Sequence-selective DNA binding to the regulatory subunit of cAMP-dependent protein kinase

The fluorescence of Trp-226 in the regulatory subunit of bovine type II cAMP-dependent protein kinase is unaffected by the binding of cAMP, but is quenched by the binding of 2'-dansyl-cAMP (DNS-cAMP). Up to 67% of the fluorescence of Trp-226 can be quenched by resonant energy transfer to the DNS-cAMP bound to the first site, and 96% of the fluorescence can be quenched by saturating both sites with DNS-cAMP. The observed efficiencies of energy transfer gave a distance of 16 A between Trp-226 and the DNS-cAMP bound at the first site and a distance of 12.7 A between Trp-226 and the DNS-cAMP bound at second site. The fluorescence of Trp-226 was suppressed by incubation of RII with the self-complementary octanucleotide TGACGTCA (CRE) due to binding of the oligonucleotide to RII. A detailed study of the binding equilibrium showed that each RII(cAMP)2 molecule binds 1 molecule of CRE with Kd = 80 nM. The corresponding Kd value for cAMP-depleted RII was found to be 25-fold higher. RII was also found to bind randomly selected DNA fragments with an average Kd value much higher than that of CRE. These observations show for the first time that the binding of oligonucleotide to RII is cAMP-enhanced and sequence-selective.

Clinical significance of serum type-III procollagen aminopropeptide in hepatitis B virus-related liver diseases

Serum type-III procollagen aminopropeptide (PIIIP) has been considered a marker of hepatic fibrogenesis. In an attempt to evaluate the clinical significance of serum PIIIP in patients with hepatitis B virus (HBV)-related liver diseases, the levels of the peptide were measured in 66 healthy adults and 200 patients with HBV-related liver diseases. As compared with the healthy adults (12.3 +/- 3.1 ng/ml), the serum PIIIP levels were significantly elevated in patients with acute hepatitis (17.4 +/- 6.6 ng/ml), chronic persistent hepatitis (18.3 +/- 4.9 ng/ml), and inactive liver cirrhosis (22.1 +/- 7.1 ng/ml). The PIIIP levels in patients with chronic active hepatitis (CAH) (33.9 +/- 23.1 ng/ml) were the highest among HBV-related liver diseases and had a tendency to increase with the severity of CAH. Of the liver-diseased patients with serum PIIIP levels greater than 30 ng/ml, 91% had a recent episode of severe hepatocellular damage, whereas 56% of patients with greatly elevated serum liver aminotransferase levels had no associated high increase in serum PIIIP levels. Thus, we suggest that fibrogenesis in HBV-related liver diseases is initiated by severe hepatocellular damage, but liver damage can also take place without prominent hepatic fibrogenesis. Serum PIIIP may be a serum marker to predict the active fibrogenesis of HBV-related liver diseases.

A potent fluorescent ATP-like inhibitor of cAMP-dependent protein kinase

The fluorescent ATP analogue 8-azido-2'-O-[14C]dansyl-ATP ([ 14C]AD-ATP) was used to probe the ATP-binding site in the catalytic (C) subunit of cAMP-dependent protein kinase. AD-ATP was found to inhibit the phosphotransferase activity of C subunit with extremely high specificity. Complete inhibition was observed when each mol of C subunit was covalently labeled with 1 mol of this fluorescent ATP analogue. The labeling can be accelerated by the presence of Mg2+ or Kemptide (Leu-Arg-Arg-Ala-Ser-Leu-Gly), whereas high concentrations of ATP can almost completely protect the enzyme from AD-ATP. Detailed studies indicated that AD-ATP competes with ATP for binding to C subunit. Analysis of the kinetic data gave dissociation constants of 2.9 and 13 microM for AD-ATP and ATP bound to C subunit, respectively. AD-ATP has a fluorescence emission peak at 510 nm in pH 7.0 aqueous buffer containing 25% glycerol. After covalent binding to C subunit this emission peak shifts to 455 nm, which suggests that the label at ATP site is in an endogenous hydrophobic environment. Upon the binding of Mg2+ or Kemptide, the fluorescence of AD-ATP-labeled C subunit can be enhanced by 50 and 45%, respectively. This enhancement suggests that the binding of either the peptide substrate or Mg2+ induces conformational change at the active site of C subunit. Analysis of the fluorescence data shows that the values of Kd for Mg2+ and Kemptide bound to AD-ATP-labeled C subunit are 0.2 mM and 2.1 microM, respectively. The normal procedure for the preparation of the C subunit from the bovine heart muscle has been simplified to require only one-fifth of the usual working time to obtain the homogeneous enzyme with 70% yield from the crude extract.

Serum C-reactive protein as a serum marker for the diagnosis of hepatocellular carcinoma

An abnormal serum C-reactive protein (CRP) level (greater than 10 mg/l) was found in 78% of 104 patients with hepatocellular carcinoma (HCC), 8% of 12 asymptomatic hepatitis B surface antigen carriers, 5% of 77 patients with chronic hepatitis, and 9% of 55 cirrhotic patients without complications. It was also discovered in 72% of 25 cirrhotic patients complicated with bacterial infections, gastrointestinal bleeding, hepatic encephalopathy, or massive ascites, 67% of nine common bile duct stone patients, and 79% of 14 patients with malignancies other than HCC. A dramatic decrease in serum CRP levels was found in two HCC patients receiving a successful surgical tumor resection, four cirrhotic patients recovering from complications, and all six patients with common bile duct stones and cholangitis controlled by antibiotics, but not in untreated HCC or other malignancy patients. Serum alpha-fetoprotein (AFP) levels correlated poorly with CRP levels. A combination of these two serum markers identified 94% of 104 patients with HCC. Since serum CRP levels were also abnormal in 57% of 14 patients with resectable HCC (less than or equal to 5 cm), in conjunction with AFP, it may be useful in the diagnosis of HCC or other malignancies.

