Phenotype screening for genetically determined age-onset disorders and increased longevity in ENU-mutagenized mice

With the goal of discovering genes that contribute to late-onset neurological and ocular disorders and also genes that extend the healthy life span in mammals, we are phenotyping mice carrying new mutations induced by the chemical N-ethyl-N-nitrosourea (ENU). The phenotyping plan includes basic behavioral, neurohistological, and vision testing in sibling cohorts of mice aged to 18 months, and then evaluation for markers of growth trajectory and stress response in these same cohorts aged up to 28 months. Statistical outliers are identified by comparison to test results of similar aged cohorts, and potential mutants are recovered for re-aging to confirm heritability of the phenotype.     

Dynamic liver imaging with iron oxide agents: Effects of size and biodistribution on contrast

In vivo effective relaxation rates in normal rat liver were evaluated for four dextran coated iron oxide agents: monocrystal-line iron oxide nanocolloid (MION) with a mean particle diameter of 3.9 nm, a polycrystalline agent (PION) with a larger mean diameter of 12 nm, and these two agents labeled with the asialofetuin (ASF) protein for high hepatocytic receptor binding affinity (MION-ASF and PION-ASF). Using echo planar imaging at 2 Tesla, dose response was measured with high temporal resolution for 3 h after injection of agent, and by comparing with relaxivities in vitro and in brain, dominant in vivo contrast phenomena were elucidated. While transverse relaxivity for PION-ASF exceeded that for MION-ASF by almost a factor of 2 in solution, relaxation rates in vivo became equivalent. Liver relaxation using non-ASF agents was consistent with rapid water exchange between vascular and extravascular compartments, which dominated relaxation as a result of agent accumulation in Kupffer cells.     

Relationships with the medical staff and aspects of satisfaction with care expressed by parents of children with cancer

Seventy-four parents of children with cancer were asked to characterize the behavior of medical staff members with whom they interacted. Seven empirically distinct dimensions of staff behavior relevant to their relationships with parents were identified, including information transmission, clarity and honesty of communication, acceptance of parental efficacy, resolution of conflicts, personal contact with parents, empathy with the child, and staff competence. With respect to their experiences with the treatment of their child, parents also were asked to indicate their satisfaction with the medical staff in terms of changes in their respect and/or anger for the medical staff, changes in feelings about doctors, support received from doctors and nurses, and stress resulting from tense relations with the staff. The seven dimensions of parent-staff relationships were used as predictors in a series of multiple regressions employing these satisfaction measures as criteria. The overall quality of the parent-staff relationship was best predicted by positive personal contact. The strongest predictor of whether or not parents felt increased anger was staff empathy with child. Increased respect for the medical staff was predicted by a combination of information transmission and perception of staff competence. Experience of support by parents was best predicted by information transmission and staff acceptance of parental efficacy in treatment and decision making. This complex pattern supports the usefulness of disaggregating measures of staff behavior and parent satisfaction when examining the relations between medical consumers and service providers.The data were gathered with the participation and support of a major university medical center and children's hospital, and a parent self-help organization, SHARE: Families of Children with Cancer. This report, and the larger study, is part of an action-research effort conducted jointly by SHARE, the hospital staff, and the investigators.     

A randomized controlled trial of an intervention designed to improve the care given in general practice to Type II diabetic patients: patient outcomes and professional ability to change behaviour

AIM: Our objective was to evaluate the effect of training in a patient- centred intervention for GPs and practice nurses on outcomes for patients with Type II diabetes. METHODS: We carried out a randomized controlled trial within general practices as the basis for randomization and a before-and-after design for measures of patient outcome. A parallel process study examined the use of the method by professionals. The study was carried out in 29 general practices in South Glamorgan who had participated for at least 2 years in a local scheme of audit and CME in relation to Type II diabetes care. The subjects were 252 Type II diabetic patients recruited by 15 experimental and 14 control practices. The main outcome measures were changes in glycosylated haemoglobin, patient satisfaction with care and treatment, functional health status and professional ability to apply the intervention. RESULTS: Professionals adopted the innovative method with enthusiasm, but after 2 years only 19% continued to apply the method systematically. The trial was, therefore, unable to demonstrate significant biochemical or functional improvements. This highlights the need to understand the factors associated with professional uptake and subsequent ability to sustain changes in behaviour. CONCLUSIONS: The efficacy of this behavioural intervention remains unproved, despite its acceptability to professional staff. Detailed and prolonged development and testing of behavioural interventions is an essential first step before embarking on randomized controlled trials which involve complex behavioural changes in professionals or patients.      

