Variation in stable-isotope ratios between fin and muscle tissues can alter assessment of resource use in tropical river fishes

Carbon and nitrogen stable-isotope ratios were compared of fin and muscle tissue from 15 fish species collected from seven headwater rivers in eastern and western Thailand. In addition, two-source stable-isotope mixing models were used to derive estimates of each fish's reliance on allochthonous and autochthonous energy based on fin and muscle tissues. Across the dataset, fish fin was enriched in ¹³ C relative to muscle by c. 1·5‰. Variation in δ¹⁵ N between tissues was below statistically significant levels. Estimates of autochthonous resource use calculated from fin tissue were on average 15% greater than those calculated from muscle. Linear mixed-effects models indicated that inter-tissue variation in estimates of resource use was predominantly related to inter-tissue variation in δ¹³ C. Fish fin is a credible and desirable alternative to tissues such as muscle or liver which require destructive sampling of fishes. Care must be taken, however, when estimating resource use or interpreting previous estimates of resource use derived from different tissues.

Trophic flexibility by roach Rutilus rutilus in novel habitats facilitates rapid growth and invasion success

Stable isotope and gut content analyses, in conjunction with backcalculated length-at-age estimates of growth, were employed to examine the relationship between trophic ecology and growth rate of a successful invader, Rutilus rutilus, in eight lakes in Ireland. The data revealed that R. rutilus was a trophic generalist in Irish lakes. It utilized a greater proportion of pelagic resources in mesotrophic lakes than in eutrophic lakes, potentially due to a greater density of benthic macroinvertebrates in eutrophic systems. The species was characterized by a large dietary and isotopic niche width and high temporal and spatial variations in diet. Growth rates were typical of those found in the native range of the species and were unrelated to either lake productivity or fish's diet. A generalist trophic ecology confers significant advantages on an invasive species, allowing it to exploit a variety of novel resources and fluctuations in prey availability.

Low cytochrome b variation in bream Abramis brama

Variability in cytochrome b (cytb) in European populations of bream Abramis brama was assessed. The cytb gene was found to be strongly conserved in A. brama relative to other cyprinid taxa. This limits the usefulness of this marker in examining geographical genetic structure in this species and raises interesting questions as to the recent evolutionary history of the species.

Heme oxygenase: expression in human retina and modulation by stress agents in a human retinoblastoma cell model system

PCR and Southern blot analyses demonstrate that mRNA for heme oxygenase (HO), a well known "stress protein" in a number of tissues, is present in human retina. Western and northern blots show that the protein and mRNA are also expressed in human Y-79 retinoblastoma cells in culture and that the HO enzyme is rapidly induced by its substrate, heme. Moreover, HO is also induced by two chemicals, sodium arsenite and menadione, that act as agents of oxidative stress. HO is the regulatory enzyme in the heme degradative pathway and an increase in its activity could lead to the accumulation of bilirubin, an antioxidant, in the cell at the expense of heme, a prooxidant. The HO pathway may thus be of importance in protecting the retina against oxidative stress in vivo. Moreover, the Y-79 culture system should provide an excellent model for use in examining stress mechanisms in retinal cells at a molecular level.

Expanding contractures of the tunica albuginea due to Peyronie's disease with temporalis fascia free grafts

We describe a procedure to expand contractures of the tunica albuginea by multiple full thickness relaxing incisions followed by inlay of tailored temporalis fascia free grafts. This technique is performed without resection of the tunica albuginea, although in the case of calcified plaques the calcifications themselves are removed, preserving the overlying tunica. Between September 1988 and February 1990, 12 patients have undergone this procedure, all of whom have greater than 3 months of followup and have experienced spontaneous erections within the first week postoperatively. Of the patients 11 resumed intercourse within 8 weeks of surgery and 1 required 12 weeks. No patient had sensory loss postoperatively and there has been no donor site morbidity. Correction of curvature was accomplished in all patients and there have been no recurrences within a maximal followup of 22 months. Within the limitations of such a small study we believe that there is evidence supporting this approach in potent patients with severe acquired penile curvature.

