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S Wachter

Publications and source records attributed to S Wachter.

7 recordsLinked to original sources
PubMed1998

Characterization of a sodium-dependent transport system for butyrobetaine into rat liver plasma membrane vesicles.

Butyrobetaine transport into the liver was studied using isolated rat hepatocyte plasma membrane vesicles. In the presence of a sodium chloride gradient, an overshoot could be observed, indicating active sodium-dependent transport. A similar overshoot was recorded in the presence of lithium, but not of potassium, cesium, or choline chloride. Investigation of several sodium salts revealed that an overshoot could only be observed in the presence of chloride, but not of nitrate, thiocyanate, sulfate, or gluconate. An osmolarity plot in the presence of sodium chloride revealed a slope different from zero and a positive intercept, indicating active transport and nonspecific binding, respectively. In agreement with the osmolarity plot, the kinetic characterization of butyrobetaine transport revealed a binding and a saturable component. The saturable component could be described by Michaelis-Menten kinetics, with a Km of 4.88 +/- 0.70 mmol/L and a Vmax of 4.16 +/- 0.73 picomoles per milligram of protein per second. Butyrobetaine transport could be inhibited significantly (30%) by 250 micromol/L propionylcarnitine, but not by D- or L-carnitine, other acylcarnitines (acetylcarnitine, isovalerylcarnitine, palmitoylcarnitine), trimethyllysine, or quinine. Butyrobetaine transport activity was also expressed in Xenopus laevis oocytes by injecting mRNA isolated from rat liver or kidney. After 5 days of cultivation, the endogenous butyrobetaine transport activity was increased by 82% in oocytes injected with liver mRNA and by 99% in oocytes injected with kidney mRNA. The studies show that butyrobetaine is transported actively across the basolateral plasma membrane of hepatocytes and that this transport is driven by sodium and chloride gradients. This transport is quite specific for butyrobetaine and is not rate-limiting for carnitine biosynthesis.

Animals↗
PubMed1998

[Probability of seminal vesicle involvement in localized prostatic carcinoma. Significance in conformal radiotherapy].

PURPOSE: The development of objective criteria for selecting patients for seminal vesicle irradiation on radical radiotherapy for prostate cancer will be important for successful planning of 3D conformal radiotherapy. MATERIALS AND METHODS: Based on morphometric studies from radical prostatectomy specimens, new imaging modalities with potential in the investigation of patients with gross seminal vesicle involvement and clinical factors with potential in the identification of patients with subclinical disease the development of objective guidelines is possible. RESULTS: Clinical tumor stage as determined by digital rectal examination, diagnostic tumor biopsy (Gleason Score), and pretherapy serum prostate-specific antigen value were significant factors for the probability of involvement of seminal vesicles. Studies show that seminal vesicle involvement is unlikely if the PSA is < 4 ng/ml or 4 to 10 ng/ml and Gleason Score < 7 and stage < or = T2b. In contrast, involvement of seminal vesicles is highly likely with levels above 20 ng/ml. In patients with PSA levels between 10 and 20 ng/ml and Gleason Score < 7 ultrasonographic findings with regard to tumor volume and localization will be useful to determine the extent of the target volume. For treatment planning a significant reduction in the volumes of irradiation to the rectum and bladder is evident when seminal vesicles were excluded. CONCLUSION: Prospective use of the objective criteria will be useful in the selection of patients for seminal vesicle involvement and should be an integral part in 3D conformal radiotherapy of prostate cancer.

Biopsy↗
PubMed1998

[Monitor assessment of digitalized and post-processed portal films compared to conventional films presented on a light box].

