Comparative evaluation of surface deposits on high water content hydrogel contact lens polymers

Twenty soft contact lens wearers were fit with a high water content, non-HEMA (ofilcon A) lens (Durasoft 4; Wesley-Jessen) on the test eye. Patients subsequently wore one of the following four lenses on the same eye: a high-water content non-HEMA (surfilcon A) lens (Permaflex 74; CooperVision); a modified mid-water content HEMA (bufilcon A) lens (Hydrocurve Elite; Sola/Barnes-Hind); a low-water content HEMA (polymacon) lens (O4; Bausch & Lomb); or a low-water content non-HEMA (crofilcon A) lens (CSI; Sola/Barnes-Hind). All lenses were worn on a daily wear basis for one month and then evaluated with the scanning electron microscope (SEM). The amount of surface deposition was measured in terms of the area of lens covered by deposit as visualized on a standard series of SEM photographs. When control was obtained for patient, eye, technique, care system, and wearing time, similar amounts of deposit were found on the two high water content soft lenses. A significantly greater amount of deposit was found on the non-HEMA high water content ofilcon A lens compared to the mid-water content modified HEMA material. However, when the patient's tendency to produce "heavy" or "light" deposits on a soft lens surface is taken into account, then for the lighter depositors the high water content non-HEMA material was found to be as acceptable as the low water content HEMA and non-HEMA materials. But for heavy depositors the high water content non-HEMA material is not recommended.     

Tolerance,cross-tolerance and dependence measured by operant responding in rats treated with triazolam via osmotic pumps

Previous research has found that drugs with affinity for (benzodiazepine) sites differ in their abilities to produce tolerance and dependence. The present study therefore investigated the effects of ligands of (BZ) sites in rats that had been rendered tolerant to a benzodiazepine. Two experiments were carried out in separate groups of rats. Behavioral changes induced by chronic infusion of triazolam (3 mg/kg/day, SC, for 14 days) via osmotic pumps were studied in animals trained on a fixed ratio 10 schedule of food presentation. Control animals were implanted with pumps containing the vehicle. Test drugs were administered IP using cumulative dosing. In one experiment triazolam decreased response rates on days 1, 2 and 3 after implantation of the pumps and tolerance developed to this depressant effect. In the other experiment, vehicle and triazolam treated rats differed in their responding during chronic infusion but differences were not statistically significant on any particular day. Flumazenil (3.0–30 mg/kg) greatly decreased rates of responding on day 11 in triazolam treated rats. This effect may represent a precipitated withdrawal syndrome. However, no withdrawal effects on operant performance were observed upon pump removal. Chronic infusion of triazolam did not affect the sensitivity of rats to alpidem on day 11 (10–100 mg/kg) whereas it abolished the stimulant effect of bretazenil (0.1–1.0 mg/kg). Chronic triazolam treatment produced tolerance to the depressant effects of triazolam (1.0–3.0 mg/kg), lorazepam (0.3–3.0 mg/kg) and zopiclone (10 mg/kg) but no tolerance to those of CL 218,872 (3.0–30 mg/kg) and zolpidem (0.3–3.0 mg/kg) when tested 3–14 days after pump removal. Differences between compounds highlighted with this model are in agreement with previous observations that these agents possess different pharmacological profiles and different potentials to induce tolerance and dependence.     

Intercomparison of calibration procedures for 192Ir HDR sources in Brazil

The lack of well established dosimetry protocols for HDR sources is a point of great concern regarding the uniformity of procedures within a particular country and worldwide. The main objective of this paper is to report the results from ten institutions of an intercomparison of calibration procedures for 192Ir HDR sources currently in use in Brazil. The treatment irradiator of one institution was calibrated by a reference system and used by all participants with their own measuring electrometers and ionization chambers under the same experimental conditions. Two methods were used: the calibration jig and the well-type ionization chamber. Each participant was allowed to use their own method and formalism. The results of this exercise were very positive since this was the first time in Brazil that a group of users gathered to share their experience and openly discuss the physical concepts behind the calibration procedures. The results were all within +/-3.0%, except one case where -4.6% was observed and later identified as a problem with the Nk value for x-rays. Though the magnitude of the deviations found was generally acceptable considering the diversity of formalisms currently in use, a proposal is now being prepared to be adopted as a national protocol. The identification of the institutions was left out for the sake of confidentiality.     

