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Biomedical subjects

H Graf

Publications and source records attributed to H Graf.

At least 19 recordsLinked to original sources
PubMed1992

Plasma apolipoprotein A-IV metabolism in patients with chronic renal disease.

The plasma concentration and distribution of apolipoprotein A-IV were investigated in normotriglyceridaemic patients with end-stage renal disease and compared with those in a sex- and age-matched control group with normal renal function. A three-fold elevated plasma mean concentration of apolipoprotein A-IV was found in patients with end-stage renal disease treated by haemo- or peritoneal dialysis (58.5 +/- 18.9 mg dl-1 or 50.5 +/- 12.2 mg dl-1, respectively) compared with the controls (18.3 +/- 6.4 mg dl-1). The plasma distribution of apolipoprotein A-IV was studied in patients treated by haemodialysis and in controls by gel permeation chromatography. In the haemodialysis group, 40.3% of the apolipoprotein A-IV was found to be associated with the fraction of high density lipoproteins, whereas the rest (59.7%) was not associated with lipoproteins. This distribution was significantly different from that in the control group (24.8% vs. 75.2%, 0.01 less than P less than 0.05). The elevated plasma concentrations of apolipoprotein A-IV in the patients are not related to triglyceride levels and therefore are unlikely to result from an impaired catabolism of triglyceride-rich lipoproteins. The accumulation of apolipoprotein A-IV in high density lipoproteins from patients with end-stage renal disease might reflect the impaired reversed cholesterol transport mechanisms which are believed to be a major cause of the high prevalence of atherosclerotic diseases in these patients.

Adult↗
PubMed1992

Numbers and vitality of leukocytes in pocket washings of untreated periodontitis lesions in humans utilizing a novel intracrevicular lavage technique.

The purpose of the present study was to develop an intracrevicular lavage technique, and to use it for assessment of the total number and % of vital leukocytes from untreated periodontitis pockets. A lavage device was developed, consisting of specially crafted cannulas, a vacuum pump and a charge amplifier. In vivo evaluations showed that there was a linear relationship between lavage time and lavage volume; 2-6 lavage samples were obtained from each of 20 patients with untreated advanced periodontitis, and the lavage time was measured in a subsample of 16 pockets. The lavage fluid was centrifuged, and the supernatant was separated from the cellular components. The cells were vital-stained using two methods, trypanblue exclusion method (TB) and ethidium-bromide fluorescein-diacetate stain (EB-FDA). Numbers of vital and non-vital leukocytes per sample were assessed using a Neubauer chamber. The number of erythrocytes per sample was evaluated using the same counting method. The results included 95 samples obtained from the 20 patients: 76% of all samples ranged in pocket depth between 4 and 8 mm. The lavage technique provided an overall mean lavage volume of 282.37 microliters in an average time of 16.44 seconds. The mean number of leukocytes per sample was 22.20 x 10(3) (TB) and 24.48 x 10(3) (EB-FDA). Percent vital leukocytes were 72.27 (TB) and 72.63 (EB-FDA). EB-FDA had a lower counting error than TB. The low erythrocyte counts per sample suggested that subgingival bleeding during sampling was negligible. Spearman correlation coefficients showed weak associations between pocket depth and leukocyte counts, % of vital leukocytes and erythrocytes. Due to the short sampling time this new intracrevicular sampling technique permits sampling of pockets before the tissue responds to the stimulus of the lavage device, and provides subgingival washings with high numbers of leukocytes.

Adult↗
PubMed1992

Cell populations associated with active probing attachment loss.

The purpose of this study was to evaluate the ability of cell populations to differentiate between untreated progressing periodontitis sites (P) and untreated non-progressing sites (NP). Pairs of biopsies were obtained from untreated periodontal patients, one biopsy from a site which had lost probing attachment of 2 mm or more within the previous month, the other biopsy from a non-progressing site. Cell populations were identified on 1 micron sections in a defined connective tissue area at the junctional epithelium. The cell types counted were fibroblasts, mast cells, monocytes/macrophages, polymorphonuclear leukocytes (PMNs), lymphoid cells, plasma cells, endothelial cells, total inflammatory cells, and the total number of cells. The number of fibroblasts, mast cells, monocytes/macrophages, and inflammatory cells, as well as their percentage of the total number of cells, differed significantly between P- and NP-sites. In addition, the actual total counts differed between groups. The difference between groups was more significant for percent fibroblasts than for any other cell type. It appears that cell populations, particularly fibroblast counts, can aid in the histological discrimination between P and NP periodontitis lesions.

Adult↗
PubMed1992

[Age- and sex-specific tooth and jaw measurements and their relation in the 1st mixed dentition phase--a longitudinal study on Jena children at the age of 7 1/2 to 8 1/2 years].

In a longitudinal study consisting of three single examinations dental findings of 89 individuals (40 boys and 49 girls) were recorded. The aim of the study was to check up the process of dental growth and development of 7.6- to 8.6-year-old children. Age- and sex-specific differences could be established in the three occlusal dimensions by means of clinical findings and 3-d-analysis of the plaster casts. The rate of DMF teeth was remarkably low in girls and boys; the presence of malocclusions was surprisingly high.

