Showing papers by "Kyushu University published in 1981"

Correlation of DNA exonic regions with protein structural units in haemoglobin

Abstract: The discovery of intervening sequences (introns) in DNA led Gilbert and Tonegawa to suggest that a new protein could have been produced by bringing together certain segments of pre-existing ones. However, Blake argued that if DNA was so organized that coding sequences (exons) correspond to structural as well as functional units of proteins, then combinations would be much more likely to yield a stable globular conformation through being 'sums of parts'. In immunoglobulin heavy chain, four separate exons encode four different units, all with distinct functions and three of which have clear domain structures. However, in haemoglobin, which has no obvious domain structure, no clear conformational characteristics have so far been recognized for the segments encoded by exons. From a close inspection of their conformations by drawing various stereodiagrams and the Calpha-Calpha distance map, I now propose a conformational characterization of the segments as structural units.

Evaluation of extensive lymph node dissection for carcinoma of the stomach.

Abstract: We compared the results of curative resection for carcinoma of the stomach in 254 patients who underwent simple resection (SR) and 454 patients who underwent extensive regional lymph node dissection (ELD). The 5-year survival rates of the 2 procedures were significantly different in carcinoma involving the serosa of the stomach; it was 45% in the ELD group and 18% in the SR group (p<0.001). In patients with regional lymph node metastasis we obtained a 5-year survival rates of 39% and 18% by ELD and SR, respectively (p<0.001). The incidence of metastasis to the secondary lymph nodes, removable only by ELD, was higher in cases with carcinomatous invasion of the deeper layers of the gastric wall, and this may have been the reason why ELD proved to be more effective than SR. ELD is discussed in relation to the site of the primary carcinoma and the extent of lymph node metastasis.

Noninteracting local-structure model of folding and unfolding transition in globular proteins. I. Formulation.

Abstract: Synopsis A statistical-mechanical model (a noninteracting local structure model) of folding and unfolding transition in globular proteins is described and a formulation is given to calculate the partition function. The process of transition is discussed in this model within the framework of equilibrium statistical mechanics. In order to clarify the range of applicability of such an approach, the characteristics of the folding and unfolding transition in globular proteins are analyzed from the statistical-physical point of view. A theoretical advantage is pointed out in studying folding and unfolding processes taking place as conformational fluctuations in individual protein molecules under macroscopic equilibrium at the melting temperature. In this case, paths of folding and unfolding are shown to be identical in the statistical sense. A key to the noninteracting local structure model lies in the concept of local structures and the assumption of the absence of interactions between local structures. A local structure is defined as a continuous section of the chain which takes the same or similar local conformation as in the native conformation. The assumption of the absence of interactions between local structures endows the model with the remarkable character that its partition function can be calculated exactly; thereby the equilibrium population of various conformations along the folding and unfolding paths can be discussed only by a knowledge of the folded native conformation.

Adsorption of lead, copper, zinc, cobalt, and cadmium by soils that differ in cation-exchange materials

Abstract: Summary The adsorption of Zn2+, Pb2+, Cu2+, Co2+, and Cd2+ (M2+) by soils was measured at concentrations ranging from 10-7 to 10-2 M in 10-3 to 10-2 M CaCI2. Exchange between Ca2+ and M2+, and solubility products [M2+][OH−]2 indicate that M2+ is not precipitated as hydroxide but is adsorbed on cation-exchange sites. The proportion of selective adsorption sites with specified values of the selectivity coefficient calculated using Ca as reference ion, increased in the order montmorillonite 10 000. The formation of the coordination complexes of heavy metal with deprotonoted OH and COOH groups as ligands is suggested as a possible mechanism of selective adsorption.

Excitation--contraction coupling in smooth muscle cells of the guinea-pig mesenteric artery.

