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Biomedical subjects

M Kofler

Publications and source records attributed to M Kofler.

At least 19 recordsLinked to original sources
PubMed2004

Brain natriuretic peptide (BNP) in patients undergoing coronary artery bypass grafting.

BACKGROUND: This study was designed to examine plasma concentrations of BNP and its relation to hemodynamic parameters in patients (pts.) with coronary artery disease (CAD) undergoing coronary artery bypass grafting (CABG). METHODS: 21 pts. with CAD undergoing CABG were examined. The pts. were divided into two groups. Group I: normal left ventricular function (LVF); Group II: reduced LVF. Pre-, intra- and postoperative BNP and hemodynamic parameters were measured. The perioperative administration of inotropic drugs was documented. RESULTS: In both groups postoperative BNP increased to a peak 24 h postoperatively; although BNP concentrations were high 24 h postoperatively hemodynamic parameters were improved in both groups. In Group I the BNP peak did not correlate with any hemodynamic parameter nor with the use of inotropic drugs. In Group II the BNP peak was inversely correlated with CO and CI and positively correlated with the PCWP. There was no correlation with inotropic support. CONCLUSION: Postoperative peak of BNP after 24 h does not reflect a state of acute perioperative heart failure or myocardial damage. These results suggest that the gene expression, metabolism and biological activity of BNP may be altered after extracorporeal circulation. Further studies are warranted to reveal the actual triggers for BNP increase early after CABG.

Aged↗
PubMed2004

No benefit derived from repetitive transcranial magnetic stimulation in depression: a prospective, single centre, randomised, double blind, sham controlled "add on" trial.

Repetitive transcranial magnetic stimulation (rTMS) has been reported to demonstrate slight effects in the treatment of depression. Hence, a novel bilateral versus unilateral and sham stimulation design was applied to further assess rTMS' antidepressant effects. Forty one medication free patients with major depression, admitted to a psychiatric unit specialising in affective disorders, were consecutively randomised into 3 groups. Group A1 (n = 12) received unilateral active stimulation consisting of high frequency (hf) rTMS over the left dorsolateral prefrontal cortex (LDLPC) and subsequent sham low frequency (lf) rTMS over the right dorsolateral prefrontal cortex (RDLPC). Group A2 (n = 13) received simultaneous bilateral active stimulation consisting of hf-rTMS over the LDLPC and lf-rTMS over the RDLPC. Group C (n = 13) received bilateral sham stimulation. Stimulation was performed on 10 consecutive workdays. All patients received antidepressant medication on the first day of stimulation, which was continued during and after the stimulation period. As no significant difference in antidepressant outcome between group A1 and A2 was found, the two groups were pooled. The time course of the outcome variables Hamilton depression rating scale (HDRS(21)) and Beck depression inventory (days 0, 7, 14, 28) by repeated measures analysis of variance revealed no significant group differences (in terms of a group by time interaction), whereas there was a significant effect of time on all three outcome variables in all groups. The results suggest that rTMS as an "add on" strategy, applied in a unilateral and a bilateral stimulation paradigm, does not exert an additional antidepressant effect.

Major Depressive Disorder↗
PubMed2002

The erythrocyte adhesiveness/aggregation test for the detection of an acute phase response and for the assessment of its intensity.

We have developed a simple slide test and image analysis to reveal the state of erythrocyte adhesiveness/aggregation in the peripheral blood of patients with various degrees of the humoral acute phase response. The significant correlation between the results of the erythrocyte adhesiveness/aggregation test (EAAT), the erythrocyte sedimentation rate and fibrinogen concentration support the notion that it is possible to use the EAAT as a marker for the intensity of the acute phase response. Within a group of 860 individuals, we were able to differentiate effectively between groups of patients with a different intensity of humoral acute phase response. The present study confirms previous observations that support the applicability of the EAAT to routine clinical practice.

Acute-Phase Reaction↗
PubMed2001

Influence of gender on auditory startle responses.

