Gene products and processes contributing to lanthanide homeostasis and methanol metabolism in Methylorubrum extorquens AM1.

Lanthanide elements have been recently recognized as "new life metals" yet much remains unknown regarding lanthanide acquisition and homeostasis. In Methylorubrum extorquens AM1, the periplasmic lanthanide-dependent methanol dehydrogenase XoxF1 produces formaldehyde, which is lethal if allowed to accumulate. This property enabled a transposon mutagenesis study and growth studies to confirm novel gene products required for XoxF1 function. The identified genes encode an MxaD homolog, an ABC-type transporter, an aminopeptidase, a putative homospermidine synthase, and two genes of unknown function annotated as orf6 and orf7. Lanthanide transport and trafficking genes were also identified. Growth and lanthanide uptake were measured using strains lacking individual lanthanide transport cluster genes, and transmission electron microscopy was used to visualize lanthanide localization. We corroborated previous reports that a TonB-ABC transport system is required for lanthanide incorporation to the cytoplasm. However, cells were able to acclimate over time and bypass the requirement for the TonB outer membrane transporter to allow expression of xoxF1 and growth. Transcriptional reporter fusions show that excess lanthanides repress the gene encoding the TonB-receptor. Using growth studies along with energy dispersive X-ray spectroscopy and transmission electron microscopy, we demonstrate that lanthanides are stored as cytoplasmic inclusions that resemble polyphosphate granules.

Is Maxillomandibular Advancement Associated With Comorbidity Reduction in Patients With Obstructive Sleep Apnea?

PURPOSE: This study investigated whether patients with documented obstructive sleep apnea (OSA) who have a decrease in apnea-hypopnea index (AHI) score and self-reported symptoms after maxillomandibular advancement (MMA) with genial tubercle advancement (GTA) also have a change in their medical comorbidity profile a minimum of 2 years postoperatively. Changes in the quantity of medical diagnoses, quantity of prescription medications, and average weight and body mass index (BMI) were assessed. PATIENTS AND METHODS: This is a retrospective cohort study of patients with a diagnosis of OSA (AHI score >5 on polysomnogram [PSG]) treated at the Massachusetts General Hospital (Boston, MA) with MMA and GTA from 2001 through 2015. Patients were identified through the oral and maxillofacial surgery patient data registry. Inclusion criteria were the availability of complete clinical records and requisite follow-up time. The primary predictor variable was operative status (preoperative or postoperative). The primary outcome variables were comorbidities reported to be associated with OSA and identified in the authors' previous study (J Oral Maxillofac Surg 76:1999.e1, 2018). Two-tailed paired t tests were used for continuous variables and χ2 or Fisher exact tests were used for categorical variables. RESULTS: Forty-six patients (39 men, 7 women) met the inclusion criteria. Average weight (206.7 ± 42.4 lb preoperatively; 213.8 ± 41.7 lb postoperatively; P = .014) and average BMI (30.0 ± 5.7 kg/m2 preoperatively; 30.9 ± 5.3 kg/m2 postoperatively; P = .041) significantly increased in patients postoperatively. No meaningful changes in the number of medical diagnoses or number of prescription medications were noted. Stratification of patients by BMI showed significant increases in weight (188.6 ± 21.5 lb preoperatively; 200.1 ± 27.9 lb postoperatively; P = .0085) and BMI (27.1 ± 1.44 kg/m2 preoperatively; 28.9 ± 3.52 kg/m2 postoperatively; P = .013) only in "overweight" patients. No other parameters were found to be relevant. CONCLUSIONS: Subjective improvement in OSA symptoms was reported by all patients and objective PSG improvement was reported for 71% of those evaluated. However, no relevant changes in comorbidity profile were found, suggesting that the medical conditions commonly observed with OSA are likely of multifocal etiology.

Does the Medical Comorbidity Profile of Obstructive Sleep Apnea Patients Treated With Maxillomandibular Advancement Differ From That of Obstructive Sleep Apnea Patients Managed Nonsurgically?

PURPOSE: Obstructive sleep apnea (OSA) patients with retrognathia and measurable anatomic airway determinants may represent a subset of OSA patients and have distinct comorbidity profiles. Our aim was to compare the medical comorbidities of OSA patients managed surgically with maxillomandibular advancement with those of nonsurgical patients. PATIENTS AND METHODS: In this cross-sectional retrospective study, patients for both cohorts were identified through the Massachusetts General Hospital oral and maxillofacial surgery data registry and the Massachusetts General Hospital Research Patient Data Registry. The inclusion criteria consisted of clinical records documenting body mass index (BMI), apnea-hypopnea index, respiratory disturbance index, and/or oxygen nadir. The primary predictor variable was the treatment modality chosen: surgical (maxillomandibular advancement) or nonsurgical. Demographic information and OSA parameters were evaluated. The primary outcome variable was the number of documented comorbidities in each group. Two-sample t tests were used for continuous variables, whereas χ2 or Fisher exact tests were used for categorical variables. RESULTS: The nonsurgical cohort consisted of 71 patients (67.6% men), and the surgical cohort consisted of 51 patients (84.3% men). Comparison of descriptive characteristics showed that the nonsurgical cohort had a higher average age (49 ± 9.4 years) than the surgical cohort (41 ± 10.7 years, P < .001). In addition, a higher average BMI was present in the nonsurgical group (42.3 ± 11.9 in nonsurgical group vs 29.7 ± 5.5 in surgical group, P < .001). Polysomnogram parameters were comparable with the exception of a higher Epworth Sleepiness Scale score in the surgical cohort (15.5 ± 5.30 in surgical group vs 9.90 ± 6.80 in nonsurgical group, P = .005). The nonsurgical cohort had a higher total number of comorbidities (7 ± 4 in nonsurgical group vs 4 ± 3 in surgical group, P < .001). Hypertension, cardiovascular disease, hyperlipidemia, pulmonary hypertension, obstructive pulmonary disease, and type 2 diabetes mellitus had higher prevalences within the nonsurgical group. CONCLUSIONS: The results of this study suggest that nonsurgically managed OSA patients tend to have more complex medical comorbidity profiles than those managed surgically. Obesity (BMI >30) was more prevalent in the nonsurgical cohort, which may be contributory. The additive contribution of OSA needs to be further elucidated.

