Effects of proteins, blood cells and glucose on the viscosity of cerebrospinal fluid

It has long been assumed that cerebrospinal fluid (CSF) is a newtonian fluid with viscosity similar to water, yet high protein content, has been postulated to increase the viscosity of CSF in vivo. Such an increase in viscosity may have serious implications for the effectiveness of surgical shunts implanted to re-establish the CSF flow in cases of abnormal CSF circulation. In this study, glucose content, total protein content and blood cell count in the CSF of 23 patients undergoing brain surgery were measured. Viscosity measurements were performed on duplicate CSF samples over a range of shear strain rates of 25-1,460 s-1. The results indicated that high protein or high cell concentration in CSF does not significantly affect the viscosity of the cerebral fluid at those shear rates. CSF is clearly newtonian, and its viscosity at 37 degreesC is in the range of 0.7-1 mPa.s.     

Tendinous insertion of semimembranosus muscle into the lateral meniscus

Forty-two cadaver knees were used for morphologic and MRI observations of the tendinous distal expansions of the semimembranosus m. and the posterior capsular structures of the knee. A tendinous branch of the semimembranosus m. inserting into the posterior horn of the lateral meniscus was found in 43.2% of the knees dissected, besides five already known insertional branches; capsular, direct, anterior and inferior, as well as the oblique popliteal ligament. The tendon had three morphologic types; thin, broad and round. All three types moved the lateral meniscus posteriorly when pulled on. Thus, the semimembranosus m. may also have a protective function for the lateral meniscus as well as the already well established function of protecting the medial meniscus in knee flexion. When a semimembranosus tendon attachment to the posterior horn of the lateral meniscus is present, its normal insertion is difficult to differentiate from a lateral meniscus tear in MRI and this may cause misdiagnosis.     

Internet resources for orthopaedic surgeons

PURPOSE: Using polarized bovine brain microvessel endothelial cells (BBMEC) monolayers as in vitro model of the blood brain barrier and Caco-2 monolayers as a model of the intestinal epithelium, the present work investigates the effects of Pluronic P85 block copolymer (P85) on the transport of the P-gycoprotein (P-gp)- dependent probe, rhodamine 123 (R123). METHODS: The permeability and cell efflux studies are performed with the confluent cell monolayers using Side-Bi-Side diffusion cells. RESULTS: At concentrations below the critical micelle concentration, P85 inhibits P-gp efflux systems of the BBMEC and Caco-2 cell monolayers resulting in an increase in the apical to basolateral permeability of R123. In contrast, at high concentrations of P85 the drug incorporates into the micelles, enters the cells and is then recycled back out to the apical side resulting in decrease in R123 transport across the cell monolayers. Apical to basolateral permeability of micelle-incorporated R123 in BBMEC monolayers was increased by prior conjugation of P85 with insulin, suggesting that modified micelles undergo receptor-mediated transcytosis. CONCLUSIONS: Pluronic block copolymers can increase membrane transport and transcellular permeability in brain microvessel endothelial cells and intestinal epithelium cells. This suggests that these block copolymers may be useful in designing formulations to increase brain and oral absorption of select drugs.     

Regulation of Sertoli cell alpha 2-macroglobulin and clusterin (SGP-2) secretion by peritubular myoid cells

alpha 2-Macroglobulin and clusterin are two putative Sertoli cell secretory products; however, the regulator(s) modulating their secretion by Sertoli cells is not known. Recent studies from this laboratory have shown that the testicular alpha 2-macroglobulin, unlike its liver homologue, is not an acute-phase reactant and its concentration is not affected by acute inflammation. We sought to determine whether FSH, testosterone, and other biomolecules would affect the secretion of alpha 2-macroglobulin and clusterin by Sertoli cells as well as whether peritubular myoid cells would affect the secretion of these proteins by Sertoli cells. It was noted that Sertoli cells cultured in vitro secreted increasing amounts of alpha 2-macroglobulin and clusterin as a function of time. FSH (50-1000 ng/ml) and testosterone (10(-11)-10(-5) M) had no apparent effect on the secretion of alpha 2-macroglobulin and clusterin by Sertoli cells. Addition of interleukin-6 to Sertoli cell-enriched cultures, in doses known to stimulate alpha 2-macroglobulin secretion by hepatocytes, did not affect the alpha 2-macroglobulin secretion. However, dexamethasone at 10(-7)-10(-5) M stimulated alpha 2-macroglobulin secretion by Sertoli cells dose-dependently while the addition of interleukin-6 had no synergistic effect on dexamethasone-stimulated alpha 2-macroglobulin secretion. These findings suggest that the synthesis and/or secretion of alpha 2-macroglobulin by Sertoli cells is regulated by a mechanism distinct from that of the liver.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative characteristics of some cultural and toxigenic properties of the Dendrodochium Bonorden and Myrothecium Tode ex Fr. representatives

The comparative study of sporulation intensity, change of medium pH, yield of biomass and ethanol soluble fraction (ESF) of extracellular metabolites as well as antibiotic and toxigenic properties of 106 fungi strains which were the potential producers of macrocyclic trichothecenes has been carried out under the conditions of stationary cultivation. It was shown that all the studied Dendrodochium strains were characterized by moderate growth, variations of biomass were within 3.5-4.5 g/l. Variations of ESF level in different strains were rather essential (from 8 to 241.6 mg/l). High antibiotic activity correlated with high or moderate toxicity (on the basis of rabbit skin test) in most cases. Dendrodochium strains with intensive sporulation were as a rule characterized by high efficiency of toxin production (40% of studied strains) and only 3 strains (5.5%) with low level of sporulation were characterized by high rate of toxin production. The toxigenic activity for Myrothecium cinctum, M. commune and M. ukrainicum has been shown for the first time. The toxigenic activity of the studied strains depending on the source of isolation and possible correlative connections between sporulation, toxin formation and other properties are discussed.