The auditory startle reaction is considered a brainstem reflex in response to an unexpected loud stimulus. It may be abnormal in various neurological conditions. However, the influence of gender on physiological characteristics of auditory startle responses (ASRs) in humans has to date been studied only in orbicularis oculi muscle. We investigated 54 healthy adult subjects (27 males, 27 females). ASRs were elicited by binaural high-intensity auditory stimuli which differed randomly in tonal frequency and intensity (250 Hz-90 db; 500 Hz-105 dB; 750 Hz-110 db, 1000 Hz-110 dB nHL), presented through tubal insert phones. Reflex electromyographic activity was simultaneously recorded with surface electrodes from masseter, orbicularis oculi, sternocleidomastoid, biceps brachii, abductor pollicis brevis, rectus femoris, tibialis anterior, and soleus muscles. ASR probability was significantly lower, and ASR area under the curve was significantly smaller, in men versus women. Median onset latencies did not differ significantly, but tended to be shorter in the lower extremities of men despite greater body height. Habituation, measured as a reduction in response probability with repeated stimulation, was significant in all muscles except orbicularis oculi in both men and women. Our data provide evidence for a significant influence of gender on ASR characteristics. The observed differences are likely due to gender-specific variations of central processing in the brainstem centers involved in ASR generation, and should be taken into account when testing ASRs in health and disease.

Acoustic Stimulation↗
PubMed2001

Influence of age on auditory startle responses in humans.

The auditory startle reaction is considered a brainstem reflex in response to an unexpected loud stimulus. We investigated the influence of age on auditory startle responses (ASRs) in 54 adult healthy subjects separated in three age groups (below 30; 30 to 50; above 50 years). ASRs were elicited by auditory stimuli randomly presented through tubal insert phones. Reflex electromyographic activity was simultaneously recorded from eight facial, neck, and extremity muscles. ASR probability was lower in extremity muscles of younger versus older subjects, but did not differ among age groups in facial and neck muscles. Median ASR latencies were significantly shorter in all muscles of younger versus older subjects. Our data provide evidence of a significant influence of age on ASRs. The observed differences are likely due to age-specific variations of central processing in the brainstem centers involved in ASR generation.

Acoustic Stimulation↗
PubMed2001

The auditory startle reaction in parkinsonian disorders.

The auditory startle reaction to an unexpected loud stimulus is regarded as a brainstem reflex originating in the nucleus reticularis pontis caudalis and being distributed up the brainstem and down the spinal cord along slowly conducting pathways. Auditory startle responses (ASR) have been reported absent or reduced in progressive supranuclear palsy (PSP), and delayed in Parkinson's disease (PD), but normal in multiple-system atrophy (MSA). For the first time we studied ASR in patients fulfilling the clinical criteria of dementia with Lewy bodies (DLB) (n = 8), a neurodegenerative disorder characterized by cortical and subcortical depositions of Lewy bodies resulting in parkinsonism and progressive cognitive decline. For comparison, we also investigated patients with PD (n = 10), MSA (n = 7), PSP (n = 10), and age-matched healthy controls (n = 10). ASR were elicited by binaural high-intensity auditory stimuli. Surface electromyographic activity was simultaneously recorded from facial, upper, and lower extremity muscles. For each muscle, we assessed response probability and measured latency, amplitude, duration, and habituation rate. Patients with DLB had fewer and abnormally delayed ASR of low amplitude and short duration in extremity muscles compared to healthy controls. Furthermore, we confirm and extend previous findings of abnormal ASR in PSP and PD, and also demonstrate exaggerated ASR in extremity muscles of MSA patients. The different patterns of ASR abnormalities may reflect distinct types of brainstem dysfunction in DLB.

Acoustic Stimulation↗
PubMed2001

Image analysis for the detection of increased erythrocyte, leukocyte and platelet adhesiveness/aggregation in the peripheral blood of patients with diabetes mellitus.

