A bowhead whale in the eastern North Pacific

Bowhead whales occur in the Arctic year‐round. Their movements are largely correlated with seasonal expansions and reductions of sea ice, but a few recent extralimital sightings have occurred in the eastern and western North Atlantic and one was also documented in the western North Pacific over 50 years ago. Here we present details of a juvenile bowhead whale that was photographed and filmed from above and below the water while it was skim‐feeding in Caamaño Sound, BC, Canada on May 31, 2016. This sighting occurred over 2000 km southeast from the nearest known range for this species in the Bering Sea at a time that most bowhead whales in that region would have been migrating northeast. This sighting represents the first and only documentation of a bowhead whale in the eastern North Pacific to date.     

Determination of two mebeverine metabolites, mebeverine alcohol and desmethylmebeverine alcohol, in human plasma by a dual stable isotope-based gas chromatographic-mass spectrometric method

A dual stable isotope-based GC-MS method was developed for the simultaneous determination of two metabolites of mebeverine, mebeverine alcohol and desmethylmebeverine alcohol, in human plasma. Plasma samples were treated with β-glucuronidase to cleave the glucuronide conjugates of both compounds prior to analysis. The treated plasma was prepared for analysis by solid-phase extraction using octadecylsilane cartridges. The isolated metabolites were derivatized and analyzed by GC-MS using selected-ion monitoring. Plots of peak-area ratio were linear with metabolite concentration from 2 to 200 ng/ml and the limit of detection for both metabolites was 0.5 ng/ml. The GC-MS methodology was applied to the analysis of plasma from human subjects following peroral administration of mebeverine. Pharmacokinetic parameters for both metabolites were determined and suggest that relative systemic mebeverine exposure may potentially be assessed using metabolite kinetics, if the latter subsequently are demonstrated to be linear with mebeverine dose.     

Microscopic and Calorimetric Assessment of Freezing Processes in Uterine Fibroid Tumor Tissue

The use of cryosurgery in the treatment of uterine fibroids is emerging as a possible treatment modality. The two known mechanisms of direct cell injury during the tissue freezing process are linked to intracellular ice formation and cellular dehydration. These processes have not been quantified within uterine fibroid tumor tissue. This study reports the use of a combination of freeze-substitution microscopy and differential scanning calorimetry (DSC) to quantify freeze-induced dehydration within uterine fibroid tumor tissue. Stereological analysis of histological tumor sections was used to obtain the initial cellular volume (V(o)) or the Krogh model dimensions (deltaX, the distance between the microvascular channels = 15.5 microm, r(vo), the initial radius of the extracellular space = 4.8 micro m, and L, the axial length of the Krogh cylinder = 19.1 microm), the interstitial volume ( approximately 23%), and the vascular volume ( approximately 7%) of the fibroid tumor tissue. A Boyle-van't Hoff plot was then constructed by examining freeze-substituted micrographs of "equilibrium"-cooled tissue slices to obtain the osmotically inactive cell volume, V(b) = 0.47V(o). The high interstitial volume precludes the use of freeze-substitution microscopy data to quantify freeze-induced dehydration. Therefore, a DSC technique, which does not suffer from this artifact, was used to obtain the water transport data. A model of water transport was fit to the calorimetric data at 5 and 20 degrees C/min to obtain the "combined best fit" membrane permeability parameters of the embedded fibroid tumor cells, assuming either a Krogh cylinder geometry, L(pg) = 0.92 x 10(-13) m(3)/Ns (0.55 microm/min atm) and E(Lp) = 129.3 kJ/mol (30.9 kcal/mol), or a spherical cell geometry (cell diameter = 18.3 microm), L(pg) = 0.45 x 10(-13) m(3)/Ns (0.27 microm/min atm) and E(Lp) = 110.5 kJ/mol (26.4 kcal/mol). In addition, numerical simulations were performed to generate conservative estimates, in the absence of ice nucleation between -5 and -30 degrees C, of intracellular ice volume in the tumor tissue at various cooling rates typical of those experienced during cryosurgery (< or =100 degrees C/min). With this assumption, the Krogh model simulations showed that the fibroid tumor tissue cells cooled at rates < or = 50 degrees C/min are essentially dehydrated; however, at rates >50 degrees C/min the amount of water trapped within the tissue cells increases rapidly with increasing cooling rate, suggesting the formation of intracellular ice.     

Liver freezing response of the freeze-tolerant wood frog, Rana sylvatica, in the presence and absence of glucose. I. Experimental measures.

