Intrinsic somatosensory feedback supports motor control and learning to operate artificial body parts.

Objective.Considerable resources are being invested to enhance the control and usability of artificial limbs through the delivery of unnatural forms of somatosensory feedback. Here, we investigated whether intrinsic somatosensory information from the body part(s) remotely controlling an artificial limb can be leveraged by the motor system to support control and skill learning.Approach.We used local anaesthetic to attenuate somatosensory inputs to the big toes while participants learned to operate through pressure sensors a toe-controlled and hand-worn robotic extra finger. Motor learning outcomes were compared against a control group who received sham anaesthetic and quantified in three different task scenarios: while operating in isolation from, in synchronous coordination, and collaboration with, the biological fingers.Main results.Both groups were able to learn to operate the robotic extra finger, presumably due to abundance of visual feedback and other relevant sensory cues. Importantly, the availability of displaced somatosensory cues from the distal bodily controllers facilitated the acquisition of isolated robotic finger movements, the retention and transfer of synchronous hand-robot coordination skills, and performance under cognitive load. Motor performance was not impaired by toes anaesthesia when tasks involved close collaboration with the biological fingers, indicating that the motor system can close the sensory feedback gap by dynamically integrating task-intrinsic somatosensory signals from multiple, and even distal, body-parts.Significance.Together, our findings demonstrate that there are multiple natural avenues to provide intrinsic surrogate somatosensory information to support motor control of an artificial body part, beyond artificial stimulation.

Investigation and control of an outbreak due to a contaminated hospital water system, identified following a rare case of Cupriavidus pauculus bacteraemia.

BACKGROUND: Cupriavidus pauculus is rare cause of clinical infection. We describe an outbreak of C. pauculus and other Gram-negative bacteraemias in a paediatric haemato-oncology unit secondary to a contaminated water supply and drainage system. AIM: To describe the investigation and control measures implemented for a waterborne infection outbreak in a new build hospital. METHODS: Extensive water testing from various points within the water system was undertaken. Taps, showerheads and components including flow straighteners underwent microbiological analysis. Drains were also swabbed. Surveillance for Gram-negative infections was established on the unit. FINDINGS: Water testing revealed widespread contamination of the water and drainage system. Outlets were also heavily contaminated, including flow straighteners. Drains were found to have underlying structural abnormalities. Water testing enabled us to detect high-risk components within the water system such as the expansion vessels and outlets and the results assisted with hypotheses generation. Review of commissioning data and risk assessments revealed extensive risks present within the water system prior to and after hospital opening. CONCLUSION: Careful design, adequate control measures and maintenance are essential for hospital water systems in order to prevent infections due to waterborne organisms. We discuss what can be learned from this incident with a view to future prevention.

Unmasking Latent Inhibitory Connections in Human Cortex to Reveal Dormant Cortical Memories.

Balance of cortical excitation and inhibition (EI) is thought to be disrupted in several neuropsychiatric conditions, yet it is not clear how it is maintained in the healthy human brain. When EI balance is disturbed during learning and memory in animal models, it can be restabilized via formation of inhibitory replicas of newly formed excitatory connections. Here we assess evidence for such selective inhibitory rebalancing in humans. Using fMRI repetition suppression we measure newly formed cortical associations in the human brain. We show that expression of these associations reduces over time despite persistence in behavior, consistent with inhibitory rebalancing. To test this, we modulated excitation/inhibition balance with transcranial direct current stimulation (tDCS). Using ultra-high-field (7T) MRI and spectroscopy, we show that reducing GABA allows cortical associations to be re-expressed. This suggests that in humans associative memories are stored in balanced excitatory-inhibitory ensembles that lie dormant unless latent inhibitory connections are unmasked.

Control of Legionella pneumophila in a hospital water system by chlorine dioxide.

