Davis, Ashlee, Brent Sinopoli, Nathaniel Mann, and Antine E. Stenbit. A photographic case of frostbite treated with delayed hyperbaric oxygen therapy. High Alt Med Biol. 23:194-197, 2022.-A 50-year-old female presented to the emergency department in June 2019 5 days after summiting Denali. Temperature on summit day was -25°F, and she developed frostbite on multiple digits of both hands. Eight digits demonstrated severe frostbite based on the grading set forth by Cauchy et al. Five of these had grade III injuries. She received three hyperbaric dives in Alaska before flying to her home state. On day 5 she received aspirin, aloe wraps, and underwent twenty-seven 90-minute dives at 2 atmospheres absolute. Unique in current literature, each dive was accompanied by photographs detailing clinical progression, which may assist providers in providing expectations in care. She eventually underwent amputation at, or distal to, the distal interphalangeals of bilateral third and fourth digits and the left fifth digit. By January 2020, she had returned to near-normal range of motion. Hyperbaric oxygen therapy represents a potential adjunct therapeutic option for frostbite, even in delayed manner, but its use as a treatment modality warrants further prospective analysis.

Bronchobiliary fistula (BBF) is a rare disease defined by passage of bile between the biliary and bronchial trees. Fistula development is associated with biliary obstruction and suppurative inflammation. 1. Gugenheim J. Ciardullo M. Traynor O. et al. Bronchobiliary fistulas in adults. Ann Surg. 1988; 207: 90-94 Crossref PubMed Scopus (89) Google Scholar Bile or gallstones may travel through the fistulous tract, causing bilioptysis or cholelithoptysis, respectively, both pathognomonic for BBF.

The mechanisms for the development of bronchiectasis and airway hyperreactivity have not been fully elucidated. Although genetic, acquired diseases and environmental influences may play a role, it is also possible that motile cilia can influence this disease process. We hypothesized that deletion of a key intraflagellar transport molecule, IFT88, in mature mice causes loss of cilia, resulting in airway remodeling. Airway cilia were deleted by knockout of IFT88, and airway remodeling and pulmonary function were evaluated. In IFT88(-) mice there was a substantial loss of airway cilia on respiratory epithelium. Three months after the deletion of cilia, there was clear evidence for bronchial remodeling that was not associated with inflammation or apparent defects in mucus clearance. There was evidence for airway epithelial cell hypertrophy and hyperplasia. IFT88(-) mice exhibited increased airway reactivity to a methacholine challenge and decreased ciliary beat frequency in the few remaining cells that possessed cilia. With deletion of respiratory cilia there was a marked increase in the number of club cells as seen by scanning electron microscopy. We suggest that airway remodeling may be exacerbated by the presence of club cells, since these cells are involved in airway repair. Club cells may be prevented from differentiating into respiratory epithelial cells because of a lack of IFT88 protein that is necessary to form a single nonmotile cilium. This monocilium is a prerequisite for these progenitor cells to transition into respiratory epithelial cells. In conclusion, motile cilia may play an important role in controlling airway structure and function.

BackgroundAerosolized tobramycin inhalation solution (TIS) may be absorbed and result in measurable serum concentrations. We assessed the significance of TIS dosing in the latter portion of the IV dosing interval on the calculation of pharmacokinetic (PK) parameters and dosing.MethodsTwenty adult CF patients admitted to the hospital for treatment of a pulmonary exacerbation were enrolled. PK parameters of tobramycin were calculated before and after introduction of TIS, which was given 5–9h after the IV dose.ResultsNine patients had a clinically significant change in tobramycin trough concentration. Fourteen patients had a reduced calculated elimination rate constant after TIS administration, which may be misinterpreted as a decreased clearance of IV tobramycin.ConclusionTrough tobramycin concentrations were significantly influenced in some CF patients (45%), suggesting that timing of the inhaled dose should be considered when interpreting PK measures of IV tobramycin dosing.

