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Biomedical subjects

J Richter

Publications and source records attributed to J Richter.

At least 325 records · Page 18Linked to original sources
PubMed1988

Myeloid cell differentiation: the differentiation inducing factors of myeloid leukemia cells.

Mitogen-stimulated lymphocytes and some T-lymphocyte lines released a polypeptide called differentiation-inducing factor (DIF), which restored maturation of promyelocytic HL-60 cells and inhibited growth of leukemic and normal progenitor cells. Tumor Necrosis Factor (TNF), which has been found to be not identical with DIF, displayed similar effects. On the other hand, an antigenic relationship was shown between DIF and lymphotoxin (LT) by use of neutralizing antibodies. An activity, which cochromatographed with DIF during all purification steps, competed with binding of both rLT and rTNF to HL-60 cells. Approximately 2,000 binding sites for rLT were detected per cell, with a Kd of 330 pmol/l. Our observations are indications of a functional and an antigenic connection between DIF and LT, and indicate that TNF, LT and DIF share cell surface-binding sites. These binding sites are down regulated by activation of protein kinase-C. Results from modulation of the response indicated that the signal for differentiation might be transduced through activation of phospholipase A2. In order to understand myeloid differentiation and the effects of differentiation factors, we have pursued investigations of the biosynthesis and processing of one marker of myeloid differentiation, namely myeloperoxidase (MPO). Our results disclosed that MPO was synthesized as a larger precursor of Mr 90,000 to which a heme group was added, followed by proteolytic cleavage in pregranular structures to generate mature heavy Mr 60,000 and light Mr 12,000 subunits. Processing of MPO was independent of acidification. cDNA probes are now available for MPO, so that investigation of gene expression in relation to differentiation and induction of differentiation is facilitated.

Cell Differentiation↗
PubMed1988

[Results of radiotherapy treatment of nasopharyngeal tumors depending upon the pathologico-anatomic diagnosis].

Malignant nasopharyngeal tumors are rare, so that there are only few communications about treatment results in dependence on histological findings. The histological classification of malignant tumors, especially in case of malignant lymphomas, has changed considerably during the last few years. All histological preparations available from 157 patients treated by radiotherapy between 1960 and 1985 have been reassessed. Above all it was attempted to classify the formerly current diagnoses "retothelial sarcoma" and "lymphosarcoma" according to today's criteria and to assign to a histological type those tumors which could not be exactly classified hitherto. This proceeding has increased especially the group of malignant non Hodgkin's lymphomas from seven to 29 patients. The therapy results achieved after irradiation are presented in dependence on histological data and compared to the results communicated in literature. A certain stagnation is found for the last few years showing that an optimum of present therapy possibilities has been reached at the individual therapy centers.

Adolescent↗
PubMed1988

Spontaneous noncardiac chest pain. Evaluation by 24-hour ambulatory esophageal motility and pH monitoring.

Noncardiac chest pain can be a diagnostic dilemma because patients rarely experience spontaneous chest pain in the laboratory. Therefore, we studied 24 patients with chronic, daily, substernal chest pain with a prototype 24-h ambulatory esophageal motility and pH system. Spontaneous chest pain episodes were correlated with pH less than 4 and abnormal motility changes (mean amplitude and duration, maximum amplitude and duration, or percentage of abnormal peristalsis) defined as exceeding the patient's normal esophageal motility pattern. Twenty-two patients experienced a total of 92 spontaneous chest pain episodes. Eleven chest pain episodes (12%) occurred during abnormal motility, whereas 18 episodes (20%) were associated with pH less than 4 and four episodes (4%) had both abnormalities. The majority of chest pain episodes, 59 events (64%), did not have any association with motility or pH. Abnormal maximum duration and amplitude were the motility changes most frequently associated with chest pain. Overall, 13 of 22 patients (59%) had at least one chest pain episode correlating with abnormal motility or pH (range 33%-100%). Therefore, we conclude that ambulatory esophageal motility and pH monitoring is useful in the evaluation of noncardiac chest pain. pH abnormalities (20%) are more commonly associated with chest pain than motility abnormalities (12%). However, the majority of chest pain episodes (64%) did not correlate with either abnormality and may be the result of lowered esophageal pain threshold for distention, i.e., the "irritable esophagus."

Chest Pain↗
PubMed1988

Subjective evaluation of isolated and combined exposure to whole-body vibration and noise by means of cross-modality matching.

Cross-modality matching (CMM) were used for the evaluation of combined effects of sinusoidal whole-body vibration (WBV) in Z-axis with the frequencies 3-7 Hz, 1.5 ms-2, and two noise levels (L1 = 65 dBA; L2 = 85 dBA). CMM's were tested by means of three responses: handgrip force, length, estimation and brightness adjustment. The subjects were instructed to set different modalities to a value corresponding to their perception of vibration. The combination of WBV and L2 caused higher sensation responses than WBV and L1.

Analysis of Variance↗
PubMed1987

Gastroenteritis in infants, associated with a genome type of adenovirus 31 and with combined rotavirus and adenovirus 31 infection.

In an infants' ward, gastroenteritis occurred in five children in two groups, probably by nosocomial spread of adenovirus 31 (three cases) and adenovirus 31 + rotavirus (two cases). The infants recovered well. The DNA of adenovirus 31 isolates was analysed with ten restriction endonucleases and found identical for all five strains, but different from the prototype.

Adenoviruses, Human↗
PubMed1987

Myocardial protection: left ventricular ultrastructure after different forms of cardiac arrest.

Clinically applied methods of cardioplegia show very different effects on the rapidity of decay of energy-rich phosphates as well as on kind and progression of ultrastructural alterations of the ischemic myocardium. Comparing the methods of cardioplegia according to Kirklin, St. Thomas's Hospital and Bretschneider (solution HTK) with pure ischemia at 25 degrees C (model A) and Kirklin's or St. Thomas's cardioplegia and subsequent 210 min or HTK cardioplegia and 300 min ischemia at 22 degrees C plus 20 min subsequent reperfusion (model B) leads to the following results: Model A: Compared with pure ischemia cardioplegia according to Kirklin and the St. Thomas's Hospital slows down the decay of the left ventricular ATP-concentration by a mean factor of 3 and the progression of structural alterations of the left ventricular subendocardium by a factor of 2. HTK retards the ATP-decay by a factor of 6, the alterations of ultrastructure by a factor of 6.5. St. Thomas's solution, in contrast to all other methods of cardioplegia, at the onset of ischemia already causes a cellular edema of myocytes; the edema increases during ischemia, and at the ATP-concentration of 4 mumol per gram myocardium is more pronounced than with pure ischemia, Kirklin or HTK. After application of Kirklin's solution, in contrast, a cellular edema of capillary endothelia develops during ischemia, which at 4 mumol ATP is more pronounced than with each of the other methods. Model B: After global ischemia until the ATP-concentration of left ventricular myocardium is 4 mumol/g and a subsequent 20 minutes post-ischemic recovery the ultrastructural alterations in principle resemble those occurring during ischemia (model A).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