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Biomedical subjects

M Nauck

Publications and source records attributed to M Nauck.

99 records · Page 6Linked to original sources
PubMed1987

[Factitious hypoglycemia caused by taking a sulfonylurea drug].

Three cases of factitious (self-induced) hypoglycaemia, brought about by regular intake of sulphonylurea preparations, seen in the span of three years are reported. The clinical picture was similar to that caused by an insulinoma. One patient was a 31-year-old male nurse, another a 17-year-old girl whose mother was a diabetic, the third a 60-year-old female diabetic. The correct diagnosis of factitious hypoglycemia was made only after demonstrating glibenclamide in serum and urine. Factitious hypoglycemia can be differentiated from fasting hypoglycemia caused by hyperinsulinaemia by a lowered C-peptide level after injection of insulin. When sulphonylurea preparations are taken, the only way of distinguishing factitious hypoglycemia from insulinoma is by determining the drug in serum and urine. The cases reported in the literature are almost all in medical personnel, diabetics or members of their family.

Adolescent↗
PubMed1986

Reduced incretin effect in type 2 (non-insulin-dependent) diabetes.

Integrated incremental immunoreactive insulin and connecting peptide responses to an oral glucose load of 50 g and an "isoglycaemic" intravenous glucose infusion, respectively, were measured in 14 Type 2 (non-insulin-dependent) diabetic patients and 8 age- and weight-matched metabolically healthy control subjects. Differences between responses to oral and intravenous glucose administration are attributed to factors other than glucose itself (incretin effect). Despite higher glucose increases, immunoreactive insulin and connecting peptide responses after oral glucose were delayed in diabetic patients. Integrated responses were not significantly different between both groups. However, during "isoglycaemic" intravenous infusion, insulin and connecting peptide responses were greater in diabetic patients than in control subjects as a consequence of the higher glycaemic stimulus. The contribution of incretin factors to total insulin responses was 72.8 +/- 6.9% (100% = response to oral load) in control subjects and 36.0 +/- 8.8% in diabetic patients (p less than or equal to 0.05). The contribution to connecting peptide responses was 58.4 +/- 7.6% in control subjects and 7.6 +/- 14.5% (p less than or equal to 0.05) in diabetic patients. Ratios of integrated insulin to connecting peptide responses suggest a reduced (hepatic) insulin extraction in control subjects after oral as compared to intravenous glucose. This was not the case in diabetic patients. Immunoreactive gastric inhibitory polypeptide responses were not different between control subjects and diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Preserved incretin effect after complete surgical denervation of the pancreas in young pigs.

Plasma insulin responses to intragastric (i.g.) (1.5 g/kg b.wt.) and "isoglycemic" intravenous (i.v.) glucose were measured in ten unanesthetized young pigs to assess the contribution of gastrointestinal factors to the total insulin secretion as observed after i.g. glucose. The participation of nerves was estimated by comparing metabolic tests performed before and after total surgical pancreatic denervation. In the five animals which survived the procedure, 52.6% of the insulin response after i.g. glucose was calculated to be due to incretion factors, a value similar to the 54.8% found in the preoperative series (with intact pancreatic innervation). The response of IR-GIP to i.g. glucose was not significantly different between preoperative and postoperative tests, although a subtotal duodenectomy had to be performed in the course of the operation designed to completely denervate the pancreas. Intragastric and i.v. (also tested by bolus glucose injection) glucose tolerance was almost identical before and after the operation. It was concluded that nerves do not seem to play a major role in mediating the incretin effect in pigs. Hormonal factors, including GIP, appear to be more important.

Animals↗
PubMed1983

Disturbances of the entero-insular axis.

The entero-insular axis comprises direct substrate stimulation of the islet cells by the absorbed nutrients and signal transmission by endocrine factors and nerves. The extent of neural influences has not yet been evaluated. GIP is the main incretin candidate. GIP release is dependent on nutrient absorption. Therefore, GIP abnormalities occur in a large number of gastrointestinal and metabolic diseases. These secondary changes are rarely of clinical significance. GIP hypersecretion may, however, contribute to the increased lipogenesis in obesity and the hypoglycemia in the late dumping syndrome. In type II diabetes hyper- and hyposecretion of GIP has been found but no correlation between GIP and insulin response. GIP abnormalities are not identical with disturbances of the entero-insular axis. These can only be evaluated by estimating the incretin effect (comparing the insulin response to oral glucose with the insulin response to an isoglycaemic iv glucose infusion). A decreased incretin effect has been observed in patients with jejuno-ileal bypass and in type II diabetes. In neither condition was a correlation found between incretin effect and GIP response. It is concluded that disturbances of the entero-insular axis are rarely explained by GIP abnormalities. Therefore, other humoral gut factors must exist. Also the neural part of the entero-insular axis requires exploration in health and disease.

