Glucose homeostasis and safety in patients with acromegaly converted from long-acting octreotide to pegvisomant

CONTEXT: In clinical practice, patients with acromegaly may be switched from therapy with long-acting somatostatin analogs to pegvisomant. The effect of changing therapies on glucose homeostasis and safety has not been reported. OBJECTIVES: The objectives of this study were to monitor changes in IGF-I levels, glycemic control, and safety, particularly liver function and tumor size. DESIGN: This was a multicenter, open-label, 32-wk trial study. SETTING: The study was performed at outpatient clinics. PATIENTS: Fifty-three patients with acromegaly previously treated with octreotide long-acting release (LAR) participated in this study. Intervention: Pegvisomant (10 mg/d) was initiated 4 wk after the last dose of octreotide LAR and was adjusted based on serum IGF-I concentrations at wk 12, 20, and 28. MAIN OUTCOME MEASURES: The main outcome measures were changes in IGF-I, glycosylated hemoglobin A1c (HbA1c), fasting plasma glucose, and safety during the first 12 wk after conversion. RESULTS: At the end of pegvisomant treatment, IGF-I was normalized in 78% of patients. At wk 32, median fasting glucose concentration and HbA1c were reduced (-1.4 mmol/liter and -0.4%, respectively; both P < or = 0.0001) in the study population. Improvements in glycemic control occurred in patients with normal IGF-I concentrations at wk 4 [n = 15; fasting glucose, -1.7 mmol/liter (P < or = 0.0001); HbA1c -0.2% (P = 0.03)]. Decreases in fasting glucose and HbA1c levels were observed in patients with and without diabetes. HbA1c was reduced by more than 1.0% in patients with diabetes. Median pituitary tumor volume did not change, although tumor volume increased in two patients with macroadenomas. CONCLUSIONS: Conversion from octreotide LAR to pegvisomant was safe and well tolerated. Improved glycemic control indicates that pegvisomant should be considered in patients with acromegaly and diabetes.     

Phospholipase A2 levels in acute chest syndrome of sickle cell disease

Acute chest syndrome (ACS) is associated with significant morbidity and is the leading cause of death in patients with sickle cell disease (SCD). Recent reports suggest that bone marrow fat embolism can be detected in many cases of severe ACS. Secretory phospholipase A2 (sPLA2) is an important inflammatory mediator and liberates free fatty acids, which are felt to be responsible for the acute lung injury of the fat embolism syndrome. We measured SPLA2 levels in 35 SCD patients during 20 admissions for ACS, 10 admissions for vaso-occlusive crisis, and during 12 clinic visits when patients were at the steady state. Eleven non-SCD patients with pneumonia were also evaluated. To determine if there was a relationship between sPLA2 and the severity of ACS we correlated SPLA2 levels with the clinical course of the patient. In comparison with normal controls (mean = 3.1 +/- 1.1 ng/mL), the non- SCD patients with pneumonia (mean = 68.6 +/- 82.9 ng/mL) and all three SCD patient groups had an elevation of SPLA2 (steady state mean = 10.0 +/- 8.4 ng/mL; vaso-occlusive crisis mean = 23.7 +/- 40.5 ng/mL; ACS mean = 336 +/- 209 ng/mL). In patients with ACS sPLA2 levels were 100- fold greater than normal control values, 35 times greater than values in SCD patients at baseline, and five times greater than non-SCD patients with pneumonia. The degree of SPLA2 elevation in ACS correlated with three different measures of clinical severity and, in patients followed sequentially, the rise in SPLA2 coincided with the onset of ACS. The dramatic elevation of SPLA2 in patients with ACS but not in patients with vaso-occlusive crisis or non-SCD patients with pneumonia and the correlation between levels of SPLA2 and clinical severity suggest a role for SPLA2 in the diagnosis and, perhaps, in the pathophysiology of patients with ACS.     

