Abstract    Kathy Calvo, Chemical Control Division (7405M), Office of Pollution Prevention and Toxics, Environmental Protection Agency, 1200 Pennsylvania Ave. NW., Washington, DC 20460-0001; telephone number: (202) 564-8089; email address: calvo.kathy@epa.gov. The docket for this Federal Register document and the docket for each related TSCA section 4 test rule is available electronically at http://www.regulations.gov or in person at the Office of Pollution Prevention and Toxics Docket (OPPT Docket), Environmental Protection Agency Docket Center (EPA/DC), West William Jefferson Clinton Bldg., Rm. 3334, 1301 Constitution Ave. NW., Washington, DC.

Abstract  The purpose of this study was to investigate the influence of chronic calcium treatment on the structure and function of thyroid C cells in ovariectomzed adult female rats. Eighteen 3-month-old, female Wistar rats were divided into three groups. The first group was used as the sham-operated control, and the other two were surgically ovariectomized (Ovx). One month after gonadectomy, one group of Ovx rats was injected with 28.55 mg Ca-glucoheptonate (Ca)/kg b.w., while the other two groups were chronically treated with vehicle alone (Ovx and sham control). Two months after surgery, the animals were killed. In the thyroid C cells, calcitonin (CT) was localized with the peroxidase-antiperoxidase method. Stereology was used to evaluate morphometric changes in the volume of C cells, their nuclei and relative volume density. The number of C cells per unit area was calculated. Serum CT content was determined by radioimmunoassay. After chronic Ca treatment C cells were numerous with darker cytoplasm than in C cells of sham-operated control animals, but more degranulated than the corresponding cells of Ovx rats. Their volume was significantly decreased by 14% (p < 0.05), while the number was increased by 47% (p < 0.05) in comparison with corresponding controls. Serum CT concentration was decreased by 27% (n.s.) in comparison to sham-operated control. Calcium treatment of Ovx rats led to a 32% increase of serum CT concentration in relation to untreated Ovx animals. These results suggest that chronic Ca treatment of Ovx female rats positively affected CT release from thyroid C cells, without any significant changes in morphometric parameters.

Abstract  The effects of multiple treatment with estradiol dipropionate (EDP) or calcium glucoheptonate (Ca) or a combination of the two on gonadotrophic cells in the pituitary pars distalis of middle-aged female rats were examined. The animals were treated daily for two weeks with EDP (0.625 mg i.p./kg body weight) or Ca (11.4 mg/kg body weight) or EDP + Ca. Luteinising (LH) and follicle stimulating hormone (FSH)-producing cells were examined by immunohistochemistry using antisera to the specific (beta) beta-subunits of LH and FSH and a peroxidase-anti-peroxidase immunohistochemical procedure. Plasma levels of FSH and LH were measured by radio-immune assay. A stereological method for determining morphometric parameters in immunopositive FSH and LH cells was used. The number of gonadotrophs per unit area (mm2), their cellular volume and relative volume densities, as well as plasma levels of FSH and LH, were decreased in all treated females in comparison with the controls. The most significant decrease of these parameters was observed in EDP-treated animals. Such changes were also expressed in Ca-treated animals, but the alterations were less distinct. These results demonstrate that multiple EDP or Ca application to middle-aged female rats is able to inhibit, directly or indirectly, the morphofunctional state of gonadotrophic cells in the pituitary pars distalis.

Abstract  Calcium chloride and calcium gluceptate were compared in their ability to increase plasma ionized calcium concentrations ([Ca2+]). To correct a low ionized calcium concentration, each of 10 critically ml of a 10% solution, containing elemental calcium 27 mg ml-1) and calcium gluceptate (20 ml, containing elemental calcium 18 mg ml-1) over a 5-min period in randomized order approximately 6 h apart. [Ca2+] and haemodynamic variables (mean arterial pressure (MAP), mean right atrial pressure (RAP) and heart rate (HR)) were monitored for a 30-min period following completion of calcium infusion. Infusion of either calcium preparation was associated with similar increases in [Ca2+] (5 min after infusion of calcium chloride: 33 +/- 3.1%; calcium gluceptate: 32 +/- 4.3% (mean +/- SEM)) and the effects on MAP were similar for each solution (11.1 +/- 1.8% and 9.7 +/- 2.4%, respectively).

Abstract  Introduction: A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata. The method followed that described in the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 761/2009 and the US EPA Draft Ecological Effects Test Guideline OPPTS 850.5400. Methods: Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to an aqueous solution of the test item at concentrations of 10, 32, 100, 320 and 1000 mg active ingredient (ai)/L (three replicate flasks per concentration) for 96 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter Multisizer Particle Counter. Results: Exposure of Pseudokirchneriella subcapitata to the test item gave the following results: *See results chart in PDF download* Analysis of the test preparations at 0 and 96 hours showed measured test concentrations to range from 93% to 105% of nominal and so the results are based on nominal test concentrations only. A re-growth test was performed which showed the test item to be algistatic in effect.