Sequence analysis of feline caliciviruses isolated from the oral cavity of clinically normal domestic cats (Felis catus) in Florida

Four isolates (7.3 per cent) of feline calicivirus (FCV), from oropharyngeal swabs taken from 55 unvaccinated apparently healthy cats, were identified by electron microscopy and reverse transcription-polymerase chain reaction (RT-PCR). A 671-bp fragment, comprising part of region B, all of regions C, D, and E and part of region F of the FCV capsid protein gene, was amplified from each isolate by RT-PCR and cloned for sequence analysis. Amino acid sequence comparison of these regions revealed significant sequence divergence from the F9 vaccine strain within regions C, E, and F. The hypervariable region E of the four Florida isolates and the NADC isolate contained three fewer amino acids than the commonly used F9 vaccine strain. This work provides support to the idea that currently circulating FCV strains may differ substantially from presently used vaccine strains.

Neurobehavioral changes in mice treated with methylmercury at two different stages of fetal development

Pregnant C57BL/6 mice were orally given daily doses of 4 or 6 mg/kg of methylmercury chloride (MeHg) or vehicle during either gestational days 7-9 (GD7-9) or days 12-14 (GD12-14). Their female offspring were tested between 6 and 16 weeks of age on a variety of behavioral tasks. Motor coordination on the rotarod and visual discrimination learning in the Y maze were not affected by administration of MeHg either at GD7-9 or at GD12-14. In the open field, the total number of square crossings was lower in mice treated with 4 and 6 mg/kg of MeHg at GD12-14 than in control mice whether the environment was new or familiar, but prenatal administration of MeHg at GD7-9 had no effect on this measure. Administration of MeHg either at GD7-9 or at GD12-14 had no effect on the percentage of central square crossings or on the frequency of rearings in the open field. On spatial alternation training in the T maze, both treated groups in Condition GD7-9 and the group treated with 6 mg/kg at GD12-14 required more sessions to reach the learning criterion than their respective vehicle groups. When spatial alternation was tested with delays, treated groups did not differ from their respective control groups. In the radial arm maze, the performance of mice treated at GD7-9 was normal, but reference memory and working memory were impaired by administration of MeHg at GD12-14. In mice treated with 4 mg/kg of MeHg, reference memory was impaired only on the first block of trials, whereas in mice treated with 6 mg/kg, the deficit persisted on all blocks of trials. Overall, these results indicate that prenatal administration of MeHg at GD12-14 had more detrimental effects on behavioral performance than administration at GD7-9. It reduced locomotor activity and impaired reference memory for egocentric and allocentric spatial information as well as working memory for places.

Screening for herpesvirus genomes in common acute lymphoblastic leukemia

There is epidemiological evidence that infection may play a role in the etiology of childhood leukemia in particular common B cell precursor acute lymphoblastic leukemia. A panel of 20 leukemic samples (panel 1) was examined for the presence of four lymphotropic herpesviruses using conventional molecular techniques. A second independent panel of 27 leukemic samples (panel 2), along with 28 control peripheral blood samples from children with other forms of cancer, was tested for the presence of the same four viruses using sensitive real-time quantitative PCR. While herpesvirus genomes were detected, they were present at very low levels; detection rates and levels were similar in the leukemic and control panels. In addition we surveyed 18 leukemic samples (five from panel 1, six from panel 2 and a further seven samples not previously analyzed) using a degenerate PCR assay capable of detecting the genomes of known herpesviruses plus putative new members of the family. No novel herpesvirus genomes were detected suggesting that a herpesvirus is unlikely to be etiologically involved as a transforming agent in common acute lymphoblastic leukemia.

Signals that initiate somatic hypermutation of B cells in vitro

Somatic hypermutation is initiated as B lymphocytes proliferate in germinal centers. The signals that switch on the mutation process are unknown. We have derived an in vitro system to define signals that will initiate mutation in normal, naive splenic B cells. We find that three signals are required to allow detection of somatic mutation in vitro; these are anti-Ig, anti-CD40, and anti-CD38. If any one of these is omitted, mutation remains off. We show that CD40 is obligatory in vivo, as CD40 knockout mice exhibit no Ag-driven mutation. In contrast, CD38 is not, as CD38 knockout mice mutate normally. We believe that, in vitro, CD38, in combination with other stimuli, drives extensive cell division, allowing the detection of mutated sequences. However, in germinal centers in vivo, proliferative activity is instigated by a different molecule. This is the first demonstration of the initiation of hypermutation in vitro with normal splenic B cells using defined stimuli.

