Theoretical study of the product specificity in the hydroxylation of camphor, norcamphor, 5,5-difluorocamphor, and pericyclocamphanone by cytochrome P-450cam

The hydroxylations of d-camphor, norcamphor, pericyclocamphanone, and 5,5-difluorocamphor by cytochrome P-450cam have been examined using theoretical methods to identify and characterize properties which determine product specificity. Experimental results indicate that each molecule is hydroxylated with quite different regio-specificity when metabolized by P-450cam. This result is surprising in view of their overall structural similiarity. Herein we report the results of calculations on d-camphor and three of its analogues which suggest that all of these molecules should, when metabolized by P-450cam, form hydroxylation products and predict the product distribution for each. Our conclusions are based on two fundamental criteria which are consistent with a generally accepted radical mechanism in determining product specificity in these molecules: 1) relative heats of formation of the radicals formed by abstracting a hydrogen, and 2) orientation of the substrate molecule with respect to the putative active oxygen species bound to iron. Our results explain the experimental observations for camphor and 5,5-difluorocamphor but disagree with original published results for norcamphor and pericyclocamphanone. In light of our results, new experiments have been performed for norcamphor and the original data reexamined for pericyclocamphanone. Our predictions have recently been experimentally confirmed for norcamphor, and unpublished data (Dr. S. Sligar) suggest that the same is true for pericyclocamphanone.     

Immortalization of human endothelial cells by murine sarcoma viruses, without morphologic transformation

Amphotropic murine leukemia virus pseudotypes of murine sarcoma viruses containing the ras or mos oncogenes were constructed to permit efficient introduction of the sarcoma virus genome into early-passage human umbilical vein endothelial cells. The resulting cell lines were morphologically and phenotypically unchanged, retaining properties characteristic of differentiated endothelial cells. For example, the cells in a Kirsten sarcoma virus-modified line were found to biosynthesize and secrete von Willebrand factor in both a constitutive and regulated manner, and they contained ultrastructurally identifiable Weibel-Palade bodies, an endothelial cell-specific organelle. In contrast to the parent cultures, sarcoma virus-modified cells were able to proliferate indefinitely in culture. Examination of both Kirsten sarcoma and Moloney leukemia virus-modified lines indicated that the immortalized cells retained a diploid female karyotype after over 18 months in culture. In addition, the sarcoma virus-modified cells were able to grow independently of added endothelial cell growth factor. This growth factor autonomy does not appear to be due to autocrine production of a biologically cross-reactive growth factor. These immortal, virus-modified endothelial cells express large amounts of sarcoma virus-specific mRNA but no detectable helper virus or transforming virus activity. This technique for immortalization of primary human cells without alteration of the differentiated characteristics of the cell type is readily applied to a variety of human cell types. Moreover, the ability to separate the immortalizing and transforming activities of viral oncogenes should provide further understanding as to mechanisms of oncogene action.     

Randomised trial of prophylactic daily aspirin in British male doctors

A six year randomised trial was conducted among 5139 apparently healthy male doctors to see whether 500 mg aspirin daily would reduce the incidence of and mortality from stroke, myocardial infarction, or other vascular conditions. Though total mortality was 10% lower in the treated than control group, this difference was not statistically significant and chiefly involved diseases other than stroke or myocardial infarction. Likewise, there was no significant difference in the incidence of non-fatal myocardial infarction or stroke—indeed, disabling strokes were somewhat commoner among those allocated aspirin. The lower confidence limit for the effect of aspirin on non-fatal stroke or myocardial infarction, however, was a substantial 25% reduction. Migraine and certain types of musculoskeletal pain were reported significantly less often in the treated than control group, but as the control group was not given a placebo the relevance of these findings was difficult to assess. There was no apparent reduction in the incidence of cataract in the treated group.The lack of any apparent reduction in disabling stroke or vascular death contrasts with the established value of antiplatelet treatment after occlusive vascular disease.     

