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Biomedical subjects

K T Nguyen

Publications and source records attributed to K T Nguyen.

61 records · Page 4Linked to original sources
PubMed1984

Temperature and field dependent 1H-NMR relaxation data as probes of prostaglandin motional parameters in aqueous media.

Proton resonance correlation times (tau eff) for PGF2 alpha and a more rigid analog have been derived from the field-strength dependence of spin-lattice relaxation times ( T1D ) using 200 and 500 MHz observation. Those hydrogens showing tau eff less than the value calculated for whole molecule tumbling (which applies for H-5----H-15) also show a significantly greater temperature dependence for T1D at 500 MHz. Minor wagging may occur at the C-7 and C-10 methylenes , and gradually increasing segmental motion is observed toward both side chain termini. A current model for the aqueous geometry of PGF2 alpha is developed from this data and studies of relaxation rate changes upon specific deuteration.

Chemical Phenomena↗
PubMedDate not supplied

Acute stress may facilitate recovery from a subcutaneous bacterial challenge.

The effects of stress on the immune system vary with both the duration and type of stressor. Many studies suggest that stress may compromise an organism's ability to recover from immune challenge. However, recent findings suggest that stress may actually enhance some aspects of immune function. For example, exposure to a single session ( approximately 2 h) of intermittent inescapable tailshocks (IS) has been shown to activate the acute phase response and increase some aspects of macrophage function. Thus, the following experiments assessed whether IS exposure would alter local inflammation produced by peripheral injection of streptomycin-killed bacteria. Rats (Harlan Sprague Dawley) were exposed to IS (100 1. 6-mA, 60 s variable intertrial interval) and injected with Escherichia coli ( approximately 2.5 x 10(8) CFU s.c. posterior to the shoulder blades). The area of inflammation was measured until the inflammation had completely resolved (typically 7-8 days). When bacteria were administered immediately after IS, rats resolved inflammation significantly faster than did nonstressed rats. Since adrenalectomy did not reduce the effect of IS, it is unlikely that this effect is a result of elevated corticosterone levels. Furthermore, IS does not appear to alter the rat's ability to sequester bacteria in the subcutaneous space since no swelling of lymph nodes or chronic activation of the hypothalamic-pituitary-adrenal axis was observed.

Animals↗
PubMedDate not supplied

Rapid morphological reorganization of the rabbit corneal endothelium after acute exposure to sodium lactate in vitro.

Corneal stroma-endothelial preparations from 2-kg albino rabbits were incubated in vitro in a bicarbonate-Ringer solution equilibrated with 5% CO2-9% O2 over 4 h in half-chambers at 37 degrees C. An average net fluid pump activity of 6.8 microliters/h was measured in the 4th hour. If such preparations were initially equilibrated with bicarbonate-Ringer for 90 min and then challenged for 20 min with 15 mM sodium lactate or NaCl, an osmotically induced increase in fluid flow occurred. After removal of the challenge and return to bicarbonate-Ringer for 2.5 h, the net fluid pump returned to baseline and then increased again (to an average of 9.7 microliters/h) for the lactate- but not NaCl-challenged endothelia. Scanning electron microscopy showed that lactate-challenged (but not the control or NaCl-challenged) endothelial contained a moderate number of very large pleomorphic cells within an otherwise regular mosaic. It is proposed that the large cells develop as a result of cell fusion (coalescence).

Animals↗