Patterns of recombination in snakes reveal a tug-of-war between PRDM9 and promoter-like features

In some mammals, notably humans, recombination occurs almost exclusively where the protein PRDM9 binds, whereas in vertebrates lacking an intact PRDM9, such as birds and canids, recombination rates are elevated near promoter-like features. To determine whether PRDM9 directs recombination in nonmammalian vertebrates, we focused on an exemplar species with a single, intact PRDM9 ortholog, the corn snake (Pantherophis guttatus). Analyzing historical recombination rates along the genome and crossovers in pedigrees, we found evidence that PRDM9 specifies the location of recombination events, but we also detected a separable effect of promoter-like features. These findings reveal that the uses of PRDM9 and promoter-like features need not be mutually exclusive and instead reflect a tug-of-war that is more even in some species than others.

Patterns of recombination in snakes reveal a tug of war between PRDM9 and promoter-like features

In vertebrates, there are two known mechanisms by which meiotic recombination is directed to the genome: in humans, mice, and other mammals, recombination occurs almost exclusively where the protein PRDM9 binds, while in species lacking an intact PRDM9, such as birds and canids, recombination rates are elevated near promoter-like features. To test if PRDM9 also directs recombination in non-mammalian vertebrates, we focused on an exemplar species, the corn snake (Pantherophis guttatus). Unlike birds, this species possesses a single, intact PRDM9 ortholog. By inferring historical recombination rates along the genome from patterns of linkage disequilibrium and identifying crossovers in pedigrees, we found that PRDM9 specifies the location of recombination events outside of mammals. However, we also detected an independent effect of promoter-like features on recombination, which is more pronounced on macro- than microchromosomes. Thus, our findings reveal that the uses of PRDM9 and promoter-like features are not mutually-exclusive, and instead reflect a tug of war, which varies in strength along the genome and is more lopsided in some species than others.

Bioceramic Scaffold Materials in Joint Movement Rehabilitation of Patients with Osteoarthritis

Arthritis occurs when the bones and joints have focal or degenerative diseases. This can lead to impaired performance and quality of life of the patient. Surgical treatment is used when the bones and joints are worn out or tumors, but often due to incomplete surgery, repeated attacks will occur. Bioceramic scaffold materials can assist in repairing cartilage tissue defects and, at the same time, contribute to arthritis rehabilitation. Therefore, this article will take this as the starting point of the research and use the new porous nanoceramic scaffold material to study its effect on joint repair in patients with osteoarthritis. The research results confirmed that the porous nanoceramic scaffold material has good biocompatibility in the treatment.

Dual histone methyl reader ZCWPW1 facilitates repair of meiotic double strand breaks in male mice

Meiotic crossovers result from homology-directed repair of DNA double-strand breaks (DSBs). Unlike yeast and plants, where DSBs are generated near gene promoters, in many vertebrates DSBs are enriched at hotspots determined by the DNA binding activity of the rapidly evolving zinc finger array of PRDM9 (PR domain zinc finger protein 9). PRDM9 subsequently catalyzes tri-methylation of lysine 4 and lysine 36 of Histone H3 in nearby nucleosomes. Here, we identify the dual histone methylation reader ZCWPW1, which is tightly co-expressed during spermatogenesis with Prdm9, as an essential meiotic recombination factor required for efficient repair of PRDM9-dependent DSBs and for pairing of homologous chromosomes in male mice. In sum, our results indicate that the evolution of a dual histone methylation writer/reader (PRDM9/ZCWPW1) system in vertebrates remodeled genetic recombination hotspot selection from an ancestral static pattern near genes towards a flexible pattern controlled by the rapidly evolving DNA binding activity of PRDM9.

The Arms Race Between KRAB–Zinc Finger Proteins and Endogenous Retroelements and Its Impact on Mammals

Nearly half of the human genome consists of endogenous retroelements (EREs) and their genetic remnants, a small fraction of which carry the potential to propagate in the host genome, posing a threat to genome integrity and cell/organismal survival. The largest family of transcription factors in tetrapods, the Krüppel-associated box domain zinc finger proteins (KRAB-ZFPs), binds to specific EREs and represses their transcription. Since their first appearance over 400 million years ago, KRAB-ZFPs have undergone dramatic expansion and diversification in mammals, correlating with the invasions of new EREs. In this article we review our current understanding of the structure, function, and evolution of KRAB-ZFPs and discuss growing evidence that the arms race between KRAB-ZFPs and the EREs they target is a major driving force for the evolution of new traits in mammals, often accompanied by domestication of EREs themselves.

