Intraperitoneal propofol and propofol fentanyl, sufentanil and remifentanil combinations for mouse anaesthesia

The combination of propofol and a rapid-acting opioid, such as fentanyl, sufentanil or remifentanil, is a relatively safe, total intravenous anaesthesia technique, commonly used in humans and which has been investigated in laboratory animals. The objective of this study was to evaluate these combinations for anaesthesia of mice by the intraperitoneal (i.p.) route. Sixty-seven mice, divided into groups of four, were used to test 28 combinations of propofol alone and propofol with fentanyl, sufentanil or remifentanil administered i.p. The dose ranges of drugs studied were propofol 50-200 mg/kg, fentanyl 0.2-0.4 mg/kg, sufentanil 0.05-0.1 mg/kg and remifentanil 0.2-1.0 mg/kg. The loss of righting reflex (RR) and the loss of pedal withdrawal reflex (PWR) were recorded along with the duration and quality of recovery. The results obtained in these studies were unpredictable. The same dose combinations of propofol and opioids were associated with different responses in different individuals. Higher doses did not induce loss of RR and PWR in all animals and were associated with high mortality rates. An adequate hypnotic level was only observed with higher doses of propofol. The synergistic effect of propofol and the opioids was not sufficient to allow surgical procedures. Animals that reached PWR loss showed tail rigidity, shaking limbs and scratched their heads with their forefeet. Higher opioid doses induced respiratory depression and higher death rates. The inconsistency between and within groups may be associated with the i.p. route. The results reported here show that the i.p. route is not appropriate for mouse anaesthesia using propofol alone or in combination with fentanyl, sufentanil or remifentanil.     

Transferrin in fetal sheep cerebrospinal fluid and plasma during gestation

1. Transferrin concentrations in fetal sheep CSF and plasma have been estimated between 31 and 125 days gestation and in the adult, using a radial immunodiffusion assay. 2. The plasma concentration was lowest (183 +/- 35 mg/100 ml) in the earliest fetuses examined (31 days). It increased to over 350 mg/100 ml by 35 days; thereafter it was around the adult value (580 mg/100 ml). 3. In CSF the transferrin concentration increased from 43 +/- 10 mg/100 ml at 31 days to a maximum of 163 +/- 14 mg/100 ml at 40 days gestation after which it decreased considerably to 6.1 +/- 0.7 mg/100 ml at 125 days and was even lower in the adult (1.1 +/- 0.2 mg/100 ml). 4. CSF: plasma ratios for transferrin especially when compared with those of other plasma proteins, are not compatible with passive leakage of protein from blood to CSF in the developing brain. The results may be explained by specific transfer of proteins into CSF but synthesis by the choroid plexus or brain has not been excluded.     

Gas chromatography-mass spectrometric assay for propofol in cerebrospinal fluid of traumatic brain patients

A sensitive gas chromatography-mass spectrometry method for measuring propofol in cerebrospinal fluid is described, validated and applied to four patients after traumatic brain injury. The limit of quantitation was 2 microg/L using a volume of 0.5 mL. The inter- and intra-assay coefficients of variation were 5.9 and 5.1%, respectively. The assay covers the linear concentration range of 2-50 microg/L, which is relevant in clinical pharmacokinetic studies when propofol is used in the Intensive Care Unit as a sedative agent or to lower the intracranial pressure.     

Plasma and cerebrospinal fluid concentration of neuropeptide Y, serotonin, and catecholamines in patients under propofol or isoflurane anesthesia

Propofol is a widely used anesthetic for both induction and maintenance of anesthesia during surgery. A strong feeling of hunger has been reported during the early recovery period after propofol anesthesia. We have investigated the effect of propofol on appetite in 10 patients undergoing a craniotomy and in parallel measured neuropeptide Y (NPY), catecholamines, and serotonin levels in the cerebrospinal fluid and plasma during anesthesia. Ten patients anesthetized with a volatile agent (isoflurane) served as a control group. Plasma NPY and catecholamines levels were not affected by surgery at any time. We observed a strong increase in NPY concentrations in the cerebrospinal fluid independently of the anesthetic technique agent used, whereas catecholamines were unchanged. We found that serotonin concentrations decreased significantly in the plasma (but not in the cerebrospinal fluid) of patients treated by propofol when compared with the control group; this decrease was associated with an increase of hunger early postoperatively. We concluded that the proappetite effect of propofol is mediated through a decrease of serotonin at the peripheral level.     

