Intensity warping for multisite MRI harmonization.

In multisite neuroimaging studies there is often unwanted technical variation across scanners and sites. These "scanner effects" can hinder detection of biological features of interest, produce inconsistent results, and lead to spurious associations. We propose mica (multisite image harmonization by cumulative distribution function alignment), a tool to harmonize images taken on different scanners by identifying and removing within-subject scanner effects. Our goals in the present study were to (1) establish a method that removes scanner effects by leveraging multiple scans collected on the same subject, and, building on this, (2) develop a technique to quantify scanner effects in large multisite studies so these can be reduced as a preprocessing step. We illustrate scanner effects in a brain MRI study in which the same subject was measured twice on seven scanners, and assess our method's performance in a second study in which ten subjects were scanned on two machines. We found that unharmonized images were highly variable across site and scanner type, and our method effectively removed this variability by aligning intensity distributions. We further studied the ability to predict image harmonization results for a scan taken on an existing subject at a new site using cross-validation.

Glycine receptor antibody mediated Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM): a rare but treatable neurological syndrome.

A 40-year-old man presented with respiratory compromise and was intubated. After tracheostomy, he was found to have ophthalmoplegia, severe limb rigidity, stimulus-sensitive myoclonus and autonomic dysfunction. For 1 week before admission, there had been a prodromal illness with low mood, hallucinations and limb myoclonus. Serum glycine receptor antibodies were strongly positive: we diagnosed progressive encephalomyelitis with rigidity and myoclonus. Despite a relapse, he has done well following immunotherapies. The clinical syndrome of encephalomyelitis with rigidity, described in 1976, often has a severe progressive course. A minority of patients have glutamic acid decarboxylase antibodies. The association with glycine receptor antibody was first reported in 2008, and we briefly review subsequent case reports to illustrate the range of clinical features. The antibody is likely to be disease mediating, although this remains unproven. The spectrum of diagnosable and treatable antibody mediated neurological syndromes is expanding. It is vital to recognise these conditions early to reduce morbidity and mortality.

Neurite Orientation Dispersion and Density Imaging for Assessing Acute Inflammation and Lesion Evolution in MS.

BACKGROUND AND PURPOSE: MR imaging is essential for MS diagnosis and management, yet it has limitations in assessing axonal damage and remyelination. Gadolinium-based contrast agents add value by pinpointing acute inflammation and blood-brain barrier leakage, but with drawbacks in safety and cost. Neurite orientation dispersion and density imaging (NODDI) assesses microstructural features of neurites contributing to diffusion imaging signals. This approach may resolve the components of MS pathology, overcoming conventional MR imaging limitations. MATERIALS AND METHODS: Twenty-one subjects with MS underwent serial enhanced MRIs (12.6 ± 9 months apart) including NODDI, whose key metrics are the neurite density and orientation dispersion index. Twenty-one age- and sex-matched healthy controls underwent unenhanced MR imaging with the same protocol. Fifty-eight gadolinium-enhancing and non-gadolinium-enhancing lesions were semiautomatically segmented at baseline and follow-up. Normal-appearing WM masks were generated by subtracting lesions and dirty-appearing WM from the whole WM. RESULTS: The orientation dispersion index was higher in gadolinium-enhancing compared with non-gadolinium-enhancing lesions; logistic regression indicated discrimination, with an area under the curve of 0.73. At follow-up, in the 58 previously enhancing lesions, we identified 2 subgroups based on the neurite density index change across time: Type 1 lesions showed increased neurite density values, whereas type 2 lesions showed decreased values. Type 1 lesions showed greater reduction in size with time compared with type 2 lesions. CONCLUSIONS: NODDI is a promising tool with the potential to detect acute MS inflammation. The observed heterogeneity among lesions may correspond to gradients in severity and clinical recovery after the acute phase.

An animal behavior model for studying the actions of LSD and related hallucinogens.

