Research review: DNA polymerases as molecular markers of the regenerating capacity of hepatocytes

Hepatocyte regeneration has been widely investigated, with the mitotic index and the incorporation of [³H]thymidine being used as regeneration markers. We focused on the induction of DNA replication enzymes, particularly DNA polymerases (pol) α, δ, and ε. Using rat models, we have shown that the activity of pol α in crude liver extract well represents the regenerating capacity of hepatocytes. Using pol α as an indicator, we analyzed liver regeneration in rat models under various conditions: obstructive jaundice, external or internal biliary drainage, and the obstruction of portal vein branches. It has been revealed that the ligation of the common bile duct alone induces a certain amount of hepatocyte proliferation. It was striking that external biliary drainage suppressed regeneration capacity in cholestatic rat liver after partial hepatectomy. The strong regeneration in nonligated lobes induced by portal branch ligation was similar to the liver regeneration seen after partial hepatectomy with respect to the induction of DNA polymerases. Taken together, the aspects of DNA replication, particularly the induction of DNA polymerases, may contribute to shedding new light on the regeneration of human liver. This work was supported in part by a Grant-in-Aid for General Scientific Research and for Cancer Research from the Ministry of Education, Science and Culture, Japan, and by grants from the Uehara Memorial Foundation     

Effect of Oral Administration of A Prostacyclin Analog (Op-41483) On Pulmonary Function and Bronchial Responsiveness in Stable Asthmatic Subjects

To examine whether prostacyclin has an attenuating effect on nonspecific bronchial responsiveness in asthma, we measured provocative concentration of methacholine producing a 20% fall in forced expiratory volume in 1 second (PC₂₀-FEV₁) before and after oral administration of a chemically stable prostacyclin analog (OP-41483) (200 μg 4 times a day for 4 days) in 8 patients with stable asthma. Neither baseline pulmonary function nor PC₂₀-FEV₁ significantly improved after the treatment. These results suggest that prostacyclin may have no direct effect on bronchial responsiveness in asthmatics. Further studies using more potent and long-lasting prostacyclin mimetic will be needed to confirm the conclusion.     

Ethylnitrosourea-induced apoptosis in primordial germ cells of the rat fetus.

Ethylnitrosourea (ENU) is a simple alkylating agent. It induces gene mutations in fetal primordial germ cells (PGCs), and a high incidence of congenital malformations is also found in the offspring of male mice treated with ENU at the embryonic stage. It is also reported that decreases in the fertility rate and weights of the testis and ovary were found in the offspring from dams treated with ENU. In this study, we analyzed the occurrence of apoptotic cell death and the expression of p53 protein which is thought to play an important role in the DNA damage-induced apoptosis after administration of ENU to pregnant rats on day 13 of gestation to obtain a clue for clarifying the toxic effect of ENU on PGCs. Apoptotic cells increased in PGCs in fetal gonads from 3 h after treatment. The number of apoptotic PGCs peaked at 6 h and gradually decreased towards 24 h after treatment. On the other hand, p53-positive PGCs increased from I h after treatment, prior to the induction of apoptosis. The number of p53-positive PGCs peaked at 3 h and returned to the control level at 24 h after treatment. These results suggest that ENU induces apoptosis in rat fetal PGCs immediately after its administration to dams and excess cell death by apoptosis may have a close relation to the later occurrence of decreases in the fertility rate and gonadal weight. Moreover, a possible involvement of p53 is suggested in the ENU-induced apoptosis in PGCs.     

Experimental Hydrocephalus in Suckling Hamster Induced by Myxovirus Infection

Abstract This study was undertaken to elucidate the pathogenesis of the hydrocephalus and aqueductal stenosis induced by intracerebral mumps virus inoculation in suckling hamsters.
Mild ventricular dilatation became apparent after 5 days of inoculation. Focal denuding of the ependymal layer and subsequent aqueductal stenosis were observed by 14 days after inoculation. The virus antigen was detected not only in the ependymal cells and choroid plexus, but also in some neurons in the cerebral cortex, hippocampus, midbrain and cerebellum. In the cerebral aqueduct, the orderly arrangement of the cilialy clusters was destroyed on the 5th day after inoculation. After 10 days, proliferation of GFAP positive cells was noticed around the cerebral aqueduct and subsequently caused aqueductal stenosis. In the advanced state of hydrocephalus, the cerebellum was displaced downward and showed an elongated, atrophic and sleevelike structure similar to the Arnold-Chiari malformation. It was suggested that the extensive damage of the ependymal cilia may account for early ventricular dilatation, and subsequent aqueductal stenosis with glial proliferation is the main cause of the advanced hydrocephalus. It has not yet been determined whether the mumps virus can pass through the human placenta or not. If it can, however, our results strongly suggest that mumps virus infection in the human fetus will cause congenital hydrocephalus.     

