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Biomedical subjects

E Hahn

Publications and source records attributed to E Hahn.

At least 55 records · Page 3Linked to original sources
PubMed1988

Linear Ferguson plots of polystyrene sulfate size standards for the quantitative agarose gel electrophoresis of subcellular particles.

Accurately standardized commercial polystyrene sulfate particles in agarose gel electrophoresis yield linear Ferguson plots at pH 7.4 over a gel concentration range up to 0.9% agarose which do not exhibit any significant sigmoidal curve elements, using either a discontinuous buffer system or a continuous buffer. Ferguson plots of these standard-sized particles were evaluated using alternatively a linear or convex model, by means of a newly developed set of programs (to be used in conjunction with program M-LAB) which (i) is sufficiently user-friendly to allow for quantitative agarose gel electrophoresis of subcellular-sized spherical particles based on their convex Ferguson plots with the same operational simplicity previously available for linear Ferguson plots only; (ii) simultaneously and interactively analyzes the Ferguson plots of all particles under consideration on the basis of an extended Ogston model.

Electronic Data Processing↗
PubMed1988

Evidence that a decrease in opioid tone on proestrus changes the episodic pattern of luteinizing hormone (LH) secretion: implications in the preovulatory LH hypersecretion.

We have studied the LH secretion pattern evoked by diminution in the opioid tone produced by iv naloxone (NAL) infusion between 1100-1400 h on proestrus, the LH secretion pattern occurring spontaneously between 1430-1730 h on proestrus and the LH secretion pattern produced by exogenous LHRH administered either as a 10 ng/pulse at 20-, 30-, or 60-min intervals or infused continuously at a rate of 30 ng/h between 1200-1700 h in rats given pentobarbital at 1100 h on proestrus. Infusion of 0.5 ng NAL/h raised plasma NAL levels to 200-300 ng/ml and augmented LH secretion, as evident by increments in pulse amplitude and frequency discharge to one every 37.5 min from an average of one every 75 min in saline-infused control rats. A 4-fold increase in circulating NAL levels, produced by 2 mg/h NAL infusion, further augmented the frequency of LH episodes to 30-33 min and induced a surge-like LH secretion pattern which resembled that seen on the afternoon of proestrus. Further analysis of the secretory pattern of the preovulatory LH surge (n = 7) showed LH pulses of increased amplitude during the basal phase (n = 4), ascending phase (n = 2), and plateau and descending phases (n = 3); in two rats the LH rise was steep, and no LH pulses were identified. A LHRH pulse (10 ng/pulse) delivered at 20- or 30-min intervals or continuous infusion of LHRH at a rate of 30 ng/h produced LH surges, with peak levels reaching the range seen on the afternoon of proestrus. Further, despite the fact that 10 ng LHRH/pulse at 20-min intervals reproduced a proestrous-type LH surge, only 40% of the LHRH pulses were followed by identifiable LH pulses. Surprisingly, despite the observations that NAL evoked robust LH episodes, the basal pattern of FSH secretion in these rats was not altered. These findings show that a decrease in opioid tone on proestrus accelerates episodic LH discharge to the range that occurs after gonadectomy. A quantitative relationship between the degree of restraint on the opioid tone imposed by NAL and the magnitude of the LH response can be demonstrated. The evidence suggests that the preovulatory LH surge may occur in an episodic fashion and that it can be reproduced by LHRH delivered at a frequency rate of LH pulses seen in ovariectomized rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Energy expenditure of patients with cystic fibrosis.

Resting energy expenditure was measured by open-circuit indirect calorimetry in 71 patients, aged 8.9 to 35.5 years, with cystic fibrosis who had no recent history of acute lung infection. Pulmonary function and nutritional status were studied simultaneously. In most patients, resting energy expenditure was above normal (range 95% to 153% of predicted values for age, sex, and weight as derived from the Harris Benedict equations), and was negatively correlated with pulmonary function (P less than 0.01) and nutritional status (P less than 0.01) when expressed as a percentage of body fat. Pulmonary status was positively correlated with nutritional status (P less than 0.01). We conclude that resting energy expenditure in patients with cystic fibrosis exceeds normal values and that the increase correlates with a deterioration in lung function and nutritional status.

Adolescent↗
PubMed1985

Basement membrane proteins and type III procollagen in murine schistosomiasis.

The livers of female CBA mice were examined 9 to 10 weeks after subcutaneous infection with Schistosoma mansoni. Cryostat liver sections and isolated liver cells were examined by indirect immunofluorescence using specific antibodies against basement membrane proteins (laminin, fibronectin and type IV collagen and type III collagen precursor. Liver cells were isolated by collagenase digestion, purification on Percoll density gradients and centrifugal elutriation to yield enriched fractions of hepatocytes, endothelial and Kupffer cells (Fractions I, II, III respectively). Infected animals yielded more than three times the control number of non-parenchymal cells; electron microscopy revealed that the increase in Fraction II was due mainly to eosinophilic leucocytes and in Fraction III due to Kupffer cells and macrophages from the schistosomal granulomata. Studies of cryostat liver sections showed that the schistosomal granulomata contained dense deposits of type III collagen precursor and fibronectin in the distribution of the reticulin fibres but laminin and type IV collagen were conspicuous only in new vessels in the periphery of the granuloma. Isolated liver cells showed fibronectin on their surface. Immunofluorescence studies could not be performed on Kupffer and endothelial cell fractions because of marked non-specific fluorescence. These experiments indicate that centrifugal elutriation is a useful method for isolating the constituent cells of murine schistosomal granulomata.

Animals↗
PubMed1984

Nalmefene: radioimmunoassay for a new opioid antagonist.

