Diurnal Variation of Melatonin Concentration in the Cerebrospinal Fluid of Unanesthetized Microminipig

BACKGROUND/AIM

The aim of this study was to develop a method for sequentially collecting cerebrospinal fluid (CSF) from an unanesthetized microminipig, which shares many physiological and anatomical similarities with humans, such as diurnality, and investigate the diurnal variation of melatonin concentration in the CSF.

MATERIALS AND METHODS

A catheter was placed percutaneously into the subarachnoid space of an anesthetized animal, and the tip of the catheter was placed into the cisterna magna under X-ray. We then sequentially collected CSF at light-on and -off times from the unanesthetized animal for several weeks. After catheter placement, a period of one week or more was necessary to relieve the contamination of RBCs in the CSF.

RESULTS

A higher melatonin level in the CSF was noted during lights-off time, and the level was higher than that in the serum.

CONCLUSION

This model of sequential collection of CSF will contribute to research in brain functions.

CHARACTERISTICS OF GAMMA OSCILLATIONS INDUCED BY KAINATE PRESSURE EJECTION ON CA1 HIPPOCAMPUS OF MICE BRAIN SLICES IN SUBMERGED CHAMBERS

Aim - mostly, gamma oscillations are studied in interface-type chambers. The purpose of the presented investigation is to describe the characteristics of gamma oscillations induced in submerged chambers by kainite pressure ejection. Horizontal combined entorhynal-hippocampal slices 300-350 µm were prepared from young mice (P18-28). Gamma oscillations were induced by 1 mM kainite pressure ejection at the boundary of stratum radiatum and lacunosum-moleculare of area CA1. Field potential recordings were registered from the vicinity of kainite application. Induced CA1 local field potential (LFP) oscillations were brief (7.55±3.77 sec.) and had heterogeneous nature; they could be divided into three epochs: well developed initial part of oscillation, middle part with reduced gamma power and last part of the rhythm with sporadic immergence of sparse (3 to 5) gamma cycles. Generally, initial parts of oscillations had higher amplitude and frequency than the middle part of it. Induction of consecutive gamma oscillations did not depend on the duration of the time intervals between oscillations. Their amplitude was affected by the order of induction but not by time intervals between oscillations. Neither the frequency was affected by the order of induced activities in the same slice. However, comparatively lower frequency oscillations were recorded after long time intervals between gamma activities. Induction of CA1 gamma oscillations in submerged conditions will offer significant experimental advantage, like using patch-clamp techniques to study the mechanism of this activity.

Surface charge impact in nonsynaptic model of epilepsy in rat hippocampus

Decreasing of surface charge screening near voltage-gated ion channels via reduction of extracellular cation divalent ions provide potent mechanism of altering cellular excitability and seizure threshold. Spontaneous field potentials were recorded from horizontal brain slices of young Wistar rats (postnatal day 10-12). Extracellular registrations wereobtained from CA1 and CA3 area of hippocampus. For induction of nonsynaptic epileptiform activity slices were perfused with artificial cerebrospinal fluid with omitted Ca2+and Mg2+ ions. Effect of different Mg2+ concentration (1, 2, and 3mmol/l) on initial stage of nonsynaptic epileptiform discharges was studied. Our results suggest that the change in Mg2+ concentration dramatically affects the probability of induction of low-Ca2+seizure-like activity (SLA), providing evidence that Mg2+ can alter cerebral excitability by affecting the surface charge and supporting the idea that surface charge could be a pharmacological target for anti-epileptic treatment.

Pathogen Detection Using Frequency Domain Fluorescent Lifetime Measurements

OBJECTIVE

Inflammation of the meninges is a source of severe morbidity and therefore is an important health concerns worldwide. The conventional clinical microbiology approaches used today to identify pathogens suffer from several drawbacks and frequently provide false results. This research describes a fast method to detect the presence of pathogens using the frequency domain (FD) fluorescence lifetime (FLT) imaging microscopy (FLIM) system.