Natural Negative Allosteric Modulators of 5-HT₃ Receptors

Chemotherapy-induced nausea and vomiting (CINV) remain the most common and devastating side-effects associated with cancer chemotherapy. In recent decades, several lines of research emphasize the importance of 5-hydroxytryptamine3 (5-HT3; serotonin) receptors in the pathogenesis and treatment of CINV. 5-HT₃ receptors are members of ligand-gated ion channels that mediate the rapid and transient membrane-depolarizing effect of 5-HT in the central and peripheral nervous system. These receptors play important roles in nausea and vomiting, as well as regulation of peristalsis and pain transmission. The development of antagonists for 5-HT₃ receptor dramatically improved the treatment of CINV in cancer patients. In fact, the most common use of 5-HT₃ receptor antagonists to date is the treatment of nausea and vomiting. In recent years, there has been an increasing tendency to use natural plant products as important therapeutic entities in the treatment of various diseases. In this article, we examined the results of earlier studies on the actions of natural compounds on the functional properties of 5-HT₃ receptors. It is likely that these natural modulators of 5-HT₃ receptors can be employed as lead structures for the synthesis of therapeutic agents for treating CINV in future clinical studies.

Sporadic on/off switching of HTLV-1 Tax expression is crucial to maintain the whole population of virus-induced leukemic cells

Viruses causing chronic infection artfully manipulate infected cells to enable viral persistence in vivo under the pressure of immunity. Human T-cell leukemia virus type 1 (HTLV-1) establishes persistent infection mainly in CD4+ T cells in vivo and induces leukemia in this subset. HTLV-1-encoded Tax is a critical transactivator of viral replication and a potent oncoprotein, but its significance in pathogenesis remains obscure due to its very low level of expression in vivo. Here, we show that Tax is expressed in a minor fraction of leukemic cells at any given time, and importantly, its expression spontaneously switches between on and off states. Live cell imaging revealed that the average duration of one episode of Tax expression is ∼19 hours. Knockdown of Tax rapidly induced apoptosis in most cells, indicating that Tax is critical for maintaining the population, even if its short-term expression is limited to a small subpopulation. Single-cell analysis and computational simulation suggest that transient Tax expression triggers antiapoptotic machinery, and this effect continues even after Tax expression is diminished; this activation of the antiapoptotic machinery is the critical event for maintaining the population. In addition, Tax is induced by various cytotoxic stresses and also promotes HTLV-1 replication. Thus, it seems that Tax protects infected cells from apoptosis and increases the chance of viral transmission at a critical moment. Keeping the expression of Tax minimal but inducible on demand is, therefore, a fundamental strategy of HTLV-1 to promote persistent infection and leukemogenesis.

Human T-cell leukemia virus type 1 infects multiple lineage hematopoietic cells in vivo

Human T-cell leukemia virus type 1 (HTLV-1) infects mainly CD4⁺CCR4⁺ effector/memory T cells in vivo. However, it remains unknown whether HTLV-1 preferentially infects these T cells or this virus converts infected precursor cells to specialized T cells. Expression of viral genes in vivo is critical to study viral replication and proliferation of infected cells. Therefore, we first analyzed viral gene expression in non-human primates naturally infected with simian T-cell leukemia virus type 1 (STLV-1), whose virological attributes closely resemble those of HTLV-1. Although the tax transcript was detected only in certain tissues, Tax expression was much higher in the bone marrow, indicating the possibility of de novo infection. Furthermore, Tax expression of non-T cells was suspected in bone marrow. These data suggest that HTLV-1 infects hematopoietic cells in the bone marrow. To explore the possibility that HTLV-1 infects hematopoietic stem cells (HSCs), we analyzed integration sites of HTLV-1 provirus in various lineages of hematopoietic cells in patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) and a HTLV-1 carrier using the high-throughput sequencing method. Identical integration sites were detected in neutrophils, monocytes, B cells, CD8⁺ T cells and CD4⁺ T cells, indicating that HTLV-1 infects HSCs in vivo. We also detected Tax protein in myeloperoxidase positive neutrophils. Furthermore, dendritic cells differentiated from HTLV-1 infected monocytes caused de novo infection to T cells, indicating that infected monocytes are implicated in viral spreading in vivo. Certain integration sites were re-detected in neutrophils from HAM/TSP patients at different time points, indicating that infected HSCs persist and differentiate in vivo. This study demonstrates that HTLV-1 infects HSCs, and infected stem cells differentiate into diverse cell lineages. These data indicate that infection of HSCs can contribute to the persistence and spread of HTLV-1 in vivo.

