Increased metabolite production by deletion of an HDA1-type histone deacetylase in the phytopathogenic fungi, Magnaporthe oryzae (Pyricularia oryzae) and Fusarium asiaticum.

Histone deacetylases (HDACs) play an important role in the regulation of chromatin structure and gene expression. We found that dark pigmentation of Magnaporthe oryzae (anamorph Pyricularia oryzae) ΔMohda1, a mutant strain in which an orthologue of the yeast HDA1 was disrupted by double cross-over homologous recombination, was significantly stimulated in liquid culture. Analysis of metabolites in a ΔMohda1 mutant culture revealed that the accumulation of shunt products of the 1,8-dihydroxynaphthalene melanin and ergosterol pathways were significantly enhanced compared to the wild-type strain. Northern blot analysis of the ΔMohda1 mutant revealed transcriptional activation of three melanin genes that are dispersed throughout the genome of M. oryzae. The effect of deletion of the yeast HDA1 orthologue was also observed in Fusarium asiaticum from the Fusarium graminearum species complex; the HDF2 deletion mutant produced increased levels of nivalenol-type trichothecenes. These results suggest that histone modification via HDA1-type HDAC regulates the production of natural products in filamentous fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: Natural products of fungi have significant impacts on human welfare, in both detrimental and beneficial ways. Although HDA1-type histone deacetylase is not essential for vegetative growth, deletion of the gene affects the expression of clustered secondary metabolite genes in some fungi. Here, we report that such phenomena are also observed in physically unlinked genes required for melanin biosynthesis in the rice blast fungus. In addition, production of Fusarium trichothecenes, previously reported to be unaffected by HDA1 deletion, was significantly upregulated in another Fusarium species. Thus, the HDA1-inactivation strategy may be regarded as a general approach for overproduction and/or discovery of fungal metabolites.

Effects of acivicin on growth, mycotoxin production and virulence of phytopathogenic fungi.

Acivicin is an inhibitor of γ-glutamyl transpeptidase and glutamine amidotransferase. When grown on a synthetic minimal agar medium, acivicin strongly inhibited the growth of Magnaporthe oryzae and Alternaria brassicicola, and to a lesser extent, Botrytis cinerea. However, only partial or marginal growth inhibition was observed with regard to Fusarium sporotrichioides and Fusarium graminearum. The growth retardation caused by acivicin was significantly alleviated by cultivating the fungus on a nutrient-rich medium. The inhibition of M. oryzae growth caused by 1 µmol l(-1) of acivicin on minimal agar medium was subdued by the addition of specific single amino acids, including His, a branched-chain amino acid (Leu, Ile or Val), an aromatic amino acid (Trp, Tyr or Phe), Met or Gln, at a concentration of 0·4 mmol l(-1). Trichothecene production by F. graminearum in trichothecene-inducing liquid medium was reduced significantly in the presence of acivicin despite its inability to inhibit growth in the trichothecene-inducing liquid medium. Foliar application of conidia in the presence of acivicin reduced the severity of rice blast disease caused by M. oryzae. These results suggest the usefulness of this modified amino acid natural product to mitigate agricultural problems caused by some phytopathogenic fungi. Significance and impact of the study: Fusarium head blight or scab disease and rice blast, caused by Fusarium graminearum and Magnaporthe oryzae, respectively, are major diseases of cereal crops that cause a significant loss of yield and deterioration in the quality of the grain. The present study investigated the effects of acivicin, a glutamine amino acid analog, on the physiology of various phytopathogenic fungi. Application of acivicin to a fungal culture and conidial suspension reduced mycotoxin production by the wheat scab fungus and the severity of rice blast, respectively. These results suggest the possibility that acivicin may serve as a lead compound to develop agricultural chemicals for the control of some plant diseases.

Heme oxygenase-1 gene induction as an intrinsic regulation against delayed cerebral vasospasm in rats.

