Characterization of skeletal muscle calsequestrin by 1H NMR spectroscopy

Calsequestrin (Mr = 44,000) is a calcium-binding (KD congruent to 1 mM, congruent to 50 sites/molecule) protein found in the lumen of the sarcoplasmic reticulum of skeletal muscle. The 1H NMR spectrum of calsequestrin in the calcium-free form is presented and is characteristic of a protein largely in the random coil configuration. A number of peaks in the aromatic region have been assigned based on their chemical shifts and sensitivity to pH. The interaction of this protein with Ca2+ and K+ was studied by 1H NMR. Potassium ion binding to calsequestrin caused broadening and concomitant loss of intensity in both the aromatic and aliphatic regions of the spectrum. Calcium ion binding caused similar effects but at much lower metal ion concentrations. It was found that the binding of Ca2+ to calsequestrin was cooperative (Hill coefficient n = 2.9 +/- 0.2) with a dissociation constant of 0.25 +/- 0.06 mM in the absence of K+. In contrast, K+ showed binding to a single class of independent sites (KD = 0.20 +/- 0.04 M). Calcium binding was also studied by circular dichroism at protein concentrations similar to the NMR experiments. The binding profile and cooperativity (n = 2.0 +/- 0.1, KD = 0.19 +/- 0.04 mM) were in agreement with the 1H NMR results. Circular dichroism studies performed at low protein concentrations to reduce the possible effect of calcium binding on the concentration of free calcium gave similar values of n = 2.42 +/- 0.14 and KD = 0.21 +/- 0.005 mM. This cooperativity was also observed in the presence of 100 mM KCl although the affinity for calcium has been significantly reduced (n = 1.65 +/- 0.09, KD = 0.87 +/- 0.036 mM). In view of the large number of calcium binding sites in calsequestrin, these small Hill coefficients show that calcium binding to calsequestrin is only mildly cooperative.

Cancer-associated alteration of beta-glucuronidase in human lung cancer: elevated activity and increased phosphorylation

beta-Glucuronidase from human lung neoplasms of various histological types and from uninvolved tissues was studied. A significant elevation of beta-glucuronidase activity was observed in adenocarcinoma and squamous cell carcinoma of the lung as compared with the corresponding uninvolved tissues (P less than 0.01). Saccharo-1,4-lactone, a strong inhibitor of the enzyme, exhibited a substantially greater stabilizing effect on the adenocarcinoma enzyme than on the other enzymes. However, removal of the carbohydrate moiety from the adenocarcinoma enzyme by treatment with endo-beta-N-acetylglucosamidase H (endoglycosidase H) brought about a decrease in the stabilizing effect. Tumor beta-glucuronidase showed considerable negative charge heterogeneity in the pI range from 4.2 to 6.2 in isoelectric focusing on polyacrylamide gel. Upon treatment with exogenous alkaline phosphatase or endoglycosidase H, the heterogenous variant forms of the tumor enzyme appeared to partly or completely lose their negative charge and to be converted into forms similar to those of the normal lung enzyme. These data strongly suggest that the variants are highly phosphorylated on the oligosaccharide chains of the enzyme. An experiment on the labelling of beta-glucuronidase with [32P]-phosphoric acid provided further evidence that the acidic variants found in lung cancers are extensively phosphorylated forms of the enzyme.

Structures of Dianosides A and B, Analgesic Principles of Dianthus superbus var. longicalycinus Herbs1

Novel triterpenoid saponins, dianosides A and B, showing analgesic activity, have been isolated from DIANTHUS SUPERBUS var. LONGICALYCINUS herbs. Degradative and spectroscopic studies have established their structures as shown in formulas 1 and 2.

Studies on the delayed neurotoxicity of organophosphorus compounds--(II)

Delayed neurotoxicity experiment was carried out on an organophosphorus compound (TOCP) in hens. Fifteen hens, 1.9 kg of their average body weight and 20 months of age, were orally administered with TOCP in a dose of 400 mg/kg body weight. Two animals out of 15 were sacrificed after 7 days to examine alterations in the nervous system under electron microscope. On the remaining 13 animals, histopathological examinations were carried out after 35 days. During the course of the experiment, progressive neuropathy developed in the animals at 10 to 12 days after the exposure to TOCP. Examinations of the sciatic nerve under electron microscope revealed slight axonal degeneration while the myelin sheath was found to be rather intact. On the animals after the observations periods of 35 days, marked axonal and myelin degeneration was observed in the anterior and posterior funiculus, and in the spinocerebellar tracts of the spinal cord as well as in the cerebellar peduncle and in the white matter of the cerebellum associated with glial proliferation. The localization and degree of these changes were considered to be "Dying Back", showing systemic neuropathy. Moreover, the morphological alterations of the nerve cells were observed in the Purkinje cells, in the cerebellar nucleus, gracilis nucleus, and anterior horn cells of the lumbar spinal cords, characterized by loss of nerve cells and/or tigrolysis. Muscular lesions showed small group atrophy, corresponding to Type I fiber atrophy.

