ELECTRON MICROSCOPIC OBSERVATIONS ON ALLERGIC ENCEPHALOMYELITIS IN THE RABBIT

Allergic encephalomyelitis was produced in rabbits by injection of white matter from bovine brain plus adjuvants. Electron microscopy revealed focal demyelinization in both the spinal roots and cord. The peripheral lesions were characterized by vacuolization of Schwann cytoplasm, destruction of the myelin sheath, and by some appearances suggesting remyelinization. In the cord there was a marked perivascular inflammatory infiltration with focal destruction of the blood-brain barrier as demonstrated by formation of an abnormal interstitial space about capillaries. Mitochondria of oligodendroglia were strikingly swollen whereas those of other cells were morphologically normal. Axons were denuded of their myelin sheaths and the myelin detritus sequestered within gitter cells. Fibrous astrocytic gliosis occurred to some degree. Focal evidences of myelin reformation were noted centrally as well as peripherally. Allergic encephalomyelitis, as a primary demyelinating lesion, is contrasted with Wallerian degeneration in which myelin degeneration is secondary to destruction of the axon.     

Visualization of cytoplasmic diffusion within living myelin sheaths of CNS white matter axons using microinjection of the fluorescent dye Lucifer Yellow

The compactness of myelin allows for efficient insulation defining rapid propagation of action potentials, but also raises questions about how cytoplasmic access to its membranes is achieved, which is critical for physiological activity. Understanding the organization of cytoplasmic ('water') spaces of myelin is also important for diffusion MRI studies of CNS white matter. Using longitudinal slices of mature rat spinal cord, we monitored the diffusion of the water-soluble fluorescent dye Lucifer Yellow injected into individual oligodendrocytes or internodal myelin. We show that living myelin sheaths on CNS axons are fenestrated by a network of diffusionally interconnected cytoplasmic 'pockets' (1.9 ± 0.2 pockets per 10μm sheath length, n=58) that included Schmidt-Lanterman clefts (SLCs) and numerous smaller compartments. 3-D reconstructions of these cytoplasmic networks show that the outer cytoplasmic layer of CNS myelin is cylindrically 'encuffing', which differs from EM studies using fixed tissue. SLCs were found in different 'open states' and remained stable within a 1-2hour observation period. Unlike the peripheral nervous system, where similarly small (<500Da) molecules diffuse along the whole myelin segment within a few minutes, in mature CNS this takes more than one hour. The slower cytoplasmic diffusion in CNS myelin possibly contributes to its known vulnerability to injury and limited capacity for repair. Our findings point to an elaborate cytoplasmic access to compact CNS myelin. These results could be of relevance to MRI studies of CNS white matter and to CNS repair/regeneration strategies.     

Bedaquiline has potential for targeting tuberculosis reservoirs in the central nervous system

Bedaquiline (BDQ) is the first-in-class United States Food and Drug Administration (US FDA) approved anti-tuberculosis (anti-TB) drug, which is a novel diarylquinoline antibiotic that has recently been utilized as an effective adjunct to existing therapies for multidrug-resistant tuberculosis (MDR-TB). BDQ is especially promising due to its novel mechanism of action, activity against drug-sensitive and drug-resistant tuberculosis (TB) in addition to having the potential to shorten treatment duration. Drug delivery to the central nervous system (CNS) is a major concern in TB chemotherapy, especially with the increasing cases of CNS-TB. In this study, we investigated the CNS penetration of BDQ in healthy rodent brain. Male Sprague-Dawley rats (n = 27; 100 ± 20 g) received a single 25 mg kg⁻¹ b.w dose of BDQ via intraperitoneal (i.p.) administration, over a 24 h period. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine whole tissue drug concentrations and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) was utilized to evaluate drug distribution in the brain. BDQ reached peak concentrations (C_max) of 134.97 ng mL⁻¹ in the brain at a T_max of 4 h, which is within the range required for therapeutic efficacy. BDQ was widely distributed in the brain, with a particularly high intensity in the corpus callosum and associated subcortical white matter including the striatal, globus pallidus, corticofugal pathways, ventricular system, basal forebrain region and hippocampal regions. Using MALDI MSI, this study demonstrates that due to BDQ''s distribution in the brain, it has the potential to target TB reservoirs within this organ.

