A genetically engineered P450 monooxygenase: construction of the functional fused enzyme between rat cytochrome P450c and NADPH-cytochrome P450 reductase

A hybrid cDNA encoding a fused enzyme consisting of rat cytochrome P450c and rat NADPH-cytochrome P450 reductase was constructed by combining the cytochrome P450c cDNA with the cDNA fragment encoding the protease-solubilized moiety of the NADPH-cytochrome P450 reductase. The hybrid cDNA was inserted between the yeast alcohol dehydrogenase I promoter and terminator of the expression vector pAAH5 to yield expression plasmid pAMP19. Saccharomyces cerevisiae AH22 cells transformed with the expression plasmid pAMP19 produced a 130-kD protein reactive with both anti-cytochrome P450c Ig and antireductase Ig. The yeast cells containing the fused enzyme exhibited about four times higher monooxygenase activity toward 7-ethoxycoumarin than those containing rat cytochrome P450c alone. The fused enzyme was purified from the yeast microsomal fraction by sequential chromatography with DEAE-cellulose and 2',5'-ADP Sepharose 4B columns. The preparation had an apparent molecular weight of 130 kD and the same sequence of the 10 amino-terminal amino acids as that of rat cytochrome P450c. Spectral properties of the fused enzyme indicated the presence of a protoheme, flavin adenine dinucleotide, and flavin mononucleotide in the molecule. The reaction mechanism of the fused enzyme followed first-order kinetics. These results clearly indicate that the fused enzyme is a new self-catalytic P450 monooxygenase. Trypsin treatment of yeast microsomes containing the fused enzyme suggested that the P450 moiety is embedded in the microsomal membrane with the reductase moiety lying on the cytoplasmic side.

Reconstruction of cerebral cortical veins using silicone tubing. Technical note

A technique for reconstruction of a cerebral cortical vein which has been sacrificed during an interhemispheric or subtemporal surgical approach is described. The method involves the use of silicone tubing. The author's clinical experience in six patients is summarized.

Expression in Saccharomyces cerevisiae of chimeric cytochrome P450 cDNAs constructed from cDNAs for rat cytochrome P450c and P450d

Three chimeric cytochrome P450 cDNAs were constructed by replacing the central region, carboxy-terminal region, or both central and carboxy-terminal regions of cytochrome P450c cDNA with the corresponding regions of cytochrome P450d cDNA. These were inserted between the alcohol dehydrogenase I promoter and terminator of yeast expression vector pAAH5 to form expression plasmids pACDC2, pACCD1, and pACDD2. On introduction of each of these plasmids into Saccharomyces cerevisiae AH22 cells, chimeric cytochrome P450 proteins were expressed in AH22/pACDC2, AH22/pACCD1, and AH22/pACDD2 cells at the level of at least 10(5), 4 X 10(5) molecules per cell, respectively. The reduced CO-difference spectra showed that AH22/pACCD1 and AH22/pACDD2 cells contained 4 X 10(5) and 10(5) molecules per cell of the corresponding chimeric cytochrome P450 hemoproteins, designated as cytochrome P450ccd and cytochrome P450cdd, respectively. Cytochrome P450ccd exhibited higher monooxygenase activities toward 7-ethoxycoumarin, acetanilide, and benzo[alpha]pyrene than cytochrome P450c, although the substrate specificity of cytochrome P450ccd seemed to be the same as that of cytochrome P450c. Cytochrome P450cdd exhibited lower activities toward 7-ethoxycoumarin and benzo[alpha]pyrene, and a higher activity toward acetanilide as compared with those of cytochrome P450c and cytochrome P450ccd. Therefore, the substrate specificity of cytochrome P450cdd seemed to be the same as that of cytochrome P450d. These results suggest that the central one-third region of cytochrome P450c and cytochrome P450d is responsible for substrate-binding, and that the carboxy-terminal third of both cytochromes P450 plays an important role in electron transport.

Microsurgical treatment of patients with vestibular and cochlear symptoms

Eighteen patients with vertigo, tinnitus, and various hearing disturbances were treated by posterior fossa exploration and microvascular decompression of the eighth cranial nerve; they were followed for more than 3 years. After successful decompression of the eighth nerve from offending vessels, the attacks of vertigo disappeared in 11 patients, improved markedly in 3 patients, and improved mildly in 4 patients. The tinnitus vanished in three patients and decreased in nine. The hearing disturbance improved in only five patients and worsened in three. Because of the satisfactory improvement of the attacks of vertigo, which are the most distressing symptoms for patients, we recommend surgical exploration for patients with severe symptoms of vestibular disturbances.