Cats injected with LSD (d-lysergic acid diethylamide) exhibit a group of behaviors that appear to be specific to hallucinogenic drugs. Two of these behaviors, limb flick and abortive grooming, have an extremely low frequency of occurrence in normal cats, but often dominate the behavior of LSD-treated cats. The frequency of occurrence of this group of behaviors is related to the dose of LSD. The behavioral changes are long-lasting following a single injection of LSD, and exhibit tolerance following the repeated administration of LSD. They are not elicited by a variety of control drugs, but are elicited by other indole nucleus hallucinogens. Because the behavioral effects are specific, reliable, easy to score, and quantifiable, they represent an animal model that can be used in studies of the effects of LSD and related hallucinogens.

An Automated Statistical Technique for Counting Distinct Multiple Sclerosis Lesions.

BACKGROUND AND PURPOSE: Lesion load is a common biomarker in multiple sclerosis, yet it has historically shown modest association with clinical outcome. Lesion count, which encapsulates the natural history of lesion formation and is thought to provide complementary information, is difficult to assess in patients with confluent (ie, spatially overlapping) lesions. We introduce a statistical technique for cross-sectionally counting pathologically distinct lesions. MATERIALS AND METHODS: MR imaging was used to assess the probability of a lesion at each location. The texture of this map was quantified using a novel technique, and clusters resembling the center of a lesion were counted. Validity compared with a criterion standard count was demonstrated in 60 subjects observed longitudinally, and reliability was determined using 14 scans of a clinically stable subject acquired at 7 sites. RESULTS: The proposed count and the criterion standard count were highly correlated (r = 0.97, P < .001) and not significantly different (t59 = -.83, P = .41), and the variability of the proposed count across repeat scans was equivalent to that of lesion load. After accounting for lesion load and age, lesion count was negatively associated (t58 = -2.73, P < .01) with the Expanded Disability Status Scale. Average lesion size had a higher association with the Expanded Disability Status Scale (r = 0.35, P < .01) than lesion load (r = 0.10, P = .44) or lesion count (r = -.12, P = .36) alone. CONCLUSIONS: This study introduces a novel technique for counting pathologically distinct lesions using cross-sectional data and demonstrates its ability to recover obscured longitudinal information. The proposed count allows more accurate estimation of lesion size, which correlated more closely with disability scores than either lesion load or lesion count alone.

Volumetric Analysis from a Harmonized Multisite Brain MRI Study of a Single Subject with Multiple Sclerosis.

BACKGROUND AND PURPOSE: MR imaging can be used to measure structural changes in the brains of individuals with multiple sclerosis and is essential for diagnosis, longitudinal monitoring, and therapy evaluation. The North American Imaging in Multiple Sclerosis Cooperative steering committee developed a uniform high-resolution 3T MR imaging protocol relevant to the quantification of cerebral lesions and atrophy and implemented it at 7 sites across the United States. To assess intersite variability in scan data, we imaged a volunteer with relapsing-remitting MS with a scan-rescan at each site. MATERIALS AND METHODS: All imaging was acquired on Siemens scanners (4 Skyra, 2 Tim Trio, and 1 Verio). Expert segmentations were manually obtained for T1-hypointense and T2 (FLAIR) hyperintense lesions. Several automated lesion-detection and whole-brain, cortical, and deep gray matter volumetric pipelines were applied. Statistical analyses were conducted to assess variability across sites, as well as systematic biases in the volumetric measurements that were site-related. RESULTS: Systematic biases due to site differences in expert-traced lesion measurements were significant (P < .01 for both T1 and T2 lesion volumes), with site explaining >90% of the variation (range, 13.0-16.4 mL in T1 and 15.9-20.1 mL in T2) in lesion volumes. Site also explained >80% of the variation in most automated volumetric measurements. Output measures clustered according to scanner models, with similar results from the Skyra versus the other 2 units. CONCLUSIONS: Even in multicenter studies with consistent scanner field strength and manufacturer after protocol harmonization, systematic differences can lead to severe biases in volumetric analyses.

Activity and properties of CTP: cholinephosphate cytidylyltransferase in adult and fetal rat lung.

