Biomedical subjects
R Löw
Publications and source records attributed to R Löw.
Liver-specific expression of interferon gamma following adenoviral gene transfer controls hepatitis B virus replication in mice.
Interferons control viral replication and the growth of some malignant tumors. Since systemic application may cause severe adverse effects, tissue-specific expression is an attractive alternative. Liver-directed interferon gene therapy offers promising applications such as chronic viral hepatitis B or C or hepatocellular carcinoma and thus needs testing in vivo in suitable animal models. We therefore used the Tet-On system to regulate gene expression in adenoviral vectors, and studied the effect of liver-specific and regulated interferon gamma expression in a mouse model of chronic hepatitis B virus (HBV) infection. In a first generation adenoviral vector, genes encoding for firefly luciferase and interferons alpha, beta or gamma, respectively, were coexpressed under control of the bidirectional tetracycline-regulated promoter P(tet)bi. Liver-specific promoters driving expression of the reverse tetracycline controlled transactivator ensured local expression in the livers of HBV transgenic mice. Following gene transfer, we demonstrated low background, tight regulation and a 1000-fold induction of gene expression by doxycycline. Both genes within the bidirectional transcription unit were expressed simultaneously, and in a liver-specific fashion in cell culture and in living mice. Doxycycline-dependent interferon gamma expression effectively controlled HBV replication in mice, but did not eliminate HBV transcripts. This system will help to study the effects of local cytokine expression in mouse disease models in detail.
Sodium Bose-Einstein condensates in the F = 2 state in a large-volume optical trap.
We have investigated the properties of Bose-Einstein condensates of sodium atoms in the upper hyperfine ground state. Condensates in the high-field seeking [F=2, m(F)=-2> state were created in a large volume optical trap from initially prepared [F=1, m(F)=-1> condensates using a microwave transition at 1.77 GHz. We found condensates in the stretched state [F=2, m(F)=-2> to be stable for several seconds at densities in the range of 10(14) atoms/cm(3). In addition, we studied the clock transition [F=1, m(F)=0> --> [F=2, m(F)=0> in a sodium Bose-Einstein condensate and determined a density-dependent frequency shift of (2.44+/-0.25+/-0.5) x 10(-12) Hz cm(3).
[Radiological assessment of loss of disk height in acute and chronic degenerative lumbar disk changes].
AIM OF THE STUDY: A loss of disc height with increasing segmental mobility is an important reason for low back pain. The measurement of hyaluronic acid content of the nucleus pulposus prolaps shows a difference between acute (group 1) and chronic (group 2) disc degeneration. The purpose of the present investigation was to determine the decreasing of disc height between these two groups and the not-symptomatic segments of these patients. METHODS: 20 human lateral preoperative X-rays measurements according to Frobin et al. [1] were taken; group 1 with 7 patients (mean age 41 years) and group 2 with 13 patients (mean age 44 years). RESULTS: There was a significant tendency (p = 0.091) to a reduction of disc height in group 2 between symptomatic and asymptomatic discs. CONCLUSION: The used method is not suitable to answer the present question conclusively.
[Attitudes of alcoholics to addiction-related topics].
PURPOSE: In Germany the attitudes towards alcohol consumption and smoking are rather heterogeneous. Although it is well accepted that both behaviours are harmful and often lead to addiction, thus far the attitudes of alcoholics to addiction-related topics have not been evaluated. METHODS: In this investigation 228 alcoholics were asked to complete a questionnaire of addiction-related topics. RESULTS: The attitudes were rather realistic, concerning the harmful effects of alcohol. The beliefs were only slightly influenced by personal involvement (e.g. divorce). Different opinions were given as to the riskiness of illegal drugs. The attitude towards the reasons of alcoholism are most important for therapeutical decisions. Only a third of the patients believed that they themselves were responsible for their addictive behaviour while nearly half accused socioeconomical factors. The curability of their alcoholism as well as their own competence to overcome alcoholism was estimated rather realistically by the patients. The results could not be generalized since the sample mainly consisted of alcoholics who themselves sought an alcohol-specific treatment service. Furthermore the data analysis shows that about 90 % of them regarded themselves as alcoholics. CONCLUSION: Future studies have to show whether these attitudes differ from those of the general population and from alcoholics not seeking-help.
[Low-field MRI of the ankle joint: initial experience in children and adolescents using an open 0.2 T MR-system].
PURPOSE: To evaluate the feasibility and diagnostic confidence of MRI with an open low field System (Magnetom open, Siemens, Germany) in children with predominantly traumatic disorders. MATERIAL AND METHODS: Conventional X-rays and MRI examinations have been evaluated in 55 children. MRI was performed at an open 0.2 T MR-unit. The study protocol comprised coronal STIR-sequence, an angulated T2 weighted TSE-sequence and T1 weighted SE-sequence. RESULTS: MRI showed ligamental rupture in 33/50 (60%) cases. Injuries of the ATFL were most frequent (27/33); osseous ligamental tears occurred in approx. 50% of all cases. Fractures of the distal tibia and fibula were diagnosed in 28/55 children. 15/28 cases showed an involvement of the epiphysis. We found occult fractures in 11/28 children. Fractures, diagnosed by conventional x-rays, were excluded in 6 cases. Therapy changed in 35/55 patients on the basis of MRI-findings. CONCLUSION: Low-field MRI of the ankle joint in children and adolescents is able to show numerous pathological conditions. We recommend low-field MRI of the ankle in children with persistent or unclear pain of the ankle joint and inconspicuous conventional x-ray.
