Search for Lepton Number and Flavor Violation in K^{+} and π^{0} Decays

Searches for the lepton number violating K^{+}→π^{-}μ^{+}e^{+} decay and the lepton flavor violating K^{+}→π^{+}μ^{-}e^{+} and π^{0}→μ^{-}e^{+} decays are reported using data collected by the NA62 experiment at CERN in 2017-2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: B(K^{+}→π^{-}μ^{+}e^{+})<4.2×10^{-11}, B(K^{+}→π^{+}μ^{-}e^{+})<6.6×10^{-11} and B(π^{0}→μ^{-}e^{+})<3.2×10^{-10}. These results improve by 1 order of magnitude over previous results for these decay modes.

Detection of Human Papillomavirus DNA, P53 and KI67 Expression in Penile Carcinomas

Our study is aimed at evaluating the presence of p53 and Ki67 expression by immunohistochemistry in a series of 11 paraffin-embedded penile carcinomas. We also investigated the presence of Human Papillomavirus (HPV) DNA in these tumours and performed an accurate typing by DNA sequencing on positive samples. Immunohistochemistry (IHC) was performed with the anti-p53 and Ki67 mouse monoclonal antibodies. DNA extracted from small sections of each specimen was submitted to amplification with HPV specific general primers; PCR products of the proper length were purified and sequenced. IHC demonstrated nuclear accumulation of mutated p53 and Ki 67 expression in 10/11 tumour samples (90.9%). The prevalence of HPV DNA was 72.7%; the most prevalent type was HPV16. Sequencing analysis revealed the presence of HPV53 (12.5%), HPV18 (25%) and HPV16 (62.5%). Out of the p53 or Ki67 positive carcinomas the percentage of HPV positives was 80% and 70% respectively. Our results indicate that penile carcinoma is frequently associated to high risk HPV and with diffuse p53 and Ki67 expression.

NA62 and NA48/2 results on search for Heavy Neutral Leptons

In this paper we present new results on upper limits for the search of Heavy Neutral Leptons (HNL) with data collected by NA48/2 (2003-2004), NA62-RK (2007) and NA62 (2015) CERN experiments. The data collected with different trigger configuration allow to search for both long and short living heavy neutrinos in the mass range below the kaon mass. In addition the status of the search for K+ → π+vv with the NA62 detector will be briefly presented.

A quantitative systems pharmacology model of blood coagulation network describes in vivo biomarker changes in non-bleeding subjects

Essentials Baseline coagulation activity can be detected in non-bleeding state by in vivo biomarker levels. A detailed mathematical model of coagulation was developed to describe the non-bleeding state. Optimized model described in vivo biomarkers with recombinant activated factor VII treatment. Sensitivity analysis predicted prothrombin fragment 1 + 2 and D-dimer are regulated differently.

SUMMARY

Background Prothrombin fragment 1 + 2 (F1 + 2 ), thrombin-antithrombin III complex (TAT) and D-dimer can be detected in plasma from non-bleeding hemostatically normal subjects or hemophilic patients. They are often used as safety or pharmacodynamic biomarkers for hemostatis-modulating therapies in the clinic, and provide insights into in vivo coagulation activity. Objectives To develop a quantitative systems pharmacology (QSP) model of the blood coagulation network to describe in vivo biomarkers, including F1 + 2 , TAT, and D-dimer, under non-bleeding conditions. Methods The QSP model included intrinsic and extrinsic coagulation pathways, platelet activation state-dependent kinetics, and a two-compartment pharmacokinetics model for recombinant activated factor VII (rFVIIa). Literature data on F1 + 2 and D-dimer at baseline and changes with rFVIIa treatment were used for parameter optimization. Multiparametric sensitivity analysis (MPSA) was used to understand key proteins that regulate F1 + 2 , TAT and D-dimer levels. Results The model was able to describe tissue factor (TF)-dependent baseline levels of F1 + 2 , TAT and D-dimer in a non-bleeding state, and their increases in hemostatically normal subjects and hemophilic patients treated with different doses of rFVIIa. The amount of TF required is predicted to be very low in a non-bleeding state. The model also predicts that these biomarker levels will be similar in hemostatically normal subjects and hemophilic patients. MPSA revealed that F1 + 2 and TAT levels are highly correlated, and that D-dimer is more sensitive to the perturbation of coagulation protein concentrations. Conclusions A QSP model for non-bleeding baseline coagulation activity was established with data from clinically relevant in vivo biomarkers at baseline and changes in response to rFVIIa treatment. This model will provide future mechanistic insights into this system.

Precision medicine in the age of big data: The present and future role of large-scale unbiased sequencing in drug discovery and development

High throughput molecular and functional profiling of patients is a key driver of precision medicine. DNA and RNA characterization has been enabled at unprecedented cost and scale through rapid, disruptive progress in sequencing technology, but challenges persist in data management and interpretation. We analyze the state-of-the-art of large-scale unbiased sequencing in drug discovery and development, including technology, application, ethical, regulatory, policy and commercial considerations, and discuss issues of LUS implementation in clinical and regulatory practice.

Using a Systems Pharmacology Model of the Blood Coagulation Network to Predict the Effects of Various Therapies on Biomarkers

A number of therapeutics have been developed or are under development aiming to modulate the coagulation network to treat various diseases. We used a systems model to better understand the effect of modulating various components on blood coagulation. A computational model of the coagulation network was built to match in-house in vitro thrombin generation and activated Partial Thromboplastin Time (aPTT) data with various concentrations of recombinant factor VIIa (FVIIa) or factor Xa added to normal human plasma or factor VIII-deficient plasma. Sensitivity analysis applied to the model revealed that lag time, peak thrombin concentration, area under the curve (AUC) of the thrombin generation profile, and aPTT show different sensitivity to changes in coagulation factors' concentrations and type of plasma used (normal or factor VIII-deficient). We also used the model to explore how variability in concentrations of the proteins in coagulation network can impact the response to FVIIa treatment.