The presterilization microbial load on used medical devices and the effectiveness of hydrogen peroxide gas plasma against Bacillus subtilis spores.

OBJECTIVES: To determine the microbial load found on used critical medical devices (5 spinal anesthesia needles, 21 catheters, and 28 sheaths) prior to sterilization and to evaluate the effectiveness of hydrogen peroxide gas plasma against inoculated Bacillus subtilis var globigii (American Type Culture Collection 9372) spores. METHODS: Membrane filter and pour-plate methods were applied to estimate total microbial loads (aerobic and anaerobic, mesophilic and thermophilic, vegetative and spore forms). Spinal anesthesia needles (102 units) and sheath components (61 units) were inoculated with a suspension of B. subtilis spores. After drying, the devices were sterilized with hydrogen peroxide gas plasma. RESULTS: Higher counts of aerobic, mesophilic, and fungal organisms were recovered when the drying period was insufficient. Anaerobic spores were not found in any analyzed presterilization items. The hydrogen peroxide gas plasma effected a 5 to 7 log10-fold reduction in B. subtilis spore counts in well-dried needles and sheath components. CONCLUSIONS: The success of hydrogen peroxide gas plasma sterilization depends mostly on educating the staff to assure well-cleaned and dried reusable medical devices, allowing penetration of the hydrogen peroxide gas plasma into the critical points of the items and providing a reduction in organisms.     

Level of use of 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) in humans correlates with EEG power and coherence

Rationale: Despite animal studies implicating 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) in serotonergic neurotoxicity, there is little direct evidence of changes in neural function in humans who use MDMA as a recreational drug. Objective: The present study investigated whether there is a correlation between quantitative EEG variables (spectral power and coherence) and cognitive/mood variables, and level of prior use of MDMA. Methods: Twenty-three recreational MDMA users were studied. Resting EEG was recorded with eyes closed, using a 128-electrode geodesic net system, from which spectral power, peak frequency and coherence levels were calculated. Tests of intelligence (NART), immediate and delayed memory, frontal function (card sort task), and mood (BDI and PANAS scales) were also administered. Pearson correlation analyses were used to examine the relationship between these measures and the subject’s consumption of MDMA during the previous 12-month period. Partial correlation was used to control for the use of other recreational drugs. Results: MDMA use was positively correlated with absolute power in the alpha (8–12 Hz) and beta (12–20 Hz) frequency bands, but not with the delta (1–3 Hz) or theta (4–7 Hz) bands. MDMA use was negatively correlated with EEG coherence, a measure of synchrony between paired cortical locations, in posterior brain sites thought to overly the main visual association pathways of the occipito-parietal region. MDMA use did not correlate significantly with any of the mood/cognitive measures except the card sort task, with which it was weakly negatively correlated. Conclusions: Alpha power has been shown to be inversely related to mental function and has been used as an indirect measure of brain activation in both normal and abnormal states. Reduced coherence levels have been associated with dysfunctional connectivity in the brain in disorders such as dementia, white-matter disease and normal aging. Our results may indicate altered brain function correlated with prior MDMA use, and show that electroencephalography may be a cheap and effective tool for examining neurotoxic effects of MDMA and other drugs. Received: 19 October 1998/Final version: 12 January 1999     

The Effect of Calcium Channel Antagonists on Spontaneous and Evoked Epileptiform Activity in the Rat Neocortex In Vitro

Calcium influx through voltage-activated calcium channels may play a crucial role in the propagation and maintenance of seizure activity. We have examined the contribution of various types of calcium currents to epileptogenesis by studying the effects of various calcium channel blockers on epileptiform activity. N-methyl-d-aspartate receptor-mediated epileptiform activity was induced by removal of magnesium ions superfusing the cortex, or by low-frequency stimulation of the underlying white matter. CoCl2, CdCl2 and omega-conotoxin, acting at the N- and L-type calcium channels, significantly reduced epileptiform activity. L-channel antagonists nifedipine and verapamil, and the agonist BAY K 8644, increased spontaneous bursting in cortical wedges, but had no effect upon evoked activity. The T-channel blocker NiCl2 had variable effects on epileptiform activity, whereas phenytoin consistently reduced such activity. These results suggest that calcium influx underlying epileptiform activity in the rat neocortex may occur at least partially via the activation of the N-type calcium channel. However, contributions from other calcium channel types cannot be excluded.     

