Bone Tissue Composition in Postmenopausal Women Varies With Glycemic Control From Normal Glucose Tolerance to Type 2 Diabetes Mellitus

The risk of fragility fracture increases for people with type 2 diabetes mellitus (T2DM), even after controlling for bone mineral density, body mass index, visual impairment, and falls. We hypothesize that progressive glycemic derangement alters microscale bone tissue composition. We used Fourier-transform infrared (FTIR) imaging to analyze the composition of iliac crest biopsies from cohorts of postmenopausal women characterized by oral glucose tolerance testing: normal glucose tolerance (NGT; n = 35, age = 65 ± 7 years, HbA1c = 5.8 ± 0.3%), impaired glucose tolerance (IGT; n = 26, age = 64 ± 5 years, HbA1c = 6.0 ± 0.4%), and overt T2DM on insulin (n = 25, age = 64 ± 6 years, HbA1c = 9.13 ± 0.6). The distributions of cortical bone mineral content had greater mean values (+7%) and were narrower (−10%) in T2DM versus NGT groups (p < 0.05). The distributions of acid phosphate, an indicator of new mineral, were narrower in cortical T2DM versus NGT and IGT groups (−14% and −14%, respectively) and in trabecular NGT and IGT versus T2DM groups (−11% and −10%, respectively) (all p < 0.05). The distributions of crystallinity were wider in cortical NGT versus T2DM groups (+16%) and in trabecular NGT versus T2DM groups (+14%) (all p < 0.05). Additionally, bone turnover was lower in T2DM versus NGT groups (P1NP: −25%, CTx: −30%, ucOC: −24%). Serum pentosidine was similar across groups. The FTIR compositional and biochemical marker values of the IGT group typically fell between the NGT and T2DM group values, although the differences were not always statistically significant. In summary, worsening glycemic control was associated with greater mineral content and narrower distributions of acid phosphate, an indicator of new mineral, which together are consistent with observations of lower turnover; however, wider distributions of mineral crystallinity were also observed. A more mineralized, less heterogeneous tissue may affect tissue-level mechanical properties and in turn degrade macroscale skeletal integrity. In conclusion, these data are the first evidence of progressive alteration of bone tissue composition with worsening glycemic control in humans. © 2020 American Society for Bone and Mineral Research (ASBMR).     

Polymorphic microsatellite loci for a neotropical leaf-litter frog (Craugastor bransfordii) characterized through Illumina sequencing

There are relatively few molecular resources for amphibians in the tropics where widespread habitat loss, disease, and contamination threaten the world’s most diverse assemblages. We used Illumina sequencing to develop microsatellite primers for a dominant amphibian species in Costa Rica that has recently experienced population declines. We characterized 12 polymorphic loci and have provided sequences for over 200 additional primers. These novel molecular resources will be useful for future studies of population genetic structure and may help explain recent declines in one of many species that are decreasing in Central America.     

The preterm gut microbiota: changes associated with necrotizing enterocolitis and infection

Aim: To describe gut colonization in preterm infants using standard culture and 16S gene rRNA profiling, exploring differences in healthy infants and those who developed NEC/late onset sepsis (LOS). Methods: Ninety‐nine stools from 38 infants of median 27‐week gestation were cultured; 44 stools from 27 infants had their microbial profiles determined by 16S. Ordination analyses explored effects of patient variables on gut communities. Results: Standard microbiological culture identified a mean of two organisms (range 0–7), DGGE 12 (range 3–18) per patient. Enterococcus faecalis and coagulase negative staphylococci (CONS) were most common by culture (40% and 39% of specimens). Meconium was not sterile. No fungi were cultured. Bacterial community structures in infants with NEC and LOS differed from healthy infants. Infants who developed NEC carried more CONS (45% vs 30%) and less Enterococcus faecalis (31% vs 57%). 16S identified Enterobacter and Staphylococcus presence associated with NEC/LOS, respectively. Conclusions: Important differences were found in the gut microbiota of preterm infants who develop NEC/LOS. The relationship of these changes to current practices in neonatal intensive care requires further exploration.     

Compromised first permanent molars: an orthodontic perspective

The first permanent molar (FPM) is commonly subject to significant compromise which may arise due to caries or endodontic complication, or from developmental anomalies such as hypoplasia. Compromised teeth with questionable prognosis may result in short and long-term clinical dilemmas. This review article highlights the factors that require careful consideration when a compromised FPM is detected and the importance of timely FPM extraction. Several clinical cases are described in detail to discuss possible treatment options from the orthodontic perspective.     

Factors Affecting the Longevity and Strength in an <Emphasis Type="Italic">In Vitro</Emphasis> Model of the Bone–Ligament Interface

The interfaces between musculoskeletal tissues with contrasting moduli are morphologically and biochemically adapted to allow the transmission of force with minimal injury. Current methods of tissue engineering ligaments and tendons do not include the interface and this may limit the future clinical success of engineered musculoskeletal tissues. This study aimed to use solid brushite cement anchors to engineer intact ligaments from bone-to-bone, creating a functional musculoskeletal interface in vitro. We show here that modifying anchor shape and cement composition can alter both the longevity and the strength of an in vitro model of the bone–ligament interface: with values reaching 23 days and 21.6 kPa, respectively. These results validate the use of brushite bone cement to engineer the bone–ligament interface in vitro and raise the potential for future use in ligament replacement surgery.     

The association between degenerative hip joint pathology and size of the gluteus maximus and tensor fascia lata muscles

The aim of this study was to obtain, using Magnetic Resonance Imaging (MRI), muscle volume measurements for the gluteus maximus (upper: UGM and lower: LGM portions) and tensor fascia lata (TFL) muscles in both healthy subjects (n = 12) and those with unilateral osteoarthritis (OA) of the hip (mild: n = 6, and advanced: n = 6). While control group subjects were symmetrical between sides for the muscles measured, subjects with hip joint pathology showed asymmetry in GM muscle volume dependent on stage of pathology. The LGM demonstrated atrophy around the affected hip in subjects with advanced pathology (p < 0.05), however asymmetry of the UGM (p < 0.01) could be attributed largely to hypertrophy on the unaffected side, based on between group comparisons of muscle volume. TFL showed no significant asymmetry, or difference compared to the normal control group. This study highlights the functional separation of UGM and LGM, and the similarities of the UGM and TFL, both superficial abductors appearing to maintain their size around the affected hip. Further research is required to determine the specific changes occurring in the deeper abductor muscles. This information may assist in the development of more targeted and effective exercise programmes in the management of OA of the hip.     

Deleterious effects of irradiation and bone marrow transplantation therapy in the genetically anemic an/an mouse

The efficacy and outcome of bone marrow transplantation therapy following lethal irradiation were examined in syngeneic mice that had a hereditary macrocytic anemia (an/an) or were genotypically normal (+/+). Successful RBC and WBC replacement, based on blood cell parameters and donor genetic markers, were observed in all combinations of transplant therapy. Nevertheless, the an/an mice died prematurely several months after treatment, whether they received +/+ or an/an marrow cells. In contrast, the +/+ recipients of either +/+ or an/an marrow cells survived for at least 1 year after transplantation. Premature death of the an/an mice was associated with lymphopenia, anemia, kidney lesions, and severe pathogen-free pneumonitis. On the basis of our results, we hypothesize that the premature deaths of an/an mice are caused by a kind of chronic irradiation damage to which an/an mice are especially susceptible.