Cholesterol affects retinal nerve fiber layer thickness in patients with multiple sclerosis with optic neuritis.

BACKGROUND AND PURPOSE: To evaluate the associations between retinal nerve fiber layer (RNFL) thickness and lipid profiles in multiple sclerosis (MS). METHODS: This study enrolled 136 patients with MS (n = 272 eyes; 108 females, 28 males, mean age: 46.7 ± 8.9 years); 45% had a history of optic neuritis (ON). Subjects received optical coherence tomography (OCT) testing to assess RNFL thickness and visual acuity testing with Snellen charts. A subset of 88 patients received pattern reversal visual-evoked potential (PRVEP) testing. Lipid profiles consisting of serum high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol and total cholesterol (TC) levels were obtained within ± 6 months of OCT. Regression analyses were used to assess the associations between RNFL thickness and lipid profile variables. RESULTS: Low RNFL thickness (P = 0.008) and higher PRVEP latency (P = 0.017) were associated with high LDL cholesterol > 100 mg/dl status. Low RNFL thickness (P = 0.008) and higher PRVEP latency (P = 0.043) were associated with high HDL cholesterol levels. Low RNFL thickness was also associated with HDL cholesterol > 60 mg/dl status (P = 0.001) and with TC > 200 mg/dl status (P = 0.015). The probability of average RNFL thickness in the lowest tertile (≤ 33rd percentile) was associated with interactions between TC > 200 mg/dl status (P = 0.001, odds ratio = 7.5, 95% confidence interval = 2.7-21) with affected/unaffected by ON status. CONCLUSIONS: High cholesterol adversely affects RNFL thickness in patients with MS with ON.

Radiofrequency neurotomy for headache stemming from the zygapophysial joints C2/3 and C3/4.

BACKGROUND: Headaches are a major socio-economic problem, and reliable and effective treatments may have an important economic impact. While many studies have investigated neck pain stemming from the zygapophysial joint, there is little data on the specific problem of headache from the zygapophysial joint C3/4. METHODS: In this investigation we included only patients who suffered from chronic headaches which had lasted for at least 12 months and were due to irritation of the zygapophysial joints (facets) of the upper cervical spine. As we aimed to prove the effectiveness of radiofrequency neurotomy in these patients, we had no randomized control group. Patients with the following underlying diseases were included in the study group: cervical fusions (followed by pseudoarthrosis); traumatic cervical fractures (not fused); arthritis. RESULTS: We examined the extent of pain relief on the first day after radiofrequency treatment and the duration of pain relief until recurrence of 50% of pre-coagulation pain in the whole collective and the three subgroups. CONCLUSIONS: Our results indicate that this therapy is effective in patients with underlying diseases of primarily degenerative origin. A significant finding was that in the group of patients with arthritis, the duration and extent of pain relief were extremely short compared to the other two groups (p<0.005, U-test).

Unilateral high-altitude pulmonary edema (HAPE): a case report and discussion of pathophysiology.

High-altitude pulmonary edema (HAPE), a potentially life-threatening altitude adaptation disorder, is considered to be caused by an exaggerated increase in pulmonary blood pressure and a non-cardiogenic rise in pulmonary vascular permeability subsequent to alveolar hypoxia. A 40-year-old male mountaineer was affected by an advanced stage of HAPE at high altitude (Monte Rosa plateau, 4000 m). The symptoms abated immediately after the patient descended from the altitude. However, six hours after the symptoms had resolved, radiographic signs of pulmonary edema, confined to the right lung, were seen. This rarely described unilateral radiological pattern of HAPE resolved completely within two days. We suggest that aspiration events of nasal secretion, the right sleeping position at night and an elevated right diaphragm reduced the patient's compensatory hyperventilation capacity of the right lung. The resulting increased alveolar hypoxia in the right lung was responsible for unilateral edema. The pathophysiological mechanism underlying unilateral HAPE is discussed.

Concentrations of copper, zinc, manganese, rubidium, and magnesium in thoracic empyemata and corresponding sera.