[Chemoembolization therapy with cisplatin.lipiodol (CDDP.lipiodol) in primary liver cancer--with special reference to hepatocellular carcinoma]

From Jan., 1985 to Mar., 1986 thirty-six patients with primary liver cancer received transcatheter arterial chemoembolization therapy with Cisplatin (100 mg) blended into Lipiodol (5 ml) and simple embolization therapy with Gelfoam particles. Thirty-three cases out of 36 had hepatocellular carcinoma, one had hepatoblastoma and one had adenocarcinoma. Ten (31%) out of 32 had hepatocellular carcinoma, and showed objective tumor reduction greater than 50% (partial response) regarding the main tumor. Of the 33 there was one sudden death due to intracerebral hemorrhage. Only two out of 25 cases with daughter nodules showed slight reduction. Almost all cases with daughter nodules showed no response to chemoembolization therapy. Five patients died after chemoembolization therapy during the fifteen-month study period. Two patients died of liver abscess or cholecystitis and surrounding abscess, one died of intracerebral hemorrhage, one died of hepatic failure and the remaining case was one of tumor death.

[Carotid-ophthalmic aneurysms and visual abnormalities]

The direct neck clipping for carotid-ophthalmic aneurysm is hazardous and difficult as compared with other intracranial aneurysms because of its location adjacent to the anterior clinoid process, the optic nerve, and the cavernous sinus. The authors discuss the visual abnormalities accompanied by carotid-ophthalmic aneurysm on the basis of our experiences with 30 patients with 33 aneurysms. Ten patients (4 of 14 with ruptured aneurysms, 6 of 16 intact aneurysms) had preoperative visual abnormalities. Of our series of patients, visual acuity and visual field were impaired in one eye. The most common field abnormalities were unilateral inner or upper side defects. In the patients whose aneurysms were intact, visual abnormalities had been slowly progressive over many months. Otherwise, 2 cases with ruptured aneurysm experienced their first visual symptoms at the same time their hemorrhage. According to the projection of aneurysm with respect to internal carotid artery, superomedial and posteromedial projections were common in the patients with visual abnormalities. Seven patients with visual dysfunctions were operated on. Improvement of the visual symptoms was observed in 3 cases. In these cases, complete collapse of the aneurysm with good decompression of the optic nerve was obtained at operation. Two patients deteriorated following surgery; this occurred in relation to attempts to clip the aneurysm neck directly, and optic nerve was probably excessively manipulated. Two patients had no change in visual symptom: one was treated with trapping of internal carotid artery combined with STA-MCA anastomosis, another had direct hemorrhage into the ipsilateral optic nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Monooxygenase activity of Saccharomyces cerevisiae cells transformed with expression plasmids carrying rat cytochrome P-450MC cDNA

The recombinant plasmids pAMC1 and pJMC1 were constructed; the former contained the cytochrome P-450MC (P-450MC) cDNA expression unit consisting of yeast alcohol dehydrogenase I (ADH) promoter, rat P-450MC cDNA and ADH terminator, and the Leu 2 marker gene, and the latter contained the same expression unit and the leu 2-d gene. Saccharomyces cerevisiae AH22 cells transformed with each of the recombinant plasmids were examined for plasmid copy number, P-450MC mRNA level, P-450MC content, and monooxygenase activity. The S. cerevisiae AH22/pJMC1 cells contained about 2-fold higher levels of the plasmid, P-450MC mRNA, and P-450MC than the AH22/pAMC1 cells. Monooxygenase activity towards 7-ethoxycoumarin and acetanilide of the AH22/pJMC1 cells was 1.7-fold and 1.5-fold higher than that of the AH22/pAMC1 cells, respectively, whereas the activity of the AH22/pAMC1 cells towards 7-ethoxycoumarin and acetanilide was more than 1,000-fold 10-fold higher than that of the control AH22/pAAH5 cells which contain no P-450MC cDNA, respectively. Therefore, it is likely that monooxygenase activity of the AH22 cells carrying rat P-450MC cDNA was approximately proportional to the expression level of P-450MC cDNA.

