Search PubMed⌕ Search

Biomedical subjects

J Schröder

Publications and source records attributed to J Schröder.

At least 19 recordsLinked to original sources
PubMed2007

PMMA versus titanium cage after anterior cervical discectomy - a prospective randomized trial.

INTRODUCTION: Nonautologous interbody fusion materials are utilised in increasing numbers after anterior cervical disc surgery to overcome the problem of donor site morbidity of autologous bone grafts. This study investigates the performance of two nonautologous materials, the bone cement Polymethylmethacrylate (PMMA) and titanium cages. This prospective randomised trial, with assessment of the results by an independent observer, evaluates whether a Polymethylmethacrylate (PMMA) spacer or a titanium cage provides a better fusion rate around the implant and a better clinical outcome. PATIENTS/MATERIAL AND METHODS: Between 2000 and 2002, 115 patients with monoradicular cervical nerve root compression syndrome caused by soft cervical disc herniation were eligible for this study. Myelopathy, excessive osteophyte formation, and adjacent level degeneration were exclusion criteria. A block-restricted randomisation was applied. The 2-year clinical outcome served as the primary endpoint of the study. Clinical outcome was assessed according to the Odom scale by an independent observer at the follow-up examination. Preoperative, postoperative, and follow-up radiographs were taken. RESULTS: The study was completed by 107 patients (53 with PMMA and 54 with titanium cage). No significant difference between the two groups could be established with respect to the clinical outcome. In each group, 26 patients scored excellent. Good results were found in 19 PMMA patients and 16 titanium cage patients; satisfactory results were found in 8 PMMA patients and 9 titanium cage patients; bad results were found in 3 titanium cage patients. In 47 titanium cage cases (87%), fusion occurred radiologically as bony bridging around the implant. The fusion rate was significantly lower (p=0.011) in the PMMA group, with 35 cases (66%) united at follow-up. CONCLUSION: The radiological result of the titanium cage is superior to that of PMMA with respect to the fusion rate. Although the titanium cage achieves a better fusion rate, there is no difference between titanium cages and PMMA with respect to the clinical outcome.

Adolescent↗
PubMed2006

Mechanical response of cervical vertebral endplates to axial loading.

OBJECTIVE: After anterior cervical discectomy the implantation of a spacer is common practice. The majority of these spacers are trapezoid titanium cages. During the development of a height-adjustable cervical implant we needed to establish the testing limits for this device. A known phenomenon is subsidence of the cage into the vertebral endplates, which leads to a decrease in height and/or angulation of the cervical spinal segment. In contrast to the thoracic and lumbar spines, there are only limited data concerning the load-bearing ability of cervical endplates. The aim of our investigation was to obtain these data. METHODS: Bone density of 16 cervical vertebrae was estimated by quantitative computed tomography. After embedding of the vertebrae into PMMA, each endplate was slowly compressed until failure using a metal indenter resembling the form of a newly developed cervical implant. A fixed protocol with increasing loading cycles was followed. Endpoint was breakage of the endplate as established by failure to resist the increasing loading forces produced by the testing machine. RESULTS: The mean bone density of the 16 cervical vertebrae was 204 with a standard deviation of 52 mg Ca-HA/mL (range 130-281). The endplates failed with a mean loading of 1084 N +/- 314 (range 340-1550 N). The maximum load correlates with the bone density (R2 = 0.7347). With the 97.79 mm2 load bearing surface of the cage we calculate a mean cervical endplate break strength of 10.47 MPa and a 95 % confidence interval of 12.66-9.51 MPa. An initial settling produced by resting of the anchoring teeth in the cervical endplates was observed in 8 vertebrae at a load of 113 N (range 50-250 N). CONCLUSIONS: In contrast to the thoracic and lumbar spines, cervical endplates show a lower resistance against axial forces. The data are important to understand postoperative cage subsidence and to establish testing limits for the development of new implant designs.

Biomechanical Phenomena↗
PubMed2006

Simulation of discontinuous damage incorporating residual stresses in circumferentially overstretched atherosclerotic arteries.

