Dysregulation of brain and choroid plexus cell types in severe COVID-19

Although SARS-CoV-2 primarily targets the respiratory system, patients with and survivors of COVID-19 can suffer neurological symptoms1-3. However, an unbiased understanding of the cellular and molecular processes that are affected in the brains of patients with COVID-19 is missing. Here we profile 65,309 single-nucleus transcriptomes from 30 frontal cortex and choroid plexus samples across 14 control individuals (including 1 patient with terminal influenza) and 8 patients with COVID-19. Although our systematic analysis yields no molecular traces of SARS-CoV-2 in the brain, we observe broad cellular perturbations indicating that barrier cells of the choroid plexus sense and relay peripheral inflammation into the brain and show that peripheral T cells infiltrate the parenchyma. We discover microglia and astrocyte subpopulations associated with COVID-19 that share features with pathological cell states that have previously been reported in human neurodegenerative disease4-6. Synaptic signalling of upper-layer excitatory neurons-which are evolutionarily expanded in humans7 and linked to cognitive function8-is preferentially affected in COVID-19. Across cell types, perturbations associated with COVID-19 overlap with those found in chronic brain disorders and reside in genetic variants associated with cognition, schizophrenia and depression. Our findings and public dataset provide a molecular framework to understand current observations of COVID-19-related neurological disease, and any such disease that may emerge at a later date.

Tertiary lymphoid structures in the choroid plexus in neuropsychiatric lupus

The central nervous system manifestations of systemic lupus erythematosus (SLE) remain poorly understood. Given the well-defined role of autoantibodies in other lupus manifestations, extensive work has gone into the identification of neuropathic autoantibodies. However, attempts to translate these findings to patients with SLE have yielded mixed results. We used the MRL/MpJ-Faslpr/lpr mouse, a well-established, spontaneous model of SLE, to establish the immune effectors responsible for brain disease. Transcriptomic analysis of the MRL/MpJ-Faslpr/lpr choroid plexus revealed an expression signature driving tertiary lymphoid structure formation, including chemokines related to stromal reorganization and lymphocyte compartmentalization. Additionally, transcriptional profiles indicated various stages of lymphocyte activation and germinal center formation. The extensive choroid plexus infiltrate present in MRL/MpJ-Faslpr/lpr mice with overt neurobehavioral deficits included locally proliferating B and T cells, intercellular interactions between lymphocytes and antigen-presenting cells, as well as evidence for in situ somatic hypermutation and class switch recombination. Furthermore, the choroid plexus was a site for trafficking lymphocytes into the brain. Finally, histological evaluation in human lupus patients with neuropsychiatric manifestations revealed increased leukocyte migration through the choroid plexus. These studies identify a potential new pathway underlying neuropsychiatric lupus and support tertiary lymphoid structure formation in the choroid plexus as a novel mechanism of brain-immune interfacing.

Corticosteroid signaling at the brain-immune interface impedes coping with severe psychological stress

The immune system supports brain plasticity and homeostasis, yet it is prone to changes following psychological stress. Thus, it remains unclear whether and how stress-induced immune alterations contribute to the development of mental pathologies. Here, we show that following severe stress in mice, leukocyte trafficking through the choroid plexus (CP), a compartment that mediates physiological immune-brain communication, is impaired. Blocking glucocorticoid receptor signaling, either systemically or locally through its genetic knockdown at the CP, facilitated the recruitment of Gata3- and Foxp3-expressing T cells to the brain and attenuated post-traumatic behavioral deficits. These findings functionally link post-traumatic stress behavior with elevated stress-related corticosteroid signaling at the brain-immune interface and suggest a novel therapeutic target to attenuate the consequences of severe psychological stress.

Targeting Germinal Matrix Hemorrhage-Induced Overexpression of Sodium-Coupled Bicarbonate Exchanger Reduces Posthemorrhagic Hydrocephalus Formation in Neonatal Rats

BACKGROUND

Germinal matrix hemorrhage (GMH) is a leading cause of mortality and lifelong morbidity in preterm infants. Posthemorrhagic hydrocephalus (PHH) is a common complication of GMH. A sodium-coupled bicarbonate exchanger (NCBE) encoded by solute carrier family 4 member 10 gene is expressed on the choroid plexus basolateral membrane and may play a role in cerebrospinal fluid production and the development of PHH. Following GMH, iron degraded from hemoglobin has been linked to PHH. Choroid plexus epithelial cells also contain iron-responsive element-binding proteins (IRPs), IRP1, and IRP2 that bind to mRNA iron-responsive elements. The present study aims to resolve the following issues: (1) whether the expression of NCBE is regulated by IRPs; (2) whether NCBE regulates the formation of GMH-induced hydrocephalus; and (3) whether inhibition of NCBE reduces PHH development.

METHODS AND RESULTS

GMH model was established in P7 rat pups by injecting bacterial collagenase into the right ganglionic eminence. Another group received iron trichloride injections instead of collagenase. Deferoxamine was administered intraperitoneally for 3 consecutive days after GMH/iron trichloride. Solute carrier family 4 member 10 small interfering RNA or scrambled small interfering RNA was administered by intracerebroventricular injection 24 hours before GMH and followed with an injection every 7 days over 21 days. NCBE expression increased while IRP2 expression decreased after GMH/iron trichloride. Deferoxamine ameliorated both the GMH-induced and iron trichloride-induced decrease of IRP2 and decreased NCBE expressions. Deferoxamine and solute carrier family 4 member 10 small interfering RNA improved cognitive and motor functions at 21 to 28 days post GMH and reduced cerebrospinal fluid production as well as the degree of hydrocephalus at 28 days after GMH.

CONCLUSIONS

Targeting iron-induced overexpression of NCBE may be a translatable therapeutic strategy for the treatment of PHH following GMH.

The choroid plexus is a key cerebral invasion route for T cells after stroke

Neuroinflammation contributes substantially to stroke pathophysiology. Cerebral invasion of peripheral leukocytes-particularly T cells-has been shown to be a key event promoting inflammatory tissue damage after stroke. While previous research has focused on the vascular invasion of T cells into the ischemic brain, the choroid plexus (ChP) as an alternative cerebral T-cell invasion route after stroke has not been investigated. We here report specific accumulation of T cells in the peri-infarct cortex and detection of T cells as the predominant population in the ipsilateral ChP in mice as well as in human post-stroke autopsy samples. T-cell migration from the ChP to the peri-infarct cortex was confirmed by in vivo cell tracking of photoactivated T cells. In turn, significantly less T cells invaded the ischemic brain after photothrombotic lesion of the ipsilateral ChP and in a stroke model encompassing ChP ischemia. We detected a gradient of CCR2 ligands as the potential driving force and characterized the neuroanatomical pathway for the intracerebral migration. In summary, our study demonstrates that the ChP is a key invasion route for post-stroke cerebral T-cell invasion and describes a CCR2-ligand gradient between cortex and ChP as the potential driving mechanism for this invasion route.