Light-Induced Alkalinization of the Suspending Medium of Guard Cell Protoplasts from Vicia faba L

The light-dependent pH changes in the suspending medium of guard cell protoplasts (GCP) from Vicia faba were studied. Upon illumination, the medium was initially slightly alkalinized and then acidified. The extent of alkalinization was lower in CO(2)-free air than in normal air. This initial alkalinization was inhibited by DCMU. Acidification in CO(2)-free air became observable in shorter duration of light exposure than that in normal air. The rate of acidification was higher in CO(2)-free air than in normal air. The CO(2) level of the medium decreased in the light, and increased in the dark. (14)CO(2) uptake was enhanced 2- to 3-fold by light, but not in the presence of DCMU. These results indicate that photosynthetic CO(2) fixation does take place in GCP and that the initial alkalinization is due to this photosynthetic CO(2) uptake. Diethylstilbestrol, a nonmitochondrial membrane-bound ATPase inhibitor, inhibited the acidification, suggesting that the acidification resulted from H(+) extrusion by GCP. The acidification in light was also prevented by KCN, and partly by DCMU. Possible mechanisms of alkalinization and acidification are discussed in relation to guard cell metabolism.

Characterization of rat cytochrome P-450MC synthesized in Saccharomyces cerevisiae

Rat cytochrome P-450MC cDNA was expressed in Saccharomyces cerevisiae AH22, SHY3 and NA87-11A cells under the control of the yeast ADH1 promoter and terminator. Although the three yeast strains transformed with the constructed expression plasmid, pAMC1, contained approximately three copies of the plasmid, the levels of both P-450MC mRNA and the corresponding protein in the AH22 cells carrying plasmid pAMC1 were 1.4- to 1.7-fold and 2-fold higher than in the other two strains, respectively. The P-450MC protein was purified from the microsomal fraction of AH22 cells carrying pAMC1 by a rapid purification method. The apparent molecular weight, chromatographic behavior, spectral properties, substrate specificity and immunochemical properties of the purified P-450MC protein were indistinguishable from those of rat liver P-450MC-I and P-450MC-II (Sasaki, T., et al. (1984) J. Biochem. 96, 117-126). The NH2-terminal amino acid sequence of the purified protein up to 10 residues was the same as those of P-450MC-I and P-450MC-II. In addition, HPLC analysis of the microsomal fraction of AH22 cells containing pAMC1 indicated that the synthesized P-450MC protein corresponds to P-450MC-II, but not P-450MC-I. With another purification method, we obtained the cleaved P-450MC protein which lacked the NH2-terminal 30 amino acids of intact P-450MC. The spectral properties and monooxygenase activities towards benzo(a)pyrene and 7-ethoxycoumarin of the cleaved P-450MC were nearly the same as those of intact P-450MC.

Expression of rat liver cytochrome P-450MC cDNA in Saccharomyces cerevisiae

Rat liver cytochrome P-450MC cDNA was inserted between the ADH1 promoter and terminator regions of the yeast expression vector pAAH5. On introduction of the resulting recombinant plasmid pAMC1, Saccharomyces cerevisiae cells synthesized up to 8 X 10(5) molecules per cell of the cytochrome P-450MC protein, most of which was localized in yeast microsomes. Approximately half of the synthesized cytochrome contained heme in the enzyme molecule. These formed a functional electron-transport chain in the microsomes which exhibited aryl hydrocarbon hydroxylase activity toward benzo[a]pyrene.

[Clinical studies on cefoxitin in the prevention of postoperative infections and the treatment of postoperative pulmonary and urinary tract infections]

This clinical trial was designed to evaluate the efficacy, safety and patient tolerance of cefoxitin (CFS) in 46 patients who were admitted to the hospitals from June 1983 to April 1984. The daily doses of CFX for 34 patients (ages ranged from 6 to 75 years old) were 2 to 8 g to prevent the infections and for 12 patients (ages ranged from 55 to 81 years old) were 2 to 6 g to treat the infections by intravenous drip infusion 1 or 3 times a day in divided doses. The following results were obtained. All of 34 patients with intracranial operation who received CFX for prevention of postoperative infections showed good results. Of 12 patients with postoperative pneumonia, infections of urinary tract and late meningitis, 11 patients showed good results. One patient was discontinued on the 3 days because of the drug eruption which improved 3 days after. The side effect was noted in only 1 patient. This was eruption which improved 3 days after the stop of the administration. The influences to the laboratory data due to CFX were not recognized. The results of this study demonstrated that CFX was an excellent drug for the prevention and treatment of the postoperative infections in the neurosurgical field because of high efficacy rate and safety.