When a balloon-angioplasty is performed, the arterial wall is overstretched and thereby damaged, which leads to a stiffness reduction in the arterial layers. An anisotropic damage model able to reflect the main damage mechanisms in overstretched arterial walls is used in combination with a polyconvex hyperelastic stored energy function. Furthermore, a method for the incorporation of residual stresses present in the wall of unloaded configurations is applied. The energy describes the anisotropic hyperelastic behavior of arteries under physiological conditions. Due to the assumption that the rupture of cross-bridges between collageneous micro-fibrils is responsible for the damage inside arterial walls, the damage function is applied to that part of the energy only which is associated to the fiber elasticity. For the incorporation of the residual stresses into the simulation, we apply a method which consists of two simulation steps. Finally, a numerical simulation of the overstretching of a simplified atherosclerotic artery is performed taking into account residual stresses.

Computer Simulation↗
PubMed2006

A type III polyketide synthase from Wachendorfia thyrsiflora and its role in diarylheptanoid and phenylphenalenone biosynthesis.

Chalcone synthase (CHS) related type III plant polyketide synthases (PKSs) are likely to be involved in the biosynthesis of diarylheptanoids (e.g. curcumin and polycyclic phenylphenalenones), but no such activity has been reported. Root cultures from Wachendorfia thyrsiflora (Haemodoraceae) are a suitable source to search for such enzymes because they synthesize large amounts of phenylphenalenones, but no other products that are known to require CHSs or related enzymes (e.g. flavonoids or stilbenes). A homology-based RT-PCR strategy led to the identification of cDNAs for a type III PKS sharing only approximately 60% identity with typical CHSs. It was named WtPKS1 (W. thyrsiflora polyketide synthase 1). The purified recombinant protein accepted a large variety of aromatic and aliphatic starter CoA esters, including phenylpropionyl- and side-chain unsaturated phenylpropanoid-CoAs. The simplest model for the initial reaction in diarylheptanoid biosynthesis predicts a phenylpropanoid-CoA as starter and a single condensation reaction to a diketide. Benzalacetones, the expected release products, were observed only with unsaturated phenylpropanoid-CoAs, and the best results were obtained with 4-coumaroyl-CoA (80% of the products). With all other substrates, WtPKS1 performed two condensation reactions and released pyrones. We propose that WtPKS1 catalyses the first step in diarylheptanoid biosynthesis and that the observed pyrones are derailment products in the absence of downstream processing proteins.

Amino Acid Sequence↗
PubMed2006

[Persons with dementia in individual everyday situations. First results of an intervention study].

First outcomes of a current intervention study focussing on emotions of nursing home residents with mild, moderate and severe dementia are discussed in the present contribution. The aim of the study was to prove the effect from an individual approach in the care of people with dementia. By promoting individual everyday situations for each resident, positive emotions should be stimulated and individual well-being should be improved. Findings show the possibility to gain such individual everyday-situations for people with mild, moderate and severe dementia, which stimulate positive reactions and may be integrated into the care process. Of particular importance are those positive situations which focus on the communication between nurses and residents or in which the residents receive personal attention from nurses.

Activities of Daily Living↗
PubMed2006

[Psychometric properties of a German version of the Apathy Evaluation Scale].

Apathy is a common feature of a variety of different psychiatric, neurological, and medical disorders. It can be defined as lack of motivation affecting cognitive, emotional, and overt behavioural aspects. Despite being associated with other clinical disorders, apathy can also occur as an independent syndrome (e. g., after brain injuries), now depicting a primary loss of motivation. However, apathy is predominantly assessed within the scope of superordinate psychiatric disorders. As a syndrome-independent scale, the Apathy Evaluation Scale (AES) claims to assess levels of apathy in different disorders. The aim of the present study is to provide German speaking researchers with an authorized German translation of the AES (AES (D)). The scale was evaluated in a sample of 217 subjects, consisting of patients suffering from dementia (n=120), remission-phase schizophrenia (n=20), Parkinson's disease (n=12), stroke (n=28), as well as elderly healthy controls (n=37). Preliminary results concerning the factorial structure, item characteristics, reliability, and construct validity demonstrate favourable statistical properties and suggest that the AESD is comparable to its original. The scale seems well-suited to detect apathy in different clinical groups. Differences between informant sources (clinician interview, self-, and informant ratings) seem to be related to the severity of symptoms or expert practice.

