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Biomedical subjects

W Wan

Publications and source records attributed to W Wan.

24 records · Page 2Linked to original sources
PubMed1993

The effects of stress on splenic immune function are mediated by the splenic nerve.

Intermittent footshock (FS) suppresses immune function of spleen cells. To determine if the autonomic nervous system mediates this immunosuppression in spleen cells, we tested whether cutting the splenic nerve, which depletes splenic norepinephrine levels by 98-100% and eliminates catecholamine fibers, blocks the effects of stress. Splenic nerve sections, sham operations, or no surgery were performed on male Sprague-Dawley rats. Ten days later, rats were injected with sheep red blood cells (SRBC). Three days later, rats were placed in a chamber equipped with a shock grid. Foot shock (1.6 mA) was administered for 5 s on a VI 3.5 min schedule for 60 min. Each FS was preceded by a 15-s warning tone. Controls were treated identically except for the FS. The next day spleen cells were harvested and the number of IgM plaque-forming cells (PFCs) determined. For the sham and unoperated control animals, the number of PFCs was reduced for the stressed animals relative to the nonstressed controls, and there was no effect of the sham surgeries. In contrast, there was no difference between the stressed and nonstressed groups in which the splenic nerve had been sectioned, and their PFC response was comparable to the controls. Next we examined the effects of FS on the proliferative response to mitogens (PHA and ConA) following splenic nerve sections or sham operations. One week following surgery, animals were given a 60-min session of FS or exposed to the chamber/tone without FS. Rats were then killed, spleens harvested, and the proliferative response to mitogens determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Differential induction of c-Fos immunoreactivity in hypothalamus and brain stem nuclei following central and peripheral administration of endotoxin.

Lipopolysaccharide (LPS), an endotoxin associated with gram-negative bacteria, is a potent activator of the immune system. We have tested the effects of ICV infusions of LPS (10 ng) or Ringer's solution on the induction of the proto-oncogene protein c-Fos in the brain as well as plasma levels of corticosterone and splenic concentrations of norepinephrine (NE) and VIP. At 3 h post-ICV infusion of LPS, numerous labeled neurons were observed in the paraventricular nucleus (PVN) of the hypothalamus and the nucleus tractus solitarius (A2) region of the brain stem. Also, corticosterone and splenic NE and VIP levels were all elevated post-ICV LPS. Analysis of the time course for the induction of c-Fos protein in the brain following IP injections of LPS indicated that, relative to control injections, increased numbers of c-Fos-positive cells were detected in the PVN 0.5 h following IP injections (100 micrograms), peaked at 2-3 h postinjection, and then returned to control levels at later intervals. Additional dose-response data for IP LPS indicated a small increase in the number of labeled cells at a dose of 4.0 micrograms, and the number and staining intensity increased up to a dose of 100 micrograms. Corticosterone levels followed a similar pattern and were elevated at the 4.0 micrograms IP dose of LPS and increased to peak levels at 40 micrograms and higher. In contrast to ICV injections, splenic NE levels were unaltered by IP injections of LPS.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of enucleations and visual deprivation on adenosine A1 and A2 receptor binding in superior colliculus of rat.

Adenosine receptors of A1 and A2 subtypes on retino-collicular projections in rat were studied using [3H]cyclohexyladenosine ([3H]CHA), [3H]N-ethylcarboxamidoadenosine ([3H]NECA), and [3H]CGS 21680. Unilateral enucleation significantly reduced by 51% [3H]CHA binding to A1 sites, and by 42% the A1 component of [3H]NECA binding in contralateral SC. The binding of [3H]CGS 21680 and [3H]NECA to A2 sites was not significantly affected by enucleation procedures. No significant reductions in adenosine receptor binding were observed in SC from rats exposed to a dark environment for three weeks. The reductions in A1 but not A2 adenosine receptor binding strongly suggests that A1 sites are presynaptically located on retinal projections and are vulnerable to deafferentiation-, but not visual deprivation-induced decreases.

Adenosine↗
PubMed1990

Binding of the adenosine A2 receptor ligand [3H]CGS 21680 to human and rat brain: evidence for multiple affinity sites.

A new radiolabeled adenosine receptor agonist, 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadeno sin e (CGS 21680), apparently specific for high-affinity binding sites of the A2 subtype in rat brain, was used to identify and pharmacologically characterize adenosine receptors in human brain. The binding of [3H]CGS 21680, as determined by standard radioligand binding technique in the presence of exogenously added adenosine deaminase, reached equilibrium after 40 min at 25 degrees C. In saturation studies, a single class of high-affinity binding sites with values for KD of 22 +/- 0.5 nM and Bmax of 444 +/- 63 fmol/mg of protein were observed. Similar binding characteristics were observed regardless of whether rapid filtration or centrifugation was used to separate bound versus free ligand. Of the 14 brain regions examined, [3H]CGS 21680 binding was highest in putamen, followed by globus pallidus and caudate nucleus. The level of [3H]CGS 21680 binding in these areas of basal ganglia was identical to 5'-N-[3H]ethylcarboxamidoadenosine ([3H]NECA) binding in the presence of 50 nM N6-cyclopentyladenosine (CPA). The rank order of agonist potencies as determined by a series of competition experiments was NECA greater than or equal to CGS 21680 greater than 2-chloroadenosine greater than N6-(R)-phenylisopropyladenosine greater than N6-cyclohexyladenosine greater than N6-(S)-phenylisopropyladenosine. This potency order was the same for the binding of [3H]CGS 21680 to rat, and of [3H]NECA in the presence of 50 nM CPA to rat and human, brain membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1989

Isotope effects on binding of NAD+ to lactate dehydrogenase.

The isotope effect on binding [4-2H]NAD+ and [4-3H]NAD+ to lactate dehydrogenase has been shown to be 1.10 +/- 0.03 by whole molecule isotope ratio mass spectrometry and 1.085 +/- 0.01 by 3H/14C scintillation counting. These values demonstrate that specific interactions of the nicotinamide ring with the enzyme make the C-H bond at C-4 less stiff in the binary complex.

Animals↗