[Histopathological findings of the pituitary gland in cases of subarachnoid hemorrhage]

Histopathological change of the pituitary gland in cases of the central nervous system disorder, especially in the cases of subarachnoid hemorrhage, was studied. Clinical materials were 23 cases who were died from subarachnoid hemorrhage due to aneurysmal rupture in the acute stage. Histopathological change was examined not only of the pituitary gland but also hypothalamus and the change due to increased intracranial pressure (midbrain hemorrhage and uncal herniation). Main histopathological findings of the pituitary gland are anterior pituitary necrosis and they are found in 8 cases out of 23 subarachnoid hemorrhage cases (34.9%). Histopathological changes in hypothalamus were hemorrhage or infarction, and these changes were present in 16 cases (70%). Eight cases with pituitary necrosis had shown hypothalamic lesions. Three cases out of 23 cases (17.4%) showed midbrain hemorrhage and uncal herniation and 3 cases out of these 4 cases had anterior pituitary necrosis. According to the angiographic findings, vasospasm tended to be severe and widespread in cases of anterior pituitary necrosis, meanwhile vasospasm did not tend to be severe or widespread in cases without anterior pituitary necrosis. It was suspected that the mechanism of the development of pituitary necrosis is related not only to the circulatory disturbance of the portal vessels due to mechanical compression on the pituitary stalk and acutely raised intracranial pressure at the moment of aneurysmal rupture, but also circulatory disturbance of the portal vessels due to vasospasm.

Characterization of three forms of cytochrome P-450 isolated from liver microsomes of rats treated with 3-methylcholanthrene

Three forms of cytochrome P-450, designated as P-450MC-I, P-450MC-II, and P-450MC-III, were isolated from liver microsomes of rats treated with 3-methylcholanthrene (MC) by using a high performance liquid chromatography (HPLC) technique. The major MC-inducible forms, P-450MC-I and P-450MC-II showed a single protein band on SDS-polyacrylamide gel electrophoresis giving a minimum molecular weight of 56,000 daltons. The oxidized absolute spectra of both cytochromes P-450 were of low spin type, having a Soret absorption peak at 417 nm. The CO-reduced difference spectra of these two cytochromes P-450 showed a peak at 447 nm. In a reconstituted system, both cytochromes P-450 exhibited similar high levels of catalytic activity for benzo(a)pyrene hydroxylation and 7-ethoxycoumarin O-deethylation. Anti-P-450MC-I IG and anti-P-450MC-II IG, which were produced against the corresponding cytochromes P-450, each formed a single continuous precipitin line with both P-450MC-I and P-450MC-II in Ouchterlony double diffusion tests. Amino acid sequence analysis revealed that the sequence of the NH2-terminal 18 amino acids of both enzymes was the same. Therefore, the major MC-inducible forms, P-450MC-I and P-450MC-II, were highly homologous, being indistinguishable from each other in terms of apparent molecular weight, spectral properties, substrate specificity and the NH2-terminal 18 amino acid residues, but clearly separable by HPLC. The characteristics of both P-450 forms appear to correspond to those of the previously reported P-450c (1). On the other hand, a minor form, P-450MC-III was different from P-450MC-I and P-450MC-II in chromatographic properties, apparent molecular weight, substrate specificity and immunochemical properties, and did not correspond to any P-450 species previously purified from MC-treated rat liver microsomes.

