The cDNA of a novel matrix metalloproteinase, collagenase-3 (MMP-13) has been isolated from a breast tumor library (Freije, J. M. P., Diez-Itza, I., Balbin, M., Sanchez, L. M., Blasco, R., Tolivia, J., and Ló pez-Otin, C. (1994) J. Biol. Chem. 269, 16766 -16773), and a potential role in tumor progression has been proposed for this enzyme. In order to establish the possible role of collagenase-3 in connective tissue turnover, we have expressed and purified recombinant human procollagenase-3 and characterized the enzyme biochemically. The purified procollagenase-3 was shown to be glycosylated and displayed a M r of 60,000, the N-terminal sequence being LPLPSGGD, which is consistent with the cDNA-predicted sequence. The proenzyme was activated by p-aminophenylmercuric acetate or stromelysin, yielding an intermediate form of M r 50,000, which displayed the N-terminal sequence L 58 EVTGK. Further processing resulted in cleavage of the Glu 84 -Tyr 85 peptide bond to the final active enzyme (M r 48,000). Trypsin activation of procollagenase-3 also generated a Tyr 85 N terminus, but it was evident that the C-terminal domain was rapidly lost, and hence the collagenolytic activity diminished. Analysis of the substrate specificity of collagenase-3 revealed that soluble type II collagen was preferentially hydrolyzed, while the enzyme was 5 or 6 times less efficient at cleaving type I or III collagen. Fibrillar type I collagen was cleaved with comparable efficiency to the fibroblast and neutrophil collagenases (MMP-1 and MMP-8), respectively. Unlike these collagenases, gelatin and the peptide substrates Mca-ProLeu-Gly-Leu-Dpa-Ala-Arg-NH 2 and Mca-Pro-Cha-GlyNva-His-Ala-Dpa-NH 2 were efficiently hydrolyzed as well, as would be predicted from the similarities between the active site sequence of collagenase-3 (MMP-13) and the gelatinases A and B. Active collagenase-3 was inhibited in a 1:1 stoichiometric fashion by the tissue inhibitors of metalloproteinases, TIMP-1, TIMP-2, and TIMP-3. These results suggest that in vivo collagenase-3 could play a significant role in the turnover of connective tissue matrix constituents.

Activation of platelets by collagen is mediated by the complex glycoprotein VI (GPVI)/Fc receptor γ (FcRγ chain). In the current study, the role of 2 Src family kinases, Fyn and Lyn, in GPVI signaling has been examined using murine platelets deficient in one or both kinases. In the fyn−/−platelets, tyrosine phosphorylation of FcRγ chain, phopholipase C (PLC) activity, aggregation, and secretion are reduced, though the time of onset of response is unchanged. In the lyn−/−platelets, there is a delay of up to 30 seconds in the onset of tyrosine phosphorylation and functional responses, followed by recovery of phosphorylation and potentiation of aggregation and α-granule secretion. Tyrosine phosphorylation and aggregation in response to stimulation by collagen-related peptide is further attenuated and delayed in fyn−/−lyn−/−double-mutant platelets, and potentiation is not seen. This study provides the first genetic evidence that Fyn and Lyn mediate FcR immune receptor tyrosine-based activation motif phosphorylation and PLCγ2 activation after the ligation of GPVI. Lyn plays an additional role in inhibiting platelet activation through an uncharacterized inhibitory pathway.

The prevalence of symptomatic sensorimotor polyneuropathy has been determined in a population of 382 insulin-treated diabetic subjects aged 15-59 yr. Forty-one subjects (10.7%) were found to have diabetic neuropathy, according to strict diagnostic criteria that required the presence of symptoms and signs of nerve dysfunction in the absence of peripheral vascular disease. There was a significant correlation between glycosylated hemoglobin levels and motor conduction velocity in the median and peroneal nerves in all subjects. This finding further emphasizes the importance of metabolic factors related to hyperglycemia in the impaired nerve function seen in diabetic patients.

The psychometric properties of a diabetes-specific treatment satisfaction scale were examined with responses from 128 adults with insulin-dependent diabetes who had used one of three treatment options for a period of 12 months. The reliability of the seven-item measured was found to be satisfactory (Cronbach's Alpha = 0.76) and factor analyses indicated three useful sub-scales (Perceived General Management; Perceived Compatibility with Lifestyle; Perceived Frequency of Hypo/hyperglycaemia). Use of the treatment satisfaction measure in a feasibility study of continuous subcutaneous insulin infusion (CSII) demonstrated the measure's ability to distinguish between three treatment groups (CSII, intensified conventional therapy and conventional therapy). People choosing to use CSII reported significantly greater improvements in satisfaction than those choosing either from of conventional therapy (F = 36.6; df 2, 125; p less than 0.001). If used in conjunction with measures of blood glucose control, the Treatment Satisfaction measure offers the opportunity for a more holistic appraisal of outcomes in studies evaluating and comparing treatments for insulin-dependent diabetes.

A new physical sign is described in the feet of a group of diabetic patients with ulcerating neuropathic problems, in which major venous distension of the veins on the dorsum of the foot and lower calf is seen. Elevation of the leg is required to an average height of 32.3 cm to cause collapse of these distended veins. It is suggested that this clinical sign indicates the presence of arteriovenous shunting in such neuropathic legs, and as such is a simple and useful measure of this abnormality.