Purpose. To quantify in a longitudinal study non-chondrocytic cells and chondrocytes, tissular architecture as well as extracellular matrix restoration during the formation of an enthesis following supraspinatus tendon attachment to the humerus. Methods. In 89 rabbits, one supraspinatus fibrocartilaginous enthesis was resected and the tendon either attached to the greater tuberosity (n = 75) or not attached (n = 14). The animals were sacrificed after 2, 6, 8, 12 or 24 weeks. The operated and contralateral shoulders were processed for histologic sections. Number of non-chondrocytes, chondrocytes and alignment of chondrocytes in rows were assessed histologically. Extracellular matrix restoration was measured based on (1) area of toluidine blue metachromasia indicating proteoglycan content and (2) on area of diffracted polarized light indicating spatial collagen fiber alignment. Results. In the attached tendon, the number of non-chondrocytic cells sharply increased at 2 weeks, progressively decreased thereafter but remained higher than controls at all time points. Chondrocytes appeared at 2 weeks and their number reached control levels by 6 weeks (136 ± 14 vs 144 ± 15 controls, p > .05). The percentage of chondrocytes aligned in rows increased from 19 ± 4% at 2 weeks to reach near normal values at 24 weeks (71 ± 3% vs 78 ± 2% controls, p > .05). Area of metachromasia increased from 0.1 ± 0.1 mm2 at 2 weeks to 3.8 ± 0.3 mm2 at 24 weeks, still below contralateral enthesis levels (4.6 ± 0.1 mm2, p < .05). Area of diffracted polarized light enlarged from 12 ± 2 × 103 μm2 at 2 weeks to 151 ± 19 × 103 μm2 at 24 weeks, still significantly smaller than contralateral levels (177 ± 13 × 103 μm2, p < .05). Neither chondrocytes nor metachromasia were observed in the non-attached tendons. Conclusion. A new enthesis was formed after attachment of the supraspinatus tendon into bony trough. Histomorphometry allowed to document extensive non-chondrocytic proliferation that was followed by appearance of chondrocytes and their spatial organization, a process was complete by 24 weeks. Extracellular matrix formation as well as spatial alignment of collagen fibers were delayed and not complete by 24 weeks. This first longitudinal investigation on the formation of the supraspinatus enthesis using quantitative outcome measures cautions against too early and too aggressive a rehabilitation program.
Abstract Carbon monoxide (CO)‐based tests have precisely measured hemolysis for over 40 years. End‐tidal CO was the primary marker in clinical hematology research, followed by carboxyhemoglobin. Quantification of CO reflects heme oxygenases degrading heme in a 1:1 stoichiometric ratio, making CO a direct marker of hemolysis. CO in alveolar air can be quantified using gas chromatography, whose high resolution allows detecting mild and moderate levels of hemolysis. CO can be elevated in active bleeding, resorbing hematoma, and smoking. Clinical acumen and other markers remain necessary to diagnose the cause of hemolysis. CO‐based tests constitute an opportunity for bench‐to‐bedside technology transfer.
