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T Ruf

Publications and source records attributed to T Ruf.

66 records · Page 4Linked to original sources
PubMed1991

Cold prevents the light induced inactivation of pineal N-acetyltransferase in the Djungarian hamster, Phodopus sungorus.

In the Djungarian hamster seasonal acclimatization is primarily controlled by photoperiod, but exposure to low ambient temperature amplifies the intensity and duration of short day-induced winter adaptations. The aim of this study was to test, whether the pineal gland is involved in integrating both environmental cues. Exposure of hamsters to cold (0 degrees C) reduces the sensitivity of the pineal gland to light at night and prevents inactivation of N-acetyltransferase (NAT). The parallel time course of NAT activity and plasma norepinephrine content suggests that circulating catecholamines may stimulate melatonin synthesis under cold load.

Acetyltransferases↗
PubMed1990

[The histamine provocation test: are 1 second capacity and specific conductance competing or complementary measurement values?].

We tested criteria for the decision, whether a provocation challenge with histamine is positive. The combination of spirometry and bodyplethysmography by the condition sGaw less than or equal to 0.04 x PC-FEV overcomes the contradictions due to conventional criteria as PC-FEV greater than or equal to 20% or PC-sGaw greater than or equal to 50%.

Airway Obstruction↗
PubMed1989

Photoperiod and thermoregulation in vertebrates: body temperature rhythms and thermogenic acclimation.

Evidence has recently begun to accumulate that photoperiodic responses of mammals and birds may affect the control of energy balance and thermoregulation. Exposure to short photoperiod can lower the set point for body temperature regulation in birds and mammals, as well as the voluntarily selected body temperature in ectothermic lizards. This decrease is accompanied by a reorganization of circadian or ultradian rhythms of body temperature, particularly an increase in periods spent at rest with minimum body temperatures. Short photoperiod is also used as an environmental cue for induction of seasonal torpor or facilitation of hibernation. During winter, cold tolerance of small mammals is improved by an increase of nonshivering thermogenesis in brown fat. Thermogenic capacity of brown fat (respiratory enzymes, mitochondria, uncoupling protein) is enhanced in response to short photoperiod. This response is mediated via an increase in the activity of sympathetic innervation in brown fat. Moreover, an exposure to short photoperiod prior to low temperatures may act in preparing brown fat for facilitated thermogenesis during acclimation to cold. This shows that photoperiodic control not only affects energy balance indirectly via the control of reproduction or body mass, but may directly interact with central control of thermoregulation and may influence the process of acclimatization.

Activity Cycles↗
PubMed1987

Computerized body temperature telemetry in small animals: use of simple equipment and advanced noise suppression.

Telemetric measurement of body temperatures in small animals implanted with commercially available transmitters (Mini-Mitter) has been automated using the Commodore C-64 microcomputer. Transmitter output frequencies are received by common AM-radios, converted to TTL level by a simple interface and measured by a machine language subroutine. Multiplexed input is under software control and allows for the recording of at least 16 animals selectively, with data points for each sample every 3 min. The effects of environmental electrical noise are significantly reduced by an error detection system based on the separate reception of interference.

Animals↗
PubMedDate not supplied

Serum levels of immunoreactive bone sialoprotein in osteoporosis: positive relations to established biochemical parameters of bone turnover.

Bone Sialoprotein (BSP), synthesized by osteoblasts and osteoclasts, is a highly glycosylated and phosphorylated protein, accounting for approximately 5-10% of noncollagenous proteins of bone extracellular matrix. The present study investigates possible correlations between serum values of immunoreactive Bone Sialoprotein in relation to established bone turnover markers like osteocalcin (OC), bone alkaline phosphatase (B-ALP) and the c-terminal extension peptide of type-I-Procollagen (PICP) in 170 osteoporosis patients (female n = 144, male n = 26) in order to evaluate the usefulness of BSP in the diagnosis of bone disease. Fasting venous blood samples were collected from our osteoporosis outpatients in the morning and stored at -80 degrees C until processing. Serum levels of BSP were determined by RIA, OC and B-ALP were measured by IRMA, and PICP was assessed employing an ELISA technique. A significant correlation was found between BSP serum values and B-ALP (r = 0.532, p = 0.0001). Median serum BSP levels were 8.0 micrograms/l, median B-ALP values were 22.39 U/ml in these patients. Also a significant correlation was observed between BSP and OC (r = 0.588, p = 0.0001), more pronounced in the female patient group (r = 0.632, p < 0.0001). A weak association between BSP and PICP in the female group was detected (r = 0.398, p = 0.0001). In the female group BSP was inversely related to serum estradiol levels (r = -0.274, p = 0.002) as to BMD (DEXA) at the lumbar spine and femoral neck. In conclusion, BSP might be a useful marker of non-collagenous organic bone matrix in laboratory assessment of bone turnover, being inversely related to BMD at lumbar spine and femoral neck and showing significant correlations to established markers of bone turnover like B-ALP and OC.

Absorptiometry, Photon↗