To B(enign) or Not to B: functionalisation of variant in a mild form of argininosuccinate lyase deficiency identified through newborn screening.

Argininosuccinate lyase (ASL) deficiency is an autosomal recessive disorder of the urea cycle with a diverse spectrum of clinical presentation that is detectable in newborn screening. We report an 8-year-old girl with ASL deficiency who was detected through newborn screening and was confirmed using biochemical and functional assay. She is compound heterozygous for a likely pathogenic variant NM_000048.4(ASL):c.283C>T (p.Arg95Cys) and a likely benign variant NM_000048.4(ASL): c.1319T>C (p.Leu440Pro). Functional characterisation of the likely benign genetic variant in ASL was performed. Genomic sequencing was performed on the index patient presenting with non-specific symptoms of poor feeding and lethargy and shown to have increased serum and urine argininosuccinic acid. Functional assay using HEK293T cell model was performed. ASL enzymatic activity was reduced for Leu440Pro. This study highlights the role of functional testing of a variant that may appear benign in a patient with a phenotype consistent with ASL deficiency, and reclassifies NM_000048.4(ASL): c.1319T>C (p.Leu440Pro) variant as likely pathogenic.

Effects of a portion design plate on food group guideline adherence among hospital staff.

Food group guideline adherence is vital to prevent obesity and diabetes. Various studies have demonstrated that environmental variables influence food intake behaviour. In the present study we examined the effect of a portion design plate with food group portion guidelines demarcated by coloured lines (ETE Plate™). A two-group quasi-experimental design was used to measure proportions of carbohydrate, vegetable and protein portions and user experience in a hospital staff lounge setting in Singapore. Lunch was served on the portion design plate before 12.15 hours. For comparison, a normal plate (without markings) was used after 12.15 hours. Changes in proportions of food groups from 2 months before the introduction of the design plate were analysed in a stratified sample at baseline (859 subjects, all on normal plates) to 1, 3 and 6 months after (in all 1016 subjects on the design plate, 968 subjects on the control plate). A total of 151 participants were asked about their experiences and opinions. Between-group comparisons were performed using t tests. Among those served on the portion design plate at 6 months after its introduction, the proportion of vegetables was 4·71 % (P < 0·001) higher and that of carbohydrates 2·83 % (P < 0·001) lower relative to the baseline. No significant change was found for proteins (-1·85 %). Over 6 months, we observed different change patterns between the different food group proportions. While participants were positive about the portion design plate, they did not think it would influence their personal behaviour. A portion design plate might stimulate food group guideline adherence among hospital staff and beyond.

Assessment of sensory neuropathy in patients with diabetic foot problems.

Our aim of this study was to compare the accuracy of three different modalities for testing sensory neuropathy in diabetic patients with and without diabetic foot problems. The three devices used included the pin-prick testing using the Neurotip® (PPT), the Semmes-Weinstein 5.07/10 g monofilament testing (SWMT), and the rapid-current perception threshold (R-CPT) measurements using the Neurometer® testing. Our study population consisted of 54 patients (108 feet) with diabetic foot problems treated at the National University Hospital in Singapore by our multi-disciplinary diabetic foot care team. Our results showed no difference in sensory neuropathy detected by PPT and 5.07/10 g SWMT in both the pathological and normal foot. In the pathological foot, there was significant increase in sensory neuropathy detected by the Neurometer® device at both the big toe and ankle sites as compared to PPT and 5.07/10 g SWMT. In the normal foot, there was a significant increase in sensory neuropathy detected by the Neurometer® device at the big toe site only as compared to PPT and 5.07/10 g SWMT. Finally, the Neurometer® measurements detected a statistically higher proportion of feet with sensory neuropathy as compared to detection by the PPT or 5.07/10 g SWMT.

5-Alpha reductase inhibitors in men with an enlarged prostate: an evaluation of outcomes and therapeutic alternatives.

