Biomedical subjects
Publications and source records attributed to J Kramer.
51 men who were more self-defeating were observed to use lower frequency of self-reinforcement and to be more depressed. The results were seen as supporting Beck's early work which proposed a relationship between depression and self-defeating patterns. They also provide construct validity for the measure of Self-defeating Personality used in the study.
Regarding cerebrovascular diseases magnetic resonance imaging (MRI) provides informations which could not be obtained before by any other imaging method. MRI permits an early detection of ischemic infarctions, exact delineation of lesions near to skull base, and microangiopathy. Further diagnosis of arteriovenous malformations and venous thromboses can be done without using contrast media. Exclusion of acute hemorrhage or subarachnoidal hemorrhage is still a domain of computed tomography (CT). Other MR methods, like magnetic resonance angiography (MRA) and magnetic resonance spectroscopy (MRS) are expected to replace angiography and positron emission tomography (PET) in the near future, at least for some purposes.
High-resolution real-time ultrasonography (US) and MR imaging, using both spin-echo (SE) and gradient-echo (GE) sequences, were performed prospectively in 14 patients with solitary osteocartilaginous exostoses to assess cartilage cap thickness and bursa formation. Results were compared to surgical and histopathologic findings in all cases. Both US and MR imaging were useful in evaluating exostotic cartilage cap thickness, which is supposed to be the most reliable sign of malignant transformation. Hyaline cartilage matrix had distinctive features in US and MR imaging caused by its specific histologic composition. The formation of bursae over the protruding exostoses, which results in pain and clinically could raise the suspicion of growth and malignant transformation, was demonstrated best using GE sequences. MR imaging was thus superior to US in the detection of bursa formation.
Magnetic resonance imaging is the study of choice in patients with suspected degenerative discogenic disease. It is a sensitive diagnostic modality offering multiplanar imaging capability and excellent soft-tissue and spatial resolution without ionizing radiation. Physiologic information, primarily relating to water content, is provided as is a myelographic effect, without the risks of intrathecal contrast. Computed tomography remains a valuable adjunct in those patients with extensive bony degenerative changes.
This article discusses the pathologic and radiologic changes in the cervical spine that occur with rheumatoid arthritis. The relevance of radiologic evaluation using radiographs, conventional tomography, myelography, computed tomography, computed tomography-myelography, and magnetic resonance imaging is discussed. Magnetic resonance imaging is the pre-eminent radiologic modality in the examination of cervical rheumatoid arthritis.
The central nervous system of nearly every HIV-positive patient becomes affected by the AIDS virus itself or by one of the associated diseases during the course of the illness. Early diagnosis of lesions which demand therapeutic consequences is of the most importance concerning prolongation of life and improvement in its quality. In spite of the frequent underestimation of cerebral involvement by imaging methods and their unspecific findings they are often the only diagnostic means which permit-timely diagnosis and, at least in some diseases, therapeutic monitoring. Indications for cranial computed tomography (CCT) or magnetic resonance tomography (MRT) are already present with mild or transient neurological or psychiatric symptoms or the extracerebral manifestation of neurotropic organisms or tumours which metastasize to the brain, even in patients without subjective complaints.
Thirty-eight patients with biochemically proven Wilson's disease underwent magnetic resonance-imaging (MRI) of the brain as well as neurological examinations. The patients were scanned using spin-echo (SE) sequences; the neurologist was looking for typical symptoms: dysarthria, tremor, ataxia, rigidity/bradykinesia and chorea/dystonia. Pathological MR findings believed secondary to this uncommon inherited disorder of copper metabolism were found in twenty-two subjects. Focal abnormalities were seen in the lenticular, thalamic and caudate nuclei as well as in brain stem and white matter; these lesions were best demonstrated on T2-weighted sequences as hyperintense areas. In eight patients we found diffuse brain atrophy with consecutive widening of the ventricular system. Five subjects showed mild, nineteen severe neurologic deficits. Generally there was no correlation between MR findings and clinical neurological symptoms; the impairment of cell-metabolism causing functional alterations of the brain precedes morphological changes. During treatment with the copper chelator D-penicillamine there seemed to be a phased course of disease. Shortening of T1-relaxation due to paramagnetic influence of copper was not seen; a possible explanation could be intracellular deposition--a proton-electron-dipolar-dipolar-interaction would therefore be impossible.