The control of chronic infectious patients with pulmonary tuberculosis in a rural area of China

The aim of this study was to reduce the prevalence of chronic infectious cases (CIC) in a rural area of China by fully supervised chemotherapy of newly diagnosed smear-positive cases and by reducing the number of existing old CIC through fully supervised retreatment. From 1980 to 1985, 83.3% of 1828 new, smear-positive cases were given fully supervised chemotherapy. In 1980, 95.2% of 565 old CIC started fully supervised retreatment. The prevalence of CIC had dropped from 40.5/100,000 in 1980 to 6.7/100,000 by the end of 1986.

Effects of moxibustion on cellular immunocompetence of gamma-irradiated mice

The effects of moxibustion on cellular immunocompetence of gamma-irradiated mice were investigated in this study. A total of 240 male young mice (ICR strain), 6-8 weeks of age, were chosen and divided into three groups. Group A was the normal control. Group B, the experimental control, was treated with 400 rad whole body gamma-irradiation. Group C, the experimental group, was treated with moxibustion (MT) after being exposed to gamma-irradiation. Six to eight mice from each group were sacrificed on days 1, 5, 12, 19, 26 and 33 post-irradiation. The body and splenic weights of mice in each group were measured. The cellular immunocompetence was measured by 3H-thymidine uptake in each experimental mouse. The results revealed that 400 rad of gamma-ray irradiation inhibited the increase of body and splenic weights, and exerted a pronounced inhibitory effect on the incorporative rates of 3H-thymidine after being stimulated by mitogens such as PHA, PWM, Con A and LPS in the splenic lymphoid cells. MT seemed to help the recovery of the cellular immunocompetence in the gamma-ray irradiated mice.

HBsAg carrier infants with serum anti-HBc negativity

A total of 128 HBsAg carrier infants born to HBeAg-positive HBsAg carrier mothers were tested for serum HBsAg, HBeAg, hepatitis B virus DNA and anti-HBc. Ninety-three of them had received hepatitis B vaccination. Anti-HBc had been found to be negative in sera of 12 infants who were HBsAg, HBeAg and hepatitis B virus DNA positive during the follow-up period of 3 to 5 years. Liver damage, as measured by serum ALT levels, was found to be normal among the 12 HBsAg carrier infants with serum anti-HBc negativity, whereas 39.7% of the 116 anti-HBc-positive HBsAg carrier infants had abnormal ALT levels during the follow-up period. Anti-HBe and anti-HBs also were not detected in sera of these anti-HBc-negative HBsAg carrier infants. Thus, HBsAg carrier infants with anti-HBc negativity probably result from immune incompetency of the hepatitis B virus antigens.

Application of des-gamma-carboxy prothrombin as a complementary tumor marker with alpha-fetoprotein in the diagnosis of hepatocellular carcinoma

By means of staphylocoagulase, plasma des-gamma-carboxy prothrombin (DCP) was measured in 255 subjects. Of these, 59 were healthy controls, 100 had primary hepatocellular carcinoma (PHC), 33 had cirrhosis of the liver, 16 had hepatitis, 11 had metastatic carcinoma of the liver (MCL), and 36 subjects had previously been treated with anti-vitamin K drugs. The mean plasma DCP level in the healthy subjects was 3.02 VGH U/l. Of PHC patients 80% had DCP levels greater than 6 VGH U/l, which we regarded as probably abnormal. None of the patients with benign liver diseases (cirrhosis of liver or hepatitis) had DCP greater than 10 VGH U/l. Of the patients with MCL 54.54% had DCP greater than 6 VGH U/l. In our study DCP was found to be as sensitive a tumor marker as alpha-fetoprotein (AFP) in the diagnosis of PHC and was better in distinguishing PHC from benign liver disease. Of PHC patients 92% had at least one of the two tumor markers. Simultaneous determination of DCP and AFP should be applied in mass survey programs for detecting PHC, especially in countries with a high prevalence of hepatitis B virus infection.

Phase II study of mitoxantrone in unresectable primary hepatocellular carcinoma following hepatitis B infection

A total of 20 patients with histologically proven primary hepatocellular carcinoma (PHC) received mitoxantrone IV at a dose of 10-16 mg/m2 every 3 weeks. All patients had previous hepatitis B infection. None underwent remission after treatment; 2 had stable disease and 18 progressive disease. The median overall survival was 13 weeks (range, 1-59 weeks). There was no evidence of significant antitumor activity for mitoxantrone in our patients with PHC. Hematotoxicity occurred in 100% of the patients with grades 2-4 leukopenia, 89% of those with grades 1-4 anemia, and 26% of those with grades 2-3 thrombocytopenia. Cardiotoxicity occurred in 20% of the patients after 14-30 mg/m2 mitoxantrone; these included complete heart block with fatal outcome in one case, decreased ventricular ejection fraction in one, and sinus tachycardia in two. Nausea, vomiting, fever, diarrhea, and alopecia were mild and occurred in 15%-45% of the patients Therefore, patients with PHC following hepatitis B infection may be less tolerant to mitoxantrone, resulting in the apparent increase in toxicities.

Kinetics and inhibition of reverse transcriptase from human and simian immunodeficiency viruses

Reverse transcriptase from the simian immunodeficiency virus (SIV) was found to have kinetic behavior similar to that of enzyme from the human immunodeficiency virus (HIV). Michaelis constants for the substrates TTP and dGTP and inhibition constants for the inhibitors 3'-azido-3'-deoxythymidine 5'-triphosphate, 2',3'-dideoxythymidine 5'-triphosphate, and 2'-3'-dideoxyguanosine 5'-triphosphate were obtained for SIV reverse transcriptase and were found to be similar to the corresponding values for HIV reverse transcriptase. Thus, the interaction of SIV reverse transcriptase with nucleotide analogs appears to be indistinguishable from that of the HIV enzyme, suggesting that SIV/simian acquired immunodeficiency syndrome (SAIDS) is a potentially good model of AIDS.