UniPR129 is a competitive small molecule Eph-ephrin antagonist blocking in vitro angiogenesis at low micromolar concentrations

BACKGROUND AND PURPOSE

The Eph receptor tyrosine kinases and their ephrin ligands are key players in tumorigenesis and many reports have correlated changes in their expression with a poor clinical prognosis in many solid tumours. Agents targeting the Eph-ephrin system might emerge as new tools useful for the inhibition of different components of cancer progression. Even if different classes of small molecules targeting Eph-ephrin interactions have been reported, their use is hampered by poor chemical stability and low potency. Stable and potent ligands are crucial to achieve robust pharmacological performance.

EXPERIMENTAL APPROACH

UniPR129 (the L-homo-Trp conjugate of lithocholic acid) was designed by means of computational methods, synthetized and tested for its ability to inhibit the interaction between the EphA2 receptor and the ephrin-A1 ligand in an elisa binding study. The ability of UniPR129 to disrupt EphA2-ephrin-A1 interaction was functionally evaluated in a prostate adenocarcinoma cell line and its anti-angiogenic effect was tested in vitro using cultures of HUVECs.

KEY RESULTS

UniPR129 disrupted EphA2-ephrin-A1 interaction with Ki = 370 nM in an elisa binding assay and with low micromolar potency in cellular functional assays, including inhibition of EphA2 activation, inhibition of PC3 cell rounding and disruption of in vitro angiogenesis, without cytotoxic effects.

CONCLUSIONS AND IMPLICATIONS

The discovery of UniPR129 represents not only a major advance in potency compared with the existing Eph-ephrin antagonists but also an improvement in terms of cytotoxicity, making this molecule a useful pharmacological tool and a promising lead compound.

Translation of anticancer efficacy from nonclinical models to the clinic

Mouse cancer models have provided critical insights into tumor biology; however, clinical translation of these findings has been challenging. This perspective posits that factors impacting on successful translation start with limitations in capturing human cancer pathophysiology and end with challenges in generating robust translatable preclinical end points. A comprehensive approach that considers clinically relevant mouse models with both an integrated biomarker strategy and a complementary modeling and simulation effort will strengthen the current oncology drug development paradigm.

Magnesium sulphate for prevention of eclampsia: are intramuscular and intravenous regimens equivalent? A population pharmacokinetic study

OBJECTIVE

To compare magnesium sulphate concentrations achieved by intramuscular and intravenous regimens used for the prevention of eclampsia.

SETTING

Low-resource obstetric hospitals in Nagpur and Vellore, India.

POPULATION

Pregnant women at risk for eclampsia due to hypertensive disease.

METHODS

A pharmacokinetic study was performed as part of a randomised trial that enrolled 300 women comparing intramuscular and intravenous maintenance regimens of magnesium dosing. Data from 258 enrolled women were analysed in the pharmacokinetic study. A single sample was drawn per woman with the expectation of using samples in a pooled data analysis.

MAIN OUTCOME MEASURES

Pharmacokinetic parameters of magnesium distribution and clearance.

RESULTS

Magnesium clearance was estimated to be 48.1 dl/hour, volume of distribution to be 156 dl and intramuscular bioavailability to be 86.2%. The intramuscular regimen produced higher initial serum concentrations, consistent with a substantially larger loading dose. At steady state, magnesium concentrations in the intramuscular and intravenous groups were comparable. With either regimen, a substantial number of women would be expected to have serum concentrations lower than those generally held to be therapeutic.

CONCLUSIONS

Clinical implications were that a larger loading dose for the intravenous regimen should be considered; where feasible, individualised dosing of magnesium sulphate would reduce the variability in serum concentrations and might result in more women with clinically effective magnesium concentrations; and lower dose magnesium sulphate regimens should be considered with caution.

Use of local hyperthermia as prophylaxis of fibrosis and modification in penile length following radical retropubic prostatectomy

OBJECTIVE

The aim of the study was to evaluate the effectiveness of local hyperthermia in reducing possible penile shortening following radical retropubic prostatectomy.

PATIENTS AND METHODS

The study population comprised 40 patients, aged 52-74 years, submitted to radical retropubic prostatectomy. Patients were divided into two groups of 20. In Group A, patients were submitted to local hyperthermia 3 weeks after surgery, three times a week, with treatment lasting 30 min. Patients received a total of 10 applications, which reached a local temperature of 39-40 degrees C. A second cycle was repeated after 1 month. In Group B, patients were submitted only to post-operative follow-up once a month. Penile length was measured in all patients both before and 3 months after surgery in the 'stretching phase' from the pubo-penile junction to the tip of the glans.

RESULTS

In Group A patients (hyperthermia treatment), no variation in penile length was observed in 16 cases (80%), while the reduction ranged from 0.5-1.5 cm in four cases (20%). In Group B, 12 patients (60%) showed a reduction in penile length ranging from 0.5-2.5 cm, while penile length remained unchanged in eight patients (40%).

CONCLUSIONS

Results of this study demonstrate a mild but statistically relevant reduction in penile shortening following low-grade, externally delivered penile hyperthermia, thus confirming the efficacy of this approach in preventing penile shortening caused by post-ischaemic fibrosis.

Are we optimizing gestational diabetes treatment with glyburide? The pharmacologic basis for better clinical practice

Glyburide's pharmacokinetics (PK) and pharmacodynamics have not been studied in women with gestational diabetes mellitus (GDM). The objective of this study was to assess steady-state PK of glyburide, as well as insulin sensitivity, beta-cell responsivity, and overall disposition indices after a mixed-meal tolerance test (MMTT) in women with GDM (n = 40), nonpregnant women with type 2 diabetes mellitus (T2DM) (n = 26), and healthy pregnant women (n = 40, MMTT only). At equivalent doses, glyburide plasma concentrations were approximately 50% lower in pregnant women than in nonpregnant subjects. The average umbilical cord/maternal plasma glyburide concentration ratio at the time of delivery was 0.7 +/- 0.4. Insulin sensitivity was approximately fivefold lower in women with GDM as compared with healthy pregnant women. Despite comparable beta-cell responsivity indices, the average beta-cell function corrected for insulin resistance was more than 3.5-fold lower in women with glyburide-treated GDM than in healthy pregnant women. Women with GDM in whom glyburide treatment has failed may benefit from alternative medication or dosage escalation; however, fetal safety should be kept in mind.

