Measurement of cerebrospinal fluid formation and absorption by ventriculo-cisternal perfusion: what is really measured?

The generally accepted hypothesis on cerebrospinal fluid (CSF) hydrodynamics suggests that CSF is actively formed mainly by the choroid plexuses, circulates unidirectionally along the brain ventricles and subarachnoid space, and is passively absorbed mainly into the dural venous sinuses. CSF formation rate (Vf ) has been extensively studied using the ventriculo-cisternal perfusion technique and the results have been used as the key evidence confirming the mentioned hypothesis. This technique and the equation for Vf calculation are based on the assumption that the dilution of the indicator substance is a consequence of the newly formed CSF, ie, that a higher CSF formation rate will result in a higher degree of dilution. However, it has been experimentally shown that the indicator substance dilution inside the CSF system does not occur because of a “newly formed” CSF, but as consequence of a number of other factors (departure of substances into the surrounding tissue, flowing around the collecting cannula into the cortical and spinal subarachnoid space, departure into the contralateral ventricle, etc). This technique allows “calculation” of the CSF formation even in dead animals, in an in vitro model, and in any other part of the CSF system outside the ventricles that is being perfused. Therefore, this method is indirect and any dilution of the indicator substance in the perfusate caused by other reasons would result in questionable and often contradictory conclusions regarding CSF formation rates

The development of perineuronal nets in the subplate zone of the human brain

Perineuronske mreže su strukture izvanstanične tvari u mozgu koje nastaju kada stanice izluče molekule hondroitin sulfata proteoglikana koje se kondenziraju i okružuju tijela određenih neurona i njihovih aksona. Danas je poznato da one imaju čitav niz važnih uloga u normalnom razvoju i funkciji mozga. U ovom radu su preparati ljudskog fetalnog i dječjeg mozga obojani Wisteria floribunda agglutin-om koji je prihvaćeni marker perineruronskih mreža, odnosno izvanstanične tvari. Cilj istraživanja je bio utvrditi intenzitet te prostornu i vremensku raspodjelu perineuronskih mreža u prvenstveno sloju pod pločom, a zatim i samoj kortikalnoj ploči tijekom razvoja ljudskog telencefalona. Rezultati su pokazali da su perineuronske mreže sa 13. gestacijskog tjedna izražene u pre-subplate zoni kao perisomatsko obojenje u dorzolateralnom telencefaličkom zidu. Nakon toga, perineuronske mreže su do 25. tjedna gestacije izražene kao difuzno obojenje u subplate zoni, najviše oko prospektivne inzule. Do 33. gestacijskog tjedna su pak vrlo slabo vidljive, dok se nakon toga, kao i u 40. gestacijskom tjednu vide kao intenzivno difuzno obojenje u remnants of subplate zoni. Ti rezultati, kao i oni drugih istraživanja upućuju na moguću vrlo bitnu ulogu koju perineuronske mreže imaju tijekom razvoja i normalnog funkcioniranja ljudskog mozga.Perineuronal nets (PNN) are structures formed when cells secrete molecules of chondroitin sulphate proteoglycan, which condense and surround certain neurons and their axons. Today it is known that they perform a wide variety of functions in the normal development and diseased brain. In this research, PNN of the human fetal and children brain were visualized using a histochemical staining with Wisteria floribunda agglutinin which is a well-established marker of the perineuronal nets and the extracellular matrix rich in. The aim of the study was to determine the intensity of expression, as well as its spatio-temporal allocation in the human telencephalon during development, focusing primarily on the subplate zone but also on the cortical plate. The results show that the perineuronal nets do have a specific pattern of expression, as well as a spatio-temporal distribution in the subplate zone. In the 13th week of gestation, perineuronal nets are expressed in the pre-subplate zone as a perisomatic staining in the dorzo-lateral telencephalic wall. After that, until the 25th week of gestation, they are expressed as a diffuse staining in the subplate zone, mostly around the prospective insula. Until the 33rd gestation week the perineuroneal nets are very faintly seen in the subplate zone. After that period they are expressed as an intense staining in the remnants of subplate zone. These results, as well as many others, suggest an important role that the perineuronal nets have during development and normal functioning of the brain

