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Biomedical subjects

P Franken

Publications and source records attributed to P Franken.

At least 19 recordsLinked to original sources
PubMed1997

Probability of detecting antibodies to bovine herpesvirus 1 in bulk milk after the introduction of a positive animal on to a negative farm.

The purpose of this study was to assess the probability that the introduction of one or more bovine herpesvirus 1 (BHV-1)-seropositive animals would result in the bulk milk of a clean herd becoming BHV-1-positive. Probability calculations (stochastic and deterministic) were based on the distribution of the log(titre) of 828 positive animals and the daily milk production of the herds and of the individual cows. They showed that the probability in average sized herds of 45 dairy cows is only between 10 and 25 per cent and that even in small herds of 25 cows the introduction of a positive animal would go undetected in the majority of cases. It is concluded that if the bulk milk has become BHV-1-positive it is most likely that the infection has spread.

Animals↗
PubMed1996

Use of composite milk samples for diagnosis of Staphylococcus aureus mastitis in dairy cattle.

OBJECTIVE: To measure relative sensitivity and relative specificity for use of composite milk samples, compared with that of individual gland milk samples, for diagnosis of Staphylococcus aureus mastitis. ANIMALS: 505 cows suspected of having subclinical mastitis. Of these cows, 172 were considered infected with Sta aureus, based on the results from individual gland samples. PROCEDURE: Composite and individual gland milk samples were collected from cows suspected of having subclinical mastitis, and results of bacteriologic culturing of samples from the same cow were compared. Results were interpreted at the cow level. Relative sensitivity and relative specificity for composite samples were computed from 2 x 2 tables, using results from individual gland samples as references. RESULTS: Relative sensitivity for use of composite milk samples in diagnosing Sta aureus mastitis was 0.63. The relative specificity was 0.98. Factors influencing the relative sensitivity for composite samples were the number of infected glands per cow, the amount of Sta aureus shedding from infected glands, and the proportion of the composite milk obtained from each gland. CLINICAL IMPLICATIONS: Collecting composite instead of individual gland milk samples increases the number of false-negative results in diagnosing Sta aureus mastitis. By collecting consecutive samples from the same cow or by increasing the inoculum volume at culturing, this problem can be diminished.

Animals↗
PubMed1996

Siberian hamsters free run or become arrhythmic after a phase delay of the photocycle.

Body temperature (Tb) and locomotor activity were recorded telemetrically from male Siberian hamsters (Phodopus sungorus sungorus) that were 3 or 12 mo of age and maintained in a light-dark (LD) cycle of 16 h light/day for 2-4 mo. After 3 wk of Tb recording, the LD cycle was phase delayed by extending the light phase by 5 h for 1 day; animals remained on a 16:8-h LD cycle for the remainder of the experiment. Tb and activity rhythms of all animals were stably entrained to the LD cycle before the phase shift. After the phase shift, > or = 80% of the animals in each age group failed to reentrain and expressed free-running Tb rhythms with stable periods that ranged from 24.33 to 26.33 h; one hamster in each age group reentrained within several days. Tb became arrhythmic in 10% of all animals immediately after, and in 28% of free running animals several weeks after, the phase shift. Changes in tau and phase of activity rhythms closely paralleled Tb rhythms in individual hamsters. Daily mean Tb was unchanged, but Tb rhythm amplitude decreased by 25-50% in individual animals after the phase shift. We believe this to be the first report of neurologically intact animals failing to reentrain to a phase shift of the LD cycle. These phenomena are not readily explained by current knowledge of circadian systems and suggest that the entrainment process in Siberian hamsters differs markedly from that in other rodent species.

Animals↗
PubMed1995

Effect of elevated ambient temperature on sleep, EEG spectra, and brain temperature in the rat.

To examine the relationship between sleep and brain temperature in the rat, the vigilance states, spectral power density of the electroencephalogram (EEG), hypothalamic temperature (T(hy)), and cortical temperature (Tcr) were recorded for 3 days. A 1-day rise of ambient temperature from 23 to 30 degrees C did not affect the percentage of waking, non-rapid eye movement sleep (NREMS), and rapid eye movement sleep (REMS), but increased EEG slow-wave activity in NREMS in the 12-h dark period. T(hy) was invariably higher than Tcr, but at 30 degrees C the difference diminished because of a rise in Tcr. In contrast to Tcr, T(hy) was only slightly increased at 30 degrees C and only during sleep and in the dark period. Although the temperatures changed largely in parallel at vigilance state transitions, Tcr rose more rapidly than T(hy) at NREMS-REMS transitions and more slowly at NREMS-waking transitions. T(hy) declined more rapidly than Tcr at waking-NREMS transitions and more slowly at REMS-NREMS transitions. The results are consistent with a central role of the hypothalamus in the activation and deactivation of the waking state.

