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Biomedical subjects

G Ludwig

Publications and source records attributed to G Ludwig.

At least 19 recordsLinked to original sources
PubMed1992

The influence of spatial polarization distribution on spot poled PVDF membrane hydrophone performance.

The influence of spatial polarization distribution on spot poled PVDF membrane hydrophone performance was calculated and then experimentally verified using a one-dimensional model based on acoustic wave propagation through a layered medium. It is shown that the sensitivity of the hydrophone is markedly dependent on the spatial polarization distribution. It is also shown that there can be a significant difference between the voltage sensitivities measured in the same hydrophone probe depending on which electrode is actually facing the acoustic source. The measurements carried out in the frequency range 1-20 MHz indicate that this difference, while negligible below 2 MHz, may exceed 1.6 dB at higher frequencies. The model developed can also be used to determine the "effective" piezoelectric constant d33 of the PVDF material as a continuous function of frequency. Moreover, the model predicts the existence of a negative slope in the frequency response of the spot poled membrane hydrophone. The experimental confirmation of this prediction underscores the importance of using swept frequency methods during calibration measurements.

Electricity↗
PubMed1991

Evaluation of conservative therapeutic approaches to Peyronie's disease (fibrotic induration of the penis).

Conservative approaches to the treatment of Peyronie's disease are limited. Irradiation is of no value because the efficacy has not been proven and it may cause tissue damage requiring or hampering subsequent surgery. Vitamin-E therapy is ineffective and is also not recommended. p-Aminobenzoate treatment has to be discontinued because of intolerance in one third of the cases, and the response rate is not superior to that of a placebo. Local infiltration of the plaques with orgotein (Peroxinorm) results in a marked improvement in just under 50% of cases and is therefore a justified approach in the early stages of the disease. It is, however, unclear how great the placebo effect and the spontaneous remission rate are. Surgery suited to the individual case must be considered in patients with severe angulation of the penis rendering introitus impossible, calcium deposits, or worsening of the condition despite injections of Peroxinorm.

4-Aminobenzoic Acid↗
PubMed1990

Androgen dependence and tissue specificity of renin messenger RNA expression in mice.

Testosterone, a steroid hormone which increases blood pressure by hitherto unknown mechanisms, is known to induce renin synthesis in the submandibular gland (SMG) of mice. Since renin as well as all other components of the renin-angiotensin system are present in organs important for cardiovascular control, e.g. the kidney, heart, adrenal gland and brain, it is of interest to study the effect of testosterone on renin gene expression in these organs. Renin messenger (m) RNA concentrations were measured by a solution hybridization assay using a 32P-labeled mouse SMG renin complementary (c) RNA as a radioactive probe (detection limit: 1 pg renin mRNA). Measurements were performed after 2 h and after 2, 7, 14 and 21 days of dihydrotestosterone (DHT) treatment in female NMRI mice. Renin mRNA concentration (values are expressed as pg renin mRNA/ micrograms total RNA) in the SMG was significantly increased after 7 days (108 +/- 22 in controls versus 630 +/- 101 in DHT-treated mice), after 14 days (83 +/- 15 in controls versus 743 +/- 83 in DHT-treated mice) and after 21 days (107 +/- 30 in controls versus 579 +/- 76 in DHT-treated mice), but did not reach levels found in untreated male NMRI mice (1021 +/- 84). In the kidney, a decrease was observed within 21 days, from 43 +/- 4 and 40 +/- 4 to 29 +/- 2 and 22 +/- 1.7 pg/micrograms in controls and DHT-treated groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1979

Apurinic acid endonuclease activity from mouse epidermal cells.

An endonuclease activity making single-strand breaks into depurinated and alkylated DNA has been purified 500-fold from carcinogen-transformed mouse epidermal cells. The enzyme was active only at apurinic/apyrimidinic sites, regardless of whether they were produced by heating at an acidic pH or by alkylation with the ultimate carcinogen MeSO2OMe. The enzyme did not act on native DNA nor on ultraviolet-induced pyrimidine-dimers nor on steric distortions caused by modification of DNA with the carcinogen (Ac)2ONFln. The enzyme was active in the presence of 1 mM EDTA; however, at pH 7.4 optimal conditions were: 6mM MgCl2 and 40--120 mM KCl or 10--40 mM potassium phosphate. The enzyme eluted from hydroxyapatite, phosphocellulose and heparin-cellulose between 100--250 mM potassium phosphate but did not bind to DEAE-cellulose. Using four chromatographic steps the endonuclease was obtained free of exonuclease, demethylase and DNA glycosylase activity specific for DNA bases methylated with MeSO2OMe or MeNOUr. The molecular weight was 31 000 +/- 3000 as calculated from the diffusion coefficient (8.2 x 10-7 cm2/s) and the sedimentation value (2.7 S).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1979

[Antibiotic therapy after prostatectomy? (author's transl)].