Delayed cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) causes cerebral ischemia and infarction. To date, the pathogenesis and gene expression associated with vasospasm remain poorly understood. The present study used fluorescent differential display to identify differentially expressed genes in a rat model of SAH. By using quantitative RT-PCR, we found that heme oxygenase-1 (HO-1) mRNA was prominently induced in the basilar artery and modestly in brain tissue in a rat vasospasm model. A significant correlation was observed between the degree of vasospasm and HO-1 mRNA levels in the basilar arteries exhibiting vasospasm. Intracisternal injection of antisense HO-1 oligodeoxynucleotide (ODN) significantly delayed the clearance of oxyhemoglobin and deoxyhemoglobin from the subarachnoid space and aggravated angiographic vasospasm. Antisense HO-1 ODN inhibited HO-1 induction in the basilar arteries but not in the whole brain tissue. This phenomenon was not observed in the nontreated, sense HO-1 ODN-treated, or scrambled ODN-treated arteries. We report the protective effects of HO-1 gene induction in cerebral vasospasm after SAH, a finding that should provide a novel therapeutic approach for cerebral vasospasm.

The cyanobacterium, Synechococcus sp. PCC7942, possesses two distinct genes encoding cation-transporting P-type ATPases.

P-type (or E1 E2-type) ATPases comprise a large family of prokaryotic and eukaryotic proteins capable of transporting a variety of cations, and function in a wide variety of cellular processes. The present study was carried out to search for genes encoding P-type ATPases in the phototrophic cyanobacterium, Synechococcus sp. PCC7942. We succeeded in cloning two genes each encoding P-type ATPases from this bacterium. It was found that Synechococcus at least, two distinct P-type ATPases; one belongs to the family of typical prokaryotic P-type ATPases and the other markedly resembles eukaryotic P-type ATPases. An insertion mutant lacking either of these two ATPase-genes was constructed. The results showed that the growth of these mutants is hypersensitive to osmotic stress upon addition of NaCl or sorbitol to the medium.

Three new nuclear genes, sigD, sigE and sigF, encoding putative plastid RNA polymerase sigma factors in Aarabidopsis thaliana.

Three new nuclear genes (sigD, sigE and sigF) of Arabidopsis thaliana, encoding putative plastid RNA polymerase sigma factors, were identified and analyzed. Phylogenetic analysis revealed that higher plant sigma factors fell into at least four distinct subgroups within a diverse protein family. In addition, Arabidopsis sig genes contained conserved chromosomal intron sites, indicating that these genes arose by DNA duplication events during plant evolution. Transcript analyses revealed two alternatively spliced transcripts generated from the sigD region, one of which is predicted to encode a sigma protein lacking the carboxy-terminal regions 3 and 4. Finally, the amino-terminal sequence of the sigF gene product was shown to function as a plastid-targeting signal using green fluorescent protein fusions.

Chloroplast development in Arabidopsis thaliana requires the nuclear-encoded transcription factor sigma B.

Development of plastids into chloroplasts, the organelles of photosynthesis, is triggered by light. However, little is known of the factors involved in the complex coordination of light-induced plastid gene expression, which must be directed by both nuclear and plastid genomes. We have isolated an Arabidopsis mutant, abc1, with impaired chloroplast development, which results in a pale green leaf phenotype. The mutated nuclear gene encodes a sigma factor, SigB, presumably for the eubacterial-like plastid RNA polymerase. Our results provide direct evidence that a nuclear-derived prokaryotic-like SigB protein, plays a critical role in the coordination of the two genomes for chloroplast development.

Signal transduction and osmoregulation in Escherichia coli: a novel mutant of the positive regulator, OmpR, that functions in a phosphorylation-independent manner.

In Escherichia coli, expression of the outer membrane proteins, OmpF and OmpC, is regulated by the regulatory factors, EnvZ and OmpR, at the transcriptional level in response to the medium osmolarity. In this particular osmotic regulation, phosphorylation of OmpR at an aspartate residue (Asp-55) by EnvZ plays an important role. The previously isolated mutant, ompR55Q, with the amino acid replacement of Asp-55 to Gln, exhibits an OmpF- and OmpC- phenotype. In this study, we isolated a novel type of ompR mutant, in which the defect caused by the ompR55Q mutation is suppressed. The intragenic suppressor mutation we isolated results in the amino acid replacement of Tyr-102 to Cys in the N-terminal domain of OmpR, and exhibits an OmpF+ and OmpC+ phenotype in response to the medium osmolarity in an EnvZ-independent manner. It was revealed that this amino acid replacement in OmpR enhances the in vitro DNA-binding ability to the cognate DNAs. These results suggested that OmpR is capable of functioning in a phosphorylation-independent manner under certain in vivo conditions, and further suggested that an EnvZ-independent mechanism may also be involved in the osmotically regulated expression of ompF and ompC.

