Derivation of lenticular transmittance from fluorophotometry

PURPOSE: To derive transmittance spectra for the human lens using the ratio between posterior and anterior autofluorescence of the lens as measured by fluorophotometry. METHODS: Transmittance spectra of the lens can be described with a one-parameter model to a high degree of accuracy. The parameter m of this model defines the differences between lens transmittance spectra of individuals. In fluorophotometry literature another parameter related to lens transmittance, T, has been defined as the square root of the ratio between posterior and anterior lenticular autofluorescence. T can be predicted from parameter m, given the spectra of the excitation light, of the fluorescence emitted by the lens and of the detecting device are known, and assuming that the anterior and posterior fluorescence efficiencies of the lens are equal. When this relation is inverted, parameter m can be derived from T, giving the complete transmittance spectrum on the basis of T. RESULTS: A transformation curve was calculated to determine T from m and vice versa. The light transmittance spectrum of the lens was calculated as a function of T. The validity of this approach was evaluated using an independent method for assessment of lenticular transmittance. This method consisted of making color slitlamp slides, grading the observed color of these slides with the LOCS III NC grading system, and transforming these grades into the model parameter m using published transformation curves. CONCLUSIONS: The total transmittance spectrum can be calculated reliably from a fluorophotometric scan of the human lens.     

Non-transferrin-bound iron in untreated and ribavirin-treated chronic hepatitis C patients

BACKGROUND: In patients with chronic hepatitis C, elevations in serum iron levels, hepatic iron content and oxidative stress-related molecules have been reported. Treatment with ribavirin induces an increase in hepatic iron concentration. In situations of iron overload, non-transferrin-bound iron can appear. Therefore, we determined non-transferrin-bound iron levels in untreated chronic hepatitis C patients and in patients during interferon-ribavirin treatment. MATERIALS AND METHODS: In 10 untreated and 19 interferon-ribavirin-treated chronic hepatitis C patients, we examined non-transferrin-bound iron levels by a colorimetric method using nitrilotriacetic acid as a ligand and sodium triscarbonatecobalt (III) to block free iron binding sites on transferrin. RESULTS: Despite the presence of high serum iron saturation and ferritin levels, non-transferrin-bound iron was absent in the majority of hepatitis C virus patients (25/29, 86%). There was no difference in non-transferrin-bound iron levels between untreated and treated patients. Four patients with high non-transferrin-bound iron levels were distinguished by higher serum iron levels. In two of these patients, hepatocytic iron was present on liver biopsy. CONCLUSIONS: In the majority of chronic hepatitis C patients, non-transferrin-bound iron levels are normal. Treatment with ribavirin does not induce high non-transferrin-bound iron levels. Non-transferrin-bound iron levels are only higher than normal in hepatitis C patients with higher serum iron levels.     

Residual effects of middle-of-the-night administration of zaleplon and zolpidem on driving ability,memory functions,and psychomotor performance

Thirty healthy volunteers participated in this two-part study. Part 1 was a single-blind, two-period crossover design to determine the effects of a single dose of ethanol (0.03% < BAC < 0.05%) or ethanol-placebo on driving ability, memory, and psychomotor performance. Part 2 was a double-blind, five-period crossover design to measure the effects of a middle-of-the-night administration of zaleplon 10 or 20 mg, zolpidem 10 or 20 mg, or placebo on driving ability 4 hours after administration and memory and psychomotor performance 6 hours after administration. The on-the-road driving test consisted of operating an instrumented automobile over a 100-km highway circuit at a constant speed (95 km/h) while maintaining a steady lateral position between the right lane boundaries. The standard deviation of lateral position (SDLP) was the primary performance parameter of the driving test. The psychomotor and memory test battery consisted of the Word Learning Test, the Critical Tracking Test, the Divided Attention Test, and the Digit Symbol Substitution Test. Data for each part were analyzed separately using ANOVA for crossover designs. Zaleplon 10 and 20 mg did not significantly impair driving ability 4 hours after middle-of-the-night administration. Relative to placebo, after zolpidem 10 mg, SDLP was significantly elevated, but the magnitude of the difference was small and not likely to be of clinical importance. Memory and psychomotor test performance was unaffected after both doses of zaleplon and zolpidem 10 mg. In contrast, zolpidem 20 mg significantly increased SDLP and speed variability. Further, zolpidem 20 mg significantly impaired performance on all psychomotor and memory tests. Finally, driving performance, Digit Symbol Substitution Test, Divided Attention Test, and immediate and delayed free recall of the Word Learning Test were significantly impaired after ethanol. The results show that zaleplon (10 and 20 mg) is a safe hypnotic devoid of next-morning residual impairment when used in the middle of the night.     