Abstract: 1. The excitation—contraction coupling mechanism in the smooth muscle of the guinea-pig mesenteric artery was studied using intact and chemically skinned muscle cells. 2. The mean membrane potential of the intact smooth muscle was -65.8 ± 2.4 mV. It was electrically quiescent. Caffeine (5 m m), procaine (> 1 m m) and TEA (> 1 m m) depolarized the membrane, increased the membrane resistance and in their presence, outward current pulses evoked action potentials with overshoot. These potential changes were still observed in Na-deficient solution but were abolished in the presence of 3 m m-MnCl2. 3. Caffeine (5 m m) and TEA (1 m m) produced contractions in the intact muscle which were suppressed by procaine (5-10 m m). Caffeine (5 m m) continued to produce contraction even after prolonged exposure to Ca-free solution (containing 2 m m-EGTA) and this contraction was suppressed by procaine (5 m m). On the other hand, the K-induced contraction was rapidly abolished in 0-Ca. 4. Electrical stimulation (1 sec) in the presence of TTX (10−7 m) evoked a contraction. Caffeine (5 m m) and TEA (5 m m) enhanced but procaine (5 m m) suppressed the contraction. 5. Chemically skinned smooth muscle cells were prepared by adding saponin, 50 μg/ml., to the relaxing solution. The minimum concentration of free Ca required to evoke contraction in skinned muscle cells was 1-2 × 10−7 m and the maximum contraction was produced at 10−5 m. When Ca was replaced with Sr, the above relationship also shifted to the right (ED50 for Ca is 4.4 × 10−7 m and that for Sr is 1.5 × 10−5 m). Treatment with high concentrations of caffeine and procaine had no effect on the pCa—tension relationship. 6. Caffeine induced contraction in skinned muscle cells preloaded with Ca, and this contraction was markedly suppressed by procaine (5-10 m m). 7. In skinned muscles, depolarization of the internal membrane by replacement of K with choline (116 m m) in the relaxing solution produced contraction, but the amplitude was much smaller than the caffeine-induced contraction. 8. The relationship between the amplitude of caffeine-induced contraction and the duration of preincubation in various Ca concentrations was observed in skinned muscles. The minimum concentration of Ca required to produce a subsequent caffeine-induced contraction was itself below threshold for contraction. The results also indicate that the Ca-induced Ca release mechanism appears to modify the amount of Ca stored by preincubation in over 3 × 10−7 m free Ca. 9. When the amount of Ca stored in intact cells was estimated from the caffeine-induced contraction evoked in Ca-free solution following preincubation with Ca, Ca applied simultaneously with procaine increased and Ca with caffeine reduced the Ca stored in the cell. After preincubation in 2.5 m m-[Ca]o with 1 m m-procaine for 5 min, the amplitude of the subsequently generated caffeine-induced contraction (5 m m) in Ca-free solution (2 min) was much the same as that observed in 118 m m-[K]o. 10. The results support the view that the excitation—contraction coupling mechanism in the mesenteric artery may be as follows; the Ca inward current generated at the myoplasmic membrane may not directly provide the free Ca required to activate the Ca-receptor of the contractile protein, but the Ca carrying the inward current may first be sequestered inside the cell and activate a Ca release mechanism which in turn leads to contraction.

Morphometric Comparison of the Vulnerability of Peripheral Motor and Sensory Neurons in Amyotrophic Lateral Sclerosis

Abstract: The diameter histograms of cell bodies (cytons) in motor neuron columns at the L5 segment of the spinal cord of adult man reproducibly yield three peaks of increasing height: small (Cs), intermediate (Ci), and large (Cl). Histograms of L5 myelinated axons obtained from the ventral root have two peaks of increasing height: intermediate (Ai) and large (Al). In histograms prepared from seven cases of amyotrophic lateral sclerosis (ALS), the Cl and Al peaks were decreased selectively and severely. This provides evidence for alpha, but not gamma, motor neuron vulnerability. The Cl peak of spinal ganglion neurons and the Al peak of dorsal roots were significantly reduced in number, without a concomitant increase in Ci, Cs, and Ai peaks. This, plus earlier reports of abnormal cutaneous sensation thresholds, abnormal rates of fiber degeneration in cutaneous nerves, and dorsal column demyelination, provides evidence that large afferent neurons are affected in ALS, but to a lesser degree than alpha motor neurons.

Insulin acting as a modulator of feeding through the hypothalamus.

Abstract: To understand the functional role of insulin in the control of feeding, biochemical and physiological studies were performed in the rat. 1) Insulin content in the brain was much higher than that in the blood, and was extremely variable from animal to animal. 2) Specific binding sites of insulin in the brain were most abundant in the hypothalamus and olfactory bulb. 3) Neither insulin content nor binding sites in the brain was significantly affected by peripheral insulin concentration. 4) Activity of glucoreceptor neurons in the ventromedial hypothalamus (VMH) was facilitated by simultaneous application of insulin and glucose, but inhibited by insulin alone. 5) Activity of the glucose-sensitive neurons in the lateral hypothalamus (LHA) was facilitated by insulin in a dose-dependent manner. 6) Stimulation of the ventral part of the LHA accelerated pancreatic vagal nerve activity. Stimulation of the dorsal part of the LHA and the VMH was inhibitory. 7) Pancreatic splanchnic nerve activity during LHA stimulation tended to show inhibition, but sometimes was modulated by the stimulus frequency. Both inhibition and facilitation were observed in the activity in response to VMH stimulation.

Streaked flow around an oscillating circular cylinder

Abstract: When a circular cylinder oscillates transversely in water at rest, a three-dimensional streaming flow streaked with the chains of separated dye sheets is produced over a certain range of amplitude of the oscillation This paper reports observations of this three-dimensional flow instability

Noninteracting local-structure model of folding and unfolding transition in globular proteins. II. Application to two-dimensional lattice proteins.

