[Effects of dopamine and dobutamine on renal function and urinary excretion of prostaglandin E2 in elderly postoperative patients]

Effects of dopamine and dobutamine on renal function and urinary excretion of prostaglandin E2 (UPGE) were studied in 21 elderly patients who underwent abdominal surgery. Fractional sodium excretion (FeNa), creatinine clearance (Ccr), urinary volume (UV, ml.kg-1.min-1) and UPGE were measured on the first and second postoperative day. These patients were divided into three groups: i.e. C (control), DA (dopamine) and DB (dobutamine) groups. Group DA received dopamine 2 mcg.kg-1.min-1 beginning at six o'clock on the first postoperative day. Group DB received dobutamine 2 mcg.kg-1.min-1. There were no significant differences in UV and UPGE among these three groups. Ccr was significantly higher on the second postoperative day than that on the first postoperative day in DA group. FeNa in DA group was higher than in C group on the second postoperative day. The relationship between UPGE and UV was not determined. These results suggest that DA improve renal functions in the elderly.

An anthelmintic compound, nafuredin, shows selective inhibition of complex I in helminth mitochondria

Infections with parasitic helminths are important causes of morbidity and mortality worldwide. New drugs that are parasite specific and minimally toxic to the host are needed to counter these infections effectively. Here we report the finding of a previously unidentified compound, nafuredin, from Aspergillus niger. Nafuredin inhibits NADH-fumarate reductase (complexes I + II) activity, a unique anaerobic electron transport system in helminth mitochondria, at nM order. It competes for the quinone-binding site in complex I and shows high selective toxicity to the helminth enzyme. Moreover, nafuredin exerts anthelmintic activity against Haemonchus contortus in in vivo trials with sheep. Thus, our study indicates that mitochondrial complex I is a promising target for chemotherapy, and nafuredin is a potential lead compound as an anthelmintic isolated from microorganisms.

Chaotic behavior in the locomotion of Amoeba proteus

The locomotion of Amoeba proteus has been investigated by algorithms evaluating correlation dimension and Lyapunov spectrum developed in the field of nonlinear science. It is presumed by these parameters whether the random behavior of the system is stochastic or deterministic. For the analysis of the nonlinear parameters, n-dimensional time-delayed vectors have been reconstructed from a time series of periphery and area of A. proteus images captured with a charge-coupled-device camera, which characterize its random motion. The correlation dimension analyzed has shown the random motion of A. proteus is subjected only to 3-4 macrovariables, though the system is a complex system composed of many degrees of freedom. Furthermore, the analysis of the Lyapunov spectrum has shown its largest exponent takes positive values. These results indicate the random behavior of A. proteus is chaotic and deterministic motion on an attractor with low dimension. It may be important for the elucidation of the cell locomotion to take account of nonlinear interactions among a small number of dynamics such as the sol-gel transformation, the cytoplasmic streaming, and the relating chemical reaction occurring in the cell.

Analysis of the isoform of Xenopus euakryotic translation initiation factor 4E

We have found two isoforms of the eukaryotic translation initiation factor 4E (eIF4E) in Xenopus laevis. These proteins differ in length by 18 amino acids. Overexpression of either of the two eIF4E proteins modestly increase translation in Xenopus oocytes. The results suggest that both of these two isoforms function in translation.

Heme protein-induced chronic renal inflammation: suppressive effect of induced heme oxygenase-1

BACKGROUND

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme; its inducible isozyme, HO-1, protects against acute heme protein-induced nephrotoxicity and other forms of acute tissue injury. This study examines the induction of HO-1 in the kidney chronically inflamed by heme proteins and the functional significance of such an induction of HO-1.

METHODS

Studies were undertaken in a patient with chronic tubulointerstitial disease in the setting of paroxysmal nocturnal hemoglobinuria (PNH), in a rat model of chronic tubulointerstitial nephropathy caused by repetitive exposure to heme proteins, and in genetically engineered mice deficient in HO-1 (HO-1 -/-) in which hemoglobin was repetitively administered.

