Brain CSF illustrations / Barriers table overlap, Brain structure (ECF / parenchyma / ventricular system), CSF turnover (4×/day), SE as a Surrogate for Assessing CNS Exposure (Lamotrigine / Phenytoin / Tiagabine / Acelagon AUC matrix), Sources of CSF proteins, Antemortem vs postmortem (Subhash 2008), Human CSF sampling (lumbar puncture 15-20 mL / 30 mL maximum), Cisterna magna puncture vs Catheter implantation, rhesus macaque CSF (Clingerman 2010 #1819), Serial sampling opener
Brain structure
- ECF
- Parenchyma (cells)
- Ventricular system (CSF): no protein binding of drugs takes place here.
- Human brain generates 7 g of proteins a day. 3.6 g of proteins may be drained a day. The rest would be degraded
- There is the BBB between ECF and CSF (?, 아래 그림 보니 맞는 말 같은데..)
Flow: total plasma → free plasma → ECF (interstitial) → CSF
(10% subset of CSF or transcellular [neuroscience])
CSF total volume: 150 mL in human and 0.04 mL in mouse, 25% renewed every day
Turnover
- 4 times/day, CSF buffer flow’s Turn-over: 4.8h in human
- In humans and mice, CSF is renewed approximately four and 12 times each 24hours, respectively, and the total CSF volume of 150-160 mL in human and 0.04 ml, in mice is kept constant by removal of CSF [3, 14, 15, 25, 29].
SE as a Surrogate for Assessing CNS Exposure: An Industrial Perspective
Single timepoint? PI AUC vs CSF / Plasma 비교 가 다 봐라.
Microdialysis only measures unbound drug
| Total serum AUC | Unbound serum AUC | ISF AUC | CSF AUC | ||
|---|---|---|---|---|---|
| Lamotrigine Rat | 1.1 | 1.1 | 0.09 | 0.32 | Phenytoin is a substrate of P-gp |
| Phenytoin | |||||
| Rat | |||||
| Tiagabine Rat | 0.01 | 0.01 | 0.001 | ||
| Acelagon Human (so, not AUC) | 0.01 | 0.0001 |
In humans
- An excellent agreement between serum unbound and CSF concentration of AEDs
- 18/9 (unbound serum (in CSF 0.1-7) concentration at the target / 인간 등 정확하다고 모듬) 임 임상 정상 특성 nM
- if 6 free fraction in ECF (interstitial: 약 시 시 정상치) — 일부 자료
- similar to Plasma in some animal model, 가 등록 임상 because the brain has 20 fold more lipids 따로 데이터, brain tissue binding 위치 (5 unbound plasma = unbound ECF (interstitial) 으로 로 보기 [나 여 ? 시 정상? 나비, …))
- ECF 는 단어로 EPA 에서, 등 어동 시 나비, …
Brain homogenate ( = ECF + Plasma + Tissue Binding) ( 정 정상 등 NLI: brain concentration 정 issue binding portion 등 free portion 등 등 가지 ( 기 해서 ECF CSF concentration 등 가지 ( 기 해서)
- it is a biomarker that has its origin in the CNS has to cross the BBB in order to be detected in the periphery and, if the concentration is low in CSF, it will be even lower in the blood due to the eventual CSF volume ratio causing a substantial dilution of the analyte.
- if the biomarker is not specific for the CNS but also expressed in peripheral tissues, the contribution from CNS will potentially drown in the high biological background caused by non-CNS sources
Sources of CSF proteins
- (interstitial extracellular space of the brain)
- Parenchyma of the brain → normal diffusion
- BBB breakdown → extravasation of blood products
- Peripheral e.g. corpuscular elements of whole blood [21,22] or from peripheral organs (e.g. liver)
Antemortem vs postmortem
(Subhash, 2008): Method - of CSF samples (1 antemortem and 1 post mortem) were collected from 7 patients
results:
- 24% of the proteins (out of ~1300 proteins) showed statistically difference in level. (js: 76% ? 자아 임의에 보아도 거의 차이 안 나.)
- 21% of proteins showed a fold change >3.5 in all 7 patients. cytoskeletal proteins, enzymes involved in glycolysis, and proteins that prevent oxidative stress
Postmortem CSF collection, processing, storage(?), good protocol: Tashjian 2020
Human CSF sampling
| MAD (Marcio) | The maximum amount of CSF collected from each subject over the duration of the study will not exceed 30 mL (a maximum of 10 mL per each of the 3 days) During the lumbar puncture procedure, 15-20 ml of CSF will be collected from study subjects. |
| (2015) | Collection of up to 30 mL of CSF will be tolerated and safe [26]. Total 3 mL CSF was taken in a polypropylene tube between 7 a.m. and 10 a.m. under fasting condition through lumbar puncture. {Total 2 ml venous whole blood was collected.} Approximately 0.5 ml volume of CSF and serum were aliquoted into separate Nunc cryotubes and kept frozen at -80°C until ready for assay. |
CSF collection sites
CSF collection sites include mainly cere-bral ventricle, lumbar cistern, cisterna magna
(2015 #1507):
| Catheter implantation | Cisterna magna puncture | |
|---|---|---|
| Advantage | Serial sampling allowed, ?, blood contamination of CSF | simple, inexpensive, and practical |
| Disadvantage | Currently-used cerebellomedullary cistern puncture method for collecting cerebrospinal fluid (CSF) from monkeys is simple, inexpensive, and practical, but with high risk for brainstem injury and CSF blood contamination | high risk for brainstem injury and CSF blood contamination |
CSF collection
| rhesus macaque | Cisterna magna | (Clingerman, 2010 #1819) 1.0 ml per animal |
- Serial sampling
- Examples
Uncertain Spans
| location | transcription | uncertainty |
|---|---|---|
Brain homogenate / 정 정상 등 NLI | mixed Korean / English narrative with OCR artefacts; preserved verbatim. | |
| Human CSF / MAD row | (a maximum of 10 mL per each of the 3 days) | trailing word days inferred from context; preserved verbatim. |
| Cisterna magna table | Currently-used cerebellomedullary cistern puncture method ... but with high risk for brainstem injury and CSF blood contamination | the phrase appears in the Disadvantage / Catheter implantation cell but the source row alignment is uncertain; preserved verbatim with the table cell layout transcribed as visible. |