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Biomedical subjects

E Horn

Publications and source records attributed to E Horn.

At least 55 records · Page 3Linked to original sources
PubMed1996

Comparison of some blood parameters of captured and farmed red deer (Cervus elaphus) hinds.

In studies on the adaptation of red deer (Cervus elaphus) to farm conditions, some blood parameters of 3- to 9-year-old captured and farmed hinds were compared. The test variable included blood plasma creatine kinase (CK), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activities, the concentrations of glucose, urea, total protein (TP), serum cortisol, haemoglobin (Hb), and the blastogenic transformation of lymphocytes upon stimulation by the nonspecific mitogens Phaseolus vulgaris (PHA) and Concanavalin A (ConA) in the lymphocyte stimulation test (LST). The effects exerted by probiotic preparation (Ascogen) on the same parameters were studied in farmed deer. In hinds that had been kept under farm conditions for 10 months, CK activity was lower (P < 0.05) and blood urea concentration higher (P < 0.001) than at the time of capture, while their blood glucose concentration exceeded (P < 0.01) that of farmed hinds. Hinds treated with Ascogen had lower ALT activity (P < 0.001) and showed a higher increase in PHA-induced blastogenic transformation of lymphocytes than the control hinds.

Adaptation, Physiological↗
PubMed1995

Double-blind, placebo-controlled study of the long-term efficacy of carvedilol in patients with severe chronic heart failure.

BACKGROUND: Clinical trials have shown that beta-adrenergic blocking drugs are effective and well tolerated in patients with mild to moderate heart failure, but the utility and safety of these drugs in patients with advanced disease have not been evaluated. METHODS AND RESULTS: We enrolled 56 patients with severe chronic heart failure into a double-blind, placebo-controlled study of the vasodilating beta-blocker carvedilol. All patients had advanced heart failure, as evidenced by a mean left ventricular ejection fraction of 0.16 +/- 0.01 and a mean maximal oxygen consumption of 13.6 +/- 0.6 mL.kg-1.min-1 despite digitalis, diuretics, and an angiotensin-converting enzyme inhibitor (if tolerated). After a 3-week, open-label, up-titration period, 49 of the 56 patients were assigned (in a double-blind fashion using a 2:1 randomization) to receive either carvedilol (25 mg BID, n = 33) or matching placebo (n = 16) for 14 weeks, while background therapy remained constant. Hemodynamic and functional variables were measured at the start and end of the study. Compared with the placebo group, patients in the carvedilol group showed improved cardiac performance, as reflected by an increase in left ventricular ejection fraction (P = .005) and stroke volume index (P = .010) and a decrease in pulmonary wedge pressure, mean right atrial pressure, and systemic vascular resistance (P = .003, .002, and .017, respectively). In addition, compared with placebo, patients treated with carvedilol benefited clinically, as shown by an improvement in symptom scores (P = .002), functional class (P = .013), and submaximal exercise tolerance (P = .006). The combined risk of death, worsening heart failure, and life-threatening ventricular tachyarrhythmia was lower in the carvedilol group than in the placebo group (P = .028), but carvedilol-treated patients had more dizziness and advanced heart block. CONCLUSIONS: Carvedilol produces clinical and hemodynamic improvement in patients who have severe heart failure despite treatment with angiotensin-converting enzyme inhibitors.

Adrenergic beta-Antagonists↗
PubMed1995

Microinjections of GABAergic agents in the locus coeruleus modify the gain of vestibulospinal reflexes in decerebrate cats.