Use of dynamic (18)F-fluorodeoxyglucose positron emission tomography to investigate choroid plexus function in Alzheimer's disease

Choroid plexuses (CPs) are structures involved in CSF production and cerebral regulation and present atypical glucose metabolism. In addition, CPs impairment may be related to Alzheimer disease (AD). In the present study, we present the first results pointing out glucose metabolism in the CP with dynamic fluorodeoxyglucose positron emission tomography (dynamic (18)F-FDG-PET). We studied 47 elderly adults who were classified into three classes: healthy subjects (HS), amnestic mild cognitive impairment (aMCI) and AD. All participants have undergone dynamic (18)F-FDG-PET for 45 min. Acquisitions were divided into 34 frames to extract tissue time-activity curves (TTACs) in various structures including CSF and CPs. Results showed a decreased CPs (18)F-FDG metabolism in AD compared with aMCI and HS. Conversely, dynamic uptake was higher in CSF for AD compared with the other groups. ROC analysis showed that CPs TTACs are a promising tool as it yielded sensitivity of 85.7% and a specificity of 83.3%. Our study showed a disturbance of glucose exchange at the blood-CSF barrier level which is in favour of a key-role of the CPs in AD.

Disturbed function of the blood-cerebrospinal fluid barrier aggravates neuro-inflammation

Multiple sclerosis (MS) is a chronic neuro-inflammatory disorder, which is marked by the invasion of the central nervous system by monocyte-derived macrophages and autoreactive T cells across the brain vasculature. Data from experimental animal models recently implied that the passage of leukocytes across the brain vasculature is preceded by their traversal across the blood-cerebrospinal fluid barrier (BCSFB) of the choroid plexus. The correlation between the presence of leukocytes in the CSF of patients suffering from MS and the number of inflammatory lesions as detected by magnetic resonance imaging suggests that inflammation at the choroid plexus contributes to the disease, although in a yet unknown fashion. We here provide first insights into the involvement of the choroid plexus in the onset and severity of the disease and in particular address the role of the tight junction protein claudin-3 (CLDN3) in this process. Detailed analysis of human post-mortem brain tissue revealed a selective loss of CLDN3 at the choroid plexus in MS patients compared to control tissues. Importantly, mice that lack CLDN3 have an impaired BCSFB and experience a more rapid onset and exacerbated clinical signs of experimental autoimmune encephalomyelitis, which coincides with enhanced levels of infiltrated leukocytes in their CSF. Together, this study highlights a profound role for the choroid plexus in the pathogenesis of multiple sclerosis, and implies that CLDN3 may be regarded as a crucial and novel determinant of BCSFB integrity.

Spontaneous lesions in aged captive raccoons (Procyon lotor)

In nature, free-ranging raccoons typically do not live longer than 2 y; most raccoons in the wild die young due to accidents and diseases. Therefore, few data are available regarding lesions associated with advancing age in raccoons. This communication documents the lesions present in raccoons (7 male; 3 female) that were older than 7 y and had been used as breeders at a commercial facility in central Iowa. The most frequent microscopic lesions in these raccoons included accumulation of iron pigment in livers and spleens (10 of 10 animals evaluated), neuroaxonal degeneration in caudal medulla (10 of 10), vascular mineralization (psammoma body) in choroid plexus (9 of 10), myocardial inclusions (7 of 8), and cystic endometrial hyperplasia (2 of 3). Other conditions were seen with less prevalence. Except for the detection of gastritis with bacteria in the gastric mucosa of 1 raccoon, the presence of inflammatory cells in 3 choroid plexuses, and the presence of Lafora bodies in the brain of 1 animal, all conditions observed had previously been reported in raccoons. Surprisingly, islet-cell amyloidosis, previously observed as common incidental finding in older captive raccoons, was not seen in any of the raccoons we examined. Because free-ranging raccoons are distributed over wide geographic areas, their local environment may have considerable influence on the range of spontaneous lesions that would occur in raccoons obtained from a specific location. Therefore, the lesions found in these raccoons from central Iowa may differ from those of other raccoon populations.

Cerebrospinal fluid corticosteroid levels and cortisol metabolism in patients with idiopathic intracranial hypertension: a link between 11beta-HSD1 and intracranial pressure regulation?

CONTEXT

The etiology of idiopathic intracranial hypertension (IIH) is unknown. We hypothesized that obesity and elevated intracranial pressure may be linked through increased 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity.

OBJECTIVE

The aim was to characterize 11β-HSD1 in human cerebrospinal fluid (CSF) secretory [choroid plexus (CP)] and drainage [arachnoid granulation tissue (AGT)] structures, and to evaluate 11β-HSD1 activity after therapeutic weight loss in IIH.

DESIGN AND SETTING

We conducted in vitro analysis of CP and AGT and a prospective in vivo cohort study set in two tertiary care centers.

PATIENTS OR OTHER PARTICIPANTS

Twenty-five obese adult female patients with active IIH were studied, and 22 completed the study.

INTERVENTION

Fasted serum, CSF, and 24-h urine samples were collected at baseline, after 3-month observation, and after a 3-month diet.

MAIN OUTCOME MEASURES

Changes in urine, serum, and CSF glucocorticoids (measured by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry) after weight loss were measured.

RESULTS

11β-HSD1 and key elements of the glucocorticoid signaling pathway were expressed in CP and AGT. After weight loss (14.2±7.8 kg; P<0.001), global 11β-HSD1 activity decreased (P=0.001) and correlated with reduction in intracranial pressure (r=0.504; P=0.028). CSF and serum glucocorticoids remained stable, although the change in CSF cortisone levels correlated with weight loss (r=-0.512; P=0.018).

CONCLUSIONS

Therapeutic weight loss in IIH is associated with a reduction in global 11β-HSD1 activity. Elevated 11β-HSD1 may represent a pathogenic mechanism in IIH, potentially via manipulation of CSF dynamics at the CP and AGT. Although further clarification of the functional role of 11β-HSD1 in IIH is needed, our results suggest that 11β-HSD1 inhibition may have therapeutic potential in IIH.

Arachnoid granules: Dandy was Dandy, Cushing and Weed were not

Errors can be instructive. It seems that Harvey Cushing and Louis Weed provided the medical world with a faulty theory of cerebrospinal fluid absorption. Louis Weed, working in Harvey Cushing's laboratory, initially studied the movement of substances in the cerebrospinal fluid by using low-pressure studies. Results of the low-pressure studies were considered unsatisfactory and high pressure experiments were undertaken and these had results similar to earlier work done by others in human cadavers. High pressure results demonstrating movement of fluid through the arachnoid granules were deemed correct. Because of Cushing's position of authority, the theory became accepted as fact and in time proved to be entrenched dogma. Walter Dandy demonstrated in experiments on hydrocephalus and the surgical removal of the arachnoid granule system that the fluid was produced by the choroid plexuses and not absorbed by the arachnoid granules. His work was dismissed by Weed as unreliable. Examination of the pattern of deposition of corpora amylacea on the surface of the brain provides evidence that cerebrospinal fluid does not pass through arachnoid granules but passes through the choroid fissure and is recycled through choroid plexus portals. The choroid plexus portal theory can explain the findings in the low-pressure experiments of Weed. Bias and pride seem to be the source of the faulty theory. Entrenched dogma is resistant to challenge.