RESULTS

The kidney in PNH evinces robust induction of HO-1 in renal tubules in the setting of chronic inflammation. The heme protein-enriched urine from this patient, but not urine from a healthy control subject, induced expression of HO-1 in renal tubular epithelial cells (LLC-PK1 cells). A similar induction of HO-1 and related findings are recapitulated in a rat model of chronic inflammation induced by repetitive exposure to heme proteins. Additionally, in the rat, the administration of heme proteins induces monocyte chemoattractant protein (MCP-1). The functional significance of HO-1 so induced was uncovered in the HO-1 knockout mouse: Repeated administration of hemoglobin to HO-1 +/+ and HO-1 -/- mice led to intense interstitial cellular inflammation in HO-1 -/- mice accompanied by striking up-regulation of MCP-1 and activation of one of its stimulators, nuclear factor-kappaB (NF-kappaB). These findings were not observed in similarly treated HO-1 +/+ mice or in vehicle-treated HO-1 -/- and HO-1 +/+ mice.

CONCLUSION

We conclude that up-regulation of HO-1 occurs in the kidney in humans and rats repetitively exposed to heme proteins. Such up-regulation represents an anti-inflammatory response since the genetic deficiency of HO-1 markedly increases activation of NF-kappaB, MCP-1 expression, and tubulointerstitial cellular inflammation.

Definition of crucial structural factors of acetogenins, potent inhibitors of mitochondrial complex I

Some natural acetogenins are the most potent inhibitors of bovine heart mitochondrial complex I. These compounds are characterized by two functional units (i.e. hydroxylated tetrahydrofuran (THF) and alpha,beta-unsaturated gamma-lactone ring moieties) separated by a long alkyl spacer. To elucidate which structural factors of acetogenins including their active conformation are crucial for the potent inhibitory effect, we synthesized a series of novel acetogenin analogues possessing bis-THF rings. The present study clearly demonstrated that the natural gamma-lactone ring is not crucial for the potent inhibition, although this moiety is the most common structural unit among a large number of natural acetogenins and has been suggested to be the only reactive species that directly interacts with the enzyme (Shimada et al., Biochemistry 37 (1998) 854-866). The presence of free hydroxy group(s) in the adjacent bis-THF rings was favorable, but not essential, for the potent activity. This was probably because high polarity (or hydrophilicity), rather than hydrogen bond-donating ability, around the bis-THF rings is required to retain the inhibitor in the active conformation. Interestingly, length of the alkyl spacer proved to be a very important structural factor for the potent activity, the optimal length being approximately 13 carbon atoms. The present study provided further strong evidence for the previous proposal (Kuwabara et al., Eur. J. Biochem. 267 (2000) 2538-2546) that the gamma-lactone and THF ring moieties act in a cooperative manner on complex I with the support of some specific conformation of the spacer.

Cathepsin B contributes to TNF-alpha-mediated hepatocyte apoptosis by promoting mitochondrial release of cytochrome c

TNF-alpha-induced apoptosis is thought to involve mediators from acidic vesicles. Cathepsin B (cat B), a lysosomal cysteine protease, has recently been implicated in apoptosis. To determine whether cat B contributes to TNF-alpha-induced apoptosis, we exposed mouse hepatocytes to the cytokine in vitro and in vivo. Isolated hepatocytes treated with TNF-alpha in the presence of the transcription inhibitor actinomycin D (AcD) accumulated cat B in their cytosol. Further experiments using cell-free systems indicated that caspase-8 caused release of active cat B from purified lysosomes and that cat B, in turn, increased cytosol-induced release of cytochrome c from mitochondria. Consistent with these observations, the ability of TNF-alpha/AcD to induce mitochondrial release of cytochrome c, caspase activation, and apoptosis of isolated hepatocytes was markedly diminished in cells from CatB(-/-) mice. Deletion of the CatB gene resulted in diminished liver injury and enhanced survival after treatment in vivo with TNF-alpha and an adenovirus construct expressing the IkappaB superrepressor. Collectively, these observations suggest that caspase-mediated release of cat B from lysosomes enhances mitochondrial release of cytochrome c and subsequent caspase activation in TNF-alpha-treated hepatocytes.

