Underreporting of AIDS cases in Canada: a record linkage study.

To estimate the rate of underreporting of AIDS (acquired immune deficiency syndrome) to the Federal Centre for AIDS (FCA), in 1988 the initials, date of birth and place of residence of 66 patients with AIDS known to the Toronto Sexual Contact Study (TSCS), 65 patients with AIDS known to the Vancouver Lymphadenopathy-AIDS Study (VLAS) and other participants in both studies who did not have AIDS were sent to the Bureau of Epidemiology and Surveillance, FCA. The FCA conducted a manual record linkage to link these data to the national registry of reported cases. The rate of underreporting was 12% (8/65) for the VLAS and 18% (12/66) for the TSCS. The specific diagnosis was not related to the rate of underreporting. For the TSCS the rate of underreporting had increased from 0% in 1983-84 to 44% in 1987-88 (p = 0.001). Differences in the observed rates of underreporting between the two studies are likely the result of differences in the reporting responsibilities of physicians involved in the studies.     

Randomised comparison of procedures for obtaining informed consent in clinical trials of treatment for cancer.

Methods of obtaining informed consent have evolved differently in Western countries without substantive information on the impact of these different practices on the patients. A randomised study was performed to compare two commonly adopted methods of seeking consent to randomised treatment: an individual approach at the discretion of each doctor and a uniform policy of total disclosure of all relevant information. The impact of both consent procedures on the patient''s understanding and anxiety levels and on the doctor-patient relationship was assessed by means of a questionnaire given soon after the consent interview. Fifty seven patients were assigned at random to two groups: to 29 patients an individual approach to seeking consent was adopted and to 28 patients all relevant information was given. Seven patients refused consent to randomised treatment, with slightly more refusals by patients in the total disclosure group (5 v 2, p = 0.25). The main effects of total disclosure of all information compared with an individual approach to seeking consent were: a better understanding of treatment and side effects and of research aspects of the treatments; less willingness to agree to randomised treatment; and increased anxiety. No significant differences were found in patients'' perceptions of the doctor-patient relationship. A repeat questionnaire given three to four weeks later no longer showed significant differences between the two groups.     

Effect of isoproterenol or exercise on pulmonary lymph flow and hemodynamics

Experiments were performed to determine whether different methods of increasing cardiac output would have similar effects on lung lymph flow, and to assess the contribution of the microvasculature (fluid-exchanging vessels) to the total calculated pulmonary vascular resistance. Yearling unanesthetized sheep with chronic vascular catheters and lung lymph fistulas underwent intravenous infusions of isoproterenol at 0.2 micrograms X kg-1. min-1 (n = 8) or were exercised on a treadmill (n = 16). Both isoproterenol and exercise increased cardiac output, lowered calculated total pulmonary and systemic vascular resistances, and had no effect on the calculated pulmonary microvascular pressure. Isoproterenol infusions did not affect lung lymph flow, whereas exercise increased lung lymph flow in proportion to the increase in cardiac output. We conclude that 1) the sheep has a different pulmonary hemodynamic response to exercise than dogs and man, 2) the microvasculature is recruited during exercise-induced but not isoproterenol-induced increases in cardiac output, and 3) the microvasculature represents only a small proportion of the total calculated pulmonary vascular resistance.     

Kinetic and equilibrium studies of cyclomalto-octaose (γ-cyclodextrin)-methyl orange inclusion complexes

Measurements of the equilibrium and temperature-jump u.v., visible, and induced c.d. spectra of Methyl Orange (MO) in the presence of cyclomalto-octaose (γ-cyclodextrin, γ-CD) have been carried out. Three mechanistic steps were detected through the temperature-jump data (25.0°):

where K₁, K₂, and K₃ are 45 (±7), 2.0 (±1.1) × 10⁶, and 6.1 (±2.5) × 10³ dm³.mol^?1, respectively, k₂ = 9.4 (±5.1) × 10⁹ dm³.mol^?1.s^?1, and k_?2 = 4.8 (±0.8) × 10³ s^?1. The equilibrium u.v./visible data are also consistent with this reaction scheme. The high stability of the dimer inclusion complex (MO)₂ · γ-CD compared to that of the monomer inclusion complex MO · γ-CD appears to be related to the annular diameter of γ-CD and demonstrates a degree of selectivity in cyclodextrin inclusion complexes. The (MO)₂ · (γ-CD)₂ complex also contains a dimer, included by both γ-CD molecules.     

Evidence that treatment with vaccinia melanoma cell lysates (VMCL) may improve survival of patients with stage II melanoma

Summary A total of 80 patients with melanoma metastases in regional lymph nodes were treated by i.d. injections with a vaccine prepared from a vaccinia virus-infected allogeneic melanoma cell line; 39 patients have been followed for a 2-year period. Interim results from comparison of the treated group with 151 historical controls treated without the vaccine from September 1978 to December 1981 at the same institution and 56 non-randomized concurrent controls suggest that survival was significantly prolonged in the vaccinated group. At the 2-year period overall survival was 75% in the treated compared to 57% in the historical control group. Subset analysis showed a greater apparent benefit of vaccine therapy among patients who had metastases detected at the time of treatment of the primary melanoma (synchronous metastases), while therapy appeared less effective in patients with metastases detected at some time after treatment of the primary (delayed metastases). In the latter only those with one lymph node appeared to benefit from the treatment whereas in patients with synchronous metastases patients with three or more nodes as well as one node appeared to have improved survival. The survival rates at 2 years for treated patients with synchronous metastases in one, two, three or more lymph nodes was 100%, 83% and 79% respectively compared with that of 82%, 86% and 47% respectively in the equivalent control groups. Survival rates in treated patients with delayed metastases in one, two, three or more lymph nodes was 70%, 70% and 65% compared with 47%, 42% and 35% in the equivalent control groups. Treatment and control groups appeared well matched for a number of known prognostic features, including number and size of involved nodes, sex and thickness of primary tumor. Multivariate analysis indicated the effect of treatment was independent of these factors. Despite the empiricism of this approach the present results suggest that this form of therapy warrants further evaluation in a randomized controlled trial.     

Cryo neutron crystallography demonstrates influence of RNA 2′-OH orientation on conformation,sugar pucker and water structure

The ribose 2′-hydroxyl is the key chemical difference between RNA and DNA and primary source of their divergent structural and functional characteristics. Macromolecular X-ray diffraction experiments typically do not reveal the positions of hydrogen atoms. Thus, standard crystallography cannot determine 2′-OH orientation (H2′-C2′-O2′-HO2′ torsion angle) and its potential roles in sculpting the RNA backbone and the expansive fold space. Here, we report the first neutron crystal structure of an RNA, the Escherichia coli rRNA Sarcin-Ricin Loop (SRL). 2′-OD orientations were established for all 27 residues and revealed O-D bonds pointing toward backbone (O3′, 13 observations), nucleobase (11) or sugar (3). Most riboses in the SRL stem region show a 2′-OD backbone-orientation. GAGA-tetraloop riboses display a 2′-OD base-orientation. An atypical C2′-endo sugar pucker is strictly correlated with a 2′-OD sugar-orientation. Neutrons reveal the strong preference of the 2′-OH to donate in H-bonds and that 2′-OH orientation affects both backbone geometry and ribose pucker. We discuss 2′-OH and water molecule orientations in the SRL neutron structure and compare with results from a solution phase 10 μs MD simulation. We demonstrate that joint cryo-neutron/X-ray crystallography offers an all-in-one approach to determine the complete structural properties of RNA, i.e. geometry, conformation, protonation state and hydration structure.