Cholinephosphate cytidylyltransferase (CTP : cholinephosphate cytidylyltransferase, EC 2.7.7.15) is located in both the microsomal and supernatant fractions of adult lung when the tissue is homogenized in 0.145 M NaCl. The activity is located predominantly in the supernatant fraction in fetal lung. Cholinephosphate cytidylyltransferase in the supernatant from fetal lung is stimulated 4- to 6-fold by the additions of total lung lipid. Serine phosphoglycerides and inositol phosphoglycerides specifically caused stimulation whereas choline phosphoglycerides and ethanolamine phosphoglycerides produced no stimulation. Lysophosphatidylcholine cause some stimulation, but only at high concentrations. A number of detergents were investigated. All produced inhibition except for the ampholytic detergent, miranol H2M which was not inhibitory. None of the detergents produced any stimulation of activity. Cytidylyltransferase activity in fetal lung when assayed in the absence of lipid is about 25% of the adult. The activity when assayed in the presence of lipid is equal or slightly higher than adult levels. The activity, measured without added phospholipid, increases 5- to 6-fold within 12 h after birth, to values higher than in the adult. The activity, measured in the presence of phospholipid, increased almost linearly from -2 day until +1 day. There is an inverse relationship between the concentration of phospholipid in the fetal lung supernatant and the degree of lipid stimulation. Chromatographic experiments with Biogel A 1.5 columns have shown that cytidylyltransferase can exist in two molecular sizes, a small molecular size that requires phospholipid for activity, and a larger molecular weight species which does not require the addition of phospholipid for activity. Fetal lung has a higher proportion of the low molecular weight form than adult lung. The small molecular weight species can be converted to the larger molecular weight form by the addition of phospholipids.

Liposome-mediated delivery of pteridine antifolates to cells in vitro: potency of methotrexate, and its alpha and gamma substituents.

We have examined the growth-inhibitory potency of several pteridines encapsulated in negatively charged liposomes, including methotrexate, methotrexate-gamma-methylamide, methotrexate-gamma-dimethylamide, methotrexate-alpha-aspartate, and a lipophilic methotrexate-phosphatidylethanolamine conjugate. The potency of encapsulated methotrexate is greater than the potency of the free drug for CV1-P cells, but not for other cell lines. The potency of methotrexate-gamma-methylamide and methotrexate-gamma-dimethylamide is only minimally improved by encapsulation. The potency of methotrexate-alpha-aspartate is increased by encapsulation. In addition, the lipophilic methotrexate derivative has demonstrable potency when incorporated in liposomes. We have also examined the potency of several pteridines under conditions where the cells are exposed to the drug for periods shorter than the entire growth assay. Reduction of the exposure time decreases the potency of both encapsulated and free drugs. However, the difference in potency between the encapsulated and free drug is increased, because the potency of the encapsulated drug is affected less. Consequently, encapsulated methotrexate-gamma-aspartate is 300-fold more potent than free drug, if CV1-P cells are exposed to drug for 4 h. Moreover, encapsulated methotrexate is more potent than free methotrexate for growth inhibition of L929 fibroblasts, if the term of exposure is less than 8 h. Potency is least affected by reduction of exposure length for the lipophilic methotrexate derivative.

Relationship of muscle capillary basement membrane thickness and diabetic retinopathy.

We examined the relationship between the thickness of the quadriceps muscle capillary basement membrane and diabetic retinopathy. Basement membrane thickness was measured in two groups of patients with long-standing type II diabetes mellitus. One group of patients (N = 13) had no evidence of diabetic retinopathy on fluorescein angiography, whereas the other (N = 12) had proliferative microvascular disease. All the patients were male, and both groups were of similar ages, duration of diabetes, serum creatinines, and glycemic control as reflected by HbA1 levels. Mean muscle capillary basement membrane width (+/- SE) of the patients with proliferative retinopathy (3346 +/- 262) was significantly greater (P less than .05) than that observed in the patients without retinopathy (2660 +/- 177). The results of this study suggest that there is a relationship between capillary basement membrane thickness in skeletal muscle and the severity of microangiopathy in the eye. However, there was a substantial overlap between the two groups, indicating that for any individual patient the measurement of muscle capillary basement width will probably not be useful in identifying the presence or absence of retinopathy.

