Categorical and coordinate spatial processing: more on contributions of the transient/magnocellular visual system.

Observers were presented with stimuli consisting of a line and two horizontally separated dots. A categorical spatial task required observers to indicate whether the dots were above or below the line and a coordinate spatial task required observers to indicate whether the line could fit into the space between the two dots. Coordinate (but not categorical) spatial processing was less accurate and took longer with stimuli presented on a red background than with stimuli presented on a green background, even though the background color varied randomly from trial to trial and the viewing screen remained gray between trials. Because the color red attenuates processing in the transient/magnocellular visual system, these results suggest that coordinate spatial processing is dependent on that pathway. Furthermore, such effects do not involve mechanisms of perceptual adaptation that depend on the same color background being present throughout an experiment or for a prolonged period of time. As in earlier experiments, the effects of color condition were the same regardless of which visual field (and hemisphere) received the stimulus information. However, in contrast to the results of earlier experiments, there was no significant interaction of task and visual field.

Evidence that orthotopic transposition following rat heterotopic small bowel transplantation corrects overgrowth of potentially pathogenic bacteria.

An overgrowth of pathogenic organisms occurs following rat heterotopic small bowel transplantation. This study assessed whether the bacterial microflora return to normal following subsequent orthotopic transposition of the graft. After 14 days the heterotopic graft was placed into continuity following resection of 15 cm of the host midintestinal loop. Quantitative and qualitative analyses of the intraluminal bacteria were performed studying the resected host intestine, the heterotopic graft at 14 days, and the graft 14 days after transposition. A group of normal rats were used as controls. An overgrowth of Staphylococcus epidermidis evident in the heterotopic graft at 14 days returned to a more normal bacterial profile following orthotopic transposition. These findings suggest that early interposition of a small bowel graft into an orthotopic position may prevent an alteration in the small bowel ecology toward potentially pathogenic organisms capable of translocation.

Immunisation of armed service medical personnel against hepatitis B infection.

Clinical and laboratory staff of the Army and RAF medical services at risk of acquiring infection with hepatitis B were immunised against the virus with a recombinant vaccine. Vaccine was administered in Service hospitals and medical centres located throughout the world. After a primary course of vaccine, 73% of personnel developed anti-HBs titres > or = 100 IU/L to hepatitis B surface antigen and were considered protected; 11% were non-responders (anti-HBs < 10 IU/l). A significantly higher proportion of females than males, and vaccinees under 40 years of age, produced a good response. Among those achieving a good response, antibody titres were higher in the younger age group and in females. After a fourth (booster) dose of vaccine, 87.2% of the poor responders and 37% non-responders, developed anti-HBs titres > or = 100 IU/L.

Unfinished business: adult immunization against tetanus.

Where effective child immunization schemes have been established virtually all cases of tetanus occur in persons aged over 50 years. Adult immunization programmes should be introduced in order to protect this age group against the disease.

Effect of small bowel transplantation, denervation and ischaemia on rat intestinal microflora.

The effects of denervation and warm ischaemia on quantitative and qualitative changes in small intestinal microflora following rat heterotopic small-bowel isotransplantation were assessed. Animals with Thiry-Vella fistula, but without transplants, acted as controls. Thirty and 40-fold increases in bacterial colony counts were seen in the isografts compared to controls at 2 and 7 days, respectively (P < 0.05). Aerobic faecal organisms predominated at 2 and 7 days, but an overgrowth of Flavobacterium meningosepticum occurred at 28 days in the transplanted and host bowels. The effect of warm ischaemia on intestinal microflora was assessed by the application of a microvascular clamp to the superior mesenteric artery for 90 min. The effect of denervation was assessed following microsurgical division of all nervous tissue around the superior mesenteric artery. After 7 days, lengths of jejunum and ileum were removed and intraluminal microflora assessed. The number of bacterial colonies isolated from the ileum in the warm ischaemia group was six times greater than the number in the control group, whereas no significant changes were seen in the upper bowel. In contrast, denervation led to a slight, but consistent, decrease in colony counts. These findings suggest that the increase in bacterial numbers in an isografted small bowel primarily results from warm ischaemia rather than from mesenteric denervation, and that physical aspects of the procedure may affect the development of sepsis following small-bowel transplantation.

Prevalence of immunity to hepatitis A in recruits to the British Army and Royal Air Force.

Between 1989 and 1992, 92% of a sample of 2790 Service recruits aged between 17 and 35 years (mean age 19 years 7 months) were found not to be immune to infection by hepatitis A virus. The proportion of males with immunity was consistently greater than that for females. There was a significantly increased probability of immunity if individuals originated from Northern England, the Midlands and Scotland, in particular the suburbs. Among male recruits there were significantly increased probabilities of immunity associated with travel to Southern and Eastern Europe or to the Tropics, and for females with travel to North West Europe or to Southern and Eastern Europe.

Antibiotic release from impregnated pellets and beads.

