Impact of the physical properties of contact lens materials on the discomfort: role of the coefficient of friction

Contact Lens Discomfort (CLD) is the main cause in contact lens (CLs) discontinuation, referred in literature as drop-out phenomenon. Despite such evidence was reported in several clinical studies, a relationship between physico-chemical properties of CLs and CLD is not still totally understood. In this regard, the friction of CLs surfaces seems to be related to discomfort feeling events, probably due to an alteration of the lubricate function of the tear film after the CL placement inside the ocular environment. In the last years, many studies have been finalized to the friction measurements of CLs surface, finding conflicting data due to a lack in standardized protocol. The aim of this review is primarily to show evident relationships between CLs surface properties (i.e. wettability, tear evaporation, tear film quality, etc.) and the coefficient of friction (CoF), resulting therefore the most relevant physical quantity in the CLs characterization. In addition, we reported the most recent studies in CLs tribology, which highlight that the introduction of a standard protocol in CoF measurements is necessary to obtain reproducible results, considering the aim to evaluate in a more precise way the relationship between this material surface property and comfort in CLs users.

Double-blind, placebo-controlled pharmacodynamic studies with a nutraceutical and a pharmaceutical dose of ademetionine (SAMe) in elderly subjects, utilizing EEG mapping and psychometry

In a double-blind, placebo-controlled crossover study, the effects of S-adenosyl-l-methionine (SAMe) on brain function measures of 12 normal elderly volunteers (6 m/6 f, aged 57-73 years, mean: 61 years) were investigated by means of EEG mapping and psychometry. In random order, the subjects were orally administered a pharmaceutical dose of 1600 mg SAMe, a nutraceutical dose of 400 mg SAMe and placebo, each over a period of 15 days, with wash-out periods of 2 weeks in between. EEG recordings, psychometric tests and evaluations of tolerability and side effects were carried out 0, 1, 3 and 6 h after drug administration on days 1 and 15. Multivariate analysis based on MANOVA/Hotelling T2 tests of quantitative EEG data demonstrated significant central effects of SAMe as compared with placebo after acute, subacute and superimposed drug administration of both the nutraceutical and the pharmaceutical dose. EEG changes induced by SAMe were characterized by an increase in total power, a decrease in absolute and relative power in the delta/theta and slow alpha frequencies, an increase in absolute and relative power in the alpha-2 and beta frequencies as well as an acceleration of the alpha centroid and the centroid of the total power spectrum. The delta/theta and the beta centroid showed variable changes over time. The dominant alpha frequency was accelerated, the absolute and relative power in the dominant alpha frequency attenuated after SAMe as compared with placebo. These acute and subacute pharmaco-EEG findings in elderly subjects are typical of activating antidepressants. Time-efficacy calculations showed that acute oral administration of SAMe in both the nutraceutical and the pharmaceutical dose induced the pharmacodynamic peak effect in the first hour with a subsequent decline. The 3rd and 6th hours still showed a significant encephalotropic effect after the 1600 mg dose. The maximum EEG effect was noted after 2 weeks of oral administration of both 1600 mg/die and 400 mg/die. The superimposed dose induced significant encephalotropic effects in the 3rd hour after 400 mg and in the 3rd and 6th hours after 1600 mg as compared with pre-treatment. Dose-efficacy calculations showed that the pharmaceutical dose of 1600 mg had a more pronounced effect on the CNS than the nutraceutical dose of 400 mg, with both doses being superior to placebo. Psychometric tests concerning noopsychic and thymopsychic measures as well as critical flicker fusion frequency generally demonstrated a lack of differences between SAMe and placebo, which reflects a good tolerability of the drug in elderly subjects. This was corroborated by the findings on side effects, pulse and blood pressure.

Ci-IPF1, the pancreatic homeodomain transcription factor, is expressed in neural cells of Ciona intestinalis larva

We describe the cloning and the expression pattern of insulin promoter factor 1 in the ascidian Ciona intestinalis (Ci-IPF1). Northern blot analysis showed that transcripts appeared at the late tailbud stage and increased at the larval stage. We have raised a specific antibody against the Ci-IPF1-GST fusion protein to determine the spatial expression of this gene. The protein is immunodetected at the larval stage in the sensory vesicle, in the visceral ganglion and in the mesenchymal cells. Our results support the hypothesis that IPF1/IDX1 might have extrapancreatic functions during animal development, particularly in neural cells.