1. Precollicular decerebrate cats show a good postural activity in the four limbs and a small-amplitude vestibulospinal (VS) reflex, as revealed by recording the EMG response of the triceps brachii to sinusoidal roll tilt of the animal at 0.15 Hz, +/- 10 degrees. This preparation was used to study whether inactivation of the locus coeruleus (LC) elicited by local administration either of the GABA-A agonist muscimol or of the GABA-B baclofen produced changes in posture as well as in gain of the VS reflexes. 2. Microinjection into the LC of one side of 0.13-0.25 microliter of a muscimol or baclofen solution (at 2.5 or 1 microgram/microliter saline, respectively) stained with 5% pontamine, usually decreased the extensor tonus in the ipsilateral limbs and to a lesser extent also in the contralateral limbs. However, the amplitude of modulation and thus the gain of the first harmonic component of the multiunit EMG responses of the ipsilateral and to a lesser extent also of the contralateral triceps brachii to the same parameters of labyrinth stimulation increased. The phase angle of the responses remained nearly unchanged by this treatment. The effects appeared 5-10 min after the injection of muscimol, fully developed in 30 min and progressively declined within the following 2-2.5 hours. 3. The increased gain of the VS reflexes acting on the triceps brachii did not depend on the decreased postural activity following the injection of the GABA-A or GABA-B agonist, since it was still observed if the reduced EMG activity following the injection was compensated by an increased static stretch of the muscle. Moreover, the postural and reflex changes described above were not due to irritative events following the injection, since they were not observed in control experiments following injection of 0.25 microliter saline within the LC-complex. On the other hand, postural and reflex changes opposite in sign to those elicited by muscimol or baclofen were obtained by local injection into the LC-complex of a GABA-A or GABA-B antagonist (0.25 microliter of bicuculline or faclofen at 8 micrograms/microliters saline). 4. In some experiments, the decrease in postural activity of the forelimbs after injection of muscimol into the LC complex was followed by transient episodes of postural atonia, which affected not only the ipsilateral but also the contralateral triceps muscles.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

[Ring-valve abscess--a diagnostic challenge].

Infective endocarditis is a life-threatening disease which may be complicated by ring-valve abscess. Since this complication increases morbidity and mortality early diagnosis is important. Pericardial effusion complicating infective endocarditis is uncommon and should raise suspicion of the presence of an abscess. We describe 2 patients admitted for infective endocarditis and pericarditis. In both, ring-valve abscess was suspected on clinical grounds. At surgery there was pathological confirmation of the diagnosis. Both patients underwent successful aortic valve replacement with complete recovery. Controlled trials are providing increasing evidence for the superiority of transesophageal echocardiography in detecting valvular vegetations. Moreover, it is the most accurate means of detecting ring-valve abscess in cases of infective endocarditis. In view of these advantages, we propose the use of transesophageal echocardiography in every case of infective endocarditis.

Abscess↗
PubMed1993

Arrest of seizure series induced by an intracortical injection of penicillin in the awake rat.

Experiments were performed to answer the question, whether series of generalized tonic-clonic seizures, induced in the awake rat by a local injection of Na-penicillin (PCN) solution into the motor cortex, terminates at the same critical concentration Ct of PCN within the focal area independently of the concentration C0 of PCN injected. Using the PCN diffusion coefficient D = 3.52 x 10(-4) mm2/s and the tortuosity factor lambda = 1.62, the concentration Ct at the onset of the last generalized seizure was calculated. The median duration of seizure series increased from 32 to 190 min, when the dose of injected PCN was raised from 32 to 1000 IU. At the onset of the last seizure, the median concentration Ct within the artificial focus ranged from 2.1 to 4.0 IU/0.5 microliter saline in rats treated with 32 to 125 IU PCN. After induction of convulsive behaviour with C0 = 250, 500, or 1000 IU PCN/0.5 microliter saline, however, Ct was at a higher level between 6.1 and 7.4 IU PCN/0.5 microliter saline. The difference between the cumulated data from the low-dose vs. the high-dose range was significant (p < 0.01). It is concluded that during long-lasting series of generalized seizures, the brain takes advantage of its plastic properties. By forming a counteracting mechanism, it protects itself from extreme epileptiform activity. This autoprotection may be due to the activation of neuronal networks which probably needs a certain frequency of seizures to become operatively.