In this study, a number of selected trace elements and clinically relevant parameters were compared between thoracic empyemata and the corresponding sera for a better understanding of the trace element distribution between these two compartments. Serumempyema pairs were obtained from 13 patients and quantified for selected and essential trace elements, namely copper (Cu), zinc (Zn), manganese (Mn), rubidium (Rb), and magnesium (Mg), by inductively coupled plasma-mass spectrometry (ICP-MS). In addition, the concentrations of the following clinical laboratory parameters were analyzed by standard methods: total protein, leukocyte count, lactate dehydrogenase, glucose, pH, and the C-reactive protein. Individual concentrations of the elements determined in the empyemata were frequently higher than in pleural effusions of any other benign or malignant condition except for Cu. Serum Cu exceeded the normal range (600-1400 microg/kg) in 6 out of 13 patients (median 1410 microg/kg). In the empyemata, Zn concentrations (median 2000 microg/kg) were characteristically higher than in the sera (median 450 microg/kg) and exceeded the upper limit for serum (1200 microg/kg) in 8 of the 13 patients. Manganese concentrations in the empyemata (median 2.7 microg/kg) were also higher compared to corresponding sera, although they stayed within the limits considered normal for serum of healthy adults (upper limit 2.9 microg/kg). Rubidium was also moderately higher in most empyemata (median 290 microg/kg) and exceeded the upper limit for serum (560 microg/kg) in two patients. The median concentration of the essential element magnesium was higher in the empyemata (23 mg/kg) than in the sera (21 mg/kg). However, all serum Mg concentrations except three remained within the normal range (17-22 mg/kg). Removal of large amounts of empyematous fluid may deprive the body of trace elements and can cause suboptimal or deficient trace element status and homeostasis. Recuperation will be accelerated by compensatory supplementation of trace elements. Therefore, selective medication with adequate trace element compounds in patients with thoracic empyema can be generally recommended for zinc. The other elements need not necessarily be monitored or substituted, because of their stable concentrations in the serum. Rb may have a biological impact, but deficiency symptoms in man are not clearly defined.

Elevated cerebral perfusion pressure and low colloid osmotic pressure as a risk factor for subdural space-occupying hygromas?

BACKGROUND: Space-occupying subdural hygromas are a late complication of severe traumatic brain injury (TBI) and may delay the patient's recovery. To evaluate the risk factors involved, we performed a semiretrospective, -prospective analysis of three groups of patients, which differed with regard to the techniques used in the management of their cerebral perfusion pressure (CPP) and colloid osmotic pressure (COP) to determine the occurrence of space-occupying subdural hygromas. PATIENTS AND METHODS: Between 1989 and 1997 we examined 696 patients after a severe TBI: Group 1. 1989-1994 mean CPP: 67 (elevated for therapeutic reasons by catecholamines, if necessary), mean COP: 19. Group 2. January 1995-October 1996, mean CPP: 77, mean COP: 20. Group 3. November 1996-December 1997, mean CPP: 79, mean COP: 23 (elevated for therapeutic reasons by infusions of colloids). The groups were comparable for other criteria. RESULTS: Compared to Group 1, Group 2, with a high CPP but lower COP, showed a significantly higher (p < 0.01; chi2-test with correction of Yates) percentage of posttraumatic subdural hygromas with space-occupying aspects, clinical signs of bradycardia, hypertension and impaired consciousness requiring surgery (Group 1: 1.75%; Group 2: 10.46%; Group 3: 0%). In Group 3 we saw no patient with a space-occupying hygroma. CONCLUSION: We conclude that iatrogenic elevated CPP, which has been reported to be helpful in preventing secondary ischemic damage after a severe TBI, may be harmful to a patient if the COP is not maintained within physiological ranges.

Visually evoked potentials in 52 children requiring operative repair of craniosynostosis.

We evaluated the prevalence of pathological visually evoked potentials (VEP) before the appearance of papilledema or other signs of elevated intracranial pressure in children suffering from craniosynostosis. In 52 children (19 girls, 33 boys, median age 7.6 months, mean age 7.6 months, range from 3 to 34 months) preoperative VEP were analyzed. In 13 patients, pathological VEP were observed. In all children, both eyes were involved. Only 1 child suffered from papillar anomalies. Latency was pathological in 12 children, whereas the amplitude was suppressed in only 2 children. In all children with preoperative pathological VEP, postoperative controls (n = 4) were improved or normal. Thus, VEP may be the first test for neuronal damage in craniosynostosis.

Quality control of liposomal lipids with special emphasis on peroxidation of phospholipids and cholesterol.

The usefulness of various assays for the determination of phospholipid and cholesterol peroxidation in liposome formulations was studied on model liposomes prepared as small unilamellar vesicles (SUV) and multilamellar vesicles (MLV) from either native egg phosphatidylcholine (EPC), partially hydrogenated egg phosphatidylcholine (PHEPC) or fully hydrogenated egg phosphatidylcholine (HEPC) and cholesterol in 65/35 molar ratio at a total lipid concentration of 10 mumol/ml in phosphate buffered saline pH 7.2. Liposomes were incubated at 50 degrees C for a total of 3 months. Fatty acid and cholesterol peroxidation were monitored after 1, 2 and 3 months by quantitative measurement of fatty acids and cholesterol and as well as peroxidation products. Fatty acid peroxidation products malondialdehyde, lipidhydroperoxides, conjugated dienes, conjugated trienes were poor predictors of actual fatty acid loss. Among the cholesterol peroxidation products 7-hydroxy-cholesterols, 7-keto-cholesterol and 4-cholesten-3-one were measured quantitatively. Only the formation of 7-keto-cholesterol correlated well with cholesterol disappearance.

