[The value of highest quality ultrasound as a reference for ultrasound diagnosis]. / Diagnostische Wertigkeit einer internistischen Referenzsonographie (DEGUM-Stufe 3).

AIM: The aim of this study is to determine whether an additional ultrasound examination of DEGUM grade 3 (DEGUM 3) requested by examiners of DEGUM grade 1, 2 (DEGUM 1, 2) results in a diagnostic improvement. METHODS: From October 2000 till June 2003 our university internal medicine sonography unit examined 34 980 patients. In 211 cases DEGUM grade 1, 2 examiners requested a second opinion by DEGUM grade 3 examiners. 28 subjects were excluded because of unconfirmed diagnosis. Data of 183 patients with assured diagnoses were retrospectively analysed. We compared DEGUM 1, 2 findings with DEGUM 3 results regarding the accuracy of the firmed diagnosis. RESULTS: In 38.8 % (71 out of 183 subjects) the correct diagnosis was ascertained by DEGUM 1, 2. DEGUM 3 confirmed the correct diagnosis in 94.5 % (173 out of 183 subjects). DEGUM 3 changed 106 (57.9 %) findings of DEGUM 1, 2 and approved 77 findings (42.1 %). In total DEGUM 3 diagnosed incorrectly twice compared to DEGUM 1, 2. In comparison to the assured diagnosis DEGUM 3 diagnosed 10 subjects incorrectly. CONCLUSION: The reference ultrasound examination done by an examiner with DEGUM grade 3 significantly increases the diagnostic accuracy compared to the ultrasonic measurement done by DEGUM grade 1, 2 investigators.

Radiommunological measurement of leptin in plasma of obese and diabetic human subjects.

Studies in mice have identified the ob gene product, leptin, as a signaling factor regulating body weight homeostasis and energy balance. Defective production of the encoded protein may be one of the causes for the development of obesity. Using a high affinity antibody, that in immunohistochemical studies specifically stained human adipocytes, a radioimmunoassay was established and leptin immunoreactivity was quantified in plasma of lean and obese human subjects. Chromatographic analysis suggested that the immunoreactive material in plasma is identical to that found in extracts from human fat and represent a protein with a molecular size of approximately 16 kD. Fasting levels were measured in plasma of 75 lean and obese human subjects (body mass index (BMI) 17.7 - 87.3). The mean concentration of leptin in plasma of lean subjects (BMI < or = 28) was 69.3 +/- 36.9 fmol/ml plasma (mean +/- SD, n=27). The highest concentration measured in obese was 533.3 fmol/ml plasma. The levels showed a strong positive correlation with BMI (r=0.77, p<0.001). A subgroup of diabetic patients did not significantly differ in their leptin plasma levels from non-diabetic subjects with similar BMI.

Gene expression of natriuretic peptide receptors in myocardial cells.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones that serve to unload the heart through their effects on the kidney and vasculature. Whether the heart itself represents a site of action for these peptides is currently the subject of debate. Although functional studies indicate that ANP has some effects on isolated myocytes, several studies have been unable to detect binding of the hormone to these cells. The present study demonstrates that the genes for all three natriuretic peptide receptor (NPR) subtypes, NPR-A, NPR-B, and NPR-C, are expressed in the rat heart. For microlocalization of the receptor mRNAs in myocytes and nonmyocytic cells, a combination of cell isolation and reverse transcription-polymerase chain reaction (RT-PCR) was used. Cardiac myocytes were isolated by enzymatic dissociation of rat ventricular tissue, purified by density gradient centrifugation, and collected as single cells under microscopic control. Analysis by RT-PCR revealed the presence of transcripts for NPR-A as well as NPR-B and NPR-C. However, cGMP generation in purified myocytes was stimulated only by ANP and BNP, which specifically bind to NPR-A, whereas C-type natriuretic peptide (CNP, an NPR-B agonist) was ineffective. Therefore, rat ventricular myocytes appear to produce predominantly NPR-A. The expression of NPR-B may be low or even absent. The mRNAs for all three NPRs were also found in cultures of fibroblasts from the rat heart. In contrast to the myocytes, large increases in cGMP were observed in response not only to ANP but also to CNP.