A population pharmacokinetic analysis of the penetration of the prostate by levofloxacin

Prostatitis has remained a pathological entity that is difficult to treat. Part of the difficulty revolves about the putative offending pathogens. For acute prostatitis, members of the Enterobacteriaceae, particularly Escherichia coli, play a central role, while intracellular pathogens such as Chlamydia are more frequently seen in chronic prostatitis. Consequently, a drug needs to be able to penetrate to this specialized site in both the acute and chronic infection forms of the disease and also have potent activity against the most common causative pathogens, both intracellular and extracellular. Levofloxacin has such an activity profile. We wished to document its ability to penetrate to the site of infection. Patients undergoing prostatectomies were administered 500 mg of levofloxacin orally every 24 h for 2 days prior to surgery, and then on the day of surgery, 500 mg was administered as an hour-long, constant-rate intravenous (i.v.) infusion. A set of blood samples was obtained as guided by stochastic optimal design theory. Prostate biopsy times were determined by randomizing subjects into one of four groups, based on the interval after the i.v. dose. All plasma and prostate drug concentrations were comodeled by a population modeling program, BigNPEM, implemented on the Cray T3E Supercomputer housed at the Supercomputer Center at the University of California at San Diego. Penetration was determined as the ratio of the area under the concentration-time curve (AUC) of levofloxacin in the prostate to the plasma levofloxacin AUC. When calculated from the mean population parameters, this penetration ratio was 2.96. We also performed a 1,000-subject Monte Carlo simulation from the mean parameter vector and covariance matrix. The mean penetration ratio here was 4.14 with a 95% confidence interval of 0.20 to 19.6. Over 70% of the population had a penetration ratio in excess of 1.0. Levofloxacin adequately penetrates a noninflamed prostate and should be evaluated for the therapy of prostatitis.

Isolation and characterization of the cDNA for a Ciona intestinalis RNA binding protein: spatial and temporal expression during development

A cDNA encoding an RNA binding protein has been isolated from a cDNA library prepared from larvae of the ascidian Ciona intestinalis. The putative protein of 162 amino acids contained in the N-terminal region one copy of the consensus sequence RNA binding domain and in the C-terminal region a glycine-rich domain. The in vitro translated protein bound various RNA homopolymers, preferentially polyU, polyA, and polyG, and the binding was affected by increasing ionic strength. Northern blot analysis revealed a single transcript of about 0.7 kb in length that was present during embryonic development with two major peaks of accumulation at gastrula and larval stages. Whole-mount in situ hybridization experiments on embryos at different stages of development showed gene expression mainly in mesenchymal cells and in neural tissue.

The role of antithrombin III in the perioperative management of the patient with unstable angina

BACKGROUND

To evaluate the effectiveness of intraoperative administration of antithrombin III (AT III) to improve anticoagulation and preserve the hemostatic mechanisms during cardiopulmonary bypass (CPB) in patients with unstable angina under heparin treatment.

METHODS

We divided 22 patients, scheduled for coronary artery bypass grafting, into two groups. Group A (11 patients) received 3000 International Units (IU) of AT III concentrates plus heparin before aortic cannulation. Group B (11 patients) received only heparin. Blood drainage, allogeneic blood transfusions, and intraoperative activated coagulation time were recorded. Also, AT III, thrombin-antithrombin complex (TAT), fragment 1.2 (F 1.2), and D-dimers were measured during the operation and the first postoperative day.

RESULTS

Group A patients had fewer transfusions and had less chest-tube drainage. In group A, AT III levels increased after AT III concentrates administration and were always higher than in group B. In group B, F 1.2 and TAT increased significantly more after CPB and at the end of operation. Differences in D-dimers between the groups were not significant.

CONCLUSIONS

Intraoperative administration of AT III concentrates allowed adequate anticoagulation during CPB and attenuated the coagulative cascade activation and the consequent consumptive coagulopathy.

Levofloxacin population pharmacokinetics and creation of a demographic model for prediction of individual drug clearance in patients with serious community-acquired infection

