Selective head cooling with hypothermia suppresses the generation of platelet-activating factor in cerebrospinal fluid of newborn infants with perinatal asphyxia.

Hypoxic-ischemic encephalopathy (HIE) remains one of the most important neurologic complications in the newborn. Several experimental and clinical studies have shown that hypothermia is the most effective means known for protecting the brain against hypoxic-ischemic brain damage. Furthermore, recent data have suggested that platelet-activating factor (PAF) could play a pathophysiologically important role in the progression of hypoxic-ischemic brain injury. The aim of the present study was to investigate the role of head cooling combined with minimal hypothermia in short-term outcome of infants with perinatal asphyxia. In addition, we have examined the effect of head cooling combined with minimal hypothermia on PAF concentrations in cerebrospinal fluid (CSF) after hypoxic-ischemic brain injury. The group of asphyxiated infants (Group 1) consisted of 21 full-term (gestational age >37 weeks). These infants were randomized and divided into either a standard therapy group (Group 1a; n=10) or cooling group (Group 1b; n=11). Head cooling combined with minimal hypothermia (rectal temperature 36.5-36 degrees C) was started as soon as practicable after birth. The infants were cooled for 72h and then were rewarmed at 0.5 degrees C/h. The control group (Group 2) consisted of seven full-term infants and none of these infants showed any sign of asphyxia. To measure PAF concentration in CSF, CSF with lumbar puncture was collected into tubes immediately before the cooling (1-3h after birth) and again after 36h. We had no evidence of severe adverse events related to hypothermia. In Group 1a, two infants died after 72h of life; however, all newborn infants in Group 1b survived. Convulsion required treatment in three infants of standard therapy group (1a); none of the infants in Group 1b had clinical seizure activity. Abnormal EEG patterns were found in four infants of Group 1a; no EEG abnormalities were noted in Group 1b (P<0.05). On admission (before cooling), PAF concentration in CSF of asphyxiated infants was found to be significantly higher when compared with that of control (P<0.001). Mean PAF concentration before initiation of the study was similar in the two asphyxiated groups (Group 1a vs. 1b) (P>0.05). Obtained PAF level in CSF after 36h, showed a profound decline in cooling group of infants compared to Group 1a infants (P<0.01). In conclusion, the present study suggests that cerebral cooling with minimal hypothermia started soon after birth has no severe adverse effects during 72-h cooling period and that short-term outcome of infants are encouraging. Our results also support the hypothesis PAF an important mediator in hypoxic-ischemic brain injury and demonstrate that head cooling combined with minimal hypothermia reduces the normal increase in PAF following hypoxic-ischemic brain injury in full-term infants.

Platelet activating factor is elevated in cerebral spinal fluid and plasma of patients with relapsing-remitting multiple sclerosis.

Platelet-activating factor (PAF) is a phospholipid mediator of inflammation with a wide range of biological activities, including the alteration of barrier function of endothelium. A biological assay combined with high pressure liquid chromatography-tandem mass spectrometry showed that plasma and cerebral spinal fluid (CSF) PAF levels in 20 patients with relapsing/remitting or secondary progressive multiple sclerosis (MS) studied by magnetic resonance imaging (MRI) were significantly higher than in healthy controls (plasma: 3.29+/-4.52 vs. 0.48+/-0.36 ng/ml, p < 0.002; CSF: 4.95+/-6.22 ng/ml vs. 0.01+/-0.04 ng/ml, p < 0.0001). Values were also significantly higher in relapsing/remitting than in secondary progressive (plasma: 5.10+/-4.97 vs. 0.52+/-0.85 ng/ml, p < 0.005; CSF: 8.59+/-6.39 vs. 0.55+/-0.68 ng/ml, p < 0.002). It was also found that both plasma (R2: 0.65) and CSF (R2:0.72) levels were correlated with the MRI number of gadolinium enhancing lesions, which are markers of blood-brain barrier (BBB) injury, whereas their peaks were not correlated with the MRI number of white matter lesions, nor with the expanded disability status score (EDSS) according to Kurtze [Kurtze, J.F., 1983. Rating neurological impairment in multiple sclerosis: an expanded disability scale (EDSS). Neurology 33, 1444-1452]. Both plasma and CSF in patients with relapsing/remitting MS and marked gadolinium enhancement contained the two major molecular species of PAF: 1-0-hexadecyl- (C16:O) and 1-0-octadecyl-sn-glycero-3-phosphocholine (C18:O). The ratio of the two molecular species was different in the two biological fluids, being PAF C18:0 more abundant in CSF and PAF C16:0 in plasma, indicating a different cellular origin of PAF or different enzymatic processing. These findings suggest that PAF is a significant mediator of BBB injury in the early stages of MS, rather than a marker of its progression and severity.