The objective of this study is to explore the transcriptomic and biologic variables characterizing the longitudinal rehabilitation intervention of patients with hospital-acquired deconditioning (HAD). This prospective clinical trial recruited HAD patients (n = 10) who spent ≥3 weeks hospitalized and then received inpatient rehabilitation. Functional improvement was measured using the Functional Independence Measure (FIM). Transcriptomic and biological variables were recorded at rehabilitation admission and 1, 2, 4, and 6 weeks post-admission. RNA sequencing studied the temporal changes of gene expression in leukocytes. Between-subject transcriptome comparisons were performed using principle component analysis. Within-subject changes in gene expression were analyzed using a gene ontology hierarchical clustering to identify common biological terms. Heart rate, weight, albumin, creatinine, and complete blood counts were analyzed. Patients average age was 50.6 ± 7.2, FIM increased during inpatient rehabilitation (p = 0.01), weight increased (p = 0.01), lymphocytes decreased (p = 0.05), neutrophil increased (0.03) and red cell distribution width decreased (p = 0.05). The temporal profiles of gene expression revealed within-patient homogeneity and between-patients heterogeneity. The biological terms “bone morphogenesis” and “muscle cell development” were the most significantly enriched differentially expressed genes. Transcriptomic and biologic markers paralleled the functional improvements of HAD patients during inpatient rehabilitation. Transcriptomic analyses were consistent with the cohort heterogeneity. Enrichment of the biological pathways bone morphogenesis and muscle cell development constituted evidence at the gene expression level of the effect of rehabilitation. Larger studies of various rehabilitation patient groups may increase gene expression profile homogeneity. Objective transcriptomic and biologic markers have the potential to improve the rehabilitation of HAD patients.IMPLICATIONS FOR REHABILITATIONNovel gene expression methods are increasingly being integrated into clinical practice and may apply to rehabilitation.Patients with hospital-acquired deconditioning (HAD) enriched gene expression of pathways targeted by inpatient rehabilitation such as bone morphogenesis and muscle cell development.The gene expression paralleled functional improvement of HAD patients.These data demonstrated the feasibility of molecular methods to identify markers of rehabilitation success in HAD patients. Novel gene expression methods are increasingly being integrated into clinical practice and may apply to rehabilitation. Patients with hospital-acquired deconditioning (HAD) enriched gene expression of pathways targeted by inpatient rehabilitation such as bone morphogenesis and muscle cell development. The gene expression paralleled functional improvement of HAD patients. These data demonstrated the feasibility of molecular methods to identify markers of rehabilitation success in HAD patients.
Patients with or at risk of developing knee osteoarthritis (OA) can acquire a knee flexion contracture (FC). The prevalence, severity, and association of knee FC on OA outcomes such as pain, stiffness, and function are not well described and clinical scales may omit measuring joint range of motion.(1) To determine if the presence and severity of a knee FC was associated with worse joint pain, stiffness and/or function and (2) to determine if this association was present in participants with or at risk of knee OA.Following a detailed standardized protocol, maximum knee extension was obtained from the baseline physical examination data using a goniometer with the fulcrum over the knee joint line, the upper arm directed towards the greater trochanter and the lower arm directed towards the lateral malleolus.Cross-sectional, using the Osteoarthritis Initiative database.Baseline cross-sectional data collected from a prospective outpatient cohort study, recruiting from four academic health care centers in the United States. Three subcohorts were included: those at-risk of OA (n = 5995 knees), those with radiographic OA (n = 2610 knees), and controls (n = 62 knees).We categorized knee FCs as none, mild, moderate, or severe. Pain scales included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and numeric pain rating scale; stiffness, the WOMAC stiffness subscale; and function, the WOMAC function subscale and 400-m walk time.Participants with FC reported overall worse pain, stiffness, and function compared to those without FC in a severity-dependent manner. OA participants' scores showed between 1.8- and 11.0-fold mean relative worsening versus at-risk participants (P < .05 for all). Knee FC was independently associated in a severity-dependent manner with all outcomes (P < .01).Knee FCs were associated with worse pain, stiffness, and function in a severity-dependent manner in a population with or at risk of knee OA. There was an interaction between OA subcohort and FC severity (P-for-interaction <.01 for all WOMAC outcomes). Evaluation of the longitudinal effects of contracture on OA and at-risk patient outcomes is necessary.
