Biomedical subjects

C Lechner

Publications and source records attributed to C Lechner.

At least 19 recordsLinked to original sources

PubMed2006

Spin precession and alternating spin polarization in spin-3/2 hole systems.

The spin density matrix for spin-3/2 hole systems can be decomposed into a sequence of multipoles which has important higher-order contributions beyond the ones known for electron systems [R. Winkler, Phys. Rev. B 70, 125301 (2004)]. We show here that the hole spin polarization and the higher-order multipoles can precess due to the spin-orbit coupling in the valence band, yet in the absence of external or effective magnetic fields. Hole spin precession is important in the context of spin relaxation and offers the possibility of new device applications. We discuss this precession in the context of recent experiments and suggest a related experimental setup in which hole spin precession gives rise to an alternating spin polarization.

Journal Article↗

PubMed2006

[Comparison of open versus percutaneous treatment for humeral head fracture].

BACKGROUND: The hypothesis of this study was that percutaneous techniques lower the risk of post-traumatic avascular necrosis. MATERIALS AND METHODS: In this retrospective study 83 patients were followed up clinically and radiologically for signs of avascular necrosis and nonunion after open or percutaneous treatment of proximal humerus fractures. Mean age was 50 years. Fractures were classified in 22 patients (26.5%) as two part, in 21 patients (25.3%) as three part, in 39 patients (47%) as four part, and in 1 patient (1.2%) as fracture dislocation (Neer classification). Fractures were treated in 12 patients (14.5%) by ORIF (open reduction and internal fixation) and in 71 patients (85.5%) by CRPF (closed reduction and percutaneous fixation). Both groups were statistically equally distributed according to fracture type (Mann-Whitney U, p=0.267) and age (One-way-Annova, p=0.740). The postoperative regime did not differ between the two groups. RESULTS: Patients suffered significantly more avascular necrosis after open treatment [five patients (50%) versus eight patients (12.7%) in the percutaneous group, Mann-Whitney, p=0.004]. The risk for avascular necrosis and nonunion increased with age. Mean age of patients with avascular necrosis was 57 years, and the age of patients with nonunion was 67 years. CONCLUSION: Percutaneous treatment of humeral head fractures seems to be a reliable method for lowering the risk of avascular necrosis in young patients.

Adult↗

PubMed2003

Involuntary vocalisations and a complex hyperkinetic movement disorder following left side thalamic haemorrhage.

A variety of involuntary speech phenomena as for example palilalia have been described as consequences of neurological disorders. Palilalia is the involuntary repetition of syllabels, words and phrases in ongoing speech. We describe a 73 year old woman who suffered from a hypertensive thalamic haemorrhage. MRI revealed that the lesion was predominantly located within the pulvinar, extending to the lateroposterior thalamic nuclei and to the pretectal area with possible involvement of the medial geniculate body. Few months after the event she developed involuntary vocalisations with whole words and meaningless syllables being rapidly reiterated. In contrast to typical palilalia these vocalisations were not meaningfully related to the ongoing speech of the patient. In addition, the patient developed a complex hyperkinetic movement disorder with right-sided painful hemidystonia and bilateral clonic jerks and a right-sided postural tremor.

Aged↗

PubMed2002

[The current value of percutaneous transhepatic biliary drainage].

Percutaneous transhepatic biliary drainage (PTBD) is a well established method in the treatment of obstructive jaundice. Major indications are malignant diseases. PTBD may be necessary preoperatively in cases with severe jaundice or cholangitis or as part of palliative treatment concepts. In the past, it has been proposed that a period of preoperative PTBD may improve the morbidity rates of surgery. Various studies could not prove this theory. The significance of preoperative PTBD has changed, as observed during a 15 years period in our own institution, the indications for preoperative PTBD have decreased by half. At present, the majority of treatments with PTBD are palliative (almost 70 % of all procedures). The diagnostic opportunities of the transhepatic approach (intraductal sonography, cholangioscopy, biopsy) are exploited only in few selected cases. Since the radiological approach ist considered to be invasive and related to serious complications most patients are being referred to endoscopic drainage first. Radiologists are consulted in complicated cases of jaundice and when endoscopic approaches have failed. The retrospective evaluation of more than 1000 procedures over a period of 16 years demonstrates good results with a low rate of serious complications. During the two observed periods of nine and seven years, respectively, there occurred complications like sepsis in 1.9 %/0.5 %, peritonitis in 0.5 %/0.7 %, severe bleeding in 0.5 %/1.5 %, procedure-related death in 0.8 %/0.7 %. The overall rate of serious complications was 5 %/3.4 %. These results are comparable to those of the endoscopic approach with a complication rate of 3.6-14 % and a mortality rate of 0.5 %.

