Comparison of oscillations of skin blood flow and deoxygenation in vastus lateralis in light exercise

The purpose of the present study was to compare oscillation of skin blood flow with that of deoxygenation in muscle during light exercise in order to determine the physiological significance of oscillations in deoxygenation. Prolonged exercise with 50% of peak oxygen uptake was performed for 60 min. Skin blood flow (SBF) was measured using a laser blood flow meter on the right vastus lateralis muscle. Deoxygenated haemoglobin/myoglobin (DHb/Mb) concentration in the left vastus lateralis were measured using a near-infrared spectroscopy system. SBF and DHb/Mb during exercise were analysed by fast Fourier transform. We classified frequency bands according to previous studies (Kvernmo et al. 1999, Kvandal et al. 2006) into phase I (0.005-0.0095 and 0.0095-0.02 Hz), phase II (0.02-0.06 Hz: phase II) and phase III (0.06-0.16 Hz). The first peak of power spectra density (PSD) in SBF appeared at 0.0078 Hz in phase I. The second peak of PSD in SBF appeared at 0.035 Hz. The third peak of PSD in SBF appeared at 0.078 Hz. The first peak of PSD in DHb/Mb appeared at 0.0039 Hz, which was out of phase I. The second peak of PSD in DHb/Mb appeared at 0.016 Hz. The third peak of PSD in DHb/Mb appeared at 0.035 Hz. The coefficient of cross correlation was very low. Cross power spectra density showed peaks of 0.0039, 0.016 and 0.035 Hz. It is concluded that a peak of 0.016 Hz in oscillations of DHb/Mb observed in muscle during exercise is associated with endothelium-dependent vasodilation (phase I) and that a peak of 0.035 Hz in DHb/Mb is associated with sympathetic nerve activity (phase II). It is also confirmed that each peak of SBF oscillations is observed in each phase.

An in-depth comparison of latent HIV-1 reactivation in multiple cell model systems and resting CD4+ T cells from aviremic patients

The possibility of HIV-1 eradication has been limited by the existence of latently infected cellular reservoirs. Studies to examine control of HIV latency and potential reactivation have been hindered by the small numbers of latently infected cells found in vivo. Major conceptual leaps have been facilitated by the use of latently infected T cell lines and primary cells. However, notable differences exist among cell model systems. Furthermore, screening efforts in specific cell models have identified drug candidates for "anti-latency" therapy, which often fail to reactivate HIV uniformly across different models. Therefore, the activity of a given drug candidate, demonstrated in a particular cellular model, cannot reliably predict its activity in other cell model systems or in infected patient cells, tested ex vivo. This situation represents a critical knowledge gap that adversely affects our ability to identify promising treatment compounds and hinders the advancement of drug testing into relevant animal models and clinical trials. To begin to understand the biological characteristics that are inherent to each HIV-1 latency model, we compared the response properties of five primary T cell models, four J-Lat cell models and those obtained with a viral outgrowth assay using patient-derived infected cells. A panel of thirteen stimuli that are known to reactivate HIV by defined mechanisms of action was selected and tested in parallel in all models. Our results indicate that no single in vitro cell model alone is able to capture accurately the ex vivo response characteristics of latently infected T cells from patients. Most cell models demonstrated that sensitivity to HIV reactivation was skewed toward or against specific drug classes. Protein kinase C agonists and PHA reactivated latent HIV uniformly across models, although drugs in most other classes did not.

Oscillation of oxygenation in skeletal muscle at rest and in light exercise

The aim of the present study was to compare the frequency of oxygenation determined in the vastus lateralis by near-infrared spectroscopy (NIRS) in light exercise with that at rest. A subject rested in a recumbent position for 5 min and changed body position to a sitting position on a cycle ergometer for 9 min. Then exercise with low intensity (work rate of 60% of maximal oxygen uptake) was carried out for 30 min. Total hemoglobin and myoglobin (THb/Mb) suddenly decreased after the start of exercise and gradually increased for 6 min. Oxygenated hemoglobin and myoglobin (Hb/MbO2) suddenly decreased and returned to a steady-state after the start of exercise. The difference between Hb/MbO2 and THb/Mb showed a sudden decrease and then a steady-state. This difference was analyzed by fast Fourier transform. The peak frequencies of the power spectrum density (PSD) were 0.0169 ± 0.0076 Hz at rest and 0.0117 ± 0.0042 Hz in exercise. The peak frequency of PSD was significantly decreased in exercise. In exercise, the range of frequencies was expanded. It is concluded that there are oscillations at rest as well as in exercise and that the frequency of peak PSD becomes lower in exercise than at rest.

