X-ray microanalysis of rat mast cells stimulated with compound 48/80 in combination with quick-freezing method

X-ray microanalysis was performed on rat mast cells prepared by quick-freezing, cryosectioning and freeze-drying (QF-FD) method, or quick-freezing and freeze-substitution (QF-FS) method. Peritoneal cells including mast cells were stimulated with compound 48/80 for 0, 10 or 30 s at 17° C, and the mast cells stimulated for 30 s started exocytosis. In X-ray spectra of the QF-FD specimen, mast cells stimulated for 10 s increased their levels of phosphorus, sodium and chlorine in the intergranular cytoplasm prior to exocytosis, and kept this increase until 30 s after stimulation. In the QF-FS specimen, where soluble elements were removed, peaks of phosphorus, sulphur and potassium could be detected as elements in X-ray spectra. Phosphorus increased and potassium decreased in intergranular cytoplasm of mast cells stimulated for 10 s, and these changes became more obvious after 30 s. However, supplemental increase of other cations such as sodium could not be detected in the QF-FS specimens.     

X-ray microanalysis of the rat parotid gland after chronic sympathectomimetic stimulation

The effects of chronic treatment with isoproterenol, reserpine, prenalterol, and terbutaline on rat parotid gland were investigated by electron microscopy and X-ray microanalysis. Chronic isoproterenol treatment induced lower potassium and calcium concentrations in the acinar cells. The cells were enlarged and contained more and larger zymogen granules than acinar cells in the controls. The zymogen granules contained markedly less sulfur, potassium, and calcium than in control animals. Prenalterol had effects similar to those of isoproterenol, but less pronounced, whereas terbutaline had no significant effects. Chronic treatment with reserpine caused a decrease in calcium levels but did not affect potassium levels. The changes in elemental composition in parotid acinar cells after chronic treatment with isoproterenol and reserpine differed from those induced by the same treatment in the submandibular gland of the rat.     

Iodine in rat alveolar macrophages following amiodarone treatment: quantitative X-ray microanalysis

The techniques of cryomicrotomy and X-ray microanalysis were used to quantitatively measure the subcellular distribution of iodine in rat alveolar macrophages following a single administration of the iodine-containing antiarrhythmic drug, amiodarone. When frozen, dried sections were analyzed, small amounts of iodine were found throughout the alveolar macrophages, but the major accumulations were observed in amorphous bodies and dense granules. The highest to lowest accumulation is in the following order: amorphous bodies (90 mmole I/kg dry wt) greater than dense granules (50 mmole I/kg dry wt) greater than nucleus = cytosol (10 mmoles I/kg dry wt). The amorphous bodies can contain high and low levels of iodine and the granules are found to have high and low levels of iron. Granules with the high and low levels of iron and amorphous bodies with the high and low levels of iodine can be found in the same cells. X-ray microanalysis proved useful in describing the intracellular distribution of iodine-labeled species following amiodarone administration.     

X-ray microanalysis of spontaneously formed urinary calculi in a jaundiced strain of rat

A high incidence of spontaneously formed urinary stone was found in the females of a jaundiced strain of rat developed from a cross between Gunn's rat and Wistar-Imamichi rat. In this colony, 42.3% of the females had urinary calculi. Elemental analyses of these urinary calculi were carried out with an analytical electron microscope, a high-resolution transmission electron microscope fitted with an energy dispersive type X-ray microanalyzer and a scanning device. In the surface and middle areas of the stone, the main components were recognized as magnesium (Mg) and phosphorus (P). In the central region of the stone, calcium (Ca) and phosphorus (P) were found as the main elements with trace amounts of sodium (Na), chlorine (Cl), and potassium (K). The analyses indicated that the spontaneous urinary stone consisted of phosphate salts with calcium or magnesium. In addition, the mass ratio of the $\text{Mg}\text{P}$ or $\text{Ca}\text{P}$ in the stones was calculated from X-ray pulse intensity ratios and compared with the mass ratio of a standard sample. The results suggested that the magnesium and phosphorus in the urinary stones existed as ammonium magnesium phosphate, MgNH₄PO₄, and the calcium and phosphorus as tribasic calcium phosphate, Ca₃(PO₄)₂.     