Cholangiography↗

PubMed2001

Direct ring fission of salicylate by a salicylate 1,2-dioxygenase activity from Pseudaminobacter salicylatoxidans.

In cell extracts of Pseudaminobacter salicylatoxidans strain BN12, an enzymatic activity was detected which converted salicylate in an oxygen-dependent but NAD(P)H-independent reaction to a product with an absorbance maximum at 283 nm. This metabolite was isolated, purified, and identified by mass spectrometry and (1)H and (13)C nuclear magnetic resonance spectroscopy as 2-oxohepta-3,5-dienedioic acid. This metabolite could be formed only by direct ring fission of salicylate by a 1,2-dioxygenase reaction. Cell extracts from P. salicylatoxidans also oxidized 5-aminosalicylate, 3-, 4-, and 5-chlorosalicylate, 3-, 4-, and 5-methylsalicylate, 3- and 5-hydroxysalicylate (gentisate), and 1-hydroxy-2-naphthoate. The dioxygenase was purified and shown to consist of four identical subunits with a molecular weight of about 45,000. The purified enzyme showed higher catalytic constants with gentisate or 1-hydroxy-2-naphthoate than with salicylate. It was therefore concluded that P. salicylatoxidans synthesized a gentisate 1,2-dioxygenase with an extraordinary substrate range, which also allowed the oxidation of salicylate.

Chromatography, High Pressure Liquid↗

PubMed2000

Non-convulsive status epilepticus with marked neuropsychiatric manifestations and MRI changes after treatment of hypercalcaemia.

We describe a 77-year-old woman who developed a confusional state, cognitive impairment, behavioural abnormalities and dysphasia after treatment of hypercalcaemia. Repeated EEG recording revealed rhythmic sharp-wave activity over the right parietal-occipital lobe. Magnetic resonance imaging (MRI) showed marked hyperintense signal changes bilaterally. The diagnosis of a non-convulsive status epilepticus (NCSE) was made. With antiepileptic treatment the patient improved and MRI as well as EEG changes were almost all reversible. NCSE is an important differential diagnosis of patients with neuropsychiatric symptoms and can develop after rapid lowering of serum calcium levels in hypercalcaemia.

Aged↗

PubMed2000

A comparison of the effects of clozapine and olanzapine on the EEG in patients with schizophrenia.

Clozapine is known to induce epileptic seizures and changes in EEG-patterns, including slowing and the appearance of epileptiform activity. Olanzapine, a new antipsychotic drug, shares many pharmacological and clinical properties with clozapine. However, in patients treated with olanzapine, no case of seizure induction has been reported so far, and the EEG has not been studied systematically. We examined the EEGs of patients with schizophrenia treated with either olanzapine (N = 9) or clozapine (N = 9) prior to medication and 3 to 7 weeks afterwards. Clozapine induced significant EEG slowing present in 78% of the patients, and definite epileptiform activity appeared in 33%. Olanzapine also induced significant EEG slowing, but less frequently (in 44% of the patients) and less pronounced than clozapine. Olanzapine had no significant effect an epileptiform activity, but in one patient, an isolated sharp/slow-wave complex was observed. These preliminary data suggest that olanzapine induces EEG slowing to a lower extent than clozapine. Olanzapine's possible effect an the seizure threshold deserves further attention.

Adult↗

PubMed1999

Magnetic resonance imaging findings in corticobasal degeneration.

