Search PubMed⌕ Search

Biomedical subjects

J Kasper

Publications and source records attributed to J Kasper.

At least 55 records · Page 3Linked to original sources
PubMed1990

Ischemic stroke due to protein C deficiency.

Plasma protein C exerts anticoagulatory effects by inactivating factors V and VIII. Hereditary protein C deficiency is transmitted as an autosomal dominant disorder. Homozygous individuals usually develop purpura fulminans as newborns; heterozygous protein C-deficient individuals are at increased risk for venous thrombosis and pulmonary embolism. However, arterial thrombosis has been only rarely observed. We describe a young patient with heterozygous protein C deficiency who experienced a severe stroke due to thrombotic occlusion of the left middle cerebral artery.

Adult↗
PubMed1990

[Does early echocardiography contribute to the prediction of complications in acute myocardial infarct?].

The authors give an account of their experience with early echocardiography (two-dimensional examination, division of left ventricle into 20 segments) during stratification of patients with acute myocardial infarction (a group of patients with a first infarction). They evaluated the presence or absence of serious asynergy (akinesia or dyskinesia) of the left ventricle and its relationship to the incidence of complications (serious dysrhythmia, decompensation, cardiogenic shock and death). The relations between asynergy and different complications were tested by means of multidimensional contingency tables. A statistically significant partial correlation (p less than 0.01) was recorded between the most serious asynergy and the presence of decompensation and also cardiogenic shock. The detection of serious asynergy of the left ventricle is a useful stratification indicator of the risk of the acute infarction, as no patient without asynergy died or overcame cardiogenic shock.

Adult↗
PubMed1990

[Ventricular tachycardia in patients with arrhythmogenic right ventricular dysplasia. Electrophysiologic characteristics and testing of the effectiveness of anti-arrhythmia therapy].

The authors present a clinical and electrophysiological characteristic in two cases of symptomatic sustained ventricular tachycardia (VT) with a QRS morphology of left bundle branch block, refractory to common antiarrhythmic treatment. It was confirmed that the mechanism of this arrhythmia associated with a high risk of sudden death is the reentry phenomenon and the authors analyzed its relationship to arrhythmogenic dysplasia of the right ventricle. In a way uncommon in our literature the authors demonstrate the importance of comprehensive electrophysiological examination in these serious cases and its usefulness in confirming the origin of VT in the right ventricle, its importance for mapping the accurate localization of tachycardia and the investigation of effectiveness of drugs and the evaluation of aptness of non-pharmacological treatment.

Adult↗
PubMed1989

Effects of muscle and cutaneous hindlimb afferents on L4 neurons whose activity is modulated by neck rotation.

We recorded extracellularly, in decerebrate, labyrinthectomized cats, from spontaneously active L4 neurons whose activity was modulated by head rotation, and studied the effects of stimulation of ipsilateral hindlimb nerves. Rotation of the head about the longitudinal (roll) axis was more effective than rotation about the transverse (pitch) axis or vertical (yaw) axis for this group of neurons. Most units received convergent excitatory or inhibitory inputs from several nerves, with excitation being more prominent. The most effective muscle nerves were quadriceps (37/43 neurons), sartorius (19/21) and tibialis anterior (17/35); stimulation of biceps posterior-semitendinosus, biceps anterior-semimembranosus, or gastrocnemius rarely influenced the firing of the neurons. Group I effects were present in only a small fraction of neurons; however, short latency (central latency less than or equal to 5 ms) group II effects were observed in almost one-third. Longer latency group II as well as group III inputs were also common. All neurons received inputs from mixed and cutaneous nerves which usually had low thresholds and central latencies greater than 5 ms. Most recording sites were in medial lamina VII or lamina VIII; some of the units were identified by antidromic stimulation as propriospinal neurons which projected to the lumbar enlargement.

Action Potentials↗
PubMed1989

Biased selection and regression toward the mean in three Medicare HMO demonstrations: a survival analysis of enrollees and disenrollees.

Mortality of aged Medicare enrollees in three demonstration health maintenance organizations (HMOs) was compared with that of three cohorts of local fee-for-service (FFS) beneficiaries as a measure of group differences in health status. Mortality of the HMO and FFS cohorts was tracked via life-table analysis for 6 years after enrollment to measure the persistence of health status differences existing at enrollment. After adjustment for age, sex, Medicaid-eligibility, and institutional status, HMO enrollee mortality was lower than FFS at all three plans in the first year after enrollment. Enrollee mortality at two plans increased to near FFS levels in year 2 and remained relatively stable thereafter. Enrollee mortality at the third plan increased toward FFS levels more gradually and was significantly below FFS levels for the first 5 years of follow-up. Mortality of disenrollees in the 2 years after disenrollment was significantly higher than that of the continuously enrolled in one plan and marginally significantly higher in a second. These findings suggest a pattern of favorable selection at enrollment, followed by different rates of decay in the favorable health status of enrollees. Other health status measures may exhibit different patterns, however. Selection effects may cause payments based on Medicare's AAPCC to be too high or low, in some cases for several years after enrollment.

