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Biomedical subjects

H Harms

Publications and source records attributed to H Harms.

At least 91 records · Page 5Linked to original sources
PubMed1985

Deoxyribonucleic acid homologies among 96 strains of ammonia-oxidizing bacteria.

DNA of 96 strains of the genera Nitrosomonas, Nitrosococcus, Nitrosospira, Nitrosolobus, and Nitrosovibrio was isolated and analysed spectrophotometrically. Percentages of guanine plus cytosine (G + C) content, genome sizes, and DNA-DNA homologies were determined. The results indicated the presence of eight Nitrosomonas species, three or four Nitrosococcus species, five Nitrosospira species, and two species of both Nitrosolobus and Nitrosovibrio. DNA homologies between strains of a separate species ranged from 56-100%. Average homologies between strains of different species were 33% in Nitrosococcus, 36% in Nitrosomonas, 37% in Nitrosolobus, 40% in Nitrosospira, and 42% in Nitrosovibrio. Average homologies between species of different genera were 33% and thus not significantly above the background value of 30% detected between DNA of ammonia-oxidizing bacteria and Escherichia coli. Genome sizes ranged from 1.90 - 2.74 X 10(9) dalton in Nitrosomonas, 2.09 - 2.37 X 10(9) dalton in Nitrosococcus, 1.87 - 2.15 X 10(9) dalton in Nitrosospira, 1.92 - 2.10 X 10(9) dalton in Nitrosolobus, and 1.91 - 2.15 X 10(9) dalton in Nitrosovibrio. Differences in genome sizes were in accordance with DNA homologies.

Ammonia↗
PubMed1985

Analysis for nonextractable (bound) residues of pentachlorophenol in plant cells using a cell wall fractionation procedure.

When plant cell cultures or aseptically grown wheat plants were treated with [14C]-pentachlorophenol (PCP) a major part of the label was found in a nonextractable or "bound" residue fraction. Soluble polar conjugates participated in the formation of these residues which were mainly located in the plant cell walls. By a sequential fractionation procedure using enzymatic and chemical methods, 90 to 95% of the bound radioactivity could be attributed to individual cell wall components. The 14C label from PCP was found mainly in hemicellulose, lignin, and protein fractions. Associations of hemicellulose with PCP derivatives with molecular weights up to 500,000 were purified to constant specific radioactivity. Hydrolysis of this fraction released 32% PCP and other unidentified products.

Adsorption↗
PubMed1984

Estimation of sampling errors in a high-resolution TV microscope image-processing system.

The basic postulate of this paper is that the commonly accepted sampling density of 2-4 pixels/micron in a high-resolution TV microscope system is too low to digitize exactly and analyze the complex cellular detail found in stained cell images. Depending on the specific microscope system, the required sampling density is much higher, lying between 15 and 30 pixels/micron. This sampling density is derived from the aliasing error, the resolution loss, and computational limitations. The mathematical and optical methods and equipment used to obtain these results are described in detail.

Analog-Digital Conversion↗
PubMed1984

Comparison of digital focus criteria for a TV microscope system.

Existing focusing methods, such as standard deviation of gray values, gradients, information content of the image and the lateral inhibition function, were compared, and a new combination criterion was developed. This combined method consists of using the standard deviation of the image for coarse focusing followed by a modified form of the lateral inhibition for the fine focus. The lateral inhibitor model of the eye is a recursive filter that can be simplified to a nonrecursive filtering algorithm, as postulated by Rechenberg. The reported focus method operates over a focusing range (z-axis) of +/- 300 micron and is accurate within +/- 0.1 micron in the transmission, dark-field, and phase contrast microscope.

Analog-Digital Conversion↗
PubMed1984

Application of a high-resolution TV-microscope system to estimate the sequence of centromere separation in muntjak chromosomes.

The sequence of centromere separation in muntjak fibroblasts was studied using a high-resolution TV-microscope system. Computer programs that identify the chromosomes as well as measure the centromere separation are described. Important prerequisites for this study are the high sampling rate and the digital processing of the two images from the red and green channel of a color TV-camera. The study demonstrates that the centromeres do not separate in a random sequence and that the separation sequence is not solely controlled by the amount of constitutive heterochromatin in the chromosomes.

