Simulations and measurements of bilamellar streak tubes

Particle-in-cell simulations of a picosecond-resolution bilamellar streak tube are described, and the results are compared to measurements of key specifications. A novel laser diode setup with a small focal spot has been used to investigate the sensitive width of the photocathode, a previously unpublished parameter. Simulations have shown that the tubes, while performing at high spatiotemporal resolution, have electron efficiencies of just 1.6% due to the action of the temporal focusing electrode, contributing to an effective dynamic range of around 10. The virtual photocathode created by this electrode was predicted to be 144 µm, in excellent agreement with the measured width of 136 µm. A simple method to improve the tube's dynamic range by narrowing the slit width is investigated and shown to have a modest simulated improvement.

Postsurgical use of amplatzer septal occluder in cyanotic patients with pulmonary atresia/intact ventricular septum: significance of cor triatriatum dexter and dilated right atrium

Percutaneous closure of secundum atrial septal defects (ASDs) has been shown to be safe and effective. However, its role after surgery in patients with cyanotic congenital heart disease who may have associated cor triatriatum dexter and a dilated right atrium has not been established. This article reports on successful closure in such patients, including precautions and results.

Social network methods for endemic foci of syphilis: a pilot project

BACKGROUND

Social network methods have improved our understanding of sexually transmitted disease transmission dynamics, and may be of use in routine field operations for partner notification.

GOAL

To augment traditional syphilis-control activities with social network methods in an Atlanta area with high syphilis morbidity.

STUDY DESIGN

Disease investigators conducted interviews, used network diagrams to prioritize their work, and relied on network connections for finding hard-to-reach persons.

RESULTS

A total of 396 contacts were elicited from 48 infected and 50 uninfected persons. The cumulative prevalence of syphilis was 12.6%, and 24 persons infected with HIV were identified. Network methods disclosed a large, interconnected group (276 persons) characterized by high network centrality and the substantial presence of small, interactive subgroups (microstructures).

CONCLUSION

The network approach is a feasible field technique, and can identify core groups involved in the intense transmission of syphilis. The targeted, network-based approach may be useful in attempts to eliminate syphilis.

The use of a single case design to investigate the effect of a pre-performance routine on the water polo penalty shot

The pre-performance routine (PPR) is proposed to assist the performance of closed skills by enhancing concentration (Crews and Boutcher, 1987) and the recall of optimal psychological and physiological states (Cohn, 1990). A multiple-baseline-across-individuals design was utilised to assess the effect of PPRs on water polo penalty shot performance. Three experienced male water polo players were assisted in designing a personalised multi-component PPR, which was rehearsed in accordance with a training program, and implemented prior to performing penalty shots in simulated trials. Mean performance scores increased for all players between pre and post intervention phases. A Split Middle analysis (White, 1974) further described performance trends and changes. Players 1 and 2 reversed negative baseline trends of -1.071 and -1.031 to positive post intervention trends of +1.011 and +1.011, producing respective positive changes in slope of +1.08 and +1.042. Player 3's baseline trend of +1.008 was reversed post intervention to -1.004, causing a negative change in slope of -1.012. Respective ratios of 1.38, 1.36 and 1.20, suggest a positive change in trend level immediately following PPR introduction. Binomial tests revealed improvements in all participant performances between stages (p<0.001). Results are reviewed in light of previous research and the utilisation of single-subject designs is discussed.

Molecular pharmacology of UK-118, 434-05, a permanently charged amlodipine analog

We studied the effects of UK-118, 434-05, a permanently charged form of amlodipine, on recombinant smooth muscle and cardiac L-type calcium channels to determine the distinct modulatory properties of the ionized form of amlodipine. We found that the short distance between the permanent charge group and the active dihydropyridine (DHP) ring of UK-118, 434-05 reduces the potency of this compound as an inhibitor of smooth muscle (alpha(1c-b)) L-type channels, and is similar to the effects of other charged DHP derivatives on cardiac (alpha(1c-a)) L-type channels. However, we found surprisingly that the tonic block of cardiac (alpha(1c-a)) L-type channels was more pronounced than the tonic block of smooth muscle (alpha(1c-b)) L-type channels. This result contrasts with the previously reported subunit-specificity of neutral DHP compounds, and suggests that interactions between the amlodipine charge group and site(s) on the L-type channel alpha1 subunit distinguish the action of charged from neutral DHPs and may contribute to amlodipine's unique pharmacological profile.

