On the Shift from Anticipatory Heart Rate Deceleration to Acceleratory Recovery: Revisiting the Role of Response Factors

The influence of inducing motor responses of low and high force at different times in the cardiac cycle was examined. A handgrip response was used which allowed the separation of response initiation from response completion. Based on earlier work, we expected initiation, rather than completion, to initiate poststimulus cardiac acceleration. We also thought that preparation for a high force response might alter preparatory changes of interbeat interval differently from preparation for a low force response. Fifteen college-aged male subjects performed a warned reaction time task in which a visual stimulus signalled a handgrip requiring either a high or a low force to close. NoGo trials in which an inhibit signal was presented occurred on 12% of the trials. Stimuli occurred either on the R-wave of the electrocardiogram or 300 ms later. Reaction speed was varied in different trial blocks by rewarding response times of 200 ms (+/- 50 ms), 300 ms, or 400 ms. Results based on the timing of response initiation were essentially identical to those based on the timing of response completion. High force relative to low force was associated with both earlier response initiation and earlier cardiac acceleration. Force did not alter preparatory cardiac deceleration. Force and response speed did, however, alter the level of heart rate after response occurrence. Thus, response initiation (or an earlier response process) appears to induce a cardiac acceleration whose level is influenced by the speed and force of the motor response.     

Cost effectiveness of vaccination against pneumococcal pneumonia

We used cost-effectiveness analysis to examine the medical-care costs of vaccination against pneumococcal pneumonia in relation to its effects on health. Vaccination could add a year of healthy life among all age groups for about $4,800 in net medical-care costs. Cost-effectiveness ratios vary according to the age of the person vaccinated--from $1,000 per year of healthy life for an adult 65 years old or older to $77,000 per year of healthy life for a child between the ages of two and four. These ratios may change substantially with variations in such factors as the cost of vaccination, the duration of immunity, the efficacy and composition of the vaccine, and the percentage of pneumonia that is pneumococcal. This analysis has particular relevance for the Medicare program, since present legislation excludes coverage of most immunizations and other preventive services. Provision of pneumococcal vaccine to the elderly and inclusion of the vaccine as a Medicare benefit merit serious consideration.     

Human herpesvirus type 6 reactivation after haematopoietic stem cell transplantation

Human herpesvirus type 6 (HHV6) is known to reactivate after hematopoetic stem cell transplantation (HSCT) and has been suggested to be associated with increased mortality and severe clinical manifestations, including graft versus host disease (GvHD). The exact etiological role of HHV6 reactivation in increased morbidity and mortality after HSCT remains unclear. This review will focus on the current available evidence of HHV6 reactivation after HSCT and its immuno-modulatory capacities, with particular emphasis on the severe complication GvHD. At present, no effective specific antiviral treatment for HHV6 reactivation has been identified. The currently available antiviral agents are outlined, as well as possible future strategies for the treatment of HHV6 reactivation. Non-toxic, specific treatment or prevention of HHV6 reactivation might improve the safety and efficacy of the HSCT procedure.     

Immunogenetic studies in families with rheumatoid arthritis and autoimmune thyroid disease.

HLA and Gm typing were carried out in 16 families. Seven families included 10 sib pairs with rheumatoid arthritis (RA) and autoimmune thyroid disease (ATD) respectively, and nine families included 16 sib pairs with RA and circulating thyroid autoantibodies respectively. Eight, 11, and seven sib pairs with either RA or clinical or immunological evidence of ATD shared none, one, and two HLA haplotypes respectively, and two, seven, and two informative sib pairs shared none, one, and two Gm haplotypes respectively. This random haplotype sharing of HLA and Gm haplotypes suggests that non-HLA, non-Gm linked genes are likely to be involved in any genetic predisposition common to RA and ATD.     

Journal Club. HIV-associated bacterial pneumonia

Bacterial pneumonia is the most common cause of death from pneumonia in patients with HIV disease, causing greater mortality than Pneumocystis carinii pneumonia. The challenge for the clinician evaluating the HIV-infected patient with pneumonia is to quickly distinguish clinically among all possible causes and to initiate therapy based on the most likely diagnosis. While an understanding of typical clinical and radiographic presentations is essential, bronchoscopy is the preferred test for reliably identifying the causative organism.     

Genetics of rheumatoid arthritis

The haplotype sharing distribution in affected sib pairs are used to demonstrate the linkage of a susceptibility gene for rheumatoid arthritis (RA) to the HLA region. Family and population studies suggest heterogeneity in the etiology of RA.     

Molecular epidemiology of pneumococcal colonization in response to pneumococcal conjugate vaccination in children with recurrent acute otitis media

A randomized double-blind trial with a 7-valent pneumococcal conjugate vaccine was conducted in The Netherlands among 383 children, aged 1 to 7 years, with a history of recurrent acute otitis media. No effect of vaccination on the pneumococcal colonization rate was found. However, a shift in serotype distribution was clearly observed (R. Veenhoven et al., Lancet 361:2189-2195, 2003). We investigated the molecular epidemiology of 921 pneumococcal isolates retrieved from both the pneumococcal vaccine (PV) and control vaccine (CV) groups during the vaccination study. Within individuals a high turnover rate of pneumococcal restriction fragment end labeling genotypes, which was unaffected by vaccination, was observed. Comparison of the genetic structures before and after completion of the vaccination scheme revealed that, despite a shift in serotypes, there was clustering of 70% of the pneumococcal populations. The remaining isolates (30%) were equally observed in the PV and CV groups. In addition, the degree of genetic clustering was unaffected by vaccination. However, within the population genetic structure, nonvaccine serotype clusters with the serotypes 11, 15, and 23B became predominant over vaccine-type clusters after vaccination. Finally, overall pneumococcal resistance was low (14%), and, albeit not significant, a reduction in pneumococcal resistance as a result of pneumococcal vaccination was observed. Molecular surveillance of colonization in Dutch children shows no effect of pneumococcal conjugate vaccination on the degree of genetic clustering and the genetic structure of the pneumococcal population. However, within the genetic pneumococcal population structure, a clear shift toward nonvaccine serotype clusters was observed.     

Single fiber electromyography in chronic progressive external ophthalmoplegia

We have reviewed the electromyographic (EMG) studies of 17 patients with chronic progressive external ophthalmoplegia (CPEO). In 13 of 17 patients, conventional concentric needle EMG demonstrated a "myopathic" pattern, usually predominating in the shoulder muscles. Single-fiber EMG showed increased jitter and/or blocking in at least one muscle in 13 of 16 patients. Jitter was increased in the frontalis muscle in 10 of 13 patients and in an arm muscle in 5 of 12. When both muscles were tested, jitter was greater in the frontalis muscle in 5 patients and in the arm muscle in 2. These observations demonstrate that it may be difficult to distinguish myasthenia gravis from CPEO by EMG. The frequency with which abnormal jitter is found in CPEO suggests that, in addition to a mild generalized myopathy, a primary defect in neuromuscular transmission may be present.