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心脏重构是心力衰竭发生发展的主要病理基础，是影响心肌损伤患者预后的重要因素。心脏重构的调节机制众多，近年来发现多与心脏细胞衰老有关。该文从氧化应激、炎症反应、能量代谢、自噬、线粒体功能障碍等方面综述了心脏细胞衰老对心脏重构的作用及机制，以期为心力衰竭的防治提供新思路。.

Structural Equation Modeling was carried out in this study to investigate whether macroeconomic variables under Business Activity, Consumer Activity and Monetary Policy influence the performance of Philippine stock market indices. A proposed economic-based model was used to determine which set of variables has direct and indirect effect on the stock market for the period of 2006 to 2018. Results showed that Consumer Activity and Monetary Policy were the main drivers that influence the performance of all sectors in the Philippine Stock Market. Business Activity is also a significant factor but only for the Financial, Industrial, and Property Sectors. On the other side, Monetary Policy showed a significant direct effect on Financial, Holding Firms, Services, and Mining-Oil Sectors but no direct effect on the Industrial and Property Sector. The results conclude that stock performance is significantly determined by some fundamental macroeconomic variables such as money supply, interest rate, remittances, consumer spending, and industrial production index. These findings suggest that investors should pay close attention to consumer activity since an increase in stock market performance is mainly determined by this factor.

In response to the Philippines education system's development plan in strengthening the research culture of the different higher education institutions, this study was conducted to assess the research efficiency of 18 research universities in the country. Standard Data Envelopment Analysis (DEA) models, have been used in previous researches to measure the relative efficiency of research performance of universities with quantity-oriented indicators inputs and outputs. This study proposed the use of a network DEA (NDEA) model considering quality indicators in assessing the efficiency of the research performance of universities. NDEA allows the measurement of efficiency per stage of a process. The main finding is that the standard DEA tends to exaggerate the research efficiency compared to that of NDEA. The use of quality-oriented publication indicator also revealed that the use of quantity-oriented indicators alone exaggerates the performance of the universities as it is mainly based on the number of researches produced, not considering the impact or quality of each research. Some of the top-performing universities ranked lower with the use of quantity-oriented indicators.

Objective This study aimed to assess IL-24 levels and their association with clinical manifestations in patients with systemic lupus erythematosus (SLE). Methods There were 75 patients with SLE and 58 healthy controls recruited in this study. Serum levels of IL-24 were measured by enzyme-linked immunosorbent assays, and mRNA levels of IL-24 were tested by quantitative real-time polymerase chain reaction . The area under the curve of the receiver operating characteristic (ROC) curve was used for diagnostic ability of the inflammatory cytokine. Results Serum IL-24 levels were significantly higher in SLE patients than that in healthy controls. SLE patients with nephritis had higher IL-24 levels than those without nephritis. Active SLE patients showed higher expression of IL-24 as compared to less active disease patients. The mRNA levels of IL-24 were much higher in SLE patients. Correlation analysis showed significant correlation between serum IL-24 levels and SLE disease activity index. In addition, ROC analysis may suggest good ability of serum IL-24 in differentiating SLE. Conclusion The inflammatory cytokine correlated with SLE disease activity, and may be involved in this disease pathogenesis.

The location of emergency response units (ERUs) is crucial to their operational success. This paper proposes the use of both qualitative and quantitative techniques to consider possible trade-offs between the two in determining optimal locations through an integrated Analytical Hierarchical Process and Mixed Integer Linear Programming approach with consideration of multiple routes with changing velocities and multiple ERU locations in a district. Neither objective is optimized at the other's expense through the maximization of the least efficiency value generated. A case application showed the model's validity by prioritizing the ERU locations that had the highest preference ratings. Scenario analysis revealed that varying ERU capacity does not change the optimal solution but affects the percent of population served, while changing the number of ERUs required per district and the preference ratings of the potential locations does, as the model adjusts to meet the new requirements and considers changed priorities.

