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At least 613 records · Page 34Linked to original sources
PubMed1996

One hundred consecutive laparoscopic cholangiograms. Results and conclusions.

BACKGROUND: In 100 consecutive patients who underwent laparoscopic cholecystectomy, the feasibility, reliability, and cost of routine laparoscopic cholangiography were prospectively studied. METHODS: Fluoroscopic cholangiograms with multiple exposures were successfully completed in all patients in an average time of 6.9 min. RESULTS: Twenty-one percent were abnormal, and 15 common duct stones and 6 significant anatomic anomalies detected. Thirteen out of 15 patients with common duct stones had preoperative suspicion of common duct stones. Two out of 15 were completely unsuspected. The average cost of cholangiography was $768, and there were no complications related to the procedure. There were no false interpretations. CONCLUSIONS: When compared with selective preoperative endoscopic retrograde cholangiopancreatography (ERCP), routine laparoscopic cholangiography is safer, more accurate, and less costly, and may have the added benefit of potentially reducing iatrogenic injuries in patients with anatomic variations. Routine laparoscopic cholangiography should be considered by all surgeons.

Adult↗
PubMed1984

Flux measurement in single cells by fluorescence microphotolysis.

Fluorescence microphotolysis--widely employed for diffusion studies--can be used to measure transfer (flux) of fluorescent solutes through membranes in single cells and organelles. This article analyses the methodological basis of flux measurements, provides experimental tests, and discusses potential applications. The principle of the method is to equilibrate cells, organelles or vesicles with a fluorescent solute, to deplete the interior of individual cells etc. of fluorescein by the pulse of a high-intensity microbeam, and to monitor influx of solute by microfluorometry. Simple equations are given and a computer curve fitting program is described by which rate constants of influx and membrane permeability coefficients can be derived from fluorescence measurements. The permeability of individual "leaky" human erythrocyte ghosts to fluorescein-isothiocyanate-labelled bovine serum albumin has been measured under various conditions. Multiple exposure to the high-intensity microbeam had no effect on permeability within experimental error. Flux measurements have been also performed on individual vesicles of 1-2 micron radius which had been derived from ghosts. The potential application of the method to sub-lightmicroscopic vesicles and to organelles within living cells is discussed.

Erythrocyte Membrane↗
PubMed1977

Frequency and pattern of radionuclide administration to medical patients in a general hospital.

As part of a drug surveillance programme details of nuclide administration were recorded for 5288 consecutive patients admitted to the medical wards of a large general hospital. Overall use of nuclides amongst this group was found to be low, and multiple exposure to radiation as a result of nuclide administration is not a major hazard when compared to the diagnostic information provided.

Hospitals, General↗
PubMed1983

Assessment of dependence potential of drugs in humans using multiple indices.

The study was designed to determine whether behavioral effects of amphetamine, which have been used to predict dependence potential, were stable after multiple exposures to the drug and whether these different indices of dependence potential were correlated. Ten normal human volunteers participated in a series of three identical choice experiments comparing 10 mg d-amphetamine and placebo. Each experiment consisted of nine sessions. During the first four sessions of each experiment, subjects alternately received amphetamine or placebo. During the next five sessions of each experiment, they were given a choice between amphetamine and placebo. Subjective effects were assessed using the Profile of Mood States (POMS) before drug was taken and 1, 3, and 6 h later. Liking scores were obtained after each session, as well as after each experiment. Subjects chose amphetamine an average of 3.9, 3.0, and 3.4 times out of five in the three experiments, in that order. Compared to placebo, amphetamine produced changes in mood as measured by the POMS including increased anxiety, vigor, friendliness, elation, arousal, and positive mood, and decreased fatigue. Liking scores for amphetamine were consistently higher than for placebo. Mood changes and liking scores produced by amphetamine were similar across all three experiments and across subjects. These results indicate that neither tolerance or increased sensitivity develops to the reinforcing properties of 10 mg d-amphetamine. The results are also discussed in terms of methods for predicting the dependence potential of psychotropic drugs and understanding the role of environmental context as a modulator of a drug's reinforcing effects.

