Endoplasmic reticulum (ER)-enriched vesicles from etiolated hypocotyls of mung bean seedlings (
Vigna radiata L.) were isolated by Ficoll gradient and two-polymer phase partition. These ER-enriched ...vesicles contain a new type of H
+-pyrophosphatase (H
+-PPase) distinct from that of tonoplasts in higher plants. H
+-PPase was then solubilized differentially by deoxycholic acid and lyso-phosphatidylcholine. The solubilized fraction was then subjected to Sephacryl S-200 gel filtration and Mono-Q anion exchange chromatography. The final purified protein complex of ER H
+-PPase (ER-PPase) was successfully obtained to high homogeneity. An approximate molecular mass of 170
kDa was determined for the purified ER-PPase by size-exclusion gel filtration chromatography. However, only a single polypeptide of 74
kDa was observed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Moreover, radiation inactivation analysis of ER-enriched vesicles and purified ER-PPase yielded functional masses of 178.6
±
9.2 and 143.4
±
4.7
kDa for inorganic pyrophosphate hydrolysis activity, respectively, indicating that ER-PPase was functionally homodimeric.
Liver has a remarkable ability to regenerate after major resection. However, little is known about the process of morphological regeneration and hepatic functional recovery in human.
Sixteen donors ...who underwent right hemihepatectomy were enrolled in this prospective clinical study. The preoperative liver volume and remnant liver volume on postoperative days 5, 12 and 28 were calculated from serial transverse computed tomography images. Liver function was evaluated by measuring the intrinsic clearance of antipyrine before and on postoperative days 5 and 12 days, as well as the biochemical and coagulation assay.
A smaller residual liver tended to regenerate faster in 28 days. Operative factors, including intraoperative blood loss, inflow occlusion time, liver transection time and duration of operation were not significantly correlated with postoperative liver regeneration. The intrinsic clearances of antipyrine on postoperative days 5 and 12 days were significantly reduced compared to the respective values before the operation (p < 0.001 and p < 0.05, respectively). On the contrary, the intrinsic clearance values per unit liver volume significantly increased on postoperative 12 days (p < 0.05).
The microsomal function of individual hepatocytes may be upregulated after right liver resection perhaps in order to compensate for the reduced functional mass of the liver.
Chloroplast thylakoid contains several membrane-bound protein kinases that phosphorylate thylakoid polypeptides for the regulation of photosynthesis. Thylakoid protein phosphorylation is activated ...when the plastoquinone pool is reduced either by light-dependent electron flow through photosystem 2 (PS2) or by adding exogenous reductants such as durohydroquinone in the dark. The major phosphorylated proteins on thylakoid are components of light-harvesting complex 2 (LHC2) and a PS2 associated 9 kDa phosphoprotein. Radiation inactivation technique was employed to determine the functional masses of various kinases for protein phosphorylation in thylakoids. Under the photosynthetically active radiation (PAR), the apparent functional masses of thylakoid protein kinase systems (TPKXs) for catalyzing phosphorylation of LHC2 27 and 25 kDa polypeptides were 540±50 and 454±35 kDa as well as it was 448±23 kDa for PS2 9 kDa protein phosphorylation. Furthermore, the functional sizes of dark-regulated TPKXs for 25 and 9 kDa proteins were 318±25 and 160±8 kDa. The 9 kDa protein phosphorylation was independent of LHC2 polypeptides phosphorylation with regard to its TPKX functional mass. Target size analysis of protein phosphorylation mentioned above indicates that thylakoid contains a group of distinct protein kinase systems. A working model is accordingly proposed to interpret the interaction between these protein kinase systems.
In CCl4-induced liver injury of rats, a hepatic microsomal functional mass measured by the 14C-aminopyrine breath test (ABT) was assessed, following 40% partial hepatectomy, and hepatic protein ...synthesis was also measured. The CCl4 group had lower ABT values than the normal group, but the difference was not significance. After 40% partial hepatectomy, the ABT values decreased in the CCl4 group more than in the normal group (p<0.05), and the return to the normal values was retarded in the CCl4 group, survivors after 40% partial hepatectomy had higher ABT values (68±29%) preoperatively than that of deaths (16.9±2.7%). The difference was significance (p<0.05). Hepatic protein synthesis in the CCl4 group was 3.6-fold greater than that in the normal group and was inversely correlated with the values of ABT (r=0.881 p<0.001). However there was no difference in hepatic protein content between the two groups. In conclusion, ABT is a good indicator of hepatic functional reserve in CCl4-induced liver injury. Enhancement of hepatic protein synthesis would induce depression of the hepatic functional reserve measured by ABT.
We evaluated perioperative changes in hepatic functional mass in patients who underwent hepatectomy using the galactose tolerance test, which specifically measures metabolism in liver cytosol. ...Preoperative T-1/2 values on the galactose tolerance test (GaTT-T/2) were significantly prolonged in various hepatobiliary diseases including primary liver cancer and liver cirrhosis (p<0.001), obstructive jaundice (p<0.01), secondary liver cancer and cholelithiasis (p<0.05) in comparison with control subjects. In hepatectomized patients, GaTT-T/2 was the most markedly prolonged at two to five weeks after surgery, but recovered to preoperative values six to eighteen weeks postoperatively. The GaTT-T/2 value at one week after hepatectomy was a good indicator of postoperative course. Furthermore, the ratio of GaTT-T/2 at one week after surgery to the preoperative value was positivery correlated with the parenchymal hepatic resection rate (r=0.799, p<0.001). The perioperative measurement of GaTT-T/2 could be a useful indicator of cytosolic functional mass of the liver in patients who undergo hepatectomy.
Hepatic functional mass was evaluated in patients with obstructive jaundice using the galactose tolerance test (GaTT), which reflected cytosolic function of hepatocyte. The T-1/2 values as an index ...on the GaTT were significantly prolonged in patients with obstructive jaundice in comparison with control subjects whether before or after percutaneous transhepatic biliary drainage (PTBD). But in each cases, some showed nearly normal GaTT-T/2 value and others showed severely prolonged value. Patients with obstructive jaundice could be devided into two groups according to the GaTT-T/2 value before PTBD. The decreasing rate of serum bilirubin level "b" after PTBD was significantly fair in the group A patients (good GaTT-T/2 value before PTBD) than the group B (poor GaTT-T/2 value before PTBD) (P<0.05). It was that GaTT-T/2 before PTBD which represented hepatic cytosolicfunctional mass could predict the effect of PTBD in patients with obstructive jaundice.
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