Ruptured aneurysms of the choroidal branches of the posterior inferior cerebellar artery: a review of the literature and a case report

Aneurysms of the choroidal branches of the posterior inferior cerebellar artery (PICA) are quite rare; only seven such cases have been reported thus far. In this study, we present a very rare case of a ruptured aneurysm of a choroidal branch of the PICA; the aneurysm was exposed by splitting the vermis and resected after proximal arterial ligation. We have also undertaken a thorough review of the literature on aneurysms in choroidal branches of the PICA, focusing on the clinical presentation, etiology, radiological findings, and surgical strategies. We found that the aneurysms in our patient and the aneurysms in seven published case reports were small, and frequently associated with vascular anomalies. Intraventricular hemorrhage (IVH) in the fourth ventricle was detected in all eight cases. The outcomes of surgical treatment were generally favorable, notwithstanding the high incidence of rebleeding after rupture of distal PICA aneurysms. The recognition of predominant fourth ventricular hemorrhage should raise the suspicion of the presence of an underlying aneurysm, and digital subtraction angiograms (DSAs) should be immediately obtained in order to detect small aneurysms of the choroidal branches of the PICA.

Melatonin ameliorates blood-brain barrier permeability, glutathione, and nitric oxide levels in the choroid plexus of the infantile rats with kaolin-induced hydrocephalus

Hydrocephalus is a disabling disease for children, but current data concerning the effects of melatonin on ventricular enlargement are still limited. We have investigated the changes in the choroid plexuses (CPs) of ventricles and blood-brain barrier (BBB) of hydrocephalic rats. Forty-five Swiss Albino rats at age 2 weeks were divided into three equal groups: control, hydrocephalus, and melatonin-treated hydrocephalus groups. Hydrocephalus was induced by kaolin injection into the cisterna magna of all pups except control group and melatonin was given at a daily dose of 0.5 mg/100 g body weight for 4 weeks. At the end of the study, one animal from each group was examined using a gamma camera to study the disruption of BBB due to hydrocephalus. All animals were then killed for assay of glutathione (GSH) and nitric oxide (NO), as well as histological study of the CPs during the hydrocephalus. We observed an increased BBB activity was found in hydrocephalus group, while melatonin reversed these changes. It was found that NO concentration was elevated in hydrocephalus group and melatonin partly abolished the increased levels of NO. In contrast, GSH levels were significantly decreased in hydrocephalus group, while melatonin increased the tissue GSH level (p<0.01). Histologically, there was a significant alteration in the CPs of the ventricles of hydrocephalic animals, but it was regressed after melatonin treatment in consistent with the gross morphological changes related to hydrocephalus. In conclusion, our results clearly demonstrated for the first time the neuroprotective effects of melatonin upon hydrocephalus-induced CP changes in infantile rats, but further studies are needed to suggest melatonin as a candidate protective drug in children.

Differential changes in junctional complex proteins suggest the ependymal lining as the main source of leukocyte infiltration into ventricles in murine neurocysticercosis

The blood brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCB) limit the influx of immune mediators and bloodstream compounds into the central nervous system (CNS). Upon injury or infection, the integrity of these barriers is compromised and leukocyte infiltration occurs. The BCB is located in the choroid plexuses (CPs) found within ventricles of the brain, and it is considered one of the main routes of cellular infiltration into the CNS into healthy individuals. Our group recently showed that in a murine model of neurocysticercosis (NCC), there is a moderate increase in infiltration of leukocytes into ventricles, but the BCB is hardly compromised. To elucidate the role played by CPs and surrounding ependyma in leukocyte infiltration at ventricular sites, we analyzed changes in the expression of junctional complex proteins in animals intracranially infected with Mesocestoides corti. The results indicate that infection does not change the expression pattern of junctional complex proteins in CPs, but structural alterations and disappearance of these proteins were evident in ependyma adjacent to the internal leptomeninges. The kinetics and magnitude of these changes directly correlated with the extent of leukocyte infiltration through ependyma and with the expression and activity of MMPs. The results of this study indicate that the anatomical elements of the BCB are minimally disrupted during the course of murine NCC. Thus, most of the leukocytes infiltrating ventricles appear to extravasate through pial vessels located in the internal leptomeninges juxtaposed to the ependyma layer and then traverse the ependyma cells. In addition, MMP activity seems to be involved in this process. These results provide evidence for a previously undescribed entry route for leukocytes into the CNS.

Variations of disseminated choroid plexus papilloma: 2 case reports and a review of the literature

BACKGROUND

Choroid plexus papillomas are typically considered benign lesions, but histology is not always predictive of their behavior. These tumors can metastasize anywhere along the neuraxis and may be intraventricular, subarachnoid, or intraparenchymal. We present 2 cases that illustrate the wide diversity with which choroid plexus papillomas can disseminate.

CASE DESCRIPTIONS

The patient described in case 1 had a primary fourth ventricular choroid plexus papilloma that produced diffuse cystic subarachnoid and leptomeningeal lesions. Patient 2 also had a primary fourth ventricular tumor but with subsequent suprasellar and spinal drop metastases. Patient 1 was treated with temozolomide, resulting in regression of symptoms including headache and dizziness. Patient 2 has been treated with several modalities, including radiation therapy and chemotherapy, with slowing of symptom progression.

CONCLUSIONS

Variations of choroid plexus papilloma dissemination include intraventricular, subarachnoid, and leptomeningeal nodules or cystic lesions, and intraparenchymal locations. There is no consensus on the most effective treatment for choroid plexus papilloma metastases; surgical resection, chemotherapy, and radiation therapy may all yield benefits. The prognosis for patients with disseminated choroid plexus papilloma can range from prolonged stable disease and symptoms to death within months.

Diffuse villous hyperplasia of choroid plexus

Diffuse villous hyperplasia of choroid plexus (DVHCP) is a rare condition which is characterized by the presence of diffuse enlargement of the entire choroid plexus throughout the length of the choroidal fissure and overproduction of CSF. The diagnosis of diffuse villous hyperplasia of choroid plexus can be established by the MR demonstration of diffusely large, contrast enhanced choroid plexus in the cases of overproduction hydrocephalus. Although some authors recommend choroid plexus excision or coagulation, ventriculo-atrial shunt insertion is a simple and effective treatment modality in cases of diffuse villous hyperplasia of the choroid plexus. In this report we present a case of diffuse villous hyperplasia of the choroid plexus and a short review of the literature. To our knowledge, in the CT and MRI era only 5 cases of DVHCP cases have been reported.