Antibiotic impregnated beads are being used increasingly in the initial treatment of open fracture wounds, producing high antibiotic levels locally, over the first few days. Pellets were prepared to assess the release of the following antibiotics: benzylpenicillin, flucloxacillin, amoxycillin, amoxycillin-clavulanate (Co-Amoxiclav), ciprofloxacin, imipenem, or gentamicin; the carrier material was either polymethylmethacrylate (PMMA) or plaster of Paris (PoP). Elution of antibiotic over 72 hours from the pellets in vitro was determined using an agar-diffusion microbiologic assay. The initial rapid release of antibiotic lasted 12-24 hours, with release from PoP pellets at least four-fold greater than that from corresponding PMMA pellets. A second phase consisted of a sustained but gradually diminishing elution. The release of antibiotics from PoP pellets compared favorably with that from the PMMA beads currently used. We conclude that PoP pellets may be particularly suitable for short-term applications such as infection prophylaxis in open fractures.

Immunity to tetanus in United Kingdom populations.

As tetanus, a totally preventable disease, is still encountered in the older age group in England and Wales, a study was carried out to assess the state of immunity to the disease in the elderly population. These levels were compared to those in recruits and service personnel in the Army. Elderly patients with underlying disease had lower levels than the elderly who were healthy. When compared with recruit population the elderly group had significantly lower levels of antibody. If tetanus is to be eliminated, an effective programme of immunisation extending throughout life must be ensured.

The effect of rejection and graft-versus-host disease on small intestinal microflora and bacterial translocation after rat small bowel transplantation.

Bacterial translocation and the development of sepsis after small bowel transplantation may be promoted by immunological damage to the intestinal mucosa or by quantitative and qualitative changes in intestinal microflora. This study assessed the effects of rejection, graft-versus-host disease (GVHD) and immunosuppression on intestinal microflora and bacterial translocation after heterotopic rat small bowel transplantation. Isografts, allografts with and without CsA immunosuppression, and the semi-allogeneic parent to the F1 hybrid GVHD model were studied. Intestinal microflora in graft and host loops and bacterial translocation to host organs and the graft mesenteric lymph node were determined. Bacterial colonies were counted and individual colonies identified using API 20E nutrient and fermentation indicator techniques. Colony counts in isografts and allografts were significantly higher than in the native intestine, whereas there was a massive overgrowth in the native intestine in the GVHD group. The species profile for the host and graft loops was similar in animals that had received isografts, allografted animals receiving CsA, and animals undergoing GVHD. However, there was a large increase in Staphylococcus epidermidis in animals with rejection. Bacterial translocation was not detected in isografted animals, but was observed in all other animal groups, with S. epidermidis being the most prevalent organism. These findings demonstrate that rejection and GVHD are associated with shifts in intestinal microflora toward potentially pathogenic organisms and that bacterial translocation into recipient tissues poses a major threat for the development of sepsis.

Acetic acid used for the elimination of Pseudomonas aeruginosa from burn and soft tissue wounds.

Acetic acid was used topically at concentrations of between 0.5% and 5% to eliminate Pseudomonas aeruginosa from the burn wounds or soft tissue wounds of 16 patients. In-vitro studies indicated the susceptibility of P. aeruginosa to acetic acid; all strains exhibited a minimum inhibitory concentration of 2 per cent. P. aeruginosa was eliminated from the wounds of 14 of the 16 patients within two weeks of treatment. Acetic acid was shown to be an inexpensive and efficient agent for the elimination of P. aeruginosa from burn and soft tissue wounds.

Typhoid Vi: a less reactogenic vaccine.

A typhoid vaccine derived from the purified Vi capsular polysaccharide (CPS) antigen of Salmonella typhi was compared with a heat-killed whole-cell typhoid vaccine in 637 healthy male volunteers. The individuals were placed in three groups: group 1 received two doses of heat-killed whole-cell typhoid vaccine, at an interval of 28 days; group 2 received a single dose of typhoid Vi CPS vaccine followed after 28 days by water for injection; and group 3 received water for injection on the first occasion and a single dose of typhoid Vi CPS vaccine 28 days later. Local and systemic adverse reactions were recorded for 5 days following each injection. Subjects receiving the typhoid Vi CPS vaccine complained of fewer local adverse reactions on each of the first 3 days following immunization: on day 1, 18.6% of subjects given typhoid Vi CPS vaccine reported local reactions compared with 59.7% of those receiving heat-killed whole-cell vaccine (P less than 0.001). The percentage of subjects receiving the heat-killed whole-cell vaccine who complained of systemic reactions was more than twice that of subjects receiving the Vi CPS vaccine (7.9% and 3.4%, respectively, on day 1; P less than 0.01).

Hospital acquired native valve endocarditis caused by Acinetobacter calcoaceticus and treated with imipenem/cilastin.

A case of hospital acquired endocarditis due to Acinetobacter calcoaceticus in a severely burned patient is presented. Both aortic and mitral native valves were affected and the organism was resistant to most antimicrobial agents.