Unusual manifestation of an osteoid osteoma of the capitate.
A case of osteoid osteoma of the capitate in a 29-year-old male is reported. The patient suffered from unspecific clinical findings and a 3-year history of uncharacteristic wrist pain. Conventional radiographs of the wrist revealed a circumscribed sclerosis in the proximal part of the capitate bone beside a diffuse demineralisation of the carpal bones. Magnetic resonance imaging demonstrated a circumscribed, tumorous lesion with marked enhancement after IV administration of contrast agent and a highly calcified nidus, which was sharply demarcated by a small rim of granulation tissue from the surrounding spongious bone. Based on MRI findings, the diagnosis of an osteoid osteoma was established and confirmed after operation and histologic analysis.
Preoperative diagnostics in pancreatic carcinoma: would less be better?
OBJECTIVE: The objective of this study was to investigate the value of preoperative diagnostics in patients with pancreatic carcinoma in terms of tumor diagnosis and evaluation of resectability. PATIENTS/METHODS: From 1 September 1985 to 31 December 1997, 408 patients shown by histology to have a ductal (n=330) or periampullary carcinoma (n=78) were treated at our hospital. RESULTS: In determining the presence of tumor, ultrasonography and computed tomography (CT) had a sensitivity of 88.3% and 94.0%, respectively; combined, they had a sensitivity of 96.2%. Endoscopic retrograde cholangiopancreatography (ERCP) had a sensitivity of 96.2%. Preoperative aspiration biopsy cytology had a sensitivity of 71.4%. No correlation was found in the patients undergoing surgery between the preoperative level of serum CA 19-9 and the presence of distant metastases. Tumor infiltration of the portal vein was shown with a sensitivity of 33.3%, 24.3%, and 76.5% and a specificity of 93.9%, 98.9%, and 65.6% by ultrasonography, CT, and angiography, respectively. Ultrasonography and CT detected liver metastases or peritoneal carcinomatosis with a sensitivity of 35.9% each and a specificity of 91.9% and 91.7%, respectively. CONCLUSION: This study shows that, in 96% of patients with pancreatic carcinoma, ultrasonography and CT are adequate for diagnosis and for the evaluation of resectability. ERCP is not the method of choice in the diagnosis of pancreatic carcinoma due to its invasiveness and to the fact that it fails to demonstrate the pathological anatomical location of the tumor; it should only be used if a tumor is suspected despite negative results on ultrasonography and CT or as an additional diagnostic method to differentiate between chronic pancreatitis and carcinoma. On account of the low sensitivity of percutaneous aspiration biopsy cytology, this method is not necessary preoperatively and may even lead to the spread of tumor cells. In 7% of patients, routine laparoscopy would additionally show liver metastases or peritoneal carcinomatosis not demonstrated using the imaging techniques.
[Low-field MR arthrography of the shoulder: early results using an open 0.2T MR system].
PURPOSE: To assess the practicability and image quality of doing MR arthrography of the shoulder using a 0.2T system. PATIENTS AND METHOD: 60 patients (24 with chronic instability, 36 with impingement syndrome) were examined in an open 0.2T MR apparatus (Magnetom Open, Siemens). After the intra-articular injections of 15-20 ml of a 2 mmol Gd-DTPA solution, coronary STIR, T1-weighted, sagittal and axial T2*-weighted FLASH 2D sequences were performed. 21 patients subsequently underwent surgery. RESULTS: Image quality of the T1- and T2*-weighted FLASH 2D sequences was regarded as good or adequate and movement artifacts were minor or moderate. STIR sequences were statistically significantly worse in respect of image quality and movement artifacts (p < 0.001, p < 0.005). The sensitivity and specificity in the diagnosis of rotator cuff rupture as confirmed by surgery was 100% (labrum lesions 100%, 93%). Agreement in the diagnosis of rupture of the supraspinatus and infraspinatus tendons was 0.93 and 0.65. CONCLUSION: MR arthrography of the shoulder using an open 0.2 T MR system provides adequate information concerning the intra articular structures of the joint. The disadvantage is the prolonged duration of the examination with the risk of poor image quality resulting from movement artifacts.
Nonradioactive northern blotting.
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[Whole body spiral CT in primary diagnosis of patients with multiple trauma in emergency situations].
