Estimating kinetic parameters from dynamic contrast-enhanced T(1)-weighted MRI of a diffusable tracer: standardized quantities and symbols

We describe a standard set of quantity names and symbols related to the estimation of kinetic parameters from dynamic contrast-enhanced T(1)-weighted magnetic resonance imaging data, using diffusable agents such as gadopentetate dimeglumine (Gd-DTPA). These include a) the volume transfer constant K(trans) (min(-1)); b) the volume of extravascular extracellular space (EES) per unit volume of tissue v(e) (0 < v(e) < 1); and c) the flux rate constant between EES and plasma k(ep) (min(-1)). The rate constant is the ratio of the transfer constant to the EES (k(ep) = K(trans)/v(e)). Under flow-limited conditions K(trans) equals the blood plasma flow per unit volume of tissue; under permeability-limited conditions K(trans) equals the permeability surface area product per unit volume of tissue. We relate these quantities to previously published work from our groups; our future publications will refer to these standardized terms, and we propose that these be adopted as international standards.

Behavioral disinhibition and the development of substance-use disorders: findings from the Minnesota Twin Family Study

One variant of substance-use disorder is characterized by behavioral disinhibition. In this report, we martial evidence for a model for the development of this variant. We hypothesize that genetic liability for this variant is reflected in a spectrum of risk indicators linked to the inability or unwillingness to inhibit behavioral impulses. Included in this spectrum are personality traits suggesting low constraint, and externalizing psychopathology, including conduct, oppositional defiant, and attention-deficit disorder in children and antisocial personality disorder and behavior in adults. We further hypothesize that these individual differences in behavioral disinhibition are manifestations of underlying central nervous system processes associated with various psychophysiological anomalies, some of which may index genetic risk for substance abuse. Support for the model is derived from the analysis of findings from the Minnesota Twin Family Study, an epidemiological investigation of approximately 2,700 adolescent twins and their parents.

Cardiac T2* magnetic resonance for prediction of cardiac complications in thalassemia major

BACKGROUND

The goal of this study was to determine the predictive value of cardiac T2* magnetic resonance for heart failure and arrhythmia in thalassemia major.

METHODS AND RESULTS

We analyzed cardiac and liver T2* magnetic resonance and serum ferritin in 652 thalassemia major patients from 21 UK centers with 1442 magnetic resonance scans. The relative risk for heart failure with cardiac T2* values <10 ms (compared with >10 ms) was 160 (95% confidence interval, 39 to 653). Heart failure occurred in 47% of patients within 1 year of a cardiac T2* <6 ms with a relative risk of 270 (95% confidence interval, 64 to 1129). The area under the receiver-operating characteristic curve for predicting heart failure was significantly greater for cardiac T2* (0.948) than for liver T2* (0.589; P<0.001) or serum ferritin (0.629; P<0.001). Cardiac T2* was <10 ms in 98% of scans in patients who developed heart failure. The relative risk for arrhythmia with cardiac T2* values <20 ms (compared with >20 ms) was 4.6 (95% confidence interval, 2.66 to 7.95). Arrhythmia occurred in 14% of patients within 1 year of a cardiac T2* of <6 ms. The area under the receiver-operating characteristic curve for predicting arrhythmia was significantly greater for cardiac T2* (0.747) than for liver T2* (0.514; P<0.001) or serum ferritin (0.518; P<0.001). The cardiac T2* was <20 ms in 83% of scans in patients who developed arrhythmia.

CONCLUSIONS

Cardiac T2* magnetic resonance identifies patients at high risk of heart failure and arrhythmia from myocardial siderosis in thalassemia major and is superior to serum ferritin and liver iron. Using cardiac T2* for the early identification and treatment of patients at risk is a logical means of reducing the high burden of cardiac mortality in myocardial siderosis. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00520559.

