Small Brain Vessels Research Articles

A Rare Mutation Associated with Cerebral Arteriopathy with Subcortical Infarct and Leukoencephalopathy (CADASIL) (P2-5.002)

<h3>Objective:</h3> To report a rare cause of CADASIL with a point mutation in exon 5 of NOTCH 3 gene causing a non-cysteine change and its implication. <h3>Background:</h3> CADASIL is a rare genetic non-amyloid arteriopathy primarily affecting small brain vessels. Its prevalence in population is 2 to 5/100,000, but may be underestimated and underdiagnosed. Although there is over 200 different NOTCH-3 mutations described worldwide, 95% of them are missense mutation in the exons 2–24, which leads to a gain or loss of a cysteine residue in one of 34 epidermal growth factor-like repeat (EGFr) domains of the NOTCH3 protein. Non-cysteine mutations are rare and their role is not well determined. <h3>Design/Methods:</h3> Case report <h3>Results:</h3> 58-year-old man with a three-year progressive cognitive decline, history of headaches, fatigue, and generalized weakness was admitted to the neurology wards for worsening weakness and increased need for assistance in daily life. Neurological exam was significant for mild left hemiparesis. MoCA score was 19/30. Brain MRI showed one subacute and numerous chronic lacunar ischemic strokes including in the corpus callosum, also seen on previous outpatient MRIs. These changes had been attributed to demyelinating disease by the outpatient physician. An extensive workup including autoimmune was unrevealing. Classical leukoencephalopathy was not present, but hyperintensities in the temporal lobe raised concern for CADASIL. DNA sequencing revealed a non-cysteine mutation with c.754 G&gt;A transition in exon 5 of NOTCH 3 gene resulting in a substitution of Valine to Methionine (V252M). This is the second case of this mutation reported in the literature. Non-cysteine mutation may affect NOTCH-3 signaling output and possibly lead to a milder leukoencephalopathy and extensive involvement of corpus callosum with lacunar infarctions resembling demyelinating disease. <h3>Conclusions:</h3> CADASIL with a point mutation in exon 5 of NOTCH 3 gene causing a non-cysteine change may present with milder disease and not classical MRI changes. <b>Disclosure:</b> Dr. Delpirou Nouh has nothing to disclose. Dr. Mahmoud has nothing to disclose. Juliane Chainakul has nothing to disclose. Robert Hamilton has nothing to disclose. Dr. Sidorov has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Allergan. Dr. Sidorov has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for BioHaven .

Small vessels in the brain and heart: How similar are they?

AbstractBackgroundIn the brain and heart alike blood vessels are end arteries and their occlusion results in anaemic infarct with high mortality and severe morbidity in a high proportion of survivors. The role of collateral circulation and early recanalization is crucial in both contexts. Ischaemic preconditioning, reperfusion injury and haemorrhagic transformation are three key pathophysiological processes in both organs and the morphological and molecular processes at the level of microcirculation are fundamental to understand and therapeutically modulate the effects of ischaemia.MethodThe morphology of small vessels in brain and heart are compared based on published literature and pathologically assessed cases. The similarities and differences are related to the morphological and molecular consequences of hypoperfusion and vascular occlusion at the level of small vessels and microcirculation. In a case series, we retrospectively analysed the clinical data of 158 patients in a regional centre for acute stroke care. For clinico‐pathological analysis 98 cases (age 62±6.5y) were suitable.ResultAlthough small vessels and the microcirculation share morphological and molecular similarities in health and in response to ischaemic challenge, the specific and unique features of the blood‐brain barrier and the neurovascular unit in the brain are major differences, with implications for drug transfer to the ischaemic parenchyma. Haemorrhagic transformation accelerates the secondary progression of stroke and indicates higher risk of adverse outcome. Neurodegenerative changes impair the microcirculation and, vice versa, microcirculatory damage and dysfunction may trigger and accelerate the neurodegenerative cascade. Vascular and neurodegenerative mechanisms in dementia usually coexist. The morphological patterns of infarct evolution and healing are rather different in the brain and the heart, which also applies to the characteristics of the inflammatory cell composition.ConclusionOur findings underline the importance of post‐mortem pathological examination in the era of advanced imaging and laboratory diagnostic techniques. The fundamental differences in the histomorphology and in the sequence of cellular and molecular events during ischaemia and reperfusion in brain and heart indicate that adaptations of findings in cardiology and clinical neuroscience should be made with caution.

