Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers

Tone recognition is partially subserved by neural activity in the right frontal and primary auditory cortices. First we determined the brain areas associated with tone perception and recognition. This study then examined how regional cerebral blood flow (rCBF) in these and other brain regions correlates with the behavioral characteristics of a difficult tone recognition task. rCBF changes were assessed using H2(15)O positron emission tomography. Subtraction procedures were used to localize significant change regions and correlational analyses were applied to determine how response times (RT) predicted rCBF patterns. Twelve trained normal volunteers were studied in three conditions: REST, sensory motor control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral activation of primary auditory cortices, cerebellum and bilateral inferior frontal gyri. DEC-SMC produced significant clusters in the right middle and inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus and supplementary motor area; the left insula/claustrum; and the left cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a positive correlation in right inferior and middle frontal cortex; rCBF in bilateral auditory cortices and cerebellum exhibited significant negative correlations with RT These changes suggest that neural activity in the right frontal, superior temporal and cerebellar regions shifts back and forth in magnitude depending on whether tone recognition RT is relatively fast or slow, during a difficult, accurate assessment.     

Neuropeptides in the insect brain: a review

Thirty-seven plants are listed, which are used by traditional healers in the central and southern parts of Somalia. For each species are listed: the botanical name with synonyms, collection number, vernacular name, medicinal use, preparation of remedy and dosage. Results of a literature survey are also reported including medicinal use, substances isolated and pharmacological effects. Three plants which should have been included in Part I of the series have been added and some corrections to that paper have been made. With these additions the series comprises 180 different plant species, distributed in 59 plant families.     

The importance of geriatrics to family medicine: a position paper by the Group on Geriatric Education of the Society of Teachers of Family Medicine

The role of geriatrics and geriatricians in family medicine remains unsettled. Despite a rapidly aging population, a tremendous shortage now exists of faculty with interest and expertise in geriatrics. Relatively few family practice residents choose to enter geriatric fellowship programs, and federal funding for such programs has been reduced. Despite accreditation requirements, residency programs are not always able to provide the range of geriatric experiences needed to properly prepare graduates to provide care for the broad range of older patients. Medical students' exposure to geriatrics remains limited. The Group on Geriatric Education of the Society of Teachers of Family Medicine believes that family medicine faculty must recognize and be committed to the notion that geriatrics is integral to family medicine. Both undergraduate and residency training programs should emphasize experience with geriatric patients in multiple settings. In particular, the nursing home should not be the main focus of geriatric training. The small number of certified geriatric faculty will be able to provide leadership, but a broad range of faculty must become involved in teaching geriatrics. Faculty development activities and continuing education programs to foster the necessary expertise will be essential to the accomplishment of this task.     

Oxidation of low density lipoprotein by iron or copper at acidic pH

Oxidized low density lipoprotein (LDL) may play a significant role in atherosclerosis. We have investigated the effect of pH on the oxidation of LDL by iron or copper. When LDL was oxidized by iron in the presence of cysteine in either Hanks' balanced salt solution (HBSS) or Ham's F-10 medium, an acidic pH greatly decreased the lag period and increased the rate of formation of hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and increased its uptake by macrophages. There was a dose-dependent increase of LDL oxidation at acidic pH in the presence of increasing concentrations of cysteine. When LDL was oxidized by copper in HBSS, an acidic pH increased the lag phase before the rapid formation of conjugated dienes, hydroperoxides, and TBARS, but increased its uptake by macrophages. Similar results were obtained using Ham's F-10 medium. Cysteine (100 microM) inhibited the modification of LDL by copper in HBSS at both pH 7.4 and 5.5 As atherosclerotic lesions may be acidic, these observations may help to explain why LDL oxidation occurs locally at these sites.     

Young children''s understanding of pretense expressions of independent agency

Data from the Cancer Registry of Slovenia were used in a cohort study to determine whether the incidence of second primary cancers in patients with first primary breast cancer differs from the incidence expected in the general population. Special interest was given to long-term survivors. The expected numbers of second primary cancers were calculated by multiplying the number of appropriate person-years at risk by the corresponding age- and calendar-period-specific cancer incidence rates for women in Slovenia. The risk of a second primary cancer was expressed as the standardized incidence ratio (SIR). Of the 8,917 patients newly diagnosed in the period 1961-85 and followed-up to the end of 1994, 547 (6.2 percent) developed second primary cancers, whereas 410 (4.7 percent) were expected (SIR = 1.3, 95 percent confidence interval [CI] = 1.2-1.4). The risk was higher among younger patients. In long-term survivors, the risk was increased significantly for second primary cancer of the breast (SIR = 1.4, CI = 1.1-1.7), lung cancer (SIR = 1.6, CI = 1.1-2.3), melanoma (SIR = 2.7, CI = 1.5-4.4) and non-melanoma skin cancers(SIR = 2.0, CI = 1.6-2.4), corpus uteri cancer(SIR = 1.6, CI = 1.2-2.1), ovarian cancer(SIR = 2.3, CI = 1.7-3.0), and thyroid cancer (SIR = 2.5, CI = 1.2-4.6). Our results confirm the findings of several cohort studies carried out in Europe, the United States, and Japan, indicating that breast cancer patients should be monitored carefully for the occurrence of second primary cancers.     

Thermal stability of indium-tin-oxide/n-GaAs Schottky diodes

The thermal degradation of ITO Schottky contacts on GaAs has been studied. The rectifying contacts show rapid degradation with heating and could have serious implications for optoelectronic devices that operate at elevated temperatures.<>     

Pharmacodynamic modeling of the electroencephalographic effects of flumazenil in healthy volunteers sedated with midazolam

The purpose of this study was to model pharmacodynamically the reversal of midazolam sedation with flumazenil. Ten human volunteers underwent four different sessions. In session 1, individual midazolam pharmacokinetics and electroencephalographic pharmacodynamics were determined. In sessions 2 and 3, a computer-controlled infusion of midazolam with individual volunteer pharmacokinetic data was administered, targeting a plasma concentration corresponding to a light or deep level of sedation (20% or 80% of the maximal midazolam electroencephalographic effect) for a period of 210 minutes. After obtaining a stable electroencephalographic effect and constant midazolam plasma concentrations, a zero-order infusion of flumazenil was started until complete reversal of midazolam electroencephalographic effect was obtained. The flumazenil infusion was then stopped and the volunteer was allowed to resedate because of the constant midazolam drug effect. The electroencephalographic response was measured during a 180-minute period and analyzed by aperiodic analysis and fast-Fourier transforms. In session 4, a midazolam plasma concentration corresponding to a deep level of sedation was targeted for 210 minutes to examine for the possible development of acute tolerance. No flumazenil was given in session 4. For a light sedation level, with a mean midazolam plasma concentration of 160 +/- 64 ng/ml, the mean half-life of the equilibration rate constant of flumazenil reversal is 5.0 +/- 2.5 minutes, and the mean effect site concentration causing 50% of Emax is 13.7 +/- 5.8 ng/ml. For a deep level of sedation, with a mean midazolam plasma concentration of 551 +/- 196 ng/ml, the mean half-life of the equilibration rate constant is 3.9 +/- 1.5 minutes, and the mean effect site concentration causing 50% of Emax is 20.6 +/- 6.8 ng/ml. This study provides an estimate of the magnitude of the blood/central nervous system equilibration delay for flumazenil antagonism of midazolam sedation and further defines the usefulness of the electroencephalogram as a measure of midazolam pharmacodynamic effect.