FGF-independent MEK1/2 signalling in the developing foetal testis is essential for male germline differentiation in mice.

BACKGROUND: Disrupted germline differentiation or compromised testis development can lead to subfertility or infertility and are strongly associated with testis cancer in humans. In mice, SRY and SOX9 induce expression of Fgf9, which promotes Sertoli cell differentiation and testis development. FGF9 is also thought to promote male germline differentiation but the mechanism is unknown. FGFs typically signal through mitogen-activated protein kinases (MAPKs) to phosphorylate ERK1/2 (pERK1/2). We explored whether FGF9 regulates male germline development through MAPK by inhibiting either FGF or MEK1/2 signalling in the foetal testis immediately after gonadal sex determination and testis cord formation, but prior to male germline commitment. RESULTS: pERK1/2 was detected in Sertoli cells and inhibition of MEK1/2 reduced Sertoli cell proliferation and organisation and resulted in some germ cells localised outside of the testis cords. While pERK1/2 was not detected in germ cells, inhibition of MEK1/2 after somatic sex determination profoundly disrupted germ cell mitotic arrest, dysregulated a broad range of male germline development genes and prevented the upregulation of key male germline markers, DPPA4 and DNMT3L. In contrast, while FGF inhibition reduced Sertoli cell proliferation, expression of male germline markers was unaffected and germ cells entered mitotic arrest normally. While male germline differentiation was not disrupted by FGF inhibition, a range of stem cell and cancer-associated genes were commonly altered after 24 h of FGF or MEK1/2 inhibition, including genes involved in the maintenance of germline stem cells, Nodal signalling, proliferation, and germline cancer. CONCLUSIONS: Together, these data demonstrate a novel role for MEK1/2 signalling during testis development that is essential for male germline differentiation, but indicate a more limited role for FGF signalling. Our data indicate that additional ligands are likely to act through MEK1/2 to promote male germline differentiation and highlight a need for further mechanistic understanding of male germline development.

Host and primary tumor factors for the development of multiple cutaneous squamous cell carcinomas among a retrospective cohort in Rhode Island.

INTRODUCTION: Risk factors for a primary cutaneous squamous cell carcinoma (CSCC) are well-established; however, the host and primary tumor risk factors for subsequent CSCC have not been fully explored. METHODS: We performed a retrospective chart review of patients diagnosed with CSCC in an academic dermatology clinic in Rhode Island from 2016-2019. Logistic regression was used to evaluate the associations between host factors and multiple CSCC and between primary tumor characteristics and the risk of subsequent CSCC. Adjusted odds ratios (aORs) and 95% CIs were calculated. RESULTS: A total of 1312 patients with CSCC diagnoses were included. Host risk factors significantly associated with multiple CSCCs included: aged >80 years (aOR, 2.18; 95% CI, 1.46-3.31); history of: solid organ transplant (aOR, 2.41; 95% CI, 1.20-4.80); skin cancer (aOR, 1.96; 95% CI, 1.52-2.54); other cancer (aOR, 1.49; 95% CI, 1.11-2.00); family history of skin cancer (aOR, 1.36; 95% CI, 1.03-1.78); and actinic keratosis (aOR, 1.52; 95% CI, 1.18-1.95). Tumor location, diameter, histologic differentiation, and treatment were not significant predictors of subsequent CSCCs. LIMITATIONS: Study patients were predominantly White and from a single institution, limiting the generalizability of results. CONCLUSIONS: Certain host characteristics were associated with the development of subsequent CSCC, which may inform clinical guidelines for follow-up.

Physical Activity Management for Youth With Type 1 Diabetes: Supporting Active and Inactive Children.

Regular physical activity and exercise are important for youth and essential components of a healthy lifestyle. For youth with type 1 diabetes, regular physical activity can promote cardiovascular fitness, bone health, insulin sensitivity, and glucose management. However, the number of youth with type 1 diabetes who regularly meet minimum physical activity guidelines is low, and many encounter barriers to regular physical activity. Additionally, some health care professionals (HCPs) may be unsure how to approach the topic of exercise with youth and families in a busy clinic setting. This article provides an overview of current physical activity research in youth with type 1 diabetes, a basic description of exercise physiology in type 1 diabetes, and practical strategies for HCPs to conduct effective and individualized exercise consultations for youth with type 1 diabetes.

Coffee consumption and risk of renal cancer: a meta-analysis of cohort evidence.

