Olfactory discrimination of amino acids in brown bullhead catfish.

Olfactory discrimination of amino acids was investigated in brown bullhead catfish (Ameiurus nebulosus). Based on the magnitude of the observed food search activity of catfish conditioned to single amino acids, the tested compounds were classified as being detected by the catfish as equal to, similar to, or different from the conditioned stimulus. L-Proline (L-Pro)-conditioned brown bullhead catfish discriminated all amino acids from L-Pro, but catfish conditioned to L-valine (L-Val) and L-isoleucine (L-Ile) did not discriminate L-Val from L-Ile nor L-Ile from L-Val; however, all other amino acids tested were always discriminated from these two compounds. Catfish conditioned to L-alanine (L-Ala) discriminated basic, acidic and several neutral amino acids with long side-chains (LCNs) from L-Ala; however, they did not always discriminate L-Ala from all neutral amino acids with short side-chains (SCNs). The L-norleucine (L-nLeu)-conditioned fish responded to L-norvaline (L-nVal), L-methionine (L-Met) and L-Ala similarly to L-nLeu, indicating that these amino acids are detected as similar or identical to L-nLeu. L-nLeu was, however, discriminated from L-Ala in L-Ala-conditioned catfish. Interestingly, L-leucine (L-Leu) was discriminated from the conditioned stimuli, L-Ala, L-Ile and L-Val, indicating independent receptors for L-Leu. Although conditioned catfish discriminated other amino acids from L-arginine hydrochloride (L-Arg), in some tests they were unable to discriminate L-Arg from L-lysine hydrochloride (L-Lys). These results imply the existence of independent olfactory receptive pathways for: (i) L-Pro; (ii) basic amino acids (L-Arg and L-Lys); (iii) L-Leu; (iv) other neutral amino acids with branched side-chains (L-Ile and L-Val); (v) neutral amino acids with long linear side-chains (L-nLeu, L-nVal and L-Met); (vi) neutral amino acids with short side-chains; and (vii) amino acids with sulfhydryl groups (L-Cys and L-homoCys).

Alternative statistical method for detecting changes in spontaneous activity of single olfactory receptor cells.

An statistical method for analysis of event data analysis, common in electrophysiological investigations of activities of olfactory receptor neurons, is proposed. The method is based on the analysis of the slopes of cumulative frequency distribution function. During the spontaneous activity the distribution function is linear which indicate that probability density distribution is uniform. During the chemical stimulation, the density of action potentials is either increased (excitation--E) or decreased (suppression--S), causing the observable change of the slope. The slope at each event is evaluated by piecewise linear regression. The type (E or S) and time of change of the slope can be determined, providing information for further statistical analyses. Graphically supported computer program (in S-PLUS) is available for interactive or routine use.

Cathepsin B, a prognostic indicator in lymph node-negative breast carcinoma patients: comparison with cathepsin D, cathepsin L, and other clinical indicators.

New prognosticators are needed for breast cancer patients after the initial surgical treatment to make therapeutic decisions that ultimately will affect their DFS. These consist of specific proteolytic enzymes including lysosomal endopeptidases. In this study, the activity and protein concentrations of cathepsins (Cats) D, B, and L were measured in 282 invasive breast tumor cytosols. These potential biological prognostic indicators were compared with other histopathological parameters, such as tumor size, lymph node involvement, tumor-node-metastasis stage, histological grade, DNA analysis, and steroid receptors. CatD protein concentration correlated with lymph node involvement. CatB and CatL levels correlated significantly with Scarf-Bloom-Richardson histological grade and were also higher in estrogen-negative tumors, and CatB was higher in larger tumors. As prognostic markers, CatB concentration was significant for increased risk for recurrence in the entire patient population and specifically also in lymph node-negative patients as follows: high CatB concentration (above 371 micrograms/g) in tumor cytosols was significant (P < 0.00) for high risk of recurrence but was of only borderline prognostic significance (P < 0.06) for overall survival of all patients. In lymph node-negative patients, CatB (above 240 micrograms/g, P < 0.003) was highly significant for recurrence-free survival, followed by CatL (above 20 micrograms/g, P < 0.049) and CatD (above 45 nmol/g, P < 0.044) concentrations. For overall survival of node-negative patients, only CatB was a significant (P < 0.014) prognosticator. We conclude that CatB is useful as a prognostic indicator in lymph node-negative patients. This suggests that selective adjuvant therapy should be applied in this lower risk group of patients when high levels of CatB are determined.