Role of cAMP-dependent protein kinase (PKA) in opioid agonist-induced mu-opioid receptor downregulation and tolerance in mice

Studies suggest that acute and chronic opioids can regulate the cAMP-dependent protein kinase (PKA) signaling pathway and that changes in this pathway may be involved in opioid tolerance. In the present study, we examined the role of cAMP-PKA on mu-opioid receptor downregulation and tolerance in mice. Mice were injected intracerebroventricular (i.c.v.) and intrathecal (i.t.) once a day with an antisense oligodeoxynucleotide directed at the mRNA for the alpha catalytic subunit of mouse PKA. Controls were treated with saline or a mismatch oligodeoxynucleotide. On day 2 of treatment, mice were implanted s.c. with a 25-mg morphine pellet and an osmotic minipump infusing morphine (40 mg/kg/day) for 3 days. Other mice were implanted with an osmotic minipump infusing etorphine (125, 250 microg/kg/day) for 2 days. Control mice were implanted s.c. with inert placebo pellets. At the end of treatment, pumps and pellets were removed and mice tested for morphine or etorphine analgesia. Other mice were sacrificed and mu-opioid receptor binding assays conducted in whole brain. Both infusion doses of etorphine produced significant tolerance (ED(50) shift = 3.6 and 6.3-fold). The higher etorphine infusion produced downregulation of mu-receptor density ( approximately 30%) while the lower infusion dose of etorphine did not. Morphine treatment also produced significant tolerance in mice (ED(50) shift = 4.5-fold), but no receptor downregulation. Antisense to PKA partially blocked tolerance induced by the higher dose of etorphine, but had no effect on receptor downregulation. On the other hand, antisense to PKA completely blocked tolerance induced by morphine and the lower infusion dose of etorphine. The mismatch oligodeoxynucleotide had no effect on any measure. These results suggest that PKA has a limited role in opioid agonist-induced receptor downregulation. However, the partial block of tolerance for the high infusion dose of etorphine and the complete block of tolerance for morphine and the low infusion dose of etorphine suggests that PKA may play a critical role in tolerance that is "receptor-regulation-independent."

Role of cAMP-dependent protein kinase (PKA) in opioid agonist-induced mu-opioid receptor downregulation and tolerance in mice

Studies suggest that acute and chronic opioids can regulate the cAMP-dependent protein kinase (PKA) signaling pathway and that changes in this pathway may be involved in opioid tolerance. In the present study, we examined the role of cAMP-PKA on mu-opioid receptor downregulation and tolerance in mice. Mice were injected intracerebroventricular (i.c.v.) and intrathecal (i.t.) once a day with an antisense oligodeoxynucleotide directed at the mRNA for the alpha catalytic subunit of mouse PKA. Controls were treated with saline or a mismatch oligodeoxynucleotide. On day 2 of treatment, mice were implanted s.c. with a 25-mg morphine pellet and an osmotic minipump infusing morphine (40 mg/kg/day) for 3 days. Other mice were implanted with an osmotic minipump infusing etorphine (125, 250 microg/kg/day) for 2 days. Control mice were implanted s.c. with inert placebo pellets. At the end of treatment, pumps and pellets were removed and mice tested for morphine or etorphine analgesia. Other mice were sacrificed and mu-opioid receptor binding assays conducted in whole brain. Both infusion doses of etorphine produced significant tolerance (ED(50) shift = 3.6 and 6.3-fold). The higher etorphine infusion produced downregulation of mu-receptor density ( approximately 30%) while the lower infusion dose of etorphine did not. Morphine treatment also produced significant tolerance in mice (ED(50) shift = 4.5-fold), but no receptor downregulation. Antisense to PKA partially blocked tolerance induced by the higher dose of etorphine, but had no effect on receptor downregulation. On the other hand, antisense to PKA completely blocked tolerance induced by morphine and the lower infusion dose of etorphine. The mismatch oligodeoxynucleotide had no effect on any measure. These results suggest that PKA has a limited role in opioid agonist-induced receptor downregulation. However, the partial block of tolerance for the high infusion dose of etorphine and the complete block of tolerance for morphine and the low infusion dose of etorphine suggests that PKA may play a critical role in tolerance that is "receptor-regulation-independent."

