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Secretion of hormones and peptides by neuroendocrine cells occurs through fast and slow modes of vesicle fusion but the mechanics of these processes are not understood. We used interference reflection microscopy to monitor deformations of the membrane surface and found that both modes of fusion involve the tightly coupled dilation and constriction of the vesicle. The rate of opening is calcium dependent and occurs rapidly at concentrations <5 microM. The fast mode of fusion is blocked selectively by a truncation mutant of amphiphysin. Vesicles do not collapse when fusion is triggered by strontium, rather they remain locked open and membrane scission is blocked. In contrast, constriction of the vesicle opening continues when endocytosis is blocked by inhibiting the function of dynamin. Thus, fast and slow modes of fusion involve similar membrane deformations and vesicle closure can be uncoupled from membrane scission. Regulation of these processes by calcium and amphiphysin may provide a mechanism for controlling the release of vesicle contents.
J Gen Physiol 2008 Oct
PMID:The mouth of a dense-core vesicle opens and closes in a concerted action regulated by calcium and amphiphysin. 1877 74

Congenital tracheal stenosis (CTS) is a rare but life-threatening disorder, particularly in neonates and infants. The stenotic lesions are commonly composed of complete rings of cartilage varying in length, location, and severity. A definitive diagnosis of CTS may be delayed because of the rarity of this disorder and thus its unfamiliarity among physicians, its variable onset time, its various clinical symptoms, and the diversity of associated clinical conditions due to the cardiovascular disorders that may accompany it. More than half of the patients who manifest clinical symptoms during early infancy show a long-segment stenosis. Long-segment CTS is problematic and challenging to manage. Over the last two decades several surgical techniques for long-segment CTS have been devised and developed, but no definitively advantageous surgical procedure has been established because of insufficient experience and the lack of large-scale studies. Although rib cartilage tracheoplasty and pericardial patch tracheoplasty have provided limited early to midterm success for infants with long-segment CTS, these procedures are associated with early and late complications, including granulation tissue formation, patch collapse, and restenosis necessitating reintervention. By contrast, slide tracheoplasty has given rise to better surgical outcomes. This procedure enables reconstruction of the stenotic trachea using native tracheal walls with preserved blood supply. The trachea is foreshortened by only one-half of the original stenosis, resulting in reduced tension on the anastomosis. Consequently, the technique has several advantages, including less formation of granulation tissue, satisfactory subsequent growth, and infrequent reoperation for restenosis. Slide tracheoplasty is currently recognized as the preferred technique for long-segment CTS.
Gen Thorac Cardiovasc Surg 2009 Apr
PMID:Surgical management of congenital tracheal stenosis. 2015 51

Slow inactivation of Kv1 channels involves conformational changes near the selectivity filter. We examine such changes in Shaker channels lacking fast inactivation by considering the consequences of mutating two residues, T449 just external to the selectivity filter and V438 in the pore helix near the bottom of the selectivity filter. Single mutant T449F channels with the native V438 inactivate very slowly, and the canonical foot-in-the-door effect of extracellular tetraethylammonium (TEA) is not only absent, but the time course of slow inactivation is accelerated by TEA. The V438A mutation dramatically speeds inactivation in T449F channels, and TEA slows inactivation exactly as predicted by the foot-in-the-door model. We propose that TEA has this effect on V438A/T449F channels because the V438A mutation produces allosteric consequences within the selectivity filter and may reorient the aromatic ring at position 449. We investigated the possibility that the blocker promotes the collapse of the outer vestibule (spring-in-the-door) in single mutant T449F channels by an electrostatic attraction between a cationic TEA and the quadrupole moments of the four aromatic rings. To test this idea, we used in vivo nonsense suppression to serially fluorinate the introduced aromatic ring at the 449 position, a manipulation that withdraws electrons from the aromatic face with little effect on the shape, net charge, or hydrophobicity of the aromatic ring. Progressive fluorination causes monotonically enhanced rates of inactivation. In further agreement with our working hypothesis, increasing fluorination of the aromatic gradually transforms the TEA effect from spring-in-the-door to foot-in-the-door. We further substantiate our electrostatic hypothesis by quantum mechanical calculations.
J Gen Physiol 2009 Dec
PMID:An electrostatic interaction between TEA and an introduced pore aromatic drives spring-in-the-door inactivation in Shaker potassium channels. 1991 31