Aged↗
PubMed2006

Spinal navigation: an accepted standard of care?

OBJECTIVE: In contrast to cranial neuro-navigation, which has been accepted as a routine intraoperative tool, there is still much debate about spinal navigation as an aid for the insertion of pedicle screws. Opinions range from "not useful at all" to "malpractice if not using it". The aim of our investigation was to obtain data about the availability of spinal navigation and compile a common opinion among German neurosurgeons about its usefulness. The current literature is reviewed. METHODS: We present the results of a survey of the Commission for Technical Standards of the German Neurosurgical Society about the use of intraoperative computerised spinal navigation. RESULTS: Of the 128 neurosurgical departments surveyed, 107 (84 %) responded. 57 (53 %) of the responders are equipped with a spinal navigation device, 12 (11 %) use a spinal navigation equipment together with other departments, and 38 (36 %) do not have spinal navigation. Of the departments not equipped with spinal navigation, 58 % would like to have it but 42 % would not. 52 (49 %) responders held the opinion that spinal navigation enhances safety when introducing pedicle screws; while 40 (37 %) answered in the negative, and 15 (14 %) were not sure. Of the responders, 101 (94 %) disagreed with the statement that spinal navigation should be mandatory for pedicle screw placement, 3 (3 %) agreed, and 3 (3 %) were not sure. Of the responders, 105 (98 %) rejected the statement that insertion of pedicle screws without navigation is medical malpractice, 1 (1 %) upheld the statement, and 1 (1 %) was not sure. CONCLUSION: It is still not generally considered common practice to use spinal navigation as an aid for the implantation of pedicle screws. Most pedicle screws are still inserted conventionally. Although nearly 50 % of German neurosurgeons believe that spinal navigation could enhance safety when placing pedicle screws, they clearly reject efforts to make spinal navigation mandatory. With only one exception, the German neurosurgical community unanimously rejects the idea that placing pedicle screws without spinal navigation is medical malpractice.

Clinical Trials as Topic↗
PubMed2005

Two dimensional counterpropagating spatial solitons in photorefractive crystals.

We demonstrate experimentally the existence of two transverse-dimensional counterpropagating (CP) incoherent spatial solitons in a 5 x 5 x 23 mm SBN:60Ce photorefractive crystal and investigate their dynamical behavior. We carry out numerical simulations that confirm our experimental findings. Substantially different behavior from the copropagating incoherent solitons is found. A symmetry breaking transition from stable overlapping CP solitons to unstable transversely displaced CP solitons is observed. We perform linear stability analysis that predicts the threshold for the split-up transition, in qualitative agreement with numerical simulations and experimental results.

Journal Article↗
PubMed2005

Psychopathology in first-episode schizophrenia and antibodies to Toxoplasma gondii.

OBJECTIVE: Environmental factors such as infectious agents may contribute to the psychopathology and aetiology of schizophrenia. Toxoplasma gondii (TG) is a candidate infectious agent as it is known to replicate within the human central nervous system and to alter behaviour in experimental animals. METHOD: The relationship between antibodies to TG and psychopathological symptoms was examined in 34 first-episode patients with schizophrenia. RESULTS: Results of regression analyses revealed that symptoms on admission, predictors of outcome, age and family history of psychiatric disease influenced the levels of antibodies to TG. CONCLUSIONS: These results indicate that TG infections may play a role in the clinical manifestation of psychopathology in a subgroup of patients with schizophrenia.

Adolescent↗
PubMed2005

[Unusual course of alpha-mannosidosis with symptoms of paranoid-hallucinatory psychosis].

