Search Results - (Author, Cooperation:R. Chow)

2015-07-07

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Cell Communication ; Cell Differentiation ; Cell Division ; Cilia/metabolism ; Female ; Male ; Membrane Proteins/metabolism ; Mice ; Receptor, Notch2/metabolism ; Signal Transduction ; Stem Cell Niche/*physiology ; Stem Cells/*cytology/metabolism/secretion ; Trachea/cytology

2018-01-05

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

1365-3083

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Profound secretory dysfunction can be associated with relatively modest lymphocytic infiltration of the lacrimal and salivary glands of Sjögren's syndrome (SjS) patients. SjS patients' sera contain autoantibodies to M3 muscarinic acetylcholine receptors (MAChR) that have variously been reported to have agonistic and antagonistic effects. We sought to identify consequences of chronic agonist stimulation by maintaining acinar cells from rabbit lacrimal glands for 20 h in the presence or absence of 10 µm carbachol (CCh). Exposure to CCh diminished the cells' ability to elevate cytosolic Ca2+ and secrete β-hexosaminidase in response to acute stimulation with 100 µm CCh, but it enhanced their secretory responses to phenylephrine and ionomycin. Secretory vesicles appeared normal by electron microscopy, but confocal fluorescence microscopy revealed depletion of the secretory vesicle membrane marker, rab3D, and decreased ability to recruit secretory transport vesicles in response to acute 100 µm CCh. Additionally, the apical cortical actin cytoskeleton was disrupted and diminished compared to the basal–lateral cortical network. Subcellular fractionation analyses revealed that total membrane phase protein content was increased. The contents of β-hexosaminidase and MAChR relative to total protein were not significantly altered, and MAChR abundance in the plasma membrane fraction was increased as the result of redistribution from endomembrane pools. However, relative cellular contents of the heterotrimeric guanosine triphosphate (GTP)-binding proteins, Gq and G11, were decreased. Additional biochemical changes included decreased contents of 47 kDa Gs and Gi3, protein kinase Cα and rab3D and polymeric immunoglobulin (Ig) receptors; internalization of Na,K-ATPase from the plasma membranes to endomembrane compartments and decreased content of β-hexosaminidase in the lysosomes. The observations demonstrate that chronic exposure to a MAChR agonist induces refractoriness to optimal stimulation, without causing receptor downregulation, by downregulating postreceptor-signalling mediators and effectors. The cells' secretory mechanisms for IgA and electrolytes also appear to be impaired, as does their ability to properly sort proteins to the lysosomes.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

A novel electrochemical technique was developed to enable high-resolution measurements of trans-plasma membrane reductase activity in vivo in growing plant tissue and single cells. Carbon fibre microelectrodes (CFMEs) with a tip diameter of 5 µm were used for electrochemical mapping of the reduction of the external impermeant electron acceptor ferricyanide along the root tip surface of 4-d-old maize seedlings. Ferricyanide reduction was detected in all locations along the first 12 mm of the growing root apex. However, a distinct peak in activity was detected at the proximal end of the elongation zone (1·5–4·5 mm from the apex), where reductase activity was three times greater than in more apical or distal regions. The inhibition of the ferricyanide reduction at all locations along the growing apex, by the vitamin K antagonists warfarin and dicumarol, supports previous data showing that electron transfer by the constitutive trans-plasma membrane reductase is achieved via a quinone shuttle. We demonstrate that in addition to their utility in whole-tissue/-organ studies, CFMEs are sensitive enough to monitor trans-plasma membrane electron transport in single cells.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary A case of graft-vs.-host disease (GVHD) arising solely within an area affected by piebaldism is described. The patient, a 35-year-old woman with a single hypopigmented patch on the right leg present since birth, had received an allogeneic bone marrow transplant (BMT) from an HLA-identical sibling donor, for treatment of a myelodysplastic syndrome (MDS). Beginning on day + 38 post-BMT, the patch developed changes which were histologically consistent with GVHD. Syngeneic mixed epidermal cell-lymphocyte reaction (MECLR) testing of tissue from the patch, and from adjacent normal skin, showed differences which suggest that piebaldism-affected skin is immunologically different from normal skin. These findings may offer new insight into the pathophysiology of this disorder.

Electronic Resource

0040-6090

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0040-6090

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

0169-4332

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1433-2965

Bone mass ; Exercise ; Osteoporosis

Springer Online Journal Archives 1860-2000

Medicine

Abstract The value of a program for the rehabilitation of osteoporotic patients (PRO) was assessed from a 4-year follow up of 139 patients referred to the program over its initial 2 years of operation. The program consisted of educational seminars, social activities and regular exercise supervision. Patients had annual clinical assessments, and bone mass measurements by neutron activation analysis (reported as CaBI). Fitness was assessed by performance on a treadmill (reported in terms of VO2 max, ml/kg/min). Seventy-eight of the 139 patients remained in the program over the 4-year follow-up. This unusually high level of commitment to the program is indicative of the psychological value that patients have derived from it. The effect of the program on the osteoporosis process was inconclusive. Group 2, the 37 patients who obtained the greatest improvement in fitness (VO 2max 〉6 ml/kg/min), had a significantly greater reduction in back pain than did group 1, the 36 with less significant improvement (VO 2max 〉6 ml/kg/min). The bone mass and incidence of vertebral fractures on entry into the program were not significantly different between the two groups. Group 2 had on average a greater increase in bone mass over the 4 years; mean increases in CaBI, (±SD) were 0.09±0.09 and 0.05±0.10 for groups 2 and 1 respectively. Group 2 had on average fewer new vertebral fractures (0.08±0.36 and 0.28±0.75 for groups 2 and 1 respectively). While these findings were encouraging, they did not reach significance at the 5% level (p=0.075 andp=0.09 for changes in CaBI and new vertebral fractures, respectively). A large randomized study would be required to establish clinical value quantitatively. Nevertheless, the qualitative benefit to patients is sufficiently impressive for a wider experience in rehabilitation programs to be encouraged.