PURPOSE: There is increasing evidence that coffee consumption is related to reduced risks for some cancers, but the evidence for renal cancer is inconclusive. Therefore, we conducted a meta-analysis to summarize the cohort evidence of this relationship. METHODS: A literature search was performed in PubMed and Embase through February 2021. Meta-analyses using a random effects model were conducted for reported relative risk estimates (RRs) relating coffee intake and renal cancer incidence or mortality. We also performed a two-stage random effects exposure-response meta-analysis. Between-study heterogeneity was assessed. RESULTS: In a meta-analysis of the ten identified cohort studies, we found a summary RR of 0.88 [95% confidence interval (CI) 0.78-0.99] relating the highest vs. the lowest category of coffee intake and renal cancer, with no significant between-study heterogeneity observed (I2 = 35%, p = 0.13). This inverse association remained among studies of incident cancers (RR 0.85, 95% CI 0.76-0.96) and studies adjusting for smoking and body mass index (RR 0.87, 95% CI 0.77-0.99). CONCLUSIONS: Our findings from this meta-analysis of the published cohort evidence are suggestive of an inverse association between coffee consumption and renal cancer risk.

Increased CD69+CCR7+ circulating activated T cells and STAT3 expression in cutaneous lupus erythematosus patients recalcitrant to antimalarials.

BACKGROUND: Antimalarials are first-line systemic therapy for cutaneous lupus erythematosus (CLE). While some patients unresponsive to hydroxychloroquine (HCQ) alone benefit from the addition of quinacrine (QC), a subset of patients is refractory to both antimalarials. METHODS: We classified CLE patients as HCQ-responders, HCQ+QC-responders, or HCQ+QC-nonresponders to compare immune profiles. Immunohistochemistry, immunofluorescence, and qRT-PCR were used to characterize inflammatory cells and cytokines in lesional skin. RESULTS: Immunohistochemistry showed that CD69+ T cells were higher in HCQ+QC-nonresponders compared to HCQ- and HCQ+QC-responders (p < 0.05). Immunofluorescence further identified these cells as CD69+CCR7+ circulating activated T cells. Myeloid dendritic cells were significantly higher in HCQ+QC-responders compared to both HCQ-responders and HCQ+QC-nonresponders. Plasmacytoid dendritic cells were significantly increased in HCQ-responders compared to HCQ- and HCQ+QC-nonresponders. No differences were found in the number of autoreactive T cells, MAC387+ cells, and neutrophils among the groups. CLASI scores of the HCQ+QC-nonresponder group positively correlated with CD69+CCR7+ circulating activated T cells (r = 0.6335, p < 0.05) and MAC387+ cells (r = 0.5726, p < 0.05). IL-17 protein expression was higher in HCQ+QC-responders compared to HCQ-responders or HCQ+QC-nonresponders, while IL-22 protein expression did not differ. mRNA expression demonstrated increased STAT3 expression in a subset of HCQ+QC-nonresponders. CONCLUSION: An increased number of CD69+CCR7+ circulating activated T cells and a strong correlation with CLASI scores in the HCQ+QC-nonresponders suggest these cells are involved in antimalarial-refractory skin disease. STAT3 is also increased in HCQ+QC-nonresponders and may also be a potential target for antimalarial-refractory skin disease.

Remdesivir for the treatment of patients in hospital with COVID-19 in Canada: a randomized controlled trial.