Carasil and htra1: an early adulthood syndrome

Cerebral Autosomal Recessive Arteriopathy Subcortical Infracts Leukoencephalopathy (CARASIL), is an autosomal recessive disorder inherited by two copies of an abnormal gene from some trait, one from each parent. Person with this disorder may have a change in deep white matter in brain; and this disorder can be characterized by damage to small blood vessels in brain. Increasing muscle tone, slurred speech, stiff movement of legs, gait disturbance, spondylosis, sparse hair are the major symptoms. But the ultimate cause of this disorder can lead to loss of memory, cognitive impairment. This disorder can be caused in early adulthood i.e., between 20-40 years of age. CARASIL has first reported in Japan, later occurred in China and Caucasian population. A neurological disorder named Binswanger’s disease (BD) and chronic immunological disorder multiple sclerosis are main different alternation of this disease. Mutation requires the high temperature resultant, A serine peptidase 1 causes CARASIL, so it is a serine protease.&#x0D; Serine protease HTRA1 is an enzyme that in humans is encoded by HTRA1 gene. HTRA1 protein is composed of four distinct protein domains. This is located on the long (q) arm of chromosome 10 in a region known as 10q26. This protein is a secreted enzyme that is proposed to regulate the availability of insulin like growth factors (IGF) by cleaving IGF binding proteins. HTRA1 enzyme helps breakdown many other kinds of proteins in this space surrounding cells (extracellular matrix). This is attached to protein in Transforming Growth Factor Beta (TGF-beta) and slows down their ability to send chemical signals. Variant known as rs11200638 is found in an area of gene called promoter region which starts the production HTRA1 enzyme. It is unclear how of polymorphism in the HTRA1 gene might be an age-related macular degeneration.&#x0D; So at last, we can conclude that CARASIL is related to brain inherited from the abnormal genes caused to small arteries and to the specific area of deep brain in higher function; tissue loss due to lack of oxygen where small arteries get blocked destruction to myelin an oily substance covers and protects the nerve fibers in CNS.

A multimodal approach in the treatment of chronic cerebral ischemia: what should a doctor know?

The article discusses one of the leading problems of modern angioneurology - chronic cerebral ischemia. The main etiological factors playing a significant role in the development of chronic cerebral ischemia, among which atherosclerosis, hypertension, myocardial diseases, diabetes mellitus, etc. play a major role. The main clinical manifestations of this disease are described. The emphasis is on the fact that the main nucleus of the clinical picture of chronic cerebral ischemia is cognitive impairment, which in most cases determines the severity of patients. The development of cognitive impairment is associated with focal or diffuse brain lesions, resulting in the impairment of one or more cognitive functions. Vascular cognitive deficits are the result of acute or chronic cerebrovascular processes. The main causes and mechanisms of vascular cognitive impairment development are presented. It is shown that depending on the mechanism and the cause, the rate of cognitive impairment development may vary. The clinical picture of cognitive impairments developing as a result of the lesion of small brain vessels is described. The peculiarities of vascular cognitive disorders occurring against the background of cerebral hypoperfusion are described. The modern criteria of diagnosis are given. The main diagnostic methods are listed. The main approaches in treatment of patients with chronic cerebral ischemia depending on the disease stage are described. In-depth attention is given to neuroprotection with a more detailed description of the mechanisms of action and clinical efficacy of drugs with active substances - citicoline and ethylmethylhydroxypyridine succinate.

Церебральная микроангиопатия (болезнь мелких сосудов) и возрастной гипогонадизм у мужчин

