Cardiomyocyte ploidy is dynamic during postnatal development and varies across genetic backgrounds.

Somatic polyploidization, an adaptation by which cells increase their DNA content to support growth, is observed in many cell types, including cardiomyocytes. Although polyploidization is believed to be beneficial, progression to a polyploid state is often accompanied by loss of proliferative capacity. Recent work suggests that genetics heavily influence cardiomyocyte ploidy. However, the developmental course by which cardiomyocytes reach their final ploidy state has only been investigated in select backgrounds. Here, we assessed cardiomyocyte number, cell cycle activity, and ploidy dynamics across two divergent mouse strains: C57BL/6J and A/J. Both strains are born and reach adulthood with comparable numbers of cardiomyocytes; however, the end composition of ploidy classes and developmental progression to reach the final state differ substantially. We expand on previous findings that identified Tnni3k as a mediator of cardiomyocyte ploidy and uncover a role for Runx1 in ploidy dynamics and cardiomyocyte cell division, in both developmental and injury contexts. These data provide novel insights into the developmental path to cardiomyocyte polyploidization and challenge the paradigm that hypertrophy is the sole mechanism for growth in the postnatal heart.

Runx1 is sufficient but not required for cardiomyocyte cell-cycle activation.

Factors responsible for cardiomyocyte proliferation could serve as potential therapeutics to stimulate endogenous myocardial regeneration following insult, such as ischemic injury. A previously published forward genetics approach on cardiomyocyte cell cycle and ploidy led us to the transcription factor, Runx1. Here, we examine the effect of Runx1 on cardiomyocyte cell cycle during postnatal development and cardiac regeneration using cardiomyocyte-specific gain- and loss-of-function mouse models. RUNX1 is expressed in cardiomyocytes during early postnatal life, decreases to negligible levels by 3 wk of age, and increases upon myocardial injury, all consistent with observed rates of cardiomyocyte cell-cycle activity. Loss of Runx1 transiently stymied cardiomyocyte cell-cycle activity during normal postnatal development, a result that corrected itself and did not extend to the context of neonatal heart regeneration. On the other hand, cardiomyocyte-specific Runx1 overexpression resulted in an expansion of diploid cardiomyocytes in uninjured hearts and expansion of 4 N cardiomyocytes in the context of neonatal cardiac injury, suggesting Runx1 overexpression is sufficient to induce cardiomyocyte cell-cycle responses. Persistent overexpression of Runx1 for >1 mo continued to promote cardiomyocyte cell-cycle activity resulting in substantial hyperpolyploidization (≥8 N DNA content). This persistent cell-cycle activation was accompanied by ventricular dilation and adverse remodeling, raising the concern that continued cardiomyocyte cell cycling can have detrimental effects.NEW & NOTEWORTHY Runx1 is sufficient but not required for cardiomyocyte cell cycle.

Safe streets for some: A review of local active transportation responses across the U.S. during the COVID-19 pandemic.

Introduction & research objectives: The COVID-19 pandemic significantly disrupted daily travel. This paper contrasts 51 US cities' responses, namely street reallocation criteria and messaging related to physical activity (PA) and active transportation (AT) during the early months of the pandemic. This study can be utilized by cities for aiding in the creation of locally responsive policies that acknowledge and remedy a lack of safe active transportation. Methods: A content analysis review was conducted of city orders and documents related to PA or AT for the largest city by population in all 50 US states and the District of Columbia. Authoritative documents issued from each city's public health declaration (ca. March 2020) to September 2020 were reviewed. The study obtained documents from two crowdsourced datasets and municipal websites. Descriptive statistics were used to compare policies and strategies, with a focus on reallocation of street space. Results: A total of 631 documents were coded. Considerable variation existed in city responses to COVID-19 that impacted PA and AT. Most cities' stay-at-home orders explicitly permitted outdoor PA (63%) and many encouraged PA (47%). As the pandemic continued, 23 cities (45%) had pilot programs that reallocated street space for non-motorized road users to recreate and travel. Most cities explicitly mentioned a rationale for the programs (e.g., to provide space for exercise (96%) and to alleviate crowding or provide safe AT routes (57%)). Cities used public feedback to guide placement decisions (35%) and several welcomed public input to adjust initial actions. Geographic equity was a criterion in 35% of programs and 57% considered inadequately sized infrastructure in decision-making. Conclusions: If cities want to emphasize AT and the health of their citizens, safe access to dedicated infrastructure needs to be prioritized. More than half of study cities did not instate new programs within the first 6 months of the pandemic. Cities should study peer responses and innovations to inform and create locally responsive policies that can acknowledge and remedy a lack of safe AT.

Synovial sarcomas usually metastasize after >5 years: a multicenter retrospective analysis with minimum follow-up of 10 years for survivors.

