Assessment of the epidemic potential of a new strain of rotavirus associated with the novel G9 serotype which caused an outbreak in the United States for the first time in the 1995-1996 season

Rotavirus causes severe morbidity in developed countries and frequent deaths (> or = 500,000 per year) in less-developed countries. Historically, four serotypes--G1, G2, G3, and G4-have predominated; they are distinguished by one of two surface neutralization antigens (VP7). However, in 1983 and 1984 we described a new rotavirus serotype, designated G9, in five children hospitalized for diarrhea in Philadelphia, Pa. G9 rotavirus was not identified again in the Western Hemisphere until it caused ca. 50% of the rotavirus disease detected in Philadelphia in the 1995-1996 season. This outbreak allowed us to question whether a rotavirus strain completely new to a well-studied community would target either very young infants or older children, cause especially severe disease, or completely displace previously extant serotypes. We observed a significant excess of G9 infections in younger infants (especially in those < 6 months old) that might be attributed to the lack of G9-specific antibodies in mothers. Of further note, six of the seven oldest patients with rotavirus diarrhea were infected with the G9 strains (not significant). However, the age distribution of children with rotavirus did not differ over a 5-year study period regardless of the infecting serotype. Patients with diarrhea associated with G9 strains did not have disease more severe than that caused by the G1, G2, or G3 serotype. G9 strains did not displace the other serotypes but were virtually completely replaced by G1 or G2 serotypes in the three subsequent rotavirus seasons. We conclude that the abrupt appearance of this novel rotavirus serotype did not present a special threat to public health in the community.     

Cerebellar damage impairs automaticity of a recently practiced movement

It has been suggested that the cerebellum plays a critical role in learning to make movements more "automatic" (i.e., requiring less attention to the details of a movement). We hypothesized that cerebellar damage compromises learning of movement automaticity, resulting in increased attentional demands for movement control. The purpose of our study was to determine whether cerebellar damage disrupts the ability to make a practiced movement more automatic. We developed a dual task paradigm using two tasks that did not have overlapping sensory or motor requirements for execution. Our motor task required subjects to maintain an upright posture while performing a figure-8 movement using their arm. This motor task was chosen to simulate requirements of everyday movements (e.g., standing while reaching for objects), but it was novel enough to require practice for improvement. Our secondary task was an auditory vigilance task where subjects listened to letter sequences and were asked to identify the number of times a target letter was heard. We tested controls and people with cerebellar damage as they practiced the movement task alone and then performed it with the auditory task. We recorded 3D position data from the arm, trunk, and leg during the movement task. Errors were recorded for both the movement and the letter tasks. Our results show that cerebellar subjects can improve the movement to a very limited extent with practice. Unlike controls, the motor performance of cerebellar subjects deteriorates to prepractice levels when attention is focused away from the movement during dual task trials. Control subjects' insensitivity to dual task interference after practice was due to learned movement automaticity and was not a reflection of better dual task performance generally. Overall, our findings suggest that the cerebellum may be important for shifting movement performance from an attentionally demanding (unpracticed) state to a more automatic (practiced) state.     

Aspects of social and emotional competence in adult attention-deficit/hyperactivity disorder

Social and emotional competence were evaluated using self-report and behavioral measures in adults with attention-deficit/hyperactivity disorder (ADHD) and controls. Adults with ADHD viewed themselves as less socially competent but more sensitive toward violations of social norms than controls. Films depicting emotional interactions were used to assess linguistic properties of free recall and perceived emotional intensity. Although adults with ADHD used more words to describe the scenes, they used fewer emotion-related words, despite rating the emotions depicted as more intense than did controls. In contrast, no group differences for words depicting social or cognitive processes were observed. Overall, adults with ADHD appear more aware of their problems in social versus emotional skills. Findings may have implications for improving the psychosocial functioning of these adults.     

Clinical,hematologic, and immunologic effects of interleukin-10 in humans

We conducted a double-blind, placebo-controlled study to investigate the safety, pharmacokinetics, and immunological properties of interleukin-10 (IL-10) administration in healthy humans. Volunteers received a single intravenous bolus injection of recombinant human IL-10 (1, 10, or 25g/kg) or placebo. Cytokine production in whole blood and peripheral blood mononuclear cells (PBMC) was assessed before and 3, 6, 24, and 48 hr after the injection. Peak serum concentrations of IL-10 (15±1.1, 208±20.1, and 505±22.3 ng/ml) occurred after 2–5 min for 1, 10, and 25g/kg IL-10, respectively. The terminal-phase half-life was 3.18 hr. A transient leukocytosis (24–63% above baseline) was observed 6 hr after injection, which coincided with a dose-dependent decrease (12–24%) in neutrophil superoxide generation. There was a marked inhibition (60–95%) of endotoxin-induced IL-6 production from whole blood in each group receiving IL-10. Production of IL-8 in endotoxin-stimulated blood was reduced in the 10g/kg group. In PBMC stimulated with phytohemagglutinin and phorbol ester, there was a decrease (72–87%) in interferon- (IFN) production 6 hr after IL-10 with a return to pre-IL-10 levels after 24 hr. This reduction was only partially associated with a decrease in the number of CD2-bearing cells. We conclude that IL-10 administration into humans is without significant side effects, and a single injection reducesex vivo production of IL-6, IL-8, and IFN.     