The influence of gender on the short and long-term effects of growth hormone replacement on bone metabolism and bone mineral density in hypopituitary adults: a 5-year study

OBJECTIVES: The objectives of this study were to investigate the effects of GH replacement therapy in hypopituitary adults with growth hormone deficiency (GHD) on activation of bone remodelling during dose titration and on BMD over a median of 58 months of continuous therapy. STUDY DESIGN: Open label study in adult patients with GHD. rhGH was commenced at dose of 0.8 IU subcutaneously daily (0.4 IU if hypertensive or glucose tolerance impaired) with subsequent dose titration based on 2 weekly measurement of serum IGF-I until levels reached the target range (between the median and upper end of the age related reference range). In patients previously commenced on GH using weight based regimens the dose of GH was adjusted during clinical follow-up in order to maintain serum IGF-I in the target range. PATIENTS: Initial effects of GH on bone remodelling during dose titration were studied in 17 patients (8F). Long-term effects of GH were determined in a separate group of 13 GHD adults (6F) over a median period of 58 months (range 44-72). MEASUREMENTS: Osteoblastic activity was estimated by measuring serum bone specific alkaline phosphatase (S-BAP). BMD was determined at both lumbar spine (L2-L4) and femoral neck by dual energy X-ray absorptiometry (DEXA). RESULTS: During dose titration a significant increment in S-BAP was observed by 10 weeks in females but occurred later in males (12-26 weeks). In the long term treatment group there was a significant increment in S-BAP compared to baseline (P = 0.013) after 6 months GH treatment. After long-term GH treatment (median 58 months) S-BAP levels decreased and were no longer statistically significantly different from baseline at the end of the study period. A similar response was observed in male and female patients. There were no significant differences in baseline BMD between male and female patients at either lumbar spine or femoral neck in the long term treatment group. No significant changes were observed in BMD after 6 months GH treatment in either lumbar spine or femoral neck but BMD increased over the remainder of the study at both sites (P = 0.023 and P = 0.03 respectively). When analysed by gender male patients showed a clear positive change in BMD after longer-term replacement in both lumbar spine and femoral neck (P = 0.01 and P = 0.02 respectively) but female patients showed no significant changes. Qualitatively similar results were observed when analysing changes in BMD expressed as Z scores. CONCLUSION: This study demonstrates an earlier onset of GH activation of bone remodelling as reflected by S-BAP in females compared to males and confirms that long-term GH treatment in hypopituitary adults with GH deficiency increases or preserves BMD both at lumbar spine and femoral neck. However male patients seem to derive the greater benefits in BMD from long-term GH replacement; in females BMD appears simply to be stabilized rather than increased. This constitutes a genuine gender difference in susceptibility given that serum IGF-I was in the upper part of the reference range in all subjects.     