Personalized dosing of cyclophosphamide in the total body irradiation-cyclophosphamide conditioning regimen: a phase II trial in patients with hematologic malignancy

This study investigates the efficacy and safety of personalized cyclophosphamide (CY) dosing in 50 patients receiving CY along with total body irradiation (TBI). Participants received CY 45 mg/kg with subsequent therapeutic drug monitoring using Bayesian parameter estimation to personalize the second CY dose to a target area under the curve (AUC) for carboxyethylphosphoramide mustard (CEPM) (a reporter molecule for CY-derived toxins) and for hydroxycyclophosphamide (to ensure engraftment). The mean second CY dose was 66 mg/kg; the total dose ranged from 45 to 145 mg/kg. After completion of this phase II study, we compared participants' clinical outcomes with those of concurrent controls (n = 100) who received TBI along with standard CY doses of 120 mg/kg. Patients receiving personalized CY dosing had significantly lower postconditioning peak total serum bilirubin (P = 0.03); a 38% reduction in the hazard of acute kidney injury (AKI) (P = 0.03); and nonrelapse and overall survival rates similar to those in the controls (P = 0.70 and 0.63, respectively) despite the lower doses of CY administered to most of the patients in the personalized dosage group.

2-Thiazolylimino/heteroarylimino-5-arylidene-4-thiazolidinones as new agents with SHP-2 inhibitory action

SHP-2, a nonreceptor protein tyrosine phosphatase encoded by the PTPN11 gene, mediates cell signaling by growth factors and cytokines via the RAS/MAP kinase pathway. Somatic mutations in PTPN11 gene account for approximately 18% of juvenile myelomonocytic leukemia (JMML) patients. Moreover, SHP-2 mutations leading to continuously active enzyme were found in more than 50% of Noonan syndrome patients and are considered to be responsible for the high tendency of these patients to juvenile leukemias and other cancer types. Recently SHP-2 became a new drug target, but till now little has been done in this field. In the present study, 17 2-thiazolylimino/heteroarylimino-5-arylidene-4-thiazolidinones divided into three series of derivatives bearing thiazole-, benzo[d]thiazole-, and benzo[d]isothizole rings were tested for SHP-2 inhibitory activity. Most of the compounds were good SHP-2 inhibitors. Benzo[d]thiazole derivatives exhibited the best inhibitory action. Docking studies revealed that hydrophobic interactions and hydrogen bond formation stabilize enzyme-inhibitor complex.

Identification of IVGTT minimal glucose model by nonlinear mixed-effects approaches

Glucose minimal model parameters are commonly estimated by applying weighted nonlinear least squares to each individual subject's data. Sometimes, parameter precision is not satisfactory, especially in "data poor" conditions. In this work, the use of population analysis through nonlinear-mixed effects models is evaluated and its performance tested against the parameter estimates obtained by the standard individual approach through weighted nonlinear least squares. In particular, we compared the performance of two likelihood approximation methods to estimate nonlinear mixed-effects model parameters, i.e. the first-order conditional estimation (FOCE) and the Laplace approximation (Laplace) methods. The results show that nonlinear mixed-effects population modeling using the FOCE approximation can be successfully used in order to accurately estimate individual minimal model parameters.

Amoxicillin pharmacokinetics in pregnant women: modeling and simulations of dosage strategies

Amoxicillin is recommended for anthrax prevention in pregnancy. The objective of this study was to evaluate the pharmacokinetics of amoxicillin during pregnancy and postpartum (PP). Sixteen women received amoxicillin during gestation (18-22 weeks (T2) and 30-34 weeks (T3)) as well as 3 months postpartum (PP) to evaluate single-dose pharmacokinetics. Amoxicillin compartmental pharmacokinetic parameters were used to simulate amoxicillin concentration-time profiles following different dosage strategies. Amoxicillin CL(renal) (T2: 24.8+/-6.7 l/h, P<0.001; T3: 24.0+/-3.9 l/h, P<0.001; and PP: 15.3+/-2.6 l/h) and renal CL(secretion) (T2: 280+/-105 ml/min, P<0.002; T3: 259+/-54 ml/min, P<0.001; and PP: 167+/-47 ml/min) were higher during pregnancy than postpartum. Simulations suggest that amoxicillin concentrations adequate to prevent anthrax may be difficult to achieve during pregnancy and postpartum. Increases in amoxicillin CL(renal) and renal CL(secretion) reflect increases in filtration and secretory transport or diminished reabsorption in the kidneys. Amoxicillin may not be an appropriate antibiotic for post-anthrax exposure prophylaxis.

Detection of human papillomavirus DNA, p53 and ki67 expression in penile carcinomas

Our study is aimed at evaluating the presence of p53 and Ki67 expression by immunohistochemistry in a series of 11 paraffin-embedded penile carcinomas. We also investigated the presence of Human Papillomavirus (HPV) DNA in these tumours and performed an accurate typing by DNA sequencing on positive samples. Immunohistochemistry (IHC) was performed with the anti-p53 and Ki67 mouse monoclonal antibodies. DNA extracted from small sections of each specimen was submitted to amplification with HPV specific general primers; PCR products of the proper length were purified and sequenced. IHC demonstrated nuclear accumulation of mutated p53 and Ki 67 expression in 10/11 tumour samples (90.9%). The prevalence of HPV DNA was 72.7%; the most prevalent type was HPV16. Sequencing analysis revealed the presence of HPV53 (12.5%), HPV18 (25%) and HPV16 (62.5%). Out of the p53 or Ki67 positive carcinomas the percentage of HPV positives was 80% and 70% respectively. Our results indicate that penile carcinoma is frequently associated to high risk HPV and with diffuse p53 and Ki67 expression.

Role of hyperthermia in the treatment of Peyronie's disease: a preliminary study

OBJECTIVE

Previous experience in the treatment of plaque with hyperthermia in orthopaedics led the authors to investigate the effectiveness of this approach in patients with Peyronie's disease.

PATIENTS AND METHODS

The study population comprised 60 patients (aged 36-76 years) with advanced Peyronie's disease. Patients were divided into two groups (A and B), with 30 in each. Group A patients underwent local hyperthermia treatment, with 30-min treatment sessions twice a week for 5 weeks. Patients received a total of 10 applications, which reached a local temperature of 39-40 degrees C. A second cycle was repeated after a 1-month interval for a total of 20 treatment sessions. Group B patients were treated with intra-plaque infiltrations using 10 mg verapamil; they received one infiltration once a week for 3 months. Differences between the two groups, as well as between variables (before and after treatment), were analysed using Student t-test and Fisher test.