Ca(2+)/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca(2+) channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within Ca(V)1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a "hinged lid-shield" mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a "shield" in Ca(V)1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca(2+) channelopathies involving S6 mutations.
J Gen Physiol 2010 Mar
PMID:Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Ca(v)1.3 channels. 2019 3

A 16-year-old boy was hospitalized for fever, chest pain, and cardiovascular collapse. Transthoracic echocardiography revealed a 30-mm circumferential echogenic "porridge-like" pericardial effusion with signs of cardiac tamponade. Tuberculosis (TB) was suspected because of its prevalence in Djibouti. Emergency pericardiocentesis was attempted, but only 10 ml of pericardial fluid was obtained. Subxiphoid pericardiotomy and drainage were then performed, and pericardial fibrinous pockets were surgically collapsed. Antituberculosis chemotherapy was given, and the pericardial effusion progressively disappeared without corticosteroids. The diagnosis of TB was subsequently confirmed by cultures of the pericardial fluid. A pericardial biopsy was normal. After 3 months of follow-up, there was no sign of constrictive pericarditis. Pericardiocentesis may fail in cases of advanced-stage fibrinous TB pericardial effusion. Thus, pericardiotomy with complete open draining is the only lifesaving procedure.
Gen Thorac Cardiovasc Surg 2010 Jun
PMID:Porridge-like tuberculous cardiac tamponade: treatment difficulties in the Horn of Africa. 2054 56

The Israeli acute paralysis virus (IAPV) is a significant marker of honeybee colony collapse disorder (CCD). In the present work, we provide the first evidence that Varroa destructor is IAPV replication-competent and capable of vectoring IAPV in honeybees. The honeybees became infected with IAPV after exposure to Varroa mites that carried the virus. The copy number of IAPV in bees was positively correlated with the density of Varroa mites and time period of exposure to Varroa mites. Further, we showed that the mite-virus association could possibly reduce host immunity and therefore promote elevated levels of virus replication. This study defines an active role of Varroa mites in IAPV transmission and sheds light on the epidemiology of IAPV infection in honeybees.
J Gen Virol 2011 Jan
PMID:Varroa destructor is an effective vector of Israeli acute paralysis virus in the honeybee, Apis mellifera. 2092 37

Descending necrotizing mediastinitis (DNM) is a rare, highly fatal disease that occurs as a complication of a cervical or odontogenic infection spreading into the mediastinum. We herein report of a 50-year-old man with DNM and severe thoracic emphysema who was successfully treated using surgical drainage by video-assisted thoracoscopic surgery (VATS) and a transcervical approach. Chest enhanced computed tomography on admission revealed massive left pleural effusion, pneumothorax, absolute collapse of the left lung, and a mediastinal shift to the right side with emphysema. We urgently performed left thoracic and mediastinal drainage using VATS. Retropharyngeal and upper mediastinal drainage was performed transcervically on the third hospital day. He recovered and was discharged on hospital day 57. Surgical drainage is the most important therapy in the treatment of DNM, but there is no standard surgical approach. We believe that VATS is a less invasive, effective modality for draining the posterior mediastinum.
Gen Thorac Cardiovasc Surg 2010 Nov
PMID:Successful treatment for descending necrotizing mediastinitis with severe thoracic emphysema using video-assisted thoracoscopic surgery. 2106 99