Aged↗
PubMed1989

Neck muscle spindle activity in the decerebrate, unparalyzed cat: dynamics and influence of vestibular stimulation.

1. Using floating electrodes, we recorded from neck-muscle spindle afferents in the C2 dorsal root ganglion of the decerebrate cat. Nerves to dorsal neck muscles were cut so that the afferents presumably originated mainly from ventral and ventrolateral perivertebral muscles and sternocleidomastoid. One goal of our experiments was to study possible vestibular influence exerted on these spindles via the fusimotor system. Unparalyzed preparations were therefore used. 2. Stimuli consisted of sinusoidal rotations in vertical planes. Neck tilt stretched neck muscles, whereas whole-body tilt stimulated vestibular receptors. 3. For each afferent we first determined the most effective direction of neck tilt, then used stimuli oriented close to this direction to study response dynamics, particularly gain of responses to stimuli of different amplitudes (0.5-7.5 degrees). 4. Three-quarters of the afferents failed to respond to 0.5 degrees, 0.2-Hz neck rotations. Stimuli that were effective usually elicited responses that had low gain and were linear over the whole range of amplitudes. Only a few afferents had behavior typical of spindle primary afferents: high-gain responses to small sinusoidal stimuli, gain decreasing as stimulus amplitude increases. This prevalence of static spindle responses in the unparalyzed cat is in striking contrast to results obtained on neck-muscle spindles in paralyzed, decerebrate cats, and on hindlimb extensor muscle spindles in decerebrate, unparalyzed cats. 5. Paralysis produced by injection of Flaxedil changed the behavior of 2/4 spindle afferents tested, causing the appearance of high-gain responses to 0.5 degrees stimuli and of nonlinear behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1989

Neck-vestibular interaction in the vestibular nuclei. A dynamic, two-dimensional study.

In decerebrate cats we used response dynamics to classify neurons in Deiters' nucleus and the rostral descending nucleus as receiving input from vertical canals, otolith organs (utricle) or canal + otolith. Many of these neurons, particularly those with convergent vestibular input (canal + otolith, canal + canal) and preferred stimulus directions near roll, also received neck input. Neck and vestibular response vectors tended to point in opposite directions. Neck and vestibular response dynamics were often well matched, so that combined stimuli (head rotation) produced no response over a wide frequency range. In some cases differing dynamics produced an output that appeared to code head position.

Animals↗
PubMed1989

[The development of myocardial infarct in a patient treated with 5-fluorouracil].

The authors describe the first case of myocardial infarction in their department which occurred during 5-fluorouracil treatment. In a 37 year-old patient two years before the infarction an epidermoid carcinoma of the lower lip was found. The patient was subjected to operation and radiotherapy. Because of a relapse of the process after one year the patient was re-operated with subsequent chemotherapy (vincristine, methotrexate, cis-platinum). Because the effect was not satisfactory, after another year 5-fluorouracil treatment was started (i.v. infusion of 3000 mg in two days). In the course of the infusion the patient developed the clinical picture of a non-transmural infarction of the anterior wall. The course was uncomplicated. The ECG returned to normal on the 9th day after discontinuation of 5-fluorouracil treatment. The effect of 5-fluorouracil on the heart is explained by a coronary vascular spasm. The authors recommend therefore administration of calcium blockers.

Adult↗
PubMed1988

Peripheral input to L4 neurons whose activity is modulated by neck rotation.

We studied, in decerebrate cats, peripheral input from the ipsilateral hindlimb to L4 neurons whose activity was modulated by neck rotation ('neck-modulated neurons'). Most neurons received convergent input from muscle, cutaneous and mixed nerves. In about half the neurons muscle input consisted of short-latency group I or group II excitation or inhibition, with group II effects far more frequent. Such synaptic actions were produced almost entirely by stimulation of quadriceps or sartorius. In the other neurons muscle afferents produced only late, diffuse excitation or inhibition, with thresholds usually in the group III range.

Animals↗
PubMed1988

Three-dimensional sensitivity and caudal projection of neck spindle afferents.