Transmembrane signal transduction and osmoregulation in Escherichia coli: I. Analysis by site-directed mutagenesis of the amino acid residues involved in phosphotransfer between the two regulatory components, EnvZ and OmpR.

Previously, the transfer of a phosphoryl group between the EnvZ and OmpR proteins, which are involved in expression of the ompF and ompC genes in response to the medium osmolarity, was demonstrated in vitro. In this study, the histidine (His) residue at position 243 of the EnvZ protein, and the aspartate (Asp) residues at positions 12 and 55 of the OmpR protein were changed, respectively, by means of site-directed mutagenesis. We characterized the mutant proteins in terms of not only their in vitro phosphotransfer reactions but also their in vivo osmoregulatory phenotypes. The mutant EnvZ protein was defective in its in vitro ability not only as to EnvZ-autophosphorylation but also OmpR-phosphorylation and OmpR-dephosphorylation. This particular mutant EnvZ protein seemed to exhibit null functions as to the in vivo osmoregulatory phenotype. The mutant OmpR protein with the amino acid change at position 12 was clearly phosphorylated in vitro, but at a very low rate as compared with the wild-type OmpR protein. In vitro phosphorylation of the mutant OmpR protein with the amino acid change at position 55 was more severely affected. This mutant OmpR protein appeared to exhibit null functions as to the in vivo osmoregulatory phenotype. These results suggest that the histidine residue at position 243 of the EnvZ protein and the aspartate residues at positions 12 and 55 of the OmpR protein are deeply involved in the phosphotransfer between the EnvZ and OmpR proteins.

Osmoregulatory expression of the porin genes in Escherichia coli: evidence for signal titration in the signal transduction through EnvZ-OmpR phosphotransfer.

The OmpR protein of Escherichia coli is a positive regulator specific for the ompF and ompC genes. The function of OmpR is modulated through phosphotransfer signaling mediated by the kinase, EnvZ. We previously demonstrated that OmpR contains two functional domains, which are physically separable; one is responsible for the interaction with EnvZ, whereas the other participates in interactions with cognate promoter DNAs. In this study, these domains of OmpR were overproduced in wild-type cells harboring the endogenous intact ompR gene on their chromosome. It was found that when the N-terminal domain of OmpR, which contains the phosphorylation site, was overproduced, expression of the ompF and ompC genes was markedly inhibited, irrespective of the osmolarity of the growth medium. Based on our current model for the molecular mechanism underlying signal transduction through Envz-OmpR phosphotransfer (T. Mizuno and S. Mizushima, Mol. Microbiol. 4, (1990), 1077-1082), we provide evidence that this phenomenon is best interpreted by the concept of 'signal titration' in the phosphotransfer signaling pathway.

Chronic hydrocephalus presenting with bilateral ptosis after minor head injury: case report.

OBJECTIVE AND IMPORTANCE: Some patients with hydrocephalus may exhibit various signs of oculomotor dysfunction. However, ptosis has not previously been described in chronic hydrocephalus patients. CLINICAL PRESENTATION: We report a 50-year-old woman who was diagnosed with chronic hydrocephalus based on an evaluation for bilateral ptosis after a minor head injury. She exhibited bilateral ptosis and upward gaze paralysis, but other oculomotor functions were normal. Neuroimages revealed chronic hydrocephalus with no traumatic abnormalities. INTERVENTION: The eyelid dysfunction resolved after placement of a right ventriculoperitoneal shunt with a programmable pressure valve. CONCLUSION: The resolution of eyelid dysfunction by cerebrospinal fluid diversion suggests that chronic hydrocephalus was involved in the development of ptosis after the minor head injury. A mild but sudden cerebrospinal fluid pressure change at the time of minor head injury might induce functional impairment at the level of vulnerable periaqueductal structures, which barely withstood the longstanding ventriculomegaly, resulting in the clinical features observed in our patient.

