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S T Ellis

Publications and source records attributed to S T Ellis.

13 recordsLinked to original sources
PubMed1988

Sodium-dependent D-glucose transport after proximal small intestinal resection in rat.

Massive small intestinal resection results in both structural and functional changes in the residual small bowel. Sodium-dependent D-glucose transport was examined in brush-border membrane vesicles derived from the terminal 20-30 cm of ileal mucosa of male Sprague-Dawley rats, 2 and 6 wk after 66% proximal jejunoileal resection or jejunoileal transection. Kinetic characteristics for sodium-dependent D-glucose transport were investigated with rapid filtration under conditions of a zero-trans, 100 mM cis-NaSCN gradient. Mucosal weight, protein, and DNA content were increased in the residual terminal intestinal segment compared with transected controls, whereas morphometric studies revealed increased villus and crypt heights as well as an increased mitotic index. Mean kinetic transport parameters at 6 wk after proximal small bowel resection revealed two saturable systems in the distal residual ileum: first, a low-affinity, high-capacity system with a Km of 0.19 +/- 0.03 mM and a Vmax of 0.48 +/- 0.04 nmol.mg protein-1.min-1; and second, a high-affinity, low-capacity system with a Km of 0.009 +/- 0.001 mM and a Vmax of 0.105 +/- 0.016 nmol.mg protein-1.min-1. In contrast, negligible sodium-dependent D-glucose transport was detected in the most distal ileum in control animals or animals 2 wk after resection or 2 and 6 wk after transection. Thus adaptational changes including mucosal hyperplasia and the appearance of two sodium-dependent D-glucose brush-border membrane vesicle transport systems occur in the residual distal intestine after massive proximal small bowel resection.

Animals↗
PubMed1988

Efficacy and specificity of monoclonal antibodies to progesterone in preventing the establishment of pregnancy in the mouse.

Anti-progesterone monoclonal antibody prevents the establishment of pregnancy in BALB/c mice by the prevention of implantation when injected i.p. 32 h after mating. To determine the specificity of this effect, mice were injected with immune and non-immune purified mouse immunoglobulins. The results show that anti-implantation efficacy was due to high-affinity antibody which bound progesterone since two further mouse immunoglobulin (Ig) G1 preparations, mouse IgA and mouse IgM which failed to bind the steroid, had no effect on pregnancy rates. From a panel of anti-progesterone monoclonal antibodies, six with a high affinity (affinity constant, 0.24-0.80 litres/nmol) and specificity for progesterone were selected for additional studies. Anti-implantation efficacy for five antibodies was similar, with a 50% effective dose within the range of 0.8-2.0 nmol. Antibody reached high concentrations in plasma within 12 h after i.p. injection, and declined with a half-life of about 80 h. Purified F(ab')2 fragments of antibody also bound progesterone, but were less effective than the native molecule in blocking pregnancy. The results show that implantation in the mouse can be blocked by a high-affinity antibody that binds progesterone and which is removed from the blood at a slow rate.

Animals↗
PubMed1986

Use of a new and rapid milk progesterone assay to monitor reproductive activity in the cow.

A new and rapid enzyme-amplified immunoassay (AELIA) has been developed for the measurement of progesterone in milk. The AELIA system is a non-isotopic method that gives results within 35 minutes. Milk progesterone concentrations measured in 10 cows sampled daily at various stages of the reproductive cycle were very similar to those recorded by a validated radioimmunoassay. The results show that the speed and sensitivity of the AELIA system would make it possible to diagnose pregnancy rapidly at about 24 days after insemination, to predict the onset of behavioural oestrus from decreasing progesterone values during the third week after a preceding oestrus, and to obtain a daily record of milk progesterone levels in animals treated for infertility of ovarian origin.

Animals↗
PubMed1984

The alloantigenic organization of RT1Aa, a class I major histocompatibility complex molecule of the rat.

Over 300 monoclonal IgG alloantibodies have been prepared against RT1Aa , the class I major histocompatibility complex molecule of the DA rat. In this study a combination of techniques is exploited to show that all these antibodies can be allocated to 9 antigenic sites which form a continuous antigenic surface, that is, no site is completely isolated from the rest. The results suggest that techniques for the identification of antigenic sites using competitive inhibition of monoclonal antibody binding are generally valid, in the sense that competition between antibodies appears most commonly to represent competition between combining sites for a structural feature of the antigenic surface. From the distribution of antibodies between sites, it is clear that the RT1Aa molecule has three immunogenic areas against which nearly all the antibodies studied were directed. Of these areas one is both antigenically complex, consisting of four closely spaced sites, and remarkably immunodominant. Antibodies directed at sites between the major areas are extremely rare.

Animals↗