Somatic embryogenesis and plant regeneration from zygotic embryo explants in mexican weeping bamboo,Otatea acuminata aztecorum

An efficient protocol has been developed for the in vitro propagation of Mexican Weeping Bamboo through somatic embryogenesis from zygotic embryo explants. Mature seeds and excised embryos were cultured in the light or in the dark on both Murashige and Skoog's and Gamborg's B5 basal media with various supplements. Optimal somatic embryogenesis and plant regeneration were obtained by culture in the dark on Murashige and Skoog's basal medium supplemented with 3 mg/1 2,4-dichlorophenoxyacetic acid, 0.5 mg/1 6-benzylaminopurine and 2.0% sucrose. More than 95% of the germinating somatic embryos developed shoots and roots, and were transferred to soil with 85% success.     

The gene for a novel epidermal antigen maps near the neurofibromatosis 1 gene.

Recently the M17S1 gene, encoding an epidermal antigen thought to play a role in cell adhesion, was mapped to chromosome bands 17q11-q12, placing it in the vicinity of the gene for the genetic disorder neurofibromatosis 1 (NF1). The pleomorphic cutaneous lesions of NF1 and the precedent for other genes being embedded within the NF1 gene prompted us to investigate whether the M17S1 gene mapped near, or within, the NF1 gene. Genetic linkage analyses revealed that M17S1 was tightly linked to NF1 and mapped within the interval bounded by D17S58 and D17S54. Physical mapping of an M17S1 cDNA on somatic cell hybrids, yeast artificial chromosomes, and an NF1 patient with a deletion involving an entire NF1 allele demonstrated that M17S1 is located at least 180 kb centromeric to the NF1 gene. The distance between the genes suggests that M17S1 is unlikely to contribute to the NF1 phenotype since a gross chromosomal rearrangement would be required to disrupt expression of both genes.     

The problem of movelength and turn definition in analysis of orientation data.

This study examines the analysis of arthropod orientation data. Three problems are discussed: (1) dealing with time as it applies to spatial data, (2) determining the appropriate movelength to be used in collecting and in analyzing data, and (3) defining a turn, to discriminate between "gait noise" and course changes. The main objective is to determine the solution to defining the most appropriate movelength for comparisons between variables and between species. The technique described here for selecting the appropriate movelength that has relevance to both the locomotory rate of the animal and its body length, reduces variation resulting from lateral translational movements, prevents the use of movelengths that lead to artifactual or unrealistic turning values per move, and permits comparisons of species and individuals under various stimulus conditions.     

In vitro OKT3-induced mitogenesis in selenium-deficient patients on a diet for phenylketonuria

Patients with phenylketonuria (PKU) are frequently deficient in the essential trace element selenium (Se), because of their very low protein diet. Using two approaches to investigate T-cell response to proliferative signaling, viz, mitogenesis caused by the monoclonal antibody OKT3 and the plant lectin phytohaemagglutinin (PHA), we demonstrated significantly reduced responses to optimal concentrations of OKT3 in a group of PKU patients with reduced serum Se compared with a normal group (p = 0.0005) and with a group of PKU patients whose serum Se was normal (p = 0.0023). The response of the Se-deficient group to optimal levels of PHA did not differ from that of the normal controls or from that of Se-normal PKU patients. A dose-dependent relationship between serum Se levels and mitogenic response was evident for OKT3 (r = 0.34, p = 0.0154), but not for PHA (r = -0.02, p = 0.9086). We suggest that the reduced response to OKT3 mitogenesis in Se-deficient PKU patients is possibly the consequence of impaired Se-dependent metabolic activity, which affects mitogenic signaling via the T cell antigen receptor (TCR/CD3) complex.     

Molecular cloning in Lactobacillus helveticus by plasmid pSA3::pVA797 co-integrate formation and conjugal transfer

Summary A gene encoding -glucanase activity from Bacillus amyloliquefaciens was subcloned in both orientations into plasmid shuttle vector pSA3. In only one orientation could a co-integrate be generated with the conjugative plasmid pVA797. The plasmid co-integrate was conjugated into Lactobacillus helveticus strain CNRZ450, where it was stably maintained without antibiotic selection and exhibited -glucanase activity. This method of introducing cloned DNA into thermophilic lactobacilli will facilitate the study of heterologous gene expression in non-transformable species. Offprint requests to: J. K. Thompson