Epidemiological study of human herpesvirus-6 and human herpesvirus-7 in pityriasis rosea

BACKGROUND

Pityriasis rosea (PR) is a common papulosquamous skin disorder that is suspected to have an infectious aetiology.

OBJECTIVES

We aimed to study the role of human herpesvirus (HHV)-7 and HHV-6 in the pathogenesis of PR.

METHODS

We performed seroepidemiological studies (indirect immunofluorescence test) and polymerase chain reaction (PCR) analysis for HHV-6 and HHV-7 in patients with PR. Seventy-two serum samples and 37 samples of peripheral blood mononuclear cells (PBMC) from 44 patients with PR were obtained. Twenty-five patients with other skin disorders such as drug eruption, urticaria or herpes zoster were studied as controls in the PCR analysis.

RESULTS

HHV-7 DNA was detected in 13 of 30 (43%) samples of PBMC of the patients with PR and 14 of 25 (56%) samples of PBMC of controls. HHV-6 DNA was detected in six of 29 (21%) patients with PR and nine of 23 (39%) controls. Thus there was no difference in the prevalence of HHV-6 or HHV-7 in PBMC between patients with PR and those with other skin disorders. In the seroepidemiological study, two cases of at least a fourfold rise in titre and five cases of a fourfold decrease in titre to HHV-7 antibody, and two cases of a fourfold rise in titre and two cases of a fourfold decrease in titre to HHV-6 antibody, were observed in 24 patients with PR. This seroepidemiological study revealed antibody responses consistent with active infection in several PR patients, but the greater proportion of the patients had no definite increase in the antibody titres.

CONCLUSIONS

We conclude that HHV-7 and HHV-6 may play a part in some patients with PR, but that other causative agents may exist. Further analyses are needed to determine the causative agents of PR.

Splanchnic perfusion during controlled hypotension combined with acute hypervolemic hemodilution: a comparison with combination of acute normovolemic hemodilution-gastric intramucosal pH study

STUDY OBJECTIVE

To evaluate the effect of controlled hypotension combined with acute hypervolemic or normovolemic hemodilution on the splanchnic perfusion in the clinical setting.

DESIGN

Randomized, prospective study.

SETTING

Inpatient surgery at Nagasaki Rosai Hospital.

PATIENTS

28 ASA physical status I and II patients scheduled for total hip arthroplasty.

INTERVENTIONS

Patients were randomly divided into two groups. Group A (n = 14) received controlled hypotension with acute normovolemic hemodilution (ANH). Group B (n = 14) received controlled hypotension with acute hypervolemic hemodilution (HHD). ANH was produced by drawing approximately 1000 mL of blood and replacing it with the same amount of 6% hydroxyethyl starch solution (HES). HHD was produced by preoperative infusion of 1000 mL of 6% HES without removing blood. The final hematocrit values were 24+/-2% (mean +/- SD) in Group A and 25+/-3% in Group B. Controlled hypotension was induced with prostaglandin E1 (PGE1) to maintain mean arterial blood pressure at 55 mmHg for 80 minutes.

MEASUREMENTS

Measurements included the gastric pH (pHi), the arterial blood pH (pHa), and plasma lactate. These indices were measured before hemodilution, after hemodilution, 80 minutes after starting hypotension, 60 minutes after recovery from hypotension, and on the first postoperative day. The value of pHi was measured by tonometric method.

MAIN RESULTS

The pHa and lactate values showed no change in either group A or group B throughout the time course. Gastric pHi values in group A showed a significant decrease from 7.424+/-0.033 to 7.335+/-0.038 (p<0.05) after hemodilution, whereas it showed no further decrease at 80 minutes after starting hypotension and 60 minutes after recovery from hypotension. The pHi values in group B showed no significant decrease after hemodilution and no further change at 80 minutes after starting hypotension.

