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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 469 records · Page 26Linked to original sources
PubMedDate not supplied

Behavioral assessment of aging in male Fischer 344 and brown Norway rat strains and their F1 hybrid.

Male Fischer-344 (F344) and Brown Norway (BN) rats 7-, 13-, and 24-month-old and their F344 x BN hybrid (F1) 7-, 13-, 24- and 31-month-old were tested in a behavioral battery (15-min and 24-h locomotor activity, inclined screen, rod suspension, rotorod, shock-motivated learning in a straight runway and 14-unit T maze). Necropsy was performed 3 days later and the results rated for pathology (i.e., severity of lesions observed). Age-related performance declines were observed in all behavioral tests except 15-min locomotor activity. Strain effects were observed in 15-min (BN more active than F344 and F1) and 24-h locomotor activity test (F344 more active than BN and F1 strains); rotorod performance (F344 fell more than BN and F1); and in all measures [errors (E), runtime (RT)], shock frequency (SF), and duration (SD)] in the 14-unit T maze (F344 worse than BN, BN worse than F1). T maze performance of 31-month-old F1 rats was deficient in RT, SD, and SF but E performance was equivalent to that of 7-month-old F1 rats. In a second experiment, only 7- and 31-month-old F1 rats were tested in the 14-unit T maze and the results obtained in Experiment 1 were replicated. Gross necropsy revealed age and strain effects in the number of lesions observed and the mean ratings of pathology. The 24-month-old F344 rats exhibited the greatest number of lesions and had the highest ratings (generally observed as chronic nephrosis and enlarged spleens characteristic of mononuclear cell leukemia). BN rats exhibited a high incidence of hydronephrosis at all age levels. While experiencing less obvious pathology, F1 rats experienced a significant number of lesions in the 31-month-old group. Pathology ratings correlated with behavioral performance but only for a few tests (e.g., SD and RT in 14 unit T maze in 24-month-old F344). Thus, behavioral performance declined with age and the battery of tests differentiated between the strains tested (in general, F344 worse than BN; BN worse than F1). The correlation of pathology ratings at gross necropsy with behavior did not appear to be systematic, suggesting that morbidity was not responsible for the age-related performance declines. However, more extensive evaluation of the relationship of age-related changes in health status to behavior with larger samples of rats is suggested.

Aging↗
PubMedDate not supplied

Chronic nimodipine treatment in aged rats: analysis of motor and cognitive effects and muscarinic-induced striatal dopamine release.

Nimodipine is a calcium channel blocker reported to have beneficial effects on treatment of ischemic damage as well as the potential for retarding aspects of brain and behavioral aging when provided chronically to rats. We treated aged male F-344 rats (24 months) with nimodipine in SC pellets in the following doses: 0 (controls), 20 mg (low-dose), or 40 mg (high-dose) replenished after 6 weeks. After 3 months of treatment, surviving rats and a group of young controls (6 months) were tested in a behavioral battery involving exploratory activity in an open field and in a runwheel cage as well as motor abilities required for remaining on an inclined screen, suspended from a wire, and balanced on a rotorod. Rats were also pretrained for one-way active avoidance in a straight runway before being trained in a 14-unit T maze. During 20 trials rats were required to negotiate each of 5 maze segments within 10 s to avoid foot shock (0.8 mA). Nimodipine treatment produced no significant effects on body weight, food intake, or survival of aged rats. Analysis of behavioral results indicated significant age-related decline in performance of all tasks except in open-field behavior. Nimodipine treatment had no significant effects on behavioral performance of aged rats except in maze learning. Rats on the high-dose regimen performed significantly better than aged controls in the maze. The results indicate that chronic nimodipine treatment of aged rats had no toxic effects and might be beneficial for preventing age-related decline in learning performance.

Aging↗
PubMedDate not supplied

Relationship of hematological variables to learning performance in aged Fischer-344 rats.

