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Biomedical subjects

J Kramer

Publications and source records attributed to J Kramer.

At least 145 records · Page 8Linked to original sources
PubMed1993

Bone-marrow oedema syndrome and transient osteoporosis of the hip. An MRI-controlled study of treatment by core decompression.

Bone-marrow oedema syndrome (BMOS) of the hip gives a characteristic MRI pattern, in association with severe pain, non-specific focal loss of radiological density and a positive bone scan. In our MRI-controlled study, nine patients with non-traumatic BMOS in ten hips all had core decompression. Bone-marrow pressure measurements and intraosseous venography in five cases showed pathological values. All patients had immediate relief of pain, with return of MRI signals to normal after three months. Regular review was continued for at least 24 months with serial clinical radiological and MRI assessment. At a mean follow-up of 33 months all patients remained free of pain with normal radiographs and MR scans. The histological evaluation of undecalcified sections obtained from eight core decompressions confirmed the presence of bone-marrow oedema, with necrotic and reparative processes involving bone and marrow similar to those of early avascular necrosis but with no evidence of 'osteoporosis'. These findings support the assumption that BMOS may be the initial phase of non-traumatic avascular necrosis. In most patients BMOS will have a self-limiting course, but the duration of symptoms may be reduced by core decompression treatment.

Adult↗
PubMed1993

[Modern intervertebral disk diagnosis].

Recent advances in our knowledge of the pathophysiology and function of the intervertebral disc, in combination with the use of CT and MRI have changed radiological diagnostic algorithms and enlarged our diagnostic scope. Microfissures in the cartilage endplates of the disc and in the endplates of the vertebral bodies and anulus fibrosus are the sequelae of loss of hydration of the nucleus pulposus leading to instability and abnormal load stress. MRI shows these early degenerative changes in the disc, but also reactive processes in the disc and the neighbouring vertebral bodies. On conventional X-rays only segmental malfunctions are visualized. Protrusion and prolapse can be recognized very well by CT, but best of all by MRI. Myelography and discography are very invasive and rarely used. Very important is that protrusion and prolapse are very often diagnosed without any clinical symptoms and that both may heal without any treatment. Therefore conservative treatment of prolapse and/or protrusion is the management of choice. Blastoma and infection of the disc are found in the vast majority of cases only in combination with corresponding diseases of the vertebral bodies. The only important exception are small children, in whom primary bacterial infection of the disc is well known.

Humans↗
PubMed1993

[Diagnostic imaging following surgery of spinal disk herniation].

The magnetic resonance imaging findings recorded in patients after surgery for degenerative disc disease in the lumbar and cervical spine are discussed in comparison with conventional radiographs and computed tomography findings. In the lumbar spine normal postoperative findings in the immediate postoperative period can be demonstrated by MR imaging. Contrast-enhanced MR imaging can differentiate disc herniation from postoperative scar formation with a greater degree of confidence than other imaging modalities. MR imaging improves differentiation between other causes of failed back syndrome such as postoperative hematoma and infection, lateral spinal stenosis and arachnoiditis. In the cervical spine types of operative approaches, the appearance of bony stenosis and disc herniations by MR imaging are discussed. Computed tomography still has a role in the assessment of osseous complications such as central or foraminal stenosis.

Humans↗
PubMed1993

Cranial MR imaging and cerebral 99mTc HM-PAO-SPECT in patients with subacute or chronic severe closed head injury and normal CT examinations.

Eighteen patients in the subacute or chronic state following severe closed head injury with normal cranial CT scans were examined by MR and 99mTc HM-PAO SPECT. Correlations were sought between these 2 imaging modalities and the clinical outcome, as defined by the Glasgow Outcome Scale (GOS) score. Both MR and SPECT revealed cerebral damage in all patients examined but structural and functional alterations did not coincide topographically in 64.9% of lesions. Nevertheless, complementary injury patterns suggesting poor recovery were found; cortical contusions and diffuse axonal injury (MR) in conjunction with cortical and thalamic hypoperfusion (SPECT) were noticed in 8 out of 12 patients with unfavorable outcome (GOS = III and IV). The synthesis of MR and SPECT information clearly enhanced the ability both to accurately assess posttraumatic brain damage and to improve patients' outcome prediction.