Adult↗
PubMed1985

Immunocytological characterization of the outer acrosomal membrane (OAM) during acrosome reaction in boar.

In order to study the acrosome reaction in boar, spermatozoa were incubated in a calcium-containing medium in the presence of the calcium ionophore A23187. The time course of the acrosome reaction was assessed by phase-contrast microscopy and correlated with the movement characteristics of the spermatozoa determined by means of multiple-exposure photography (MEP). Different stages of the acrosome reaction could be observed by indirect immunofluorescence using an antibody fraction raised in rabbits against the isolated outer acrosomal membrane (OAM). At the start of the acrosome reaction, a bright fluorescence located exclusively at the acrosomal cap of the sperm head could be observed, whereas after 60-120 min, the fluorescence vanished, indicating the complete loss of the OAM. However, to gain more insight into the stages of the plasma membrane and OAM during the acrosome reaction, immunoelectron-microscopical studies were performed using anti-OAM antibodies detected by the protein-A gold method. Ultrathin sections and total preparations in combination with transmission electron microscopy (TEM) confirmed, that boar spermatozoa start their acrosome reaction by a vesiculation of the plasma membrane, thus exposing the heavily labelled OAM, which is then lost as sheets or large vesicles. The newly exposed inner acrosomal membrane did not show any labelling with gold, thereby indicating clear differences in the antigenicity of both acrosomal membranes.

Acrosome↗
PubMed1993

Spurious dual-energy X-ray absorptiometry images in a patient exposed to the contrast agent Thorotrast.

A 69-year-old woman presented with a 20-year history of back pain and a 10 cm height loss. She had received an injection of the contrast agent, Thorotrast, at age 23. There was no history of fluoride exposure. Multiple vertebral compression fractures were seen on radiographs. Dual-energy X-ray absorptiometry (DXA) scans revealed high normal bone mineral content on the spine and, on whole body scan, visualization of the liver and spleen regions. Given the attenuation coefficient of thorium and the thorium concentrations reported for liver, spleen and vertebral bodies, it is likely that thorium was visualized in the liver and spleen and that it caused spurious elevation in her DXA bone mineral content values.

Absorptiometry, Photon↗
PubMed1989

Experiments with extracorporeal shock wave nephrolithotripsy.

Two sets of experiments were carried out on 14 live rabbits having renal calculi from nephrolithiasis patients implanted in their kidneys. Shock waves were used to disintegrate the implanted concrements. It took 100 to 150 sound pulses to crush struvite stones to fragments less than 2 mm in size, with 400 to 800 pulses needed to destroy calcium oxalate stones. After multiple exposures to shock waves there were no indications of any gross damage to the soft tissues of the experimental animals. Mechanisms for destruction of kidney stones by shock waves were considered.

Animals↗
PubMed2006

[Vitamins and minerals in food supplements. Up-to-date risk assessment].

The Federal Institute of Risk Assessment (BfR) has applied principles of scientific risk assessment to derive proposals for maximum levels of vitamins and minerals including trace elements in food supplements and fortified food products. This review describes the special features pertaining to the risk assessment of these essential micronutrients and the procedure used for the derivation of maximum levels for individual food supplements. The applied procedure takes into account tolerable upper intake levels (UL), intakes of vitamins and minerals in normal daily diets and dietary reference values for the derivation of maximum levels in individual food products. In this context, consideration must be given to the possibility of multiple exposure via daily intakes of several food supplements or several fortified food products. A careful risk-benefit analysis was necessary because, with nutrients having a narrow margin of safety, the need to compensate for possibly inadequate intakes or increased demands had to be weighed against the risk of excessive intakes. With nutrients where no UL could be derived due to inadequate databases, the BfR recommends that maximum levels should be set on the basis of nutritional-physiological aspects. It should be noted that this recommendation is based on reasons of preventive health protection.

Administration, Oral↗
PubMed2001

Mechanisms for sensorimotor adaptation to rotated visual input.