Purpose of review The chronic infection and inflammation of cystic fibrosis (CF) lung disease causes a progressive decline of lung function resulting in daily symptoms such as cough and sputum production. There are intermittent episodes of acute worsening of symptoms, more commonly referred to as pulmonary exacerbations. Despite this being a common event, there is still no standardized definition of an exacerbation. A recent set of guidelines from the CF Foundation Pulmonary Therapies Committee on the treatment of exacerbations noted the paucity of data supporting commonly used therapies. This review describes our current understanding of pulmonary exacerbations and the therapies used to treat them. Recent findings The treatment of an exacerbation is intended to resolve the worsened symptoms and to restore the lung function that is commonly lost in the acute presentation. A most striking finding is the observation that for many patients there is no restoration of lung function, suggesting we either need better therapies to prevent exacerbations or better treatment of exacerbations. Summary We have established recommendations on specific treatment of a pulmonary exacerbation and have outlined the areas where we need better information on appropriate therapies. Once we have a standardized definition of an exacerbation, we can proceed with clinical trials of therapies specific for its treatment.

Cystic fibrosis (CF) is an autosomal recessive disorder which despite advances in medical care continues to be a life-limiting and often fatal disease. With increase in life expectancy of the CF population, bone disease has emerged as a common complication. Unlike the osteoporosis seen in postmenopausal population, bone disease in CF begins at a young age and is associated with significant morbidity due to fractures, kyphosis, increased pain, and decreased lung function. The maintenance of bone health is essential for the CF population during their lives to prevent pain and fractures but also as they approach lung transplantation since severe bone disease can lead to exclusion from lung transplantation. Early recognition, prevention, and treatment are key to maintaining optimal bone health in CF patients and often require a multidisciplinary approach. This article will review the pathophysiology, current clinical practice guidelines, and potential future therapies for treating CF-related bone disease.

Deletion of the intraflagellar transport protein, polaris, results in loss of cilia. The purpose of this study was to characterize the effects of polaris deletion on ciliated airway epithelial cells and lung parenchyma. Utilizing a conditional floxed ift88 allele under the control of the estrogen receptor, 8 cre+ and 7 (control) cre− adult mice were induced with tamoxifen. Both cre+ and cre− mice, at either 3 wks or 3 months post tamoxifen, appeared to be healthy. Weights were not different and lungs looked grossly normal. At both time points western blot and immunofluorescence (IF) revealed a > 80% loss of polaris in cre+ lungs. Utilizing acetylated‐alpha tubulin as a marker of cilia, IF demonstrated a dramatic loss of cilia in airways from cre+ mice. Interestingly, in cre+ lungs, there was hypertrophy of airway epithelial cells, with increased cytoplasmic blebbing, and a decreased number of goblet cells. In BAL fluid and in lung parenchyma there was evidence of an increased inflammatory response in lungs from cre+ mice and a greater number of reactive type II pneumocytes. These changes were greater at 3 months versus 3 wks in lungs from cre+ mice. These results suggest that loss of cilia leads to morphologic changes of airway epithelial cells and initiates an enhanced inflammatory response in lung parenchyma. This mouse model may serve as a means for defining the role of cilia in the pathophysiology of lung injury. NIH/VA

Polycystic kidney disease (PKD) is characterized by the growth of fluid‐filled cysts in the kidneys and other organs. These cysts arise from uncontrolled cellular proliferation, potentially resulting from dysfunctional cilia. We hypothesized that the mechanosensory action of cilia regulates cellular proliferation by limiting signaling through the mitogen‐activated protein kinase (MAPK) pathway. Immortalized collecting duct cell lines from the Oak Ridge mouse that is a hypomorph for the Tg737 gene [cilia (−) cells] or cells in which the Tg737 gene was reinserted [cilia (+) cells] were incubated in a stationary state or subjected to 12 hr of shear stress on a rotator. Analysis of proteins from cilia (+) cells subjected to rotation revealed cilia movement increased expression of the raf kinase inhibitor protein (RKIP) and decreased expression of downstream phosphorylated proteins in the MAPK pathway when compared to all other cells. In addition, renal cortex tissue obtained from adult Tg737 conditional floxed allele mice in which cilia had been knocked out for 3 weeks [cre (+)] or in which cilia were unaffected [cre (−)] was analyzed by western blot. We found that RKIP was significantly higher in renal tissue expressing cilia. These results suggest that flow‐induced bending of cilia suppresses cellular proliferation by controlling the MAPK signaling pathway. This work was supported by NIH grants and a VA Merit Award.

