Adenovirus early gene products may control viral mRNA accumulation and translation in vivo

The mechanisms controlling early adenovirus gene expression in vivo have been studied using inhibitors of protein synthesis. When inhibitors were added shortly before or at the onset of infection, viral mRNA from all early regions was transcribed, spliced and accumulated over a 7 hr period. After longer pretreatment, accumulation of several early mRNAs were suppressed. Addition of inhibitors 1 hr after infection enhanced the accumulation of viral mRNA in the cytoplasm. Translation of early mRNA selected on adenovirus DNA in a cell-free system reflected the amount of viral mRNA present. A viral coded product may therefore control accumulation of viral mRNA.A different pattern emerged when inhibitors of protein synthesis were removed at 5 hr postinfection and cells were pulse-labeled in vivo. If inhibitors were introduced at or before infection, early viral proteins were synthesized only after a lag of 1–3 hr. However, if treatment was introduced 1 hr post-infection, reversion of the protein synthesis block was instantaneous. It appears that protein synthesis inhibitors reveal an in vivo translational block for viral mRNA. This block could be overcome by preinfection with a related virus. Furthermore, no block was observed in a virus-transformed human embryonic kidney cell line (293) which expresses early region 1 of the viral genome. Viral gene product(s) encoded in early region 1 may control translation of early adenovirus messenger RNA in vivo.     

Human P301L-Mutant Tau Expression in Mouse Entorhinal-Hippocampal Network Causes Tau Aggregation and Presynaptic Pathology but No Cognitive Deficits

Accumulation of hyperphosphorylated tau in the entorhinal cortex (EC) is one of the earliest pathological hallmarks in patients with Alzheimer’s disease (AD). It can occur before significant Aβ deposition and appears to “spread” into anatomically connected brain regions. To determine whether this early-stage pathology is sufficient to cause disease progression and cognitive decline in experimental models, we overexpressed mutant human tau (hTauP301L) predominantly in layer II/III neurons of the mouse EC. Cognitive functions remained normal in mice at 4, 8, 12 and 16 months of age, despite early and extensive tau accumulation in the EC. Perforant path (PP) axon terminals within the dentate gyrus (DG) contained abnormal conformations of tau even in young EC-hTau mice, and phosphorylated tau increased with age in both the EC and PP. In old mice, ultrastructural alterations in presynaptic terminals were observed at PP-to-granule cell synapses. Phosphorylated tau was more abundant in presynaptic than postsynaptic elements. Human and pathological tau was also detected within hippocampal neurons of this mouse model. Thus, hTauP301L accumulation predominantly in the EC and related presynaptic pathology in hippocampal circuits was not sufficient to cause robust cognitive deficits within the age range analyzed here.     

In situ generation of iminodiacetic acid groups on nanoporous alumina for the reversible immobilization of enzymes and other biomolecules

Nanoporous alumina membranes were silanized with aminopropylsilane and iminodiacetic acid (IDA) groups were generated in situ by reaction with iodoacetate. The membranes were mounted in standard filter holders, connected to a HPLC system and saturated with selected metal ions. Cu(II) allowed the capture of chicken muscle lactate dehydrogenase with such stability, repeatability and reproducibility that Michaelis–Menten kinetics could be studied. The IDA surface was stable for months and could be depleted and regenerated with metal ions multiple times without appreciable loss of capacity. The binding of lactate dehydrogenase influenced the backpressure to the extent that could be expected for a monolayer according to Poiseuilles law.     

Competition-induced switch in young of the year perch,Perca fluviatilis: an experimental test of resource limitation

Synopis Reproductively developed male fathead minnows, Pimephales promelas, exhibited courtship behaviour in the presence of female conspecifies under laboratory conditions. Male courtship consisted of several distinctive and visually conspicuous behaviours directed toward females, including approach, display, and two contact behaviours, as well as leading behaviour from the female to a suitable spawning site. An ovulated condition in females was not necessary to generate male courtship behaviour; in fact, the amount of courtship exhibited by males may depend inversely on the readiness of females to spawn.     