[High performance thin layer chromatographic (HPTLC) determination of PAF in cerebrospinal fluid of patients with subarachnoid hemorrhage(SAH)].

The Platelet Activating Factor (PAF) is believed to be the major function in human after cerebral vascular spasm and cerebral ischemia. PAF has been found to participate in cerebral vascular spasm and cerebral ischemia by the basic and clinical study. The symptom of cerebral vascular spasm and cerebral ischemia has appeared with SAH. It has not been reported that the rule and change of PAF with SAH. In the present work, the concentration of PAF in human cerebral spinal fluid (CSF) with SAH were determined by high performance layer thin chromatography. The TLC plate was coated with high performance silica gel G using V(chloroform):V(methanol):V(water) = 65:35:6 as developing solvent. The PAF was determined by TLC scanning method and detected at 630 nm. The method was applied to determine the concentration of PAF in 16 CSF samples with SAH. The samples were collected in 1-3 d, 7-10 d and 14-21 d. CSF samples were deproteinized with methanol and chloroform. After centrifugation, the chloroform layer separated was dried at room temperature with nitrogen and stored under 20 degrees C in the refrigerator. The linear range of the method was 0.5-2.5 micrograms/L with regression coefficient of 0.9990. The lower limit of detection were 50 ng/L. The recovery of the method was 98.6%. The method enables a simple, rapid and reproducible quantification of PAF with SAH.

Administration of methylprednisolone acetate into the subdural cavity in an infant with subdural fluid collection. PAF is a good indicator of the efficacy of the treatment.

We report on the successful treatment of a case of infantile subdural fluid collection after cardiac surgery by administration of methylprednisolone acetate into the subdural cavity. The protein content in subdural fluid did not change even after administration of this steroid and was not a good indicator of the efficacy of treatment; however, the content of platelet-activating factor (PAF), an inflammatory mediator, in the fluid removed from the subdural cavity decreased rapidly after administration of the steroid. Subdural fluid collection subsequently decreased and mental retardation was improved. Our findings suggest that PAF content is a good indicator of the severity of infantile subdural fluid collection.

The metabolism of platelet-activating factor in severe and cerebral malaria.

In order to examine the effects of platelet-activating factor (PAF) in complicated Plasmodium falciparum infections, plasma concentrations of lyso-PAF, stable metabolite and principal precursor of PAF, were measured in 25 Vietnamese adults with severe malaria. The concentration of PAF in the cerebrospinal fluid (CSF) was determined in a sub-group of 23 comatose patients and, together with that of lyso-PAF, in the plasma of 20 patients on recovery of consciousness. The concentration of lyso-PAF in the plasma was depressed on admission to hospital (median [range]; 21 [8-143] vs. 293 [215-410] ng/ml in 10 controls; P < 0.001). There was, however, no change in plasma activity of acetylhydrolase which converts PAF to lyso-PAF (P > 0.01 vs. controls) while simultaneous reduction in the concentration of lipoproteins associated with lyso-PAF were less than those of lyso-PAF per se in the plasma. The plasma concentration of lyso-PAF on admission was associated with parasitaemia and the concentration of serum triglycerides (rs = -0.42, P = 0.04 in each case), the latter being consistent with hepatic effects of PAF reported in previous studies. CSF concentrations of PAF on admission were low (2.3 [0.5-7.7] vs. 0.9 [0-2.5] ng/ml after recovery, P < 0.01) compared with values reported previously in bacterial meningitis. Plasma concentrations of lyso-PAF after recovery lay between admission and control values. While increased availability of PAF may reflect parasite burden and may modulate liver-mediated metabolic disturbances such as hypoglycaemia and lactic acidosis, the role of PAF in cerebral malaria is uncertain.

Platelet-activating factor: a candidate human immunodeficiency virus type 1-induced neurotoxin.

The pathogenesis of central nervous system disease during human immunodeficiency virus type 1 (HIV-1) infection revolves around productive viral infection of brain macrophages and microglia. Neuronal losses in the cortex and subcortical gray matter accompany macrophage infection. The question of how viral infection of brain macrophages ultimately leads to central nervous system (CNS) pathology remains unanswered. Our previous work demonstrated high-level production of tumor necrosis factor alpha, interleukin 1 beta, arachidonic acid metabolites, and platelet-activating factor (PAF) from HIV-infected monocytes and astroglia (H. E. Gendelman, P. Genis, M. Jett, and H. S. L. M. Nottet, in E. Major, ed., Technical Advances in AIDS Research in the Nervous System, in press; P. Genis, M. Jett, E. W. Bernton, H. A. Gelbard, K. Dzenko, R. Keane, L. Resnick, D. J. Volsky, L. G. Epstein, and H. E. Gendelman, J. Exp. Med. 176:1703-1718, 1992). These factors, together, were neurotoxic. The relative role(s) of each of these candidate neurotoxins in HIV-1-related CNS dysfunction was not unraveled by these initial experiments. We now report that PAF is produced during HIV-1-infected monocyte-astroglia interactions. PAF was detected at high levels in CSF of HIV-1-infected patients with immunosuppression and signs of CNS dysfunction. The biologic significance of the results for neurological disease was determined by addition of PAF to cultures of primary human fetal cortical or rat postnatal retinal ganglion neurons. Here, PAF at concentrations of > or = 300 pg/ml produced neuronal death. The N-methyl-D-aspartate receptor antagonist MK-801 or memantine partially blocked the neurotoxic effects of PAF. The identification of PAF as an HIV-1-induced neurotoxin provides new insights into how HIV-1 causes neurological impairment and how it may ultimately be ameliorated.