The postantibiotic effect (PAE) exhibited by Pseudomonas aeruginosa after exposure to single doses of tobramycin was investigated under various pharmacokinetic conditions using an established in-vitro kinetic model. At equal doses of the antibiotic stimulating an intravenous bolus condition, the effects of varying elimination half-life on PAE were assessed. The PAE was longer when the rate of antibiotic elimination was lower. However, after correcting for the different degrees of antibiotic exposure using the area under the concentration-time curve above the MIC (AUC > MIC), a coherent PAE versus antibiotic exposure profile was obtained. The effects of increasing tobramycin dose and exposure time on PAE were investigated in another series of experiments; PAE was assessed during antibiotic exposure when the exponentially decreasing concentrations were above the MIC, at the MIC and below the MIC. A longer PAE was achieved at higher doses and changes were dependent on both the degree and time of exposure. For all the doses tested, the PAE was longest when the decreasing antibiotic concentrations were near or at the MIC. Shorter PAEs were detected at sub-MIC concentrations and diminished rapidly as antibiotic concentrations continued to decline. Such a decrease in PAE was counteracted by the longer exposure time, so that the total time for which the organism was under the influence of the antimicrobial effects, i.e. the sum of exposure time and PAE, remained steady at sub-MIC concentrations. Under these simulated pharmacokinetic conditions, present data support a substantial impact of pharmacokinetics on PAE. Along with MIC, AUC > MIC can be a useful pharmacokinetic parameter for PAE assessments. Should PAE be a relevant factor in antibiotic chemotherapy, both time and degree of antibiotic exposure would have to be considered.

The effect of concomitant dosing with the antiretroviral agent zidovudine (ZDV) on the pharmacokinetics of rifabutin (RBT) was investigated under steady-state conditions. Sixteen human immunodeficiency virus-positive patients with AIDS-related complex who had been maintained on stable ZDV therapy for > or = 6 weeks were administered RBT concomitantly for 12 days. Eight patients received daily doses of 300 or 450 mg of RBT. Administration of ZDV was discontinued on day 13, and RBT was given alone for 3 additional days. Four patients receiving 450 mg of RBT discontinued treatment. Under steady-state ZDV and RBT dosing, safety and kinetics assessments were performed on day 13 (ZDV plus RBT) and day 16 (RBT alone). Kinetics on days 13 and 16 demonstrated that RBT (300 or 450 mg) was readily absorbed, with the time at which the plasma concentration was maximal (Tmax) ranging between 2.6 and 2.9 h. At these two doses, the mean steady-state maximal plasma concentrations (Cmax) were 250 and 430 ng/ml on day 13 and 245 and 458 ng/ml on day 16, respectively. RBT kinetics at the two doses were proportional and similar on the basis of estimates of the ratios of the areas under the concentration-time curves over the dosing interval from 0 to 24 h (AUC0-24) (450 mg/300 mg), which were 1.5 and 1.4 for days 13 and 16, respectively. No significant differences were apparent in the mean oral clearance (CLs/F) estimates (range, 1.60 to 1.77 liters/h/kg), which were dose independent and similar for the 2 assessment days, as was the urinary recovery of RBT and its 25-deacetyl metabolite. Low urinary recovery of 25-deacetyl RBT and an AUC metabolite/parent ratio of 0.1 suggest that there is minimal metabolism of RBT via the deacetylation pathway. For RBT, pooled mean (95% confidence interval) ratio (day 13/day 16) estimates for Cmax, Tmax, AUC0-24, and CLs/F were 1.07 (range, 0.77 to 1.38), 1.08 (0.89 to 1.27), 0.97 (0.82 to 1.13), and 1.09 (0.92 to 1.26), respectively. In addition, no significant changes in any of the major safety parameters were detected throughout the study. Therefore, it is concluded that coadministration of ZDV and RBT does not affect the pharmacokinetics and/or safety of RBT in human immunodeficiency virus-positive patients.

OBJECTIVE: To determine the reliability of the Cybex 6000 isokinetic dynamometer in measuring the knee muscle performance concentrically and eccentrically. METHODS: 18 male and 12 female subjects with no previous knee injuries, who had not previously undergone any isokinetic testing, were studied. The flexor and extensor muscles groups of both knees were tested at 60 degrees s-1 and 120 degrees s-1 with the continuous concentric-eccentric cycle testing protocol. Variables studied included peak torque, total work, and average power. The interclass correlation coefficient (ICC 2,1) was used to determine the reliability with P < 0.05. RESULTS: Peak torque showed significantly greater ICC than the total work and average power, with test-retest reliability ranging from 0.82 to 0.91 for peak torque, from 0.76 to 0.89 for total work, and 0.71 to 0.88 for average power. Average variability for the three variables studied ranged from 9% to 14%. The ICCs for the three variables studied were significantly greater at 120 degrees s-1. The knee extensor muscle group showed greater test-retest reliability, and the results of isokinetic testing in the concentric contraction mode were more reproducible. CONCLUSIONS: The Cybex 6000 isokinetic dynamometer shows high reliability in measuring isokinetic concentric and eccentric variables. Some fluctuation should be allowed when evaluating variations of muscle performance between tests.

