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Biomedical subjects

W Rohde

Publications and source records attributed to W Rohde.

At least 163 records · Page 9Linked to original sources
PubMed1981

Detection of complementary RNA intermediates of viroid replication by Northern blot hybridization.

Molecular hybridization by the Northern blot technique in combination with 125I-labeled PSTV (+) RNA and 32P-labeled PSTV cDNA as probes has been applied to detect viroid-specific sequences in healthy and viroid(PSTV)-infected tomato plants. Conditions are described which allow differentiation of (+) and (-) viroid sequences on the basis of the different thermostabilities of the corresponding hybrid molecules. By this experimental approach, it is documented that no viroid-specific DNA sequences can be detected and that viroid replication proceeds via complementary RNA intermediates. Out of the seven (-) RNA species found, six are apparently larger than the circular viroid (+) RNA and one is about the same size as the linear (+) RNA molecule.

Base Sequence↗
PubMed1981

Specifically primed synthesis in vitro of full-length DNA complementary to potato-spindle-tuber viroid.

Potato spindle tuber viroid (PSTV) RNA is transcribed in vitro by reverse transcriptase into complementary DNA in the presence of synthetic oligodeoxyribonucleotides as primers. In the case of priming with the pentadecadeoxyribonucleotide d(T-T-C-T-T-T-T-T-T-C-T-T-T-T-C) complementary to PSTV RNA from nucleotides 49 to 63, specificity of transcription initiation allows rapid sequencing of part of the viroid genome using chain-terminating dideoxyribonucleoside triphosphates. The DNA transcripts obtained represent distinct molecular species with the largest product being a full-length copy of the viroid RNA template. Molecular hybridization with 32P-labeled complementary DNA detects sequence homologies among different viroid species.

Base Composition↗
PubMed1981

Further studies on the hypothalamic desensitization to estrogen in immature female rats: evidence for a possible role in the control of puberty.

Immature and puberal female rats were ovariectomized and implanted with estradiol benzoate and cholesterol at the ratios of 1:120 or 1:240 into the hypothalamic ventromedial-arcuate region at 26 or 32 days of age, or on the day of the first vaginal estrus. Evaluation of the serum LH and FSH concentrations on the 2nd day after implantation revealed that the gonadotropin-inhibiting effect of the locally administered estrogen decreased between days 26 and 32 and showed a further distinct decline at the time of puberty. In a second experiment, uterine weight and serum LH and FSH levels were monitored in untreated immature female rats at daily intervals from 25 to 36 days of age. Relatively high values for both gonadotropins were recorded between days 25 and 28. Accelerated uterine growth around day 30 indicating increasing estrogen secretion was associated with a sudden decrease of LH and FSH concentration in the blood. After that, LH and, to a less degree FSH levels began to rise in spite of further weight gain of the uterus. The results suggest that the hypothalamic sensitivity to the gonadotropin-inhibiting effect of estrogen declines during the last week before the onset of puberty. Together with other findings they furthermore indicate that this desensitization process may be involved in the neurohormonal control of puberty in female rats.

Animals↗
PubMed1981

Failure to demonstrate a significant influence of ovarian maturity on the onset of puberty in female rats.

Ovaries of 23- and 35-day-old rats were transplanted under the kidney capsules of 31- and 23-day-old females, respectively. The recipient rats were ovariectomized on the fourth day after transplantation, and the onset of puberty was recorded. Neither the age and body weight at vaginal opening and first ovulation nor the length of the first ovarian cycle differed significantly between the experimental rats and sham-transplanted or untreated controls. Estimation of the serum FSH an LH concentrations before and after ovariectomy provided no evidence that different gonadotropic responses had masked puberty-delaying or puberty-advancing effects of the implanted immature and prepuberal ovaries, respectively. The results suggest that the developmental stage of the ovaries is not a decisive factor in the control of the onset of female puberty.

Animals↗
PubMed1981

Comparison of four mathematical models for the calculation of radioimmunoassay data of LH, FSH, and GH.