Abstract: Synopsis The noninteracting local-structure model of the folding and unfolding transition in globular proteins, the formulation of which was given in the preceding paper, is applied to the analysis of the two-dimensional lattice model of proteins. The lattice model of proteins is a theoretical tool designed to study the statistical-mechanical aspect of the folding and unfolding transition. Its dynamics have been studied by a method of Monte Carlo simulation. The noninteracting local-structure model reproduces the equilibrium properties of the lattice model obtained previously by computer simulation remarkably well, when the specificity of the long-range interactions is strong. This observation indicates that the basic assumption of the noninteracting local-structure model is equivalent to the assumption of strong specificity of intramolecular interactions. It is argued that by assuming this strong specificity, we can emphasize the correct main paths of folding and unfolding transition. The way local structures grow and/or merge along the most probable path of folding in the lattice model is discussed by the noninteracting local-structure model.

Two major genes, linked to HLA and Gm, control susceptibility to Graves' disease

Abstract: Graves' disease is a multifactorial disease in which immunogenetic as well as environmental factors have important roles. Recently, cumulative evidence has shown that genes controlling immune responses are linked to the MHC (major histocompatibility complex)1 and/or immunoglobulin allotype genes2,3. To identify the genes governing susceptibility to Graves' disease, we have studied 30 Japanese families where more than two first degree relatives were affected with the disease. From genetic analysis of HLA (human MHC) and immunoglobulin allotype of all family members, we present here evidence for the existence of two genes controlling the susceptibility to Graves' disease, one closely linked to HLA-DR, the other linked to the gene coding for the Gm allotype.

Tannins and Related Compounds. I. Rhubarb (1)

Abstract: Three new tannin-related compounds (I, II and III), along with lindleyin (IV), (+)-catechin, 3-O-galloyl-(-)-epicatechin, gallic acid, 3, 5, 4'-trihydroxystilbene 4'-O-β-D-(6"-O-galloyl)-glucopyranoside, 3, 5, 4'-trihydroxystilbene 4'-O-β-D-glucopyranoside and 4-(4'-hydroxyphenyl)-2-butanone 4'-O-β-D-glucopyranoside, have been isolated from commercial rhubarb (Rhei Rhizoma). On the basis of spectral and chemical evidence, I, II and III were characterized as 3, 3'-di-O-galloylprocyanidin B-2, 3-O-galloylprocyanidin B-1 and 1, 2, 6-tri-O-galloylglucose, respectively. The occurrence of IV in rhubarb is of great significance, since IV has been reported to have analgesic and anti-inflammatory activities almost equal to those of aspirin and phenylbutanone. Tannins in rhubarb have been partially purified (designated as rhatannin (V)). Thiolysis degradation and enzymatic hydrolysis have shown that V is mainly composed of C4 to C8 linked 3-O-galloyl-(-)-epicatechin units in the extension part (upper part) with either 3-O-galloyl-(-)-epicatechin or (+)-catechin unit in the lower terminal part.

Bacteria and gallstones. Etiological significance.

Abstract: Two hundred consecutive gallstone cases have been subjected to bacteriological study employing improved anaerobic culture techniques. In addition to Clostridia species, species of anaerobes such as Bacteroides fragilis, Peptococcus, Veillonella, and Eubacterium are found to be present, some of which possessed beta-glucuronidase activity. This finding has a certain bearing on the etiology of bile pigment calcium stones. In addition to Escherichia coli, Bacteroides and Clostridium often found in the biliary tract may contribute to the formation of bile pigment calcium stones by producing beta-glucuronidase and thus deconjugating bilirubin diglucuronide to form free unconjugated bilirubin which in turn combines with calcium, leading to stone formation. In contrast, very low bacterial incidence was associated with cholesterol stones and so-called black stones--sometimes called pure pigment stones--and thus bacteria play little role, if any, in their formation. Therefore, bile pigment calcium stones and so-called black stones, which are often classified as pigment stones indiscriminately, should be differentiated not only because of their difference in their appearance and composition but also in their etiological background. Regardless of the kind of stones present in the common duct, the incidence of bacteria was found to be increased.

N‐substituted poly(p‐phenylene terephthalamide)

Abstract: N-substituted poly(p-phenylene terephthalamide)s (PPTA), such as N-alkylated, N-aralkylated, and N-carboxymethylated poly(p-phenylene terephthalamide), were synthesized from PPTA and the corresponding halides by the polymer reaction via the metalation reaction in a solution of sodium methylsulfinylcarbanion in dimethyl sulfoxide at low temperature. The introduction of various substitutional groups into the amide groups of PPTA increased their solubilities, but decreased their thermal stabilities compared with PPTA. The effects of various substitutional groups on the thermal properties and the solubilities are discussed. Liquid crystal formation was noticed for PPTA substituted with bulky groups such as 9-anthrylmethyl group.