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Biomedical subjects

A Kopp

Publications and source records attributed to A Kopp.

At least 19 recordsLinked to original sources
PubMed2001

[Optimizing image reconstruction timing for the RR interval in imaging coronary arteries with multi-slice computerized tomography].

PURPOSE: Multislice spiral CT is a newly developed technology that allows the non-invasive detection of coronary stenoses and plaques. The acquired raw data are reconstructed at a given time point in the RR interval of the heart cycle. Thus, determination of this time point is a key factor for picture quality and for reliable diagnostic results. This study was performed to investigate the optimal time point for reconstruction within the RR interval. MATERIALS AND METHODS: The coronary arteries of 13 patients were examined with CT. Raw data were reconstructed 250, 350, 450 and 550 ms before the following R wave (absolute reverse retrospective ECG gating) for each patient. Data were then analyzed with a volume rendering mode on a SIEMENS 3 D-Virtuoso workstation. A total of 91 segments (segments 1 and 2 of the RCA, segments 5, 6, 7 and proximal and distal parts of segment 11) were assessed and image quality was classified. RESULTS: Visualization of the left main coronary artery was of a good quality at all time points, segments 6 and 7 of the LAD as well as the proximal and distal parts of segment 11 of the RCX had the best quality at 450 ms absolute reverse retrospective ECG gating. The segments 1 and 2 of the RCA were of best quality 550% ms absolute reverse to the R peak. CONCLUSIONS: Classification of image quality of coronary artery CT scans after retrospectively ECG gated reconstruction is highly determined by the time point of reconstruction in the heart cycle. The optimization of this time point increases diagnostic accuracy and helps to avoid misinterpretation due to image artifacts.

Blood Flow Velocity↗
PubMed2001

Waste gas exposure to sevoflurane and nitrous oxide during anaesthesia using the oesophageal-tracheal Combitube small adult.

Exposure to sevoflurane (SEV) and nitrous oxide during ventilation using a Combitube (37Fr) small adult (SA) was compared with waste gas exposure using conventional endotracheal tubes. Trace concentrations of SEV and nitrous oxide were assessed using a direct reading spectrometer during 40 gynaecological laparoscopic procedures under general anaesthesia. Measurements were made at the patients' mouth and in the anaesthetists' breathing zone. Mean (SD) concentrations of SEV and nitrous oxide measured at the patients' mouth were comparable in the Combitube SA (SEV 0.6 (0.2) p.p.m.; nitrous oxide 9.7 (8.5) p.p.m.) and endotracheal tube group (SEV 1.2 (0.8) p.p.m.; nitrous oxide 17.2 (10.6) p.p.m.). These values caused comparable contamination of the anaesthetists' breathing zone (SEV 0.6 (0.2) p.p.m. and nitrous oxide 4.3 (3.7) p.p.m. for the Combitube SA group, compared with SEV 0.5 (0.2) p.p.m. and nitrous oxide 4.1 (1.8) p.p.m. for the endotracheal tube group). We conclude that the use of the Combitube SA during positive pressure ventilation is not necessarily associated with increased waste gas exposure, especially when air conditioning and scavenging devices are available.

Adult↗
PubMed2000

Effect of pre-emptive hydromorphone administration on postoperative pain relief--a randomized controlled trial.

BACKGROUND AND AIM OF STUDY: Pre-emptive analgesia represents a treatment strategy which tries to prevent the development of pain by inhibiting central reactions to peripheral sensory stimuli. In a prospective randomized double-blind placebo-controlled study, the effect of oral premedication with 4 mg of a slow-release hydromorphone preparation on postoperative piritramide consumption and subjective pain perception is being evaluated. PATIENTS AND METHODS: 96 women undergoing hysterectomy were randomly assigned to four study groups. Patients from groups 1 and 2 received hydromorphone and placebo respectively two hours before surgery, while those from groups 3 and 4 were given the same substances one hour after the end of the operation. Postoperative pain relief was provided by a patient-controlled infusion pump with piritramide. The intensity of postoperative pain as perceived by the patients was quantified on a visual analogue scale. Piritramide consumption and pain scores were recorded at 1 and 24 hours after surgery. Approval of the local Ethics Committee had been obtained beforehand as well as written informed consent from the patients. RESULTS: No significant differences in piritramide consumption were observed in between the four study groups. Visual analogue scale (VAS) ratings at 1 and 24 hours after surgery did not show any significant differences either--irrespective of whether the patients had received hydromorphone or placebo preoperatively or postoperatively. CONCLUSION: In our study, oral administration of 4 mg of slow-release hydromorphone did not show any greater pre-emptive analgesic effect than placebo.

