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Biomedical subjects

I Grunwald

Publications and source records attributed to I Grunwald.

15 recordsLinked to original sources
PubMed2003

[White matter alterations in neurodegenerative and vascular dementia].

Due to a significant overlap of the two syndromes, differentiation of degenerative dementia of the Alzheimer-type from vascular dementia may be difficult even when imaging studies are available. White matter changes occur in many patients suffering from Alzheimer's disease. Little is known about the impact of white matter changes on the course and clinical presentation of Alzheimer's disease. High sensitivity of MRI in the detection of white matter alterations may account for over-diagnosing vascular dementia. The clinical significance of white matter alterations in dementia is still a matter of debate. The article reviews current concepts about the role of white matter alterations in dementia.

Age Factors↗
PubMed2003

[Craniocerebral trauma in childhood].

This article describes typical head injuries in infants and children. In comparison with adults there are distinct differences in the etiology of trauma and in the kind of reaction of the skull and brain. In infants and children there are three different types of trauma: birth trauma, accidental and non-accidental injury. The typical injuries in these three groups are described.

Cerebral Hemorrhage, Traumatic↗
PubMed2003

[Stroke in childhood].

About 3% of cerebral infarcts occur in children and young individuals, and pediatric stroke is even less common. Cerebral infarcts in children have different etiologies compared to adults. The common causes are described, as well as sinus venous occlusions. Cerebral veno occlusive disease is an elusive, often underdiagnosed cause of acute neurologic deterioration.

Adolescent↗
PubMed2003

[Supratentorial tumors in childhood].

In Germany about 400 children are diagnosed of having a brain tumour each year. About half of them are located in the supratentorial region. Despite the fact, that brain tumours are the most common solid tumour in childhood, they are very heterogeneous, regarding clinical symptoms, pathology, treatment and prognosis. Imaging studies play an important role for diagnosis and follow-up.

Adolescent↗
PubMed2002

[Accuracy of fluoroscopic navigation of pedicle screws. CT-based evaluation of bone screw placement].

While the advantages of C-arm navigation in computer-assisted spine surgery are obvious, the accuracy of pedicle screw placement with virtual fluoroscopy still needs to be verified. The C-arm-based ION system (Medtronic Sofamor Danek) was used to navigate pedicle screw insertion in patients undergoing spinal surgery for various conditions. In a prospective study, a total of 160 screws were inserted in the first 30 consecutive patients since introduction of the system at our institution: 54 at the thoracic spine (highest level: TH4) and 106 at the lumbar spine. Computed tomography (CT) scans were performed postoperatively by two independent radiologists to control the accuracy of screw placement at the level of the pedicles after reconstruction of axial images according to Laine et al. The comparison of the calculated accuracy rate of pedicle screw placement using virtual fluoroscopy with reported results achieved with CT-based navigation shows similar results for virtual fluoroscopy and a remarkable increase of accuracy in comparison to reports on conventional pedicle screw placement.

Bone Screws↗
PubMed2002

Oligodendrogliomas.

PURPOSE: To study the pattern of contrast enhancement in MR and CT of oligodendrogliomas and to compare this with other imaging findings and with histopathological grading criteria. MATERIAL AND METHODS: 20 patients with oligodendrogliomas (12 low-grade WHO II and 8 anaplastic WHO III) were reviewed. 20 complete MR investigations, 20 non-enhanced CT studies and 16 CTs after contrast enhancement were estimated blindly without knowledge of the tumour histological grades. RESULTS: All anaplastic oligodendrogliomas showed tumour contrast enhancement on MR and CT images. Also in 6/12 low-grade oligodendrogliomas the contrast was enhanced on MR imaging. In 5 of these, tumour calcifications were detected by CT. The remaining 6/12 WHO grade II cases showed no significant MR contrast enhancement. Of the oligodendrogliomas grade II, CT showed contrast uptake in 3 cases and no enhancement in 6, while in 3 cases postcontrast CT was not available. A comparison of contrast enhancement with tumour grade resulted in a p-value of 0.042 for MR and of 0.011 for CT. A combined statistical test of tumour grade and calcifications detected by CT compared with MR contrast enhancement showed a significant correlation (p=0.014). CONCLUSION: These data demonstrated that a clear grading of oligodendrogliomas based on the image criterion MR contrast enhancement was not possible. We suppose that, besides tumour neovascularisation, additional factors such as calcifications may disturb the blood-brain barrier.