In this study, two methods are used to assess the equilibrium and dynamic cell volumes in Rana sylvatica liver tissue during freezing in the presence and absence of a cryoprotectant (glucose). The first is a "two-step" low-temperature microscopy (equilibrium and dynamic) freezing method and the second is a differential scanning calorimeter (DSC) technique. These two techniques were used to study (i) the in vitro architecture of R. sylvatica frog liver tissue and to measure its characteristic Krogh cylinder dimensions; (ii) the "equilibrium" (infinitely slow) cooling behavior and the osmotically inactive cell volume (V(b)) of R. sylvatica liver cells; and (iii) the dynamic water transport response of R. sylvatica liver cells in the presence and absence of the CPA (glucose) at a cooling rate of 5 degrees C/min. Stereological analysis of the slam frozen (>1000 degrees C/min) micrographs led to the determination that 74% of the liver tissue in control frogs was cellular versus 26% that was extracellular (vascular or interstitial). Mapping the stereological measurements onto a standard Krogh cylinder geometry (Model 1) yielded distance between adjacent sinusoid centers, DeltaX = 64 microm; original sinusoid (vascular) radius, r(vo) = 18.4 microm; and length of the Krogh cylinder, L = 0.71 microm (based on an isolated frog hepatocyte cell diameter of 16 microm). A significant observation was that approximately 24% of the frog hepatocyte cells are not in direct contact with the vasculature. To account for the cell-cell contact in the frog liver architecture a modified Krogh cylinder geometry (Model 2) was constructed. In this model (Model 2) a second radius, r(2) = 28.7 microm, was defined (in addition to the original sinusoid radius, r(vo) = 18.4 microm, defined above) as the radius of the membrane between the adjacent cells (directly adjacent to vascular spaces) and embedded cells (removed from vascular spaces). By plotting the two-step equilibrium cooling results on a Boyle-van't Hoff plot, the osmotically inactive cell volume, V(b) was obtained as 0.4. V(o) (where V(o) is the isotonic cell volume). The two-step dynamic micrographs and the heat release measurements from the DSC were used to obtain water transport data during freezing. The DSC technique confirmed that R. sylvatica cells in control liver tissue do not dehydrate completely when cooled at 5 degrees C/min but do so when cooled at 2 degrees C/min.     

Kinetic studies of iron deposition in horse spleen ferritin using H2O2 and O2 as oxidants

The reaction of horse spleen ferritin (HoSF) with Fe2+ at pH 6.5 and 7.5 using O2, H2O2 and 1:1 a mixture of both showed that the iron deposition reaction using H2O2 is approximately 20- to 50-fold faster than the reaction with O2 alone. When H2O2 was added during the iron deposition reaction initiated with O2 as oxidant, Fe2+ was preferentially oxidized by H2O2, consistent with the above kinetic measurements. Both the O2 and H2O2 reactions were well defined from 15 to 40 degrees C from which activation parameters were determined. The iron deposition reaction was also studied using O2 as oxidant in the presence and absence of catalase using both stopped-flow and pumped-flow measurements. The presence of catalase decreased the rate of iron deposition by approximately 1.5-fold, and gave slightly smaller absorbance changes than in its absence. From the rate constants for the O2 (0.044 s(-1)) and H2O2 (0.67 s(-1)) iron-deposition reactions at pH 7.5, simulations of steady-state H2O2 concentrations were computed to be 0.45 microM. This low value and reported Fe2+/O2 values of 2.0-2.5 are consistent with H2O2 rapidly reacting by an alternate but unidentified pathway involving a system component such as the protein shell or the mineral core as previously postulated [Biochemistry 22 (1983) 876; Biochemistry 40 (2001) 10832].     

A series of spirocyclic analogues as potent inhibitors of bacterial phenylalanyl-tRNA synthetases

We have identified a series of spirocyclic furan and pyrrolidine inhibitors of Enterococcus faecalis and Staphylococcus aureus phenylalanyl-tRNA synthetases. The most potent analogue 1b showed IC50=5 nM (E. faecalis PheRS) and IC50=2 nM (S. aureus PheRS) with high selectivity over the human enzyme. The crystal X-ray structure of analogue 1b was determined.     

Genetic variation in the midcontinental population of sandhill cranes,Grus canadensis

Three subspecies of sandhill crane (Grus canadensis) are recognized in the Midcontinental population, the lesser (Grus c. canadensis), Canadian (G. c. rowani), and greater (G. c. tabida). Blood samples collected on the population's primary spring staging area in Nebraska, U.S.A., were used to resolve the genetic relationship among these subspecies. Phylogenetic analysis of 27 G. canadensis, by DNA sequencing of a 675 bp region of the mtDNA, supports the subspecies designations of G. c. canadensis and G. c. tabida. G. c. rowani individuals were intermediate with each of the other two subspecies. Genetic divergence ranged from 6.5 to 14.5% between G. c. canadensis and G. c. tabida, 0.5 to 6.6% within G. c. canadensis, and 0.1 to 6.0% within G. c. tabida. Sufficient DNA for analysis was obtained from shed feathers indicating a source of genetic material that does not require the capture or sacrifice of the birds. Other genetic markers and methods, including satellite telemetry, are required for obtaining detailed information on crane distributions as needed to establish effective management units for the MCP.