Effects of water on the mechanical properties of gelatin films

The mechanical properties of gelatin films were studied in relation to the effect of water, and compared with those of collagen films. The S-shaped sorption isotherm was separated into an adsorption curve C₁ and dissolution curve C₂. From the C₂ curve, the interaction parameter χ₁ of Flory–Huggins' equation was calculated. The χ₁ of gelatin were larger than those of collagen at low relative humidities (RH), while they coincided with each other at high RH. It was found that a composite curve was made by shifting stress relaxation curves obtained at different humidities along the log time axis. The shift factor for the formation of the composite curve was analyzed by Fujita–Kishimoto's equation, which was based on the free volume theory. The parameter β, which expressed the extent of the contribution of sorbed water to the increase in the free volume of the system, was 0.05 in the range of C₂ from 0 to 0.08 (0–65% RH). This value was much smaller than 0.16 for collagen. The value was 0.16 in the range of C₂ higher than 0.08, which was equal to that of the collagen. Dynamic shear modulus G′, loss modulus G″, and tan δ were determined as functions of RH. The gelatin film extended more than 100% at 73% RH under the very small stress of about 10⁷ dyn/cm². This corresponds to the region where β changes from 0.05 to 0.16, although such a phenomenon was not observed in the collagen film. The wide-angle X-ray pattern of extended gelatin was similar to that of renatured collagen fiber.     

Chemosensory basis of hostplant selection in the silkworm

Even the odors of many non-hostplant leaves have a phagostimulative function besides attraction for the silkworm, Bombyx mori. Consequently, the odor by itself emanating from any plant leaves can not give a significant cue for discriminating acceptable plants from non-acceptable ones. Finding of plant leaves from a certain distance and stimulation of feeding by odors were achieved through the functions of olfactory receptors in the antenna and maxillary palpus, respectively.The sugar and inositol receptors in the lateral hair and the bitter-substance receptor in the medial hair on the maxilla play relatively important roles in the response to various plant juices. The response pattern of these three receptors roughly correlates with the feeding response.The maxillary palpus has chemoreceptors which are sensitive to some olfactory and gustatory stimulants such as n-butyl propionate, morin, -sitosterol, etc. and in addition, it exerts an inhibitory influence upon feeding unless the amount of feeding stimulants in the diet reaches a certain sufficient level.In addition to synergistic interactions at the receptor sites, which were previously reported for the responses of the bitter-substance and salt receptors in the maxilla, antagonistic interactions were also observed. Some constituent occurring in Artemisia vulgaris leaves, of which the active principle was not identified chemically, was found to inhibit specifically the maxillary sugar receptor activity.The feeding response is influenced considerably by the amounts or ratios of the feeding stimulants. Accordingly, synergistic or antagonistic interaction of the mixture of chemical stimuli, rather than individual stimuli, is a significant determinant of the palatability of the diet.Compared with Hyphantria cunea, the feeding behavior of Bombyx is characterized especially by the high sensitivities for many kinds of feeding deterrents associated with various non-hostplants.

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Zusammenfassung Neben der Anlockwirkung hat sogar der Geruch vieler Nicht-Wirtsflanzen-Blätter auch eine fraßanregende Wirkung für die Raupen des Seidenspinners, Bombyx mori. Infolgedessen kann der von irgendwelchem Laub ausgeschiedene Duft selbst keinen signifikanten Aufschluß für die Unterscheidung von annehmbaren und abzulehnenden Pflanzen liefern. Das Auffinden der Pflanzenblätter aus einer gewissen Entfernung und die Fraßstimulation durch Geruchsreize werden mit Hilfe von olfaktorischen Rezeptoren gewährleistet, die in den Antennen bzw. den Maxillarpalpen liegen.Die Zucker- und Inositol-Rezeptoren im Lateralhaar und der Bitterstoff-Rezeptor im medialen Haar der Maxille spielen eine relative wichtige Rolle bei der Reaktion auf verschiedene Pflanzensäfte. Die Reaktionsmuster dieser drei Rezeptoren stehen grob mit der Fraßreaktion in Beziehung.Der Maxillartaster besitzt Chemorezeptoren, die für einige Duft- und Geschmacksstimulantien wie n-Butylpropionat, Morin, -Sitosterol usw. empfindlich sind, und außerdem eine Funktion, die dann eine Hemmung auf das Fressen ausübt, wenn die Fraßstimulantien in der Nahrung keine genügend hohen Beträge erreichen.Zusätzlich zu den synergistischen Wechselwirkungen auf Seiten der Rezeptoren, über die früher als Reaktionen der Bitterstoff- und Salz-Rezeptoren in der Maxille berichtet wurde, wurden auch antagonistische Wechselreaktionen beobachtet. Ein in Artemisia vulgaris-Blättern auftretender Bestandteil, dessen aktives Prinzip chemisch nicht identifiziert wurde, erwies sich als spezifischer Hemmer der maxillaren Zucker-Rezeptor-Aktivität.Die Fraßreaktion wird beträchtlich durch die Menge und den Anteil der Fraßstimulantien beeinflußt. Dementsprechend ist die synergistische oder antagonistische Wechselwirkung eines Gemisches chemischer Reize eher für die Annahme einer Nahrung ausschlaggebend als der einzelne Reizstoff.Verglichen mit Hyphantria cunea ist das Fraßverhalten von Bombyx besonders durch die hohe Empfindlichkeit gegenüber vielerlei Arten von Fraßabschreckstoffen gekennzeichnet, die bei verschiedenen Nicht-Wirtspflanzen auftreten.