Stromal estrogen receptors mediate mitogenic effects of estradiol on uterine epithelium

Estradiol-17beta (E2) acts through the estrogen receptor (ER) to regulate uterine growth and functional differentiation. To determine whether E2 elicits epithelial mitogenesis through epithelial ER versus indirectly via ER-positive stromal cells, uteri from adult ER-deficient ER knockout (ko) mice and neonatal ER-positive wild-type (wt) BALB/c mice were used to produce the following tissue recombinants containing ER in epithelium (E) and/or stroma (S), or lacking ER altogether: wt-S + wt-E, wt-S + ko-E, ko-S + ko-E, and ko-S + wt-E. Tissue recombinants were grown for 4 weeks as subrenal capsule grafts in intact female nude mice, then the hosts were treated with either E2 or oil a week after ovariectomy. Epithelial labeling index and ER expression were determined by [3H]thymidine autoradiography and immunohistochemistry, respectively. In tissue recombinants containing wt-S (wt-S + wt-E, wt-S + ko-E), E2 induced a similar large increase in epithelial labeling index compared with oil-treated controls in both types of tissue recombinants despite the absence of epithelial ER in wt-S + ko-E tissue recombinants. This proliferative effect was blocked by an ER antagonist, indicating it was mediated through ER. In contrast, in tissue recombinants prepared with ko-S (ko-S + ko-E and ko-S + wt-E), epithelial labeling index was low and not stimulated by E2 despite epithelial ER expression in ko-S + wt-E grafts. In conclusion, these data demonstrate that epithelial ER is neither necessary nor sufficient for E2-induced uterine epithelial proliferation. Instead, E2 induction of epithelial proliferation appears to be a paracrine event mediated by ER-positive stroma. These data in the uterus and similar studies in the prostate suggest that epithelial mitogenesis in both estrogen and androgen target organs are stromally mediated events.

The 6-min walk distance: change over time and value as a predictor of survival in severe COPD

The 6-min walk distance (6MWD) is used to evaluate the functional capacity of patients with chronic obstructive pulmonary disease (COPD). The change in 6MWD over time and its correlation with changes in spirometry and survival are unclear. Patients (n=198) with severe COPD and 41 age-matched controls were followed for 2 yrs, and anthropometrics, spirometry, 6MWD and comorbidities were measured. The 6MWD decreased in the COPD group from 238 +/- 107 m to 218 +/- 112 m (-26 +/- 37 m x yr(-1)), and increased in the control group from 532 +/- 82 m to 549 +/- 86 m (12 +/- 25 m x yr(-1)). In both groups, there was a poor correlation with changes in forced expiratory volume in one second (FEV1). Nonsurvivors in the COPD group (42%) had a more pronounced change in the 6MWD (-40 versus -22 m x yr(-1)) but a similar change in FEV1 (118 versus 102 mL x yr(-1)). The 6MWD independently predicted survival, after accounting for age, body mass index, FEV1 and comorbidities. In severe chronic obstructive pulmonary disease, the 6-min walk distance predicts mortality better than other traditional markers of disease severity. Its measurement is useful in the comprehensive evaluation of patients with severe disease.

Initiation of replication of the human hepatitis delta virus genome from cloned DNA: role of delta antigen

Beginning with three partial cDNA clones of the RNA genome of human hepatitis delta virus (HDV), we assembled the complete 1,679-base sequence on a single molecule and then inserted a trimer of this into plasmid pSLV, a simian virus 40-based eucaryotic expression vector. This construct was used to transfect both monkey kidney (COS7) and human hepatocellular carcinoma (HuH7) cell lines. In this way we obtained replication of the HDV RNA genome and the appearance, in the nucleoli, of the delta antigen, the only known virus-coded protein. This proved both that the HDV genome could replicate in nonliver as well as liver cells and that there was no requirement for the presence of hepatitis B virus sequences or proteins. When the pSVL construct was made with a dimer of an HDV sequence with a 2-base-pair deletion in the open reading frame, genome replication was reduced at least 40-fold. However, when we cotransfected with a plasmid that expressed the correct delta antigen, the mutated dimer achieved a level of genome replication comparable to that of the nonmutated sequence. We thus conclude that the delta antigen can act in trans and is essential for replication of the HDV genome.