Dysfunctional cilia lead to altered ependyma and choroid plexus function, and result in the formation of hydrocephalus

Cilia are complex organelles involved in sensory perception and fluid or cell movement. They are constructed through a highly conserved process called intraflagellar transport (IFT). Mutations in IFT genes, such as Tg737, result in severe developmental defects and disease. In the case of the Tg737orpk mutants, these pathological alterations include cystic kidney disease, biliary and pancreatic duct abnormalities, skeletal patterning defects, and hydrocephalus. Here, we explore the connection between cilia dysfunction and the development of hydrocephalus by using the Tg737orpk mutants. Our analysis indicates that cilia on cells of the brain ventricles of Tg737orpk mutant mice are severely malformed. On the ependymal cells, these defects lead to disorganized beating and impaired cerebrospinal fluid (CSF) movement. However, the loss of the cilia beat and CSF flow is not the initiating factor, as the pathology is present prior to the development of motile cilia on these cells and CSF flow is not impaired at early stages of the disease. Rather, our results suggest that loss of cilia leads to altered function of the choroid plexus epithelium, as evidenced by elevated intracellular cAMP levels and increased chloride concentration in the CSF. These data suggest that cilia function is necessary for regulating ion transport and CSF production, as well as for CSF flow through the ventricles.

Strain-dependent disruption of blood–cerebrospinal fluid barrier byStreptoccocus suisin vitro

Streptococcus suis capsular type 2 is an important agent of diseases including meningitis among pigs worldwide, and is also a zoonotic agent. The barrier function of the choroid plexus epithelium that constitutes the structural basis for the blood-cerebrospinal fluid (CSF) barrier has not been elucidated yet in bacterial meningitis. We investigated the influence of various S. suis isolates on the barrier function of cultured porcine choroid plexus epithelial cells with respect to the transepithelial resistance and paracellular [(3)H]-mannitol flux. Preferentially apical application of S. suis isolates significantly decreased transepithelial resistance and significantly increased paracellular [(3)H]-mannitol flux in a time-, dose- and strain-dependent manner. Viable S. suis isolates caused cytotoxicity determined by lactate dehydrogenase assay and electron microscopy, whereas S. suis sonicates and UV-inactivated S. suis did not cause cytotoxicity. The observed effects on porcine choroid plexus epithelial cells barrier function could not exclusively be ascribed to known virulence factors of S. suis such as suilysin. In conclusion, S. suis isolates induce loss of blood-cerebrospinal fluid barrier function in an in vitro model. Thus, S. suis may facilitate trafficking of bacteria and leucocytes across the blood-cerebrospinal fluid barrier. The underlying mechanisms for the barrier breakdown have yet to be determined.

Hippocampal damage in mouse and human forms of systemic autoimmune disease

Systemic lupus erythematosus (SLE) is frequently accompanied by neuropsychiatric (NP) and cognitive deficits of unknown etiology. By using autoimmune MRL-lpr mice as an animal model of NP-SLE, we examine the relationship between autoimmunity, hippocampal damage, and behavioral dysfunction. Fluoro Jade B (FJB) staining and anti-ubiquitin (anti-Ub) immunocytochemistry were used to assess neuronal damage in young (asymptomatic) and aged (diseased) mice, while spontaneous alternation behavior (SAB) was used to estimate the severity of hippocampal dysfunction. The causal relationship between autoimmunity and neuropathology was tested by prolonged administration of the immunosuppressive drug cyclophosphamide (CY). In comparison to congenic MRL +/+ controls, SAB acquisition rates and performance in the "reversal" trial were impaired in diseased MRL-lpr mice, suggesting limited use of the spatial learning strategy. FJB-positive neurons and anti-Ub particles were frequent in the CA3 region. Conversely, CY treatment attenuated the SAB deficit and overall FJB staining. Similarly to mouse brain, the hippocampus from a patient who died from NP-SLE showed reduced neuronal density in the CA3 region and dentate gyrus, as well as increased FJB positivity in these regions. Gliosis and neuronal loss were observed in the gray matter, and T lymphocytes and stromal calcifications were common in the choroid plexus. Taken together, these results suggest that systemic autoimmunity induces significant hippocampal damage, which may underlie affective and cognitive deficits in NP-SLE.

Stress protein expression in the Alzheimer-diseased choroid plexus

Abnormal patterns of stress protein expression are found in the cerebral cortex and hippocampus of Alzheimer (AD) subjects. In this study, expression of various stress proteins in the Alzheimer-diseased choroid plexus (CP) was assessed immunohistochemically. We observed decreased HO-1 immunoreactivity in the AD CP, commensurate with our earlier report of suppressed HO-1 protein levels in AD cerebrospinal fluid (Schipper et al., Neurology 54:1297-1304, 2000). Heat shock protein (HSP) 90 was up-regulated in the AD CP relative to controls. There was a trend towards increased expression of HSP60, a mitochondrial stress protein; this is compatible with mitochondrial pathology recently documented in AD CP. Up-regulation of HSP90, a steroid receptor chaperone, in the AD CP may indicate abnormal hormone receptor expression in this secretory tissue. Glucose-regulated protein (GRP) 78 and 94 immunostaining was diminished in AD CP, implicating possible derangements in glucose or calcium homeostasis. Oxidative stress, per se, is probably not responsible for our observations because: i) there were no noticeable differences in the expression of HSP 70, ubiquitin, and alpha-B crystallin in the AD CP; and ii) augmentation, rather than the noted suppression, of HO-1 immunoreactivity would have been expected.

Radiobiological effects of photon radiosurgery on choroid plexus cells in vitro

The standard surgical treatment of hydrocephalus by cerebrospinal fluid (CSF) shunt is accompanied by numerous complications. The search for alternative treatment methods includes resection, coagulation and irradiation of part of the plexus choroideus. The reduction of CSF secretion after choroid plexus (CP) irradiation has been investigated only on the experimental level. The new Photon Radiosurgery System (PRS) now also provides clinically the opportunity to induce selective radionecrosis on the CP with high efficiency and safety. In order to achieve a basic understanding of the reaction of CP cells after PRS irradiation, we investigated the cell death after different irradiation doses using TB dye-exclusion and MTT assay on sheep choroid plexus (SCP) cells. We observed a dose-dependent decrease in cell survival with increasing doses of irradiation (9, 18, 27 and 36 Gy). Lower irradiation doses (9, 18 Gy) induced an initial decrease of cell survival. Cells were able to recover from day 6 on and achieved a similar cell viability compared to non-irradiated cells on day 12. In contrast, higher doses (27 and 36 Gy) of irradiation induced a constant decrease of the cell survival over 12 days. These results clearly demonstrate that PRS irradiation is able to induce radionecrosis of CP cells which are responsible for the secretion of CSF. Interstitial photon radiosurgery can provide the opportunity to deliver the irradiation dose locally to CP with minimal exposure of surrounding tissue. Our basic data support further studies investigating this concept in animal models and clinically.

