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Biomedical subjects

R Gerlach

Publications and source records attributed to R Gerlach.

At least 37 records · Page 2Linked to original sources
PubMed1996

Alloplastic replacement of the urinary bladder.

PURPOSE: The loss of a functioning bladder is nowadays mostly managed by replacement with gastrointestinal segments. Management of these urinary diversions is difficult and the long-term effects are unknown. We developed a silicone rubber prosthesis for alloplastic replacement of the urinary bladder and tested it in an animal experiment. MATERIAL AND METHODS: Two artificial bladders were implanted into subcutaneous pockets on each side of the anterior abdominal wall. Cystectomy was performed and each prosthesis was connected to one kidney. Distally, a Y-shaped tube sutured to the urethral stump joined the two bladder outlets. The whole system was successfully implanted in 5 sheep with a mean follow-up of 11.5 months (5-19 months). RESULTS: Adequate capacity, effective and reliable mechanical function and patent anastomoses to the renal pelvis and the urethra could be achieved. Blood chemistry and renal ultrasound were performed at regular intervals demonstrating neither morphological nor functional deterioration of the renal parenchyma. Histopathological examination in the end of the experiment confirmed the excellent clinical results. CONCLUSIONS: The positive outcome of these animal experiments suggests this system would be useful for human bladder substitution. Standardized industrial production of the prostheses will be needed prior to implantation in humans.

Animals↗
PubMed1991

Abstinence and acceptance? The problematic relationship between the German abstinence paradigm, low-threshold oriented drug work, and methadone.

It is hardly surprising that, compared to international standards, the Federal Republic of Germany holds an exceptional position in the area of drug policy. For decades, the majority of so-called 'drug experts' in Germany have deliberately ignored the findings of international research and, often despite their better knowledge, pursued a policy of misinformation which has remained unaffected by international research findings and standards of practice. This policy is essentially characterised by a rigid adherence to the abstinence paradigm.

Journal Article↗
PubMed1989

[A report on the status of the compilation of the registry paper: "cardiac pacemaker patients"].

On the basis of valid legal arrangement in the GDR to take radiomedical measures in heart pace-maker patients a standardized practice in irradiation planning and a standardized documentation are represented. With this a central registration and analysis of pace-maker patients in radiotherapy can be done to same aspects. The documentation comprehends measures of carrying out radiotherapy, which have been fixed within irradiation planning and risk estimation, and during therapy ascertained measuring values and observations for estimate of heart-circulation-situation of the patient and of the technical state of the pace-maker. The documentation is recommended for application in agreement with the Society for Radiology of the GDR. The Clinic and Policlinic for Radiology of the Martion Luther University Halle-Wittenberg is proposed for central registration and analysis.

Germany, East↗
PubMed1989

[A procedure for determining the dose distribution behind block shields. I. A computational method of determining the scatter distribution of a 60Co pencil beam].

The energy dose distribution of a photon pencil beam ray for photons with the primary energy of 1.25 MeV is determined using the Monte-Carlo-method. The found energy dose distribution underlies the calculation of spreading additive-air-ratio for extended 60Co-irradiation fields. The spreading additive-air-ratios, found by the model, show good correspondence with known values from literature.

Cobalt Radioisotopes↗
PubMed1989

[A procedure for determining the dose distribution behind block shields. II. Calculation of the dose distribution of 60Co radiation fields using a pencil beam model].

A model to calculate dose distribution behind block shielding is represented in a water equivalent medium for 60Co-radiation. The model is based on integration of spread dose distribution of a pencil beam over the total irradiation area. It is suitable to estimate dose distribution for an irregularly shaped irradiation field.

Cobalt Radioisotopes↗
PubMed1988

Correlation of in vitro immune defects with impaired gamma interferon response in human-immunodeficiency-virus-infected individuals.

65 patients belonging to known acquired-immune-deficiency-syndrome (AIDS) risk groups were tested for mitogen responsiveness to pokeweed mitogen, concanavalin A and phytohemagglutinin, percentages of peripheral blood CD4, CD8 and Leu7 lymphocyte subsets, serum neopterin levels, and gamma-interferon (gamma-IFN) concentrations in cell culture supernatants. Patients with clinical symptoms of human-immunodeficiency-virus infection showed reduced gamma-IFN production in vitro. The IFN concentrations were correlated significantly with mitogen-induced blastogenesis. High serum neopterin levels and decreased CD4/CD8 ratios were associated with diminished gamma-IFN levels. The percentage of Leu7 lymphocytes was increased in a group of patients with strikingly elevated gamma-IFN levels.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Gadolinium-DTPA-enhanced MR imaging of spinal neoplasms: preliminary investigation and comparison with unenhanced spin-echo and STIR sequences.

