Hematopoietic stem cell transplantation for severe aplastic anemia

Clara cell protein (CC16) is an endogenous anti-inflammatory agent. It is produced mainly in the respiratory and urogenital tracts. CC16 has been quantified in serum, but not in cerebrospinal fluid (CSF). The aim of this study was to examine CSF CC16 in relation to age, gender and serum CC16, and to examine CC16 levels in parturients. If CC16 levels are increased with age and during pregnancy, it may be responsible for the attenuation of inflammatory diseases such as multiple sclerosis during these conditions. CC16 was measured in CSF and serum taken just before Caesarean section (n=33) or just before an elective surgical procedure in females (n=52) or males (n=31). Fetal serum, amniotic fluid, and maternal urine were also sampled during Caesarean section. CC16 levels in CSF did not differ between parturients and an age and gender matched non-pregnant group, but was higher in male than in female patients. There was a significant and positive relationship between age and CSF CC16 levels and between serum and CSF CC16 levels. Fetal CC16 was significantly and positively correlated with amniotic fluid CC16. The present study suggests that CC16 found in CSF originates from passive diffusion from blood, and that CC16 found in amniotic fluid is derived from the fetal lung. During pregnancy, CC16 does not appear to contribute to alterations which occur in the progression of inflammatory disorders.     

CSF levels of carnitine in children with meningitis, neurologic disorders, acute gastroenteritis, and seizure

Carnitine concentrations in CSF, serum, and urine in normal febrile children and children with meningitis, neurologic disorders, and dehydration were studied. Carnitine levels in CSF were 1/10 compared with serum in normal febrile children. These levels increased two- to three-fold in the pathologic conditions studied. Since damage to the blood-brain barrier occurs in these conditions, higher blood-brain barrier permeability might explain CNS carnitine accumulation.     

The in vivo effect of colchicine on the addition of galactose and sialic acid to rat hepatic serum glycoproteins

Colchicine inhibits the secretion of plasma protein by rat hepatocytes and causes their intracellular accumulation in Golgi-derived secretory vesicles. This study examines whether colchicine affects secretion before or after galactose and sialic acid have been added to the secretory glycoproteins. D-[G-3H] Galactose was injected into rats and was found to be incorporated into serum glycoproteins contained within Golgi-derived secretory vesicles. The administration of colchicine (25 mumol/100 g, body weight), immediately before the injection of D-[G-3H] galactose, caused an increase in radioactivity of the serum glycoproteins in these cell fractions. D-[G-3H] Glucosamine was incorporated into serum glycoproteins contained within the rough and smooth endoplasmic reticulum and the Golgi cell fractions; however, its incorporation into the sialic acid moieties of these proteins only occurred in Golgi-derived cell fractions. Colchicine administration resulted in an increased incorporation of D-[G-3H] glucosamine into the sialic acid residues of serum glycoproteins contained within the Golgi cell fractions. These data indicate that colchicine inhibits secretion of serum proteins by rat liver after the addition of galactose and sialic acid to the secretory proteins has taken place.     

Do blood cell counts have an independent prognostic value in primary lung cancer?

A review of the biomedical literature suggests that lymphocyte and neutrophil counts are probably the only blood cell count parameters whose independent pre-therapeutic prognostic values are significantly documented in lung cancer (and only in non small cell lung cancer). The independent pre-therapeutic prognostic value of these two parameters remains quite controversial however, and further studies should be conducted, and in particular, comparisons between neutrophils, lymphocytes, and serum cyfra 21-1. For the therapeutic follow-up, further prognostic evaluation studies are also necessary for blood cell count parameters as well as for serum cyfra 21-1. Clinical biologists still have to convince clinicians and/or journal editors that it is not scientifically acceptable for publications to omit detailing the analytical and pre-analytical methodologies used for blood cell count measurements.     