Electronic Resource

1432-1017

Key words Total internal reflection ; Evanescent wave microscopy ; Optical sectioning ; Ca2+-triggered exocytosis ; Vesicle fusion

Springer Online Journal Archives 1860-2000

Biology

Physics

Abstract In neuroendocrine cells and neurones, changes in the size of a limited pool of readily releasable vesicles contribute to the plasticity of secretion. We have studied the dynamic alterations in the size of a near-membrane pool of vesicles in living neuroendocrine cells. Using evanescent wave microscopy we monitored the behaviour of individual secretory vesicles at the plasma membrane. Vesicles undergo sequential transitions between several states of differing fluorescence intensity and mobility. The transitions are reversible, except for the fusion step, and even in nonstimulated conditions the vesicles change states in a dynamic equilibrium. Stimulation selectively speeds up the three forward transitions leading towards exocytosis. Vesicles lose mobility in all three dimensions upon approach of the plasma membrane. Their movement is directed and targeted to the docking fusion sites. Sites of vesicle docking and exocytosis are distributed non-uniformly over the studied “footprint” region of the cell. While some areas are the sites of repeated vesicle docking and fusion, others are completely devoid of spots. Vesicular mobility at the membrane is confined, as if the vesicle were imprisoned in a cage or tethered to a binding site.

Electronic Resource

1439-6327

Key words Gastrocnemius ; Gender ; Muscle architecture ; Soleus ; Ultrasound

Springer Online Journal Archives 1860-2000

Medicine

Abstract The purpose of this study was to establish if there are gender differences in muscle architecture in relaxed human soleus and gastrocnemius muscles of normal, live subjects. Ultrasonography was used to measure fiber bundle length, muscle thickness, and angles of pennation in a total of ten predetermined sites in the medial and lateral heads of gastrocnemius and the anterior and posterior soleus in 19 males and 16 females. Percentage differences between males and females for each parameter were recorded. Gender differences were statistically analyzed using multivariate analysis of variance. In the gastrocnemius and soleus muscles of males and females the differences between the overall fiber bundle length, angle of pennation and muscle thickness were statistically significant (P 〈 0.05). Overall, females were found to have longer average muscle fiber bundle length and males thicker muscles and larger angles of pennation. The greatest percentage differences of the architectural parameters between males and females were in the posterior soleus: 13% difference in fiber length and 26% difference in angle of pennation in the midline of posterior soleus and 26% difference in muscle thickness of the lateral part of posterior soleus. No correlation was found between leg length and fiber length, angle of pennation or muscle thickness. Fiber length (decreased), angle of pennation (greater) and muscle thickness (greater) of most parts of the gastrocnemius and soleus muscles were significantly different in males and females. Leg length of males and females did not correlate to these architectural parameters.

Electronic Resource

1439-6327

Key words Bone mineral density ; Cross-efficacy ; Energy expenditure ; Fractures ; Physical activity

Springer Online Journal Archives 1860-2000

Medicine

Abstract The efficacy of an exercise program was investigated in a study of 89 post-menopausal women with osteoporosis over a 5-year follow-up period. The study attempted to examine and compare potential differences in bone mineral density (BMD), incidence of fracture, and loss of height, between a group of patients (n=42) who attended the supervised exercise program in the hospital, and a group (n=47) who exercised at home. Habitual physical activity, as estimated using the Harvard Alumni Questionnaire, and a Physical Activity Index were combined to obtain an estimate of overall weekly caloric expenditure over the 5-year period. The exercise program involved weight-bearing aerobic activities of moderate intensity, and muscle strengthening exercise using free weights. The mean percentage change for the lumbar BMD was +4.4% in the hospital group and +3.4% in the home group while for the femoral neck BMD was +1.1% in the hospital group and −0.9% in the home group. There was a significant reduction in the number of fractures and no significant loss of height over the 5-year follow-up period for both groups. As the correlation between BMD and weekly caloric expenditure of the subjects was not significant, no conclusion can be drawn as to the minimum level of caloric expenditure necessary in order to retard bone loss. It was concluded that for the post-menopausal women with osteoporosis who participated in the program it was possible to stabilize their height and the BMD of the lumbar site, and to reduce fractures over the 5-year study period regardless if they exercised in a supervised or in an unsupervised setting.

Electronic Resource

0021-8995

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

The effect of water vapor on a polyimide has been investigated in the temperature region of -190 to 325°C using an automated torsion pendulum. A damping peak, TH2O developes at -122°C (1 Hz) in the thermomechanical spectra of the polymer which is due to water-polymer interactions. The peak intensifies as the humidity of the conditioning atmosphere, at both 30° and at 325°C, increases and attains a limiting value at about 3000 ppmv H2O. The process is reversible. It is concluded that the number of sites in the polymer for interaction with water is low and limited (〈0.3 molecule H2O per polymer repeat unit) and, assuming direct proportionality between the intensity of the loss peak and the amount of water adsorbed, that the adsorption of water vapor follows the Langmuir isotherm.

10 Ill.

Electronic Resource