SIRT1 enhances Th17 cell generation by deacetylating RORγt (P1163)

Although Sirtuin 1 (SIRT1), an NAD-dependent protein deacetylase, has emerged as a critical regulator of the cell cycle, replicative senescence, inflammation, and metabolism, its contribution to immune function remains to be fully investigated. Here we report that SIRT1 regulates the function of IL-17 producing CD4 T helper cells (Th17 cells) by modulating the activity of the Th17 master transcription factor RORγt. We found that Sirt1 interacts with RORγt and increases its transcriptional activity by deacetylating lysine residues K16 and K81. In mixed hematopoietic chimeras, cells from donors in which Sirt1 is deleted in ROR γ+ cells (SIRT1-cKO) exhibited compromised Th17 differentiation. Moreover, SIRT1-cKO mice were resistant to developing experimental autoimmune encephalomyelitis (EAE) upon MOG peptide immunization. Importantly, the SIRT1 specific inhibitor Ex-527 substantially inhibited trans-differentiation to Th17 cells in vitro, and injection of Ex-527 into mice strongly blocked EAE disease progression in vivo. These findings reveal a previously unappreciated proinflammatory role of SIRT1 in CD4 T cells, and provide significant evidence that pharmacological SIRT1 inhibitors might constitute a novel approach in the treatment of Th17-mediated autoimmune diseases such as multiple sclerosis.

Relationship between ventilation and predicted arterial CO2 pressure during recovery from an impulse-like exercise without metabolic acidosis

We investigated ventilation (V(.)E) control factors during recovery from light impulse-like exercise (100 watts) with a duration of 20 s. Blood ions and gases were measured at rest and during recovery. V(.)E, end tidal CO(2) pressure (PETCO(2)) and respiratory exchange ratio (RER) were measured continuously during rest, exercise and recovery periods. Arterial CO(2) pressure (PaCO(2) (pre) was estimated from PETCO(2) and tidal volume (V(T)). RER at 20 s of exercise and until 50 s during recovery was significantly lower than RER at rest. Despite no change in arterialized blood pH level, PaCO(2) (pre) was significantly higher in the last 10 s of exercise and until 70 s during recovery than the resting value. V(.)E increased during exercise and then decreased during recovery; however, it was elevated and was significantly higher than the resting value until 155 s (p<0.05). There was a significant relationship between V(.)E and PaCO(2) (pre) during the first 70 s of recovery in each subject. The results suggest that PaCO(2) drives V(.)E during the first 70 s of recovery after light impulse-like exercise. Elevated V(.)E in the interval from 70 s until 155 s during recovery might be due to neural factors.

Reactivation of latent HIV by histone deacetylase inhibitors

Latent HIV persists in CD4(+) T cells in infected patients under antiretroviral therapy (ART). Latency is associated with transcriptional silencing of the integrated provirus and driven, at least in part, by histone deacetylases (HDACs), a family of chromatin-associated proteins that regulate histone acetylation and the accessibility of DNA to transcription factors. Remarkably, inhibition of HDACs is sufficient to reactivate a fraction of latent HIV in a variety of experimental systems. This basic observation led to the shock and kill idea that forcing the transcriptional activation of HIV might lead to virus expression, to virus- or host-induced cell death of the reactivated cells, and to the eradication of the pool of latently infected cells. Such intervention might possibly lead to a cure for HIV-infected patients. Here, we review the basic biology of HDACs and their inhibitors, the role of HDACs in HIV latency, and recent efforts to use HDAC inhibitors to reactivate latent HIV in vitro and in vivo.

Comparison of oscillation of oxygenation in skeletal muscle between early and late phases in prolonged exercise

The aim of the present study was to compare the oscillations of oxygenation in skeletal muscle between early and late phases in prolonged exercise. During prolonged exercise at 60 % of peak oxygen uptake (V(.)o(2)) for 60 min and at rest, oxygenated hemoglobin/myoglobin (Hb/MbO(2)) and total Hb/Mb (THb/Mb) were determined by near-infrared spectroscopy in the vastus lateralis. Power spectra density (PSD) for the difference between Hb/MbO(2) and THb/Mb (-HHb/MbO(2): deoxygenation) was obtained by fast Fourier transform at rest, in the early phase (1-6 min) and in the late phase (55-60 min) in exercise. Peak PSD in the early phase was significantly higher than that at rest. There were at least three peaks of PSD in exercise. The highest peak was a band around 0.01 Hz, the next peak was a band around 0.04 Hz, and the lowest peak was a band around 0.06 Hz. PSD in the early phase was not significantly different from that in the late phase in exercise. Heart rate (HR) showed a continuous significant increase from 3 min in exercise until the end of exercise. Skin blood flow (SBF) around the early phase was significantly lower than that around the late phase. It was concluded that oscillation of oxygenation in the muscle oxygen system in the early phase is not different from that in the late phase in prolonged exercise despite cardiovascular drift.