Animals↗
PubMed1993

Protective sensitivity changes of the motor cortex due to epileptiform experience of the visual cortex.

In awake rats, experiments were performed to study early epileptiform events (interictal spike, myoclonic jerk) in relation to a) the strength of the convulsive stimulus, b) the site of the focus, and c) epileptiform experience. For this reason, Na-penicillin G (PCN) was injected either into the motor or visual cortex and, in a second test 2 weeks thereafter, into the motor cortex in all these rats. The median latencies of both the first interictal potential and jerk were independent of the applied PCN concentration in the range between 16-1,000 IU/0.5 microliter (90.5-113 s, and from 106-196 s, respectively), as well as from the injection site in the visual or motor cortex (potential: 80 vs. 69 s; jerk: 124 vs. 129 s, respectively). After epileptiform experience in the visual cortex, the latencies of the first potential and jerk were significantly (p < 0.05) increased compared to animals with an experience in the motor cortex (first potential: 100 vs. 66 s; first jerk: 159 vs. 116 s, respectively). The results show that a PCN focus in the visual cortex decreases the susceptibility of the motor cortex for the convulsant action of PCN. This means that an autoprotective mechanism is activated whose efficiency depends upon a close linkage between the visual and motor cortex.

Animals↗
PubMed1993

Modulation of vestibulospinal reflexes through microinjection of an alpha 1-adrenergic antagonist in the dorsal pontine tegmentum of decerebrate cats.

1. The possibility that the norepinephrine (NE)-containing locus coeruleus (LC) neurons produce changes in posture as well as in gain of the vestibulospinal (VS) reflexes by acting on the dorsolateral pontine tegmentum (DPT) and the related medullary inhibitory reticulospinal (RS) system through alpha 1-adrenoceptors has been investigated in decerebrate cats. 2. Injection of the alpha 1-adrenergic antagonist prazosin PRZ (0.25 microliter at 0.1-1 microgram/microliter solvent) into the DPT, namely in the dorsal pontine reticular formation (pRF), as well as in the peribrachial nucleus of one side, decreased the postural activity in the ipsilateral limbs while increasing that of the contralateral limbs. In addition, the amplitude of modulation and thus the gain of the multiunit EMG responses of the ipsilateral and to a lesser extent of the contralateral triceps brachii to roll tilt of the animal at 0.15 Hz, +/- 10 degrees, increased. These effects appeared 5-10 min after the injection, reached the highest values in about 40-60 min and persisted for additional 1.5-2 h before disappearing. 3. The effects were site-specific and to some extent dose-dependent. However, neither changes in posture nor in gain of the VS reflexes were obtained after injection in the effective area of an equal volume of solvent. 4. In order to account for these findings it was postulated that the alpha 1-antagonist blocks the tonic inhibitory influence that the NE-containing LC neurons exert on ipsilateral DPT either by exciting through alpha 1-receptors interposed inhibitory interneurons, or by inhibiting presynaptically excitatory afferents to the same pontine tegmental structures. The increased discharge of these neurons and the related medullary inhibitory RS neurons would reduce the postural activity in the ipsilateral limbs. However, since the inhibitory RS neurons show a response pattern to tilt opposite in sign to that elicited by the excitatory VS neurons, we could expect that for a given labyrinth signal, the increased discharge of the RS neurons in the animal at rest would lead to a greater disinhibition of limb extensor motoneurons during ipsilateral tilt. These motoneurons would then respond more efficiently to the same excitatory volleys elicited by given parameters of stimulation, thus leading to an increased gain of the EMG responses of forelimb extensors to labyrinth stimulation. The possibility that the DPT of one side activates inhibitory RS neurons of both sides explains why PRZ increases the gain of the VS reflexes not only ipsilaterally but also contralaterally to the side of the injection.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1993

T-cell deficiency in Suffolk lambs.