Single unit activity in frontal cortex and caudate nucleus of young and old rats.

Spontaneous neuronal activity was recorded extracellularly from isolated single units in frontal neocortex and caudate nucleus of young and aged F344 rats anesthetized with urethane. Average firing rates, mean interspike intervals (ISI) +/- standard deviations, and ISI frequency histograms were computed and analyzed by microprocessor. For frontal cortex cells (N = 226), there was a nonsignificant trend toward slower average discharge rates in the old group. However, a significantly longer mean ISI and proportionally more very slow firing cells (less than 1 Hz) were observed in old rats. A laminar analysis of frontal cortex unit activity in young animals showed average discharge rates to be distributed somewhat evenly throughout the cortical mantle with the exception of the zone 1200-1400 mu beneath brain surface. This depth corresponds approximately to layer V where a 50% increase in mean firing rate in young animals was observed. In aged animals, this increased cell firing in layer V was absent, while mean discharge rates in other laminae remained essentially the same in the young and old rat groups. Caudate nucleus cells (n = 70) showed a significant shift towards fewer fast discharging cells in old rats, with the average firing rate diminished by one-third. Although more brain regions need to be examined in a similar fashion, the consistency of the present results with those previously reported for the brainstem and cerebellum suggests that slower firing rates and longer ISIs are likely to be wide-spread throughout the brains of aged rats.

Etoposide combined with interferon alfa-2b: novel exploitation of established etoposide pharmacokinetics and pharmacodynamics.

PURPOSE: To construct an efficient pilot study design to determine whether interferon alfa-2b modifies the pharmacokinetics and pharmacodynamics of continuous-infusion etoposide. PATIENTS AND METHODS: A two-stage randomized 2 X 2 factorial design was used to evaluate interferon alfa-2b at two doses (2 or 10 MU/m2/day SQ for 3 days) and two schedules (interferon alfa-2b administered before or concurrent with 72-hour continuous-infusion etoposide). Etoposide was administered at 75, 100, or 125 mg/m2/day. In lieu of comparing the experimental arms to an etoposide-alone control arm to determine effect of interferon alfa-2b dose and schedule, a novel analytic approach was used. The effect of interferon alfa-2b on etoposide-induced leukopenia was assessed indirectly by comparison of the observed white blood cell (WBC) nadir to the nadir predicted from an established pharmacodynamic model for single agent etoposide. RESULTS: Based on 29 patients, dose-normalized 24-hour total and estimated free etoposide concentrations did not differ with interferon alfa-2b dose or schedule. Patients treated with interferon alfa-2b before etoposide had, on average a WBC nadir 545 +/- 225 cells microliter lower than that predicted by a pharmacodynamic model for etoposide alone. An optimal nonlinear model for leukopenia was defined by interferon alfa-2b schedule in addition to 24-hour etoposide concentration. CONCLUSION: A novel study design and statistical analysis provided an efficient preliminary evaluation of the combination of interferon alfa-2b with etoposide in a modest number of patients. Exploitation of a previously validated pharmacodynamic model allowed evaluation of interferon alfa-2b effect and eliminated the need for an etoposide-alone control arm. The pharmacokinetics of continuous-infusion etoposide at doses from 75 to 125 mg/m2/day appear to be unchanged by interferon alfa-2b at the doses and schedules tested and the combination appears to be feasible. We hypothesize that leukopenia may be enhanced when interferon alfa-2b is administered before etoposide, especially at a higher dose of interferon alfa-2b.

A double-blind study of bupropion and placebo in depression.

Bupropion HCl, a new nontricyclic antidepressant, produced marked improvement in 49 hospitalized patients with primary depression at doses of 300-600 mg/day. Bupropion resulted in statistically significant differences from placebo as early as day 5, and by the end of the 4-week study 79% (N = 27) of the bupropion patients and 13% (N = 2) of the placebo patients showed much to very much improvement. Bupropion and placebo had similar side effect profiles. Tremor and sweating were reported more often with bupropion and headache, nausea, and tiredness with placebo.

