Autosomal dominant hypertension and brachydactyly in a Turkish kindred resembles essential hypertension

1. The aim of this study was to investigate, by use of spectral analysis, (1) the blood pressure (BP) variability changes in the conscious rat during blockade of nitric oxide (NO) synthesis by the L-arginine analogue NG-nitro-L-arginine methyl ester (L-NAME); (2) the involvement of the renin-angiotensin system in these modifications, by use of the angiotensin II AT1-receptor antagonist losartan. 2. Blockade of NO synthesis was achieved by infusion for 1 h of a low-dose (10 micrograms kg-1 min-1, i.v., n = 10) and high-dose (100 micrograms kg-1 min-1, i.v., n = 10) of L-NAME. The same treatment was applied in two further groups (2 x n = 10) after a bolus dose of losartan (10 mg kg-1, i.v.). 3. Thirty minutes after the start of the infusion of low-dose L-NAME, systolic BP (SBP) increased (+10 +/- 3 mmHg, P < 0.01), with the effect being more pronounced 5 min after the end of L-NAME administration (+20 +/- 4 mmHg, P < 0.001). With high-dose L-NAME, SBP increased immediately (5 min: +8 +/- 2 mmHg, P < 0.05) and reached a maximum after 40 min (+53 +/- 4 mmHg, P < 0.001); a bradycardia was observed (60 min: -44 +/- 13 beats min-1, P < 0.01). 4. Low-dose L-NAME increased the low-frequency component (LF: 0.02-0.2 Hz) of SBP variability (50 min: 6.7 +/- 1.7 mmHg2 vs 3.4 +/- 0.5 mmHg2, P < 0.05), whereas the high dose of L-NAME not only increased the LF component (40 min: 11.7 +/- 2 mmHg2 vs 2.7 +/- 0.5 mmHg2, P < 0.001) but also decreased the mind frequency (MF: 0.2-0.6 Hz) component (60 min: 1.14 +/- 0.3 mmHg2 vs 1.7 +/- 0.1 mmHg2, P < 0.05) of SBP. 5. Losartan did not modify BP levels but had a tachycardic effect (+45 beats min-1). Moreover, losartan increased MF oscillations of SBP (4.26 +/- 0.49 mmHg2 vs 2.43 +/- 0.25 mmHg2, P < 0.001), prevented the BP rise provoked by the low-dose of L-NAME and delayed the BP rise provoked by the high-dose of L-NAME. Losartan also prevented the amplification of the LF oscillations of SBP induced by L-NAME; the decrease of the MF oscillations of SBP induced by L-NAME was reinforced after losartan. 6. We conclude that the renin-angiotensin system is involved in the increase in variability of SBP in the LF range which resulted from the withdrawal of the vasodilating influence of NO. We propose that NO may counterbalance LF oscillations provoked by the activity of the renin-angiotensin system.     

Ribosomes from Xenopus laevis eggs and embryos in a cell-free protein-synthesizing system: translational regulation

Three types of ribosomal preparations from Xenopus laevis eggs and embryos were tested in a cell-free system to study possible translational regulation of protein synthesis as mediated by the ribosome during early amphibian development: type 1, a crude high-speed sediment, mainly containing monoribosomes completely dissociable by 0.5 M KC1; type II, ribosomes washed with 0.5 M KC1; and type III, ribosomes treated with puromycin - 0.5 M KC1. All three types showed an active response to the addition of poly[U]. Type III was found to be the most active: levels of incorporation of 30 phenylalanine residues/ribosome were reached. In all three cases ribosomes prepared from unfertilized eggs were 30-40% less active in vitro than those from cleavage and gastrula stages.     

Training of medical practitioners in Nigeria (west Africa) for surgery in the rural areas

Awojobi Clinic in Eruwa, Nigeria, a hospital in a rural setting, is used as a case study. Medical practitioners hoping to practise surgery in a rural setting should be able to carry out certain essential life-saving procedures. The curricula of surgical training in medical institutions are examined to determine their relevance to performing surgery in a rural setting, and some suggestions are proffered.     