In a flock of Suffolk sheep respiratory diseases were regularly observed, while a flock of Booroola sheep kept under similar feeding and management conditions remained healthy. Experiments were conducted to compare the immunological and haematological parameters of Suffolk and Booroola sheep of different age groups. The percentage of T and B cells in the lymphocyte population and the capacity for blastogenesis induced by nonspecific mitogens were analyzed. Suffolk sucking lambs had significantly (P < 0.001) lower Concanavalin A (Con-A) induced blastogenesis and significantly lower T cell percentage at 6 months of age than Booroola lambs of the same age. B cell percentage and the rate of blastogenesis induced by Phaseolus vulgaris lectin (PHA) were lower in Suffolk lambs, though the differences were not significant. Sucking and growing Suffolk lambs had significantly (P < 0.01) lower red blood cell count and packed cell volume than Booroola lambs of the same age. Blood haemoglobin concentration was also lower in Suffolk lambs. No consistent differences were seen between the two breeds in total leucocyte count. T-cell deficiency and anaemia could be corrected by treatment with the immunomodulator levamisole (administered at a dose of 3 mg/kg body mass intramuscularly, twice with an interval of 10 days) and with vitamin B12 (1,000 micrograms/animal i.m.), respectively. On day 16 after the first treatment, the T-cell percentage, Con-A induced blastogenesis, red blood cell count, and packed cell volume of growing Suffolk lambs increased. T-cell deficiency and anaemia, either separately or together, may explain the lower resistance of Suffolk lambs to opportunistic pathogens. The relative contribution of genetic and environmental factors requires further studies.

Animals↗
PubMed1993

Ritanserin, imipramine, and placebo in the treatment of dysthymic disorder.

Fifty outpatients with dysthymic disorder (DSM-III) were divided by double-blind randomized assignment into three groups given ritanserin, imipramine, and placebo, respectively. The trial was of 7 weeks' duration; by week 6, imipramine was clearly superior to placebo, whereas by week 7, both drugs caused significantly more improvement than the placebo. Although imipramine had slightly greater efficacy than ritanserin, it also had significantly more side effects. This was particularly evident in the higher dropout rate with imipramine. The efficacy and side effect profile of ritanserin makes it well tolerated and acceptable with dysthymic patients who, although they do not respond as quickly as patients with major depressive disorder, do show significant improvement, given sufficient time.

Adult↗
PubMed1993

Transient epileptiform experience affects the duration of penicillin-induced convulsive activity in the awake rat.

1. Experiments were performed to investigate whether the sensitivity of the cerebral cortex to produce convulsive activity was modified by a transient epileptic focus. For this reason, 30 awake rats received two intracerebral penicillin (PCN) injections (125 IU/0.5 microliter solvent), the first one into the motor or visual cortex, the second one two weeks later into the motor cortex. Convulsive activity was recorded by means of EEG. 2. After the first PCN injection, interictal activity lasted 143.4 +/- 19.3, S.E. min (n = 17) in the motor cortex group, but 426 min (n = 13) in the visual group (p < 0.05). The median frequency of interictal potentials (np/min) was significantly lower in the motor cortex group than in the visual cortex group (18.4 and 25.5 np/min, respectively, p < 0.05). The period between the onset of the first and last seizure was 110.6 +/- 10.2 min for the motor cortex group, and 119.8 +/- 31.2 min for the visual cortex group. The seizures lasted longer and were less frequent in the motor than in the visual group (length: 12.5 +/- 1.1 vs 7.5 +/- 2.8 s; number: 43 +/- 11 vs 131 +/- 40, respectively, 0.05 < p < 0.1). 3. After the second PCN injection which was performed in all rats into the motor cortex, the duration but not the frequency of the interictal activity depended on the site of the first injection. The duration after this treatment was 96.8 +/- 43.3, S.E. min in the visual and 173.2 +/- 30.5 min in the motor cortex group (p < 0.05), while the frequency values of both groups were at a similar level (20.5 +/- 2.1 vs 18.9 +/- 1.7 np/min, respectively). Also the period with generalized activity after the second PCN injection was shorter in the visual than in the motor cortex group (43.9 +/- 32.3 vs 114.3 +/- 31.8 min, respectively, p < 0.05), and the number of seizures slightly lower (8 +/- 210 vs 54 +/- 30, respectively, p < 0.1). The length of the seizures was rather equal 11.6 +/- 2.5 vs 12.0 +/- 3.5 s, respectively, p > 0.1). 4. It is postulated that a transient epileptiform focus can induce, in a site-specific manner, long-lasting anticonvulsant effects. Therefore, epileptogenic experience may not only sensitize the brain, but also desensitize it with respect to the induction and duration of epileptiform activity.

