Flow characteristics and exchange in complex biological systems as observed by pulsed-field-gradient magnetic-resonance imaging.

Water flow through model porous media was studied in the presence of surface relaxation, internal magnetic field inhomogeneities and exchange with stagnant water pools with different relaxation behavior, demonstrating how the apparent flow parameters average velocity, volume flow and flow conducting area in these situations depend on the observation time. To investigate the water exchange process a two component biological model system consisting of water flowing through a biofilm reactor (column packed with methanogenic granular sludge beads) was used, before and after a heat treatment to introduce exchange. We show that correction of the stagnant fluid signal amplitude for relaxation at increasing observation time using the observed relaxation times reveals exchange between the two fractions in the system. Further it is demonstrated how this exchange can be quantified.

Characteristic regional cerebral blood flow patterns in anorexia nervosa patients with binge/purge behavior.

OBJECTIVE: The authors' goal was to investigate the effect of imagining food on the regional cerebral blood flow (rCBF) of anorexia nervosa patients with and without habitual binge/purge behavior. METHOD: The subjects included seven female patients with purely restrictive anorexia, seven female patients with anorexia and habitual binge/purge behavior, and seven healthy women. Single photon emission computed tomography examination was performed before and after the subjects were asked to imagine food. Changes in rCBF count ratios (percent change) were then calculated and compared. The subjects were also asked to assess their degree of fear regarding their control of food intake. RESULTS: The anorexia nervosa patients with habitual binge/purge behavior had a significantly higher percent change in the inferior, superior, prefrontal, and parietal regions of the right brain than the patients with purely restrictive anorexia and the healthy volunteers. The patients with habitual binge/purge behavior also had the highest level of apprehension in regard to food intake. CONCLUSIONS: Specific activation in cortical regions suggests an association between habitual binge/purge behavior and the food recognition process linked to anxiety in patients with anorexia nervosa.

Effect of stimulus length on nasalance scores.

OBJECTIVE: Nasalance measures were compared for speech stimuli of four different lengths. DESIGN: The standard for comparison was a 44-syllable passage. The 44-syllable passage was compared to a 17-syllable passage, a 6-syllable sentence, and a 2-syllable word. All stimuli were devoid of nasal consonants and were composed only of low pressure consonants and vowels. SETTING: Academic and clinical craniofacial center. SUBJECTS: The subjects were 20 children at risk for velopharyngeal dysfunction and 5 children without history of communication disorder. MAIN OUTCOME MEASURE(S): The main outcome measures were the nasalance scores associated with speech samples of different lengths. RESULTS: The results showed that comparable measures of nasalance can be obtained using stimuli as short as a six-syllable sentence. Both the 17-syllable and the 6-syllable stimulus achieved high criterion validity, indicating that stimuli of that length could be substituted for the longer 44-syllable passage. The two-syllable word, however, had significantly lower criterion validity and could not be used to obtain valid estimates of nasalance. CONCLUSION: Valid assessment of nasalance can be achieved with speech samples as short as six syllables.

[Possible mechanisms of hematoma formation in the urinary tracts in a patient with idiopathic thrombocytopenic purpura].

A 30-year-old female was admitted to our hospital complaining of hematuria and right flank pain in September, 1987. She had been diagnosed idiopathic thrombocytopenic purpura in 1980, and had similar symptoms before. Hematoma in the right ureter was demonstrated by retrograde pyelography and CT-scanning, and these symptoms improved within one month. Each activity of plasma clotting factors was within normal limits. Enzymatic studies of the urine revealed low values of plasmin-, urokinase-, and kallikrein-like activities in both excerbation and remission. These hemorrhagic tendencies might have been the result of marked thrombocytopenia: After bleeding into the urinary tracts began, the bleeding would tend to form hematoma because of elevated clotting activity; then hematoma would grow due to decreased urine fibrinolytic activities. This suggested that a decline of fibrinolysis in urine might have a promoting effect on the process of hematoma formation.