Single-dose pharmacokinetics and tolerance of a cholesteryl sulfate complex of amphotericin B administered to healthy volunteers.

Twenty-three healthy volunteer subjects received a single dose of amphotericin B colloidal dispersion or placebo (4:2) in a double-blind, randomized, dose-escalating design. Doses ranged from 0.25 to 1.5 mg/kg of body weight. The medication was administered via intravenous infusion at a rate of 0.5 mg/kg/h. Plasma amphotericin B concentrations increased with increasing doses, resulting in a linear increase in the amphotericin B area under the curve. Concentrations in plasma decreased rapidly upon discontinuation of the infusion, indicating rapid tissue distribution. A log-linear biexponential elimination phase was observed. A three-compartment open model was used to describe the distribution and elimination of amphotericin B. The mean terminal elimination half-life ranged from 86 h at the 0.25-mg/kg dose level to 244 and 235 h at the 1.0- and 1.5-mg/kg dose levels, respectively. Mean total body clearance ranged from 219 to 284 ml/kg/h. The volume of distribution increased with dose, from 3.37 liter/kg at the 0.25-mg/kg dose to 7.92 liter/kg at the 1.5-mg/kg dose. At the lowest dose level, 0.25 mg/kg, the medication was generally well tolerated. Progressive increases in the dose led to increasing side effects. At the 1.5-mg/kg dose level, 50% of the patients on active medication experienced nausea, vomiting, and chills. Physical examinations, ophthalmologic examinations, and clinical laboratory parameters remained within normal limits compared with those obtained during prestudy examinations.

Quantitative determination of cholesterol in liposome drug products and raw materials by high-performance liquid chromatography.

Most liposomes used as drug delivery systems contain cholesterol as a major structural component. Cholesterol has profound effects on the chemical, physical and metabolic stability of liposomes and liposome drug products and must be accurately monitored during formulation and processing development, stability testing and manufacturing. Before analyzing their components, the liposomes must be disintegrated and solubilized by dilution with methanol or 2-propanol. This high-performance liquid chromatographic assay is applicable to the resulting lipid-rich matrices and allows a direct quantitative analysis of cholesterol. Cholesterol separates well from common ingredients of liposome-based drug products and cholesterol oxidation products. Calibration curves are linear over two orders of magnitude and the cholesterol detection limit is 1.5 microliter/ml. Method precision for an anticancer liposome drug formulation was 0.9% relative standard deviation. The assay is also useful for measuring cholesterol in phospholipid and cholesterol raw materials.

Changes in membrane lipid composition during saline growth of the fresh water cyanobacterium Synechococcus 6311.

Growth of Synechococcus 6311 in the presence of 0.5 molar NaCl is accompanied by significant changes in membrane lipid composition. Upon transfer of the cells from a low salt' (0.015 molar NaCl) to high salt' (0.5 molar NaCl) growth medium at different stages of growth, a rapid decrease in palmitoleic acid (C16:1 delta 9) content was accompanied by a concomitant increase in the amount of the two C18:1 acids (C18:1 delta 9, C18:1 delta 11), with the higher increase in oleic acid C18:1 delta 9 content. These changes began to occur within the first hour after the sudden elevation of NaCl and progressed for about 72 hours. The percentage of palmitic acid (C16:0) and stearic acid (C18:0) remained almost unchanged in the same conditions. High salt-dependent changes within ratios of polar lipid classes also occurred within the first 72 hours of growth. The amount of monogalactosyl diacylglycerol (bilayer-destabilizing lipid) decreased and that of the digalactosyl diacylglycerol (bilayer-stabilizing lipid) increased. Consequently, in the three day old cells, the ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol in the membranes of high salt-grown cells was about half of that in the membranes of low salt-grown cells. The total content of anionic lipids (phosphatidylglycerol and sulfoquinovosyl diacylglycerol) was always higher in the isolated membranes and the whole cells from high salt-grown cultures compared to that in the cells and membranes from low salt-grown cultures. All the observed rearrangements in the lipid environment occurred in both thylakoid and cytoplasmic membranes. Similar lipid composition changes, however, to a much lesser extent, were also observed in the aging, low salt-grown cultures. The observed changes in membrane fatty acids and lipids composition correlate with the alterations in electron and ion transport activities, and it is concluded that the rearrangement of the membrane lipid environment is an essential part of the process by which cells control membrane function and stability.

