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At least 1,225 records · Page 68Linked to original sources
PubMed2000

Deep venous thrombosis: detection by using indirect CT venography. The Pulmonary Angiography-Indirect CT Venography Cooperative Group.

PURPOSE: To assess the clinical benefits of performing indirect computed tomographic (CT) venography after pulmonary CT angiography to detect deep venous thrombosis (DVT) in patients suspected of having a pulmonary embolism. MATERIALS AND METHODS: The authors prospectively enrolled 541 consecutive patients who underwent pulmonary CT angiography for suspected pulmonary embolism at seven institutions. Using a protocol that optimizes venous enhancement without additional contrast material injection, the authors obtained contiguous images from the pelvis to the popliteal fossa. Ultrasonography (US) also was performed in 116 patients. RESULTS: DVT was found at indirect CT venography in 45 (8%), and pulmonary embolism was found at pulmonary CT angiography in 91 (17%) of 541 patients. Among the 45 patients with DVT, DVT occurred in 16 patients who had no pulmonary embolism at pulmonary CT angiography, which increased the diagnosis of thromboembolic disease by 18%. Among 116 patients who underwent US and indirect CT venography, 15 had DVT at US, and in all 15, DVT also was seen at indirect CT venography. In four additional cases, DVT was seen at only indirect CT venography. CONCLUSION: Among patients suspected to have pulmonary embolism, a substantial number had DVT in the absence of pulmonary embolism. Combined pulmonary CT angiography-indirect CT venography can depict these cases with accuracy comparable to that of US and thus could have a significant effect on patient care.

Adolescent↗
PubMedDate not supplied

Informatics in radiology (infoRAD): introduction to the language of three-dimensional imaging with multidetector CT.

The recent proliferation of multi-detector row computed tomography (CT) has led to an increase in the creation and interpretation of images in planes other than the traditional axial plane. Powerful three-dimensional (3D) applications improve the utility of detailed CT data but also create confusion among radiologists, technologists, and referring clinicians when trying to describe a particular method or type of image. Designing examination protocols that optimize data quality and radiation dose to the patient requires familiarity with the concepts of beam collimation and section collimation as they apply to multi-detector row CT. A basic understanding of the time-limited nature of projection data and the need for thin-section axial reconstruction for 3D applications is necessary to use the available data effectively in clinical practice. The axial reconstruction data can be used to create nonaxial two-dimensional images by means of multiplanar reformation. Multiplanar images can be thickened into slabs with projectional techniques such as average, maximum, and minimum intensity projection; ray sum; and volume rendering. By assigning a full spectrum of opacity values and applying color to the tissue classification system, volume rendering provides a robust and versatile data set for advanced imaging applications.

Imaging, Three-Dimensional↗
PubMedDate not supplied

Sonographic examination of the carotid arteries.

Ultrasonography (US) of the carotid arteries is a common imaging study performed for diagnosis of carotid artery disease. In the United States, carotid US may be the only diagnostic imaging modality performed before carotid endarterectomy. Therefore, the information obtained with carotid US must be reliable and reproducible. Technical parameters that can affect the accuracy of carotid US results include the Doppler angle, sample volume box, color Doppler sampling window, color velocity scale, and color gain. Important factors in diagnosis of atherosclerotic disease of the extracranial carotid arteries are the intima-media thickness, plaque morphology, criteria for grading stenosis, limiting factors such as the presence of dissection or cardiac abnormalities, distinction between near occlusion and total occlusion, and the presence of a subclavian steal. Challenges to the consistency of carotid US results may include lack of a standard protocol, poor Doppler technique, inexperience in interpretation of hemodynamic changes reflected in the Doppler waveform, artifacts, and physical challenges. Hindrances in the classification of problematic carotid artery stenoses may be overcome by following a standard protocol and optimizing scanning techniques and Doppler settings.

Carotid Arteries↗
PubMed2004

Position in cell cycle controls the sensitivity of colon cancer cells to nitric oxide-dependent programmed cell death.