Structural asymmetries in the human brain: a voxel-based statistical analysis of 142 MRI scans

The use of computational approaches in the analysis of high resolution magnetic resonance images (MRI) of the human brain provides a powerful tool for in vivo studies of brain anatomy. Here, we report results obtained with a voxel-wise statistical analysis of hemispheric asymmetries in regional 'amounts' of gray matter, based on MRI scans obtained in 142 healthy young adults. Firstly, the voxel-wise analysis detected the well-known frontal (right > left) and occipital (left > right) petalias. Secondly, our analysis confirmed the presence of left-greater-than-right asymmetries in several posterior language areas, including the planum temporale and the angular gyrus; no significant asymmetry was detected in the anterior language regions. We also found previously described asymmetries in the cingulate sulcus (right > left) and the caudate nucleus (right > left). Finally, in some brain regions we observed highly significant asymmetries that were not reported before, such as in the anterior insular cortex (right > left). The above asymmetries were observed in men and women. Our results thus provide confirmation of the known structural asymmetries in the human brain as well as new findings that may stimulate further research of hemispheric specialization.

NYVAC: a highly attenuated strain of vaccinia virus

A highly attenuated vaccinia virus strain, NYVAC (vP866), was derived from a plaque-cloned isolate of the Copenhagen vaccine strain by the precise deletion of 18 open reading frames (ORFs) from the viral genome. Among the ORFs deleted from NYVAC (vP866) are two genes involved in nucleotide metabolism, the thymidine kinase (ORF J2R) and the large subunit of the ribonucleotide reductase (ORF I4L); the gene encoding the viral hemagglutinin (ORF A56R); the remnant (ORF A26L) of a highly expressed gene responsible for the formation of A-type inclusion bodies; the disrupted gene (ORFs B13R/B14R) normally encoding a serine protease inhibitor; and a block of 12 ORFs bounded by two known viral host range regulatory functions (ORFs C7L through K1L). Within this block a secretory protein (ORF N1L) implicated in viral virulence and a functional complement 4b binding protein (ORF C3L) are encoded. The ORFs were deleted in a manner which prevents the synthesis of undesirable novel gene products. The attenuation characteristics of the derived NYVAC strain were compared in in vitro and in vivo studies with those of the Western Reserve (WR) laboratory strain, the New York City Board of Health vaccine strain (Wyeth), the parental plaque-cloned isolate (VC-2) of the Copenhagen vaccine strain used to derive NYVAC, and the avipox virus canarypox (ALVAC), which is naturally restricted for replication to avian species. The NYVAC strain was demonstrated to be highly attenuated by the following criteria: (a) no detectable induration or ulceration at the site of inoculation on rabbit skin; (b) rapid clearance of infectious virus from the intradermal site of inoculation on rabbit skin; (c) absence of testicular inflammation in nude mice; (d) greatly reduced virulence as demonstrated by the results of intracranial challenge of both 3-week-old or newborn mice; (e) greatly reduced pathogenicity and failure to disseminate in immunodeficient (nude or cyclophosphamide treated) mice; and (f) dramatically reduced ability to replicate on a variety of human tissue culture cells. Despite these highly attenuated characteristics, the NYVAC strain, as a vector, retains the ability to induce strong immune responses to extrinsic antigens.

Antigenomic RNA of human hepatitis delta virus can undergo self-cleavage

The structure and replication of the single-stranded circular RNA genome of hepatitis delta virus (HDV) are unique relative to those of known animal viruses, and yet there are real similarities between HDV and certain infectious RNAs of plants. Therefore, since some of the latter RNAs have been shown to undergo in vitro site-specific cleavage and even ligation, we tested the hypothesis that similar events might also occur for HDV RNA. In partial confirmation of this hypothesis, we found that in vitro the RNA complementary to the HDV genome, the antigenomic RNA, could undergo a self-cleavage that was not only more than 90% efficient but also occurred only at a single location. This cleavage was found to produce junction fragments consistent with a 5'-hydroxyl and a cyclic 2',3'-monophosphate. Since the observed cleavage was both site-specific and occurred only once per genome length, we propose that the site may be relevant to the normal intracellular replication of the HDV genome. Because the site is located almost adjacent to the 3' end of the delta antigen-coding region, the only known functional open reading frame of HDV, we suggest that the cleavage may have a role not only in genome replication but also in RNA processing, helping to produce a functional mRNA for the translation of delta antigen.