HTLV-1 primarily infects peripheral CD4⁺CCR4⁺CADM1⁺ T cells in vivo. In this study, we show that HTLV-1 infects HSCs, which differentiate into multiple lineages of hematopoietic cells, and likely act as viral reservoir, giving rise to infected neutrophils, monocytes and B cells. Infected monocytes are thought to spread virus in vivo. Infected T cells in the periphery are chimeric in origin: T cells newly infected in the periphery, and infected T cells differentiated from infected HSCs. This observation suggests that viral genes such as HBZ and tax are responsible for converging the molecular differentiation program into a single direction with the characteristic immunophenotype associated with the expression of CCR4 and CADM1. It has been believed that HTLV-1 infects target cells in the periphery. However, this study reveals a new strategy of HTLV-1 spreading in vivo. These findings have implications for understanding of HTLV-1 pathogenesis as well as treatment of HTLV-1 associated diseases.

HTLV-1 Viral Factor HBZ Induces CCR4 to Promote T-cell Migration and Proliferation

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia-lymphoma (ATL) and other inflammatory diseases in infected individuals. However, a complete understanding of how HTLV-1 transforms T cells is lacking. Expression of the chemokine receptor CCR4 on ATL cells and HTLV-1-infected cells suggested the hypothesis that CCR4 may mediate features of ATL and inflammatory diseases caused by HTLV-1. In this study, we show that the constitutively expressed HTLV-1 bZIP factor (HBZ) encoded by HTLV-1 is responsible for inducing CCR4 and its ability to promote T-cell proliferation and migration. Ectopic expression of HBZ was sufficient to stimulate expression of CCR4 in human and mouse T cells. Conversely, HBZ silencing in ATL cell lines was sufficient to inhibit CCR4 expression. Mechanistic investigations showed that HBZ induced GATA3 expression in CD4(+) T cells, thereby activating transcription from the CCR4 promoter. In an established air pouch model of ATL, we observed that CD4(+) T cells of HBZ transgenic mice (HBZ-Tg mice) migrated preferentially to the pouch, as compared with those in nontransgenic mice. Migration of CD4(+) T cells in HBZ-Tg mice was inhibited by treatment with a CCR4 antagonist. Proliferating (Ki67(+)) CD4(+) T cells were found to express high levels of CCR4 and CD103. Further, CD4(+) T-cell proliferation in HBZ-Tg mice was enhanced by coordinate treatment with the CCR4 ligands CCL17 and 22 and with the CD103 ligand E-cadherin. Consistent with this finding, we found that ATL cells in clinical skin lesions were frequently positive for CCR4, CD103, and Ki67. Taken together, our results show how HBZ activates CCR4 expression on T cells to augment their migration and proliferation, two phenomena linked to HTLV-1 pathogenesis. Cancer Res; 76(17); 5068-79. ©2016 AACR.

Temperature variable high-pressure volumetric studies of diethylene glycol

It was demonstrated that direct compression experiments in a piston-cylinder press provide precise information on volume data and phase transition pressure complementary to X-ray diffraction. The experimental setup, described in detail previously [1], is capable of compressing liquid and solid samples up to ca. 2 GPa. We have continued these studies adding temperature control of the sample. Piston and cylinder chamber was placed in an thermally isolated mantle. The constant temperature was maintained by circulating hot air. As demonstrated by the experiments on diethylene glycol, it is a relatively quick and simple, yet efficient method for exploring phase diagrams and recording volume reduction at phase transition in different thermodynamic conditions.

