The fundamentally diverse vertebrate pigment cells, melanophores, xanthophores, and iridophores, contain pigmentary organelles known, respectively, as melanosomes, pterinosomes, and reflecting platelets. Their pigments are melanins, pteridines, and purines. Mosaic pigment cells containing more than one type of organelle have been observed and mosaic organelles containing more than one type of pigment have been discovered. It is proposed that the various pigment cells are derived from a stem cell that contains a primordial organelle of endoplasmic reticular origin. This primordial organelle can differentiate into any of the known pigmentary organelles.
The fine structure and the composition of pteridine pigments of erythrophores in adults of the swordtail fish, Xiphophorus helleri, were studied by means of cytochemistry, paper chromatography, ionophoresis, centrifugal fractionation, and electron microscopy. It was found that water-soluble pigments of erythrophores consisted exclusively of pteridine derivatives including large amounts of drosopterin, isodrosopterin, neodrosopterin, and moderate amounts of sepiapterin. While these substances were responsible for red pigmentation, moderate quantities of colorless pteridines, biopterin, Rana-chrome 3, xanthopterin, isoxanthopterin, and others, were also detectable. The ultrastructure of the erythrophore is characterized by numerous pigment granules and a well developed tubular endoplasmic reticulum. The former consist of a three-layered limiting membrane and inner lamellae which appear to be whorl-like due to a concentric arrangement of parallel membranes. All of the mentioned pteridines are primarily contained in this organelle which is designated, accordingly, "pterinosome." The possible functions of erythrophores and pterinosomes are discussed in the light of their structure and pigmentary constitution.
We investigated the role of capsaicin-sensitive sensory neurons in regulation of gastroduodenal HCO3- secretion in anesthetized rats. The stomach (under acid inhibition by omeprazole 60 mg/kg i.p.) or the duodenum was perfused with saline (pH 4.5) and HCO3- output was determined by pH change in the perfusate. Both the duodenum and stomach responded to prostaglandin E2 (PGE2; 300 μg/kg i.v.) or luminal acid by a significant increase in pH and HCO3- output. These tissues also responded to luminal application of capsaicin (0.3–6 mg/ml for 30 min), resulting in a significant increase of pH and HCO3- output in a concentration-related manner. The HCO3- stimulatory action of capsaicin was markedly attenuated by functional ablation of capsaicin-sensitive sensory neurons, significantly mitigated by indomethacin, and exhibited tachyphylaxis after repeated application at a high concentration. The acid-induced pH and HCO3- responses were also significantly mitigated by sensory deafferentation and by indomethacin, whereas those induced by PGE2 remained unaffected. In addition, defunctionalization of these sensory nerves resulted in macroscopically visible damage in the duodenum when acid secretion was concomitantly stimulated by histamine. We conclude that capsaicin-sensitive sensory neurons may be involved in the regulatory mechanism of gastroduodenal HCO3-secretion and contribute to protection of the mucosa against acid. Endogenous PGs may be involved in the HCO3- stimulatory action mediated by capsaicin-sensitive sensory neurons.
To make a physiologically-based pharmacokinetic model of isosorbide dinitrate (ISDN), the author infused ISDN at 1, 10, 30 micrograms.kg-1.min-1 into anesthetized rabbits and measured concentrations of ISDN and its metabolites (2-ISMN and 5-ISMN) in plasma and in the brain, liver as well as fat tissue. There was the accumulation of ISDN in the brain and fat tissue. There was no significant difference in concentrations of ISDN between the plasma and liver, or in concentrations of its metabolites among plasma, and the tissues of the brain, liver and fat. Using these informations, the author constructed a physiologically-based pharmacokinetic model to human and estimated values were compared with observed values to determine the validity of the model. There was no remarkable differences between the estimated values and observed values. This suggests the validity of the model. The plasma concentrations of ISDN estimated by this model, showed a linear increase (Y = 25 X) with the infusion rate less than 6.0 micrograms.kg-1.min-1. The accumulation of ISDN, especially in the brain was suggested by this model.
Prenatal diagnosis of isolated total anomalous pulmonary venous drainage (TAPVD) is difficult. The objective of our report is to improve the detecting rate of fetal TAPVD, and to show that 3D/4D ultrasound with spatio-temporal image correlation (STIC) is a useful tool for the detecting isolated TAPVD. Ultrasound examination was performed using a Voluson E8 (GE Healthcare) and the transabdominal probe (RAB 2-5-D). 4D datasets by Color STIC were analyzed. 4D gray images were rendered with surface texture and gradient light modes. Three fetuses with isolated TAPVD were enrolled in the study. Case 1: TAPVD (cardiac type) 4D Color images visualized pulmonary venous (PV) drainage to coronary sinus, and showed blurred common chamber behind the left atrium at 26 weeks. 4D images were able to facilitate identification of a hollow of common pulmonary venous chamber (CPV) more clearly than B-mode image. Case 2: TAPVD (infracardiac type) 4D Color images showed CPV, vertical vein, infra-diaphragmatic PV drainage and turbulent flow in the ductus venousus at 26 weeks. 4D images depicted circumference of CPV rather thicker than B-mode image. Case 3: TAPVD (infracardiac type without CPV) 4D Color images showed vertical vein behind left atrium, and infra-diaphragmatic PV drainage in the portal vein. And CPV was not found at 34 weeks. 4D images visualized vertical vein as only a small hole behind the left atrium. There are some diagnostic clues for detecting the isolated-TAPVD. Among them the presence of a common pulmonary venous chamber behind the left atrium is a highly suspicious finding. 4D images with gradient light mode were easy to find a common pulmonary venous chamber rather than B-mode images, being useful for the detecting fetal isolated-TAPVD.