CSF-folate levels are decreased in late-onset AD patients

Folates are involved in the cerebral metabolism of cobalamine, methionine, L-tyrosine and acetylcholine. Remarkably CSF-folate levels are 3 to 4 times higher than blood-folate levels. To reach the brain, folates are actively transported by choroid plexus (CP) as well as vitamins B6, B12, C and E. Epithelial atrophy having been reported in aging and in Alzheimer's disease (AD), we measured the CSF folate-levels of 126 patients, including 30 AD consecutive patients to evaluate whether CP functions of folate-transport were impaired. CSF-folate concentrations did not vary with age (10.47 +/- 1.93ng/ml between 20 and 60 years; 9.96 +/- 2.01 ng/ml in elderly control patients older than 60 years of age, p > 0.05) while late-onset AD patients had significantly lower CSF-folate levels (8.26 +/- 1.82 ng/ml, p < 0.001). These data support a specific alteration of CP transport function in AD patients.

Selective involvement of the choroid plexus on cerebral magnetic resonance images: a new radiological sign in patients with systemic lupus erythematosus with neurological symptoms

The selective involvement of the choroid plexus on brain magnetic resonance (MR) images is described in 2 patients with systemic lupus erythematosus presenting with neurological symptoms. The decrease in choroid plexus abnormalities on followup MR examination paralleled the clinical recovery with glucocorticoid therapy in both patients. Our cases indicate that selective involvement of the choroid plexus should be included in the spectrum of the radiological signs for neurological lupus.

Choroid plexus in the central nervous system: biology and physiopathology

Choroid plexuses (CPs) are localized in the ventricular system of the brain and form one of the interfaces between the blood and the central nervous system (CNS). They are composed of a tight epithelium responsible for cerebrospinal fluid secretion, which encloses a loose connective core containing permeable capillaries and cells of the lymphoid lineage. In accordance with its peculiar localization between 2 circulating fluid compartments, the CP epithelium is involved in numerous exchange processes that either supply the brain with nutrients and hormones, or clear deleterious compounds and metabolites from the brain. Choroid plexuses also participate in neurohumoral brain modulation and neuroimmune interactions, thereby contributing greatly in maintaining brain homeostasis. Besides these physiological functions, the implication of choroid plexuses in pathological processes is increasingly documented. In this review, we focus on some of the novel aspects of CP functions in relation to brain development, transfer of neuro-humoral information, brain/immune system interactions, brain aging, and cerebral pharmaco-toxicology.

Choroid plexus recovery after transient forebrain ischemia: role of growth factors and other repair mechanisms

1. Transient forebrain ischemia in adult rats, induced by 10 min of bilateral carotid occlusion and an arterial hypotension of 40 mmHg, caused substantial damage not only to CA-1 neurons in hippocampus but also to epithelial cells in lateral ventricle choroid plexus. 2. When transient forebrain ischemia was followed by reperfusion (recovery) intervals of 0 to 12 hr, there was moderate to severe damage to many frond regions of the choroidal epithelium. In some areas, epithelial debris was sloughed into cerebrospinal fluid (CSF). Although some epithelial cells were disrupted and necrotic, their neighbors exhibited normal morphology. This patchy response to ischemia was probably due to regional differences in reperfusion or cellular metabolism. 3. Between 12 and 24 hr postischemia, there was marked restoration of the Na+, K+, water content, and ultrastructure of the choroid plexus epithelium. Since there was no microscopical evidence for mitosis, we postulate that healthy epithelial cells either were compressed together on the villus or migrated from the choroid plexus stalk to more distal regions, in order to "fill in gaps" along the basal lamina caused by necrotic epithelial cell disintegration. 4. Epithelial cells of mammalian choroid plexus synthesize and secrete many growth factors and other peptides that are of trophic benefit following injury to regions of the cerebroventricular system. For example, several growth factors are upregulated in choroid plexus after ischemic and traumatic insults to the central nervous system. 5. The presence of numerous types of growth factor receptors in choroid plexus allows growth factor mediation of recovery processes by autocrine and paracrine mechanisms. 6. The capability of choroid plexus after acute ischemia to recover its barrier and CSF formation functions is an important factor in stabilizing brain fluid balance. 7. Moreover, growth factors secreted by choroid plexus into CSF are distributed by diffusion and convection into brain tissue near the ventricular system, e.g., hippocampus. By this endocrine-like mechanism, growth factors are conveyed throughout the choroid plexus-CSF-brain nexus and can consequently promote repair of ischemia-damaged tissue in the ventricular wall and underlying brain.

Multidrug resistance protein 1 protects the choroid plexus epithelium and contributes to the blood-cerebrospinal fluid barrier

Multidrug resistance protein 1 (MRP1) is a transporter protein that helps to protect normal cells and tumor cells against the influx of certain xenobiotics. We previously showed that Mrp1 protects against cytotoxic drugs at the testis-blood barrier, the oral epithelium, and the kidney urinary collecting duct tubules. Here, we generated Mrp1/Mdr1a/Mdr1b triple-knockout (TKO) mice, and used them together with Mdr1a/Mdr1b double-knockout (DKO) mice to study the contribution of Mrp1 to the tissue distribution and pharmacokinetics of etoposide. We observed increased toxicity in the TKO mice, which accumulated etoposide in brown adipose tissue, colon, salivary gland, heart, and the female urogenital system. Immunohistochemical staining revealed the presence of Mrp1 in the oviduct, uterus, salivary gland, and choroid plexus (CP) epithelium. To explore the transport function of Mrp1 in the CP epithelium, we used TKO and DKO mice cannulated for cerebrospinal fluid (CSF). We show here that the lack of Mrp1 protein causes etoposide levels to increase about 10-fold in the CSF after intravenous administration of the drug. Our results indicate that Mrp1 helps to limit tissue distribution of certain drugs and contributes to the blood-CSF drug-permeability barrier.

Fibroblast growth factor and hydrocephalus

The immunohistochemical localization of basic fibroblast growth factor (bFGF) was studied in ventricular ependyma and choroid plexus of aged-matched normotensive and spontaneously hypertensive rats at different ages using a polyclonal antibody against bFGF. The bFGF-like immunoreactivity was observed in brain ependyma and choroid plexus of young and old normotensive rats. However, a progressive loss of immunoreactivity was observed with age in spontaneously hypertensive rats, that was associated with a progressive cerebroventricular dilation. These results show a new neuroendocrine anomaly to be added to the many others previously observed in this rat strain, when they develop hydrocephalus as they age.

