Wear and creep of highly crosslinked polyethylene against cobalt chrome and ceramic femoral heads

The wear and creep characteristics of highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against large-diameter (36mm) ceramic and cobalt chrome femoral heads have been investigated in a physiological anatomical hip joint simulator for 10 million cycles. The crosslinked UHMWPE/ceramic combination showed higher volume deformation due to creep plus wear during the first 2 million cycles, and a steady-state wear rate 40 per cent lower than that of the crosslinked UHMWPE/cobalt chrome combination. Wear particles were isolated and characterized from the hip simulator lubricants. The wear particles were similar in size and morphology for both head materials. The particle isolation methodology used could not detect a statistically significant difference between the particles produced by the cobalt chrome and alumina ceramic femoral heads.     

Comparison of two dust collection methods for reservoir indoor allergens and endotoxin on carpets and mattresses

Variable methods of dust collection may lead to uncertainty in the measurement of biomarkers. The purpose of this study was to examine the effect of two different dust collection devices on dust weight, Der p 1, Fel d 1, and endotoxin levels. We compared: (1) a nylon mesh sock inserted between the furniture attachment and the vacuum hose (the reference method) and (2) the ALK device. Duplicate dust samples were collected for 2 min from 2 m(2) of 37 living room floors and from each longitudinal half of 37 mattresses. Measurement of Der p 1 and Fel d 1 were by double monoclonal antibody enzyme-linked immunosorbent assay (ELISA) and endotoxin by a Limulus Amobocyte Lysate assay. Geometric mean ratios (95% confidence intervals) were calculated to show the differences between sampling devices for each measurement. Compared with the ALK device, the reference method collected significantly more dust from floors (sevenfold) and mattresses (threefold) and more total Der p 1, Fel d 1, and endotoxin in both sites. Floor, but not mattress, Der p 1 concentrations were also significantly higher (threefold) using our reference method. We recommend that, in order to minimize sampling device bias, allergen and endotoxin are expressed as a concentration, and that the bed is considered the major source of allergen exposure. Practical Implications Dust sampling equipment can influence the dust yield. In order to have confidence in comparisons of allergen and endotoxin reservoir levels between centers, standardization in the use of sampling equipment is important.     

p53 expression in neurofibroma and malignant peripheral nerve sheath tumor. An immunohistochemical study of sporadic and NF1-associated tumors

OBJECTIVES--(1) to evaluate regional cerebral blood flow (rCBF) with single photon emission computed tomography and 99mTc-hexamethylpropyleneamine oxime in patients with the idiopathic adult hydrocephalus syndrome (IAHS); (2) to examine regional cerebral blood flow (rCBF), gait, and psychometric functions before and after CSF removal (CSF tap test); (3) to assess abnormalities in subcortical white matter by MRI. METHODS--Thirty one patients fulfilling the criteria for IAHS (according to history and clinical and neuroradiological examination) were studied. Quantified gait measurements, psychometric testing, and rCBF before and after removal of CSF were obtained. Pressure of CSF and CSF outflow conductance were investigated with a constant pressure infusion method. Brain MRI was used to quantify the severity of white matter lesions and periventricular hyperintensities. In IAHS a widespread rCBF hypoperfusion pattern was depicted, with a caudal frontal and temporal grey matter and subcortical white matter reduction of rCBF as the dominant feature. Removal of CSF was not accompanied by a concomitant increase in rCBF. Significant white matter lesions were detected only in a minority of patients by MRI. An altered CSF hydrodynamic state with a higher CSF pressure and lower conductance was confirmed. IAHS is characterised by an abnormal CSF hydrodynamic state, associated with a widespread rCBF reduction with preference for subcortical white matter and frontal-temporal cortical regions. Furthermore in most patients MRI did not show white matter changes suggestive of a coexistent subcortical arteriosclerotic encephalopathy. At least in the idiopathic group of patients with AHS, measurements of rCBF before and after temporary relief of the CSF hydrodynamic disturbance will not provide additional information that would be helpful in the preoperative evaluation but is suggestive of a preserved autoregulation of rCBF.     

Flap prefabrication: effectiveness of different vascular carriers

A new experimental model of a vascular carrier to prefabricate a "secondary" island flap, the popliteal musculovascular pedicle, was developed in the rat. Using quantitative skin-surface fluorometry 30 minutes after sodium fluorescein injection and a flap survival area in the prefabricated 8 x 2.5-cm abdominal composite island flap, we compared the revascularization ability of our muscular carrier to nonrevascularized controls: the skeletonized arteriovenous pedicle and the fasciovascular pedicle. The free composite graft with no vascular carrier exhibited near-total necrosis. The skeletonized vascular pedicle demonstrated 15.2% +/- 7.8% perfusion of normal skin on dye fluorescence index measurements and 50% flap survival. The fasciovascular pedicle exhibited better revascularization, with a dye fluorescence index of 36.2 +/- 15.5 (p < 0.01) and 90% +/- 10% flap survival (p < 0.001). India ink injection study and histological examination of our model provided visual evidence of revascularization from the musculovascular pedicle, along with preservation of the carrier's muscular architecture. The musculovascular pedicle is a reliable carrier for making new, vascularized composite flaps.     

