Barbara D. Smith

Collagen synthesis has been examined in primary cultures of human corpus cavernosum smooth muscle cells (HCCSMC), the major mesenchymal cell type of the corpus cavernosum. These cultures were grown from human surgical specimens and characterized by morphological and biochemical characteristics. These cells express mRNA for transforming growth factor-beta 1 (TGF-beta 1), a major regulator of extracellular matrix synthesis, as well as all three subtypes of TGF-beta receptors. Human corpus cavernosum smooth muscle cells primarily synthesize types I and III fibrillar collagen. Treatment of HCCSMC with exogenous TGF-beta 1 (80 pM.) induced a 2.5- to 4.5-fold increase in the synthesis of types I and III collagen and resulted in detectable levels of type V/XI collagen. Treatment of HCCSMC with the eicosanoid PGE1 in combination with TGF-beta 1 suppressed the induction of collagen synthesis by TGF-beta 1 in a dose-dependent manner with concomitant decreases in types I, III and V/XI collagen. The expression of TGF-beta 1 mRNA as well as types I and II TGF-beta receptors was induced by exogenous TGF-beta 1. Transforming growth factor-beta 1 mRNA induction was suppressed by PGE1. These data suggest that prostaglandins and TGF-beta 1 may play a key role in modulation of collagen synthesis in the corpus cavernosum, and in the regulation of fibrosis of the corpus cavernosum.

We examined the effects of insulin and insulin-like growth factor I (IGF-I) on the production of collagen by cultures of human embryonic lung fibroblasts. Insulin at 20 ng/ml increased collagen accumulation by 58% and total protein formation by 18%. At 2 micrograms/ml, insulin increased collagen production by 2- to 3-fold and total protein production by 2-fold. The mRNA levels for alpha 1(I) and alpha 1(III) collagen chains were elevated by insulin compared with untreated control values. IGF-I at 10 ng/ml increased collagen production 2-fold. IGF-I at 100 ng/ml maximally increased collagen production 3-fold. A specific antibody to the IGF-I receptor (alpha IR-3) caused a concentration-related decline in insulin-induced collagen formation. The addition of antibody at 1 micrograms/ml, resulted in 80% inhibition of insulin-induced collagen accumulation. Higher levels of antibody were required to inhibit IGF-I mediated collagen formation. The presence of antibody (alpha IR-3) also blocked fibroblast proliferation stimulated by epidermal growth factor plus insulin. These data show that insulin-induced collagen formation is mediated primarily through an interaction with the IGF-I receptor. The modulation of extracellular matrix production by insulin may influence the repair of tissue injury and the development of the accelerated atherosclerosis that accompanies the diabetic state in humans.

1. Macrophyte and macroinvertebrate species richness, and the extent of aquatic vegetation, were surveyed in 51 newly created or renovated ponds in mid and west Wales, together with a range of environmental variables. These data are analysed in relation to management issues including pond size, rate of development, planting for oxygenation, stocking with fish and shading by riparian trees. 2. Richness of both plants and invertebrates increases with vegetated area, but the relationships are weak. Similarities among assemblages in ponds are low and not related to the proximity of the ponds. It is likely that two small ponds would together support more species than a single large pond. 3. New ponds are colonized rapidly by plants and invertebrates. There is no relationship between age and the number of species in ponds that were at least one year old, except for invertebrates in ponds that were isolated from other wetland. As expected, the extent of aquatic vegetation increases with age. 4. Minimum dissolved oxygen levels decrease with the cover of floating plants and with extent of vegetation in relation to pond size. 5. There is no evidence that stocking with fish (mainly salmonids at low densities) influences the total number of species of either macrophytes or macroinvertebrates. However, the number of anisopteran (Insecta: Odonata) species is lower in stocked ponds and the number of trichopteran (Insecta) species is higher. 6. Macrophyte species richness increases with the percentage of the margin shaded by trees to a peak between 22% (emergent species) and 30% (submerged and floating species), and then declines. The number of species of invertebrates with short-lived flying adults (Odonata, Ephemeroptera, Trichoptera) decreases with the extent of riparian trees. Other invertebrates are unaffected. 7. The relationship between the survey results and existing management recommendations is discussed, emphasizing the need for field experiments to provide empirical support. © 1997 John Wiley & Sons, Ltd.