Bedaquiline (BDQ) was administered to healthy Sprague-Dawley rats in order to determine its localisation in the brain using mass spectrometry imaging (MSI). This study shows that BDQ has the potential for targeting TB reservoirs in the CNS.     

Mapping heterogenous anisotropic tissue mechanical properties with transverse isotropic nonlinear inversion MR elastography

The white matter tracts of brain tissue consist of highly-aligned, myelinated fibers; white matter is structurally anisotropic and is expected to exhibit anisotropic mechanical behavior. In vivo mechanical properties of tissue can be imaged using magnetic resonance elastography (MRE). MRE can detect and monitor natural and disease processes that affect tissue structure; however, most MRE inversion algorithms assume locally homogenous properties and/or isotropic behavior, which can cause artifacts in white matter regions. A heterogeneous, model-based transverse isotropic implementation of a subzone-based nonlinear inversion (TI-NLI) is demonstrated. TI-NLI reconstructs accurate maps of the shear modulus, damping ratio, shear anisotropy, and tensile anisotropy of in vivo brain tissue using standard MRE motion measurements and fiber directions estimated from diffusion tensor imaging (DTI). TI-NLI accuracy was investigated with using synthetic data in both controlled and realistic settings: excellent quantitative and spatial accuracy was observed and cross-talk between estimated parameters was minimal. Ten repeated, in vivo, MRE scans acquired from a healthy subject were co-registered to demonstrate repeatability of the technique. Good resolution of anatomical structures and bilateral symmetry were evident in MRE images of all mechanical property types. Repeatability was similar to isotropic MRE methods and well within the limits required for clinical success. TI-NLI MRE is a promising new technique for clinical research into anisotropic tissues such as the brain and muscle.     

Multiple white matter tract abnormalities underlie cognitive impairment in RRMS

Diffusion tensor imaging (DTI) is a sensitive tool for detecting microstructural tissue damage in vivo. In this study, we investigated DTI abnormalities in individuals with relapsing remitting multiple sclerosis (RRMS) and examined the relations between imaging-based measures of white matter injury and cognitive impairment. DTI-derived metrics using tract-based spatial statistics (TBSS) were compared between 37 individuals with RRMS and 20 healthy controls. Cognitive impairment was assessed with three standard tests: the Symbol Digit Modalities Test (SDMT), which measures cognitive processing speed and visual working memory, the Rey Auditory Verbal Learning Test (RAVLT), which examines verbal memory, and the Paced Auditory Serial Addition Test (PASAT), which assesses sustained attention and working memory. Correlations between DTI-metrics and cognition were explored in regions demonstrating significant differences between the RRMS patients and the control group. Lower fractional anisotropy (FA) was found in RRMS participants compared to controls across the tract skeleton (0.40 ± 0.03 vs. 0.43 ± 0.01, p < 0.01). In areas of reduced FA, mean diffusivity was increased and was dominated by increased radial diffusivity with no significant change in axial diffusivity, an indication of the role of damage to CNS myelin in MS pathology. In the RRMS group, voxelwise correlations were found between FA reduction and cognitive impairment in cognitively-relevant tracts, predominantly in the posterior thalamic radiation, the sagittal stratum, and the corpus callosum; the strongest correlations were with SDMT measures, with contributions to these associations from both lesion and normal-appearing white matter. Moreover, results using threshold-free cluster enhancement (TFCE) showed more widespread white matter involvement compared to cluster-based thresholding. These findings indicate the important role for DTI in delineating mechanisms underlying MS-associated cognitive impairment and suggest that DTI could play a critical role in monitoring the clinical and cognitive effects of the disease.     