1. We recorded from neck muscle spindle afferents in the C2 dorsal root ganglion of the decerebrate cat using floating electrodes. The afferents presumably innervated mainly ventral and ventrolateral perivertebral muscles, and sternocleidomastoid. Stimuli consisted of combinations of rotatory head movements about the roll/pitch or pitch/yaw axes. An important difference from our earlier experiments (10) was the addition of yaw movement to the stimulus paradigm making possible a three-dimensional analysis of afferent behavior. 2. For each afferent we determined the most effective direction of tilt (orientation of the response vector) in three dimensions by using sinusoidal stimuli that combined pitch and roll, or pitch and yaw, or by measuring the gains to responses to roll, pitch, and yaw rotation. 3. Most afferents were sensitive to rotation around all three axes; pitch and yaw were usually more effective than roll. There was no indication of clustering of response vectors, as might be expected if the receptors were located in a small number of muscles each of which has receptors aligned in a homogeneous direction. 4. The responses of afferents were further studied using sinusoidal and trapezoidal stimuli aligned as closely as possible with the orientation of their response vector. The availability of the yaw stimulus made receptor classification based on response linearity, gain, and dynamic index more reliable than in our earlier experiments (10). 5. Muscle spindle responses were divided into three categories: A, B, and ambiguous. The evidence suggests that category A are probably spindle primary receptors and category B are secondaries. Ambiguous receptors have intermediate properties. 6. The caudal projection of spindle afferents was examined by delivering antidromic stimuli with a movable electrode on the surface of the ipsilateral dorsal column. Eighteen percent of the afferents projected to C4, and 14% as far as C5. Long caudal projections can be found in A, B, and ambiguous receptors with a range of directional sensitivities. 7. The evidence suggests that C2 spindle afferents make synapses in the midcervical segments with interneurons and propriospinal neurons that are part of the intraspinal pathway of the tonic neck reflex.

Action Potentials↗
PubMed1988

Response of vestibular neurons to head rotations in vertical planes. I. Response to vestibular stimulation.

1. We have studied, in decerebrate cats, the responses of neurons in the lateral and descending vestibular nuclei to whole-body rotations in vertical planes that activated vertical semicircular canal and utricular receptors. Some neurons were identified as vestibulospinal by antidromic stimulation with floating electrodes placed in C4. 2. The direction of tilt that caused maximal excitation (response vector orientation) of each neuron was determined. Neuron dynamics were then studied with sinusoidal stimuli closely aligned with the response vector orientation, in the range 0.02-1 Hz. A few cells, for which we could not identify a response vector, probably had spatial-temporal convergence. 3. On the basis of dynamics, neurons were classified as receiving their input primarily from vertical semicircular canals, primarily from the otolith organs, or from canal+otolith convergence. 4. Response vector orientations of canal-driven neurons were often near +45 degrees or -45 degrees with respect to the transverse (roll) plane, suggesting these neurons received excitatory input from the ipsilateral anterior or posterior canal, respectively. Some neurons had canal-related dynamics but vector orientations near roll, presumably because they received convergent input from the ipsilateral anterior and posterior canals. Few neurons had their vectors near pitch. 5. In the lateral vestibular nucleus, neurons with otolith organ input (pure otolith or otolith+canal) tended to have vector orientations closer to roll than to pitch. In the descending nucleus the responses were evenly divided between the roll and pitch quadrants. 6. We conclude that most of our neurons have dynamics and response vector orientations that make them good candidates to participate in vestibulospinal reflexes acting on the limbs, but not those acting on the neck.

Animals↗
PubMed1988

Response of vestibular neurons to head rotations in vertical planes. II. Response to neck stimulation and vestibular-neck interaction.

1. We have studied the responses of neurons in the lateral and descending vestibular nuclei of decerebrate cats to stimulation of neck receptors, produced by rotating the body in vertical planes with the head stationary. The responses to such neck stimulation were compared with the responses to vestibular stimulation produced by whole-body tilt, described in the preceding paper. 2. After determining the optimal vertical plane of neck rotation (response vector orientation), the dynamics of the neck response were studied over a frequency range of 0.02-1 Hz. The majority of the neurons were excited by neck rotations that brought the chin toward the ipsilateral side; most neurons responded better to roll than to pitch rotations. The typical neck response showed a low-frequency phase lead of 30 degrees, increasing to 60 degrees at higher frequencies, and a gain that increased about threefold per decade. 3. Neck input was found in about one-half of the vestibular-responsive neurons tested with vertical rotations. The presence of a neck response was correlated with the predominant vestibular input to these neurons; neck input was most prevalent on neurons with vestibular vector orientations near roll and receiving convergent vestibular input, either input from both ipsilateral vertical semicircular canals, or from canals plus the otolith organs. 4. Neurons with both vestibular and neck responses tend to have the respective orientation vectors pointing in opposite directions, i.e., a head tilt that produces an excitatory vestibular response would produce an inhibitory neck response. In addition, the gain components of these responses were similar. These results suggest that during head movements on a stationary body, these opposing neck and vestibular inputs will cancel each other. 5. Cancellation was observed in 12 out of 27 neurons tested with head rotation in the mid-frequency range. For most of the remaining neurons, the response to such a combined stimulus was greatly attenuated: the vestibular and neck interaction was largely antagonistic. 6. Neck response dynamics were similar to those of the vestibular input in many neurons, permitting cancellation to take place over a wide range of stimulus frequencies. Another pattern of interaction, observed in some neurons with canal input, produced responses to head rotation that had a relatively constant gain and remained in phase with position over the entire frequency range; such neurons possibly code head position in space.