5-Fluoroorotate: a new liposome-dependent cytotoxic agent.

The potency of 5-fluoroorotate for inhibition of L929 or CV1-P cell growth is increased by encapsulation in negatively charged liposomes. The optimal liposome composition is dipalmitoylphosphatidylglycerol: cholesterol, 67:33. Unextruded large unilamellar liposomes are the optimal size for delivery. This compound is the second transport-negative drug which we have found to exhibit liposome-dependent delivery.

Chronic low-dose levodopa therapy in Parkinson's disease: an argument for delaying levodopa therapy.

Levodopa is the most useful drug for treatment of Parkinson's disease today. But after continued use for several years, the effectiveness declines, and the undesirable side effects become more frequent, leading to unsatisfactory control. Once the treatment failure emerges, further management is difficult and often unsuccessful. One alternative for preventing side effects and treatment failure is to use a low dose. We are reporting our 12-year experience on uninterrupted treatment with levodopa, 3 grams (approximate) daily. The improvement was comparable with the best reports on higher dosage, and the side effects were significantly less frequent. The frequency of dyskinesia and on-off phenomena showed a strong correlation with duration of treatment. Psychiatric side effects were more common on treatment, but frequency of dementia did not correlate with duration of therapy. Improvement reached a peak after 6 months and remained statistically significant for 3.5 years. By the end of 5 years, the disability profile in the group was similar to that prior to levodopa treatment. So far, there is no satisfactory method for preventing treatment failure. From our observations, low dosage of levodopa is a desirable alternative, but not the answer to therapeutic failure. We recommend that levodopa use be delayed until the patient has a functional and/or psychological handicap that cannot be satisfactorily controlled with less potent antiparkinsonian agents.

X-ray diffraction studies on the lattice perfection of human bone apatite (Crista iliaca).

The lattice perfection of human bone apatite (iliac crest of 117 individuals aged 0-90 years) was systematically investigated by means of combined X-ray diffraction procedures--profile fitting and line-broadening analysis--correlated with age, sex, type of tissue (corticalis, spongiosa), and position (superior, middle, and inferior) for different crystallographic directions [length axis using reflection (002), basal plane by means of reflections (300), (210), and (310)]. Bone specimens within age group 0-30 were strongly affected by an increased crystallinity in the direction of the c-axis (domain size increasing by 5-7 nm, strain decreasing respectively), whereas in the direction of the a-axis crystallinity decreased significantly (domain size shortening by 5-7 nm, strain increasing respectively) in correlation with some heteroionic substitutions within the apatitic structure. Within age group 30-80 a certain balance seemed to exist between processes of ordering and disordering such that statistically only a slight increase of crystallinity within the basal plane was observed. Age as main fixed effect was highly significant for all investigated parameters. Crystallinity was well correlated with type of tissue (corticalis, spongiosa) in the direction of the length axis of the bone crystallite.

Retinoids and butyrate modulate fibroblast growth and contraction of collagen matrices.

Wound healing in the eye may lead to undesirable sequelae such as proliferative vitreoretinopathy and scarring of glaucoma filtering fistulas. We therefore sought to manipulate in vitro two key wound healing processes--cell proliferation and contraction of extracellular matrices--using vitamin A (VA), retinoic acid (RA), and n-butyrate (BUT). These substances modulate growth and differentiation of normal and neoplastic cells. We examined the effects of these agents on cultured rabbit fibroblast proliferation and contraction of collagen matrices. Dermal fibroblast proliferation was unaffected by VA, stimulated by RA, and inhibited by BUT. Scleral fibroblast proliferation, in contrast, was stimulated by both VA and RA. All three agents mildly inhibited fibroblast contraction of collagen matrices. We conclude that 1) VA, RA, and BUT have differential effects on rabbit fibroblast proliferation; 2) retinoid effects on fibroblast growth vary with the tissue of origin; and 3) VA, RA, and BUT modestly inhibit fibroblast contraction of extracellular matrices. This study suggests that fibroblast-mediated processes in ocular wound healing and cicatricial disease may be differentially modulated by retinoids and BUT.