ADJUVANTS IN IMMUNIZATION WITH INFLUENZA VIRUS VACCINES

Subcutaneous inoculation, of PR8 allantoic fluid, or watery suspensions of the virus obtained from allantoic fluid by high-speed centrifugation or by elution after adsorption on red cells induced serum antibodies in experimental animals, which reached the highest levels within 2 weeks after inoculation and were gradually lost thereafter. The addition of killed acid-fast bacteria (Myco. tuberculosis or butyricum), paraffin oil, and a proprietary adsorption base (Falba) to form a stable water-in-oil emulsion of influenza virus suspensions greatly enhanced and maintained immunity and antibody response to the virus. These adjuvants provided a much more effective method of increasing antibody production to the virus than the use of concentrated preparations of virus alone. Paraffin oil and Falba without the acid-fast bacilli were less effective as adjuvants, although the antibody levels induced were higher than those produced by watery suspensions of the virus and were maintained at a constant level for at least 6 months. Myco. butyricum appeared to be more effective in producing antibodies against the virus than the tubercle bacilli in the emulsions of paraffin oil and Falba. Immunization with these adjuvants and suspensions of influenza virus obtained from allantoic fluid induced antibodies not only against the virus but against antigenic material contained in normal allantoic fluid, although the latter titers were considerably lower. A suspension of influenza virus (sedimented by high-speed centrifugation) and Myco. butyricum in sesame oil induced about four times as much antibody as when the virus was suspended in saline, in sesame oil alone, or in combination with typhoid bacilli.     

探索高原登山的脑结构改变

目的 探讨一次短暂高原登山引起的脑结构改变.方法 对15名厦门大学学生登山队员[男9名,女6名,19~23岁,平均(21.0±1.1)岁]分别于攀登珠穆朗玛峰前、后进行常规T2W及高分辨率全脑3DT1W结构成像;应用SIENA软件分别对登山前、后高分辨率3DT1W结构像进行全脑灰质、白质分割,计算体积萎缩百分率,并进行统计分析;对全脑进行基于体素的纵向脑萎缩评价,获取显著萎缩脑区.结果 视觉观察,登山前、后所有登山队员常规T2WI均未发现异常,但脑灰质及白质体积均有明显减少,脑灰质萎缩百分率为(2.70±1.43)%,白质萎缩百分率为(1.43±1.36)%,差异有统计学意义(P<0.01);基于体素的全脑统计分析发现,萎缩脑区包括左侧额叶、胼胝体压部、双侧颞极、双侧枕叶距状沟周围及双侧小脑半球,以优势半球受损明显.结论 高原登山运动可引起脑白质和灰质萎缩,且灰质萎缩更明显.     

Identification of lymphotoxin and tumor necrosis factor in multiple sclerosis lesions.

Multiple sclerosis (MS) brain tissue, spleen, and PBMC were studied using immunocytochemistry and FACS for immunoreactivity for lymphotoxin (LT) and TNF. Both cytokines were identified in acute and chronic active MS lesions but were absent from chronic silent lesions. LT was associated with CD3+ lymphocytes and Leu-M5+ microglia cells at the lesion edge and to a lesser extent, in adjacent white matter. TNF was associated with astrocytes in all areas of the lesion, and with foamy macrophages in the center of the active lesion. In acute lesions, immunoreactivity for TNF in endothelial cells was noted at the lesion edge. No LT or TNF reactivity was detected in Alzheimer's or Parkinson's disease brain tissues but was present at lower levels in central nervous system (CNS) tissue from other inflammatory conditions, except for adrenoleucodystrophy which displayed high levels of LT in microglia. No increase in LT and TNF reactivity was detected in spleen and PBMC of MS patients suggesting specific reactivity within the CNS. These results indicate that LT and TNF may be involved in the immunopathogenesis of MS, and can be detected in both inflammatory cells and cells endogenous to the CNS.     