Platelet-activating factor (PAF) concentration and PAF acetylhydrolase activity in cerebrospinal fluid of patients with subarachnoid hemorrhage.

The authors studied the sequential changes in platelet-activating factor (PAF) and PAF acetylhydrolase in the cerebrospinal fluid (CSF) of patients with subarachnoid hemorrhage (SAH). Levels of PAF in CSF showed a gradual increase after the onset of SAH, with a subsequent decrease. The PAF concentration between 5 and 9 days after SAH was greater in patients with cerebral infarction due to vasospasm than in patients without infarction. Conversely, PAF acetylhydrolase activity decreased gradually after SAH, then increased. The enzyme activity for the same period was smaller in patients with cerebral infarction than in patients without infarction. The distribution of the days of maximum PAF concentration and minimum PAF acetylhydrolase activity did not differ significantly between the two groups. The CSF as a source of PAF acetylhydrolase activity gave an apparent Michaelis constant value of 90.8 microM and a maximum velocity of 0.2 nmol/min/mg. The optimum pH level for the PAF acetylhydrolase activity obtained from CSF was 6.5. The enzyme activity of CSF increased, depending on the incubation temperature, ranging from 25 degrees to 45 degrees C. Ethylene-glycol tetra-acetic acid (1 mM) was found to inhibit PAF acetylhydrolase activity in CSF obtained from patients with SAH. Unaltered PAF acetylhydrolase activity was inhibited by adding an aliquot of CSF and minimum PAF acetylhydrolase activity decreased following SAH. Two peaks of inhibitory activity were detected on Sephacryl S-200 HR gel filtration: one was eluted in void volume and the other with an apparent molecular mass of 13 kD. The inhibitory activity was very labile and was lost completely within 3 days of incubation at 4 degrees C. The regulation of the PAF concentration in the CSF of SAH patients is discussed.

Changes in platelet-activating factor, catecholamine, and serotonin concentrations in brain, cerebrospinal fluid, and plasma of pichinde virus-infected guinea pigs.

Brain concentrations of platelet-activating factor (PAF), catecholamines, and serotonin were measured in control and Pichinde virus-infected strain 13 guinea pigs on postinoculation day (PID) 12. After virus inoculation, PAF concentrations increased 81% in cerebrum, 147% in diencephalon-brain stem, and 110% in cerebellum from baseline values of 2.6 +/- 0.3, 4.3 +/- 0.2, and 6.1 +/- 0.5 (ng/g wet tissue), respectively. Dopamine concentrations in the infected cerebrum and diencephalon-brain stem increased significantly, whereas norepinephrine concentration increased only in cerebrum. However, serotonin concentrations in all three regions of infected brain decreased significantly as compared with control values. There were no significant changes in epinephrine concentrations of infected brain. Norepinephrine and epinephrine concentrations in plasma and cerebrospinal fluid on PID 7 and 12 increased significantly as compared with control values, while plasma dopamine concentration increased significantly on PID 7. Increased brain PAF, dopamine, and and norepinephrine concentrations with decreased brain serotonin concentrations may mediate the hyperactivity of the hypothalamic-pituitary-adrenal axis and involve some unknown pathophysiologic processes of arenaviral infection. Furthermore, increased plasma catecholamine concentrations are associated with stress and may be partially responsible for the development of cardiovascular dysfunction and pulmonary edema during this viral disease.

Increased release of tumor necrosis factor-alpha into the cerebrospinal fluid and peripheral circulation of aged rats.