CONCLUSIONS

HHD does not impair splanchnic perfusion, whereas ANH might cause impairment. Controlled hypotension with prostaglandin E1 would not impair splanchnic perfusion in combination with either HHD or ANH.

Accuracy of detection of colorectal neoplasia using an immunochemical occult blood test in symptomatic referred patients: comparison of retrospective and prospective studies

OBJECTIVE

In this study the sensitivity and specificity of immunochemical tests for colorectal neoplasia were evaluated in retrospective and prospective studies.

METHODS

Four types of fecal blood tests--a chemical test (Hemoccult II) and three different immunochemical tests including a test which detects hemoglobin and transferrin- were performed in the retrospective study. In the prospective study the test for hemoglobin and transferrin was used for all patients that underwent total colonoscopy.

PATIENTS

One hundred seven patients with colorectal neoplasia, 57 with gastroduodenal bleeding, and 62 with normal digestive tracts were examined retrospectively. One thousand two hundred and ninety-eight nonspecifically symptomatic patients whose endoscopic examination was negative for hemorrhagic lesions in the upper digestive tract were examined prospectively.

RESULTS

In the retrospective study, sensitivities for the detection of colorectal cancers and adenomas with diameters > or =10 mm using the tests which detect hemoglobin and transferrin were 98% and 89%, respectively. These were the highest sensitivity among the four tests. The specificity of this test was 97%, which was higher than that of the Hemoccult II test. In the prospective study, the sensitivities of the tests for hemoglobin and transferrin for the detection of colorectal cancers and adenomas with diameters > or =10 mm were 79% and 33%, respectively. The specificity was 95%.

CONCLUSIONS

The test for hemoglobin and transferrin showed the highest sensitivity and specificity for colorectal neoplasia in the retrospective study. The sensitivity and specificity of this test were not so high in the prospective study, but they may be clinically applicable in the evaluation of patients with various nonspecific symptoms.

New type of matrix support for bone marrow cell cultures: in vitro culture and in vivo transplantation experiments

A new type of bone marrow cell culture system was developed by using a highly porous substrate matrix, i.e., porous polyvinyl formal (PVF) resin. Murine bone marrow (BM) cells were cultured without the use of exogenous growth factors in a three-dimensional matrix support made of collagen coated porous PVF resin. To examine the optimal conditions for highest stromal cell density, short-term and long-term in vitro culture experiments using PVF were performed. In the short-term culture experiments, it was found that cubes of PVF (10 x 10 x 2 mm and 130 microm in pore size) coated with type I collagen with a seeding density of 2x10(7) BM cells offered the most appropriate culture conditions. In the long-term cultures, BM cells in PVF maintained their viability for up to 6 weeks. In another series of re-inoculation experiments, freshly isolated BM cells were inoculated onto the already developed stromal layer. In this study, a higher cell density of the stromal layer was obtained in the PVF culture compared with those in the control dish culture. Based upon the results of in vitro experiments, in vivo transplantation studies were also performed. Histologic examinations of the subcutaneously transplanted PVF with stroma revealed host derived hematopoiesis inside the PVF matrix. Moreover, survival of approximately 15% of the transplanted BM cells that were cultured in PVF were confirmed in X-ray irradiated recipients. From these results, it is suggested that PVF resin is a promising three-dimensional substrate for BM cell culture and that it can maintain hematopoietic stem cells or progenitor cells after transplantation.