Population pharmacokinetic modeling is a useful approach to obtaining estimates of both population and individual pharmacokinetic parameter values. The potential for relating pharmacokinetic parameters to pharmacodynamic outcome variables, such as efficacy and toxicity, exists. A logistic regression relationship between the probability of a successful clinical and microbiological outcome and the peak concentration-to-MIC ratio (and also the area under the plasma concentration-time curve [AUC]/MIC ratio) has previously been developed for levofloxacin; however, levofloxacin assays for determination of the concentration in plasma are not readily available. We attempted to derive and validate demographic variable models to allow prediction of the peak concentration in plasma and clearance (CL) from plasma for levofloxacin. Two hundred seventy-two patients received levofloxacin intravenously for the treatment of community-acquired infection of the respiratory tract, skin or soft tissue, or urinary tract, and concentrations in plasma, guided by optimal sampling theory, were obtained. Patient data were analyzed by the Non-Parametric Expectation Maximization approach. Maximum a posteriori probability Bayesian estimation was used to generate individual parameter values, including CL. Peak concentrations were simulated from these estimates. The first 172 patients were used to produce demographic models for the prediction of CL and the peak concentration. The remaining 100 patients served as the validation group for the model. A median bias and median precision were calculated. A two-compartment model was used for the population pharmacokinetic analysis. The mean CL and the mean volume of distribution of the central compartment (V1) were 9.27 liters/h and 0.836 liter/kg, respectively. The mean values for the intercompartmental rate constants, the rate constant from the central compartment to the peripheral compartment (Kcp) and the rate constant from the peripheral compartment to the central compartment (Kpc), were 0.487 and 0.647 h(-1), respectively. The mean peak concentration and the mean AUC values normalized to a dosage of 500 mg every 24 h were 8.67 microg/ml and 72.53 microg x h/ml, respectively. The variables included in the final model for the prediction of CL were creatinine clearance (CLCR), race, and age. The median bias and median precision were 0.5 and 18.3%, respectively. Peak concentrations were predicted by using the demographic model-predicted parameters of CL, V1, Kcp and Kpc, in the simulation. The median bias and the median precision were 3.3 and 21.8%, respectively. A population model of the disposition of levofloxacin has been developed. Population demographic models for the prediction of peak concentration and CL from plasma have also been successfully developed. However, the performance of the model for the prediction of peak concentration was likely insufficient to be of adequate clinical utility. The model for the prediction of CL was relatively robust, with acceptable bias and precision, and explained a reasonable amount of the variance in the CL of levofloxacin from plasma in the population (r2 = 0.396). Estimated CLCR, age, and race were the final model covariates, with CLCR explaining most of the population variance in the CL of levofloxacin from plasma. This model can potentially optimize the benefit derived from the pharmacodynamic relationships previously developed for levofloxacin.

Pharmacodynamics of levofloxacin: a new paradigm for early clinical trials

CONTEXT

One purpose of early clinical trials is to establish the appropriate dose of an antibiotic for phase 3 trials. Development of a relationship between the ratio of drug exposure to organism minimum inhibitory concentration (MIC) and therapeutic response early in the development process would allow an optimal choice of dose to maximize response.

OBJECTIVE

To prospectively quantitate the relationship between plasma levels of levofloxacin and successful clinical and/or microbiological outcomes and occurrence of adverse events in infected patients.

DESIGN

Multicenter open-label trial.

SETTING

Twenty-two enrolling university-affiliated medical centers.

PATIENTS

A total of 313 patients with clinical signs and symptoms of bacterial infections of the respiratory tract, skin, or urinary tract.

MAIN OUTCOME MEASURES

Clinical response and microbiological eradication of pathogenic organisms.

RESULTS

Of 313 patients, 272 had plasma concentration-time data obtained. Of these, 134 patients had a pathogen recovered from the primary infection site and had an MIC of the pathogen to levofloxacin determined. These patients constituted the primary analysis group for clinical outcome. Groups of 116 and 272 patients, respectively, were analyzed for microbiological outcome and incidence of adverse events. In a logistic regression analysis, the clinical outcome was predicted by the ratio of peak plasma concentration to MIC (Peak/MIC) and site of infection (P<.001). Microbiological eradication was predicted by the Peak/MIC ratio (P<.001). Both clinical and microbiological outcomes were most likely to be favorable if the Peak/MIC ratio was at least 12.2.

CONCLUSIONS

Levofloxacin generated clinical and microbiological response rates of 95% and 96%, respectively. These response rates included fluoroquinolone "problem pathogens," such as Streptococcus pneumoniae and Staphylococcus aureus. Exposure to levofloxacin was significantly associated with successful clinical and microbiological outcomes. The principles used in these analyses can be applied to other classes of drugs to develop similar relationships between exposure and outcome. This pharmacokinetic modeling could be used to determine optimal treatment dose in clinical trials in a shorter time frame with fewer patients. This modeling also should be evaluated for its potential to improve outcomes (maximizing therapeutic response, preventing emergence of resistance, and minimizing adverse events) of patients treated with this drug.

[Intraoperative evaluation of the function of the saphenous vein as coronary graft, visualized by myocardial contrast echocardiography]

The assessment of area at risk of saphenous vein graft occlusion is an unsolved problem. We studied myocardial perfusion with contrast echocardiography in 13 patients undergoing coronary surgery. The left ventricle was imaged in the transgastric short axis view at midpapillary muscle level. The myocardial distribution area of 21 saphenous vein grafts was measured by injecting 0.2-0.5 cc of sonicated 5% albumin microspheres directly in the graft, early after weaning from cardiopulmonary bypass. Percent left ventricular area opacification was calculated for each graft injection: right coronary (N = 8) 21 +/- 7%, marginal branch (N = 10) 17 +/- 5%, left anterior descending and diagonal branch (N = 3) 41 +/- 4%. Myocardial systolic wall thickening was not effected by contrast injection (preinjection 45 +/- 12% vs postinjection 46 +/- 7%, p = NS). No local or systemic side effects were encountered.