Mounting evidence suggests that the position in the cell cycle of cells exposed to an oxidative stress could determine their survival or apoptotic cell death. This study aimed at determining whether nitric oxide (NO)-induced cell death in colon cancer cells might depend on their position in the cell cycle, based on a clone of the cancer cell line HT29 exposed to an NO donor, in combination with the manipulation of the cell entry into the cell cycle. We show that PAPA NONOate (pNO), from 10(-4) m to 10(-3) m, exerted early and reversible cytostatic effects through ribonucleotide reductase inhibition, followed by late resumption of cell growth at 5 x 10(-4) m pNO. In contrast, 10(-3) m pNO led to late programmed cell death that was accounted for by the progression of cells into the cell cycle as shown by (a) the accumulation of apoptotic cells in the G(2)-M phase at 10(-3) m pNO treatment; and (b) the prevention of cell death by inhibiting the entry of cells into the cell cycle. The entry of pNO-treated cells into the G(2)-M phase was associated with actin depolymerization and its S-glutathionylation in the same way as in control cells. However, the pNO treatment interfered with the build-up of a high reducing power, associated in control cells with a dramatic increase in reduced glutathione biosynthesis in the G(2)-M phase. This oxidative stress prevented the exit from the G(2)-M phase, which requires a high reducing power for actin deglutathionylation and its repolymerization. Finally, our demonstration that programmed cell death occurred through a caspase-independent pathway is in line with the context of a nitrosative/oxidative stress. In conclusion, this work, which deciphers the connection between the position of colonic cancer cells in the cell cycle and their sensitivity to NO-induced stress and their programmed cell death, could help optimize anticancer protocols based on NO-donating compounds.

Actins↗
PubMed2005

Identification of biomarkers for breast cancer in nipple aspiration and ductal lavage fluid.

PURPOSE: To establish a comprehensive proteomic approach for biomarker discovery and validation in breast fluid. EXPERIMENTAL DESIGN: A total of 95 specimens from three institutions were used including 10 nipple aspiration fluid (5 stage I/II cancerous breasts and 5 age-matched healthy controls), 42 ductal lavage fluid from 14 patients with unilateral stage I/II cancer (25 from 9 cancerous breasts and 17 from 7 contralateral breasts), and 42 ductal lavage fluid from 14 high-risk women (multiple ducts repeated lavage). Differentially expressed protein/peptides were discovered by proteomic analysis of training sample, using ProteinChip arrays and surface-enhanced laser desorption ionization (SELDI) time-of-flight mass spectrometry, and validated on independently collected testing samples. After protein identification, ELISA was done to confirm the SELDI findings. RESULTS: We were able to obtain reproducible protein profiles using minimal amount of protein (1 mug) by applying an optimized chip protocol and SELDI. We were able to select cancer-associated biomarkers despite large individual variability by applying both unsupervised and supervised cluster analysis. Furthermore, we were able to train and test candidate biomarkers on independently collected samples and identified one component of a multimarker panel as human neutrophil peptides 1 to 3. CONCLUSIONS: Breast fluid is a rich source of breast cancer biomarkers. In combination with high-throughput novel proteomic profiling technology and multicenter study design, markers that are highly specific to breast cancer can be discovered and validated. Our observations also suggest that persistent elevation of human neutrophil peptide in high-risk women may imply early onset of cancer not yet detectable by current detection method. Proof of this hypothesis requires follow-up on a larger study population.

Adenocarcinoma↗
PubMed1999

Regulation of megakaryocytopoiesis.

