Synthesis, structure, and magnetism of bimetallic manganese or nickel complexes of a bridging verdazyl radical.

Two binuclear metal-radical complexes, formed by the reaction of M(hfac)(2) x 2H(2)O (M = Mn or Ni; hfac = hexafluoroacetylacetonate) with the 1,5-dimethyl-3-(4,6-dimethylpyrimidin-2-yl)-6-oxoverdazyl radical (3), were synthesized. The binuclear Mn complex 5 (i.e., 3[Mn(hfac)(2)](2)) crystallizes in the monoclinic space group C2/c: C(30)H(17)N(6)O(9)F(24)Mn(2), a = 29.947(3), b = 17.143(3), c = 16.276(3) A, beta = 123.748(3)*, Z = 4. The compound consists of two pseudo-octahedral Mn(II) ions, both bearing two hfac ancillary ligands, bridged by the bis(bidentate) radical 3. The temperature dependence of the magnetic susceptibility of 5 reveals moderate antiferromagnetic exchange between each of the Mn(II) ions and the verdazyl radical (J = -48 cm(-1)). The S = 9/2 ground spin state of the complex was corroborated by low-temperature magnetization versus field measurements. In contrast, the magnetic susceptibility versus temperature behavior of 6 (whose molecular structure is presumed to be analogous to that of 5) indicates that the two Ni(II) ions are strongly ferromagnetically coupled to the verdazyl radical (J = +220 cm(-1)). The magnetization versus field behavior of 5 is consistent with an S = 5/2 ground-state species.

Application of the cavitron ultrasonic surgical aspirator (CUSA) for gynecological laparoscopic surgery using the rabbit as an animal model.

OBJECTIVE: To study the potential application of the cavitron ultrasonic surgical aspirator (CUSA) in gynecological laparoscopic surgery using a rabbit animal model. DESIGN: Twenty-six rabbits were prospectively randomized into two groups. Laparoscopically directed standard injuries were made on the randomly assigned horn and sidewall in all animals with the CUSA. Contralateral injuries were made with a contact neodymium-yttrium aluminum garnet (Nd:YAG) laser in group 1 and with bipolar cautery in group 2. Adhesion and inflammation scores were assessed for two animals in each group at 24, 48, and 72 hours, and seven animals in each group at 14 days. SETTING: University animal research facility. MAIN OUTCOME MEASURES: Adhesion and inflammation scores were compared between animals in the CUSA versus Nd:YAG study and the CUSA versus bipolar cautery at 14 days. RESULTS: No significant difference in uterine or sidewall adhesion scores was noted between the CUSA versus Nd:YAG or the CUSA versus bipolar cautery. Bipolar cautery produced significantly less inflammation on the uterine horn compared with the CUSA (3.0 +/- 0.2 versus 5.3 +/- 0.7, P = 0.0001), but no difference in sidewall inflammation was noted between the CUSA compared with bipolar cautery. No difference in inflammation was observed between the CUSA and the Nd:YAG laser. CONCLUSIONS: The bipolar cautery appears to be preferable to the CUSA for coagulation of uterine lesions, although dissection of the uterus is not possible with bipolar cautery. The CUSA and the Nd:YAG appear to be comparable for uterine horn dissection. Because the CUSA causes similar adhesion formation and tissue inflammation at the sidewall when compared with the Nd:YAG laser and bipolar cautery and may be less likely to damage blood vessels, ureters, or other collagen-rich tissues, the CUSA may represent a promising new surgical tool for laparoscopically directed peritoneal dissection.

Characterization of the multiple forms of cytochrome b559 in photosystem II.

Cytochrome b559 is an essential component of the photosystem II (PSII) protein complex. Its function, which has long been an unsolved puzzle, is likely to be related to the unique ability of PSII to oxidize water. We have used EPR spectroscopy and spectrophotometric redox titrations to probe the structure of cytochrome b559 in PSII samples that have been treated to remove specific components of the complex. The results of these experiments indicate that the low-temperature photooxidation of cytochrome b559 does not require the presence of the 17-, 23-, or 33-kDa extrinsic polypeptides or the Mn complex (the active site in water oxidation). We observe a shift in the g value of the EPR signal of cytochrome b559 upon warming a low-temperature photooxidized sample, which presumably reflects a change in conformation to accommodate the oxidized state. At least three redox forms of cytochrome b559 are observed. Untreated PSII membranes contain one high-potential (375 mV) and one intermediate-potential (230 mV) cytochrome b559 per PSII. Thylakoid membranes also appear to contain one high-potential and one intermediate-potential cytochrome b559 per PSII, although this measurement is more difficult due to interference from other cytochromes. Removal of the 17- and 23-kDa extrinsic polypeptides from PSII membranes shifts the composition to one intermediate-potential (170 mV) and one low-potential (5 mV) cytochrome b559. This large decrease in potential is accompanied by a very small g-value change (0.04 at gz), indicating that it is the environment and not the ligand field of the heme which changes significantly upon the removal of the 17- and 23-kDa polypeptides.