The development of perineuronal nets in the subplate zone of the human brain

Perineuronske mreže su strukture izvanstanične tvari u mozgu koje nastaju kada stanice izluče molekule hondroitin sulfata proteoglikana koje se kondenziraju i okružuju tijela određenih neurona i njihovih aksona. Danas je poznato da one imaju čitav niz važnih uloga u normalnom razvoju i funkciji mozga. U ovom radu su preparati ljudskog fetalnog i dječjeg mozga obojani Wisteria floribunda agglutin-om koji je prihvaćeni marker perineruronskih mreža, odnosno izvanstanične tvari. Cilj istraživanja je bio utvrditi intenzitet te prostornu i vremensku raspodjelu perineuronskih mreža u prvenstveno sloju pod pločom, a zatim i samoj kortikalnoj ploči tijekom razvoja ljudskog telencefalona. Rezultati su pokazali da su perineuronske mreže sa 13. gestacijskog tjedna izražene u pre-subplate zoni kao perisomatsko obojenje u dorzolateralnom telencefaličkom zidu. Nakon toga, perineuronske mreže su do 25. tjedna gestacije izražene kao difuzno obojenje u subplate zoni, najviše oko prospektivne inzule. Do 33. gestacijskog tjedna su pak vrlo slabo vidljive, dok se nakon toga, kao i u 40. gestacijskom tjednu vide kao intenzivno difuzno obojenje u remnants of subplate zoni. Ti rezultati, kao i oni drugih istraživanja upućuju na moguću vrlo bitnu ulogu koju perineuronske mreže imaju tijekom razvoja i normalnog funkcioniranja ljudskog mozga.Perineuronal nets (PNN) are structures formed when cells secrete molecules of chondroitin sulphate proteoglycan, which condense and surround certain neurons and their axons. Today it is known that they perform a wide variety of functions in the normal development and diseased brain. In this research, PNN of the human fetal and children brain were visualized using a histochemical staining with Wisteria floribunda agglutinin which is a well-established marker of the perineuronal nets and the extracellular matrix rich in. The aim of the study was to determine the intensity of expression, as well as its spatio-temporal allocation in the human telencephalon during development, focusing primarily on the subplate zone but also on the cortical plate. The results show that the perineuronal nets do have a specific pattern of expression, as well as a spatio-temporal distribution in the subplate zone. In the 13th week of gestation, perineuronal nets are expressed in the pre-subplate zone as a perisomatic staining in the dorzo-lateral telencephalic wall. After that, until the 25th week of gestation, they are expressed as a diffuse staining in the subplate zone, mostly around the prospective insula. Until the 33rd gestation week the perineuroneal nets are very faintly seen in the subplate zone. After that period they are expressed as an intense staining in the remnants of subplate zone. These results, as well as many others, suggest an important role that the perineuronal nets have during development and normal functioning of the brain

New experimental model of acute aqueductal blockage in cats: effects on cerebrospinal fluid pressure and the size of brain ventricles

It is generally assumed that cerebrospinal fluid (CSF) is secreted in the brain ventricles, and so after an acute blockage of the aqueduct of Sylvius an increase in the ventricular CSF pressure and dilation of isolated ventricles may be expected. We have tested this hypothesis in cats. After blocking the aqueduct, we measured the CSF pressure in both isolated ventricles and the cisterna magna, and performed radiographic monitoring of the cross-sectional area of the lateral ventricle. The complete aqueductal blockage was achieved by implanting a plastic cannula into the aqueduct of Sylvius through a small tunnel in the vermis of the cerebellum in the chloralose-anesthetized cats. After the reconstitution of the occipital bone, the CSF pressure was measured in the isolated ventricles via a plastic cannula implanted in the aqueduct of Sylvius and in the cisterna magna via a stainless steel cannula. During the following 2 h, the CSF pressures in the isolated ventricles and cisterna magna were identical to those in control conditions. We also monitored the ventricular cross-sectional area by means of radiography for 2 h after the aqueductal blockage and failed to observe any significant changes. When mock CSF was infused into isolated ventricles to imitate the CSF secretion, the gradient of pressure between the ventricle and cisterna magna developed, and disappeared as soon as the infusion was terminated. However, when mock CSF was infused into the cisterna magna at various rates, the resulting increased subarachnoid CSF pressure was accurately transmitted across the brain parenchyma into the CSF of isolated ventricles. The lack of the increase in the CSF pressure and ventricular dilation during 2 h of aqueductal blockage suggests that aqueductal obstruction by itself does not lead to development of hypertensive acute hydrocephalus in cats

