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Biomedical subjects

H Harms

Publications and source records attributed to H Harms.

At least 73 records · Page 4Linked to original sources
PubMed1990

Metabolism of Dibenzofuran by Pseudomonas sp. Strain HH69 and the Mixed Culture HH27.

A Pseudomonas sp. strain, HH69, and a mixed culture, designated HH27, were isolated by selective enrichment from soil samples. The pure strain and the mixed culture grew aerobically on dibenzofuran as the sole source of carbon and energy. Degradation proceeded via salicylic acid which was branched into the gentisic acid and the catechol pathway. Both salicylic acid and gentisic acid accumulated in the culture medium of strain HH69. The acids were slowly metabolized after growth ceased. The enzymes responsible for their metabolism showed relatively low activities. Besides the above-mentioned acids, 2-hydroxyacetophenone, benzopyran-4-one (chromone), several 2-substituted chroman-4-ones, and traces of the four isomeric monohydroxydiben-zofurans were identified in the culture medium. 2,2',3-Trihydroxybiphenyl was isolated from the medium of a dibenzofuran-converting mutant derived from parent strain HH69, which can no longer grow on dibenzofuran. This gives evidence for a novel type of dioxygenases responsible for the attack on the biarylether structure of the dibenzofuran molecule. A meta-fission mechanism for cleavage of the dihydroxylated aromatic nucleus of 2,2',3-trihydroxybiphenyl is suggested as the next enzymatic step in the degradative pathway.

Journal Article↗
PubMed1990

Transformation of Dibenzo-p-Dioxin by Pseudomonas sp. Strain HH69.

Dibenzo-p-dioxin was oxidatively cleaved by the dibenzofuran-degrading bacterium Pseudomonas sp. strain HH69 to produce minor amounts of 1-hydroxydibenzo-p-dioxin and catechol, while a 2-phenoxy derivative of muconic acid was formed as the major product. Upon acidic methylation, the latter yielded the dimethylester of cis, trans-2-(2-hydroxyphenoxy)-muconic acid.

Journal Article↗
PubMed1990

[Pattern analytic investigations of blast cells in myelodysplastic syndrome and secondary acute myeloid leukemia].

Blast-cells in Romanowsky-Giemsa stained bone marrow smears from 14 cases of primary myelodysplastic syndrome which consequently developed an acute myeloid leukemia and 28 cases of primary acute myeloid leukemia were analysed by a computer aided high resolution pattern recognition system. As control we used blast-cells from reactive affected bone marrow. Whereas blast-cell types in MDS and secondary AML showed overlapping features and a heterogenous distribution we could distinguish blasts in primary AML compared to "reactive" blasts. Opposite to this blasts in secondary AML showed no different pattern compared to "reactive" blast.

Acute Disease↗
PubMed1990

[Centroblast morphology: a morphometric evaluation by means of computer-aided image analysis].

In cytologic preparations, cell images from 30 cases of high grade malignant Non-Hodgkin's lymphoma (NHL) and 10 cases of tonsillitis have been analysed using a colour TV microscope system, high resolution scanning and image processing. Multivariate analysis of 30 cell features allowed satisfying recognition and discrimination of centrocytes, centrocyte-like centroblasts, ordinary centroblasts and multilobated centroblasts. In addition, according to their image analytical data, the ordinary centroblasts from NHL formed 5, and those from tonsillitis 4 well defined, homogeneous clusters. Even at simultaneous analysis, there was an essential overlap only between centroblast subtype 3 from NHL and subtype 9 from tonsillitis, but reliable discrimination of all the rest.

Computers↗
PubMed1990

Automated recognition of cell images in high grade malignant lymphoma and reactive follicular hyperplasia.