Radioimmunoassay of serum IGF-I and IGF-II in patients with chronic liver diseases and hepatocellular carcinoma with or without hypoglycemia

Insulin-like growth factor (IGF) I and IGF-II were measured by radioimmunoassay in the sera of seven patients with acromegaly, 36 normal control subjects, 15 patients with chronic hepatitis, 15 patients with cirrhosis, 25 patients with hepatocellular carcinomas (HCCs) who did not have hypoglycemia, 20 patients with HCCs who did have hypoglycemia, and 10 patients with metastatic liver tumors. Both IGF-I and IGF-II levels decreased as liver disease progressed from the normal control stage to chronic hepatitis and cirrhosis, and both levels reflected the severity of liver disease. Patients with HCCs who had hypoglycemia had relatively higher IGF-II levels in their sera in comparison with those who did not have hypoglycemia (272 +/- 167.5 ng/ml vs 110.4 +/- 85.9 ng/ml [mean +/- SD], p less than 0.0005), despite the fact that those with hypoglycemia had more advanced liver cancer and had lower IGF-I levels in sera (16.7 +/- 14.1 ng/ml vs 46.8 +/- 47.9 ng/ml, p less than 0.002). It is possible that a labile IGF-II material is produced by the cancer cells of patients with hypoglycemia. This factor is reactive to the IGF-II receptor and partially cross-reacts with an antibody to IGF-II; it accounted for the mildly elevated levels of serum IGF-II. Hypoglycemia may be an integral effect of relatively elevated IGF-II like material and an advanced liver cancer. Also, higher serum alpha-fetoprotein (AFP) levels were more frequently found in patients with hypoglycemia who had relatively elevated IGF-II levels and short survivals.

Role of caesarean section in prevention of mother-infant transmission of hepatitis B virus

447 infants, born to mothers positive for hepatitis B e antigen and hepatitis B surface antigen (HBsAg), received hepatitis B immunisation. A higher rate of hepatitis B virus (HBV) infection was found at birth in infants delivered vaginally (96/385, 24.9%) than in infants delivered by caesarean section (6/62, less than 10%). At birth, serum HBV-DNA was detected in 13 of 67 infants delivered vaginally, but in none of 30 infants delivered by caesarean section. Caesarean section combined with hepatitis B immunisation is advisable in infants of mothers who are chronic HBsAg carriers with high serum HBV-DNA levels.

Natural and activated cytotoxic lymphocytes reactivity to human hepatocellular carcinoma cell lines in hepatocellular carcinoma patients

The status of cellular cytotoxic activity in Hepatocellular Carcinoma (HCC) patients was compared to that in normal individuals by testing the cytotoxicity against K562 and five established HCC cell line targets. Natural killer (NK) activity of fresh peripheral blood mononuclear (PBM) cells in HCC patients to K562 cell line target was lower than that in normal donors. NK activity of unstimulated PBM cells from either source was minute against all five HCC cell line targets. Three different activation systems were employed to examine the cellular cytotoxicity of activated PBM cells: (1) conventional mixed lymphocyte culture (MLC), (2) allogeneic mixed lymphocyte tumor culture (MLTC), and (3) lymphokine-activated killer (LAK) cell culture. The cytotoxic effects of PBM cells in all three activation conditions were significantly lower in HCC patients than in normal donors (P less than 0.05 to P less than 0.01). These results suggest that, in addition to naturally present NK cells, the degree of in vitro activation of PBM cells may also have decreased in HCC patients.

Comparison of enzyme- and radio-immunoassay kits to detect hepatitis B surface antibody response among hepatitis B vaccinees

A total of 288 of sera was obtained from 96 hepatitis B vaccinees to test antibody to hepatitis B surface antigen (anti-HBs) by enzyme immunoassay (EIA) and radioimmunoassay (RIA), respectively. An anti-HBs titer greater than 10 mIU/mL is required for immunity; 172 (59.7%) were positive by EIA and 173 (60.1%) were positive by RIA. A correlation study of anti-HBs titers tested by these two methods showed a correlation coefficient r = 0.889 (n = 162, p less than 0.001). Of 173 serum specimens whose anti-HBs were positive by RIA, 10 were negative by EIA; those 10 had had anti-HBs titers between 11 to 20 mIU/mL by RIA. Among 172 serum specimens whose anti-HBs were positive by EIA, 9 were negative by RIA; 3 of those were between 21 to 70 mIU/mL, and 6 were between 11 to 20 mIU/mL by EIA. Of the 96 vaccinees, following first dose of hepatitis B vaccination their anti-HBs response rates were found to be 20.8% by EIA and 17.7% by RIA. Following second and third vaccinations, their anti-HBs response rates were 65.6% and 92.7% by EIA, and 71.9% and 90.6% by RIA, respectively. Thus, EIA correlates well with RIA for anti-HBs testing especially when its titers are greater than 70 mIU/ml.

5-Fluorocytosine in DNA is a mechanism-based inhibitor of HhaI methylase

5-Fluorodeoxycytidine (FdCyd) was incorporated into a synthetic DNA polymer containing the GCGC recognition sequence of HhaI methylase to give a polymer with about 80% FdCyd. In the absence of AdoMet, poly(FdC-dG) bound competitively with respect to poly(dG-dC) (Ki = 3 nM). In the presence of AdoMet, the analogue caused a time-dependent, first-order (k = 0.05 min-1) inactivation of the enzyme. There is an ordered mechanism of binding in which enzyme first binds to poly(FdC-dG), then binds to AdoMet, and subsequently forms stable, inactive complexes. The complexes did not dissociate over the course of 3 days and were stable to heat (95 degrees C) in the presence of 1% SDS. Gel filtration of a complex formed with HhaI methylase, poly(FdC-dG), and [methyl-3H] AdoMet gave a peak of radioactivity eluting near the void volume. Digestion of the DNA in the complex resulted in a reduction of the molecular weight to the size of the methylase, and the radioactivity in this peak was shown to be associated with protein. These data indicate that the complexes contain covalently bound HhaI methylase, poly(FdC-dG), and methyl groups and that 5-fluorodeoxycytidine is a mechanism-based inactivator of the methylase. By analogy with other pyrimidine-modifying enzymes and recent studies on the mechanism of HhaI methylase (Wu & Santi, 1987), these results suggest that an enzyme nucleophile attacks FdCyd residues at C-6, activating the 5-position for one-carbon transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

