Effect of murine strain on metabolic pathways of glucose production after brief or prolonged fasting

Background strain is known to influence the way a genetic manipulation affects mouse phenotypes. Despite data that demonstrate variations in the primary phenotype of basic inbred strains of mice, there is limited data available about specific metabolic fluxes in vivo that may be responsible for the differences in strain phenotypes. In this study, a simple stable isotope tracer/NMR spectroscopic protocol has been used to compare metabolic fluxes in ICR, FVB/N (FVB), C57BL/6J (B6), and 129S1/SvImJ (129) mouse strains. After a short-term fast in these mice, there were no detectable differences in the pathway fluxes that contribute to glucose synthesis. However, after a 24-h fast, B6 mice retain some residual glycogenolysis compared with other strains. FVB mice also had a 30% higher in vivo phosphoenolpyruvate carboxykinase flux and total glucose production from the level of the TCA cycle compared with B6 and 129 strains, while total body glucose production in the 129 strain was approximately 30% lower than in either FVB or B6 mice. These data indicate that there are inherent differences in several pathways involving glucose metabolism of inbred strains of mice that may contribute to a phenotype after genetic manipulation in these animals. The techniques used here are amenable to use as a secondary or tertiary tool for studying mouse models with disruptions of intermediary metabolism.     

Effects of prostaglandin on estrous cycles,behavior and blood progesterone levels of American Saddlebred mares

Twelve American Saddlebred mares ranging in weight from 365 to 450 kg were given intramuscular injections of 2.5, 5.0 and 7.5 mg of Prostaglandin (PGF_2α) on day 6 of diestrus a mean length of control estrus and diestrus were 6.5 ± .6, 16.9 ± 1.0 days, respectively. The 2.5, 5.0 and 7.5 mg PGF_2α doses significantly (P < .01) shortened the length of the treatment diestrus to 10.8 ± 1.8, 9.9 ± .7 and 9.9 ± .7, respectively. The 2.5 mg dose was 90% effective in shortening the duration of diestrus while doses of 5.0 and 7.5 mg were 100% effective. No effects were noted on the mean length of estrus or diestrus following treatment. Peripheral plasma progesterone concentrations were measured by radioimmunoassay to determine the luteolytic effect of PGF_2α. As compared to the non-treatment estrous cycles, all three treatments caused a significant (P < .01) decline in peripheral plasma progesterone concentrations 24 and 48 hr after treatment. The 2.5 mg PGF_2α dose caused a drop in progesterone from 7.7 ± .4 on day 6 to 2.6 ± 1.0 and 2.1 ± .9 ng/ml 24 and 48 hr later, respectively. Similarly, 5.0 mg lowered the progesterone level from 7.7 ± .3 to 1.6 ± .6 and 1.5 ± .5 ng/ml, and the 7.5 mg dose lowered the progesterone level 7.5 ± .3 to 1.2 ± .2 and 1.3 ± .3 PGF_2α. Abdominal cramps were noted in some mares after treatment. The incidence and severity of these reactions increased with the dose of PGF_2α.     

Overexpression of phosphoenolpyruvate carboxylase from Corynebacterium glutamicum lowers the CO2 compensation point (*) and enhances dark and light respiration in transgenic potato

The effect of decreased or increased phosphoenolpyruvate carboxylase (PEPC) activity on the CO2 compensation point, respiration in the light or dark as well as the partitioning of carbon into starch, soluble sugars, organic acids, and amino acids was investigated using transgenic potato plants. Engineered PEPC activity ranged form 0.5-fold wild-type level in antisense plants to 5-fold wild-type levels in lines overexpressing the ccpc gene of Corynebacterium glutamicum encoding for a PEPC not modulated by protein phosphorylation. The CO2 compensation point determined according to Brooks and Farquhar (1985) was lower in PEPC overexpressors (32 l l^-1 CO2) compared to control potato lines (38 l l^-1 CO2), but was increased in antisense PEPC plants (42 l^-1 CO2). 3-fold overexpression of PEPC gave a minimum CO2 compensation point of 32 l l^-1 CO2. Increased PEPC activity resulted in enhanced respiration in the light and dark. Altered PEPC activity had no effect on the pattern of ¹⁴CO2 incorporation into leaf discs in the light. ¹⁴C pulse-chase experiments in the dark, demonstrated that substantially more total label was lost in the leaf discs from PEPC overexpressors. Metabolite levels were determined in 21 PEPC overexpressing lines after 8 h in the light. A 5-fold increase in PEPC over the wild-type increased malate (61%), starch (75%) and significantly increased sucrose contents 9150%). Total amino acid contents were only marginally increased. From gas exchange characteristics and labeling experiments it was concluded that PEP carboxylation, followed by an increased rate of respiratory CO2 release, might work as a HCO3^-/CO2 pump. This might result in elevated CO2/O2 ratios in the mesophyll, concomitant with a more favoured carboxylation/oxygenation ratio of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco).     

Development of germ cell transplants: morphometric and ultrastructural studies.