Atypical aortic coarctation and innominate artery stenosis associated with clubfoot and lower leg ischemia in an infant

We report findings in a male infant born with talipes equinovarus and ischemic necrosis of the left lower leg and foot associated with atypical coarctation of the ascending aorta and stenosis and hypoplasia of the proximal innominate artery. We hypothesize that a vasculopathy of unknown etiology occurred in utero that resulted in ascending aortic arch coarctation and innominate artery stenosis. The presence of a thrombus in the coarcted segment suggests that one or more emboli could have been responsible for vascular compromise and subsequent clubfoot deformity and lower leg ischemia. Alternatively, a vasculopathy similar to that hypothesized as occurring in the aorta might also have occurred in the left anterior tibial artery, causing structural deformity and soft tissue ischemia of the left lower leg and foot. We believe that this is the first report of this association of findings.

Hereditary hyperparathyroidism-jaw tumor syndrome: the endocrine tumor gene HRPT2 maps to chromosome 1q21-q31

The syndrome of hereditary hyperparathyroidism and jaw tumors (HPT-JT) is characterized by inheritance, in an autosomal dominant pattern, of recurrent parathyroid adenomas, fibro-osseous tumors of the mandible and/or maxilla, Wilms tumor, and parathyroid carcinoma. This syndrome is clinically and genetically distinct from other endocrine neoplasia syndromes and appears to result from mutation of an endocrine tumor gene designated "HRPT2." We studied five HPT-JT families (59 persons, 20 affected); using PCR-based markers, we instituted a genomewide linkage search after excluding several candidate genes. Lod scores were calculated at various recombination fractions (theta), penetrance 90%. We mapped HRPT2 to the long arm of chromosome 1 (1q21-q31). The maximal lod score was 6.10 at theta = .0 with marker D1S212, or > 10(6) odds in favor of linkage. In six hereditary Wilms tumor families (96 persons, 29 affected), we found no linkage to 1q markers closely linked with HRPT2 (lod scores -15.6 [D1S191] and -17.8 [D1S196], theta = .001). Nine parathyroid adenomas and one Wilms tumor from nine members of three HPT-JT families were examined for loss of heterozygosity at linked loci. The parathyroid adenomas and Wilms tumor showed no loss of heterozygosity for these DNA markers. Our data establish that HRPT2, an endocrine tumor gene on the long arm of chromosome 1, is responsible for the HPT-JT syndrome but not for the classical hereditary Wilms tumor syndrome.

Toxic health effects including reversible macrothrombocytosis in workers exposed to asphalt fumes

We investigated an outbreak of irritative and neurotoxic symptoms associated with exposure to asphalt fumes in a commercial lighting factory; 27 symptomatic female workers were clinically assessed including hematologic testing. When compared with a laboratory reference group (n = 107), the workers' mean platelet volume (MPV) was significantly higher and mean platelet count was lower (p = 0.013 and p = 0.048, respectively). Five months later, the factory's ventilation system was substantially modified. Follow-up assessments 6 months postmodification on 15 of the original workers documented a significant decline in acute symptoms and a lowering of the subjects' mean MPV towards normal (p = 0.0007 by paired t-test). The findings suggest that reversible macrothrombocytosis (enlarged platelets) can occur among symptomatic workers exposed to asphalt fumes.

Scrapie: Report of an outbreak and brief review

An outbreak of scrapie in western Canada is described. The disease was confirmed in seven sheep, all originating from the same flock; six were Suffolk ewes and one was a Hampshire ewe. The main clinical signs were pruritus with a positive "nibbling reflex", weight loss and seizures precipitated by handling or excitement. At presentation four ewes were between 35 and 38 months of age; two were approximately four years old and the oldest was six years old. No evidence of scrapie was seen in six goats on the original farm. The clinical signs, epizootiology, pathology, and pathogenesis of the disease are reviewed.

