Instability of artificially circularized chromosomes of Streptomyces lividans

The chromosomes of Streptomyces species are linear molecules, containing long terminal inverted repeats and covalently bound terminal proteins. These chromosomes undergo spontaneous deletions of the terminal sequences at high frequencies and become circularized in several cases examined. Artificial circularization of the Streptomyces lividans chromosome was also achieved by targeted recombination in vivo, in which the terminal inverted repeats of the chromosome were connected by a kanamycin resistance gene (aphII). Under kanamycin selection, the circularized chromosomes harboured tandem amplifications of a 20.2 kb sequence that included the aphII gene flanked by direct repeats and deletions nearby. On release from kanamycin selection, the aphII amplifications and the neighbouring sequences were deleted from the chromosomes, rendering all the cultures kanamycin sensitive. The chloramphenicol resistance gene, which was prone to deletion in wild-type S. lividans, became much more stable in the kanamycin-sensitive derivatives. These results indicate that the telomeres and/or certain terminal sequences may be involved in the structural instability of Streptomyces chromosomes.     

Age-dependent decrease in embryo implantation rate after in vitro fertilization

OBJECTIVE: To investigate the relation between the implantation rate per embryo after replacement in IVF-ET in relation to female age. DESIGN: Retrospective study using linear and biphasic models in a multivariate analysis. SETTING: Academic tertiary care institution. INTERVENTION(S): In vitro fertilization-ET and determination of gestational sacs at 6 to 7 weeks of pregnancy buy ultrasound. MAIN OUTCOME MEASURE(S): Implantation rate as defined by the number of gestational sacs per embryo replaced. RESULT(S): Woman's age and embryo morphology were strongly related to the implantation rate, indication for IVF-ET and cycle rank number also were related significantly but less strongly. A linear model was built describing the decrease in implantation rate with age, resulting in a decrease of approximately 7%. A biphasic model was tested also and performed significantly better, resulting in a yearly decrease of > 20% after 37 years of age. CONCLUSION(S): The most important independent factors related to the ability of embryos to implant are female age and embryo morphology. The best way to describe the relation with female age is biphasic model with a discontinuity at approximately 37 years of age.     

Entropy-driven binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles

This study employed large unilamillar vesicles composed of purchased stratum corneum lipids to investigate the binding/partition of amino acids/dipeptides to stratum corneum lipid vesicles. The partition coefficients of amino acids/dipeptides between the stratum corneum lipid vesicles and the acetate buffer were determined by HPLC. In addition, the binding/partition enthalpy of amino acids/dipeptides with the stratum corneum lipid vesicles was derived by directly measuring the binding/partition heat with isothermal titration calorimetry. According to the binding/petition Gibbs free energy and the binding/partition enthalpy, all the binding/partition of amino acids/dipeptides with the stratum corneum lipid vesicles is endothermic, implying an entropy-driven binding/partition. Also, the equilibrium binding/partition results demonstrate that the partition coefficients of amino acids/dipeptides do not correlate with the transdermal permeability. This finding suggests that either the interaction between the penetrants and the lipid bilayer between corneocytes may not be a determining step or that the paracellular path is not a dominant route of transdermal penetration.     

Pharmacological analysis of intracellular Ca2+ signalling: problems and pitfalls

Sexual coercion, a topic of relevance to school health personnel, may be as common in high school populations as in university populations. Twenty-one sexuality education curricula were examined for information on the topics of date rape, stranger rape, pressure, incest, sexual harassment, unwanted/inappropriate touch, and exploitation/victimization. Curricula scoring highest in total coverage also were the most comprehensive with six of the seven sexual coercion topics covered. Overall, pressure and exploitation/victimization received the greatest attention, while sexual harassment was not covered in any of the curricula. Common themes occurring within the coercion topic areas included guilt, communication/assertiveness skills, blame, drug use, premeditation, fear, sources of help. Results suggest sexuality education curricula have not responded to the increased concern regarding sexual harassment in schools.     

