Virtual and solution conformations of oligosaccharides

The possibility that observed nuclear Overhauser enhancements and bulk longitudinal relaxation times, parameters measured by 1H NMR and often employed in determining the preferred solution conformation of biologically important molecules, are the result of averaging over many conformational states is quantitatively evaluated. Of particular interest was to ascertain whether certain 1H NMR determined conformations are "virtual" in nature; i.e., the fraction of the population of molecules actually found at any time within the subset of conformational space defined as the "solution conformation" is vanishingly small. A statistical mechanics approach was utilized to calculate an ensemble average relaxation matrix from which (NOE)'s and (T1)'s are calculated. Model glycosidic linkages in four oligosaccharides were studied. The solution conformation at any glycosidic linkage is properly represented by a normalized, Boltzmann distribution of conformers generated from an appropriate potential energy surface. The nature of the resultant population distributions is such that 50% of the molecular population is found within 1% of available microstates, while 99% of the molecular population occupies about 10% of the ensemble microstates, a number roughly equal to that sterically allowed. From this analysis we conclude that in many cases quantitative interpretation of NMR relaxation data, which attempts to define a single set of allowable torsion angle values consistent with the observed data, will lead to solution conformations that are either virtual or reflect torsion angle values possessed by a minority of the molecular population. On the other hand, calculation of ensemble average NMR relaxation data yields values in agreement with experimental results. Observed values of NMR relaxation data are the result of the complex interdependence of the population distribution and NOE (or T1) surfaces in conformational space. In conformational analyses, NMR data can therefore be used to test different population distributions calculated from empirical potential energy functions.     

Radio Telemetry of the Electrocardiogram,Fitness Tests,and Oxygen Uptake of Water-Polo Players

During competitive water polo, heart rate in six subjects was monitored by cupped plastic and silver electrodes glued to the skin. Minimum rates during the game averaged 156 beats/min.; maximum rates averaged 186 beats/min. Mean maximum rate with bicycle exercise was 188 beats/min. Maximum oxygen (VO₂ max.) with bicycle exercise of 14 water-polo players was 53.3 ml./kg. Physical working capacity (PWC 170) was 1310 kilopond metres per square metre (k.p.m./sq.m.). PWC 170 correlated well with VO₂ max. in this small group (r = 0.77).Oxygen uptake was measured at three speeds of swimming and four levels of work on a bicycle ergometer. VO₂ max. of swimming was 88% of that obtained on bicycle exercise. The slope of the oxygen uptake vs. pulse rate curves was less for the swimming than for cycling, so that for a given oxygen uptake below the maximal, pulse rate was less in the swimmers. At near-maximal swimming, respiratory quotient was 0.95 compared with 1.27 for cycling, suggesting that the swimmers were underbreathing.     

Genetics of formamidase-5 (brain formamidase) in the mouse: Localization of the structural gene on chromosome 14

A single formamidase, which is different from the formamidases found in other tissues, occurs in the brains of mice. This enzyme is here called formamidase-5 and the gene symbol is designated For-5. Two alleles are recognized on the basis of their differential heat sensitivity: For-5 ^b is relatively heat stable and is present in strain C57BL/6J, while For-5 ^d is relatively heat sensitive and is present in strain DBA/2J. The heat sensitivity of formamidase-5 in 44 other inbred strains and substrains was tested and found to resemble that of C57BL/6J or DBA/2J. Thirty-six recombinant inbred strains derived from progenitors that differed at For-5 were studied to test for single-gene inheritance and linkage with other loci. Complete concordance was found with the esterase-10 locus (Es-10), indicating close linkage. The 99% upper confidence limit of the distance between For-5 and Es-10 is 3.7 centimorgans (cM). Es-10 is located on chromosome 14 about 19 cM from the centromere. An independent demonstration of linkage of For-5 with Es-10 and another chromosome 14 marker, hairless (hr), is provided by the finding that the HRS/J strain, which has been sibmated for 60 generations with forced heterozygosity at the hr locus, is cosegregating at For-5 and Es-10. A survey of 32 inbred strains and substrains revealed that the For-5 ^d allele is associated with the Es-10 ^b allele, and that the For-5 ^b allele is associated with Es-10 ^a and Es-10 ^c. Formamidase-5 segregates as expected in the F₂ generation of crosses between strains bearing For-5 ^b and For-5 ^d alleles. It is possible that this unique formamidase of the brain is involved in the metabolism of a neurotransmitter substance.This research was sponsored in part by the Department of Energy under contract with the Union Carbide Corporation and in part by NIH Research Grant GM-18684 from the National Institute of General Medical Sciences. J. C. F. is a predoctoral Fellow supported by Grant CA 09104 from the National Cancer Institute. The Biology Division of Oak Ridge National Laboratory and the Jackson Laboratory are fully accredited by the American Association for Accreditation of Laboratory Animal Care.     

