Tracer kinetic modeling of the 5-HT1A receptor ligand [carbonyl-11C]WAY-100635 for PET

[Carbonyl-11C]WAY-100635 is a promising PET radioligand for the 5-HT1A receptor, having demonstrated more favorable characteristics for in vivo imaging than the previously available [O-methyl-11C]WAY-100635. The current study evaluates different tracer kinetic modelling strategies for the quantification of 5-HT1A receptor binding in human brain. Mathematical modelling of the carbonyl-labeled radiotracer is investigated using compartmental structures, including both plasma input and reference tissue approaches. Furthermore, the application of basis function methods allows for the investigation of parametric imaging, providing functional maps of both delivery and binding of the radioligand. Parameter estimates of binding from normal volunteers indicate a low intra- versus a high intersubject variability. It is concluded that a simplified reference tissue approach may be used to quantify 5-HT1A binding either in terms of ROI data or as parametric images.     

Neural networks: a bridge between neuroscience and psychology

Between the anatomy and physiology of neurons on the one hand, and the study of perception and personality on the other, there is a vast gap in our understanding. Although, today, most neuroscientists say it is axiomatic that the phenomena of mind result from the operation of the brain, they could not tell you how.     

Identification of epitopes of fibronectin attachment protein (FAP-A) of Mycobacterium avium which stimulate strong T-cell responses in mice

The T-cell response to fibronectin attachment protein (FAP-A) in BALB/c and B10.BR mice was examined. Both strains developed strong T-cell responses to FAP-A, directed to single, unique epitopes. T cells from mice infected with Mycobacterium avium responded to FAP-A, suggesting a possible role in a protective immune response.     

Intracranial aneurysms

MR angiography provides a rapid, accurate, and extremely flexible noninvasive evaluation of intracranial aneurysms without the cost and risk of conventional angiography. TOF and phase contrast techniques each have specific advantages and disadvantages that can be selectively exploited to optimize aneurysm evaluation. Present indications for MR angiography in aneurysm evaluation include: (1) the presence of incidental findings on a CT or MR examination that suggest the possibility of aneurysm (Figs. 7 and 8), (2) when angiography is contraindicated or when the risk is too high, (3) non-invasive follow-up of patients with known aneurysms, (4) patient refusal of contrast angiography, and (5) evaluation of patients with specific clinical symptoms (i.e., third cranial nerve palsy) or patients with non-specific subacute symptoms in whom an aneurysm might explain the clinical presentation. Although MR angiography certainly can detect aneurysms with a high rate of sensitivity and specificity, detailed decision analyses generally have not supported the overall benefit of this type of screening. Future technical advances as well as advances in the overall understanding of aneurysms may one day prove unequivocally the benefit of MR angiography in screening high-risk patient groups. MR angiography has not yet been clinically evaluated as a tool in the evaluation of acute subarachnoid hemorrhage. Potential obstacles to such an evaluation include the clinical instability of SAH patients, limited spatial resolution of the MR angiography acquisitions, the potential for subarachnoid blood or focal intraparenchymal hematomas to obscure or mimic small aneurysms, and the unreliability of MR angiography in demonstrating vasospasm. Currently these factors continue to provide an integral role for contrast angiography in aneurysm evaluation.     

Bone alkaline phosphatase and collagen markers as early predictors of height velocity response to growth-promoting treatments in short normal children

OBJECTIVE: A number of long-term research studies are in progress to evaluate the effects of treatment with GH on growth and final height in children with short stature but no demonstrable abnormality of GH secretion. Such treatment is invasive, expensive and carries some risk to the child. An early indication of growth response would allow restriction of treatment to those children most likely to benefit, but anthropometric measurements are relatively subjective, insensitive and imprecise. The aim of this study was to evaluate bone alkaline phosphatase, procollagen Type I C-terminal propeptide, procollagen Type III N-terminal propeptide and the cross-linked carboxy-terminal telopeptide of Type I collagen as early biochemical predictors of height velocity response to growth-promoting treatments in short normal children. DESIGN: A prospective intervention study, partially placebo controlled on a double blind basis. PATIENTS: Fifty healthy children with familial short stature or constitutional delay in growth and puberty (8 girls, 42 boys, ages 5.5-16.5 years and all either prepubertal (45) or in very early puberty (5 boys) at the start of treatment) were treated with placebo (6), GH alone (32), GH plus oxandrolone (8) or GH plus testosterone (4). MEASUREMENTS: Bone alkaline phosphatase and the collagen markers were measured at the start of treatment and 3 months later. Height velocity was calculated at the start of treatment and again after one year. RESULTS: Pre-treatment biochemical marker concentrations did not predict height velocity response after one year. Increments in all markers after 3 months were significantly correlated with height velocity increments after one year of treatment, the highest correlations being observed for bone alkaline phosphatase (r = 0.67, P < 0.0001) and procollagen Type III N-terminal propeptide (r = 0.57, P < 0.0001). Highly significant correlations (P < 0.0001) were also observed between bone alkaline phosphatase and procollagen Type I C-terminal propeptide (r = 0.55) and between procollagen Type III N-terminal propeptide and the cross-linked carboxy-terminal telopeptide of Type I collagen (r = 0.62). Multiple linear regression with stepwise selection of variables identified bone alkaline phosphatase and procollagen Type III N-terminal propeptide as the only two independent variables that contributed significantly to the prediction of height velocity response after one year (analysis of variance, P < 0.0001). Together they predicted 59% of the variability in height velocity response after a year. CONCLUSIONS: The best early predictors of height velocity response were bone alkaline phosphatase (a protein found in hypertrophic chondrocytes in the epiphyseal growth plate, in calcifying matrix vesicles and in mature osteoblasts) and procollagen Type III N-terminal propeptide, a marker of interstitial fibril biosynthesis in soft tissues. Using these markers, GH treatment could be targeted to those children most likely to benefit in the medium term.     

Effects of group discussion and guided patient care experience on nurses'' attitudes towards care of patients with AIDS

An in vivo study was carried out to determine if capacitive coupled electrical stimulation increased the rate of recovery of strength of regenerate bone produced as a result of lengthening by the Ilizarov technique. Thirty-four adult male beagles underwent a right tibial mid-diaphyseal corticotomy, followed by a 5-day delay, and then 21 days of lengthening (1 mm/day). At the start of the post-distraction period (day 27), stimulation (3-6.3 V peak to peak, 5-10 mA root-mean-square at 60 kHz) was applied for 28 days to one group. The nonstimulated group (n = 17) underwent a 28-day period with no stimulation. From each group, four tibiae were prepared for histology; both ends of the remaining bones were embedded in polymethylmethacrylate and tested in torsion (internal rotation at 4.7 degrees/sec) until failure. Statistically significant changes included a 37% lower maximum torque capacity and a 40% decrease in strain energy to failure in the stimulated group compared with the nonstimulated group. The findings are supported by measured trends to a lower modulus of rigidity (37% decrease) and a smaller percentage of active osteoid perimeter (20% decrease) for the stimulated group. The experimental data suggest that when this dose of capacitive coupled electrical stimulation is applied to the regenerating bone created during distraction osteogenesis, it delays the recovery of bone strength compared with an untreated control.