TCR trafficking in resting and stimulated T cells

Dynamic regulation of TCR expression levels plays important roles in modulating T-cell responses during T-cell development and in mature T cells. TCR expression levels are determined by the rate constants for synthesis, endocytosis, recycling, and degradation. This review examines the rate constants, the molecular mechanisms, and the proposed physiological roles of TCR trafficking in resting and stimulated T cells. In resting T cells, the TCR slowly and constitutively cycles between the plasma membrane and the intracellular compartment. Constitutive TCR cycling is dependent on the di-leucine-based (diL) receptor-sorting motif in the TCR subunit CD3g and might play a role in quality control of the TCR. TCR triggering induces an enhancement in the endocytic rate constant leading to TCR down-regulation. At least two pathways exist for endocytosis of triggered TCR. One is dependent on protein tyrosine kinase activity leading to ubiquitination of the TCR, whereas the other is dependent on protein kinase C (PKC)-mediated activation of the diL motif. In addition, nontriggered TCR are endocytosed (co-modulated) by the PKC/CD3g-dependent pathway. TCR down-regulation might attenuate signaling and/or might ensure an internal store of TCR that can be rerouted to the immunological synapse during the encounter with an antigen-presenting cell.     

The electrical properties of resting and secreting pancreas

1. The electrical properties of the resting and stimulated pancreas have been studied in the anaesthetized cat. There is an inverse relationship between the frequency of applied alternating current and the resistivity and dielectric constant of the resting pancreas. The resistivity is also affected by the fat content of the gland. The impedance locus of the pancreas is similar to that of other tissues.2. On intravenous injection of secretin there is a brief increase, followed by a more marked decrease, in conductance and capacitance of the pancreas. The phase of decreased conductance is related to the flow of pancreatic juice. The decrease in conductance and the flow rate can be characterized by two closely related empirical equations.3. During secretin stimulation the sodium concentration in pancreatic tissue increases, and the potassium concentration falls.4. It is tentatively suggested that the decreased conductance across the secreting gland is mostly due to swelling of the secretory cells and to a minor degree is the result of changes in the composition of the secretion in the pancreatic ducts.5. In the anaesthetized cat the mean half life of the secretory action of secretin is 199 sec.     

X-ray microanalysis as applied to fungal tissues

Analytical electron microscopy combines the techniques of high-resolution electron microscopy and high-sensitivity X-ray microanalysis of samples. Spectrometry of the elements (characteristic X-rays produced by a scanning electron microprobe) was employed to detect some elements of Mendeleev's classification in pathogenic fungi for humans. X-ray microanalysis applied in wavelength dispersive spectrometry was used to study Coccidio?des immitis, Paracoccidio?des brasiliensis and Trichosporum cutaneum.     

X-ray microanalysis of the Michaelis-Gutmann bodies of malakoplakia

The Michaelis-Gutmann (MG) inclusion bodies of three cases of malakoplakia (prostate, testis, colon) were studied by X-ray microanalysis to determine their elemental composition. Calcium and phosphorus were consistently found. Iron was detected in a few bodies. No other elements were detected. The electrondense laminations were of similar composition to the core material. Small aggregates of electron-dense material containing calcium and phosphorus were also occasionally seen in phagolysosomes. These observations are consistent with view that MG bodies arise by a process of phagolysosomal coalescence and mineralisation.     

Cadmium toxicity in perinatal rat hepatocytes: electron microscopy, X-ray microanalysis, and morphometric analysis

Effects of cadmium on the fetal and postnatal rat hepatocytes were studied with an electron microscope and an X-ray microanalyzer. Pregnant and lactating Wistar rat dams at 15 and 21 days of pregnancy and at 3 days after delivery received intraperitoneal injections of cadmium sulfate (1 mg/kg body weight) for 3 days. On the day following the last injection, the livers were isolated from the fetal and suckling rats and provided for electron microscopy. The livers from the untreated fetal and newborn rats served as control. Large bile canaliculi, which were formed by five or more hepatocytes, were frequently observed in the cadmium-treated perinatal rat livers. The intercellular space between each adjacent hepatocyte was widened. By X-ray microanalysis, cadmium peaks were preferentially detected out from intramitochondrial granules of the cadmium-treated hepatocytes. By morphometric analysis, the increase both in the mitochondria volume and in the number of intramitochondrial granules was evident in the cadmium-treated hepatocytes when compared to those of control. These data suggest the preferential accumulation of cadmium in mitochondria of the hepatocytes interferes with the morphogenesis of the perinatal rat liver.     

Fe-rich corpuscles inDiplogonoporus grandis detected using X-ray microanalysis

An energy dispersive X-ray microanalysis of the individual corpuscles in the parenchyma ofDiplogonoporus grandis was performed for the chemical identification of their inorganic composition. Besides the corpuscles showing distinct peaks for calcium, a major inorganic element, a type of corpuscle showing distinct peaks for iron was observed. It is suggested that it is necessary to examine not only the whole corpuscles isolated but also individual corpuscles in the tissue when studying the nature and roles of corpuscles in cestodes.     

X-ray microanalysis as applied to fungal tissues.

Analytical electron microscopy combines the techniques of high-resolution electron microscopy and high-sensitivity X-ray microanalysis of samples. Spectrometry of the elements (characteristic X-rays produced by a scanning electron microprobe) was employed to detect some elements of Mendeleev''s classification in pathogenic fungi for humans. X-ray microanalysis applied in wavelength dispersive spectrometry was used to study Coccidioïdes immitis, Paracoccidioïdes brasiliensis and Trichosporum cutaneum.     