Increased erythrocyte, leukocyte, and platelet adhesiveness and aggregation may contribute to the development of ischemic vascular conditions in diabetic patients. They have been described by using different diagnostic systems and following various ex vivo manipulations. We have adopted a simple slide test and image analysis to reveal the adhesiveness and aggregation of the three cellular elements in a picture that is obtained from one single citrated venous blood sample presented on a glass slide. A significant increment in the degree of adhesiveness/aggregation of erythrocytes, leukocytes and platelets was noted in 29 patients with diabetes mellitus as opposed to age- and gender-matched healthy controls. It is feasible to look at the increased state of adhesiveness/aggregation of erythrocytes, leukocytes and platelets present in their native milieu and following minimal manipulation by using an almost real time and low cost procedure.

Adult↗
PubMed2001

Cutaneous and mixed nerve silent periods in syringomyelia.

OBJECTIVES AND METHODS: We studied cutaneous and mixed nerve silent periods (CSP, MNSP) in 4 patients with cervical syringomyelia documented by magnetic resonance imaging who on clinical examination presented with unilateral hypalgesia and hypothermesthesia. In addition, we recorded upper and lower extremity somatosensory and motor evoked potentials (SEP, MEP), and cortical silent periods. RESULTS: In all patients, CSP and the later portion of MNSP were absent or shortened on their affected side, while both were normal on their unaffected side. In all patients, SEP latencies were normal following both median and tibial nerve stimulation. In two patients, the amplitude N13 (median nerve SEP), and in one patient each the amplitudes N20 (median nerve SEP) and P37 (tibial nerve SEP) were reduced. Central motor conduction time was prolonged to abductor digiti minimi muscle in one patient on the affected side, but was normal to tibialis anterior muscle in all patients. Cortical silent periods where present bilaterally in spite of unilateral complete absence of CSP and MNSP in two subjects tested. Loss of CSP and MNSP were a sensitive parameter of spinal cord dysfunction in syringomyelia. The cervical median nerve SEP response N13 reflected gray matter involvement, while corticospinal tract dysfunction was less frequently observed. CONCLUSION: Our data suggest that CSP and later portion of MNSP are generated at the spinal level by the same small myelinated A-delta fibers, and that their central network is distinct from large diameter fiber afferents and efferents.

Adolescent↗
PubMed2001

Modulation of upper extremity motor evoked potentials by cutaneous afferents in humans.

The excitability of motoneurons controlling upper limb muscles in humans may vary with cutaneous nerve stimulation. We investigated the effect of noxious and non-noxious conditioning stimuli applied to right and left digit II and right digit V on motor evoked potentials (MEPs) recorded from right thenar eminence, abductor digiti minimi, biceps and triceps brachii muscles in twelve healthy subjects. Transcranial magnetic stimulation (TMS) was applied at interstimulus intervals (ISI) ranging from 40 to 160 ms following conditioning distal digital stimulation. TMS and transcranial electrical stimulation (TES) were compared at ISI 80 ms. Painful digital stimulation caused differential MEP amplitude modulation with an early maximum inhibition in hand muscles and triceps brachii followed by a maximum facilitation in arm muscles. Stimulation of different digits elicited a similar pattern of MEP modulation, which largely paralleled the behavior of cutaneous silent periods in the same muscles. Contralateral digital stimulation was less effective. MEPs following TMS and TES did not differ in their response to noxious digital stimulation. MEP latencies were shortened by cutaneous stimuli. The observed effects were stimulus intensity dependent. We conclude that activation of A-alpha and A-delta fibers gives rise to complex modulatory effects on upper limb motoneuron pools. A-delta fibers initiate a spinal reflex resulting in MEP amplitude reduction in muscles involved in reaching and grasping, and MEP amplitude facilitation in muscles involved in withdrawal. These findings suggest a protective reflex mediated by A-delta fibers that protects the hand from harm. A-alpha fibers induce MEP latency shortening possibly via a transcortical excitatory loop.

Adult↗
PubMed2000

Nociceptive fingertip stimulation inhibits synergistic motoneuron pools in the human upper limb.