Arterial wall changes in cerebral vasospasm.

A right-sided subarachnoid hemorrhage (SAH) was created in 12 monkeys. Only the right (clot-side) cerebral arteries developed angiographic vasospasm (VSP), which was maximal 7 days after SAH. Eight animals were killed at this time and the remainder at 14 days. At the time of killing the middle cerebral arteries (MCAs) were harvested, and four normal, left (non-clot-side) MCAs were vasoconstricted in vitro with prostaglandin F2 alpha. All MCAs were studied with scanning and transmission electron microscopy. Right MCAs in maximal VSP 7 days from SAH were undistinguishable on scanning electron microscopy from normal arteries vasoconstricted in vitro: both groups demonstrated a mean 57% reduction in vessel caliber and a 5-fold increase in vessel wall thickness compared to normal, nonvasoconstricted left MCAs. On transmission electron microscopy, however, arteries in SAH-induced VSP showed degenerative changes in the tunica intima and media. These changes were still evident at 14 days, despite considerable resolution of VSP. These findings, as well as those from other pathological studies of animal and human cerebral arteries in VSP, suggest that the arterial narrowing and vessel wall thickening seen within several weeks of SAH is due primarily to medial contraction, but unlike simple vasoconstriction, is associated with degenerative ultrastructural changes in the endothelium and vascular smooth muscle cells which may denote a temporarily irreversible state.

Anterior cervical vertebrectomy and interbody fusion for multi-level spondylosis and ossification of the posterior longitudinal ligament.

Multi-level cervical spondylosis and ossification of the posterior longitudinal ligament (OPLL) are well-documented causes of myelopathy. The choice of surgical procedures remain controversial. Between January 1983 and December 1987, we have performed anterior cervical vertebrectomy in 45 patients with cervical myelopathy caused by multi-level spondylosis and OPLL. They consisted of 19 patients with cervical spondylosis, 12 with OPLL, and 14 with combined lesions of both cervical spondylosis and OPLL. There were 32 men and 13 women. The mean age was 55 years, ranging from 35 to 70 years. In all of our 45 patients, anterior vertebrectomy, discectomy, removal of posterior osteophytes and OPLL, and interbody fusion were done for progressive myelopathy refractory to conservative treatment. In 2 of 45 patients, 5 vertebral bodies were resected; in 3 patients, 4 vertebral bodies were resected; in 12 patients, 3 vertebral bodies were resected, in 19 patients, 2 vertebral bodies were resected; and in 9 patients, 1 vertebral body was resected. Thirty-nine of 45 patients (87%) had good results. Neurological signs did not improve in 5 patients (11%). One patient died because of agranulocytosis secondary to treatment with antibiotics. In conclusion, cervical cord compression caused by lesions located principally in the anterior aspect of the spinal canal may be completely relieved via anterior vertebrectomy, discectomy, removal of the calcified ligament, and fusion.

The effect of timing of intrathecal fibrinolytic therapy on cerebral vasospasm in a primate model of subarachnoid hemorrhage.

The effect of intrathecal tissue plasminogen activator administered at times from 0 to 72 hours after subarachnoid hemorrhage on the development of cerebral vasospasm in primates was examined. Thirty monkeys were randomly assigned into one of five equal groups: a control group that underwent subarachnoid hemorrhage alone, and 0-, 24-, 48-, and 72-hour treatment groups that received 0.75 mg of tissue plasminogen activator at those times after baseline cerebral angiography and subarachnoid hemorrhage on the right side. Seven days later angiography was repeated and the animals were killed. One animal in the 72-hour group developed a delayed ischemic deficit on Day 7 after subarachnoid hemorrhage. In the control and 72-hour groups significant vasospasm occurred in most of the major, right cerebral arteries (P less than 0.05), but no significant vasospasm developed in the 0-, 24-, and 48-hour groups. Although a large subarachnoid clot remained in the control animals, most clot had been dissolved in all treatment groups. Lysing of subarachnoid hematoma with intrathecal tissue plasminogen activator within 72 hours of subarachnoid hemorrhage is effective in preventing vasospasm in primates.

