A T7 RNA polymerase expression system has been used for the efficient expression of the yeast RNA polymerase general transcription factor TFIID (TFIIDY), the TATA-box factor (previously called BTF1) in Escherichia coli. Expression of the gene was performed at 25 degrees C instead of 37 degrees C to increase the total amount of soluble TFIIDY. Soluble TFIIDY was purified in three chromatographic steps and was eluted from the final column, a heparin-5PW HPLC column, in two peaks at 0.38 M (peak I) and 0.42 M (peak II) KCl in which this protein was 52% and greater than 95% pure, respectively. The protein in both peaks was active in an in vitro transcription assay. However, while TFIIDY from peak II was essentially indistinguishable from the material isolated from yeast, the protein of peak I differed in a number of biochemical characteristics, having a lower specific activity in an in vitro transcription assay and displaying an altered pattern of bands in a DNA band shift assay. Despite these differences, the proteins in both peaks have identical molecular weights on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, have indistinguishable N-terminal amino acid sequences, and apparently exist as monomers under the conditions used for the heparin-5PW chromatography.

Amino Acid Sequence↗

PubMedDate not supplied

A case of orbital solitary fibrous tumor.

BACKGROUND: Solitary fibrous tumor is a spindle cell neoplasm that most commonly arises in the pleura and very rarely involves the orbit. CASE: A 38-year-old woman presented with slowly progressive proptosis of 3 months duration and optic nerve head edema in her right eye. Magnetic resonance imaging revealed a well-circumscribed, round mass lesion, which showed isointensity to the gray matter in a T1-weighted image, and variegated intensity in a T2-weighted image and contact with the optic nerve in her right orbit. The tumor was successfully removed by anterior orbitotomy. OBSERVATIONS: The tumor showed a "patternless pattern" of tumor cell arrangement, alternating hypercellular and hypocellular areas, a hemangiopericytoma-like pattern, and thickened strands of collagen. Immunohistochemically, the tumor cells were positive for CD34 and vimentin, and all were negative for other markers of epithelial, neural, muscular, histiocytic, and vascular endothelial cell elements. The tumor was diagnosed as a solitary fibrous tumor, and the patient was doing well with no evidence of recurrence 15 months after surgery. CONCLUSIONS: This case was the 19th reported case of solitary fibrous tumor in the orbital region. CD34 is a highly sensitive marker for solitary fibrous tumor.

Adult↗

PubMedDate not supplied

Restriction enzyme analysis of mitochondrial DNA of Acanthamoeba strains isolated from corneal lesions.

Although Acanthamoeba keratitis has been recognized as one of the important infectious diseases of the cornea, especially in contact lens wearers in recent years, its taxonomy has not been well established. We carried out mitochondrial DNA (mtDNA) analysis of the Acanthamoeba organisms isolated from corneal lesions in four eyes of three patients who had suffered from keratitis. The mtDNA was analyzed by restriction fragment length polymorphism (RFLP) using restriction enzymes Bg/II and EcoRI. The RFLP analyses revealed that the DNA phenotypes of the Acanthamoeba organisms were identical to those of the Ma strain in two patients and to the Castellani strain in one patient.

Acanthamoeba↗

PubMedDate not supplied

Effects of verapamil and lidocaine on changes in action potential characteristics and conduction time induced by combined hypoxia, hyperkalemia, and acidosis in canine ventricular myocardium.

We examined the effects of verapamil and lidocaine on changes in action potential characteristics and conduction time in the isolated right ventricular myocardium of canine hearts during superfusion with altered Tyrode's solution imitating some of metabolic alterations that occur in acute myocardial ischemia (Po2 less than 50 mm Hg, KCl 8 mM, pH 6.80). Altered Tyrode's solution produced loss of resting membrane potential (RMP), action potential amplitude (APA), action potential duration, and upstroke velocity of action potential (Vmax), and prolonged conduction time (CT). In the presence of lidocaine (5 mg/L), altered Tyrode's solution aggravated the reductions of APA and Vmax and the prolongation of CT in both endocardial and epicardial muscle cells. On the other hand, in the presence of verapamil (1 mg/L), the degree of the reductions of APA and Vmax and of the prolongation of CT induced by altered Tyrode's solution was reduced in epicardial muscle cells, but not in endocardial ones. Neither verapamil nor lidocaine affected change in RMP. These results suggest that the improving effect of verapamil on ischemia-induced conduction delay can be partly explained by its salutary effect on the depressed fast channel.

Acidosis↗

PubMedDate not supplied

Relaxation in different-sized rat blood vessels mediated by endothelium-derived hyperpolarizing factor: importance of processes mediating precontractions.