BACKGROUND: Activation of distinct muscle groups organized in a stereotyped manner ("muscle synergies") is thought to underlie the production of movement by the vertebrate spinal cord. This results in movement with minimum effort and maximum efficiency. The question of how the vertebrate nervous system inhibits ongoing muscle activity is central to the study of the neural control of movement. OBJECTIVE: To investigate the strategy used by the human spinal cord to rapidly inhibit muscle activation in the upper limb. METHODS: The authors performed a series of experiments in 10 healthy subjects to assess the effect of nociceptive cutaneous stimulation on voluntarily contracting upper limb muscles. They recorded the electromyogram (EMG) with surface electrodes placed over various upper limb muscles. RESULTS: The authors found evidence of a simple inhibitory strategy that 1) was dependent on the intensity of the stimulus, 2) was maximally evoked when stimulation was applied to the fingertips, 3) preceded the earliest onset of voluntary muscle relaxation, and 4) produced inhibition of EMG activity in specific upper limb muscle groups. Nociceptive fingertip stimulation preferentially inhibited contraction of synergistic muscles involved in reaching and grasping (intrinsic hand muscles, forearm flexors, triceps) while having little effect on biceps or deltoid. CONCLUSIONS: Neural circuitry within the human spinal cord is organized to inhibit movement by rapidly deactivating muscles that constitute distinct muscle synergies. This strategy of selective and concurrent deactivation of the same basic elements that produce synergistic movement greatly simplifies motor control.

Adult↗
PubMed2000

Somatosensory evoked potentials in progressive supranuclear palsy.

We report median and digital nerve somatosensory evoked potentials (SEPs) in 14 patients with probable progressive supranuclear palsy (PSP) along with transcortical long-loop reflexes, motor evoked potentials, and auditory startle responses. Enlarged cortical responses were found in 14 median and 13 digital nerve SEP studies, while long-loop reflexes were increased in only one patient. All motor evoked potential studies were normal. Auditory startle responses were either absent or reduced in 11 patients. The observed neurophysiological abnormalities may reflect cortical hyperexcitability but are distinct from those in other disorders associated with giant SEPs, such as progressive myoclonus epilepsy. A number of groups reported widespread cortical changes in addition to the characteristic subcortical neurofibrillary degeneration in post-mortem confirmed PSP. However, clinical features reflecting cortical dysfunction such as ideomotor apraxia and cortical sensory loss are uncommon in classical PSP. Furthermore, frontal lobe dementia which is frequently present in PSP patients, is thought to be of subcortical origin resulting from striato-frontal deafferentation. We propose that cortical neurofibrillary pathology may lead to subclinical intracortical disinhibition accounting for the enlarged cortical SEPs in PSP.

Aged↗
PubMed1999

Underestimated health hazard: proposal for an ergonomic microscope workstation.

Working daily for a long time with a standard microscope causes back pain, fibromyalgia, or tension headache in up to 80% of microscopists. These complaints may be prevented by an ergonomic design of the microscope workstation, leading to a beneficial and significant reduction of electromyographical activity in the most strained muscle groups as shown by surface electromyographic recordings.

Adult↗
PubMed1999

[Streptococcus suis meningitis and neurophysiology of the acoustic system. First case report from Austria].

Meningitis caused by Streptococcus suis was diagnosed in a 63 year old female in Austria. Sixteen months after onset she still suffers from ataxia, disturbance of gait and bilateral hearing impairment. Being a farmer, the patient belongs to a recognized high-risk-group, as most other infected people do. To the best of our knowledge, there has been no report of a human infection by Streptococcus suis in Austria so far. The results of neurophysiological tests excluded a direct lesion to the cochlea during the acute phase of meningitis, and thus, are in contrast to the guinea-pig-model by Kay, who showed suppurative labyrinthitis being the cause of hearing loss. The present knowledge of Streptococcus suis meningitis with respect to neurophysiology, pathogenesis, epidemiology and increasing resistance against antibiotics is discussed.

Agricultural Workers' Diseases↗