Contaminant assimilation within the water column of two newly created prairie wetlands

This research examined the influence of abiotic factors on contaminant assimilation within the water column of two wetlands (RMA3 and RMA4) located on Rocky Mountain Arsenal National Wildlife Area, north of Denver, Colorado, USA. We define contaminant assimilation as the ability of a wetland system to reduce negative impacts of contaminants on aquatic organisms. To examine the influence of abiotic factors (i.e., alkalinity, suspended solids), chronic toxicity tests were performed from February 1992 through November 1993. Ceriodaphnia dubia were exposed to water from the wetlands, which was spiked with Zn. These tests indicated higher assimilative capacity in wetland RMA4 relative to RMA3. Dissolved organic carbon (DOC) was significantly greater in RMA4 than in RMA3, suggesting that it may have influenced differences in bioavailability of Zn in wetland water. Suspended solids were also consistently higher in RMA4 than in RMA3. To test the influence of suspended solids on contaminant assimilation, C. dubia were exposed to filtered and unfiltered Zn-spiked water from RMA4. The greater toxicity of Zn to C. dubia in filtered water indicated that suspended solids were important in ameliorating impacts of Zn in RMA4. Results from this study suggest that from the suite of variables assessed, DOC and suspended solids were the most important physiochemical influences on Zn toxicity within the water column of these two wetlands. Differences in habitat characteristics of RMA3 and RMA4 demonstrated the importance of site-selection toward functional design of wetlands.     

Synthesis and characterization of phi-type zeolites LZ-276 and LZ-277: faulted members of the ABC-D6R family of zeolites

A new zeolite, LZ-276, was synthesized in an organic (TEAOH) system by varying the crystallization temperature in the procedure used by Jacobs and Martens for the synthesis of zeolite phi. LZ-276 (with SiO₂/Al₂O₃=7.8) is more siliceous than phi. Another silicon-rich zeolite, LZ-277 (SiO₂/Al₂O₃=6.6), was synthesized in a totally inorganic system. The similar chemical and physical properties of LZ-276 and LZ-277 are compared with those of zeolite phi described by Grose and Flanigen, and others. TEM [100] selected area diffraction patterns of LZ-277 can be indexed on a hexagonal unit cell with a=13.8 and c=15 Å. Twin spots and considerable streaking parallel to {00l} indicate mirror faulting along c. High resolution images on selected crystals of LZ-277 show that the most closely spaced mirror faults occur approximately every 18 Å. The bulk X-ray sample of LZ-276 is less faulted. A close match between the experimental synchrotron X-ray powder diffraction pattern of LZ-276 and one simulated by the DIFFaX program (with faulting probability=10%) indicates that the structures of these materials can be described as a chabazite (CHA) topology with faulting along c, the stacking direction in these ABC double six-ring (D6R) materials. The distribution of interior cages, including new larger cages that result from faulting, is presented.     

Creatine and cyclocreatine treatment of human colon adenocarcinoma xenografts: 31P and 1H magnetic resonance spectroscopic studies

Creatine (Cr) and cyclocreatine (cyCr) have been shown to inhibit the growth of a variety of human and murine tumours. The purpose of this study was to evaluate the anti-tumour effect of these molecules in relation to drug accumulation, energy metabolism, tumour water accumulation and toxicity. Nude mice carrying a human colon adenocarcinoma (LS174T) with a creatine kinase (CK) activity of 2.12 units mg(-1) protein were fed Cr (2.5% or 5%) or cyCr (0.025%, 0.1% or 0.5%) for 2 weeks and compared with controls fed standard diet. Cr concentrations of 2.5% and 5% significantly inhibited tumour growth, as did 0.1% and 0.5% cyCr. In vivo 31P magnetic resonance spectroscopy (MRS) after 2 weeks of treatment showed an increase in [phosphocreatine (PCr)+phosphocyclocreatine (PcyCr)]/nucleoside triphosphate (NTP) with increasing concentrations of dietary Cr and cyCr, without changes in absolute NTP contents. The antiproliferative effect of the substrates of CK was not related to energy deficiency but was associated with acidosis. Intratumoral substrate concentrations (measured by 1H-MRS) of 4.8 micromol g(-1) wet weight Cr (mice fed 2.5% Cr) and 6.2 micromol g(-1) cyCr (mice fed 0.1% cyCr) induced a similar decrease in growth rate, indicating that both substrates were equally potent in tumour growth inhibition. The best correlant of growth inhibition was the total Cr or (cyCr+Cr) concentrations in the tissue. In vivo, these agents did not induce excessive water accumulation and had no systemic effects on the mice (weight loss, hypoglycaemia) that may have caused growth inhibition.     

Inhibition of hepatic inositol 1,4,5-trisphosphate receptor function by ethanol and other short chain alcohols

OBJECTIVE: To formulate the fundamental structure of caring as lived by Critical Care Nurses. DESIGN: Colaizzi's phenomenological research method and Diekelmann's dialogue technique were applied. SETTING: The home of each nurse constituted the setting for the interview. The nurses were employed in critical care units in six large metropolitan hospitals in the Southwest. SAMPLE: The availability sample consisted of 15 female critical care registered nurses. The nurses' mean age was 35 years. The mean number of years in critical care nursing was 4.7. One nurse was Asian, one was Hispanic, and 13 were Caucasian. RESULTS: Caring was composed of affective, cognitive, action, and outcome subprocesses. The caring process originated in the nurse's feelings and knowledge, and moved the nurse to competent actions that contributed to patient, family, and nurse outcomes. CONCLUSIONS: Understanding of the process of caring was strengthened by the findings. The decision process used by nurses would benefit from further examination for the presence of the affective and nurse outcome subprocesses.     

Isoenzyme analysis of Arthrobotrys, a nematode-trapping fungus

Extraction and isoenzyme analysis of four isolates of Arthrobotrys including A. musiformis, A. robusta and A. conoides were conducted. Among the 14 enzymes studied by starch gel electrophoresis, using morpholine-citrate as gel/electrode buffer, the following nine enzymes showed interpretable banding patterns: alpha-esterase, fumarase, hexokinase, isocitrate dehydrogenase, leucine aminopeptidase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase and phosphoglucoisomerase. All isolates studied displayed typical isoenzyme phenotypes for each species. Two isolates of A. conoides differed in their alpha-isoesterase banding patterns, but no differences were observed for the other enzymes. The assay was satisfactory for enzyme extraction and resolution of Arthrobotrys and could be used in future taxonomic and genetic studies of this organism.