The time-course of DNA fragmentation in the choroid plexus and the CA1 region following transient global ischemia in the rat brain. The effect of intra-ischemic hypothermia

The time-course of DNA fragmentation in the CA1 region of the hippocampus and the choroid plexus was studied following induction of transient forebrain ischemia under lethal normothermic (37 degrees C), or sublethal hypothermic (33 degrees C) conditions. Oligonucleosomal- and high-molecular-weight DNA fragmentation were analysed by conventional agarose gel electrophoresis and pulsed-field gel electrophoresis, respectively. DNA breaks were visualized by the terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridinetriphosphate nick-end labeling method. At 48 h of recovery following normothermic ischemia, in situ labeling of DNA breaks were widespread in medial CA1 and high-molecular-weight DNA cleavage was seen. In contrast, at the same time-point in lateral CA1, many pyknotic but few cells displaying in situ labeling of DNA breaks were observed. Major oligonucleosomal DNA fragmentation was not seen until 72 h of recovery. Following hypothermic ischemia, DNA fragmentation was absent in CA1. DNA fragmentation was seen in the choroid plexus at 24 h of recovery following normothermic ischemia, which was diminished by 48 h of recovery. In conclusion, oligonucleosomal and high-molecular-weight DNA fragmentation at 10-50 kilobase pairs, occur in CA1 after morphological signs, and acidophilia signifying neurodegeneration appear. DNA fragmentation and cell death in the choroid plexus precede neuronal death in CA1 and may play a causative role.

Biological reactions to cerebrospinal fluid shunt devices: a review of the cellular pathology

OBJECTIVE

To understand the interaction between cerebrospinal fluid shunt components and the brain and other tissues.

METHODS

A systematic review of the medical literature directly pertaining to shunt complications, and that dealing with tissues' reactions to implants in general, was conducted.

RESULTS

Vascularized pedicles of glial tissue or choroid plexus grow into ventricular catheters, primarily as a mechanical phenomenon. Cellular debris or blood can cause dysfunction of valve components. Chronic inflammation, which is nonspecific, might contribute to degradation of the components.

CONCLUSION

Care must be taken to prevent early entry of debris or blood into the shunt system. Ventricular collapse onto the shunt must be avoided. Refinement of manufacturing methods or modification of shunt materials could reduce the susceptibility of shunts to infection and improve longevity of the apparatus.

Isolated choroid plexus cysts and association with fetal aneuploidy in an unselected population

We sought to determine the relationship between an isolated choroid plexus cyst diagnosed antenatally and fetal aneuploidy in an unselected population at a district general hospital. Over a 5-year period all women attending for a detailed anomaly scan at 18-20 weeks' gestation were screened for evidence of a fetal choroid plexus cyst. All cases of choroid plexus cyst were recorded prospectively. The size, position and number of the cysts were noted and associated abnormalities seen on ultrasound were also recorded. Cases of choroid plexus cyst associated with fetal aneuploidy were noted. A total of 13,690 women were screened, and 84 cases of choroid plexus cyst were identified (0.6%). Of these, 41% underwent prenatal karyotyping by amniocentesis; 78 of 84 cases (93%) were isolated. Six had other markers for aneuploidy, and three of these fetuses had trisomy 18. All cases of isolated choroid plexus cyst resulted in chromosomally normal neonates. This was confirmed by either normal antenatal karyotype or postnatal examination by the pediatricians. The size, position and number of cysts did not appear to influence the risk of aneuploidy. We conclude that the risk of aneuploidy for a case of isolated choroid plexus cyst in an unselected population appears to be very low, and in this series was 0%. In this setting, we suggest detailed ultrasound examination is essential, rather than routine karyotyping.

Severe pathological crying after left anterior choroidal artery infarct. Reversibility with paroxetine treatment

BACKGROUND

There is increasing evidence that serotonergic neurotransmission may be damaged in poststroke pathological crying. A correlation between the clinical severity of pathological crying and the size of stroke-induced serotonergic pathway lesions is commonly accepted. We present a case of severe pathological crying after a limited left anterior choroidal artery territory infarction.

CASE DESCRIPTION

A right-handed 55-year-old man who was a heavy smoker was admitted to the hospital after a right hemiplegia of sudden onset. Clinical examination revealed a right global hemiplegia including the face and a right hemihypoesthesia. Cerebral CT scan and MRI showed an infarct in the retrolenticular part of the posterior limb of the left internal capsule extending upward into the posterior paraventricular corona radiata region. Transesophageal echocardiography revealed an atrial septal aneurysm of 15-mm excursion without associated patent foramen ovale. From the first day of admission, the patient exhibited very frequent and intense fits of pathological crying. Their persistence led to initiation of treatment with the selective serotonin reuptake inhibitor paroxetine on day 30. Complete and immediate resolution of pathological crying occurred 24 hours after onset of therapy. Follow-up examination at day 90 confirmed the absence of relapse of pathological crying.

CONCLUSIONS

We conclude that poststroke pathological crying in our patient may have been due to unilateral disruption of the capsular ascending projections of the serotonergic brain stem raphe nuclei. A small left-sided capsular lesion may have led to severe pathological crying. This disabling condition may be reversible with selective serotonin reuptake inhibitor therapy.

Serotonin2C receptors and serotonin2C receptor-mediated phosphoinositide hydrolysis in the brain of alcohol-preferring and alcohol-nonpreferring rats

To examine the role of serotonin2C (5HT2C) receptors in alcohol drinking behavior, the binding indices of 5HT2C receptors were determined in various brain regions of alcohol-preferring (P) and alcohol-nonpreferring (NP) rats. 5HT2C receptor-mediated phosphoinositide hydrolysis in the choroid plexus of P and NP rats was also determined. It was observed that the densities of 5HT2C receptors are significantly higher in the hippocampus, the amygdala, and the choroid plexus, but not in the cortex of P rats compared with NP rats. The Kd values of [3H]mesulergine binding to 5HT2C receptors were not different in these brain regions of P rats compared with NP rats. It was also observed that 5HT-stimulated [3H]inositol 1-phosphate formation was significantly higher in the choroid plexus of P rats compared with NP rats. The results of this study indicate that the numbers of 5HT2C receptors are higher in the hippocampus, the amygdala, and the choroid plexus, and that 5HT2C receptor-mediated phosphoinositide hydrolysis is more elevated in the choroid plexus of P rats compared with NP rats. Thus, it seems from these results that increased 5HT2C receptors may be involved in the genetic vulnerability to alcohol drinking behavior.

Choroid plexus arteriovenous malformations. A report of four pathologically proven cases and review of the literature

The clinical, radiological and pathological findings of four cases of primary intraventricular haemorrhage secondary to choroid plexus arteriovenous malformations (AVM) are described and the relevant literature reviewed. In three of the cases the diagnosis was confirmed or made at autopsy. The fourth case survived to undergo craniotomy followed by radiosurgery with excellent results. All AVMs originated in the choroid plexus of the lateral ventricle, and autopsy confirmation required a high degree of suspicion and the systematic microscopic examination of serial coronal sections of the ventricle with the clot in situ.

