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Nailfold capillary microscopy patterns in 22 patients with mixed connective tissue disease (MCTD) were compared with those of 21 patients with systemic lupus erythematosus (SLE) and 30 patients with systemic sclerosis (scleroderma [SD]). Microvascular data were classified blindly as follows: normal, nonspecific abnormalities, SD pattern, and SLE pattern, with special attention to the presence of dystrophic, branched "bushy" capillary formations. Of the 22 patients with MCTD, 63.6% had an SD pattern, 22.7% had an SLE pattern, 13.6% had nonspecific abnormalities, and 72.7% had bushy capillary formations. Compared with SLE microangiopathy, MCTD microangiopathy exhibited significantly greater capillary loss (P less than 0.05), more frequent SD patterns (P less than 0.001), and more frequent bushy capillaries (P less than 0.001). Compared with SD patients, MCTD patients displayed less frequent SD patterns (P less than 0.02) and more frequent bushy capillary formations (P less than 0.01). The presence of bushy capillaries was suggestive of MCTD. For diagnostic purposes, bushy capillaries displayed 72% sensitivity, 80% specificity, and 87.2% negative predictive value. The quantitative and qualitative expressions of microangiopathy were different in MCTD and SLE, respectively. This supports the hypothesis that each disease is a distinct entity. Nevertheless, there were many resemblances between MCTD and SD, which implies that MCTD is possibly a clinical form of SD.

When added in vitro, insulin exerts little or no effect on the metabolism of arterial media. However, indirect evidence suggests that an in vivo exposure of arterial tissue to insulin stimulates its metabolism. To evaluate the possibility that hemodynamic forces existing only in vivo may account for this difference, we studied the effect of brief (9-minute) exposures to insulin of isolated rat thoracic aorta perfused in situ at low (34 mm Hg = 4.6 kPa) and high (70 mm Hg = 9.4 kPa) static pressures. After perfusion, incorporation of glucose-derived 14C into CO2 and lipids, and production of lactate by incubated aortic tissue, were measured. At low perfusion pressure, insulin did not affect the metabolism of the media but strongly stimulated all aspects of the glucose metabolism of the adventitia. At high pressure, insulin again stimulated the adventitia but now also significantly stimulated (+66%) the synthesis of glucose-derived lipids by the media; production of CO2 and lactate by the media did not increase significantly. These results indicate that insulin directly stimulates at least one pathway of glucose metabolism by the media; and that hemodynamic forces are an important factor in determining the response of aortic media to insulin.

The action of trimethylcolchicinic acid on the synthesis and excretion of proteoglycans has been studied on the L cell strain. The incorporation of precursors has been measured, and proteoglycans produced in the culture medium have been extracted and their concentration determined. The mucopolysaccharide components have been studied by electrophoresis. Control cultures produce hyaluronic acid, dermatan sulfate and very low concentrations of chondroitin 4-sulphate or 6-sulphate. Cultures treated with trimethycolchicinic acid (4 mu g/ml) produce hyaluronic acid, very high concentrations of chondroitin 4-sulphate or 6-sulphate and only traces of dermatan sulphate. So, trimethylcolchicinic acid does not modify the synthesis of hyaluronic acid: it considerably increases the production of chondroitin 4-sulphate or 6-sulphate and inhibits the production of dermatan sulphate. Protein fraction of the proteoglycans is proportionally increased in treated cultures, but there is no marked difference between amino acid concentrations of proteoglycans extracted from control and treated cultures. A slight fall in the cystine concentrations was the only change in the amino acid content of proteoglycans extracted from treated cultures. A hypothesis to explain these results is discussed.

Hemodynamic parameters and systemic arterial compliance were measured in patients with arteriosclerosis obliterans of the lower limbs before and after acute administration of propranolol. Arterial compliance was evaluated from a simple viscoelastic model, enabling the calculation of diastolic drainage and diastolic blood flow as indices of the reservoir role of the larger arteries in overall circulation. In comparing basal conditions with normal subjects of the same age, patients with arteriosclerosis obliterans exhibited a significant decrease in arterial compliance (p less than 0.01) and heart rate (p less than 0.02) with a significant increase in systolic pressure (p less than 0.001). Diastolic drainage was increased (p less than 0.01) and was positively correlated with diastolic time (r = 0.73, p less than 0.001). Diastolic blood flow remained within normal ranges (52 +/- 2 vs 49 +/- 3 ml/m2/sec). After acute propranolol intravenous administration, heart rate and stroke volume decreased (p less than 0.001), while total peripheral resistance increased (p less than 0.001). Systemic arterial compliance and diastolic blood flow significantly decreased (p less than 0.01). The study provided evidence that in patients with arteriosclerosis obliterans, the diastolic blood flow was maintained in basal conditions despite the observed reduction in arterial compliance, and that intravenous propranolol administration decreased systemic arterial compliance and diastolic blood flow.