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Biomedical subjects

G Schubert

Publications and source records attributed to G Schubert.

At least 19 recordsLinked to original sources
PubMed1994

[Clinical and urodynamic effects of oral propiverine therapy in neurogenic urinary incontinence. A multicenter study for optimizing dosage].

The efficacy and tolerability of propiverine hydrochloride (in doses of 15, 30, 45 and 60 mg/day) were evaluated in the treatment of 66 patients suffering from neurogenic incontinence for 21 days in an open, randomized, multicentre, parallel-group trial. Evaluation of efficacy was based on changes in cystometry, flow measurements and micturition and that of safety on adverse reactions and blood chemistry. The bladder volume increased and bladder pressure decreased dose dependently; the ratio of the two increased by 0.6, 3.3, 3.8 and 8.1 ml/cm H2O after 15, 30, 45 and 60 mg/day respectively. Some 54% of patients had a decreased micturition frequency after 15 mg/day and about 80% after 30-60 mg/day. At the same time, 8, 35, 12 and 42% of patients had subjective anticholinergic symptoms after therapy with 15, 30, 45 and 60 mg/day, respectively. The results suggest that propiverine is a safe and effective drug for the treatment of neurogenic incontinence. A daily dose of 30 mg propiverine is recommended; individual adjustment of the maintenance dose to 15 or 45 mg/day may be necessary.

Adolescent↗
PubMed1992

Liver-specific drug targeting by coupling to bile acids.

Bile acids are selectively taken up from portal blood into the liver by specific transport systems in the hepatocyte plasma membrane. Therefore, studies were performed to evaluate the potential of bile acids as shuttles to deliver drugs specifically to the liver. The alkylating cytostatic drug chlorambucil and the fluorescent prolyl-4-hydroxylase inhibitor 4-nitrobenzo-2-oxa-1,3-diazol-beta-Ala-Phe-5-oxaproline-Gly were covalently linked via an amide bond to 7 alpha, 12 alpha,-dihydroxy-3 beta- (omega-aminoalkoxy)-5-beta-cholan-24-oic acid. The chlorambucil-bile acid conjugates S 2521, S 2539, S 2567, and S 2576 inhibited Na(+)-dependent [3H]taurocholate uptake in a concentration-dependent manner both into isolated rat hepatocytes and rabbit ileal brush border membrane vesicles, whereas the parent drug chlorambucil showed no significant inhibitory effect. The chlorambucil-bile acid conjugates were able to prevent photoaffinity labeling of bile acid binding proteins in rat hepatocytes by the photolabile [3H]7,7-azo derivative of taurocholic acid indicating their bile acid character. The chlorambucil-bile acid conjugate S 2577 was able to alkylate proteins demonstrating the drug character conserved in the hybrid-molecules. Liver perfusion experiments revealed a secretion profile of the chlorambucil-bile acid conjugate S 2576 into bile very similar to taurocholate compared to chlorambucil which is predominantly excreted by the kidney. 4-Nitrobenzo-2-oxa-1,3-diazol-beta-Ala-Phe-5-oxaproline-Gly- t-butylester (S 4404), a fluorescent peptide inhibitor of prolyl-4-hydroxylase, was not transported in intact form from portal blood into bile in contrast to its bile acid conjugate S 3744; about 25% of the peptide-bile acid conjugate S 3744 was secreted in intact form into bile within 40 min compared with less than 4% of the parent oxaprolylpeptide S 4404. In conclusion, these studies reveal that modified bile acid molecules can be used as "Trojan horses" to deliver a drug molecule specifically into the liver and the biliary system. This offers important pharmacological options for the development of liver-specific drugs.

Affinity Labels↗
PubMed1991

[Enteral anastomosis with the biofragmentable Valtrac ring. A prospective study].