Adolescent↗
PubMed1993

[Systematic strength training in the postmenopause: accompanying densitometric control with DXA].

Of all the forms of osteoporosis, the postmenopausal type is the most important in social medicine due to the potentially high fracture risk in aging. The positive effects of physical activity on bone density have been emphasized in several studies. In this study on 31 female volunteers (minimum age 50 years), who had been postmenopausal for at least 2 years, 16 underwent systematic strength building (training group). They were compared with a control group consisting of 15 female volunteers. The parameters of success were physical strength and bone mineral density (BMD) before and after training. BMD was measured by dual-energy X-ray absorptiometry. The subjects in the control group showed significant decrease in bone density after 6 months: between 6.7 and 22.3% of the values measured at the beginning. The loss was more evident in the proximal femur than in the lumbar spine. In contrast, the subjects in the training group only showed a marginal decrease in bone density in the proximal femur: 0.8 to 3.8% of the earlier values. In the lumbar spine there was even a slight increase (+0.3%) in bone density.

Absorptiometry, Photon↗
PubMed1993

[Stenosis of the extracranial carotid artery].

Magnetic resonance angiography (MRA) as well as intraarterial digital subtraction angiography (DSA) were performed in 45 patients suffering from cerebrovascular disease, both procedures within one week of each other. MRA und DSA were evaluated separately for every patient retrospectively by two experienced radiologists on consensus basis. The results were then compared using catheter angiography as gold standard. Evaluation was confined to the common and internal carotid arteries (CCA, ICA) in the neck subdivided into 5 grades of stenosis. A comparative assessment was impossible in 9% cases due to motion artifacts and patient malposition. Out of 18 verified CCA stenoses 13 were demonstrated by MRA and 39 out of 44 ICA stenoses were assessed by MRA. There was a highly significant correlation between degree of stenosis detected by the two methods. Spearman Rank correlation coefficients of 0.824 and 0.913 were found for CCA and ICA, respectively.

Adult↗
PubMed1992

Molecular cloning, analysis, and chromosomal localization of a mouse genomic sequence related to the human papillomavirus type 18 E5 region.

The E5 open reading frame (ORF) from bovine papillomavirus type 1 (BPV 1) as well as the E5 ORFs from human papillomaviruses (HPV) type 6 and type 16 have been reported to transform immortalized rodent cells. In an analysis of murine and human tumors for the presence of putative papillomavirus-related sequences, we cloned amplified cellular sequences from the mouse cell line Eb that cross-hybridized with the E5 ORF of HPV 18. A 2.1-kb fragment termed HC1 was sequenced. In normal murine cells, it was present as a single-copy genomic sequence located on chromosome 8. A region of 213 nucleotides corresponded to the E5 gene (HC1 E5), based on the best alignments and on the presence of direct and inverted repeats bearing a central sequence motif. These structural elements are also present in the HPV 18 E5 ORF. HC1 E5 contained an ORF that was transcribed bidirectionally. The transcription in the E5 direction was enhanced in RNA obtained from organs and tumors from carcinogen-treated animals and C127 cells. The polypeptide deduced from the sequence was related to E5 proteins from genital papillomaviruses, to the putative product of the Q300 mouse gene, and to several viral and human growth factors. The data suggest that there may be several cellular counterparts to the viral E5 proteins.

Amino Acid Sequence↗
PubMed1992

MRI of cartilaginous tumours of the larynx.

Cartilaginous lesions of the larynx are uncommon, approximately 250 cases being documented in the literature. In general, these tumours grow slowly, exhibiting only local aggressiveness. Distant metastases are rare. Up until now CT has been the best diagnostic tool for the evaluation of these tumours because it demonstrates intratumoral calcification so well. To the best of our knowledge there are no reports of the use of MRI for these lesions. Three cases of cartilaginous laryngeal tumours are presented, emphasizing the MRI features.

Cartilage Diseases↗
PubMed1992

C1 inhibitor hinge region mutations produce dysfunction by different mechanisms.