Two women (patient 1, 77 years old, and patient 2, 63 years old) with strong clinical evidence for corticobasal degeneration (CBD) are presented. Patient 2 was in an early stage of the disease with only a mild disability of her left hand. In addition to the clinical characteristics, both patients presented the typical cortical reflex myoclonus. Magnetic resonance imaging studies for both patients revealed nearly identical hyperintense lesions somatotopic from the left-hand primary motor cortex (M1), extending to the midline and possibly supplementary motor area (SMA) in patient 2. To our knowledge, this has not been previously described in patients with CBD. These lesions may play a role in the etiology and the development of CBD with involvement of the M1 and may correspond to the underlying pathology of demyelination or gliosis.

Aged↗

PubMed1999

[Hallervorden-Spatz syndrome. Differential diagnosis of early onset dementia].

We report the history of a 38 year old patient who began to develop mental deterioration at the age of 26. After a time of 7 years neurological signs like writing dystonia occurred. Hallervorden-Spatz-Disease (HSD) was diagnosed at the age of 36 in vivo with the clinical presentation of severe dystonia, rigidity, dementia, and typical signal loss in the globus-pallidus the reticular part of the substantia nigra, and the nucleus ruber in the T-2 weighted MRI. The "eye-of-the-tiger"-sign, a bilateral hyperintensity in the rostral globus pallidus, was not observed in follow-up examinations. HSD is a rare autosomal-recessive or sporadic disease of unknown etiology. In one third of the patients a dementing process is the first clinical sign of the disorder, and is a rare differential diagnosis of early onset dementia.

Adult↗

PubMed1999

Orienting response and frontal midline theta activity: a somatosensory spectral perturbation study.

OBJECTIVE: Brain electric activity in the theta frequency band has been associated with the encoding of new, and the retrieving of previously stored, information. We studied the time course of stimulus-to-stimulus changes of theta activity under repetitive somatosensory stimulation. MATERIALS AND METHODS: Twelve healthy subjects participated in the study. Repetitive electric stimuli, grouped into 48 stimulus trains, were applied to the left index finger. The stimulus trains contained 27 stimuli (0.9 Hz, 2.5 times sensory threshold). Each stimulus train of 30 s was followed by a stimulus-free break of 30 s. This stimulation paradigm allowed the separate estimation of effects for each position of the stimulus in the train and an analysis of stimulus-to-stimulus changes. Multichannel EEG recordings allowed a topographic analysis of the event-related spectral perturbation effects in the theta frequency band. The brain electric novelty response triggered by the stimulus train onset was analyzed by 3 methods: (1) event-related potentials; (2) event-related power spectra for the investigation of spectral perturbation effects on theta activity; and (3) an approach to break down the stimulus-induced theta activity into phase-locked activity and effects on the spontaneous, ongoing theta activity using digital filtering. RESULTS: The main findings are a frontal midline activation in the theta band with the beginning of the stimulus train, which habituates during the subsequent stimulation cycles, as well as evidence that distinct effects of the first stimulus on the ongoing, non-phase-locked, theta activity exist.

Adult↗

PubMed1998

[Exacerbation of tics by prednisolone].

Tics-disorders are hyperkinetic movement disorders which manifest in childhood or early adolescence and ameliorate in later adulthood. We report on two patients with a basically subclinical tic-disorder (age of 53 and 68 years). During the therapy of polymyalgia rheumatica and endocrine orbitopathy in Graves disease with prednisolone the tics exacerbated and were therefore diagnosed and treated for the first time. Possible causes for the exacerbation of the tics during the therapy with glucocorticosteroids are discussed in the context of the dopamine hypothesis of tics.

Aged↗

PubMed1998

[Prolonged non-convulsive status epilepticus as an early clinical manifestation of epilepsy in connection with HIV infection--case report with EEG and MRI follow-up].

