Cerebral metabolism in brains of rats infected with neuropathogenic murine leukemia viruses

Friend murine leukemia virus A8 and PVC211 cause spongiform neurodegeneration in rat brains. Glutamate is an important neurotransmitter synthesized from alpha-ketoglutaric acid, an intermediate product of the citric acid cycle, and glutamine is synthesized from glutamate. To examine the brain metabolism of rats infected with neuropathogenic viruses, the amount of glutamate and glutamine in the brains of rats infected with A8, PVC211, and non-neuropathogenic 57 was measured using high performance liquid chromatography, and the (13)C-label incorporation into the C4 position of glutamate and glutamine from [1-(13)C] glucose was measured with (13)C nuclear magnetic resonance. In the cerebral hemisphere and region containing the brain stem and basal ganglia of rats infected with A8 and PVC211 at 8-9 weeks post-infection (wpi), the amount of glutamine was decreased compared with the 57-infected rats. The amount of glutamate was decreased in the cerebral hemisphere of the A8-infected rats and the region containing the brain stem and basal ganglia of PVC211-infected rats at 8-9 wpi. The amount of [4-(13)C] glutamine and [4-(13)C] glutamate in the cerebral hemisphere and region containing the brain stem and basal ganglia of rats infected with A8 and PVC211 at 8-9 wpi was equivalent to that of the 57-infected rats. These results suggest that in the brains of rats infected with neuropathogenic viruses, de novo synthesis of glutamate and glutamine is not decreased, but the ability to maintain quantitative levels of glutamate and glutamine is decreased compared with the brains of rats infected with non-neuropathogenic virus.     

Mining the biodiversity of plants: a revolution in the making

Only a small fraction of the immense diversity of plant metabolism has been explored for the production of new medicines and other products important to human well-being. The availability of inexpensive high-throughput sequencing is rapidly expanding the number of species that can be investigated for the speedy discovery of previously unknown enzymes and pathways. Exploitation of these resources is being carried out through interdisciplinary synthetic and chemical biology to engineer pathways in plant and microbial systems for improving the production of existing medicines and to create libraries of biologically active products that can be screened for new drug applications.     

Effects of 17beta-estradiol on in vitro maturation of pig oocytes in protein-free medium

The present study examined the effects of 17 beta-estradiol (E(2)) on in vitro maturation and subsequent in vitro fertilization of pig oocytes matured with or without cumulus cells. When E(2) (10 ng/ml) was added to the protein-free maturation medium, the proportions of cumulus-enclosed oocytes that underwent germinal vesicle breakdown and reached metaphase II were significantly reduced (P<0.05), and cumulus expansion was also significantly inhibited (P<0.05) compared with the control (no E(2) added). Although oocytes matured in the presence of E(2) were penetrated by sperm in vitro at the same level as the control, the incidences of male pronuclear (MPN) formation and activated oocytes were significantly lower (P<0.05) than the control. These inhibitory effects of E(2) were prevented when the medium was supplemented with E(2) together with its antagonist, ICI 182,780 (1 microg/ml), although the presence of the antagonist alone in the medium had no effect on the maturation and fertilization in vitro of oocytes. In cumulus-free oocytes, E(2) had no effect on nuclear maturation and penetration in vitro, but low MPN formation was observed in oocytes matured in the presence and absence of E(2). When cumulus-enclosed oocytes were cultured in the presence of progesterone (P(4); 600 ng/ml) alone or together with E(2), no significant differences in nuclear maturation, cumulus expansion or penetration in vitro were observed compared with control oocytes. The concentration of P(4) in maturation medium was significantly (P<0.01) lower when cumulus-enclosed oocytes were cultured for 44 h in the medium with E(2) than in medium without E(2). These results indicate that E(2) inhibits both nuclear and cytoplasmic maturation of cumulus-enclosed pig oocytes, and that this inhibition can be prevented by an E(2) antagonist or P(4). This E(2) inhibition may occur indirectly via the cumulus cells and inhibition of P(4) synthesis.     