Animals↗
PubMed1984

[Evaluation of surgical methods for chronic glaucoma].

In the light of personal experience, the present author repeats the call for generally applicable rules for classifying findings and criteria for evaluating them; this demand was originally made by Leydhecker . Taking a comparison of various surgical procedures for chronic glaucoma as an example, the need for such rules and criteria is illustrated in detail, and concrete proposals for formulating them are made.

Corneal Opacity↗
PubMed1984

[Ophthalmological experiences with automobile drivers with inadequate vision].

A total of 369 ophthalmological practices were asked to report the number of patients seen within one test week who drove their cars but did not satisfy minimum legal requirements for diurnal visual acuity applicable for applicants for a West German Class 3 driver's license. There were 471 such patients. From this number it can be calculated that approximately 570 000 individuals (+/- 9%) drive cars in the Federal Republic of Germany with inadequate visual acuity. An analysis of the questionnaire produced the following results: Fifty percent of these patients are less than 62 years of age. The main cause of inadequate visual acuity is age. In younger drivers refractive errors were the prime cause and in most cases correction with glasses was possible. In older drivers the loss of acuity was mainly due to opacities of the lens which for the most part could not be corrected by spectacles. Two-thirds of the drivers with inadequate visual acuity consider their vision to be "sufficient" or "good" for driving; younger drivers are more self-critical than older ones. Only 31% of these drivers stopped driving at night of their own accord. As many as two-thirds of the drivers who consider their acuity to be "insufficient" drive their cars during darkness. The authors show that the findings in patients suffering from severe loss of visual acuity must in principle also be valid for patients with minor visual impairments who still meet the minimum legal requirements. This agrees well with published statistical investigations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Computer analysis of chromatin arrangement and nuclear texture in follicular thyroid tumours.

The differentiation of the thyroid glands follicular neoplasias into adenomas and carcinomas is currently done using the histological criteria recommended by WHO. This pilot study of 10 human follicular carcinomas and 10 folliculars adenomas demonstrates the possibility of a cytological classification using digital picture processing of high resolution cell images. Giemsa stained paraplast sections were scanned with a Colour-TV-camera, different channels were used with respect to staining and analyzing methods and computed with an image processing system. The computer aided cytophotometric methods detected significant differences in the chromatin arrangement and structure.

Adenocarcinoma↗
PubMed1983

Evidence for non-random sequence of centromere separation in muntjak chromosomes by high resolution TV-microscopy.

The sequence of separation of sister centromeres in the chromosomes of the muntjak was analysed using a high resolution TV-microscope-system. Computer programs which permit the identification of the individual chromosome pairs and the measurement of the distances between the sister centromeres are described. The study demonstrates that the centromeres do not separate in a random sequence. It could be shown that the amount of pericentromeric heterochromatin participates in the control of centromere separation; however, other factors must also be involved. The significance of the asynchronous division of centromeres in the origin of aneusomic cells in mammals is discussed.

Animals↗
PubMed1982

Comparative colorimetry in cytophotometric measurements of azure B-eosin Y-stained and Giemsa-stained blood cell smears.

The advantages of the Commission Internationale de l'Eclairage (CIE) color measurements and the use of the standardizable purified azure B-eosin Y stain, as compared to the commonly used commercial Giemsa stain, were studied. Color measurement and analysis according to the CIE standards allows the comparison of color measurements from different slides stained by either the same or different procedures. Moreover, measurements from different cytophotometric systems can be compared. The results can also be directly correlated with human visual subjective color estimates and thus used to quantify the human observations. The color information in the air-dried cell specimens, which differs from the color characteristics of the components of the staining solution, was measured and analyzed.

Azure Stains↗
PubMed1982

[Simultaneous cutaneous and choroidal melanomas (author's transl)].