Induction of rat liver glutathione transferase isoenzyme 7-7 by lead nitrate

The glutathione transferase (GST) activity of rat liver cytosolic preparations with ethacrynic acid (EA) and (±)-7β,8α-dihydroxy-9α, 10α-epoxy-7,8,9,10-tetrahydro-benzo(a)pyrene (BPDE) as substrates, increased by 125 and 350%, respectively, in animals that had been treated with a single intravenous dose of Pb(NO₃)₂ (100 μmol/kg body wt) 48 h prior to sacrifice, whereas activity with 1-chloro-2,4-dinitro-benzene (CDNB) increased only about 60%. No induction of these activities was observed in cytosolic preparations from regenerating rat liver, whereas cytosols prepared from hepatocyte nodules showed increased activity with all three substrates (EA: 400%; BPDE: 790%; CDNB: 205%). These results suggest that Pb(NO₃)₂ is an inducer of GST 7-7, an isoenzyme that has been associated with hepatocarcinogenesis. Elucidation of the mechanism of GST 7-7 induction by lead may contribute to our understanding of the process of chemical carcinogenesis.     

Monoclonal antibodies to the pituitary growth-hormone receptor by the anti-idiotypic approach. Production and initial characterization.

We obtained 10/192 and 3/384 antibody-secreting hybrids after immunization of Balb/c mice with either human growth hormone or affinity-purified rabbit anti-(human growth hormone) respectively. Radiolabelled rabbit anti-(human growth hormone) antibodies, but not human growth hormone, were specifically bound by supernatants from the 13 hybrids. The binding was completely inhibited by human-growth-hormone serum binding protein. However, anti-(human growth hormone antibodies) were detected in the sera of all the mice immunized with human growth hormone. In an independent fusion, which was carried out after immunization with fewer doses of human growth hormone, anti-(human growth hormone) antibodies were also obtained. Five hybrids, where the starting antigen was human growth hormone, were selected for ascites production, and the corresponding monoclonal antibodies were partially purified and characterized with respect to their immunoglobulin isotype and their interaction with human-growth-hormone receptors. These antibodies were found to enhance the binding of radioiodinated human growth hormone to human-growth-hormone serum binding protein from human and rabbit plasma by 40%. Scatchard analysis of the effect of one of the monoclonal antibodies showed that this enhancement was due to an increased number of binding sites. All of the partially purified antibodies but one (F12) inhibited the binding of human growth hormone to rat but not rabbit, liver microsomes to various extents, as well as to H-4-II-E rat hepatoma cells. Monoclonal antibody F12 enhanced the binding of radiolabelled human growth hormone to rat liver microsomes and H-4-II-E hepatoma cells. This enhancement was found to be due to an increase in the number of binding sites.     

Leukaemia and transient leukaemia in Down syndrome

Summary We have reviewed 215 published cases of leukaemia and transient leukaemia in Down syndrome. There is an over-representation of mosaic trisomy 21, possibly the result, at least in part, of a survival effect. The most intriguing observation is a bimodal distribution of maternal age, produced largely because cases with true leukaemia have a significantly higher maternal age than cases with transient leukaemia (33.5 versus 29.5 years). In conjunction with evidence that meiosis I non-disjunction is infrequent in transient leukaemia, this suggests different mechanisms for the etiology of leukaemia and transient leukaemia, and favours a locus predisposing to transient leukaemia proximal to the centromere on the long arm of chromosome 21.     

