Human V5/MT+: comparison of functional and cytoarchitectonic data

To date, the delineation of the human visual “motion area” still relies on functional paradigms originally devised to identify monkey area MT. Using fMRI, we have identified putative human area V5/MT+ in normals by modelling the BOLD responses to alternating radially moving and stationary dot patterns. Functional activations were compared with cytoarchitectonic probability maps of its putative correlate area hOc5, which was calculated based upon data from histological sections of ten human post-mortem brains. Bilateral visual cortex activations were seen in the single subject dynamic versus stationary contrasts and in the group random-effects analysis. Comparison of group data with area hOc5 revealed that 19.0%/39.5% of the right/left functional activation was assigned to the right/left hOc5. Conversely, 83.2%/53.5% of the right/left hOc5 was functionally activated. Comparison of functional probability maps (fPM) with area hOc5 showed that 28.6%/18.1% of the fPM was assigned to hOc5. In turn, 84.9%/41.5% of the area hOc5 was covered by the respective fPM. Thus, random-effects data and fPMs yielded similar results. The present study shows for the first time the correspondence between the functionally defined human V5/MT+ and the post-mortem cytoarchitectonic area hOc5.     

In situ dormancy of B lymphocytes programmed for an IgE antibody response and their sudden release from unresponsiveness under in vitro conditions

Priming of CBA/J mice with different doses of antigen has aprofound effect on the ratio of IgE versus IgG antibodies appearingupon Immunization. Repeated injections of minute doses induceIgG and high titers of IgE antibodies. Large doses elicit ahigh IgG but a very low IgE antibody titer. In order to studythe modalities for activation and inactivation of IgE-producingB cells, an in vitro culture system was established in whichspleen cells from animals primed with keyhole limpet hemocyaninwere re-stliulated with antigen. In contrast to the expectationfrom the in vivo situation, spleen cells from animals Immunizedwith large doses of antigen and virtually lacking IgE antibodiesproduce high amounts of IgE antibodies upon re-stimulation invitro. The titers in spleen cell cultures from mice primed withminute doses remain proportional to the response measured asserum antibodies. In accordance with the induction of high amountsof IgE antibodies in spleen cell cultures from mice primed withlarge doses, the frequency of IgE antibody-secreting cells wasraised drastically, 1000-fold. The in vitro response is a trueanamnestic response. The sudden appearance in high frequencyof IgE antibody-forming cells among spleen cells isolated fromprimed mice which have high IgG but virtually no IgE antibodytiters is as yet unexplained and the origin of the B memorycells has not yet been traced. The answer might be crucial forour understanding of the down-regulation of the IgE Immune responses.     

Inhibition of the allograft response by donor specific blood transfusion: association with reduced local TH1 cytokines and nitric oxide but enhanced prostaglandin E2 production

BACKGROUND: Donor-specific blood transfusion (DST) may improve allograft survival in human and animal models, but the mechanisms for this graft protective effect are incompletely understood. The sponge matrix allograft model was used to determine if DST induces regulatory factors within the allograft. METHODS: C57BL/6 (H-2b) recipients received donor-specific (DBA/2J, H-2d) or syngeneic (C57BL/6) blood 7 days before sponge matrix allograft (DBA/2J) implantation. Fourteen days postgrafting, the sponge infiltrating cells (SIC) were examined for cytotoxic T cell (CTL) and natural killer (NK) activity, and sponge exudate fluid (SEF) was assessed for nitric oxide (.N=O) and prostaglandin E2 (PGE2) content. Interleukin- (IL) 2, IL-4, IL-10, and interferon-gamma (IFN-gamma) production by SIC was also determined. Recipient splenocytes were simultaneously assessed for anti-donor cytotoxic and proliferative responses and .N=O production. RESULTS: SIC from mice receiving syngeneic transfusions (ST) acquired both CTL and NK activity postgrafting, with maximal activity by day 14. DST suppressed both CTL and NK activity throughout the postgrafting period. Limiting dilution analysis (LDA) of SIC to determine precursor and native CTL frequency showed significantly lower responder cell frequency after DST compared with ST. SEF .N=O levels and SIC production of IL-2 and IFN-gamma in grafted DST mice were significantly lower than in grafted mice receiving ST. No significant amounts of IL-4 and very low levels of IL-10 were produced by SIC from grafted mice after either ST or DST. Conversely, PGE2 content of sponge fluid and serum from DST mice was higher than in mice receiving ST. Antigen stimulated splenocyte proliferation and CTL development assessed by LDA were also inhibited by DST. CONCLUSIONS: Reduction in local TH1 cytokines, absence of detectable TH2 cytokines, with enhanced PGE2 and depressed .N=O were observed in the local graft environment after DST. These data support the hypothesis that DST induces donor-specific intragraft suppressor factors, accompanied by reduced local and systemic immune activation.     

Respiratory syncytial virus genotypes and disease severity among children in hospital

OBJECTIVES: To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection. PATIENTS AND METHODS: Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation). RESULTS: Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease. CONCLUSIONS: During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease.     

Total but not resting energy expenditure is increased in infants with ventricular septal defects

OBJECTIVE: The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants. METHODS: Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance. RESULTS: No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group. CONCLUSIONS: REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation.     

Tapping movements according to regular and irregular visual timing signals investigated with fMRI

Whole-head functional MR images were acquired while 10 subjects were asked to tap with their right index finger in synchrony with a visual stimulus appearing regularly with a frequency of 1.5 Hz, or irregularly with a mean frequency of 1.5 Hz. Performance data show that during regular tapping most taps were close to stimulus onset. However, when the subjects paced their tapping according to the irregular stimuli, most taps appeared about 300 ms after the onset of the pacing stimuli. Comparing the brain activations resulting from regular tapping with those from irregular tapping, we found increased activation in left precuneus only. Comparing irregular versus regular tapping shows increased activity in right cerebellar nuclei and vermis, left ventrolateral thalamus, left sensorimotor cortex, left and right pre-SMA and left SMA proper. These results show that during irregular pacing the motor areas are more strongly activated than during regular pacing. In addition, further neural systems are involved in the motor control during irregular pacing: cerebellar vermis and a cerebello-thalamo-cortical system. The latter is supposedly involved in error correction in the context of visually guided movements.     

Pneumatic compression hemodynamics in total hip arthroplasty

A crossover study was performed to evaluate the effect of several pneumatic compression devices and active dorsoplantar flexion in 10 patients who underwent total hip arthroplasty. Using the Acuson 128XP/10 duplex ultrasound unit with a 5-MHz linear array probe, peak venous velocity and venous volume were assessed above and below the greater saphenous vein and common femoral vein junction. A computer generated randomization table was used to determine the order of the test conditions. The pneumatic compression devices evaluated included two foot pumps, one foot and calf pump, one calf pump, and three calf and thigh pumps. Statistical analyses included analysis of variance and analysis of variance with covariance between devices and patients. The covariates tested were the baseline measurements and the order in which the devices were tested. Differences between devices relate in part to the frequency and rate of inflation and the location and type of compression. Pulsatile calf and foot and calf pneumatic compression with a rapid inflation time produced the greatest increase in peak venous velocity, whereas compression of the calf and thigh showed the greatest increase in venous volume. Because patient and nursing compliance is essential to the success of mechanical prophylaxis for thromboembolic disease, the more simple, yet efficacious, devices that are easier to apply and less cumbersome appear to have a greater likelihood of success. In the active and alert patient, active dorsoplantar flexion should be encouraged.