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Biomedical subjects

H Ehrenreich

Publications and source records attributed to H Ehrenreich.

At least 91 records · Page 5Linked to original sources
PubMed1991

A vasoactive peptide, endothelin-3, is produced by and specifically binds to primary astrocytes.

Primary rat astrocytes were found by immunohistochemistry to display positive staining for endothelin-3, located predominantly in the perinuclear area. The ability of these cells to produce and release endothelin-3 was confirmed by a combination of reverse-phase HPLC and radioimmunoassay, specific for endothelin-3, which demonstrated immunoreactive peptide in cellular extracts and astrocyte-conditioned medium. In addition, astrocytes were shown to possess a single class of binding sites for endothelin with comparable high affinity for endothelin-1, -2 and -3. These results suggest that astrocytes, by virtue of their ability to produce and secrete endothelin-3, serve as a potential extravascular source of intracerebral vasoregulation capable of influencing regional cerebral blood flow.

Animals↗
PubMed1991

Selective autoregulation of endothelins in primary astrocyte cultures: endothelin receptor-mediated potentiation of endothelin-1 secretion.

Observations that primary rat astrocytes express high-affinity binding sites for endothelins and, in addition, are capable of producing not only endothelin-3 but also endothelin-1 prompted the investigation of a possible relation between endothelin peptides and receptors in these cells. Sarafotoxin S6b, an endothelin receptor agonist, was used as a tool to study endothelin receptor-mediated changes in the secretion of endothelin-1 and -3. The effects of sarafotoxin S6b and endothelin-1 in stimulating inositolphospholipid turnover as well as in inducing AP1 in primary astrocyte cultures were found to be similar. A low cross-reactivity of sarafotoxin S6b with endothelin-1 and -3 in the endothelin radioimmunoassays used here, along with a distinctly different elution position in high-performance liquid chromatography, allowed a clear discrimination between sarafotoxin and endothelins in the culture media. Stimulation of primary rat astrocytes with 10(-7) M sarafotoxin S6b for 1 hour resulted in a substantial increase in endothelin-1 immunoreactivity in the medium. This immunoreactivity reached a peak at 3 hours and showed no further increase after 8 and 24 hours. Treatment of our cultures with phorbol myristate acetate, lipopolysaccharide, tumor necrosis factor alpha, and norepinephrine for 24 hours led to only a moderate elevation of endothelin-1 immunoreactivity. Immunoreactive endothelin-3 was not affected by any of the treatments tested. Thus, our data suggest that endothelins in primary rat astrocytes are subject to selective autoregulation, as demonstrated by the potentiation of endothelin-1 secretion after activation of glial endothelin receptors.

Animals↗
PubMed1990

Endothelins, peptides with potent vasoactive properties, are produced by human macrophages.

Endothelins are peptides, originally isolated from endothelial cells, with potent vasoactive and mitogenic properties. In this study, we demonstrate that human macrophages synthesize and secrete endothelins. Cultured human macrophages were found by immunocytochemistry to stain positively for endothelin 1 and endothelin 3. Their capability to produce and release these peptides was confirmed by a combination of reverse-phase high-performance liquid chromatography and radioimmunoassays, specific for endothelin 1 and 3, respectively. Immunoreactive peptides were identified both in cellular extracts and in macrophage-conditioned medium. The secretion of endothelin 1, but not of endothelin 3, from macrophages could be stimulated 6-10-fold by lipopolysaccharide or phorbol myristate acetate (PMA). Northern blot analysis of total macrophage RNA using an endothelin 1 cDNA probe revealed induction of endothelin mRNA in PMA-treated macrophages. Furthermore, immunoreactive endothelin 1 and 3 were found in U937 cells, a human promonocytic line, and in freshly isolated human monocytes. In contrast, no immunoreactive endothelin was detected in cell extracts from human neutrophils and lymphocytes. The expression of endothelins in tissue macrophages was demonstrated in paraffin sections of human lung using immunohistochemistry. In conclusion, the finding that human macrophages produce endothelins suggests an important role for these peptides in the microenvironment of tissue macrophages. Macrophage-derived endothelins may have an essential function in blood vessel physiology, and aberrant production may contribute to vessel pathology.

Cells, Cultured↗
PubMed1989

Complete bilateral internal ophthalmoplegia as sole clinical sign of botulism: confirmation of diagnosis by single fibre electromyography.