In a prospective study, 150 enteral anastomoses using the new Valtrac biofragmentable anastomosis ring (BAR) are described. The manipulation involved was simple to learn and standardised intestinal anastomoses could be created at various bowel segments. No stenoses or postoperative bleeding occurred, the suture dehiscence rate was low. The use of these rings can be recommended to achieve a high level of standardisation for colon anastomoses and small bowel-colon anastomoses without restriction, whereas for other localisations the number of cases is too small to allow a final assessment to be made.

Anastomosis, Surgical↗
PubMed1990

Development and perspectives of experimental pancreas transplantation in the rat.

Whole organ pancreas transplantation in the rat was first described by Sun Lee in 1972. Since that time the basic technique has been modified in several ways and this model can now be used for a variety of experiments. Various techniques for transplantation and representative results of functional and immunological experiments are summarized.

Animals↗
PubMed1990

[Studies on the occurrence of texture types in calcium oxalate urinary stones].

A review of texture types of calcium oxalate calculi and a pattern of 4 basic texture types was presented. A method of texture classification as a part of the routine polarization microscopy urinary calculus analysis was developed. Thereby a representative material could presented on the distribution of texture types. A connection between pathological urinary parameters and the texture type was demonstrated.

Calcium Oxalate↗
PubMed1989

Molecular mechanics and X-ray crystal structure investigations on conformations of 11 beta substituted 4,9-dien-3-one steroids.

The influence of 11 beta-phenyl substitution upon 4,9-dien-3-one steroid-backbone conformations is calculated by means of the MM2p molecular mechanics scheme. In the case of steroids having a 13 beta configuration, the lowest strain energy is always evaluated for the conformational combination of rings A(inverted) B(normal) while, moreover, the 11 beta substitution increases the relative stability of the conformation A(normal) B(normal) compared to the nonsubstituted compound. Introduction of the 11 beta substituent causes some bowing of the energy-minimum structures in the A-ring region toward the beta side. For 13 alpha configurated steroids, the ring conformations A(inverted) B(normal) C(boat) and A(normal) B(inverted) C(twist/boat) are found to be energetically preferred. Quantitative description of different ring conformations using asymmetry and pseudorotational parameters as well as the comparison of molecular mechanics and available X-ray structure data give an impression of the conformational mobility. Whereas the effect of 11 beta substitution within a given ring conformation is limited, contributions to molecular flexibility can be found in the ability to adopt different basic conformations and in the occupation of near-minimum structures. An X-ray crystal structure analysis of a potential antiprogestational steroid has been performed, and the results are in good agreement with the calculated structure.

Crystallography↗
PubMed1989

[Value of ambulatory clinic-associated stoma therapy, analysis of expenses, success and cost effectiveness from the public economic viewpoint].

A pilot project providing ambulant, hospital-associated stoma care for the affected patients both in the hospital and at home has been in progress in the Kiel/Neumünster area since 1982. An evaluation of the stoma therapist's activities in 1988 and a survey in 1989 demonstrated that patients and family physicians are increasingly accepting the project. Besides a markedly better quality of life, a cautious cost analysis is proved that more than DM 200,000 can be saved annually by avoiding hospitalization and adapting the care system to the needs of the patients.

Ambulatory Care↗
PubMed1988

Urolithiasis associated with urogenital tuberculosis. Clinical and mineralogical aspects.

Of 628 patients with bacteriologically or histologically proven urogenital tuberculosis (UGT) treated from 1960 to 1985. 126 patients (20.1%) had additional urinary tract infection and 66 patients (10.5%) developed urolithiasis. In these 66 patients a simultaneous urinary tract infection occurred in 29 cases (43.9%). Twenty-eight calculi were analyzed by a combined crystal-optical and x-ray-diffraction method. A high incidence of struvite/carbonate apatite calculi (11/28) as well as of calcium phosphate calculi (6/28) was found. The texture of 15 calculi was investigated on thin sections by polarization microscopy and a high concentration of organic material was found in both calcium oxalate and struvite/carbonate apatite calculi probably due to the specific and nonspecific infection with deposition of cell and protein degradation products.