We report the case of a 27-year-old female with recurrent paranoid-hallucinatory episodes who was initially diagnosed as suffering from schizophrenic psychosis. After 10 years of treatment under this diagnosis, alpha-mannosidosis was identified to be the underlying cause of her psychiatric symptoms. alpha-Mannosidosis is a rare autosomal recessive lysosomal storage disorder associated with decreased activity of the enzyme mannosidase. In the present case, diagnosis was made late in the illness after failure of a response to antipsychotic treatment and with the patient additionally showing progressive cognitive decline. Only after extensive investigation was the diagnosis made by showing decreased alpha-mannosidase enzyme activity in serum and blood leukocytes. This case demonstrates that an unusual clinical course or striking symptom patterns, especially in association with somatic comorbidity, in psychotic patients should lead to diagnostic consideration of inherited metabolic disease.

Adult↗
PubMed2005

[Working memory in healthy subjects and schizophrenics: studies using BOLD fMRT].

Functional magnetic resonance imaging uses the blood oxygen level-dependent effect (BOLD MRI) for noninvasive display of cerebral correlatives of cognitive function. The importance for the understanding of physiological and pathological processes is demonstrated by investigations of working memory in schizophrenics and healthy controls. Working memory is involved in processing rather than storage of information and therefore is linked to complex processes such as learning and problem solving. In schizophrenic psychosis, these functions are clearly restricted. Training effects in the working memory task follow an inverse U-shape function, suggesting that cerebral activation reaches a peak before economics of the brain find a more efficient method and activation decreases.

Brain↗
PubMed2005

[The Heidelberg instrument for the assessment of quality of life in dementia (H. I. L. DE.)--dimensions of quality of life and methods of organization].

The contribution is intended to describe the theoretical background and measurement approach of H.I.L.DE., a research project aimed to develop and validate a comprehensive assessment of quality of life in nursing home residents suffering from dementia. Proceeding from the assumption that emotions are felt even in advanced stages of dementia and can be interpreted on the basis of peoples' mimic expressions, three samples of participants were recruited from 11 nursing homes of varying maintenance: 121 nursing home residents suffering from dementia, 97 professional caregivers and 101 relatives participated in the first wave of this study. Operational definition of quality of life in H.I.L.DE. proceeds from the differentiation of eight dimensions of quality of life: physical environment, social environment, quality of care, behavioral competence, medical and functional status, cognitive status, psychopathology and behavior disturbances, and subjective experiences of physical and social environment and emotional well-being. Measures of the eight dimensions involve data from medical examination, interviews with residents, professional caregivers and relatives, ecopsychological assessment of physical environment and analysis of care documents. First results from the H.I.L.DE.-study are used as an illustration of the potentials of such a comprehensive approach to the measurement of quality of life.

Aged↗
PubMed2005

[Mild cognitive impairment and Alzheimer's disease: an investigation of the CERAD-NP test battery].

To investigate the psychometric properties of the German version of the CERAD-NP, neuropsychological deficits were compared between 49 patients with mild cognitive impairment (MCI), 80 patients with Alzheimer's disease (AD), 36 with major depression (MD), and 26 elderly controls. All participants were outpatients of the memory clinic of the Section of Geriatric Psychiatry, Heidelberg University. Diagnoses were established based on clinical examination, laboratory testing, neuroimaging, and routine neuropsychological testing according to the criteria of aging-associated cognitive decline (AACD) for MCI, NINCDS-ADRDA for AD, and DSM-IV for MD, respectively. All CERAD-NP subtests discriminated between controls and AD patients with the latter showing significantly (p< or = 0.05) lower test scores. The subtests verbal fluency and constructive apraxia differed significantly between mildly and moderately AD, while the subtests assessing declarative (epsisodic) memory performance showed only minor, non-significant differences between the respective groups. The LKB patients took an intermediate position between controls and AD patients with significantly lower scores in verbal fluency and declarative memory performance than the controls. When compared with the AD patients, MCI patients were significantly impaired in all subtests except constructive apraxia. Relative to the controls, the patients with MD showed a decreased episodic memory performance but no evidence suggesting an impairment in other neuropsychological domains. Our results indicate that the CERAD-NP is a psychometric instrument which allows a sensitive discrimination between mild and moderate AD, MCI, MD and healthy controls. However, sensitivity of discrimination between different stages of dementia varies with respect to the different subtest. While the subtest for episodic memory showed floor effects already for mild dementia, subtests for verbal fluency and constructive apraxia were able to discriminate even between more advanced stages of the disease.

