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Biomedical subjects

K Baum

Publications and source records attributed to K Baum.

At least 19 recordsLinked to original sources
PubMed1998

[Differential diagnosis of distal peripheral nerve compression syndrome of the tibial nerve. Case report of primitive neuroectodermal tumor].

Tumors of the tibial nerve are not sufficiently taken into account in the diagnosis of tarsal tunnel syndromes (TTS). They may present with atrophy of the plantar flectors and with disturbances of sensory functions, but far more commonly with pain. Diagnosis is often only achieved after 1-2 years. Taking tumors into account when examining patients presenting with TTS may lead to a more rapid diagnosis and to improvement in patients' prognoses. We present the case of a 37-year-old female in whom a primitive neuroectodermal tumor (PNET) was found to be the cause of long-standing pain in the right foot.

Adult↗
PubMed1998

Leg blood flow during slow head-down tilt with and without leg venous congestion.

The effects of slow changes in body position on leg blood flow (LBF) were studied in nine healthy male subjects. Using a tilt table, sitting volunteers were tilted about 60 degrees backwards to a supine position within 40 s. To modify the venous filling in the legs, the tilt manoeuvre was repeated with congestion of the leg veins induced by two thigh cuffs inflated to a subdiastolic pressure of 60 mmHg. Doppler measurements in the femoral artery were used to estimate LBF. Additional Doppler measurements at the aortic root in five of the subjects were taken for the determination of cardiac output. The LBF was influenced by body position. In the control experiment it increased from 500 ml x min(-1) in the upright to 780 ml x min(-1) after 15 min in the supine position. A mean maximal value of 950 ml x min(-1) was observed 20 s after the tilt. Heart rate remained almost constant during the tilt phase, whereas stroke volume increased from 90 ml to 120 ml and it remained at that level after the cessation of the tilt. Congestion of the leg veins had no significant effect on heart rate, stroke volume and mean blood pressure. However, it increased vascular resistance of the leg during and after the tilt. After 15 min in the tilted position LBF amounted to 600 ml x min(-1). The results suggest that the filling of the leg veins is inversely related to leg blood flow. The most likely mechanism underlying this observation is a local effect of venous filling on vasomotor tone.

Adult↗
PubMed1997

Plasma ubiquinol-10 is decreased in patients with hyperlipidaemia.

Ubiquinol-10, the reduced form of ubiquinone-10 (coenzyme Q10), is a potent lipophilic antioxidant present in nearly all human tissues. The exceptional oxidative lability of ubiquinol-10 implies that it may represent a sensitive index of oxidative stress. The present study was undertaken to assess the hypothesis that the level of ubiquinol-10 in human plasma can discriminate between healthy subjects and patients who are expected to be subjected to an increased oxidative stress in vivo. Using a newly developed method, we measured plasma ubiquinol-10 in 38 hyperlipidaemic patients with and without further complications, such as coronary heart disease, hypertension, or liver disease, and in 30 healthy subjects. The oxidizability of plasma samples obtained from hyperlipidaemic patients was found to be increased in comparison with control subjects, suggesting that the patients were subjected to a higher oxidative stress in vivo than the controls. Plasma ubiquinol-10, expressed as a percentage of total ubiquinol-10 + ubiquinone-10 or normalized to plasma lipids, was lower in the patients than in controls (P = 0.001 and 0.008, respectively). The proportion of ubiquinol-10 decreased in the order young controls > aged controls > hyperlipidaemic patients without complications > hyperlipidaemic patients with complications (P = 0.003). A negative correlation was found between the proportion of ubiquinol-10 and plasma triglycerides. The hyperlipidaemic patients with hypertension had a lower proportion of ubiquinol-10 than subjects without. When the study population was divided into smokers and non-smokers, plasma ubiquinol-10 was found to be reduced amongst smokers, independently of whether it was expressed as a percentage of total ubiquinol-10 + ubiquinone-10 (P = 0.006) or normalized to plasma lipids (P = 0.009). These data suggest that the level of ubiquinol-10 in human plasma may represent a sensitive index of oxidative stress in vivo especially indicative of early oxidative damage. Measuring plasma ubiquinol-10 can be proposed as a practical approach to assess oxidative stress in humans.

Adult↗
PubMed1997

Improved ballistic transient transformation conditions for tomato fruit allow identification of organ-specific contributions of I-box and G-box to the RBCS2 promoter activity.