This prospective study shows, that, neither an antibiotic prophylaxis of abacteriuric patients nor postoperative treatment of an asymptomatic urinary tract infection after transurethral prostatectomy have a significant influence on the clinical complications or the microbiologic results. After suprapubic prostatectomy complications in the control group were not significantly more frequent than in the group with antimicrobial prophylaxis. Patients with asymptomatic urinary tract infections before suprapubic prostatectomy had better clinical results, if they were treated with antibiotics as compared to a control group, although the difference control group was not significant. The correlation between consumption of antibiotics and development of resistant in pathogenic organisms forced us to use a more critical approach in the use of antimicrobial prophylaxis and therapy. This study shows clearly, that aseptic operations do not need an antibiotic protection and that faulty of asepsis cannot be corrected by antibiotics.

Anti-Bacterial Agents↗
PubMed1979

[Late changes of the testicular tissue in experimental torsion of the spermatic cord (author's transl)].

In three experimental groups and a control group unilateral or bilateral torsion of the testicle were carried out in 195 mature rats. The testicles were retorted at various intervals up to 24 hours. Four weeks and three months following the torsion the retorted as well as the contralateral normal testicles were examined morphologically and histologically. A total testicular torsion is fully reversable after one hour in all cases and after 2 hours in 40% of the cases. The Sertoli cells are destroyed after 6 hours and the Leydig cells after 10 hours. The time causing irreversable tissue damage therefore appears to be shorter than generally assumed, and the germinative epithelium is reacting faster than the testosterone producing Leydig cells. No changes were noted in the contralateral normal testis.

Animals↗
PubMed1978

[Hemorrhagic calico papillitis. Clinical picture of pyelitic hematuria with special reference to cytodiagnostic problems].

A case is reported of hemorrhagic calico papillitis showing unilateral hematuria. There was no evidence of pathological changes either in i.v.P. or in retrograde pyelogram, angiogram, or angiogram with epinephrine. Large were found in the urine papillary cellgroups, suspicious for papilloma of the renal pelvis. It is pointed on the difficulty of differentiating such cellgroups from real papillomas of the renal pelvis. Possible are discussed causes of this mucosa proliferation and dysplasia. If there is found the following trias: unilateral hematuria, pseudopapillomatous cellgroups in urine, missing pathological changes in urological X-ray examinations (or only minimal blurs at the fornices) the diagnosis of calico papillitis has to be considered carefully.

Adult↗
PubMed1977

[Spontaneous regression of pulmonary metastases from hypernephroma: report of a case and review of literature (author's transl)].

Until now there are reported some 60 cases of spontaneous regression of pulmonary metastases from hypernephroma. An own case is shown up: There was taken nephrectomy and following local radiation of hypernephroma in a 59 years old male patient in spite of pulmonary metastases. 8 months after operation these metastases had disappeared. There was no indication for any metastases in radiologic and scintigrafic examination even 4 years following up neither in lungs nor in other organ. The causality of hormones and autoantibodies - perphaps additionally stimulated by wound infection-in the phenomenon of spontaneous regression of pulmonary hypernephroma-metastases is discussed. According to the literature and to experience in an own case nephrectomy and following local radiation - possibly additional progesterone-therapy for one year - is recommended in hypernephroma even in case of pulmonary metastases.

Adenocarcinoma↗
PubMed1977

[Epididymitis].

Explore the source record for details and available documents.

Adult↗
PubMed1977

[Epididymitis and fertility. Treatment results in acute unspecific epididymitis].

Spermiograms of 46 patients were examined 8 days, 4 weeks, 3 months, 6 months and 1 year after acute unilateral non-specific epididymitis. The treatment consisted in 24 cases besides antibiotic treatment with doxycycline in local infiltrations of the spermatic cord with 1% Scandicain solution. Primarily there was found an inhibiting effect on spermatogenesis. In more than 2/3 of the cases a varying oligoasthenospermia was shown 8 days after beginning of the infection. In the further course this disturbance of fertility improves; if local infiltration of the spermatic cord with 1% Scandicain solution is performed, the improvement is more evident. Still, there remain about 20% of the cases in which the fertility disturbance is so severe, that sterility results. One year after the beginning of the infection spermagglutinating antibodies could be shown only in 1 case. The seminal fluid fructose was controlled over 1 year following the beginning of infection and found to be normal in all cases.

Acute Disease↗
PubMed1976

[The significance of the columar structure of the stratum corneum for the effect of light on the skin].

Autologous full thickness skin autografts were carried out on 60 male guineapigs in such a way that the hair roots were destroyed. The light sensitivity of the skin towards UV B was then tested on the hairless skin by means of the Xenon lamp and the corresponding filter. Exploratory excisions were taken from another area of the graft and used to demonstrate the structure of the stratum corneum according to the method of Christophers. It could be shown that light erythema developed significantly less than when the columnar structure of the stratum cornuem was well developed.

Animals↗