After 35 years of research, a physiological regulator of platelet production has been identified and the recombinant protein is available. With the discovery of thrombopoietin (TPO), its potential use in a wide variety of clinical megakaryocytic and platelet disorders has been expected and clinical trials have been undertaken. To date, the reported encouraging pre-clinical studies indicate that, as with erythropoietin or G-CSF, minimal toxicity can be expected. A potential limiting side-effect of TPO could be the induction of thrombosis. Nevertheless, it is too early to know whether this cytokine will be of major therapeutic importance for patients with life-threatening thrombocytopenia, such as patients undergoing bone marrow transplantation or subjected to a high dose of chemotherapy. Several experimental and clinical studies are still needed to determine the efficacy of TPO in the prevention or the amelioration of bleeding, which is the ultimate goal for the appropriate use of cytokines with haemostatic benefit. Basic and clinical studies on regulators of megakaryocytopoiesis have rapidly progressed. Now, there is no doubt that some of these regulators are effective in correcting haematopoietic disorders of various aetiologies. Studies on negative regulators not only are important to understand the regulation of megakaryocytopoiesis in normal and pathological states but also have a potential clinical application. Some of these regulators have been shown to be effective in the treatment of essential thrombocythaemia and other myeloproliferative disorders. Platelet factor 4 (PF4) and some other chemokines are also capable of protecting progenitor cells from the cytotoxicity of chemotherapeutic drugs. However, detailed investigations are still required to determine the precise mechanism(s) of action of these regulators and to establish the optimal clinical protocols of negative regulators alone or in association with positive regulators for the treatment of various haematological diseases and cancer.

Animals↗
PubMed1983

Lymphocytes bearing both T and B markers in lymphoproliferative disorders.

The appearance of dual-marked (D) lymphocytes, i.e. lymphocytes having both T and B markers, was investigated in patients with acute (ALL) and chronic lymphocytic leukaemia (CLL) as well as with non-Hodgkin's lymphoma (NHL). E-rosette and immunobead-rosette techniques were combined and simultaneously administered, and the combination was found to be simple, fast and reproducible. D cells could be detected also in normal peripheral blood, however, only in a low percentage. In the blood of 4 patients suffering from ALL, in 2 with CLL and in 1 with NHL the number of D cells were increased significantly. In ALL the relative number of these cells decreased during remission and increased in relapses; thus the determination of the relative frequency of D cells might have prognostic value and could be useful in the choice of an optimal therapeutic protocol.

Adult↗
PubMed1991

Oxytocin pharmacodynamics: effect of long infusions on uterine activity.

Despite common use in obstetrics for almost 50 years, there is still disagreement concerning optimal clinical protocols for the use of oxytocin. This disagreement arises in part from inadequate data on oxytocin pharmacokinetics and pharmacodynamics. This report evaluates the uterine response to fixed doses of oxytocin (1-3 mIU/min) over long infusion times (up to 120 min) in 10 patients with secondary arrest of dilatation. The uterine activity increased from 132 +/- 61 Alexandria units during the control period to 199 +/- 64 Alexandria units at an infusion rate of 1 mIU/min. Increasing the infusion rate to 2 mIU/min increased the uterine activity to 240 +/- 64 Alexandria units. The uterine activity increased until a steady state was achieved between 40 and 70 min after the initiation of infusion. Continuing the infusion at a fixed rate for more than 90 min appears to result in a decreasing uterine activity. Patients requiring oxytocin for augmentation of labor developed adequate uterine activity with dose rates of 1-3 mIU/min. Clinical protocols for oxytocin augmentation with an interval of 40-60 min between increases in the dosing seem reasonable based on these pharmacodynamic data.

Dose-Response Relationship, Drug↗
PubMed1995

A method of human semen centrifugation to minimize the iatrogenic sperm injuries caused by reactive oxygen species.

Current techniques of sperm preparation for in vitro fertilization or intrauterine insemination require centrifugation of human semen to separate spermatozoa from the seminal plasma. Centrifugation increases reactive oxygen species (ROS) formation in semen. Moreover, high levels of ROS are associated with sperm membrane injury through spontaneous lipid peroxidation, which may alter sperm function. We investigated the relationship between centrifugation variables (time and g-force) and ROS production to establish an optimal centrifugation protocol for sperm preparation techniques. Semen from 38 men (24 patients and 14 normal volunteers) was evaluated for the formation of ROS before centrifugation and after centrifugation at 200 g for 2 or 10 min and after 500 g for 2 or 10 min. The absence of white blood cells in semen which can also produce ROS was determined with the myeloperoxidase technique (Endtz test). All specimens were negative (< 1 x 10(6)/ml) by the Endtz test. The formation of ROS was measured by chemiluminescence. ROS formation was regarded as high (positive) when the chemiluminescence response was at least 10 x 10(4) counted photons/min (cpm). The sperm concentration in each sample was adjusted to 15-20 x 10(6) cells/ml before analysis. Eight specimens (7 patients and 1 donor) exhibited high levels of ROS before centrifugation. All 8 showed further, significant increases in ROS formation regardless of g-force or time. The increase in ROS was significantly less when semen was centrifuged for 2 as compared to 10 min (p < 0.001). Six specimens previously ROS-negative became ROS-positive after centrifugation for 10 min at 200 and 500g. We conclude that the time of centrifugation is more important than g-force for inducing ROS formation in semen. Based on these results, we recommend a shorter centrifugation period in the preparation of sperm for assisted reproductive techniques.

