 has greater aqueous solubility, but similar chemical stability and enzymatic hydrolysis rates compared to ester 4, the better bioavailability of ester 4 may result from its greater partitioning into the gastrointestinal membranes.

Inhibitors of cyclic AMP phosphodiesterase. 4. Synthesis and evaluation of potential prodrugs of lixazinone (N-cyclohexyl-N-methyl-4-[(1,2,3,5-tetrahydro-2- oxoimidazo[2,1-b]quinazolin-7-yl)-oxy]butyramide, RS-82856)

The cyclic AMP phosphodiesterase (cAMP PDE) inhibitor and cardiotonic agent lixazinone (N-cyclohexyl-N-methyl-4-[(1,2,3,5-tetrahydro-2- oxoimidazo[2,1-b]quinazolin-7-yl)oxy]butyramide, RS-82856, 1) and its acid and base addition salts were found to be insufficiently soluble in formulations suitable for intravenous administration. These results prompted an investigation into potential prodrugs with enhanced aqueous solubility designed to deliver 1 by three distinct mechanisms: (1) decarboxylation of alpha-carboxamides; (2) hydrolytic loss of a solubilizing N-1-(acyloxy)methyl or (N,N-dialkylamino)methyl moiety; or (3) intramolecular closure of a guanidino ester or amide. The target compounds were evaluated as delivery systems for 1 by three criteria: (1) chemical conversion rate to 1 under physiological conditions; (2) inhibition of type IV cAMP PDE at a fixed time point; and (3) in vivo inotropic activity in anesthetized dogs by both intravenous and oral administration. Release of 1 from 4a (series 1) was found to be too slow to be of value as a prodrug of 1, since decarboxylation could be induced only by strong acid, conditions under which hydrolytic ring opening was found to severely compete. Conversely, 1 was released too readily on exposure of (N,N-dialkylamino)methyl derivatives such as 8d (series 2) to physiological conditions, although no large increase in aqueous solubility was realized. Finally, both the physicochemical and in vitro studies indicated that ring closure of the guanidinium esters and amides 17a-k (series 3) to 1 was quantitative and pH- and time-dependent, suggesting the possibility of delivery of the open, water-soluble prodrug form, followed by closure to 1 in plasma. Detailed examination of these agents in vivo, however, demonstrated that only those compounds that rapidly cyclized to 1, as measured by plasma levels of 1, exhibited inotropic activity, indicating that the open prodrug form was not efficiently absorbed upon oral administration.

Distribution of transfer RNA genes in thePisum sativum chloroplast DNA

Purified chloroplast tRNAs were isolated fromPisum sativum leaves and radioactively labeled at their 3' end using tRNA nucleotidyl transferase and α(32)P-labeled CTP. Pea ctDNA was fragmented using a number of restriction endonucleases and hybridized with thein vitro labeled chloroplast tRNAs by DNA transfer method. Genes for tRNAs have been found to be dispersed throughout the chloroplast genome. A closer analysis of the several hybrid regions using recombinant DNA plasmids have shown that tRNA genes are localized in the chloroplast genome in both single and multiple arrangements. Two dimensional gel electrophoresis of total ct tRNA have identified 36 spots. All of them have been found to hybridize withPisum sativum ctDNA. Using recombinant clones, 30 of the tRNA spots have been mapped inPisum sativum ctDNA.

Radioimmunoassay of nafarelin ([ 6-(3-(2-naphthyl)-D-alanine)]-luteinizing hormone-releasing hormone) in plasma or serum

A procedure which is suitable for the radioimmunoassay (RIA) of nafarelin [( 6-(3-(2-naphthyl)-D-alanine)]-luteinizing hormone-releasing hormone) in plasma or serum at concentrations as low as 50 pg/ml is described. Antiserum was prepared by replacing the pyroglutamyl portion of nafarelin with glutaric acid, coupling the product to keyhole limpet hemocyanin, and immunizing rabbits with the resulting conjugate. At a dilution of 1:30,000 the binding was approximately 50%. The antibodies did not cross react with luteinizing hormone-releasing hormone. For RIA, 125I-labeled analyte was used as the tracer and charcoal was used to separate the free and the bound fractions. No purification of samples was required prior to RIA. Accuracy of the method was assessed by adding known quantities of nafarelin to nafarelin-free plasma and determining the ratio of measured to added analyte. Linear regression analysis for the concentration range 0.050-5.00 ng/ml yielded a regression equation of y = 1.01x - 0.066 and a correlation coefficient of 0.997. At 0.050 ng/ml the CV was 11.3% (interassay). Additional validation was obtained from an in vivo study in which [3H]nafarelin was administered to monkeys and plasma profiles were determined by RIA, by high-performance liquid chromatography (HPLC), and by an HPLC-radiochemical method. The results obtained by RIA agreed well with those obtained by the HPLC methods.

Sucrose metabolism in situ by dental plaque in appliance-borne bovine enamel tooth fissure inserts in man

Sucrose metabolism of dental plaque which accumulated in fissure-like spaces between small bovine enamel cubes on removable U-shaped appliances was analysed using radiolabelled techniques. The appliances were worn by 8 dental students for 21 days. Half of the fissural inserts (3) on one wing of the appliance were exposed to a 10 per cent sucrose solution in normal saline and half (3) to normal saline as a control on the opposite wing, 8 x/day. At 21 days [14C]-sucrose (U) was applied directly to sucrose and saline-exposed inserts extra-orally for 60 min at 37 degrees C (non-dispersed plaques, NDP). Adjacent inserts on both sides of the appliances were removed. The plaque was dispersed in buffer by sonication, cultured and was exposed to radiolabelled sucrose for the same incubation period (dispersed plaques, DP). The following observations were made: (1) quantitative values for sucrose consumption and lactic acid, cell-bound and insoluble product, soluble polysaccharide, carbon dioxide and total volatile acid formation did not differ between sucrose and saline exposed DP or sucrose- and saline-exposed NDP; (2) all DP consumed more sucrose and formed higher quantitative levels of all products than NDP counterparts, p less than 0.001; (3) sucrose-exposed DP and sucrose exposed NDP formed proportionally more lactic acid than saline-exposed counterparts, p less than 0.05; (4) sucrose-exposed NDP formed proportionally more lactic acid and less soluble polysaccharide than sucrose exposed DP, p less than 0.025; (5) concentrations of lactobacilli were higher in sucrose exposed plaques, p less than 0.049.