Acclimatization↗
PubMed1995

Varying photoperiod in the laboratory rat: profound effect on 24-h sleep pattern but no effect on sleep homeostasis.

To assess the influence of the photoperiod on sleep regulation, laboratory rats were adapted to a long photoperiod (LPP; 16:8-h light-dark cycle, LD 16:8) or a short photoperiod (SPP; LD 8:16). The electroencephalogram (EEG) and cortical temperature (TCRT) were continuously recorded for a baseline day, a 24-h sleep deprivation (SD) period, and a recovery day. Data obtained previously for LD 12:12 served for comparison. Whereas the photoperiod exerted a prominent effect on the 24-h sleep pattern, the 24-h baseline level of sleep and the response to SD were little affected. Recovery from SD was characterized by a marked rise in rapid eye movement sleep, a moderate rise in non-rapid eye movement sleep, and an initial enhancement of EEG slow-wave activity followed by a decrease below baseline. The amplitude and phase of the "unmasked" 24-h component of TCRT did not differ between LPP and SPP. Computer simulations demonstrated that the changes of TCRT and EEG slow-wave activity can be largely accounted for by the sequence of the vigilance states. We conclude that the photoperiod does not affect the basic processes underlying sleep regulation.

Animals↗
PubMed1995

Cardiac SPECT with iodine-123-labeled fatty acids: evaluation of myocardial viability with BMIPP.

The use of 123I-labeled fatty acids is witnessing a resurgence of interest, primarily because of data from recent clinical protocols comparing regional myocardial uptake of 123I-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentandecanoic acid (BMIPP) with flow tracers. Comparison of mismatches in BMIPP and flow tracer distribution (BMIPP < flow tracer) has demonstrated the usefulness of evaluating myocardial viability with BMIPP. BMIPP was introduced in 1993 as "Cardiodine" as an approved radiopharmaceutical in Japan by Nihon Medi-Physics, Inc. This article reviews the clinical use of BMIPP in the assessment of cardiomyopathy, myocardial infarction, ischemic heart disease and for the evaluation of myocardial viability in comparison with PET tracers. The results of two specific protocols demonstrating the utility of using BMIPP to detect viable myocardium are described in detail. The first study compares BMIPP and sestamibi uptake to wall motion and inotropic reserve after acute myocardial infarction in conjunction with two-dimensional echocardiography and low-dose dobutamine stimulation. The second example describes results of a triple SPECT technique using BMIPP reinjection for the assessment of ischemia.

Cardiomyopathies↗
PubMed1994

Room light impairs sleep in the albino rat.

Since the rat is a nocturnal animal sleep experiments in this species are commonly performed during the light period of the 24-h light-dark (LD) cycle. To examine whether light itself affects sleep, chronically implanted albino rats were continuously recorded for a day under a 12-h light-12-h dark cycle (light intensity approx. 300 lx) and on the subsequent day in constant darkness (DD). In the absence of light, EEG slow-wave activity (0.75-4.0 Hz) in non-REM sleep and sleep continuity were significantly enhanced, while total sleep time and cortical temperature were not affected. The results show that in the albino rat room light impairs sleep by reducing its intensity and continuity.

Action Potentials↗
PubMed1994

High-frequency components of the rat electrocorticogram are modulated by the vigilance states.

In view of the reports that in the human magnetoencephalogram, 40-Hz oscillations are more abundant in waking and REM sleep than in non-REM sleep, we performed a 24-h broad-band (0.25-64 Hz) spectral analysis of the electrocorticogram in unrestrained rats. Spectral power above 33 Hz was higher in waking and REM sleep than in non-REM sleep, and in the range of 6-38 Hz it was higher in REM sleep than in waking. Consistent frequency-specific changes in spectral power marked the transitions between vigilance states. The study demonstrates that the rat EEG exhibits state- and frequency-specific changes over a large frequency range.

Animals↗
PubMed1994

Sleep and cortical temperature in the Djungarian hamster under baseline conditions and after sleep deprivation.