In adult cystic fibrosis patient populations, gram-negative bacteria, particularly Pseudomonas aeruginosa, frequently require aggressive therapy including systemic antibiotics, bronchodilators and airway clearance techniques. Aminoglycosides including tobramycin are used frequently to control these chronic airway infections. They, however, cause important nephrotoxic and ototoxic effects that can significantly alter the quality of life. We investigated the genetic predisposition to aminoglycoside ototoxicity in a typical unscreened North American cystic fibrosis population by screening for variants in mitochondrial 12S ribosomal RNA and noted several polymorphisms occurred at higher frequencies than expected and were associated with clinically significant cases of hearing loss. In the population studied, both patients possessing the 1555A>G transition exhibited profound ototoxicity after nontoxic dosing of tobramycin. We also identified new homoplasmic genetic variations in the mitochondrial 12S ribosomal RNA, several of which occurred in highly conserved regions of the gene and were present in patients with moderate-to-severe ototoxicity after exposure to aminoglycosides.

Expression of GLUT4 in fast-twitch skeletal muscle fibers of GLUT4 null mice (G4-MO) normalized glucose uptake in muscle and restored peripheral insulin sensitivity. GLUT4 null mice exhibit altered carbohydrate and lipid metabolism in liver and skeletal muscle. To test the hypothesis that increased glucose utilization by G4-MO muscle would normalize the changes seen in the GLUT4 null liver, serum metabolites and hepatic metabolism were compared in control, GLUT4 null, and G4-MO mice. The fed serum glucose and triglyceride levels of G4-MO mice were similar to those of control mice. In addition, the alternations in liver metabolism seen in GLUT4 nulls including increased GLUT2 expression and fatty acid synthesis accompanied by an increase in the oxidative arm of the pentose phosphate pathway were absent in G4-MO mice. The transgene used for GLUT4 restoration in muscle was specific for fast-twitch muscle fibers. The mitochondria hypertrophy/hyperplasia in all GLUT4 null skeletal muscles was absent in transgene-positive extensor digitorum longus muscle but present in transgene-negative soleus muscle of G4-MO mice. Results of this study suggest that the level of muscle GLUT4 expression influences mitochondrial biogenesis. These studies also demonstrate that the type and amount of substrate that muscle takes up and metabolizes, determined in part by GLUT4 expression levels, play a major role in directing hepatic carbohydrate and lipid metabolism.

A 47-year-old African American female with a history of asthma since childhood, stage IV sarcoidosis, and bilateral upper lobe aspergillomas was seen in follow-up for her multiple pulmonary disorders. She also had a history of frequent asthma exacerbations, an elevated total serum IgE level, and very high level positivity for serum Aspergillus precipitins. After several years of therapy with relatively high-dose corticosteroids and multiple antifungal agents for allergic bronchopulmonary aspergillosis, she had developed diabetes mellitus and osteoporosis and had gained over 60 pounds. Multiple prior attempts to wean her from corticosteroids had failed. The patient was subsequently started on omalizumab with significant clinical improvement and successful cessation of corticosteroid therapy. When she later temporarily discontinued omalizumab therapy for insurance reasons, she experienced symptomatic deterioration, which was promptly reversed upon reinitiation of this agent. We present this case to illustrate a novel and effective use of omalizumab (which inhibits IgE-mediated activation of mast cells and basophils) in a patient with multiple pulmonary disorders, including sarcoidosis, aspergillomas, asthma, and allergic bronchopulmonary aspergillosis.

Compartmentation and dynamics of cAMP and PKA signaling are important determinants of specificity among cAMP’s myriad cellular roles. Both cardiac inotropy and the progression of heart disease are affected by spatiotemporal variations in cAMP/PKA signaling, yet the dynamic patterns of PKA-mediated phosphorylation that influence differential responses to agonists have not been characterized. We performed live-cell imaging and systems modeling of PKA-mediated phosphorylation in neonatal cardiac myocytes in response to G-protein coupled receptor stimuli and UV photolysis of “caged” cAMP. cAMP accumulation was rate-limiting in PKA-mediated phosphorylation downstream of the β-adrenergic receptor. Prostaglandin E1 stimulated higher PKA activity in the cytosol than at the sarcolemma, whereas isoproterenol triggered faster sarcolemmal responses than cytosolic, likely due to restricted cAMP diffusion from submembrane compartments. Localized UV photolysis of caged cAMP triggered gradients of PKA-mediated phosphorylation, enhanced by phosphodiesterase activity and PKA-mediated buffering of cAMP. These findings indicate that combining live-cell FRET imaging and mechanistic computational models can provide quantitative understanding of spatiotemporal signaling.

