Selection of task-dependent diffusion filters for the post-processing of SPECT images

Iterative reconstruction from single photon emission computed tomography (SPECT) data requires regularization to avoid noise amplification and edge artefacts in the reconstructed image. This is often accomplished by stopping the iteration process at a relatively low number of iterations or by post-filtering the reconstructed image. The aim of this paper is to develop a method to automatically select an optimal combination of stopping iteration number and filters for a particular imaging situation. To this end different error measures between the distribution of a phantom and a corresponding filtered SPECT image are minimized for different iteration numbers. As a study example, simulated data representing a brain study are used. For post-reconstruction filtering, the performance of 3D linear diffusion (Gaussian filtering) and edge preserving 3D nonlinear diffusion (Catté scheme) is investigated. For reconstruction methods which model the image formation process accurately, error measures between the phantom and the filtered reconstruction are significantly reduced by performing a high number of iterations followed by optimal filtering compared with stopping the iterative process early. Furthermore, this error reduction can be obtained over a wide range of iteration numbers. Only a negligibly small additional reduction of the errors is obtained by including spatial variance in the filter kernel. Compared with Gaussian filtering, Catté diffusion can further reduce the error in some cases. For the examples considered, using accurate image formation models during iterative reconstruction is far more important than the choice of the filter.     

Mental disorders in elderly suicide

The purpose of this study was to investigate the prevalence and comorbidity of current mental disorders defined by DSM-III-R among elderly suicide victims and to compare them with the mental disorders among younger victims. Using a psychological autopsy method, we collected comprehensive data on all suicides in Finland during 1 year. Retrospective Axis I-III consensus diagnoses were assigned to a random sample consisting of 43 victims aged 60 years or over and 186 victims aged under 60 from the nationwide suicide population. At least one Axis I diagnosis was made for 91% of the elderly victims. Major depression as the principal diagnosis was more common among the elderly victims. Almost all elderly female victims were major depressives. Psychiatric comorbidity was more common among elderly male than among elderly female victims. More of the elderly victims (88%) than the younger (36%) received Axis III diagnoses. Suicide among the elderly without a diagnosable mental disorder and somatopsychiatric comorbidity seems to be rare.     

Study of the phlebotomines (Diptera, Psychodidae), in area of cutaneous leishmaniasis in the State of Mato Grosso do Sul, Brazil

Interleukin-1 beta (IL-1 beta) significantly inhibits insulin secretion from glucose stimulated islet cells. The mechanism for this inhibition has been hypothesized to be due to stimulation of the inducible form of nitric oxide synthase and a resulting increase in nitric oxide (NO) concentration. Ways to block the effect of IL-1 beta have focused on blocking the binding of IL-1 beta to the IL-1 receptor and the use of antioxidants to neutralize increases in NO. This report focuses on a 33 residue peptide synthesized based on the C-terminal region of the IL-1 beta molecule, a reported binding site of the IL-1 beta molecule, and the redoxcycling antioxidant pyrroloquinoline quinone (PQQ). The 33 residue peptide did not function as an antagonist, but as a weak agonist. High concentrations of PQQ itself inhibited glucose-dependent insulin release while low concentrations did not. PQQ had no effect on the actions of IL-1 beta. Three isosteric and isomeric analogues of PQQ were also investigated. One of the PQQ isomers had an inhibitory effect on insulin secretion at low concentrations where PQQ had no effect. These results reflect the sensitivity of islets to oxidative stress.     

Bovine mastitis due to algae of the genus Prototheca

A survey of the prevention of disability policy and activities in a random sample of 200 ILEP assisted projects was conducted in 1995. This was followed by a workshop of field experts in different aspects of prevention of disability who work in different geographical regions. The survey findings and state of current knowledge on prevention of disability were reviewed during the workshop and recommendations on the planning, implementation, and evaluation of simple and effective prevention of disability developed. Prevention of disability includes complex activities, such as nerve decompression and reconstructive surgery, however these recommendations focus on the simple techniques and approaches which can be implemented through leprosy control programmes, primary health care and community-based rehabilitation. These recommendations have been approved by the ILEP Medical Commission, and reported in the ILEP Medical Bulletin (N degree 8, December 1995).     