Hitna stanja u onkologiji

Emergency conditions in oncology may arise either as part of the malignant disease itself, or may be associated with its treatment. They are potentially life-threatening conditions that require urgent care, often with patient hospitalization and a multidisciplinary treatment approach. Consequently, it is important that all physicians are familiar not only with potential oncological emergencies which may occur in their clinical practice but also how to provide the most effective care in a timely fashion. In this review article we comprise the clinical features and treatment of several of these emergencies, namely the superior vena cava syndrome (SVCS), elevated intracranial pressure, metastatic spinal cord compression (MSCC), hypercalcemia and febrile neutropenia.Hitna stanja u onkologiji mogu nastati kao posljedica prisustva maligne bolesti ili mogu biti povezana s liječenjem. To su stanja potencijalno opasna po život koja zahtijevaju hitno zbrinjavanje, često uz hospitalizaciju bolesnika, te multidisciplinarni terapijski pristup. Stoga je važno da svi liječnici budu upoznati s mogućim hitnim onkološkim stanjima koja se mogu pojaviti u njihovoj kliničkoj praksi i kako na vrijeme pružiti najučinkovitije liječenje. U ovom preglednom članku obuhvatili smo klinička obilježja i liječenje sindroma gornje šuplje vene, povišenog intrakranijskog tlaka, metastatske kompresije leđne moždine, hiperkalcemije i febrilne neutropenije

Physiological Characteristics of Some Monoamine Metabolites in Cat Cerebrospinal Fluid

The concentrations of main metabolites of serotonin and dopamine, 5-hydroxyindoleacetic acid and homovanillic acid, respectively, were measured in cisternal cerebrospinal fluid of cats by high performance liquid chromatography with an electrochemical detector. Higher concentrations of homovanillic acid and a wide interindividual oscillation for both parameters have been found. However, samples collected at four different time intervals showed stabile intraindividual concentrations of the metabolites. The existence of a concentration gradient of both parameters inside the cat cerebrospinal fluid system was confirmed in experiments with a provoked artificial flow of cerebrospinal fluid inside physiological limits. These experiments also suggested that the hydrodynamics of cerebrospinal fluid is the factor responsible for the concentration gradient existence. It appears that the absence of cerebrospinal fluid circulation is the main hydrodynamic reason for the maintenance of 5-hydroxyindoleacetic acid and homovanillic add gradients between various parts of the cerebrospinal fluid system

The influence of body position on cerebrospinal fluid pressure gradient and movement in cats with normal and impaired craniospinal communication

Intracranial hypertension is a severe therapeutic problem, as there is insufficient knowledge about the physiology of cerebrospinal fluid (CSF) pressure. In this paper a new CSF pressure regulation hypothesis is proposed. According to this hypothesis, the CSF pressure depends on the laws of fluid mechanics and on the anatomical characteristics inside the cranial and spinal space, and not, as is today generally believed, on CSF secretion, circulation and absorption. The volume and pressure changes in the newly developed CSF model, which by its anatomical dimensions and basic biophysical features imitates the craniospinal system in cats, are compared to those obtained on cats with and without the blockade of craniospinal communication in different body positions. During verticalization, a long-lasting occurrence of negative CSF pressure inside the cranium in animals with normal cranio-spinal communication was observed. CSF pressure gradients change depending on the body position, but those gradients do not enable unidirectional CSF circulation from the hypothetical site of secretion to the site of absorption in any of them. Thus, our results indicate the existence of new physiological/pathophysiological correlations between intracranial fluids, which opens up the possibility of new therapeutic approaches to intracranial hypertension