17 Beta-estradiol and progesterone inhibit transcription of the genes encoding the subunits of ovine follicle-stimulating hormone

FSH, the primary trophic hormone for gamete development in mammals, is composed of two protein subunits, alpha and beta. It is known that 17 beta-estradiol (E2) and progesterone (P4) can decrease the secretion and synthesis of FSH in ovine pituitary cultures. Data presented here indicate that E2 and P4 decrease the steady state levels of FSH beta mRNA concomitantly with FSH secretion in ovine pituitary cultures. By 24 h, E2 decreased the steady state levels of FSH beta mRNA and FSH secretion by 68% +/- 5%. P4 also decreased both concomitantly, but by 58% +/- 7% after 24 h. E2 and P4 also decrease steady state levels of alpha mRNA, but at a lower rate. Finally, it is shown that E2 and P4 decrease transcription of the FSH beta by greater than 85% in 2 h; alpha mRNA transcription is decreased by 70% in 12 h. These effects are not altered even when cycloheximide is present to block protein synthesis by 95%. These data further define the mechanisms whereby E2 and P4 inhibit ovine FSH secretion/synthesis directly at the pituitary level. They also provide the first example of negative transcriptional regulation by P4 and the second of two examples now established for E2.

Symptomatic anti-HBe positive chronic hepatitis B in Taiwan with special reference to persistent HBV replication and HDV superinfection

Ninety-four patients, who were admitted with symptoms of liver disease and found to be positive for hepatitis B surface antigen and antibody to hepatitis B e antigen (anti-HBe), were examined for hepatitis B virus (HBV) DNA in serum and immunoglobulin antibody to hepatitis B core antigen and liver biopsies were stained for hepatic hepatitis B core antigen. Of 94 patients, 34 (36%) had evidence of HBV replication and 35 (37%) evidence of hepatitis D virus (HDV) superinfection. Most of the latter two groups of patients (greater than 70%) had evidence of chronic active hepatitis or active cirrhosis in their liver biopsies. The majority of these patients (greater than 80%) also had high levels of serum alanine aminotransferase (greater than 200 U/L) during the acute stage of their illness, and suffered from prolonged hepatic inflammation (greater than 1 year). Many of the patients (59%) also experienced frequent (1-6 episodes) relapsing exacerbations during a two-year follow-up period. Thus, persistent replication or reactivation of HBV and HDV superinfection were the two major causes of clinical exacerbations in anti-HBe-positive chronic HBV carriers in Taiwan, and also played an important role in the progression of their liver diseases and unfavorable outcomes.

Mass screening of primary hepatocellular carcinoma by alpha-fetoprotein in a rural area of Taiwan--a dried blood spot method

A prospective survey of primary hepatocellular carcinoma (PHC) was conducted in a rural area of Taiwan using a two-site enzyme immunoassay for alpha-fetoprotein (AFP) in dried blood samples collected on filter paper. Of 1894 men over 40 years of age who were tested, 20 (1%) had AFP levels of greater than 20 ng/ml of blood on screening. Nineteen of these men received ultrasound examinations, and small PHCs were detected in 4 (21%). The remaining 15 cases had other types of hepatobiliary tract diseases, and 6 (40%) were also serum HBsAg positive. They should all be closely followed up by AFP determination and ultrasound examination of the liver. In contrast to the low resection rate of PHC in symptomatic patients who were admitted through the outpatient clinic during the period of this survey, the four cases with small PHC discovered by AFP screening had their tumors successfully removed (5/57 vs. 4/4, p less than 0.005). Our preliminary results showed that this method is a simple, sensitive and convenient assay for AFP and may be used as a first-line screening test in mass population surveillance programs for PHC, particularly in areas where PHC is highly prevalent.

High level expression and purification of HhaI methyltransferase

A cloning system for the DNA-(cytosine-5)-methyltransferase MHhaI and high level expression of the enzyme are described. A parent plasmid was constructed from fragments of the MHhaI gene and synthetic oligonucleotides. The construct permits introduction of various restriction sites for cloning at precise positions near the initiation codon, and beyond the termination codon. The entire MHhaI coding sequence was introduced as a 1042 b.p. NdeI-XbaI fragment into the vector pAR3040 which contains the T7 RNA polymerase promoter. The resultant plasmid pTNX3 (MHhaI-pAR3040) was introduced into McrB- E. coli strains HB101 and GM2929, and expression of MHhaI was induced by infection with the lambda phage CE6 carrying the T7 RNA polymerase gene. In induced cells, catalytically active MHhaI was produced at a level that corresponds to about 8% of the total soluble protein; an insoluble form of the protein was also formed, but could be readily removed. The expressed soluble enzyme from HB101/pTNX3 was purified to apparent homogeneity in about 50% yield by a two-step chromatographic procedure involving DEAE-cellulose and Heparin-Sepharose; a one liter culture gave about 2.5 mg of pure enzyme. The molecular weight and kinetic properties of the expressed protein are identical to those reported for the authentic MHhaI, and its amino terminal sequence agrees with that predicted from the DNA sequence.

Effects of amoxapine and imipramine on evoked potentials in the Continuous Performance Test in patients with affective disorder

Twenty patients with major depressive disorder were studied with evoked potential (EP) topographic mapping after receiving placebo, imipramine, or amoxapine for 2 days in a random-assignment, double-blind design. Patients performed the Continuous Performance Test (CPT), a visual vigilance test. The stimuli were the digits 0-9, with 0 a target to be responded to with a button press. EPs were recorded from 32 channels and were averaged separately for detected and undetected targets and for false positives and correctly identified nontargets (no button press). Twenty-one normal controls were also tested. Amoxapine enhanced N120 amplitude in midline parietal and right parietal cortex where selective attention effects have been found to be greatest in studies of normal controls. Both amoxapine and imipramine enhanced differences in P200 between target and nontarget stimuli in comparison to placebo, with amoxapine differences again being greatest over midline parietal locations. CPT performance was significantly better on amoxapine than placebo.