Using the multiple-exposure approach, we investigated sensorimotor adaptation by exposing human subjects to different angles of visual rotation in a tracking task. Generally, the tracking error was high at the onset of the visual rotation and gradually declined towards the baseline level during the exposure period. In experiment A, we confirmed that the initial tracking error increases more than proportionally with the angle of rotation. In experiment C, we were unable to confirm intermanual transfer, and attribute this discrepancy with previous literature to details of the experimental tasks. In our main experiment, B, we found that pre-exposure to 45 degrees or 60 degrees of visual rotation facilitated the subsequent adaptation to a 90 degrees rotation, with the facilitatory effect being more pronounced following the 60 degrees rotation. We interpret this finding as evidence that adaptation is achieved by a gradual process, which progresses from small angles of output transformation through intermediate values up to the prescribed angle of rotation.

Adaptation, Physiological↗
PubMed2006

Radiation-free quantitative assessment of scoliosis: a multi center prospective study.

Accurate quantitative measurements of the spine are essential for deformity diagnosis and assessment of curve progression. There is much concern related to the multiple exposures to ionizing radiation associated with the Cobb method of radiographic measurement, currently the standard procedure for diagnosis and follow-up of the progression of scoliosis. In addition, the Cobb method relies on 2-D analysis of a 3-D deformity. The aim of this prospective study was to investigate the clinical value of Ortelius800 that provides a radiation-free method for scoliosis assessment in three planes (coronal, sagittal, apical), with simultaneous automatic calculation of the Cobb angle in both coronal and sagittal views. Analysis of the clinical value of the device for assessing spinal deformities was performed on patients with adolescent idiopathic scoliosis, deformity angles ranging from 10 degrees to 48 degrees. Correlation between Cobb angles measured manually on standard erect posteroanterior radiographs and those calculated by Ortelius800 showed an absolute difference between the measurements to be significantly less than +/- 5 degrees for coronal measurements and significantly less than +/- 6 degrees for sagittal measurements indicating good correlation between the two methods. The measurements from four independent sites and six independent examiners were not significantly different. We found the novel clinical tool to be reliable for following mild and moderate idiopathic curves in both coronal and sagittal planes, without exposing the patient to ionizing radiation. Considering the need for further validation of this new method, any change in treatment protocol should still be based on radiographic control.

Adolescent↗
PubMed1992

Drug-associated "bite cell" hemolytic anemia.

PURPOSE: "Bite cell" hemolytic anemia is a variant of drug-related hemolysis usually associated with methemoglobinemia and Heinz body inclusions in red blood cells secondary to oxidant drug injury. Bite cells are morphologically characterized as poikilocytes with one or more semicircular portions removed from the cell margin. The purpose of this report is to emphasize the importance of peripheral smear examination in patients with possible drug-associated hemolytic anemia. The morphologic characteristics of bite cells by light microscopy and scanning electron microscopy are detailed in this study, and the pathophysiologic mechanism is discussed. PATIENTS AND METHODS: Clinical and laboratory data were retrospectively studied on eight patients (two men and six women, aged 29 to 85 years) who showed evidence of bite cell hemolytic anemia associated with drug exposure. Multiple standard hematologic laboratory evaluations for hemolytic anemia were performed. Five hundred red blood cells were counted from randomly selected peripheral smear fields for the calculation of bite cell percentage. RESULTS: Peripheral smears showed predominantly normochromic normocytic red cells with prominent bite cells and occasional blister cells. Bite cell counts ranged from 5.5% to 13.6% (mean, 8.7 +/- 3.0% SD) associated with a hematocrit reduction of 3.0% to 13.2% (mean, 8.5 +/- 3.8% SD) and concomitant reticulocytosis of varying degree from 2.3% to 15.4% (mean, 7.3 +/- 4.9% SD). Withdrawal of the offending drug(s) and treatment of underlying diseases resulted in improvement of hemolytic anemia and eventual disappearance of bite cells. A close correlation between hematocrit reduction, reticulocyte response, and bite cell percentage increase was seen. The usual biochemical markers of hemolysis were not consistently observed. Scanning electron microscopy confirmed the light microscopic evidence of bite cell morphology and revealed a keratocytic variant. CONCLUSION: This study emphasizes the importance of peripheral smear examination for early diagnosis and management of bite cell hemolytic anemia. Withdrawal of the putative offending drug(s) and treatment of underlying disorders should result in improvement of this form of drug-associated hemolysis.

