The 100K-chaperone protein from adenovirus serotype 2 (Subgroup C) assists in trimerization and nuclear localization of hexons from subgroups C and B adenoviruses

Recombinant hexons from subgroup C adenoviruses (Ad2 and Ad5) and from a member of subgroup B (Ad3) adenoviruses have been expressed in insect cells. When expressed alone, all three hexons were found to be insoluble and accumulated as inclusion bodies in the cytoplasm. However, co-expression of recombinant Ad2, Ad5 or Ad3 hexon with Ad2 L4-100K protein resulted in the formation of soluble trimeric hexons. EM analysis of hexons revealed that they were indistinguishable from native hexon capsomers isolated from Ad2-infected human cells, or released from partially disrupted adenovirions. This suggests that 100K acts as a chaperone for hexon folding and self-assembly into capsomer in insect cells. Since 100K protein assists in the trimerization of subgroup C hexon, and of subgroup B hexon protein, it implies that it functions in a manner that is both homo- and heterotypic. During the course of recombinant protein expression, the 100K protein was found in association with hexon monomers and trimers within the cytoplasm. In the nucleus, however, 100K was found in complexes with hexon trimers exclusively. EM observation of purified 100K protein samples showed a dumb-bell-shaped molecule compatible with a monomeric protein. EM analysis of hexon-100K protein complexes showed that interaction of hexon with the 100K protein occurred via one of the globular domains of the 100K protein molecule. Our data confirm the role of the 100K protein as a scaffold protein for hexon, and provide evidence suggesting its function in hexon nuclear import in insect cells.     

Left ventricular dysfunction following rewarming from experimental hypothermia

This study was aimed at elucidating whetherventricular hypothermia-induced dysfunction persisting after rewarmingthe unsupported in situ dog heart could be characterized as a systolic,diastolic, or combined disturbance. Core temperature of 8 mongrel dogswas gradually lowered to 25°C and returned to 37°C over aperiod of 328 min. Systolic function was described by maximum rate ofincrease in left ventricular (LV) pressure(dP/dt_max),relative segment shortening (SS%), stroke volume (SV), and theload-independent contractility index, preload recruitable stroke work(PRSW). Diastolic function was described by the isovolumic relaxationconstant () and the LV wall stiffness constant(K_p). Comparedwith prehypothermic control, a significant decrease in LV functionalvariables was measured at 25°C:dP/dt_max 2,180 ± 158 vs. 760 ± 78 mmHg/s, SS% 20.1 ± 1.2 vs.13.3 ± 1.0%, SV 11.7 ± 0.7 vs. 8.5 ± 0.7 ml, PRSW 90.5 ± 7.7 vs. 29.1 ± 5.9 J/m · 10²,K_p 0.78 ± 0.10 vs. 0.28 ± 0.03 mm¹, and  78.5 ± 3.7 vs. 25.8 ± 1.6 ms. After rewarming, the significant depression ofLV systolic variables observed at 25°C persisted: dP/dt_max 1,241 ± 108 mmHg/s, SS% 10.2 ± 0.8 J, SV 7.3 ± 0.4 ml, and PRSW52.1 ± 3.6 m · 10², whereasthe diastolic values ofK_p and  returned to control. Thus hypothermia induced a significant depressionof both systolic and diastolic LV variables. After rewarming, diastolicLV function was restored, in contrast to the persistently depressed LVsystolic function. These observations indicate that cooling inducesmore long-lasting effects on the excitation-contraction coupling and the actin-myosin interaction than on sarcoplasmicreticulum Ca²⁺trapping dysfunction or interstitial fluid content, makingposthypothermic LV dysfunction a systolic perturbation.

     

X-Chromosomal Maternal and Fetal SNPs and the Risk of Spontaneous Preterm Delivery in a Danish/Norwegian Genome-Wide Association Study

Background

Recent epidemiological studies suggest that the maternal genome is an important contributor to spontaneous preterm delivery (PTD). There is also a significant excess of males among preterm born infants, which may imply an X-linked mode of inheritance for a subset of cases. To explore this, we examined the effect of maternal and fetal X-chromosomal single nucleotide polymorphisms (SNPs) on the risk of PTD in two independent genome-wide association studies and one replication study.

Methods

Participants were recruited from the Danish National Birth Cohort and the Norwegian Mother and Child cohort studies. Data from these two populations were first analyzed independently, and then combined in a meta-analysis. Overall, we evaluated 12,211 SNPs in 1,535 case-mother dyads and 1,487 control-mother dyads. Analyses were done using a hybrid design that combines case-mother dyads and control-mother dyads, as implemented in the Haplin statistical software package. A sex-stratified analysis was performed for the fetal SNPs. In the replication study, 10 maternal and 16 fetal SNPs were analyzed using case-parent triads from independent studies of PTD in the United States, Argentina and Denmark.