A case of complete bilateral internal ophthalmoplegia as the sole clinical sign of botulism is reported. Diagnosis was immediately confirmed by single-fibre electromyography (SFEMG), which revealed abnormally high blocking (14.3%), contrasting with moderately increased jitter (mean consecutive difference in the extensor digitorum communis muscle, 43.9 microseconds). After giving equine botulinum antitoxin and simultaneous forced emptying of the bowels, ocular symptoms completely disappeared within 2 days. Six days, 5 weeks and 6 months after the first SFEMG study, the jitter was still abnormal, even becoming more so with time. Blocking, however, was only rarely observed in the follow-up studies. It is concluded that SFEMG may serve as a useful and sensitive method for the rapid diagnosis of botulinum intoxication, even in cases where no clinical signs of general muscular weakness are apparent.

Adult↗
PubMed1989

Non-invasive topographic analysis of intestinal activity in man on the basis of acustic phenomena.

In an attempt to find a non-invasive method yielding a comprehensive insight into a patient's intestinal activity, continuous multichannel registration and analysis of acustic phenomena as produced by the intestines were performed. Previous work, described by others, was further developed with respect to topographical interpretation of the data obtained, and to the possible introduction into general clinical use by installing different methods of artifact detection and reduction. To record and process bowel sounds, a device developed for this purpose (Phonoenteroanalyzer PEA-06, G-W Elektronik, Munich, FRG) was used. Five specially designed microphones were placed on the abdominal wall. After amplification and filtering, further processing of the signal was achieved by means of rectifying, peak detection, and logarithmic transformation techniques, yielding a topographically discernible pattern of intestinal activity. Noise and movement artifacts, although a basic problem of this technique, could be adequately managed, e.g., by using a control microphone as well as simultaneous registration of breathing. Ten normal subjects as well as eight patients with manifest or suspected gastrointestinal problems, had their bowel sounds registered either continuously overnight or during adequate stimulatory tests (gastrocolonic response, neostigmine test, rectal distension). Bowel sounds were registrated as short "clicks" or longer lasting, sometimes rhythmically appearing, complex acustic phenomena. Overnight registrations revealed periodical changes in general or local intestinal activity, which in turn showed remarkable interindividual variabilities. Stimulatory tests provoked an enhancement of intestinal activity, which could well be documented with this method. In conclusion, analysis of acustic phenomena provoked by the bowels should henceforth allow an objective, continuous, long-term, non-invasive, indirect, and at any time repeatable topographical registration of intestinal activity.

Adult↗
PubMed1989

Immunoreactive atrial natriuretic peptide (ANP) in endoscopic biopsies of the human gastrointestinal tract.

The human gastrointestinal tract, important for body salt and water balance, was investigated by endoscopic biopsy for the presence of atrial natriuretic peptide (ANP). Using immunohistochemistry, ANP-immunoreactive cells were identified in the lamina epithelialis mucosae of stomach, duodenum, jejunum, colon, and rectum. The findings indicate that ANP plays a role in intestinal salt and water regulation in man. ANP measurements in tissue specimens reached by endoscopic biopsy may be of major interest for future investigations on (patho-)physiological and pharmacological aspects of ANP.

Adult↗
PubMed1988

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Journal Article↗
PubMed1988

Stimulation by hCRF of C-peptide release in type 2 diabetics during concomitant opioid receptor blockade.

Administration of synthetic human corticotropin-releasing factor (hCRF, 2 micrograms/kg body weight) during simultaneous application of the opioid antagonist naloxone (1.6 mg i.v. bolus, followed by an infusion at a rate of 1.2 mg/h) produced a significant increase in plasma C-peptide levels of six male Type 2 diabetic patients which even exceeded the postprandial values. This stimulatory effect of hCRF/naloxone on plasma C-peptide was less pronounced in six healthy men. hCRF alone did not provoke any reaction of plasma C-peptide in either group. The possibility of a paracrine, CRF-dependent mechanism in pancreatic islets which somehow involves inhibitory opioid receptors is preferentially discussed. Such a mechanism may underlie the stimulatory action of hCRF/naloxone on B cells and would explain the absent reaction of peripheral venous plasma C-peptide to hCRF alone as well as the amplifying effect of simultaneous opioid receptor blockade.

Blood Glucose↗