Spirochete-platelet attachment and thrombocytopenia in murine relapsing fever borreliosis

Thrombocytopenia is common in persons infected with relapsing fever Borreliae. We previously showed that the relapsing fever spirochete Borrelia hermsii binds to and activates human platelets in vitro and that, after platelet activation, high-level spirochete-platelet attachment is mediated by integrin alpha IIb beta 3, a receptor that requires platelet activation for full function. Here we established that B hermsii infection of the mouse results in severe thrombocytopenia and a functional defect in hemostasis caused by accelerated platelet loss. Disseminated intravascular coagulation, immune thrombocytopenic purpura, or splenic sequestration did not play a discernible role in this model. Instead, spirochete-platelet complexes were detected in the blood of infected mice, suggesting that platelet attachment by bacteria might result in platelet clearance. Consistent with this, splenomegaly and thrombocytopenia temporally correlated with spirochetemia, and the severity of thrombocytopenia directly correlated with the degree of spirochetemia. Activation of platelets and integrin alpha IIb beta 3 were apparently not required for bacterium-platelet binding or platelet clearance because the bacterium-bound platelets in the circulation were not activated, and platelet binding and thrombocytopenia during infection of beta 3-deficient and wild-type mice were indistinguishable. These findings suggest that thrombocytopenia of relapsing fever is the result of platelet clearance after beta 3-independent bacterial attachment to circulating platelets.     

Pain assessment in patients with possible vascular dementia

PREVIOUS studies comparing Alzheimer's disease (AD) patients with the normal elderly suggest that AD patients experience less pain. In the present study, pain reporting in 20 patients with possible vascular dementia (VaD) was compared to 20 nondemented elderly who had comparable pain conditions. It was hypothesized that, due to de-afferentiation, the possible VaD patients would experience more pain than the cognitively intact elderly. Pain assessment was conducted using three visual analogue scales, (1) the Coloured Analogue Scale (CAS) for Pain Intensity, (2) the CAS for Pain Affect, and (3) the Faces Pain Scale (FPS); a verbal pain questionnaire, Number of Words Chosen--Affective (NWC-A) of the McGill Pain Questionnaire; and an observation scale, the Checklist of Nonverbal Pain Indicators (CNPI). Results showed a significant increase in the scores on the CAS for Pain Affect and the FPS in the demented patients compared to the control group. There was a tendency for an increase in scores on the CNPI in the VaD group. These results suggest that patients with possible VaD suffer more pain than healthy elderly without cognitive impairment.     

Inflammation markers in relation to cognition in a healthy aging population

The relation between serum inflammatory protein levels and cognitive performance was investigated in a healthy population.Individuals were tested during 6 years of follow-up. Serum concentrations of 10 inflammatory proteins were correlated to cognitive speed (Letter-Digit Coding Test, LDCT), attention and information processing (Stroop) and memory (Word Learning). Haptoglobin levels at baseline correlated negatively with cognitive performance on the Stroop and Word Learning Recall test over the 6 years follow-up period. C-reactive protein (CRP) levels at baseline correlated negatively with performance on the Word Learning tests over the 6 years follow-up period. Thus, relatively high concentrations of haptoglobin and C-reactive protein may be indicative for impaired cognitive performance.     