Centrifugation↗
PubMed2005

Ambulatory transcranial Doppler cerebral embolic signal detection in symptomatic and asymptomatic carotid stenosis.

BACKGROUND AND PURPOSE: Transcranial Doppler (TCD) ultrasound can detect asymptomatic emboli in carotid stenosis. Current systems are nonportable and can only record for short durations. A novel ambulatory TCD system allows prolonged recording. We applied this to patients with symptomatic and asymptomatic carotid stenosis to determine patterns of embolization in the 2 conditions and optimal recording protocols. METHODS: Ambulatory TCD recordings were performed in 12 symptomatic and 15 asymptomatic carotid stenosis (> or =50%) patients for 8 hours and then repeated on a second occasion. RESULTS: Nine (75%) of symptomatic subjects had embolic signals during the first recording. In this group, repeating the recording did not increase the proportion of positive patients. In asymptomatic patients, 4 (26.7%) had embolic signals on 1 recording, and this proportion increased to 46.7% after 2 recordings. There was significant clustering of embolic signals demonstrating that the process was nonrandom. CONCLUSIONS: Ambulatory TCD is possible in patients with carotid artery stenosis. By increasing the duration of recording, additional information is provided, particularly in asymptomatic patients. Our results also demonstrate clustering of embolic signals. Our study provides baseline data to allow studies in both asymptomatic and symptomatic carotid stenosis to be planned.

Aged↗
PubMed1999

Functional magnetic stimulation of the abdominal muscles in humans.

Functional magnetic stimulation (FMS) of the thoracic nerve roots to simulate cough has been suggested as a treatment approach in patients unable to voluntarily activate the abdominal muscles. However, factors that could influence the efficacy of FMS in clinical use have not been evaluated. In the present investigation we studied train length, posture, and frequency to determine the optimal stimulation protocol. We also evaluated the use of a valve at the mouth to enhance glottic function and investigated whether lung volume at the time of stimulation would influence the tension generated by the abdominal muscles. Studies were performed using a Magstim rapid stimulator augmented by four booster packs in nine healthy subjects; we measured the change in gastric (DeltaPga(FMS)), esophageal (DeltaPes(FMS)), and mouth pressure and expiratory flow. With our apparatus pressure generation was maximized by having a train length of at least 300 ms and a frequency of 25 Hz. Posture and valve use were not important determinants of DeltaPga(FMS) or DeltaPes(FMS). Lung volume exerted only a minor influence on DeltaPga(FMS), but the ratio DeltaPes(FMS):DeltaPga(FMS) was increased at TLC compared with FRC. Expiratory flow was increased by adopting a seated posture and using an occlusion valve with an opening threshold close to the maximum DeltaPes(FMS) generated by the stimulus train; however, expiratory flow was susceptible to interference from glottic incoordination. Representative results (with train length 600 ms, 25 Hz, and 100% power, seated) were mean DeltaPga(FMS), 166 cm H(2)O; mean DeltaPes(FMS), 108 cm H(2)O; and mean expiratory flow, 311 L/min. We confirm that FMS of the abdominal muscles can generate a substantial positive intra-abdominal and intrathoracic pressure and, consequently, expiratory flow in normal subjects.

Abdominal Muscles↗
PubMed1994

Prejunctional angiotensin II receptors. Facilitation of norepinephrine release in the human forearm.