Roles of estrogen receptor-alpha gene expression in reproduction-related behaviors in female mice

The role of gene expression of the estrogen receptor-alpha form (ER alpha) in the regulation of female reproductive behavior was investigated in estrogen receptor knockout (ERKO) mice, deficient specifically for the ER alpha, but not the ER beta, gene. Estrogen- or estrogen- plus progesterone-treated gonadectomized ERKO mice did not show any lordosis response. Detailed behavioral analysis revealed that ERKO females were also deficient in sexual behavioral interactions preceding the lordosis response. They were extremely rejective toward attempted mounts by stud male mice, which could not show any intromissions. During resident-intruder aggression tests, gonadally intact ERKO females were more aggressive toward female intruder mice than wild-type (WT) mice. Gonadectomy did not influence the levels of aggressive behavior, and their genotype differences when mice were tested both before and after gonadectomy. However, when mice were tested after gonadectomy for the first time, very few ERKO mice showed aggression. In contrast to aggression, male-type sexual behavior shown by resident mice toward female intruder mice during aggression tests was not different between ERKO and WT mice and was completely abolished after gonadectomy of the resident mice. Finally, it was also found that ERKO females showed greatly reduced levels of parental behavior toward newborn pups placed in their home cage. These changes in parental behavior were not influenced by gonadectomy. ERKO females retrieved significantly fewer numbers of pups with longer latencies compared with wild-type (WT) or heterozygous (HZ) littermates when they were tested as gonadally intact or 20-65 days after gonadectomy. In addition, during parental behavior tests, a significantly higher percentage of ERKO mice exhibited infanticide compared with WT and HZ mice, which rarely showed infanticide. Taken together, these findings suggest that ER alpha gene expression plays a key role in female mice, not only for sexual behavior but also for other interrelated behaviors, such as parental and aggressive behaviors. In addition, persistence of genotype differences in parental and aggressive behavior after gonadectomy indicates that ER alpha activation during neural developmental processes may also be involved in the regulation of these behaviors.

Factors associated with early failure of arteriovenous fistulae for haemodialysis access

The radiocephalic arteriovenous fistula remains the method of choice for haemodialysis access. In order to assess their suitability for fistula formation, the radial arteries and cephalic veins were examined preoperatively by ultrasound colour flow scanner in conjunction with a pulse-generated run-off system. Intraoperative blood flow was measured after construction of the fistulae. Post-operative follow-up was performed at various intervals to monitor the development of the fistulae. Radial artery and cephalic vein diameter less than 1.6 mm was associated with early fistula failure. The intraoperative fistula blood flow did not correlate with the outcome of the operation probably due to vessel spasm from manipulation. However, blood flow velocities measured non-invasively 1 day after the operation were significantly lower in fistulae that failed early compared with those that were adequate for haemodialysis. Most of the increase in fistula diameter and blood flow occur within the first 2 weeks of surgery.

Structure and replication of the genome of the hepatitis delta virus

The hepatitis delta virus can be found in the serum and liver of some hepatitis B virus patients. We now report that the RNA genome of serum-derived delta virus is single-stranded and circular. Livers of infected chimpanzees or woodchucks contained as many as 300,000 copies of genomic strand RNA per average cell, and at least some of this RNA had a circular conformation. Also present in the livers were RNA species complementary to the virion RNA. The genomic RNA was 5-22 times more abundant than this antigenomic strand. Some of the antigenomic RNA was complexed with genomic RNA, as evidenced by the fact that at least 34% of the antigenomic RNA was resistant to digestion with either RNase A in 0.3 M NaCl or S1 nuclease. Some of the antigenomic RNA was in a circular conformation. These and other findings showed that the structure and replication of hepatitis delta virus are in many ways similar to those of the previously described plant viroids, virusoids, and satellite RNAs.