The effect of temperature on copper tolerance ofParamecium

Summary The copper tolerance ofParamecium tetraurelia decreases with increased temperatures over the range of 12 C to 34 C. The relationship is linear and the correlation=–0.98. The regression equation has an intercept of 16 M Cu⁺⁺ at 0 C, and tolerance is reduced by 0.33 M for each degree increase in temperature.     

Ten-year outcomes in a population-based cohort of node-negative, lymphatic, and vascular invasion-negative early breast cancers without adjuvant systemic therapies.

PURPOSE: To discuss the absolute benefits from adjuvant systemic therapy knowledge of long-term outcomes and baseline risks of relapse and disease-specific survival are required. We assessed the 10-year outcomes in a population-based cohort of node-negative (N-) lymphovascular negative (LV-) early breast cancers diagnosed from 1989 to 1991 who did not receive adjuvant systemic therapy. METHODS: One thousand one hundred eighty-seven cases of pT(1-2)N(0) LV- breast cancers with a median follow-up of 10.4 years were reviewed. Kaplan-Meier survival curves for relapse free survival (RFS), breast cancer-specific survival (BCSS) and overall survival (OS) were compared with log-rank tests with cohorts stratified for tumor size and grade. RESULTS: The median age of this series was 62 years. Four hundred thirty tumors were < or = 1 cm in diameter (cohort 1), 507 were 1.1-2 cm (cohort 2), and 250 were 2.1 to 5 cm in diameter (cohort 3). The 10-year outcomes for cohorts 1, 2, and 3, respectively, were significantly different: RFS, 82%, 75%, and 66%; BCSS, 92%, 90%, and 77%; and OS, 79%, 78%, and 66%. Tumor grade significantly altered outcome within size cohorts, particularly in pT(1)N(0) breast cancers. CONCLUSION: This study provides detailed information on the continued relapse and breast cancer death rate to 10 years of follow-up. Specifically, without adjuvant systemic therapy, patients with LV-, N - breast cancer had a > or = 25% 10-year risk of relapse and a corresponding 10-year breast cancer death rate of > or = 10% if they had either a grade 3 tumor < or = 1 cm, a grade 2 to 3 tumor from 1.1 to 2 cm, or any grade tumor greater than 2 cm.     

Localized pelvic neuroblastoma: excellent survival and low morbidity with tailored therapy--the 10-year experience of the French Society of Pediatric Oncology.

PURPOSE: To assess the results and morbidity of treatment of children with localized pelvic neuroblastoma (NB). PATIENTS AND METHODS: All consecutive cases of localized pelvic NB registered in the French multicenter prospective studies NBL90 and NBL94 between 1990 and 1999 were reviewed. Resectability was decided on the basis of clinical and radiologic evaluation. In unresectable tumors, primary chemotherapy (combinations of carboplatin-etoposide and vincristine-cyclophosphamide-doxorubicine) was administered before surgery. RESULTS: Forty-seven children (with 26 resectable tumors and 21 unresectable) were included in this study. At the end of treatment, 31 children were in complete remission (66%). Long-term neurologic sequelae were observed in seven patients (15%), directly attributable to surgery in three cases. After a median follow-up of 48 months (range, 13 to 129 months), 44 patients are alive. Six children experienced local relapse; four of these children achieved subsequent remission. The projected overall survival and event-free survival (EFS) rates at 5 years are, respectively, 93% +/- 4% and 84% +/- 5%. Survival of children treated with preoperative chemotherapy are similar to those treated by primary surgery (80% and 88% respectively). The extent of surgical resection seemed to have no influence on the outcome (EFS rates 76% and 89% in case of gross residue and complete resection or microscopic residue, respectively). CONCLUSION: Our data confirm the excellent survival of localized pelvic NBs. Considering the efficacy of preoperative chemotherapy, patients with pelvic NB should be carefully screened for primary surgery. The risk of neurologic impairment during radical excision should be balanced with the good survival of children with minimal residual disease.