Selenium deficiency, endurance exercise capacity, and antioxidant status in rats.

Increased O2 metabolism imposed by physical exercise is likely to augment the production of active O2 species that have been shown to react with lipids, proteins, and DNA. Antioxidants and antioxidant enzymes, such as the selenium enzyme glutathione peroxidase, minimize or prevent such potentially toxic reactions. This study shows that selenium deficiency decreases glutathione peroxidase activity in liver and muscle (less than 80%, P less than 0.001), increases total glutathione in liver, muscle, and plasma (P less than 0.05) and increases muscle cytochrome oxidase activity, and ubiquinone content (P less than 0.05) but has no effect on endurance capacity. Exercise to exhaustion resulted in a significant (P less than 0.001) elevation of total and oxidized glutathione (GSSG) and a significant (P less than 0.05) decrease of vitamin E in plasma of control and selenium-deficient rats. Acute exercise also increased tissue GSSG levels in both control and selenium-deficient groups of rats. Hence, despite a large depletion of selenium-deficient glutathione peroxidase, pronounced oxidation of glutathione to GSSG can be produced by the increased oxidative metabolism during physical exercise. The results suggest that the residual glutathione peroxidase activity is sufficient to detoxify hydroperoxides in exercising selenium-deficient animals and to prevent the impairment of endurance capacity.

Quantitative determination of vitamin E and oxidized and reduced coenzyme Q by high-performance liquid chromatography with in-line ultraviolet and electrochemical detection.

We describe a sensitive quantitative high-performance liquid chromatographic (HPLC) assay for the simultaneous determination of vitamin E isomers (alpha-, gamma- and delta-tocopherol), oxidized coenzyme Q species (ubiquinone 9, ubiquinone 10) and reduced coenzyme Q homologues (ubiquinol 9, ubiquinol 10) in various tissues, including blood and plasma. The compounds of interest are quantitatively extracted with a fast one-step lipid extraction procedure and subjected to HPLC without further purification. The extract is separated on a reversed-phase column and the eluted compounds are monitored by sequential UV and electrochemical detection. Ubiquinones are detected at their 275 nm absorbance maximum, by the UV detector, whereas tocopherols and ubiquinols are monitored by the electrochemical detector with high sensitivity and selectivity. The method can detect as little as 1 pmol of the individual ubiquinones. Detection limits for tocopherols and ubiquinols are at least two orders of magnitude lower.

Simultaneous determination of tocopherols, ubiquinols, and ubiquinones in blood, plasma, tissue homogenates, and subcellular fractions.

A fast single-step lipid extraction procedure and high-performance liquid chromatography with in-line uv and electrochemical detection are used for the simultaneous quantitative determination of tocopherols, ubiquinols, and ubiquinones in blood, plasma, tissue homogenates, and subcellular fractions. The compounds of interest can be quantitatively extracted into hexane from a sodium dodecyl sulfate-treated aqueous homogenate after precipitation of protein by addition of an equal volume of ethanol. alpha-, gamma-, and delta-Tocopherol, ubiquinol 9, ubiquinol 10, and ubiquinones 9 and 10 can be well separated on a reversed phase column. Ubiquinones are detected at 275 nm by the uv detector, and ubiquinols and tocopherols by the electrochemical detector in the oxidative mode. Quantitation is done by comparing chromatographic peak heights to those of a standard solution containing known amounts of tocopherols, ubiquinols 9 and 10, and ubiquinones 9 and 10, analyzed under identical conditions. The high sensitivity of the electrochemical detection allows operation at low potentials (+0.5 V) with low detector response, but high selectivity for the easily oxidizable tocopherols and ubiquinols and decreased baseline noise. The uv detection limits the overall sensitivity of the procedure to 2 pmol ubiquinone, corresponding to 0.1 microM ubiquinone in the lipid extract. The ranges of values obtained for rat and guinea pig tissues, for rat liver mitochondria, and for blood and plasma from rats and humans are given.

Bremsstrahlung isochromat spectroscopy using a modified XPS apparatus.

The new components required for bremsstrahlung isochromat spectroscopy (BIS) in UHV (10(-12) Torr range) have been developed and incorporated into an x-ray photoelectron spectrometer. They consist of a Pierce electron gun and a soft x-ray photon detector, both of which have to fulfill precise geometrical conditions imposed by the already existing monochromator. A description of the design and testing of this equipment is given. The resolution and the intensity appear to be correlated so that a compromise has to be found in order to achieve high resolution with acceptable intensity. It is demonstrated on the basis of suitable spectra that the density of unoccupied states above the Fermi level can be investigated with a resolution better than 0.43 eV.