     

Choice of extraction procedure for estimation of anterior pituitary hormone content

Searching for the best procedure for simultaneous estimation of the anterior pituitary hormones, extraction efficiencies of various media, additives such as urea and triton X-100, and physical treatments such as freezing-thawing (F-T) and sonication, were examined by measuring prolactin (PRL), growth hormone (GH), lutropin (LH), follitropin (FSH), and thyrotropin (TSH) in the extracts. Ethanolic media (60% EtOH) gave high yields of PRL at neutral to alkaline pH, but poor extraction of GH accompanied by a marked loss of its immunoreactivity during storage. Ethanolic media also gave a poor yield of LH even at high pH. Aqueous media like PBS at various pH, 0.1 M acetic acid and distilled water were considerably effective in the extraction of GH, LH, FSH and TSH if they were coupled with F-T and sonication. However, high yields of PRL could not be obtained with these aqueous media even with F-T and sonication. Hartree's 40% EtOH-6% ammonium acetate, pH 5.1, solubilized considerable amounts of glycoprotein hormones, but yielded almost no GH and only a small amount of PRL. The addition of triton X-100 to PBS (pH 7) at 0.1% resulted in the maximum extraction of glycoprotein hormones with homogenization and F-T, but further sonication was necessary for GH and PRL. When the anterior pituitaries were homogenized and frozen-thawed in PBS (pH 7) containing 1 M urea, yields of PRL, GH, LH, FSH, and TSH were maximum, and sonication did not cause any additional extraction, indicating that this procedure, i.e. homogenization and F-T in 1 M urea-PBS, would be the best for the simultaneous estimation of these anterior pituitary hormones.     

Phospholipid metabolism in bile duct-ligated rat plasma and erythrocytes

Incorporation of [32P]orthophosphate into phosphatidylcholine, lysophosphatidylcholine and molecular species of phosphatidylcholine in vivo was observed in liver, plasma and erythrocytes of bile duct-ligated or sham-operated rats. Both the amount and radioactivity of dienoic species of phosphatidylcholine in all tissues examined increased in bile duct-ligated rats as compared to sham-operated rats. The experiments in vivo and in vitro showed that the ratio of lysophosphatidylcholine to phosphatidylcholine transferred to erythrocytes from plasma in sham-operated rats was much higher than that in bile duct-ligated rats. It is suggested that one of the mechanisms by which abnormal erythrocytes appear might be explained by the facilitated and direct transfer of phosphatidylcholine, which is caused by the interaction of erythrocytes with bile acid in bile duct-ligated rat plasma.     

Calorimetric analysis of Escherichia coli in continuous culture

The heat evolution rate was measured in continuous culture of Escherichia coli k-12 on glucose-limiting medium. The specific heat production rate based on the dry cell mass increased in proportion to increase of dilution rate. The specific heat production rate based on a viable cell increased nonlinearly because the cell size varied in each dilution rate. Several thermochemical data were calculated for each dilution rate from the stoichiometric equation which was derived from elementary analysis of the cells. Growth yields based on energy measured directly was found to be less influenced by dilution rate than the growth yield based on consumed glucose. This suggested that the energy efficiency of utilization of catabolic energy for anabolism was almost constant.     

Identification of 5-Hydroxy Eicosatetraenoic Acid in Cerebrospinal Fluid After Subarachnoid Hemorrhage

Abstract: To detect and identify lipid peroxides in the CFS following subarachnoid hemorrhage (SAH), CSF samples were obtained sequentially from 10 patients who developed typical vasospasm and were analyzed by HPLC and gas chromatography-mass spectrometry. One of the peaks appearing on the 7th day after SAH was identified as 5-hydroxy eicosatetraenoic acid. On HPLC, an identical peak was detected in samples from other SAH patients. The results gave unequivocal evidence that peroxides of arachidonic acid are present in the CSF following SAH, and a correlation between them and the occurrence of vasospasm seemed likely. The hypothesis that lipid peroxides are involved in the genesis of vasospasm deserves further investigation.