Rabbits immunized with dinitrophenylated calmodulin produced monospecific antibody against CaM. Using the purified antibody, enzyme-linked immunosorbent assays (ELISAs) were carried out for calmodulin (CaM). The immunological heterogeneity of human and bovine CaMs from erythrocytes was investigated by means of indirect and inhibition ELISAs. The cross-reactivity between the two CaMs was found to be 50% in the indirect ELISA. An eight times higher concentration of human CaM was necessary to produce 30% inhibition in an inhibition assay. The effect of anti-bovine CaM on the stimulation of the red cell membrane calcium pump by human and bovine CaM has also been studied. We have found that (a) the human and bovine CaMs showed indistinguishable activator activities; (b) the antibody partially inhibited the stimulating effects of CaMs; (c) the inhibition was much less effective in the case of stimulation by human CaM. These results suggest that there is a difference in the reactivity of the anti-bovine CaM antibody with bovine and human CaMs. This difference can be attributed to a slight deviation in the antibody binding structure of the two mammalian CaMs in or near the antigenic site of the CaMs.
Two different head coils--one with linear polarization and the other with circular polarization--were compared under the same measurement conditions. Comparison was done on a phantom with water-filled and gadolinium-filled pin-holes, as well as on anatomical MR images of 23 volunteers. In three volunteers the whole brain was examined while, in the remaining 20 volunteers the sella region or cerebellopontine angle region was examined. Criteria for comparison were signal-to-noise ratio, background noise, and detail resolution (phantom), as well as subjective criteria--image sharpness, anatomical, contrast, and recognition of anatomical details--, evaluated on anatomical MR images by four radiologists independently of each other. The results show a significant improvement of signal-to-noise ratio, lower background noise and therefore marked improvement of images sharpness, and moderate improvement in the recognition of anatomical details using the circular polarized head coil; as for as detail resolution and anatomical contrast were concerned, however, no significant difference was seen between the two coils. Major advantages of the circular, polarized head coil in clinical application are shorter measurement times (reduced number of acquisitions), as well as thinner slices without loss of signal-to-noise ratio.
MRI of proven spondylitis was performed in 39 patients. Acute spondylitis appeared hypointense on T1-weighted and hyperintense on T2-weighted images. Following intravenous application of Gd-DTPA, enhancement of the marrow and disk was seen. With progressive healing 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. Corresponding to the clinical healing process T1-signal increased due to fatty marrow, while the T2-signal decreased as well as the enhancement following Gd-DTPA application. Therefore, MR imaging can be recommended as the method of choice for early diagnosis of spondylitis and assessment of therapy response.
We present our first experience with MR in bone grafts in 23 patients. Graft implantation followed curettage of benign bone lesions. The locations were, rather exclusively, the long tubular bones. T1-and T2-weighted spin echo-sequences including intravenous application of Gadolinium-DTPA were performed (Magnetom 63, 1,5 T). A total of 29 examinations (1 follow-up control in 6 pat.) was divided into 5 groups, with regard to different stages after surgery, which varied from 1 week to more than 3 years postoperatively. The MR results were related to the respective groups. The results show typical stages of bone graft incorporation, but also greater individual variations in the duration of incorporation. Our first results, however, represent only "snapshots" of different patients at different stages after bone graft surgery. Therefore some important questions are still unanswered but may perhaps be explained with the help of subsequent prospective studies.
46 patients with invasive pulmonary aspergillosis (IPA) were investigated by chest radiographs (n = 46), plain film tomograms (n = 16), CT (n = 8) and MRI (n = 13). Radiologic characteristics of early IPA were nodular or patchy infiltrates in the upper lobes of all patients. Enlargement of the infiltrates and/or development of segmental/lobar consolidations were typical for fully developing IPA. Air crescent signs were seen in 40% of patients during or after bone marrow restitution. CT added additional information by visualisation of small pleural based infiltrates, demonstration of air crescents and identification of halo phenomena. MRI revealed the target character of nodular aspergillomas with hypointense centres and rims of higher signal intensity. A gadolinium-DTPA rim enhancement could be observed in almost all nodular lesions. Hyperintense areas in nodular and segmental infiltrates on T1-weighted images were interpreted as aging haemorrhage (methemoglobin) in aspergillus-induced haemorrhagic infarcts or in focal parenchymal bleeding.