Extracellular alkaline-acid pH shifts evoked by iontophoresis of glutamate and aspartate in turtle cerebellum.

The effect of glutamate and aspartate iontophoresis on extracellular pH was investigated in the turtle cerebellum in vitro. Both amino acids produced a rapid alkaline transient, typically followed by a prolonged acidification. These responses could be evoked in all layers of the cerebellum. Transition from bicarbonate to N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered media amplified the pH shifts. Similar alkaline-acid transients could be evoked in the molecular layer by electrical stimulation of the parallel fibers or the ipsilateral peduncle, or by superfusion of glutamate or aspartate. However, no alkaline shifts were evoked in the granular layer by either parallel fiber or peduncle stimulation. In contrast, the iontophoretically induced alkaline shifts were largest in the granular layer. Compared with the stimulus-evoked alkalinizations, the iontophoretic alkaline shifts were relatively insensitive to Mn2+ or Cd2+. These data suggest that the activity-dependent alkalinization of brain extracellular space is generated by a bicarbonate-independent mechanism related to excitatory synaptic transmission. The results are consistent with a flux of hydrogen ions through cationic channels, but do not support a direct role for voltage-dependent Ca2+ channels. In view of the sensitivity of ion channels to changes in external pH, and the magnitude of the amino acid-induced pH shifts, these results indicate that extracellular pH could play an important modulatory role in excitatory synaptic transmission.     

Extracellular alkaline shifts in rat hippocampal slice are mediated by NMDA and non-NMDA receptors.

1. The pharmacology of synaptically evoked extracellular alkaline shifts was studied in the CA1 area of rat hippocampal slices. 2. Stimulus-evoked alkalinizations were unaffected by 2-amino-5-phosphonovalerate (APV) (20 microM). 3. 6-Cyano-7-nitro-nitroquinoxaline-2,3-dione (CNQX) (10 microM) inhibited the alkalinizations. In the continued presence of CNQX, an APV-sensitive, picrotoxin-insensitive, alkaline shift was elicited in low Mg2+ media. 4. Antidromic stimulation produced small alkaline shifts in comparison with orthodromic activation. 5. Our results demonstrate that in the hippocampal CA1 region, synaptically evoked alkalinizations can arise through both N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors. These responses cannot be explained by cell firing per se.     

Validity of testing alanine aminotransferase in refrigerated whole blood

Alanine aminotransferase (ALT) was tested in the sera and plasma of in-line segments as well as the main bags of whole blood units collected from blood donors. The purpose of this study was to evaluate the stability of enzyme activity during blood storage when the analysis of ALT is postponed over weekends or holidays. In addition, when validation of a particular result is requested, an in-line segment may be convenient for confirmatory testing. While a dilutional effect was found, the anticoagulant in the main collection bag was not shown to have affected enzyme activity. During storage the mean enzyme concentration decreased. Appropriate plasma ALT cutoffs for respective time periods during storage were calculated to compensate for downward drift. This correction prevented the use of the blood units (40% of total) that would erroneously have appeared transfusable if the serum cutoff had been used. If the Day 0 plasma cutoff was used throughout the total storage time period, 14 percent of the blood would erroneously have appeared transfusable.     

Mr perfusion studies with t1-weighted echo planar imaging

The T₁ perfusion model has worked well in brain functional studies where flow changes are measured. Using selective and nonselective inversion pulses, a new method has been developed to study steady-state brain blood flow. The authors obtained flow-sensitive images using selective inversion and flow-insensitive images using nonselective inversion. Subtraction of flow-insensitive images from flow-sensitive images gave us flow-weighted images with good gray-white flow contrast in cortical gray matter as well as in the thalamus and basal ganglia. Fitting T₁S of flow-insensitive and flow-sensitive images allowed us to obtain preliminary results of brain blood flow maps. Two specific problems can seriously affect the accuracy of the brain blood flow values and the gray-white flow contrast of brain blood flow maps. These are the problems of the partial volume effect of CSF and gray matter, and the difference between blood T₁ and white matter T₁. The authors discuss in detail the character of these problems and present a number of approaches to manage such problems.