Microwave-induced increase of water and conductivity in submaxillary salivary gland of rats

Hypersalivation is an important mechanism for heat dissipation by animals without sweat glands. The water content and conductivity (at 20 kHz) in sub-maxillary salivary gland (SSG) and in other tissues were investigated in adult male rats exposed to microwaves (2880 MHz, 1.5 μs pulses at 1000 Hz) or to conventional heat at 40 °C. Eighty rats in one series were exposed, one at a time, for 30 min to microwaves producing a specific absorption rate (SAR) of 4.2,6.3,6.8,8.4,10.8 or 12.6 W/kg. Fifty rats were sham-exposed under similar environmental conditions. In the second series, ten rats were sham-exposed, 33 rats were exposed, one at time, for 15, 30 or 60 min to microwaves at a SAR of 9.5 W/kg, and 32 rats were exposed for similar periods to conventional heat at 40 °C. In rats of the first series colonic temperatures were elevated significantly at a SAR of 4.2 W/kg, while SSG water content and conductivity increased significantly at SAR values of 6.3 W/kg and higher. In the second series of experiments increases in colonic temperature and SSG water content were greater after 15 and 30 min of microwave exposure than after exposure to heat. Also, SSG conductivity was significantly depressed by heat and significantly increased by microwaves after exposure for 15 or 30 min. The results support the hypothesis that water content and conductivity of SSG of rats can be used as a sensitive specific test of a microwave induced thermal response.     

Accelerated development of spontaneous and benzopyrene-induced skin cancer in mice exposed to 2450-MHz microwave radiation

C₃H/HeA mice with high incidence of spontaneous breast cancer and Balb/c mice treated with 3,4-benzopyrene (BP) (by painting of the skin resulting in the development of skin cancer) were irradiated with 2,450-MHz microwaves (MW) in an anechoic chamber at 5 or 15 mW/cm² (2 h daily, 6 sessions per week). C₃H/HeA mice were irradiated from the 6th week of life, up to the 12th month of life. Balb/c mice treated with BP were irradiated either prior to (over 1 or 3 months) or simultaneously with BP treatment (over 5 months). The appearance of palpable tumors in C₃H/HeA mice and of skin cancer in BP-treated Balb/c mice was checked every 2 weeks for 12 months. Two additional groups of mice were exposed to chronic stress caused by confinement or to sham-irradiation in an anechoic chamber; these served as controls. Irradiation with MWs at either 5 or 15 mW/cm² for 3 months resulted in a significant lowering of natural antineoplastic resistance (mean number of lung neoplastic colonies was 2.8 ± 1.6 (SD) in controls, 6.1 ± 1.8 in mice exposed at 5 mW/cm² and 10.8 ± 2.1 in those irradiated at 15 mW/cm²) and acceleration of development of BP-induced skin cancer (285 days in controls, 230 days for 5 mW/cm² and 160 days for 15 mW/cm²). Microwave-exposed C₃H/HeA mice developed breast tumors earlier than controls (322 days in controls, 261 days for 5 mW/cm² and 219 days for 15 mW/cm²). A similar acceleration was observed in the development of BP-induced skin cancer in mice exposed simultaneously to BP and MWs (285 days in controls, 220 day for 5 mW/cm² and 121 days for 15 mW/cm²). The acceleration of cancer development in all tested systems and lowering of natural antineoplastic resistance was similar in mice exposed to MW at 5 mW/cm² or to chronic stress caused by confinement but differed significantly from the data obtained on animals exposed at 15 mW/cm², where local thermal effects (“hot” spots) were possible.     

