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Biomedical subjects

U Bergmann

Publications and source records attributed to U Bergmann.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Ultrasound biomicroscopy as a criterium of functional assessment of the supra-choroidal cleft after chamber angle surgical interventions].

BACKGROUND: The new technique of ultrasonic biomicroscopy provides detailed information about the extension and width of suprachoroidal clefts during the follow-up period after cyclodialysis ab interno. PATIENTS AND METHODS: We examined a group of 9 patients suffering from dysgenetic glaucoma and secondary glaucoma. Ultrasonic biomicroscopy was performed before and after cyclodialysis ab interno. The results were compared to those of gonioscopy. RESULTS: These examinations revealed that even cyclodialysis clefts which appeared to be closed by gonioscopy were still open. This was proven by a broad choroidal cleft in the cyclodialysis area. CONCLUSIONS: Thus, ultrasonic biomicroscopy is a means of checking the outcome of cyclodialysis ab interno and may influence the indications for further surgical procedures.

Adolescent↗
PubMed1997

Altered expression of insulin-like growth factor II receptor in human pancreatic cancer.

The insulin-like growth factor-II (IGF-II) receptor (IGF-IIR) is a single-chain transmembrane protein identical to the mannose-6-phosphate receptor. In the present study we examined IGF-IIR expression in normal and cancerous human pancreatic tissues. In the normal pancreas, moderately strong IGF-IIR immunoreactivity was present in the cytoplasm of islet cells, and mild cytoplasmic immunoreactivity was evident occasionally in ductal and acinar cells. Some ductal cells also exhibited nuclear IGF-IIR immunoreactivity. In the pancreatic cancers, regions of strong IGF-IIR immunoreactivity were present in the duct-like cancer cells within the tumor mass, often exhibiting nuclear localization. Expression of IGF-IIR mRNA in the cancer cells was confirmed by in situ hybridization. By comparison with normal pancreatic tissues, 7 of 12 pancreatic cancers exhibited a 5.6-fold increase in IGF-IIR mRNA levels, whereas in 3 cancers the IGF-IIR transcript was below the level of detection. Furthermore, all six tested cultured human pancreatic cancer cell lines expressed the IGF-IIR mRNA transcript. Our data indicate that IGF-IIR is overexpressed in a significant number of human pancreatic cancers, where it has a tendency to localize in the nucleus, and raise the possibility that IGF-IIR may contribute to the pathobiology of pancreatic cancer.

Adolescent↗
PubMed1996

Increased expression of insulin receptor substrate-1 in human pancreatic cancer.

Insulin receptor substrate-1 (IRS-1) is a multisite docking protein implicated in mitogenic signaling following activation of the insulin and insulin-like growth factor I receptors. In the present study we characterized IRS-1 expression in human pancreatic cancer. Northern blot analysis revealed high levels of IRS-1 mRNA transcripts in ASPC-1 and MIA PaCa-2 human pancreatic cancer cell lines, and lower levels in COLO-357, PANC-1, and T3M4 cells. Immunoblotting with anti-IRS-1 antibodies indicated that IRS-1 protein levels paralleled IRS-1 mRNA levels. Analysis of RNA isolated from normal and cancerous human pancreatic tissues indicated that 7 of 16 pancreatic cancer samples overexpressed IRS-1 mRNA transcripts by comparison with the normal pancreas and that insulin mRNA levels were abundant in many tumors. These data suggest that IRS-1 contributes to the signaling pathways that lead to excessive growth stimulation in human pancreatic cancer.

Blotting, Northern↗
PubMed1996

X-ray Monochromator with 2 x 10(8) Energy Resolution.

An X-ray beam of 3 x 10(7) photons s(-1) with 2 x 10(8) relative energy resolution has been obtained at a third-generation synchrotron undulator X-ray source using the (13 13 13) Bragg reflection from a silicon perfect crystal. The production of these 25.70 keV X-rays with 450 +/- 50 mueV bandpass opens up new possibilities in X-ray optics and spectroscopies.

Journal Article↗
PubMed1996

[Ultrasound biomicroscopy imaging of accommodative configuration changes in the presbyopic ciliary body].

Direct observation of the position of the ciliary body was possible only in cases of gross anatomic, and probably also functional, abnormalities. Utilizing the 50 MHz ultrasound biomicroscope, we investigated the profile changes of the ciliary body in ten eyes of ten patients, ranging in age from 54 to 86 years while they were ocusing on a target at a distance and afterwards on an object up close. After electronic image processing of ten single video pictures from each accommodative status, a summarized picture for every accommodative status was obtained. In seven of ten cases, during accommodation a remarkable shift of the ciliary body was observed anterior to the iris and in the direction of the lens equatore, while the iridociliary body contact zone became wider in five of the ten eyes. Ultrasound biomicroscopy allows visualization of the dynamics of the accommodative process. As the human ciliary body does not lose its contractility in the senium, the loss of accommodation in presbyopia is mainly caused by age-related changes of the lens and capsula.

Accommodation, Ocular↗
PubMed1995

Insulin-like growth factor I overexpression in human pancreatic cancer: evidence for autocrine and paracrine roles.