Studies were conducted to explore altered substrate utilization and metabolism in GLUT4 null mice. Liver fatty acid synthase mRNA and fatty acid synthesis rates were dramatically increased in GLUT4 null mice compared with control mice and were supported by increased rates of the pentose phosphate pathway oxidative phase and sterol regulatory binding protein mRNA expression. Increased GLUT2 protein content, glucokinase mRNA, and glucose-6-phosphate in GLUT4 null mice may provide substrate for the enhanced fatty acid synthesis. Increased fatty acid synthesis, however, did not lead to hepatic triglyceride accumulation in GLUT4 null mice because of increased hepatic triglyceride secretion rates. GLUT4 null mice rapidly cleared orally administered olive oil, had reduced serum triglyceride concentrations in the fed and the fasted state, and increased skeletal muscle lipoprotein lipase when compared with controls. Oleate oxidation rates were increased in GLUT4 null skeletal muscle in association with mitochondrial hyperplasia/hypertrophy. This study demonstrated that GLUT4 null mice had increased hepatic glucose uptake and conversion into triglyceride for subsequent use by muscle. The ability of GLUT4 null mice to alter hepatic carbohydrate and lipid metabolism to provide proper nutrients for peripheral tissues may explain (in part) their ability to resist diabetes when fed a normal diet.

To understand the long-term metabolic and functional consequences of increased GLUT4 content, intracellular substrate utilization was investigated in isolated muscles of transgenic mice overexpressing GLUT4 selectively in fast-twitch skeletal muscles. Rates of glycolysis, glycogen synthesis, glucose oxidation, and free fatty acid (FFA) oxidation as well as glycogen content were assessed in isolated EDL (fast-twitch) and soleus (slow-twitch) muscles from female and male MLC-GLUT4 transgenic and control mice. In male MLC-GLUT4 EDL, increased glucose influx predominantly led to increased glycolysis. In contrast, in female MLC-GLUT4 EDL increased glycogen synthesis was observed. In both sexes, GLUT4 overexpression resulted in decreased exogenous FFA oxidation rates. The decreased rate of FFA oxidation in male MLC-GLUT4 EDL was associated with increased lipid content in liver, but not in muscle or at the whole body level. To determine how changes in substrate metabolism and insulin action may influence energy balance in an environment that encouraged physical activity, we measured voluntary training activity, body weight, and food consumption of MLC-GLUT4 and control mice in cages equipped with training wheels. We observed a small decrease in body weight of MLC-GLUT4 mice that was paradoxically accompanied by a 45% increase in food consumption. The results were explained by a marked fourfold increase in voluntary wheel exercise. The changes in substrate metabolism and physical activity in MLC-GLUT4 mice were not associated with dramatic changes in skeletal muscle morphology. Collectively, results of this study demonstrate the feasibility of altering muscle substrate utilization by overexpression of GLUT4. The results also suggest that as a potential treatment for type II diabetes mellitus, increased skeletal muscle GLUT4 expression may provide benefits in addition to improvement of insulin action.

GLUT4-null mice lacking the insulin-sensitive glucose transporter are not diabetic but do exhibit abnormalities in glucose and lipid metabolism. The most striking morphological consequence of ablating GLUT4 is cardiac hypertrophy. GLUT4-null hearts display characteristics of hypertrophy caused by hypertension. However, GLUT4-null mice have normal blood pressure and maintain a normal cardiac contractile protein profile. Unexpectedly, although they lack the predominant glucose transporter in the heart, GLUT4-null hearts transport glucose and synthesize glycogen at normal levels, but gene expression of rate-limiting enzymes involved in fatty acid oxidation is decreased. The GLUT4-null heart represents a unique model of hypertrophy that may be used to study the consequences of altered substrate utilization in normal and pathophysiological conditions.

