Role of DNA in the activation of the Cry1A insecticidal crystal protein from Bacillus thuringiensis

The Cry1A insecticidal crystal protein (protoxin) from six subspecies of Bacillus thuringiensis as well as the Cry1Aa, Cry1Ab, and Cry1Ac proteins cloned in Escherichia coli was found to contain 20-kilobase pair DNA. Only the N-terminal toxic moiety of the protoxin was found to interact with the DNA. Analysis of the crystal gave approximately 3 base pairs of DNA per molecule of protoxin, indicating that only a small region of the N-terminal toxic moiety interacts with the DNA. It is proposed that the DNA-protoxin complex is virus-like in structure with a central DNA core surrounded by protein interacting with the DNA with the peripheral ends of the C-terminal region extending outward. It is shown that this structure accounts for the unusual proteolysis observed in the generation of toxin in which it appears that peptides are removed by obligatory sequential cleavages starting from the C terminus of the protoxin. Activation of the protoxin by spruce budworm (Choristoneura fumiferana) gut juice is shown to proceed through intermediates consisting of protein-DNA complexes. Larval trypsin initially converts the 20-kilobase pair DNA-protoxin complex to a 20-kilobase pair DNA-toxin complex, which is subsequently converted to a 100-base pair DNA-toxin complex by a gut nuclease and ultimately to the DNA-free toxin.     

Treatment of extrahepatic occlusive jaundice with activated charcoal hemoperfusion in dogs

To find the feasibility of treatment for congenital bile duct atresia, we studied the usefullness of extracorporeal hemoperfusion over activated charcoal in canine obstructive jaundice. One, three and five weeks after ligation and disection of common bile duct in 5 dogs we performed the hemoperfusion over activated charcoal extracorporeally (group 3). In this animals we examined hematological and blood coagulation studies, serum electrolyte levels, kidney function tests and liver chemistries. As control in 5 animals we carried out after sham operation the perfusion without common bile duct ligation (group 2) and in 5 animals only common bile duct ligation without perfusion (group 1). In the liver chemistries we found 2 weeks after 2nd and 3rd perfusion (5 and 7 weeks after bile duct ligation) lower levels of serum bilirubin, GOT, GPT and SDH in treated group than in non-treated jaundiced animals. It suggest the effectiveness of hemoperfusion with activated charcoal in the treatment of occlusive jaundice. There were no alteration in the hematological studies, serum electrolyte levels and kidney function tests. PT and PTT was prolonged in the jaundiced animals there were no significant differences with and without hemoperfusion.     

Analysis of theoretical behavior of a proposed zero-order drug delivery system

An analysis of the theoretical behavior of a proposed zero-order drug delivery system is presented. Equations describing drug release with time are developed using a physically realistic model. The theory agrees well with experimental data and indicates that drug release from the device is nearly, although not rigorously, zero order.     

An evaluation of transverse axial emission tomography of the brain in the clinical situation

The Aberdeen section scanner provides, in addition to conventional views, a display of the distribution of radioactivity in a tomographic section of the brain. This paper examined the value of this additional information. Scans of lesions confirmed pathologically or radiologically, along with normal and doubtful cases, were examined after a careful randomization procedure. During the course of the study each set of conventional views was examined twice, once without and once with a tomographic section view. In two out of 29 cases (7%) the lesion was diagnosed only with the aid of the tomographic section scan. Improved accuracy of diagnosis with the tomographic section view was significant at the 1% level or better.     

MR imaging in pretruncal nonaneurysmal subarachnoid hemorrhage: is it worthwhile?

BACKGROUND and PURPOSE: The cause of pretruncal (perimesencephalic) nonaneurysmal subarachnoid hemorrhage is not known. MRI of the brain or spine is often performed to exclude any other vascular abnormalities. Its diagnostic value is not known. METHODS: We used MR imaging of the brain with routine sequences, gadolinium enhancement, and additional thin T1-weighted axial sections following a triple dose of contrast. RESULTS: We performed MR imaging of the brain in 18 patients with a pretruncal nonaneurysmal subarachnoid hemorrhage. The focal nature of the subarachnoid hemorrhage exclusively in front of the brain stem was confirmed in 14 patients studied within 7 days of the ictus. No vascular abnormalities were found in 17 cases, including 14 patients with gadolinium enhancement. An incidental capillary telangiectasia was found in 1 patient. Fluid-attenuated inverse recovery MR additionally documented blood in the sulci due to cerebrospinal fluid recirculation of blood. Five patients underwent MR imaging of the spine, and no arteriovenous malformations were found. CONCLUSIONS: MR imaging did not reveal a source of pretruncal subarachnoid hemorrhage. The cost of MR imaging probably outweighs the benefit in the evaluation of this variant of subarachnoid hemorrhage.     

Induction of cytotoxic T lymphocytes by recombinant canarypox (ALVAC) and attenuated vaccinia (NYVAC) viruses expressing the HIV-1 envelope glycoprotein

Successful immunization against many viruses, including retroviruses such as HIV-1, is thought to depend upon the roles of both antibody and cytotoxic T-lymphocyte responses. With safety a major concern, we developed two poxvirus recombinants expressing the envelope glycoprotein of HIV-1 IIIB. Canarypox (ALVaC), which is not known to replicate in mammalian cells, and a highly attenuated vaccinia (NYVAC) virus deleted of 18 open reading frames associated with virulence and host range were used as vectors. Upon inoculation into BALB/c mice, both the ALVAC and NYVAC recombinants were capable of inducing antibody responses to HIV gp120 and provoking remarkable levels of primary and memory Thy1.2+, CD4-, CD8+ cytotoxic T-lymphocyte responses to the hypervariable V3 loop of the HIV-1 envelope glycoprotein.     

Synthesis and Electrical Characterization of Thin Films of PT and PZT Made from a Diol-Based Sol-Gel Route

Lead titanate (PT) sols were prepared using propanediol, butanediol, or pentanediol solutions of lead acetate trihydrate and titanium diisopropoxide bis(acetylacetonate). Precursor sols for PbZr_0.53Ti_0.47O₃ (PZT) films were prepared from propanediol solutions, with zirconium tetrapropoxide being used as the zirconium source. Films were formed by spin-coating the sols onto silicon and platinized silicon substrates; the resulting gel layers were converted to ceramic films by adopting a two-stage heating schedule with final firing temperatures of 600–700°C. Information on film crystallization, microstructure development, and electrical properties is presented for both compositions. The limiting thickness of surface-smooth crack-free single-layer films was ∼1 μm. The PT films exhibited a "linear" polarization-electric field ( P-E ) response, while the PZT films gave rise to characteristic ferroelectric P-E hysteresis loops. A 0.5 μm thick single-layer PZT film exhibited remanent polarization (P_r) values of ∼34 μC·Cm⁻², with a coercive field ( E _c) of ∼45 kV·Cm⁻²; the relative permittivity (ɛ_r) and the dissipation factor ( D ) were ∼1250 and 0.07. For a 1 μm single-layer PZT film, the respective values were P _r∼19 μC∼Cm⁻², E _c∼40 kV∼Cm⁻², ɛ_r∼750, and D = 0.03.