The non-convulsive status epilepticus (NCSE) is a complication of petit mal epilepsy or epilepsy with temporal lobe seizures. Very rarely it is the primary manifestation of a symptomatic epilepsy. This report is on a 30-year old female inpatient with NCSE as the primary manifestation of symptomatic epilepsy, occurring four years after HIV infection (stage B3 according to the CDC classification) through heterosexual contact. After an initial tonic-clonic seizure, the patient suffered from NCSE for four weeks with diminished consciousness and major cognitive deficits. During this whole time period the EEG showed bilateral synchrone 1-2 Hz spike-wave complexes. After several failed treatment attempts, the NCSE was successfully and permanently treated with a combination of valproic acid and ethosuximide. The cerebrospinal fluid, cranial CT and cranial MRI were completely uneventful with regard to a CNS infection by the HI-virus or other infectious agents. 20 days after the initial symptoms, MRI showed bilateral cortical-subcortical and bilateral hippocampal lesions which stood out as focal edema zones, gradually disappeared completely and occurred in combination with the development of a discrete brain and right sided hippocampal atrophy. The EEG continued to show signs of right-temporal epileptic discharges with tendencies to generalise after 3 months but normalised after 6 months. Epileptic seizures are rarely an initial clinical sign of an infection with the HI-Virus even if no signs of encephalitis is detectable in the cerebrospinal fluid or in the cerebral MRI.

Adult↗

PubMed1998

[Spontaneous perimesencephalic subarachnoid hemorrhage (PMH). A disease category with good prognosis?].

Perimesencephalic subarachnoidal haemorrhage (PMH) is characterized by a typical blood distribution pattern in the basal cysterns in the CAT, missing evidence of an aneurysm in the panangiogram, a mild clinical course and a very positive prognosis. Between 1990 and 1995, 108 inpatients with non-traumatic subarachnoidal haemorrhage were treated in our clinic. Within this group 14 patients (13%) were identified retrospectively with a perimesencephalic haemorrhage distribution pattern in the CAT and a negative panangiogram. These patients experienced a mild clinical course with excellent outcome without rebleeding during the observation period of 2 to 50 months. All patients were fully able to work, and only two patients complained of frequent headaches. The mild clinical course, the negative panangiogram as well as the extremely positive outcome confirm the hypothesis of of a benign subgroup of non-traumatic subarachnoidal haemorrhages.

Adult↗

PubMed1998

Twenty-four-hour blood pressure profile and blood pressure responses to head-up tilt tests in Parkinson's disease and multiple system atrophy.

OBJECTIVE: To investigate the 24 h blood pressure profile in patients with Parkinson's disease with intact autonomic function or with autonomic failure and patients with multiple system atrophy (MSA), and to assess whether these patients exhibit posture-related variations in blood pressure. PATIENTS AND METHODS: We studied 24 patients with Parkinson's disease (11 with autonomic failure) and 13 patients with MSA (all with autonomic failure). Autonomic failure was determined by autonomic tests. An oscillometric recorder was used for ambulatory blood pressure monitoring. Tilt-table tests were performed with a head-up tilt position of 60 degrees. RESULTS: An alteration in the normal 24 h blood pressure profile was observed in 82% of Parkinson's disease patients with autonomic failure and in 85% of those with multiple system atrophy, but not in the patients with intact autonomic function. Head-up tilt tests revealed a significantly higher supine blood pressure in Parkinson's disease patients with autonomic failure and in those with MSA than in Parkinson's disease patients with intact autonomic function. Tilting resulted in a marked fall in blood pressure in patients with MSA; in Parkinson's disease patients with autonomic failure, the fall was comparatively slighter. CONCLUSIONS: We conclude that autonomic failure contributes to the alterations in the day-night blood pressure profile that may possibly be ascribed to postural dysregulation of blood pressure. We hypothesize that nocturnal hypertension is a risk factor in the development of additional cerebrovascular disease in patients with Parkinson's disease or MSA who are affected by autonomic failure.

Aged↗

PubMed1996

ERK6, a mitogen-activated protein kinase involved in C2C12 myoblast differentiation.