METHODS

The study included 43 individuals divided into 4 groups: 9 diagnosed with different types of bacteria; 16 diagnosed with different types of viruses; 5 healthy samples served as a control; and 12 samples were negative to any pathogen, although presenting related symptoms. All samples contained leukocytes that were extracted from the cerebrospinal fluid (CSF) and were subjected to nuclear staining by 4', 6-diamidino-2-phenylindole (DAPI) and FLT analyses based on phase and amplitude crossing point (CRPO).

RESULTS

Using notched boxplots, we found differences in 95% probability between the first three groups through different notch ranges (NR). Pathogen samples presented a longer median FLT (3.28 ns with NR of 3.24-3.32 ns in bacteria and 3.18 ns with NR of 3.16-3.21 ns in viruses) compared to the control median FLT (2.65 ns with NR of 2.63-2.67 ns). Furthermore, we found that the undetected forth group was divided into two types: a relatively normal median FLT (2.72 ns with NR of 2.68-2.76 ns) and a prolonged FLT (3.22 ns with NR of 3.17-3.27 ns).

CONCLUSION

FLT measurements can differentiate between control and pathogen by the CRPO method.

SIGNIFICANCE

The FD-FLIM system can provide a high throughput diagnostic technique that does not require a physician.

The Effect of Electro-Convulsive Therapy on Spinal Fluid Constituents

During the course of an investigation of the effectiveness of various components of electric convulsive therapy in the treatment of hospitalized psychiatric patients (Brill et al., 1957, 1959) observations were made on the spinal fluid concentrations of cations and total protein before and after treatment. The possibility existed that alterations in brain function and structure (which are believed by many to occur during a course of electro-convulsive treatment, and to be responsible for improvement in patients receiving such treatment) might be associated with, or reflected by measurable changes in the cerebral spinal fluid.

Cerebrospinal Fluid - A Clinicopathologic Analysis

CONTEXT AND OBJECTIVE

This study aims to emphasize the importance of an appropriate CSF examination in patients of suspected CNS disease and the necessity of correlating it with the clinico-radiologic findings which will help in early diagnosis of CNS diseases and guide the further management of the disease.

DESIGN

In this 2 year study, 215 CSF samples from patients with clinically suspected diseases of the CNS were studied. The CSF samples were analyzed for gross examination, protein, sugar, adenosine deaminase (ADA) levels, microscopic examination and microbiologic examination. Culture was performed an all cases. A cytospin examination was done where malignancy (primary/metastasis) was suspected.

RESULTS

Of the 215 samples analyzed, 97(45.1%) were found to have abnormal CSF findings. The maximum number of abnormal CSF samples were seen in the adolescents and adults (56.7%) age group. Very high protein levels were seen with bacterial, tuberculous and parasitic meningitis whereas fungal and viral meningitis showed moderate elevation of proteins. CSF ADA levels were raised in cases of tuberculous meningitis with mean value of 20.9 IU/L whereas all other types of meningitis showed normal level of ADA. A total of 3 cases of IVH and 2 cases of demyelinating disease were found in our study. Malignant cells were detected in two cases.

CONCLUSION

Thus, a study of CSF is vital as it provides an invaluable diagnostic window to the central nervous system atmosphere. A timely and appropriate analysis of CSF can help the clinician to direct the line of treatment and enhance patient care as well as reduce morbidity and mortality.

Modifications in acute phase and complement systems predict shifts in cognitive status of HIV-infected patients

BACKGROUND

The prevalence of HIV-associated neurocognitive disorders (HAND) has not changed considerably in the last two decades. Potent antiretroviral therapy has shifted the severity of HAND to milder phenotypes, but excess morbidity and mortality continue to be associated with HAND. Changes in numerous markers of immune function, inflammation, and cellular stress have been repeatedly associated with HAND, but the underlying systems that drive these changes have not been identified.