RESULTS

Hyperthermia significantly reduced plaque size and penile curvature and led to an increase in mean scores of erectile function (EF) domain, while verapamil had no such effects. Haemodynamic parameters were not significantly modified in either group. Hyperthermia caused significantly fewer side effects than verapamil infiltrations and was significantly more effective in preventing disease progression. There were no significant differences between the two groups in terms of pain reduction during erection.

CONCLUSIONS

Results of this study stress the efficacy of hyperthermia in the treatment of advanced Peyronie's disease.

Protective effects of benzisothiazolylamidines on IL-1 beta induced alterations in human articular chondrocyte metabolism

The in vitro effects on human articular chondrocytes were evaluated for a series of N-benzo[d]isothiazol-3-yl-amidines, bearing as pharmacophoric moiety the nonacidic isosteric nitrogen analogue of the carboxylic group. The aim was to verify their effectiveness in articular diseases, such as arthritis. Human chondrocytes were treated with IL-1beta in the presence of a series of N-benzo[d]isothiazol-3-yl-amidines at a concentration of 100 microg/mL. After 120 h, the amount of glycosaminoglycans (GAGs), the production of nitric oxide (NO) and the inhibition of metalloproteinases (MMP-3) and prostaglandin (PGE2) were measured. Nitrite production induced by inflammatory IL-1beta on cultured chondrocytes was inhibited by the N-benzo[d]isothiazol-3-yl-amidines tested, in particular by N-benzo[d]isothiazol-3-yl-benzamidine, which was the most active. Concerning the effects on GAGs, all the tested benzisothiazolylamidines, and in particular N-benzo[d]isothiazol-3-yl-acetamidine, prevented the depletion of proteoglycan induced by IL-1beta. Inhibitory effects of the tested compounds on MMP-3 activity and on PGE2 production were also observed.

Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetes

PURPOSE

To investigate the efficacy and tolerability of oral propionyl-L-carnitine (PLC) plus sildenafil in men with erectile dysfunction (ED) and diabetes unresponsive to sildenafil monotherapy.

MATERIALS AND METHODS

Patients with medically documented ED of organic or mixed aetiology and diabetes (type 1 and 2) were randomised to receive oral PLC (2 g/day) plus sildenafil (50 mg twice weekly) (20 patients, Group 1) or sildenafil alone (20 patients, Group 2), in a double-blind, fixed-dose study. All patients had been previously treated unsuccessfully with a minimum of eight administrations of sildenafil. Efficacy was evaluated using the International Index of Erectile Function (IIEF) questionnaire: total score, subscores for questions 3 (Q3; achieving an erection) and 4 (Q4; maintaining an erection) and global efficacy question (GEQ: 'Has treatment improved your erections?'). Patients Event Logs were also used.

RESULTS

After 24 weeks of treatment, mean scores for IIEF Q3 and Q4 had improved significantly in patients of Group 1 (4.25 +/- 0.63 and 3.95 +/- 1.0) compared with Group 2 (2.9 +/- 0.71 and 2.7 +/- 0.96) (p < 0.01). Moreover, the percentage of patients with improved erections (GEQ 68% vs. 23%) and successful intercourse attempts (76% vs. 34%) was significantly increased in Group 1 compared with Group 2 (p < 0.01). Fourteen (70%) patients in Group 1 and four (20%) in Group 2 reported an increase in mean IIEF EF domain score of > or = 4 (p < 0.01). Treatments were well tolerated and no patient discontinued study medication. Two patients in Group 1 reported mild gastric pain.

CONCLUSIONS

Salvage therapy with PLC plus sildenafil was more effective than sildenafil in the treatment of ED in patients with diabetes refractory to sildenafil monotherapy.

Study of local anesthetic activity of some derivatives of 3-amino-benzo-[d]-isothiazole

On the basis of computer prediction of biological activity by PASS and toxicity by DEREK, the most prospective 18 alkylaminoacyl derivatives of 3-amino-benzo-[d]-isothiazole were selected. Their local anesthetic action was assessed using an in vitro preparation of the isolated peroneal nerve of the frog. The local anesthetics action of the compounds was assessed according to the time required for each compound to reduce the amplitude of the evoked compound action potential (CAP). Lidocaine was used as the control compound. The results show that the tested compounds can be divided into three groups: (a) compounds with action similar to lidocaine, (b) compounds with action lower than lidocaine and (c) compounds which block completely the evoked CAP, but after the compound was removed and replaced with normal saline showed no recovery of the potential at all. QSAR studies showed that polarizability, polarity and presence of five-membered rings in molecules have a positive influence on local anesthetic activity, while contributions of aromatic CH and singly bonded nitrogen are negative. Since estimations from PASS probabilities to find local anesthetic activity in the most active compounds were less than 50%, these compounds may be considered as new chemical entities (NCEs).

Computer aided prediction of biological activity spectra: evaluating versus known and predicting of new activities for thiazole derivatives

Computer aided prediction of biological activity spectra by the computer program PASS was applied to a set of 89 new thiazole derivatives. Experimentally tested activities (NSAID, local anaesthetic and antioxidant) coincide with the experiment in 70.8% cases, that exceeds significantly the random guess-work (approximately 0.1%). Therefore, computer aided prediction using the Prediction of Activity Spectra for Substances (PASS) system (http://www.ibmh.msk.su/PASS) provides a reliable basis for planning of synthesis and experimental study for new compounds. New psychotropic activities are predicted for some compounds from the series under study. In particular, 7, 44 and 55 compounds likely have anxiolytic, anticonvulsant and cognition enhancer effects, respectively. Most of these compounds have the estimated values of probability to be active (Pa) less than 60%. Therefore, if their activity will be confirmed by the experiment, they might occur to be New Chemical Entities.