ERK6, a mitogen-activated protein (MAP) kinase-related serine/threonine kinase, is highly expressed in human skeletal muscle and appears to function as a signal transducer during differentiation of myoblasts to myotubes. In transfected 293 cells, activation of the 45-kDa enzyme results in tyrosine-phosphorylated 46- and 56-kDa forms, which phosphorylate myelin basic protein. Overexpression of wild-type ERK6 or the inactive mutant Y185F has no effect on fibroblast and myoblast proliferation, but it enhances or inhibits C2C12 cell differentiation to myotubes, respectively. Our findings suggest ERK6 to be a tissue-specific, differentiation signal-transducing factor that is connected to phosphotyrosine-mediated signaling pathways distinct from those activating other members of the MAP kinase family such as LRK1 and ERK2.

3T3 Cells↗

PubMed1996

Intraoperative esophageal manometry and fundoplications: prospective study.

The purpose of this study was to validate the use of intraoperative manometry for assessing fundoplication and to search for predictive manometric criteria. This prospective study concerned 48 patients operated for gastroesophageal reflux. The manometry was carried out pre- and intraoperatively for all patients and postoperatively as well for 30 patients. The operative procedures were total fundoplication (n = 25) and posterior (partial) fundoplication (n = 5). The lower esophageal sphincter (LES) pressures and lengths were similar in the preoperative and intraoperative measurements before any esophageal mobilization, whereas the intraoperative LES pressure was significantly higher after fundoplication. The mean postoperative LES pressure decreased by 50 +/- 19% compared with the intraoperative pressure after fundoplication. The final intraoperative pressures of two dysphagic patients were not the highest of the study. More importantly, their final intraoperative pressures were 7.5 and 8.2 times the initial pressure, respectively, which was significantly greater than the intraoperative pressure increase of the nondysphagic patients (4.6 +/- 2.0 times). The final intraoperative pressure of the only patient with recurrence (18.2 mmHg) was the lowest of the study. In conclusion, intraoperative manometry is an effective method for evaluating the LES, and it could have predictive value for the surgical management of gastroesophageal reflux disease.

Esophagus↗

PubMed1995

[Heller's myotomy by laparoscopic approach for megaesophagus].

The development of laparoscopic surgery has allowed the indications of this technique to be extended to the management of achalasia. Four patients were operated for achalasia confirmed by esophageal manometry. The procedure consisted of laparoscopic Heller's myotomy. The purpose of this paper is to detail the technical principles of this procedure and to evaluate its feasibility. There were no intra-operative incident and no conversion to open procedure. The postoperative course was uneventful in every case. The mean postoperative stay was 5 days. The postoperative manometry (n = 3), performed an average of 14.5 months after the operation, showed a normal lower esophageal sphincter pressure in all cases. Only one patient complained of intermittent dysphagia without food restriction and with normal postoperative manometry. The feasibility of laparoscopic Heller's myotomy is therefore obvious. Consequently, this procedure could replace repeated balloon dilatations in the management of achalasia.

Adult↗

PubMed1994

Prospective analysis of 40 initial laparoscopic colorectal resections: a plea for a randomized trial.

The experience reported herein is on our initial 40 cases of laparoscopic-assisted (LA) colorectal resection that were prospectively evaluated. The operations were performed for colonic tumors of the right segment (n = 4), sigmoid (n = 11), or rectum (n = 7), diverticular disease (n = 17), and chronic constipation (n = 1). Among 22 tumors, 11 were malignant. The operative procedures were 4 right hemicolectomies, 28 segmental left colectomies, 5 anterior resections, 2 abdominoperineal resections, and 1 total colectomy. Thirty-one patients (77.5%) had a successfully completed LA resection. The reasons for conversion in the majority of the cases (66.6%) were difficulties in dissection. In the entirely LA procedures, the mean flatus postoperative day was 3, the mean postoperative hospitalization was 10.7 days, and there were 8 complications (25%) in 7 patients. Two patients were reoperated 2 and 3 months later for adhesion and ischemic stenosis of the colon above the anastomosis. There was 1 death in the LA group (3.2%). The length of operative specimen was 19.6 cm, and the mean number of resected lymph node was six. In contrast to laparoscopic biliary surgery, the benefits of LA colorectal surgery are not obvious. A randomized trial comparing LA and open colorectal resection must be carried out.

Colectomy↗