Administration, Oral↗
PubMed2000

Genetic control and evolution of sexually dimorphic characters in Drosophila.

Sexually dimorphic abdominal pigmentation and segment morphology evolved recently in the melanogaster species group of the fruitfly Drosophila. Here we show that these traits are controlled by the bric à brac [corrected] (bab) gene, which integrates regulatory inputs from the homeotic and sex-determination pathways. bab expression is modulated segment- and sex-specifically in sexually dimorphic species, but is uniform in sexually monomorphic species. We suggest that bab has an ancestral homeotic function, and that regulatory changes at the bab locus played a key role in the evolution of sexual dimorphism. Pigmentation patterns specified by bab affect mating preferences, suggesting that sexual selection has contributed to the evolution of bab regulation.

Animals↗
PubMed2000

[Multislice spiral CT of the paranasal sinuses: first experiences using various parameters of radiation dosage].

PURPOSE: To evaluate the potential of multislice CT in the diagnosis of the paranasal sinuses. METHODS: Dose measurements were performed exposing an Alderson Rando phantom in a four-slice spiral CT (MS-CT) while applying a variety of scan parameters. Additionally, 30 consecutive patients underwent a transversal examination by the MS-CT using 1/1/3.5/0.5 mm spiral parameters and an additional transversal or coronal scan on a conventional single slice spiral CT (SS-CT) with 2/3/1 mm. Coronal reformations of the MS-CT were compared with the primary coronal SS-CT, or coronal reformations of the transversal SS-CT, respectively, with regard to image quality and depiction of relevant anatomical details of the region. RESULTS: Superficial exposure values at the level of the eye lenses as well as for the thyroid gland were superior for MS-CT (3.62 mGy, and 0.12 mGy, resp.) as compared to SS-CT (2.96 mGy, and 0.07 mGy). Image quality was equal or superior for MS-CT as compared to SS-CT in all but one case. Drawbacks of SS-CT, such as dental amalgam artifacts, stair step artifacts or partial volume artifacts did not notably affect the coronal reformations of MS-CT. CONCLUSION: MS-CT seems to have the potential to replace primary coronal CT of the paranasal sinuses without any loss of image quality, but may even improve the overall diagnostic value. Radiation doses may still have to be reduced.

Humans↗
PubMed1999

Clinical performance of polyacid-modified resin restorations using "softstart-polymerization".

This study investigated the influence of "softstart-polymerization" on the clinical performance and marginal integrity of polyacid-modified resin restorations (PMR) in class V cavities. Eighty PMR restorations were placed in 20 patients [40 Dyract (DY); 40 Hytac (HY)] with (npat = 10) and without preparation (npat = 10). Restorations were light cured for 40 s either conventionally (CP) or with a lower light intensity for the first 10 s (SSP). Each patient received four restorations (DY-CP, DY-SSP, HY-CP, HY-SSP), which were examined clinically according to modified USPHS criteria, and by quantitative SEM-analysis after 7 days (baseline), 6 months and 1 year. Statistical analysis was performed using the Mann-Whitney-U test (P < or = 0.05) and error rates method. Clinically, no restoration showed recurrent caries or crevices. After 1 year, margins of 24-47% of the HY- and 36-53% of the DY-restorations were rated "Bravo". Marginal discoloration occurred in 20-37% in HY- and in 18-21% in DY-restorations. The error rates method revealed no significant differences between materials or between polymerization modes with and without preparation. Pairwise testing showed that without preparation, the marginal adaptation to dentin was significantly worse compared to enamel for HY with both polymerization modes, for DY with SSP. With preparation, no significant differences were found. Cavity preparation may have an influence on differences in marginal quality between enamel and dentin.

Compomers↗
PubMed1999

Wingless, decapentaplegic and EGF receptor signaling pathways interact to specify dorso-ventral pattern in the adult abdomen of Drosophila.