Nematocidal quassinoids and bicyclophosphorothionates: a possible common mode of action on the GABA receptor

The present study was undertaken to identify noncompetitive γ-aminobutyric acid receptor (GABAR) antagonists that are effective in nematodes, as well as to examine the hypothesis that the noncompetitive antagonism of the GABAR underlies the nematocidal activity of quassinoids against free-living nematodes of the Diplogastridae family. First, 14 known GABAR antagonists were screened for the effectiveness of their nematocidal activity in Diplogastridae. As a result, 3-isopropyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane 1-sulfides (3-isopropyl-BPTs) were found to have high nematocidal activities, and 4-cyclohexyl-3-isopropyl-BPT (23) and 3-isopropyl-4-(2-propenyl)-BPT (27) were the two most potent analogues; these compounds are equipotent to samaderine B and more potent than the anthelmintic abamectin. 23-resistant nematodes, selected by challenge with 23, showed cross-resistance to samaderine B. 23 (10 μM) reduced [³H]23 binding to nematode membranes by 30.4%. Samaderine B (10 μM) resulted in a similar level of the inhibition, but had neither additive nor synergistic effects on the 23 inhibition of [³H]23 binding. These findings suggest that samaderine B shares a common binding site with the GABAR antagonist 23 in Diplogastridae. The results of comparative molecular field analysis, a method of three-dimensional quantitative structure-activity relationship analysis, supported this conclusion.     

Reproduction of acute bracken poisoning in a calf with ptaquiloside, a bracken constituent

Acute bracken fern toxicity in a calf was reproduced with ptaquiloside, a norsesquiterpene glucoside, isolated from the boiling water extract of bracken fern. Ptaquiloside was dissolved in 500 ml of saline and administered by drench at increasing dosages for six days out of every seven for the following periods: 400 mg/day for 24 days, 800 mg/day for 14 days and 1600 mg/day for four days. Neutrophilic granulocytes began to decrease markedly around 50 days after the start of the experiment, and granulocytopenia continued for a further 35 days until the autopsy, despite the discontinuance of ptaquiloside administration. Thrombocytes showed a relatively slow depression and reached 1 X 10(5)/mm3 at the lowest level. The calf was autopsied 86 days after the start of administration of ptaquiloside. Sternal bone marrow was found to be mostly replaced with fat marrow and only small foci of erythropoietic cells and a small number of megakaryocytes remained.     

Successful mouse cloning of an outbred strain by trichostatin A treatment after somatic nuclear transfer

Although the somatic cloning technique has been used for numerous applications and basic research of reprogramming in various species, extremely low success rates have plagued this technique for a decade. Further in mice, the "clonable" strains have been limited to mainly hybrid F1 strains such as B6D2F1. Recently, we established a new efficient cloning technique using trichostatin A (TSA) which leads to a 2-5 fold increase in success rates for mouse cloning of B6D2F1 cumulus cells. To further test the validity of this TSA cloning technique, we tried to clone the adult ICR mouse, an outbred strain, which has never been directly cloned before. Only when TSA was used did we obtain both male and female cloned mice from cumulus and fibroblast cells of adult ICR mice with 4-5% success rates, which is comparable to 5-7% of B6D2F1. Thus, the TSA treatment is the first cloning technique to allow us to successfully clone outbred mice, demonstrating that this technique not only improves the success rates of cloning from hybrid strains, but also enables mouse cloning from normally "unclonable" strains.     

Evaluation of serum amyloid A and surfactant protein D in sera for identification of the clinical condition of horses with bacterial pneumonia

In the present study, the concentrations of serum amyloid A and surfactant protein D in sera were measured to evaluate them for identification of the clinical condition of horses with bacterial pneumonia. The study utilized 185 clinically healthy control thoroughbreds and 9 thoroughbreds for experimental infectious study with S. zooepidemicus. Blood samples were collected from the 185 healthy control thoroughbreds. The 9 thoroughbreds were experimentally infected S. zooepidemicus using an endoscopic injection to a lung lobe and were then observed of clinical conditions. Blood samples were collected before inoculation and on the 1-15th, 22nd, and 29th days after inoculation (follow-up group). The levels of SAA and SP-D in the healthy control thoroughbreds were very low. In the follow-up group, the levels of SAA and SP-D changed in parallel with the horses' clinical condition. The pyrexia observed after bacterial inoculation faded by the 11th day, and the changes in SAA and SP-D occurred simultaneous to disappearance of the clinical signs. Measurement of SAA and SP-D proved useful for monitoring the clinical condition of the horses with bacterial pneumonia. Changes in the SP-D value were preceded by changes in the SAA value. Since the changes in SP-D occurred approximately simultaneous to the changes in the horses' clinical signs, we believe that they reflect the condition of the alveolar membranes. We conclude that measurement of SAA and SP-D in sera is useful for identification of the clinical condition of horses with bacterial pneumonia.