Biomedical subjects
P Ross
Publications and source records attributed to P Ross.
Calcification in liver metastases from neuroblastoma.
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Detection of unwanted residues of ivermectin in bovine milk by dissociation-enhanced lanthanide fluoroimmunoassay.
Avermectins are frequently used to control parasitic infestations in many animal species. Previous studies have shown the long-term persistence of unwanted residues of these drugs in animal tissues and fluids. An immunoassay screening test for the detection and quantification of ivermectin residues in bovine milk has been developed. After an extensive extraction procedure, milk samples were applied to a competitive dissociation-enhanced lanthanide fluoroimmunoassay using a monoclonal antibody against an ivermectin-transferrin conjugate. The monoclonal antibody, raised in Balb C mice, showed cross-reactivity with eprinomectin (92%), abamectin (82%) and doramectin (16%). The limit of detection of the assay (mean + 3 SD), calculated from the analysis of 17 known negative samples, was calculated as 4.6 ng/mL. Intra- and inter-assay RSDs were determined as 11.6% and 15.8%, respectively, using a negative bovine milk sample fortified with 25 ng/mL ivermectin. Six Friesian milking cows were treated with ivermectin, three with a pour-on formulation of the drug and three with an injectable solution at the manufacturer's recommended dose rate. An initial mean peak in ivermectin residue concentration was detected at day 4 (mean level = 47.5 ng/mL) and day 5 post-treatment (mean level = 26.4 ng/mL) with the injectable form and pour-on treatment, respectively. A second peak in residue concentration was observed using the DELFIA procedure 28 days post-treatment in both treatment groups (23.1 ng/mL injectable and 51.9 ng/mL pour-on). These second peaks were not confirmed by HPLC and must at this time be considered to be false-positive results. By day 35 after treatment the mean ivermectin residue concentration of both groups fell below the limit of detection of the assay.
An unusual case of hip septic arthritis due to Bacteroides fragilis in an alcoholic patient.
We describe a 53-year-old alcoholic man who presented with hip septic arthritis due to Bacteroides fragilis. This arthritis involved a severe destruction of the femoral head, which was completely devitalized. Recovery was achieved after 4 months of antimicrobial therapy with imipenem/cilastatin plus metronidazole, surgical debridement of the necrotic tissues and four sessions of hyperbaric oxygen.
Demonstration of radiation nephritis by computed tomography.
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Global methylation profiling of lung cancer identifies novel methylated genes.
Epigenetic changes, including DNA methylation, are a common finding in cancer. In lung cancers methylation of cytosine residues may affect tumor initiation and progression in several ways, including the silencing of tumor suppressor genes through promoter methylation and by providing the targets for adduct formation of polycyclic aromatic hydrocarbons present in combustion products of cigarette smoke. Although the importance of aberrant DNA methylation is well established, the extent of DNA methylation in lung cancers has never been determined. Restriction landmark genomic scanning (RLGS) is a highly reproducible two-dimensional gel electrophoresis that allows the determination of the methylation status of up to 2000 promoter sequences in a single gel. We selected 1184 CpG islands for RLGS analysis and determined their methylation status in 16 primary non-small cell lung cancers. Some tumors did not show methylation whereas others showed up to 5.3% methylation in all CpG islands of the profile. Cloning of 21 methylated loci identified 11 genes and 6 ESTs. We demonstrate that methylation is part of the silencing process of BMP3B in primary tumors and lung cancer cell lines.
An evaluation of the effectiveness of CT vs. other imaging modalities in the diagnosis of atypical renal masses.
A retrospective review of 34 patients undergoing nephrectomy for suspected renal malignancy was undertaken to evaluate the effectiveness of computed tomography (CT), ultrasound, arteriography, and cyst puncture in providing a definitive preoperative diagnosis of benign vs. malignant renal abnormality. The predictive value of a test suggesting malignancy was 88% for angiography, 86% for ultrasound, 71% for cyst puncture, and 80% for CT. The predictive value of a test suggesting no malignancy for non-CT imaging modalities was poor. The predictive value of renal CT increased to 96%, when three or more characteristics are present which suggest the lesion is not a simple, benign renal cyst. Using these criteria all malignancies were identified, and all but one benign lesion excluded. Unusual lesions that have equivocal or indeterminate diagnostic studies and only one or two noncystic CT features should undergo selective exploration rather than radical nephrectomy.