The Djungarian hamster (Phodopus sungorus) is a markedly photoperiodic rodent which exhibits daily torpor under short photoperiod. Normative data were obtained on vigilance states, electroencephalogram (EEG) power spectra (0.25-25.0 Hz), and cortical temperature (TCRT) under a 16:8 h light-dark schedule, in 7 Djungarian hamsters for 2 baseline days, 4 h sleep deprivation (SD) and 20 h recovery. During the baseline days total sleep time amounted to 59% of recording time, 67% in the light period and 43% in the dark period. The 4 h SD induced a small increase in the amount of non-rapid eye movement (NREM) sleep and a marked increase in EEG slow-wave activity (SWA; mean power density 0.75-4.0 Hz) within NREM sleep in the first hours of recovery. TCRT was lower in the light period than in the dark period. It decreased at transitions from either waking or rapid eye movement (REM) sleep to NREM sleep, and increased at the transition from NREM sleep to waking or REM sleep. After SD, TCRT was lower in all vigilance states. In conclusion, the sleep-wake pattern, EEG spectrum, and time course of TCRT in the Djungarian hamster are similar to other nocturnal rodents. Also in the Djungarian hamster the time course of SWA seems to reflect a homeostatically regulated process as was formulated in the two-process model of sleep regulation.

Animals↗
PubMed1994

Molecular analysis of C1 alleles in Zea mays defines regions involved in the expression of this regulatory gene.

The structure and function of several C1 alleles have been investigated molecularly and the importance of C1 promoter sequences for gene expression was studied using transient transformation assays. The C1 mutants analyzed were the overexpressing allele C1-S, the light-inducible allele c1-p, the null recessive allele c1-n, and the Ds element-induced allele c1-m1. Nucleotide sequence analysis of the alleles revealed a number of differences, predominantly located at the 3' end of the gene. The promoter sequences of the C1 alleles investigated so far (including wild-type and the dominant inhibitor C1-I allele) are almost identical except for two short footprint-like sequences (Box I and Box II) close to the putative CAAT box. Northern blot experiments and transient expression in particle gun experiments indicate that these sequences may be correlated with the different expression patterns of the alleles in the aleurone of maturing and germinating kernels.

Alleles↗
PubMed1994

Molecular analysis of protein domain function encoded by the myb-homologous maize genes C1, Zm 1 and Zm 38.

Two maize genes, Zm 1 and Zm 38, related to the regulatory anthocyanin gene C1 were analyzed molecularly and used for fusion constructs in transient domain swapping experiments with the C1 wild-type gene. It was shown that both genes (Zm 1 and Zm 38) influence the expression of the A1 locus, a target gene for C1. Zm 1 activates the A1 promoter, however it does not turn on the whole anthocyanin pathway. The Zm 38 gene product shows functions similar to C1-I, a dominant inhibitor of the C1 wild-type gene. Concerning the trans-inhibition by C1-I two effects seem to be involved, competition for binding and formation of heterodimers. Further analysis of C1 function was carried out by a fine structure analysis of C1 mutants induced by the insertion and excision of transposable elements. These experiments indicate that for the activating domain of the protein, the formation of an alpha helix seems to be more important than a high negative charge.

Alleles↗
PubMed1994

Sleep deprivation in the rat at different ambient temperatures: effect on sleep, EEG spectra and brain temperature.

To investigate the relationship between thermoregulation and sleep regulation, rats were sleep-deprived for 3 hours at two different ambient temperatures. Sleep deprivations (SD) were performed at 23 degrees C (SD-23) and at 32 degrees C (SD-32) in the beginning of the 12-h light period in animals chronically implanted with ECoG and EMG electrodes, and with epidural and hypothalamic thermistors. SD-32 enhanced cerebral temperature more than SD-23 at both brain sites. The SD-induced hyperthermia was followed by a fall of brain temperature below baseline. During recovery from either SD procedure, waking was reduced and sleep continuity increased. REM sleep was increased after SD-32. EEG slow-wave activity (spectral power density in the 0.75-4.0 Hz band) exceeded the baseline level in the first 3-h interval of recovery; however, the effects of SD-23 and SD-32 did not differ. In the same time interval, power density in the 1.25-1.5 Hz bin as well as in some bins in the theta and alpha band was higher after SD-32 than after SD-23. The increase in hypothalamic temperature during SD did not correlate with the increase in SWA during recovery. It is concluded that even a brief SD has major repercussions on recovery sleep whereas the extent of cerebral hyperthermia during SD is only a minor factor.