Weighted linear logit-log regression, point-to-point logit-log interpolation, smoothing spline approximation and the four-parameter logistic function calculated by non-linear regression have been compared. The data for comparison have been obtained from two different pool-sera for each of the LH-, FSH- and GH-RIA and from the basal serum LH values of two populations of children. The Wilcoxon matched pairs signed rank test was used for comparison: For GH there is no significant difference between all methods, for FSH the weighted linear logit-log regression and spline approximation appeared to be equivalent, but for LH no unequivocal assertion can be made. There is no significant difference between the mathematical models for determination of hormone concentration within one assay-run of a population as exemplified for LH. In addition, pool-sera data were subjected to an analysis of variance and the comparison of the results revealed that the different models did not lead to different statements about assay performance. The point-to-point logit-log interpolation is proposed as most simple curvilinear approximation for assays which cannot be linearized by logit-log transformation.

Adolescent↗
PubMed1981

Enzyme immunoassay and radioimmunoassay for plasma renin activity. I. Comparison of the methods.

Sensitive and specific enzyme and radioimmunoassays have been developed for the determination of renin activity. These methods are based upon the determination of angiotensin I generated by endogenous renin and angiotensinogen. An antibody trapping technique was used, while the addition of chemicals to the plasma, used until now as inhibitors for converting enzyme and angiotensinases, was eliminated. The angiotensin I was labelled with horseradish peroxidase for enzyme immunoassay and with iodine-125 for radioimmunoassay. Antibody bound and free labelled antigen were separated from each other by a second antibody polyethyleneglycol method (enzyme immunoassay) and by charcoal-dextran adsorption (radioimmunoassay). The values of renin activity in human plasma determined by enzyme immunoassay correlated well with those obtained by radioimmunoassay.

Adult↗
PubMed1981

[Comparison of radioimmunological methods for the determination of basal serum TSH levels].

In our experience the routine measurement of basic serum TSH levels is of great value in diagnosis and therapy control of thyroid diseases. However, the reliable differentiation of normal and suppressed TSH levels requires a very sensitive and accurate radioimmunoassay. Based on a commercially available TSH-RIA-kit it is demonstrated that the prolongation of several incubation-times as well as the use of thoroughly selected, pooled "TSH-poor" human sera for establishing the standard dilutions result in a pronounced improvement of the RIA. Further assay improvement is achieved by a higher dilution of the first antibody and by reduction of the added tracer-amount, provided that the TSH used for labelling is of high quality, that the labelling-procedure is carried out under mild conditions and that the 125-I-TSH is prepared carefully by high-resolution-gel chromatography. The resulting RIA can be characterized by a between-assay coefficient of variation: 5-10% in the so-called normal range (0.8-5.0 mU TSH/l), by a lower detection-limit: 0.2 mU TSH/l and by a 50%-intercept: 2.0 mU TSH/l.

Humans↗
PubMed1981

A simple strategy convenient for processing of RIA data and quality control in the laboratory on a desk-top-calculator.

The experience with a computer strategy of mathematically simple models for the description of standard curves and continuous quality control calculations with outlier diagnostics for the processing of RIA data in laboratory is discussed. To get over the difficulties associated with the approximation of the nonlinear shape of standard curves, the combination of weighted iterative linear logit-log regression and point-to point logit-log interpolation is proposed. Monitoring of assay performance is based on three large pool sera determined in triplicates. The control data are checked by statistical tests for the rejection of single outlying observations, followed by calculation of objective criteria on within- and between-assay precision by means of analysis of variance for a one-way classification on the basis of which actual triplicates and whole assays can be assessed. Combined with quality control chart technique and the construction of a rough three-point precision profile the empirical knowledge of an experienced assayist should be included in the RIA interpretation as can be easily organized by way of a dialogue-program on a desk-top-calculator.

Computers↗
PubMed1980

On the origin of the gene coding for an influenze A virus nucleocapsid protein.

The gene coding for the nucleocapsid protein NP of the influenza A virus recombinant strain 413 1,1 was characterized biochemically by molecular hybridization and fingerprint analysis. The data presented suggest that this NP gene has evolved by intracistronic recombination between NP genes of virus N and the fowl plague virus temperature-sensitive mutants ts 19.

Capsid↗
PubMed1980

Evidence for direct central nervous inhibition of LH secretion during sexual maturation of female rats.