Ocular cicatricial disease. Drug effects in vitro on cell proliferation, contraction, and viability.

Fluoroorotate, tunicamycin, and actinomycin D exhibit optimal effects on cell contractility if cells are exposed to the drug for 72 hr, followed by 24 hr of exposure during the contractility assay. Under these conditions, fluoroorotate and tunicamycin inhibit contractility at concentrations very similar to those required to inhibit proliferation, and at higher concentrations affect cell viability. In contrast, the concentrations at which actinomycin D inhibits cell contractility and viability are very similar, and the concentration at which it inhibits cell proliferation is much lower. These results suggest that fluoroorotate and tunicamycin inhibit cell contractility by inhibiting membrane protein glycosylation. Actinomycin D, which inhibits RNA synthesis, appears to block cell contractility only by blocking cell viability, and its most potent effect inhibits only cell proliferation. Daunomycin exhibits very similar effects on cell contractility if cells are exposed to drug for 48 or 72 hr prior to the assessment of contractility, and its effects are not appreciably increased by the further inclusion of the drug for 24 hr during the contractility assay. Daunomycin also has appreciable effects on contractility if cells are exposed to the drug only for the 24 hr of the contractility assay. Similar to actinomycin D, daunomycin inhibits cell contractility and viability at similar concentrations, and inhibits cell proliferation at much lower concentrations. Moreover, daunomycin can appreciably inhibit cell viability in 24 hr of exposure. Therefore, daunomycin appears only to block cell contractility by blocking cell viability, and its most potent effect inhibits only cell proliferation.

The effect of mannitol infusion on retinal function and oxygen tension.

Mannitol administered intravenously in rhesus monkeys resulted in a temporary recovery of the visual evoked response (VER) after its decrease due to elevation of the intraocular pressure. Mannitol infusion caused an immediate, albeit transitory, increase in retinal oxygen tension. These changes were independent of the ocular hypotensive effect of mannitol, and we conclude that the drug is a far better agent for the treatment of acute glaucoma than heretofore believed.

Initial observations on the isolated retinal pigment epithelium-choroid of the cat.

An in vitro preparation of a mammalian retinal pigment epithelium (RPE)-choroid was developed, that of the cat, in order to study the RPE in isolation from the neural retina. The purpose of these initial experiments was to evaluate the electrical characteristics of the tissue and the ionic properties of the RPE apical membrane. They were designed so that results would be directly comparable to those previously obtained on a more extensively studied cold-blooded preparation, the bullfrog. The electrical characteristics of the best cat tissues were similar to those routinely obtained in bullfrog, whereas the average cat apical membrane potential was 20 mV more depolarized than that of frog. The apical membrane of cat resembled the frog's in having a large sensitivity to potassium, but it had a relatively smaller sensitivity to bicarbonate and a relatively larger sensitivity to sodium. The cat, like the frog, also had a ouabain-sensitive mechanism on its apical membrane that directly contributed to membrane potential. Two factors contributing to the lower apical membrane potential in cat were the higher potassium concentration of the mammalian salt solution and the sodium conductance of the apical membrane.

Fluoropyrimidine treatment of ocular cicatricial disease.

The authors have studied the antiproliferative and anticontractile effects of fluorouracil, fluorouridine, and fluorodeoxyuridine on rabbit dermal fibroblasts. All three drugs have antiproliferative effects, the order of their efficacy being fluorodeoxyuridine greater than fluorouridine greater than fluorouracil. In contrast, only fluorouridine and fluorouracil have anticontractile effects. Fluorouridine requires less time of exposure and has greater anticontractile effects than fluorouracil. Thymidine eliminates the antiproliferative effects of fluorodeoxyuridine, but has no effect on either the antiproliferative or anticontractile effects of fluorouracil and fluorouridine. These results suggest that the anticontractile effects of the fluoropyrimidines are caused by their incorporation into RNA and not by the inhibition of DNA synthesis. Metabolites of fluorouracil may provide enhanced control of cell proliferation and contractility in the management of ocular disorders such as proliferative vitreoretinopathy and glaucoma.