We assessed the potential roles of insulin-like growth factor-I (IGF-I) and the IGF-I receptor (IGF-IR) in human pancreatic cancer. IGF-I enhanced the growth of ASPC-1 and COLO-357 human pancreatic cancer cells, and this effect was significantly inhibited by a highly specific monoclonal anti-IGF-IR antibody (alpha IR3). Both cell lines expressed mRNA transcripts for IGF-IR, and basal cell growth was significantly reduced by an IGF-IR antisense oligodeoxynucleotide. IGF-I mRNA transcripts were not detected in either cell line or in two additional pancreatic cancer cell lines. In contrast, analysis of 12 pancreatic cancers revealed a 32-fold increase (P < 0.01) in IGF-I mRNA levels by comparison with the low levels observed in the normal pancreas. By in situ hybridization, IGF-I mRNA grains were present in both the cancer cells and in the surrounding connective tissue. Six of the cancers exhibited a 4.4-fold increase in IGF-IR mRNA levels. These findings suggest that IGF-I may participate in aberrant autocrine and paracrine activation of IGF-IR in pancreatic cancer in vivo.

Adolescent↗
PubMed1995

Autolytic activation of recombinant human 72 kilodalton type IV collagenase.

Human 72 kDa type IV collagenase (gelatinase A, MMP-2) was expressed in a baculovirus/insect cell system. The enzyme was produced in the wild-type form and in two mutant forms, where the active site Glu375 was substituted by Asp or Gln. The mutated proteins had strongly reduced or no detectable activity, respectively, allowing detailed analysis of rapid autoactivation reactions. MMP-2 was readily degraded to a proenzyme form lacking the first four amino acid residues. This cleavage was shown to be an autolytic process, although enzyme activity was apparently not affected by this truncation. Conversion to the active enzyme form was achieved without external activator in a concentration-dependent manner at 37 degrees C. The activation of MMP-2 was shown to be a stepwise process, probably via a delta 1-50 form as a highly unstable intermediate. The C-terminal hemopexin-like domain is removed rather early at two cleavage sites, and degradation within the Zn-binding site inactivates the enzyme. The fibronectin- and hemopexin-like domains are stable, although the autodegradation pattern did not show any sequence specificity, except for charged residues in the P1' position. The results indicate that a specific activator may not be essential for MMP-2.

Amino Acid Sequence↗
PubMed1995

[Continuous ultrasound biomicroscopic imaging of accommodative changes in the human ciliary body].

BACKGROUND: Slitlamp observations of the position of the ciliary body behind the iris root are possible only in cases of gross anatomic, and probably also functional, abnormalities. This study was performed to investigate physiological changes of the human ciliary body configuration during accommodation. MATERIAL AND METHODS: We used the 50 MHz ultrasound biomicroscope to measure the ciliary body changes in 5 left eyes of normal subjects during accommodation, while the right eye, wearing corrective spectacles, focussed Snellen letters at a distance of 3 m. For desaccommodation plus lenses were utilized, while negative lenses were applied to blur vision as a stimulus for accommodation. During postprocessing the best images of the video sequence were recalled on a monitor and the profile of the ciliary body was manually drawn on a transparent folder. For interpretation we used a projection system with vector analysis. RESULTS: During accommodation there is a shift of the ciliary body anteriorly toward the scleral spur and in the direction of the lens equator. In 4 out of 5 eyes a contact between the ciliary body and the posterior iris surface could be demonstrated. There was a measurably widening of the anterior chamber angle in 3 out of 5 eyes. CONCLUSIONS: Ultrasoundbiomicroscopy seems to be a way for assessing ciliary body deformation during accommodation. Our results are in accordance with histologic and gonioscopic findings and confirm biomechanical theories of the accommodation process. Further investigations including online digital image processing will be necessary to evaluate accommodation in its complexity.

Accommodation, Ocular↗
PubMed1995

[Postoperative complications and fatalities in surgical therapy of colon carcinoma. Results of the German multicenter study by the Colorectal Carcinoma Study Group].

In a prospective multicenter study an analysis of postoperative morbidity and mortality of 1224 patients with colon carcinoma treated in 7 departments of surgery was performed. The postoperative morbidity rate was 23.2% in elective surgery and 39.1% in emergency surgery. Postoperative mortality was 3.4% in elective cases and 11.6% in emergency cases. Preoperative associated diseases, which are more frequent in higher age, advanced tumor stage, and postoperative non-surgical complications rise operative mortality. However, surgical complications increase postoperative mortality only in cases of anastomotic leaks. The rates of postoperative complications depended on different surgical departments. Departments performing a delayed tumor resection in emergency surgery had better results. In elective cases the standard of oncological resections should be observed. In emergency cases operative procedure and extension of the resection should be planed in consideration of preoperative risk factors of the individual patient.

Adult↗
PubMed1995

[Ultrasound biomicroscopy for evaluation of space-occupying lesions of the anterior eye segment. Initial results].

Pavlin's group developed the ultrasound biomicroscope, and it has been in use since 1990. It is an ultrasound method working at high frequencies between 40 and 100 MHz. It is possible to resolve structures up to approximately 50 microns in size at a maximal depth of 5 mm. We examined about 80 patients with tumors in the anterior segments of the eye, mainly in the iris and the ciliary body. Good differentiation between cystic and solid space-occupying lesions is possible to say whether or not is malignant.

Adult↗