This article presents background information and highlights key findings from a managed care perspective related to enlarged prostate (EP) in Medicare-eligible patients. This article does not provide a comprehensive review of EP but instead attempts to increase the current understanding of EP through discussion of its prevalence in men aged > or =65 years, its associated economic burden, and some available treatment options. This supplement includes 3 additional articles, all of which present data from a naturalistic, managed care setting. The article by Fenter et al assesses differences in outcomes between elderly EP patients treated with finasteride and those treated with dutasteride in relation to the risks of acute urinary retention and prostate-related surgery. Issa et al conduct a comparative analysis of the combined use of alpha-blockers and 5-alpha reductase inhibitors to treat EP. The final article compares medical costs incurred within the first year of initiating treatment for EP patients receiving finasteride versus dutasteride. This supplement is intended to assist managed care formulary decision makers in evaluating key clinical and economic data that differentiate dutasteride and finasteride within the Medicare-aged population. Although the information presented is not designed to illustrate the superiority of one product over the other, it answers important questions in relation to treating EP in elderly men and raises substantial issues beyond medication costs.

Comparative in vivo efficacy of meropenem, imipenem, and cefepime against Pseudomonas aeruginosa expressing MexA-MexB-OprM efflux pumps.

To identify the optimal pharmacodynamic exposures of meropenem, imipenem, and cefepime, and the emergence of resistance in vivo for Pseudomonas aeruginosa overexpressing MexA-MexB-OprM efflux pumps, we used the murine thigh model. Mice were challenged with P. aeruginosa isolates: PAO1 (K767 wild type), K767+ (MexA-MexB-OprM efflux mutant), and DeltaK767 (knockout strain). Efficacy (Delta log colony-forming unit [CFU]) was determined at various exposures of %T > MIC at both standard (10(5) CFU/thigh) and high (10(7) CFU/thigh) inoculums. At 10(5) CFU/thigh, meropenem and imipenem produced a maximal activity against PAO1 (-2.82, -1.88) and K767+ (-2.24, -2.68) at 40%T > MIC; cefepime at 70%T > MIC produced a comparable kill (-2.74 and -2.19, respectively). Similar magnitudes of kill were observed at the 10(7) inocula. Except for DeltaK767 with cefepime, no development of resistance emerged at various %T > MIC. All agents exhibited reduced activity against DeltaK767. DeltaK767 cefepime-resistant strains were isolated up to 100%T > MIC. The overexpression of MexA-MexB-OprM efflux pumps did not result in the loss of efficacy of the antibiotics tested regardless of the amount of bacterial inocula; however, their presence also did not lead to increased selection for resistance. The effects of efflux mechanisms on beta-lactam agents in vivo warrant further research.

Comparison of probability of target attainment calculated by Monte Carlo simulation with meropenem clinical and microbiological response for the treatment of complicated skin and skin structure infections.

Monte Carlo simulation is often used to predict the cumulative fraction of response (CFR) for antibiotics, but the relevance of these predictions to outcomes in humans has not been well studied. We compared the CFR for meropenem 500 mg every 8h against pathogens causing complicated skin and skin structure infections from a randomised, multicentre clinical trial with clinical response (CR) and microbiological response (MR). A population pharmacokinetic model was utilised to estimate pharmacokinetic parameters for 96 clinically evaluable patients with pathogen and minimum inhibitory concentration (MIC) data available. A 1000-subject Monte Carlo simulation was performed to estimate bacteriostatic (20% of time serum concentration above the MIC (T>MIC)) and bactericidal (40% T>MIC) exposures for comparison. Only the bactericidal CFR versus the CR was not statistically different (92% CR versus 91.9% CFR; 95% confidence interval of the difference, -7.7% to 4.2%), whilst bacteriostatic CFRs overestimated actual CR and MR. This study demonstrates that the use of Monte Carlo simulation to predict the CR of meropenem in complicated skin and skin structures is accurate.

Penetration, efflux and intracellular activity of tigecycline in human polymorphonuclear neutrophils (PMNs).