Effects of cannabidiol on the function of α7-nicotinic acetylcholine receptors

The effects of cannabidiol (CBD), a non-psychoactive ingredient of cannabis plant, on the function of the cloned α7 subunit of the human nicotinic acetylcholine (α7 nACh) receptor expressed in Xenopus oocytes were tested using the two-electrode voltage-clamp technique. CBD reversibly inhibited ACh (100 μM)-induced currents with an IC50 value of 11.3 µM. Other phytocannabinoids such as cannabinol and Δ(9)-tetrahydrocannabinol did not affect ACh-induced currents. CBD inhibition was not altered by pertussis toxin treatment. In addition, CBD did not change GTP-γ-S binding to the membranes of oocytes injected with α7 nACh receptor cRNA. The effect of CBD was not dependent on the membrane potential. CBD (10 µM) did not affect the activity of endogenous Ca(2+)-dependent Cl(-) channels, since the extent of inhibition by CBD was unaltered by intracellular injection of the Ca(2+) chelator BAPTA and perfusion with Ca(2+)-free bathing solution containing 2mM Ba(2+). Inhibition by CBD was not reversed by increasing ACh concentrations. Furthermore, specific binding of [(125)I] α-bungarotoxin was not inhibited by CBD (10 µM) in oocytes membranes. Using whole cell patch clamp technique in CA1 stratum radiatum interneurons of rat hippocampal slices, currents induced by choline, a selective-agonist of α7-receptor induced currents were also recoded. Bath application of CBD (10 µM) for 10 min caused a significant inhibition of choline induced currents. Finally, in hippocampal slices, [(3)H] norepinephrine release evoked by nicotine (30 µM) was also inhibited by 10 µM CBD. Our results indicate that CBD inhibits the function of the α7-nACh receptor.

Menthol binding and inhibition of α7-nicotinic acetylcholine receptors

Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α₇ subunit of the nicotinic acetylcholine (nACh) receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca²⁺-dependent Cl⁻ channels, since menthol inhibition remained unchanged by intracellular injection of the Ca²⁺ chelator BAPTA and perfusion with Ca²⁺-free bathing solution containing Ba²⁺. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [¹²⁵I] α-bungarotoxin was not attenuated by menthol. Studies of α₇- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α₇ mediated Ca²⁺ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner.

Introduction of an NT-proBNP assay to an acute admission unit--a 2-year audit

BACKGROUND

The differential diagnosis of dyspnoea is difficult due to the low predictive value of clinical and laboratory parameters. The elevated levels of NT-proBNP in congestive heart failure may improve diagnostic accuracy. We have evaluated the effect of the introduction of an NT-proBNP assay on hospital length of stay (LOS) and mortality.

METHODS

There were 11,853 AMAU patient episodes in the 22 months study period (March 2005-Dec 2006). An NT-proBNP assay was requested in 657 (5.5%) of these. Comparison between categorical variables such as diagnosis, NT-proBNP testing, LOS, and in-hospital mortality was made using Chi-square tests. Literature review suggested that an NT-proBNP cut-off >or=5000 ng/L should predict acute in-patient mortality. Logistic regression analysis was used to examine the association between such an elevated NT-proBNP level and outcomes.

RESULTS

Of the 396 patients with NT-proBNP <5000 ng/L, 8.1% died compared with 22.5% of the 178 patients dying with values >or=5000 ng/L (p<0.0001). An NT-proBNP >or=5000 ng/L was predictive of both LOS >or=9 days (odds ratios (OR) 1.54 (95% CI 1.06, 2.24: p=0.02) and LOS >or=14 days (OR=1.87 (95% CI 1.29, 2.71: p=0.0009). NT-proBNP requests increased over time, from 2.6% to 8.2% of all patients; the result fell in the diagnostic range for CHF in 60% of requests.

CONCLUSION

The introduction of an NT-proBNP was reflected in an appropriate but rapidly increasing pattern of requests from clinicians. High NT-proBNP levels predicted in-hospital mortality and longer LOS in an acute medical population.