Suppression of oxidative stress by β-hydroxybutyrate, an endogenous histone deacetylase inhibitor

Concentrations of acetyl-coenzyme A and nicotinamide adenine dinucleotide (NAD(+)) affect histone acetylation and thereby couple cellular metabolic status and transcriptional regulation. We report that the ketone body d-β-hydroxybutyrate (βOHB) is an endogenous and specific inhibitor of class I histone deacetylases (HDACs). Administration of exogenous βOHB, or fasting or calorie restriction, two conditions associated with increased βOHB abundance, all increased global histone acetylation in mouse tissues. Inhibition of HDAC by βOHB was correlated with global changes in transcription, including that of the genes encoding oxidative stress resistance factors FOXO3A and MT2. Treatment of cells with βOHB increased histone acetylation at the Foxo3a and Mt2 promoters, and both genes were activated by selective depletion of HDAC1 and HDAC2. Consistent with increased FOXO3A and MT2 activity, treatment of mice with βOHB conferred substantial protection against oxidative stress.

HIV latency: experimental systems and molecular models

Highly active antiretroviral therapy (HAART) has shown great efficacy in increasing the survival of HIV infected individuals. However, HAART does not lead to the full eradication of infection and therefore has to be continued for life. HIV persists in a transcriptionally inactive form in resting T cells in HAART-treated patients and can be reactivated following T-cell activation. These latently infected cells allow the virus to persist in the presence of HAART. Here, we review recent advances in the study of the molecular mechanisms of HIV latency. We also review experimental models in which latency is currently studied. We focus on the epigenetic mechanisms controlling HIV transcription and on the role of chromatin and its post-translational modifications. We discuss how small molecule inhibitors that target epigenetic regulators, such as HDAC (histone deacetylase) inhibitors, are being tested for their ability to reactivate latent HIV. Finally, we discuss the clinical potential of these drugs to flush out latently infected cells from HIV-infected patients and to eradicate the virus.

Epigenetic regulation of HIV latency

PURPOSE OF REVIEW

A reservoir of latently infected cells remains in HIV-infected patients treated with highly active antiretroviral therapy treatment. Persistence of HIV in this latent reservoir has prevented full viral eradication. In order to understand and develop rational therapeutics to flush out HIV latency, the molecular mechanisms governing the phenomena of HIV latency need to be understood. Several mechanisms have been proposed to explain HIV latency.

RECENT FINDINGS

Epigenetic regulation of the HIV promoter in the 5' long terminal repeat of HIV-1 via histone protein modifications and the presence of inhibitory nucleosomes play a critical role in the establishment, maintenance, and reactivation of HIV latency. Recent reports have shed further light on how HIV latency might be epigenetically regulated. In this review, we discuss how these recent reports broaden our understanding of how HIV latency is regulated. Here, we review how histone modifications and chromatin remodeling affect the transcriptional activity of the HIV promoter in the context of HIV latency.

SUMMARY

These new epigenetic regulators of HIV latency pose as potential interesting candidates for therapeutics against HIV latency.

MDM2 is a novel E3 ligase for HIV-1 Vif

The human immunodeficiency virus type 1 (HIV-1) Vif plays a crucial role in the viral life cycle by antagonizing a host restriction factor APOBEC3G (A3G). Vif interacts with A3G and induces its polyubiquitination and subsequent degradation via the formation of active ubiquitin ligase (E3) complex with Cullin5-ElonginB/C. Although Vif itself is also ubiquitinated and degraded rapidly in infected cells, precise roles and mechanisms of Vif ubiquitination are largely unknown. Here we report that MDM2, known as an E3 ligase for p53, is a novel E3 ligase for Vif and induces polyubiquitination and degradation of Vif. We also show the mechanisms by which MDM2 only targets Vif, but not A3G that binds to Vif. MDM2 reduces cellular Vif levels and reversely increases A3G levels, because the interaction between MDM2 and Vif precludes A3G from binding to Vif. Furthermore, we demonstrate that MDM2 negatively regulates HIV-1 replication in non-permissive target cells through Vif degradation. These data suggest that MDM2 is a regulator of HIV-1 replication and might be a novel therapeutic target for anti-HIV-1 drug.