An evaluation of extended vs weighted least squares for parameter estimation in physiological modeling

Weighted least squares (WLS) is the technique of choice for parameter estimation from noisy data in physiological modeling. WLS can be derived from maximum likelihood theory, provided that the measurement error variance is known and independent of the model parameters and the weights are calculated as the inverse of the measurement error variance. However, using measured values in lieu of predicted values to quantify the measurement error variance is approximately valid only when the noise in the data is relatively low. This practice may thus introduce sampling variation in the resulting estimates, as weights can be seriously mis-specified. To avoid this, extended least squares (ELS) has been used, especially in pharmacokinetics. ELS uses an augmented objective function where the measurement error variance depends explicitly on the model parameters. Although it is more complex, ELS accounts for the Gaussian maximum likelihood statistical model of the data better than WLS, yet its usage is not as widespread. The use of ELS in high data noise situations will result in more accurate parameter estimates than WLS (when the underlying model is correct). To support this claim, we have undertaken a simulation study using four different models with varying amounts of noise in the data and further assuming that the measurement error standard deviation is proportional to the model prediction. We also motivate this in terms of maximum likelihood and comment on the practical consequences of using WLS and ELS as well as give practical guidelines for choosing one method over the other.

Serum and lower respiratory tract drug concentrations after tobramycin inhalation in young children with cystic fibrosis

OBJECTIVES

To assess the serum and lower respiratory tract tobramycin concentrations (C(T)) produced by a single dose of tobramycin for inhalation delivered by a nebulizer and a compressor in patients with cystic fibrosis (CF) 6 months to 6 years of age.

STUDY DESIGN

We performed a dose escalation study of serum C(T) measured before and 0.5, 1, 2, and 4 hours after a single dose of inhaled tobramycin, either 180 mg (10 patients) or 300 mg (19 patients). In a separate group of 12 patients, epithelial lining fluid (ELF) C(T) was measured by bronchoalveolar lavage 30 to 45 minutes after a 300-mg dose.

RESULTS

A 180-mg dose of inhaled tobramycin produced a mean peak serum C(T) of 0.5 microg/mL (SD 0.4; range, <0.2 to 1.4 microg/mL). A 300-mg dose produced a mean peak serum C(T) of 0.6 microg/mL (SD 0.5; range, <0.2 to 1.2 microg/mL). These peak values are well below the accepted maximum trough concentration with parenteral dosing (2 microg/mL). The target ELF C(T) was 20 microg/mL, 10-fold greater than the minimal inhibitory concentration for most Pseudomonas aeruginosa isolates from very young patients with CF (2 microg/mL). Mean ELF C(T) was 90 microg/mL (SD 54; range, 16 to 204 microg/mL) and exceeded the target concentration in 11 patients.

CONCLUSION

In patients with CF ages 6 months to 6 years, a single 300-mg dose of inhaled tobramycin appears to produce safe peak serum concentrations and drug concentrations in the bactericidal range in the lower respiratory tract.

Impact of cyclosporine and low-dose steroid therapy on insulin sensitivity and beta-cell function in patients with long-term liver grafts

To examine whether factors controlling glucose tolerance, i.e., insulin sensitivity (SI) and first-(phi1) and second-phase insulin secretion (phi2), are impaired in after orthotopic liver transplantation (OLT), they were assesssed in patients that had undergone OLT for cirrhosis (n = 10) with cyclosporin A and low-dose steroid therapy (5 mg prednisone per day) and were compared with those of healthy matched control subjects (n = 10). These factors were determined by means of computer-based analysis of frequently sampled intravenous glucose tolerance tests (FSIGTT). Glucose and insulin profiles (posthepatic insulin) did not differ between both groups, whereas C-peptide levels (prehepatic insulin) were elevated in the transplant group after the FSIGTT, indicating an increased hepatic insulin degradation. SI and (phi1 did not differ between both groups. phi2, however, was significantly enhanced (23.94 +/- 2.63 vs 13.88 +/- 1.25 min(-1), P < 0.05). These results indicate that cyclosporine and low-dose steroid therapy do not impair SI and phi1. However, enhanced phi2 compensates the increased hepatic insulin clearance.

Triglyceride enrichment of HDL does not alter HDL-selective cholesteryl ester clearance in rabbits

Triglyceride (TG) enrichment of high density lipoprotein (HDL), which occurs in hypertriglyceridemic states, significantly enhances the rate at which HDL apolipoprotein (apo)A-I is cleared from the circulation of healthy humans. In the New Zealand White (NZW) rabbit, a species naturally deficient in hepatic lipase (HL), TG enrichment of HDL requires prior lipolytic modification to enhance apoA-I clearance. However, the effect of TG enrichment of HDL on the subsequent clearance of HDL cholesteryl ester (CE) has not previously been examined in vivo. Therefore, we investigated, in the NZW rabbit, the effect of ex vivo TG enrichment of rabbit HDL (by incubation with human very low density lipoprotein) on the clearance of HDL CE and apoA-I radiolabeled with (3)H-cholesteryl oleyl ether and with (131)I, respectively. In nine experiments, TG enrichment of rabbit HDL resulted in an 87% average increase in HDL TG and a corresponding 31% reduction in HDL CE content. The calculated apoA-I and CE fractional catabolic rates associated with TG-rich versus fasting HDL tracers were not significantly different (apoA-I: 0.119 +/- 0.017 vs. 0.107 +/- 0.024 pools per h, P = 0.68; CE: 0.147 +/- 0.014 vs. 0.114 +/- 0.019 pools per h, P = 0.20). In an animal model deficient in HL, TG enrichment of HDL did not alter the rates of HDL apoA-I or selective CE clearance. Further studies are needed to determine whether, in the presence of HL, TG enrichment of HDL alters selective HDL CE clearance.

