Anticoagulant low molecular weight heparin does not enhance the activation of plasminogen by tissue plasminogen activator

The activity of tissue plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) is stimulated by heparin. Heparin binds tightly to t-PA, u-PA, and plasminogen and decreases the usual stimulatory effect of fibrin on t-PA activity. In the present study we have found that low molecular weight heparin (LMW-heparin) preparations obtained by nitrous acid depolymerization or heparinase treatment of standard heparin have different properties with respect to their interaction with the fibrinolytic system. LMW-heparin prepared by either method does not stimulate plasmin formation by t-PA. However, these preparations of heparin still efficiently accelerate the inhibition of thrombin by antithrombin III. Binding data show that LMW-heparin does not bind t-PA and Glu-plasminogen and only binds very weakly to Lys-plasminogen. These results illustrate that it is possible to selectively destroy the fibrinolytic stimulating properties of heparin while leaving the classical anticoagulant characteristics intact.     

Sylvatic trichinosis in Ontario, Canada

Samples of muscle from 4,773 specimens of 18 species of wild mammals from Ontario were examined for Trichinella. One of 12 mink (Mustela vison), 83 of 1,821 fisher (Martes pennanti) and 68 of 1,980 marten (Martes americana) had T. spiralis. Prevalences of infections by Trichinella were determined for fisher and marten from the Algonquin region, over a 10-yr period. Prevalences ranged from 0.9-9.2% in fisher and 1.3-8.7% in marten indicating that the parasite is well-established in the region. Prevalences of Trichinella increased with age of both fisher and marten. Intensities determined for the 1981-1982 sample ranged from 0.4-15.8 larvae/g for fisher and 22.4-159.7 larvae/g for marten. Higher intensities were not correlated with older hosts. Fisher and marten appeared to be the key hosts maintaining Trichinella in the Algonquin region, but transmission dynamics were unclear. Transmission may include an unidentified small rodent or other host and natural carrion-feeding.     

Ovarian plasminogen activator: relationship to ovulation and hormonal regulation.

A technique is described for detecting fibrinolytic activity of single cells in culture. This method was applied to the analysis of rat ovarian granulosa cells. Cells obtained from follicules shortly before ovulation show high levels of fibrinolytic activity. This activity is plasminogen-dependent, indicating that it is due to plasminogen activator. The appearance of this activity is correlated with ovulation by temporal and functional criteria, and can be demonstrated both in immature animals primed with hormones and in mature cycling animals. Granulosa cell cultures can be stimulated to release plasminogen activator by exposure in vitro either to luteinizing hormone or to dibutyryl cyclic AMP.     

Genetic Characteristics of Restored Elk Populations in Kentucky

Translocations are a common management practice to restore or augment populations. Understanding the genetic consequences of translocation efforts is important for the long-term health of restored populations. The restoration of elk (Cervus canadensis) to Kentucky, USA, included source stocks from 6 western states, which were released at 8 sites in southeastern Kentucky during 1997–2002. We assessed genetic diversity in restored herds and compared genetic similarity to source stocks based on 15 microsatellite DNA loci. Genetic variation in the restored populations was comparable to source stocks ( allelic richness = 3.52 and 3.50; expected heterozygosity = 0.665 and 0.661 for restored and source, respectively). Genetic differentiation among all source and restored populations ranged from 0.000 to 0.065 for pairwise F_ST and 0.034 to 0.161 for pairwise Nei's D_A. Pairwise genetic differentiation and Bayesian clustering revealed that stocks from Utah and North Dakota, USA, contributed most to restored populations. Other western stocks appeared less successful and were not detected with our data, though our sampling was not exhaustive. We also inferred natural movements of elk among release sites by the presence of multiple genetic stocks. The success of the elk restoration effort in Kentucky may be due, in part, to the large number of elk (n = 1,548), repeated releases, and use of diverse source stocks. Future restoration efforts for elk in the eastern United States should consider the use of multiple stock sources and a large number of individuals. In addition, preservation of genetic samples of founder stock will enable detailed monitoring in the future. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Serum Gastrin in Chronic Gastritis

Fasting gastrin levels in serum were measured in 49 patients with different types of chronic gastritis and in matched controls. In 15 patients with established pernicious anaemia the mean (± S.E. of mean) level of gastrin was greatly raised (699 ± 99 pg/ml). In 17 patients with chronic atrophic gastritis, seropositive for parietal cell antibody but with adequate vitamin-B₁₂ absorption, the level was also raised (476 ± 74 pg/ml). By contrast, in “simple” atrophic gastritis seronegative for parietal cell antibody the gastrin levels were significantly lower for both diffuse atrophic gastritis (129 ± 31 pg/ml) and multifocal gastritis (14 ± 4 pg/ml). These levels were similar to those in the controls (46 ± 7 pg/ml).The mechanism of the raised gastrin levels remains uncertain, but neither achlorhydria nor in vivo action of the parietal cell antibody wholly accounted for the hypergastrinaemia.We conclude that hypergastrinaemia is characteristic of gastritis associated with autoimmune reactions to gastric antigens and pernicious anaemia and that a raised serum gastrin is a useful marker of the type of gastritis that tends to progress to the gastric lesion of pernicious anaemia. The findings suggest that this type of gastritis is an essentially different disease from “simple” atrophic gastritis, and the differences in gastrin levels may be due to sparing of the antral mucosa in the autoimmune type but not in “simple” gastritis.     

HETEROTROPHY OF FOUR MARINE PHYTOPLANKTERS AT LOW SUBSTRATE CONCENTRATIONS1

Three pelagic marine phytoplankters, Coccolithus huxleyi, Skeletonema costatum, and Thalassiosira ro-tula, and a facultative heterotroph, Cyclotella cryp-tica, have been exposed to three organic substrates, viz, glucose, acetate, and glutamate, at low concentrations (organic carbon 0.25 mg/liter). Experiments were performed in the dark and light and the net assimilation of substrate was measured by using radiocarbon. The dark uptake of carbon dioxide was also determined, together with photosynthesis at near optimum light intensity. The expected heterotrophy was detected with Cyclotella cryptica. Thalassiosira rotula was found to assimilate glutamate at an appreciable rate. In all cases, however, the short-term uptake of carbon dioxide in the dark was the greatest assimilation rate measured. Values are discussed in relation to their ecological significance and it is concluded that heterotrophic survival of these and probably most other algae in the open ocean xuould be impossible unless they were in contact with a high concentration of substrate in the form of particulate matter.     

Dissociation of mRNA cytoplasmic polyadenylation from translational activation by structural modification of the 5'-UTR.

During early metazoan development, certain maternal mRNAs are translationally activated by elongation of their poly(A) tails. Bicoid ( bcd ) mRNA is a Drosophila maternal mRNA that is translationally activated by cytoplasmic polyadenylation during the first hour after egg deposition. The sequences necessary and sufficient to promote its poly(A) elongation, and hence translation, are contained within its 3'-untranslated region (UTR). The mechanism by which poly(A) elongation at the 3'-end affects translational initiation at the 5'-end remains unknown. To investigate this question, we have analyzed a bicoid mRNA whose 5'-UTR contains a short antisense sequence directed against a portion of the coding region. This mutated RNA is efficiently translated in vitro. After injection into Drosophila embryos, this RNA is stable and polyadenylated, but inefficiently translated. These experiments show that structural modification of the 5'-end of an mRNA can perturb the translational activation normally conferred by polyadenylation in vivo.