BACKGROUND: Synovial sarcoma (SS) is a malignant soft tissue sarcoma with a poor prognosis because of late local recurrence and distant metastases. To our knowledge, no studies have minimum follow-up of 10 years that evaluate long-term outcomes for survivors. PATIENTS AND METHODS: Data on 62 patients who had been treated for SS from 1968 to 1999 were studied retrospectively in a multicenter study. Mean follow-up of living patients was 17.2 years and of dead patients 7.7 years. RESULTS: Mean age at diagnosis was 35.4 years (range 6-82 years). Overall survival was 38.7%. The 5-year survival was 74.2%; 10-year survival was 61.2%; and 15-year survival was 46.5%. Fifteen patients (24%) died of disease after 10 years of follow-up. Local recurrence occurred after a mean of 3.6 years (range 0.5-14.9 years) and metastases at a mean of 5.7 years (range 0.5-16.3 years). Only four patients were treated technically correctly with a planned biopsy followed by a wide resection or amputation. Factors associated with significantly worse prognosis included larger tumor size, metastases at the time of diagnosis, high-grade histology, trunk-related disease, and lack of wide resection as primary surgical treatment. CONCLUSIONS: In SS, metastases develop late with high mortality. Patients with SS should be followed for >10 years.

"May the Force Be with You!" Force-Volume Mapping with Atomic Force Microscopy.

Information of the chemical, mechanical, and electrical properties of materials can be obtained using force volume mapping (FVM), a measurement mode of scanning probe microscopy (SPM). Protocols have been developed with FVM for a broad range of materials, including polymers, organic films, inorganic materials, and biological samples. Multiple force measurements are acquired with the FVM mode within a defined 3D volume of the sample to map interactions (i.e., chemical, electrical, or physical) between the probe and the sample. Forces of adhesion, elasticity, stiffness, deformation, chemical binding interactions, viscoelasticity, and electrical properties have all been mapped at the nanoscale with FVM. Subsequently, force maps can be correlated with features of topographic images for identifying certain chemical groups presented at a sample interface. The SPM tip can be coated to investigate-specific reactions; for example, biological interactions can be probed when the tip is coated with biomolecules such as for recognition of ligand-receptor pairs or antigen-antibody interactions. This review highlights the versatility and diverse measurement protocols that have emerged for studies applying FVM for the analysis of material properties at the nanoscale.

[The Legg-Calvé-Perthes disease: which assessment? Which therapeutic approach?]. / L'ostéochondrite primitive de to hanche ou maladie de Legg- Calvé-Perthes: quel bitan ? quelle prise en charge?

Legg-Calvé-Perthes disease remains indefinite from an etiologic point of view and unforeseable in its evolution. The evolution depends on the extent of epiphyseal involvement and the age of the child. It may safely be stated that the more extensive the epiphyseal involvement, the more compromised is the prognosis. Also the older the child, the more the femoral head remoulding will be limited. Preserving articular mobility and containing the head within the depth of acetabulum constitute the mainstay of treatment aiming for a femoral head as spherical as possible upon completion of growth. At the end of growth spherical or ovoid heads will cause no or few problems, however strongly deformed femoral heads will evolve into early hip arthritis. The early recognition of which hip will profit from which treatment, constitutes the major difficulty of the therapeutic process.

Widespread intracranial calcifications in the follow-up of a patient with cartilage-hair hypoplasia--anauxetic dysplasia spectrum disorder: a coincidental finding?

BACKGROUND/PURPOSE: Intracranial calcifications have been identified in many neurological disorders. To our knowledge, however, such findings have not been described in cartilage-hair hypoplasia - anauxetic dysplasia spectrum disorders (CHH-AD), a group of conditions characterized by a wide spectrum of clinical manifestations. METHODS/RESULTS: We report a 22-year old female patient, diagnosed with this disorder during her first year of life, and in whom bilateral intracranial calcifications (frontal lobes, basal ganglia, cerebellar dentate nuclei) were discovered by brain MRI at the age of 17 years. CONCLUSION: The etiology of this finding remains unclear. Some causes of such deposits can be of a reversible nature, thus prompting early recognition although their consequences on clinical outcome remain mostly unknown.

Absence of blocking antibody in non-inhibitor haemophilic plasma.

This study examined the hypothesis that non-inhibitor haemophilic plasma contains antibodies which are specific for sites other than the active procoagulatn site on factor VIII, and that some of them might be sufficiently close to the active site that pre-incubation of such plasma with factor VIII would block the subsequent binding of inhibitor antibody. Among the 26 non-inhibitor plasmas examined, none was found to contain such blocking antibody. This result does not eliminate the possibility that antibody is present in such non-inhibitor plasmas which is neither specific for the active enzyme site of factor VIII nor capable of blocking the binding of antibody which does have that specificity.