Hepatitis B vaccination in healthy Chinese adults with low dose regimens

Three hundred seronegative healthy Chinese adults were divided randomly into three groups to receive 5, 2 and 1 micrograms of Pasteur's hepatitis B vaccine on a four dose schedule. No difference between the three groups was observed in the antibody to hepatitis B surface antigen (anti-HBs) response rate (96, 92 and 94%, respectively) a month following the fourth dose of vaccination. Young vaccinees had a faster and higher anti-HBs response than older ones. There was no difference in antibody response rate by sex. This study shows a good immunogenic effect for low dose hepatitis B vaccine in Chinese adults. The use of low dose (1 microgram) hepatitis B vaccine in susceptible adults would make mass hepatitis B vaccination more economically feasible.

Catalytic hydrolysis and synthesis of adenosine 5'-triphosphate by stereoisomers of covalently labeled F1-adenosinetriphosphatase and reconstituted submitochondrial particles

Bovine heart F1-adenosinetriphosphatase (F1) was labeled specifically and precisely with 7-chloro-4-nitro-2,1,3-[14C]benzoxadiazole ([14C]NBD-Cl). The stereospecifically labeled F1 (O-beta'-[14C]-NBD-F1) was partially reactivated by LiCl treatment, which could cause rearrangement of the beta subunits to form O-beta', beta''-[14C]NBD-F1. Both labeled enzymes were used to combine with F1-deficient submitochondrial particles (ASU) to form the reconstituted particles O-beta'-NBD-F1-ASU and O-beta', beta''-NBD-F1-ASU, respectively. A comparison of the observed steady-state rates of catalytic ATP hydrolysis and oxidative phosphorylation by these specifically labeled submitochondrial particles (SMP) with those of the unlabeled control samples suggests that oxidative phosphorylation involves more active sites of F1 than catalytic ATP hydrolysis. A comparison of the observed ATPase activity of uncoupled labeled SMP and the activity for ATP-driven reverse electron transport in coupled labeled SMP with the corresponding values of the unlabeled control samples shows that the observed fractional inhibition ATP hydrolysis is the same for both the coupled SMP and uncoupled SMP and is determined only by the state of stereospecific labeling of F1. The effect of preincubation under simulated oxidative phosphorylation conditions on the ATPase activity of the unperturbed, specifically NBD-labeled submitochondrial particles was also examined. The data show that respiration-generated proton flux does not cause the beta subunits in bovine heart proton-ATPase to continue switching places with each other during oxidative phosphorylation. Samples of NBD-F1 with specific labels on its nonhydrolytic beta'' subunits but none on its hydrolytic beta' subunit were prepared by a three-cycle process.(ABSTRACT TRUNCATED AT 250 WORDS)

P1-(5'-adenosyl)-P2-N-(2-mercaptoethyl)diphosphoramidate. An affinity reagent for demonstrating the presence of Tyr-beta 311 at the hydrolytic site of F1-ATPase

The compound P1-(5'-adenosyl)-P2-N-(2-mercaptoethyl)diphosphoramidate (AMEDA) was synthesized as an ATP analogue for in situ reaction with the 4-nitro-2,1,3-[14C]benzoxadiazolyl group (NBD) in the labeled F1-ATPase (F1). AMEDA was found to reactivate O-[14C]NBD-F1 via a dual-path mechanism. The principal path involves the binding of AMEDA at a site in F1 with Kd = 14.5 microM and subsequent reaction with the [14C]NBD label. The second slower path involves the direct biomolecular reaction of AMEDA with the radioactive label on F1. The rate of reactivation of O-[14C]NBD-F1 by AMEDA was decreased by ADP or ATP which competes with the ATP analogue for binding to the labeled enzyme. The reaction product was found to contain one adenine group, two phosphate groups, and one [14C]NBD label per molecule as expected from the structure of the compound AMEDA-[14C]NBD. Purified AMEDA-[14C]NBD was found to bind to unlabeled F1 with Kd = 2 microM. These observations demonstrate the in situ reaction of bound AMEDA with the nearby [14C]NBD label attached to Tyr-beta 311 and support the assumed presence of Tyr-beta 311 near the phosphate groups of ATP bound at the hydrolytic site of F1-ATPase. The possible locations of Tyr-beta 364, His-beta 427, and Tyr-beta 345 relative to Tyr-beta 311 in F1 are discussed, and the validity of the previously proposed model for F1-ATPase with one hydrolytic site assisted by two auxiliary sites is examined and compared with that of the widely accepted alternating sites model.

Kinetic and catalytic mechanism of HhaI methyltransferase

Kinetic and catalytic properties of the DNA (cytosine-5)-methyltransferase HhaI are described. With poly(dG-dC) as substrate, the reaction proceeds by an equilibrium (or processive) ordered Bi-Bi mechanism in which DNA binds to the enzyme first, followed by S-adenosylmethionine (AdoMet). After methyl transfer, S-adenosylhomocysteine (AdoHcy) dissociates followed by methylated DNA. AdoHcy is a potent competitive inhibitor with respect to AdoMet (Ki = 2.0 microM) and its generation during reactions results in non-linear kinetics. AdoMet and AdoHcy significantly interact with only the substrate enzyme-DNA complex; they do not bind to free enzyme and bind poorly to the methylated enzyme-DNA complex. In the absence of AdoMet, HhaI methylase catalyzes exchange of the 5-H of substrate cytosines for protons of water at about 7-fold the rate of methylation. The 5-H exchange reaction is inhibited by AdoMet or AdoHcy. In the enzyme-DNA-AdoHcy complex, AdoHcy also suppresses dissociation of DNA and reassociation of the enzyme with other substrate sequences. Our studies reveal that the catalytic mechanism of DNA (cytosine-5)-methyltransferases involves attack of the C6 of substrate cytosines by an enzyme nucleophile and formation of a transient covalent adduct. Based on precedents of other enzymes which catalyze similar reactions and the susceptibility of HhaI to inactivation by N-ethylmaleimide, we propose that the sulfhydryl group of a cysteine residue is the nucleophilic catalyst. Furthermore, we propose that Cys-81 is the active-site catalyst in HhaI. This residue is found in a Pro-Cys doublet which is conserved in all DNA (cytosine-5)-methyltransferases whose sequences have been determined to date and is found in related enzymes. Finally, we discuss the possibility that covalent adducts between C6 of pyrimidines and nucleophiles of proteins may be important general components of protein-nucleic acid interactions.