Proteomics analysis of human cerebrospinal fluid

Cerebrospinal fluid (CSF) is secreted from several different central nervous system (CNS) structures, and any changes in the CSF composition will accurately reflect pathological processes. Proteomics offers a comprehensive bird's eye view to analyze CSF proteins at a systems level. This paper reviews the variety of analytical methods that have been used for proteomics analysis of CSF, including sample preparation, two-dimensional liquid and gel electrophoresis, mass spectrometry, bioinformatics, and non-gel methods. The differentially expressed CSF proteins that have been identified by proteomics methods are discussed.     

A gas chromatography-mass spectrometry method for the quantitative analysis of melatonin in plasma and cerebrospinal fluid

A method has been developed for the quantitative analysis of melatonin in human plasma and cerebrospinal fluid. The technique involves a simple one-step extraction with chloroform and conversion of the melatonin in the extract to its N-trimethylsilyl derivative, which is then measured by means of high-sensitivity gas chromatography—mass spectrometry. Intra-assay precision for triplicate samples at the 20-pg/ml level was better than 20%, while the interassay precision for separate determinations made over the course of a week was better than 18%. In a series of human plasma samples taken over several times during a 24-hr period, a significant increase in melatonin level was noted during the hours of darkness.     

Proteins in cerebrospinal fluid and plasma of fetal rats during development

Rat mammary epithelial tumor cells from the line Rama 25 can grow into three-dimensional, multicellular structures when cultured on floating collagen gels. These structures include branching tubules reminiscent of ducts in glands, and the production of the tubules is studied here as a model of glandular morphogenesis. The cell line contains cells of two types which can be cloned and grown separately. Tubules are formed by neither cell type alone, but by combinations. The behavior of the two cell types suggests a mechanism for the growth of glands.     

Effect of chronic maternal hyperkalaemia on plasma, cerebrospinal fluid and brain interstitial fluid potassium in developing rats

Plasma hyperkalaemia was induced in pregnant and lactating rats using a high potassium diet. Fetuses of high-K-diet mothers showed no increase in the potassium concentration [( K+]) of plasma, cerebrospinal fluid (CSF) and brain interstitial fluid, presumably due to placental control. Neonates from high-K-diet rats did show an increase in plasma [K+] but this increase was very small and there was no increase in CSF or interstitial fluid [K+]. Maternal milk [K+] was not affected by plasma hyperkalaemia. Weanling rats fed the high-K diet directly showed marked plasma hyperkalaemia but no increase in CSF or interstitial fluid [K+]. Thus, prior to weaning, a relatively stable plasma [K+] is maintained by maternal influence reducing the need for direct brain fluid K+ regulation.     

Oxytocin in the cerebrospinal fluid and plasma of pregnant and nonpregnant subjects

The oxytocin concentration in the cerebrospinal fluid (CSF) and plasma of pregnant women at term with and without labor pain were measured by radioimmunoassay and compared with those of non-pregnant women of matched age. The oxytocin concentrations in the CSF were 4.9 +/- 4.1 microU/ml (mean +/- S.D.) in pregnant women with labor pain, 4.1 +/- 2.4 microU/ml in those without labor pain and 4.0 +/- 2.8 microU/ml in nonpregnant women, and the oxytocin concentrations in the plasma of these subjects were 45.2 +/- 19.6, 17.1 +/- 22.2 and 7.0 +/- 5.3 microU/ml, respectively. Thus the oxytocin level in the CSF did not change appreciably even when the level in the plasma was raised in the pregnant women with labor pain. These findings suggest that oxytocin does not penetrate the blood-brain barrier, and that oxytocin in the CFS has little or no central role in parturition in women.     