Effect of corticosteroid administration in ischemia--ischemic injury

In order to study the preservation of ischemic tissue, an in vivo end-artery model was designed using the rabbit ear. Ear surface-area necrosis and ear edema were quantitatively evaluated for 14 postoperative days in a total of 107 rabbits. The LD50 of ischemic injury was determined by effecting 8, 10, and 12 hours of circulatory arrest. Using a 12-hour ischemic interval in this model, methylprednisolone decreased edema formation (p less than 0.01) and dramatically halted the progression of ischemic injury to necrosis (p less than 0.05) when administered within 5 hours after the onset of ischemia and continued for 3 postoperative days. A single perioperative dose of methylprednisolone was ineffective in decreasing edema formation and preserving tissue. Administration of steroids greater than 5 hours after the onset of ischemia was similarly ineffective even when administered for 3 postoperative days.

Salvage of ischemic rabbit ear by BW-755C and steroids, but not by indomethacin

The effects of anti-inflammatory steroids and BW-755C (both of which inhibit the formation of prostaglandins and leukotrienes) were studied in ischemia-induced edema and necrosis of the rabbit ear utilizing an occlusion reperfusion model. The results were compared with cyclooxygenase inhibitors which selectively block the synthesis of prostaglandins without affecting leukotriene production. Significant inhibition of the progression of necrosis was observed with both methyl prednisolone and BW-755C. The cyclooxygenase inhibitors, naproxen and low-dose indomethacin had no effect on the progression of ear necrosis. By contrast, high-dose indomethacin significantly inhibited edema but accelerated the progression of necrosis.

Barrier Island Configuration

The 11 Virginia barrier islands are undergoing rapid changes in shore-line configuration. If this trend continues for another 100 years, two capelike features will develop. The process responsible for this island-chain pattern may be a standing edge wave trapped between Assateague Island and Cape Charles.

Evanescent delayed-type hypersensitivity: mediation by effector cells with a short life span

Four days after i.v. immunization of mice with optimal low doses of heterologous erythrocytes (2 x 10(5) RBC), strong delayed-type hypersensitivity (DTH) responses can be elicited in the footpad. At later intervals after immunization, DTH responsiveness is progressively diminished and replaced by 4-hr antibody-dependent reactions. These evanescent T cell-mediated DTH responses, which are progressively replaced by antibody-dependent reactions, resemble Jones-Mote type delayed hypersensitivity responses of humans and guinea pigs. Since higher doses of immunizing antigen activate suppressor mechanisms that inhibit DTH responses, we examined the possibility that the evanescence of DTH in mice immunized with an optimal low dose of antigen might also be due to suppression. Using techniques that could clearly demonstrate the suppression produced by high antigen doses, we failed to find evidence for either humoral or cellular suppression in optimally immunized mice with declining of DTH responses. Thus, it appears that the evanescence of produced by optimal low dose immunization with RBC may be due to an intrinsic short life span of the effector cells rather than to the activation of an identifiable shut-off mechanism.

Shoreline Forms and Shoreline Dynamics

Atlantic coast barrier-island shorelines are sinuous in plan view, with curvatures ranging in size from cusps to capes. The orientation of shoreline segments within the larger of these sinuous features (10 to 15 kilometers between apexes) is significantly related to shoreline dynamics.

Impact on hospital practice of liberalizing abortions and female sterilizations

The number of therapeutic abortions performed at the Vancouver General Hospital in 1969 was double the average number for the previous four years and in 1970 the total reached 1465. The more liberal attitude towards abortion has resulted in a decided reduction in the number of children available for adoption in the community. This policy has required a streamlining of the duties of the Therapeutic Abortion Committee and an alteration in the pattern of bed and operating-room utilization. By far the greatest number of abortions were performed on psychiatric-social grounds. The complication rate of 17% was influenced chiefly by the advanced duration of the gestation in a high proportion of cases. Gynecologists and hospitals must be prepared to assume their altered role in providing abortion and sterilization in today's society.