METHOD

In this study, we used systems informatics to interrogate the cerebrospinal fluid proteomic content of longitudinal samples obtained from HIV-infected adults with stably unimpaired, stably impaired, worsening, or improving neurocognitive performance.

RESULTS AND CONCLUSION

The patterns of change in cerebrospinal fluid protein content implicated the induction of acute phase and complement systems as important regulators of neurocognitive status. Worsening neurocognitive performance was preceded by induction of acute phase and complement systems, whereas improving neurocognitive performance was preceded by a downregulation of these systems.

Elucidation of the complex metabolic profile of cerebrospinal fluid using an untargeted biochemical profiling assay

We sought to determine the molecular composition of human cerebrospinal fluid (CSF) and identify the biochemical pathways represented in CSF to understand the potential for untargeted screening of inborn errors of metabolism (IEMs). Biochemical profiles for each sample were obtained using an integrated metabolomics workflow comprised of four chromatographic techniques followed by mass spectrometry. Secondarily, we wanted to compare the biochemical profile of CSF with those of plasma and urine within the integrated mass spectrometric-based metabolomic workflow. Three sample types, CSF (N=30), urine (N=40) and EDTA plasma (N=31), were analyzed from retrospectively collected pediatric cohorts of equivalent age and gender characteristics. We identified 435 biochemicals in CSF representing numerous biological and chemical/structural families. Sixty-three percent (273 of 435) of the biochemicals detected in CSF also were detected in urine and plasma, another 32% (140 of 435) were detected in either plasma or urine, and 5% (22 of 435) were detected only in CSF. Analyses of several metabolites showed agreement between clinically useful assays and the metabolomics approach. An additional set of CSF and plasma samples collected from the same patient revealed correlation between several biochemicals detected in paired samples. Finally, analysis of CSF from a pediatric case with dihydropteridine reductase (DHPR) deficiency demonstrated the utility of untargeted global metabolic phenotyping as a broad assessment to screen samples from patients with undifferentiated phenotypes. The results indicate a single CSF sample processed with an integrated metabolomics workflow can be used to identify a large breadth of biochemicals that could be useful for identifying disrupted metabolic patterns associated with IEMs.

Modification in CSF specific gravity in acutely decompensated cirrhosis and acute on chronic liver failure independent of encephalopathy, evidences for an early blood-CSF barrier dysfunction in cirrhosis

Although hepatic encephalopathy (HE) on the background of acute on chronic liver failure (ACLF) is associated with high mortality rates, it is unknown whether this is due to increased blood-brain barrier permeability. Specific gravity of cerebrospinal fluid measured by CT is able to estimate blood-cerebrospinal fluid-barrier permeability. This study aimed to assess cerebrospinal fluid specific gravity in acutely decompensated cirrhosis and to compare it in patients with or without ACLF and with or without hepatic encephalopathy. We identified all the patients admitted for acute decompensation of cirrhosis who underwent a brain CT-scan. Those patients could present acute decompensation with or without ACLF. The presence of hepatic encephalopathy was noted. They were compared to a group of stable cirrhotic patients and healthy controls. Quantitative brain CT analysis used the Brainview software that gives the weight, the volume and the specific gravity of each determined brain regions. Results are given as median and interquartile ranges and as relative variation compared to the control/baseline group. 36 patients presented an acute decompensation of cirrhosis. Among them, 25 presented with ACLF and 11 without ACLF; 20 presented with hepatic encephalopathy grade ≥ 2. They were compared to 31 stable cirrhosis patients and 61 healthy controls. Cirrhotic patients had increased cerebrospinal fluid specific gravity (CSF-SG) compared to healthy controls (+0.4 %, p < 0.0001). Cirrhotic patients with ACLF have decreased CSF-SG as compared to cirrhotic patients without ACLF (-0.2 %, p = 0.0030) that remained higher than in healthy controls. The presence of hepatic encephalopathy did not modify CSF-SG (-0.09 %, p = 0.1757). Specific gravity did not differ between different brain regions according to the presence or absence of either ACLF or HE. In patients with acute decompensation of cirrhosis, and those with ACLF, CSF specific gravity is modified compared to both stable cirrhotic patients and healthy controls. This pattern is observed even in the absence of hepatic encephalopathy suggesting that blood-CSF barrier impairment is manifest even in absence of overt hepatic encephalopathy.

