Evidence for human orosensory (taste?) sensitivity to free fatty acids

Accumulating evidence suggests dietary fatty acids (FAs) may be sensed in the oral cavity. However, the effective cues have not been characterized. In particular, influences from other sensory cues have hampered identification of an independent gustatory contribution. Experiment 1 examined techniques to minimize the formation of FA oxidation products and improve the homogeneity of water/lipid emulsions to be used as stimuli in Experiment 2, a psychophysical study to determine FA detection thresholds in humans. Through sonication of chilled samples held in polypropylene labware and the addition of 0.01% ethylenediaminetetraacetic acid, calcium disodium salt, homogenous emulsions of unoxidized linoleic and oleic FAs were obtained. Spectrophotometric analysis revealed no oxidation product formation over a 24-h period. Coupled with these techniques, a masking approach was used to minimize other sensory cues imparted from linoleic, oleic, and stearic FAs. Concentration ranges from 0.00028% to 5% (w/v) were prepared in mixtures with 5% mineral oil (w/v) and 5% gum acacia (w/v) to mask lubricity and viscosity effects, respectively. Testing was conducted under red light with nares blocked to eliminate visual and olfactory cues. Oral rinses with 20 ppm capsaicin were administered to desensitize participants to selected irritation effects prior to remeasuring linoleic acid detection thresholds. To determine if the effective stimulus was an oxidation product, oxidized linoleic acid was included among the test stimuli. Detection thresholds were obtained using a 3-alternative, forced-choice ascending-concentration presentation procedure. The mean detection threshold for linoleic acid pre-desensitization was 0.034 +/- 0.008%, for linoleic acid post-desensitization was 0.032 +/- 0.007%, for oleic 0.022 +/- 0.003%, for stearic 0.032 +/- 0.005%, and oxidized linoleic 0.025 +/- 0.005%. The results suggest that linoleic, oleic, stearic, and oxidized linoleic acids are detectable in the oral cavity of humans with minimal input from the olfactory, capsaicin, and viscosity-assessing tactile systems.     

Effects of moderate ammonium enrichment on three submersed macrophytes under contrasting light availability

1. Increased ammonium concentrations and decreased light availability in a water column have been reported to adversely affect submersed vegetation in eutrophic waters worldwide. 2. We studied the chronic effects of moderate enrichment (NH₄–N: 0.16–0.25 mg L^?1) on the growth and carbon and nitrogen metabolism of three macrophytes (Ceratophyllum demersum, Myriophyllum spicatum and Vallisneria natans) under contrasting light availability in a 2‐month experiment. 3. The enrichment greatly increased the contents of free amino acids and nitrogen in the shoot / leaf of the macrophytes. This indicates that was the dominant N source for the macrophytes. 4. Soluble carbohydrate contents remained relatively stable in the shoot / leaf of the macrophytes irrespective of the treatments. Under ambient light, the starch contents in the shoot / leaf of C. demersum and M. spicatum increased with enrichment, whereas V. natans did not exhibit any change. The starch contents decreased in C. demersum, increased in M. spicatum and remained unchanged in V. natans after the combined treatment of enrichment and reduced light. 5. The enrichment did not affect the growth of the three macrophytes under the ambient light. However, it did suppress the growth of C. demersum and M. spicatum under the reduced light. The results indicate that a moderate enrichment was not directly toxic to the macrophytes although it might change their viability in eutrophic lakes in terms of the carbon and nitrogen metabolism.     

Biochemical analysis of two cell surface glycoprotein complexes, very common antigen 1 and very common antigen 2. Relationship to very late activation T cell antigens

Two mouse monoclonal antibodies (mAb), AJ2 and J143, define two related human cell surface protein complexes, very common antigen 1 (VCA-1) and very common antigen 2 (VCA-2). In the present report, these complexes have been defined with respect to: (i) subunit arrangement; (ii) monoclonal antibody binding sites; (iii) carbohydrate content; (iv) homology to other cell surface protein complexes; and (v) possible functional roles. Analysis of the antigens from a human melanoma cell line, MeWo, reveals that VCA-1 is a noncovalently linked heterodimer of 170- and 140 (designated 1401)-kDa polypeptides. mAb AJ2 reacts with an epitope on the 1401-kDa polypeptide. VCA-2 is composed of the same 1401-kDa polypeptide as VCA-1 and another 170-kDa species; this 170-kDa species consists of a second distinct 140-kDa (designated 140(2)) and a 30-kDa polypeptide which are disulfide-bonded. Indirect evidence indicates that mAb J143 reacts with an epitope on this 170-kDa complex. Peptide mapping has shown that the complexes are members of a family of cell surface proteins that include antigens present on activated T cells (designated very late activation antigens). Since VCA-2 is found predominantly on the basal membrane of adherent cells and its expression increases 12-fold when HUT-102 lymphoblastoid cells are grown as an adherent cell culture, we suggest that VCA-2 plays a role in cellular adherence.     

6-Amino quinazolinedione sulfonamides as orally active competitive AMPA receptor antagonists

A new set of quinazolinedione sulfonamide derivatives as competitive AMPA receptor antagonist with improved properties compared to 1 is disclosed. By modulating physico-chemical properties, compound 29 was identified with a low ED(50) of 5.5mg/kg in an animal model of anticonvulsant activity after oral dosage.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.