Decreased GLUT4 expression, impaired insulin receptor (IR), IRS-1, and pp60/IRS-3 tyrosine phosphorylation are characteristics of adipocytes from insulin-resistant animal models and obese NIDDM humans. However, the sequence of events leading to the development of insulin signaling defects and the significance of decreased GLUT4 expression in causing adipocyte insulin resistance are unknown. The present study used male heterozygous GLUT4 knockout mice (GLUT4(+/-)) as a novel model of diabetes to study the development of insulin signaling defects in adipocytes with the progression of whole body insulin resistance and diabetes. Male GLUT4(+/-) mice with normal fed glycemia and insulinemia (N/N), normal fed glycemia and hyperinsulinemia (N/H), and fed hyperglycemia with hyperinsulinemia (H/H) exist at all ages. The expression of GLUT4 protein and the maximal insulin-stimulated glucose transport was 50% decreased in adipocytes from all three groups. Insulin signaling was normal in N/N adipose cells. From 35 to 70% reductions in insulin-stimulated tyrosine phosphorylation of IR, IRS-1, and pp60/IRS-3 were noted with no changes in the cellular content of IR, IRS-1, and p85 in N/H adipocytes. Insulin-stimulated protein tyrosine phosphorylation was further decreased to 12-23% in H/H adipose cells accompanied by 42% decreased IR and 80% increased p85 expression. Insulin-stimulated, IRS-1-associated PI3 kinase activity was decreased by 20% in N/H and 68% reduced in H/H GLUT4(+/-) adipocytes. However, total insulin-stimulated PI3 kinase activity was normal in H/H GLUT4(+/-) adipocytes. Taken together, these results strongly suggest that hyperinsulinemia triggers a reduction of IR tyrosine kinase activity that is further exacerbated by the appearance of hyperglycemia. However, the insulin signaling cascade has sufficient plasticity to accommodate significant changes in specific components without further reducing glucose uptake. Furthermore, the data indicate that the cellular content of GLUT4 is the rate-limiting factor in mediating maximal insulin-stimulated glucose uptake in GLUT4(+/-) adipocytes.

We have characterized the glucose-transport system in soleus muscle from female GLUT4-null mice to determine whether GLUT1, 3 or 5 account for insulin-stimulated glucose-transport activity. Insulin increased 2-deoxyglucose uptake 2.8- and 2.1-fold in soleus muscle from wild-type and GLUT4-null mice, respectively. Cytochalasin B, an inhibitor of GLUT1- and GLUT4-mediated glucose transport, inhibited insulin-stimulated 2-deoxyglucose uptake by >95% in wild-type and GLUT4-null soleus muscle. Addition of 35 mM fructose to the incubation media was without effect on insulin-stimulated 3-O-methylglucose transport activity in soleus muscle from either genotype, whereas 35 mM glucose inhibited insulin-stimulated (20 nM) 3-O-methylglucose transport by 65% in wild-type and 99% in GLUT4-null mice. We utilized the 2-N-4-1-(1-azi-2,2,2-triflu oroethyl)benzoyl-1, 3-bis(D-mannose-4-yloxy)-2-propylamine (ATB-BMPA) exofacial photolabel to determine if increased cell-surface GLUT1 or GLUT4 content accounted for insulin-stimulated glucose transport in GLUT4-null muscle. In wild-type soleus muscle, cell-surface GLUT4 content was increased by 2.8-fold under insulin-stimulated conditions and this increase corresponded to the increase in 2-deoxyglucose uptake. No detectable cell-surface GLUT4 was observed in soleus muscle from female GLUT4-null mice under either basal or insulin-stimulated conditions. Basal cell-surface GLUT1 content was similar between wild-type and GLUT4-null mice, with no further increase noted in either genotype with insulin exposure. Neither GLUT3 nor GLUT5 appeared to account for insulin-stimulated glucose-transport activity in wild-type or GLUT4-null muscle. In conclusion, insulin-stimulated glucose-transport activity in female GLUT4-null soleus muscle is mediated by a facilitative transport process that is glucose- and cytochalasin B-inhibitable, but which is not labelled strongly by ATB-BMPA.