Estradiol treatment altered anticholinergic-related brain activation during working memory in postmenopausal women

Diffusion MRI is used extensively to investigate changes in white matter microstructure related to brain development and pathology. Ageing, however, is also associated with significant white and grey matter loss which in turn can lead to cerebrospinal fluid (CSF) based partial volume artefacts in diffusion MRI metrics. This is especially problematic in regions prone to CSF contamination, such as the fornix and the genu of corpus callosum, structures that pass through or close to the ventricles respectively. The aim of this study was to model the effects of CSF contamination on diffusion MRI metrics, and to evaluate different post-acquisition strategies to correct for CSF-contamination: Controlling for whole brain volume and correcting on a voxel-wise basis using the Free Water Elimination (FWE) approach. Using the fornix as an exemplar of a structure prone to CSF-contamination, corrections were applied to tract-specific and voxel-based [tract based spatial statistics (TBSS)] analyses of empirical DT-MRI data from 39 older adults (53-93 years of age). In addition to significant age-related decreases in whole brain volume and fornix tissue volume fraction, age was also associated with a reduction in mean fractional anisotropy and increase in diffusivity metrics in the fornix. The experimental data agreed with the simulations in that diffusivity metrics (mean diffusivity, axial and radial diffusivity) were more prone to partial volume CSF-contamination errors than fractional anisotropy. After FWE-based voxel-by-voxel partial volume corrections, the significant positive correlations between age and diffusivity metrics, in particular with axial diffusivity, disappeared whereas the correlation with anisotropy remained. In contrast, correcting for whole brain volume had little effect in removing these spurious correlations. Our study highlights the importance of correcting for CSF-contamination partial volume effects in the structures of interest on a voxel-by-voxel basis prior to drawing inferences about underlying changes in white matter structures and have implications for the interpretation of many recent diffusion MRI results in ageing and disease.     

Modifications of brain tissue volumes in facioscapulohumeral dystrophy

Facioscapulohumeral muscular dystrophy (FSHD), a pathology primarily characterized by involvement of the muscles in the face, shoulder and upper arm, can be associated to several CNS disorders, including sensorineural hearing deficits, schizophrenia, epilepsy and mental retardation. Aim of our study was to verify if brain tissue volumes, as measured by segmentation of MRI studies, are altered in FSHD. Volumes of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were compared, taking into account head size age and sex, both globally (by multiple regression analysis) and regionally (by optimized voxel-based morphometry-VBM) in thirty patients with FSHD and 39 normal subjects (NS). FSHD patients had significantly lower GM volumes and higher CSF volumes (P < 10(-4)). GM loss showed a borderline correlation with clinical severity (P < 0.05). Brain tissue volumes did not correlate with disease duration, size of the genetic deletion, age at onset and the presence at MRI of WM hyperintensities (detected in 4/22 patients). At VBM three clusters of GM loss were detected, in the left precentral cortex (Brodmann areas 6, 2 and 44, P < 10(-14) corrected for multiple comparisons at cluster level), in the anterior cingulate (Brodmann areas 33, 24 and 11, P < 10(-4)) and in the right fronto-polar region (Brodmann area 10, P < 5.10(-3)). To the best of our knowledge, this is the first study to demonstrate a reduction in GM volume in FSHD. We hypothesize that localized GM loss in FSHD is the consequence of a selective involvement of specific CNS structures.     

Astrocytes are central in the pathomechanisms of vanishing white matter

Vanishing white matter (VWM) is a fatal leukodystrophy that is caused by mutations in genes encoding subunits of eukaryotic translation initiation factor 2B (eIF2B). Disease onset and severity are codetermined by genotype. White matter astrocytes and oligodendrocytes are almost exclusively affected; however, the mechanisms of VWM development remain unclear. Here, we used VWM mouse models, patients’ tissue, and cell cultures to investigate whether astrocytes or oligodendrocytes are the primary affected cell type. We generated 2 mouse models with mutations (Eif2b5^{Arg191His/Arg191His} and Eif2b4^{Arg484Trp/Arg484Trp}) that cause severe VWM in humans and then crossed these strains to develop mice with various mutation combinations. Phenotypic severity was highly variable and dependent on genotype, reproducing the clinical spectrum of human VWM. In all mutant strains, impaired maturation of white matter astrocytes preceded onset and paralleled disease severity and progression. Bergmann glia and retinal Müller cells, nonforebrain astrocytes that have not been associated with VWM, were also affected, and involvement of these cells was confirmed in VWM patients. In coculture, VWM astrocytes secreted factors that inhibited oligodendrocyte maturation, whereas WT astrocytes allowed normal maturation of VWM oligodendrocytes. These studies demonstrate that astrocytes are central in VWM pathomechanisms and constitute potential therapeutic targets. Importantly, astrocytes should also be considered in the pathophysiology of other white matter disorders.     