Skeletal disuse can cause an accumulation of bone marrow adipose tissue (MAT) characterized by a combination of marrow adipocyte hyperplasia and/or hypertrophy. The malleability of MAT accumulation and of the hyperplasia and hypertrophy upon remobilization is unknown. In this study, we showed extensive hyperplasia and accelerated hypertrophy of bone marrow adipocytes in the proximal tibia epiphysis of rat knees immobilized for durations between 1 and 32 wk. Similar histomorphometric measures of adipocytes carried out in unoperated controls allowed distinguishing the effects of immobilization from the effects of aging. Although both knee immobilization and aging led to adipocyte hypertrophy, adipocyte hyperplasia was the hallmark signature effect of immobilization on MAT. Both bone marrow adipocyte hyperplasia and hypertrophy were sustained despite knee remobilization for durations up to four times the duration of immobilization. These results suggest that adipocyte hyperplasia is the predominant mechanism explaining MAT accumulation in skeletal disuse. In this model, the changes were unremitting for the investigated time points. Investigating the cellular and molecular mechanisms of marrow adipocyte mechanoregulation will be important to better understand how adipocytes adapt to changes in mechanical environments.NEW & NOTEWORTHY This longitudinal study elucidates the response of marrow adipose tissue adipocytes in weight-bearing joints to changes in different mechanical environments, and we provide insight on the malleability of the changes over time. In a rat animal model, knee immobilization induced hyperplasia and accelerated the age-dependent hypertrophy of adipocytes. Changes in adipocyte number and size were sustained despite unassisted remobilization. Multimodal distributions of cell size were characteristic of bone marrow adipocytes.
Anemia in astronauts has been noted since the first space missions, but the mechanisms contributing to anemia in space flight have remained unclear. Here, we show that space flight is associated with persistently increased levels of products of hemoglobin degradation, carbon monoxide in alveolar air and iron in serum, in 14 astronauts throughout their 6-month missions onboard the International Space Station. One year after landing, erythrocytic effects persisted, including increased levels of hemolysis, reticulocytosis and hemoglobin. These findings suggest that the destruction of red blood cells, termed hemolysis, is a primary effect of microgravity in space flight and support the hypothesis that the anemia associated with space flight is a hemolytic condition that should be considered in the screening and monitoring of both astronauts and space tourists.
Although it is assumed that most mammals experience growth plate closure and cessation of bone growth soon after sexual maturity, bone growth in rats continues throughout their lifespan. The rat was compared to other laboratory animals to assess differences in the duration of bone growth and its relationship to age at sexual maturity and lifespan. We reviewed the literature from 1966 to March 1999 by searching MEDLINE and other databases. Growth closure times and age at sexual maturity were retrieved for the mouse, rabbit, dog, cat, sheep, cow, horse, nonhuman primates, and human. For all species, we calculated the ratios of: 1) age at growth plate closure to lifespan, 2) age at growth plate closure to age at sexual maturity, and 3) age at sexual maturity to average lifespan. The ratio of age at physis closure to the average lifespan was large for the rat (22 to 35) and showed some overlap with that of humans (17 to 25); this ratio was comparatively small in all other nonhuman species (range, 4 to 17). This finding indicates that bone growth continues in the rat for a greater proportion of their lifespan than does that in other species. The ratio of age at physis closure to age at sexual maturity was larger for the rat (5 to 6) than that for other species, indicating that bone growth continues much longer after sexual maturity in rats than in other animals. The ratio of age at sexual maturity to average lifespan was largest for humans and nonhuman primates (13 to 14), indicating the increased time to reach puberty versus that in other species. These differences are important for studies in which animal models are used in research involving bone growth.
Abstract It is now widely recognised that the environment in space activates a diverse set of genes involved in regulating fundamental cellular pathways. This includes the activation of genes associated with blood homeostasis and erythropoiesis, with a particular emphasis on those involved in globin chain production. Haemoglobin biology provides an intriguing model for studying space omics, as it has been extensively explored at multiple -omic levels, spanning DNA, RNA, and protein analyses, in both experimental and clinical contexts. In this study, we examined the developmental expression of haemoglobin over time and space using a unique suite of multi-omic datasets available on NASA GeneLab, from the NASA Twins Study, the JAXA CFE study, and the Inspiration4 mission. Our findings reveal significant variations in globin gene expression corresponding to the distinct spatiotemporal characteristics of the collected samples. This study sheds light on the dynamic nature of globin gene regulation in response to the space environment and provides valuable insights into the broader implications of space omics research.