The syndrome of posterior choroidal artery territory infarction

Posterior choroidal artery (PChA) territory infarcts remain the least well-known type of thalamic infarcts. Our study of 10 personal cases, selected from 2,925 stroke patients admitted consecutively to a community-based primary care center, and 10 published cases of unilateral PChA territory infarct suggests that they can often be differentiated clinically from other thalamic infarcts. Patients with PChA territory infarct associated with superficial posterior cerebral artery territory infarct or with another infarct were excluded. Damage was characteristically limited to the lateral geniculate body, pulvinar, posterior thalamus, hippocampus, and parahippocampal gyros, without involvement of the upper midbrain and the anterior nucleus of thalamus. In lateral PChA territory infarct, the most common clinical manifestations included homonymous quadrantanopsia, with or without hemisensory loss and neuropsychological dysfunction (transcortical aphasia, memory disturbances). A homonymous horizontal sectoranopsia is exceptional but particularly suggestive of the involvement of the lateral geniculate body in this territory. Media] PChA territory infarct was less frequent. Its neurologic picture was dominated by eye movement disorders not particularly suggestive of thalamic involvement. Late disability was usually absent or slight, being related to pain and delayed abnormal movements. The most common stroke etiology was presumed small-vessel occlusive disease.

Choroid plexus compression of glossopharyngeal nerve in patients with glossopharyngeal neuralgia

Compression of the glossopharyngeal nerve by the lateral choroid plexus of the 4th ventricle protruding excessively through the foramen of Luschka may be at the basis of some forms of glossopharyngeal neuralgia. This condition was observed in four patients. In one case, an anterior compression of the 9th nerve by a megadolic vertebral artery was also present. The condition was resolved in all patients by separating the nerve from the plexus and transecting it at the level of the foramen of Luschka.

Morphological modifications of the choroid plexus in a rodent model of acute ventriculitis induced by gram-negative liquoral sepsis. Possible implications in the pathophysiology of hypersecretory hydrocephalus

Gram-negative bacterial infections of the central nervous system are generally associated with high morbidity and mortality rates. In patients with ventriculitis induced by gram-negative liquoral sepsis, a reduction in cerebrospinal fluid formation has been reported, suggesting that gram-negative ventriculitis is able per se to alter the normal functioning of the choroid plexus. The aim of the present study was to analyse, for the first time in the rat, the effects of acute ventriculitis on the ultrastructure of the choroid plexus. A simple and inexpensive experimental model of acute ventriculitis was developed: we injected into the cisterna magna of rats 10(3) CFU of live Escherichia coli, inducing septic ventriculitis without major neurological deficits. Histological examinations of rodent choroid plexus 24 h after the injection revealed patches of altered epithelium, with swollen and vacuolated ependymal cells associated with leukocyte infiltration. Electron microscopy demonstrated a reduced number of microvilli and flattening of the epithelial surface. These results (a) indicate that gram-negative septic ventriculitis is able to induce visible ultrastructural alterations of the choroid plexus which (b) are consistent with a picture of marked reduction of the functioning epithelial choroid plexus surface, and (c) highlight the potential usefulness of our rodent acute ventriculitis model for developing treatment modalities.

Hydrocephalus: is impaired cerebrospinal fluid circulation only one problem involved?

Hydrocephalus is a complex disease of the brain as a whole, and imbalance between cerebrospinal fluid (CSF) formation and absorption is not the sole mechanism involved in its pathophysiology. In the absence of a lymphatic system in the central nervous system, open communication between CSF and interstitial fluid (ISF) of the brain may contribute to maintaining homeostasis of the brain, keeping the microchemical environment in good balance. Membranes or cell layers separating CSF from ISF of the brain do not provide impermeability, so the CSF communicates with ISF across the ependymal layer and the pial surface of the brain. In contradiction of the classical theory, the CSF one may obtain at the cisterna magna, for instance, is different from the newly formed CSF out of the choroid plexus, because it has been modified by the free communication between CSF and ISF spaces as the CSF descends along the neural axis. Free flow of water and some smaller molecules provides a bidirectional movement of water and other materials, and this must play an important role in brain volume control. The significance of this role should not be overlooked in regard to the pathophysiology of hydrocephalus.

[Lateral ventricle choroid plexus papillomas in infants]

Choroid plexus papillomas are rare intracranial tumours occurring most frequently in children. In the period 1983-1988 in the neurosurgery department 10 infants were treated for choroid plexus papillomas. Their age was from 4 weeks to 12 months. The diagnosis was based on the results of ultrasonography and CT. Eight patients had shunts implanted for hydrocephalus. In most cases the histological examination demonstrated benign tumours. Radical removal of the lesion was done in 90% of cases, but, despite this, remote results were satisfactory in only 40% of cases.

The acute inflammatory response to lipopolysaccharide in CNS parenchyma differs from that in other body tissues

Acute inflammation is important for defence against infection, wound repair and the mediation of auto-immune tissue destruction. Myelomonocytic recruitment in acute inflammation is a stereotyped and non-specific response to tissue insult which begins within 2 h. In this study, lipopolysaccharide was injected into the murine CNS and other body sites of mice to compare the inflammatory responses. Doses of lipopolysaccharide which induced typical myelomonocytic recruitment in skin and the choroid plexus had no effect in CNS parenchyma, apart from the morphological activation of local resident microglia. The CNS parenchymal response proceeded independently of that in the choroid plexus-cerebral ventricles and had three distinct and unique phases. Initially there was minimal neutrophil exudation and a two-day delay before any increase in macrophage-microglial cell number. Next, there was a rapid increase in macrophage-microglial cell numbers during the third day, mainly due to recruitment of blood monocytes. During this phase, leukocyte recruitment was restricted to monocytes which rapidly adopted the arborized microglial phenotype. Monocytes migrated through an intact blood-brain barrier independent of changes in solute permeability. Finally, there was a florid myelomonocytic reaction predominantly in the white matter, one week after intracerebral injection of 2 micrograms lipopolysaccharide. At this time, the leukocyte reaction disrupted the blood-brain barrier, mononuclear phagocytes expressed macrophage morphology and abundant major histocompatibility complex Class II antigen, and T lymphocytes were present. Myelomonocytic entry into the CNS was partially inhibited by prior blockade of the type 3 complement receptor, known to mediate leukocyte adhesion to endothelium elsewhere. The processes which lead to rapid myelomonocytic recruitment in other tissues are absent in CNS parenchyma. Understanding the molecular mechanisms responsible could have considerable significance both for CNS pathophysiology as well as possible anti-inflammatory therapeutic application elsewhere in the body.

Risk factors for neuroleptic-induced movement disorders

Chronic neuroleptic therapy may be associated with the development of diverse movement disorders including Tardive dyskinesia (TD), Parkinsonism, dystonia, and akathisia in a subset of schizophrenic patients. It is presently unknown why only a proportion of neuroleptic-treated patients develop these movement disorders. In the following communication, we present a series of studies which demonstrate that the development of these movement disorders may be facilitated by certain risk factors including disturbances in pineal melatonin functions, diabetes mellitus, cognitive deficits, suicidal behavior, and disturbances in the functions of the choroid plexus. Recognition of these biological factors may prove useful in: (a) further understanding of the pathophysiology of these disorders, and (b) identifying patients at risk for these movement disorders.