Animals↗
PubMed1988

Chronic central nervous system involvement in Lyme borreliosis.

We describe four patients with marked chronic meningoencephalomyelitis caused by tick-transmitted Borrelia burgdorferi infection. Imaging techniques showed either MS-like lesions or evidence of vascular involvement, as in other spirochetal infections, especially in meningovascular syphilis.

Adult↗
PubMed1988

Septic complications in patients with permanent pacemakers.

Nine patients with implanted pacemakers had the diagnosis of septicaemia to endocarditis. The diagnosis was established on the basis of a repeatedly positive haemoculture. The interval since the first pacemaker implantation to the onset of sepsis to endocarditis was about 5 years. All nine patients had previous reoperation either of the pacemaker or its lead due to decubitus. While, in four patients, the route of infection was a pacemaker lead in its extravascular couse, in 5 patients the source of infection was a lead placed right in the venous system. All patients were treated with ATB according to the antibioticogram. 4 patients had the pacemaker lead extracted. In the remaining five, the pacemaker lead was removed by catheterization. All patients recovered. There is only one way of eliminating infection that caused the sepsis, that is, to remove the foreign body present in the patient - the pacemaker leas in this particular case.

Aged↗
PubMed1988

Myocardial infarction at young age.

In a group of 25 men after myocardial infarction (MI) at an age under 40 years the occurrence of risk factors of ischaemic heart disease, the results of both invasive and noninvasive investigations as well as other special examinations within one year after the attack of acute MI were analysed. In 36% there was a normal finding or nonsignificant stenosis on the coronary arteries (less than 50% lumen obstruction at coronary angiography); a significant stenosis was found in 64%, out of which only one coronary vessel was affected in 32%. Dominant risk factors were: smoking, lipid metabolism disturbances, hypertension and a positive family history. The average number of risk factors in the group with a normal finding on the coronary arteries was 2.55, and in the group with a significant coronary sclerosis 4.85. The risk of myocardial infarction is increased by the coexistence of heavy smoking habits and vigorous physical activity. No correlation was found between the extent and location of coronary sclerosis and the functional parametres and wall motion of the left ventricle. An analysis of occupational status before MI revealed that 52% of the patients were workers, 40% professional drivers and only 8% were clerks.

Adult↗
PubMed1987

Dynamics and directional sensitivity of neck muscle spindle responses to head rotation.

With the use of floating electrodes we recorded from the C2 dorsal root ganglion of decerebrate cats during sinusoidal and trapezoidal head rotation. Fifty-one spontaneously firing afferents were identified as muscle spindle endings. Some were identified by their excitatory response to injection of succinylcholine, others by the similarity of their behavior to that of endings excited by the drug. Because afferent input to the ganglion was restricted by sectioning most nerve trunks, most spindle endings were presumably located in ventral and ventrolateral perivertebral muscles. The firing of each spindle afferent was modulated most effectively by tilting the head in a specific direction; this direction was termed its response vector. Responses to sine waves and trapezoids were then studied with stimuli oriented as closely as possible to the vertical plane of this vector. Most spindle afferents could be classified in one of two categories. Those with high gain, pronounced nonlinearity, and high dynamic index were called type A. Those classified as type B had low gain, a fairly linear response, and low dynamic index. In response to small (0.5 degrees) stimuli, type A endings had phase leads of approximately 40 degrees at frequencies of sinusoidal stimulation of 0.02-0.1 Hz, increasing to approximately 80 degrees at 4 Hz; with larger (2.5 degrees) stimuli, phase was advanced by an additional 10-20 degrees at all frequencies. Phase of type B responses was less advanced than that of type A responses. Gain slopes of the two types of endings were similar. Bode plots of spindle afferents strongly resembled those of upper cervical neurons whose activity is modulated by head rotation. Each spindle afferent had a response vector whose direction remained stable with time, different frequencies of stimulation, and different stimulus amplitudes. The distribution of response vectors covered approximately 270 degrees, with a gap near nose down pitch. Changing initial head position usually had little effect on the direction of an afferent's response vector or on response dynamics. However, stimulation far from the best plane could transform a type A into a type B response. This raises the possibility that type B receptors could be type A receptors best stimulated by yaw and with only low sensitivity to stimulation in vertical planes. Type A receptors have all the properties of spindle primaries. The identification of type B receptors remains uncertain, because they may include secondary afferents as well as primaries stimulated far from their best three-dimensional vector.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