Effects of sodium, potassium and calcium on salt-stressed barley

We grew barley ( Hordeum vulgare L. CM 72) for a 28-day period and sequentially harvested plants every 3 or 4 days. Plants were salt-stressed with either NaCl or KCl (125 m M ) with or without supplemental Ca (10 or 0.4 m M final concentration, respectively). We determined tissue concentrations of Na, Ca, Mg, K. S, P, Fe, Mn, Cu and Zn for each harvest date by inductively coupled plasma spectrometry. Uptake (specific absorption rate) was calculated from the element content and growth rates. Salinity had significant effects on the uptake and concentrations of most elements. Mg and Mn concentrations declined with time. The concentrations of all other elements determined increased over time. Element uptake on a root dry weight basis declined with time. Three variables were significantly affected by salinity and correlated with growth; 1) the Ca concentration, 2) the total sum of the cation concentration (TC), and 3) the Mn concentration of the shoot. Salinity reduced Ca uptake and concentrations. Supplemental Ca increased Ca concentrations and was positively correlated with growth during salt stress. Salinity doubled TC, which was negatively correlated with relative growth rate (RGR). Relative growth rate declined at TC values above 150 m M . Salinity reduced the uptake and concentration of Mn. Manganese concentrations in the shoot were highly correlated with RGR. Relative growth rate declined at Mn concentrations below 50 nmol (g fresh weight)⁻¹.     

Distribution of specific proteins in the salivary gland lobes of Culicidae and their relation to age and blood sucking

Specific proteins are produced in different parts of the salivary glands of female Anopheles and Culex. In both species there are concentrated low molecular weight proteins in the median lobes and proteins in the mol. wt range 25,000–60,000 in the distal parts of the lateral lobes. These proteins are not identical in the two species. In the proximal parts of the lateral lobe there are only small amounts of protein in addition to an unknown high molecular weight substance. At the time of blood-sucking 15–35% of soluble gland proteins are injected with the saliva into the host animal, the proteins from the median lobes and the proximal part of the lateral lobes being released in greater quantities than the proteins from the distal parts of the lateral lobes. The typical gland proteins are only extractable in low concentrations from the salivary glands of the newly-hatched adult mosquito, they increase up to the 7th day of the adult development and are stored in the glands.     

Sequential changes in salivary gland structure during attachment and feeding of the cattle tick, Boophilus microplus

A study of the morphology and histochemistry of the salivary glands of the parasitic stages of Boophilus microplus has been made, glands of feeding females being studied in greatest detail. Of 9 granular cell types present in the female and 10 in the male, 3 probably secrete attachment cement and 4 others glycoproteins and enzymes, possible functions of which are discussed. Two cell types, c₄ and g (the latter being present only in males) are of unknown function. The most likely functions of non-granular epithelial cells and those forming acinus I are in osmoregulation.     

Developmental changes in morphology and toxin content of the salivary gland of the australian paralysis tick Ixodes holocyclus

Binnington K.C. and Stone B.F. 1981. Developmental changes in morphology and toxin content of the salivary gland of the Australian paralysis tick Ixodes holocyclus.International Journal for Parasitology11: 343–351. Histological study of the salivary gland of female I. holocyclus has shown that 2 of the 4 cell types present are richest in granules in the unfed stage but have discharged these granules after an attachment period of 24 h. The presence of a toxin in homogenates of salivary glands from unfed females and its absence after 24 h of attachment may be associated with the loss of granules from these 2 cell types shortly after attachment. Another cell type shows a gradual increase in granule content throughout feeding and a fourth, a peak in granule content after an attachment period of 120 h. The latter cell type may produce the paralysing toxin since ticks do not paralyse the host until they have fed for about this time and homogenised glands are most toxic at 120–144 h.     

