Synaptic physiology and ultrastructure in comatose mutants define an in vivo role for NSF in neurotransmitter release

N-Ethylmaleimide-sensitive fusion protein (NSF) is a cytosolic protein thought to play a key role in vesicular transport in all eukaryotic cells. Although NSF was proposed to function in the trafficking of synaptic vesicles responsible for neurotransmitter release, only recently have in vivo experiments begun to reveal a specific function for NSF in this process. Our previous work showed that mutations in a Drosophila NSF gene, dNSF1, are responsible for the temperature-sensitive paralytic phenotype in comatose (comt) mutants. In this study, we perform electrophysiological and ultrastructural analyses in three different comt alleles to investigate the function of dNSF1 at native synapses in vivo. Electrophysiological analysis of postsynaptic potentials and currents at adult neuromuscular synapses revealed that in the absence of repetitive stimulation, comt synapses exhibit wild-type neurotransmitter release at restrictive (paralytic) temperatures. In contrast, repetitive stimulation at restrictive temperatures revealed a progressive, activity-dependent reduction in neurotransmitter release in comt but not in wild type. These results indicate that dNSF1 does not participate directly in the fusion of vesicles with the target membrane but rather functions in maintaining the pool of readily releasable vesicles competent for fast calcium-triggered fusion. To define dNSF1 function further, we used transmission electron microscopy to examine the distribution of vesicles within synaptic terminals, and observed a marked accumulation of docked vesicles at restrictive temperatures in comt. Together, the results reported here define a role for dNSF1 in the priming of docked synaptic vesicles for calcium-triggered fusion.     

Adenovirus-mediated delivery of rhodopsin-promoted bcl-2 results in a delay in photoreceptor cell death in the rd/rd mouse

Gene transfer to retinal cells may provide a means to retard photoreceptor cell death and thus prevent blindness in diseases such as retinitis pigmentosa. We tested the possibility of interfering with apoptotic photoreceptor cell death in the rd mouse through subretinal delivery of a recombinant replication-defective adenovirus containing the human cDNA for bcl-2, Ad.2.5HRPbcl-2. Photoreceptor-specific transgene expression was accomplished through incorporation of the 2.5 kb human rhodopsin upstream fragment (HRP). Ad.2.5HRPbcl-2 was injected alone or in combination with Ad.CMVPDE beta. Ad.CMVPDE beta contains a cDNA encoding the beta subunit of cGMP phosphodiesterase (PDE beta). Recombinant viruses containing lacZ (driven either by the cytomegalovirus (CMV) promoter/enhancer or HRP) and of Ad.CMVPDE beta and vehicle alone were injected in contralateral eyes as control. Injection of Ad.2.5HRPbcl-2 in the rd mouse resulted in histologically detectable rescue lasting 6 weeks after birth. Extent of rescue was not as large as after delivery of wildtype PDE beta, the gene defective in the rd mouse. However, delivery of genes which prevent apoptotic cell death may have broad application to gene therapy of retinal degenerative diseases.     

Interrelationships among disablement concepts

BACKGROUND: Understanding interrelationships among disablement concepts is critical to the design of future disability treatment and prevention interventions. METHODS: This study uses cross-sectional data to examine the relationships among physiologic impairments, functional limitations, and disability in a moderately disabled sample of 207 community-dwelling older adults. RESULTS: As hypothesized, the data revealed statistically significant curvilinear relationships of upper and lower extremity strength and balance with mobility in this older sample. Multivariate analyses further clarified the hypothesized causal mechanism among the disablement concepts by demonstrating that most of the association of muscle strength and balance with disability was through the intermediary role of mobility limitations. CONCLUSIONS: The findings from this study highlight the value of clinical trials that focus on prevention or treatment of mobility limitations as a means of preventing disability; our findings underscore the need for future research that examines the effects of other variables believed to influence disablement in late life.     

An optoelectric plantar "shear" sensing transducer: design, validation, and preliminary subject tests