BACKGROUND: The role of remdesivir in the treatment of patients in hospital with COVID-19 remains ill defined in a global context. The World Health Organization Solidarity randomized controlled trial (RCT) evaluated remdesivir in patients across many countries, with Canada enrolling patients using an expanded data collection format in the Canadian Treatments for COVID-19 (CATCO) trial. We report on the Canadian findings, with additional demographics, characteristics and clinical outcomes, to explore the potential for differential effects across different health care systems. METHODS: We performed an open-label, pragmatic RCT in Canadian hospitals, in conjunction with the Solidarity trial. We randomized patients to 10 days of remdesivir (200 mg intravenously [IV] on day 0, followed by 100 mg IV daily), plus standard care, or standard care alone. The primary outcome was in-hospital mortality. Secondary outcomes included changes in clinical severity, oxygen- and ventilator-free days (at 28 d), incidence of new oxygen or mechanical ventilation use, duration of hospital stay, and adverse event rates. We performed a priori subgroup analyses according to duration of symptoms before enrolment, age, sex and severity of symptoms on presentation. RESULTS: Across 52 Canadian hospitals, we randomized 1282 patients between Aug. 14, 2020, and Apr. 1, 2021, to remdesivir (n = 634) or standard of care (n = 648). Of these, 15 withdrew consent or were still in hospital, for a total sample of 1267 patients. Among patients assigned to receive remdesivir, in-hospital mortality was 18.7%, compared with 22.6% in the standard-of-care arm (relative risk [RR] 0.83 (95% confidence interval [CI] 0.67 to 1.03), and 60-day mortality was 24.8% and 28.2%, respectively (95% CI 0.72 to 1.07). For patients not mechanically ventilated at baseline, the need for mechanical ventilation was 8.0% in those assigned remdesivir, and 15.0% in those receiving standard of care (RR 0.53, 95% CI 0.38 to 0.75). Mean oxygen-free and ventilator-free days at day 28 were 15.9 (± standard deviation [SD] 10.5) and 21.4 (± SD 11.3) in those receiving remdesivir and 14.2 (± SD 11) and 19.5 (± SD 12.3) in those receiving standard of care (p = 0.006 and 0.007, respectively). There was no difference in safety events of new dialysis, change in creatinine, or new hepatic dysfunction between the 2 groups. INTERPRETATION: Remdesivir, when compared with standard of care, has a modest but significant effect on outcomes important to patients and health systems, such as the need for mechanical ventilation. Trial registration: ClinicalTrials.gov, no. NCT04330690.

Effect of Awake Prone Positioning on Endotracheal Intubation in Patients With COVID-19 and Acute Respiratory Failure: A Randomized Clinical Trial.

Importance: The efficacy and safety of prone positioning is unclear in nonintubated patients with acute hypoxemia and COVID-19. Objective: To evaluate the efficacy and adverse events of prone positioning in nonintubated adult patients with acute hypoxemia and COVID-19. Design, Setting, and Participants: Pragmatic, unblinded randomized clinical trial conducted at 21 hospitals in Canada, Kuwait, Saudi Arabia, and the US. Eligible adult patients with COVID-19 were not intubated and required oxygen (≥40%) or noninvasive ventilation. A total of 400 patients were enrolled between May 19, 2020, and May 18, 2021, and final follow-up was completed in July 2021. Intervention: Patients were randomized to awake prone positioning (n = 205) or usual care without prone positioning (control; n = 195). Main Outcomes and Measures: The primary outcome was endotracheal intubation within 30 days of randomization. The secondary outcomes included mortality at 60 days, days free from invasive mechanical ventilation or noninvasive ventilation at 30 days, days free from the intensive care unit or hospital at 60 days, adverse events, and serious adverse events. Results: Among the 400 patients who were randomized (mean age, 57.6 years [SD, 12.83 years]; 117 [29.3%] were women), all (100%) completed the trial. In the first 4 days after randomization, the median duration of prone positioning was 4.8 h/d (IQR, 1.8 to 8.0 h/d) in the awake prone positioning group vs 0 h/d (IQR, 0 to 0 h/d) in the control group. By day 30, 70 of 205 patients (34.1%) in the prone positioning group were intubated vs 79 of 195 patients (40.5%) in the control group (hazard ratio, 0.81 [95% CI, 0.59 to 1.12], P = .20; absolute difference, -6.37% [95% CI, -15.83% to 3.10%]). Prone positioning did not significantly reduce mortality at 60 days (hazard ratio, 0.93 [95% CI, 0.62 to 1.40], P = .54; absolute difference, -1.15% [95% CI, -9.40% to 7.10%]) and had no significant effect on days free from invasive mechanical ventilation or noninvasive ventilation at 30 days or on days free from the intensive care unit or hospital at 60 days. There were no serious adverse events in either group. In the awake prone positioning group, 21 patients (10%) experienced adverse events and the most frequently reported were musculoskeletal pain or discomfort from prone positioning (13 of 205 patients [6.34%]) and desaturation (2 of 205 patients [0.98%]). There were no reported adverse events in the control group. Conclusions and Relevance: In patients with acute hypoxemic respiratory failure from COVID-19, prone positioning, compared with usual care without prone positioning, did not significantly reduce endotracheal intubation at 30 days. However, the effect size for the primary study outcome was imprecise and does not exclude a clinically important benefit. Trial Registration: ClinicalTrials.gov Identifier: NCT04350723.

Government trust, perceptions of COVID-19 and behaviour change: cohort surveys, Singapore.