Insulin-like growth factor delivery across the blood-brain barrier. Potential use of IGF-1 as a drug in child neurology

BACKGROUND: Recent data indicate that insulin-like growth factor-1 (IGF-1) can cross the blood-brain barrier when bound to binding proteins. IGF-1 is very important for early brain development, myelination and survival of cerebellar neurons. It is antiapoptotic and is important for synaptic development. The aim of this study was to identify neurological conditions with low CNS IGF-1. METHODS: Levels of CSF IGF-1 were determined by radio-immunoassay (Mediagnost, Tubingen, Germany). RESULTS: Levels of CSF IGF-1 were low in some progressive diseases of white matter and the cerebellum. In some other diseases not involving cerebellum or white matter, CSF IGF-1 was normal. CONCLUSIONS: Our findings might pave the way for rational therapy in patients with neurodegeneration. Patients with low CNS IGF-1 might be candidates for IGF-1 therapy.     

A sobering addition to the literature on COVID-19 and the brain

Several coronavirus disease 2019 (COVID-19) studies have focused on neuropathology. In this issue of the JCI, Qin, Wu, and Chen et al. focused specifically on people whose acute infection lacked obvious neurological involvement. Severely infected patients showed abnormal gray matter volumes, white matter diffusion, and cerebral blood flow compared with healthy controls and those with mild infection. The data remain associative rather than mechanistic, but correlations with systemic immune markers suggest effects of inflammation, hypercoagulation, or other aspects of disease severity. Mechanistic research is warranted. Given the lack of obvious neurological symptoms, neurocognitive assessments were not performed, but the findings suggest that such assessments may be warranted in severely affected patients, even without obvious symptoms. Further, studying CNS involvement of other disorders with overlapping pathophysiologies such as inflammation, coagulation, hypoxia, or direct viral infection may reveal the causes for COVID-19–related neuropathology.     

White matter lesion extension to automatic brain tissue segmentation on MRI

A fully automated brain tissue segmentation method is optimized and extended with white matter lesion segmentation. Cerebrospinal fluid (CSF), gray matter (GM) and white matter (WM) are segmented by an atlas-based k-nearest neighbor classifier on multi-modal magnetic resonance imaging data. This classifier is trained by registering brain atlases to the subject. The resulting GM segmentation is used to automatically find a white matter lesion (WML) threshold in a fluid-attenuated inversion recovery scan. False positive lesions are removed by ensuring that the lesions are within the white matter. The method was visually validated on a set of 209 subjects. No segmentation errors were found in 98% of the brain tissue segmentations and 97% of the WML segmentations. A quantitative evaluation using manual segmentations was performed on a subset of 6 subjects for CSF, GM and WM segmentation and an additional 14 for the WML segmentations. The results indicated that the automatic segmentation accuracy is close to the interobserver variability of manual segmentations.     

扩散张量成像观察先天性耳聋患者脑白质结构

目的 利用扩散张量成像(DTI)研究先天性耳聋(CD)患者的脑白质结构,探讨脑白质变化机制.方法 对6名先天性耳聋患者和6名正常人进行脑部DTI扫描,应用基于体素的分析(VBA)对CD组和正常对照(HC)组的全脑分数各向异性(FA)值进行比较,计算样本感兴趣区(ROI)Brodmann(BA)41、BA22和BA44区的平均FA值.结果 CD组FA值显著减少的区域位于右脑的颞上回(STG), ROI平均FA值除在右脑BA22区有下降的趋势外,未发现显著异常;CD组和HC组中左脑ROI的平均FA值显著偏大.结论 先天性耳聋患者右脑STG白质损伤,这种结构异常是由其先天缺乏声音刺激所造成的.     