Amyloid-beta is an antioxidant for lipoproteins in cerebrospinal fluid and plasma

Amyloid-beta (Abeta) peptide, a major constituent of senile plaques and a hallmark of Alzheimer's disease (AD), is normally secreted by neurons and can be found in low concentrations in cerebrospinal fluid (CSF) and plasma, where it is associated with lipoproteins. However, the physiological role of Abeta secretion remains unknown. Here we show that at the concentrations measured in biological fluids (0.1-1.0 nM), Abeta(1-40) strongly inhibits autooxidation of CSF lipoproteins and plasma low density lipoprotein (LDL). At higher concentrations of the peptide its antioxidant action was abolished. Abeta(1-40) also inhibited copper-catalyzed LDL oxidation when added in molar excess of copper, but did not influence oxidation induced by an azo-initiator. Other Abeta peptides also possessed antioxidant activity in the order Abeta(1-40) > Abeta(1-42) > Abeta(25-35), whereas Abeta(35-25) was inactive. These data suggest that Abeta(1-40) may act as a physiological antioxidant in CSF and plasma lipoproteins, functioning by chelating transition metal ions.     

Detection and interpretation of 8-oxodG and 8-oxoGua in urine,plasma and cerebrospinal fluid

Background

DNA and RNA oxidations have been linked to diseases such as cancer, arteriosclerosis, neurodegeneration and diabetes. The prototype base modification studied is the 8-hydroxylation of guanine. DNA integrity is maintained by elaborate repair systems and RNA integrity is less studied but relies mainly on degradation.

Scope of review

DNA and RNA oxidations are measured by very similar techniques. The scope of this review is to highlight the preferred methods of measurement of oxidized nucleic acid metabolites, to highlight novel findings particularly in RNA oxidation, and to present the interpretation of the measurements.

Major conclusions

Tissue levels are snap-shots of the level in a specific organ or cell system and reflect the balance between formation rate and elimination rate (repair), and must be interpreted as such. Urinary excretion is a global measure of oxidative stress in an organism and is therefore best suited for situations or diseases where large parts or the entire organism is stressed by oxidation. It represents the body average rate by which either RNA or DNA is oxidized and is interpreted as oxidative stress. Oxidations of RNA and DNA precursors have been demonstrated and the quantitative importance is debated.

General significance

Careful experimental designs and appropriate choice of methodology are paramount for correct testing of hypotheses related to oxidative stress, and pitfalls are plentiful. There is accumulating evidence that DNA oxidation is associated with disease, particularly cancer, and recent evidence points at an association between RNA oxidation and neurodegenerative diseases and diabetes. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.     

Determination of ribonucleosides,deoxyribonucleosides, and purine and pyrimidine bases in adult rabbit cerebrospinal fluid and plasma

Purine and pyrimidine base and nucleoside levels were measured in adult rabbit cisternal CSF and plasma by reversed-phase high-performance liquid chromatography. The concentrations of bases, nucleosides, and nucleoside phosphates were similar in plasma and CSF except for the adenosine phosphates and uracil which were higher in the plasma. In plasma and CSF, adenosine levels were low (0.12 microM) and guanosine, deoxyadenosine, deoxyguanosine, and deoxyinosine were not detectable (less than 0.1 microM); inosine and xanthine concentrations were 1-2 microM and hypoxanthine concentrations were approximately 5 microM; uridine (approximately 8 microM), cytidine (2-3 microM), and thymidine, deoxyuridine, and deoxycytidine (0.5-1.4 microM) were easily detectable. In both plasma and CSF, guanine, and thymine were undetectable (less than 0.1 microM), adenine and cytosine were less than 0.2 microM, but uracil was present (greater than 1 microM). Adenosine, inosine, and guanosine phosphates were also detectable at low concentrations in CSF and plasma. These results are consistent with the hypothesis that purine deoxyribonucleosides are synthesized in situ in the adult rabbit brain. In contrast, pyrimidine deoxyribonucleosides and ribonucleosides, and purine and pyrimidine bases are available in the CSF for use by the brain.     