Adult↗
PubMed1993

Cellular accumulation of amiodarone and desethylamiodarone in cultured human cells. Consequences of drug accumulation on cellular lipid metabolism and plasma membrane properties of chronically exposed cells.

Amiodarone (AMIO), a potent antiarrhythmic drug, is clinically widely used despite its frequent side effects after chronic administration. These side effects coincide with an intralysosomal accumulation of AMIO and its main metabolite desethylamiodarone (DEA) and may be causally related to the drug-induced intracellular storage of phospholipids (PL). Kinetics of cellular uptake and release of radiolabelled AMIO and DEA were studied following single and multiple exposures of cultured human skin fibroblasts to 5 and 10 microM drug concentrations. AMIO and DEA were efficiently taken up into cultured cells. The rate of uptake was slower than that of other cationic amphiphilic drugs. The intracellular steady state concentrations were in the millimolar range suggesting a lysosomal trapping. Repetitive exposures of cultures resulted in a cumulative and partly saturable drug uptake. The accumulation of DEA was higher than that of AMIO throughout. AMIO and DEA previously taken up into the cells during a 2 hr exposure were completely released into the washing media, suggesting an exchangeable form of the accumulated drugs. Following repetitive exposures only part of the drugs was released. Under chasing conditions using washing media containing non-labelled AMIO and DEA respectively or ammonium chloride the release of the chronically accumulated 14C-labelled drugs was increased. This suggested a drug storage in the form of complexes in acidic compartments. Phospholipid (PL) content as well as individual PL fractions were changed in whole cells and in isolated plasma membranes. PL accumulation is assumed to occur by inhibition of PL degradation due to formation of non-degradable drug-PL complexes or by inhibition of phospholipase activities. Cellular PL accumulation seemed to interfere with PL recycling. Changes in PL composition of purified plasma membranes were in part complementary to the ones in whole cells. The alterations in membrane PL composition may explain the changes in membrane fluidity and the decrease in beta-adrenoceptor density and in isoproterenol-stimulated cAMP formation. The results obtained provide an explanation for the pharmacokinetic, and possibly for the pharmacodynamic and also toxicological behaviour of AMIO and DEA in vivo.

Amiodarone↗
PubMed1986

Longevity of Gynol II and Ortho Creme in the Prentif cervical cap.

A review of the literature yielded no scientific basis for current recommendations on the length of time spermicide-filled cervical caps can be worn while continuing to protect against pregnancy. Ten cervical cap users provided 99 samples of cap contents after a variety of insertion periods using Gynol II, Ortho Creme and vehicle controls. Testing for spermicidal effect was performed in the laboratory using quality semen from two donors and employing the Multiple Exposure Photography system of semen analysis. Criteria for determining spermicide effectiveness were developed. Results suggest that 3 to 4 days is the reasonable limit for cap use with Gynol II and 5 days with Ortho Creme, contrasted with 1 day limits for Gynol II and 2 day limits for Ortho Creme using existing criteria. Limited experience with samples exposed to semen in vivo suggest that spermicidal potency is not lost through repeated intercourse. Recommendations for validating these limits with clinical studies are made.

Adult↗
PubMed1986

Longevity of Ortho Creme and Gynol II in the contraceptive diaphragm.

A literature review yielded no scientific basis for the currently accepted recommendations on the length of time spermicides used with diaphragms continue to kill sperm. Twelve volunteers provided 68 spermicide samples representing 6, 12, 18, and 24 hours of in vivo insertion in a contraceptive diaphragm using Ortho Creme, Gynol II, and vehicle controls. Testing for continued spermicidal effect was performed in the laboratory using quality semen from 2 donors and employing the Multiple Exposure Photography system of semen analysis. Results showed effective spermicidal action after 12 hours of insertion, mixed effectiveness after 18 hours, and poor effectiveness after 24 hours with both products, with Ortho Creme being more effective in the longer insertions. Placebo jelly enhanced sperm activity while placebo creme had a moderate inhibitory effect. Recommendations for further study are made.