In the past, the comparison of results of studies on malignant lymphomas has been biased by the use of different classifications of the diseases and to an even greater extent by subjective interpretation in the classification of the tumour cells. To overcome these short-comings, we have developed cytometric features specifically for automated recognition of cell images from high grade malignant non-Hodgkin's lymphomas (NHL) and reactive lymphoid lesions. This study used a colour TV-microscope system, high resolution scanning (13.3 pixel/microns), and image processing to study a total of 3600 lymphoid cells from 15 high grade malignant NHL and three tonsils. Sixteen out of 64 features, especially developed for image analysis in cytological preparations, have been evaluated. Because of a considerable overlap of all the single features, no feature on its own allows reliable discrimination. But, multivariant analysis of suitable feature combinations resulted in reliable identification and discrimination of the most frequently occurring cell types. We show that the lymphocytes, centrocytes, centroblasts, immunoblasts and lymphoblasts, as they are defined by subjective morphological criteria in the Kiel-classification of malignant NHL, also form distinctive subpopulations on the basis of their objective mathematical cell features. Furthermore, we have shown that there are distinctive differences between the lymphoma cells and their benign counterparts derived from reactive lymphoid lesions.

Diagnosis, Differential↗
PubMed1989

Computer aided cytometry in high grade malignant non-Hodgkin's lymphomas and tonsils.

The aim of the study is to establish quantitative cytological criteria for reliable diagnoses in high grade malignant non-Hodgkin's lymphomas (NHL). For this purpose Pappenheim-stained cytologic imprints from 15 cases of high grade malignant NHL and ten cases of chronic tonsillitis have been analysed using a TV-microscope system, high resolution color scanning (13.3 pixel/microns), and image processing on a computer. The highly reliable computer-extracted cell features can be used to discriminate the different cell types of malignant NHL. Because of a considerable overlap, no feature on its own is sufficient to discriminate all the different cells. Only multivariate analysis of a suitable combination of features allows reliable discrimination. The results show that the different cells defined by subjective morphological criteria in the Kiel-classification of malignant NHL also form distinctive subpopulations with regard to their objective mathematical cell features and show distinctive differences when compared with their benign counterparts derived from reactive lymphatic tissue.

Color↗
PubMed1988

Results of a stimulatory therapy of low bone metabolism in osteoporosis with (1-38)hPTH and diphosphonate EHDP. Protocol of study I, osteoporosis trial Hannover.

In contrast to prevention, the therapy of manifest osteoporosis remains a clinically significant problem. So far all therapeutic attempts have yielded unsatisfying results. For this reason we have tried to achieve a positive bone balance by sequential stimulation and inhibition of the osseous metabolism. The therapy consisted of six 14-day courses with 400 units (1-38)hPTH per day and, in addition, starting with the 2nd week of PTH therapy, EHDP 5 mg per kg body weight per day for a total of 2 weeks. Already the initial therapeutic course resulted in a stimulation of decreased bone metabolism which could be documented by an increase in the calcium-47 accretion rate (six patients). An increase of the alkaline phosphatase could be noted (four patients); this, however, did not correlate with the calcium accretion. A positive calcium balance could, nonetheless, only be attained in four of eight patients within this period, while neither the alkaline phosphatase nor the kinetics would allow a prediction of this effect. Changes of the balance coincided with equal changes in the net calcium absorption. The urinary calcium excretion increased temporarily during the therapeutic phase. We were not able to detect an influence on the vitamin D metabolites. Histomorphometric studies did not demonstrate an increase in bone mass in the iliac creast after six therapeutic courses. Nevertheless, progressive deformations of vertebral bodies did not occur. We conclude that already after 2 weeks this therapeutic concept can lead to a stimulation of bone metabolism.

Adult↗
PubMed1987

[Causes of inadequate vision in drivers and their significance in traffic].

From an analysis of the data of 462 automobile drivers with inadequate visual acuity it was established that the frequency of visits to the ophthalmologist by drivers with inadequate vision is determined less by age than by the cause of the visual deficiency. Here, considerable differences appear in the duration of inadequate vision before it is detected by the ophthalmologist and in the frequency of visits to the ophthalmologist. These have the effect that the refractive error, the most common visual deficiency among younger drivers, is considerably more important as an accident risk in road traffic than one might assume from the number of those affected. A precautionary elimination of visual deficiencies as cause of accidents therefore necessitates an examination of visual acuity which includes all age groups. In order to eliminate visual deficiencies in road traffic as a cause of accidents as a precaution, the officials responsible must find a practicable way of detecting and eliminating these deficiencies so early as possible. On the other hand, ophthalmologists must make it clear to their visually unsuited patients that in their own and the general interest they should give up driving.