Brain Neoplasms↗
PubMed2001

[Spinal angiography: vascular anatomy, technique and indications].

The indication for spinal angiography has to be closely set as in case of inadequate handling this procedure bares the risk of paraplegia. In unclear spinal symptoms lasting over a longer period of time, spinal vascular malformation have to be considered. Spinal vascular malformations are often reversible, especially if diagnosed early. Diagnostic methods have to include spinal angiography if other non-invasive methods do not lead to results. The main point is to consider spinal vascular malformations in unclear cases.

Adolescent↗
PubMed2001

Lexical emotional expression across the life span: quantitative and qualitative analyses of word list generation tasks.

The current study examined the effects of age and gender on emotional and nonemotional expression using an experimental word list generation (WLG) task (also referred to in the literature as verbal fluency) from the New York Emotion Battery (Borod, Welkowitz, & Obler, 1992). Subjects were 28 young ( M = 29.6 years), 28 middle-aged (M = 49.8 years), and 28 older (M = 69.9 years) healthy adults. The WLG task consists of 8 emotional (E; 3 positive and 5 negative) and 8 nonemotional (NE) categories. We developed and present here a detailed word error-type analysis that was used to evaluate the lexical output. In this study, both quantitative (amount of output and error-types) and qualitative (accuracy and intensity) analyses were used. While subjects produced more nonemotional than emotional words and more positive than negative words, the amount of error-free output and the number of errors did not change with age. An age group by error-type interaction indicated that older adults, especially men, produced more repetition errors than younger adults. The error-free output was subsequently rated for accuracy and emotional intensity. The rating data revealed that older women's overall lexical output was less accurate than that produced by younger women. Also, negative emotional words were more accurate and intense than positive emotional words. The procedures described here have implications for research assessing word list generation and emotional expression in clinical populations.

Adult↗
PubMed2000

A rare simultaneous presentation of testicular mixed germ cell tumor with a contralateral testis torsion.

We report a rare case of a 27-year-old man presenting with an acute scrotum with simultaneous occurrence of testicular tumor and contralateral torsion. Preoperative imaging demonstrated the testicular missed torsion, yet findings were equivocal with regard to the testicular tumor. On scrotal exploration the left testis was found to be ischemic due to threefold rotation. The right testis was not identifiable, being composed of numerous necrotic lesions. Frozen section suggested malignancy, hence high right orchiectomy was performed. Histologic examination of the right testis showed mixed germ cell tumor, containing all the subtypes. To our knowledge no similar case has been reported.

Adult↗
PubMed1997

[Cementless fixation of the endoprosthesis using trabecular, 3-dimensional interconnected surface structures].

While the principle of enlarging the surface area has been recognized and used in different ways for some time, there is often no schematic, detailed description or fundamental research. Taking a surface structure consisting of trabecular three-dimensional connecting elements, essential parameters are shown, making it clear that the flexible dynamic reaction of the effective "anchoring space" with a suitable specified shape (construction height, alignment, network) can be reproducibly shaped and used. This has led to a hip endoprosthesis with a graduated surface structure. The construction height of the trabecular structure varies, decreasing from proximal to distal.

Biocompatible Materials↗
PubMed1993

Malignant tumour of the psoas: another cause of meralgia paraesthetica.

Contrasting the more benign causes known for meralgia paraesthetica we report a case due to a malignant tumour of the psoas muscle. We discuss the use of sensory nerve conduction study and somatosensory evoked potentials of the lateral femoral cutaneous nerve as well as needle EMG and diagnostic nerve block to detect the site of the lesion along its course. This appears of major importance, as causes located above the inguinal ligament can bear a more serious prognosis than the ones below.