The iterative two-stage population approach to IVGTT minimal modeling: improved precision with reduced sampling. Intravenous glucose tolerance test

The minimal model method is widely used to estimate glucose effectiveness (S(G)) and insulin sensitivity (S(I)) from intravenous glucose tolerance test (IVGTT) data. In the standard protocol (sIVGTT, 0.33 g/kg glucose bolus given at time 0), which allows the simultaneous assessment of beta-cell function, the precision of the individualized estimates often degrades and particularly so in the presence of reduced sampling schedules. Here, we investigated the use of a population approach, the iterative two-stage (ITS) approach, to analyze 16 sIVGTTs in healthy subjects and to obtain refined estimates of S(G) and S(I) in the population and in the individual subjects. The ITS is based on calculation of the population mean and standard deviation of the parameters at each iteration and then use of them as prior information for the individual analyses. Theoretically, the use of a prior in the ITS should improve the precision of the individual estimates. The customary approach (standard two stage, STS), where modeling is performed separately for each individual subject, does not take the population knowledge into account. We used both frequent (FSS, 30 samples) and (quasi-optimally) reduced (RSS, 14 samples) sampling schedules. For the FSS, STS gave estimates (mean +/- SD) for S(G) = 2.66 +/- 1.09 x 10(-2). min(-1) and S(I) = 6.46 +/- 6.99 10(-4). min(-1). microU(-1). ml, with an average precision of 51 (range 5-176) and 33% (3-91), respectively. RSS radically worsened the precision of both S(G) and S(I). However, RSS and ITS gave S(G) = 2.59 +/- 0.73 and S(I) = 6.06 +/- 7.28, with an average precision of 23 (12-42) and 27% (), respectively. In conclusion, population minimal modeling of sIVGTT data improves the precision of individual estimates of glucose effectiveness and insulin sensitivity, as the theory predicts, and, even with reduced sampling, the improvement is substantial.

Severity of HCV-induced liver damage alters glucose homeostasis in noncirrhotic patients with chronic HCV infection

BACKGROUND/AIMS

To investigate the link between hepatitis C infection and glucose intolerance, we measured insulin sensitivity, glucose effectiveness and beta-cell secretion in noncirrhotic HCV-infected patients with normal glucose tolerance according to WHO criteria as assessed by oral glucose tolerance tests.

METHODS

Glucose, insulin and C-peptide data from frequently sampled intravenous glucose tolerance tests were analyzed using the minimal modeling technique for glucose and C-peptide to determine insulin sensitivity, glucose effectiveness, first and second phase insulin secretion in noncirrhotic HCV-infected patients (n = 10) and in healthy control subjects (n = 10). Histological activity index (HAI) as well as the extent of fibrosis were evaluated by scoring liver biopsies.

RESULTS

Insulin sensitivity (2.72 +/- 1.63 vs. 6.84 +/- 1. 20 10(-4) min(-1) per microU/ml, p < 0.01) and glucose effectiveness (2.29 +/- 0.45 vs. 2.89 +/- 0.39 10(-2) min(-1), p < 0.05) ere significantly lower in patients with HCV-induced liver disease. Insulin sensitivity was negatively related to serum alanine aminotransferase (r = -0.47, p < 0.05) and aspartate aminotransferase concentrations (r = -0.65, p < 0.05). Multiple linear regression analysis revealed a strong relation of insulin sensitivity with fibrosis score and HAI (r = -0.82, p < 0.02 for both). Second phase insulin secretion was significantly enhanced in HCV-infected patients (14.30 +/- 2.04 vs. 8.29 +/- 1.65 min(-1), p < 0.05).

CONCLUSIONS

HCV-infected patients with normal glucose tolerance are insulin and glucose resistant. The impairment of glucose tolerance appears to be closely related with the severity of HCV-induced liver damage.

Identifiability and interval identifiability of mammillary and catenary compartmental models with some known rate constants

The identifiability problem is addressed for n-compartment linear mammillary and catenary models, for the common case of input and output in the first compartment and prior information about one or more model rate constants. We first define the concept of independent constraints and show that n-compartment linear mammillary or catenary models are uniquely identifiable under n-1 independent constraints. Closed-form algorithms for bounding the constrained parameter space are then developed algebraically, and their validity is confirmed using an independent approach, namely joint estimation of the parameters of all uniquely identifiable submodels of the original multicompartmental model. For the noise-free (deterministic) case, the major effects of additional parameter knowledge are to narrow the bounds of rate constants that remain unidentifiable, as well as to possibly render others identifiable. When noisy data are considered, the means of the bounds of rate constants that remain unidentifiable are also narrowed, but the variances of some of these bound estimates increase. This unexpected result was verified by Monte Carlo simulation of several different models, using both normally and lognormally distributed data assumptions. Extensions and some consequences of this analysis useful for model discrimination and experiment design applications are also noted.

Pubertal adolescent male-female differences in insulin sensitivity and glucose effectiveness determined by the one compartment minimal model

Most studies of insulin sensitivity in puberty have been cross-sectional and have not been able to longitudinally address changes that might occur. In addition, these studies were unable to separate out glucose's ability to stimulate its own disposal (glucose effectiveness, S(G)) from insulin sensitivity (S(I)) or to separate the hepatic and peripheral effects of insulin. To address these problems, we used the frequently sampled i.v. glucose tolerance test with [6,6]D2 glucose to study S(G)* and S(I)* in 24 children (Tanner stage 1-3) at 6-mo intervals over an 18-mo period. Mean overnight GH and fasting GH binding protein (GHBP), IGF-1, and leptin levels were also measured. S(G)* did not differ between the sexes or Tanner stages. S(I)* did not differ between Tanner stages for either sex and was higher in boys than in girls. Hepatic insulin resistance did not differ between sexes or Tanner stages. S(G)* was not related to any of the other variables measured. S(I)* was negatively related to BMI, GHBP, IGF1, and leptin. These results demonstrate that insulin sensitivity is greater in prepubertal and early pubertal boys than in girls and is primarily determined by body mass effects.

2-Amino-Benzo[d]isothiazol-3-one derivatives: synthesis and assessment of their antiplatelet/spasmolytic effects

We describe a series of 2-amino-benzo[d]isothiazol-3-one derivatives (2-8), which were synthesized and screened in vitro for inhibition of platelet aggregation and for their spasmolytic activity, with the awareness that the development of antiplatelet agents with additional vasodilation activity could be beneficial in the treatment of various vaso-occlusive disorders. The tested compounds show a powerful antiplatelet activity and various modifications resulted in molecules possessing antiaggregating effects as well as spasmolytic actions.