[Biomarkers for dementia and other neurodegenerative diseases : Current developments]

Cerebrospinal fluid-based neurochemical dementia diagnostics (CSF-NDD) support the early and differential diagnosis of dementia, most importantly the diagnosis of early or preclinical Alzheimer's dementia (AD). Meanwhile CSF-NDD are now recommended for improved exclusion and positive diagnostics of AD by the German national neuropsychiatry S3 dementia guidelines ( www.DGPPN.de ). Meta-analyses of independent international multicenter studies have shown that a combined CSF analysis of amyloid-beta 1-42 (Aβ 1-42, decreased), total tau proteins (increased) and phospho-tau proteins (increased) offers a sensitivity and specificity of 80-90 % for the early and differential diagnosis of AD (AD versus all other). Generally, CSF-NDD should be combined with blood-based routine diagnostics and should be part of routine CSF diagnostics, e. g. cell count and cell differentiation (if applicable), intrathecal antibody synthesis and blood-CSF barrier analysis. The CSF-NDD are most valuable for the improved differentiation between reversible dementia syndromes and irreversible neurodegenerative dementia, e. g. cognitive deficits due to late onset depression (pseudodementia due to depression) or AD. Combined with extended psychometric neuropsychological evaluation and neuroimaging methods, such as magnetic resonance imaging (MRI), dopamine transporter scanning (DaTscan) by single photon emission computed tomography (SPECT), 18F-fluorodeoxyglucose positron emission tomography (glucose-PET) and amyloid-PET, CSF-NDD also significantly improve the differential diagnostics within the heterogeneous group of primary neurodegenerative dementias. Meanwhile, several independent studies have indicated that the Aβ 1-42:Aβ 1-40 ratio is superior to the determination of Aβ 1-42 alone. Currently, several international research initiatives have been launched to further harmonize and optimize preanalytical procedures and CSF-NDD biomarker assays.

Experimental evaluation of new chitin-chitosan graft for duraplasty

Natural materials such as collagen and alginate have promising applications as dural graft substitutes. These materials are able to restore the dural defect and create optimal conditions for the development of connective tissue at the site of injury. A promising material for biomedical applications is chitosan-a linear polysaccharide obtained by the deacetylation of chitin. It has been found to be nontoxic, biodegradable, biofunctional and biocompatible in addition to having antimicrobial characteristics. In this study we designed new chitin-chitosan substitutes for dura mater closure and evaluated their effectiveness and safety. Chitosan films were produced from 3 % of chitosan (molar mass-200, 500 or 700 kDa, deacetylation rate 80-90%) with addition of 20% of chitin. Antimicrobial effictively and cell viability were analysed for the different molar masses of chitosan. The film containing chitosan of molar mass 200 kDa, had the best antimicrobial and biological activity and was successfully used for experimental duraplasty in an in vivo model. In conclusion the chitin-chitosan membrane designed here met the requirements for a dura matter graft exhibiting the ability to support cell growth, inhibit microbial growth and biodegradade at an appropriate rate. Therefore this is a promising material for clinical duroplasty.

