3-(1-Hydroxyethylidene)-1-phenylpyrrolidine-2,4-dione.

Analysis of C(12)H(11)NO(3) revealed a coplanar N-substituted phenyl group on a pyrrolidine ring with two keto moieties and a hydroxyethylidene functionality. The hydroxy group forms part of a hydrogen-bonding network characterized by a short intramolecular H.O distance of 1.81 (3) A, and a longer intermolecular interaction with an H.O distance of 2.38 (3) A. Both keto groups form additional intra- and intermolecular C-H.O contacts with H.O distances ranging from 2.26 to 2.41 A.

(3R,4aS,5R)-3-Hydroxy-5-isopropenyl-3,8-dimethyl-4,4a,5,6-tetrahydro-2(3H)-naphthalenone.

In the crystal structure of C(15)H(20)O(2), molecules are associated by intermolecular hydrogen bonds between the hydroxy function and a keto group [O.O 2.770 (2) A], forming chains along the [100] direction in the crystal. Both six-membered rings in the decalin unit adopt envelope conformations; one section of the molecule, encompassing the extended conjugation of a C=C double bond with an enone functionality [C=C-C=O = 175.6 (2) degrees and C=C-C=C = 176.6 (2) degrees ], is flat, whilst the rest of the molecule is folded relative to the constrained part. The stereochemistry was determined from the R-(-)-carvone starting material.

Silver as an exopolyhedral auxiliary to the rhenacarborane anion [Re(CO)3(eta5-7,8-C2B9H11)]-.

The rhenacarborane salt Cs[Re(CO)3(eta5-7,8-C2B9H11)] (1) has been used to synthesize the tetranuclear metal complex [[ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3]2[mu-Ph2P(CH2)2PPh2]] (3) where two [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3] fragments have been shown by X-ray crystallography to be bridged by a single 1,2-bis(diphenylphosphino)ethane ligand. Reaction of 1 with Ag[BF4] in the presence of the ligands bis- or tris(pyrazol-1-yl)methane yields the complexes [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3[kappa2-CH2(C3H3N2-1)2]] (4) or [[ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3]2[mu-kappa1,kappa2-CH(C3H3N2-1)3]] (5), respectively. From X-ray studies, the former comprises a Re-Ag bond bridged by the carborane cage and with the bis(pyrazol-1-yl)methane coordinating the silver(I) center in an asymmetric kappa(2) mode. Complex 5 was unexpectedly found to contain a tris(pyrazol-1-yl)methane bridging two [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3] fragments in a kappa1,kappa2 manner. Treatment of 1 with Ag[BF4] in the presence of 2,2'-dipyridyl and 2,2':6',2' '-terpyridyl yields [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3[kappa2-(C5H4N-2)(2)]] (6) and [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3[kappa3-C5H3N(C5H4N-2)2-2,6]] (7). The X-ray structure determination of 7 revealed an unusual pentacoordinated silver(I) center, asymmetrically ligated by a kappa3-2,2':6',2' '-terpyridyl molecule. The same synthetic procedure using N,N,N',N'-tetramethylethylenediamine gave a tetranuclear metal complex [[ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3]2[mu-Me2N(CH2)2NMe2]2] (8) which is believed, in the solid state, to be bridged between the silver atoms by two of the diamine molecules. The salt 1 with Ag[BF4] in the absence of any added ligand gave the tetrameric cluster [ReAg[mu-5,6,10-(H)3-eta5-7,8-C2B9H8](CO)3]4 (9) where, in the solid state, four [ReAg(mu-10-H-eta5-7,8-C2B9H10)(CO)3] units are held together by long interunit B-H right harpoon-up Ag bonds.

[eta(2)-(E)-But-2-enedinitrile](N,N'-di-phenyl-1,7,7-trimethylbicyclo[2.2.1]-heptane-2,3-diimine-N,N')-palladium(0).

The zero-valent palladium in [Pd(C(4)H(2)N(2))(C(22)H(24)N(2))] is coordinated to two imine N atoms of a derivatized camphor ligand, and to the olefinic C atoms of a pi-bonded fumaronitrile group. The N--Pd--N bite angle of 77.31 (9) degrees is similar to angles observed in other zero-valent palladium diiminoalkene species. The asymmetry of the camphor moiety leads to two different orientations of the N-aryl groups relative to the PdN(2) plane [C==N--C--C torsion angles of 102.4 (4) and 39.4 (4) degrees ].

(5S)-3-oxo-4-oxa-endo-tricyclo[5.2.1.0(2,6)]dec-8-en-5-yl acetate.

The molecular structure of C(11)H(12)O(4), based on a norbornene core, was established to confirm the configuration of an acetoxy side-chain group in addition to the formation of the endo product. The acetoxy side chain lies in an axial position relative to the five-membered fused ring. Bond distances and angles show no unusual features, with all geometric parameters lying within their expected ranges. The overall stereochemistry of the molecule was ascertained from the chiral furanone starting material.

Is interruption in residency training associated with a change in in-training examination scores?