Immuno-compromised patients are particularly susceptible to Legionnaires' Disease. After three cases of the disease occurred in a hospital, a continuous dosing regime using chlorine dioxide was initiated to replace chlorination of the water system. This study identified a number of factors which may have resulted in conditions that would encourage the growth of the water-borne pathogen Legionella pneumophila. The residual chlorination was inadequate for microbial control at the taps furthest from the four storage tanks, of which two were found to be in excess for demand. The temperature of the water in the storage tanks was also found to be above 20 degrees C; a temperature that would encourage microbial growth. A back-up calorifier was present and was found to contain L. pneumophila, and linseed oil-based sealants that provide nutrients for microbial growth were also prevalent as jointing compounds in the water circuit. Although the shower heads were routinely disinfected, a requirement was identified to also disinfect the shower hoses. No L. pneumophila were recovered from the water system after the chlorine reduced dioxide disinfection trial. Biofilm was also dramatically reduced after disinfection; however, small microcolonies were identified and proved to be metabolically active when tested with a metabolic indicator. Using light and fluorescence microscopy, the pipe samples removed from the water system were rapidly analysed for biofouling, complementing existing microbiological methods.

Legionella in hospitals: a review.

Although epidemics of nosocomial Legionnaires' disease attract great attention, up to 30% of sporadic cases of hospital-acquired pneumonia are caused by legionellae. Legionellae are ubiquitous contaminants of potable water and can achieve high numbers in the hot-water systems of large buildings such as hospitals. They are present in the mains water supply in small numbers but are amplified considerably in the hospital's hot-water system. This is encouraged by water temperatures below 50 degrees C, areas of stagnation and sludge formation, the presence of amoebae and other bacteria and the materials used in the piping. Formation of aerosols from contaminated water is a major mode of spread of legionellae, but there is evidence to suggest that aspiration is also a mode of entry. Safe levels of legionellae in cooling towers have been defined, but not for hot-water systems. A combination of culture and antigen detection by immunofluorescence offer the best method for enumerating legionellae in environmental samples. Control involves a mixture of physical (heat, UV irradiation, sanitation) and chemical (hypochlorite, ozone) methods combined with good plumbing practice (e.g. arrangement of pumps and calorifiers, elimination of dead-legs). Adequate control can be costly and requires considerable attention to detail.

The effect of a self-regulating trace heating element on Legionella within a shower.

A self-regulating trace heating element was assessed for its ability to maintain a temperature of 50 degrees C in the mixer valve and dead-legs of a shower, and for its effect on legionellas colonizing the shower. The trace heating element maintained a temperature of 50 degrees C +/- 1.5 degrees C in dead-legs when the circulating hot water supply remained above 45 degrees C. Legionellas appeared in a trace heated dead-leg when the temperature of the dead-leg reached 45 degrees C and the hot water supply dropped below this temperature. Legionellas were eradicated or significantly reduced in sections of the shower where a temperature of 50 degrees C was consistently achieved. The mixer valve which was trace heated but not insulated remained colonized with Legionellas. Legionellas were found in shower water throughout the study.

Bacteriological studies of the venom and mouth cavities of wild Malayan pit vipers (Calloselasma rhodostoma) in southern Thailand.

Venom and oropharyngeal swabs from freshly captured Malayan pit vipers (Calloselasma rhodostoma) in southern Thailand and captive specimens in England were cultured aerobically and anaerobically to identify the bacterial flora which might contaminate wounds inflicted by bites of this species. The snakes' mouths contained a wider range of organisms than their venoms, especially gut-related Gram-negative rods such as Enterobacter and Pseudomonas species and some staphylococci and clostridia. There were fewer positive cultures from captive snakes. C. rhodostoma venom inhibited the growth of group A streptococci and, to a lesser extent, that of Staphylococcus aureus and Clostridium perfringens but not that of 2 Gram-negative organisms. Secondary bacterial infection is an important complication of snake bite, especially of necrotic wounds. A combination of gentamicin with benzyl penicillin would have prevented infection with, or treated, most of the bacteria isolated from snake venoms and mouths in Thailand.

The efficacy of control measures for eradicating legionellae in showers.

The efficacy of secondary control measures on showers colonized with legionellae was assessed. Hyperchlorination of shower heads and angle valve strainers had only a short-lived effect on legionellae. Automatic drain valves fitted to showers were ineffective in maintaining a reduction in the number of legionellae in shower water. Regular flushing of showers reduced legionellae to below detectable levels. Removal of dead-legs from the feed-pipes supplying hot water to showers, resulted in a decrease in legionellae in these sites but an increase in legionellae colonizing mixer valve components.

