Maternal age does not affect tetrahydrocannabinol's in utero actions in rats

The potential contribution of maternal age to tetrahydrocannabinol's (THC) in utero effects in rats was studied. Pregnant animals were intubated with 25, 10 or 0 mg/kg of THC from gestation day six to parturition. Animals in the 10 and 0 mg/kg groups were pair fed to those given the 25 mg/kg dose. Each series of doses was administered to females three, four or six months of age. THC lowered maternal weight gain and weights of offspring at birth and at 21 days of age, but did not affect litter size, spontaneous alternation or passive avoidance learning in offspring. Increased maternal age was associated with smaller litter size and lower birth weight and weight at 21 days, but did not interact significantly with THC.     

Evolution of the ATP-binding-cassette transmembrane transporters of vertebrates

The ATP-binding-cassette transmembrane transporters (ABC transporters) known from vertebrates belong to four major subfamilies: (1) the P- glycoproteins (Pgp); (2) the cystic fibrosis transmembrane conductance regulators (CFTR); (3) the Tap proteins encoded with the major histocompatibility complex of mammals; and (4) the peroxisomal membrane proteins. Both Pgp and CFTR have a structure suggesting a past internal gene duplication; a phylogenetic analysis indicated that these duplications occurred independently, while an independent tandem gene duplication occurred in the case of the Tap family. Both the Pgp and Tap proteins show evidence of relationship to bacterial ABC transporters lacking internal duplication, and both are significantly more closely related to the HlyB and MsbA families of transporters from purple bacteria than they are to ABC transporters from nonpurple bacteria. The simplest hypothesis to explain this observation is that eukaryotic Pgp and Tap genes are descended from a mitochondrial gene or genes that were subsequently translocated to the nuclear genome. The Pgp genes of eukaryotes are characterized by a remarkable degree of convergent evolution between the ATP-binding cassettes of their N- terminal and C-terminal halves, whereas no such convergence is seen between the two halves of CFTR genes or between the duplicated Tap genes. Exon 13 of the CFTR gene, which encodes a putative regulatory domain not found in other ABC transporters apart from CFTR, showed high levels of both synonymous and nonsynonymous difference in comparisons among different mammalian species, suggesting that this region is a mutational hot spot.      

Evidence for the presence of β-lactamase inStreptomyces glaucescens and its inhibition by sodium clavulanate

Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis.     

Selective activation of cyclic AMP dependent protein kinase by calcitonin in a calcitonin secreting lung cancer cell line

When the F1-ATPase from the thermophilic bacterium, PS3, was inactivated by 90% with 7-chloro-4-nitro[14C]benzofurazan ([14C]Nbf-Cl) at pH 7.3 and then gel-filtered, 1.25 mols of [14C]Nbf-O-Tyr and less than 0.1 mol of Nbf-N-Lys were formed per mol of enzyme. After adjusting the pH of the gel-filtered, modified enzyme to 9.0 and incubating it for 14 hrs. at 23 degrees C to promote O----N migration, 0.68 mol of Nbf-N-Lys were formed per mol of enzyme while about 16% of the original activity reappeared. Isolation of the subunits after the O----N migration showed that 90% of the incorporated 14C was present in the beta subunit, which contained 0.21 mols of [14C]Nbf-N-Lys per mol. A tryptic peptide which contained the majority of the 14C incorporated into the beta subunit was isolated and subjected to automatic amino acid sequence analysis contained 38 residues. The amino acid sequence immediately around the lysine residue labeled with [14C]Nbf-, K*, was found to be: ...I-G-L-F-G-G-A-G-V-G-K*-T-V-L-I-G... .     

Optimal muscular coordination strategies for jumping

This paper presents a detailed analysis of an optimal control solution to a maximum height squat jump, based upon how muscles accelerate and contribute power to the body segments during the ground contact phase of jumping. Quantitative comparisons of model and experimental results expose a proximal-to-distal sequence of muscle activation (i.e. from hip to knee to ankle). We found that the contribution of muscles dominates both the angular acceleration and the instantaneous power of the segments. However, the contributions of gravity and segmental motion are insignificant, except the latter become important during the final 10% of the jump. Vasti and gluteus maximus muscles are the major energy producers of the lower extremity. These muscles are the prime movers of the lower extremity because they dominate the angular acceleration of the hip toward extension and the instantaneous power of the trunk. In contrast, the ankle plantarflexors (soleus, gastrocnemius, and the other plantarflexors) dominate the total energy of the thigh, though these muscles also contribute appreciably to trunk power during the final 20% of the jump. Therefore, the contribution of these muscles to overall jumping performance cannot be neglected. We found that the biarticular gastrocnemius increases jump height (i.e. the net vertical displacement of the center of mass of the body from standing) by as much as 25%. However, this increase is not due to any unique biarticular action (e.g. proximal-to-distal power transfer from the knee to the ankle), since jumping performance is similar when gastrocnemius is replaced with a uniarticular ankle plantarflexor.     

Transplantation of Hymenolepis diminuta into naive, immune and irradiated mice.

Almost 100% of 7- to 10-day-old Hymenolepis diminuta became established when surgically transplanted from donor mice into the duodenum of naive recipient mice. Transplanted tapeworms survived 8-12 days, by which time they had survived much longer in total than they would have done in the donor. Mice previously immunized by a primary infection rejected transplants within 4 days. Sub-lethal irradiation (550 rad) delayed rejection by immune mice but such mice still rejected worms much more quickly than did naive mice. Surgery was shown to delay by 2-3 days the rejection of worms by naive mice, and the importance of circumventing surgery by administering the worms per os is emphasized. Prospects for reconstituting irradiated immune mice are considered vis-à-vis work with nematodes, and the differences which, on present knowledge, appear to exist between nematode and cestode rejection are briefly discussed.     

Three-Dimensional Trabecular Alignment Model

The Shear-slip Mesh Update Method (SSMUM) is being used in flow simulations involving large but regular displacements of one or more boundaries of the computational domain. We follow up the earlier discussion of the method with notes on practical implementation aspects. In order to establish a benchmark problem for this class of flow problems, we define and report results from a two-dimensional viscous flow around a rotating stirrer in a square chamber. The application potential of the method is demonstrated in the context of biomedical design problem, as we perform an analysis of blood flow in a centrifugal left ventricular assist device, or blood pump, which involves a rotating impeller in a non-axisymmetric housing.