DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

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.     

Cross-reactivity patterns of murine cytotoxic T lymphocytes.

Cross-reactivity of TNP-immune, virus-immune, and alloreactive murine cytotoxic thymus-derived (T_c) cells was investigated at the level of target cell lysis. Alloreactive T_c cells cross-reacted on TNP-modified and unmodified third-party targets and on syngeneic TNP-modified targets but did not cross-react on syngeneic virus-infected targets. TNP-immune T_c cells showed marked cross-reactivity on certain allogeneic targets modified by TNP (loss of H-2 restriction) and also on certain unmodified allogeneic targets but did not cross-lyse virus-infected syngeneic targets. Targets treated with TNP-Sendai virus were not lysed by TNP-immune T_c cells, but T_c cells stimulated by cells treated with TNP-Sendai virus lysed such targets readily. These results are consistent with the view that T_c-cell recognition of foreign H-2 antigens and TNP-modified self-H-2 antigens are mechanistically similar (possibly via one receptor), whereas recognition of viral plus H-2 antigens is different (possibly via two receptors).Virus-immune T_c cells ubiquitously exhibited strong cross-reactivity on syngeneic TNP-modified targets using pox-, arena-, alpha-, myxo-, and paramyxoviruses for T_c-cell induction. The lysis of virus-infected targets by virus-immune T_c cells could be inhibited by cold TNP-modified competitors, thus establishing that some individual virus-immune T_c cells could recognize both types of target cells. This genuine cross-reactivity at the effector level was not observed at the level of induction of secondary responses, since the cross-reactive subset of virus-immune memory T_c cells could not be activated by TNP-modified stimulator cells but could be activated by virus-infected stimulators. These results implied that requirements for stimulation of precursor T_c cells are sometimes different from antigenic requirements for recognition and lysis of effector T_c cells.     

Cooperation between mouse T-cell subpopulations in the cell-mediated response to a natural poxvirus pathogen.

Irradiated CBA anti-DBA/2 cells (10⁶ cells/culture) suppressed the production of effector cells in cultures containing 10⁷ unprimed CBA (responder) and 10⁶ irradiated DBA/2 (stimulator) spleen cells per culture. The suppressive element was cellular and suppression was specific for the stimulating antigen. The suppressive activity resided in the cytotoxic cell population in that both suppressive and cytotoxic activities were found in cells of the same size range, predominantly in T-cells, were produced in response to similar doses of stimulator antigen, and were produced with the same time course following establishment of first sensitization cultures. Eventual suppression correlated with the cytotoxic activity introduced into second sensitization cultures by suppressor cells. The short-term cytotoxic activity and suppressor activity were both highly radioresistant. These studies indicate that the suppressor cells formed in an in vitro mixed lymphocyte culture are cytotoxic to stimulator cells.     

Delimitation of the maritime boundary in the gulf of Maine area

The compulsory dispute settlement regime included in the 1982 Law of the Sea Convention is recognized as one of the most comprehensive in a modern international convention. Yet, in the recent application of this regime, the question has arisen as to whether the procedural prerequisites associated with the LOS Convention's compulsory dispute settlement mechanism are so arduous as to avoid binding and compulsory jurisdiction in most instances. This article addresses that question by examining, in particular, the reasoning of the Southern Bluefin Tuna arbitration tribunal, which found Article 281 of Section 1 of the LOS Convention to bar jurisdiction to the compulsory dispute settlement mechanism prescribed by the Convention, and offers suggestions as to how states might distinguish or overcome the barriers imposed by the Southern Bluefin Tuna tribunal in future cases.     

Progesterone and oestrogen receptors in the female genital tract throughout pregnancy in tammar wallabies

The tammar, Macropus eugenii, is a monovular macropodid marsupial which has a post-partum oestrus and an 11 month embryonic diapause. Progesterone and oestradiol cytosol receptors were measured by Scatchard analyses and single point analysis in the lateral vagina, endometrium and myometrium of the gravid and contralateral non-gravid uterus throughout pregnancy, immediately after parturition and during seasonal reproductive quiescence. In endometrial tissues, both progesterone and oestradiol receptors doubled in concentration in both gravid and non-gravid uteri between day 0 and day 5 of pregnancy, coinciding with previously described peak values in peripheral plasma progesterone and oestrogen. Receptor concentrations in endometrial tissue during seasonal quiescence were not significantly different from those immediately after reactivation. After day 12 of pregnancy, downregulation of both progesterone and oestradiol cytosolic receptors occurred concomitant with the increase in progesterone in the peripheral plasma. However, there was a unilateral increase in oestradiol receptor concentrations in endometrium obtained from the non-gravid uterus between day 25 of the 26.5 day gestation and immediately after parturition. Myometrial receptor concentrations mirrored those of the endometrium but were lower. Concentrations of progesterone receptor in the lateral vaginae were at the lower limit of detection, while the oestradiol cytosol receptor concentrations were even lower in this tissue. Thus, the steroid receptor concentrations provide another example of local unilateral endocrine responses in the reproductive tract of the tammar. These results also indicate that the downregulation of progesterone and oestradiol receptors that occurs in both uteri in mid- and late-pregnancy is selectively and locally reversed before parturition in the non-gravid endometrium in response to the local effects of follicular oestradiol from the ipsilateral ovary.     

A spatial analytical approach for selecting reintroduction sites for burbot in English rivers

1. Availability of suitable habitat is a prerequisite for species reintroduction success, and to ensure population persistence, investigations of a species’ habitat utilisation throughout its life history should be conducted as part of a feasibility study. 2. Habitat utilisation models for burbot, Lota lota, developed using data from field studies conducted in France and Germany and information from the literature were used to assess the feasibility of reintroducing burbot into rivers of its former native range in eastern England. 3. Per cent tree roots, aquatic vegetation and flow types were important predictors of adult burbot abundance. Furthermore, the habitat utilisation models were supplemented with information from the literature, which suggested that off‐channel habitat such as wetlands and backwaters is important for spawning and nursery stages. 4. An assessment of the habitat availability in the rivers of the burbot’s former native range using variables related to spawning and nursery and adult life stages showed that although adult habitat was widely distributed, the availability of spawning and nursery habitat was less abundant, potentially limiting successful reestablishment. 5. Potential suitable habitat was concentrated in the central and southern areas of the species’ former English distribution. Overall, rivers of the burbot’s former range potentially afford suitable habitat to sustain a reintroduced population. However, sites should be preferentially selected on the basis of having appropriate spawning and nursery areas.