Cellular energetics analysis by a mathematical model of energy balance: estimation of parameters in human skeletal muscle

Cellular energy balance requires that the physiological demands by ATP-utilizing functions be matched by ATP synthesis to sustain muscle activity. We devised a new method of analysis of these processes in data from single individuals. Our approach is based on the logic of current information on the major mechanisms involved in this energy balance and can quantify not directly measurable parameters that govern those mechanisms. We use a mathematical model that simulates by ordinary, nonlinear differential equations three components of cellular bioenergetics (cellular ATP flux, mitochondrial oxidative phosphorylation, and creatine kinase kinetics). We incorporate data under resting conditions, during the transition toward a steady state of stimulation and during the transition during recovery back to the original resting state. Making use of prior information about the kinetic parameters, we fitted the model to previously published dynamic phosphocreatine (PCr) and inorganic phosphate (P(i)) data obtained in normal subjects with an activity-recovery protocol using (31)P nuclear magnetic resonance spectroscopy. The experiment consisted of a baseline phase, an ischemic phase (during which muscle stimulation and PCr utilization occurred), and an aerobic recovery phase. The model described satisfactorily the kinetics of the changes in PCr and P(i) and allowed estimation of the maximal velocity of oxidative phosphorylation and of the net ATP flux in individuals both at rest and during stimulation. This work lays the foundation for a quantitative, model-based approach to the study of in vivo muscle energy balance in intact muscle systems, including human muscle.

Regulation of glucose tolerance in patients after liver transplantation: impact of cyclosporin versus tacrolimus therapy

BACKGROUND

We investigated the factors regulating glucose homeostasis in 10 healthy (control) subjects, as well as in stable, long-term, liver-grafted patients receiving monotherapy in the form of either cyclosporin A (n=10) or tacrolimus (n=10).

METHODS

We measured insulin sensitivity, first- and second-phase insulin secretion, with a minimal modeling technique based on the analysis of glucose, insulin, and C-peptide profiles during frequently sampled intravenous glucose tolerance tests (FSIGTT). Proinsulin levels, as a marker of beta-cell dysfunction, were measured in the fasting state and during FSIGTT.

RESULTS

Glucose and insulin concentrations before and after glucose loading did not differ in liver transplant patients and in control subjects. Fasting C-peptide levels in both liver-grafted groups were higher than in healthy subjects and remained elevated during FSIGTT (P<0.05). Intravenous glucose tolerance [(K(G)), i.e. the slope of the regression of logarithm of the blood glucose concentrations vs. time], insulin sensitivity, and first-phase insulin secretion did not differ in liver-grafted groups and healthy subjects. Second-phase insulin secretion was about 56% higher in liver-grafted patients than in controls (P<0.05). Body mass index was the overall determinant of insulin sensitivity in all groups.

CONCLUSIONS

Long-term monotherapy with cyclosporin A or tacrolimus has no deleterious effects on insulin sensitivity, first-phase insulin secretion, and insulin synthesis in liver transplant patients. Normal insulin sensitivity (posthepatic insulin effect) and enhanced second-phase insulin secretion (prehepatic insulin) point to an accelerated hepatic insulin clearance rate in liver transplant patients. Increased hepatic insulin clearance is compensated by enhanced insulin secretion, indicating that insulin clearance is the major determinant of pancreatic function in liver-grafted patients.

Synthesis and correlations between experimental and calculated lipophilic indices of new 1,2-benzisothiazole derivatives with potential antimicrobial activity

Five series of new hydrazones (1a-m, 2a-m, 3a-m, 4a-m, 5a-m) with potential antimicrobial activity were synthesized from cyclic (1 and 4) or acyclic (2, 3 and 5) 1,2-benzisothiazolylhydrazides and characterized. Condensation of the appropriate hydrazide with aldehydes afforded the designed compounds. Aldehydes carrying different hydrophobic substituents were used and the five series were designed so that the hydrophobicity also varied among congeners. Retention parameters were measured by HPLC employing a deactivated alkyl-bonded silica column and different eluent systems (methanol-aqueous buffer, acetonitrile-water). The hydrophobicity chromatographic parameters (log k') were compared with those provided by measurement of partitioning of solutes between n-octanol and water (log P), and with theoretical partition coefficients, calculated by a fragmental method and scaled according to the experimental values. Correlations between different hydrophobicity indices are reported and discussed.

Evidence for impaired glucose effectiveness in cirrhotic patients after liver transplantation

To evaluate the impact of acute and chronic liver disease and single immunosuppression (cyclosporine A [CSA] or FK506) on insulin sensitivity and glucose effectiveness in liver-grafted patients, we performed a frequently sampled intravenous glucose tolerance test (FSIGTT) in nondiabetic patients after orthotopic liver transplantation (OLT) with acute liver failure ([ALF] group, n = 9, with CSA therapy), in patients after OLT with chronic liver disease (CSA group, n = 8; FK506 group, n = 8), and in 9 healthy control subjects. Insulin sensitivity and glucose effectiveness were determined by analyzing glucose and insulin data from the FSIGTT with Bergman's minimal model technique for glucose. The intravenous glucose tolerance index ([KG] ie, the slope of the regression of the logarithm of blood glucose concentration) was not different between the ALF group (2.17 +/- 0.16 min(-1)) and controls (2.29 +/- 0.13 min(-1)), but was lower (P < .05) in both groups with chronic liver disease (CSA group, 1.46 +/- 0.1; FK506 group, 1.61 +/- 0.11 min(-1)) compared with the ALF group (P < .05). A positive relation for the KG and glucose effectiveness was found in all liver-grafted patients and controls. Insulin sensitivity was not different between all liver-grafted patients and controls. The body mass index (BMI) was the overall determinant of insulin sensitivity in all groups. Single immunosuppressive therapy does not impair insulin sensitivity in liver-grafted patients. The lower glucose effectiveness in liver-grafted patients with chronic liver disease but not in patients after ALF points to a defect in the regulation of glucose-mediated glucose uptake in peripheral tissue.

Evaluation of factors controlling glucose tolerance in patients with HCV infection before and after 4 months therapy with interferon-alpha

BACKGROUND

Epidemiological data suggest that chronic hepatitis C virus (HCV) infection may contribute to the development of diabetes mellitus. Therapy of HCV infection with recombinant interferon-alpha (r-IFN-alpha) can also impair of glucose metabolism.