Animals↗
PubMed1993

Sleep homeostasis in the guinea pig: similar response to sleep deprivation in the light and dark period.

In the guinea pig, sleep and slow-wave activity (SWA) are evenly distributed over 24 h in contrast to the sleep pattern in other rodents where a daily preference for sleep and a decline of SWA within the main sleep period is typical. SWA is regulated as a function of prior waking and is assumed to reflect sleep intensity. We investigated sleep homeostasis and its possible circadian modulation by performing sleep deprivation (SD) at two phases of the light-dark cycle. SD induced an increase in SWA which was similar under both conditions. We conclude that sleep is homeostatically regulated in the guinea pig and is not subject to a circadian modulation.

Animals↗
PubMed1993

[Serological study of the occurrence of L. hardjo in sheep in The Netherlands].

Sheep (3918) from 137 farms in the regions of North-, West- and Mid-Netherlands and Gelderland were serologically investigated for the presence of antibodies against Leptospira hardjo. Antibodies were detected in 3.3% of the sheep. There were large regional differences with respect to both the percentage of positive sheep and the percentage of positive flocks. All sera from sheep in Gelderland were negative. In West- en Mid-Netherlands there were 0.9 and 6.5% positive sera, respectively, and 19.4 and 32.7% positive flocks. The percentage of positive sheep per positive flocks varied from 1 tot 51.6. Serological positive sheep were from farms with and without cattle. On farms with cattle, there was no clear relationship between serologically sheep and the presence of hardjo antibodies in cattle. It thus seems plausible that sheep can be infected with hardjo independently of cattle.

Animals↗
PubMed1993

Effects of 12-h sleep deprivation and of 12-h cold exposure on sleep regulation and cortical temperature in the rat.

The predictions of the two-process model of sleep regulation were tested by 12-h sleep deprivation (SDEP) and 12-h cold exposure (cold, 4 degrees C) in the rat, both carried out in the 12-h dark period. The analysis was based on recordings of vigilance states, electroencephalogram (EEG) power spectra (0.25-25.0 Hz), and cortical temperature (Tcrt). During recovery from SDEP, slow-wave activity (SWA; EEG power density in the 0.75-4.0 Hz band) in non-REM sleep was higher and the number of brief awakenings (nBA) lower than in the corresponding baseline period. During recovery from cold, a moderate and delayed increase in SWA was present. During SDEP, Tcrt was above baseline, and in some intervals of recovery below baseline. In those intervals waking was also decreased. During recovery from cold, Tcrt and waking were not affected. It is concluded that 12-h SDEP causes an intensification of sleep, as indicated by the enhanced SWA and the reduced nBA, whereas 12-h cold has only marginal effects. The time course of SWA in both experiments could be accurately predicted by a computer simulation based on the assumption of the two-process model and the parameter values determined in a previous experiment.

Animals↗
PubMed1993

Vigilance states, EEG spectra, and cortical temperature in the guinea pig.

Vigilance states, electroencephalogram (EEG) power spectra (0.25-25.0 Hz), and cortical temperature (TCRT) were obtained in nine guinea pigs for 24 h in a 12:12-h light-dark (LD 12:12) schedule. Sleep was markedly polyphasic and fragmented and amounted to 32% of recording time, which is a low value compared with sleep in other rodents. There was 6.8% more sleep in the light period than in the dark period. EEG power density in non-rapid eye movement (NREM) sleep showed no significant temporal trend within the light or the dark period. The homeostatic aspects of sleep regulation, as proposed in the two-process model, can account for the slow-wave activity (SWA) pattern also in the guinea pig: The small 24-h amplitude of the sleep-wakefulness pattern resulted in a small, 12% decline of SWA within the light period. In contrast to more distinctly nocturnal rodents, SWA in the dark period was not higher than in the light period. TCRT showed no difference between the light and the dark period. TCRT in REM sleep and waking was higher than TCRT in NREM sleep. TCRT increased after the transition from NREM sleep to either REM sleep or waking, and decreased in the last minute before the transition and after the transition from waking to NREM sleep. Motor activity measured in six animals for 11 days in constant darkness showed no apparent rhythm in three animals and a significant circadian rhythm in three others. Our data support the notion that guinea pigs exhibit only a weak circadian rest-activity rhythm.

Animals↗