Simultaneous creep and oxidation of an Fe-1 Wt pct Al alloy at 973 to 1073 K

Studies of the simultaneous creep and oxidation of an Fe-lwt pct Al alloy at constant stresses of 16 to 26 MN/m² in the temperature range 973 to 1073 K have shown that the steady state creep obeys a power law. The stress exponentn was found to be 6.9 for creep in an argon atmosphere(Po₂ = 10^-3 mbar). Values of the apparent activation energy for creep were in the range 225 to 351 kJ/mol and appeared to be dependent on theP _{o 2} of the test environment. Oxidationstrengthening (è decreasing) o°Curred at 998 K but only atP _{o 2} = 10^-3 mbar and was primarily due to intergranular oxidation and the mechanical constraint of a strongly adherent scale. Oxidationweakening (è increasing), however, o°Curred at 973 to 1073 K in environments of the lowestP _{o 2} (10^-9 and 10^-5 mbar) and in the highestP _{o 2} (162 to 1013 mbar). The factors contributing to weakening are believed to be oxidation-induced vacancies, weakly adherent scales and the loss of solute strengthening aluminum through selective oxidation. M. H. SHAHHOSSEINI, formerly a Research Student at the University of Manchester.     

Maximal functional capacity in patients with endomyocardial fibrosis

We evaluated objectively the cardiocirculatory dysfunction of patients with EMF, and related the functional class (FC-NYHA) to the data obtained by analysis of maximal functional capacity. We studied 55 subjects, divided into three groups: group 1 (G1) 21 (38.1%) normal persons, group 2 (G2) seven (12.7%) patients with EMF who were in FC I or II, and group 3 (G3) 27 (49%) patients in FC III or IV. Maximal oxygen consumption (VO2max) and O2 pulse index (PO2max) were obtained using a Beckman computerized gas analyser. The mean values were significantly different among the three groups. We conclude that the greater the clinical impairment, the greater the alterations that occur in the indices of cardiac function.     

Critical test evaluation (1977-1992) of drug efficacy against endoparasites featuring benzimidazole-resistant small strongyles (population S) in Shetland ponies

Several compounds (n = 13 single or combinations; most at therapeutic dosages) were evaluated between 1977 and 1992 in critical tests (n = 91) against benzimidazole (BZ) resistant small strongyles (Population S) and several other species of internal parasites in Shetland ponies, mostly under 1 year old. The closed breeding herd, from which the test ponies were selected, had been treated every 8 weeks with cambendazole (CBZ) for 4 years (1974-1978) and oxibendazole (OBZ) for 14 years (1978-1992). Published field test data (1974-1992) on older ponies in the herd showed BZ resistance of small strongyles. Average efficacies in the present critical tests against small strongyles for OBZ (n = 59 animals) were high in early years (95% or higher), but gradually declined to a low of 1% in 1991. Side-resistance of small strongyles was evident in critical tests (n = 1-6/single drug or combination) for several other BZs and a pro-BZ; ivermectin and piperazine were highly active, but pyrantel pamoate exhibited weak activity. BZ resistance was evident for six small strongyle species (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocylus nassatus, Cylicostephanus calicatus, Cylicostephanus goldi, and Cylicostephanus longibursatus). Activity on bots, ascarids, large strongyles, and pinworms was essentially as expected, indicating no drug resistance.     

Follicle stimulating hormone (FSH) activates the p38 mitogen-activated protein kinase pathway, inducing small heat shock protein phosphorylation and cell rounding in immature rat ovarian granulosa cells

This study investigates the possibility that FSH activates the p38 mitogen-activated protein kinase (MAPK) pathway in immature granulosa cells (GC). FSH induced the phosphorylation (activation) of p38 MAPK as evaluated by immunoprecipitation and by phosphorylation-specific immunoblotting. FSH-induced phosphorylation of p38 MAPK was blocked by pretreatment with the protein kinase A (PKA) inhibitor H89 and mimicked by the cAMP generating agonist forskolin, indicating that FSH-induced cAMP production and PKA activation are necessary and sufficient for the activation of p38 MAPK in GC. The small heat shock protein HSP-27 comprises a downstream phosphorylation target for the p38 MAPK pathway. FSH-induced phosphorylation of HSP-27 was blocked by pretreatment with the p38 MAPK inhibitor SB 203580, indicating that p38 MAPK activation is necessary for FSH-induced HSP-27 phosphorylation. FSH-induced GC rounding/aggregation was blocked by pretreatment with SB 203580 indicating that p38 MAPK activation is necessary for FSH-induced GC cell shape change. The results of these experiments show that the p38 MAPK pathway is activated in GC in response to FSH in a cAMP/PKA-dependent manner, and that p38 MAPK activity is required for FSH-induced HSP-27 phosphorylation as well as rounding/aggregation in GC.