Safety profile of the intravitreal streptokinase-plasmin complex as an adjunct to vitrectomy in the rabbit

BACKGROUND

The generation of an atraumatic posterior vitreous detachment (PVD), a common goal in vitreoretinal surgery, is a challenge, particularly in children and young trauma patients. Plasmin has been proposed as an adjunct to vitrectomy to enzymatically generate a PVD. Low doses of streptokinase-activated plasmin were tested in human pilot studies. This dose-escalation study assesses the safety range of intravitreal human streptokinase-plasmin in rabbits.

METHODS

Plasminogen was isolated from human plasma by affinity chromatography, followed by activation with streptokinase (1:1), to generate the streptokinase-plasmin complex. Enzyme doses from 0.1-7 activity units (AU, in 0.1 ml) were injected into the mid-vitreous of 35 eyes; six control eyes were injected with balanced salt solution (BSS, 0.1 ml). Thirty minutes after injection, a two-port vitrectomy was performed. Fundus and slit lamp examinations were performed on days 1 and 7. On days 2 and 7, bright flash electroretinography was performed and compared with preoperative recordings. Some animals receiving higher doses of streptokinase-plasmin (1-7 AU) were followed clinically and with electroretinography for up to 9 months.

RESULTS

A mild-to-moderate inflammatory response was seen in both control and plasmin-treated eyes on day 1, but had disappeared completely by day 7 in most eyes. In the 7 AU group, inflammation was stronger and more protracted. Two of three eyes from this group developed wrinkling of the medullary rays; one of them showed discoloration and traction at the medullary rays in the late follow-up. Electroretinograms (ERGs) of vitrectomized control eyes showed the following changes from preoperative values: 48 h, a-wave -11.10% [no significant (n.s.)], b-wave -14.62% (P=0.046); 7 days, a-wave +9.18% (n.s.), b wave +11.69% (n.s.). For the enzyme-treated eyes: 48 h: a-wave -20.43% (P<0.001), b-wave -9.57% (p<0.001); 7 days: a wave -14.21% (P<0.001), b-wave +2.48% (P<0.001). There was no evidence of dose-dependent ERG changes in enzyme-treated eyes at doses up to 5 AU. Groups of up to 3 AU were investigated by light and transmission electron microscopy, without evidence of toxicity.

CONCLUSION

Streptokinase-plasmin doses up to 3 AU were found to be safe when injected into rabbit eyes followed by vitrectomy.

Transient otoacoustic emissions in children with chronic renal failure

This study was conducted on 34 children with chronic renal failure: 27 on regular haemodialysis and seven on conservative treatment. Twenty normal healthy children served as controls. They were subjected to clinical examination including otoscopic examination, basic audiological assessment and transient otoacoustic emission testing (TOAE). Four patients had a conductive hearing loss and five had a bilateral moderately severe high frequency sensory neural hearing loss. TOAE testing was carried out for the rest whose ears displayed normal hearing. No response (fail) was obtained in 8% of them but in none of the controls and a partial pass response in 38% versus 10% of controls (P < 0.001). Cochlear dysfunction was significant only at low frequency levels. The mean overall echo-level and reproducibility were significantly lower in patients than in controls. The same holds true for the subgroup of patients on haemodialysis but not for those on conservative treatment. The overall echo-levels did not correlate with serum urea, creatinine, sodium or potassium.

Non-A, non-B hepatitis in Omdurman, Sudan

One-hundred nineteen patients (cases) at least 13 years of age with acute hepatitis were studied to determine the viral etiology of acute hepatitis in Omdurman, Sudan. Ninety-eight control subjects (controls) were also evaluated to determine the risk factors associated with the development of clinical disease. Acute hepatitis non-A, non-B was diagnosed in 88 cases (73.9%), hepatitis B in 15 cases (12.6%), delta infection in 15 (12.6%), and hepatitis A in just one patient (0.8%). A higher percentage of hepatitis B cases had received a parenteral injection for medical therapy during the previous 6 months than control subjects (26.7% vs 4.1%, p less than 0.05). The data in this study indicate that hepatitis non-a, non-B may be the major cause of acute hepatitis in adults in this area of Sudan. The suggested association of parenteral therapy with the transmission of hepatitis B could have important implications for the spread of other parenterally-transmitted diseases.