Positron emission tomography studies of basal ganglia and somatosensory cortex neuroleptic drug effects: differences between normal controls and schizophrenic patients

Glucose metabolic rate in the basal ganglia, thalamus, and somatosensory cortex was examined in eight patients with schizophrenia before and after receiving neuroleptic medication. Basal ganglia metabolic rates were increased with medication: more on the right than on the left and more in putamen than caudate. The cortical anteroposterior ratio, an index of relative hypofrontality, was not affected by neuroleptics. The brain areas that were found to be altered by neuroleptics were selected for comparison between off-medication schizophrenics and controls. Metabolic rates in the basal ganglia tended to be low in patients with schizophrenia in comparison to 24 age- and sex-matched controls.

Correlation between hepatic hepatitis B core antigen and serum hepatitis B virus-DNA levels in patients with chronic hepatitis B virus infections in Taiwan

Paired liver biopsy specimens and serum samples from 76 patients with chronic hepatitis B virus (HBV) infection were taken for staining of hepatitis B core antigen (HBcAg) by immunoperoxidase and testing of HBV-DNA by a spot hybridization technique, respectively. Thirty-two tissue specimens showed positive staining for HBcAg in their hepatocytes. The two patients with diffuse HBcAg expression in liver tissue also had high serum concentrations of HBV-DNA (greater than 10 pg/10 microL). Among 30 patients with focal HBcAg distribution, 28 patients (93.3%) had measurable levels of serum HBV-DNA and 17 patients (60.7%) had high levels of serum HBV-DNA. Of 44 patients without hepatic HBcAg expression, only 12 patients (27.3%) had detectable serum HBV-DNA, and most patients (93.1% [11/12]) had low concentrations (less than 10 pg/10 microL). Nineteen patients had superimposed hepatitis D virus infection, and, of these, three patients (15.8%) had detectable serum HBV-DNA in low concentrations, while one of the three patients had stainable HBcAg in his hepatocytes with focal distribution. Two of the three patients with hepatitis A virus superinfection who had focal HBcAg expression in their liver tissue had serum HBV-DNA levels that were high during the acute phase of hepatitis A virus infection, and in one patient his serum HBV-DNA levels further increased from 10 pg/10 microL to 40 pg/10 microL during the recovery phase. Thus, measurement of serum HBV-DNA levels in patients with chronic HBV infection correlated well with their hepatic HBcAg expression, and both represent the precise status of HBV replication.

Hepatitis D virus (delta agent) superinfection in an endemic area of hepatitis B infection: immunopathologic and serologic findings

In 86 Chinese patients with histologically proven hepatitis B surface antigen (HBsAg) positive chronic hepatitis and serum alanine aminotransferase levels exceeding 200 U/l, antibody to hepatitis D antigen (HDAg) was detected more frequently in sera from hepatitis B e antigen (HBeAg) negative patients (11/35, 31.4%) than in HBeAg positive (4/51, 7.8%) patients (p less than 0.02). 10 liver biopsy specimens (76.9%) from 13 chronic hepatitis B patients with superimposed hepatitis D virus (HDV) infection, showed positive staining for HDAg in their hepatocytes. Neither HBsAg nor hepatitis B core antigen (HBcAg) was found in the liver in 12/13 patients with superimposed HDV infection. However, in liver biopsy specimens from 42 patients without HDV superinfection, HBsAg was stained positively in 41 patients (97.6%), and HBcAg in 24 patients (47.1%). Using dot blot hybridization technique, serum hepatitis B virus (HBV) DNA was detected in 62.1% (41/66) of patients without HDV superinfection, while it was detected only in 10.0% (1/10) of patients who had HDV superinfection. It is concluded that HDV superinfection plays a significant role in Taiwan in HBeAg negative chronic hepatitis B patients with clinical "exacerbation". The data show clear evidence of HDV interfering with the replication of HBV.

Geometric isomers of covalently labeled mitochondrial F1-adenosinetriphosphatase with different properties

Two geometric isomers of covalently labeled F1-adenosinetriphosphatase (F1-ATPase) have been prepared by reaction with 7-chloro-4-nitro-2,1,3-benzoxadiazole (NBD-Cl): a directly labeled product denoted by O-beta'-NBD-F1 and an indirectly prepared product denoted by 0-beta'-NBD-F1. The normal isomer O-beta'-NBD-F1 is highly inhibited, and its label can be removed by 20 microM N-acetyl-L-cysteine (AC) at the expected rate with dr/dn approximately equal to -1, where n is the molar ratio of the label to F1 and r is the ratio of the ATPase activity of the labeled enzyme to that of the unlabeled control enzyme. But O-beta"-NBD-F1 is almost fully active, and its label can be removed by 20 microM AC at much slower rates with dr/dn approximately equal to 0. Cleavage of either isomer with pepsin and subsequent amino acid analysis of the isolated radioactive polypeptides show that the label is attached to Tyr-beta 311 in both isomers. At pH 9 the label in O-beta'-NBD-F1 spontaneously transfers from Tyr-beta 311 to the presumably nearby Lys-beta 162 in the dark with a half-time of 1/2 h, but the label in O-beta"-NBD-F1 does not transfer under the same conditions. The existence of geometric isomers of O-NBD-F1 with contrastingly different properties invalidates models for F1 with three equivalent beta subunits but is consistent with the model based on one principal catalytic beta' subunit and two auxiliary beta" subunits. A possible mechanism for promoting the catalytic efficiency of beta' through protein conformation change induced by ATP and/or ADP is suggested.