To determine if peripheral angiotensin II (Ang II) prejunctional receptors facilitating NE release exist in humans, we used [3H]NE kinetic methodology to measure forearm NE spillover during intrabrachial arterial Ang II infusions in eight normal male subjects. We used the following protocol to optimize conditions for demonstrating these receptors: (a) lower body negative pressure (-15 mmHg) to increase sympathetic nerve activity to skeletal muscle; and (b) intraarterial nitroprusside to maintain a high constant forearm blood flow (approximately 10 ml/min.100 ml) to maximize the proportion of neuronally released NE that spills over into the circulation. During lower body negative pressure, the following were infused intraarterially for three consecutive 20-min periods: saline, Ang II (4 ng/min), and Ang II (16 ng/min). During the Ang II infusions, forearm venous NE increased significantly from 173 to 189 and 224 pg/ml (P < 0.01), and forearm NE spillover increased from 384 to 439 and 560 ng/min.100 ml (P < 0.05 for high Ang II). Forearm NE clearance was unchanged. During low and high dose Ang II, the plasma venous Ang II concentrations were 25 and 97 pM, respectively. Since normal subjects increase plasma Ang II from 4 to 20-22 pM with exercise, standing, or diuretic administration, and patients with severe congestive heart failure can have a plasma Ang II of approximately 25 pM at rest, we suggest that Ang II might facilitate NE release in severe congestive heart failure, especially under conditions of stress.

Adult↗
PubMed1997

Antigen retrieval immunohistochemistry: past, present, and future.

The antigen retrieval (AR) technique, which is predominantly based on high-temperature heating of tissues, is used as a non-enzymatic pretreatment for immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections. It has been widely applied in pathology and analytical morphology. The existence of a growing body of literature on the AR technique raises a number of interesting issues for the further development of AR. These issues include the use of a "test battery" and the concept of "maximal retrieval" applied to the selection of optimal test protocols for the standardization of AR.

Animals↗
PubMedDate not supplied

Factors affecting bone loss in female endurance athletes: a two-year follow-up study.

BACKGROUND: Low bone mass leading to stress fractures is a well-known and yet unsolved problem among female athletes. PURPOSE: To quantify the rate of bone loss in healthy female athletes and investigate the effects of estrogen and vitamin K supplementation on bone loss. STUDY DESIGN: Prospective cohort study. METHODS: We classified 115 female endurance athletes into amenorrheic, eumenorrheic, or estrogen-supplemented groups and randomized them to receive either placebo or vitamin K(1). The bone mineral densities of the subjects' femoral neck and lumbar spine were measured at baseline and after 2 years. RESULTS: Bone mineral density in the lumbar spine remained constant, but bone density in the femoral neck had decreased significantly after 2 years in all three subgroups. The decrease was higher in amenorrheic (-6.5% +/- 4.0%) than in eumenorrheic (-3.2% +/- 4.1%) and estrogen-supplemented athletes (-3.9% +/- 3.1%). Supplementation with vitamin K did not affect the rate of bone loss. CONCLUSIONS: The rate of bone loss in all three subgroups of female athletes was unexpectedly high; neither estrogen nor vitamin K supplementation prevented bone loss. CLINICAL RELEVANCE: High-intensity training maintained over several years must be regarded in women as a risk factor for osteoporosis, and protocols for optimal treatment should be developed.

Adolescent↗
PubMed1997

Contamination in expressed breast milk following breast cleansing.

The purpose of this study was to determine if preexpression breast cleansing reduced the bacterial count in expressed breast milk. The study involved the collection of 178 breast milk samples (89 matched samples); 38 matched samples were from mothers of term infants and 51 matched samples were from mothers of preterm infants. One half of the samples were collected following breast cleansing with Phisoderm and tap water. The other half were collected following breast cleansing with tap water only. Hand and equipment washing with Phisoderm and tap water preceded all sample collections. Storage containers were sterile. Samples were cultured for pathogenic and nonpathogenic bacteria and examined at 24 and 48 hours. Data were analyzed by Wilcoxon Matched-Pairs sign test and Chi square. Breast cleansing with Phisoderm and water was not more effective than water alone at reducing nonpathogenic bacteria or eliminating pathogenic bacteria. Mothers of preterm infants had higher levels of both nonpathogenic and pathogenic bacteria than mothers of full-term infants. The most common form of bacterial contamination was coagulase-negative Staphylococcus epidermidis. This particular bacteria is found in higher levels in the stools of breast fed infants than formula fed infants and it also the most common contaminant found in the blood of preterm infants who develop sepsis. The findings of this study reveal that chemical interventions may not be effective at rendering breast milk free from pathogenic bacteria. More research is needed to determine the optimal cleansing protocol to achieve bacterial decontamination of breast milk or to determine the clinically acceptable level of contamination based on the effects on infants.