The checkerboard technique leading to the fractional inhibitory concentration indexes and the killing curve method are currently the most widely used methods to study antibiotic combinations. For both methods, experimental conditions and interpretation criteria are somewhat arbitrary. The relevance of the fractional inhibitory concentration index computation, in the classic case of additivity [P = d1/(D1)p + d2/(D2)p, where d1 and d2 are the doses of drugs 1 and 2 in combination to produce an effect at a percent level (P) and (D1)p and (D2)p are the doses required for the two respective drugs alone to produce the same effect] relies on the assumption of a linear relationship between the MIC and the concentration of the test antibiotics. In addition, there is no consensus as to the definition of synergy in killing curve interpretation. The fractional maximal effect (FME) method is a new approach which was developed to handle the nonlinear pharmacodynamics exhibited by antibiotics and other drugs. This method relies on the mathematical linearization of the nonlinear concentration-effect scales and eventual construction of an isobologram-type data plot. The FME method was applied to study interactions between several antibiotic combinations: amoxicillin and tetracycline, ciprofloxacin and erythromycin, and ticarcillin and tobramycin. These combinations were selected because the pharmacologic basis for their interactions has been previously described. The FME method correctly identified antagonism for the first two combinations and synergism for the last combination. Conclusions were reproducible across the range of concentrations studied. Besides providing information on the nature of the interaction, the method can rapidly explore the effect of changing concentration ratios of two antimicrobial agents on the degrees of interaction. The FME method may be applied to interactions between drugs or agents with either a linear or nonlinear endpoint measurement. Methods frequently used for drug combination testing are also discussed in the paper.

To determine the frequency of hepatitis B surface antigen (HBsAg) mutations in the alpha determinant region among children who developed chronic hepatitis B virus (HBV) infection after receiving only active postexposure immunoprophylaxis.HBsAg mutations were determined by PCR-directed nucleotide sequencing and sequence-specific solid-phase PCR analysis(SS-SPPCR) for 97 Chinese carrier cases after hepatitis B vaccination, for 88 children born aged women controls, and for 95 population based children controls.Prevalence of amino acid substitutions as detected by direct sequencing among carrier cases, women controls, and children controls were 30.9%, 10.2%, and 5.3%, respectively. The most frequent amino acid substitutions observed were at residues 145, 126, and 133. However, there was no difference in the prevalence of 145 and 126 amino acid mutants as detected by a sensitive SS-SPPCR method between carrier cases and controls. The prevalence of 145 Arg and 145 Ala mutants that were detected by SS-SPPCR was 39.2%, 33.0% and 32.6% among carrier cases, women controls, and children controls, respectively. The total odds ratio was 5.41 for mutants detected by direct sequencing. Odds ratio were 34.55 and 33.39 among adw2 subtype and genotype B subjects for mutants detected by direct sequencing, respectively.The results show that hepatitis B virus mutants in the determinant are fairly consistent observed but without immune selective pressures; HBV variant strains may pre-existent as minor quasispecies. The prevalence of mutants is related to HBV subtypes and genotypes.

Three cases of decompression illness are reported. Two patients presented with joint pain and skin signs, while one patient presented with joint pain and neurological signs and symptoms. The patients received emergency recompression therapy in a Hong Kong clinic, using a monoplace hyperbaric chamber. All three patients were treated successfully and no residual signs or symptoms were evident on review at 90 days' post-treatment. Issues concerning the use of monoplace and multiplace hyperbaric chambers are also discussed, along with additional clinical applications of the monoplace hyperbaric chamber.