Excess smoking in malignant-phase hypertension

The smoking habits of 82 patients with malignant-phase hypertension were compared with those of subjects in three control groups matched for age and sex. Sixty-seven (82%) of the patients with malignant-phase hypertension were smokers compared with 41 (50%) and 71 (43%) of the patients in two control groups with non-malignant hypertension, and 43 people (52%) in a general population survey. The excess of smokers in the malignant-phase group was significant for men and women, together and separately, for cigarette smoking alone, and for all forms of smoking. There were no significant differences between the control groups. The chance of a hypertensive patient who smoked having the malignant phase was five times that of a hypertensive patient who did not. Twelve patients in the malignant-phase group had never smoked. All were alive three and a half years on average after presentation (range 11 months to seven years). Twenty-four (36%) of the smokers with malignant-phase hypertension died during the same period. The mortality rate was significantly higher among patients with renal failure, as was the prevalence of smoking. Eighteen patients with malignant-phase hypertension had a serum creatinine concentration higher than 250 μmol/l (2·8 mg/100 ml); 17 were smokers and one an ex-smoker. Eleven of these 18 patients died.It is concluded that hypertensive patients who smoke are much more likely to develop the malignant phase than those who do not, and that once the condition has developed it follows a particularly lethal course in smokers.     

SARS-CoV-2 seropositivity and COVID-19 among 5 years-old Amazonian children and their association with poverty and food insecurity

BackgroundThe epidemiology of childhood SARS-CoV-2 infection and COVID-19-related illness remains little studied in high-transmission tropical settings, partly due to the less severe clinical manifestations typically developed by children and the limited availability of diagnostic tests. To address this knowledge gap, we investigate the prevalence and predictors of SARS-CoV-2 infection (either symptomatic or not) and disease in 5 years-old Amazonian children.Methodology/Principal findingsWe retrospectively estimated SARS-CoV-2 attack rates and the proportion of infections leading to COVID-19-related illness among 660 participants in a population-based birth cohort study in the Juruá Valley, Amazonian Brazil. Children were physically examined, tested for SARS-CoV-2 IgG and IgM antibodies, and had a comprehensive health questionnaire administered during a follow-up visit at the age of 5 years carried out in January or June-July 2021. We found serological evidence of past SARS-CoV-2 infection in 297 (45.0%; 95% confidence interval [CI], 41.2–48.9%) of 660 cohort participants, but only 15 (5.1%; 95% CI, 2.9–8.2%) seropositive children had a prior medical diagnosis of COVID-19 reported by their mothers or guardians. The period prevalence of clinically apparent COVID-19, defined as the presence of specific antibodies plus one or more clinical symptoms suggestive of COVID-19 (cough, shortness of breath, and loss of taste or smell) reported by their mothers or guardians since the pandemic onset, was estimated at 7.3% (95% CI, 5.4–9.5%). Importantly, children from the poorest households and those with less educated mothers were significantly more likely to be seropositive, after controlling for potential confounders by mixed-effects multiple Poisson regression analysis. Likewise, the period prevalence of COVID-19 was 1.8-fold (95%, CI 1.2–2.6-fold) higher among cohort participants exposed to food insecurity and 3.0-fold (95% CI, 2.8–3.5-fold) higher among those born to non-White mothers. Finally, children exposed to household and family contacts who had COVID-19 were at an increased risk of being SARS-CoV-2 seropositive and–even more markedly–of having had clinically apparent COVID-19 by the age of 5 years.Conclusions/SignificanceChildhood SARS-CoV-2 infection and COVID-19-associated illness are substantially underdiagnosed and underreported in the Amazon. Children in the most socioeconomically vulnerable households are disproportionately affected by SARS-CoV-2 infection and disease.     

G4-quadruplex-binding proteins: review and insights into selectivity

There are over 700,000 putative G4-quadruplexes (G4Qs) in the human genome, found largely in promoter regions, telomeres, and other regions of high regulation. Growing evidence links their presence to functionality in various cellular processes, where cellular proteins interact with them, either stabilizing and/or anchoring upon them, or unwinding them to allow a process to proceed. Interest in understanding and manipulating the plethora of processes regulated by these G4Qs has spawned a new area of small-molecule binder development, with attempts to mimic and block the associated G4-binding protein (G4BP). Despite the growing interest and focus on these G4Qs, there is limited data (in particular, high-resolution structural information), on the nature of these G4Q-G4BP interactions and what makes a G4BP selective to certain G4Qs, if in fact they are at all. This review summarizes the current literature on G4BPs with regards to their interactions with G4Qs, providing groupings for binding mode, drawing conclusions around commonalities and highlighting information on specific interactions where available.