The uptake of oxalate by rat liver and kidney mitochondria

Oxalate, a metabolic end product, forms calcium oxalate deposits in the tissues under a variety of pathological conditions. In order to determine whether oxalate is able to penetrate the mitochondrial matrix, the uptake of oxalate by rat liver and kidney cortical mitochondria was characterized. Mitochondria did not swell in an iso-osmotic medium of ammonium oxalate unless a small amount of phosphate was provided. This phosphate-induced swelling was prevented by N-ethylmaleimide. The uptake of [14C]oxalate by liver and kidney mitochondria followed first order kinetics and was inhibited by mersalyl an inhibitor of the phosphate and dicarboxylate carriers. Accumulation of [14C]oxalate at equilibrium was significantly higher by mitochondria energized with succinate than by rotenone-inhibited mitochondria due to higher matrix pH as determined by the [14C]5,5'-dimethyloxazolidine-2, 4-dione distribution ratio. The velocity of oxalate accumulation by mitochondria was temperature dependent. The activation energy was 81.5 and 86.5 J/mol for liver and kidney mitochondria, respectively. In both types of mitochondria, the rate of oxalate uptake was hyperbolic with respect to the concentration of oxalate. The apparent Km was 28.8 +/- 0.6 and 13.4 +/- 1.2 mM and the Vmax 87.1 +/- 1.1 and 66.1 +/- 3.1 nmol X mg-1 X min-1 at 12 degrees C for liver and kidney mitochondria, respectively. Phenylsuccinate exhibited mixed inhibition of the rate of oxalate uptake. Oxalate exhibited also a mixed inhibition of the uptake and oxidation of malate by mitochondria. The data obtained provide evidence that oxalate is transported across the mitochondrial membrane by a phosphate-linked, carrier-mediated system similar to or identical to the dicarboxylate transporter.     

Decapod Crustacea from the International Indian Ocean Expedition The species of Thalassocaris (Caridea) and their larvae

Plankton collections from the Indian Ocean contain adults and larvae of three species of Thalassocaris: T. lucida (Dana), T. crinita (Dana) and T. obscura sp.n. The new species was previously confused with T. crinita by Borradaile and with T. lucida by Kemp.
Larvae of Thalassocaris are described for the first time. In each species there are 10–13 zoeal stages. The cephalothorax is very broad and shallow, the maxilla has only one coxal endite, and exopods develop on legs 1–4.
T. crinita is a shallow-water species with a wide distribution in the Indian Ocean and western Pacific. T. lucida and T. obscura are open ocean species. T. lucida is most common in the eastern Indian Ocean (and probably in the western Pacific) and is not recorded from the Arabian Sea. T. obscura is most common in the Arabian Sea and is not recorded from the south-eastern Indian Ocean or from the Pacific.
Larval characters do not support the inclusion of Thalassocaris in the Pandalidae. Recognition of the family Thalassocarididae, comprising the genera Thalassocaris and Chlorosocoides, is advocated.     

NMR simulation analysis of statistical effects on quantifying cerebrovascular parameters

Determining tissue structure and composition from the behavior of the NMR transverse relaxation during free induction decay and spin echo formation has seen significant advances in recent years. In particular, the ability to quantify cerebrovascular network parameters such as blood volume and deoxyhemoglobin concentration from the NMR signal dephasing has seen intense focus. Analytical models have been described, based on statistical averaging of randomly oriented cylinders in both the static and slow diffusion regimes. However, the error in estimates obtained from these models when applied to systems in which the statistical assumptions of many, randomly oriented perturbers are violated has not been systematically investigated. Using a deterministic simulation that can include diffusion, we find that the error in estimated venous blood volume fraction and deoxyhemoglobin concentration obtained using a static dephasing regime statistical model is inversely related to the square root of number of blood vessels. The most important implication of this is that the minimum imaging resolution for accurate deoxyhemoglobin and blood volume estimation is not bound by hardware limitations, but rather by the underlying tissue structure.     