Age Factors↗
PubMed1992

Three-dimensional force measurements on mandibular implants supporting overdentures.

The purpose of this study was to determine masticatory and functional forces in three axes on mandibular implants supporting overdentures. Five edentulous test subjects were selected, each having two mandibular implants. Three-dimensional piezoelectric force transducers were mounted on the two-part ITI Bonefit implants and rigidly connected to the denture. Forces in vertical, lateromedial, and anteroposterior directions were measured by means of electrostatic plotter records. The test modalities were light tapping, grinding, maximal occlusal force, and chewing test food. Results showed that the five subjects developed similar stress patterns but quantitatively different occlusal and chewing forces. In all but one subject, reduced maximal occlusal force was found compared to dentate subjects and edentulous subjects with fixed partial prostheses supported by implants. The recordings of chewing cycles when eating test food resulted in very regular rhythmic strokes, similar to those of dentate subjects but with slightly reduced speed. All stress patterns showed that occlusal and chewing forces were mainly directed in vertical, medial, and anterior dimensions. The dominating component was vertical.

Aged↗
PubMed1992

Biocompatibility of high-flux membranes.

Standard dialysis with cuprophane membranes is known to stimulate the immune system. As a result of activation of macrophages various interleukins and tumor necrosis factor (TNF) are secreted, presenting further evidence of the poor biocompatibility of cuprophane. We investigated the immunogenic properties of three modern high-flux membranes. Seven patients were studied during hemodiafiltration sessions using either a polysulfone (F60, Fresenius), a polymethylmetacrylate (BK 2.1, Toray) or a cellulose triacetate (FB-210 U, Nipro) dialyzer in a hemodiafiltration procedure. Serial measurements were made during each treatment of interleukin-1 beta (II-1 beta), TNF, soluble IL-2 receptor (sII-2r), soluble CD4 (sCD4), soluble CD8 (sCD8), interferon gamma (IFNg) and neopterin. In contrast to the known increase of IL-1 beta, IL-2r and TNF with cuprophane membranes, none of the modern high-flux dialyzers stimulated the production of these factors. Significant decreases of neopterin and sCD4 were observed. IFNg and sCD8 did not change significantly. Our results suggest that the modern high-flux dialyzers are non-immunogenic, and thus provide further evidence of the superior biocompatibility of synthetic or semisynthetic membranes over the conventional cuprophane.

Aged↗
PubMed1991

Some aspects of hybridoma cell cultivation.

Two hybridoma cell lines were cultivated in an indirectly aerated 10-1 reactor in batch, fed-batch and continuous (perfusion) operations and in spinner flasks. The medium in the reactor was sampled either by an aseptic cross-flow filtration module integrated into a loop or by an in-situ tubular filter. The glucose concentration was monitored by an on-line flow injection analyser and the ammonia concentration by an ion-selective electrode. Since the membrane transmission of the high-molecular components decreased during cultivation, the product, a monoclonal antibody, was enriched in the reactor. During cultivation, the concentrations of cells, viable cells, glucose, lactase, acetate, citrate, ammonia, urea, amino acids, proteins, and monoclonal antibodies were determined off-line. The specific growth rate, specific production, and consumption rates of the medium components were influenced considerably by the medium composition, especially by the type and amount of serum used.

Animals↗
PubMed1991

Effect of recombinant human erythropoietin on anterior pituitary function in patients on chronic hemodialysis.

In 7 patients with end stage renal failure, anterior pituitary function was tested by simultaneous application of maximally effective doses of the hypothalamic releasing peptides, corticotropin-releasing hormone, growth hormone-releasing hormone, thyrotropin-releasing hormone and gonadotropin-releasing hormone, and compared to 8 normal controls. In addition to the pituitary hormones, plasma cortisol, thyroxine and testosterone concentrations were measured. To test for possible effects of treatment with recombinant human erythropoietin (rhu-EPO), all patients with chronic renal failure were studied again after partial correction of anemia by treatment with erythropoietin. Before initiation of rhu-EPO treatment, plasma concentrations of follicle-stimulating hormone were significantly elevated and the thyroid-stimulating hormone and prolactin responses to thyrotropin-releasing hormone blunted when compared to normal controls. Treatment with rhu-EPO induced a significant increase in plasma ACTH and follicle-stimulating hormone concentrations. All other pituitary functions remained unchanged. Thus, the general improvement in well-being, working capacity and sexual activity cannot be attributed to hormonal changes.

Adrenocorticotropic Hormone↗
PubMed1991

In vivo determination of radiographic projection errors produced by a novel filmholder and an x-ray beam manipulator.

