The colorimetric method of Seligman 3) for the assay of carboxypeptidase (CPase) A in pancreatic juice has been modified for measurement of CPase A activity in serum, as shown in TABLE I. The following results were obtained on hydrolytic activity of carbonaphthoxy-Lphenylalanine in this reaction system.
1) No effect was observed by the addition of diisopropyl fluorophosphate, cyanide, trypsin or epsilon amino caproic acid, respectively.
2) The activity was inhibited by dialysis against phenanthroline solution, and was recovered by the addition of Zn+ ions.
3) Further addition of the substrates for CPase A (different from carbonaphthoxy-L-phenylalanine) inhibited this reaction, whereas the presence of CPase B substrate showed no effect.(Fig.1)
In various organs of human beings and dogs, the pancreas was found as the only organ which has a rich activity of CPase A, while a trace activity was observed in the kidney.
The serum CPase A level that decreased following the initial elevation was observed in experimental bile pancreatitis of a dog.(Fig.2)
The mean serum CPase A activity in 34 normal subjects was 234 U/ml (range 158-310 U/ ml), and no significant difference was found between the mean values of normal men and women.
In some cases with different diseases, the serum CPase A level was changed. According to our investigations, almost all cases of pancreas cancer, 70% of liver cirrhosis and 40% of chronic pancreatitis showed a lower level of this enzyme activity, and cases of nephrosis, lupoid nephritis and Kimmelstiel-Wilson syndrome also showed a decreased activity in serum.(Fig. 4)
The serum CPase A level in a patient who had undergone total pancreatectomy dropped down rapidly, and only a negligible activity was found 3 weeks after the operation, while serum levels of total protein, choline esterase and amylase showed minor changes during the same clinical course, respectively.(Fig. 3)

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膵外分泌酵素の一つであるCarboxypeptidase A (CPase A) の生理学的ならびに病態生理学的動態については不明である. 今回, われわれは本酵素の生理学的ならびに病態生理学的動態について実験的ならびに臨床的に検討した. 膵液中のCPase A活性はP-S連続刺激下でAmylase値と同様の変動を示した.急性膵炎時は血清CPase A活性は軽度の上昇がみられたにすぎなかった. 膵全剔, および膵管結紮後では血清CPase A活性は経日的に著明に低下した. 確認した膵癌17例の術前CPase A活性は低値を示すものが多く, 特にビマン性はものに著明であった. これらの成績から, 本酵素活性は膵液中に高濃度に存在し, 血清CPase A活性は膵外分泌障害時に低値を示したこの事実から, 本酵素の測定は膵疾患の存在を推測する一つの方法として有用と推測された.

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This report is concerned with the colorimetric assay method of carboxypeptidase A activity in serum using carbonaphthoxy-L-phenylalanine (CNPA) as a substrate and the hydrolytic activity of CNPA in this reaction system.
1) No effect was observed with the addition of DFP, cyanide, trypsin or epsilon aminocaproic acid.
2) Activity was inhibited by dialysis against o-phenenthroline solution, and recovered with the addition of Zn^{+ +} ions.
3) Further addition of the CPase A substrates (different from CNPA) inhibited this reaction, whereas the presence of CPase B substrates showed no effect.
4) In organs of humans and dogs, the pancreas was found as the only organ which was rich in CPase A activity, while traces of activity were observed in the kidneys.
5) The mean serum CPase A activity in 28 normal subjects was 289.2±3.8 units (range 272.0-312.4 units).
6) In almost all subjects with pancreatic cancer, and in some subjects with liver cirrhosis, chronic pancreatitis, diabetes mellitus, cholelithiasis, or chronic glomerulonehritis, a low level of serum CPase A activity was observed.
7) The serum CPase A level in a patient who had undergone a total pancreatectomy dropped rapidly, and only negligible activity was found 3 weeks after the operation, while serum levels of total protein, cholinesterase and amylase showed minor changes during the same clinical course.
8) It was observed that amylase activity and CPase A activity in serum changed inversely in experimental pancreatitis.
Moreover, this amylase activity and CPase A activity varied in inverse proportions to each other.

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The Serum carboxypeptidase A activity (CPase) was measured in patients with various diseases using Okuda's colorimetric method. The relationships between CPase and case history, the results of the liver function test and the exocrine function test of the pancreas were studied. The following results were obtained.
(1) The mean CPase in 21 normal subjects was 289.2±3.8 units (U.)(Mean±SE), and no correlation was found between CPase and age of the patients.
(2) CPase in 13 cases of pancreatic cancer verified by laparatomy, and that in 16 cases of chronic pancreatitis, diagnosed by clinical history, physical and laboratory findings, were 168.7±7.5 and 231.6±9.6 U. respectively.
(3) CPase of 14 cases of growth-onset type and 26 cases of adult onset type diabetes were 248.0±22.8 U. and 257.6±6.5 U. respectively. Among these diabetics, relatively lower CPase levels were observed in patients of long duration whose control had been poor.
(4) CPase level in patients with cirrhosis of the liver was 197.3±9.9 U, especially low in heavy drinkers.
(5) In cases of cirrhosis of the liver, significant correlation was observed between CPase and serum albumin concentration (P<0.05) or serum pseudocholinesterase activity (p<0.05).
(6) Relatively low level of CPase was often observed in patients with normal pancreatic exocrine function judged by pancreozymin secretin test.
(7) Low levels of CPase were observed in patients whose pancreatic scanning showed abnormality. The determination of CPase seems to be one of the useful screening methods for pancreatic disorders.

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Five rolling contact fatigue tests, Tests (1)∼(5) were conducted. In Tests (1)∼(3), in the first step, when a fatigue crack was initiated on the surface of a follower, the test was stopped. In the second step, the rotating direction was reversed in Test (1), the roles of follower and driver were exchanged in Test (2), and the same test as the first step was continued in Test (3). In Test (3) the original crack grew to a pit. On the other hand, in Tests (1) and (2) the original crack immediately ceased propagating. In Tests (4) and (5), mating with a harder roller, a softer roller was used as the follower in Test (4) and as the driver in Test (5). A typical arrowhead pit appeared in Test (4). In Test (5), however, surface damage substantially different from a typical pit was generated. Based on the experimental results, the mechanism of pit formation was analyzed by 3-D crack analysis, in which the effects of frictional force on contact surface and oil hydraulic pressure on crack surfaces were considered in particular.

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