The review discusses the contribution of age-related male hypogonadism to the formation of cerebral microangiopathy (disease of small brain vessels) (CMA/SVD). The current explanation of the nature of CMA by an ischemic-hypoxic process, which is based on hypo- or hyperperfusion of the white matter of brain due to a complex of various causes, does not explain the etiopathogenesis of CMA. The article considers a violation of the neuroglyovascular connection, represented by a vessel, astrocytic glia, and a neuron, as the cause of SVD development. The main role in the CMA formation is assigned to endothelial dysfunction, all variants of which (vasomotor, thrombophilic, adhesive, angiogenic) can be traced in SVD. The role of disorders of the main functions of arterial vessels — conducting and damping, as well as liquorodynamics disorders in the CMA pathogenesis is discussed. The data indicating the involvement of testosterone and its derivatives in the formation of cerebral vascular pathology are presented. It is emphasized that this participation can be of one kind in men with early physiological uncomplicated hypogonadism, when the hypothalamic-pituitary system is involved in the process, and of another kind in complicated or late climax. At that, an increase in the production of gonadotropin — releasing hormone (GnRH), the content of FSH and LH in peripheral blood is considered as a reaction to an age-related decrease in androgen function, and the vegetative dysfunction, metabolic and other disorders inherent in this period of life – as a result of changes in the functioning of the entire hypothalamus-pituitary-testicular axis. In complicated age-related hypogonadism, the resulting endocrine or somatic pathology is included in the process of small vessel disease formation. In late hypogonadism, the androgen function fades, and the hypothalamic-pituitary system begins to function in a different mode. Often, the clinic and mechanism of CMA formation are determined by diseases inherent in old age. The differences in the pathogenetic mechanisms of CMA development at various periods of IgG determine the need for a differentiated approach to the preventive means and methods of CMA therapy in men of the involutional period. The presented information may be useful for better understanding of CMA development in individuals with age-related hypogonadism.

Analysis of dynamic texture and spatial spectral descriptors of dynamic contrast-enhanced brain magnetic resonance images for studying small vessel disease

Cerebral small vessel disease (SVD) comprises various pathological processes affecting small brain vessels and damaging white and grey matter. In this paper, we propose a framework comprising region of interest sampling, dynamic spectral and texture description, functional principal component analysis, and statistical analysis to study exogenous contrast agent distribution over time in various brain regions in patients with recent mild stroke and SVD features.We compared our results against current semi-quantitative surrogates of dysfunction such as signal enhancement area and slope. Biological sex, stroke lesion type and overall burden of white matter hyperintensities (WMH) were significant predictors of intensity, spectral, and texture features extracted from the ventricular region (p-value < 0.05), explaining between a fifth and a fourth of the data variance (0.20 ≤Adj.R2 ≤ 0.25). We observed that spectral feature reflected more the dysfunction compared to other descriptors since the overall WMH burden explained consistently the power spectra variability in blood vessels, cerebrospinal fluid, deep grey matter and white matter. Our preliminary results show the potential of the framework for the analysis of dynamic contrast-enhanced brain magnetic resonance imaging acquisitions in SVD since significant variation in our metrics was related to the burden of SVD features. Therefore, our proposal may increase sensitivity to detect subtle features of small vessel dysfunction. A public version of the code will be released on our research website.

МІАСТЕНІЯ – ТРУДНОЩІ ДІАГНОСТИКИ ТА ЛІКУВАННЯ (РОЗБІР КЛІНІЧНОГО ВИПАДКУ)

Myasthenia gravis is an autoimmune rapidly progressive disease characterized by a neuromuscular disorder due to the formation of autoantibodies to different epitopes of the peripheral neuromuscular device and is clinically manifested by pathological muscle fatigue and weakness. Diagnosis of myasthenia in the elderly is very problematic because doctors regard muscle weakness at this age as a symptom of other diseases. In addition, it may be combined with various pathological conditions. The article describes the presence of comorbid states in patients with myasthenia who were treated at the neurological department of Lviv regional clinical hospital in 2016-2018. 58% of patients with myasthenia, mainly older people, had comorbid diseases. Hypertensive heart disease (34%), ischemic heart disease (20%), diabetes mellitus (12%,) and small brain vessels disease (8%) were frequently observed. A case of late diagnosed generalized myasthenia in a 66-year-old woman with concomitant small vessels disease of the brain and diabetes mellitus is described. The patient was treated at the neurological department of Lviv regional clinical hospital in December 2018. For a long time, the patient had been treated of the small vessels disease, though main complaints were difficulties with speaking, swallowing, periodic double vision, ptosis, general weakness, weakness in the right leg, memory impairment, problems with walking and urination. The diagnosis of myasthenia was based on clinical manifestations, a positive reaction to acetylcholinesterase inhibitors, and detection of antibodies to acetylcholine receptors. Clinical manifestations of myasthenia, as well as apraxia of walking, disorders of urination and cognitive impairment due to vascular changes in the brain intensified the patient's disability and created the need for careful outside care and control of the drug intake. The positive influence of anticholinesterase drugs and prednisolone in the treatment of myasthenia was noted. The presence of diabetes mellitus is a relative contraindication to the administration of corticosteroids, but in the presence of comorbidity of generalized myasthenia and diabetes mellitus type II, prednisolone was used under constant monitoring of blood glucose by hypoglycemic agents. Thus, late-onset, severe comorbid diseases (small vessel disease of the brain, diabetes mellitus) complicate and delay the diagnosis of myasthenia and prescription of appropriate therapy.