MutS mediates heteroduplex loop formation by a translocation mechanism

Interaction of Escherichia coli MutS and MutL with heteroduplex DNA has been visualized by electron microscopy. In a reaction dependent on ATP hydrolysis, complexes between a MutS dimer and a DNA heteroduplex are converted to protein-stabilized, alpha-shaped loop structures with the mismatch in most cases located within the DNA loop. Loop formation depends on ATP hydrolysis and loop size increases linearly with time at a rate of 370 base pairs/min in phosphate buffer and about 10,000 base pairs/min in the HEPES buffer used for repair assay. These observations suggest a translocation mechanism in which a MutS dimer bound to a mismatch subsequently leaves this site by ATP-dependent tracking or unidimensional movement that is in most cases bidirectional from the mispair. In view of the bidirectional capability of the methyl-directed pathway, this reaction may play a role in determination of heteroduplex orientation. The rate of MutS-mediated DNA loop growth is enhanced by MutL, and when both proteins are present, both are found at the base of alpha-loop structures, and both can remain associated with excision intermediates produced in later stages of the reaction.

Characterization of self-cleaving RNA sequences on the genome and antigenome of human hepatitis delta virus

Recently we reported that in vitro RNA transcripts complementary to the genome of hepatitis delta virus (HDV) contain a unique site at which self-cleavage can occur. Subsequent studies showed that a similar self-cleavage site was present on in vitro RNA transcripts of genomic HDV RNA. The same self-cleavage reactions were also found to occur on HDV RNAs from the livers of infected chimpanzees. Using the in vitro RNA it was also possible to determine that the minimum length of contiguous sequence needed for self-cleavage of genomic RNA was 30 bases 5' and 74 bases 3' of the cleavage site. This sequence was not compatible with the "hammerhead" structure hypothesized to be important in the self-cleavage reactions of other RNAs.

Van Gogh: a new Drosophila tissue polarity gene

Mutations in the Van Gogh gene result in the altered polarity of adult Drosophila cuticular structures. On the wing, Van Gogh mutations cause an altered polarity pattern that is typical of mutations that inactivate the frizzled signaling/signal transduction pathway. The phenotype however, differs from those seen previously, as the number of wing cells forming more than one hair is intermediate between that seen previously for typical frizzled-like or inturned-like mutations. Consistent with Van Gogh being involved in the function of the frizzled signaling/signal transduction pathway, Van Gogh mutations show strong interactions with mutations in frizzled and prickle. Mitotic clones of Van Gogh display domineering cell nonautonomy. In contrast to frizzled clones, Van Gogh clones alter the polarity of cells proximal (and in part anterior and posterior) but not distal to the clone. In further contrast to frizzled clones, Van Gogh clones cause neighboring wild-type hairs to point away from rather than toward the clone. This anti-frizzled type of domineering nonautonomy and the strong genetic interactions seen between frizzled and Van Gogh suggested the possibility that Van Gogh was required for the noncell autonomous function of frizzled. As a test of this possibility we induced frizzled clones in a Van Gogh mutant background and Van Gogh clones in a frizzled mutant background. In both cases the domineering nonautonomy was suppressed consistent with Van Gogh being essential for frizzled signaling.

A randomized trial of acyclovir for 7 days or 21 days with and without prednisolone for treatment of acute herpes zoster

BACKGROUND

Acyclovir given for 7 to 10 days is of proved benefit in acute herpes zoster, but studies of its effectiveness in preventing postherpetic neuralgia have had conflicting results. The role of corticosteroids in the treatment of herpes zoster is also controversial.

