Rainbow trout (Oncorhynchus mykiss) which were air exposed for 60 s after exhaustive exercise initially had a much larger extracellular acidosis than trout which were only exercised. In both groups, however, plasma pH returned to normal by 4 h. Blood lactate concentrations were also greater in the air-exposed fish and continued to increase throughout the experiment. During air exposure, there was retention of carbon dioxide in the blood, and oxygen tension (Po2) and hemoglobin:oxygen carriage (Hb:O2) both fell by over 80%. After 30 min of recovery, however, blood gases resembled those in fish which were only exercised. Finally, survival after 12 h was 10% in control fish and 88% in the exercised fish but fell to 62 and 28% in fish which were air exposed for 30 and 60 s, respectively, after exercise. These results indicate that the brief period of air exposure which occurs in many "catch and release" fisheries is a significant additional stress which may ultimately influence whether a released fish survives.

We report an ultrasensitive time-resolved immunofluorometric assay (TRIFA) for prostate-specific antigen (PSA). The assay is an improvement of our previous report (Clin Chem 1993;39:2108-14) and includes the utilization of two monoclonal antibodies and a one-step incubation period, which greatly reduces analysis time. The new method demonstrates a superior lower analytical limit of detection (< or = 1 ng/L), a wide dynamic range, absence of a hook effect at 10(6) ng/L PSA, and equimolarity for free PSA and PSA-antichymotrypsin complex. Also, we have compared several aspects of our TRIFA with a commercially available third-generation assay (Immulite). An evaluation of breast tumor cytosol extracts from 315 patients shows PSA immunoreactivity > 15 ng/g of total protein in 28% and 23% by TRIFA and Immulite analysis, respectively. Both methods demonstrate a significant association between breast tumor PSA immunoreactivity and progesterone and estrogen receptor positivity (P <0.001). Analysis of serum samples obtained for monitoring of postradical prostatectomy patients reveals significant PSA changes at concentrations undetectable by conventional methods. The significance of these results as well as the potential applications of ultrasensitive PSA assays in breast and prostate cancers are discussed.

The relationship between body size, anaerobic capacity, and white muscle acid‐base and metabolite status was examined for two sizes of brook trout Salvelinus fontinalis and largemouth bass Micropterus salmoides. Resting muscle lactate, pH, HCO3−, and partial pressure of carbon dioxide (Pco2) were size‐independent in brook trout. After exercise, however, there was a significant positive relationship between the accumulation of both lactate and metabolic protons and body size in brook trout. In addition, there was a significant size‐dependent decrease in postexercise muscle pH, with larger trout experiencing a more severe drop in muscle pH. In contrast, the postexercise changes in muscle HCO3− and Pco2 remained size‐independent in trout. Having observed that anaerobic capacity (i.e., lactate production) apparently was affected by body size in trout, we measured the concentrations of two other anaerobic energy reserves—phosphocreatine (PCr) and ATP—in trout white muscle before and after exercise. Under resting conditions, large trout possessed greater concentrations of both ATP and PCr than smaller trout. After exercise, the levels of ATP and PCr decreased in all trout but were size‐dependent and size‐independent, respectively. Under resting conditions, muscle lactate, pH, HCO3−, and Pco2 remained size‐independent in largemouth bass. After exercise, white muscle lactate and metabolic proton concentrations increased and pH decreased in all bass; however, in contrast with brook trout, none of these variables were significantly related to body size. The results of our in vivo experiments therefore agree with the previously documented in vitro relationships between body size and glycolytic enzyme activities in different species of fish. In addition, these results may be important for fisheries management issues, such as catch‐and‐release fishing.

An in vivo-in vitro test system with high sensitivity to teratogens has been developed and validated. A single acute intra-peritoneal injection of teratogens (18) and non-teratogens (13) was administered to pregnant rats on the 12th day after fertilisation, and uteri were removed after 16 h by laparotomy. 34-36 Embryos somites were selected, and mid-brain (CNS) and fore-limb buds (LB) were dissected free and dispersed as single-cell suspensions in Ham's F12 culture medium. The cells were cultured as micromass cell islands for 5 days, and discrete foci of neuronal cells differentiated in CNS cultures and chondrocytes in LB cultures. After 5 days, differentiation as determined by number of stainable foci of differentiated cells and 3H-GABA incorporation in CNS or 35SO4 incorporation in LB and growth (as determined by total protein) were measured. Both differentiation and growth of CNS and LB cultures were markedly reduced following exposure of the dam to teratogens, whereas no significant effect was observed with non-teratogens. One teratogen (amaranth) and one non-teratogen (nitrilotriacetic acid) were classified as false negative and positive, respectively; the sensitivity of the test (proportion of teratogens correct) was therefore 92% and the specificity (proportion of non-teratogens correct) was 94%. Inhibition of growth and differentiation in the rat embryo cell cultures following maternal exposure forms the basis of a short-term in vitro test for teratogens.

The full extent and apportionment of aerobic and anaerobic contributions to energy transduction for membrane pumps associated with cellular pH regulation are very poorly understood. One way of approaching this problem at the cellular level is by using the nucleated erythrocyte as a model cell. Indeed, the aerobic and anaerobic capacity of salmonid erythrocytes and their β-adrenergic mediated pH regulation offers a model "pH regulating system" for examining cellular strategies of response to acute and (or) chronic changes in oxygen availability. Much of our work has focused on the balance between metabolic energy production and the maintenance of erythrocytic pH through primarily or secondarily active ionic exchange mechanisms at the cell membrane. Upon adrenergic stimulation, a rise in cyclic AMP activates the Na+–H+ exchanger, leading to cell alkalinization and an elevation of intracellular Na+. The increased Na+ evidently stimulates Na+,K+-ATPase activity and the increased ATP consumption is matched with aerobic energy production. The pHi that is subsequently established appears to be set by levels of poly anionic phosphates.