Genetic and environmental control of host-gut microbiota interactions

Genetics provides a potentially powerful approach to dissect host-gut microbiota interactions. Toward this end, we profiled gut microbiota using 16s rRNA gene sequencing in a panel of 110 diverse inbred strains of mice. This panel has previously been studied for a wide range of metabolic traits and can be used for high-resolution association mapping. Using a SNP-based approach with a linear mixed model, we estimated the heritability of microbiota composition. We conclude that, in a controlled environment, the genetic background accounts for a substantial fraction of abundance of most common microbiota. The mice were previously studied for response to a high-fat, high-sucrose diet, and we hypothesized that the dietary response was determined in part by gut microbiota composition. We tested this using a cross-fostering strategy in which a strain showing a modest response, SWR, was seeded with microbiota from a strain showing a strong response, A×B19. Consistent with a role of microbiota in dietary response, the cross-fostered SWR pups exhibited a significantly increased response in weight gain. To examine specific microbiota contributing to the response, we identified various genera whose abundance correlated with dietary response. Among these, we chose Akkermansia muciniphila, a common anaerobe previously associated with metabolic effects. When administered to strain A×B19 by gavage, the dietary response was significantly blunted for obesity, plasma lipids, and insulin resistance. In an effort to further understand host-microbiota interactions, we mapped loci controlling microbiota composition and prioritized candidate genes. Our publicly available data provide a resource for future studies.Studies carried out over the last decade have revealed that gut microbiota contribute to a variety of common disorders, including obesity and diabetes (Musso et al. 2011), colitis (Devkota et al. 2012), atherosclerosis (Wang et al. 2011), rheumatoid arthritis (Vaahtovuo et al. 2008), and cancer (Yoshimoto et al. 2013). The evidence for metabolic interactions is particularly strong, as a large body of data now supports the conclusion that gut microbiota influence the energy harvest from dietary components, particularly complex carbohydrates, and that metabolites such as the short-chain fatty acids produced by gut bacteria can perturb metabolic traits, including adiposity and insulin resistance (Turnbaugh et al. 2006, 2009; Backhed et al. 2007; Wen et al. 2008; Ridaura et al. 2013). Gut microbiota communities are assembled each generation, influenced by maternal seeding, environmental factors, host genetics, and age, resulting in substantial variations in composition among individuals in human populations (Eckburg et al. 2005; Costello et al. 2009; Human Microbiome Project Consortium 2012; Goodrich et al. 2014). Most experimental studies of host-gut microbiota interactions have employed large perturbations, such as comparisons of germ-free versus conventional mice, and the significance of common variations in gut microbiota composition for disease susceptibility is still poorly understood. Furthermore, while studies with germ-free mice have clearly implicated microbiota in clinically relevant traits, it has proven difficult to identify the responsible taxa of bacteria.We now report a population-based analysis of host-gut microbiota interactions in the mouse. One of the issues we explore is the role of host genetics. Although some evidence is consistent with significant heritability of gut microbiota composition, the extent to which the host controls microbiota composition under controlled environmental conditions is unclear. We also examined the role of common variations in gut microbiota in metabolic traits such as obesity and insulin resistance and mapped loci contributing to the abundance of certain microbiota. We performed our study using a resource termed the Hybrid Mouse Diversity Panel (HMDP), consisting of about 100 inbred strains of mice that have been either sequenced or subjected to high-density genotyping (Bennett et al. 2010). The resource has several advantages for genetic analysis as compared to traditional genetic crosses. First, it allows high-resolution mapping by association rather than linkage analysis, and it has now been used for the identification of a number of novel genes underlying complex traits (Farber et al. 2011; Lavinsky et al. 2015; Parks et al. 2015; Rau et al. 2015). Second, since the strains are permanent, the data from separate studies can be integrated, allowing the development of large, publicly available databases of physiological and molecular traits relevant to a variety of clinical disorders (systems.genetics.ucla.edu and phenome.jax.org). Third, the panel is ideal for examining gene-by-environment interactions, since it is possible to examine individuals of a particular genotype under a variety of conditions (Orozco et al. 2012; Parks et al. 2013).     

Review: Head and neck squamous cell carcinoma in sub-Saharan Africa

Aim

Review the literature from 1990 to 2013 to determine known anatomic sites, risk factors, treatments, and outcomes of head and neck squamous cell carcinoma (HNSCC) in sub-Saharan Africa.

Methods

Using a systematic search strategy, literature pertaining to HNSCC in sub-Saharan Africa was reviewed and patient demographics, anatomic sites, histology, stage, treatment, and outcomes were abstracted. The contributions of human immunodeficiency virus (HIV), human papillomavirus (HPV) and behavioural risk factors to HNSCC in the region were assessed.

Results

Of the 342 papers identified, 46 were utilized for review, including 8611 patients. In sub-Saharan Africa, the oropharyngeal/oral cavity was found to be the most common site, with 7750 cases (90% of all cases). Few papers distinguished oropharyngeal from oral cavity, making identification of possible HPV-associated oropharyngeal squamous cell carcinoma (SCC) difficult. SCC of the nasopharynx, nasal cavity, or paranasal sinuses was identified in 410 patients (4.8% of all cases). Laryngeal SCC was found in 385 patients (4.5% of all cases), and only 66 patients (0.8% of all cases) with hypopharyngeal SCC were identified. In 862 patients with data available, 43% used tobacco and 42% used alcohol, and reported use varied widely and was more common in laryngeal SCC than that of the oropharyngeal/oral cavity. Toombak and kola nut use was reported to be higher in patients with HNSCC. Several papers reported HIV-positive patients with HNSCC, but it was not possible to determine HNSCC prevalence in HIV-positive compared to negative patients. Reports of treatment and outcomes were rare.

Conclusions

The oropharyngeal/oral cavity was by far the most commonly reported site of HNSCC reported in sub-Saharan Africa. The roles of risk factors in HNSCC incidence in sub-Saharan Africa were difficult to delineate from the available studies, but a majority of patients did not use tobacco and alcohol.