Immunochemical cross-reactivity between the dissociated capsid proteins of PVY group plant viruses

Primary (4–5-week) and long-term (12-week) antisera were elicited against the pyrrolidine-dissociated capsid proteins (D-proteins) of tobacco etch virus (TEV) and potato virus Y (PVY), and subsequently used to ascertain the degree of immunochemical cross-reactivity between several PVY group viral D-proteins. Primary antisera were highly specific for homologous antigen. However, immunodiffusion and cross-absorption experiments with long-term anti-TEV D-protein and anti-PVY D-protein sera revealed pronounced cross-reactivity among the D-proteins of 14 different PVY group viruses. Furthermore, all cross-reactions involved the same antibody population except in the case of celery mosaic virus (CeMV) D-protein where but a portion of the antibody population was reactive. Spur formation in immuno-diffusion experiments was only observed among heterologous D-proteins when they were either adjacent to homologous D-protein antigen or (in an opposite direction) when compared with CeMV D-protein. Wheat streak mosaic virus dissociated protein, in contrast, was not found to be cross-reactive with PVY group D-proteins in reciprocal tests, and no cross-reactions were observed with the dissociated proteins of 6 additional viruses outside the PVY group.     

Recommendations on performance characteristics of diagnostic exposure meters: report of AAPM Diagnostic X-Ray Imaging Task Group No. 6.

Task Group 6 of the Diagnostic X-Ray Imaging Committee of the American Association of Physicists in Medicine (AAPM) was appointed to develop performance standards for diagnostic x-ray exposure meters. The recommendations as approved by the Diagnostic X-Ray Imaging Committee and the Science Council of the AAPM are delineated in this report and provide specifications on meter precision, calibration accuracy, calibration reference points, linearity, energy dependence, exposure rate dependence, leakage, amplification gain settings, directional dependence, the stem effect, constancy checks, and calibration intervals. The report summarizes recommendations for meters used in mammography, general purpose radiography including special procedures, computed tomography, and radiation safety surveys for x-ray radiography.     

Limiting factors for cytopathological diagnosis of high-grade squamous intraepithelial lesions: a cytohistological correlation between findings in cervical smears and loop electrical excision procedure.

The present study sought possible factors leading to the cytological diagnosis of atypical squamous cells of uncertain significance (ASCUS) in cases of high-grade squamous intraepithelial lesions (HSIL). Based on retrospective histopathological analysis of loop electrical excision procedure (LEEP) products that diagnosed HSIL, two study groups were randomly selected. The first was consisted of cases with two consecutive Papanicolaou (Pap) smears with the diagnosis of ASCUS. The second (control) group was represented by cases diagnosed as HSIL by cytology. From the Pap smears diagnosed as ASCUS, the sampling limitations was different from control group (P < 0.05). The median size of the largest lesion in each case with ASCUS was 2.66 mm (+/- 1.71 mm). In the control group, the median size of the largest lesion was 5.15 mm (+/-2.58 mm) (P < 0.05). The size of the lesion and sample limitations led patients with cervical intraepithelial neoplasms to be diagnosed as ASCUS for two consecutive times, after a 6-mo period.     

Attenuation of ethanol tolerance by a novel stimulus

A Pavlovian conditioning model of tolerance emphasizes that an association between predrug cues and the systemic effects of the drug contributes to tolerance. On the basis of this model, established tolerance should be attenuated by external inhibition, i.e., by presentation of a novel, extraneous stimulus. This prediction was evaluated in the present experiment. Rats that were so tolerant to the hypothermic effect of ethanol that they evidenced no drug-induced decrease in temperature were presented with a bright strobe light following ethanol administration. The light precipitated a large decrease in temperature in these rats. These results provide further evidence that tolerance to the hypothermic effect of ethanol is, in part, mediated by learning.     

186Re-labeled antibodies to p185HER2 as HER2-targeted radioimmunopharmaceutical agents: comparison of physical and biological characteristics with 125I and 131I-labeled counterparts

Overexpression of the HER2/neu protooncogene has been shown to correlate with poor clinical prognosis. A murine monoclonal antibody (4D5) directed against the extracellular domain (ECD) of p185HER2 has been shown to inhibit in vitro and in vivo growth of carcinomas overexpressing HER2 and has been humanized (rhuMAb HER2). The objective of the study was the identification of an agent which might be useful for in vitro studies, tumor imaging and/or radioimmunotherapy by linking beta-emitting radionuclides to these HER2-targeted antibodies. Murine 4D5 and humanized rhuMAb HER2 were radiolabeled with 125I, 131I or 186Re. Physical characteristics (TCA precipitability, SDS-PAGE, size exclusion chromatography), binding affinities to the HER2 ECD (in an ELISA and on SK-BR-3 cells) and antiproliferative activities of the radiolabeled antibodies were determined. Although 131I-4D5 and 131I-rhuMAb HER2 usually retained > 85% ECD binding, they exhibited increased aggregation and fragment content, drastically reduced antiproliferative activities and poor stability upon storage at 4 degrees C. For these antibody preparations, conservation of binding did not necessarily correlate with preservation of bioactivity indicating the importance of bioactivity determinations in radiolabeled antibody studies. Conversely, 4D5 and rhuMAb HER2 labeled with 125I or 186Re maintained physical properties, ECD binding, antiproliferative activities and were stable upon storage at 4 degrees C for at least 8 days. The superior retention of physical and biological characteristics of 186Re-labeled 4D5 and rhuMAb HER2 compared with their 131I-labeled counterparts suggests the potential for their use as radioimaging and radioimmunotherapeutic agents in the treatment of HER2 overexpressing tumors.     

