Synthesis and characterization of mixed ruthenium/platinum mu(4)-phosphinidene, phosphorus monoxide, and related clusters.

The mixed-metal cluster complexes [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-PR)] [R = N(i)Pr(2) (1), F (3)] were formed by capping the Ru(3)P face of the nido clusters [Ru(4)(CO)(13)(mu(3)-PR)] with the labile Pt(0) reagent [(eta(2)-C(2)H(4))Pt(PPh(3))(2)]. The aminophosphinidene complex 1 undergoes acid hydrolysis to yield the PO complex [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-PO)][H(2)N(i)Pr(2)] (4). The fluorophosphinidene cluster 3 reacts with ethanol to form the alkoxyphosphinidene complex [Ru(4)(CO)(12)Pt(CO)PPh(3)(mu(4)-POEt)] (5). Comparison of spectroscopic and structural data for clusters 1, 3, 4, and 5 reveals the remarkable effects of the mu(4)-phosphinidene and phosphorus monoxide ligands on cluster bonding.

Diagnostic polymerase chain reaction assays for identification of murine polyomaviruses in biological samples.

PURPOSE: Mouse polyoma virus and K virus are murine polyomaviruses frequently used in carcinogenicity and cellular biology studies in mice. These viruses can cause persistent infections, which increase the likelihood of transmission through transplantation of cells from infected mice. To identify polyomavirus-infected biological samples, several diagnostic polymerase chain reaction (PCR) assays were developed. METHODS: Polyomavirus-family and virus-specific PCR assays were designed and optimized for specificity and sensitivity. The generic (polyomavirus-family) PCR assay and mouse polyoma virus-specific assays were compared with the mouse bioassay for diagnosis of infected cellular samples. RESULTS: Specificity of the PCR assays was confirmed by testing a battery of other murine viruses. The mouse polyoma virus PCR test was the most sensitive assay, detecting as few as 2,000 copies of homologous virus. The K virus PCR assay was about eightfold less sensitive, and the generic PCR test was the least sensitive. Mouse polyoma virus and generic PCR assays amplified mouse polyoma virus in the inoculum and tissues from experimentally infected mice, and performed better than did the mouse bioassay. CONCLUSIONS: Results of this study confirm that PCR is a specific and sensitive method for detection of murine polyomaviruses in biological samples.

Coxiella burnetii infection in C.B-17 scid-bg mice xenotransplanted with fetal bovine tissue.

Two from a group of approximately 50 C.B-17 scid-bg mice were examined because of lethargy, dehydration, and rough coat. Three months prior to development of clinical signs of disease, mice of this study had been surgically implanted with fetal bovine liver, thymus, and lymph node. At necropsy, marked splenomegaly and mild hepatomegaly were observed in both animals. Large areas of necrosis and inflammation, with associated intracytoplasmic granular basophilic inclusions, were observed in histologic sections of multiple organs. Aerobic and anaerobic culturing of the liver yielded negative results. Six months after the initial case, four more reconstituted scid-bg mice from a different fetal donor had identical clinical, gross, and histologic signs of disease. To determine whether the basophilic inclusions represented an infective agent, 4-month-old immune-naive C.B-17 scid-bg mice were inoculated intraperitoneally with a liver and spleen homogenate from an affected mouse. Two weeks after inoculation, mice developed clinical signs of disease and lesions identical to those seen in the signal mice. On ultrastructural examination of the liver, pleomorphic bacteria were found in large cytoplasmic vacuoles of hepatocytes. Bacterial DNA was amplified from the liver, using primers that amplify a segment of the 16S rRNA gene from many bacterial species. Sequencing of the polymerase chain reaction (PCR) product revealed gene sequence identical to that of Coxiella burnetii, the agent of Q-fever. These results highlight the need to consider infective agents of the donor species when working with xenografted animals.

Synthesis and structure of the cluster ion pair [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]]. A theoretical overview of M3(mu-PR2)3 frameworks.