Studies on the neutralization of rabbit antibodies to human factor VIII.

The capacity of normal and haemophilic cryoprecipitates to neutralize the anticoagulant effect of rabbit antibodies to human factor VIII (anti-VIII) was assessed using a quantitative estimation of antibody. About 4 times as much anti-VIII could be neutralized by normal factor VIII as was required to neutralize clotting activity. This suggests that there are probably several antigenic sites intimately associated with factor VIII clotting activity, quite apart from any antigenic sites which may be detected using antibodies directed against other components of the factor VIII complex. The neutralizing capacity of factor VIII was only slightly greater for the rabbit antibodies employed in this study than has been previously reported for antibodies of human origin, thus indicating only minor differences in specificities. Additional evidence in support of this concept was the finding that cryoprecipitates prepared from haemophilic plasmas previously recognized as either lacking or possessing the capacity to neutralize antibodies of human origin neutralized least or most quantities of rabbit antibodies, respectively.

A study of monooxygenase activity in human placental homogenates: in vitro behaviour towards a number of substrates and inhibitors.

The in vitro effects of cimetidine, metyrapone, SKF-525A and alpha-naphthoflavone on the monooxygenase activity in human placental tissue have been determined by indirect fluorimetric assay methods in placental homogenates from five maternal smokers. The inhibitor concentrations producing half-maximum inhibition (I50 values) were calculated for the O-deethylation of 7-ethoxycoumarin and 7-ethoxyphenoxazone, and the hydroxylation of 2,5-diphenyloxazole. The results indicate that cimetidine is a weak inhibitor of the placental monooxygenase system, resembling metyrapone and SKF-525A in its effects rather than alpha-naphthoflavone. Characterization of the behaviour of the three substrates towards placental monooxygenase activity indicates a much greater enzymic affinity for 7-ethoxyphenoxazone than for 7-ethoxycoumarin or 2,5-diphenyloxazole.

A survey of aryl hydrocarbon hydroxylase activity in human placental homogenates.

The mono-oxygenase activity in vitro towards 7-ethoxyresorufin (ERR) and 2,5-diphenyloxazole (PPO) was studied in 108 human placental homogenates obtained from mothers who were either smokers (61), non-smokers (44), or epileptics (3). With both substrates the average placental AHH level among smokers was 50 to 60 times greater than the average level in nonsmokers. Some association was found between levels of placental AHH activity and the number of cigarettes smoked per day by the woman concerned: PPO, r = 0.42, P less than 0.01; ERR, r = 0.39, P less than 0.01. In smokers, placental PPO hydroxylase and ERR O-deethylase activities were highly significantly correlated (r = 0.96, P less than 0.001). In non-smokers the low average levels of AHH activity obtained using both substrates were found to be significantly non-zero: PPO, P less than 0.01; ERR, P less than 0.001. No correlation was found, in either smokers or non-smokers, between placental AHH activity and parameters such as age, body weight, diet (including consumption of tea, coffee and alcohol), number of previous pregnancies or placental and baby birth weights. Women who continued smoking during pregnancy but at a reduced rate still maintained fairly high levels of AHH activity. Administration of carbamazepine appeared to cause some enhancement of placental AHH activity. Phenytoin administration, however, had no apparent effect on the level of enzyme activity.

A study of the distribution of 7-ethoxycoumarin O-de-ethylase activity in human placental subcellular fractions.

Human placental homogenates from maternal smokers and non-smokers were fractionated using differential centrifugation techniques. Yields of the various subfractions were determined and their homogeneity assessed using electron microscopic procedures. The distribution and response of 7-ethoxycoumarin O-de-ethylase activity towards inhibition by dimethylsulphoxide, alpha-naphthoflavone and 9-hydroxyellipticine inhibitors in the placental subfractions were investigated. The low yield of microsomal protein obtained following differential centrifugation of placental homogenates (2.5 +/- 0.2 mg protein per g placenta) highlights the extremely refractory nature of human placental tissue towards homogenization. Enzymic studies showed that the majority (75 per cent) of the original O-de-ethylase activity in homogenates from smokers and non-smokers was to be found in the crude nuclear fraction. The 7-ethoxycoumarin O-de-ethylase activity present in both homogenate and crude nuclear preparations from a maternal smoker was found to be inhibited by both alpha-naphthoflavone and 9-hydroxyellipticine to a lesser extent than the O-de-ethylase activity which was present in both mitochondrial and microsomal fractions. While this observation suggests the existence of more than one induced O-de-ethylase activity in the human placenta, the possibility that such differences in inhibitory response may be due to other factors (e.g. inhibitor solubility effects) cannot be excluded. Studies using the above inhibitors also confirmed the results of earlier work by demonstrating that the O-de-ethylase activity in placental homogenates and subfractions from non-smokers is qualitatively different from the O-de-ethylase activities induced as a result of maternal smoking.