An improved protocol for the ballistic transient transformation of developing tomato (Lycopersicon esculentum) fruits is reported, which allows high-resolution cis-analysis of fruit-specific transcriptional activation. The tomato RBCS2 promoter fused to the firefly luciferase gene was used as a model system for this study. Osmotic treatment of fruit slices before, during and after particle bombardment, together with the optimization of bombardment conditions, resulted in a 100-fold increase in RBCS2 promoter-driven transient luciferase expression compared with previously reported protocols. Under these conditions, the transformed RBCS2 promoter was shown to be properly regulated in a developmental fashion. A cis-analysis of the RBCS2 promoter was performed. A 37 bp domain is required for high-level RBCS2 promoter activity both in leaves and young fruits. Two conserved sequence elements within this domain, an I-box element (GATAAG) and a G-box element (CACGTG), are necessary for its activity in leaves. In contrast, in young fruits, the G-box is the single dominant cis-acting element. These findings are discussed with respect to the proposed functions of G-box and I-box binding factors in regulating plant genes in different organs.

Animals↗
PubMed1997

Alternate finger tapping test in patients with migraine.

Migraine patients are thought to show some cognitive dysfunction and slight structural abnormalities in the white matter of the brain, whereas most patients with multiple sclerosis (MS) are known to have numerous white matter lesions, often affecting the corpus callosum. To demonstrate psychomotor dysfunction, an alternate finger tapping task (a-FTT) on a PC was administered to controls (n = 41), migraine patients (n = 25), and multiple sclerosis patients (n = 22). Five MS patients with secondary callosal atrophy detected by MRI were also investigated as a separate group. Significant slowing was demonstrated in migraine (P = 0.0005) and MS (P<0.0001). The poorest test results were found in patients with callosal atrophy. In summary, a-FTT on a PC is able to detect minimal psychomotor dysfunction in migraine.

Adolescent↗
PubMed1996

Calcified brain metastases from ovarian carcinoma.

A case of calcified brain metastases from ovarian carcinoma is reported. Lesions developing during chemotherapy were thought on Ct to be parasitic and, to avoid dissemination of pathogens, biopsy was postponed. When neurological deficits progressed, MRI showed perifocal oedema and contrast enhancement. It also showed a new noncalcified focus which was biopsied, proving to be a metastasis.

Brain Neoplasms↗
PubMed1996

Influence of gravity on cardiovascular reflexes from skeletal muscle receptors.

Skeletal muscles are important reflexogenic areas of the cardiovascular system. The afferent pathways of the reflex loops involve slow-conducting group III and group IV fibers that are excited by mechanical and chemical events in the muscle. The present paper reviews a series of experiments dealing with the question of whether those afferents are also influenced by gravitational forces. The results of these studies suggest the following answers: 1) gravitational forces can modulate cardiovascular reflexes from exercising skeletal muscles. 2) This effect is primarily due to changes in the interstitial fluid volume rather than to a direct mechanical influence, venous pressure, or venous volume. 3) The amplitudes of heart rate and blood pressure responses during exercise are inversely related to the local interstitial volume. Measurements during post-exercise circulatory arrest indicate that this sensitivity is mainly mediated by muscle chemoreceptors. These receptors, which also contribute to the spinal control of movement, generally appear to be sensitized by regional fluid losses and desensitized by overhydration of their environment.

Afferent Pathways↗
PubMed1995

Comparison of blood pressure and heart rate responses to isometric exercise and passive muscle stretch in humans.

The responses of mean arterial blood pressure (BPa) and heart rate (fc) to isometric contraction and passive stretch were compared in seven healthy male subjects at identical external forces. They were investigated in the sitting position with the hip and knee joint flexed to 90 degrees. Each subject performed two tests, separated by a day, in which the stimuli were applied in random order. After 5 min of rest they performed either 10-min static plantar flexion of one calf (200 N) or 10 min of passive calf muscle stretch at the same load. After 5-min rest, the second stimulus was applied for a further 10 min followed by 5-min rest. The second test was identical except for the sequence of the stimuli. The BPa was measured by a noninvasive and continuous method. Contraction of the vastus lateralis, gastrocnemius lateralis, and soleus muscles were determined by the myo-electric activity (electromyogram, EMG) by means of surface electrodes. The EMG activity of the vastus lateralis muscle remained at resting values throughout the experiments. Increases in EMG activity could only be detected for the triceps surae muscles during isometric contraction. During the initial 2 min of stimulation the BPa and fc responses to active contraction and passive stretch were comparable. Thereafter, both parameters showed significantly higher values during contraction. It was concluded that mechanical stress may have contributed to the early response of BPa during both passive stretch and voluntary contraction but that chemical stimuli were needed to maintain the peripheral cardiovascular drive.

Blood Pressure↗
PubMed1995

Developmental pathways to schizophrenia: behavioral subtypes.