A dosage study of the effect of the 21-aminosteroid U74006F on chronic cerebral vasospasm in a primate model.

The efficacy of the 21-aminosteroid U74006F was investigated using different dosages in a restricted, randomized, placebo-controlled trial. Forty cynomolgous monkeys were divided into five groups of eight. There were two groups given treatment with placebos, one being saline and the other the vehicle in which U74006F was delivered. There were three U74006F treatment dosage groups: 0.3, 1.0, and 3.0 mg/kg. Each monkey underwent baseline cerebral angiography followed by right-sided craniectomy and subarachnoid placement of a clot around the middle cerebral artery (MCA). Treatment was administered intravenously every 8 hours for 6 days. Seven days after experimental subarachnoid hemorrhage, angiography was repeated, and the animals were killed. In both saline or vehicle placebo treatment groups, significant vasospasm (VSP) occurred on the clot side in the extradural internal carotid artery (C3), the intradural internal carotid artery, the precommunicating segment of the anterior cerebral artery (A1,) and the MCA (P less than 0.01). After U74006F treatment, significantly less VSP developed in the A1 on the clot side (0.3 mg/kg U74006F treatment group) and the MCA (all U74006F treatment groups, P less than 0.05). When the percentages of change from the baseline for the vessel diameters on the clot side were compared, VSP was attenuated in the A1 (P less than 0.05) and MCA (P less than 0.001) of all U74006F treatment groups as compared with the placebo treatment groups. Only 0.3 mg/kg of U74006F significantly prevented VSP in C3 (P less than 0.01). Although the 0.3 mg/kg dosage appeared to have the most favorable effect, no significant differences were observed among the three dosage groups. Electron microscopy of the MCA on the clot side in the animals treated with U74006F still showed luminal convolutions and morphological changes in the endothelial cells. These changes appeared less prominent in those MCAs with milder VSP. If these results in primates are applicable to humans, U74006F would be useful in reducing VSP after aneurysmal subarachnoid hemorrhage.

The effect of atherosclerosis on endothelium-dependent relaxation in the aorta and intracranial arteries of rabbits.

The effect of hypercholesterolemia on vascular responsiveness was studied in isolated rabbit arteries. The arteries of animals maintained on a cholesterol-rich (1%) diet for 6 months had more pronounced intimal lesion than those receiving the diet for 3 months. The aortas were more severely damaged than the carotid or basilar arteries. Segments of the arteries were mounted in organ chambers for isometric tension recording or for measurement of the endothelium-derived relaxing factor. Endothelium-independent relaxation induced by glyceryl trinitrate was not affected even in the most severely damaged arteries; endothelium-dependent relaxation in response to acetylcholine (ACh) and A23187 was progressively inhibited as the degree of fatty streak formation increased. In the carotid arteries, mean (+/- standard deviation) relaxation induced by 10(-5) M of ACh (expressed as a percentage of the maximum relaxation induced by 10(-4) M of papaverine) decreased from 87.33% +/- 6.30% in control tissues to 60.90% +/- 4.64% in vessels from animals subjected to 6 months of hypercholesterolemia (p less than 0.01); in the aortas, mean relaxation due to 10(-5) M of ACh was 85.08% +/- 8.03% in control tissues and 41.35% +/- 13.68% in hypercholesterolemic tissues (p less than 0.01). In the carotid arteries, mean relaxation induced by 10(-7) M of A23187 decreased from 95.81% +/- 3.58% in control tissues to 55.95% +/- 2.81% in hypercholesterolemic tissues (p less than 0.01); in the aortas, relaxation in response to 10(-7) M of A23187 was 73.73% +/- 4.35% in control tissues and 29.35% +/- 6.77% in hypercholesterolemic tissues (p less than 0.01). Intimal lesions were not produced in the basilar arteries even in rabbits with 12 months of hypercholesterolemia, and endothelium-dependent relaxation was preserved.