The impact of IGF-I, puberty and obesity on early retinopathy in children: a cross-sectional study

BackgroundChildhood obesity has been correlated with coronary heart disease, but the correlation with microvascular disease remains unclear. The retinal microcirculation is affected early in the process of atherosclerosis and it offers the opportunity to indirectly study the effects of obesity on small brain vessels. Insulin-like growth factor 1 (IGF-I) is involved in angiogenesis and it has a crucial role in retinal vascularization.MethodsA single-centre cross-sectional study was performed in 268 children and adolescents (116 males; mean age 13.03 ± 1.9 years,) with overweight/obesity, in order to identify risk factors for early retinopathy.ResultsNine patients (3.3%) showed signs of retinopathy, defined as arteriovenous crossings and/or papilledema. Body mass index and fat mass, analysed by Dual X-ray Absorptiometry, were not different in patients with or without retinopathy. Patients with retinopathy were pubertal and showed higher waist circumference (107.78 ± 15.83 versus 99.46 ± 10.85 cm; p: 0.027), waist circumference/height ratio (0.66 ± 0.07 versus 0.62 ± 0.05; p: 0.04) and IGF-I SDS (0.03 ± 1.3 versus − 0.66 ± 0.9; p: 0.04). Multivariate analysis (after correction for sex, age, family history of type 2 diabetes mellitus, obesity, cardiovascular disease, hypertension and dyslipidaemia) showed that waist circumference/height ratio and IGF-I SDS were the only variables independently correlated with the presence of retinopathy.ConclusionsRetinal vascular changes may become evident as an early complication of overweight and obesity, even during childhood and adolescence. Relatively high levels of IGF-I during this phase may act as an additional risk factor for microvascular damage. The screening for retinopathy should be proposed to all children and adolescents with overweight/obesity.

Cerebral Critical Closing Pressure: Is the Multiparameter Model Better Suited to Estimate Physiology of Cerebral Hemodynamics?

Cerebral critical closing pressure (CrCP) is the level of arterial blood pressure (ABP) at which small brain vessels close and blood flow stops. This value is always greater than intracranial pressure (ICP). The difference between CrCP and ICP is explained by the tone of the small cerebral vessels (wall tension). CrCP value is used in several dynamic cerebral autoregulation models. However, the different methods for calculation of CrCP show frequent negative values. These findings are viewed as a methodological limitation. We intended to evaluate CrCP in patients with severe traumatic brain injury (TBI) with a new multiparameter impedance-based model and compare it with results found earlier using a transcranial Doppler (TCD)-ABP pulse waveform-based method. Twelve severe TBI patients hospitalized during September 2005-May 2007. Ten men, mean age 32 years (16-61). Four had decompressive craniectomies (DC); three presented anisocoria. Patients were monitored with TCD cerebral blood flow velocity (FV), invasive ABP, and ICP. Data were acquired at 50Hz with an in-house developed data acquisition system. We compared the earlier studied "first harmonic" method (M1) results with results from a new recently developed (M2) "multiparameter method." M1: In seven patients CrCP values were negative, reaching -150mmHg. M2: All positive values; only one lower than ICP (ICP 60mmHg/ CrCP 57mmHg). There was a significant difference between M1 and M2 values (M1<M2) and between ICP and M2 (M2>ICP). M2 results in positive values of CrCP, higher than ICP, and are physiologically interpretable.

Unexpected Neurological Sequelae following Cerebral Fat Embolism Syndrome

Fat embolism syndrome is the most common form of non-thrombotic embolism and often described by presence of fat globules blocking small vessels in lung, skin or brain. The classical triad of fat embolism syndrome is respiratory manifestations, neurological signs and symptoms and petechial rash. Almost all neurological deficits are transient and fully reversible. Early diagnosis and supportive therapy is crucial for management of FES to decrease mortality and morbidity. We present a case of fat embolism syndrome due to multiple fractures recovered with neurological sequelae.