In patients with both cutaneous and ocular malignant melanomas it is most important for prognosis and therapy to know whether they are distinct tumors developing simultaneously or whether one of the tumors represents a metastasis of the other. In the case reported here, two distinct tumours developed independently from pre-existing benign melanocytic lesions. Cases of this type, which are extremely rare, are discussed as well as the differential diagnosis between primary choroidal malignant melanoma and choroidal metastases from melanomas of different origin.

Choroid Neoplasms↗
PubMed1981

Cytophotometric analysis of lytically and persistently infected tissue culture cells with measles virus.

Lytically and persistently infected VERO and LUB cells were cytophotometrically characterized with the aid of computer analysis. Images scanned at 260 and 280 nm were processed by computer algorithms. With this approach, infected cells could be segmented and differentiated from uninfected cells. Lytically and persistently infected cells could be distinguished by distinct differences in nuclear and cytoplasmic optical densities. These findings are supported by biologic data based on the analysis of virus-specific proteins and nucleic acids. The applied computer aided cytophotometry provides a new approach in the study of virus cell interaction.

Animals↗
PubMed1981

Characterization of coronavirus-infected tissue cultures by computer-aided cytophotometry.

Coronavirus-infected cells were cytophotometrically measured and analyze during a replication cycle. Distinct cytoplasmic differences were observed in images scanned at 260 and 280 nm; these differences could be attributed to specific virologic changes using virologic tests. The application of computer-aided cytophotometry may prove to be a valuable approach in the analysis of infected cells.

Animals↗
PubMed1981

Computer-aided image analysis for the differentiation of mononuclear cells in peripheral blood smears from leukemic patients.

Different leukemias originating from the lymphatic system and from the myeloid tissue of the bone marrow were selected to develop and test algorithms to cytophotometrically define leukemic cells. Two of these cases were of low-grade, one of intermediate-grade and one of high-grade malignancy. The malignant cell types of each leukemic form could be identified and characterized by assessing the chromatin texture of the nucleus in the leukemic cells. With this method, normal peripheral white blood cells could be differentiated from leukemic ones. The results correlate directly with established hematologic parameters as they are described in the literature. The investigation demonstrated the usefulness of computer methods in the differentiation of closely related cell structures.

Blood Cells↗
PubMed1981

[Investigations on the conditions of scanning on cell images by means of a microscope-TV-system (author's transl)].

One common method for determining the spatial resolution of a TV-microscope scanning system is to measure a sharp edge, differentiate the digitized response and calculate the Modulation Transfer Function (MTF) using the Fourier transformation. The MTF provides a measure of the information content of a digitized picture as well as the resolving power of the whole system. Knowledge of this measure is prerequisite for understanding the capabilities and limitations of computer aided techniques for analyzing cellular structures as observed in the light microscope. The information content of a digitized image depends on the MTF of the whole measurement system. Results from this study show that the information content increases almost linearly up to a sampling rate of approximately 20 pixel/micrometer and saturates at 30--35 pixel/micrometer. The MTF and the signal/noise ratio is effected by averaged multiscans. The aliasing error is presented as a function of the sampling rate for the described system. The need for this resolving power of the cell image analysis system is demonstrated by an example in the haematology. Small granules with a diameter of 0.2 to 1.0 micrometer must be registered with a high sampling rate up to 30 pixel/micrometer. The analysis of the small granules is basic for automated detection and differentiation of many leukemic conditions.

Computers↗
PubMed1980

Relationship of ploidy and chromatin condensation in the rat liver, moreover a comparison of the nuclear texture in sections and touch preparations.

In touch preparations and tissue sections from normal rat hepatocytes and alpha-amanitine- and actinomycin D-poisoned liver cells the extent of chromatin condensation relatively to the degree of ploidy and the chromatin distribution were studied by means of computer aided cytophotometry. It could be found, that the relationship of the condensed and decondensed chromatin is independent of the degree of ploidy and first of all dependent upon the intoxicant. Therefore, the extent of chromatin condensation can be utilized also in sections as additional parameter for automated cell screening.

Amanitins↗