Ganoderma lucidum was studied for its antioxidative activity by bioassay guided isolation in conjunction with in vitro tests. The powdered crude drug was treated with boiling water and the aqueous extract (Ex1) was further separated to obtain terpene and polysaccharide fractions. The two fractions and Ex1 were screened for their antioxidative effect against pyrogallol induced erythrocyte membrane oxidation and Fe (II)-ascorbic acid induced lipid peroxidation. All tested samples showed antioxidative activities in a dose dependent manner and the terpene fraction was found to possess the highest effect compared with the others. Chemical isolation of the terpene fraction resulted in the detection of ganoderic acids A, B, C and D, lucidenic acid B and ganodermanontriol as major ingredients.

To determine whether recipients of clinical laboratory science (CLS) advanced degrees (MS) perceive greater career enhancement value related to earning an advanced degree than is perceived by their baccalaureate level (BS) colleagues.Two questionnaires were used-one for certified or licensed CLS professionals who had earned MS CLS degrees; the other for matched BS CLS colleagues.Five academic programs that conduct both National Accrediting Agency for Clinical Laboratory Sciences accredited CLS education and CLS MS degree programs participated.The number of survey respondents was 220 (117-MS; 103-BS level controls). The groups were matched for gender, residence region, and years of experience.The primary outcome measurements were the perceived benefits of having a CLS MS degree, the reasons for and against obtaining a CLS MS degree, and the overall evaluation of CLS degree programs at both levels.The highest perceived benefit of having a CLS MS degree was the same in both groups, "enhanced self esteem and confidence". The highest priority motivation of MS degree recipients for obtaining a CLS advanced degree was "personal satisfaction". The highest priority reason of the BS group for not obtaining a CLS advanced degree was "family obligation". In both levels of degree programs the subject most commonly cited as needing modification was laboratory management.The results indicate that CLS professionals who have CLS MS degrees perceive a greater career enhancement value of advanced CLS degrees than their BS level colleagues.

Determine whether recipients of clinical laboratory science (CLS) advanced degrees (MS) experience greater career achievements than their baccalaureate level (BS) colleagues.Two similar questionnaires were used-one for certified or licensed CLS professionals who had earned advanced CLS degrees (MS); the other for matched BS CLS colleagues.Five academic programs that conduct both National Accrediting Agency for Clinical Laboratory Sciences accredited CLS education and CLS MS degree programs participated.The number of survey respondents was 220, 117 with advanced CLS degrees and 103 BS level controls. There were 99 matched pairs, i.e., 198 individuals were matched for gender, residence region, and years of experience.Careers of BS vs. MS respondents were statistically compared, e.g., fractions with managerial level jobs, relative earnings increases per year, numbers of publications and reports, and other professional contributions.Compared to their BS degree controls, MS degree respondents had more managerial level jobs (62% MS; 36% BS), a higher frequency of job change (once per 4.3 years MS; once per 5.9 years BS), and a higher increase per year of earnings (9.1% MS; 8.1% BS). A greater percentage of the MS degree graduates (77%) than the BS level controls (33%) had authored external publications; the responses related to authorship of institutional reports and procedures were less different-84% MS and 64% BS. Professional contributions to their institutions or profession were cited slightly more frequently by the MS graduates (65%) than by the BS level controls (55%).Compared to their matched BS level CLS colleagues, CLS MS degree recipients had greater job mobility, greater management authority, higher salary, and more numerous professional contributions.

The endpoints associated with conventional susceptibility testing, e.g., the minimum inhibitory concentration or minimum bactericidal concentration (MIC or MBC), are discrete in nature. These endpoint measurements do not provide any information, regarding the pharmacodynamic changes exhibited by the bacteria in reaction to the antibiotic activity during the incubation period. Another limitation of these susceptibility tests is the maintenance of constant antibiotic concentrations; this condition contrasts sharply to the continuously changing concentrations observed in vivo. To tackle these problems, various in vitro pharmacokinetic/pharmacodynamic models have been developed. Taking into consideration various pharmacokinetic determinants, such models allow more comprehensive study of the pharmacodynamic effects demonstrated by antibiotics. In this paper, the implications and usefulness of these in vitro models to the characterization of antimicrobial activity are discussed. Limitations associated with their use are also addressed.