Location of lysine-beta 162 in mitochondrial F1-adenosinetriphosphatase

The quenching of the fluorescence of bovine heart F1-adenosinetriphosphatase labeled specifically at its essential Lys-beta 162 with 7-chloro-4-nitro-2,1,3-benzoxadiazole (N-NBD-F1) by 2',3'-O-(2,4,6-trinitrocyclohexadienylidene)adenosine 5'-triphosphate (TNP-ATP) has been studied. Analysis of the fluorescence data in the presence of 1 mM ATP shows that the dissociation constant of TNP-ATP from its first binding site in the covalently labeled enzyme is 250-fold lower than that of ATP, which it replaces in pH 7.0 buffer containing 25% glycerol, and that this binding causes a 54% quenching of the fluorescence of the N-NBD label due to energy transfer to the weakly fluorescent TNP-ATP molecule. Computation based on the observed quenching gives a distance of 25.6 +/- 0.4 A between the NBD label and the chromophore of the bound TNP-ATP molecule. Since the distance between the chromophore and the farthest O atom of the bound TNP-ATP is about 16 A, it seems quite likely that the epsilon-amino group of Lys-beta 162 is near the gamma-phosphate group of the TNP-ATP bound at the catalytic site. Similar measurements in the presence of 1 mM ADP show that the replacement of ADP at the catalytic site by TNP-ATP causes a 49% quenching of the fluorescence of the N-NBD label, which gives a distance of 26.5 +/- 0.4 A between the label and the chromophore of the bound TNP-ATP molecule.

Two-site enzyme immunoassay for alpha-fetoprotein in dried-blood samples collected on filter paper

This is a method for measuring alpha-fetoprotein (AFP) in eluates of dried-blood samples on filter paper by use of a simple, sensitive two-site enzyme immunoassay. The spot, 6 mm in diameter (equivalent to about 12 microL of whole blood), is incubated overnight with alkaline phosphatase conjugated to rabbit anti-AFP antibody in a tube containing a polystyrene bead coated with mouse monoclonal antibody to AFP. After the beads are washed the enzyme activities associated with them are determined colorimetrically, with p-nitrophenyl phosphate as substrate. The measurable range of AFP is from 9 to 900 micrograms per liter of plasma. AFP in the dried-blood spot as determined by this method correlated well with the AFP value for serum from the same blood sample as determined by radioimmunoassay (r = 0.957, p less than 0.001). Preliminary studies in which we used this method with 242 healthy blood donors and 60 patients with hepatocellular carcinoma indicate that it may be suitable for use in mass screening for hepatocellular carcinoma in high-risk populations.

Hepatitis B and D virus infection among drug abusers in Taiwan

Approximately 15 to 20% of the general population in Taiwan are chronic hepatitis B surface antigen (HBsAg) carriers. However, the incidence of hepatitis D virus (HDV) infection is low (5-8%) in patients with HBsAg-positive chronic liver diseases in this area. To evaluate the prevalence of hepatitis B virus (HBV) and HDV infection among drug abusers in Taiwan, serum samples were collected from 152 drug abusers at the Taipei Municipal Anti-Narcotic Institute and test for HBV and HDV markers. Of these, 24 (15.8%) were HBsAg positive, and only 15 (9.9%) were seronegative for all HBV markers. Of the 115 intravenous drug abusers, serum antibody to hepatitis D antigen (anti-HD) was positive in 78.9% of 19 persons who were HBsAg positive, and in 7.5% of 80 persons who were positive for antibody to HBsAg (anti-HBs). Anti-HD was not detected in the sera from all 37 nonintravenous drug abusers regardless of the status of their HBV markers. Also, none of 63 asymptomatic HBsAg carrier pregnant women or 23 patients with acute type B viral hepatitis had measurable anti-HD in their sera. Thus, the high frequency of HDV detected among Chinese HBsAg carrier intravenous drug abusers in Taiwan is similar to that reported in Western countries.

Two-site enzyme immunoassay for alpha-fetoprotein in dried-blood samples collected on filter paper

This is a method for measuring alpha-fetoprotein (AFP) in eluates of dried-blood samples on filter paper by use of a simple, sensitive two-site enzyme immunoassay. The spot, 6 mm in diameter (equivalent to about 12 microL of whole blood), is incubated overnight with alkaline phosphatase conjugated to rabbit anti-AFP antibody in a tube containing a polystyrene bead coated with mouse monoclonal antibody to AFP. After the beads are washed the enzyme activities associated with them are determined colorimetrically, with p-nitrophenyl phosphate as substrate. The measurable range of AFP is from 9 to 900 micrograms per liter of plasma. AFP in the dried-blood spot as determined by this method correlated well with the AFP value for serum from the same blood sample as determined by radioimmunoassay (r = 0.957, p less than 0.001). Preliminary studies in which we used this method with 242 healthy blood donors and 60 patients with hepatocellular carcinoma indicate that it may be suitable for use in mass screening for hepatocellular carcinoma in high-risk populations.