METHODS

We conducted a double-blind, controlled trial in patients with acute herpes zoster to determine whether either 21 days of acyclovir therapy or the addition of prednisolone offered any improvement over 7 days of acyclovir therapy. Patients with a rash of less than 72 hours' duration were assigned to receive acyclovir (800 mg orally, five times daily) for 7 days with either prednisolone or placebo, or acyclovir for 21 days with either prednisolone or placebo. Prednisolone therapy was initiated at a dose of 40 mg per day and tapered over a three-week period. Patients were assessed frequently through day 28 and then monthly through month 6 to assess postherpetic neuralgia.

RESULTS

Of 400 patients recruited, 349 completed the study. No significant differences were detected between the four groups in the progression of the rash (P > 0.1). With steroid therapy, a significantly higher proportion of the rash area had healed on days 7 and 14 (P = 0.02). Pain reduction was greater during the acute phase of disease in patients treated with steroids or 21 days of acyclovir (P < 0.01 and P = 0.02, respectively, on day 7; P < 0.01 for steroid therapy on day 14). However, on follow-up there were no significant differences between any of the groups in the time to a first or a complete cessation of pain. The steroid recipients reported more adverse events.

CONCLUSIONS

In acute herpes zoster, treatment with acyclovir for 21 days or the addition of prednisolone to acyclovir therapy confers only slight benefits over standard 7-day treatment with acyclovir. Neither additional treatment reduces the frequency of postherpetic neuralgia.

Risks of young age for selected neurocognitive deficits in medulloblastoma are associated with white matter loss

PURPOSE

To test the hypothesis that inadequate development of normal-appearing white matter (NAWM) is associated with the relationship between young age at the time of craniospinal irradiation (CRT) and deficient neurocognitive performance in survivors of childhood medulloblastoma.

PATIENTS AND METHODS

Forty-two patients treated since 1985 participated in this cross-sectional study. All had been treated with CRT with or without chemotherapy and had survived 1 or more years after treatment. Neurocognitive evaluations were conducted with tests of intellect (intelligent quotient; IQ), verbal memory, and sustained attention. Quantitative magnetic resonance imaging, using a hybrid neural network, assessed the volume of NAWM.

RESULTS

Neurocognitive test results were below normal expectations for age at the time of testing. A young age at CRT was significantly associated with worse performance on all neurocognitive tests except that of verbal memory. An increased time from completion of CRT was significantly associated with worse performance on all neurocognitive tests except that of sustained attention. After statistically controlling for the effects of time from CRT, we examined the association of NAWM with neurocognitive test results. These analyses revealed that NAWM accounted for a significant amount of the association between age at CRT and IQ, factual knowledge, and verbal and nonverbal thinking, but not sustained attention or verbal memory.

CONCLUSION

The present results suggest that, at least for some cognitive functions, deficient development and/or loss of NAWM after CRT may provide a neuroanatomical substrate for the adverse impact of a young age at the time of CRT.

Human estrogen receptor beta binds DNA in a manner similar to and dimerizes with estrogen receptor alpha

The cloning of a novel estrogen receptor beta (denoted ERbeta) has recently been described (Kuiper, G. G. J. M., Enmark, E., Pelto-Huikko, M., Nilsson, S., and Gustafsson, J-A. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 5925-5930 and Mosselman, S., Polman, J. , and Dijkema, R. (1996) FEBS Lett. 392, 49-53). ERbeta is highly homologous to the "classical" estrogen receptor alpha (here referred to as ERalpha), has been shown to bind estrogens with an affinity similar to that of ERalpha, and activates expression of reporter genes containing estrogen response elements in an estrogen-dependent manner. Here we describe functional studies comparing the DNA binding abilities of human ERalpha and beta in gel shift assays. We show that DNA binding by ERalpha and beta are similarly affected by elevated temperature in the absence of ligand or in the presence of 17beta-estradiol and the partial estrogen agonist 4-hydroxy-tamoxifen. In the absence of ligand, DNA binding by ERalpha and beta is rapidly lost at 37 degrees C, while in the presence of 17beta-estradiol and 4-hydroxy-tamoxifen, the loss in DNA binding at elevated temperature is much more gradual. We show that the loss in DNA binding is not due to degradation of the receptor proteins. However, while the complete antagonist ICI 182, 780 does not "protect" human ERalpha (hERalpha) from loss of DNA binding at elevated temperature in vitro, it does appear to protect human ERbeta (hERbeta), suggestive of differences in the way ICI 182, 780 acts on hERalpha and beta. We further report that ERalpha and beta can dimerize with each other, the DNA binding domain of hERalpha being sufficient for dimerization with hERbeta. Cell and promoter-specific transcription activation by ERalpha has been shown to be dependent on the differential action of the N- and C-terminal transcription activation functions AF-1 and AF-2, respectively. The existence of a second estrogen receptor gene and the dimerization of ERalpha and beta add greater levels of complexity to transcription activation in response to estrogens.