Crystallization↗
PubMed1988

Composition and structure of renal and ureteral calculi in patients under covalitin therapy.

We examined the composition and texture of 53 urinary calculi from patients receiving Covalitin therapy. The texture of the infection stones and of concrements containing mainly apatite showed no changes as compared to concrements from control groups receiving no such therapy. Calcium oxalate stones more often showed a whewellite texture (Type 2) and a less frequent occurrence of weddellite (Type 4) as compared to the control groups. Surface or marginal changes indicating a possible litholysis could not be shown.

Adult↗
PubMed1988

[Need for the differentiation of apatite and carbonate apatite].

With extensive analytical and clinical examinations it is shown that the proof of carbonate in apatite may allow no additional reference of an infection with urea-splitting bacteria. With certain analytical methods the presence of carbonate is demonstrable in each urinary calculus apatite phase. Carbonate-bearing apatite indeed is accompanied frequently with struvite, but may be occur also without an infection. Therefore, in the future it should be renounced on the differentiation of apatite and carbonate apatite in routine analyses of urinary calculi.

Apatites↗
PubMed1988

[Surgical possibilities in recurrence of colorectal carcinoma].

Locoregional recurrences occur in 10 to 15% of curatively operated rectal carcinomas. Technically conditioned relapses can be largely avoided by proper procedure, such as taking into consideration the localisation, staging, grading, safety zones and step-by-step procedure, e.g. "no-touch-isolation" technique, radicular approach and rinsing with cytocides. In this manner, locoregional relapses can be reduced to about 10%. Only technically conditioned relapses can be cured by surgery, but, as already stated above, these should be avoided by an appropriate technique. It is quite out of place to indulge in euphoria in respect of treating locoregional recurrences, as shown by long-term examination of actual survival rates; calculated survival rates are certainly inappropriate for spreading euphoria. Such locoregional relapses can be recognised relatively early and reoperated "curatively" only if aftercare follow-up is regular and intensive. It seems that endorectal sonography is of special diagnostic importance for the early detection of relapses while being a relatively simple method. It must be stated quite clearly that efficient preventive measures during the first operation will be much more effective than any efforts put into follow-up or aftercare. Every surgeon should therefore know that it is imperative to proceed subtly and carefully during the first operation so as to avoid any relapses due to faulty technique, the more so since all relapses have a poor prognosis even with so-called "curative" operations.

Colonic Neoplasms↗
PubMed1987

Quantitative structure-activity relationships of estrogenic steroids substituted at C14, C15.

The uterotropic activity of thirty 3-methoxyestradiol derivatives is measured and discussed on the basis of X-ray crystallographic results and quantitative structure-activity relationship analyses involving hydrophobic substituent constants pi and f as well as steric parameters Pr and L. In addition, estrogenicity is compared to data of interceptive activity and receptor binding affinity. All the biological data exhibit a high degree of intercorrelation. 17 beta-Hydroxysteroids having 14 alpha configuration reveal a generally better capability of high-affinity binding than those being 14 beta configurated. Between the uterotropic activity and the hydrophobicity of C14, C15 substituents, statistically significant correlations are found which suggest a close contact between the steroidal D-ring subsite and the receptor protein (e.g. for 14 alpha steroids: log UDD = -0.996 pi -0.392; n = 9, r = -0.943, s = 0.235, t = -7.5, alpha less than 0.001). The hydrophobic nature of both 14 alpha and 14 beta medium-sized substituents employed is shown by QSAR regressions to exert a stronger influence than steric effects. Furthermore, there are indications to additional hydrogen bonding and steric repulsion phenomena. As to the receptor-binding models discussed in the literature, it is concluded that the receptor protein has a high conformational flexibility to accommodate very different drug structures all having the common phenolic ring A. But, if an appropriate spacing of steroidal key atoms is recognized by the receptor and, consequently, the steroid-receptor complex is formed, the binding is complemented by hydrophobic interactions also in the D-ring region.

Animals↗