Animals↗
PubMedDate not supplied

A new liquid homogeneous assay for HDL cholesterol determination evaluated in seven laboratories in Europe and the United States.

We evaluated a new liquid homogeneous assay for the direct measurement of high density lipoprotein cholesterol (HDL-C Plus) in seven laboratories. The assay includes two reagents which can be readily used in most available clinical chemistry analyzers. The total CVs of the new method were below 4.6% and the bias in relation to the designated comparison method was below 3.9%. The total error ranged between 4 to 7%. HDL-C values determined by this method were in good agreement with those obtained by the old homogeneous assay using lyophilized reagents, and other homogeneous and precipitation assays (0.944 < r < 0.996). The assay was linear up to at least 3.89 mmol/l HDL-C. Hemoglobin did not interfere, whereas in icteric samples slight deviations were observed. Lipemia up to 11.3 to 22.6 mmol/l triglycerides did not interfere with this homogeneous HDL-C assay. In samples of patients with paraproteinemia, discrepant results were seen. This liquid homogeneous HDL-C assay was easy to handle and produced similar results in all laboratories participating in this study. This method will enable clinical laboratories to reliably measure HDL-C for risk assessment of coronary heart disease.

Artifacts↗
PubMedDate not supplied

Tumorigenic potential and the molecular mechanism of the carcinogenic effect exerted by 2-nitroanisole.

The host-mediated in vitro/in vivo assay system was used to evaluate the tumorigenic potential of the aromatic nitro compound 2-nitroanisole (2-NA). After intraperitoneal administration of the compound, resident macrophages were recovered by peritoneal lavage from treated and untreated mice and cultured in soft agar. 2-NA was shown to be carcinogenic, and the tumorigenic potential was evaluated. Additionally, by establishment of a transformed peritoneal macrophage cell line, the underlying molecular mechanism of 2-NA's carcinogenic effect was studied.

Animals↗
PubMedDate not supplied

Elevated lipoprotein(a) and fibrinogen levels [corrected] increase the cardiovascular risk in continuous ambulatory peritoneal dialysis patients.

OBJECTIVE: To analyze the relationship between lipoprotein(a) [Lp(a)] and fibrinogen as potential cardiovascular risk factors in patients on continuous ambulatory peritoneal dialysis (CAPD). PATIENTS: A total of 47 uremic patients receiving CAPD, 21 with coronary artery disease (CAD), 26 without CAD. MEASUREMENTS: Lp(a) levels were determined by an immunoradiometric assay. Since Lp(a) serum concentrations vary depending on the size, apoprotein(a) [apo(a)] isoforms were determined (Westernblot). Fibrinogen was quantified according to Clauss. RESULTS: The mean Lp(a) serum concentration was 43 +/- 5 mg/dL (SEM) (median 33 mg/dL) in CAPD patients and 21 +/- 2 mg/dL (8 mg/dL) in controls (p < 0.01). Patients with low molecular weight apo(a) isoforms exhibited substantially elevated Lp(a) levels when compared with patients with high molecular isoforms (p < 0.01). In addition, we found elevated fibrinogen levels in the CAPD patients (538 +/- 61 mg/dL) compared with healthy controls (288 +/- 46 mg/dL). Twenty-one CAPD patients (45%) were suffering from CAD. Patients with CAD had higher Lp(a) levels (54 +/- 5 mg/dL vs 34 +/- 4 mg/dL) as well as higher fibrinogen concentrations (628 +/- 59 mg/dL vs 459 +/- 46 mg/dL). Furthermore, a positive correlation between the fibrinogen levels and the Lp(a) serum concentration was observed (r = 0.45, p = 0.01). CONCLUSION: We suggest that elevated Lp(a) levels are influenced by the allelic variation of the apo(a) isoform. In addition to the typical dyslipidemia found in CAPD patients, high levels of Lp(a) and fibrinogen may contribute to the elevated risk of coronary artery disease and other cardiovascular complications.

Adult↗