Tactile recognition of mirror images by children: intermanual transfer and rotation of the palm

In order to evaluate the importance of the axis of stimulus presentation, inter- and intramanual recognition of mirror pairs was studied with the stimulus materials aligned along the front/back axis (whereas in previous work the mirror pairs were aligned along the left/right axis). Children were allowed to feel shapes with the whole hand, with only four fingers (excluding the thumb), or with only the index finger. After learning with one hand, recognition was tested in experiment 1 with the other hand; after learning with one orientation of the hand (palm down or up), recognition was tested in experiment 2 with the other orientation (palm up or down) of the same hand; after learning with one coronal alignment of the hand (to the left or right), recognition was tested in experiment 3 with the other alignment (to the right or left), but without rotation, of the same hand. Significantly fewer intermanual recognition errors were made on mirror pairs with the materials oriented along the front/back axis than in previous work when oriented along the left/right axis. This supports the suggestion that such errors arise when the stimuli are oriented along the left/right axis during formation of the memory trace. The same trend was unexpectedly obtained for intramanual recognition errors (after rotation of the hand). These errors (after hand rotation) are largely due to coding with respect to the hand; they are reduced when the hand is not aligned with the body axis, since then coding can also occur in relation to the environment.

Why families change pediatricians. Factors causing dissatisfaction with pediatric care

Dissatisfaction with their child's physician sometimes causes parents to transfer to a new provider. We studied the reasons for such transfers from four pediatric practices in Chittenden County, Vermont. Personal qualities of the physician, including the parent's perception of the physician's communication skills, his or her clinical competence, and the apparent level of concern were the most important factors that distinguished satisfied from dissatisfied parents. Structural features, including costs, waiting time, and continuity with the same physician, were less often sources of enough dissatisfaction to produce a transfer. Effectiveness and success in pediatric practice are dependent on competence, communication, and caring.

Changes in chromatin and the phosphorylation of nuclear proteins during heat shock of Achlya ambisexualis

Heat shock led to marked changes in the apparent levels of phosphorylation of nuclear proteins in the fungus Achlya ambisexualis. We characterized these heat shock-induced changes in nuclear proteins on two types of two-dimensional polyacrylamide gel systems. We report here that one of two Achlya H3 histones (H3.1) and also the oomycete histone alpha appear to be highly phosphorylated with heat shock. Additional changes observed in acid-soluble nuclear proteins included an apparent increase in the 32P labeling of a 43,000-molecular-weight protein and the dephosphorylation of a major group of Achlya phosphoproteins in the 30,000-to-32,000-molecular-weight range. The changes in protein phosphorylation were accompanied by striking changes in the morphology of Achlya nuclei. Nuclei in the heat-shocked cells, but not in control cells, exhibited marked chromatin condensation and contained bundles of filaments which were approximately 4 nm in diameter. Concomitantly, the bulk of chromatin from heat-shocked nuclei showed a decreased sensitivity to digestion with the enzyme DNase I relative to chromatin from control cells.

Experimental evaluation of coronary infusates in dogs

In a study involving dogs, a coronary infusate containing a variety of substances including cardiac substrates, metabolic inhibitors, membrane stabilizers, electrolytes, and anticoagulants was evaluated in terms of protection afforded to the myocardium for up to 90 minutes of normothermic anoxic arrest. Electron microscopical studies and tissue adenosine triphosphate measurements revealed this coronary infusate to be considerably beneficial to the myocardium. Infused myocardium was better preserved compared to myocardium that was not infused or infused with two other "control" infusates. The individual components of our infusate are known cardiac preservatives. The rationale for combining a number of them in our infusate is to produce an additive or synergetic effect through beneficial intervention at several points in the cardiac metabolic cycle. This objective appears to have been fulfilled under the conditions of the present experiment.

Corticosteroids in brain tissue

Total corticosteroid concentrations were determined in the plasma and brains of five species: mouse, rat, cat, monkey and man. Corticosteroid concentrations were measured also in the livers of mice, rats and monkeys. Competitive protein binding techniques were validated and used for the tissue corticosteroid assays. In each species the brain corticosteroid value was less than the total plasma corticosteroid level but greater than the presumed unbound fraction of plasma corticosteroids. A clear circadian variation of brain corticosteroid values was found in mice, together with a rapid elevation of the tissue levels in response to stress. Reduction of both plasma and tissue corticosteroid concentrations was observed after adrenalectomy and in response to dexamethasone treatment of mice. Between 24 and 48 h post morten, mouse brain corticosteroid values decreased greatly. In cat, monkey and human brains all regions examined contained approximately equal amounts of corticosteroids. In particular, brain areas which are not involved in pituitary-adrenocortical regulation contained large amounts of corticosteroids.