Heterozygosity for a mutant dysfunctional C1 inhibitor protein, a member of the serine proteinase inhibitor (serpin) superfamily, results in type II hereditary angioneurotic oedema. We identified a "hinge" region mutation in C1 inhibitor with a Val to Glu replacement at P14 Val-432. Recombinant C1 inhibitors P10 Ala-->Thr and P14Val-->Glu did not form stable complexes with fluid phase C1s or kallikrein. The P14 Val-->Glu mutant, however, was cleaved to a 96K form by C1s, while the P10 Ala-->Thr mutant was not. The recombinant P10 mutant also did not complex with C1s, kallikrein or beta-factor Xlla-Sepharose. The two mutations, therefore, result in dysfunction by different mechanisms: in one (P14 Val-->Glu), the inhibitor is converted to a substrate, while in the other (P10 Ala-->Thr), interaction with target protease is blocked.

Alanine↗
PubMed1992

Factors influencing the DNA content of radiation-induced micronuclei.

The distribution of the DNA content of radiation-induced micronuclei was analysed in several cell lines (Chinese hamster, Syrian hamster and mouse NIH-3T3 cells) by flow cytometry. Frequency and DNA content of micronuclei were measured simultaneously using fluorescence and forward scatter signals of micronuclei and nuclei in suspension stained with ethidium bromide. Computerized random breakage of chromosomes and random combination of fragments was performed to compare the measured micronucleus distributions in synchronized cells irradiated during G1-phase with calculated distributions. The measured DNA distribution of radiation-induced micronuclei was found to be influenced by several factors: (1) the DNA distribution and the centromeric index of the chromosomes in the various cell lines; (2) the cell cycle phase at time of micronucleus measurement due to DNA synthesis in micronuclei; (3) the presence of chromosome fragments in micronuclei; and (4) the presence of whole chromosomes in micronuclei. These factors were shown to be responsible for the previously found large radiation-induced micronuclei which could not be explained by the classic assumption only that radiation-induced micronuclei are mainly produced by single acentric fragments.

3T3 Cells↗
PubMed1992

Improved time-of-flight MR angiography of the brain with magnetization transfer contrast.

The authors hypothesized that magnetization transfer contrast (MTC) could be used to improve flow contrast in time-of-flight (TOF) magnetic resonance (MR) angiography. Two- and three-dimensional flow-compensated gradient-echo images were obtained with and without MTC. MTC images were obtained by applying low-power radio-frequency (RF) radiation with a frequency offset from the bulk "free" water resonance frequency before the excitation RF pulse. The signal intensity of stationary tissue decreased as the power applied for the MTC pulse was increased. A smaller decrease occurred in venous signal intensity as measured in the superior sagittal sinus, and less change was seen in the arterial signal intensity as measured in the middle cerebral artery. Cerebrospinal fluid showed no MTC effect. The use of MTC improved small-vessel depiction on maximum-intensity projection images. The authors conclude that use of MTC can substantially enhance the quality of TOF MR angiography of the brain.

Adult↗
PubMed1992

Pituitary adenomas: findings of postoperative MR imaging.

Preoperative and postoperative magnetic resonance (MR) images obtained in 25 patients with pituitary macroadenomas (1.1-5.2 cm in diameter) were evaluated to determine normal (physiologic) and abnormal findings after transsphenoidal or subfrontal surgery. With a 1.5-T unit, T1-weighted sagittal and coronal images were obtained before and after administration of gadopentetate dimeglumine. The physiologic changes after surgery included resorption of packing material and sphenoid sinus opacifications, reexpansion of the pituitary gland, and lowering of the optic chiasm. Implanted gelatin foam appeared as an endosellar, circularly enhancing mass that was seen on follow-up studies to have decreased in size. Muscle-and-fat implants appeared as areas of high signal intensity. In 14 patients, residual tumors were found in the suprasellar (n = 4), retrosellar (n = 3), parasellar (n = 8), and/or endosellar (n = 3) space. Residual tumors were differentiated from implant materials by means of location, characteristic signal intensity, and enhancing pattern, which were identical to those of the corresponding preoperative adenoma in 13 cases (93%). Preoperative studies and clinical information are helpful in the evaluation of postoperative MR imaging examinations.

Adenoma↗
PubMed1992

Transaqueductal migration of a neurocysticercus cyst. Case report.