Clinical characteristics with inflammation profiling of long COVID and association with 1-year recovery following hospitalisation in the UK: a prospective observational study

BACKGROUND

No effective pharmacological or non-pharmacological interventions exist for patients with long COVID. We aimed to describe recovery 1 year after hospital discharge for COVID-19, identify factors associated with patient-perceived recovery, and identify potential therapeutic targets by describing the underlying inflammatory profiles of the previously described recovery clusters at 5 months after hospital discharge.

METHODS

The Post-hospitalisation COVID-19 study (PHOSP-COVID) is a prospective, longitudinal cohort study recruiting adults (aged ≥18 years) discharged from hospital with COVID-19 across the UK. Recovery was assessed using patient-reported outcome measures, physical performance, and organ function at 5 months and 1 year after hospital discharge, and stratified by both patient-perceived recovery and recovery cluster. Hierarchical logistic regression modelling was performed for patient-perceived recovery at 1 year. Cluster analysis was done using the clustering large applications k-medoids approach using clinical outcomes at 5 months. Inflammatory protein profiling was analysed from plasma at the 5-month visit. This study is registered on the ISRCTN Registry, ISRCTN10980107, and recruitment is ongoing.

FINDINGS

2320 participants discharged from hospital between March 7, 2020, and April 18, 2021, were assessed at 5 months after discharge and 807 (32·7%) participants completed both the 5-month and 1-year visits. 279 (35·6%) of these 807 patients were women and 505 (64·4%) were men, with a mean age of 58·7 (SD 12·5) years, and 224 (27·8%) had received invasive mechanical ventilation (WHO class 7-9). The proportion of patients reporting full recovery was unchanged between 5 months (501 [25·5%] of 1965) and 1 year (232 [28·9%] of 804). Factors associated with being less likely to report full recovery at 1 year were female sex (odds ratio 0·68 [95% CI 0·46-0·99]), obesity (0·50 [0·34-0·74]) and invasive mechanical ventilation (0·42 [0·23-0·76]). Cluster analysis (n=1636) corroborated the previously reported four clusters: very severe, severe, moderate with cognitive impairment, and mild, relating to the severity of physical health, mental health, and cognitive impairment at 5 months. We found increased inflammatory mediators of tissue damage and repair in both the very severe and the moderate with cognitive impairment clusters compared with the mild cluster, including IL-6 concentration, which was increased in both comparisons (n=626 participants). We found a substantial deficit in median EQ-5D-5L utility index from before COVID-19 (retrospective assessment; 0·88 [IQR 0·74-1·00]), at 5 months (0·74 [0·64-0·88]) to 1 year (0·75 [0·62-0·88]), with minimal improvements across all outcome measures at 1 year after discharge in the whole cohort and within each of the four clusters.

INTERPRETATION

The sequelae of a hospital admission with COVID-19 were substantial 1 year after discharge across a range of health domains, with the minority in our cohort feeling fully recovered. Patient-perceived health-related quality of life was reduced at 1 year compared with before hospital admission. Systematic inflammation and obesity are potential treatable traits that warrant further investigation in clinical trials.

FUNDING

UK Research and Innovation and National Institute for Health Research.