Elevated activity of beta-hexosaminidase and sulfhydryl modification in the B-variant of human lung cancer

Activities of beta-hexosaminidase A and beta-hexosaminidase B (Hex B) were measured both in human lung carcinoma and the adjacent normal tissues of 47 patients. The specific activity of total beta-hexosaminidase in the tumors was considerably higher than in the adjacent normal tissues, irrespective of histological types. In isoelectric focusing experiments, Hex B purified from normal lung exhibited a single peak with an isoelectric point (pI) of 7.9, while Hex B purified from adenocarcinoma contained two forms with pI 7.6 and 7.9. With respect to heat stability, Hex B from the normal lung was very stable at 52 degrees, while the tumor Hex B (mixture of pI 7.6 and 7.9 forms) was unstable. After treatment of the tumor enzyme with dithiothreitol, heat stability was restored. When the tumor pI 7.6 form was treated with dithiothreitol and subjected to polyacrylamide gel electrophoresis, the enzyme converted to a pI 7.9 form similar to that of the normal lung. Determination of the sulfhydryl group of the tumor pI 7.6 form under nondenaturing conditions showed that the enzyme had some easily reducible disulfide bonds on its surface. These findings indicate that the formation of mixed disulfide bonds in the tumor Hex B increases the net negative charge and results in the appearance of a heat-labile form.

RT1-linked Ir and Is genes control the immune response to bovine insulin in the rat

The immune response to bovine or pork insulin (BI or PI, respectively) was studied in the rat using the in vitro insulin-induced lymphocyte-proliferation assay. Results indicated that 11 inbred rat strains were divided into categories of high and low responders. Two high responders, SDJ (RT1u) and BN(RT1n) inbred rat strains, appeared to recognize different antigenic determinant(s) on the insulin molecule. The results of linkage and segregation analyses in F1, F2, backcross, and partially congenic rats showed that the Ir gene (Ir-BI), which encodes the high responsiveness in the SDJ rats, is inherited associated with RT1u, whereas the immune suppression gene (Is-BI), which encodes the low responsiveness in the WKA(RT1k) rats, is inherited together with RT1k. The Is-BI is the first major histocompatibility complex (MHC)-linked Is gene reported in the rat. The LEJ(RT1-AuBb) inbred rat strain showed a low response to BI, indicating that Ir-BI is closer to RT1-B/RT1-D region than to RT1-A.

[Difference in motility between anterior and posterior gastric wall after anterior and/or posterior truncal vagotomy]

The present experiment was designed to see the effect of anterior or posterior truncal vagotomy on the movement of anterior and posterior walls of the stomach with the use of electromyography and force transducer. A total of 28 dogs were prepared with strain gages and bipolar electrodes at both anterior and posterior walls of the stomach. Three types of vagotomy, namely, anterior, posterior and bilateral truncal vagotomy were carried out consecutively or independently. Postoperatively, myoelectrical and contractile activities were compared between the anterior and the posterior wall of the stomach at fasted and fed state. Results are summarized as follows: 1) Motor activity of the control dogs could be divided into digestive, intermediate and interdigestive patterns. 2) Following 3 types of vagotomy, an appearance of the interdigestive pattern showed a tendency of delay which was more evident after the posterior than after the anterior truncal vagotomy. 3) There was little difference in contractile force of the antrum before and after 3 types of vagotomy, except that the hunger contraction was found weaker after all the 3 types of vagotomy. Vagotomy showed little effect on the frequency of basic electrical rhythm at any conditions. 4) In any observation mentioned above, there was no significant difference in the gastric motility between the anterior and posterior wall of the stomach. In conclusion, the patterns of motor activity were more affected after the posterior than after the anterior truncal vagotomy. Little difference in gastric motility, however, was found between the anterior and posterior wall of the stomach after all the 3 types of vagotomy.