Model of particle growth in silane discharges

The growth of silicon particles in the neutral plasma region of pure silane, rf capacitively coupled, steady-state discharges is calculated with a homogeneous, plasma-chemistry model. Plasma conditions are typical of those used in hydrogenated amorphous silicon (a-Si:H) device production. SiH3 and SiH-3 grow into particles by the step-by-step addition of silicon atoms, primarily due to reactions with SiH3. Attrition of growing Si(x)H(z)(m) radicals and ions with z charges, which are "particles" for large x, occurs by diffusion of neutral and positively charged radicals to the electrodes. Rate coefficients for electron, ion, radical, and silane collisions with the Si(x)H(z)(m) for x=1-10(5) are estimated from detailed considerations of the literature and relevant physics. Self-consistent anion, cation (n(+)), and electron (n(e)) densities and charge fluxes are used, and charge neutrality is maintained. Typically n(+)/n(e) congruent with100, which causes a large fraction of neutral particles and thereby a major particle flux into the growing a-Si:H film. The density of visible particles (x>10(4)) varies many orders of magnitude with relatively minor changes in discharge power, pressure, and electrode gap. This parameter dependence agrees with experiment, and by adjusting collision parameters within a reasonable range the calculated particle densities can be brought into exact agreement with experiment. An additional result of the model, which has not yet been detected, is that Si(x)H(m) clusters with 3<x<30 are continuously deposited into growing films, and for typical conditions yield a very significant fraction (1-10 %) of total film growth.

Analysis of post-translational modification of mycobacterial proteins using a cassette expression system

A recombinant expression system was developed to analyse sequence determinants involved in O-glycosylation of proteins in mycobacteria. By expressing peptide sequences corresponding to known glycosylation sites within a chimeric lipoprotein construct, amino acids flanking modified threonine residues were found to have an important influence on glycosylation. The expression system was used to screen mycobacterial sequences selected using a neural network (NetOglyc) trained on eukaryotic O-glycoproteins. Evidence of glycosylation was obtained for eight of 11 proteins tested. The results suggest that sites involved in O-glycosylation of mycobacterial and eukaryotic proteins share similar structural features.

Precursors of literacy delay among children at genetic risk of dyslexia

This paper reports the literacy skills of 63 children selected as being at genetic risk of dyslexia compared with 34 children from families reporting no history of reading impairment. Fifty-seven per cent of the at-risk group were delayed in literacy development at 6 years compared with only 12% of controls. The "unimpaired" at-risk group were not statistically different from controls on most cognitive and language measures at 45 months, whereas the literacy-delayed group showed significantly slower speech and language development, although they did not differ from controls in nonverbal ability. Letter knowledge at 45 months was the strongest predictor of literacy level at 6 years. In addition, early speech and language skills predicted individual differences in literacy outcome and genetic risk accounted for unique variance over and above these other factors. The results are discussed in terms of an interactive developmental model in which semantic and phonological skills support early reading acquisition.

Neurotrophin-3 reverses nerve conduction velocity deficits in streptozotocin-diabetic rats

The ability of neurotrophin-3 (NT-3) to reverse established nerve disorders was investigated in the peripheral neuraxis of streptozotocin-diabetic rats. Sciatic sensory and motor nerve conduction velocity deficits established after 2 months of diabetes were completely normalized by one further month of treatment with either NT-3 or insulin. None of these conduction velocity changes were associated with altered mean axonal caliber in the sciatic nerve. In the dorsal and ventral roots, mean axonal caliber was significantly decreased after 8 weeks of diabetes (both P < 0.05). Subsequently, one month of insulin, but not NT-3, treatment increased mean axonal caliber to age-matched control values. NT-3 treatment was also without effect on the significant (both P < 0.05) decrease in phosphorylated heavy neurofilament (NFH) subunits seen in dorsal and ventral roots of 12 week diabetic rats. In the sural nerve, diabetes attenuated a maturation-associated increase in mean axonal caliber over the first 8 weeks of diabetes, and induced atrophy between weeks 8 and 12 that was ameliorated by both NT-3 and insulin treatment. Reductions in sural nerve axonal caliber were associated with a tendency for elevation of both phosphorylated NFH levels in large fibers and the ratio of phosphorylated to nonphosphorylated NFH that was attenuated by NT-3. These data demonstrate that NT-3 corrects established sciatic nerve conduction deficits in diabetic rats in a manner independent of changes in axonal caliber in this nerve. Further, although NT-3 was without effect on decreases in axonal caliber and NFH subunit phosphorylation in the spinal roots, reversal of axonal caliber deficits in peripheral nerves of sensory fibers may involve NT-3-mediated normalization of aberrant neurofilament phosphorylation.