Animals↗
PubMed1991

Time course of interictal EEG patterns induced by a penicillin injection into the olfactory cortex.

In awake rats, the time courses of behavioural and cortical interictal hyperactivity patterns were investigated following an injection of the GABA antagonist Na-penicillin (PCN) (125 IU/0.5 microliters) into the olfactory or motor cortex. The cortical EEG was recorded by means of 6 AgAgCl-electrodes, behaviour was videotaped simultaneously. Behavioural hyperactivity developed immediately after PCN injection. It lasted longer than 2.5 to 4 h in the olfactory but less than 30 min in the motor cortex group of rats. The interictal EEG pattern of the olfactory group was characterized by a slow establishing of three centers of high cortical activity. They were located in the ipsilateral central and the contralateral frontal and occipital cortex. In the motor cortex group, however, a cortical center of high activity developed immediately after the PCN injection near the injection site only, or additionally, over the homotopic area of the contralateral hemisphere. The results indicate different susceptibility properties in the underlying neuronal networks. Ongoing epileptiform activity obviously modifies this susceptibility in a site-specific manner. Moreover, the time-correlated occurrence of high activity in the frontal motor and occipital cortex evoked by a PCN injection into the olfactory cortex suggests a close coupling of these three areas. A coupling between the frontal motor, occipital and focal area could not be shown, if PCN was injected into the motor cortex.

Animals↗
PubMed1991

Preparatory brain potentials in major depressive disorder.

1. Psychomotor slowing in depression is frequently reflected by delayed reaction times (RT). 2. The role of central arousal mechanisms in response slowing was examined by comparing scalp-recorded slow negative potentials of depressed patients with normal controls in two separate studies. 3. Varying fore-warned RT conditions elicited contingent negative variation (CNV) waveforms and the resultant mid-point amplitudes of these waveforms together with orienting (O-wave), expectancy (E-wave) and post-imperative negative variation (PINV) component amplitudes and sensory evoked responses (N1, P2) were compared between groups. 4. RTs were significantly slowed in depressed patients and the patient group exhibited consistently larger PINV amplitudes. Depending on the RT condition, patients also exhibited larger mid-point CNV amplitudes and smaller N1 and P2 amplitudes.

Adult↗
PubMed1991

Locus coeruleus and dorsal pontine reticular influences on the gain of vestibulospinal reflexes.