NELL-1 injection maintains long-bone quantity and quality in an ovariectomy-induced osteoporotic senile rat model.

Over 10 million Americans have osteoporosis, and is the predominant cause of fractures in the elderly. Treatment of fractures in the setting of osteoporosis is complicated by a suboptimal bone regenerative response due to a decline in the number of osteoblasts, their function, and survival. Consequently, an osteogenic therapeutic to prevent and treat fractures in patients with osteoporosis is needed. Nel-like molecule-1 (NELL-1), a novel osteoinductive growth factor, has been shown to promote bone regeneration. In this study, we aim to demonstrate the capacity of recombinant NELL-1 to prevent ovariectomy (OVX)-induced osteoporosis in a senile rat model. Ten-month-old female Sprague-Dawley rats underwent either sham surgery or OVX. Subsequently, 50 µL of 600 µg/mL NELL-1 lyophilized onto a 0-50-µm tricalcium phosphate (TCP) carrier was injected into the femoral bone marrow cavity while phosphate-buffered saline (PBS) control was injected into the contralateral femur. Our microcomputed tomography results showed that OVX+PBS/TCP control femurs showed a continuous decrease in the bone volume (BV) and bone mineral density (BMD) from 2 to 8 weeks post-OVX. In contrast, OVX+NELL-1/TCP femurs showed resistance to OVX-induced bone resorption showing BV and BMD levels similar to that of SHAM femurs at 8 weeks post-OVX. Histology showed increased endosteal-woven bone, as well as decreased adipocytes in the bone marrow of NELL-1-treated femurs compared to control. NELL-1-treated femurs also showed increased immunostaining for bone differentiation markers osteopontin and osteocalcin. These findings were validated in vitro, in which addition of NELL-1 in OVX bone marrow stem cells resulted in increased osteogenic differentiation. Thus, NELL-1 effectively enhances in situ osteogenesis in the bone marrow, making it potentially useful in the prevention and treatment of osteoporotic fractures.

High doses of bone morphogenetic protein 2 induce structurally abnormal bone and inflammation in vivo.

The major Food and Drug Association-approved osteoinductive factors in wide clinical use are bone morphogenetic proteins (BMPs). Although BMPs can promote robust bone formation, they also induce adverse clinical effects, including cyst-like bone formation and significant soft tissue swelling. In this study, we evaluated multiple BMP2 doses in a rat femoral segmental defect model and in a minimally traumatic rat femoral onlay model to determine its dose-dependent effects. Results of our femoral segmental defect model established a low BMP2 concentration range (5 and 10 µg/mL, total dose 0.375 and 0.75 µg in 75 µg total volume) unable to induce defect fusion, a mid-range BMP2 concentration range able to fuse the defect without adverse effects (30 µg/mL, total dose 2.25 µg in 75 µg total volume), and a high BMP2 concentration range (150, 300, and 600 µg/mL, total dose 11.25, 22.5, and 45 µg in 75 µg total volume) able to fuse the defect, but with formation of cyst-like bony shells filled with histologically confirmed adipose tissue. In addition, compared to control, 4 mg/mL BMP2 also induced significant tissue inflammatory infiltrates and exudates in the femoral onlay model that was accompanied by increased numbers of osteoclast-like cells at 3, 7, and 14 days. Overall, we consistently reproduced BMP2 side effects of cyst-like bone and soft tissue swelling using high BMP2 concentration approaching the typical human 1500 µg/mL.

Role of glutathione in macrophage control of mycobacteria.

Reactive oxygen and nitrogen intermediates are important antimicrobial defense mechanisms of macrophages and other phagocytic cells. While reactive nitrogen intermediates have been shown to play an important role in tuberculosis control in the murine system, their role in human disease is not clearly established. Glutathione, a tripeptide and antioxidant, is synthesized at high levels by cells during reactive oxygen intermediate and nitrogen intermediate production. Glutathione has been recently shown to play an important role in apoptosis and to regulate antigen-presenting-cell functions. Glutathione also serves as a carrier molecule for nitric oxide, in the form of S-nitrosoglutathione. Previous work from this laboratory has shown that glutathione and S-nitrosoglutathione are directly toxic to mycobacteria. A mutant strain of Mycobacterium bovis BCG, defective in the transport of small peptides such as glutathione, is resistant to the toxic effect of glutathione and S-nitrosoglutathione. Using the peptide transport mutant as a tool, we investigated the role of glutathione and S-nitrosoglutathione in animal and human macrophages in controlling intracellular mycobacterial growth.