A novel CNS-homing peptide for targeting neuroinflammatory lesions in experimental autoimmune encephalomyelitis

Using phage peptide library screening, we identified peptide-encoding phages that selectively home to the inflamed central nervous system (CNS) of mice with experimental autoimmune encephalomyelitis (EAE), a model of human multiple sclerosis (MS). A phage peptide display library encoding cyclic 9-amino-acid random peptides was first screened ex-vivo for binding to the CNS tissue of EAE mice, followed by in vivo screening in the diseased mice. Phage insert sequences that were present at a higher frequency in the CNS of EAE mice than in the normal (control) mice were identified by DNA sequencing. One of the phages selected in this manner, denoted as MS-1, was shown to selectively recognize CNS tissue in EAE mice. Individually cloned phages with this insert preferentially homed to EAE CNS after an intravenous injection. Similarly, systemically-administered fluorescence-labeled synthetic MS-1 peptide showed selective accumulation in the spinal cord of EAE mice. We suggest that peptide MS-1 might be useful for targeted drug delivery to CNS in EAE/MS.     

Cerebrovascular dysfunction and microcirculation rarefaction precede white matter lesions in a mouse genetic model of cerebral ischemic small vessel disease

Cerebral ischemic small vessel disease (SVD) is the leading cause of vascular dementia and a major contributor to stroke in humans. Dominant mutations in NOTCH3 cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetic archetype of cerebral ischemic SVD. Progress toward understanding the pathogenesis of this disease and developing effective therapies has been hampered by the lack of a good animal model. Here, we report the development of a mouse model for CADASIL via the introduction of a CADASIL-causing Notch3 point mutation into a large P1-derived artificial chromosome (PAC). In vivo expression of the mutated PAC transgene in the mouse reproduced the endogenous Notch3 expression pattern and main pathological features of CADASIL, including Notch3 extracellular domain aggregates and granular osmiophilic material (GOM) deposits in brain vessels, progressive white matter damage, and reduced cerebral blood flow. Mutant mice displayed attenuated myogenic responses and reduced caliber of brain arteries as well as impaired cerebrovascular autoregulation and functional hyperemia. Further, we identified a substantial reduction of white matter capillary density. These neuropathological changes occurred in the absence of either histologically detectable alterations in cerebral artery structure or blood-brain barrier breakdown. These studies provide in vivo evidence for cerebrovascular dysfunction and microcirculatory failure as key contributors to hypoperfusion and white matter damage in this genetic model of ischemic SVD.     

Automatic segmentation of MR images of the developing newborn brain

This paper describes an automatic tissue segmentation method for newborn brains from magnetic resonance images (MRI). The analysis and study of newborn brain MRI is of great interest due to its potential for studying early growth patterns and morphological changes in neurodevelopmental disorders. Automatic segmentation of newborn MRI is a challenging task mainly due to the low intensity contrast and the growth process of the white matter tissue. Newborn white matter tissue undergoes a rapid myelination process, where the nerves are covered in myelin sheathes. It is necessary to identify the white matter tissue as myelinated or non-myelinated regions. The degree of myelination is a fractional voxel property that represents regional changes of white matter as a function of age. Our method makes use of a registered probabilistic brain atlas. The method first uses robust graph clustering and parameter estimation to find the initial intensity distributions. The distribution estimates are then used together with the spatial priors to perform bias correction. Finally, the method refines the segmentation using training sample pruning and non-parametric kernel density estimation. Our results demonstrate that the method is able to segment the brain tissue and identify myelinated and non-myelinated white matter regions.     