A prototype miniature plantar shear sensing transducer was developed, characterized, and tested in this study. Electro-optical components were chosen for the design because of the fast response time, low cost, small size, low power requirements, and adaptability to this application. The optoelectric circuit employed a 660 nm wavelength light source and photodiode solar cell. Signal amplification and sensitivity were adjusted to provide an output voltage proportional to light power. The sensor shell was designed to encapsulate the electro-optical sensing components while providing mechanical resistance to shear through a spring mechanism. A naval bronze was chosen for the shell due to its strength and nonreflective characteristics (alloy of copper and tin). Static and dynamic characteristics of the shear sensor were determined through a series of calibration tests. Mechanical crosstalk sensitivity ranged from 14.34 to 30.51 mV/N. This represented 1% full-scale/Newton sensitivity. Nonlinearity averaged 5.6% in the forward direction and 7.6% in the reverse direction. Overall sensor output hysteresis was 1.1 +/- 3.1% while the natural frequency of the sensor to an input shear transient was approximately 5 Hz. Temperature sensitivity was -7.0 mV/degree C or 3.5% full-scale/degree C. Testing of five adult subjects revealed peak anterior-posterior shear ranging from 6.7 kPa (posterior heel) to 51.4 kPa (great toe) and medial-lateral shear ranging from 5.4 kPa (great toe) to 43.5 kPa (first metatarsal head). Stress-time integral values ranged from 0.78 kPa-sec (posterior shear at the posterior heel) to 37.3 kPa-sec (medial shear at the posterior heel). Contact durations ranged from 0.28 sec (posterior shear at the posterior heel) to 1.25 sec (medial shear at the posterior heel). Further application of the sensor for plantar shear characterization in able-bodied subjects and those with pathology is suggested.     

The lepidopteran transposon vector, piggyBac, mediates germ-line transformation in the Mediterranean fruit fly

The piggyBac (IFP2) short inverted terminal repeat transposable element from the cabbage looper Trichoplusia ni was tested for gene transfer vector function as part of a bipartite vector-helper system in the Mediterranean fruit fly Ceratitis capitata. A piggyBac vector marked with the medfly white gene was tested with a normally regulated piggyBac transposase helper at two different concentrations in a white eye host strain. Both experiments yielded transformants at an approximate frequency of 3-5%, with a total of six lines isolated having pigmented eyes with various levels of coloration. G1 transformant siblings from each line shared at least one common integration, with several sublines having an additional second integration. For the first transformant line isolated, two integrations were determined to be stable for 15 generations. For five of the lines, a piggyBac-mediated transposition was verified by sequencing the insertion site junctions isolated by inverse PCR that identified a characteristic piggyBac TTAA target site duplication. The efficient and stable transformation of the medfly with a lepidopteran vector represents transposon function over a relatively large evolutionary distance and suggests that the piggyBac system will be functional in a broad range of insects.     

Reduction in complications of angioplasty with abciximab occurs largely independently of baseline lesion morphology. EPIC and EPILOG Investigators. Evaluation of 7E3 for the Prevention of Ischemic Complications. Evaluation of PTCA To Improve Long-term Outcome with abciximab GPIIb/IIIa Receptor Blockade

OBJECTIVES: We investigated the hypothesis that abciximab might lead to a differential effect among patients with different lesion morphologies; hence, its cost/benefit ratio would be optimized if it were used selectively on the basis of baseline angiographic findings. BACKGROUND: Major complications of coronary angioplasty occur in 4% to 9% of patients. In the Evaluation of 7E3 for the Prevention of Ischemic Complications (EPIC) and Evaluation of PTCA To Improve Long-term Outcome with abciximab GPIIb/IIIa Receptor Blockade (EPILOG) trials, abciximab decreased the ischemic complications after intervention by 35% to 56%. However, the cost of this agent is appreciable, and there remain concerns about the safety of its readministration. METHODS: There were 1,362 patients in EPIC and 2,792 patients in EPILOG randomized to either bolus plus an infusion of abciximab or placebo, administered with aspirin and heparin at the time of the coronary intervention. Data from these studies were combined, and a differential effect of abciximab in relation to baseline lesion morphology on 30-day risk of death, myocardial infarction or urgent intervention was investigated using the Breslow Day test for statistical interaction. RESULTS: Abciximab consistently reduced the relative risk of complications across all lesion morphologies studied, with the possible exception of patients treated with degenerated saphenous vein grafts (risk with placebo 16.3% vs. risk with abciximab 18.6%, Breslow Day test for interaction, p=0.08). However, the absolute reduction of risk was somewhat greater in patients with more complex B2 or C lesions (7.6% and 5.8%, respectively) than in patients with morphologically simpler A or B1 lesions (3.7% and 3.2%, respectively). CONCLUSIONS: The reduction of early adverse ischemic events associated with angioplasty by abciximab occurs largely independent of pretreatment morphology.     