PURPOSE: Judgement of image quality and detail recognition of digitized and post-processed portal films presented on a computer monitor compared to the present standard, conventional portal films presented on a light box. MATERIALS AND METHODS: Conventional portal films of 3 different tumor sites (10 pelvis, 10 cranium, 10 vertebral column) were presented to a panel of 8 observers in 3 different matters: conventional film presented on a light box (Conv), digitized post-processed images (Dig-1) and digitized post-processed images (Dig-2) presented on a high resolution computer monitor. Subjective judgement of image quality, detailed recognition and time requirement of conventional films compared to monitor presentation were evaluated using a 5-scaled questionnaire (from 1 = much better to 5 = much worse). Furthermore the observers had to point out predefined anatomical bony structure on the conventional films (Conv) as well as on the digitized post-processed images (Dig-2). Standard deviations of the landmark outlined by 10 different observers were used as a criterion of objective detail recognition (Figure 1). RESULTS: Image quality of digitized post-processed images presented on the computer monitor was judged statistical significant better than that of conventional films (pelvis 78%, vertebral column 62%, cranium 45% better) (Figure 3). Similar results were found for comparison of detail recognition: digitized post-processed images were scored better for pelvis in 81%, for vertebral column in 57%, for cranium in 40% (Figure 4, Table 1). Most benefit from portal film enhancement was found for pelvic images, where portal films are known to be of poor image quality (Figure 2). In contrast image quality of non-processed digital images compared to conventional films was graded worse (pelvis 69%, vertebral column 53%, cranium 71% worse) (Figure 4). Digital post-processed images were especially for the pelvis judged to require less time (pelvis 68%, vertebral column 26%, cranium 8% less time requirement) (figure 5). For the pelvis a statistical significant decrease of standard deviations was found for Dig-2 compared to conventional films, indicating an objective increase of image quality and detailed recognition (Table 2). In case of vertebral column and cranium no significant differences were evaluated (Table 3). CONCLUSIONS: Digitized enhanced portal films presented on a computer monitor resulted in a quicker assessment and equal to better image quality as well as detail recognition compared to conventional films. Non-processed digitized images were judged to be of less image quality.

Data Display↗
PubMed1997

[Planned 3-dimensional low-volume conformal irradiation of a local prostatic carcinoma].

AIM: Recent data have shown a significant reduction of acute side effects by means of a three-dimensional planned conformal radiotherapy of carcinoma of the prostate compared to treatment techniques used before. Theoretically, an optimized field coverage of the planning target volume should result in a reduction of treated bladder and rectum volumes. We studied the effects of individualized blocks on treatment volumes, planning target volumes, irradiated bladder and rectum volumes on basis of three-dimensional treatment planning by means of beam's-eye-view technique. PATIENTS AND METHOD: We compared dose-volume-histograms of 2 different planning models, a (fictitious) open 4-field-box-technique and a technique with conformal blocked fields designed from the beam's-eye-view display (prescribed dose 66 Gy, daily single fraction 2 Gy). Plans of 115 patients with localized prostate cancer treated from January 1994 to February 1996 were analyzed. RESULTS: Using individualized fields treatment volume (covered by the 90%-isodose) was reduced by 23% on the average in comparison to the planning model without blocks. The averaged difference of treated volume and planning target volume, as a grade of efficiency of conformation, was reduced by 38% (496 cm3 303 cm3) using individualized blocks. 23% of the treated bladder volume and 13% of the treated rectum volume had been saved on the average. Nevertheless, at least 11.5% of the bladder volume and 27.6% of the contoured rectum volume were treated with the prescribed dose (55 Gy = 100%). CONCLUSIONS: The comparison of dose-volume-histogram-data showed that especially high dose volumes of organs at risk had been saved by means of individualized blocks created from the beam's-eye-view. The blocks did not affect the dose distribution of the planning target volume adversely. Consequently the impact of these data on the extent of side effects and local tumor control has to be proven.

Aged↗
PubMed1989

Early discontinuance of borderline patients from psychotherapy.

Sixty newly hospitalized patients with borderline personality disorder who began psychotherapy were followed for 6 months. Thirty-six discontinued their therapy--most often (N = 26) this was due to covert opposition, familial resistance, or angry dissatisfaction with treatment. The dropouts were healthier on some baseline measures than those who continued in therapy. Clinical implications that may diminish dropouts are discussed.

Adult↗