Aortic perforation during lumbar laminectomy

A method to determine the optimal replacement time for dye affinity adsorbents used in protein purification processes that are subjected to severe regeneration conditions has been developed. To demonstrate the utility of the method, an experimental fixed-bed decay model was employed to determine the optimum number of cycles for the adsorbent replacement. This number is a function of the column regeneration frequency and of the capital and operation costs. The implications of the results on the design and operation of dye-ligand chromatographic processes are discussed.     

Cerebrospinal fluid levels of oxytocin in Prader-Willi syndrome: a preliminary report

BACKGROUND: Prader-Willi syndrome (PWS) is a genetic disorder characterized by mental retardation, appetite dysregulation, and a high risk for obsessive-compulsive disorder (OCD). Microscopic abnormalities of the hypothalamus have been described in PWS, and oxytocin has been implicated in both appetite regulation and OCD. METHODS: Oxytocin and arginine vasopressin (AVP) were measured in the cerebrospinal fluid of 5 subjects with PWS (2 male, 3 female) and in 6 normal control subjects (all female). RESULTS: CSF oxytocin was elevated in PWS (9.2 +/- 3.9 pmol/L) as compared to normal control subjects (5.1 +/- 0.9 pmol/L, p = 0.045), a finding that was more significant when excluding male subjects from analysis (p = 0.02). AVP was not significantly different between the groups as a whole. CONCLUSIONS: These data provide further evidence for hypothalamic and oxytocinergic dysfunction in PWS. The associations between oxytocin, appetite regulation, and obsessive compulsive symptomatology in PWS warrant further investigation.     

Homeless at risk of mortality: a proactive approach to vulnerable "repeaters"

Certain flavonoids having a C-2,3-double bond were reported to show an inhibitory activity against T-lymphocyte proliferation, but not against B-lymphocyte proliferation in vitro. In the course of these studies, vitexicarpin (3',5-dihydroxy-3,4',6,7-tetramethoxyflavone) isolated from the fruits of Vitex rotundifolia was found to show potent inhibition against lymphocyte proliferation. Vitexicarpin inhibited T-lymphocyte proliferation as well as B-lymphocyte proliferation at > 0.1 microM. IC50's were approximately 0.7 microM both for T- and B-cell proliferation. The inhibitory activity of vitexicarpin was reversible. Vitexicarpin also inhibited the growth of certain cancer cell lines, EL-4 and P815.9 (IC50 = 0.25-0.3 microM). These results suggest that vitexicarpin may be a potential therapeutic agent involved in inflammatory/immunoregulatory disorders such as rheumatoid arthritis and lymphomas.     

Nucleotide sequencing of S-RNA segment and sequence analysis of the nucleocapsid protein gene of the newly isolated Akabane virus PT-17 strain

The nucleotide sequences of the S-RNA of Akabane viruses JaGAr-39, OBE-1, Iriki and the newly isolated PT-17 strains and the Aino virus were determined and compared. The results reveal that the S-RNAs of the four Akabane strains share 96.9% homology in nucleotide sequences. Only one amino acid difference out of the 233 amino acids of the nucleocapsid protein (N) and three amino acid differences in the 91 amino acids of the nonstructural protein (NSs) were found among the Akabane viruses. Amino acid sequences of N and NSs proteins of the Aino virus have approximately 80% identity as compared with the Akabane viruses. The results also demonstrate that the four Akabane viruses and the Aino virus can be clearly differentiated by RFLP (restriction fragments length polymorphism) analysis using RT-PCR generated nucleocapsid protein genes and digested with HaeIII and HindIII. The phylogenetic tree based on the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) analysis of the sequences of nucleocapsid protein genes and the S-DNAs revealed that the newly isolated PT-17 strain is most closely related to Iriki strain, than the JaGAr-39 or OBE-1 strains.