DNA degradation by bleomycin: evidence for 2'R-proton abstraction and for C-O bond cleavage accompanying base propenal formation

Reaction of poly(dA-[2'S-3H]dU) with activated bleomycin yields [3H]uracil propenal that completely retains the tritium label. In contrast, we have previously shown that reaction of poly(dA-[2'R-3H]dU) with activated bleomycin affords unlabeled uracil propenal [Wu, J. C., Kozarich, J. W., & Stubbe, J. (1983) J. Biol. Chem. 258, 4694-4697]. We have also prepared both cis- and trans-thymine propenals by chemical synthesis and have observed that the trans isomer is the exclusive product of the bleomycin reaction. Moreover, the cis isomer was found to be stable to the conditions of bleomycin-induced DNA degradation. Taken together, these results establish that the formation of trans-uracil propenal occurs via an anti-elimination mechanism with the stereospecific abstraction of the 2'R proton. The question of phosphodiester bond cleavage during base propenal formation has also been addressed by the analysis of the fate of oxygen-18 in poly(dA-[3'-18O]dT) upon reaction with activated bleomycin. The 5'-monophosphate oligonucleotide ends produced from thymine propenal formation have been converted to inorganic phosphate by the action of alkaline phosphatase, and the phosphate has been analyzed for 18O content by 31P NMR spectroscopy. The oxygen-18 is retained in the inorganic phosphate, establishing that the formation of thymine propenal by activated bleomycin proceeds with C-O bond cleavage at the 3'-position.

Effects of H2-receptor antagonists on the rat liver after partial hepatectomy or carbon tetrachloride-induced hepatic injury

A total of 512 male rats were used to investigate the effects of H2-receptor antagonists on the liver after two-thirds hepatectomy or after carbon tetrachloride (CCl4)-induced hepatic injury. The serum aminotransferase levels in hepatectomy rats were significantly elevated as compared with those of rats with the sham operation 1 and 2 days after the operation. However, there were no differences in the serum aminotransferase levels and liver regeneration rates among the groups of hepatectomy rats who were treated with saline, cimetidine, or ranitidine. The injections of cimetidine or ranitidine did not induce a significant increase in serum amino-transferase levels or increase the severity of liver cell necrosis in CCl4-treated rats, as compared with the CCl4-treated rats who received saline injection. Thus, our data indicate that H2-receptor antagonists do not inhibit liver regeneration in rats after two-thirds hepatectomy or exert a detrimental effect on the liver cell necrosis in rats after CCl4-induced hepatic injury.

Prevention of maternal-infant hepatitis B virus transmission by immunization: the role of serum hepatitis B virus DNA

Sera from 108 HBsAg carrier mothers at delivery and their respective offspring at birth and at 6 months of age were examined for hepatitis B virus DNA by the dot-blot hybridization technique. Hepatitis B virus DNA was detected in 83% of 88 carrier mothers who were HBeAg positive, and in 10% of 20 carrier mothers who were HBeAg negative. All five infants born to HBeAg-positive carrier mothers with hepatitis B virus DNA levels over 80 pg per 10 microliters of serum were infected by hepatitis B virus, in spite of receiving hepatitis B immunization. All 17 infants without hepatitis B immunization who were born to HBeAg and hepatitis B virus DNA-positive carrier mothers developed hepatitis B virus infection. Of 56 infants born to HBeAg and hepatitis B virus DNA-positive carrier mothers and who had received hepatitis B immunization, a higher hepatitis B virus infection rate was found in a group of infants whose sera hepatitis B virus DNA were positive (15/16, 93.8%) than in infants whose sera were negative (17/40, 42.5%) at birth (p less than 0.0005). These data suggest that the assay for hepatitis B virus DNA in sera of HBsAg carrier mothers at delivery or their infants at birth will predict the efficacy of hepatitis B immunization for prevention of maternal-infant hepatitis B virus transmission.

Dynamic aspects of whole-body nitrogen metabolism in uremic patients on dietary therapy

15N-glycine administered orally to 3 patients with chronic renal failure and 15N-ammonium chloride given by intravenous infusion to 5 patients were used as tracers in studying the total body nitrogen metabolism during the course of dietary therapy. Patients on a diet providing 1.2 g protein per kilogram body weight per day had significantly lowered total nitrogen flux (Q) and rates of total body protein synthesis (S) and catabolism (C) as compared with the normal controls. A reduction in daily protein intake to 0.6 g/kg/day resulted in marked increases in all these parameters, so that the values actually approached that of the normal controls. While in the normal subjects low-protein intake did not affect the total body protein turnover significantly, it tended to decrease Q and to raise S, C, and S/Q. The results of the present study suggest that the adaptive response to restriction in protein intake is a more efficient utilization of nitrogen entering the metabolic pool for anabolic purposes, and less nitrogen excreted as urea. This response becomes manifest and essential to patients with chronic renal failure and forms the basis for low-protein diet therapy.

Mechanism of bleomycin: evidence for 4'-ketone formation in poly(dA-dU) associated exclusively with free base release

Incubation of poly(dA-[3'-3H]dU), poly(dA-[5'-3H]dU), or poly(dA-[5'-3H]dT) under a variety of conditions with activated bleomycin resulted in the production of free nucleic acid base, base propenal, and a small amount of 3H2O. Adjustment of the terminated reaction mixture to pH 10 and incubation at 95 degrees C resulted in a time-dependent increase in 3H2O to an amount equal to the amount of free base. If the terminated reaction mixture was incubated with NaBH4 prior to the heat and alkaline treatment, the release of 3H2O was significantly inhibited. These results are consistent with the generation by activated bleomycin of a 4'-ketone yielding free base, with the exchange of the 3'- and 5'-hydrogens by enolization and with the alkaline-induced strand scission occurring from this intermediate.

Mechanism of bleomycin: evidence for a rate-determining 4'-hydrogen abstraction from poly(dA-dU) associated with the formation of both free base and base propenal

When poly(dA-[4'-3H]dU) was degraded by activated bleomycin under a variety of conditions, 50 +/- 10% of the deoxyuridine residues were converted to uracil and uracil propenal, paralleling observations made with DNA. By manipulation of the concentration of O2 in solution, the relative ratio of uracil propenal to uracil could be varied between 0.03 for anaerobic activation and 7.0 for activation at 3 atm of O2. Tritium selection effects on 4'-hydrogen abstraction were also measured under these conditions and found to range from 7.2 to 12.5. These results strongly suggest that the formation of both uracil and uracil propenal is the consequence of a rate-determining 4'-carbon-hydrogen bond cleavage and of an O2-dependent partitioning of the intermediate produced by this cleavage.