Assessment of flow-mediated dilatation in the superficial femoral artery using a sustained shear stress stimulus via calf plantar-flexion exercise.

NEW FINDINGS: What is the central question of this study? The aim was to establish the ability of a newly designed leg exercise technique to produce sustained elevations in shear rate that stimulate flow-mediated dilatation (FMD) in the superficial femoral artery and to determine the repeat trial stability of the FMD response. What is the main finding and its importance? Calf plantar-flexion exercise can be used to increase shear stress and stimulate FMD in the superficial femoral artery. However, the magnitude of FMD varied systematically when multiple trials were repeated in short succession. The superficial femoral artery (SFA) is susceptible to vascular disease, and a technique to assess flow-mediated dilatation (FMD) in this vessel in response to a sustained shear stress stimulus could provide important information about endothelial function. The aim of this study was to establish the ability of a newly designed SFA leg exercise-FMD (LEX-FMD) technique to produce sustained elevations in shear rate, which stimulate FMD, and to determine the repeat trial stability of the FMD response. The SFA FMD stimulated by reactive hyperaemia (RH) and calf plantar-flexion exercise (LEX) was assessed via ultrasound in 19 healthy men (n = 10) and women (n = 9). The two experimental visits included either four trials of LEX-FMD or four trials of RH-FMD. The shear stress stimulus was estimated as the shear rate (blood velocity/SFA diameter). Results are expressed as the means ± SD. The LEX steady-state shear rate was consistent between trials (P = 0.176), whereas the RH shear rate area under the curve was higher in trial 1 versus trials 2-4 (P < 0.05). The %RH-FMD (four-trial mean 4.9 ± 2.5%) and absolute RH-FMD were not significantly different between trials (P = 0.465 and P = 0.359, respectively). Both %LEX-FMD and absolute LEX-FMD were higher during trial 3 (4.8 ± 3.4%) than trial 1 (3.6 ± 2.7%; P = 0.026 and P = 0.026, respectively). The magnitude of RH-FMD and LEX-FMD did not differ (P = 0.241). These results indicate that calf plantar-flexion exercise can be used to increase shear stress and stimulate FMD in the SFA. However, although SFA RH-FMD was stable across four trials, LEX-FMD varied systematically when multiple trials were repeated in rapid succession.

Impaired brachial artery endothelial function in young healthy women following an acute painful stimulus.

INTRODUCTION: Impaired endothelial function has been observed during and immediately following an acutely painful stimulus. However, the extent to which this persists following pain dissipation is unclear. PURPOSE: To determine whether painful ischemic handgrip exercise (pain task) causes impaired flow-mediated dilation (FMD) after the sensation of pain and hemodynamic responses have abated. A second purpose was to determine whether the response to pain differed with a predisposition to magnify, ruminate, and feel helpless about pain (pain catastrophizing status). METHODS: Brachial artery FMD stimulated by reactive hyperemia was assessed via ultrasound in 18 (9 high catastrophizing) healthy, women (20 ± 1 years) before and 15 min after a 3 min pain task. The shear stress stimulus for FMD was estimated as shear rate (blood velocity/brachial artery diameter). RESULTS (MEAN ± SD): None of the variables were significantly impacted by pain catastrophizing status and are presented pooled across group. The pain task increased pain ratings [1 ± 1-6 ± 3 (0-10 scale) (p < 0.001)], mean arterial pressure (MAP) (p < 0.001) and heart rate (HR) (p < 0.001), all returning to pre-pain levels ≤2-min post-pain task (pre-pain vs. 2-min post-pain: pain rating p = 1.000; MAP p = 0.142; HR p = 0.992). The shear rate stimulus was not different between pre- and post-pain task FMD tests (p = 0.200). FMD decreased post-pain task (10.8 ± 4.6 vs. 7.0 ± 2.7 %, p < 0.001). CONCLUSION: These results indicate that, regardless of pain catastrophizing status, painful ischemic handgrip exercise has a deleterious impact on endothelial function that persists after the pain sensation and hemodynamic responses have abated.

The action of natural and synthetic isomers of quisqualic acid at a well-defined glutamatergic synapse.

L-, D- and DL-quisqualic acid have been synthesized and their activities at the glutamatergic locust nerve-muscle junction have been compared with those of natural quisqualic acid and with glutamic acid. Two well-characterised locust nerve-muscle preparations were used in these studies, the retractor unguis nerve-muscle system and the extensor tibiae nerve-muscle system. The amino acids were tested on the whole nerve-muscle system in the former, when reduction in neurally evoked twitch contraction amplitude was the measured parameter, and by ionophoretic application to single excitatory junctional sites in the latter, when amplitude of junctional depolarization was the measured parameter. Synthetic L-quisqualic acid exhibited identical potency to its natural counterpart. However, D-quisqualic acid and DL-quisqualic acid were more active than expected from the known stereospecificity of this glutamatergic system towards D- and L-glutamic acid. The hydantoin analogue of quisqualic acid was inactive. X-ray crystallographic analysis of L-quisqualic acid and the hydantoin analogue showed that the ring junction in the former is pyramidal whereas in the latter it is planar. This may account for the high potency of L-quisqualic acid on a receptor system which identifies a partially folded conformation of L-glutamic acid. A pyramidal configuration of D-quisqualic acid would allow either rapid interconversion between active and inactive configurations at its ring junction or adoption of a trigonal configuration in solution. Either interpretation could explain the unexpected potency of D-quisqualic acid.