Intact and ovariectomized female rats were bilaterally lesioned in the anterior part of the medial amygdaloid nucleus (AMN) at 15, 21 or 26 days of age. The onset of puberty and the LH concentration in the peripheral serum on the third day after lesioning, respectively, were recorded. Damage to the AMN on day 15 induced a significant delay of vaginal opening and the first puberal ovulation and suppressed completely the castration-induced increase of LH secretion. In contrast, females lesioned on day 21 showed true precocious puberty and a significant elevation of the LH level as compared to the ovariectomized controls. The LH-inhibiting effect of s.c. administered estradiol benzoate (0.05 micrograms/100 g/day) was not diminished by lesions produced at this age. Neither the onset of puberty nor the LH concentration were influenced by lesioning of the AMN on day 26. Estimation of the LH concentration in untreated female rats revealed a distinct decline between 19 and 23 days of age followed by a significant increase between days 24 and 26. The findings indicate a transient LH-inhibiting activity of the medial amygdala in three-week-old female rats that is not related to the negative estrogen feedback. In other species, too, a temporary inhibitory action of the central nervous system may play a significant role in the prepuberal control of gonadotropin secretion.

Aging↗
PubMed1979

Characterization of virus-like particles produced by an influenza A virus.

The influenza strain 413 1,1 segregated as a stable recombinant during passage of the isolate 19/N which was obtained after double infection of chick embryo fibroblasts by virus N and the fowl plague virus (FPV) mutant ts 19. Its gene constellation was determined by molecular hybridization. Upon infection of chick embryo cells by this recombinant strain, two particle populations of high (H) and low (L) buoyant densities were produced. By biological and biochemical parameters, the H-population (delta = 1.22 g/cm3) cannot be distinguished from standard infectious influenza virus. In contrast, the noninfectious L-particles (delta = 1.14 g/cm3) lack all virus-specific glycoproteins (HA, NA) as well as the matrix protein M and are visualized by electron microscopy as spikeless particles. Significant changes in the quantitative composition of the phospholipid bilayer are evident as compared to the H-particles. In addition to the previously characterized eight genes both populations contain a variety of smaller RNA fragments which hybridize with complementary RNA and presumably represent degradation products of full-length genes.

Animals↗
PubMed1979

Binding of N-methyl isatin beta-thiosemicarbazone-copper complexes to proteins and nucleic acids.

N-Methyl isatin beta-thiosemicarbazone-copper complexes interact with nucleic acids and proteins as shown by ultraviolet (UV) and visible spectroscopy and Sephadex exclusion chromatography. The Cu++ ions are most effective; Co++ ions have less albeit significant activity. Chelating agents, such as Tris and histidine, high NaCl concentration, and dimethyl sulfoxide reduce the binding of the drug-metal complex. The binding constant of the drug-copper complex to calf-thymus DNA was calculated to range between 6.9 x 10(4) and 2.7 x 10(5) M-1.

Chelating Agents↗
PubMed1979

[Initial experience with ethinyl estradiol sulfonate (J 96) in the therapy of prostate carcinoma].

Ethinylestradiol sulphate (J 96) is a depot estrogen which in a dosage of 2 mg per week has clearly antigonadotropic effects and evokes a suppression of the free testosterone in bilaterally orchiectomized patients with carcinoma of the prostate. The good compatibility in oral application and the possibility for the controlled intake recommend its use for the long-term therapy of the carcinoma of the prostate.

Carcinoma↗
PubMed1979

Experience with a radioimmunoassay of luteinizing hormone-releasing hormone (LH-RH) in biological material of man.

A radioimmunoassay of LH-RH with a sensitivity of 7.8 pg/ml is described. Labelling and purification techniques, methods for extraction of LH-RH and separation techniques of bound and free labelled hormone are compared. Determination of LH-RH levels in serum after administration of synthetic LH-RH by different routes and measurements of endogenous LH-RH levels in serum of normal subjects and patients with different endocrine diseases as well as in cerebrospinal fluid of normal men are performed. The measurement of exogenously administered LH-RH in serum reflects the disappearance of synthetic LH-RH from peripheral circulation in dependence upon the kind of administration route. The level of endogenous LH-RH was found to be under the limit of the assay in all samples of cerebrospinal fluid and of serum of normal male subjects. The results obtained in the patient groups show that the radioimmunological estimation of endogenous LH-RH in peripheral body fluids does not reflect the hypophysiotrophic role of this hypothalamic peptide.

Adolescent↗