Expression of hirudin fusion proteins in mammalian cells: a strategy for prevention of intravascular thrombosis

BACKGROUND: Intravascular thrombosis occurs in disorders of diverse pathogeneses, including allograft and xenograft rejection. In this in vitro study, we describe an approach for tethering the specific thrombin inhibitor hirudin to plasma membranes as part of a genetic strategy for regulating intravascular coagulation. METHODS AND RESULTS: An HLA class I leader sequence was fused with hirudin linked to domains 3 and 4 of human CD4 and intracytoplasmic sequence from either CD4 or human P-selectin. The constructs were transfected into mouse fibroblasts, Chinese hamster ovary (CHO)-K1 cells, immortalized porcine endothelial cells (IPECs), and a pituitary secretory cell line (D16/16). Thrombin binding to the hirudin fusion proteins expressed on fibroblasts and CHO-K1 cells could be blocked by an anti-hirudin monoclonal antibody and by pretreatment of thrombin with either the synthetic tripeptide thrombin inhibitor PPACK or native hirudin. Hirudin expression significantly modified the procoagulant phenotype of IPECs in human plasma, leading to prolongation of clotting times. Hirudin-CD4-P-selectin fusion proteins accumulated in adrenocorticotropic hormone-containing granules in D16/16 cells, with no cell surface expression except on activation with phorbol ester, when hirudin relocated to the outer membrane. CONCLUSIONS: Hirudin fusion proteins were expressed on mammalian cells, where they reduced local thrombin levels and inhibited fibrin formation. Regulated expression was achieved on activated cells by use of the cytoplasmic sequence from P-selectin. In vivo, these fusion proteins may prove useful transgenic or gene therapy agents for preventing intravascular thrombosis.     

Provitamin A carotenoid intake and carotid artery plaques: the Atherosclerosis Risk in Communities Study

Clara cell protein is a 16-17 kDa protein (CC16) secreted by Clara cells in the bronchiolar lining fluid of the lung. In order to investigate the potential of this protein as a pulmonary marker in animals, CC16 was isolated from rat bronchoalveolar lavage fluid (BALF) and a sensitive latex immunoassay applicable to both rat and mouse CC16 was developed. The pattern of CC16 concentrations in rat biological fluids determined by the immunoassay was consistent with the hypothesis of a passive diffusion of the protein across the bronchoalveolar/blood barriers showing a difference of more than 5,000 fold between the concentration in the epithelial lining fluid (mean, 140 mg x L(-1)) and that in serum (20 microg x L(-1)) or urine (3 microg x L(-1)). In BALF, the CC16 concentration averaged 5,500 microg x L(-1) and was of the same magnitude as that determined on lung and trachea homogenates. CC16 was also detectable in amniotic fluid with a mean value of 800 microg x L(-1) before delivery. Damage of Clara cells produced by methylcyclopentadienyl manganese tricarbonyl resulted in a significant decrease of CC16 in BALF but did not affect the serum levels of the protein. The nephrotoxicant sodium chromate by contrast had no influence on the CC16 content of BALF but markedly increased CC16 levels in both serum and urine as a result of impaired glomerular filtration and tubular reabsorption, respectively. In conclusion, mouse or rat Clara cell protein of 16-17 kDa can easily be quantified, not only in bronchoalveolar lavage fluid, but also in extrapulmonary fluids such as serum or urine. Thus, in rodents, Clara cell protein of 16-17 kDa follows the same metabolic pathway as in humans, diffusing from the respiratory tract into serum where it is eliminated by the kidneys. This serum Clara cell protein of 16-17 kDa may be useful as a peripheral marker of events taking place in the respiratory tract.     

Dental procedure fees 1975 through 1995: how much have they changed?

Generally, cationic vector-based intravenous delivery of DNA is hindered by interactions of positively charged complexes with serum proteins. However, if optimally formulated, cationic vectors can provide reasonable levels of transfection in the lung either by intravenous or intrapulmonary routes. We investigated the in vivo transfection capacity of a cationic polymer: linear, 22 kDa polyethylenimine. PEI/DNA complexes were formulated in 5% glucose and delivered into adult mice through the tail vein. Two marker genes were used, beta-galactosidase and luciferase. High levels of luciferase expression (10(7) RLU/mg protein) were found in the lung when DNA was complexed with PEI at a ratio of 4 nitrogen equivalents per DNA phosphate. Lower levels of transfection were found in the heart, spleen, liver and kidney. Expression was dose- and time-dependent in all tissues examined. In the lung, beta-galactosidase staining showed transgene expression in clusters of 10 or more pulmonary cells including the alveolar endothelium, squamous and great alveolar epithelial cells (type I and II pneumocytes) and septal cells. These findings indicate that the complexes pass the capillary barrier in the lung. Although the delivery mechanism requires elucidation, linear PEI has promise as a vector for intravenous transfer of therapeutic genes.     