Adult abdominal segments of Drosophila are subdivided along the dorso-ventral axis into a dorsal tergite, a ventral sternite and ventro-lateral pleural cuticle. We report that this pattern is largely specified during the pupal stage by Wingless (Wg), Decapentaplegic (Dpp) and Drosophila EGF Receptor (DER) signaling. Expression of wg and dpp is activated at the posterior edge of the anterior compartment by Hedgehog signaling. Within this region, wg and dpp are expressed in domains that are mutually exclusive along the dorso-ventral axis: wg is expressed in the sternite and medio-lateral tergite, whereas dpp expression is confined to the pleura and the dorsal midline. Neither gene is expressed in the lateral tergite. Shirras and Couso (1996, Dev. Biol. 175, 24-36) have shown that tergite and sternite cell fates are specified by Wg signaling. We find that DER acts synergistically with Wg to promote tergite and sternite identities, and that Wg and DER activities are opposed by Dpp signaling, which promotes pleural identity. Wg and Dpp interact antagonistically at two levels. First, their expression is confined to complementary domains by mutual transcriptional repression. Second, Wg and Dpp compete directly with one another by exerting opposite effects on cell fate. DER signaling does not affect the expression of wg or dpp, indicating that it interacts with Wg and Dpp at the level of cell fate determination. Within the tergite, the requirements for Wg and DER function are roughly complementary: Wg is required mainly in the medial region, whereas DER is most important laterally. Finally, we show that Dpp signaling at the dorsal midline controls dorso-ventral patterning within the tergite by promoting pigmentation in the medial region.

Abdomen↗
PubMed1997

beta Amyloid does not activate the antioxidant pentose phosphate pathway within the B12 neural cell line.

The aim of this study was to determine whether neural cells exposed to beta amyloid (A beta) activate the pentose phosphate pathway (PPP), a critical oxidative stress defense mechanism. A beta stimulated H2O2 production in neural (B12) and non-neural (HepG2) cells and stimulated PPP activity, the source of the main intracellular reductant NADPH, in HepG2 cells (67% increase). Catalase blocked the A beta-induced increase in PPP, demonstrating that H2O2 mediated the increase in PPP activity. B12 cells showed no increase in PPP following A beta exposure. Fifty-five per cent of HepG2 cells but only 11.1% of B12 cells remained viable after A beta exposure. Lack of PPP activation may contribute to A beta cytotoxicity in neural calls and may lead to differences in survival between neural and non-neural cells.

Amyloid beta-Peptides↗
PubMed1997

The roles of hedgehog and engrailed in patterning adult abdominal segments of Drosophila.

We present evidence that hedgehog (hh) protein secreted by posterior compartment cells plays a key role in patterning the posterior portion of the anterior compartment in adult abdominal segments. Loss of function of hh in the hh(ts2) mutant causes the loss of posterior tergite characteristics in the anterior compartment, whereas ectopic expression driven by hs-hh or the gain-of-function allele hh(Mir) causes transformation of anterior structures toward the posterior. FLP-out hh-expressing clones in the anterior compartment induce surrounding wild-type cells to produce posterior tergite structures, establishing that hh functions nonautonomously. The effects of pulses of ectopic expression driven by hs-hh indicate that bristle type and pigmentation are patterned by hh at widely different times in pupal development. We also present evidence that the primary polarization of abdominal segments is symmetric. This symmetry is strikingly revealed by ectopic expression of engrailed (en). As expected, this transforms anterior compartment cells to posterior compartment identity. In addition, however, ectopic en expression causes an autonomous reversal of polarity in the anterior portion of the anterior compartment, but not the posterior portion. By determining the position of polarity reversal within en-expressing clones, we were able to define a cryptic line of symmetry that lies within the pigment band of the normal tergite. This line appears to be retained in hh(ts2) mutants raised at the restrictive temperature, suggesting it is not established by hh signaling. We argue that the primary role of hh in controlling polarity is to cause anterior compartment cells to reverse their interpretation of an underlying symmetric polarization. Consistent with this, we find that strong ectopic expression of hh causes mirror-symmetric double posterior patterning, whereas hh loss of function can cause mirror-symmetric double anterior patterning.

Abdomen↗
PubMed1997

Control of cell fate and polarity in the adult abdominal segments of Drosophila by optomotor-blind.