Long-term culture of fetal liver cells using a three-dimensional porous polymer substrate

To develop a bioartificial liver, long-term culture of fetal liver cells over a month's time was performed under three different culture conditions, i.e., stationary cultures and shaken-flask cultures, both by using a substratum made of porous polyvinyl formal (PVF) resin and conventional monolayer dish cultures as controls. Time course changes in cell numbers and albumin secretion were evaluated in cultures using Williams' E medium (WE) or minimum essential medium alpha (aMEM) supplemented with serum and hormones. In the WE medium, the numbers of fetal liver cells in all culture conditions gradually decreased with time, and albumin secretion rates rapidly decreased. In the stationary cultures using PVF, however, a significant increase in albumin secretion was observed after two weeks of culture. When cells were cultured in aMEM, the fetal liver cells exhibited sufficient proliferation in stationary and monolayer cultures, although albumin secretion rates per single cell were lower than those in WE. On the basis of these results, another series of culture experiments were performed, in which aMEM was used for the first 10 days to encourage cell proliferation, and the medium was changed to WE afterward. In these cultures, albumin secretion rates in the stationary cultures dramatically increased after the medium exchanges and were maintained at these high levels throughout the remaining culture period.

The inhibitory effect of prostaglandin E1 on oxidative stress-induced hepatocyte injury evaluated by calpain-mu activation

BACKGROUND

Prostaglandin E1 (PGE1) is known to inhibit ischemia-reperfusion injury of the liver. The calcium-dependent neutral proteinase, calpain-mu, is involved in oxidative stress-induced hepatocyte injury. We investigated the mechanisms of cytoprotection by PGE1, focusing on the elevation of intracellular calcium ([Ca2+]i), activation of calpain-mu, and calpain-mu-mediated activation of protein kinase C-alpha (PKC-alpha).

METHODS

Cultured hepatocytes were treated with various amounts of PGE1 (0, 0.1, 1.0, 10, and 100 ng/ml) for 30 min and subsequently with 0.5 mM tert-butyl hydroperoxide (TBHP). Cell injury was evaluated by the release of lactate dehydrogenase. Plasma membrane bleb formation was examined by phase contrast microscopy. Activation of calpain-mu and limited degradation of PKC-alpha was evaluated by Western blotting using antibodies that specifically recognize the amino-terminal regions of calpain-mu and PKC-alpha. [Ca2+]i was measured by confocal microscopy using Fluo-3AM.

RESULTS

LDH release from cells treated with 10 ng/ml PGE1 was significantly lower than from untreated cells (135 +/- 12 vs. 258 +/- 18 IU/L, respectively; P < 0.05). Morphologically, many blebs were observed in untreated cells, but very few were seen in those treated with 10 ng/ml PGE1. Western blotting revealed that the amount of activated calpain-mu and [Ca2+]i increased up to 1,300 nM at 35 min after the addition of TBHP (0.5 mmol/L) in control experiments (without PGE1). PGE1 (10 ng/ml) delayed the rise in [Ca2+]i for about 30 min, but did not suppress it completely. PKC-alpha decreased in experiments using PGE1 (10 ng/ml).

CONCLUSION

PGE1 exerts its cytoprotective effect in TBHP-induced hepatocyte injury partly by inhibiting Ca2+-calpain-mu-mediated mechanisms.

Phosphorylation-dependent activation of TAK1 mitogen-activated protein kinase kinase kinase by TAB1

TAK1 is a mitogen-activated protein kinase kinase kinase (MAP3K) that is involved in the c-Jun N-terminal kinase/p38 MAPKs and NF-kappaB signaling pathways. Here, we characterized the molecular mechanisms of TAK1 activation by its specific activator TAB1. Autophosphorylation of two threonine residues in the activation loop of TAK1 was necessary for TAK1 activation. Association with TAK1 and induction of TAK1 autophosphorylation required the C-terminal 24 amino acids of TAB1, but full TAK1 activation required additional C-terminal Ser/Thr rich sequences. These results demonstrated that the association between the kinase domain of TAK1 and the C-terminal TAB1 triggered the phosphorylation-dependent TAK1 activation mechanism.