Results

In the meta-analysis, the G allele at the maternal SNP rs2747022 in the FERM domain containing 7 gene (FRMD7) increased the risk of spontaneous PTD by 1.2 (95% confidence interval (CI): 1.1, 1.4). Although an association with this SNP was confirmed in the replication study, it was no longer statistically significant after a Bonferroni correction for multiple testing.

Conclusion

We did not find strong evidence in our data to implicate X-chromosomal SNPs in the etiology of spontaneous PTD. Although non-significant after correction for multiple testing, the mother’s G allele at rs2747022 in FRMD7 increased the risk of spontaneous PTD across all populations in this study, thus warranting further investigation in other populations.     

Effects of Leaf Shape and Boundary Layer Thickness on Photosynthesis in Cotton (Gossypium hirsutum)

In upland cotton (Gossypium hirsutum L.) certain varieties are available with the mutant character “okra” leaves. These deeply lobed leaves were found to have thinner boundary layers than their normal analogues. Apparent photosynthesis and transpiration measurements were made in field-grown stands under a variety of light intensities and carbon dioxide levels to assess the effect of leaf boundary layer diffusion resistance on photosynthetic efficiency. The thinner boundary layers associated with deeply lobed “okra” cotton failed to euhance carbon fixation rates per unit land area. It was concluded that the leaf boundary layer resistance under field conditions is small compared with the total CO₂ diffusion resistance.     

Bacteria of the <Emphasis Type="Italic">Burkholderia cepacia</Emphasis> complex are cyanogenic under biofilm and colonial growth conditions

Background  

The Burkholderia cepacia complex (Bcc) is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. Pseudomonas aeruginosa is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN), a potent inhibitor of cellular respiration. We have recently shown that HCN production by P. aeruginosa may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN.     

Repeated post-exercise administration with a mixture of leucine and glucose alters the plasma amino acid profile in Standardbred trotters

Background  

The branched chain amino acid leucine is a potent stimulator of insulin secretion. Used in combination with glucose it can increase the insulin response and the post exercise re-synthesis of glycogen in man. Decreased plasma amino acid concentrations have been reported after intravenous or per oral administration of leucine in man as well as after a single per oral dose in horses. In man, a negative correlation between the insulin response and the concentrations of isoleucine, valine and methionine have been shown but results from horses are lacking. This study aims to determine the effect of repeated per oral administration with a mixture of glucose and leucine on the free amino acid profile and the insulin response in horses after glycogen-depleting exercise.     

Left sided ablation for Atrioventricular Nodal Re-entrant Tachycardia: Frequency,Characteristics and Outcomes

BackgroundLeft-sided ablation, targeting left inferior AV nodal extensions, is thought to be necessary for success in a small proportion of atrioventricular nodal re-entrant tachycardia (AVNRT) ablations; however Indian data are scarce in this regard.MethodsConsecutive cases of AVNRT undergoing slow pathway ablation in a single centre over an 18-month period were retrospectively analyzed. Left-sided ablation at the posteroseptal mitral annulus was performed if right-sided ablation failed to abolish AVNRT.ResultsFrom January 2017 to June 2018, out of 215 consecutive supraventricular tachycardia (SVT) cases, 154 (71.6%) were AVNRT (47.1 ± 13.1 years, 46.1% male). Trans-septal ablation was required in 5 (3.2%) cases (mean age 48.8 ± 9.4 years; 4 female, 1 male); all with typical (slow-fast) form of AVNRT. Compared with cases needing only right-sided ablation, radiofrequency time (50.8 ± 16.9 vs. 9.9 ± 8.5 min; p = 0.005) and procedure time (166.0 ± 35.0 vs 79.6 ± 35.9 min; p = 0.004) were significantly longer for trans-septal cases, while baseline intervals and tachycardia cycle length were not significantly different. Junctional ectopy was seen in only 2 of the 5 cases during left-sided ablation, but acute success (non-inducibility) was obtained in 3 cases. There were no instances of AV block. Over mean follow-up of 12.2 ± 4.0 months, clinical recurrence of AVNRT occurred in one case, while others remained arrhythmia-free without medication.ConclusionLeft-sided ablation was required in a small proportion of AVNRT ablations. Trans-septal approach targeting the posteroseptal mitral annulus was safe and yielded good mid-term clinical success.