METHODS

To investigate the impact of HCV infection and the therapy with r-IFN-alpha on glucose metabolism we measured insulin sensitivity, glucose effectiveness, and first and second phase insulin secretion, using the minimal modelling analysis of frequently sampled intravenous glucose tolerance tests in 13 nondiabetic patients with HCV-induced liver disease before and after therapy with r-INF-alpha (6 x 106 U, subcutaneously, three times a week over 4 months). Liver biopsy was performed to evaluate and score liver fibrosis as a marker of HCV-induced cell injury.

RESULTS

Insulin sensitivity (r = - 0.59, P < 0.05) and first phase insulin secretion (r = - 0.66, P < 0.03) were negatively related to the fibrosis score. Insulin sensitivity rose from 1.96 (SEM 0.37, n = 8) to 5.69 (SEM 0.99, n = 8) 10-4 min-1 per microU mL-1 (P < 0.01) in responders and from 2.51 (SEM 0.61, n = 5) to 6.95 (SEM 1.99, n = 5) in nonresponders after 4 months r-INF-alpha therapy. Fasting free fatty acids decreased significantly to about 50% (P < 0.01) in patients with and without therapy response after 4 months, whereas first phase insulin secretion did not change.

CONCLUSIONS

HCV-induced liver injury is related to the deterioration of insulin sensitivity and first phase insulin response, thus impairing glucose homeostasis in these HCV-infected patients. The administration of r-INF-alpha three times a week over 4 months is not associated with an impairment of glucose homeostasis.

Individual prior information in a physiological model of 2H8-toluene kinetics: an empirical Bayes estimation strategy

Physiologically-based toxicokinetic (PBTK) models are widely used to quantify whole-body kinetics of various substances. However, since they attempt to reproduce anatomical structures and physiological events, they have a high number of parameters. Their identification from kinetic data alone is often impossible, and other information about the parameters is needed to render the model identifiable. The most commonly used approach consists of independently measuring, or taking fom literature sources, some of the parameters, fixing them in the kinetic model, and then performing model identification on a reduced number of less certain parameters. This results in a substantial reduction of the degrees of freedom of the model. In this study, we show that this method results in final estimates of the free parameters whose precision is overestimated. We then compared this approach with an empirical Bayes approach, which takes into account not only the mean value, but also the error associated with the independently determined parameters. Blood and breath 2H8-toluene washout curves, obtained in 17 subjects, were analyzed with a previously presented PBTK model suitable for person-specific dosimetry. Model parameters with the greatest effect on predicted levels were alveolar ventilation rate QPC, fat tissue fraction VFC, blood-air partition coefficient Kb, fraction of cardiac output to fat Qa/co and rate of extrahepatic metabolism Vmax-p. Differences in the measured and Bayesian-fitted values of QPC, VFC and Kb were significant (p < 0.05), and the precision of the fitted values Vmax-p and Qa/co went from 11 +/- 5% to 75 +/- 170% (NS) and from 8 +/- 2% to 9 +/- 2% (p < 0.05) respectively. The empirical Bayes approach did not result in less reliable parameter estimates: rather, it pointed out that the precision of parameter estimates can be overly optimistic when other parameters in the model, either directly measured or taken from literature sources, are treated as known without error. In conclusion, an empirical Bayes approach to parameter estimation resulted in a better model fit, different final parameter estimates, and more realistic parameter precisions.

Comparison of in vitro and ex vivo antiplatelet effects of 1,2-benzisothiazolin-3-one and its 2-amino derivative

The in vitro and ex vivo antiplatelet effects of 2-amino-1,2-benzisothiazolin-3-one (1) are compared with those of its parent compound 1,2-benzisothiazolin-3-one (2) and with acetylsalicylic acid (ASA) against different agonists. 2-Amino-1,2-benzisothiazolin-3-one inhibits adenosine diphosphate (ADP)-, arachidonic acid (AA)- and collagen-induced human platelet aggregation in vitro, with IC50 values of 8.90 x 10(-5), 1.50 x 10(-6) and 5.11 x 10(-8) mol/l, respectively. The strong inhibitory activity is significant not only for collagen but also for AA-induced aggregation. The same compound inhibits ex vivo collagen- and particularly AA-induced rabbit platelet aggregation at the tested dose of 10 mg/kg i.m. In view of the potential use of 2-amino-1,2-benzisothiazolin-3-one as antithrombotic agent, the log P values for both 1,2-benzisothiazolin-3-one derivatives 1 and 2 are determined, to gain an understanding of the significance of the 2-amino group in the 1,2-benzisothiazolin-3-one moiety with respect to the biological activity under study.

Interferon-alpha improves glucose tolerance in diabetic and non-diabetic patients with HCV-induced liver disease

This pilot study was initiated to evaluate factors controlling glucose tolerance in patients with hepatitis C virus-induced liver disease before and after therapy with recombinant interferon-alpha (r-INF-alpha). Fifteen patients with histologically and serologically proven hepatitis C infection underwent oral and frequently sampled intravenous glucose tolerance tests (FSIGTT) before and after four months of therapy (6 x 106 U r-INF-alpha, subcutaneously, three times a week). Glucose, insulin and C-peptide data from FSIGTT were analysed using the minimal modeling technique to determine insulin sensitivity, glucose effectiveness and first and second phase insulin secretion. According to the WHO criteria 13 patients, had normal glucose tolerance; diabetes mellitus was diagnosed in 2 patients. In the morning following the last r-INF-alpha injection four months later, insulin sensitivity improved significantly in hepatitis C virus-infected patients with normal glucose tolerance (2.17 +/- 0.37 vs. 6.18 +/- 0.94 10(-4) min(-1) per microU/ml, p < 0.001) and with diabetes mellitus (0.86 to 2.61; 0.46 to 1.06 10(-4) min(-1) per microU/ml). This effect was independent of the extent of fibrosis, virus load before treatment and therapy response. First phase insulin secretion increased in non-diabetic (139.2 +/- 17.1 vs. 200.0 +/- 32.7, p < 0.05) and diabetic patients with HCV infection (55.24 to 118.5; 84.23 to 261.1). Moreover, free fatty acid concentrations in all HCV-infected patients were significantly reduced (0.48 +/- 0.01 vs 0.21 +/- 0.03 mmol/l, p < 0.01). Therapy with recombinant interferon-alpha is associated with an amelioration of glucose tolerance in non-diabetic and diabetic HCV-infected patients.