Purification and characterization of troponin C from pike muscle: a comparative spectroscopic study with rabbit skeletal muscle troponin C

The conformation of troponin C (TN-C) isolated from the white muscle of pike (Esox lucius), in the Ca2+ and metal-free states, was studied by circular dichroism, absorption difference spectroscopy, solvent perturbation difference spectroscopy, intrinsic fluorescence, thiol titration, and 1H nuclear magnetic resonance spectroscopy. In addition, the molecular weight of the protein was determined by sedimentation equilibrium and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The composition of the protein was established by amino acid analysis. The resulting data were compared with those from the widely studied analogue isolated from rabbit skeletal muscle. The results indicate near equivalence in many of the properties of pike and rabbit TN-C, such as molecular weight, the magnitude of the calcium-induced conformational change, and urea- or thermal-induced denaturability. However, the pike protein has five additional potential carboxyl groups, and there is good evidence from NMR, solvent perturbation, and fluorescence studies for the presence of a buried tyrosine residue in the apo state.

Intravascular coagulation in mice by the compact-colony-forming active substance (CCFAS) extracted from a strain of Staphylococcus aureus

The compact-colony-forming active substance (CCFAS) extracted from a Staphylococcus aureus strain was capable of killing mice only when Staph. aureus, Staph. epidermidis or Escherichia coli was injected i.v. before the injection of CCFAS. In the mice killed 30 min after treatment with heat-killed Staph. aureus and CCFAS, remarkable congestion of the lung and thrombus-like lesions in the kidney were observed. In the mice killed 6 h after injection with CCFAS and living Staph. aureus congestion and inflammatory-cell filtration were found in the liver, especially within the Glisson's capsule. However, when mice were killed 30 days after treatment with CCFAS and Staph. aureus, fibrin and hyalin thrombi were observed most frequently in the renal glomeruli but also in the liver and lung.

Studies on the delayed neurotoxicity of organophosphorus compounds- (I)

Delayed neurotoxicity experiments of an organophosphorus compound, TOCP, on hens and quails were carried out. The animals were orally exposed with TOCP in dose of 400 mg/kg, and maintained for 25 and 50 days under observation, respectively. They were sacrificed and dissected at different periods after the exposure, and the histopathological examinations were made on those animals. During the periods of 50 days, no abnormal symptoms except for acute poisoning were noted in the quails. As to the hens, neurological disorders were observed from around 12 days of the experiment. In hens, the morphological alteration in the earlier stage of the experiment was perivascular cuffing of small round cells seen in the cerebrum, cerebellum and spinal cord. The major alteration was degeneration of axons and myelin in the white matter of the spinal cord. A minimal degree of these changes was found even in the hens in which the clinical signs of neurotoxicity had not yet been observed. Later the process expanded to the whole spinal cord as well as the sciatic nerve. The electron microscopy performed after 15 days revealed moderate change of myelin and axons. From these results, it was concluded that the clinical signs as well as the morphological changes were closely related to the exposure of the compound, TOCP.

A scanning electron microscopic study on the liver of mice

The three-dimensional fine structures of several tissue components of the liver in normal mice were studied by scanning electron microscopy. The tissue components observed were as follows: hepatocytes, sinusoidal endothelial cells, the Kupffer cells, fat-storing cells, reticulin fibers and epithelial cells of the bile duct. Two types of fenestrations were found in the sinusoidal endothelial cells. One was smaller and clustered, and the other larger and scattered. Both of them were distributed equally throughout the hepatic lobule. Intercellular gaps were found at the endothelial junction. The Kupffer cell which was localized in a large gap between the endothelial cells was characterized by numerous villous projections, and by the absence of fenestrations which were observed in the endothelial cells. Fat-storing cells were located between hepatocytes. They elongated their processes into the space of Disse, but never protruded into the sinusoidal lumen. They were clearly distinguished from the endothelial cells and the Kupffer cells by their morphological feature and location. No transitional form was seen among the endothelial cells, the Kupffer cells, and the fat-storing cells.

A scanning electron microscopic study on hepatic changes induced by mouse hepatitis virus-2

No significant changes in the structure of the liver were seen until 9 hr after the inoculation of mouse hepatitis virus-2 (MHV-2) into mice. At the 24 hr stage, distinct swelling of hepatocytes and narrowing of sinusoidal lumina were observed from the middle to the central area of the hepatic lobules. Most of the Kupffer cells were swollen. Their villous projections were decreased in number, and the remaining projections became like blebs. Virus particles appeared from this stage in the hepatocytes, the Kupffer cells and the space of Disse. At the 48 hr stage, parenchymal necrotic foci were present in the central and the middle area of the lobules. The necrotic change was increased from 72 hr after inoculation, and was followed by submassive or massive necrosis. It is suggested that hepatic necrosis in both the central and the middle area, or in either area, of the lobules was advanced by aggravation of the sinusoidal microcirculation, as a result of the swelling of the hepatocytes and the Kupffer cells in addition to the direct affection by virus. Fine granulation was observed on the surface of most of the central flagella of the bile duct. Some flagella were degenerated, and came in part to be a fibrillar net.