Monoacylation of ribonuclease A enables its transport across an in vitro model of the blood-brain barrier

A major challenge in correcting disorders affecting the central nervous system is to induce blood-brain barrier (BBB) crossing of exogenous biological compounds such as proteins or specific nucleic acid sequences. Fatty acids, due to their high membrane affinity and low toxicity, are good potential candidates to promote this barrier crossing when covalently bound to proteins. In this paper, we report that regiospecific monoacylation of ribonuclease A (RNase A) enables its transport across an in vitro model of the BBB. Myristoylated, palmitoylated and stearoylated RNases A were prepared using reversed micelles as microreactors. All the purified acylated RNases A kept their original enzymatic activity. A single fatty acid moiety was linked to RNase A through the alpha-amino group of its N-terminal lysine as shown by powerful analytical techniques. The ability of monoacylated RNases A to cross an in vitro model of the BBB is strictly dependent on the acyl chain length, which must be at least 16 carbon atoms long.     

The use of null mutant mice to study complex learning and memory processes

Fractionation of the rat lung yielded a 54,000 g supernate, and DOC-solubilized 775 g, 3100 g and 54,000 g sediments, each of these preparations displaying an increasing angiotensin-converting enzyme activity with increasing dilution, suggesting the presence of freely reversible angiotensin-converting enzyme inhibitors. The solubilized 775 g sediment was applied to an immobilized captopril column, eluted successively with 20 mM Pi(K+), pH 7.8 buffer, buffer/0.5 M NaCl, and buffer/0.01M cysteine to obtain four major protein bands, two of which appeared with the cysteine eluant. The first two protein peaks were each pooled and subjected to ultrafiltration with 10,000 molecular weight cutoff filters. The pooled peaks, retentates and ultrafiltrates each inhibited the angiotensin-converting enzyme activity, suggesting the presence of large and small molecular weight reversible angiotensin-converting enzyme inhibitors in association with the solubilized (membranous) particulate angiotensin-converting enzyme fraction. These results expand upon earlier observations on the existence of angiotensin-converting enzyme inhibitors in mammalian serum by observing an increasing angiotensin-converting enzyme activity with increasing dilution. This activity was eluted in multiple peaks, including elution with the cysteine eluate, suggesting that the angiotensin-converting enzyme, as well as other proteins, may react covalently with the sulfhydryl functional group of the immobilized captopril in a transsulfhydration reaction cleaving the disulfide bonds in proteins. Subsequent elution with cysteine affects an additional transsulfhydration reaction, releasing the proteins from the column. It is further postulated that air oxidation of the proteins permits reformation of disulfide bonds, yielding some active angiotensin-converting enzyme. Having in mind the possibility of lipophilic angiotensin-converting enzyme inhibitors crossing the blood-brain barrier as a means of treatment of alcohol abuse, the intriguing presence of a naturally occurring angiotensin-converting enzyme inhibitors in the particulate, lipid-rich fraction of the lung cell raises the theory that inhibitors such as these might cross the blood-brain barrier to serve as downregulators of alcohol consumption.     

Molecular cloning and characterization of NESP55, a novel chromogranin-like precursor of a peptide with 5-HT1B receptor antagonist activity

The chromogranins comprise a class of acidic proteins that are secreted from large dense core vesicles and expressed in neuronal and endocrine tissues. We describe here the molecular characterization of NESP55 (neuroendocrine secretory protein of Mr 55,000), a novel member of the chromogranins. Several NESP55 cDNA clones were isolated from bovine chromaffin cell libraries. The cDNA sequence of NESP55 totals 1499 nucleotides. All of the clones that were isolated contained in their 3'-untranslated mRNA a sequence that was homologous to exon 2 of the G-protein Gsalpha. The open reading frame encodes for an acidic and hydrophilic protein of 241 amino acids with a predicted molecular mass of 27,494 Da. An antiserum directed against the C terminus of NESP55 labeled a band of Mr 55,000 with an acidic pI ranging from 4.4 to 5.2 in one- and two-dimensional immunoblots of secretory proteins from chromaffin granules. NESP55 is localized within the cell to the large dense secretory vesicles and is expressed, apart from the adrenal medulla, in the anterior and posterior pituitary and various regions of the brain. For the physiological function, one interesting factor has emerged. NESP55 is proteolytically processed within the chromaffin granule to smaller peptides that might be physiologically active. One tetrapeptide, Leu-Ser-Ala-Leu (LSAL), present in the NESP55 sequence and flanked by arginine residues suitable for cleavage by prohormone convertases, has been identified recently as an endogenous antagonist of the serotonergic 5-HT1B receptor subtype. Alterations in the serotonergic system are thought to play an important role in mental disorders, especially depression, and might be related to abnormal ethanol consumption. It is tempting to speculate that increased expression of NESP55 or its proteolytically derived peptide LSAL might contribute to the pathophysiology of the serotonergic transmission.     