Unenhanced T1- and T2-weighted spin-echo, short inversion time inversion recovery (STIR), and gadolinium-DTPA (Gd-DTPA)-enhanced spin-echo and STIR imaging techniques were used in 20 patients as part of a multicenter study to assess the safety and efficacy of Gd-DTPA in spinal imaging. Five patients had normal MR scans. Of those with lesions, both Gd-DTPA-enhanced T1-weighted spin-echo and unenhanced STIR scans improved detection and evaluation of spinal tumors over conventional spin-echo methods, particularly T2-weighted spin echo, by providing higher tissue contrast in shorter imaging times. The Gd-DTPA-enhanced T1-weighted spin-echo scans were most helpful in evaluating intradural tumors, whereas STIR sequences were most effective for extradural tumors and bone metastases. In most cases, Gd-DTPA-enhanced T1-weighted spin-echo scans best delineated tumor margins, and the enhancement was helpful in suggesting a cellular or active nature of the lesions. In some cases, the enhancement resulted in a more homogeneous and thus less abnormal-appearing marrow in vertebrae involved by tumor; therefore, a precontrast T1-weighted spin-echo scan is necessary in all patients who are to be studied with Gd-DTPA. A combined approach that uses T1-weighted spin-echo, Gd-DTPA-enhanced T1-weighted spin-echo, and STIR images currently appears optimal for MR imaging of spinal neoplasms. T2-weighted spin-echo images add information only in occasional cases.

Bone Marrow↗
PubMed1988

Age-related changes in the beagle spine.

Age-related changes were evaluated in the spines of beagle dogs by radiology, histology, and mechanical testing. Thirty healthy beagle dogs were divided into five groups having mean ages of 2-14 years. Radiographs were taken of intact spines at the time of death and of defleshed spines at necropsy. Cervical, thoracic, and lumbar segments were tested in compression to calculate peak stress, peak strain, and elastic modulus. Adjacent spine segments were graded grossly for osteophyte development, and sections of the intervertebral discs were evaluated histologically. Histologic evidence of disc degeneration and changes in the mechanical properties of the intervertebral disc joint preceded radiographic changes. Changes in the mechanical properties of the disc space were probably a result of the disc degeneration rather than the spondylitic lesions.

Aging↗
PubMed1988

[Effect of a metal implant on the depth-dose curve for 6-20 MeV electron radiation].

The use of compression plates for osseous fixation in the inferior maxilla causes some problems for radiation therapy. The retrodiffusion of electrons from the metal implant induces an increased dose at the surface and especially at the metal border. A dose increase up to 40% is demonstrated for the central ray by means of thermoluminescent dosimetry. A dose decrease of up to 90% is measured for 6 MeV behind the inhomogeneity.

Bone Plates↗
PubMed1986

Comparison of short-latency trigeminal evoked potentials elicited by painful dental and gingival stimulation.

Painful stimulation of tooth pulp and of the maxillary gingiva was undertaken in 16 volunteers. Short-latency evoked potentials (15-50 msec) were recorded over 800 trials in each case at F3-P3 of F4-P4, and the resultant averaged wave forms were compared. The gingival wave was distinct in all subjects and could be averaged across subjects while the dental waves were either noise or very inconsistent over subjects. Averaging of the dental wave forms across subjects yielded an uninterpretable result. It was clear that dental evoked potentials could not be recorded at the sites. These findings could be explained by either or both of two hypotheses: dental afferents are predominantly small fiber, nociceptive end organs that conduct more slowly than soft tissue afferents whereas gingival stimulation activates both large and small fiber populations; and dental representation in somatosensory cortex is different and phylogenetically more primitive than that of neighboring soft tissue. Therefore, the location of the generator sites in cortex and the orientation of the dipole may be different for dental than for gingival wave forms.

Adult↗
PubMed1986

Uroflow measurements: their information yield in a long-term investigation of pre- and postoperative measurements.

This investigation shows that the reproducibility of uroflow measurements is limited. For their evaluation, anamnesis and the measured results have to be taken into account equally. We found correspondence of both parameters in about 50% only. One single measurement cannot provide precise information, as psychogenic, social, and other factors influence the measurement. In our study 3 subjects had their micturitions registered over a period of 2 months. We found an increase of the maximum flow with increasing bladder volume. The maximum bladder volume was reached in only four micturitions. Normal values range at about 25% of the maximum bladder volume. Analyzing the micturitions in regard to the time of day, we found maximum flow rates in the morning hours. Under clinical conditions the altered surroundings lead to a measured result which is psychogenically influenced and can only be balanced after repeated measurements. The curves of all 3 patients were equal and inconspicuous. In cases of infravesical obstruction, surgical success could be documented by comparing the pre- and postoperative uroflows. In all cases of neurogenic bladder disorders and unclear findings, uroflow measurements are, however, not sufficient, and diagnosis is accomplished by a complete urodynamic examination. In spite of certain restrictions, uroflowmetry yields a high level of information, besides being a simple, at any time reproducible, and noninvasive procedure. Due to its low costs, it should be the primary step in diagnostics in the clinic as well as for practitioners.

Adult↗
PubMed1986

[Thermoluminescent dosimetry studies on absorptive behavior of bones without and with metal implants].

The absorption and scattering in bones with and without metal implants (femur, humerus, ramus mandibulae) is investigated in an automatic water phantom by means of thermoluminescent dosimetry, a semi-conductor detector, and the ionization measuring chamber for different types of radiation. In case of Co-60 gamma radiation a strong back scattering is observed which increases the dose by up to 50% at the side of entry of radiation and reduces the dose at the other side by equally up to 50%. If ultrahard X-radiation of 9 MeV is used under the same conditions, there is considerably less back scattering and an increased forward scattering. Electron radiation of 10 MeV causes a considerable dose increase of up to 45% due to back scattering.

Bone and Bones↗