This study examined childhood behavior problems in schizophrenic patients and their healthy siblings. Childhood Behavior Checklist (T. Achenbach, 1991) ratings were obtained from retrospective maternal reports, for 4 age periods: birth to 4 years, 4 to 8 years, 8 to 12 years, and 12 to 16 years. The results indicated that the patients had a variety of childhood behavior problems when compared to their siblings and that the various types of problems differed in their developmental course. Cluster analysis was conducted on the childhood behavior ratings for the schizophrenic patients, and 2 subgroups emerged. Cluster I showed more pronounced behavioral problems than Cluster II, and some of these problems were apparent in early childhood and increased with age. Cluster I also demonstrated greater neuromotor abnormalities in childhood.

Adolescent↗
PubMed1995

Time courses of cardiac output and oxygen uptake following stepwise increases in exercise intensity.

The adjustment of pulmonary oxygen uptake (VO2) following a step increase in work rate has been characterized as consisting of an early "cardiodynamic" component with unchanged mixed-venous O2-content ("phase 1") and a subsequent "metabolic" component ("phase 2") starting when venous blood from the muscle arrives at the lungs. The aim of the present study was to investigate whether the onset of phase 2 actually indicates the arrival of blood influenced by the altered muscle metabolism. Parallel measurements of cardiac output (Doppler technique) and VO2 (breath-by-breath measurements at the mouth) were performed in eight subjects during step increases in exercise intensity (from a 20 W baseline to either 80 W, 120 W, 160 W or 200 W). To vary the absolute cardiac output values for given muscle VO2 the subjects exercised both in upright and supine position. Individual time-courses of the arterio-venous O2 difference (a-v delta O2) were computed from cardiac output and VO2 data. Independent of body position two clear-cut phases of similar duration were seen both in VO2 and in the computed a-v delta O2. The duration of the first component with unchanged a-v delta O2 was about 20 s at the lowest step amplitudes (20-80 W and 20-120 W). It decreased to about 15 s for the 20-160 W and 20-200 W steps. At the lower exercise intensities the duration of phase 1 appears too long to be entirely due to the transit time of venous blood from the exercising muscles to the lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Postural effect on cardiac output, oxygen uptake and lactate during cycle exercise of varying intensity.

Owing to changes in cardiac output, blood volume distribution and the efficacy of the muscle pump, oxygen supply may differ during upright and supine cycle exercise. In the present study we measured, in parallel, circulatory (heart rate, stroke volume, blood pressure) and metabolic parameters (oxygen uptake, lactic acid concentration [la]) during incremental-exercise tests and at constant power levels ranging from mild to severe exercise. In supine position, cardiac output exceeded the upright values by 1.0-1.5 l.min-1 during rest, light ([la] < 2 mmol.l-1) and moderate ([la] = 2-4 mmol.l-1) exercise. At higher exercise intensities the cardiac output in an upright subject approached and eventually slightly exceeded the supine values. For both rest-exercise transitions and large-amplitude steps (delta W > or = 140 W) the cardiac output kinetics was significantly faster in upright cycling. The metabolic parameters (VO2 and [la]) showed no simple relationship to the circulatory data. In light to moderate exercise they were unaffected by body position. Only in severe exercise, when cardiac output differences became minimal, could significant influences be observed: with supine body posture, [la] started to rise earlier and maximal power (delta W = 23 W) and exercise duration (64 s) were significantly reduced. However, the maximal [la] value after exercise was identical in both positions. The present findings generally show advantages of upright cycling only for severe exercise. With lower workloads the less effective muscle pump in the supine position appears to be compensated for by the improved central circulatory conditions and local vasodilatation.

Adult↗
PubMed1994

Mixed connective tissue disease: recurrent episodes of optic neuropathy and transverse myelopathy. Successful treatment with plasmapheresis.

Severe neuropsychiatric manifestations in mixed connective tissue disease (MCTD) are thought to be quite rare. We report an unusual case of MCTD with recurrent optic neuropathy and transverse myelopathy suggestive of a relapsing-remitting demyelinating disorder. Symptoms responded dramatically to a treatment with plasmapheresis and immunosuppressive medication.

Adult↗
PubMed1994

Early leg blood flow adjustment during dynamic foot plantarflexions in upright and supine body position.