Effect of 21-aminosteroid U-74006F on lipid peroxidation in subarachnoid clot.

The present study was undertaken to investigate the effect of U-74006F on malondialdehyde (a by-product of lipid peroxidation) in subarachnoid clot. Eighteen cynomolgus monkeys were divided into three groups of six each. There were two U-74006F-treated groups, receiving doses of 0.3 or 1.0 mg/kg, and a placebo-treated group. Each monkey underwent baseline cerebral angiography followed by right-sided craniectomy and placement of subarachnoid clot around the middle cerebral artery (MCA). Treatment was administered intravenously every 8 hours for 6 days. Seven days after the experimental subarachnoid hemorrhage (SAH), angiography was repeated and the animals were killed. In the placebo-treated group, significant vasospasm occurred in the MCA on the side of the clot (p less than 0.01). After U-74006F treatment at both dosages, significantly less vasospasm developed in the clot-side MCA (p less than 0.01). The content of malondialdehyde was measured by both the thiobarbituric acid test and high-performance liquid chromatography (HPLC). Comparing the two methods, HPLC proved to be more accurate than the thiobarbituric acid test, especially for measurement of low concentrations of malondialdehyde. In the placebo-treated group, the malondialdehyde content was significantly increased in the Day 7 clot (p less than 0.05). In contrast, malondialdehyde content in freshly prepared clot was very low. In the 0.3-mg/kg U-74006F group, the malondialdehyde content of clot was significantly less at Day 7 compared to clot from the placebo-treated group (p less than 0.05). Although the malondialdehyde content of clot from the 1.0 mg/kg U-74006F-treated group was less than that of placebo, it was not significantly so. Malondialdehyde was not detected in the actual vessel wall of the MCA of any group. These results suggest that lipid peroxidation in subarachnoid clot may play a role in the pathogenesis of vasospasm and that the salutary effects of U-74006F in vasospasm may be mediated by a reduction of lipid peroxidation in SAH.

Pharmacological studies on relaxation of spastic primate cerebral arteries in subarachnoid hemorrhage.

Chronic cerebral vasospasm was induced in 16 monkeys by direct placement of a clot of autologous blood over the arteries of the circle of Willis on the right side. The middle cerebral arteries (MCA's) on the clot side all showed angiographic vasospasm, which was maximal 7 days after subarachnoid hemorrhage. Animals were sacrificed at this time and vascular responses to acetylcholine (ACh), histamine, and the calcium ionophore A23187 were studied in MCA rings from the clot (spastic) side and the non-clot (control) side. In control preparations with an intact endothelium, which had been precontracted by prostaglandin F2 alpha (PGF2 alpha), histamine and A23187 produced significant relaxation. The same concentrations of histamine and A23187 did not relax vascular tissues in which the endothelium had been mechanically removed. Acetylcholine did not produce a significant endothelium-dependent relaxation of primate MCA rings, but did relax rings of primate common carotid artery. Pretreatment with chlorpheniramine (an H1-receptor antagonist) prevented histamine-induced relaxation; however, cimetidine (an H2-receptor antagonist) had no inhibitory action. It thus seems that histamine mediates relaxation of intact MCA's mostly by an H1-receptor-mediated release of endothelium-derived relaxing factor (EDRF). Relaxations induced by histamine and A23187 in MCA's from the clot side were substantially reduced. Moreover, the small component of ACh-induced relaxation was also abolished. Endothelium-independent relaxation induced by glyceryl trinitrate (GTN) occurred in arteries from both the control and the clot sides. Constrictions induced by KC1 and PGF2 alpha were reduced on the clot side of the MCA's. These results suggest that subarachnoid hemorrhage influences both the generation of EDRF and the constriction of affected arteries. The small contraction which was elicited in spastic arteries was fully relaxed by GTN.

Etiology of cerebral vasospasm in primates.

