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Paradoxically, bilateral transection of the chorda tympani nerve (CTX) raises the taste discrimination threshold for the free fatty acid, linoleic acid (LA), yet the chorda tympani nerve (CT) is unresponsive to lingual application of LA alone. LA may require a background of saliva to activate taste cells, since CTX decreases saliva production through denervation of the submaxillary and sublingual salivary glands. To assess the role of saliva, we measured LA taste discrimination thresholds for animals whose submaxillary and sublingual salivary glands were removed and also recorded CT responses to LA mixed in artificial saliva. Partial desalivation shifted LA discrimination thresholds from between 5.5 and 1l [micro]M to between 11 and 22 [micro]M. However, this effect was not as pronounced as previously seen with CTX animals. Surprisingly, the CT was unresponsive to LA mixed with artificial saliva, suggesting that artificial saliva may lack components necessary for LA taste. Additionally, fats may primarily enhance other tastes. We previously reported that LA increases CT responses to monosodium glutamate (MSG). Thus we also recorded CT whole nerve responses to taste mixtures of LA and sodium chloride (NaCl), sucrose (SUC), citric acid (CA), or quinine hydrochloride (QHCl) in anesthetized rats. We found that LA increased CT responses to NaCl but did not alter CT responses to SUC, CA, and QHCl. Thus CT recordings either lack the sensitivity to detect small changes to SUC, CA, and QHCl or LA may affect CT responses to MSG and NaCl only, perhaps by specifically modulating gustatory processing of [Na.sup.+]. fat taste; free fatty acids; electrophysiology; electrolytes doi: 10.1152/ajpregu.00217.2009

Background: Saliva has a high nitrite concentration, derived from the enterosalivary recirculation of dietary nitrate, and is the main source of nitrite entering the acidic stomach. Acidification of nitrite in [...]

Previous studies have shown that the human salivary antifungal peptide histatin 5 is taken up by Candida albicans cells and associates intracellularly with mitochondria. The purpose of the present study was to investigate the biological consequence of this specific subcellular targeting. Histatin 5 inhibited respiration of isolated C. albicans mitochondria as well as the respiration of intact blastoconidia in a dose and time-dependent manner. A nearly perfect correlation was observed between histatin-induced inhibition of respiration and cell killing with either logarithmic- or stationary-phase cells, but stationary-phase cells were less sensitive. Because nonrespiring yeast cells are insensitive to histatin 5, the potential mechanistic relationship between histatin 5 interference with the respiratory apparatus and cell killing was explored by using an oxygen radical sensitive probe (dihydroethidium). Fluorimetric measurements showed that histatin 5 induced the formation of reactive oxygen species (ROS) in C. albicans cells as well as in isolated mitochondria and that ROS levels were highly correlated with cell death. In the presence of an oxygen scavenger (L-cysteine), cell killing and ROS formation were prevented. In addition, the membrane-permeant superoxide dismutase mimetic 2,2,6,6-tetramethylpiperidine-N-oxyl, abolished histatin-induced ROS formation in isolated mitochondria. In contrast to histatin 5, the conventional inhibitors of the respiratory chain, sodium cyanide or sodium azide, neither induced ROS nor killed yeast cells. These data provide strong evidence for a comprehensive mechanistic model of histatin-5-provoked yeast cell death in which oxygen radical formation is the ultimate and essential step.

Key Words sand flies, vector biology, lipophosphoglycan, saliva * Abstract Leishmania-sand fly interactions are reviewed in the context of the potential barriers to the complete development of the parasite that [...]

Saliva can inhibit the adhesion of Candida albicans to plastic when the fungus is in the germinating stage. The inhibition is mediated by saliva secretory IgA, which blocks adhesins on the cell wall surface of germ tubes. Adhesion of Candida to plastic dentures can cause denture stomatitis.

Background. Aging is associated with a loss of bone mineral density (BMD) in men and women. Loss of BMD can also be caused by hypercortisolemia in men or women at any age. This study measured salivary cortisol at 2300 h and 0700 h as indices or cortisol secretory activity in 228 elderly, community-dwelling subjects. Salivary cortisol results were correlated with BMD. We hypothesized that the salivary cortisol is elevated at 2300 h in elderly people, and that salivary cortisol will correlate negatively with BMD. Methods. Saliva was sampled at 2300 h (nadir in circadian rhythm) and 0700 h (peak in circadian rhythm) in 130 men (70.7 +/-0.4 years old) and 98 women (70.0 +/-0.4 years old); approximately half of the women were receiving hormone replacement therapy (HRT). BMD was measured by dual energy x-ray absorptiometry. Results. Salivary cortisol at 2300 was significantly elevated in men (2.3+/-0.1 nmol/L) and women (2.1+/-0.1 nmol/L) as compared to 73 younger controls (1.2+/-0.1 nmol/L;37+/-1 year old). Salivary cortisol at 0700 h was not different between older subjects and younger controls. There was a significant negative correlation of lumbar (L2-4) BMD and 2300 h salivary cortisol in older women (r=-0.20,p=.05;n=98); this correlation was significant only in women not on HRT. There was a highly significant negative correlation of lumbar (L2-4) BMD and 0700 h salivary cortisol in older men (r=-0.31,p=.003). Conclusions. Salivary cortisol is a simple, nonstressful method for assessing activity of the hypothalamic-pituitary-adrenal (HPA) axis in the elderly population. A major finding was an elevation in the late night nadir in cortisol secretion. We also suggest that elevated cortisol secretion in elderly people may contribute to the age-related loss in bone mineral density and that this effect is prevented by HRT.

HIV patients appear to produce IgA antibodies directed against the V4 envelope region of HIV and IgG antibodies against the V3 loop of the virus. Antibodies were measured in the blood and saliva of 45 HIV-infected patients.

The survival of free DNA in human saliva and its degradation have been studied by using competitive polymerase chain reaction. The free DNA is a 520-bp target sequence from a recombinant plasmid, pVACMC1, after the admixture of the plasmid with freshly-sample human saliva. Results reveal that the plasmid DNA that has been exposed to degradation by human saliva can transform naturally-competent Streptococcus gordonii DL1 to erythromycin resistance. The transformation decreased rapidly with a half-life of 50 seconds.

Several proteins produced by saliva appear to account partly for the lowered risk of transmitting HIV via saliva. Although mucosal transmission via the anus and vagina account for many cases, this is not true of the oral mucosa. Epidemiologic studies have consistently shown that the virus is not transmitted by kissing or sharing eating utensils. Studies have shown that the virus is found in saliva but saliva also has mucins as well as a protein called secretory leukocyte protease inhibitor, which appear to block infection of oral epithelial cells by HIV.