Kinetic analysis of respiratory tract proteins recovered during a sequential lavage protocol

Although bronchoalveolar lavage (BAL) has been used as a research tool for over a decade, the technique of lavage has varied markedly between laboratories. For example, lavage instillate volumes from 50 to 300 ml have been used, and yet the influence of the variable of total lavage volume on subsequent protein recovery is uncertain. We performed sequential BAL (50 ml/aliquot; total volume, 300 ml) of the right middle lobe of 14 normal volunteers and separately processed and analyzed recovered aliquots for the absolute and relative concentrations of several protein substances. These proteins include free secretory component and secretory IgA, which emanate from airway secretions, and IgG, which is thought to transude from more distal alveolar sites. Analysis of these data showed a marked decrease in the absolute concentration of all proteins measured in serial aliquots. Analysis of protein ratios in sequential aliquots, however, revealed no significant change from the first to the fifth recovered aliquot. Finally, we analyzed the influence of the size of the first recovered aliquot on absolute and relative concentrations of proteins. Here there seemed to be a trend indicating preferential recovery of airway proteins in smaller aliquots. This was significant for the ratio of free secretory component to albumin (p less than 0.05). We conclude that lung proteins are efficiently and homogeneously sampled with 100 ml of lavage instillate. Larger volumes will add more protein but not alter protein ratios. Lavage with smaller volumes may preferentially sample airway proteins.     

Genetic heterogeneity of ischemic (coronary) heart disease

Results are presented on a study of the blood coagulation system and some indices of serum lipids and proteins in 133 normal individuals and probands with ischaemic heart disease and their 681 relatives. The examination of the relatives of probands with different types of biochemical disorders revealed a similar biochemical background in the probands and the members of their families. The disorders in blood biochemistry in the probands were most similar in the parents, the children of the probands' siblings, and less distinct in more distant relatives (cousins, nephews and nieces, etc.), biochemical disorders similar to those of the probands being found in young persons (14-16 years old) and reappearing in several generations. The author concludes on the genetic heterogeneity of ischaemic (coronary) heart disease and underlying coronary atherosclerosis.     

Oral immunization of mice with attenuated Salmonella typhimurium aroA expressing a recombinant Mycoplasma hyopneumoniae antigen (NrdF)

Mycoplasma hyopneumoniae is the etiological agent of porcine enzootic pneumonia, a commercially expensive respiratory disease of swine. Salmonella typhimurium SL3261 was used as a live carrier of plasmid pKF1, which encodes a 15-kDa recombinant M. hyopneumoniae protein. This expressed recombinant protein consists of the carboxy-terminal 11 kDa of a 42-kDa M. hyopneumoniae NrdF ribonucleotide reductase R2 subunit protein. Rabbit anti-15-kDa serum was able to inhibit the growth of viable M. hyopneumoniae J in vitro. When used as a live oral vaccine, S. typhimurium SL3261(pKF1) induced a significant secretory immunoglobulin A immune response in the lungs of mice orally immunized against the M. hyopneumoniae antigen. Utilization of live oral vaccines expressing potentially protective M. hyopneumoniae proteins, such as the NrdF antigen, which can stimulate a lung mucosal response against surface-accessible proteins may provide a cost-effective alternative to the present control strategies used for porcine enzootic pneumonia.     

Pathophysiology of antigen 85 in patients with active tuberculosis: antigen 85 circulates as complexes with fibronectin and immunoglobulin G