A basal membrane-like structure surrounding tumour nodules may prevent intraepithelial leucocyte infiltration in colorectal cancer

Epithelial tumours consist of an epithelial compartment and a stromal compartment, which are sometimes separated by a basal membrane-like structure. We sought to determine whether these factors have prognostic value in 84 curatively resected stage II and III colorectal cancer by immunohistochemically staining tumours for leucocytes (CD45) and extracellular matrix, and to assess the presence of a basal membrane-like structure. Leucocyte infiltration was also assessed in hematoxylin-eosin (HE) stained sections. Most leucocytes were located in the tumour stroma. A relatively high intraepithelial leucocyte infiltration was significantly correlated with a lower level of tumour recurrence (P=0.03) and a longer disease-free survival (P=0.05), whereas leucocytes located in the tumour stroma (P=0.92) or at the advancing margin (p=0.06) were not. Intraepithelial leucocyte infiltration was also significantly correlated with leucocyte infiltration in the tumour stroma (P=0.02) and at the advancing tumour margin (P=0.005), and as assessed in HE-stained tumour sections (P=0.05), but each of these parameters on its own did not have a prognostic value in predicting disease-free survival. Moreover, the presence of a basal membrane-like structure surrounding the tumour epithelium was inversely correlated with the number of intraepithelial leucocytes (P=0.05), suggesting that this membrane-like structure functions as a barrier to intraepithelial leucocyte infiltration. We conclude that leucocytes must be in the direct vicinity of tumour cells to affect tumour growth. The presence of an extracellular matrix barrier seems to prevent this interaction.     

Mitochondrial signatures revealed panmixia in <Emphasis Type="Italic">Lutjanus argentimaculatus</Emphasis> (Forsskål 1775)

Mangrove red snapper, Lutjanus argentimaculatus is a commercially important fish. The genetic stock structure of L. argentimaculatus from Indian waters was identified using mitochondrial ATPase 6 and ATPase 8, and cytochrome b (Cytb) genes. A 842 bp region of ATPase 6/8 genes and 1105 bp region of Cytb gene were amplified in 120 samples from six different locations along the Indian coast and obtained 58 and 66 haplotypes, respectively. The high haplotype and low nucleotide diversity values along with mismatch distribution, Tajima’s D and Fu’s \(F_\mathrm{s}\) analysis suggested a genetic bottleneck events or founder effect, with subsequent population expansion in L. argentimaculatus. Coefficient of genetic differentiation \((F_\mathrm{ST})\) values was low and nonsignificant for both ATPase 6/8 gene and Cytb genes indicating low genetic differentiation in L. argentimaculatus which can be managed as a unit stock in Indian waters.     

A MIV-150/Zinc Acetate Gel Inhibits SHIV-RT Infection in Macaque Vaginal Explants

To extend our observations that single or repeated application of a gel containing the NNRTI MIV-150 (M) and zinc acetate dihydrate (ZA) in carrageenan (CG) (MZC) inhibits vaginal transmission of simian/human immunodeficiency virus (SHIV)-RT in macaques, we evaluated safety and anti-SHIV-RT activity of MZC and related gel formulations ex vivo in macaque mucosal explants. In addition, safety was further evaluated in human ectocervical explants. The gels did not induce mucosal toxicity. A single ex vivo exposure to diluted MZC (1∶30, 1∶100) and MC (1∶30, the only dilution tested), but not to ZC gel, up to 4 days prior to viral challenge, significantly inhibited SHIV-RT infection in macaque vaginal mucosa. MZC''s activity was not affected by seminal plasma. The antiviral activity of unformulated MIV-150 was not enhanced in the presence of ZA, suggesting that the antiviral activity of MZC was mediated predominantly by MIV-150. In vivo administration of MZC and CG significantly inhibited ex vivo SHIV-RT infection (51–62% inhibition relative to baselines) of vaginal (but not cervical) mucosa collected 24 h post last gel exposure, indicating barrier effect of CG. Although the inhibitory effect of MZC (65–74%) did not significantly differ from CG (32–45%), it was within the range of protection (∼75%) against vaginal SHIV-RT challenge 24 h after gel dosing. Overall, the data suggest that evaluation of candidate microbicides in macaque explants can inform macaque efficacy and clinical studies design. The data support advancing MZC gel for clinical evaluation.