The relationship between hematological variables and the ability to perform behaviorally in two learning tests was evaluated in male F344 rats aged 22-24 months. Rats were screened for ability to meet criterion for learning one-way active avoidance in a straight runway task. Rats failing to meet criterion were given no further testing and were assigned to Group 1 (G1). Rats meeting criterion were tested in a 14-unit T-maze (2 days, 10 trials/day). Failure to negotiate the T-maze within 600 s on any three trials resulted in assignment to Group 2 (G2) with no further testing. Rats successfully completing both tasks constituted Group 3 (G3). Trunk blood was collected following behavioral testing and was assayed to determine red blood cell count (RBC), hematocrit (HCT), hemoglobin (HGB), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), white blood cell count (WBC), bands (BND), polymorphs (POLY), lymphocytes (LYM), monocytes (MON), and eosinophils (EOS). The combined G1/G2 group had significantly lower RBC, HCT, HGB, and EOS but significantly higher MCV and MCH than G3 rats. Correlation analysis revealed a positive relationship of group membership (i.e., learning test completion) to RBC, HCT, HGB, and EOS, but a negative correlation of group membership to MCH. No significant correlation emerged between any hematological characteristic and performance in either behavioral task. These results suggest that a simple blood test to determine HCT may be a useful screen for removal of moribund rats from aging studies attempting to control for effects of health on behavioral performance in rodent models.

Aging↗
PubMedDate not supplied

Interrater reliability of the Motivation Assessment Scale: failure to replicate with aggressive behavior.

The Motivation Assessment Scale (MAS) was used to identify the variables maintaining aggressive behaviors exhibited by 18 adolescents and adults with severe to profound intellectual disability. Each client was rated by two staff members. A variety of measures were calculated to assess interrater reliability. Pearson coefficients across the 18 pairs of raters ranged from -.667 to .722 with an overall correlation of .034. Five of the 12 positive correlations were significant at the .05 level. Correlations across each of the 16 questions of the MAS ranged from -.337 to .425. None of these correlations were significant. Similarly low reliability was obtained when percentage of agreement measures were calculated, although 8 of the 18 pairs of raters (44.44%) did agree on the source of reinforcement maintaining the client's aggressive behavior. These results suggest that for some individuals the MAS may not represent a viable alternative to more formal functional analysis procedures.

Adolescent↗
PubMedDate not supplied

Background levels of non-ortho-substituted (coplanar) polychlorinated biphenyls in human serum of Missouri residents.

This study characterizes the levels of polychlorinated biphenyls (PCB) congeners PCB 77, PCB 81, PCB 126, and PCB 169, in a group of 150 men and women with no documented exposure to PCBs. Its purpose is to provide current referent levels of coplanar PCBs in Missouri residents and to compare those levels to levels reported in the literature from the United States and other countries. Although this study used an extensive questionnaire assessing potential sources of exposure, no positive relations were found between these exposure sources and participants' PCB levels. The PCB levels for the four congeners measured were lower than any reported in the literature. PCBs 126 and 169 are only two of the dioxin-like congeners; however, their contribution makes up 11% of the total TEQ. Age was significantly related to PCB 126 and PCB 169. For every one-year increase in age, both PCB congeners increased by approximately 0.4 parts per trillion (ppt). There was no gender difference for PCB 126; however, PCB 169 levels were 3 ppt higher in males than females.

Adult↗
PubMedDate not supplied

Arctic willy.

Explore the source record for details and available documents.

Adult↗
PubMedDate not supplied

Congenital cystic adenomatoid malformation of the lung coexisting with recombinant chromosome 18. A case report.

OBJECTIVE: Diagnosis of congenital cystic adenomatoid malformation of the lung (CCAM) in association with recombinant chromosome 18. METHOD: Ultrasound diagnosis of a CCAM and hydrops was made. The mother was known to have a pericentric inversion of chromosome 18 and had a previous pregnancy with a recombinant chromosome 18 (partial deletion of 18p and partial duplication of 18q). Cordocentesis for karyotype was therefore performed. RESULT: Fetal karyotype revealed a recombinant chromosome 18, this time with partial deletion of 18q and partial duplication of 18p. Postmortem confirmed a type III CCAM and a septum primum atrial defect. CONCLUSIONS: Although deletion/duplication of chromosome 18 is commonly associated with a wide variety of anomalies, the association with CCAM is an unusual one. Fetal and parental karyotyping should be considered in cases of CCAM, because fetal therapy is increasingly being considered in these pregnancies. Current management of parents with pericentric inversions must rely on invasive diagnostic testing in the second trimester because predicting the likelihood of an unbalanced karyotype and phenotype in a fetus is difficult.