Antigen 85 (Ag85) complex proteins are major secretory products of Mycobacterium tuberculosis and induce strong cellular and humoral immune responses in infected experimental animals and human beings. We have previously shown that nanogram doses of these 30- to 32-kDa fibronectin-binding proteins inhibit local expression of delayed hypersensitivity by a T-cell fibronectin-dependent mechanism. Circulating levels of Ag85 might be expected to be elevated in patients with active tuberculosis and possibly to play a role in systemic anergy in these patients. To test this hypothesis, Ag85 was measured in serum and urine by a monoclonal antibody-based dot immunobinding assay in 56 patients and controls with known skin test reactivity. Median serum Ag85 levels were 50- to 150-fold higher in patients with active tuberculosis than in patients with active M. avium-intracellulare disease or other nontuberculous pulmonary disease or in healthy controls (P < 0.001). The median and range of serum Ag85 in patients with active tuberculosis was not significantly different between skin test-positive and -negative subjects. Patients with active M. avium disease could be distinguished from those with disease due to M. tuberculosis by monoclonal anti-Ag85 antibodies of appropriate specificities. No increases in urinary Ag85 were detected in any patient, regardless of the Ag85 level in serum. Chromatographic analysis and immunoprecipitation studies of serum revealed that Ag85 existed in the serum of these patients complexed to either fibronectin or immunoglobulin G (IgG). Uncomplexed circulating Ag85 was demonstrable in serum from fewer than 20% of patients with active tuberculosis. In patients with active tuberculosis, Ag85 is therefore likely to circulate primarily as complexes with plasma fibronectin and IgG rather than in unbound form. The existence of Ag85 complexes with plasma proteins would account for its lack of urinary clearance.     

Expression of progesterone receptor isoforms in corpora lutea of human subjects: correlation with serum oestrogen and progesterone concentrations

To understand the biological significance of progesterone receptor forms A (PR-A) and B (PR-B) in human corpus luteum, the expression of mRNA and serum steroid hormone concentrations were determined simultaneously in the luteal stages. The expression of PR-A mRNA predominated over PR-B mRNA in all samples analysed. Total PR (PR-AB) and PR-B mRNA concentrations at the late secretory phase were significantly (P < 0.01) lower than those at the early and mid secretory phases of the menstrual cycle. The ratio of PR-B to PR-AB mRNA concentration showed no significant change during the secretory phase. In the early and mid secretory phases, there was a negative correlation between PR-B mRNA concentration and serum progesterone concentration, and between the ratio of PR-B to PR-AB mRNA concentrations and serum progesterone concentration (P < 0.01). These findings suggest that human corpus luteum might intracellularly synthesize PR-A and PR-B, and thus be involved in the steroid functional regulation of the corpus luteum, especially at the early and mid secretory phases, and that progesterone might regulate the synthesis of PR-A and PR-B.     

Anemia and neutropenia due to copper deficiency in enteral nutrition

Although thrombomodulin (TM) in circulating blood is regarded as an indicator of vascular endothelial disorders, blood TM levels are also known to be affected by renal dysfunction. We measured plasma TM levels in primary glomerular disease (PGD) and lupus glomerulonephritis (GN) with the EIA method, and assessed the extent to which renal dysfunction and endothelial disorders contribute to plasma TM levels in these diseases. The plasma TM/serum creatinine (TM/Cr) ratio was significantly higher in lupus GN patients than in PGD patients or normal controls. A significant positive correlation was found between plasma TM and serum Cr levels in both PGD and lupus GN patients, but the slope (A) of the regression line (TM = A.Cr+B) in lupus GN patients was significantly steeper than in PGD patients. We conclude that plasma TM levels are greatly influenced by renal dysfunction, but that not only renal dysfunction but endothelial disorders may be an important determinant of increased plasma TM levels in diseases such as lupus GN.     

Peak expiratory flow rate (PEF) and serum eosinophil cationic protein (ECP) changes in nocturnal asthmatics

We have investigated the serum ECP and peak expiratory flow rate in 20 patients with nocturnal asthma. Changes of PEF were measured in every 2 hours around the whole day, and the blood samples were obtained at 4:00 and 16:00 to measure the serum ECP level and the peripheral Eo numbers. In addition, 10 asthmatics as well as normal subjects received methacholine challenge at 4:00 and 16:00. It was found that the PEF reached the lowest point at 4:00 and obviously less than that at 16:00 (187.50 +/- 120.31 L/min vs 313.00 +/- 108.14 L/min, P < 0.05), that the airway reactivity at 4:00 was significantly higher than at 16:00 (P < 0.05) and the difference of MCH-PC20 between the two time points was 0.34 +/- 0.31 mg/ml, that the serum ECP level at 4:00 was obviously higher than that at 16:00 (11.14 +/- 7.40 micrograms/ml vs 5.49 +/- 4.12 micrograms/ml, P < 0.05). The change rate of PEF markedly related to the change of serum ECP between the two time points (r = 0.61, P < 0.05). The findings suggested that the activation of Eo and its release of ECP might be effect of the circadian-rhythmic change of pulmonary functions in nocturnal asthma.     