In an accompanying report (Kopp, A., Muskavitch, M. A. T. and Duncan, I. (1997) Development 124, 3703-3714), we show that Hh protein secreted by posterior compartment cells patterns the posterior portion of the anterior compartment in adult abdominal segments. Here we show that this function of hh is mediated by optomotor-blind (omb). omb- mutants mimic the effects of loss-of-function alleles of hh: structures from the posterior of the anterior compartment are lost, and often this region develops as a mirror image of the anterior portion. Structures from the anterior part of the posterior compartment are also lost. In the pupa, omb expression in abdominal histoblasts is highest at or near the compartment boundary, and decreases in a shallow gradient toward the anterior. This gradient is due to activation of omb by Hh secreted by posterior compartment cells. In contrast to imaginal discs, this Hh signaling is not mediated by dpp or wg. We describe several gain-of-function alleles that cause ectopic expression of omb in the anterior of the segment. Most of these cause the anterior region to develop with posterior characteristics without affecting polarity. However, an allele that drives high level ubiquitous expression of omb (QdFab) causes the anterior tergite to develop as a mirror-image duplication of the posterior tergite, a pattern opposite to that seen in omb- mutants. Ubiquitous expression of hh causes similar double-posterior patterning. We find that omb- alleles suppress this effect of ectopic hh expression and that posterior patterning becomes independent of hh in the QdFab mutant. These observations indicate that omb is the primary target of hh signaling in the adult abdomen. However, it is clear that other targets exist. One of these is likely Scruffy, a novel gene that we describe, which acts in parallel to omb. To explain the effects of omb alleles, we propose that both anterior and posterior compartments in the abdomen are polarized by underlying symmetric gradients of unknown origin. We suggest that omb has two functions. First, it specifies the development of appropriate structures both anterior and posterior to the compartment boundary. Second, it causes cells to reverse their interpretation of polarity specified by the underlying symmetric gradients.

Abdomen↗
PubMed1997

Transient alkaline hyperphosphatasaemia in an adult: biochemical peculiarities.

We report on a 27-year-old healthy female with transient hyperphosphatasaemia of adulthood (it is the eighth case ever recorded). A maximum alkaline phosphatase activity of 1950 U/l, 11-fold the upper reference limit, was measured. The activity normalized within 11 weeks. Electrophoresis revealed the typical pattern for alkaline phosphatase isoenzymes observed in transient hyperphosphatasaemia of infancy: a fast-migrating liver isoenzyme and a bone isoenzyme. Contrary to the findings in transient hyperphosphatasaemia of infancy the liver isoenzyme did not precipitate with wheat-germ lectin whereas the bone isoenzyme partially bound to lectin. Biochemical features of transient hyperphosphatasaemia in an adult may be different from those in infancy. Recognition of an atypical pattern could help avoid unnecessary extensive investigations.

Adult↗
PubMed1996

Regulation and role of TGF beta production in breast cancer.

The influence of antiestrogens on the secretion of transforming growth factor beta (TGF beta) proteins that have an autoinhibitory potential for human cancer cells was studied in the estrogen-responsive human breast cancer cell line, MCF-7: Antiestrogens induce the secretion of TGF beta-1 via a nontranscriptional pathway; TGF beta-1 itself induces TGF beta-2 by a direct transcriptional mechanism; and TGF beta-2 is a marker of antiestrogen action. This hypothesis was confirmed in a clinical study with 18 patients with advanced metastatic breast cancer. TGF beta-2 plasma levels were measured before and after 4 weeks of treatment with tamoxifen. In the majority of patients who responded to the treatment, increasing TGF beta-2 concentrations were seen under therapy. Patients who did not respond did not show changes in the TGF beta-2 plasma level after 4 weeks of treatment. These results suggest that the sequential analysis of TGF beta-1 in plasma before and under treatment with tamoxifen allows the early identification of patients with antiestrogen resistance.

Breast Neoplasms↗
PubMed1995

Transforming growth factor beta 2 (TGF-beta 2) levels in plasma of patients with metastatic breast cancer treated with tamoxifen.

Blood levels of transforming growth factor beta 2 (TGF-beta 2) were measured in 20 patients with metastatic breast cancer before and during treatment with the antiestrogen tamoxifen, and in a control group of 7 patients with primary breast cancer before and during adjuvant tamoxifen treatment. The results of this study reveal typical time patterns for TGF-beta 2 in relation to the clinical outcome. Patients in remission showed a significant increase of TGF-beta 2 in the first 4-6 weeks of therapy, followed by a subsequent decrease. Patients who did not respond showed unchanged or diminished TGF-beta 2 values after start of therapy, followed by a later increase preceding the clinical manifestation of tumor progression. Thus, TGF-beta 2 blood levels after 4 weeks of tamoxifen treatment can be used as an early marker for prediction of response.

Breast Neoplasms↗
PubMed1995

[Primary lymphoma of the cervix uteri--2 case reports].

Two cases of primary non-Hodgkin's lymphoma of the uterine cervix are described. Diagnostic pitfalls and therapeutic applications of this rare disease are discussed. The main approach in local therapy is external beam radiation--with or without surgical staging. Prognosis is favourable--depending on the stage of disease.

Adult↗