Mitogenic activity of cell wall components from smooth and rough strains of Brucella abortus.

On the basis of [3H]thymidine incorporation by normal mouse spleen cell cultures, cell wall preparations from a smooth (45/0) strain and a rough (45/20) strain of Brucella abortus were strongly mitogenic. On the other hand, none of several subcomponents extracted from the cell wall preparations, including aqueous and phenolic lipopolysaccharides, was active. These results contrast with the marked mitogenic activity of lipopolysaccharides isolated from other gram-negative bacteria such as Salmonella typhimurium.     

Placental transport of vitamin B12 in the pregnant rat

Placental transport of vitamin B₁₂ was studied in the pregnant rat in two series of experiments. In the first series animals were given cyanocobalamin-⁵⁷Co intravenously at various stages of gestation. High specific activity tracer was used and doses of B₁₂ were 1-2 ng per animal. The rats were killed from 15 min to 24 hr after injection and the fetuses, placentas, and serum were assayed for radioactivity. In the second series using uninjected animals, absolute amounts of vitamin B₁₂ in fetuses and placentas were measured at stages of gestation from day 12 through day 20.     

[I] 5-Iodo-3-pyridyl ethers: syntheses and binding to neuronal nicotinic acetylcholine receptors

Three 3-pyridyl ether nicotinic ligands-(S)-5-Iodo-3-[(2-pyrrolidinyl)-methoxy]pyridine (5-iodo-A-85865), (S)-5-Iodo-3-[1-(methyl)-2-pyrrolidinyl-methoxy]pyridine (5-Iodo-A-84543), and (S)-5-iodo-3-[1-methyl-(2-azetidinyl)-methoxy]pyridine (5-iodo-N-Me-A-85380) were labeled with I-125/I-123, and their ability to label high-affinity brain nicotinic acetylcholine receptors (nAChRs) was evaluated. The most promising ligand, [^123/125I] 5-iodo-A-85865, showed approximately 65% inhibition of radioactivity uptake in thalamus in mice pretreated with cytisine. Preliminary SPECT imaging studies with [¹²³I] 5-iodo-A-85865 revealed a distribution profile consistent with nAChRs (thalamus > frontal cortex > cerebellum) and a more rapid pharmacokinetic profile relative to azetidinyl 3-pyridyl ether based ligands.     

Radiation dose of cardiac dual-source CT: the effect of tailoring the protocol to patient-specific parameters

Objective

To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients.

Materials and methods

Two hundred consecutive patients (68 women; mean age 61 ± 9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prospective ECG-triggering: 50 patients (any BMI, any HR) were examined with a standard, non-tailored protocol (helical CTCA, 120 kV, 330 mAs), whereas the other 150 patients were examined with a tailored protocol: 40 patients (group A, BMI ≤ 25 kg/sqm, HR ≤ 70 bpm) with sequential CTCA (100 kV, 190 mAs_ref), 43 patients (group B, BMI ≤ 25 kg/sqm, HR > 70 bpm) with helical CTCA (100 kV, 220 mAs), 28 patients (group C, BMI > 25 kg/sqm, HR ≤ 70 bpm) with sequential CTCA (120 kV, 330 mAs_ref), and 39 patients (group D, BMI > 25 kg/sqm, HR > 70 bpm) with helical CTCA (120 kV, 330 mAs). The effective radiation dose estimates were calculated from the dose-length-product for each patient. Image quality was classified as being diagnostic or non-diagnostic in each coronary segment.

Results

Image quality was diagnostic in 2403/2460 (98%) and non-diagnostic in 57/2460 (2%) of all coronary segments. No significant differences in image quality were found among all five CTCA protocols (p = 0.78). The non-tailored helical CTCA protocol was associated with a radiation dose of 9.0 ± 1.0 mSv, being significantly higher compared to that using sequential CTCA (group A: 1.3 ± 0.3 mSv, p < 0.001; group C: 2.9 ± 0.6 mSv, p < 0.001), and helical CTCA at reduced tube voltage and tube current (group B: 4.2 ± 0.6 mSv, p < 0.01). No significant differences were found compared to the non-tailored CTCA protocol in patients with HR > 70 bpm (group D: 8.5 ± 0.9 mSv, p = 0.51).

Conclusions

Dual-source CTCA is associated with radiation doses ranging between 1.3 and 9.0 mSv, depending on the protocol used. Tailoring of the CTCA protocol to the HR and BMI of the individual patient results in dose reductions of up to 86%, while maintaining a diagnostic image quality of the examination.     

Coronary 64-slice CT angiography predicts outcome in patients with known or suspected coronary artery disease

The aim of this study was to assess the prognostic value of 64-slice CT angiography (CTA) in patients with known or suspected coronary artery disease (CAD). Sixty-four-slice coronary CTA was performed in 220 patients [mean age 63 ± 11 years, 77 (35%) female] with known or suspected CAD. CTA images were analyzed with regard to the presence and number of coronary lesions. Patients were followed-up for the occurrence of the following clinical endpoints: death, nonfatal myocardial infarction, unstable angina, and coronary revascularization. During a mean follow-up of 14 ± 4 months, 59 patients (27%) reached at least one of the predefined clinical endpoints. Patients with abnormal coronary arteries on CTA (i.e., presence of coronary plaques) had a 1st-year event rate of 34%, whereas in patients with normal coronary arteries no events occurred (event rate, 0%, p < 0.001). Similarly, obstructive lesions (≥50% luminal narrowing) on CTA were associated with a high first-year event rate (59%) compared to patients without stenoses (3%, p < 0.001). The presence of obstructive lesions was a significant independent predictor of an adverse cardiac outcome. Sixty-four-slice CTA predicts cardiac events in patients with known or suspected CAD. Conversely, patients with normal coronary arteries on CTA have an excellent mid-term prognosis.     