Magnetic resonance examinations were performed in 15 patients suffering from echocardiographically detected intracardiac masses. All patients were examined with a 1.5 T superconducting machine, using spin echo technique, including Gd-DTPA, and gradient echo sequences. The MR findings were confirmed partially by histology and angiography, otherwise by good correlation to clinical findings. MR results were divided into three groups: 1. tumour, 2. thrombosis, 3. pseudotumorous mass, and corresponded well with the final diagnosis: in 8 patients tumour, in 5 patients thrombosis, and in two patients pseudotumorous masses, including one hydatid cyst and one case of lipomatosis. Tumours showed in contrast to thrombosis marked enhancement after gadolinium injection, whereas the hydatid cyst and the lipomatosis demonstrated characteristic signal behaviour. Problems existed in differentiation mass vs slow flow, in the detection of very small masses, and in the assessment of wall-fixation and motion of a mass during cardiac cycle. The results demonstrate that MRI with Gd-DTPA can give important additional information in the differential diagnosis of echocardiographically detected intracardiac masses.
Hereditary angioneurotic edema is inherited as an autosomal dominant disorder and is characterized by potentially life-threatening episodic angioedema. In type II hereditary angioneurotic edema, a dysfunctional C1 inhibitor molecule is present together with low levels of normal C1 inhibitor. About 70% of these dysfunctional proteins result from reactive center (Arg-444) mutations. We describe the deletion of nucleotides encoding Lys-251 (AAG) in C1 inhibitor Ta, the dysfunctional C1 inhibitor from a family with type II hereditary angioneurotic edema. DNA sequence analysis was derived from clones obtained through polymerase chain reaction amplification of blood monocyte C1 inhibitor mRNA. As expected, clones with both normal and abnormal sequence were isolated. The deletion was verified by protein sequence analysis. These data, together with biochemical analysis of the protein and cell-free translation studies, suggest that this deletion, by altering the normal amino acid sequence from Asn-Lys-Ile-Ser to Asn-Ile-Ser, creates a new glycosylation site. The additional carbohydrate accounts for the larger size on SDS/PAGE and very likely interferes with protein function.
DNA synthesis in radiation-induced micronuclei of Chinese hamster cells was studied as a function of time after irradiation using pulse labelling of cells with bromodeoxyuridine (BrdUrd) and an immunofluorescence technique with anti-BrdUrd antibodies. It was shown with this technique that DNA synthesis in micronuclei corresponds with DNA synthesis in nuclei during S phase in approximately 98% of the micronuclei. The presence of radiation-induced micronuclei that are too large to be produced by acentric fragments alone was therefore attributed at least in part to DNA synthesis in micronuclei. A partially synchronized progression of micronuclei from G1 phase into S phase could be observed allowing the measurement of the duration of G1 phase in cells containing micronuclei. The duration of G1 phase in these cells agreed with the duration of G1 phase in unirradiated cells.
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Thirty-eight patients with mediastinal and/or hilar masses were imaged by computed tomography (CT) and magnetic resonance imaging (MRI). Results were analyzed retrospectively regarding the ability to demonstrate the masses, their number, size, definition, location and tissue characteristics. CT and MRI showed equivalent results in 32 cases; additional information was obtained in two patients by CT, in four patients by MRI. In view of the specific advantages and limitations of both CT and MRI we believed that in patients with mediastinal and/or hilar masses, contrast enhanced CT remains the procedure of choice after performing plain chest radiographs; in certain cases MRI will prove useful for further evaluation.
Allotype frequencies of three complement proteins (C2, factor B, and C4) encoded on the sixth chromosome were tested in 150 "young" (under 53 yrs) and 131 "old" (over 62 yrs) healthy Hungarian individuals. In women, we found significant differences in BF*F allotype frequencies between the two age groups. A marked decrease of null alleles for C4 was observed especially in men. In the "old" age group, the total frequency of the non-expressed, "null" (Q0) alleles of the C4 protein dropped to almost one third of the "young" ones. The decrease was even larger (a 5.5-fold decrease in the incidence) among men. The relative risk of those having C4B*Q0 allele not to survive a "critical age period" of 53-62 yrs for males and 58-62 yrs for females was calculated to be 12.4 and 2.85, respectively. Our data substantiate the view that the expected life time is genetically determined and it can be forecast partly by the analysis of the antigens encoded on the sixth chromosome.