IN CONCLUSION

myocardial contrast echocardiography is a safe and useful method to measure the area at risk for saphenous vein graft occlusion.

[An atypical case of visceral leishmaniasis]

The authors report a case of infant visceral Leishmaniosis observed in their Department, that showed unusual clinical finding (absence of fever). They emphasize the current epidemiologic situation and recommend to consider the disease in the diagnosis of long term syndroms occurring without fever and with hepatosplenomegaly.

Assessment of liver circulation by quantitative scintiangiography: evaluation of the relative contribution of the hepatic arterial and portal venous blood flows to liver perfusion

Quantitative hepatic scintiangiography was previously used for evaluating the relative contribution of hepatic arterial and portal venous blood flows to the hepatic circulation. The present study compares 3 different procedures (automatic and manual integration, and slope fitting methods) for analyzing the hepatic time activity curves obtained after bolus i.v. injection of 370 MBq 99mTc-diethylentriaminopentacetic acid. Twenty five subjects were studied: five controls, ten cirrhotics, and ten portal hypertensive patients previously submitted to side to side portacaval anastomosis. The correspondence between results given by the different methods was satisfactory only in shunted patients, and the reproducibility of computed parameters was quite poor for all procedures. Accordingly, none of the methods can be considered as supporting reliable quantitative pathophysiological evaluations. However, the hepatic arterial/portal venous flow ratio was found to be increased in liver cirrhosis and in shunted patients and therefore, in spite of the limitations underlined before and of the absence of data on the reproducibility of consecutive injections, hepatic scintiangiography may be of some clinical utility.

The course of cryptococcal capsular polysaccharide antigenemia/human cryptococcal polysaccharide elimination kinetics

The detection of cryptococcal polysaccharides in the serum is diagnostic of cryptococcosis in the absence of rheumatoid factor. The significance of the continued detection of this antigen in the serum during antifungal therapy is not known. Prolonged antigenemia might indicate ongoing active infection, delayed clearance of the polysaccharides from the blood, or continued release of the polysaccharide antigens from a reservoir of nonviable organisms. In seven cases the cryptococcosis with prolonged and high levels of cryptococcal polysaccharide antigenemia, the courses of antigenemia were determined. During the convalescent phase, the T 1/2's were approximately 48 hours for the antigen clearance in all the cases studied. The polysaccharide antigens recovered from the serum of one patient had molecular weights of greater than 200,000 daltons. In rabbits, a single intravenous injection of cryptococcal capsular polysaccharides showed a similarly slow clearance of the antigen with a T 1/2 of approximately 24 to 48 hours. These data suggest that adequately treated cases of cryptococcosis may have a predictable rate of antigen clearance from the serum during convalescence.

The significance of eubacterium bacteremia

Eubacterium is a commensal of the human gastrointestinal tract. In rare instances this organism can become blood-borne. Nine cases of bacteremia were described and eight cases were found in the medical literature. Thirteen of the 17 cases (76%) had active gastrointestinal disease leading to the Eubacterium bacteremia. It is suggested that recovery of Eubacterium in blood culture should alert the clinician to the possibility of active gastrointestinal disease including occult neoplasms.

Susceptibility of zygomycetes to amphotericin B, miconazole, and ketoconazole

Susceptibility to amphotericin B, miconazole, and ketoconazole was determined for 25 clinical isolates of zygomycetes in yeast nitrogen base broth and human serum. In yeast nitrogen base broth, 7 of 25 isolates were susceptible to an imidazole or amphotericin B. In serum, all were resistant to the imidazoles and inhibited by amphotericin B, the current drug of choice for infections caused by zygomycetes.

Susceptibility of Zygomycetes to human serum

Seven members of the class Zygomycetes were tested for serum susceptibility. Five of the isolates were inhibited to different degrees by pooled fresh human serum. Heating the serum at 56 degrees C for 30 min to inactivate complement did not abolish the inhibitory activity in the serum. Members of the genera Cunninghamella and Absidia appeared most susceptable to the inhibitory effects of serum while members of the genus Rhizopus were most resistant. One isolate of R. arrhizus appeared to have enhanced growth in the presence of human serum. Our findings suggest certain species of the class Zygomycetes are strongly inhibited by serum, and this may account for the rarity of human infections by these species.