Mechanical complications of total shoulder inverted prosthesis

Our series of inverted prosthesis included 5 patients with a mean age of 73 +/- 6 years. In 4 cases, the implant was performed as a surgical revision. The follow up was 81 +/- 15 months. Three shoulders were pain free whereas two caused a dull pain after a free interval due to mechanical complications. The mean active elevation was 72 degrees while external rotation was - 2 degrees. The adjusted Constant score passed from 32 to 60. In case of complications, the score dropped to 32. Mechanical complications were important with in one case, an unscrening of the glenosphere and in two cases, a loosening of the glenoid prosthesis. This last and major complication occurred 6 years after surgery and was promoted by the occurrence of a progressive bone erosion in the scapula. This gap represented an attempt to accomodate the medial part of the humeral prosthesis under the scapula when the arm is at rest or in adduction. The concept of an inverted prosthesis is attractive and this implant remains one of the options in cuff-tear arthropathy. Our results were not as good as those reported by others but most of ours patients had been already operated before. The occurrence of an osseous gap on pilar of scapula may lead to failure of this prosthesis. This gap remains a threath as it can progress and as such warrants a design alteration of the prosthesis.     

A comparison of 0.1% and 0.2% ropivacaine and bupivacaine combined with morphine for postoperative patient-controlled epidural analgesia after major abdominal surgery

Ropivacaine (ROPI), which is less toxic and produces less motor block than bupivacaine (BUPI), seems attractive for epidural analgesia. Few data are available concerning dose requirements of epidural ROPI when combined with morphine. In this study, we compared the dose requirements and side effects of ROPI and BUPI combined with small-dose morphine after major abdominal surgery. Postoperatively, 60 patients were randomly allocated (double-blinded manner) to four groups: patient-controlled epidural analgesia with the same settings using 0.1% or 0.2% solution of ROPI or BUPI combined with an epidural infusion of 0.1 mg/h of morphine. Pain scores, side effects, motor block, and local anesthetic consumption were measured for 60 h. Pain scores and the incidence of side effects did not differ among the groups. Consumption of ROPI and BUPI were similar in both 0.1% groups. Doubling the concentration significantly reduced the consumption (milliliters) of BUPI (P < 0.05) but not of ROPI. Consequently, using ROPI 0.2% significantly increased the dose administered as compared with ROPI 0.1% (ROPI 0.1% = 314 +/- 151 mg and ROPI 0.2% = 573 +/- 304 mg at Hour 48; P < 0.05). Patient-controlled epidural analgesia with the 0.1% or 0.2% solution of ROPI or BUPI combined with epidural morphine resulted in comparable analgesia. As compared with ROPI 0.1%, the use of ROPI 0.2% increased consumption of local anesthetic without improving analgesia. IMPLICATIONS: Small-dose (0.1%) ropivacaine and bupivacaine have similar potency and result in comparable analgesia and incidence of side effects.     

How correctly does an intramedullary rod represent the longitudinal tibial axes?

In a robot-assisted procedure for preparing the tibia in total knee arthroplasty, developed in the authors' laboratory, an intramedullary rod is used to register the tibia. In 18 formalin-fixed tibias, the difference in orientation was calculated between the intramedullary rod and several longitudinal tibial axes used in clinical practice. This was done using roentgenstereophotogrammetric analysis. Three tibial axes and two insertion techniques were considered. In three-dimensional space, small differences between the axes are observed. The results showed a high standard deviation, indicating the importance of anatomic differences. In the frontal plane, the difference in orientation between rod and tibial axes never exceeded +/- 2 degrees. In the sagittal plane, the observed differences were larger. Significant differences between the considered axes appeared. The results of the two insertion techniques were not significantly different. Because an intramedullary rod frequently is used for alignment of the tibia in conventional surgery, these results also are valuable for conventional surgery. In the current study, the accuracy of the intramedullary alignment is examined, without influences of the sawing procedure. Moreover, the study is not limited to the frontal plane; the total accuracy in three-dimensional space, and the accuracy in the frontal and the sagittal planes were studied.