In 2001, the sudden collapse of the Columbia Basin population of pygmy rabbits prompted the initiation of a captive breeding program to facilitate reintroduction, but reproductive success in captivity has not met expectations. Therefore, the objective of this study was to characterize the reproductive and adrenal endocrinology of this endangered rabbit species so that appropriate management strategies could be developed to monitor animal welfare and increase reproduction. Fecal samples were collected from 27 female pygmy rabbits over three breeding and non-breeding seasons. HPLC analyses verified the presence of progesterone in the excreta of pygmy rabbits, but the majority of progestagen metabolites were unidentified polar compounds. By contrast, >70% of glucocorticoid immunoactivity was associated with cortisol. Longitudinal fecal hormone profiles during pregnancy were characterized by a large spike in progestagens shortly after mating, a gradual increase in progestagen and glucocorticoid concentrations throughout gestation and a return of hormones to baseline soon after birth (Day 24). The spike in progestagens 1 day after mating was a significant discovery for this species and appears to provide a reliable means of determining if a successful mating has occurred. Seasonal analyses of hormone excretion found that progestagen baselines did not vary between the breeding and non-breeding seasons, but, as expected, were highest during the breeding season in association with pregnancy. Across seasons, the lowest concentrations of glucocorticoids were associated with the highest rates of offspring production and survival, suggesting a possible link between heightened adrenal activity and lowered reproductive fitness in pygmy rabbits.
Gen Comp Endocrinol 2011 May 01
PMID:Characterizing gonadal and adrenal activity by fecal steroid analyses in pygmy rabbits (Brachylagus idahoensis). 2137 69

A 63-year-old woman, who presented with severe jaundice and elevated serum conjugated bilirubin level, denied alcohol and drug use and showed no evidence of viral hepatitis. Based on clinical and laboratory features, she was diagnosed with autoimmune hepatitis with primary biliary cirrhosis. Hematological and immunochemical assays, radiographic imaging, clinical examination, and liver biopsy were conducted. Laboratory results were the following: negative for fluorescence antinuclear antibody, negative for antismooth muscle antibodies but positive for antinuclear antibody (enzyme-linked immunosorbent assay) and antimitochondrial M2 antibody, high titers of serum globulin, and positive for cytomegalovirus IgM. Liver biopsy showed submassive lobular necrosis, inflammation with broad areas of parenchymal collapse, and chronic nonsuppurative destructive cholangitis. The patient responded well to corticosteroid therapy. This case might illustrate an association between cytomegalovirus infection and the occurrence of autoimmune hepatitis.
Int J Gen Med 2011
PMID:Association of an overlap syndrome of autoimmune hepatitis and primary biliary cirrhosis with cytomegalovirus infection. 2173 90

A biosurfactant-producing and hydrocarbon-utilizing bacterium, Pseudomonas aeruginosa USM-AR2, was used to assist conventional distillation. Batch cultivation in a bioreactor gave a biomass of 9.4 g L(-1) and rhamnolipid concentration of 2.4 g L(-1) achieved after 72 h. Biosurfactant activity (rhamnolipid) was detected by the orcinol assay, emulsification index and drop collapse test. Pretreatment of crude oil TK-1 and AG-2 with a culture of P. aeruginosa USM-AR2 that contains rhamnolipid was proven to facilitate the distillation process by reducing the duration without reducing the quality of petroleum distillate. It showed a potential in reducing the duration of the distillation process, with at least 2- to 3-fold decreases in distillation time. This is supported by GC-MS analysis of the distillate where there was no difference between compounds detected in distillate obtained from treated or untreated crude oil. Calorimetric tests showed the calorie value of the distillate remained the same with or without treatment. These two factors confirmed that the quality of the distillate was not compromised and the incubation process by the microbial culture did not over-degrade the oil. The rhamnolipid produced by this culture was the main factor that enhanced the distillation performance, which is related to the emulsification of hydrocarbon chains in the crude oil. This biotreatment may play an important role to improve the existing conventional refinery and distillation process. Reducing the distillation times by pretreating the crude oil with a natural biosynthetic product translates to energy and cost savings in producing petroleum products.
J Gen Appl Microbiol 2012
PMID:Rhamnolipid produced by Pseudomonas aeruginosa USM-AR2 facilitates crude oil distillation. 2268 47


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