Molecular cloning of hepatitis delta virus RNA from an infected woodchuck liver: sequence, structure, and applications

cDNA prepared from the single-stranded circular RNA genome of hepatitis delta virus was cloned in lambda gt11 by using RNA from the liver of an infected woodchuck. From the sequence of overlapping clones, we assembled the full sequence of 1,679 nucleotides. The sequence indicated an exceptional ability for intramolecular base pairing, yielding a rod structure with at least 70% of the bases paired and a predicted free energy of -805 kcal (-3,368 kJ)/mol. Three of the lambda clones contained sequences that were not only expressed as fusion proteins with beta-galactosidase but were recognized by human hepatitis delta virus-specific antibody. These clones were sequenced so as to establish the reading frame of the delta antigen on the antigenomic strand. The fusion protein produced by one clone was purified by immunoaffinity chromatography and then was used to raise rabbit antibodies specific for the delta antigen.

A specific base transition occurs on replicating hepatitis delta virus RNA

Three independent lines of evidence showed that when an infectious clone of hepatitis delta virus of known sequence was used to initiate genome replication, up to 41% of the genomes were specifically mutated in the amber termination codon (UAG to UGG) for the open reading frame of the delta antigen, thereby increasing the length of the predicted protein from 195 to 214 amino acids. This change was detected only on molecules that participated in RNA-directed RNA synthesis.

Modifications of testosterone-dependent behaviors by estrogen receptor-alpha gene disruption in male mice

The role of the a form of estrogen receptor (ER alpha) gene expression in the regulation of testosterone-dependent male reproductive behaviors was investigated using ER knockout mice (ERKO), which are specifically deficient in functional ER alpha, but not ER beta, gene expression. Previous studies in gonadally intact ERKO mice revealed that male aggressive behavior was greatly reduced by the lack of a functional ER alpha gene. In the present study the almost complete suppression of male-typical offensive attacks was further confirmed in ERKO mice that had been singly housed since weaning. Regarding aggression, it was also found that ER alpha gene disruption virtually abolished the propensity to initiate offensive attacks, even though ERKO mice could elicit attacks from resident C57BL/6J mice as wild-type (WT) and heterozygous littermates. Daily injection of testosterone propionate (TP) was completely ineffective in inducing aggressive behavior in gonadectomized ERKO mice, whereas it successfully restored aggression in WT mice. In contrast, male sexual behaviors, mounts and intromissions, were induced by daily injection of TP in both gonadectomized ERKO and WT mice. In addition to TP, dihydrotestosterone propionate (DHTP) was also effective in restoring mounts in ERKO mice, although DHTP was much more potent in WT mice than in ERKO mice. Neither TP nor DHTP, however, ever induced ejaculation in ERKO mice. These results together with previous findings in gonadally intact ERKO mice suggest that ER alpha may be responsible for the regulation by testosterone of consummatory, but not motivational, aspects of male sexual behavior. Finally, ERKO male mice retrieved newborn pups placed in their home cage with similar latencies to males of the two other genotypes. During parental behavior tests, however, a higher percentage of ERKO mice (70%) showed infanticide compared with WT mice (35%). The latter result was interpreted as showing that ER alpha activation by testosterone during the perinatal period may exert a suppressive effect on testosterone-inducible infanticide in adulthood. With respect to three major testosterone-dependent behavioral systems reflecting masculinization, these findings demonstrate three different types of effects due to ER alpha gene disruption.

Physiology: does gut hormone PYY3-36 decrease food intake in rodents?

Batterham et al. report that the gut peptide hormone PYY3-36 decreases food intake and body-weight gain in rodents, a discovery that has been heralded as potentially offering a new therapy for obesity. However, we have been unable to replicate their results. Although the reasons for this discrepancy remain undetermined, an effective anti-obesity drug ultimately must produce its effects across a range of situations. The fact that the findings of Batterham et al. cannot easily be replicated calls into question the potential value of an anti-obesity approach that is based on administration of PYY3-36.