Mechanical property evaluation of pressable restorative ceramics.

OBJECTIVE: The aim of this study was to evaluate the flexure strength under static and cyclic loading and the fracture toughness under static loading of six restorative ceramic materials. Specifically the intent was to compare four leucite (K2O.Al2O(3).4SiO2) strengthened feldspathic (pressable) porcelains (OA, OI, E, and FP) to a low fusing feldspathic porcelain (F) and an experimental (EC) lithium disilicate containing ceramic. METHODS: All materials were tested as a control in air and distilled water (without aging) and after three months aging in air or distilled water to determine flexure strength and fracture toughness. A staircase approach was used to determine the cyclic flexure strength. EDS and SEM analysis were conducted on the polished and fracture surfaces. RESULTS: The mean flexure strength for the controls in air and water (without aging or cyclic loading) ranged from 67 to 99 MPa, except the experimental ceramic that was twice as strong with a mean flexure strength of 191-205 MPa. For the mean fracture toughness, the range was 1.1-1.9 MPa/m0.5 with the experimental ceramic being 2.7 MPa/m0.5. The effect of testing in water and aging for three months caused a moderate reduction in the mean flexure strength (6-17%), and a moderate to severe reduction in the mean fracture toughness (5-39%). The largest decrease (15-60%) in mean flexure strength was observed when the samples were subjected to cyclic loading. SIGNIFICANCE: The lithium disilicate containing ceramic had a significantly higher flexure strength and fracture toughness when compared to the four pressable leucite strengthened ceramics and the low fusing conventional porcelain. All of the leucite containing pressable ceramics did provide an increase in mean flexure strength (17-19%) and mean fracture toughness (3-64%) over the conventional feldspathic porcelain. Further, the influence of testing environment and loading conditions implies that these ceramic materials in the oral cavity might be susceptible to cyclic fatigue, resulting in a significant decrease in the survival time of all-ceramic restorations.

Biochemical and haematological evidence of endotoxic shock in gnotobiotic lambs with watery mouth disease.

Eight gnotobiotic lambs deprived of colostrum were infected by mouth when two hours old with nonenterotoxigenic strains of Escherichia coli. All developed clinical signs of watery mouth disease and seven died within 24 hours. The mean concentrations of several blood constituents were determined in samples taken at intervals until 24 hours after infection in infected lambs and in four control lambs. The biochemical and haematological changes observed in the lambs developing watery mouth disease were those characteristic of endotoxic shock.

Primary closure of fasciotomy incisions with a skin-stretching device in patients with burn and trauma.

Closure of fasciotomy wounds is often a clinical problem after successful management of compartment syndrome. Commonly, split-thickness skin grafts or regional composite grafts are used for fasciotomy closure. However, functional and cosmetic results would be improved if primary reapproximation of these wounds were more practical. The main obstacle that must be overcome is excessive tension on the wound edges. A recently developed skin-stretching device (Sure-Closure, Life Medical Sciences, Princeton, N.J.) allows large tissue defects to be closed with approximation of the wound edges. In this report we describe two patients in whom closure of the fasciotomy incisions was successfully accomplished with the skin-stretching device. These patients included an 11-month-old girl with a circumferential burn of the left arm, and a 42-year-old woman involved in a motor vehicle accident who sustained frostbite and crush injury to her left upper extremity without bone fractures. The skin-stretching device produced excellent functional and cosmetic wound closure results and eliminated the need for additional operative procedures.

Clinicopathological investigation of primary, uncomplicated maedi-visna virus infection.

Maedi-visna virus infection in a flock of sheep in Scotland was associated with respiratory disease, neurological disease, mastitis and lameness. The major clinical signs were dyspnoea (particularly on exercise), progressive fore- and hindlimb ataxia and balance defects, mammary induration and multilimb lameness, occasionally with enlarged carpal joints. Pathological examinations revealed lesions in the lungs, central nervous system, mammary glands and joints which were consistent with those induced by maedi-visna virus. The was no clinical or pathological evidence of concurrent sheep pulmonary adenomatosis, and pulmonary bacterial infections, when they occurred, were superimposed on the lesions due to maedi-visna virus.

Systemic mycosis due to Aspergillus deflectus in a dog.