Chi-Square Distribution↗
PubMed2006

Use of pooled samples for the detection of Salmonella in feces by polymerase chain reaction.

Many epidemiological studies of Salmonella rely on conventional bacteriological culture methods to detect Salmonella in fecal samples. These culture-based methods are inefficient for epidemiological studies in populations with a low prevalence of Salmonella. The objective of this study was to optimize a protocol that uses pooled Salmonella enrichment broth cultures of bovine feces and polymerase chain reaction (PCR) for the detection of the invA gene of Salmonella in feces. In one field trial, 196 animals were sampled, and all samples were tested by culture, invA PCR on individual samples, invA PCR on pools of 5 samples, and BAX PCR on individual samples. All assays showed a high agreement on individual samples (kappa > or = 0.75). The invA PCR was run on each of 40 pools and detected 19 of 22 culture-positive pools. In another field trial, 152 samples were taken from 4 dairies, and the invA PCR was performed on pools of 5 samples in addition to bacteriological culture of individual samples. Salmonella was detected in 5 of the 32 pools (7 total positive samples) by both PCR and culture. One pool was PCR-positive but culture-negative. Pooling did not dramatically affect the performance of the invA PCR; most of the culture-positive samples were detected, including all of the samples when there were 4 or more Salmonella colonies on the agar plate. Based on these field trials, invA PCR on pooled samples appears to be an efficient method of Salmonella detection as long as Salmonella loads are not extremely low.

Animals↗
PubMed2003

A homogeneous 384-well high-throughput binding assay for a TNF receptor using alphascreen technology.

To take advantage of the growing knowledge of cellular signaling pathways, modern-day drug discovery faces an increasing challenge to develop assays to screen for compounds that modulate protein-protein interactions. One bottleneck in achieving this goal is a lack of suitable and robust assay technologies amenable to a high-throughput format. In this report, we describe how we utilized Alphascreen trade mark technology to develop a high-throughput assay to monitor ligand binding to a member of the tumor necrosis factor receptor superfamily. We expressed a fusion protein consisting of the extracellular domain of the OX40 receptor with the constant domains of human IgG. In the presence of OX40 ligand, we determined a binding affinity constant consistent with reported values and optimized the protocol to develop a simple, homogeneous, and sensitive binding assay in a 384-well format. Finally, we assessed if this system could identify small peptides capable of inhibiting the OX40 receptor and ligand interaction. The results showed that the assay was able to detect such peptides and could be used to launch a high-throughput screening campaign for small molecules able to prevent OX40 receptor activation.

Biochemistry↗
PubMed2006

Development of a microsphere-based p38alpha MAP kinase no-wash assay.

A nonradioactive, microsphere-based, no-wash assay for the measurement of p38alpha mitogen-activated protein (MAP) kinase activity was established. In this assay, a glutathione-S-transferase activating transcription factor 2 (amino acids 19-96) fusion protein (GST-ATF-2) was used as substrate for p38alpha MAP kinase. The assay involves immobilization of GST-ATF-2 on glutathione-microspheres (GSH-microspheres), addition of test solution containing p38alpha MAP kinase and test compounds, and measurement of the respective substrate phosphorylation with the aid of a bi-phospho-specific antibody. The optimization of test conditions is described in this article. With an optimized standard protocol, p38alpha MAP kinase inhibitors were investigated and IC50 values were compared to those derived using known assays. This assay might be useful in testing drug candidates.

Activating Transcription Factor 2↗