Adult↗
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The relationship of upper extremity strength to throwing speed.

Cybex II Isokinetic Dynamometer (Lumex Corp. Ronkonkoma, NY) tests for the upper extremity strength of eight professional baseball players, together with radar gun measurements of their individual throwing speeds, were subjected to statistical analysis. Results of simple and multiple regression analysis showed a relationship between the strength of the elbow extension and wrist extension movements and throwing speed.

Arm↗
PubMedDate not supplied

Increased muscularization of small pulmonary arteries in preterm infants of diabetic mothers: a morphometric study in noninflated, noninjected, routinely fixed lungs.

We attempted to identify a structural correlate of the pulmonary hypertension observed in newborn infants of diabetic mothers (IDM) by performing a morphometric analysis of pulmonary arteries at the transition of terminal to respiratory bronchiolus (TRB) in postmortem lungs of 20 IDM and 14 control infants. Although there was no readily apparent microscopic difference between the lungs of newborn IDM and controls, the degree of muscularization, as measured by mean medial area (MMA) of 10 TRB arteries, was significantly greater in preterm IDM (gestational age < or = 37 weeks) than in age-matched controls (502 versus 341 microns 2; P = .0038). Among infants of gestational age > 37 weeks, there was no significant difference between MMA in IDM (508 microns 2) and MMA in controls (598 microns 2). These findings point at an accelerated muscularization of the TRB arteries in IDM, apparent early in the third trimester. The pathogenesis of this hypermuscularization is not understood, but smooth muscle growth promoters such as insulin may play a role. The abnormal timing of TRB artery muscularization could be a manifestation of the basic disturbance in development that contributes to the pulmonary hypertension observed in newborn IDM and to the respiratory difficulties commonly experienced by these infants.

Bronchi↗
PubMedDate not supplied

Suicide prevention by general nurses.

This article aims to review what is known about the nature of suicide and attempted suicide, and examine the ways in which the general nurse can make the most effective contribution to the management and prevention of these problems.

Humans↗
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A nursing model of overdose assessment.

Assessing people following a suicide attempt is an opportunity for therapeutic intervention and for gathering essential information. This article outlines a nursing model for assessing people admitted to hospital following a drug overdose. The model is presented alongside a case study demonstrating its application in practice.

Adaptation, Psychological↗
PubMedDate not supplied

Suppression of growth hormone does not affect ongoing spermatogenesis in rats.

Recent evidence suggests that growth hormone (GH) may enhance physiologic processes, such as spermatogenesis, in addition to causing classical anabolic effects. We have previously shown that testosterone restores spermatogenesis in rats that were made azoospermic by immunization against gonadotropin-releasing hormone (GnRH). In this study, we investigated whether suppression of GH affects spermatogenesis and the ability of testosterone to restore spermatogenesis following immunization against GnRH and/or growth hormone-releasing hormone (GHRH). Twelve rats were actively immunized against GnRH (anti-GnRH), twelve rats were actively immunized against GHRH (anti-GHRH), six rats were immunized against both GnRH and GHRH (anti-GnRH/GHRH), and six rats served as controls. Two weeks after the second booster, six rats each from the anti-GnRH and anti-GHRH groups as well as the six anti-GnRH/GHRH rats received 24-cm testosterone-filled Silastic implants (T), and the remaining six rats from each of these groups received empty Silastic implants. All rats were euthanized 2 months later. Weights of testes and testicular sperm counts were determined. Serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and insulin-like growth factor-1 (IGF-1) concentrations were determined by radioimmunoassays. Serum GH and IGF-1 were suppressed in anti-GHRH rats. IGF-1 was partially restored by testosterone in anti-GHRH and in anti-GnRH/GHRH rats, but GH was restored to control value in anti-GnRH/GHRH rats. Serum LH and FSH were suppressed in anti-GnRH and anti-GnRH/GHRH rats, but only FSH was partially restored by testosterone. Suppression of GH did not affect maintenance of spermatogenesis. However, because T partially restored GH and IGF-1 levels in anti-GnRH/GHRH rats and because spermatogenesis was found to be restored in these rats, we conclude that GH does not play a role in the maintenance of spermatogenesis in adult rats, but it may be required for the replenishment of germ cells in experimentally induced regressed rat testes.

Animals↗