THE CULTIVATION OF THE LEPROSY BACILLUS AND THE EXPERIMENTAL PRODUCTION OF LEPROSY IN THE JAPANESE DANCING MOUSE

Pure cultures of an acid-fast bacillus were cultivated upon special media from the human tissues in four cases of leprosy. The nature of the growth, morphological characters and tinctorial properties do not differ for any of the cultures and correspond closely to the bacilli in the human leprous tubercles. That the bacillus of leprosy will multiply and continue to do so indefinitely outside of the animal body was first demonstrated by Clegg who cultivated an acid-fast organism from leprosy tissue in the presence of ameba and their symbiotics. Not only have I been able to confirm Clegg''s work, but in addition I have succeeded in growing the bacillus in pure culture and in reproducing the disease in the Japanese dancing mouse, thereby establishing its identity. This species of animal acquires the infection in four to six weeks after intraperitoneal or subcutaneous inoculation with either emulsions of fresh leprous tissue or the pure cultures of B. lepræ. Comparatively few bacilli are necessary to infect the mouse; and the mode of inoculation does not seem to make any appreciable difference in respect to the nature and time of development of the lesion. The experimental lesions are proliferative in character and identical with those in the human subject. Macroscopically they appear as glistening, white nodules which, in the early stages of development, resemble miliary tubercles. In my experience neither the cultures nor the bacilli directly from the human tissues have shown any evidence of multiplication or given rise to lesions when injected into the ordinary laboratory animals such as guinea pigs, rabbits, gray and white mice and rats, although repeated attempts have been made to infect these animals. B. lepræ will not only multiply but it will colonize on a plain agar medium seeded with a pure culture of encysted ameba (Plate LVIII, Fig. 5), and upon an agar or banana medium prepared with a I per cent. solution of cystein and tryptophane. Colonization occurs in the form of glistening, white colonies, one to two millimeters in diameter, in from one to two months incubation. The bacilli in cultures are at all times acid-fast and differ only in morphology from those of the tissues in that they exhibit a greater variation in the distribution of the chromatin and are longer and more distinctly curved. To prove that the cultures obtained from the human tissues of these four cases are leprosy bacilli and not some other acid-fast species, the following facts are offered: (1) the growth features are distinctive and multiplication takes place only under special conditions of temperature and medium; (2) the complete correspondence in tinctorial properties and similarity in morphology to those in the tissues; (3) the failure to multiply or produce lesions in the common laboratory animals; and (4) the growth of the bacilli and the production of typical leprous lesions in the Japanese dancing mouse. The successful cultivation of B. lepræ and the fact that the cultures retain pathogenic properties are of commanding importance in respect to a possible production of an artificial immune serum for combating the infection in man. Work along this interesting line is already in progress in our laboratories.     

White Matter Involvement in Chronic Musculoskeletal Pain

There is emerging evidence that chronic musculoskeletal pain is associated with anatomic and functional abnormalities in gray matter. However, little research has investigated the relationship between chronic musculoskeletal pain and white matter. In this study, we used whole-brain tract-based spatial statistics and region-of-interest analyses of diffusion tensor imaging data to demonstrate that patients with chronic musculoskeletal pain exhibit several abnormal metrics of white matter integrity compared with healthy controls. Chronic musculoskeletal pain was associated with lower fractional anisotropy in the splenium of the corpus callosum and the left cingulum adjacent to the hippocampus. Patients also had higher radial diffusivity in the splenium, right anterior and posterior limbs of the internal capsule, external capsule, superior longitudinal fasciculus, and cerebral peduncle. Patterns of axial diffusivity (AD) varied: patients exhibited lower AD in the left cingulum adjacent to the hippocampus and higher AD in the anterior limbs of the internal capsule and in the right cerebral peduncle. Several correlations between diffusion metrics and clinical variables were also significant at a P < .01 level: fractional anisotropy in the left uncinate fasciculus correlated positively with total pain experience and typical levels of pain severity. AD in the left anterior limb of the internal capsule and left uncinate fasciculus was correlated with total pain experience and typical pain level. Positive correlations were also found between AD in the right uncinate and both total pain experience and pain catastrophizing. These results demonstrate that white matter abnormalities play a role in chronic musculoskeletal pain as a cause, a predisposing factor, a consequence, or a compensatory adaptation.PerspectivePatients with chronic musculoskeletal pain exhibit altered metrics of diffusion in the brain's white matter compared with healthy volunteers, and some of these differences are directly related to symptom severity.