Results of a high-resolution genome screen of 437 Alzheimer's disease families

Alzheimer's disease (AD) is a devastating neurodegenerative disorder of late life with complex inheritance. Mutations in three known genes lead to the rare early-onset autosomal dominant form of AD, while a common polymorphism (epsilon 4) in the gene encoding apolipoprotein E (APOE ) is a risk factor for more typical late-onset (>60 years) AD. A recent study concluded that there are up to four additional genes with an equal or greater contribution to the disease. We performed a 9 cM genome screen of 437 families with AD, the full National Institute of Mental Health (NIMH) sample, which has been carefully ascertained, evaluated and followed by our group over the last decade. Performing standard parametric and non-parametric linkage analyses, we observed a 'highly significant' linkage peak by Lander and Kruglyak criteria on chromosome 19q13, which probably represents APOE. Twelve additional locations-on 1q23, 3p26, 4q32, 5p14, 6p21, 6q27, 9q22, 10q24, 11q25, 14q22, 15q26 and 21q22-met criteria for 'suggestive' linkage [i.e. two-point lod score (TLS) >/=1.9 and/or multipoint lod score (MLS) >/=2.2] in at least one of our analyses. Although some of these will surely prove to be false positives, these linkage signals should provide a valuable framework for future studies aimed at identifying additional susceptibility genes for late-onset AD.     

Mutational analysis of the enzymatic domain of Clostridium difficile toxin B reveals novel inhibitors of the wild-type toxin

Toxin B (TcdB), a major Clostridium difficile virulence factor, glucosylates and inactivates the small GTP-binding proteins Rho, Rac, and Cdc42. In the present study we provide evidence that enzymatically inactive fragments of the TcdB enzymatic domain are effective intracellular inhibitors of native TcdB. Site-directed and deletion mutants of the TcdB enzymatic region (residues 1 to 556), lacking receptor binding and cell entry domains, were analyzed for attenuation of glucosyltransferase and glucosylhydrolase activity. Five of six derivatives from TcdB(1-556) were found to be devoid of enzymatic activity. In order to facilitate cell entry, mutants were genetically fused to lfn, which encodes the protective antigen binding region of anthrax toxin lethal factor and mediates the cell entry of heterologous proteins. In line with reduced enzymatic activity, the mutants also lacked cytotoxicity. Remarkably, pretreatment or cotreatment of cells with four of the mutants provided protection against the cytotoxic effects of native TcdB. Furthermore, a CHO cell line expressing enzymatically active TcdB(1-556) was also protected by the mutant-derived inhibitors, suggesting that inhibition occurred at an intracellular location. Protection also was afforded by the inhibitor to cells treated with Clostridium sordellii lethal toxin (TcsL), which uses the same cosubstrate as TcdB but shares Rac only as a common substrate target. Finally, the inhibitor did not provide protection against Clostridium novyi alpha-toxin (Tcnalpha), which shares similar substrates with TcdB yet uses a different cosubstrate. This is the first report to demonstrate that the potential exists to inhibit toxins at their intracellular site of action by using inactive mutants.     

Enhanced molecular volume of conservatively pegylated Hb: (SP-PEG5K)6-HbA is non-hypertensive

Recent studies have suggested that the "pressor effect" of acellular Hb is a consequence of perturbation of the macro-and microcirculatory system in multiple ways, and that PEGylation is an effective approach for controlling the same. In an attempt to confirm this concept, a new and simple thiolation mediated, maleimide chemistry-based conservative PEGylation protocol has been developed to conjugate multiple copies of PEG-chains to Hb. This approach combines the high reactivity of maleimides towards thiols with the propensity of iminothiolane to derivatize the epsilon-amino groups of proteins into reactive thiol groups, with conservation of their positive charge. One of the PEGylated products, namely (SP-PEG5K)6-HbA, that carries on an average six copies of PEG5000 chains per Hb, is non-hypertensive in hamster top load and in rat 50% exchange transfusion models. This hexa-PEGylated-Hb has (i) a hydrodynamic volume corresponding to that of an oligomerized Hb of 256kDa, (ii) a molecular radius of approximately 6.8 nm, (iii) high oxygen affinity, (iv) lowered Bohr effect, and (v) increased viscosity and colloidal osmotic pressure. These properties of (SP-PEG5K)6-HbA are consistent with the emerging new paradigms for the design of Hb based oxygen carriers and confirm the concept that the "pressor effect" of Hb is a multifactorial event. The thiolation mediated maleimide chemistry-based PEGylation protocol described here for the generation of (SP-PEG5K)6-Hb is simple, highly efficient, and is carried out under oxy conditions. The results demonstrate that a non-hypertensive PEG-Hb can be generated by conjugation of a lower number of PEG chains than previously reported.