Systematic development of small molecules to inhibit specific microscopic steps of Aβ42 aggregation in Alzheimer's disease

The aggregation of the 42-residue form of the amyloid-β peptide (Aβ42) is a pivotal event in Alzheimer's disease (AD). The use of chemical kinetics has recently enabled highly accurate quantifications of the effects of small molecules on specific microscopic steps in Aβ42 aggregation. Here, we exploit this approach to develop a rational drug discovery strategy against Aβ42 aggregation that uses as a read-out the changes in the nucleation and elongation rate constants caused by candidate small molecules. We thus identify a pool of compounds that target specific microscopic steps in Aβ42 aggregation. We then test further these small molecules in human cerebrospinal fluid and in a Caenorhabditis elegans model of AD. Our results show that this strategy represents a powerful approach to identify systematically small molecule lead compounds, thus offering an appealing opportunity to reduce the attrition problem in drug discovery.

Influence of pneumatic tube system transport on routinely assessed and spectrophotometric cerebrospinal fluid parameters

BACKGROUND

Pneumatic tube systems (PTS) are widely used in many hospitals. Using PTS reduces turnaround time (TAT) and can improve patients' outcome.

METHODS

We investigated whether clinically significant differences could be observed in CSF samples transported by pneumatic tube in comparison with samples transported by hand. Two aliquots from one sample were sent by PTS and by hand from the department of neurology or neurosurgery and compared.

RESULTS

Routine cytological and biochemical assessment was compared in 27 cases. There were no statistically significant changes (transport by hand vs. PTS) in glucose levels [data are expressed as median (minimum-maximum)] at 3.7 (2.5-8.6) mmol/L vs. 3.6 (2.7-8.6) mmol/L, p=0.96 or lactate levels at 1.8 mmol/L (1.1-5.5) vs. 1.8 mmol/L (1.1-5.4). We observed a statistically significant decline in total protein levels in samples transported by PTS at 0.56 g/L (0.19-4.29) vs. 0.49 g/L (0.18-4.3), p=0.008. We observed no changes in erythrocyte count at 5/μL (0-40,000) vs. 5/μL (0-40,106), mononuclear cells at 2/μL (1-145) vs. 3/μL (1-152), or polynuclear cells at 0/μL (0-235) vs. 0/μL (0-352). Spectrophotometric examination was performed in 20 cases. There were no statistically significant differences (transport by hand vs. transport by PTS) in NOA at 0.002 (0.001-1.537) vs. 0.001 (0.001-1.528), p=0.95 or NBA at 0.001 (0.001-0.231) vs. 0.001 (0.001-0.276), p=0.675. Samples transported by PTS were delivered faster than samples transported by courier (transport by hand vs. PTS) at 25 min (10-153) vs. 15 min (4-110), p=0.002.

CONCLUSIONS

We found no significant changes in glucose, lactate levels and in any of the cytological parameters assessed, nor were statistically significant changes observed in the spectrophotometric parameters. We found a statistically significant decrease in total protein levels in samples transported by PTS. Transport by PTS can be faster than transport by hand.

Digital Detection of Exosomes by Interferometric Imaging

Exosomes, which are membranous nanovesicles, are actively released by cells and have been attributed to roles in cell-cell communication, cancer metastasis, and early disease diagnostics. The small size (30-100 nm) along with low refractive index contrast of exosomes makes direct characterization and phenotypical classification very difficult. In this work we present a method based on Single Particle Interferometric Reflectance Imaging Sensor (SP-IRIS) that allows multiplexed phenotyping and digital counting of various populations of individual exosomes (>50 nm) captured on a microarray-based solid phase chip. We demonstrate these characterization concepts using purified exosomes from a HEK 293 cell culture. As a demonstration of clinical utility, we characterize exosomes directly from human cerebrospinal fluid (hCSF). Our interferometric imaging method could capture, from a very small hCSF volume (20 uL), nanoparticles that have a size compatible with exosomes, using antibodies directed against tetraspanins. With this unprecedented capability, we foresee revolutionary implications in the clinical field with improvements in diagnosis and stratification of patients affected by different disorders.