Portal vein measurement by ultrasonography in patients with long-standing cystic fibrosis: preliminary observations.
Adult cystic fibrosis (CF) patients are increasingly diagnosed with hepatic cirrhosis, cholecystitis, and cholelithiasis. A continuing diagnostic problem is the early detection of cirrhosis prior to diffuse liver involvement. Sonography has been used in evaluating the pancreas, gallbladder, liver, and spleen in cystic fibrosis patients. We used a real-time mechanical sector scanner to study the portal veins in adult CF patients randomly selected from our CF population and correlated the portal vein diameters with liver function studies. A measurement greater than 12 mm was interpreted as a probable sign of portal hypertension. Of 21 patients studied, 14 had portal veins that measured greater than 12 mm, and 12 patients had (although not necessarily at the time of the exam) elevated serum alkaline phosphatase levels. Three patients had associated splenomegaly and thrombocytopenia, and 10 patients also exhibited cholelithiasis and abnormal gallbladders on sonography. Initial results indicate that portal vein measurement may be a sensitive indicator of early portal hypertension. Sonography may, thus, isolate patients at high risk for possible future complications. Serial sonograms can be performed easily in evaluating the progress of liver disease.
Defining where, what, and how in a cost conscious manner can improve patient care in all areas.
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An EEG coherence test of the frontal dorsal versus ventral hypothesis in N-back working memory.
We examined Goldman-Rakic's conceptualization of working memory (WM) involving modality-specific reverbatory circuits using electrophysiological measures. An n-back WM task, with either spatial information or object information to be remembered, was administered with EEG coherence used to provide a functional measure of corticocortical communication. Support was not found for modality-specific WM systems in this task. Instead, results suggest that there is a circuit that connects dorsal frontal with dorsal parietal areas which is activated during all levels of the WM vigilance task, regardless of the type of stimuli involved. Data also suggest that left frontal areas are sensitive to the level of difficulty of the WM task (0,1,2, and 3-back), as well as familiarity of task demands. Overall, our results support a model that conceptualizes a unitary WM system rather than a system composed of separate WM circuits for different modalities.
Remnant atrial function in human and animal recipients of a total artificial heart.
The native atria remains intact after total artificial heart (TAH) implantation. The electrical activity of the recipient's atria can be recorded from wires placed during TAH implantation. Regulating TAH heart rate by coupling it with native atrial activity has the potential for a more physiologically responsive TAH. The reactivity of the atrial impulse rate is a critical component of this link, but little is known about atrial responsiveness after TAH placement. Two human and three animal TAH recipients had recordable atrial electrical activity. Human atrial impulse rate after TAH was relatively constant at rest but unresponsive to physiologic stimuli. Analysis of human atrial contraction provided no discernable effect on ventricular filling. Animal atrial impulse rate at rest was more rapid than calves without a TAH. The bovine TAH recipients had an atrial impulse rate that responded to catecholamine stimulation and blockade. Isoproterenol caused a significant rise in atrial impulse rate (152 +/- 16 impulses per minute to 216 +/- 24 impulses per minute; p < 0.05) and propranolol caused a decrease in atrial impulse rate (142 +/- 20 impulses per minute to 122 +/- 19 impulses per minute; p > 0.05). Despite beta blockade, the atrial impulse rate remained abnormally elevated secondary to unknown factors. Animal atrial contraction did appear to intermittently augment TAH ventricular filling. These data indicate that the atria remains electrically intact after TAH implantation. The human atrial impulse rate was unresponsive to physiologic stimuli although the animal atrial impulse rate was affected by exogenous catecholamine administration, but the rate remained abnormally rapid.(ABSTRACT TRUNCATED AT 250 WORDS)
Cerebral angiography--a chart.
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Advance directives: the price of life.
Advance directives support the concepts of patient autonomy and resource allocation. Promotion of advance directives by nurse managers according to the suggested paradigm should be an economic and policy priority.