Fever-range hyperthermia enhances L-selectin-dependent adhesion of lymphocytes to vascular endothelium.

The L-selectin leukocyte adhesion molecule plays an important role in controlling leukocyte extravasation in peripheral lymph nodes and at sites of tissue injury or infection. Although febrile responses during infection and inflammation are associated with enhanced immune activity, the contribution of fever-range temperatures to controlling lymphocyte recruitment to tissues has not been previously examined. In this report we provide evidence that direct exposure of lymphocytes to fever-range temperatures (38-41 degrees C) in vitro for 9 to 24 h resulted in a >100% increase in L-selectin-dependent adhesion of these cells to lymph node high endothelial venules (HEV). Moreover, culture of lymphocytes under hyperthermia conditions markedly enhanced the ability of these cells to traffic in an L-selectin-dependent manner to peripheral lymph nodes, mesenteric lymph nodes, and Peyer's patches. In contrast, febrile temperatures did not increase LFA-1 function as assessed by measuring lymphocyte adhesion to ICAM-1-3T3 transfectants. Fever-range hyperthermia further did not increase L-selectin surface density on lymphocytes or L-selectin-dependent recognition of soluble carbohydrate substrates; however, a marked increase in ultrastructural immunogold-labeling of L-selectin was observed in response to thermal stimuli. These results suggest that elevated temperatures enhance L-selectin adhesion and/or avidity through the regulation of L-selectin conformation or organization in the plasma membrane. Finally, the observed thermal effects on L-selectin adhesion were attributed to soluble factors in the conditioned medium of heat-treated cells. Taken together, these data provide new insight into the potential physiologic role of the febrile response in enhancing lymphocyte recruitment to tissues through the regulation of L-selectin adhesion.

Tryptophan and neutral amino acids in premenstrual syndrome.

An abnormality of the serotonin system may play a role in the genesis of the symptoms of premenstrual syndrome, especially those related to mood and appetite. Whole blood and platelet uptake of serotonin are decreased during the luteal phase in women with premenstrual syndrome. The ratio of L-tryptophan (the amino acid precursor of serotonin) to the sum of the other neutral amino acids that compete for the same protein carrier cerebral uptake mechanism has been suggested to reflect central L-tryptophan levels and resultant serotonin levels in the brain. We evaluated the ratio of plasma L-tryptophan to the sum of five competing neutral amino acids in women with premenstrual syndrome and in controls. There were no significant differences between groups or across time, suggesting that it is unlikely that the aberrations of the serotonergic system in women with premenstrual syndrome are due to saturation of the tryptophan-carrying protein.

Raman scattering from flames.

Laser Raman scattering data for nitrogen, oxygen, and water vapor have been obtained from hydrogen-air and hydrogen-oxygen flames. The resulting ground-state and upper-state vibrational bands exhibit strong asymmetrical broadening. Experimental spectral profiles have been fitted theoretically to give a new measurement technique for the determination of rotational and vibrational excitation temperatures.