The uptake kinetics of cisplatin analogs of 1,2-cyclohexanediamine(dach) isomers with various leaving groups, by human erythrocytes in plasma isotonic buffer, were studied. The experimental results showed that the uptake rate constants (k values) decrease with the change of leaving group in the sequence: chloride (Cl)squaric acid (SA)oxalate (OX)demethylcantharic acid (DA), with the same dach isomer as carrier group. It is noteworthy that for the platinum (II) complexes with the same leaving group, the k values always reduce as: 1R, 2R-dach1R, 2S-dach1S, 2S-dach. This result reflects the chirality selectivity. No differences in reactivity to protein thiols and effects on membrane permeability were found for the R,R-, R,S-, S,S-isomeric complexes. It is proposed that the chirality selectivity in uptake is due to the recognition of the chirality of the platinum complexes by the erythrocyte membrane. The interactions between the chiral platinum complexes and the head groups of the membrane phospholipid molecules are probably involved.

Forty-eight patients with transitional cell carcinima (TCC) of the bladder were investigated. Routine paraffin-embedded sections were stained with proliferating cell nuclear antigen (PCNA) monoclonal antibody in order to determine the growth fraction of the bladder tumors and to correlate this with tumor grade, stage, development of recurrence and survival rate during follow-up. PCNA positive staining was detected in 95.8% (46/48) of the tumors. The mean labeling index (LI) of superficial tumors (Ta-1, n = 28) was 12.58 +/- 12.33%, and 34.55 +/- 21.89% in invasive tumors (T2-4, n = 18). A similar correlation was found in association with tumor grade. The patients were followed up for a mean of 4.9 years (range 1-14 years). The mean PCNA LI in nonrecurrent (n = 21) and simple recurrent (n = 7) superficial tumors was 11.29 +/- 11.79% and 16.44 +/- 14.05%, respectively, the difference not being statistically significant. To access survival, tumors with a PCNA LI above and below the median level (21%) were compared. Those patients (n = 19) with an index of21% (the mean of all the PCNA values) had a worse prognosis than those (n = 27) with an index of21%, a difference which is statistically significant. These results suggest that PCNA LI in bladder cancer may prove to be an objective and quantitative assay of biological aggressiveness and provide significant prognostic information, although it does not help the selection of patients at risk of simple recurrence in superficial tumors.

OBJECTIVE: To test the hypothesis that increasing the hamstrings and quadriceps (H:Q) isokinetic strength ratio will, in the short term, improve the functional ability of an anterior cruciate ligament (ACL) deficient knee. METHODS: The isokinetic muscular characteristics at a speed of 60 degrees s-1 and 180 degrees s-1 of 46 recreational athletes with an arthroscopically confirmed ACL tear were determined using the Cybex II+ isokinetic dynamometer. The variables tested included peak torque, endurance ratio, total work output, and explosive power. Functional ability was scored with the Cincinnati rating system, measuring the severity of pain and swelling, the degree of giving way, and the overall ability to walk, run, ascent and descent stairs, jump and twist. RESULTS: Among all muscular characteristics, the H:Q ratio at 180 degrees s-1 at 30 degrees of knee flexion was shown to have the highest correlation to the functional score (r = 0.6249, P < 0.001). All variables involving hamstring strength were shown to be significantly correlated to the functional ability score (P < 0.01), while none of the variables involving quadriceps strength showed significant correlation with the functional ability of the injured knee. CONCLUSIONS: The H:Q ratio is strongly correlated to the functional ability of ACL deficient knees in Chinese recreational athletes. It could be used as an additional measure to guide in the decision making process in the management of ACL deficient knees.

The autoinduction characteristic of rifabutin (RIF) following multiple oral dosing was investigated via pharmacokinetic modeling. A two-compartment model with first-order absorption was fit to plasma RIF data obtained from a study conducted in healthy normal volunteers following both a single and multiple oral doses. Parameter estimates showed an elimination rate constant (k10) of about 0.12-0.14 h-1 which was independent of the single or multiple-dosing condition. The lower-than-expected drug accumulation following multiple dosing seems to suggest that prolonged dosing perturbs the linear kinetic system. However, this analysis has shown no significant changes (p0.05) in the rate constants describing RIF absorption, tissue distribution/redistribution, and elimination. The mean rate of drug redistribution from the tissue compartment (k21; 0.04-0.06 h-1) was twofold to threefold lower than k10, and, with a large steady-state distribution volume (Vss/F after a single dose, 1630 L), RIF elimination appears to be dependent on drug redistribution. This hypothesis was further supported by a significant correlation (p0.01) between RIF tissue redistribution (k21) and terminal disposition phase rate (lambda z) constants. The redistribution dependent elimination of RIF also helps explain the stability of the terminal half-life under both single and multiple-dosing paradigms. Urinary excretion of RIF and its 25-O-deacetyl metabolite totalled less than 7% of the oral dose following single dosing, and decreased to about 4% after multiple dosing. For individual patients, the decrease in urinary recovery of the 25-O-deacetyl metabolite was directly proportional to the decrease in urinary RIF recovery. In addition, both estimates of the model intercepts (A and B) were lower following multiple dosing. Further analyses revealed a linear relationship between A and B intercepts, and also between the urinary RIF recovery and the B intercept. These relationships, in conjunction with the lack of significant increase in the rate of elimination, indicate that induction of presystemic extrahepatic metabolism and/or decrease in the extent of oral absorption may be the primary causes for the lower-than-expected systemic RIF plasma levels after multiple oral dosing.