A specific radioimmunoassay (RIA) has been developed for the quantitation of a new opioid antagonist, nalmefene, in human plasma. The method employs a rabbit antiserum to an albumin conjugate of naltrexone-6-(O-carboxymethyl)oxime and [3H]naltrexone as the radioligand. Assay specificity was achieved by extraction of nalmefene from plasma at pH 9 into ether prior to RIA. The procedure has a limit of sensitivity of 0.2 ng/mL of nalmefene using a 0.5-mL sample of plasma for analysis. The intra- and interassay coefficients of variation did not exceed 5.6 and 11%, respectively. The specificity of the RIA was established by demonstrating excellent agreement (r = 0.99) with a less sensitive and more time consuming HPLC procedure in the analysis of clinical plasma samples. The use of the RIA for the pharmacokinetic evaluation of nalmefene is illustrated with plasma concentration profiles of the drug in humans following intravenous and oral administration.

Humans↗
PubMed1982

Mathematical processes in the evaluation of the dangerous nature of chemicals.

The present study was carried out on the basis of the question of "whether it is possible to use mathematical methods meaningfully for the evaluation of the environmental effects of chemicals." The analysis of the evaluation process showed that this may be considered as a relation between the set of test data and a target set, that of the danger classes. The very general structure of a relation considerably restricts the use of algorithms; in particular it can be shown that algorithms which would map the data directly onto the danger classes like a functional coordination are, in general, excluded. This is partly due to the highly nonhomogeneous parameter set which must be determined for evaluation purposes, and partly to the high degree of randomness or human participation in the selection of the parameters. Moreover, there was no indication whether or to what extent the parameters are interdependent, i.e., whether there are interdisciplinary regularities which could be expressed algebraically and interpreted scientifically. Questions of this kind remain components of interdisciplinary research, and they cannot be explained from a mathematical--i.e., theoretical--point of view. Considerably more empirical material needs to be available for use as the foundation for a reasonable theory.

Animals↗
PubMed1980

Distribution of basement membrane proteins in normal and fibrotic human liver: collagen type IV, laminin, and fibronectin.

Specific antibodies to collagen type IV, laminin, and fibronectin were used to localise these proteins by indirect immunofluorescence in frozen sections of normal and fibrotic liver. In normal livers distinct staining was found in basement membranes of blood and lymph vessels, of bile ducts and ductules and around nerve axons. Positive reactions for type IV collagen and fibronectin were also observed in the perisinusoidal space, while hepatocytes and most of the interstitial matrix of portal fields remained unstained. Liver specimens obtained from patients with alcoholic liver disease (fatty liver, hepatitis or cirrhosis) and chronic active hepatitis showed a more intense reaction with the antibodies in the perisnusoidal space including now distinct staining for laminin. These patterns were particularly prominent at borders between fibrotic septa and remnants of parenchyma or pseudolobules. Strong reactions were also found for type IV collagen and fibronectin in the periportal interstitium and in large fibrotic areas. The findings support previous electron-microscopical and chemical evidence for increased basement membrane production in human liver fibrosis and demonstrate that this may involve different proteins and occur at different anatomical sites.

Adolescent↗
PubMed1979

[Current aspects of rheumatoid arthritis].

According to recent investigations two factors might play an essential role in the pathogenesis of rheumatoid arthritis (R.A.). Besides genetic components, i.e. the HLA-system and familial aggregation, the immune processes, mediating tissue inflammation and injury, are acknowledged as having established roles in the pathogenesis of R.A. The present report reemphasizes recent data concerning the autoimmunity and the immunologic network with trends of therapy in R.A. In view of the effectiveness of new nonsteroidal antiinflammatory drugs, a double-blind study of suxibuzon vs. indomethacin in 30 patients with active R.A. is described in detail. Both drugs were active and similar in their efficacy at 4 weeks as judged by clinical and laboratory measurements. No serious toxic side-effects were observed in both treatment regimens.

Administration, Oral↗
PubMed1979

[Infections caused by Yersinia enterocolitica: bacteriological, serological, epidemiological and immunological findings in 51 cases (author's transl)].

Within two years 51 infections caused by Yersinia enterocolitica were diagnosed by bacteriological and (or) serological tests (Yersinia enterocolitica Serovar 03 in 48, Serovar 09 in two and Serovar 04 in one). The latter was isolated from the discharge of a badly healing superinfected wound. In the other 50 there was feverish enteritis, in 12 with arthritic complaints. Of the latter 12 nine had the antigen HLA-B27. This investigation demonstrated a slight increase in cases during the cold months. Men were more frequently affected than women and 38 were older than 16 years. In-vitro sensitivity of the isolated Yersinia strains against various chemotherapeutic agents was also tested.

Adolescent↗
PubMed1979

Radioimmunoassay for type III procollagen peptide and its application to human liver disease.

A sensitive and specific radioimmunoassay was developed for the precursor-specific peptide segment located at the amino end of bovine type III procollagen. Human material showed high cross-reactivity in this assay. Two forms of human procollagen peptides were detected in body fluids. The larger peptide (45K) was found in serum and ascites, and resembled the whole precursor-specific segment which is presumably released from human type III procollagen by a single enzymatic cleavage. The smaller peptide (10K) was found mainly in urine indicating that further degradation of circulating procollagen peptides is required prior to their passage through the kidney. Compared to peptide concentrations in normal human serum two to twenty-fold increases were observed in all patients with alcoholic liver disease, in fifteen of seventeen patients with acute hepatitis, and in ten of fourteen patients with chronic active hepatitis. Much higher levels were detected in ascites fluid. Patients with rheumatoid arthritis and other diseases showed far smaller elevations of the serum peptide. In alcoholic liver disease peptide levels correlated well with inflammation and necrosis observed in liver biopsies, but not with other laboratory parameters.

Adolescent↗