Bile salts mediate hepatocyte apoptosis by increasing cell surface trafficking of Fas

Toxic bile salts induce hepatocyte apoptosis by a Fas-dependent, Fas ligand-independent mechanism. To account for this observation, we formulated the hypothesis that toxic bile salts induce apoptosis by effecting translocation of cytoplasmic Fas to the cell surface, resulting in transduction of Fas death signals. In McNtcp.24 cells the majority of Fas was cytoplasmic, as assessed by cell fractionation and immunofluorescence studies. However, cell surface Fas increased sixfold after treatment with the toxic bile salt glycochenodeoxycholate (GCDC) in the absence of increased Fas protein expression. Moreover, in cells transfected with Fas-green fluorescence protein, cell surface fluorescence also increased in GCDC-treated cells, directly demonstrating Fas translocation to the plasma membrane. Both brefeldin A, a Golgi-disrupting agent, and nocodazole, a microtubule inhibitor, prevented the GCDC-induced increase in cell surface Fas and apoptosis. In conclusion, toxic bile salts appear to induce apoptosis by promoting cytoplasmic transport of Fas to the cell surface by a Golgi- and microtubule-dependent pathway.

Retroviral vector targeting to human immunodeficiency virus type 1-infected cells by receptor pseudotyping

We report the generation of retroviral vectors based on Moloney murine leukemia virus that specifically transduce cells infected with T-cell-tropic human immunodeficiency virus type 1 (HIV-1). This vector was pseudotyped with T-cell-tropic HIV-1 receptors CD4 and CXCR4. We demonstrate that transduction is contingent upon HIV-1 gp120 and gp41 expression.

[Diabetic nephropathy and low molecular weight advanced glycation end-product in urine]

Glucose reacts non-enzymatically with amino groups of proteins to produce diverse groups of protein-bound moieties with cross-linking properties called advanced glycation end-products (AGEs). A large number of studies suggest that tissue and circulating AGEs, especially those bound to small peptides, play an important role in the pathogenesis and development of diabetic complications. The aim of the present study was to evaluate AGE-peptide levels in the urine in various stages of diabetic nephropathy and to analyze structures of AGEs generated in vivo. Urine samples were obtained from 100 type-2 diabetic patients with various stages of nephropathy, 39 non-diabetic patients with renal dysfunction, and 20 control subjects with neither diabetes nor renal disease. Low molecular weight peptides (< 10 kDa) isolated from each sample were used. With the use of size-exclusion HPLC monitored by AGE-specific fluorescence, three main fluorescence peaks were detected at molecular weights of 6,000 Da, 2,500 Da, and 300 Da. The fluorescence intensity of total AGE-peptide and 6,000 Da peak AGE-peptide is enhanced together with the development of renal dysfunction in diabetic patients, which strongly correlated with the level of serum creatinine. There was no difference in total urinary AGE between diabetic and non-diabetic hemodialysis patients, suggesting that insufficient clearance during dialysis is more important than AGE production. A competitive ELISA using a polyclonal anti-AGE antibody, anion-exchange HPLC, and reversed-phase HPLC were performed on the peaks appearing in size-exclusive HPLC to further characterize the AGE composition. The 300 Da product was specific to diabetic patients with chronic renal failure and hemodialysis patients, which may be a good marker to distinguish diabetic from non-diabetic renal failures. We also speculated that because of its low molecular weight, the 300 Da product might represent the final degradation product of AGE-peptides in the kidney.

Design syntheses and mitochondrial complex I inhibitory activity of novel acetogenin mimics