Abstract 46: Obstructive Sleep Apnea (OSA) Accelerates Cerebral Pathology in Spontaneously Hypertensive Stroke Prone Rat (SHRsp)

Cerebral small vessel disease (CSVD) and its pathological changes in small vessels in brain, is responsible for lacunar infarcts, white matter lesions, hemorrhages, microbleeds, and cognitive impairment. Although it has been suggested that OSA has a role in CSVD, there are no controlled studies relating OSA to CSVD and it pathological consequences. We tested the hypothesis that OSA in SHRsp rats, a model for CSVD, accelerates the development of associated brain pathologies. Chronic intermittent airway obstructions (termed OSA, 10 sec in duration, 60/hr, during 8 hr of the sleep cycle) were induced by remotely inflating balloons implanted in the tracheas of SHRsp and their parent strain, Wistar Kyoto rats (WKY). Studies were conducted at 12 and 20 weeks of age after being subjected to 14 days of OSA. Sham rats had balloons implanted but without inflations to occlude the airway. Systolic blood pressure was significantly increased in SHRsp with OSA by 58 ± 15 and 32 ± 7 mm Hg at 12 and 20 weeks respectively compared to SHRsp sham rats (n=7-10, p&lt;0.05). Working memory as assessed by novel object recognition was impaired in the SHRsp with OSA at both 12 and 20 weeks (n=6, p&lt;0.01). IgG extravasation, a measure of blood brain barrier integrity, was significantly increased (n=6, p&lt;0.05) in small vessels of the 12 and 20 week SHRsp OSA groups. In the 12 week SHRsp OSA group the IgG extravasation was mainly present in the white matter small vessels, while in the 20 week SHRsp OSA group, which contained far greater (p&lt;0.05, n=6) IgG positive small vessels, the majority of the IgG extravasation was found in the grey matter. Activation of microglia in the external capsule (as determined by morphometric analysis) was significantly greater in the SHRsp OSA group compared to all other groups of rats (n=6 each group, p&lt;0.05). There was a significant loss of white matter as indicated by a 192 ± 10% increase (n=6, p&lt;0.05) in the breakdown products of myelin basic protein in the SHRsp OSA group at 20 weeks but not at 12 weeks. We conclude that OSA in the SHRsp accelerates the onset of the cerebral pathologies associated with cerebral small vessel disease.

Calibrating Doppler imaging of preterm intracerebral circulation using a microvessel flow phantom.

Introduction: Preterm infants are born during critical stages of brain development, in which the adaptive capacity of the fetus to extra-uterine environment is limited. Inadequate brain perfusion has been directly linked to preterm brain damage. Advanced high-frequency ultrasound probes and processing algorithms allow visualization of microvessels and depiction of regional variation. To assess whether visualization and flow velocity estimates of preterm cerebral perfusion using Doppler techniques are accurate, we conducted an in vitro experiment using a microvessel flow phantom.Materials and Methods: An in-house developed flow phantom containing two microvessels (inner diameter 200 and 700 μm) with attached syringe pumps, filled with blood-mimicking fluid, was used to generate non-pulsatile perfusion of variable flow. Measurements were performed using an Esaote MyLab70 scanner.Results: Microvessel mimicking catheters with velocities as low as 1 cm/s were adequately visualized with a linear ultrasound probe. With a convex probe, velocities <2 cm/s could not be depicted. Within settings, velocity and diameter measurements were highly reproducible [intra-class correlation 0.997 (95% CI 0.996–0.998) and 0.914 (0.864–0.946)]. Overall, mean velocity was overestimated up to threefold, especially in high velocity ranges. Significant differences were seen in velocity measurements when using steer angle correction and in vessel diameter estimation (p < 0.05).Conclusion: Visualization of microvessel-size catheters mimicking small brain vessels is feasible. Reproducible velocity and diameter results can be obtained, although important overestimation of the values is observed. Before velocity estimates of microcirculation can find its use in clinical practice, calibration of the ultrasound machine for any specific Doppler purpose is essential. The ultimate goal is to develop a sonographic tool that can be used for objective study of regional perfusion in routine practice.