Detection of Legionella pneumophila in environmental water samples using a fluorescein conjugated monoclonal antibody.

Sixty-three environmental water samples from various sources were examined for the presence of Legionella pneumophila with a commercially available direct fluorescent monoclonal antibody (GS), an indirect fluorescent antibody test (IFAT) and culture. GS detected L. pneumophila in 94% and 100% of environmental water samples which were culture and IFAT positive for L. pneumophila, respectively. IFAT detected 69% of L. pneumophila culture positive samples. Cultures of L. pneumophila serogroups 1 to 12, 14 and non-L. pneumophila bacteria which may be found in water, and bacteria containing non-specific binding proteins, were stained by GS and IFAT. GS identified all serogroups of L. pneumophila and did not cross react with any non-L. pneumophila bacteria. L. pneumophila in environmental samples was easy to detect against a clear dark background when stained with GS.

Legionella pneumophila serogroup 12 pneumonia in a renal transplant recipient: case report and environmental observations.

We describe the first reported case of pneumonia due to Legionella pneumophila serogroup 12 in the UK. This hospital-associated infection occurred in an immuno-incompetent patient and coincided with a change in character of the local environmental strains of legionellas. The patient produced a serological response both to her own isolate and to L. pneumophila serogroups 1-6. Thus serodiagnosis was attainable using the usual screening antigens.

Amoxycillin-clavulanic acid (Augmentin) antibiotic prophylaxis against wound infections in renal failure patients.

A randomized, controlled trial of the use of amoxycillin with clavulanic acid (Augmentin) for prophylaxis against wound infections following major surgery, including transplantation, in patients with chronic renal failure, was undertaken. Six of 22 control patients developed wound infections (27%) whereas no patient in the treatment group (24) developed a wound infection (P less than 0.05). After the termination of this trial, the next 35 consecutive patients received prophylactic amoxycillin/clavulanate; of these only two developed wound infections associated with leakage from their pancreatic anastomoses. All the wound infections were shown to be caused by bacteria sensitive to amoxycillin/clavulanate. Pharmacokinetic studies in patients have shown that a bactericidal concentration of the drugs was present for up to 20 h post-operatively in patients on dialysis, and in recipients of non-functioning renal transplants. In patients with normal renal transplant function excretion of the drug within 12 h was observed.

Comparative evaluation of the immediate and sustained antibacterial action of two regimens, based on triclosan- and chlorhexidine-containing handwash preparations, on volunteers.

The degerming effect of a 3 min handwash with 2% triclosan, or 4% chlorhexidine, in detergent and enhanced efficacy of either antiseptic in isopropyl alcohol, was evaluated in volunteers. Handwashing with either antiseptic preparation reduced the normal flora by a factor of 10; alcohol rubbing by approximately a factor of 1000. Both regimens eliminated Micrococcus roseus, artificially inoculated before every procedure. The sustained action of the same detergent preparations was further studied in gloved and ungloved hands by the Vinson's 'finger imprint test'. In the gloved hand both antiseptics inhibited Staphylococcus epidermidis for 4 h. In the ungloved hand however, triclosan remained active longer than chlorhexidine. Whilst the activity of chlorhexidine was short-lived against a clinical isolate of S. aureus, particularly in the ungloved hand, the sustained effect of triclosan against the same strain persisted for 4 h on either hand.

Evaluation of the skin disinfecting activity and cumulative effect of chlorhexidine and triclosan handwash preparations on hands artificially contaminated with Serratia marcescens.