PURPOSE: The aim of this study was to evaluate the role of a fast whole body helical CT scanner for primary diagnosis in trauma patients. METHODS: 27 severely injured patients (9 women, 18 men; mean age 43 years) were first examined with a helical CT scanner allowing for digital radiograms up to a length of 1024 mm and continuous helical scans of up to 70 seconds (slice thickness 3 to 10 mm, pitch factor up to 2). The primary CT diagnosis was verified either by x-ray after the CT examination or during the subsequent days, by abdominal ultrasound, by additional CT scans in the following days, and by clinical follow-up. RESULTS: CT showed all clinically relevant injuries of the head, spine, chest, abdomen and pelvis. The diagnosis and classification of vertebral fractures was performed immediately. 4% of the fractures of the extremities and the ribs were not seen primarily. 6% of the injuries were outside the CT scan field. CONCLUSION: Helical CT is a reliable and fast method to obtain vital information and to improve management planning in severely injured patients. It reduces the number of conventional x-ray examinations. In certain cases, additional x-rays of extremity fractures may be required.
The 32 kDa tonoplast polypeptide Di associated with the V-type H+-ATPase of Mesembryanthemum crystallinum L. in the CAM state: A proteolytically processed subunit B?
In the facultative halophyte Mesembryanthemum crystallinum, the salt- or age-induced transition to crassulacean acid metabolism (CAM) leads to the occurrence of a tonoplast-bound 32 kDa polypeptide (Di). The alignment of its N-terminal protein sequence with protein sequences of recently cloned higher plant V-ATPase B-subunits indicates that Di may be derived from subunit B by proteolytic removal of a protein fragment of about 20 kDa from its N-terminus. Furthermore, an antiserum directed against Di cross-reacts with subunit B from Nicotiana tabacum. It inhibits both proton pumping and ATP hydrolysis of the holoenzyme in M. crystallinum. As Di remains firmly attached to the holoenzyme the proteolytic processing may have functional implications.
Salt stress induces an increased expression of V-type H(+)-ATPase in mature sugar beet leaves.
In the halotolerant sugar beet co-expression of V-ATPase and a vacuolar Na+/H(+)-antiporter provides a mechanism for vacuolar salt sequestration. To analyze salt-induced changes in the expression of the vacuolar H(+)-ATPase (V-ATPase) a partial cDNA of the proton-channel forming subunit c was cloned by RT-PCR. Southern blot analysis indicated a small gene family. In control plants transcript levels were high in roots and young growing leaves but low in fully expanded leaves. In mature leaves salt exposure (400 mM, 48 h) induced a strong increase in subunit c-mRNA. Transcripts for the catalytic subunit A followed a similar developmental and stress-modulated pattern, indicating a coordinate regulation of transcripts for both V-ATPase subunits. Concomittant with the mRNA increases the amount of V-ATPase protein increased as well.
Early salt stress effects on the differential expression of vacuolar H(+)-ATPase genes in roots and leaves of Mesembryanthemum crystallinum.
In Mesembryanthemum crystallinum, the salt stress-induced metabolic switch from C3 photosynthesis to Crassulacean acid metabolism is accompanied by major changes in gene expression. However, early effects of salt exposure (i.e. prior to Crassulacean acid metabolism induction) on genes coding for vacuolar transport functions have not yet been studied. Therefore, the expression of vacuolar H(+)-ATPase genes was analyzed in different organs of 4-week-old plants stressed with 400 mM NaCl for 3, 8, or 24 h. Partial cDNAs for the subunits A, B, and c were cloned and used as homologous probes for northern blot analysis. In control plants, the mRNA levels for the different subunits showed organ-specific differences. In fully expanded leaves, subunit c mRNA was very low but increased transiently during the light period. Plant organs also differed in their salt-stress response. In roots and young leaves, mRNA levels for all three subunits increased about 2-fold compared to control plants, whereas in fully expanded leaves only subunit c mRNA responded to salt. The results indicate that the expression of vacuolar H(+)-ATPase genes does not always involve a fixed stoichiometry of mRNAs for the different subunits and that the mRNA level for subunit c is particularly sensitive to developmental and environmental changes.
[The magnetic resonance tomographic findings following the resection arthroplasty of the caput humeri].
PURPOSE: The resection of the humeral head is normally carried out only with respect to four-part and dislocation fractures in elderly patients. The purpose of this study was to examine whether there is a correlation between the clinical results and the MRI findings. MATERIAL AND METHODS: 8 patients underwent clinical and MR examination two to 6 years after resection. RESULTS: A cartilage-like tissue formation between the remaining humeral head and the glenoid fossa, with signal intensities comparable to hyalin cartilage was found in all patients. CONCLUSION: The good functional results following resectional surgery of the humeral head can partially be related to new substitute cartilage resulting from a chondroid metaplasia.
[Traumatic spinothoracic cerebrospinal fluid fistula].
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Sensitive, nonradioactive northern blots using alkaline transfer of total RNA and PCR-amplified biotinylated probes.
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[Quality of life--discourse and dialogue of a multilevel concept].
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