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.     

Maximum cardiac output during incremental exercise by first-pass radionuclide ventriculography

A flow injection hydride atomic absorption spectrometric (FI-HAAS) method was developed for determining selenium in human milk and whole blood after microwave digestion of the sample. The sample (2 mL human milk or 0.25 mL blood) was introduced into the microwave vessel with 1.5 mL HNO3 and 0.25 mL H2O2 and 300 W (4 min) and 600 W (4 min) were applied. The digestion was completed by heating to 140 degrees C (2-3 h). Se (VI) was reduced to Se (IV) with hydrochloric acid. The instrumental conditions for FI-HAAS (concentrations of reducing agent and carrier acid, flow rate of argon carrier gas, and sample volume injected) were optimized. The detection limit of the proposed method was 0.23 ng/mL (assay) or 115 pg Se (absolute) in biological samples (1.15 ng/mL milk, 10.4 ng/mL blood). The precision values were 5.0% for milk and 4.0% for blood. The accuracy was evaluated with 2 reference materials, National Institute of Standards and Technology Non-Fat Milk Powder (found: 104.3 +/- 7.2 ng/g, certified: 110 +/- 10 ng/g) and Whole Blood Seronorm (found: 81 +/- 7.3 ng/mL, reference: 83 +/- 4 ng/mL). The results show the suitability of the method for selenium determination in human milk and whole blood. The method was applied to whole blood samples obtained from pregnant women and to human milk.     

Family, peer, and neighborhood influences on academic achievement among African-American adolescents: one-year prospective effects

Using a 1-year prospective design, this study examined the influence of family status variables (family income, parental education, family structure), parenting variables (maternal support and restrictive control), peer support, and neighborhood risk on the school performance of 120 African American junior high school students. In addition to main effects of these variables, neighborhood risk was examined as a moderator of the effects of parenting and peer support. Family status variables were not predictive of adolescent school performance as indexed by self-reported grade point average. Maternal support at Time 1 was prospectively related to adolescent grades at Time 2. Neighborhood risk was related to lower grades, while peer support predicted better grades in the prospective analyses. Neighborhood risk also moderated the effects of maternal restrictive control and peer support on adolescent grades in prospective analyses. These findings highlight the importance of an ecological approach to the problem of academic underachievement within the African American Community.     

Estimating eye care workforce supply and requirements

PURPOSE: To estimate the workforce supply and requirements for eye care in the United States. METHODS: Three models were constructed for analysis: supply of providers, public health need for eye care, and demand (utilization) for eye care. Ophthalmologists, other physicians, and optometrists were included in the models. Public health need was determined by applying condition-specific prevalence and incidence rates from population-based and other epidemiologic studies. Demand was determined by use of national databases, such as the National Ambulatory Care Survey, National Hospital Discharge Survey, and Medicare Part B. Time requirements for care were obtained through a stratified sample survey of the membership of the American Academy of Ophthalmology. RESULTS: Under modeling assumptions that use a work-time ratio of one between optometrists and ophthalmologists and between specialist and generalist ophthalmologists, a significant excess of eye care providers exists relative to both public health need and demand. Changes in the work-time ratio, work-hours per year per provider, care patterns for the same condition, or other factors could significantly reduce or eliminate the surplus relative to need. CONCLUSION: If optometrists are the preferred primary eye care provider, ophthalmologists would be in excess under all demand scenarios and all need scenarios where the optometrist to ophthalmologist work-time ratio is greater than 0.6. No excess of ophthalmologists would exist if ophthalmologists are the preferred primary eye care provider. Data on the appropriate work time ratio will help refine estimates of the imbalance between supply and requirements.     

Neuropeptide Y and luteinizing hormone releasing hormone synergize to stimulate the development of cellular follicle-stimulating hormone in the hamster adenohypophysis

Luteinizing hormone releasing hormone (LHRH) stimulates the development of cellular FSH immunoreactivity in the perinatal hamster adenohypophysis. Because neuropeptide Y (NPY) can act directly on rat adenohypophysial cells to stimulate FSH and LH release and potentiate the stimulatory effect of LHRH on FSH and LH release, we investigated the effects of NPY alone and in combination with a low, ineffective dose of LHRH on inducing cellular FSH immunoreactivity in the neonatal hamster adenohypophysis. Neonatal female pituitary glands were grafted beneath the right renal capsules of hypophysectomized-ovariectomized adult hamster hosts with a catheter implanted in the external jugular vein. After treatment, hosts were decapitated and graft tissue was stained for FSH and LH immunoreactivity. The mean percentage of adenohypophysial cells that stained for FSH was low (2.8%) in grafts in hosts infused continuously with heparinized saline vehicle for 7 days. In other hosts, peptides were pulsed through the catheter every 12 h for 7 days. The mean percentage of FSH cells also was low after pulsing 6 ng LHRH or 2 micrograms NPY but increased substantially when the two peptides were pulsed simultaneously. No differences in the mean percentage of LH cells existed between any of the groups. The results demonstrate that NPY and LHRH can synergize to induce cellular FSH immunoreactivity in the neonatal female hamster.     

Developing competency-based perioperative orientation programs

Ensuring the competency of staff members at all levels of practice is an ongoing challenge for perioperative clinical educators. The authors developed a competency-based orientation program using AORN's perioperative nursing competency statements as a conceptual framework. The model also incorporates requirements from external regulatory agencies (e.g., the Joints Commission on Accreditation of Healthcare Organizations) that influence the direction of health care institutions seeking accreditation. The model provides the components necessary to validate the orientation of perioperative staff members and the delivery of comprehensive nursing care in perioperative settings.     

Production of hydroxyl radicals in contracting skeletal muscle of cats

Reactive oxygen species increase during exhaustive contraction of skeletal muscle, but characterization of the specific species involved and their rates of production during nonexhaustive muscle contraction have not been investigated. We hypothesized that the production rate of hydroxyl radical (.OH) increases in contracting muscle and that this rate is attenuated by pretreatment with deferoxamine (Def) or dimethylthiourea (DMTU). We measured the rate of production of .OH before, during, and after 5 min of intermittent static contraction of the triceps surae muscles in cats (n = 6) using the formation of p-, m-, and o-tyrosines by hydroxylation of phenylalanine. L-Phenylalanine (30 mg/kg i.v.) was administered to each animal 3 min before contraction. Blood samples were collected from the popliteal vein 1 min before contraction; 1, 3, and 4.5 min during contraction; and 1 min after contraction. During and after contraction, the cumulative production rates of p-, m-, and o-tyrosines were elevated by 42.84 +/- 5.41, 0.25 +/- 0.04, and 0.21 +/- 0.03 nmol.min-1.g-1, respectively, compared with noncontracting triceps surae muscles. Pretreatment with Def (10 mg/kg i.v.; n = 5) or DMTU (10 mg/kg i.v.; n = 4) decreased the cumulative rates of production of p-, m-, and o-tyrosines during and after contraction. Additionally, the rate of tyrosine production increased in proportion to the percentage of maximal tension developed by the triceps surae muscles. These results directly demonstrate that .OH is produced in vivo in the skeletal muscle of cats during intermittent static contraction and that production can occur before the onset of fatigue.     

Prednisolone therapy of idiopathic feline lower urinary tract disease: a double-blind clinical study

A double-blind clinical study was performed to evaluate prednisolone as treatment for idiopathic feline lower urinary tract disease. No differences in response were observed in prednisolone- and placebo-treated cats.     

Apoptosis in the failing human heart

BACKGROUND: Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS: Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS: Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS: Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.