The time courses of leg blood flow, systolic peak velocity, heart rate and blood pressure have been studied in nine health volunteers during dynamic exercise in upright sitting and in a tilted sitting body position. In both positions the subjects performed single and repeated foot plantarflexions against light and moderate forces corresponding to 5%-10% and 25%-30% of maximal voluntary contraction. The following measurement techniques were used: Doppler ultrasound method (blood flow parameters), FINAPRES device (arterial blood pressure) and standard ECG chest leads (heart rate). At rest the supine blood flow parameters measured in the arteria femoralis were significantly higher than in the upright sitting position. In both positions, even one single plantarflexion at the light exercise intensity caused significant increases in blood flow for almost 20s. The major part of the blood flow response to repeated contractions always occurred within the first 10s at virtually unchanged blood pressures. During this initial phase upright leg blood flow increased by factors of 2.5 (light exercise) and 3.1 (moderate exercise). The corresponding values in the tilted sitting posture were 1.7 and 1.9, respectively. The initial increases in the upright position were too large to be attributed only to the increase of the perfusion pressure caused by the withdrawal of the hydrostatic pressure on the venous side ("muscle pump"). Additional, fast decreases in local resistance have to be considered. In the supine posture effects on local resistance have to be taken into account for the early increases in blood flow since hydrostatic effects on arterio-venous pressure differences are too small. The present findings indicate that the effects of repeated contraction-relaxation cycles on the early adjustment of muscle blood flow are not sufficiently described by a "muscle pump" that induces only venous volume shifts and hydrostatic pressure changes. Additional fast effects on local resistance have to be taken into account.

Adult↗
PubMed1994

VO2 and cardiac output during rest-exercise and exercise-exercise transients.

The dynamics of external gas exchange during exercise is influenced by pulmonary, cardiovascular, and metabolic factors. During rest-exercise transitions the interaction of these factors is more complex than during exercise-exercise transients. In the present study, we directly compared oxygen uptake (VO2) and cardiac output (CO) responses to step changes in exercise intensity. Nine students performed the following step changes on a bicycle ergometer in upright body position: rest-20W, 20W-80W, 20-140W. VO2 was measured breath-by-breath while CO was determined beat-by-beat by means of a Doppler device. The probe was positioned in the suprasternal notch and directed towards the aortic root. When starting from the 20 W baseline the VO2 responses showed a first, mainly cardio-vascular component over the first 30 s, followed by a second, metabolic component at constant CO. The rest-exercise transients displayed two additional early features. First, there was a very rapid VO2 increase during the initial breathing cycles of the on-transient. This was probably caused by events in the lungs or the pulmonary circulation. Second, the CO attained its steady-state level in about 10 s. This suggests a sudden increase in venous return. The present results generally show that both the VO2 and CO kinetics are faster when exercise in the upright body position is started from rest.

Adult↗
PubMed1994

[Multiple sclerosis. Clinical topodiagnosis in comparison with cerebral MRI findings].

Clinicotopographic correlations were performed in a larger group of patients with multiple sclerosis (n = 121). In the assessment of two raters working independently from one another, 73% of all clinical brainstem findings (n = 74) could be traced back to demyelination plaques in the supposed localization as visualized by MRI. The clinical topodiagnostic was especially in accordance with MRI findings concerning internuclear ophthalmoplegia (85%) and abducens palsy (79%). Cerebellar dysfunctions (n = 60) correlated with morphological findings in 87%. More than half of all patients with cerebellar and brainstem symptoms exhibited a periventricular demyelination around the 4th ventricle which was associated with the clinical topodiagnostic. Unequivocal MRI correlations could be hardly found for clinical findings of low topodiagnostical value (symptoms of the long motor and sensory pathways). The clinical status as expressed by Kurtzke's EDSS reflects the extent of cerebral demyelination as seen by MRI only in a larger patient group.

Adolescent↗
PubMed1993

Effect of graded changes in extracellular muscle volume on cardiovascular drives during static exercise.

The effects of graded changes in peripheral extracellular volume on heart rate and blood pressure during isometric exercise were studied in 12 healthy male subjects. Each subject performed four calf ergometer tests with each calf. In all tests, static plantar flexion of one foot was performed in a supine body position with the knee joint flexed to 90 degrees. After a pre-exercise period of 18 min, during which the calf volume was manipulated, the subjects had to counteract a spring force of 120 N for 8 min. In the pre-exercise period the peripheral extracellular volume of the calf muscle to be tested was manipulated in four ways. Test 1:15 min of rest in the exercise position. During the last 3.5 min, the calf volume was increased by venous congestion [80 mmHg (10.67 kPa) applied to the distal part of the thigh by pneumatic cuff]. Test 2: the same protocol as in test 1 but with 7.5-min venous congestion. Test 3:15 min of venous congestion. Test 4: the calf volume was decreased by a negative hydrostatic pressure for 15 min (calf raised about 40 cm above heart level). To clamp the changed calf volume, the thigh cuff was rapidly inflated to 300 mmHg (40.0 kPa) at the end of the volume manipulation and the subjects remained resting for a further 3 min. In test 4, the leg of the subject was passively brought into the exercise position. The occlusion was maintained until 2 min after exercise. The calf volume manipulation led to changes ranging from +105 ml (test 3) to -134 ml (test 4) as measured by water displacement plethysmography. The blood pressure response to exercise was inversely related to the calf volume changes while the heart rate response during exercise showed no clearcut relationship to the pretreatments.

Adult↗