OBJECTIVE: To evaluate how public perceptions and trust in government communications affected the adoption of protective behaviour in Singapore during the coronavirus disease 2019 (COVID-19) pandemic. METHODS: We launched our community-based cohort to assess public perceptions of infectious disease outbreaks in mid-2019. After the first case of COVID-19 was reported in Singapore on 23 January, we launched a series of seven COVID-19 surveys to both existing and regularly enrolled new participants every 2 weeks. As well as sociodemographic properties of the participants, we recorded changing responses to judge awareness of the situation, trust in various information sources and perceived risk. We used multivariable logistic regression models to evaluate associations with perceptions of risk and self-reported adopted frequencies of protective behaviour. FINDINGS: Our cohort of 633 participants provided 2857 unique responses during the seven COVID-19 surveys. Most agreed or strongly agreed that information from official government sources (99.1%; 528/533) and Singapore-based news agencies (97.9%; 522/533) was trustworthy. Trust in government communication was significantly associated with higher perceived threat (odds ratio, OR: 2.2; 95% confidence interval, CI: 1.6-3.0), but inversely associated with perceived risk of infection (OR: 0.6; 95% CI: 0.4-0.8) or risk of death if infected (OR: 0.6; 95% CI: 0.4-0.9). Trust in government communication was also associated with a greater likelihood of adopting protective behaviour. CONCLUSION: Our findings show that trust is a vital commodity when managing an evolving outbreak. Our repeated surveys provided real-time feedback, allowing an improved understanding of the interplay between perceptions, trust and behaviour.

Increased MxA protein expression and dendritic cells in spongiotic dermatitis differentiates dermatomyositis from eczema in a single-center case-control study.

BACKGROUND: Dermatomyositis (DM) is conventionally characterized by interface dermatitis (ID) on skin histopathology. A subset of DM patients has skin biopsies showing spongiotic dermatitis (SD), a histopathology more commonly seen in eczema. In this study, we aimed to (a) identify the percentage of clinically diagnosed DM patients with SD skin biopsies, (b) identify cytokine and cell markers that can help determine if a SD skin biopsy is consistent with DM. METHODS: In this case-control study, biopsy specimens from ten DM patients with SD (DM-SD) were compared to specimens from ten healthy controls, ten patients with eczema, and 12 patients with DM with ID (DM-ID). Specimens were stained by immunohistochemistry for MxA, IFN-ß, CD11c, and BDCA2. One-way ANOVA with Bonferroni's multiple comparison test was used to compare protein expression between groups. RESULTS: Eleven of 164 (6.7%) patients with a clinical diagnosis of DM at our tertiary care center were identified as having SD. MxA, IFN-ß, CD11c, and BDCA2 protein expression was significantly higher in DM-SD compared to eczema and healthy controls. Expressions of MxA, IFN-ß, and BDCA2 were not significantly different between DM-SD and DM-ID. CONCLUSION: Increased MxA, IFN-ß, CD11c, and BDCA2 protein expression may aid in distinguishing between DM-SD and eczema and warrants further investigation.

Spironolactone in adolescent acne vulgaris.

Acne vulgaris (AV) is the most common skin condition affecting adolescents, most likely due to elevated androgen levels during puberty. Androgens stimulate and enlarge the sebaceous glands and keratinocytes, resulting in increased production of sebum and abnormal hyperproliferation of keratinocytes which lead to the formation of acne lesions. Current standard of care for AV includes topical therapies for mild cases and antibiotics or oral retinoids for severe cases. In recent years, spironolactone, an aldosterone antagonist and diuretic, has been applied to the treatment of AV due to its anti-androgen effects. Spironolactone is currently recommended in women who use oral contraceptives, are refractory to or contraindicated for standard treatment, show clinical signs of hyperandrogenism, or present with late-onset or persistent-recurrent AV past the teenage years. It is not prescribed to adolescents due to potential side effects; however, current data studying adults indicate that most side effects are mild, and that potential associations with hyperkalemia and increased risk of cancer are not sufficiently supported. Hence, we believe that spironolactone may be a safe and effective therapy for adolescent AV.

Evaluating hemoptysis hospitalizations among patients with bronchiectasis in the United States: a population-based cohort study.