BACKGROUND AND PURPOSE: We earlier reported that risk factors for stroke prepare brain stem tissue for a modified Shwartzman reaction, including the development of ischemia and hemorrhage and the production of tumor necrosis factor-alpha, after a provocative dose of lipopolysaccharide. In the present study, we sought to determine whether blood and central nervous system cells of rats with the stroke risk factor of advanced age produce more proinflammatory and prothrombotic mediators than do those of young rats of the same strain. METHODS: Levels of tumor necrosis factor-alpha and platelet activating factor in the cerebrospinal fluid and tumor necrosis factor-alpha in the serum of 2-year-old and 16-week-old Sprague-Dawley rats were monitored before and after challenge with lipopolysaccharide. RESULTS: No consistent tumor necrosis factor-alpha activity was found in the cerebrospinal fluid or blood of control animals. Intravenous administration of lipopolysaccharide (1.8 mg/kg) increased serum tumor necrosis factor-alpha levels but had no effect on tumor necrosis factor-alpha in the cerebrospinal fluid. Serum tumor necrosis factor-alpha increased much more in aged rats than in young rats. When lipopolysaccharide was injected intracerebroventricularly, tumor necrosis factor-alpha activity in cerebrospinal fluid increased significantly more in old rats than in young rats. Baseline levels of platelet activating factor in cerebrospinal fluid were significantly higher in old rats than in young rats, and the levels increased to a greater degree in aged rats on stimulation. CONCLUSIONS: Rats with the stroke risk factor of advanced age respond to lipopolysaccharide with a more exuberant production of tumor necrosis factor-alpha and platelet activating factor than young rats of the same strain. These findings are consistent with our working hypothesis that perivascular cells are capable of exaggerated signaling of endothelium through cytokines such as tumor necrosis factor-alpha in animals with stroke risk factors. The effect of such signaling might be to prepare the endothelium of the local vascular segment for thrombosis or hemorrhage in accord with the local Shwartzman reaction paradigm.

Release of proinflammatory and prothrombotic mediators in the brain and peripheral circulation in spontaneously hypertensive and normotensive Wistar-Kyoto rats.

BACKGROUND AND PURPOSE: We reported previously that stroke risk factors prepared the brain stem for the development of ischemia and hemorrhage and induced the production of tumor necrosis factor following an intrathecal injection of lipopolysaccharide, a prototypic monocyte-activating stimulus. This study evaluates whether blood or brain cells of hypertensive rats produce more proinflammatory and prothrombotic mediators than do blood or brain cells of normotensive rats. METHODS: Levels of tumor necrosis factor, platelet-activating factor, 6-ketoprostaglandin F1 alpha, and thromboxane B2 in the cerebrospinal fluid and blood of spontaneously hypertensive and normotensive Wistar-Kyoto rats were monitored before and after a challenge with lipopolysaccharide. RESULTS: Little or no activity from these mediators was found in the cerebrospinal fluid or blood of saline-injected control animals. Intravenous administration of lipopolysaccharide (0.001, 0.1, and 1.8 mg/kg) produced dose-dependent increases in blood levels of all mediators in hypertensive rats. In normotensive rats the levels were less than in hypertensive rats and were not clearly dose-related. When lipopolysaccharide was injected intracerebroventricularly, more tumor necrosis factor was measured in the cerebrospinal fluid than in the blood, suggesting local synthesis of this cytokine. Levels of tumor necrosis factor and platelet-activating factor in the cerebrospinal fluid were higher in hypertensive than in normotensive rats. The thromboxane A2/prostacyclin ratio was not altered significantly between the two rat strains. CONCLUSIONS: It is suggested that the higher incidence of brain stem ischemia and hemorrhage after the intrathecal injection of lipopolysaccharide in hypertensive rats than in normotensive rats might be related to the higher levels of the two cytotoxic factors tumor necrosis factor and platelet-activating factor produced in response to such challenge.

Cerebrospinal fluid cachectin/tumor necrosis factor-alpha and platelet-activating factor concentrations and severity of bacterial meningitis in children.

In prospective studies, tumor necrosis factor (TNF alpha) was detected in cerebrospinal fluid (CSF) of 33 of 38 children with bacterial meningitis (BM) but in none of 15 with viral meningitis/encephalitis (P less than .001). BM CSF TNF alpha (less than 35 to greater than 25,500 pg/ml) correlated with CSF bacterial density (P less than .01), CSF protein (P less than .001), endotoxin (LPS) in gram-negative disease (P less than .01), and consecutive febrile hospital days (P less than .001); initial CSF TNF alpha greater than 1000 pg/ml was associated with seizures (P less than .05). Only 5 children with BM (13%) had detectable plasma TNF alpha activity on admission. A higher proportion who died had detectable plasma TNF alpha activity compared with survivors (3/4 vs. 2/34, P less than .005). Platelet-activating factor (PAF) in CSF was higher in 19 children with Haemophilus influenzae meningitis than in 17 controls (P less than .01) and correlated with bacterial density (P less than .01), CSF LPS (P less than .01), CSF TNF alpha levels (P less than .01), and the Herson-Todd severity score (P less than .01). Elevated CSF TNF alpha and PAF are often present in children with BM and are associated with seizures and severity of disease. Detectable CSF TNF alpha appears to distinguish BM from viral meningitis.