Biofouling-Resistant Impedimetric Sensor for Array High-Resolution Extracellular Potassium Monitoring in the Brain

Extracellular potassium concentration, [K⁺]o, plays a fundamental role in the physiological functions of the brain. Studies investigating changes in [K⁺]o have predominantly relied upon glass capillary electrodes with K⁺-sensitive solution gradients for their measurements. However, such electrodes are unsuitable for taking spatio-temporal measurements and are limited by the surface area of their tips. We illustrate seizures invoked chemically and in optogenetically modified mice using blue light exposure while impedimetrically measuring the response. A sharp decrease of 1-2 mM in [K⁺]o before each spike has shown new physiological events not witnessed previously when measuring extracellular potassium concentrations during seizures in mice. We propose a novel approach that uses multichannel monolayer coated gold microelectrodes for in vivo spatio-temporal measurements of [K⁺]o in a mouse brain as an improvement to the conventional glass capillary electrode.

Drug concentrations in the serum and cerebrospinal fluid of patients treated with norvancomycin after craniotomy

Intracranial infection by gram-positive cocci is commonly found after craniotomy. Norvancomycin was independently developed in China, and had demonstrated therapeutic capability against gram-positive infection. This study investigated the serum and cerebrospinal fluid (CSF) concentrations in patients that received intravenous injection of norvancomycin after craniotomy. Patients with an indwelling catheter in the operational area/ventricle after craniotomy were administered norvancomycin by two approaches: (1) The conventional group consisted of 14 cases that were infused with 0.8 g norvancomycin for 1 h, every 12 h; (2) The continuous administration group consisted of 14 cases that were infused with 0.8 g norvancomycin for 1 h, and then another 0.4 g for 11 h with extended infusion, followed by continuous infusion of 0.4 g norvancomycin for 12 h. Samples of serum and CSF were collected at different time-points to measure norvancomycin levels after administration. In the conventional and continuous administration groups, the peak serum concentrations of norvancomycin were 55.52 ± 26.04 and 59.22 ± 41.88 mg/L, respectively, while those at 24 h were 8.21 ± 6.04 and 8.01 ± 4.17 mg/L, respectively. Meanwhile, peak CSF concentrations were 16.31 ± 11.15 and 8.82 ± 8.91 mg/L, respectively, while those at 24 h were 6.12 ± 2.34 and 6.24 ± 4.38 mg/L, respectively. This preliminary study showed that for the early administration of standard doses of norvancomycin post-neurosurgery, the CSF concentration in both the conventional and continuous administration groups reached or exceeded the 90 % minimum inhibitory concentration (MIC₉₀, 2 mg/L) of target bacteria such as methicillin-resistant Staphylococcus aureus (MRSA).

National audit of cerebrospinal fluid testing

Background: UK National External Quality Assessment Service (NEQAS) Specialist Advisory Group for EQA of CSF Proteins and Biochemistry was interested in current practice for the biochemical investigation of cerebrospinal fluid (CSF) in the UK.

Methods: A questionnaire was sent to laboratories via regional audit committees and the results collated.

Results: Most laboratories were analysing CSF in a satisfactory manner. There was some variation in the reference ranges used for glucose, protein and lactate. There was concern about the rejection policies of some laboratories on these unrepeatable samples and the wavelengths used to measure bilirubin. The survey revealed the lack of spectrophotometric scanning for haem pigments and bilirubin in some hospitals.

Conclusions: The current practice for the measurement of CSF samples in the UK is satisfactory in most laboratories responding to the questionnaire. National agreement on reference ranges for glucose, protein and lactate should be achievable. Those performing spectrophotometric scanning of the CSF were doing so in concordance with the national guidelines. Some hospitals in the UK may not have responded to the questionnaire because they did not offer spectrophotometric scanning.