BACKGROUND: The burden of hospitalizations and mortality for hemoptysis due to bronchiectasis is not well characterized. The primary outcome of our study was to evaluate in-hospital mortality in patients admitted with hemoptysis and bronchiectasis, as well as the rates of bronchial artery embolization, length of stay, and hospitalization costs. METHODS: The authors queried the Nationwide Inpatient Sample (NIS) claims database for hospitalizations between 2016 and 2017 using the ICD-10-CM codes for hemoptysis and bronchiectasis in the United States. Multivariable regression was used to evaluate predictors of in-hospital mortality, embolization, length of stay, and hospital costs. RESULTS: There were 8240 hospitalizations (weighted) for hemoptysis in the United States from 2016 to 2017. The overall in-hospital mortality was 4.5%, but higher in males compared to females. Predictors of in-hospital mortality included undergoing three or more procedures, age, and congestive heart failure. Bronchial artery embolization (BAE) was utilized during 2.1% of hospitalizations and was more frequently used in those with nontuberculous mycobacteria and aspergillus infections, but not pseudomonal infections. The mean length of stay was 6 days and the median hospitalization cost per patient was USD $9,610. Having comorbidities and procedures was significantly associated with increased length of stay and costs. CONCLUSION: Hemoptysis is a frequent indication for hospitalization among the bronchiectasis population. In-hospital death occurred in approximately 4.5% of hospitalizations. The effectiveness of BAE in treating and preventing recurrent hemoptysis from bronchiectasis needs to be explored.

Acitretin for Secondary Prevention of Keratinocyte Cancers in a Veteran Population: A Retrospective Cohort Study.

Acitretin, a vitamin A derivative used for psoriasis, can prevent keratinocyte carcinoma (KC). It induced regression of keratoacanthomas (KA) in animal models, presumably by activating retinoic acid and retinoid X receptors that regulate gene expression for growth and proliferation.1,2.

Are Oral Antibiotics an Effective Alternative to Intravenous Antibiotics in Treatment of Osteomyelitis of the Jaw?

PURPOSE: To review treatment of osteomyelitis of the jaw (OMJ) and determine whether antibiotic route and/or length of administration impacts resolution of infection postsurgically. METHODS: The investigators designed a retrospective cohort study enrolling a sample of patients treated at Harborview Medical Center from January 1, 2009 to December 31, 2019. The primary predictor variable was antibiotic administration route: oral (PO) only, intravenous (IV) only, IV transitioned to PO (IV + PO), or none. The secondary predictor was duration of antibiotic therapy (≤6 weeks or >6 weeks). The primary outcome variable was resolution of infection at 2 months follow-up posttreatment completion. The secondary outcome variable was number of surgeries to resolution of infection. Descriptive, bivariate, and multiple linear regression statistics were computed, with statistical significance set at P < .05. RESULTS: Sixty-seven individuals met inclusion criteria (38 male), mean age 51 years (18 to 88). Forty-nine (73%) received PO antibiotics, 12 (18%) IV + PO, 3 (4%) IV, and 3 (4%) none. Both PO and IV antibiotics were associated with clinical resolution (P = .022, .005, respectively) compared with debridement alone. Antibiotic duration of ≤6 weeks compared with >6 weeks was not significant. Seventy-six percent (51 of 67) required only 1 surgery. In the multivariate logistic regression, PO was associated with clinical resolution (P = .025, OR = 5.05). Penicillin allergy (P = 0.049, OR = 0.223) and diabetes (P = .008, OR = 0.104) were adversely associated with outcome. CONCLUSIONS: OMJ was successfully treated with oral antibiotics and surgery. Prescribing 6 weeks of IV antibiotics may be antiquated. Clinicians should consider oral penicillins as first line whenever possible. Further studies are recommended.

The potential of electrochemistry for the detection of coronavirus-induced infections.

Human coronaviruses (HCoV) are no stranger to the global environment. The etiology of previous outbreaks with reported symptoms of respiratory tract infections was attributed to different coronavirus strains, with the latest global pandemic in 2019 also belonging to the coronavirus family. Timely detection, effective therapeutics and future prevention are stake key holders in the management of coronavirus-induced infections. Apart from the gold standard clinical diagnostics, electrochemical techniques have also demonstrated their great potentials in the detection of different viruses and their correlated antibodies and antigens, showing high sensitivities and selectivities, and faster times for the analysis. This article aims to critically review the multifaceted electrochemical approaches, not only in the development of point-of-care portable devices but also as alternative detection strategies that can be coupled with traditional methods for the detection of various strains of coronaviruses.

Oxygen in patients with fibrotic interstitial lung disease: an international Delphi survey.