Cytidine deaminases as a weapon against retroviruses and a new target for antiviral therapy

APOBEC3G (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G) was identified as an anti-HIV-1 (human immunodeficiency virus type 1) cellular factor in target CD4 T cells. It is a member of the APOBEC family of cytidine deaminases consisting of APOBEC1, APOBEC2, APOBEC3 (A to H), and AID (activation induced deaminase). During reverse transcription, it deaminates dC to dU in nascent minus-strand viral DNA, resulting in G-to-A hypermutation in the plus strand DNA to inhibit the replication of HIV-1. On the contrary, HIV-1 Vif protein counteracts this enzyme by the ubiquitin-proteasome pathway to enable HIV-1 replicate in target cells. Vif forms an E3 ligase complex with cellular proteins including Cullin5, ElonginB, and ElonginC (Vif-BC-Cul5) and functions as a substrate recognition subunit of the complex to target APOBEC3G for ubiquitin-proteasome dependent degradation in virus-producing cells. APOBEC3G has also been shown to have a broad antiviral activity on a wide variety of viruses which include not only retroviruses such as other lentiviruses, murine leukemia virus (MLV), and human T-cell leukemia virus type 1 (HTLV-1) but also other viruses such as hepatitis B virus (HBV) and adeno-associated virus. Furthermore, other members of the APOBEC family also show a broad antiviral activity, but target virus specificities vary among APOBEC members. On the other hand, viruses have their own mechanisms to escape from APOBEC. These expanding evidences suggest that the APOBEC family of cytidine deaminases plays an important role in antiviral innate immunity and might be a novel target for an antiviral therapy. Here we review the present understanding of APOBEC3 proteins as an antiviral innate immunity and battles between APOBEC3 and viruses.

Dual effect of APOBEC3G on Hepatitis B virus

G to A hypermutation of Hepatitis B virus (HBV) and retroviruses appears as a result of deamination activities of host APOBEC proteins and is thought to play a role in innate antiviral immunity. Alpha and gamma interferons (IFN-alpha and -gamma) have been reported to upregulate the transcription of APOBEC3G, which is known to reduce the replication of HBV. We investigated the number of hypermutated genomes under various conditions by developing a quantitative measurement. The level of hypermutated HBV in a HepG2 cell line, which is semi-permissive for retrovirus, was 2.3 in 10(4) HBV genomes, but only 0.5 in 10(4) in permissive Huh7 cells. The level of APOBEC3G mRNA was about ten times greater in HepG2 cells than in Huh7 cells. Treatment of HepG2 cells with either IFN-alpha or -gamma increased the transcription of APOBEC3G and hypermutation of HBV. These mRNAs and hypermutation of HBV genomes were induced more prominently by IFN-gamma than by IFN-alpha. Both IFNs decreased the number of replicative intermediate of HBV. Overexpression of APOBEC3G reduced the number of replicative intermediate of HBV and increased hypermutated genomes 334 times, reaching 968 in 10(4) genomes. Deamination-inactive APOBEC3G did not induce hypermutation, but reduced the virus equally. Our results suggest that APOBEC3G, upregulated by IFNs, has a dual effect on HBV: induction of hypermutation and reduction of virus synthesis. The effect of hypermutation on infectivity should be investigated further.

Murine retrovirus escapes from murine APOBEC3 via two distinct novel mechanisms

APOBEC3G (A3G) is an antiretroviral host factor that functions by deaminating dC to dU in retroviral cDNA. HIV-1 Vif protein counteracts A3G via a ubiquitin-proteasome pathway. In the case of a simple retrovirus such as the murine leukemia virus (MLV), it remains unclear why it can replicate in cells expressing APOBEC3 (A3) even though it doesn't possess any accessory proteins such as Vif. In this study, we demonstrate that MLV escapes from murine A3 (mA3) via two distinct novel mechanisms. First, viral RNA (vRNA) blocks the binding of mA3 to Gag, resulting in the exclusion of mA3 from MLV virions. Second, viral protease (vPR) cleaves mA3 after maturation of virions. Here, we suggest that each virus has its own strategy to escape from A3 proteins and that these mechanisms might be used by other viruses that do not possess Vif-like protein. On the other hand, mice possess another form of mA3, delta exon5, that escapes from the cleavage by vPR to show more antiviral activity than the wild type mA3. This also suggests that battles between host intrinsic immunity and viruses have led to the evolution of proteins on both sides.