Semi-automated image analysis of gel electrophoresis of cerebrospinal fluid for oligoclonal band detection

Detection of oligoclonal electrophoretic bands in cerebrospinal fluid (CSF) is an important diagnostic tool for Multiple Sclerosis (MS). Electrophoretic profiles are difficult to interpret due to low contrast and artefacts. A semi-automated method to ease analysis and to reduce subjectivity is presented. The method sequentially converts color images to grayscale, realigns bands, removes artifacts, then converts 2D images to a signal, before detecting, thresholding and editing peaks to optimize profiles. Such treated profiles (21 positive and 15 negative) are compared to ground truth analysis of an expert biologist. 16 profiles over 21 are well detected positive and 12 profiles over 15 are detected negative, results seem similar to inter-experts variability reported in literature.

Marked inflammation in catastrophic longitudinal myelitis associated with systemic lupus erythematosus

Catastrophic longitudinal myelitis is an extremely rare neurologic manifestation of collagen vascular disease, described heretofore in 11 cases of SLE and 1 of Sjogren's Syndrome. This report documents markedly abnormal and worsening CSF findings on sequential CSF examinations over a period of three days (WBC >1500 cells/μL, >80% neutrophils, markedly elevated protein, and extremely low glucose levels) in the absence of infection. These abnormalities cleared rapidly with institution of immunosuppressive therapy so that a third CSF exam done within three days revealed almost complete normalization of CSF values. These findings suggest that in some cases of CLM a strong inflammatory component may be present, while in others, other pathogenic factors may predominate. Lupus (2007) 16, 823—826.

Utility of High-Performance Liquid Chromatography in the Characterization of Iatrogenic Sodium Diatrizoate–Induced Seizures in a Horse

Diagnostic evaluation of a mildly ataxic young gelding Quarterhorse included a contrast myelogram. Unfortunately, sodium diatrizoate was inappropriately administered by intrathecal injection resulting in severe unrelenting seizure activity and necessitated the destruction of the animal. The contrast agent was identified by analyzing cerebrospinal fluid by high-performance liquid chromatography and confirmed with probe mass spectrometric analysis. This contrast agent is highly ionic, has high osmolarity, and also blocks neurotransmission at specific receptors; for these reasons it is contraindicated for use in myelography. This is the first report of intrathecal administration of this agent in a horse, although there has been a previous report of similar untoward reactions in a dog, and numerous cases have been reported in humans.

Development of a Percutaneous Cerebrospinal Fluid Collection Technique in F-344 Rats and Evaluation of Cell Counts and Total Protein Concentrations

A simple technique for cerebrospinal fluid (CSF) collection was developed in F-344 rats. Cell counts and total protein concentrations were evaluated to assess sample quality. While the 50 to 70 μL samples of CSF collected on three different days showed a progressive decrease in the total erythrocyte and nucleated cell counts, no significant changes were observed in the total protein concentrations. Progressive decreases in the total erythrocyte count correlated positively with the decreases in volume of CSF collected. Our data suggest that collection of less than 50 μL of CSF will give a better quality of CSF in F-344 rats. This is the first report of cellular and protein parameters in the CSF of F-344 rats.

Method of intracranial pressure monitoring and cerebrospinal fluid sampling in swine

Cerebral oedema and encephalopathy have been noted to occur frequently in patients severely ill or dying after trauma, ischaemia, infections or even metabolic disorders. The objective of the present study was to establish continuous monitoring of the intracranial pressure (ICP) and sampling of cerebrospinal fluid (CSF) for further investigations in swine.

ICP monitoring was established in eight pigs by using a ventricular drainage system, implemented after paramedian trepanation of the os frontale. CSF and serum samples were taken for measurement of the levels of glucose and protein.

Operating time was 21±8 min for the trepanation until ICP monitoring was performed. No complications occurred during surgery. Continuous monitoring of ICP and CSF sampling was easy to perform, and without any side-effects in any animal. At autopsy, no iatrogenic lesions were found and monitoring catheters were still in place.

For several types of research requiring ICP monitoring and sampling of CSF, this method can be used successfully.