Action Potentials↗
PubMed1990

Reading with fixed and variable character pitch.

We compared the effects of fixed and variable (proportional) spacing on reading speeds and found variable pitch to yield better performance at medium and large character sizes and fixed pitch to be superior for character sizes approaching the acuity limit. The data indicate at least two crowding effects at the smallest sizes: one that interferes with individual character identification and one that interferes with word identification. A control experiment using rapid serial visual presentation suggests that it is the greater horizontal compression and consequently reduced eye-movement requirements of variable pitch that are responsible for its superiority at medium and large character sizes.

Eye Movements↗
PubMed1988

Effect of aging on kinetic parameters of 5 alpha-reductase in epithelium and stroma of normal and hyperplastic human prostate.

Altered 5 alpha-dihydrotestosterone (DHT) metabolism and stromal-epithelial cell interactions are two factors hypothesized to explain the development of benign prostatic hyperplasia (BPH). Furthermore, the development of BPH is clearly age dependent. Therefore, we studied the age-dependent alteration of 5 alpha-reductase, the enzyme that catalyzes the irreversible conversion of testosterone to DHT in epithelium and stroma of the human prostate. For this purpose kinetic parameters [Km Vmax] of 5 alpha-reductase were determined separately in epithelium and stroma of normal prostatic tissue (NPR) from 5 and BPH tissue from 20 men, and the results were correlated with the age of the donors (15-86 yr). The mean Km in epithelium [NPR, 14.3 +/- 1.8 (+/- SE); BPH, 29.5 +/- 2.7 nmol/L] was significantly (P less than 0.0001) lower than that in stroma (NPR, 78.4 +/- 8.5; BPH, 185.8 +/- 13.6 nmol/L). The mean Vmax in epithelium [NPR, 23.8 +/- 3.9 (+/- SE); BPH, 27.9 +/- 3.0 pmol/mg protein.h] was significantly (P less than 0.0001) lower than that in stroma (NPR, 68.3 +/- 4.4; BPH, 173.8 +/- 12.2 pmol/mg protein.h). The DHT-forming index (Vmax/Km) in NPR epithelium [1.6 +/- 0.2 (+/- SE)] was significantly (P less than 0.01) higher than that in NPR stroma (0.9 +/- 0.1), while in BPH the DHT-forming index was nearly identical in epithelium (1.1 +/- 0.1) and stroma (1.0 +/- 0.1). The Km values in epithelium and stroma both correlated positively (P less than 0.01) with age, but the Vmax values correlated positively with age (P less than 0.0001) only in stroma. The DHT-forming index decreased significantly with age in epithelium (P less than 0.01), but remained constant in stroma. These results indicate that there is a nonuniform age-dependent alteration of Km and Vmax in epithelium and stroma of the human prostate independent of the presence of BPH, which might have an impact on the conversion rate of testosterone to DHT with advancing age.

Adult↗
PubMedDate not supplied

[Comparative static biomechanical studies of tripod surface structures of cementless endoprostheses].

AIM: While the importance of stability of endoprosthetic surface structures has been recognized for some time there is a lack of comparative surveys and assessment indices that would permit comparison and improvement of surfaces on cementless endoprostheses. METHOD: Using separately produced, systematically mounted specimen pieces of endoprosthetic surfaces with isolated non-linked elements of varying shapes and sizes, stability parameters and stability behaviour are described. Results of tripode-structures are compared to spherical surfaces. RESULT: These investigations show clearly that geometrical attributes, the orientation and the contact of surface elements to the endoprosthetic stem influence the stability considerably more than the size of these surface elements. CONCLUSION: Using tripode-elements with different orientation, size and density, a differentiated formation of cementless endoprosthetic surfaces is possible.

Biomechanical Phenomena↗