It has been suggested that didanosine (ddI) may undergo hepatic metabolism. Rifabutin is an inducer of drug metabolism. Fifteen human immunodeficiency virus-infected patients whose conditions were stabilized on twice-daily doses of ddI participated in a Phase I, open-label, pharmacokinetic and safety drug interaction study between rifabutin and ddI. Twelve patients completed the study. All patients received their regular ddI dose (167-375 mg) on day 1. On days 2-13 they received once-daily rifabutin (600 mg, three patients; 300 mg, nine patients) with their regular twice-daily ddI regimen. On days 14-16 they received rifabutin alone. Serial blood and urine samples were collected for 12 h on day 1 and for 24 h on days 13 and 16, and safety evaluations were made throughout the study. Average day 1/day 13 ddI pharmacokinetic ratios and 95% confidence interval values for Cmax, AUC0-infinity, Cls/F, and t 1/2, lambda z were 1.17 (0.96-1.38), 1.13 (0.99-1.27), 0.91 (0.81-1.01), and 0.97 (0.79-1.15), respectively (p0.05 for all comparisons; paired t test). A 20% difference in AUC0-infinity could be detected with 90% power. Also, there were no significant changes in laboratory values or electrocardiograms, or in rifabutin pharmacokinetic parameters when the two agents were coadministered. Based on the safety and pharmacokinetic assessments, rifabutin did not appear to interact with ddI.

There is a scarcity of descriptive data on the physiological characteristics of elite Asian junior soccer players. The purpose of this study was to evaluate the cardiorespiratory fitness and isokinetic muscle strength of elite junior soccer players in Hong Kong. It was conducted in conjunction with the selection of the Hong Kong team to the 1989 Gothia Cup held in Sweden. Twenty-one top junior soccer players were selected as subjects for the study. The following means (+/- SD) were observed: age 17.3 +/- 1.1 years; height 172.5 +/- 6.2 cm; weight 62.8 +/- 7.0 kg; body fat 5.2 +/- 1.8%; forced vital capacity (FVC) 4.6 +/- 0.6 L; maximum oxygen uptake (VO2max) 58.6 +/- 2.9 ml.kg-1.min-1; anaerobic threshold (AT) 76.7 +/- 10.2% of VO2max; peak isokinetic dominant knee extensor and flexor strengths 3.28 +/- 0.37 Nm.kg-1 and 1.84 +/- 0.24 Nm.kg-1; hamstring to quadriceps peak torque ratio (H/Q) 56 +/- 0.6% measured at 60 degrees s-1. Hong Kong players appeared to have comparable aerobic power, light body weight, poor flexibility and above average isokinetic muscle strength compared to other international junior soccer players. Training programs to improve the contralateral knee muscle imbalance and to increase the fast speed movement capability of the non-dominant knee flexors are recommended.

A turbidimetric assay was developed and validated against Escherichia coli for the quantitation of viable bacterial densities. The Abbott MS-2 research system was employed for continuous 5-min measurements of optical density. A linear standard curve was obtained by regressing the initial bacterial density (log CFU per milliliter) against the time required for bacterial growth causing a 5% decrease in optical transmittance. Slope and intercept values obtained from eight standard curves showed excellent assay reproducibility. Results obtained by the turbidimetric assay compared favorably to those obtained by the conventional pour plate assay. Prior to the application of the new assay, possible interferences of postantibiotic effect induced by the test antibiotics were excluded. The turbidimetric assay, which is presumably more efficient and less expensive, was implemented for the time-kill studies of three different beta-lactams against E. coli.