In vivo visualization of myelin water in brain by magnetic resonance.

We exploit the intrinsic difference in magnetic resonance spin-spin relaxation time, T2, between water associated with myelin sheaths and water in other central nervous system tissue in order to measure myelin water content within any region of an image or to generate indirectly a myelin map of the brain. In normal volunteers, myelin water maps give the expected myelin distribution. In multiple sclerosis patients, lesions exhibit different myelin water contents providing insight into the demyelination process unavailable from conventional magnetic resonance images. In vivo myelin measurement has important applications in the clinical management of multiple sclerosis and other white matter diseases.

Peripheral vision suppression of melatonin.

The suppression of melatonin by bright light is probably mediated by the suprachiasmatic nucleus (SCN) in humans. In animals, SCN cells have broad visual receptive fields, suggesting that peripheral bright light could be effective for melatonin suppression. Twelve healthy subjects were subjected to 1000 lux illumination for 2 hr from 0100 to 0300 on two occasions: once lighting the central visual field 5 degrees from the center of gaze and once lighting the peripheral visual field 60 degrees lateral to the direction of gaze. Six subjects were observed on a third occasion in dim light. The three conditions differed significantly, with less melatonin secreted in 1000 lux, but melatonin levels with central and peripheral illumination did not differ. This suggests that phototherapy using bright light in the visual periphery may be effective.

[Comparative studies of the paraspecific immunostimulation (paramunization) by bacterial lysates in bacterial infection models and in the cytotoxicity test]. / Vergleichende Untersuchungen über die paraspezifische Immunstimulierung (Paramunisierung) durch Bakterienlysate in bakteriellen Infektionsmodellen und im Cytotoxizittstest.

Bacterial lysates of different bacterial strains (E. coli, B. bronchiseptica, P. haemolytica) were prepared by heating, acid- and alkaline-hydrolysis. Lysates were tested for their immunostimulating effect in bacterial infection models and with chromium 51 test demonstrating spontaneous (natural) cytotoxicity. Lysate production was standardized by protein- and Lps-determination. The alkaline-hydrolysis reduced toxicity of Lps and increased the content of soluble bacterial protein. Heating and acid-hydrolysis did not alter bacterial suspensions with respect to Lps-toxicity and protein-content. Mice infected with P. aeruginosa, P. multocida, E. coli and L. monocytogenes (5-10 LD50) had a significantly longer survival time after prophylactic immunostimulation with bacterial lysates than control animals. No protection was observed in immunostimulated mice infected with Erysipelothrix rhusiopathiae. In the Pseudomonas infection model, bacterial lysates prepared by alkaline-hydrolysis had a 10 times higher immunostimulating effect than lysates prepared by acid-hydrolysis or heating. Bacterial lysates stimulated spontaneous cytotoxicity of natural mouse peritoneal killer cells after intraperitoneal application. Whole bacterial lysates had a higher NK-activity as their corresponding purified lipopolysaccharide portion.

Influence of stimulation parameters on auditory stimulus processing in schizophrenia and major depression: an auditory evoked potential study.

The influence of stimulation frequency and stimulus intensity on the auditory evoked potential components N1 and P2 was investigated in schizophrenic and major depressive patients. The findings in the patients were compared with those in normal controls. At a high stimulation frequency the amplitude of N1 was enhanced in both schizophrenic and major depressive patients; the latency of N1 increased only in the schizophrenic patients. These changes may be related to impairments of auditory input control and processing in these diseases. In the schizophrenic patients, P2 latency was prolonged under treatment with high-potency neuroleptic drugs.

Alcohol and anxiety reduction in female social drinkers.

The present study used a 3 X 2 factorial design to investigate effects on assertive behavior and social anxiety of different doses of alcohol and individual differences in female social drinkers. Contrary to previous findings with men, a dose-dependent effect of alcohol was not found during the social interaction task. The high dose had mixed effects, reducing anxiety on some but not other dependent measures. The moderate dose resulted in significantly less assertiveness and increased heart rate during the social interaction, in high-tolerant subjects. Expectancies about intoxication failed to show significant effects. Of the individual difference variables, only acute tolerance significantly influenced alcohol's effects on anxiety. Alcohol did not reduce self-awareness.

Effects of hyperinsulinism and of diabetes on proteoglycans of the intervertebral disc in weanling sand rats.