Some natural acetogenins are the most potent inhibitors of mitochondrial complex I. These compounds are characterized by two functional units [i.e. hydroxylated tetrahydrofuran (THF) and alpha, beta-unsaturated gamma-lactone ring moieties] separated by a long alkyl spacer. To elucidate which structural factors of acetogenins, including their active conformation, are crucial for the potent inhibitory activity we synthesized a novel bis-acetogenin and its analogues possessing two gamma-lactone rings connected to bis-THF rings by flexible alkyl spacers. The inhibitory potency of the bis-acetogenin with bovine heart mitochondrial complex I was identical to that of bullatacin, one of the most potent natural acetogenins. This result indicated that one molecule of the bis-acetogenin does not work as two reactive inhibitors, suggesting that a gamma-lactone and the THF ring moieties act in a cooperative manner on the enzyme. In support of this, either of the two ring moieties synthesized individually showed no or very weak inhibitory effects. Moreover, combined use of the two ring moieties at various molar ratios exhibited no synergistic enhancement of the inhibitory potency. These observations indicate that both functional units work efficiently only when they are directly linked by a flexible alkyl spacer. Therefore, some specific conformation of the spacer must be important for optimal positioning of the two units in the enzyme. Furthermore, the alpha,beta-unsaturated gamma-lactone, the 4-OH group in the spacer region, the long alkyl tail attached to the THF unit and the stereochemistry surrounding the hydroxylated bis-THF rings were not crucial for the activity, although these are the most common structural features of natural acetogenins. The present study provided useful guiding principles not only for simplification of complicated acetogenin structure, but also for further wide structural modifications of these molecules.

Disinfection potential of electrolyzed solutions containing sodium chloride at low concentrations

Electrolyzed products of sodium chloride solution were examined for their disinfection potential against hepatitis B virus (HBV) and human immunodeficiency virus (HIV) in vitro. Electrolysis of 0.05% NaCl in tap water was carried out for 45 min at room temperature using a 3 A electric current in separate wells installed with positive and negative electrodes. The electrolyzed products were obtained from the positive well. The oxidation reduction potential (ORP), pH and free chlorine content of the product were 1053 mV, pH 2.34 and 4.20 ppm, respectively. The products modified the antigenicity of the surface protein of HBV as well as the infectivity of HIV in time- and concentration-dependent manner. Although the inactivating potential was decreased by the addition of contaminating protein, recycling of the product or continuous addition of fresh product may restore the complete disinfection against bloodborne pathogens.

Reactivation of human herpesvirus 6 by infection of human herpesvirus 7

We have attempted to reactivate human herpesvirus 6 (HHV-6) by infection with HHV-7 using childhood exanthem subitum patients in vitro. Peripheral blood mononuclear cells (PBMCs) were collected from children who had a history of exanthem subitum(ES) by HHV-6 and were infected by human herpesvirus 7 (HHV-7) in vitro. The antigen positive rate to HHV-6 started to increase 7 days after the infection and reached a maximum by Day 15 using an immunofluorescence antibody test. The copy number of HHV-6 DNA also increased in the samples in 10 days after infection in vitro. No antigen or increase in DNA was detected in PBMCs, that were mock-infected or infected with supernatant of stock virus after ultracentrifugation, suggesting that an infection by HHV-7 is necessary to reactivate HHV-6. In the paired sera samples during the acute and the convalescent phases of ES, seven to ten bands, that were specific for HHV-6, were recognized in samples from the acute phase, and at least 5 dominant polypeptides were found more intensively after HHV-7 infection.

Regulation of human eIF4E by 4E-BP1: binding analysis using surface plasmon resonance

The interaction between recombinant human eukaryotic initiation factor (eIF)4E and recombinant glutathione S-transferase (GST)-fused human 4E-binding protein (BP)1 was analyzed by using the surface plasmon resonance method. The association rate of 4E-BP1 with eIF4E increased by about two orders of magnitude in the presence of m7GTP (a model compound of mRNA cap structure), but the dissociation rate was scarcely affected, indicating the cap-dependent binding of 4E-BP1 to eIF4E. On the other hand, phosphorylation of 4E-BP1 weakened its interaction with eIF4E whether m7GTP was present or not. However, phosphorylation of 4E-BP1 already associated with eIF4E or its m7GTP complex did not cause any change of the association, probably because of incomplete phosphorylation. This suggests that the regulation of eIF4E by 4E-BP phosphorylation is performed at its free state, not when it is in the associated state with eIF4E. Given these results, we discuss how 4E-BP regulates eIF4E at the first step of translation initiation.