A cultural effect on brain function

We present behavioral and anatomical evidence for a multi-component reading system in which different components are differentially weighted depending on culture-specific demands of orthography. Italian orthography is consistent, enabling reliable conversion of graphemes to phonemes to yield correct pronunciation of the word. English orthography is inconsistent, complicating mapping of letters to word sounds. In behavioral studies, Italian students showed faster word and non-word reading than English students. In two PET studies, Italians showed greater activation in left superior temporal regions associated with phoneme processing. In contrast, English readers showed greater activations, particularly for non-words, in left posterior inferior temporal gyrus and anterior inferior frontal gyrus, areas associated with word retrieval during both reading and naming tasks.

Detection of Epstein-Barr virus (EBV) genomes in the serum of patients with EBV-associated Hodgkin's disease

DNA from malignant cells is present in the serum/plasma of cancer patients and DNA from this source is amenable to analysis by polymerase chain reaction (PCR). In the present study, we evaluated whether Epstein-Barr virus (EBV) DNA is present in the serum of patients with EBV-associated Hodgkin's disease (HD). Using conventional PCR, EBV DNA was detected in serum from 30/33 patients with EBV-associated HD but in only 6/26 patients with non-EBV-associated disease (p < 0.001). Samples from healthy individuals were negative and only 5/12 infectious mononucleosis samples were positive. Real-time quantitative PCR was subsequently employed to determine the concentration of EBV DNA present in serum; among positive samples the level ranged from 1 to 705 copies per 125 microliter of serum. Post-treatment samples from 5/14 cases with EBV-associated HD contained detectable EBV DNA; analysis of this small group of cases suggests that positivity in post-treatment samples correlates with risk factors indicative of a poor prognosis. Overall, our results are consistent with the notion that DNA from Reed-Sternberg cells is present in the serum of HD patients, and further suggest that serum EBV should be evaluated as a prognostic marker. Int. J. Cancer (Pred. Oncol.) 84:442-448, 1999.

Aberrant neurofilament phosphorylation in sensory neurons of rats with diabetic neuropathy

Aberrant neurofilament phosphorylation occurs in many neurodegenerative diseases, and in this study, two animal models of type 1 diabetes--the spontaneously diabetic BB rat and the streptozocin-induced diabetic rat--have been used to determine whether such a phenomenon is involved in the etiology of the symmetrical sensory polyneuropathy commonly associated with diabetes. There was a two- to threefold (P < 0.05) elevation of neurofilament phosphorylation in lumbar dorsal root ganglia (DRG) of diabetic rats that was localized to perikarya of medium to large neurons using immunocytochemistry. Additionally, diabetes enhanced neurofilament M phosphorylation by 2.5-fold (P < 0.001) in sural nerve of BB rats. Neurofilaments are substrates of the mitogen-activated protein kinase (MAPK) family, which includes c-jun NH2-terminal kinase (JNK) or stress-activated protein kinase (SAPK1) and extracellular signal-regulated kinases (ERKs) 1 and 2. Diabetes induced a significant three- to fourfold (P < 0.05) increase in phosphorylation of a 54-kDa isoform of JNK in DRG and sural nerve, and this correlated with elevated c-Jun and neurofilament phosphorylation. In diabetes, ERK phosphorylation was also increased in the DRG, but not in sural nerve. Immunocytochemistry showed that JNK was present in sensory neuron perikarya and axons. Motoneuron perikarya and peroneal nerve of diabetic rats showed no evidence of increased neurofilament phosphorylation and failed to exhibit phosphorylation of JNK. It is hypothesized that in sensory neurons of diabetic rats, aberrant phosphorylation of neurofilament may contribute to the distal sensory axonopathy observed in diabetes.