To clarify the mechanisms involved in relaxations mediated by endothelium-derived hyperpolarizing factor (EDHF), acetylcholine (ACh)-induced endothelium-dependent relaxations and hyperpolarizations were examined in the rat aorta, the main branch of the mesenteric artery (MBMA) and the first branch of the mesenteric aftery (FBMA). In the presence of 100 microM N(G)-nitro-L-arginine (L-NNA) and 10 microM indomethacin, ACh (1 nM to 100 microM) produced no relaxation in the phenylephrine-precontracted aorta. The L-NNA-resistant relaxations by ACh in MBMA precontracted with phenylephrine were eliminated in the presence of 1 microM nifedipine where contractions were independent of L-type Ca(2+) channel activation. In FBMA precontracted with phenylephrine, the L-NNA-resistant relaxations were only partially inhibited by nifedipine. When vessels had been contracted with 300 nM phorbol-12,13-dibutyrate in the presence of nifedipine, ACh-induced L-NNA-resistant relaxations were observed in FBMA only. Pinacidil produced relaxations in all different-sized blood vessels, although sensitivity was inversely related to vessel size. The extent of the ACh hyperpolarizing responses was much smaller than that by pinacidil in the aorta. The membrane potential changes by ACh and pinacidil were almost the same in FBMA. These results indicate that the contribution of EDHF to endothelium-dependent relaxations increases as the vessel size decreases. This may be partly explained by precontractile processes dependent on Ca(2+) entry through L-type Ca(2+) channels, because Ca(2+) channel deactivation seems to be involved as a major mechanism of EDHF-mediated vasorelaxations. However, EDHF may also generate vasorelaxations by an additional mechanism, probably a reduced Ca(2+) sensitivity of contractile elements, as proposed for ATP-sensitive K(+) channel openers.

Analysis of Variance↗

PubMedDate not supplied

Histopathologic and flow cytometric analysis of colorectal polyps resected at endoscopy.

Forty-seven colorectal polyps of various histologic types were studied using retrospective flow cytometric (FCM) DNA analysis to determine the prevalence of aneuploid cell populations and whether they were associated with any particular histologic features. Overall, 6 of 47 polyps (12.8%) contained DNA aneuploid cells, comprising 4 adenomatous polyps, 1 of 12 with mild atypia (8.3%), 2 of 19 with moderate atypia (10.5%) and 1 of 4 with severe atypia (25.0%), and 2 of 4 polyps (50.0%) with histologic features of carcinoma in situ (CIS). The incidence of DNA aneuploid cells in CIS was significantly higher than that of all adenomatous polyps (p = 0.043). All of the 8 hyperplastic polyps were diploid. The detection of aneuploidy as a marker of increased risk for malignant transformation was possible even in colorectal adenomas measuring < or = 10 mm. These results show that retrospective FCM analysis can detect DNA aneuploidy in adenomatous polyps and that DNA aneuploidy may occur before histologic evidence of invasive carcinoma.

Adenoma↗

PubMedDate not supplied

Enhanced 5-HT2 receptor mediated contractions in diabetic rat aorta: participation of Ca2+ channels associated with protein kinase C activity.

The aim of this study was to determine how the contractile responses to 5-hydroxytryptamine (5-HT) are altered in aortas from rats with streptozotocin-induced diabetes and to explore the possible mechanisms of the altered vascular reactivity to 5-HT in diabetes. In the presence of extracellular Ca2+ (2.5 mM), the contractile responses to stimulation of 5-HT2 receptors with 5-HT were greater in aortas from diabetic rats as compared with those from age-matched controls. Similarly, phorbol-12,13-dibutyrate (PDBu) (> or = 30 nM) induced significantly greater contractions in diabetic aortas. The enhanced contractile responses of diabetic aortas to 5-HT and PDBu were abolished in the presence of 1 microM nifedipine. Pretreatment with 20 nM staurosporine caused a complete inhibition of the contractile responses to 5-HT in both control and diabetic aortas. In contrast to those to 5-HT and PDBu, the contractile responses to high K+ (40 mM) were markedly diminished in diabetic aortas. The nifedipine-sensitive uptake of 45Ca2+ induced by 5-HT was significantly greater in diabetic aortas than in controls, whereas that induced by high K+ was significantly less in diabetics. The phasic contractions produced by 5-HT in Ca(2+)-free medium were significantly attenuated in diabetic aortas, but those produced by norepinephrine were unchanged. Accumulation of [3H]inositol monophosphate (IP1) in aortic strips prelabeled with myo-[3H]inositol was increased to a similar extent by 5-HT and norepinephrine in control rats, but the 5-HT-induced increase in [3H]IP1 accumulation was significantly less than the norepinephrine-induced one in diabetics. These findings indicate that the extracellular Ca(2+)-dependent contractions mediated by 5-HT2 receptors are enhanced in aortas from diabetic rats, and this is presumably related to a greater influx of Ca2+ through transmembrane Ca2+ channels as a consequence of increased protein kinase C activated processes. On the other hand, the contraction induced by release of Ca2+ from intracellular stores in response to 5-HT is diminished in these tissues, possibly due to the impaired phosphoinositide response.

Alkaloids↗