Intracellular location of inapparently infecting Chlamydia in synovial tissue from patients with Reiter's syndrome

Culture of Chlamydia trachomatis from synovial tissues/fluids from Reiter's syndrome (RS) patients frequently yields negative results. However, we have identified chlamydial RNA at that site in such patients, suggesting that viable organisms may be present. Here we define the cellular location of chlamydia within the synovium via in situ hybridization. Using a chlamydial ribosomal RNA-directed probe, we show that synovial tissue from culture-negative RS patients gives strong hybridization which is often localized to a subsynovial cell layer, rather than to the synovial lining; in some cases, hybridizing cells are dispersed through the synovium. All hybridization signal is located within host cells, indicating that infectious extracellular elementary bodies are rare or absent. These data confirm the extensive intracellular presence of inapparent chlamydia in the synovia of RS patients and provide some insight into the usual culture negativity of synovial tissues for the organism.     

The psychophysiological specificity problem in panic attacks

Traumatic intrusion of permanent teeth is a relatively infrequent but serious type of dental injury, due to the complicated picture it involves. Various treatment approaches have been suggested, so far, regarding management of intrusive luxation. Techniques aiming to reposition the intruded tooth include observation for spontaneous reeruption, surgical as well as orthodontic repositioning. However, development of complications such as pulp necrosis, inflammatory root resorption, replacement resorption and ankylosis and loss of marginal bone support makes selection of the most favorable technique controversial. In this paper, a critical review of the existing treatment modalities is attempted and treatment approaches based on diagnostic parameters that are indicative of the severity of an intrusive injury are presented. Recommendations are made after taking into consideration experimental and clinical study findings and observations from other author's and our own clinical experience. Two cases of intrusive luxation in children are presented and management of the dental injuries as well as the complications which occurred are being discussed.     

Pharmacological characterization of a specific binding site for angiotensin IV in cultured porcine aortic endothelial cells

This study demonstrated the existence of a specific binding site for angiotensin IV in porcine aortic endothelial cells. Non-equilibrium kinetic analyses at 37 degrees C allowed the calculation of a kinetic Kd of 0.44 nM. Pseudo-equilibrium saturation binding studies at 37 degrees C for 90 min indicated the presence of a single high-affinity site (Kd = 3.87 +/- 0.60 nM), saturable and abundant (Bmax = 9.64 +/- 1.44 pmol/mg protein). Competitive binding studies demonstrated the following rank order of effectiveness: angiotensin IV > angiotensin III > angiotensin II > angiotensin I > angiotensin II-(1-7), while 2-n-butyl-4-chloro-5-hydroxymethyl-1 [(2'-(1H-tetrazol-5-yl) biphenyl-4-yl) methyl] imidazol (DuP 753: losartan), 1-(4-amino-3-methyl-phenyl) methyl-5-diphenylisoethyl-4,5,6,7-tetrahydro-1H-imidazo [4,5-C] pyridine-6-carboxylic acid (PD 123177) or nicotinic acid-Tyr-(N alpha -benzyl-oxycarbonyl-Arg) Lys-His-Pro-Ile-OH (CGP 42112A) were inactive at the concentration of 100 microM. This binding site is, therefore, distinct from angiotensin II receptors, AT1 and AT2. Addition of the divalent cations Mg2+, Mn2+ or Ca2+ to the incubation buffer resulted in 90-95% inhibition of the [125I]angiotensin IV-specific binding to porcine aortic endothelial cells. Furthermore, the chelator, EGTA, at 5 mM increased the number of binding sites (Bmax = 17.8 +/- 2.5 pmol/mg protein), with no change in affinity (Kd = 5.7 +/- 1.3 nM). Exposure of porcine aortic endothelial cell membranes to the non-hydrolyzable GTP analog, GTP gamma S, had no effect on [125I]angiotensin IV binding. The presence of a high concentration of binding sites for angiotensin IV in porcine aortic endothelial cells suggests that this peptide may play an important role in the modulation of the cardiovascular system.     

Evaluation of the paraskeletal clamp system (Mennen plate) in treatment of mandibular fractures

In this study, we used the relatively recent Paraskeletal clamp system (Mennen plate) to evaluate its effectiveness in the treatment of mandibular fractures. This study was conducted on eight patients with mandibular fractures selected from the out patient clinic, Oral Surgery Department, Faculty of Oral and Dental Medicine, Cairo University. Patient sample consisted of six males and two females, four patients were children below the age of 11 years, while the other four were edentulous above the age of 58. Each patient was thoroughly examined both clinically and radiographically. Data collected from each patient were recorded in a special examination chart. Under general anesthesia, the fracture was exposed using a submandibular approach. The fractured segments were reduced and fixed using micro-5 Mennen plates. All patients were followed up both clinically and radiographically for six months postoperatively. Results obtained from this study showed uneventful healing of all patients with no cases of non-union, bony infection or osteomyelitis as proven both clinically and radiographically. All the patients presented normal functioning occlusion and facial symmetry. No bony step deformities were detected.