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Biomedical subjects

B Hess

Publications and source records attributed to B Hess.

281 records · Page 16Linked 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

Could implantable cardioverter defibrillators provide a human model supporting the learned helplessness theory of depression?

Affective symptoms were examined retrospectively in 25 patients following placement of implantable cardioverter defibrillators (ICD) which can produce intermittent shocks without warning in response to cardiac ventricular arrhythmias. The number of ICD random, uncontrollable discharge shocks and pre-ICD history of psychological distress (i.e., depression and/or anxiety) were documented in all patients using a demographics questionnaire and a standardized behavioral/psychological symptoms questionnaire (i.e., Symptom Checklist-90 Revised). ICD patients were dichotomized into two groups: those without a history of psychological distress prior to ICD (n = 18) and those with a history of psychological distress prior to ICD (n = 7). In ICD patients without a prior history, results indicated that quantity of ICD discharge shocks was significantly predictive of current reported depression (r = 0.45, p = 0.03) and current reported anxiety (r = 0.51, p = 0.02). Conversely, in patients with a reported history of psychological distress, there was no significant relationship found between quantity of discharge shocks and current reported depression or anxiety. This study may provide evidence in support of a human model of learned helplessness in that it supports the notion that exposure to an unavoidable and inescapable aversive stimulus was found to be related to patients' reported depression. Further studies may wish to prospectively consider a larger sample as well as a more comprehensive assessment of premorbid psychological symptoms.

Adult↗
PubMedDate not supplied

The role of serum high density lipoproteins in adrenal steroidogenesis.

The rat adrenal cortex possesses at least two mechanisms for uptake of extracellular lipoprotein cholesterol; one is receptor mediated endocytosis and the second is a non-endocytotic pathway. The latter was revealed by the ability of lipoproteins such as HDL which do not possess apo B or apo E to enhance steroid hormone output. Rat adrenocortical cell uptake of HDL cholesterol is saturable and differs for unesterified cholesterol and cholesterol esters. In addition rat adrenocortical cells possess ACTH regulated HDL binding sites although the relationship of HDL receptor activity to cholesterol uptake remains uncertain. Further elucidation of the "HDL pathway" in the rat adrenal cortex may have biologic significance beyond understanding adrenal function since many non-steroidogenic tissues also possess HDL receptors and in man circulating levels of HDL-cholesterol are a strong inverse risk factor for accelerated atherosclerosis.

Adrenal Cortex↗
PubMedDate not supplied

[Effect of histamine-blocking substances on mitogen-induced lympho proliferation in rheumatic diseases].

Peripheral blood lymphocytes of patients with rheumatoid arthritis, psoriatic arthritis and healthy controls, isolated by a ficoll density gradient, were incubated with different concentrations of histamine, cimetidine and diphenhydramine (DPH) and simultaneously stimulated with phytohemagglutinine (PHA). In comparison to healthy control persons the lymphoproliferation rate in arthritic patients could be increased about 20% by addition of the histamine-blocking agents cimetidine and DPH. This suggests the existence of in vivo histamine-induced suppressor cells in arthritic patients, which can be inhibited by receptor blocking agents.

Arthritis, Rheumatoid↗