Weanling sand rats (Psammomys obesus) develop hyperinsulinemia or diabetes or both, if fed a standard laboratory diet without a supplement of fiber rich salt bush. The annuli fibrosi of hyperinsulinemic or diabetic animals, which are still hyperinsulinemic, show a slight but statistically significant increase in chondroitin sulfate and a lesser, statistically nonsignificant increase in keratan sulfate. Possible causes of these changes are discussed and the likelihood of a role of hyperinsulinism in their production is pointed out.

The effect of alcohol on self-evaluation and perception of negative interpersonal feedback.

Recent theories of alcohol use and misuse assume that alcohol alters cognitive-perceptual mediating processes that indirectly reduce emotional distress. One view is that alcohol enhances perceptions of control and power. Alternatively, it has been suggested that alcohol is used to reduce self-awareness, perceptions of negative feedback and negative self-evaluations. The purpose of this study was to test these two hypotheses. Forty men, all college students, participated in the study and were randomly assigned to the four conditions in a 2 X 2 balanced placebo design. Subjects interacted with a woman confederate at two points in the procedure: first under positive feedback conditions and then, after beverage consumption, under negative feedback conditions. Both sequences were videotaped and eventually viewed by the subjects. Before and after each interaction period and after the videotape procedure, subjects completed rating forms which assessed their self-perceptions. Whereas perceptions of control and power were diminished when subjects were sober, the ratings of intoxicated subjects remained stable after they received negative interpersonal feedback. Alcohol impaired the perception of negative feedback and reduced negative evaluations of the videotaped sequences.

Intraocular pressure response to inversion.

Intraocular pressure (IOP) response to hanging completely head-down (inversion) was measured in 26 healthy young subjects. Systolic and diastolic blood pressure (BP) were also recorded. From the standing position, subjects were rotated 180 degrees and suspended by the ankles from a gravity inversion device. IOP and BP were measured in the standing position, immediately upon inverting, 3 min after inverting, immediately on return to the standing position and 3 min later. Subjects remained at rest during the test. Mean standing right eye IOP of 16.4 mm Hg and left eye IOP of 15.9 mm Hg increased to 34 and 31 mm Hg, respectively. Mean standing BP of 110/77 mm Hg increased to 130/90 mm Hg. Both IOP and BP remained elevated during inversion and decreased to near original values on return to the standing position. IOP significantly increases when the posture changes from standing to hanging completely head-down.

Growth characteristics of Saccharomyces cerevisiae and Aspergillus nidulans when biotin is replaced by aspartic and fatty acids.

When either aerobic or anaerobic cultures of Saccharomyces cerevisiae were supplemented with aspartic and fatty acids in place of biotin, stationary phase populations were very small compared with those obtained in the presence of biotin. Similarly, these acids failed to fulfil the role of biotin-requiring strain of Aspergillus nidulans. Furthermore, a requirement for saturated fatty acid was found with anaerobically cultured S. cerevisiae. Cells were fragmented when biotin was replaced by aspartic and oleic acids alone, while cellular integrity was maintained, but with only slight growth, when biotin was replaced by oleic and palmitic acids together with aspartate. The importance of biotin in the growth of A. nidulans was particularly pronounced in the presence of glucose. In a medium containing glucose, growth ceased when biotin was replaced by aspartate and Tween 80 (a source of saturated and unsaturated fatty acids), but such replacement permitted a very small amount of growth to occur in the absence of glucose.

A novel mechanism of resistance to penicillin-gentamicin synergism in Streptococcus faecalis.

A patient with enterococcal endocarditis, who relapsed after repeated courses of apparently adequate treatment with ampicillin plus gentamicin, was subsequently cured with ampicillin-tobramycin therapy. The organisms isolated from this patient were strains of Streptococcus faecalis that were resistant to penicillin (or ampicillin)-gentamicin synergism but not to penicillin (or ampicillin)-tobramycin synergism. The mechanism of resistance in these strains appears to be related to a specific defect in the intracellular uptake of gentamicin (but not tobramycin) in the presence of penicillin.

Pleiotropic aspartate taxis and serine taxis mutants of Escherichia coli.

Mutants that at one time were thought to be specifically defective in taxis toward aspartate and related amino acids (tar mutants) or specifically defective in taxis toward serine and related amino acids (tar mutants) are now shown to be pleiotropic in their defects. The tar mutants also lack taxis toward maltose and away from Co2+ and Ni2+. The tsr mutants are altered in their response to a variety of repellents. Double mutants (tar tsr) fail in nearly all chemotactic responses. The tar and tsr mutants provide evidence for two complementary, converging pathways of information flow: certain chemoreceptors feed information into the tar pathway and others into the tsr pathway. The tar and tsr products have been shown to be two different sets of methylated proteins.