Adult↗
PubMed1984

Carcinogenicity of single and multiple intratracheal instillations of cadmium oxide in the rat.

The carcinogenic effects of single or multiple exposures to intratracheally instilled cadmium oxide, resulting in total doses of 0, 25, 50, and 75 micrograms, were studied in groups of 41 to 48 male Fischer rats. Pulmonary-deposited cadmium oxide did not result in increased numbers of tumors, except in the mammary gland or in rats that had three or more tumor types. Cadmium oxide was not carcinogenic in the lung, liver, kidney, or prostate gland of rats.

Animals↗
PubMed1988

Effects of radiofrequency radiation on rabbit kidney: a morphological and immunological study.

The histopathology of the acute and chronic kidney reaction to low-frequency nonionizing electromagnetic radiation was evaluated in New Zealand white rabbits treated with multiple exposure to 27.12-MHz radiofrequencies. At the end of treatment, the animals exhibited focal tubular necrosis and focal and segmental glomerular sclerosis which in a few months evolved into a membranous nephropathy. The latter was characterized by a diffuse, granular localization of rabbit gamma-globulin and complement in most glomeruli and by electron-dense deposits in the subepithelial zone of the glomerular capillary walls, suggesting that these glomerular changes are induced by the localization of antigen-antibody complexes. The data obtained provide strong evidence for the potential nephrotoxicity of radiofrequency radiation and indicate that these nonionizing types of radiation may be capable of eliciting autoimmune phenomena that are likely responsible for the evolution of renal disease in rabbits.

Animals↗
PubMedDate not supplied

Compressive fatigue behavior of bovine trabecular bone.

We studied the fatigue behavior of bovine trabecular bone specimens under stress control using a sinusoidal uniaxial compressive load profile with a frequency of 2 Hz. The stress range was determined from the corresponding initial global platen-to-platen strain range, where the maximum initial strain was between 0.8 and 2.1% and the minimum strain was 0.6%. The local strain distribution was measured on the same type of specimen by affixing glass spheres and photographing them in the unloaded and loaded positions using multiple exposures. The number of cycles to failure (defined as a 5% decrease in secant modulus) was strongly correlated with the initial global maximum strain (r2 = 0.78) and ranged from 20 cycles at 2.1% strain to 400,000 cycles at 0.8% strain. All of the fatigue specimens showed a region of transverse failure approximately 1 mm from the end of the specimen. Microscopic examination of the failure zones revealed two failure modes: a straight transverse brittle-like fracture through the trabeculae, most often found in trabeculae transverse to the loading direction, and buckling-like failure, common in oblique trabeculae, involving bending and splitting. The local strain increased towards the ends of the specimens to a value 2-4 times that in the middle. Modulus degradation with the number of cycles was distinctively different for high-cycle and low-cycle fatigue, suggesting the possibility that both creep and damage accumulation contribute to fatigue failure of trabecular bone.

Animals↗
PubMed1984

Short-wave ultraviolet irradiation increases photo-affinity labeling of benzodiazepine sites.

Photoaffinity labeling of benzodiazepine sites with [3H]-flunitrazepam was examined using either long-wave (366 nm) or short-wave (254 nm) ultraviolet irradiation. A multiple exposure protocol was employed so that the time course of the process could be determined as well as the fraction of total sites labeled. At 366 nm, approximately 20% of the total sites present were labeled and the remainder showed reduced affinity for flunitrazepam, in agreement with published reports. When membranes from either cortex or cerebellum were irradiated at 254 nm, however, the fraction of sites labeled increased above 40%. The change in the ratio of labeled sites to those showing reduced affinity, as well as differences in the time courses of the two phenomena, are taken as evidence that the labeling and affinity change are independent processes rather than two effects of a single event. Inhibition of labeling by clonazepam and Ro15-1788 indicated the "central" nature of the labeled sites.

Affinity Labels↗