The compound [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]] (1), obtained via the addition of PCl(NPri2)2 to K2[Ru4(CO)13], crystallizes in the monoclinic space group P2l/c with a = 15.537(8) A, b = 36.151(16) A, c = 19.407(5) A, beta = 91.14(2) degrees, Z = 4, and R = 0.069 for 8006 observed reflections. The unit cell is unusual in that it contains both a typical octahedral Ru6 cluster anion (1a), featuring an encapsulated carbide, and a symmetrical phosphido bridge, in addition to a 50-electron trinuclear cluster cation [Ru3(CO)9[mu-P(NPri2)2]3]+ (1c). The latter, with approximate D3h symmetry, exhibits long Ru-Ru distances (> or = 3.15 A). Among the family of clusters with M3(mu-PR2)3 cores and different numbers of both electrons (TEC) and terminal ligands (LxLyLz), 1c is unique in that it is a 333 stereotype with 50 valence electrons. MO calculations permit us to predict the existence of redox congeners of 1c clusters and related 48e Re3 clusters. This work also presents a summary of the relationships between the electronic and the geometric structures for all known M3LxLyLz(mu-PR2)3 species. The basic stereochemical features are influenced by the total-electron count and, hence, by the degree of M-M bonding, as well as the remarkable flexibility of the phosphido bridging ligands. The mu-PR2 ligands need not necessarily lie in the M3 plane, and a wide range of M-P-M angles (as small as 72 degrees or as large as 133 degrees) have been observed.

Changes in serum antioxidant concentrations during infection with caprine lentivirus.

We are currently using caprine arthritis encephalitis virus (CAEV) infection in goats as a model to understand changes in some clinical parameters and host response to infection with human immunodeficiency virus (HIV). The objective of this study was to measure changes in serum antioxidant activities in various age groups of goats infected with CAEV. Serum from CAEV-infected goats had significantly higher catalase activity (105.47 +/- 5.96 kU/l) than serum from healthy control goats (79.92 +/- 17.06 kU/l). Moreover, serum catalase activity increased with increase in the time after infection with CAEV. No change was observed in total superoxide dismutase (SOD) or glutathione peroxidase activity although CuZn SOD levels were elevated in infected goats. There was a positive correlation between serum catalase activity and hydrogen peroxide (H2O2) scavenging activity (r = 0.70, p < 0.05). In order to investigate cell membrane integrity, we determined lactate dehydrogenase (LDH) activity in infected goats. Although there was a transient increase in LDH no correlation was observed between increased serum catalase activity and LDH activity (r = 0.16, p > 0.05). We have earlier observed decreased oxyradical production in CAEV infected goats. This observed increase in serum catalase, a scavenger of endogenous free radicals such as H2O2 may be partly responsible for the observed decrease in oxygen radicals found in vivo.

Chemical alkylation of lead (II) salts to tetraalkyllead (IV) in aqueous solution.

Methylation of lead in the environment would have serious consequences for water quality and for the well being of aquatic biota. As there is strong evidence that tetraalkylleads, the end products of lead alkylation, are considerably more toxic than lead (II) compounds, the elevated levels of inorganic lead now present in inland waterways and sediments as a result of industrial and motor vehicle emissions will pose a serious environmental hazard if mechanisms exist for the conversion to alkyllead (IV) species in aquatic systems. In the belief that the key to biological Pb(II) methylation lies in methyl transfer to Pb(II) from a carbonium ion donor (for example, S-adenosylmethionine), we recently initiated chemical and biological studies on the reactions of CH3+ donors with neutral and anionic Pb(II) compounds. We describe here the unequivocal synthesis of volatile tetramethyllead and other tetraalkylleads from Pb(II) salts and simple chemical reagents in aqueous solution. The known occurrence of methyl iodide in natural waters and our demonstration that Me4Pb is readily synthesized from this reagent and Pb(II) salts in aqueous solution could have far reaching significance not only for the chemical synthesis of toxic organoleads but also for possible mechanisms of microbiological methylation.