Effects of training at simulated altitude on performance and muscle metabolic capacity in competitive road cyclists

Differences between the effects of training at sea level and at simulated altitude on performance and muscle structural and biochemical properties were investigated in 8 competitive cyclists who trained for 3-4 weeks, 4-5 sessions/week, each session consisting of cycling for 60-90 min continuously and 45-60 min intermittently. Four subjects, the altitude group (AG), trained in a hypobaric chamber (574 torr = 2300 m above sea level), and the other four at sea level (SLG). Before and after training work capacity was tested both at simulated altitude (574 torr) and at sea level, by an incremental cycle ergometer test until exhaustion. Work capacity was expressed as total amount of work performed. Venous blood samples were taken during the tests. Leg muscle biopsies were taken at rest before and after the training period. AG exhibited an increase of 33% in both sea level and altitude performance, while SLG increased 22% at sea level and 14% at altitude. Blood lactate concentration at a given submaximal load at altitude was significantly more reduced by training in AG than SLG. Muscle phosphofructokinase (PFK) activity decreased with training in AG but increased in SLG. All AG subjects showed increases in capillary density. In conclusion, work capacity at altitude was increased more by training at altitude than at sea level. Work capacity at sea level was at least as much improved by altitude as by sea level training. The improved work capacity by training at altitude was paralleled by decreased exercise blood lactate concentration, increased capillarization and decreased glycolytic capacity in leg muscle.     

Tachykinin release from rat spinal cord in vitro and in vivo in response to various stimuli

The aim of the present study was to establish an experimental model, previously used in cat, for studying tachykinin release from the rat spinal cord in vivo and to compare the results with those obtained in vitro. Stimulation with pulses of 40 mM potassium or 10 microM capsaicin in the spinal cord superfusion fluid increased the release of substance P (SP)- and neurokinin A (NKA)-like immunoreactivity (LI) both in vivo and in vitro. The amounts of SP-LI and NKA-LI released by potassium in vitro were 1.02 +/- 0.12 and 1.17 +/- 0.22 fmol/mg tissue, respectively. Also the ratio between the amounts released by two consecutive potassium stimulations were similar for SP-LI and NKA-LI. Reversed-phase high performance liquid chromatography of the NKA-LI released in vitro by potassium or capsaicin revealed a major immunoreactive component coeluting with synthetic NKA. Despite the use of highly sensitive radioimmunoassays, basal release of SP-LI and NKA-LI was found only in 9 of 31 in vivo experiments. In these, peripheral electrical stimulation of the sciatic nerves (50 Hz, 50 V and 0.05 ms or 10 Hz, 10 V and 5 ms) induced an increase of the SP-LI and NKA-LI levels in the superfusates. This increase persisted for more than 40 min after a 2 min stimulation. In most experiments, however, no SP-LI or NKA-LI could be detected in the superfusates, neither at basal conditions nor following electrical nerve stimulation. Similarly, no release of SP-LI could be detected in response to various noxious mechanical, thermal or chemical stimuli applied to the skin. The present results demonstrate that the superfused rat spinal cord may be used to study in vivo release of tachykinins in response to intense chemical stimulation of the entire spinal cord. However, the method seems to be less suitable for studies of tachykinin release in response to electrical activation engaging only a few spinal segments or in response to natural noxious stimuli. The results obtained in vitro suggest that SP and NKA are released in equimolar amounts from the spinal cord upon stimulation with potassium.     

Glycosphingolipid expression in spontaneously aborted fetuses and placenta from blood group p women. Evidence for placenta being the primary target for anti-Tja-antibodies

A 12-week-old fetus and one 17-week-old fetus + placenta were obtained after spontaneous abortions from two women of blood group p. The 17-week-old fetus was dissected into intestine, liver, brain and residual tissue. Nonacid glycosphingolipid fractions were prepared from the tissues. Glycolipid characterization was carried out using thin layer chromatography immunostained with monoclonal antibodies and bacteria and by¹H NMR spectroscopy and mass spectrometry. In the placental fraction substantial amounts of globotetraosylceramide (P-antigen) and globotriaosylceramide (P^k-antigen) were identified. In contrast, the fetuses contained only trace amounts of these structures, as revealed by immunostaining. These results indicate that the primary target for the antibodies of the anti-Tj^a serum is the placenta tissue, resulting in termination of the pregnancy.