Calcium exchange in the resting and electrically stimulated canine myocardium

⁴⁵Ca²⁺ exchange was studied in small pieces of canine left ventricular free wall. The loss of⁴⁵Ca²⁺ from⁴⁵Ca²⁺ equilibrated tissue into ice-cold (4°C) wash medium could be best fitted with a model containing a minimum of 3 compartments.⁴⁵Ca²⁺ uptake into and⁴⁵Ca²⁺ efflux from the most slowly exchanging compartment (compartment 3) at 37°C allowed it to be subdivided into two fractions; a rapidly exchanging fraction (t _1/21.25 min) and a slowly exchanging fraction (t _1/250 min). The total Ca²⁺ content of compartment 3 was enhanced by isoproterenol but little affected by caffeine. The slowt _1/2 for exchange of the Ca²⁺ in compartment 3 at 4°C and its increased Ca²⁺ content following isoproterenol treatment suggest that this compartment contains some Ca²⁺ of intracellular origin. In addition, the finding that the rapidly exchanging part of compartment 3 could be preserved by cooling the tissue to 4°C shows that rapidly exchanging Ca²⁺ compartments can be studied in superfused cardiac preparations using this technique. Action potentials, elicited by electrical stimulation of the tissue, caused large changes in the Ca²⁺ content of compartment 3 (up to 170 M/kg) indicating that this postulated intracellular compartment may play a significant role in the normal contraction-relaxation cycle.     

The chronically isoproterenol-treated rat in the study of cystic fibrosis: X-ray microanalysis of the submandibular gland

The chronically isoproterenol-treated rat has been proposed as an animal model for cystic fibrosis. Ultrastructural studies showed enlarged cells with abnormally large mucus granules that were more often fused than in control animals. X-ray microanalysis of mucous acinar cells showed a significant increase in calcium levels, but unaffected magnesium levels. Combined treatment with isoproterenol and reserpine caused a very large increase in cellular calcium levels that appeared to be an addition of the single effects and increased magnesium levels (as in glands of rats treated with reserpine only). Chronic treatment with isoproterenol, reserpine, or both substances tended to decrease cellular potassium levels. Chronic exposure to the specific beta 1-agonist prenalterol or the specific beta 2-agonist terbutaline did not affect cellular calcium or potassium levels. It is concluded that chronic isoproterenol treatment affects the elemental composition of mucous acinar cells of rat submandibular gland differently from chronic reserpine treatment. The increase in cellular calcium concentration after chronic isoproterenol treatment does not appear to be due to an effect via beta-adrenergic receptors.     

Demonstration of iron and thorium in autopsy tissues by X-ray microanalysis

We performed x-ray microanalysis of autopsy specimens using a scanning-transmission electron microscopy mode. Tissues were obtained at necropsy from a patient with history of angiography using thorium dioxide and from a patient with hemochromatosis. X-ray microanalysis confirmed the presence of thorium and iron in their respective tissues. Effects of staining reagents were examined.     

Release of endogenous 5-hydroxytryptamine from resting and stimulated enteric neurons

Physiological and biochemical evidence has indicated that there may be serotoninergic neurons in the enteric nervous system. A critical step in the identification of a neurotransmitter is the demonstration of the release of the substance upon nerve stimulation. We now report the release of endogenous 5-hydroxytryptamine from enteric neurons. Segments of guinea-pig small intestine were everted and perfused in vitro through the newly created serosal lumen. Tests with [³H]5-hydroxytryptamine revealed the existence of a tissue barrier preventing diffusion of mucosal (enteroendocrine cell) 5-hydroxytryptamine into the perfusate; thus, all 5-hydroxytryptamine in the perfusate was of neural origin. The gut was stimulated electrically. 5-Hydroxytryptamine in the perfusate and in the myenteric plexus was assayed by a specific radioenzymatic method. 5-Hydroxytryptamine was present in the myenteric plexus; it was released into the perfusate spontaneously and the release was enhanced by electrical stimulation. The stimulated, but not the spontaneous, release of the amine was Ca²⁺-dependent. Comparison with the release of newly taken up [³H]5-hydroxytryptamine showed that the specific radioactivity of electrically released 5-hydroxytryptamine was higher than that of either the spontaneously released or tissue amine. Stimulation also increased the release of 5-hydroxytryptamine more than that of its metabolites in the perfusate.These results indicate that 5-hydroxytryptamine is an endogeneous constituent of the enteric nervous system, that it is released by electrical field stimulation of enteric nerves, and that newly taken up 5-hydroxytryptamine is released preferentially by these neurons.