Effects of sodium, potassium and calcium on salt-stressed barley. I. Growth analysis

Barley ( Hordeum vulgare L. cv. CM 72) was grown for a 28-day period and stressed with treatments of 125 mol m⁻³ NaCl or KC1 with low Ca²⁺ (0.4 mol m⁻³ Ca²⁺) or high Ca²⁺ (10 mol m⁻³ Ca²⁺). Plants were harvested periodically so that relative growth rate (RGR), net assimilation rate (NAR) and leaf area ratio (LAR) could be calculated using the functional approach to plant growth analysis. Relative growth rate declined with time for all treatments, including controls. Salinity inhibited RGR relative to control values by day 10. High Ca²⁺ improved the growth of salt-stressed plants in both NaCl-salinity and KCl-salinity. KC1 proved more toxic than NaCl, especially for KCI-salinity plants with low Ca²⁺, which died by day 28. Net assimilation rate, but not LAR, was highly correlated with RGR for all treatments. This indicates that the photosynthetic-assimilatory machinery was limiting RGR and not the leaf area of the plant.     

Alteration of Ca2+‐ATPase activity in the homogenate,plasma membrane and microsomes of the salivary glands of streptozotocin‐induced diabetic rats

Diabetes has been implicated in the dryness of the mouth, loss of taste sensation, sialosis, and other disorders of the oral cavity, by impairment of the salivary glands. The aim of the present study was to examine the plasma membrane, microsomal, and homogenate Ca²⁺‐ATPase activity in the rat submandibular and parotid salivary glands of streptozotocin‐induced diabetes. We have also examined the influence of the acidosis state on this parameter. Diabetes was induced by an intraperitoneal injection of streptozotocin and acidosis was induced by daily injection of NH₄Cl. At 15 and 30 days after diabetes induction, the animals were euthanized and the submandibular and parotid salivary glands were removed and analyzed. Ca²⁺‐ATPase (total, independent, and dependent) was determined in the homogenate, microsomal, and plasma membranes of the salivary glands of diabetic and control rats. Calcium concentration was also determined in the glands and showed to be higher in the diabetic animals. Ca²⁺‐ATPase activity was found to be reduced in all cell fractions studied in the diabetic animals compared with control. Similar results were obtained for the submandibular salivary glands of acidotic animals; however in the parotid salivary glands it was found an increase in the enzyme activity. Copyright © 2009 John Wiley & Sons, Ltd.     

On approaches to the functional restoration of salivary glands damaged by radiation therapy for head and neck cancer,with a review of related aspects of salivary gland morphology and development

Radiation therapy for cancer of the head and neck can devastate the salivary glands and partially devitalize the mandible and maxilla. As a result, saliva production is drastically reduced and its quality adversely altered. Without diligent home and professional care, the teeth are subject to rapid destruction by caries, necessitating extractions with attendant high risk of necrosis of the supporting bone. Innovative techniques in delivery of radiation therapy and administration of drugs that selectively protect normal tissues can reduce significantly the radiation effects on salivary glands. Nonetheless, many patients still suffer severe oral dryness. I review here the functional morphology and development of salivary glands as these relate to approaches to preventing and restoring radiation-induced loss of salivary function. The acinar cells are responsible for most of the fluid and organic material in saliva, while the larger ducts influence the inorganic content. A central theme of this review is the extent to which the several types of epithelial cells in salivary glands may be pluripotential and the circumstances that may influence their ability to replace cells that have been lost or functionally inactivated due to the effects of radiation. The evidence suggests that the highly differentiated cells of the acini and large ducts of mature glands can replace themselves except when the respective pools of available cells are greatly diminished via apoptosis or necrosis owing to severely stressful events. Under the latter circumstances, relatively undifferentiated cells in the intercalated ducts proliferate and redifferentiate as may be required to replenish the depleted pools. It is likely that some, if not many, acinar cells may de-differentiate into intercalated duct-like cells and thus add to the pool of progenitor cells in such situations. If the stress is heavy doses of radiation, however, the result is not only the death of acinar cells, but also a marked decline in functional differentiation and proliferative capacity of all of the surviving cells, including those with progenitor capability. Restoration of gland function, therefore, seems to require increasing the secretory capacity of the surviving cells, or replacing the acinar cells and their progenitors either in the existing gland remnants or with artificial glands.