OBJECTIVES: To evaluate the penetration, efflux and intracellular activity of tigecycline in human polymorphonuclear neutrophils (PMNs). METHODS: PMNs were isolated from fresh whole blood and tested for viability and purity prior to use. Tigecycline drug uptake was evaluated by incubating 5 x 10(6) cells/mL at 37 degrees C up to 3 h at tigecycline concentrations of 1, 2, 5 and 10 mg/L. Drug efflux from PMNs was determined following a 2 h incubation with tigecycline at 10 mg/L. Its intracellular activity against Staphylococcus aureus was evaluated following tigecycline extracellular exposures of 1 mg/L. RESULTS: Tigecycline uptake was rapid and achieved high concentrations within PMNs with maximal penetration noted at 1 h of incubation. At 1 h, dose-dependent intracellular concentrations ranged from 15.83 +/- 11.09 mg/L to 264 +/- 54.60 mg/L at tigecycline 1 and 10 mg/L, respectively. At these exposures, intracellular drug concentrations were approximately 20 and 30 times higher at 1 h than extracellular concentrations. By 3 h, tigecycline displayed sustained high intracellular exposures. Tigecycline cell efflux followed first order kinetics with a half-life of 1.39 h. Tigecycline was bacteriostatic against intracellular S. aureus. CONCLUSIONS: Tigecycline rapidly achieved high intracellular concentrations in PMNs and exhibited static activity against S. aureus supporting its potential clinical utilization.

Pharmacokinetic profile of tigecycline in serum and skin blister fluid of healthy subjects after multiple intravenous administrations.

The pharmacokinetics of tigecycline, when given as a 100-mg loading dose followed by 50 mg every 12 h, were determined in serum and blister fluid. The peak tigecycline concentration and half-life in serum were greater than those in blister fluid. Tigecycline penetrates into blister fluid well, with a mean penetration rate of 74%.

Pharmacodynamic modeling of imipenem-cilastatin, meropenem, and piperacillin-tazobactam for empiric therapy of skin and soft tissue infections: a report from the OPTAMA Program.

BACKGROUND: The bactericidal exposures necessary for positive clinical outcomes among skin and soft tissue infections are largely dependent on interpatient pharmacokinetic variability and pathogen drug susceptibility. By simulating the probability of achieving target bactericidal exposures, the pharmacodynamics of three beta-lactam agents were compared against a range of pathogens implicated commonly in complicated skin and soft tissue infections. METHODS: Using Monte Carlo simulation, pharmacodynamic target attainment expressed as the percentage of the time interval during which the antibiotic concentration exceeded the minimal inhibitory concentration (%T > MIC) in serum and blister fluid was calculated for 5,000 simulated patients receiving imipenem-cilastatin 0.5 g q8h, meropenem 0.5 g q8h, piperacillin-tazobactam 3.375 g q6h, and piperacillin-tazobactam 4.5 g q8h. The pharmacokinetics for each antibiotic were derived from previously published healthy volunteer studies. The MICs for Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Enterobacter sp., Klebsiella sp., coagulase-negative staphylococci, Proteus sp., beta-hemolytic streptococci, and Serratia sp. were taken from the MYSTIC 2003 surveillance study and weighted by the prevalence of each pathogen among 1,404 isolates collected from skin and soft tissue infections during the 2000 SENTRY study. The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) was added into the model at increasing resistance rates. RESULTS: Imipenem-cilastatin, meropenem, and piperacillin-tazobactam 3.375 g q6h achieved greater than 90% likelihood of achieving bactericidal exposure in serum and blister fluid until the prevalence of MRSA increased beyond 10%. Piperacillin-tazobactam 4.5 g q8h achieved a lower probability of achieving bactericidal exposure than the other regimens (88.7%, p < 0.001). CONCLUSIONS: When the incidence of MRSA is low, imipenem-cilastatin, meropenem and piperacillin-tazobactam 3.375 g q6h would be optimal choices for the empiric treatment of complicated skin and soft tissue infections among the regimens studied. When MRSA is suspected, a drug that retains activity against this pathogen should be considered.