PReS-FINAL-2364: Status epilepticus as an initial manifestation of central nervous system small vessel vasculitis is related to unfavourable neurological outcome in paediatric patients

Childhood primary angiitis of the central nervous system (cPACNS) is an inflammatory disease involving small and medium-large size brain vessels with variable clinical presentation. Clinical symptoms range from headache, cognitive impairment, hemiplegia, language deficit to seizures and status epilepticus. However, it remains unclear if the type of initial manifestation/symptoms predicts neurological outcome in cPACNS.

In Vivo Imaging of Neurovascular Remodeling After Stroke

Stroke is one of the leading causes of adult disability throughout the world and, even though neural mechanisms of loss of function have been extensively studied, many aspects of poststroke cerebral responses remain poorly understood. Of particular interest is the mounting evidence of the capacity of the adult brain to reorganize after injury, which is believed to contribute to limitation of the extent of neural dysfunction and to restoration of affected neural functions. Processes such as neuronal plasticity, glial proliferation, and neovascularization may be essential for preservation or recovery of function after stroke and may conceivably go hand-in-hand at nearby and remote sites of active tissue reorganization.1,2 Specifically, the acute initiation of neurovascular remodeling, stimulating the proliferation and growth of existing arteries/arterioles (ie, arteriogenesis) or new capillaries (ie, angiogenesis), may be critical to facilitate the survival and restructuring of neural tissue, which ultimately may contribute to functional recovery at later stages.3 A variety of vascular imaging strategies is available for in vivo detection, characterization, and quantification of these processes, which can significantly aid in elucidation of the role of neurovascular remodeling after stroke, as discussed in this review. Because most of the described imaging modalities are present in experimental and clinical settings, this raises significant opportunities for translational studies. Growth and remodeling of existing and nascent vascular networks in health and disease involve a number of critical steps that have been comprehensively described by Risau4 and Carmeliet.5 Arteriogenesis involves adaptive growth and proliferation of preexisting (collateral) arteries and arterioles in response to increase in intravascular shear forces. The increased shear stress leads to upregulation of cell adhesion molecules, followed by accumulation of monocytes and other leukocytes that release cytokines and growth factors around the proliferating and maturating arteries.6 Although arteriogenic growth of collateral …

Stases are associated with blood–brain barrier damage and a restricted activation of coagulation in SHRSP

Cerebral small vessel disease (CSVD) is a chronically proceeding pathology of small brain vessels associated with white matter lesions, lacunar infarcts, brain atrophy and microbleeds. CSVD leads to slowly increasing cognitive and functional deficits but may also cause stroke-like symptoms, if vessels in critical brain areas are affected. Spontaneously hypertensive stroke-prone rats (SHRSP) exhibit several vascular risk factors, develop infarcts and hemorrhages and therefore represent a relevant model for the study of CSVD. Using this animal model, we recently demonstrated that intravasal accumulations of erythrocytes, we interpreted as stases, stand at the beginning of a pathological vascular cascade. After stases microbleeds occur, which are followed by reactive microthromboses. Bleeds and thromboses finally cause hemorrhagic infarcts. Immunohistochemical stainings show, that plasma proteins like IgG are deposited in the walls of vessels affected by stases. Further, we found small clots and thread-shaped aggregations of thrombocytes as well as thread-shaped structures of von Willebrand-Factor within stases. Thus, we conclude that blood–brain barrier damages occur in the neighborhood of stases and stases seem to be associated with a restricted activation of blood coagulation without formation of obstructive thromboses. Finally, we demonstrate that small vessel damage rarely appears in the cerebellum. Even animals with multiple cerebral infarcts may be free of any cerebellar vascular pathology.

Subcellular localization and distribution of the reduced folate carrier in normal rat tissues