Aged↗
PubMed2005

Analysis of mRNA in hemophilia A patients with undetectable mutations reveals normal splicing in the factor VIII gene.

BACKGROUND: haemophilia A (HA) is characterized by partial or total deficiency of factor VIII (FVIII) protein activity. It is caused by a broad spectrum of mutations in the FVIII gene. Despite tremendous improvements in mutation screening methods, in about 2% of HA patients no DNA change could be found, even after sequencing the whole coding part of the FVIII gene including the flanking splice sites, as well as the promotor and the 3' UTR regions. OBJECTIVES, PATIENTS AND METHODS: In the present study we performed a detailed RNA analysis of three groups of patients. The first included control patients with known splicing defects, the second included two patients with already identified nucleotide changes close to splicing sites, that could potentially alter the normal splicing process, and a third group of 11 unrelated patients whose genomic DNA have already been screened for mutations by DHPLC and direct sequencing with no mutation being identified. RESULTS: Both candidate splice site mutations were shown to result in either skipping or alternative splicing of at least one exon, therefore these DNA changes must be considered as causal for the patients' HA phenotype. In contrast, no abnormalities on the RNA level were observed in any of 11 unrelated patients without mutations in the FVIII gene. CONCLUSIONS: These findings exclude mutations that could be located deep in the introns and affecting either normal splicing or lead to mechanisms causing some unknown rearrangements of the FVIII gene. In fact, our results point to the presence of still unknown factor(s) causing HA, which might be either allelic or in the close proximity of the FVIII gene or non-allelic associated with other genetic loci that are involved in the processing of the FVIII protein.

DNA Mutational Analysis↗
PubMed2005

Spontaneous spinal epidural haematoma: a therapeutical challenge? Report of an unusual case.

We report the conservative treatment of a spontaneous spinal epidural haematoma attending with acute extensive neurological deficits, which resolved spontaneously. Spontaneous remission of spontaneous spinal epidural haematoma with severe neurological deficit is rare in the literature. An 80 year old man was admitted to our hospital presenting sciatica followed by rapid development of paraparesis and cauda equina syndrome, which represents a neurosurgical emergency. Magnetic resonance imaging revealed a multilevel epidural haematoma from L1 to L5. During the initial diagnostic procedure the symptoms started to decline unexpectedly, so the surgical intervention could be withdrawn. Twenty four hours after admission the patient was almost free of symptoms, mobile, and continent. Awareness and high index of suspicion, and a willingness to seek the prompt help of the imaging department, are crucial to successful management before the opportunity to treat is lost.

Aged↗
PubMed2004

[Hypokalemic paralysis with thyrotoxicosis].

Hypokalemic periodic paralysis as a complication of thyrotoxicosis (thyrotoxic periodic paralysis) most often occurs in east Asian men. It is characterised by recurrent episodes of flaccid paralysis, hypokalemia, and underlying hyperthyroidism. It needs to be distinguished from sporadic and familial forms of periodic hypokalemic paralysis. No disturbances in the acid-base state and no extracorporal potassium loss are present. We report on the typical case of a young Chinese man presenting with hypokalemic periodic paralysis associated with yet unknown Graves' disease. Intravenous substitution of potassium and oral propranolol were administered. Complete remission was achieved after 10 hours. After medical therapy had normalised thyroid hormone levels, no further hypokalemic paralytic attacks occurred.

1-Propanol↗