RATIONALE: Patients with fibrotic interstitial lung disease (ILD) frequently develop resting or exertional hypoxaemia. There is heterogeneity in clinical practice and a paucity of evidence guiding supplemental oxygen use in this patient population. The objectives of this study were to build international expert-based consensus on the indications and goals of supplemental oxygen from the perspective of healthcare providers, and identify potential barriers to its access. METHODS: Semistructured interviews and a comprehensive literature search informed items for the Delphi survey, with items not meeting consensus included in round 2. Round 3 contained survey questions regarding regional funding coverage for oxygen therapy. A priori definitions of consensus were median scores of 4 (agree) to 5 (strongly agree) for "agreement", 1 (strongly disagree) to 2 (disagree) for "disagreement" or 3 (unsure) with an interquartile range of 0-1. RESULTS: 42 out of 45 (93%) experts completed all three survey rounds, representing 17 countries. 20 out of 36 items met consensus for agreement or disagreement, 10 items met consensus for unsure and four items did not meet consensus. Experts agreed that oxygen should be recommended for patients with severe resting hypoxaemia and in cases of exertional desaturation to <85-89%, particularly with attributable symptoms or exercise limitation. There are regional differences in funding coverage for oxygen, based on desaturation thresholds, clinical symptoms and testing requirements. CONCLUSIONS: Experts achieved consensus on 20 items guiding supplemental oxygen use in fibrotic ILD. These findings may inform research, clinical recommendations and funding policy.

Investigating the Legacy of the 1918 Influenza Pandemic in Age-Related Seroepidemiology and Immune Responses to Subsequent Influenza A(H1N1) Viruses Through a Structural Equation Model.

A(H1N1) strains of Influenzavirus were responsible for 2 pandemics in the last 100 years. Because infections experienced early in life may have a long-lasting influence on future immune response against other influenza strains, we drew on previously collected seroincidence data from Singapore (n = 2,554; June-October 2009) to investigate whether the 1918 pandemic influenza virus and its early descendants produced an age-related signature in immune responses against the A/California/7/2009(H1N1)pdm09 virus of 2009. Hemagglutination inhibition assays revealed a J-shaped relationship; the oldest birth cohort (born in 1911-1926) had the highest titers, followed by the youngest (born in 1987-1992). Differential response by vaccination history was also observed, with seasonal influenza vaccine being associated with higher titers mainly in the oldest birth cohort. On the assumption that antibody titers are a correlate of protection, structural equation modeling predicted that a titer-mediated effect by the vaccine could, on its own, account for a negative association with seroconversion equivalent to a risk reduction of 23% (relative risk = 0.77, 95% confidence interval: 0.60, 0.99) in the oldest birth cohort. A subset of 503 samples tested against the A/Brisbane/59/2007(H1N1) and A/Puerto Rico/8/1934(H1N1) strains also revealed different age-related antibody profiles. The effectiveness of seasonal influenza vaccines against future pandemic strains could thus be age-dependent and related to early-life exposures.

Effects of Bisphosphonate Administration on Cleft Bone Graft in a Rat Model.

OBJECTIVE: Bone grafts in patients with cleft lip and palate can undergo a significant amount of resorption. The aim of this study was to investigate the effects of bisphosphonates (BPs) on the success of bone grafts in rats. DESIGN: Thirty-five female 15-week-old Fischer F344 Inbred rats were divided into the following experimental groups, each receiving bone grafts to repair an intraoral CSD: (1) Graft/saline: systemic administration of saline and (2) systemic administration of zoledronic acid immediately following surgery (graft/BP/T0), (3) 1 week postoperatively (graft/BP/T1), and (4) 3 weeks postoperatively (graft/BP/T2). As an additional control, the defect was left empty without bone graft. MAIN OUTCOME MEASURES: Microcomputed tomography and histologic analyses were performed in addition to evaluation of osteoclasts through tartrate-resistant acid phosphatase staining. RESULTS: Bone volume fraction (bone volume/tissue volume) for the delayed BP treatment groups (graft/BP/T1 = 45.4% ± 8.8%; graft/BP/T2 = 46.1% ± 12.4%) were significantly greater than that for the graft/saline group (31.0% ± 7.9%) and the graft/BP/T0 (27.6% ± 5.9%) 6 weeks postoperatively (P < .05). Hematoxylin and eosin staining confirmed an evident increase in bone volume and fusion of defect margins with existing palatal bone in the graft/BP/T1 and graft/BP/T2 groups. The graft/BP/T0 group showed the lowest bone volume with signs of acute inflammation. CONCLUSIONS: Delayed BP administration following cleft bone graft surgery led to significant increase in bone volume and integration compared with saline controls. However, BP injection immediately after the surgery did not enhance bone volume, and rather, may negatively affect bone graft incorporation.