Influence of parental age on degree of curvature in idiopathic scoliosis.

One hundred and seventy-seven patients who had adolescent idiopathic scoliosis were followed from the time of the initial evaluation to skeletal maturity or arthrodesis. At that time, we analyzed the degree of curvature to determine if it was related to parental age at the time of the patient's birth. Patients who were born to mothers who were twenty-seven years old or more had a mean curve of 35.2 degrees, which was significantly greater (p = 0.02) than that of patients whose mothers were younger than twenty-seven years, who had a mean curve of 30.4 degrees. More patients whose mothers were twenty-seven years old or older ultimately needed arthrodesis than did those whose mothers were younger than twenty-seven years (26 compared with 12 per cent). Therefore, a maternal age of twenty-seven years old or more is a risk factor for greater progression of the curve and indicates a potential need for arthrodesis. No difference in the degree of curvature was seen when the patients were grouped according to paternal age.

Synthetic porphyrins as tumour-localizing agents.

A series of radioactively labelled porphyrin analogues have been synthesized and compared for tissue distribution and tumour uptake against 67Ga in the same tumour-mouse system. The compounds were: 14C-ms-tetraphenylporphine sulphonate (14C-TPPS), 35S-ms-tetraphenylporphine sulphonate (TPP35S), 35S-ms-tetra[beta-naphthyl]porphine sulphonate (TNP35S), 14C-ms-thienylphenylporphine sulphonate (14C-TTPPS) and 35S-ms-tetra[p-tolyl]porphine sulphonate (TTP35S). 14C-TPPS and TNP35S appear to concentrate in tumours to a greater extent than 67Ga (ratios of tumour uptake for TPPS/67Ga and TNPS/67Ga were about two and three respectively) but their uptake in kidneys and lungs was also greater than that of gallium. The type of side group attached to the central tetrapyrrole ring appears to have a substantial effect on the tumour-localizing properties of these compounds. Comparison of 14C and 35S-labeled TPPS indicates that the sulphonate groups are split off in vivo and that compounds with highly aromatic side groups (e.g. TNPS) and a radioactive label in a non-labile part of the molecule (e.g. in the tetrapyrrole ring system itself) would show even better tumour localization. The feasibility of synthesizing porphyrins with a variety of reactive side groups suggests that it may be possible to introduce suitable gamma-emitters while retaining the tumour-localizing properties.

The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients.

A total of 295 patients treated with the Boston bracing system with follow-up of at least 1 year after completion of bracing are reviewed. Pre-brace curves ranged from 20-59 degrees Cobb. Mean age at brace initiation was 13.2 years with a mean treatment time of 2.9 years and mean follow-up of 1.4 years. Mean best in-brace correction averaged 50% with correction averaging 23% at the initiation of weaning from the brace. By the time of brace discontinuance, average curve correction was 15%. At follow-up, average correction was 11%. A comparison of follow-up with pre-brace values of major curves showed that 49% were unchanged +/- 5 degree, 39% achieved final correction of 5-15 degrees, 4% achieved final correction of 15 degrees or more, 4% of patients lost 5-15 degrees, and 3% lost more than 15 degrees by the time of follow-up. Eleven percent of patients underwent surgery during the period of bracing; 1% had surgery during follow-up period. Correction and control of major curves with apexes below T8 and above L2 were best. A strong correlation between best, or initial in-brace correction, and follow-up correction was noted. Young age at the initiation of bracing and higher degrees of pre-brace curvature increased the incidence of surgery. Those curves that had corrected most at the end of bracing were most at risk for loss of correction after bracing. Partial compliance with brace wear appeared as effective as full-time wear. Boston braces without superstructure appeared to be as effective as braces with superstructure for curves with apexes below T7.

Inferior (obturator) dislocation of the hip in neonates. A complication of treatment by the Pavlik harness.

Two neonates, treated by the Pavlik harness for congenital dislocation of the hip, developed inferior dislocation due to excessive hip flexion. Early recognition of the complication and diminution of the angle of flexion gave a stable relocation of the hip in both patients.

Congenital aplasia of the cruciate ligaments. A report of six cases.

Instability of the knee is frequently found in association with congenital leg-length discrepancy. We have studied six such patients clinically, radiologically and arthroscopically. Clinical signs of knee instability and significant radiological changes were present in all, and at arthroscopy the anterior cruciate ligament was completely absent in four patients and functionless in the other two. This deficiency appears to be a congenital condition which may predispose to meniscus injury or retropatellar pain; it may also lead to subluxation or dislocation of the knee during leg-lengthening procedures.

An unusual Monteggia type-I equivalent fracture in a child.

A six-year-old girl sustained a Monteggia type-I equivalent fracture of the right forearm. We describe the method of treatment of this rare fracture and its outcome.