[Cerebral schistosomiasis with a huge calcification. A case report]

A case of cerebral schistosomiasis with a huge calcification and with a long clinical course was reported. A 39-year-old male developed ataxic gait gradually associated with headache and general fatigability. According to the past history, the patient had suffered from severe meningitis with disturbance of consciousness for 2 weeks when he was 10 years of age. Neurological examination revealed positive Romberg's sign and left homonymous hemianopsia. Plain craniogram showed a large calcification occupying the whole right occipital region. This calcification was lobulated in shape and was 11 X 9 X 9 cm in size. CT scan demonstrated calcification and remarkable hydrocephalus. This calcification had no mass effect. Left vertebral angiogram revealed the right parieto-occipital artery to be stretched and slightly displaced toward midline. Hematological analysis disclosed no abnormality except for eosinophilia (10%). Pre-operative diagnosis was an old calcified granuloma of unknown origin. For the purpose of biopsy, a right occipital craniotomy was performed. On reflecting the dura, fibrous adhesion and vascular network were seen between the inner table of the dura and the arachnoid. Subarachnoid space was enlarged and all cortical vessels were narrow in their diameters. By a corticotomy, a whitish-yellow calcified mass was seen in the depth of 2 mm. The yellowish gelatinous content poured out of the mass. A piece of calcification and a small amount of content were taken as specimen. Microscopic study of the calcified tissue showed many egg shells of schistosoma japonica, necrotic tissues and infiltration of small round cells.

[Clinical study on six cases of subcortical cavernous angiomas]

Cavernous angioma is a rare but important clinical entity because of its potential curability. We experienced with 6 cases of cavernous angiomas located in the subcortical region and summarized with special respect on clinical symptoms, CT scan, angiographic manifestations and operative findings. In all of these 6 cases, the diagnosis is confirmed as cavernous angioma histologically. The age in these cases ranged from 16 to 45 years and sex distribution was 3 males and 3 females. Initial symptoms of 6 cases were long-standing epilepsy in 4 cases and attack of unconsciousness in 2 cases. Plain craniogram revealed calcification in only one patient. On the other hand, plain CT scan showed high density areas in all cases. Among these, 3 patients showed slight contrast enhancement. Perifocal low density areas were noted in all cases and these low density areas extended to the cortical region. The most important lesion to differentiate from cavernous angioma is low-grade astrocytoma with calcification on CT scan. We misdiagnosed in one patient with cavernous angioma as contusional hemorrhage, because the patient fell unconscious and hit the occiput. Angiographically, most cavernous angiomas are represented as avascular masses with displacement of adjacent vessels. In contrast to this general acceptance, 4 out of the present 6 cases showed abnormal findings such as feeding artery, capillary blush and draining vein. The draining veins were encountered in 4 cases. It must be emphasized that these angiographic manifestations are very small and caution has to be paid not to be overlooked. From the operative view, there are several characteristic findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Spin-label studies of the oligomeric structure of band 3 protein in erythrocyte membranes and in reconstituted systems

A spin-labeled fatty acid (16-doxylstearic acid), linked by an ester bond to a maleimide or a nitrene residue, was covalently attached to band 3 of erythrocyte membranes. The electron spin resonance spectrum of the spin-labeled protein was examined at different temperatures in: (a) whole erythrocyte ghosts; (b) ghosts depleted of spectrin and actin; (c) alkaline-treated ghosts; (d) vesicles made with purified band 3 reassociated with dimyristoylphosphatidylcholine. Most spectra are composite with a major component corresponding to a large overall splitting. The determination of the percentage of the immobilized component was carried out by pairwise subtraction. At low temperatures (1-7 degrees C), the highest fraction of immobilized component was found in dimyristoylphosphatidylcholine vesicles (approx. 100%); alkaline-treated membranes had approx. 75% of the immobilized component at the same temperature; whole erythrocyte, spectrin/actin-depleted and spectrin/actin/ankyrin-depleted ghosts gave identical results (approx. 60% of immobilized component). The immobilized fraction decreased in all samples with increasing temperature or addition of a nonsolubilizing concentration of dodecyl octaethylene glycol monoether. In dimyristoylphosphatidylcholine vesicles, however, the modification in the ration of the two components was obtained only above the lipid transition temperature (23 degrees C). The strong immobilization of the spin-labeled lipid chain at all temperatures suggested trapping of the lipid chain between proteins. At low temperature, in dimyristoylphosphatidylcholine vesicles or in alkaline-treated ghosts, lipid-protein segregation is likely to take place. In whole erythrocyte ghosts, on the other hand, the large contribution of the motionally restricted component at physiological temperature indicates the oligomeric nature of band 3. Partial dissociation of the oligomers occurs as the temperature is increased, but the presence or absence of cytoskeletal proteins has no influence on the state of oligomerization of band 3.