The pineal gland in multiple sclerosis

Multiple sclerosis (MS) is a chronic demyelinating disease of unknown etiology. Clinical, neurochemical, and neuroradiological data implicate the pineal gland in the pathophysiology of MS. To investigate the relationship of MS to the pineal gland further, we surveyed the prevalence of pineal calcification (PC) on CT scan in a cohort of 29 MS patients (7 men, 22 women, mean age: 40.1 years, SD = 8.9) who were admitted consecutively to a neurological service for acute exacerbation of symptoms. For the purpose of comparison, we also surveyed the prevalence of choroid plexus calcification (CPC) in the sample. Twenty-one age and sex-matched neurological patients served as controls (5 men, 16 women, mean age: 37.0, SD = 9.2). PC was seen in 100% of MS patients, while 72.4% patients (N = 21) had CPC. In the control sample, PC was found in 42.8% (N = 9) and CPC in 28.5% (N = 6). Thus, the strikingly high prevalence of PC in MS provides indirect support for an association between MS and abnormalities of the pineal gland. Moreover, since pineal melatonin is involved in neuroimmunomodulation, we propose, for the first time, that abnormalities of pineal melatonin functions are implicated in the pathophysiology of the disease.

Vascular responses of choroid plexus during hypercapnia in rats

The response of blood flow to choroid plexus (CPBF) during hypercapnia is controversial. The goal of this study was to determine the effect of hypercapnia on CPBF in unanesthetized rats. Rats breathed air or a mixture of 5-8% CO2 in air, and CPBF was measured with [14C]isopropyliodoamphetamine and quantitative autoradiography. In hypercapnic rats [arterial PCO2 61.6 +/- 1.6 (SE) mmHg; n = 7] CPBF was similar to that of normocapnic control rats (525 +/- 39 ml.min-1.100 g-1; arterial PCO2 42.7 +/- 0.6 mmHg; n = 5). In contrast, blood flow to cerebral cortex increased 67% during hypercapnia. CPBF in normocapnic rats that were treated with phentolamine was similar to untreated normocapnic and hypercapnic rat CPBF. However, during hypercapnia, CPBF in phentolamine-treated rats increased 29%. Responses were similar in blood flow to choroid plexus of lateral, third, and fourth ventricles. Our findings indicate that hypercapnia has no effect on CPBF when alpha-adrenergic receptors are intact. In contrast, after blockade of alpha-adrenergic receptors, hypercapnia increases CPBF. These findings suggest that, during hypercapnia, levels of sympathetic activity or blood-borne catecholamines are increased that prevent increases in CPBF.

The treatment of childhood hydrocephalus by choroid plexus coagulation and artificial cerebrospinal fluid perfusion

The authors report their experience in the treatment of childhood hydrocephalus by endoscopic choroid plexus coagulation and post-operative ventricular perfusion with artificial CSF. The procedure was carried out on 23 children without mortality. In 12 cases (52%) the procedure was successful in controlling the hydrocephalus. The average follow-up was 2.3 years. Eleven cases (48%) required shunting which was done from 1 week to 13 months following the choroid plexus coagulation. As cure of the hydrocephalus was achieved in over half of the patients, the authors recommend the procedure as a first line treatment for childhood hydrocephalus.

Uptake and concentrations of calcium in rat choroid plexus during chronic hypo- and hypercalcemia

The choroid plexus has been implicated in the regulation of cerebrospinal fluid (CSF) [Ca], but little information is available concerning Ca transport by this epithelium. We determined the transfer coefficients for 45Ca uptake into choroid plexus from blood, as well as tissue [Ca], in weanling Fischer-344 rats fed low, normal, or high Ca diets for 8 weeks. Plasma [Ca] decreased by 45% with low Ca diet and increased by 25% with high Ca diet. Choroid plexus 45Ca uptake varied inversely with plasma [Ca]. This relation was due largely to changes in extracellular Ca binding rather than to entry from blood, as the transfer coefficient was independent of plasma [Ca]. The extracellular Ca distribution in choroid plexus, the intercept of a plot of tissue 45Ca distribution against time, was reciprocally related to plasma [Ca]. Changes in total cell [Ca] during hypercalcemia were equivalent to those in plasma, and in hypocalcemia were 70% of those in plasma. These findings indicate that regulation of CSF [Ca] does not involve saturable transport of Ca into the choroid epithelium from blood, and that the apical membrane of the choroid epithelium is involved in homeostasis of CSF [Ca].

Herpes zoster ophthalmicus and ipsilateral infarction in the territory of the anterior choroidal artery

We report a further case of retarded contralateral hemiplegia syndrome after herpes zoster ophthalmicus in which the motor deficit was caused by an ischemic infarction in the territory supplied by the anterior choroidal artery. We discuss the clinical and physiopathogenetic features of the case and consider the computed tomographic and neurological patterns of anterior choroidal infarction.

Alpha-atrial natriuretic peptide binding sites in the rat choroid plexus are increased in the presence of hydrocephalus

Specific alpha-rat atrial natriuretic peptide(1-28) [ANF-(99-126)] (rANP) binding sites in the choroid plexus of rats with kaolin-induced hydrocephalus were analyzed following incubation of related tissue sections with 125I-rANP, then using autoradiography and an image analysis coupled with computer-assisted micro-densitometry. The number of 125I-rANP binding sites in the choroid plexus of these rats was significantly higher, as compared to findings in the control rats, whereas no differences in the binding affinity were observed, 3 days and 3 weeks after the intracisternal injection of kaolin. The possibility that atrial natriuretic peptide may play a significant role in the function of cerebrospinal fluid production by interacting with specific, high affinity receptors in the rat choroid plexus has to be considered.

Cerebrospinal fluid transthyretin in multiple sclerosis

Transthyretin is an important choroid plexus-specific transport protein that has been reported to be both elevated and decreased in the CSF of multiple sclerosis patients. We report that CSF transthyretin levels are not altered in MS, indicating that choroid plexus function with respect to this protein is unaffected in this disease.

Choroid plexus papilloma: hydrocephalus and cerebrospinal fluid dynamics

Dynamics of the cerebrospinal fluid were measured pre- and postoperatively in a patient with a choroid plexus papilloma associated with hydrocephalus. The production rate was 0.35 ml/min, absorption 0.0057 ml/min H2O, and the critical opening pressure 196 mm H2O. Following removal of the tumor, these values were 0.32 ml/min, 0.0053 ml/min/mm H2O, and 105 mm H2O, respectively. It was concluded that no over-production of cerebrospinal fluid was present in this case. The hydrocephalus was due solely to obstruction of the fourth ventricle.

Rheumatoid disease with encephalopathy

A 63-year-old woman developed progressive rheumatoid disease complicated by a confusional state as well as persistent cerebrospinal fluid pleocytosis and hypoglycorrhachia. Neuropathological examination revealed extensive rheumatoid lesions in the cranial dura, falx, and choroid plexus. The choroid plexus has not been affected in any of the 16 previously reported cases of pathologically verified rheumatoid disease of the central nervous system. The findings in this patient support the observations of others regarding the role of the choroid plexus in development of CNS manifestations in systemic immune complex disease.