Induction of subcutaneous tissue fibrosis in newborn mice by transforming growth factor beta--simultaneous application with basic fibroblast growth factor causes persistent fibrosis

OBJECTIVE: To determine the effect of serum P on endometrial histology in stimulated cycles. DESIGN: Prospective clinical study. SETTING: Community hospital-based donor oocyte program. PATIENT(S): Fertile young oocyte donors and infertile donor oocyte recipients. INTERVENTION(S): Oocyte donors underwent gonadotropin stimulation after midluteal pituitary suppression. Endometrial biopsies were obtained at the time of oocyte retrieval. MAIN OUTCOME MEASURE(S): Endometrial histology and serum P levels in oocyte donors. Pregnancy and implantation rates in oocyte recipients. RESULT(S): Thirteen biopsy specimens (52.0%) showed in-phase mixed proliferative pattern (days 14 to 15), whereas 12 (48.0%) were secretory (days 16 to 17). On the day of hCG, subjects with secretory endometrium had higher P of 1.7 ng/mL (5.4 nmol/L) than women with the mixed pattern (0.8 ng/mL [2.5 nmol/L]). Progesterone > or = 0.9 ng/mL had a 78.6% positive predictive value for secretory transformation. In 75.0% of cycles with secretory endometrium, P was > or = 0.9 ng/mL, (2.9 nmol/L) as early as 2 days before hCG. Both mixed and secretory patterns were associated with similar clinical pregnancy rates (57.1% and 60.0%, respectively) and delivery rates (38.1% and 50.0%, respectively) in recipients. CONCLUSION(S): Subtle elevation of P induced secretory endometrial transformation without reduction in embryo viability.     

Biochemistry of airway mucus secretions

Tracheobronchial secretions are a complex mixture of secretory fluids derived from sources within the lung. Important constituents include the mucous glycoproteins, other secretory proteins, serum proteins, lipids, salts; water makes up 95% of mucus by weight. These secretions form two phases at the epithelial surface: a mucous gel and an aqueous layer (periciliary fluid). Polymerization and aggregation of mucous glycoproteins create the gel matrix. Other macromolecules such as lysozyme, albumin, and immunoglobulin A also may participate in the process of gelation. Intermolecular forces contributing to gelation include disulfide bonding, sugar-sugar interactions between adjacent glycoproteins, and ionic interactions between the glycoprotein anionic groups (sialic acid carboxyl and sulfate) and cationic components in the secretions. Respiratory tract mucous glycoproteins are large, extended molecules, which have a high carbohydrate content. They are polydisperse, with variation occurring largely in the content of sulfated sugars and sialic acid. Factors such as cell of origin, chronic lung disease, and pharmacologic effects influence the density of these anionic (acidic) groups. Variation in acidic properties may influence the physical and virus-binding properties of mucus. Little information is available concerning the biosynthetic mechanisms in airway epithelium through which these variations are effected.     

Protein accumulation in cerebrospinal fluid during -90 degrees head-down tilt in rabbit

Plasma proteins are only somewhat larger than the intercellular spaces of the cerebral microvessels that constitute the blood-brain barrier or of the choroid plexus villi that elaborate cerebrospinal fluid (CSF). We hypothesized that the integrity of these barriers in anesthetized rabbits might be compromised during head-down tilt (HDT). Plasma protein and osmolality, hematocrit, and CSF protein concentration were compared in rabbits exposed to 1 h of HDT (n = 20) and prone rabbits (n = 10). In addition, the concentration of trypan blue dye, injected intravenously at the end of HDT or the prone position, was measured in brain homogenate. Finally, arterial blood pressure was measured via a catheterized carotid artery. HDT disrupted the barrier between blood and CSF, as indicated by a significantly (P < 0.01) greater brain trypan blue concentration in the HDT rabbits [172.2 +/- 14.4 (SD) micrograms/g dry wt] than in the prone rabbits (29.8 +/- 4.4 micrograms/g dry wt). Moreover CSF protein 5 min after HDT onset was significantly increased compared with control in HDT rabbits (54.6 +/- 1.9 vs. 81.4 +/- 5.2 mg/dl; n = 8) but not in prone rabbits (55.6 +/- 2.7 vs. 57.2 +/- 5.0 mg/dl; n = 6). Changes in the plasma protein-to-hematocrit ratio in the HDT animals, but not in the prone animals, were also compatible with a loss of fluid from the vascular compartment.(ABSTRACT TRUNCATED AT 250 WORDS)