Subtraction radiography requires radiographs made with identical projection geometry. The purpose of the present investigation was to develop and evaluate a new in vivo method to measure angular radiographic projection error. This included the development of a system for accurate control of the x-ray beam angulation relative to the intraoral film and the evaluation of the in vivo projection errors (equivalent to the "angular difference" between repeated exposures) produced by the new system. A filmholder, an x-ray beam manipulator, and an aiming device were newly constructed. Reference wires were attached for measuring the projection error on the filmholder and on the 22 bicuspids at the sites of investigation in 16 patients. Two exposures using standardized projection conditions were made of each site. The relative position of the reference wires on the duplicate radiographs was used to calculate the angular difference in the direction of the x-ray beam which occurred between the 2 exposures. Triplicate measurements allowed the determination of measurement error. The angular projection errors were measured in a horizontal and vertical direction. The reference wires allowed determination of the angular projection errors relative to the filmholder, relative to the dentition and the angular error due to the repositioning of the filmholder in the patient's mouth. The average projection errors deviated only slightly from zero. The largest deviation registered was -0.11 degrees. This applies to the horizontal and vertical direction and all relationships. The standard deviations varied between 0.403 degrees and 0.697 degrees. This applies to the standard deviation for all relationships in the horizontal, the vertical, and the oblique directions. The measuring error found from the triplicate measurements had a standard deviation of 0.08 degrees to 0.19 degrees depending on the distance between the reference wires. This new system for controlling in vivo projection errors seems to provide highly standardized radiographs in vivo. The new measuring system proved to be accurate enough to measure the in vivo projection errors between repeated radiographs produced with the new filmholder and x-ray beam manipulator. The in vivo errors produced by the new system are markedly smaller than all in vivo and in vitro errors previously reported in the literature.

Adult↗
PubMed1991

Root substance removal by scaling and root planing.

The amount of root substance removed by scaling and root planing is largely unknown. The present study evaluated in vitro the root substance loss caused by a defined number of working strokes at known forces. Forty extracted teeth with loss of connective tissue attachment into the middle third of the roots were washed and embedded in plaster, leaving one entire corono-apical tooth aspect exposed. The teeth were reproducibly repositioned in a bench-vise, where a profilometer repeatedly measured root surface levels at the same location. In a standard area of the roots a total of 40 working strokes were applied. Low forces were used in 30 teeth and high forces in 10 teeth. The forces were recorded using a piezo-electric receiver built into the upper shank of the curet. Root substance loss was measured after 5, 10, 20, and 40 working strokes. The results showed that the mean low force used per working stroke across all 40 strokes was 3.04 Newtons for the low forces, and 8.48 Newtons for the high forces. Mean cumulative loss of root substance across 40 strokes was 148.7 microns at low forces, and 343.3 microns at high forces. The mean force per stroke increased slightly across the 40 strokes, while substance removal per stroke decreased. Substance removal per stroke during strokes 1 to 5 was 6.8 microns using low forces and 20.6 microns using high forces. During strokes 21 to 40 mean removal per stroke was 2.3 microns at low forces, and 5.6 microns at high forces. These results suggest that high forces remove more root substance, and loss per stroke becomes less with increasing numbers of strokes.

Dental Scaling↗
PubMed1991

[The colloid osmotic pressure of blood. Physiology, measuring technique and pre-analytic factors of influence].

Since the fundamental work of Starling the central of colloid osmotic pressure for maintaining volume homoeostasis and for transcapillary fluid exchange has been well known. To treat an intravasal volume deficit colloidal plasma substitution solutions are able to secure a sufficient colloid osmotic pressure. The last one can be measured by oncometry. Therefore an individual therapy is possible. This review describes the physiologic function, measurement techniques and important influencing parameters and disturbing factors which may be taken into consideration when colloid osmotic pressure is determined.

Blood Proteins↗
PubMed1979

[Calcium and phosphorus metabolism in patients on chronic intermittent haemodialysis with different calcium concentrations in the dialysate (author's transl)].

A study was carried out in 25 patients on chronic intermittent haemodialysis on the effect of increasing the dialysate calcium concentration from 1.5 to 1.75 mMol/l on calcium and phosphorus metabolism. In 16 patients the increase in the dialysate calcium resulted in a sufficiently large increase in the plasma Ca level to suppress the parathyroid glands. The calcium influx during dialysis in these patients was sufficient to abolish the effects of diminished calcium absorption from the intestine due to loss of endocrine renal function. The remaining 9 patients showed no suppression of parathyroid gland activity and could be separated into two different groups, one requiring calcium supplementation and the other group manifesting signs of autonomic hyperparathyroidism. The five patients showing a higher calcium requirement were started on active vitamin D metabolites. In the remaining 4 patients parathyroidectomy will probably be inevitable if progression of the clinical manifestations of hyperparathyroidism occurs. Close control of plasma phosphorus levels is mandatory to avoid an increase in the calcium phosphate product or the danger of hypophosphataemic osteomalacia.

Adolescent↗
PubMed1979

Optimization of conditions for the in vitro formation of hybrid DNA molecules by DNA ligase.

Conditions for the ligation with T4 induced DNA ligase of two DNA molecules via their complementary sticky ends have been established which lead preferentially to the formation of hybrid molecules. This is demonstrated with two combinations of parent molecules varying greatly in their relative molecular weights. In one case the intact hybrid molecule could be directly isolated. In addition a DNA dependent quantitative electrophoretic assay for DNA ligase activity is described which does not need a radioactively labeled substrate. The ligation procedure has been shown to be useful in molecular cloning experiments.

DNA↗