A 4-year-old, entire female, German Shepherd Dog was referred with a 3-month history of right foreleg lameness that partially responded to nonsteroidal anti-inflammatory and antimicrobial therapy. The bitch lost weight, was polydipsic and had reduced exercise tolerance. On referral, the animal was in poor condition, pyrexic and exhibited moderate pain on full extension of the right shoulder. Blood, urine and joint fluid were obtained and radiographs were taken of the right shoulder and chest. The bitch was lymphopaenic, hyperfibrinogenaemic, hyperglobulinaemic, mildly azotaemic, mildly proteinuric and isosthenuric. Branching fungal hyphae were present in the urine. On radiography, the thorax contained a large ventral mediastinal mass and the humeral head had extensive areas of radiolucency. An aspirate from the right humeroscapular joint exhibited branched fungal hyphae and numerous neutrophils and macrophages. A diagnosis of disseminated mycosis was made and euthanasia was performed. At necropsy, numerous caseating granulomas were present, especially in the kidneys, adrenal glands, heart and lymph nodes. Extensive osteomyelitis involved the head of the right humerus, the sternebrae and the fifth intervertebral disc. Fungal hyphae were detected in sections of granulomas in all affected organs and a diagnosis of disseminated fungal granulomatosis was made. Aspergillus deflectus was readily isolated from affected lymph nodes, but confirming its identity as A deflectus using standard procedures proved difficult. The identity of the fungus was finally confirmed by sequencing part of the 185 rRNA of the isolate. This is the first report in Australia of a disseminated mycosis caused by A deflectus. Previously, the involvement of A deflectus as a cause of disseminated mycosis was limited to 5 cases from the West Coast of the USA, four of which occurred in German Shepherd Dogs.

CMV enhancer-promoter is preferentially active in exocrine cells in vivo.

The CMV enhancer-promoter sequence is often used as a transcriptional regulatory element in vector systems. We have used this control element to drive expression of GFP in a lentivirus vector transgene in pigs and chickens. Promoted as a 'universal' enhancer/promoter element capable of transcriptional activity in a number of cells in vitro, CMV-GFP transgene expression in vivo is preferentially observed in exocrine cells. This expression profile validates the use of this transcriptional control sequence to target expression to exocrine cells in gene transfer strategies.

Crystallographic studies and semi-empirical MNDO calculations on quisqualic acid and its analogues: systems containing unusual pyramidal heterocyclic ring nitrogens.

X-ray crystallographic studies on synthetic DL-quisqualic acid and the corresponding carbon analogue have revealed pyramidal and almost planar geometries respectively for the ring nitrogen atoms carrying the alkyl side chain. Semi-empirical molecular orbital calculations on methyl-substituted model systems predict ring geometries in close agreement with experimentally observed data. The calculated energy barriers between the two enantiomeric forms (invertomers) of the oxadiazolidine systems along with some physical data would suggest that such forms are rapidly interconverting.

Thermal and cyclic loading of endodontic posts.

The intent of this study was to determine pullout (shear) strength of carbon and stainless steel serrated posts from teeth. The tooth-posts groups were controls, thermal-cycled, load-cycled (load applied at either a 45 degrees angle or along the long axis of the post), and thermal- and load-cycled. Human extracted third molars were embedded in denture acrylic. Post space was prepared and the posts cemented with a resin cement according to manufacturer's instructions. The testing was in tension at a loading rate of 2 mm/min. The pullout (shear) strengths (MPa+/-SD) for the carbon posts were: controls 6.1+/-3.3; load-cycled 4.3+/-2.2; and thermal-cycled 4.2+/-2.2. The thermal-cycled and then load-cycled carbon posts all fractured during testing and were unable to be evaluated for shear strength. The pullout (shear) strengths (MPa+/-SD) for the stainless steel posts were: controls 6.6+/-2.9; load-cycled 7.1+/-3.2; thermal-cycled 4.8+/-2.0; and thermal load-cycled 6.8+/-3.5. The statistical analysis indicated no significant difference in the pullout (shear) strength between any of the post groups tested. Two different operators then prepared specimens using carbon posts abraded with 50 microm alumina and non-abraded carbon posts. The alumina abrasion caused a decrease in the post bond strength with the alumina particles impinging on the carbon fibers resulting in their fracture. The significant difference between bond strengths was attributed to each operator's years of clinical experience.

Antibiotic suseptibility of bacteria isolated from oral infections.

Exudates from bacterial infections of oral soft tissues were cultured and tested for antiobiotic susceptibility. Of 74 specimens tested, 68 were cultivable on blood agar; 56 of the cultivable exudates were pure cultures and 12 were mixed cultures. Strepococci and staphylococci accounted for 57% and 34%, respectively, of the pure cultures. Anaerobic bacteria were found in nearly 15% of the pure culture exudates. Gramnegative organisms accounted for about 4% of the pure cultures. Virtually all of the pure and mixed streptococcal cultures were sensitive or moderately susceptible to ampicillin, cephalothin, and penicillin; however, approximately 50% of the streptococal and staphylocococcal isolates were resistant to demeclocycline hydrochloride and erythromycin.