Fusion protein-based epitope mapping of phytochrome. Precise identification of an evolutionarily conserved domain.

Fusion proteins are used to define with precision an evolutionarily conserved domain on the carboxyl-terminal portion of the chromoprotein phytochrome. Simultaneously, assignments of two other epitopes are made with significantly greater precision, while the location of a fourth is confirmed. The epitope-mapping method that is described here is systematic, using complementary, overlapping nested sets of fusion proteins of predefined sequence rather than randomly generated peptides. Moreover, in contrast to previous methods, this approach yields rigorous and unambiguous assignments because it relies solely upon the ability of an antibody to detect a given polypeptide. A cDNA fragment encoding phytochrome amino acids 464-1129, which is its carboxyl terminus, was identified in lambda gt11 and subcloned in frame into the lacZ alpha sequence of pUC18. Four nested sets of subclones in pUC18 were created by digestion with selected restriction endonucleases and with the exonuclease Bal31. Fusion proteins were analyzed by immunoblotting following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The epitope for monoclonal antibody Oat-13 was confirmed to be between residues 551 and 617, while the epitopes for Oat-8 and Oat-28 were narrowed to 624-686 and 624-747, respectively. The epitope recognized by Pea-25, Pea-2, and Oat-15 was resolved unequivocally to a sequence of only seven residues (residues 765-771): N-Pro-Ile-Phe-Gly-Ala-Asp-Glu-C.

Determination of delta 9-tetrahydrocannabinol in human blood and saliva by high-performance liquid chromatography with amperometric detection.

A rapid, sensitive and selective determination of delta 9-tetrahydrocannabinol (THC) in human plasma, serum and saliva was developed with high-performance liquid chromatography with electrochemical detection. Initially, samples were deproteinized, followed by a one step liquid-liquid extraction. Samples were measured by high-performance liquid chromatography with electrochemical detection with 4-dodecylresorcinol as the internal standard. The minimal detectable limit for THC in biological samples was ca. 1 ng/ml with a signal-to-noise ratio greater than 3, corresponding to an on-column sensitivity for THC of ca. 0.5 ng. The detector was operated at + 0.90 V vs. Ag/AgCl and exhibited linearity over a concentration range of 1-150 ng/ml with correlation coefficients of the standard curves greater than 0.99.

The role of acetylator genotype on hepatic and extrahepatic acetylation, deacetylation, and sulfation of 2-aminofluorene, 2-acetylaminofluorene, and N-hydroxy-2-acetylaminofluorene in the inbred hamster.

In vitro rates of acetylation, deacetylation, and sulfation were measured with carcinogenic arylamine, arylamide, and arylhydroxamic acid substrates using enzyme preparations derived from inbred hamster tissues of known acetylator genotype. Homozygous rapid acetylators (Bio. 87.20), heterozygous acetylators (Bio. 87.20 X Bio. 82.72/H F1), and homozygous slow acetylators (Bio. 82.73/H) did not differ significantly with respect to paraoxon-resistant intermolecular N,N-transacetylation reactions from N-hydroxy-2-acetylaminofluorene to 4-aminoazobenzene in tissue cytosol. Similarly, they did not differ with respect to paraoxon-sensitive, microsomal N-hydroxy-2-acetylaminofluorene and 2-acetylaminofluorene deacetylase, and cytosolic N-hydroxy-2-acetylaminofluorene sulfotransferase activity. However, a gene dose-response relationship was observed in the same animals for cytosolic acetyl coenzyme A-dependent 2-aminofluorene N-acetyltransferase activity. Partial purification of liver cytosol yielded two paraoxon-resistant isozyme forms of acetyltransferase activity. The rates of one isozyme were acetylator genotype dependent (polymorphic), whereas the rates of the second isozyme appeared to be acetylator genotype independent (monomorphic). Acetyl coenzyme A-dependent 2-aminofluorene N-acetyltransferase activity was catalyzed at high rates by both isozymes, whereas transacetylation of 4-aminoazobenzene by various acyl donors (N-hydroxy-2-acetylaminofluorene, N-hydroxy-4-acetylaminobiphenyl, and acetyl coenzyme A) was catalyzed primarily (but not exclusively) by the monomorphic acetyltransferase isozyme. These results provide further information concerning the importance of acetylator genotype in the metabolism of carcinogenic arylamines and their metabolites.