BACKGROUND: Many military physicians interrupt their training to serve in the position of general medical officer (GMO) after completing their first year of postgraduate medical education. This study compares American Board of Family Practice In-training Examination (ITE) scores of military family practice residents who received continuous training (CFP residents) with those who did GMO tours (GMO residents). METHODS: Historical cohorts of CFP and GMO residents from Army and Navy family practice residencies were compared. The dependent measures were their ITE scores in each year of training. Paired data were analyzed using the Student's test. RESULTS: There were no significant differences in composite or clinical problem set scores between GMO and CFP resident groups. Power to detect a true difference between the groups was 74. CONCLUSIONS: Interruption in residency training is not associated with a significant change in the returning resident's ITE scores.

Taxol production in nodule cultures of Taxus.

The in vitro synthesis of secondary compounds from plants is one source of scarce and valuable phytopharmaceuticals. Often, some level of cellular or tissue differentiation is needed for the biosynthesis of many of these important compounds. Nodule cultures, consisting of cohesive multicellular units displaying a high degree of differentiation, were initiated from cultured needles of seven Taxus cultivars (Taxus cuspidata, Taxus x media 'Hicksii', Taxus x hunnewelliana 'Richard Horsey', Taxus x media 'Dark Green Spreader', Taxus x media 'L. C. Bobbick', and Taxus brevifolia). Under normal semicontinuous perfusion culture conditions (bimonthly refreshments to yield 0.2% sucrose), only trace amounts of taxol were detected from Taxus nodule cultures. However, with an elevated sucrose level (0.5% or 1.0%), taxol production was enhanced in T. cuspidata nodules to approximately 12 micrograms taxol/g nodule dry weight (dw). Stimulation of taxol production by elevated sucrose levels occurred even in the absence of other nutrients. The effect of increased sucrose on taxol induction does not appear to be due to an osmotic effect in the medium, suggesting that the increase in taxol production may be correlated with a metabolic process within the nodules. Although sucrose had a significant effect on taxol production, taxane precursors or elicitors of terpenes, as well as other plant secondary metabolites, had no effect on the production of taxol from these cultures. In addition to taxol, the higher sucrose levels also induced the production of 7-epi-10-deacetyltaxol, cephalomannine, and 7-epi-10-deacetylcephalomannine, so that total content of these taxanes equaled approximately 39 micrograms taxane/g dw nodules.

Analysis of linear and nonlinear QSAR data using neural networks.

The use of feed forward back propagation neural networks to perform the equivalent of multiple linear regression has been examined using artificial structured data sets and real literature data. Their predictive ability has been assessed using leave-one-out cross-validation and training/test set protocols. While networks have been shown to fit data sets well, they appear to suffer from a number of disadvantages. In particular, they have performed poorly in prediction for the QSAR data examined here, they are susceptible to chance effects, and the relationships developed by the networks are difficult to interpret. This investigation reports results for one particular form of artificial neural network; other architectures and applications, however, may be more suitable.

Expression of inducible angiosperm promoters in a gymnosperm, Picea glauca (white spruce).

Electrical discharge particle acceleration was used to test the transient expression of numerous inducible angiosperm promoters in a gymnosperm Picea glauca (white spruce). Promoter expression was assayed in three different tissues capable of in vitro regeneration, zygotic embryos, seedlings and embryogenic callus. The promoters tested include the light-inducible Arabidopsis and soybean ribulose-1,5-bisphosphate small subunit promoters and a maize phosphoenolpyruvate carboxylase promoter; a soybean heat-shock-inducible promoter, a soybean auxin inducible promoter and a maize alcohol dehydrogenase promoter. Promoters were cloned into a promoter-less expression vector to form a promoter-beta-glucuronidase-nopaline synthase 3' fusion. A similar construct was made using the cauliflower mosaic virus 35S (CaMV 35S) promoter as a control. All promoters were expressed in white spruce embryos, yet at levels lower than CaMV 35S. In addition, in the embryos the heat-shock and the alcohol dehydrogenase promoters showed inducible expression when given the proper induction stimulus. In seedlings, expression of all promoters was lower than in the embryos and expression was only inducible with the heat-shock promoter in the cotyledons. Of the tissues tested, the expression level of all promoters was lowest in embryogenic callus. Interestingly, the expression of the beta-glucuronidase gene in embryogenic callus was restricted to the proembryonal head cells regardless of the promoter used. These results clearly demonstrate the use of particle bombardment to test the transient expression of heterologous promoters in organized tissue and the expression of angiosperm promoters in a gymnosperm.

Multiple Bud Formation by Cultured Embryos of Pinus ponderosa.

Excised embryos of Pinus ponderosa Dougl. ex Laws formed callus and initiated a few buds from the tips of the cotyledons when placed on the full-strength medium of Sommer et al. (1975) or Cheng (1975). When excised embryos were placed on a full or half strength dilution of the medium of Reilly and Washer (1977) or on a half strength dilution of Cheng (1975), buds were initiated along the entire length of those cotyledons which were in contact with the medium. Initiating buds along the entire length of the cotyledon increased the yield of excisable buds. Benzyladenine must be present in the media for bud initiation; however, the addition of auxin may increase the yield of excisable cotyledonary buds.