The effect of dark-rearing, strobe-rearing and acute visual cortex removal on the visual responses in the superficial superior colliculus of the guinea-pig

The interaction of zinc and vitamin A in rats receiving a regional diet of Manaus, supplemented with vitamin A, zinc and zinc and vitamin A was studied. The regional diet was elaborated according to data of Shrimpton and Giugliano (6), for families receiving less than two minimum salaries. The biological test to study the interaction was based on the depletion of zinc and vitamin A in rats in the period of lactation, and a period of repletion where supplements of zinc (0.82 mg%) and vitamin A (94.2 micrograms %) were given, either separately or together, according to the recommendations of the Committee on Laboratory Animal Diets (7). From the results, it was concluded that there was an interaction of these nutrients in terms of mobilization of hepatic vitamin A. Although the regional diet of Manaus did not meet the zinc RDA, the amount present was enough to utilize the available vitamin A. Although the amount of zinc present in the diet, as determined by parameters of bioavilability, such as growth, concentration in organs and zinc-dependent enzymes, was adequately used by the animals, probably due to promoting factors in the diet. The Manaus regional diet needs to be supplemented with vitamin A in order to maintain the hepatic reserves, and with zinc, to maintain the normal levels of vitamin A in plasma.     

A PC-based software test for measuring alcohol and drug effects in human subjects

A new software-based visual search and divided-attention test of cognitive performance was developed and evaluated in an alcohol dose-response study with 24 human subjects aged 21-62 years. The test used language-free, color, graphic displays to represent the visuospatial demands of driving. Cognitive demands were increased over previous hardware-based tests, and the motor skills required for the test involved minimal eye movements and eye-hand coordination. Repeated performance on the test was evaluated with a latin-square design by using a placebo and two alcohol doses, low (0.48 g/kg/LBM) and moderate (0.72 g/kg/LBM). The data on 7 females and 17 males yielded significant falling and rising impairment effects coincident with moderate rising and falling breath alcohol levels (mean peak BrALs = 0.045 g/dl and 0.079 g/dl). None of the subjects reported eye-strain or psychomotor fatigue as compared with previous tests. The high sensitivity/variance relative to use in basic and applied research, and worksite fitness-for-duty testing, was discussed. The most distinct advantage of a software-based test that operates on readily available PCs is that it can be widely distributed to researchers with a common reference to compare a variety of alcohol and drug effects.     

Characterization of type I 5 alpha-reductase activity in DU145 human prostatic adenocarcinoma cells

Each amino acid is represented by a vector of numerical measurements for the attributes of volume, area, hydrophilicity, polarity, hydrogen bonding, shape, and charge. Inter-residue distances are then calculated according to common metrics, and we introduce a new clustering objective function derived from information-theoretic considerations. The arguments of the function are the inter-object distances of the things to be clustered: in this case the amino acids. By means of approximating the solution of an integer programming problem, then, the residues are partitioned into clusters. The clusters obtained are compared with groups obtained in substitution/mutation studies and found to be similar. Thus, probably the strongest and most objective evidence to date is supplied for believing that physico-chemical properties account for the viability of substitutions and that the important similarities/differences are explained by a relatively small and simple set of properties.     

Dimension and related anatomical distance of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia

INTRODUCTION: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. METHODS AND RESULTS: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His-bundle area and the base of the coronary sinus orifice (DHis-OS) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His-bundle recording site from the successful ablation site (DHis-Ab) and the distance as a fraction of the entire length of Koch's triangle (DHis-Ab/DHis-Os) were determined. The mean DHis-Os and DHis-Ab were 25.9 +/- 7.9 and 13.4 +/- 3.8 mm, respectively. DHis-Os negatively correlated with patient age (r = -0.41, P < 0.0001) and body mass index (r = -0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, DHis-Os was longer (27.2 +/- 6.6 vs 24.6 +/- 8.4 mm, P < 0.005), DHis-Ab was similar (12.9 +/- 3.1 vs 13.9 +/- 4.0, P > 0.05) and DHis-Ab/DHis-Os was smaller (0.48 +/- 0.04 vs 0.74 +/- 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 +/- 4 vs 4 +/- 3, P < 0.05). CONCLUSION: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His-bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle; therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter DHis-Os to avoid injury to AV node.     

Flavopiridol: a cytotoxic flavone that induces cell death in noncycling A549 human lung carcinoma cells

Flavopiridol (NSC 649890, L86-8275), a potent inhibitor of cyclin-dependent kinase 1/p34cdc2 phosphorylation and kinase activity, is currently undergoing Phase I clinical testing as a potential antineoplastic agent. Previous studies have suggested that flavopiridol is cytostatic but not cytotoxic when applied to exponentially growing cells. In the present study, various human tumor cell lines were assayed for trypan blue exclusion and ability to form colonies after exposure to flavopiridol under a variety of growth conditions. When log phase A549 non-small cell lung cancer cells were examined 72 h after the start of a 24-h flavopiridol exposure, as many as 90% of the cells accumulated trypan blue. A 24-h exposure to 250-300 nM resulted in trypan blue uptake in 50% of A549 cells at 72 h and a 50% reduction in colony formation. Similar results were observed in HCT8 ileocecal adenocarcinoma, T98G glioblastoma, MCF-7 breast adenocarcinoma, and HL-60 leukemia cells. With A549 cells, identical results were obtained in actively growing logarithmic phase cells and growth-arrested confluent cells. Treatment with the DNA synthesis inhibitor aphidicolin only minimally affected the cytotoxicity of flavopiridol. In contrast, the RNA synthesis inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole or the protein synthesis inhibitor cycloheximide reduced the cytotoxicity of flavopiridol. These results suggest that: (a) flavopiridol is not only cytostatic, but also cytotoxic to a variety of human tumor cell lines; (b) flavopiridol is equally active against cycling and noncycling A549 cells; and (c) RNA and protein synthesis appear to play a role in flavopiridol-induced cytotoxicity.