Mouse-to-mouse transplants were studied at 10 min, 9 h, 24 h, 1 week, 1 month, 2 months, and 3 months post-transplantation. Data from a previous light microscope study were confirmed and extended using morphometric and ultrastructural techniques. As soon as 10 min after introduction of the germ cells from one mouse into the tubule lumen of a recipient mouse they developed relationships with small Sertoli cell processes. The extent of this surface-to-surface relationship increased in animals sacrificed up to 1 week post-transplantation. Most transplanted germ cells retained the characteristics of the donor germ cells after they had been isolated and pelleted. Nearly all transplanted cells eventually underwent phagocytosis by the recipient Sertoli cells. The presence of small apparent clones of germ cells after 1 week of transplantation indicated that some germ cells may divide and survive for short periods within the epithelium. No discernible qualitative subcellular changes in the host Sertoli cell accompanying the development of transplant spermatogenesis were noted. Macrophages were present in the region of the boundary tissue between myoid cells and appeared to increase in number in the peritubular tissue of transplanted testes. Images suggest that they migrated into the tubule to gain entrance to the lumen and there take on the form of activated macrophages. Some macrophages phagocytose sperm at 2 months and 3 months post-transplantation. A testis weight increase previously demonstrate to occur at 24 h post-introduction of germ cells was found to be due to an increase in the volume of the tubular lumen. The increase of lumen size at 24 h was not related to the volume of the injected material. It is suggested that the presence of injected cells, likely germ cells, in the tubule lumen stimulated increased secretion by the Sertoli cell.     

Neurotoxicological effects of a primary and ozonated treated wastewater on freshwater mussels exposed to an experimental flow-through system

The neurotoxic potential of a primary-treated and ozonated municipal effluent was examined using feral freshwater Elliptio complanata mussels. Specimens were exposed to increasing concentrations (0, 1, 3, 10 and 20% v/v) of a primary-treated effluent before and after treatment with 10 mg/L of ozone in a mesocosm-type experiment for 30 days. A suite of biomarkers was used to assess the potential neurotoxic stress of the wastewaters on these benthic invertebrates: opiate binding sites, gamma-aminobutyric acid (GABA) metabolism, monoamines levels (serotonin, dopamine), monoamine oxidase, acetylcholinesterase and lipid peroxidation. Gametogenic activity was also determined by the gonado-somatic index and by vitellogenin-like proteins. The results show that the number of opiate binding sites increased slightly, especially after ozonation. GABA metabolism was generally reduced, suggesting higher glutamate stimulation than GABA dampening effects in mussel ganglia. This excitatory state was further confirmed by decreased acetylcholinesterase activity in gonadal tissues. The turnover of dopamine was enhanced with increased serotonin levels, but accompanied by reduced catabolism, as evidenced by decreased monoamine oxidase activity. Moreover, oxidative stress was increased, as determined by lipid peroxidation in the gonad (containing ganglia), which was significantly correlated with acetylcholinesterase activity and dopamine metabolism. The gonado-somatic index was significantly reduced with increased levels of vitellogenin-like proteins, again confirming the estrogenic action of these wastewaters. The data suggest that exposure to a primary-treated municipal effluent before and after ozonation leads to an excitotoxic syndrome implicating perturbations in GABA, dopamine and acetylcholine signaling. The increase in dopamine metabolism may be associated with the occurrence of opiate-like compounds (i.e. morphine) in the effluent. In general, ozonation reduced the severity of the responses, indicating that this disinfection strategy does not increase neurotoxicity to mussels.     

Pharmacokinetics of 5-fluorouracil in patients heterozygous for the IVS14+1G > A mutation in the dihydropyrimidine dehydrogenase gene

5-Fluorouracil (5FU) and capecitabine are two of the most frequently prescribed chemotherapeutic drugs for the treatment of patients with cancer. Administration of test doses of 5FU to eight patients heterozygous for the IVS14+1G > A mutation and five control patients showed that the AUC and clearance were weak parameters with respect to the identification of patients with a DPD deficiency. However, highly significant differences were observed for the terminal half life of 5FU between DPD patients and controls. Thus, a DPD deficiency could be predicted from 5FU blood concentrations measured after the administration of a test dose of 5FU.     

Effects of ozone, ultraviolet and peracetic acid disinfection of a primary-treated municipal effluent on the immune system of rainbow trout (Oncorhynchus mykiss)

Municipal sewage effluents are complex mixtures that are known to compromise the health condition of aquatic organisms. The aim of this study was to evaluate the impacts of various wastewater disinfection processes on the immune system of juvenile rainbow trout (Oncorhynchus mykiss). The trout were exposed to a primary-treated effluent for 28 days before and after one of each of the following treatments: ultraviolet (UV) radiation, ozonation and peracetic acid. Immune function was characterized in leucocytes from the anterior head kidney by the following three parameters: phagocytosis activity, natural cytotoxic cells (NCC) function and lymphocyte (B and T) proliferation assays. The results show that the fish mass to length ratio was significantly decreased for the primary-treated and all three disinfection processes. Exposure to the primary-treated effluent led to a significant increase in macrophage-related phagocytosis; the addition of a disinfection step was effective in removing this effect. Both unstimulated and mitogen-stimulated T lymphocyte proliferation in fish decreased dramatically in fish exposed to the ozonated effluent compared to fish exposed to either the primary-treated effluent or to aquarium water. Stimulation of T lymphocytes proliferation was observed with the peracetic acid treatment group. In conclusion, the disinfection strategy used can modify the immune system in fish at the level of T lymphocyte proliferation but was effective to remove the effects on phagocytosis activity.