The clearly documented transaqueductal migration of a solitary intraventricular neurocysticercus cyst is described. The cyst was fortuitously demonstrated on magnetic resonance imaging during migration through the aqueduct. The radiological appearance and clinical significance of this condition are discussed.

Adult↗
PubMed1992

MRI of spondylitis.

MRI of proven spondylitis was performed in 39 patients. Acute spondylitis appeared hypointense on T1-weighted and hyperintense on T2-weighted images. Following intravenous administration of Gd-DTPA, enhancement of the marrow and disc was seen. With progressive healing an increasing signal was seen on T1-weighted images. This was caused by the presence of focal fat marrow representing the first sign of therapy response. As healing progressed, the T1-signal increased due to fatty marrow, while the T2-signal decreased as well as the enhancement following Gd-DTPA administration. Therefore, MR imaging can be recommended as the method of choice for early diagnosis of spondylitis and assessment of therapy response.

Adult↗
PubMed1991

Differential regulation of the expression of proteinases/antiproteinases in fibroblasts. Effects of interleukin-1 and platelet-derived growth factor.

We have previously reported that polypeptide growth factors had an anti-inflammatory effect by decreasing the cytokine-enhanced expression of factor B (FB), an activator of the alternative complement pathway, in human fibroblasts. To further characterize the role of cytokines and growth factors in the inflammatory/repair continuum, we have studied the effects of interleukin-1 (IL-1) and platelet-derived growth factor (PDGF) on the expression of metalloproteinases/antiproteinases of the extracellular matrix in cultured human fibroblasts. Co-incubation of IL-1 and PDGF synergistically increased the expression of stromelysin and interstitial collagenase to 23-fold (for both proteins) over background, while PDGF decreased the IL-1-enhanced expression of FB by 82%. PDGF, but not IL-1, alone or in combination, increased the synthesis of tissue inhibitor of metalloproteinases. RNA blot analysis indicated that the changes in protein synthesis were regulated at a pretranslational level. Cycloheximide treatment indicated that the effects of PDGF on the metalloproteinases/antiproteinases were not protein-dependent, in contrast to results obtained for FB. The effect of the three dimeric forms of PDGF (AA, AB, and BB) on the synthesis of metalloproteinases and FB was also analyzed. The effects were qualitatively similar for each of the dimeric forms; however, the BB and AB isoforms had considerably greater effects than PDGF-AA. It has been reported that the PDGF receptors found in human fibroblasts have higher binding affinity for the BB and AB isoforms of the growth factor. The results presented in this paper are in accord with the possibility that differences in the biological activity of the three isoforms of PDGF are due to differences in the number or affinity of the binding sites of the target cells, rather than to different activation pathways of the receptor. Thus, PDGF increased cytokine effects on metalloproteinases, while decreasing cytokine effects or complement activator FB. The net effect of these changes may be to decrease inflammation and enhance remodeling early in repair and to enhance matrix stability later in the repair process.

Blotting, Northern↗
PubMed1991

Evolution of the major histocompatibility complex: molecular cloning of major histocompatibility complex class I from the amphibian Xenopus.

Class I major histocompatibility complex (MHC) cDNA clones have been isolated from an expression library derived from mRNA of an MHC homozygous Xenopus laevis. The nucleotide and predicted amino acid sequences show definite similarity to MHC class I molecules of higher vertebrates. The immunoglobulin-like alpha-3 domain is more similar to the immunoglobulin-like domains of mammalian class II beta chains than to those of mammalian class I molecules, and a tree based on nucleotide sequences of representative MHC genes is presented.

Amino Acid Sequence↗
PubMed1991

MRI in basal ganglia diseases.

76 patients suffering from different basal ganglia diseases (28 cases with M. Parkinson, secondary parkinsonism and Parkinson diseases; 5 cases with Chorea Huntington; 5 cases with Fahr disease and 38 cases with M. Wilson) MRI featured 2 characteristical patterns: 1. abnormal deposition of minerals, 2. focal atrophies of involved organs. Thus MRI provides with informations about: 1. differential diagnosis in clinically misleading courses, 2. stage and, as a consequence, prognosis of some diseases, 3. biochemical processes of diseases in vivo.

Adolescent↗