Experimental anatomical and physiological studies have shown that noradrenergic locus coeruleus (LC) neurons, which are NE-sensitive due to inhibitory adrenoceptors, send inhibitory afferents to neurons of the peri-LC alpha and the adjacent dorsal pontine reticular formation (pRF); on the other hand these tegmental neurons, which are, in part at least, cholinergic as well as cholinoceptive, send excitatory afferents to the medullary inhibitory reticulospinal (RS) system. Experiments performed in precollicular decerebrate cats indicate that these pontine structures exert a regulatory influence on posture as well as on the gain of vestibulospinal (VS) reflexes. In particular, the increased discharge of dorsal pontine reticular neurons, and the related inhibitory RS neurons induced by microinjection of cholinergic agonists into the peri-LC alpha and the adjacent pRF of one side, decreased the postural activity, but greatly increased the response gain of the ipsilateral triceps brachii in response to stimulation of labyrinth receptors resulting from roll tilt of the animal (at 0.15 Hz, +/- 10 degrees). Similar results were also obtained when the discharge of these pontine and medullary reticular neurons was raised, either by local injection into the peri-LC alpha and the dorsal pRF of the beta-adrenergic antagonist propranolol, which blocked the inhibitory influence of the noradrenergic LC neurons on these structures, or by local injection into the LC complex of an alpha 2- or beta-adrenergic agonist (clonidine or isoproterenol) which led to functional inactivation of the noradrenergic neurons; in the latter case the effects were bilateral. Just the opposite results were obtained after microinjection into the LC of a cholinergic agonist, leading to activation of the corresponding neurons. Evidence was also presented indicating that the cholinergic excitatory afferents to the LC originated from the ipsilateral dorsal pRF. The effects described above were dose-dependent and site-specific, as shown by histological controls. Under given conditions, the decrease in postural activity induced either by direct activation of presumptive cholinergic and cholinoceptive pRF neurons or by inactivation of noradrenergic and NE-sensitive LC neurons was followed by transient episodes of postural atonia which lasted several minutes and affected the ipsilateral and sometimes also the contralateral limbs. In these instances, the EMG modulation of the corresponding triceps brachii to animal tilt was suppressed. These findings suggest two different ranges of operation for the noradrenergic and cholinergic structures located in the dorsolateral pontine tegmentum, leading either to a decrease or to an increase in gain of the VS reflexes. The cellular basis of these gain changes is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1991

The contribution of diffusion to the termination of penicillin-induced convulsive activity in the awake rat.

1. Experiments were performed to investigate the contribution of diffusion to the termination of PCN induced convulsive (epileptiform) activity in the awake rat. The basic question was whether convulsive activity terminates at the same critical concentration Ct of PCN independently of the concentration Co of PCN injected into the superficial layer of the foreleg field of the right motor cortex. Different concentrations Co were used, the lowest being 16 IU PCN/0.5 microliters saline, the largest 1000 IU PCN/0.5 microliters saline. The convulsive activity was recorded by means of the electroencephalogram (EEG). 2. Mathematical calculations concerning the diffusion of the substances were performed by using the diffusion equation with a PCN diffusion coefficient D = 3.52 x 10(-4) mm2/s and the tortuosity factor lambda = 1.62. 3. The lowest dose of PCN used was considered as a threshold dose for acute induction of convulsive activity because only 4 out of 9 rats treated with 16 IU PCN developed epileptiform activity. For the range of doses between 16 and 32 IU, the median frequency of convulsive potentials was dose-dependent, and increased from 7.9 to 13.8 pot./min, respectively. For higher doses covering the range between 63 and 1000 IU, there was only an insignificant increase from 19.2 to 22.7 pot./min, respectively. 4. The median period of convulsive activity increased significantly (p less than 0.05 or less than 0.01) and monotonically from 19.5 min in rats treated with 16 IU PCN to 267 min after treatment with 1000 IU PCN. 5. At the end of the convulsive activity, the median critical concentration Ct within the artificial focus ranged from 1.75 to 1.31 IU/0.5 microliters saline in rats treated with 16 to 125 IU PCN, while after induction of convulsive activity with doses of 250, 500 or 1000 IU PCN, Ct gradually increased to 2.01, 2.83, and 3.75 IU/0.5 microliters, respectively. This means that the brain became less sensitive for PCN the longer the epileptiform activity lasted. 6. It is concluded that during long-lasting convulsive activity, the brain takes advantage of its plastic properties by eliciting counteracting mechanisms. These self-protective factors may utilize neuronal networks which needs some time to become effective in the control of the cortical activity.

Administration, Topical↗