Proteome analysis of chick embryonic cerebrospinal fluid

During early stages of embryo development, the brain cavity is filled with embryonic cerebrospinal fluid (E-CSF), a complex fluid containing different protein fractions that contributes to the regulation of the survival, proliferation and neurogenesis of the neuroectodermal stem cells. Using 2-DE, protein sequencing and database searches, we identified and analyzed the proteome of the E-CSF from chick embryos (Gallus gallus). We identified 26 different gene products, including proteins related to the extracellular matrix, proteins associated with the regulation of osmotic pressure and metal transport, proteins related to cell survival, MAP kinase activators, proteins involved in the transport of retinol and vitamin D, antioxidant and antimicrobial proteins, intracellular proteins and some unknown proteins. Most of these gene products are involved in the regulation of developmental processes during embryogenesis in systems other than E-CSF. Interestingly, 14 of them are also present in adult human CSF proteome, and it has been reported that they are altered in the CSF of patients suffering neurodegenerative diseases and/or neurological disorders. Understanding these molecules and the mechanisms they control during embryonic neurogenesis is a key contribution to the general understanding of CNS development, and may also contribute to greater knowledge of these human diseases.     

Enhanced detection of CNS cell secretome in plasma protein-depleted cerebrospinal fluid

Human cerebrospinal fluid (CSF) proteome is actively investigated to identify relevant biomarkers and therapeutic targets for neurological disorders. Approximately 80% of CSF proteome originate from plasma, yielding a high dynamic range in CSF protein concentration and precluding identification of potential biomarkers originating from CNS cells. Here, we have adapted the most complete multiaffinity depletion method available to remove 20 abundant plasma proteins from a CSF pool originating from patients with various cognitive disorders. We identified 622 unique CSF proteins in immunodepleted plus retained fractions versus 299 in native CSF, including 22 proteins hitherto not identified in CSF. Parallel analysis of neuronal secretome identified 34 major proteins secreted by cultured cortical neurons (cell adhesion molecules, proteins involved in neurite outgrowth and axonal guidance, modulators of synaptic transmission, proteases and protease inhibitors) of which 76% were detected with a high confidence in immunodepleted CSF versus 50% in native CSF. Moreover, a majority of proteins previously identified as secretory products of choroid plexus cells or astrocytes were detected in immunodepleted CSF. Hence, removal of 20 major plasma proteins from CSF improves detection of brain cell-derived proteins in CSF and should facilitate identification of relevant biomarkers in CSF proteome profiling analyses.     

Pharmacokinetic behavior in plasma, cerebrospinal fluid and cerebral cortex after intranasal administration of hydrochloride meptazinol

The aim of this paper is to investigate the pharmacokinetic behavior of hydrochloride meptazinol (MEP) in plasma, cerebrospinal fluid (CSF) and cerebral cortex after intranasal administration (8 mg/kg) in male Sprague-Dawley rats. The pharmacokinetic study of intravenous administration (8 mg/kg) was also performed in rats. CSF and cerebral cortex samples were collected by serial CSF sampling and intracerebral microdialysis, respectively. The concentration of MEP in the biological samples was measured by high performance liquid chromatography (HPLC). It was determined that the absorption of MEP from the nasal cavity to systemic circulation was rapid and complete. The concentration-time profile showed a prolonged duration of MEP concentration in CSF and cortex following intranasal administration. The ratios of AUC values of intranasal to intravenous administrations were 0.96, 1.07 and 1.81 in plasma, CSF and cortex dialysate, respectively. In conclusion, intranasal administration of MEP is a promising alternative to traditional administration modes. Olfactory mucosa did not present intranasal MEP another pathway, in addition to systemic absorption, for transport to the brain.     

Decreased plasma and cerebrospinal fluid ascorbate levels in patients with septic encephalopathy

Septic encephalopathies rapidly affect brain function without the involvement of a specific area causing a broad range of reversible neurologic symptoms. Capillary leakage including dysfunction of the blood-brain barrier has been proposed as a potential pathogenic mechanism in this entity. We tested the hypothesis that oxidative stress measured in plasma and cerebrospinal fluid (CSF) of patients suffering from septic encephalopathy could be linked to the neurologic symptoms of the disease. The neurologic symptoms of eleven patients with septic encephalopathy were described semiquantitatively through a score system. The ascorbate levels were significantly lower in both plasma and CSF from patients with septic encephalopathy than controls, and in CSF but not plasma this decrease correlated with the severity of neurologic symptoms. No significant changes were found for alpha-tocopherol. Our findings suggest that the short-term oxidative stress may be an important factor in the development of septic encephalopathy, possibly through dysregulation of the blood-brain barrier.