CD4(+) T cell-mediated control of a gamma-herpesvirus in B cell-deficient mice is mediated by IFN-gamma

The lack of B cells and antibody does not prevent mice from dealing effectively with a pathogenic gamma-herpesvirus. Both CD4(+) and CD8(+) T cells contribute to the control of virus replication in the respiratory tract, with the depletion of either lymphocyte subset leading to increased titers in the lung. However, the further neutralization of IFN-gamma diminishes the effectiveness of the CD4(+) T cell response and causes substantially increased mortality. Experiments with bone marrow radiation chimeras indicate that the immune CD4(+) effectors operate optimally when there is the potential for direct interaction with virus-infected targets expressing MHC class II glycoproteins, suggesting that the IFN-gamma produced by these lymphocytes is functioning at short range. The numbers of latently infected cells in the spleens of carrier mice are also significantly increased by the concurrent depletion of both the CD4(+) population and IFN-gamma. These experiments raise the possibility that the defective control of intercurrent gamma-herpesvirus infections in patients with AIDS not only is due solely to the absence of helper T cells but also reflects the loss of an important set of CD4(+) effectors.     

Instillagel: an anaesthetic antiseptic gel for use in catheterization

Instillagel is a prefilled syringe containing lignocaine 2% and chlorhexidine 0.25% in a sterile lubricant gel. It is available in two sizes, 11 ml and 6 ml, for male and female catheterization respectively, and for intermittent self-catheterization. It has been used successfully for these purposes for many years, and its usage in the community setting is increasing. It is used for surface anaesthesia by many UK urologists. It is easily applied by both nurse and patient and remains the product of choice when performing indwelling catheterization. It also has an important role in stricture therapy where patients require extra lubrication for the passage of a catheter or an anaesthetic effect to provide patient comfort following the procedure. Instillagel has the added benefit of an antibacterial effect due to its chlorhexidine content.     

Uptake and Persistence of the Vertebrate Pesticide, Sodium Monofluoroacetate (Compound 1080), in Plants of Cultural Importance

Field research was undertaken to determine if naturally occurring plants utilised by a Maori (the indigenous people of New Zealand) community for food and medicine would take up the toxin sodium monofluoroacetate (Compound 1080) from baits used to control the brush-tailed possum Trichosurus vulpecula. Single baits were placed at the base of individual plants of two species, pikopiko (Asplenium bulbiferum) and karamuramu (Coprosma robusta). Plants were sampled at various times up to 56 days, and samples analyzed for 1080 content. No 1080 was detected in any of the pikopiko samples, whereas 1080 was detected in karamuramu, at a maximum concentration of 5 ppb after 7 days, and 2.5 ppb after 14 days. This concentration decreased to zero at 28 days, indicating that while karamuramu was shown to take up 1080, it was not persistent. The results of this study suggest there is negligible risk of humans being poisoned by consuming plants that have taken up 1080 from baits. To allay community concerns that minute concentrations of 1080 might influence the medicinal properties of plants, it is suggested a withholding period of 30 days after 1080 control operations could be adopted.     

Decomposition-based quantitative electromyography: effect of force on motor unit potentials and motor unit number estimates

Decomposition-based quantitative electromyography (DQEMG) allows for the collection of motor unit potentials (MUPs) over a broad range of force levels. Given the size principle of motor unit recruitment, it may be necessary to control for force when using DQEMG for the purpose of deriving a motor unit number estimate (MUNE). Therefore, this study was performed to examine the effect of force on the physiological characteristics of concentric needle- and surface-detected MUPs and the subsequent impact on MUNEs obtained from the first dorsal interosseous (FDI) muscle sampled using DQEMG. Maximum M waves were elicited in 10 subjects with supramaximal stimulation of the ulnar nerve at the wrist. Intramuscular and surface-detected EMG signals were collected simultaneously during 30-s voluntary isometric contractions performed at specific percentages of maximal voluntary contraction (MVC). Decomposition algorithms were used to identify needle-detected MUPs and their individual MU firing times. These MU firing times were used as triggers to extract their corresponding surface-detected MUPs (S-MUPs) using spike-triggered averaging. A mean S-MUP was then calculated, the size of which was divided into the maximum M-wave size to derive a MUNE. Increased levels of contraction had a significant effect on needle- and surface-detected MUP size, firing rate, and MUNE. These results suggest that force level is an important factor to consider when performing quantitative EMG, including MUNEs with this method.     

Clinical implications of splenium magnetic resonance imaging signal changes

BACKGROUND: Magnetic resonance imaging (MRI) may show discrete splenium abnormalities; however, the implications of this radiologic finding are unclear. OBJECTIVE: To describe causes, clinical presentations, and prognoses of midline splenium changes evident on MRI. DESIGN: Retrospective case series. SETTING: Teaching hospital. PATIENTS: Medical records of 9 patients with MRI-noted splenium changes were studied; 60 additional published cases were accessed. INTERVENTIONS: Sixty-nine cases were reviewed. MAIN OUTCOME MEASURES: Clinical and imaging findings, causes, and prognosis. RESULTS: Confusion (35 patients), ataxia (25 patients), and recent seizure (23 patients) were common. Causes included alcohol use, infections, hypoglycemia, trauma, salt abnormalities, and seizure. Twenty-eight patients had complete resolution, 23 improved, and 1 died. Diffusion-weighted imaging showed splenium abnormalities the best. Eleven of 12 patients showed decrease in apparent diffusion coefficient. Most improved clinically, as did their subsequent MRI studies. CONCLUSIONS: Midline splenium changes are commonly seen on MRI diffusion-weighted imaging sequences. Multiple causes can result in splenium changes. Physicians should evaluate for glucose and electrolyte abnormalities, seizure risk, ongoing infectious or parainfectious process, and traumatic causes.     

Partial seizure provoked by hyperbaric oxygen therapy: possible mechanisms and implications

Hyperbaric oxygen treatment (HBO2) is used commonly for treatment of bone and soft-tissue radiation necrosis. It may be a potential therapy for radiation necrosis seen after brain irradiation. HBO2 risks include generalized tonic-clonic convulsions. We report a patient after resection of anaplastic astrocytoma and 5,580 cGy of total external-beam radiation treatments with brain radiation necrosis who underwent HBO2 therapy and developed a partial seizure during treatment. Mechanisms and implications are discussed.