Adolescent↗
PubMed1987

On-line transmission electron microscopic image analysis of chromatin texture for differentiation of thyroid gland tumors.

Nuclei of the cells from the thyroid gland were analyzed in a transmission electron microscope by direct TV scanning and on-line image processing. The method uses the advantages of a visual-perception model to detect structures in noisy and low-contrast images. The features analyzed include area, a form factor and texture parameters from the second derivative stage. Three tumor-free thyroid tissues, three follicular adenomas, three follicular carcinomas and three papillary carcinomas were studied. The computer-aided cytophotometric method showed that the most significant differences were the statistics of the chromatin texture features of homogeneity and regularity. These findings document the possibility of an automated differentiation of tumors at the ultrastructural level.

Adenocarcinoma↗
PubMed1986

Leukemia-related morphological features in blast cells.

This paper investigates the use of image-processing methods to detect leukemia-related morphological differences in mononuclear blast cells. Routinely prepared Pappenheim-stained blood smears were scanned in a high-resolution color TV-microscope system. Eleven blast-cell classes (OMSBC, T-ALL, OMS, ALL, LBL, IBL, AUL, AML, AMOL, AMMOL, and CML) were analyzed with the nonparametric statistical software program "Classification and Regression Trees" (CART). This paper documents the initial statistical evaluation of 62 leukemia-related morphological features that directly measure and analyze the cell-related quantifiable differences occurring in the various blast cells. The 62 cell image features include both common cytophotometric features, and new texture and color features developed for this project. This study found that each leukemia specimen contains a dominant class of blasts that correlates with the specific leukemia, plus a distribution of blasts from related diseases. The present data suggest the existence of a distribution fingerprint pattern for each leukemia.

Cell Nucleus↗
PubMed1986

Segmentation of stained blood cell images measured at high scanning density with high magnification and high numerical aperture optics.

In hematological morphology, it is necessary to resolve and analyze the smallest possible cellular details appearing in the light microscope. A prerequisite for computer-aided analysis of subtle morphological features is measuring the cells at a high scanning density with high magnification and high numerical aperture optics. Contrary to visual observations, the information content in a measured picture can be increased by setting the condensor's numerical aperture (NA) greater than the objective's NA. The complexity and heterogeneity of such cell images necessitate a new segmentation method that conserves the morphological information required in the subsequent image analysis, feature extraction, and cell classification. In our segmentation strategy, characteristic color difference thresholds for each nucleus and cytoplasm are combined with geometric operations, probability functions, and a cell model. All thresholds are repeatedly recalculated during the successive improvements of the image masks. None of the thresholds are fixed. This strategy segments blood cell images containing touching cells and large variations in staining, texture, size, and shape. Biological inconsistencies in the calculated cell masks are eliminated by comparing each mask with the cell model criteria integrated into the entire segmentation process. All 20,000 leukocyte images from 120 smears in our leukemia project were segmented with this method.

Blood Cells↗
PubMed1986

[The incidence of visually impaired drivers seen in ophthalmologic consultation].

On the basis of a critical review by Dr. rer. nat. Bresser the calculation contained in the paper "Ophthalmological Experiences with Automobile Drivers with Inadequate Visual Acuity" is corrected. From the information on visits to the ophthalmologist contained in the study data, the average frequency of repeated visits can be worked out to 1.56. As a consequence, the average duration of unsuitable vision is 22.1 months. This results in a prevalence P = 360750. However, this figure can only apply to drivers who visit an ophthalmologist. According to a recent study based on a random sample of the population, the true number of drivers with unsuitable vision seems to be more than 4 times the figure quoted.

Automobile Driving↗
PubMed1985

Computer-based cytophotometric classification of thyroid tumors in imprints.

This study of 14 follicular adenomas, 10 papillary carcinomas and 11 follicular carcinomas of the human thyroid gland demonstrates the possibility of a cytological tumor classification using digital picture processing. Routinely prepared, HE-stained imprints of surgical specimens were scanned under a light microscope at high resolution with a colour TV camera. The cell nuclei were segmented and analysed with an image processing system. The computer-aided cytophotometric methods detected the most significant differences in the chromatin texture with a criteria variance of texture line distances and texture points per texture knots. Using these criteria benign and malignant tumor types could be successfully differentiated.

Adenocarcinoma↗