A primate model was used to determine whether oxyhemoglobin (OxyHb), methemoglobin (MetHb), or bilirubin is likely to be responsible for cerebral vasospasm following subarachnoid hemorrhage (SAH). Forty cynomolgus monkeys were randomly assigned to one of five groups. On Day 0, each animal underwent angiography followed by right craniectomy and placement of an Ommaya reservoir with its catheter adjacent to the right middle cerebral artery (MCA). The animals received intrathecal injections twice a day for 6 days of one of the following solutions: mock cerebrospinal fluid (CSF); OxyHb; MetHb; bilirubin; or supernatant fluid from an incubated mixture of autologous blood and mock CSF. On Day 7, angiography was repeated and the animals were killed. Comparison of angiograms obtained on Day 0 and Day 7 of the experiment showed significant vasospasm of the right MCA and the right anterior cerebral and internal carotid arteries in the animal groups that had received OxyHb or supernatant fluid. There was a smaller reduction in diameter of the same vessels in the bilirubin group (not statistically significant), while no effects were observed in the groups receiving MetHb or mock CSF. Electron microscopy of the right MCA's gave results consistent with the angiographic findings. One monkey in the OxyHb group developed a delayed-onset right MCA infarction. These data suggest that OxyHb is the cause of cerebral vasospasm following SAH.

Effects of unilateral intrathecal administrations of low dose tissue-type plasminogen activator on clot lysis, vasospasm and brain phospholipid hydroperoxidation in a primate model of bilateral subarachnoid hemorrhage.

In order to clarify the effect of clot lysis by recombinant tissue-type plasminogen activator (tPA) on the brain lipid peroxidation, we measured phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) levels in a primate model of subarachnoid hemorrhage (SAH). Monkeys were assigned into two groups; a tPA-treated group receiving intrathecal injections of 0.02 mg tPA, and a placebo-treated group receiving saline. The tPA or placebo was injected into the right side of the basal cistern every 8 h for 6 days following bilateral SAH induction. The tPA cleared the right side clots (p < 0.0001), but not the left side clots. The degree of vasospasm in the right middle cerebral artery and the rCBF decrease in the right parietal cortex were significantly attenuated in the tPA group (p < 0.05). In the placebo group, more severe vasospasm and marked rCBF reduction were noted in comparison with those in the tPA group. PCOOH levels in the parietal cortex were significantly higher in the placebo group than in the tPA group (p < 0.05). There were no significant changes in brain PEOOH levels. These results may explain the limitations for clinical application of unilateral intrathecal administration of tPA.

Intrathecal fibrinolytic therapy after subarachnoid hemorrhage: dosage study in a primate model and review of the literature.

Because of the naturally low fibrinolytic activity of CSF many erythrocytes entrapped in subarachnoid blood clot undergo hemolysis in situ, releasing vasogenic oxyhemoglobin (OxyHb) in high concentrations around the basal cerebral arteries. In order to promote more rapid clearance of erythrocytes from the basal subarachnoid cisterns we are currently investigating intrathecal thrombolytic therapy with human, recombinant, tissue plasminogen activator (rt-PA) in a primate model of subarachnoid hemorrhage (SAH) and cerebral vasospasm (VSP). In the present study 16 monkeys were divided into 4 groups of 4, and each group received a different dose of sustained-release gel rt-PA at the time of experimental SAH. Cerebral angiography seven days later showed that whereas no VSP occurred in the groups receiving 0.5 or 0.75 mg of rt-PA, mild to moderate VSP occurred in the groups receiving 0.125 or 0.25 mg of rt-PA. Analysis of the combined 2 smaller dosage groups revealed significant (P less than 0.05) reduction of lumen caliber in the clot-side internal carotid (C3 and C4), proximal anterior cerebral (A1) and middle cerebral (MCA) arteries. Gross subarachnoid clot remained in all of the animals in the 0.125 and 0.25 mg dose groups, in 2 of the animals in the 0.5 mg dose group, and none of the animals in the 0.75 mg dose group. It was concluded that 0.75 mg of gel rt-PA is sufficient to completely lyse a 4.25 ml SAH and prevent VSP in our primate model. The literature on fibrinolysis and erythrocyte clearance in cerebrospinal fluid (CSF) is reviewed.