Ubiquitination of APOBEC3 proteins by the Vif–Cullin5–ElonginB–ElonginC complex

APOBEC3 proteins are antiviral host factors for a wide variety of retroviruses. HIV-1 Vif overcomes the antiviral activity of APOBEC3G by ubiquitinating the protein. In this study, we examined the ability of Vif to antagonize other family members of APOBEC3 proteins, together with its mechanism. Using HIV infectivity, virion incorporation, immunoprecipitation, and in vitro ubiquitin conjugation assays, we show that the ability of Vif to inhibit antiviral activity of APOBEC3 proteins positively correlates with its ability to bind and ubiquitinate these proteins by a Vif-Cullin5-ElonginB-ElonginC (Vif-BC-Cul5) complex. These results suggest that Vif exhibits its anti-APOBEC3 activity by the ubiquitin ligase activity of the Vif-BC-Cul5 complex.

Minimal change oesophagitis: a disease with characteristic differences to erosive oesophagitis

BACKGROUND

The majority of gastro-oesophageal reflux disease (GERD) seems to be non-erosive reflux disease. Nonerosive reflux disease includes minimal change oesophagitis (whitish or reddish, oedematous change and erosion that is not regarded as mucosal break) and no endoscopic abnormalities.

AIM

To investigate the accurate proportion of those with minimal change oesophagitis and to clarify its characteristics. In addition, we evaluated the effect of famotidine (40 mg/day) in those with minimal change.

METHODS

Prospective endoscopic assessment was performed for consecutive 606 out-patients. Of the 582 patients suitable for analysis, 347 were non-treated. The latter were divided into those with erosive GERD or minimal change, and their endoscopic findings and characteristics were compared.

RESULTS

Among 347 non-treated patients, 88 (25%) had erosive GERD and 249 (72%) had minimal change. Compared with patients who have erosive GERD and those with minimal change, the latter were less likely to have hiatal hernia or bile reflux, but more likely to have gastric atrophy. Symptomatic patients (n = 55) with minimal change oesophagitis were more likely to have hiatal hernia than those who were asymptomatic (n= 194). Most patients preferred taking famotidine on-demand, during a 4-week follow-up period.

CONCLUSIONS

Most non-erosive reflux disease can be classified as minimal change oesophagitis, and that have different characteristics from erosive GERD. On-demand famotidine may be a suitable alternative treatment for patients with minimal change disease.

APOBEC3G targets human T-cell leukemia virus type 1

Background

Apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3G) is a host cellular protein with a broad antiviral activity. It inhibits infectivitiy of a wide variety of retroviruses by deaminating deoxycytidine (dC) into deoxyuridine (dU) in newly synthesized minus strand DNA, resulting in G-to-A hypermutation of the viral plus strand DNA. To clarify the mechanism of its function, we have examined the antiviral activity of APOBEC3G on human T-cell leukemia virus type 1 (HTLV-1), the first identified human retrovirus.

Results

In this study, we have demonstrated that overexpressed as well as endogenous APOBEC3G were incorporated into HTLV-1 virions and that APOBEC3G inhibited the infection of HTLV-1. Interestingly, several inactive mutants of APOBEC3G also inhibited HTLV-1 and no G-to-A hypermutation was induced by APOBEC3G in HTLV-1 genome. Furthermore, we introduced the human immunodeficiency virus type 1 (HIV-1) vif gene into HTLV-1 producing cell line, MT-2, to antagonize APOBEC3G by reducing its intracellular expression and virion incorporation, which resulted in upregulation of the infectivity of produced viruses.

Conclusion

APOBEC3G is incorporated into HTLV-1 virions and inhibits the infection of HTLV-1 without exerting its cytidine deaminase activity. These results suggest that APOBEC3G might act on HTLV-1 through different mechanisms from that on HIV-1 and contribute to the unique features of HTLV-1 infection and transmission.

[Analyses of the allogeneic stem cell transplantation outcome based on the new risk classification]

To disclose the information for the risk in allogeneic hematopoietic stem cell transplantation (allo-HSCT), we propose a new concept of the risk in allo-HSCT. We analyzed all 94 allo-HSCT cases (86 patients) in our hospital since 1983. The overall survival rate was 56.4%. Among 27 patients considered to be at standard risk judged by conventional risk criteria who underwent initial transplantation from HLA-identical donors, 66.7% of them survived. Univariate statistical analyses among subgroups classified by conventional risk criteria and several reported prognostic factors show significant differences. However, all of them failed to show significant difference because of too much variation between cases in the same subgroup or a too small number of patients as compared with the U.S.A or European transplantation centers. We propose an alternative comprehensive classification of transplantation risk according to two newly-recognized distinct risks, disease state and transplantation risk. This comprehensive classification revealed significance in the multivariate statistical analyses in our hospital. We expect further discussion or the appearance of other beneficial nationwide proposals to evaluate and disclose the risk affecting survival following allo-HSCT.