Pharmacokinetics of oritavancin in plasma and skin blister fluid following administration of a 200-milligram dose for 3 days or a single 800-milligram dose.

Oritavancin is a novel glycopeptide currently being developed for the treatment of complicated skin and skin structure infections (cSSSI), including those caused by multidrug resistant gram-positive pathogens. The disposition of oritavancin in skin structures was investigated using a cantharide-induced blister fluid model. Seventeen healthy male subjects received oritavancin, but only 16 subjects were evaluated after one subject discontinued study drug. Each subject (eight per dose group) received 200 mg of oritavancin once a day for 3 days (group A) or 800 mg as one single dose (group B). Group A plasma samples and exudates from blister fluid were collected on days 3, 4, 7, 9, and 12 and on days 3, 4, 7, and 9, respectively. Group B samples and exudates were collected on days 1, 2, 5, 7, and 10 and on days 1, 2, 5, and 7, respectively. Drug concentrations were determined using a liquid chromatography-tandem mass spectrometry assay and, subsequently, pharmacokinetic analysis was performed. Differences between treatment groups in ratios for area under the concentration-time curve for blister fluid and plasma (AUC(blister fluid)/AUC(plasma) ratios) were evaluated using a t test (alpha = 0.05). Mean maximum concentration of drug in plasma or blister fluid was approximately 8-fold and 11-fold higher in plasma than in blister fluid following the 200- or 800-mg doses of oritavancin, respectively. Mean AUC(blister fluid)/AUC(plasma) ratios at 24 h were 0.190 (standard deviation [SD], 0.052) and 0.182 (SD, 0.062) for groups A and B, respectively (P = 0.791). To place these results in a clinical context, mean drug concentrations in blister fluid exceed the oritavancin MIC at which 90% of strains are inhibited of Staphylococcus aureus (2 microg/ml) by approximately 2- to 5.5-fold at 12 h and 1.5- to 3-fold at 24 h following administration of both dosing regimens. These results support the potential use of oritavancin for the treatment of cSSSI.

Determination of the in vivo pharmacodynamic profile of cefepime against extended-spectrum-beta-lactamase-producing Escherichia coli at various inocula.

Cefepime was evaluated in vivo against two inoculum sizes of four strains of Escherichia coli that produced extended-spectrum beta-lactamases (ESBLs) in a murine neutropenic thigh infection model to characterize the pharmacodynamic activity of cefepime in the presence of ESBL-producing bacteria and to evaluate if differences in lengths of cefepime exposure are required with various inocula. Three strains possessed a single enzyme each: TEM-10, TEM-12, and TEM-26. The fourth strain possessed two TEM-derived ESBLs and a third uncharacterized enzyme. Two non-ESBL-producing E. coli strains were included for comparison. Mice received various doses of cefepime to achieve a spectrum of percentages of time the drug was above the MIC (%T>MICs) for each isolate at both inocula. No significant difference in cefepime exposure was required to achieve similar bactericidal effects for ESBL- and non-ESBL-producing isolates when the starting inoculum was 10(5) CFU of E. coli per thigh. The increased MICs observed in vitro for the ESBL-producing strains at 10(7) CFU/ml did not predict the amount of exposure required to achieve a comparable level of bactericidal activity in vivo at the corresponding starting inoculum of 10(7) CFU/thigh. Compared to the cefepime exposure in tests with the lower inoculum (10(5) CFU/thigh), less exposure was required when the starting inoculum was 10(7) CFU/thigh (%T>MIC, 6% versus 26%), such that similar doses (in milligrams per kilogram of body weight) produced similar bactericidal effects with both inocula of ESBL-producing isolates. Equivalent exposures of cefepime produced similar effects against the microorganisms regardless of the presence of ESBL production. Pharmacodynamic profiling undertaken with conventional cefepime MIC determinations predicted in vivo microbial outcomes at both inoculum sizes for the ESBL-producing isolates evaluated in this study. These data support the use of conventional MIC determinations in the pharmacodynamic assessment of cefepime.