Low kilovoltage cardiac dual-source CT: attenuation,noise, and radiation dose

The purpose of this study was to investigate the effect of low kilovoltage dual-source computed tomography coronary angiography (CTCA) on qualitative and quantitative image quality parameters and radiation dose. Dual-source CTCA with retrospective ECG gating was performed in 80 consecutive patients of normal weight. Forty were examined with a standard protocol (120 kV/330mAs), 20 were examined at 100 kV/330mAs, and 20 at 100 kV/220mAs. Two blinded observers independently assessed image quality of each coronary segment and measured the image parameters noise, attenuation, and contrast-to-noise ratio (CNR). The effective radiation dose was calculated using CT dose volume index and the dose-length product. Diagnostic image quality was obtained in 99% of all coronary segments (1,127/1,140) without significant differences among the protocols. Image noise, attenuation, and CNR were significantly higher for 100 kV/330mAs (26 +/- 3 HU, 549 +/- 62 HU, 25.5 +/- 3.2; each P < 0.01) and 100 kV/220mAs (27 +/- 2 HU, 560 +/- 43 HU, 25.0 +/- 2.2; each P < 0.01) when compared to the 120-kV protocol (21 +/- 2 HU, 317 +/- 28 HU, 20.6 +/- 1.7). There was no significant difference between the two 100-kV protocols. Estimated effective radiation dose of the 120-kV protocol (8.9 +/- 1.2 mSv) was significantly higher than the 100 kV/330mAs (6.7 +/- 0.8 mSv, P < 0.01) or 100 kV/220mAs (4.4 +/- 0.6 mSv, P < 0.001) protocols. Dual-source CTCA with 100 kV is feasible in patients of normal weight, results in a diagnostic image quality with a higher CNR, and at the same time significantly reduces the radiation dose.     

Comparison of diagnostic accuracy of 64-slice computed tomography coronary angiography in patients with low, intermediate, and high cardiovascular risk

RATIONALE AND OBJECTIVES: The aim of this study was to compare the diagnostic accuracy of 64-slice computed tomographic coronary angiography (CTCA) in groups of patients with low, intermediate, and high risk for coronary artery disease (CAD) events. MATERIALS AND METHODS: The institutional review board approved this study; written informed consent was obtained from all patients. Eighty-eight consecutive patients with suspected CAD (40 women; mean age, 64.3 +/- 9.4 years; range, 39-82) underwent CTCA, calcium scoring, and invasive coronary angiography and were grouped according to their Framingham 10-year risk for hard coronary events into low (<10%), intermediate (10%-20%), and high (>20%) risk categories. Significant stenoses (luminal diameter narrowing > or =50%) were assessed on an intention-to-diagnose-basis; no coronary segment was excluded and nonevaluative segments were rated false positive. To determine differences between groups, Kruskal-Wallis tests were performed for individually determined values of diagnostic performance. RESULTS: Per-patient sensitivity, specificity, negative predictive, and positive predictive values were 90.0%, 79.2%, 95.0%, and 64.3%, respectively, with low (n = 34), 87.5%, 92.3%, 85.7%, and 93.3%, respectively, with intermediate (n = 29), and 100%, 75.0%, 100%, and 89.5%, respectively, with high risk (n = 25), with a trend toward higher positive predictive value (P = .07). Per-segment negative predictive value was lower with high pretest probability (P < .01). Mean calcium-score units were 90, 220, and 312 (P = .23), and the prevalence of CAD was 29.4%, 55.2%, and 68.0% (P < .01) with low, intermediate, and high risk. CONCLUSION: Sensitivity and specificity of CTCA are not influenced by the prevalence of CAD, whereas the negative predictive value is lower and the positive predictive value tends to be higher in patients with a high prevalence of CAD.     

Automated detection of single nucleotide polymorphism in beta-2 adrenergic receptor gene using LCx(R).

Beta-2 adrenergic receptor (B2AR) agonists are the most widely prescribed rescue agents used in the treatment of asthma. Recent studies have indicated a relationship between a polymorphism at codon 16 of the B2AR gene, and the response to recurrent beta-agonist therapy. The B2AR polymorphism of interest involves a single nucleotide change from A to G, resulting in an amino acid change from Arginine (Arg) to Glycine (Gly). Clinical efforts to further investigate this relationship require an accurate, reliable and inexpensive method for detecting the polymorphism.In this study, we report an LCx(R) assay for the detection of a single nucleotide polymorphism at codon 16 of the beta-2 adrenergic receptor. This assay is capable of detecting patients harboring any of the three possible genotypes at this locus, namely, homozygous wild type, homozygous variant or heterozygous individuals with a single genomic DNA sample of 25-500 ng. It requires minimum hands-on time with automated detection. The assay would be suitable for use in research labs for screening of a large number of samples. We believe that this type of assay will facilitate research and clinical investigations in elucidating the association of SNPs with disease states, diagnosis, prognosis and treatment.