The reduced folate carrier (Rfc1; Slc19a1) mediated transport of reduced folates and antifolate drugs such as methotrexate (MTX) play an essential role in physiological folate homeostasis and MTX cancer chemotherapy. As no systematic reports are as yet available correlating Rfc1 gene expression and protein levels in all tissues crucial for folate and antifolate uptake, storage or elimination, we investigated gene and protein expression of rat Rfc1 (rRfc1) in selected tissues. This included the generation of a specific anti-rRfc1 antibody. Rabbits were immunised with isolated rRfc1 peptides producing specific anti-rRfc1 antiserum targeted to the intracellular C-terminus of the carrier. Using RT-PCR analysis, high rRfc1 transcript levels were detected in colon, kidney, brain, thymus, and spleen. Moderate rRfc1 gene expression was observed in small intestine, liver, bone marrow, lung, and testes whereas transcript levels were negligible in heart, skeletal muscle or leukocytes. Immunohistochemical analyses revealed strong carrier expression in the apical membrane of tunica mucosa epithelial cells of small intestine and colon, in the brush-border membrane of choroid plexus epithelial cells or in endothelial cells of small vessels in brain and heart. Additionally, high rRfc1 protein levels were localized in the basolateral membrane of renal tubular epithelial cells, in the plasma membrane of periportal hepatocytes, and sertoli cells of the testes. Taken together, our results demonstrated that rRfc1 is expressed almost ubiquitously but to very different levels. The predominant tissue distribution supports the essential role of Rfc1 in physiological folate homeostasis. Moreover, our results may contribute to understand antifolate pharmacokinetics and selected organ toxicity associated with MTX chemotherapy.

Microvascular intraoperative Doppler sonography

The use of Doppler sonographic equipment transmitting pulsed high-frequency (20 MHz) ultrasound in conjunction with miniaturised probes, allowed recordings from small brain vessels having diameters of 1 mm and less. Experience made with this technique in clinical and experimental neurosurgery demonstrated its value in all types of neurovascular operations. Nearly 10% of the immediate results of such operations, though apparently successful or without adverse findings, eventually proved unsatisfactory on Doppler sonography only and could be subsequently corrected. The quality of arterial anastomoses performed in animal experiments as well as the various anastomotic techniques can be investigated in terms of their haemodynamic efficiency. The same holds true for cerebral arterial anastomoses in man. The patency of these anastomoses can be examined intraoperatively and necessary corrections can be made immediately. Similarly the method is most helpful in aneurysm operations by allowing to verify the clipping of the aneurysm neck and the patency of the supplying vessels.

Tumor-necrosis factor and other cytokines in cerebral malaria: experimental and clinical data.

Evidence is presented here that tumor necrosis factor/cachectin (TNF), is of crucial importance in the pathogenesis of cerebral malaria. First, the central lesion of CM, hemorrhagic necrosis of cerebral vessels, corresponds to lesions observed during other pathological conditions associated with high serum TNF levels, such as endotoxemic shock or administration of TNF. Second, in both mouse and human, there is a close correlation between high serum TNF levels and CM. At least in mouse, high TNF levels and CM depend upon T lymphocytes of the CD4+ phenotype. Third, passive immunization against mouse TNF significantly prolongs the survival of P. berghei-infected CBA/Ca mice, and prevents the development of neurologic signs. Treatment with the anti-TNF antibody also prevents hemorrhagic necrosis of brain vessels. Fourth, in the mouse model, a cytokine cascade including at least GM-CSF, IL-3 and IFN-gamma is required for the elevation of TNF level. This cascade appears to involve two components: (a) a quantitative component: increased accumulation of macrophages results from the concomitant release of IL-3 and GM-CSF, and (b) a qualitative component: macrophage number has not only to be raised, but macrophages need to be activated by IFN-gamma. Fifth, metabolic parameters of CM and its main lesion in both mouse and human, i.e. the hemorrhagic necrosis of small brain vessels, correspond to the known properties of TNF.

Ultrastructural localization of choline acetyltransferase in vascular endothelial cells in rat brain.

Furchgott and Zawadski have shown that acetylcholine (ACh) does not act directly on the smooth muscle of blood vessel walls, but rather via receptors on the endothelial cells lining the lumen, to release an endothelium-derived relaxing factor (EDRF). As it is very unlikely that neurotransmitter released from the periarterial nerves, which are confined to the adventitial-medial border, diffuses all the way through the medial muscle coat before acting on endothelial cells to release EDRF to produce vasodilatation, this discovery has been regarded as an indication of a pathophysiological mechanism, rather than a physiological one (see refs 2, 3). ACh is rapidly degraded in the blood by acetylcholinesterase, so that ACh must be released locally to be effective on endothelial cells. Here we demonstrate the immunocytochemical localization of choline acetyltransferase in endothelial cells of small brain vessels, which is consistent with the view that the ACh originates from endothelial cells that can synthesize and store it. We suggest that release of ACh following damage to endothelial cells during ischaemia contributes to a pathophysiological mechanism of vasodilation which protects that segment of vessel from further damage as well as brain cells from hypoxia.