The initial and cumulative efficacy of two antiseptic handwash preparations in eliminating Serratia marcescens from hands was evaluated on volunteers. Two antiseptics with persistent skin antibacterial activity, 4% chlorhexidine gluconate in detergent and 1.5% triclosan in natural soap, were studied in a new protocol designed according to Food and Drug Administration guidelines. After a single handwash, both preparations exhibited a degerming action statistically superior to the mechanical elimination of the marker organism that was achieved by the nonmedicated controls. Following a further nine hand recontamination sequence with 10(9) colony-forming units (cfu)/mL S marcescens (mean predisinfection baseline, log10 6.6), the efficacy of chlorhexidine and triclosan was significantly augmented: the mean log10 reduction factors were 4.15 and 3.78, respectively. In the absence of internationally accepted testing standards for antiseptic handwash products, the significance of protocol variables is discussed. The advantages to preventative microbiology of antiseptics with persistent skin antibacterial activity are highlighted.

Assessment of the remanent antibacterial effect of a 2% triclosan-detergent preparation on the skin.

A method of quantifying the remanent antibacterial effect of a 2% triclosan preparation in detergent following three consecutive applications on the forearm of 20 volunteers over 2 h, is described with reference to its efficacy against a gentamicin- and multiply-resistant serotype of Klebsiella aerogenes. The relevance of the residual activity of triclosan and other skin antiseptics in surgical and hygienic hand disinfection are discussed.

Intestinal changes associated with rotavirus and enterotoxigenic Escherichia coli infection in calves.

Newborn calves inoculated with rotavirus, enterotoxigenic Escherichia coli (ETEC) serotype 020:K' x 106':K99:HNM, either alone or in combination, became depressed, anorectic, diarrhoeic and dehydrated. ETEC did not adhere to the intestine although there was extensive proliferation in the lumen. Only slight mucosal changes were induced by ETEC and the activity of membrane bound lactase remained normal. More severe mucosal damage and a decrease in lactase activity were found in newborn calves inoculated with either rotavirus or rotavirus and ETEC in combination. The most severe clinical illness was found in calves inoculated with both rotavirus and ETEC. Calves inoculated at 1 week of age with either rotavirus or ETEC remained clinically normal. Rotavirus infection produced slight mucosal changes and a reduction of lactase activity. In contrast, colostrum-fed or suckling calves up to 2 weeks old inoculated with both rotavirus and ETEC became clinically affected, showed severe mucosal damage and decreased lactase activity. There was no bacterial adhesion to the intestinal mucosa as observed by immunofluorescent labelling and light microscopy.

Enterocolitis in piglets caused by Cryptosporidium sp. purified from calf faeces.

Twelve gnotobiotic piglets were dosed with a bacteria-free calf faecal homogenate which contained Cryptosporidium oocysts. The infection induced severe enterocolitis in piglets when inoculated at 1 day of age, moderate diarrhoea at 7 days of age and a subclinical infection at 15 days of age. In piglets aged 3 days or less, the entire intestine was extensively infected with Cryptosporidium and the mucosa was severely damaged. In piglets 7 days of age or older, the upper small intestine was sparsely infected with the organisms, but the ileum and the large bowel were heavily infected with associated mucosal damage.

Experimental colibacillosis in gnotobiotic piglets exposed to 3 enterotoxigenic serotypes.

Three strains of enterotoxigenic Escherichia coli (ETEC) (064:KSNT, K88ac; 020:KSNT, K88ac and 08:K85ab, K99) originally cultured from outbreaks of diarrhoea in piglets a few hours old, were administered orally to gnotobiotic piglets. There was a marked age-related difference in the clinical response to infection between the 3 strains although they all produced heat-stable toxin. All 3 strains produced severe clinical signs of depression, anorexia, vomiting, diarrhoea, followed by dehydration and death in one-day-old piglets. In piglets infected at 3 days of age the two K88+ ETEC caused diarrhoea and death but the K99+ ETEC induced moderate diarrhoea only. In piglets infected at 7 days of age, the 064 strain produced severe diarrhoea and death, and 020 strain caused mild diarrhoea in 3 of 6 piglets with one death while the 08 strain caused no illness. Pathological changes in the intestinal tract associated with these infections were minimal, or absent. Immunofluorescent staining with homologous hyperimmune sera demonstrated adherence of the 3 ETEC strains to the brush border of small intestinal epithelial cells. Fluorescing organisms were observed in all infected piglets irrespective of the severity of clinical signs but the degree and extent of colonisation varied with the age of the piglets and the infecting strain. This may explain the difference in clinical response between the 3 strains.