Small extra-adrenal pheochromocytoma causing severe hypertension in an elderly patient.

We report the case of a 67-year-old woman with severe hypertension caused by an extra-adrenal pheochromocytoma. The tumor was detected by 131I metaiodobenzylguanidine scintigraphy and it was found to be small (2 cm ?) by enhanced CT. After the extirpation of the tumor, the blood pressure of the patient immediately normalized. It should be taken into account that a small extra-adrenal pheochromocytoma can be one of the causes of secondary hypertension in elderly patients. Since small extra-adrenal pheochromocytomas are difficult to detect, it is also important to perform suitable examinations to establish the diagnosis. Furthermore, we emphasize the importance of an accurate diagnosis in elderly patients with pheochromocytoma, for they often have less symptomatology and more severe cardiovascular complications due to refractory hypertension than younger patients.     

Increase of striatal dopamine turnover by stress in MPTP-treated mice

The characteristics of motor function and brain dopamine (DA) metabolism in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice after immersion immobilization stress were investigated. There was no significant difference in locomotor activities between MPTP-treated and saline-treated mice, but locomotor activities of MPTP-treated mice after stress decreased more remarkably than those of saline-treated mice. Immediately after stress, striatal DA concentrations of MPTP-treated mice were significantly lower than those of saline-treated mice. Striatal DA levels improved when 24 h passed after stress. The striatal and cortical (DOPAC + HVA)/DA ratios of MPTP-and stress-treated mice was significantly higher than that of saline-and stress-treated mice. It is due to the decreased DA level and the enhancement of DA turnover that MPTP-treated mice became remarkably akinetic after stress, and that L-DOPA therapy is not effective when the symptoms in patients with Parkinson's disease worsen due to stress.     

Single photon emission computerized tomography in childhood hydrocephalus

Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by ¹²³I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome.     

In vivo detection by microscopic chromocystoscopy of concurrent urothelial atypia in superficial bladder cancer.

Microendoscopic observation of methylene blue-stained urothelial surfaces, so-called microscopic chromocystoscopy (MCC), was undertaken in 65 patients with superficial bladder cancer (Ta and T1) and its effectiveness in detecting concurrent urothelial dysplasia or carcinoma in situ was studied. A total of 166 biopsy samples were taken from 75 stained and 91 non-stained portions. Of 75 methylene blue-stained areas, 21 were judged to be abnormal (MCC-positive) by microscopic observation. Fourteen of these 21 MCC-positive areas (67%) were proven to be abnormal histologically, while 7 of 54 MCC-negative portions (13%) were histologically abnormal. Only 4 of 91 biopsies (4%) from non-stained mucosa were proven to have urothelial atypia. In per patient figures, 1 or more concurrent field changes were detected in 15 of 65 cases (23%). MCC contributed to the diagnosis in 10 of these 15 patients.     

Apolipoprotein levels in preeclamptic pregnancies]

Lipoprotein is known to increase during pregnancy but the factors responsible for the change have not been established. In addition, the lipoprotein concentration in preeclamptic pregnancy is significantly higher than in normal pregnancy. The apolipoproteins are an important determinant of metabolism and the structure of plasma lipoproteins. In normal pregnancies, non pregnancies and preeclamptic pregnancies the levels of blood apolipoproteins AI, AII, B and E were determined by TIA methods. (1) In normal pregnancies, the concentrations of apolipoproteins AI, AII, B and E were 182.6 +/- 20.9 mg/dl (n = 12, mean +/- S.D.), 33.3 +/- 5.7 mg/dl, 128.6 +/- 20.8 mg/dl, and 6.8 +/- 1.9 mg/dl, respectively. (2) In the pregnancies, the concentrations of apolipoproteins AI, AII, B and E were 135.6 +/- 9.3 mg/dl (n = 5), 30.8 +/- 1.9 mg/dl, 76.0 +/- 19.7 mg/dl, and 4.4 +/- 0.7 mg/dl, respectively. (3) In the preeclamptic pregnancy, the concentrations of apolipoproteins AI, AII, B and E were 181.0 +/- 27.6 mg/dl (n = 22), 33.2 +/- 4.8 mg/dl, 145.7 +/- 41.6 mg/dl and 5.8 +/- 1.4 mg/dl, respectively. The concentration of apolipoprotein B in preeclamptic pregnancy was significantly higher (p less than 0.001) and apolipoprotein E was significantly lower (p less than 0.01) than in normal pregnancies. These data suggest that the measurement of apolipoprotein is useful for the evaluation of preeclamptic pregnancy.