A specific chromosome breakpoint associated with mouse plasmacytomas.

The chromosomes of uncultured cells of the near-diploid mouse plasmacytoma MOPC-31C were studied. The modal number of chromosomes was 44. The tumor lacked two marker chromosomes, reciprocal translocation [rcp t(12; 15)], that in previous studies were found to be common to 3 other uncultured myelomas and 1 cultured mouse myeloma. Through the formation of two markers, rcp t(6; 15), unique to this tumor, however, the tumor shared with other tumors and their specific markers a common breakpoint in chromosome "15 at band D3/E. This breakpoint has been found in all mouse plasmacytomas examined with banding thus far and is considered of possible importance in the development of this tumor.     

Altered coriolis stress susceptibility in essential hypertension

Patients with hypertension frequently have vague complaints of dizziness and many other symptoms experienced by healthy individuals with motion sickness. We examined vestibular function in patients with essential hypertension, and we determined whether patients with essential hypertension are more prone to motion sickness using Coriolis stress testing. Vestibular function and Coriolis stress susceptibility were measured in 12 normotensive (NT) and seven asymptomatic patients with mild essential hypertension (HT). The Coriolis stress susceptibility index (CSSI) was calculated from the number of head movements in the four cardinal directions an individual could complete while being rotated in a computerized chair at increasing velocity before they developed motion sickness. The patients with hypertension had normal vestibular function and normal vestibuloocular responses as measured by standard techniques. Subjects with hypertension had significantly decreased Coriolis stress susceptibility scores compared to normotensive subjects (NT, 29.70 +/- 4.8; v HT, 5.48 +/- 2.0, P less than .001) and significantly decreased suppression of postrotatory nystagmus (NT, 44.5% +/- 3.8; v HT, 19.1% +/- 6.9, P less than .05). Medical treatment of hypertension did not result in an increased tolerance to provocative stimuli for motion sickness. It is suggested from our data that an increased susceptibility to motion sickness and abnormal vestibular responses to normal motion may account for many of the vague symptoms of "dizziness" reported by a large number of hypertensive patients.     

Clinical measurement, statistical analysis, and risk-benefit: controversies from trials of spinal injury

BACKGROUND: The National Acute Spinal Cord Injury Studies have been a series of trials assessing the role of pharmacologic agents in the prevention of secondary neuronal damage after acute spinal cord injury. METHODS: The trials were multicenter randomized, controlled studies. RESULTS: Two trials have demonstrated the efficacy of high-dose methylprednisolone in improving neurologic and functional recovery and have shown a reassuring safety profile. CONCLUSION: This study responds to a recent commentary on these trials and examines in particular the roles of clinical measurement, statistical analysis, and risk benefit in assembling evidence for or against innovative therapies.     

Diagnosis of pulmonary embolism: Ventilation perfusion scintigraphy versus helical computed tomography pulmonary angiography

The present study compared the accuracy of ventilation perfusion scintigraphy (VQS) and CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism. This was a prospective observational study of 112 patients with suspected pulmonary embolism (PE) who could be studied with both investigations within 24 h. Results were compared to final diagnosis at completion of 6-month follow up, using receiver operating characteristic (ROC) analysis. Pulmonary embolism was diagnosed in 27 referred patients (24%). The sensitivity and specificity of VQS and CTPA were similar to that reported from the literature. A normal VQ scan had the highest negative predictive value (100%), while a high-probability VQ scan had the highest positive predictive value (92%). There was no overall difference (area under the ROC curve (AUC)) between VQS (AUC (95% CI) = 0.82 (0.75,0.89)) and CTPA (AUC = 0.88 (0.81,0.94)) for the diagnosis of PE. Among patients with abnormal chest X-rays, CTPA (AUC 0.90 (0.83,0.97)) appeared somewhat better than VQS (AUC 0.78 (0.68,0.88)) but this difference did not reach statistical significance. In this instance, CTPA is at least as accurate as VQS and may provide an opportunity to make alternative diagnoses.