Comparison of recommended respirable mass dust sampling devices

The draft, "Revised Guide for Respirable Mass Sampling," prepared by the AIHA-ACGIH Aerosol Hazards Committee, recommends five respirable mass sampling devices that sample in accordance with the "Los Alamos" respirable dust criterion. The spectrum of recommended sampling rates for these devices ranges from 1.8 to 430. liters per minute. A study was conducted to determine if simultaneous measurements with these devices yielded comparable respirable mass concentrations. The penetration characteristics of the first stage separators were also evaluated and compared.     

Imported dengue virus infections in German tourists

Dengue viruses (DEN) are increasingly becoming endemic and epidemic in tropical and subtropical countries. In this study, 17 serologically confirmed clinical cases of DEN infection diagnosed in German tourists over the period from May 1993 until May 1994 are presented. Thirteen out of 17 (76.5%) infections occurred in southeast Asia (Thailand 58.9%), and 4/17 (23.5%) in Central and South America. All sera screened by means of the indirect immunofluorescence assay (IIFA) were positive for anti-DEN IgM. Acute infection was confirmed by demonstrating anti-DEN IgM using a "mu-capture assay". Sixteen out of 17 (94.1%) of patients presenting with fever upon admission were positive for anti-DEN IgG, with titres of > or = 128 in the IIFA. This report indicates the rising significance of DEN as a travel-associated infection in German tourists.     

Workplace smoking policies in the United States: results from a national survey of more than 100,000 workers

OBJECTIVE: To determine the prevalence of smoking policies in indoor work environments as reported by a nationally representative sample of workers in the United States. DESIGN: Cross-sectional survey of households within the United States. SETTING: All 50 state and the District of Columbia, 1992-93. PARTICIPANTS: Currently employed indoor workers 15 years of age and older who responded to the National Cancer Institute's Tobacco Use Supplement to the Current Population Survey (n = 100,561). MAIN OUTCOME MEASURES: The prevalence and restrictiveness of workplace smoking policies as reported by workers currently employed in indoor workplaces in the United States. RESULTS: Most of the indoor workers surveyed (81.6%) reported that their place of work had an official policy that addressed smoking in the workplace; 46.0% reported that their workplace policy did not permit smoking in either the public/common areas--for example, restrooms and cafeterias--or the work areas of the workplace. The reporting of these "smoke-free" policies varied significantly by gender, age, race/ethnicity, smoking status, and occupation of the worker. CONCLUSIONS: Although nearly half of all indoor workers in this survey reported that they had a smoke-free policy in their workplace, significant numbers of workers, especially those in blue-collar and service occupations, reported smoke-free rates well below the national average. If implemented, the US Occupational Safety and Health Administration's proposed regulation to require worksites to be smoke-free has the potential to increase significantly the percentage of American workers covered by these policies and to eliminate most of the disparity currently found across occupational groups.


     

Prognostic value of vasodilator myocardial perfusion imaging in patients with left bundle-branch block

BACKGROUND: The prognostic value of tomographic myocardial perfusion imaging with dipyridamole or adenosine in patients with left bundle-branch block has not been established. METHODS AND RESULTS: The study group consisted of 245 patients with left bundle-branch block who underwent tomographic (single photon emission tomography) myocardial perfusion imaging with thallium-201 (n=173) or technetium-99m sestamibi (n=72) and either dipyridamole (n=153) or adenosine (n=92) stress. Patients were prospectively classified into two groups. Patients were classified as "high risk" if they had (1) a large severe fixed defect (n=28), (2) a large reversible defect (n=36), or (3) cardiac enlargement and either increased pulmonary uptake (thallium) or a decreased resting ejection fraction (sestamibi) (n=20). The remaining 161 patients (66% of the study group) were at "low risk." Follow-up was 99% complete at 3+/-1.4 years. Three-year overall survival was 57% in the high-risk group compared with 87% in the low-risk group (P<.0001). Survival free of cardiac death/nonfatal myocardial infarction/cardiac transplantation was 55% in the high-risk group and 93% in the low-risk group (P<.0001). The presence of a high-risk scan had significant incremental prognostic value after adjustment for age, sex, diabetes, and previous myocardial infarction (P<.0001). Patients with a low-risk scan had an overall survival that was not significantly different from that of a US age-matched population (P=.86). CONCLUSIONS: Tomographic myocardial perfusion imaging with adenosine or dipyridamole stress provides important prognostic information in patients with left bundle-branch block, which is incremental to clinical assessment.     

Prospective identification of myocardial stunning using technetium-99m sestamibi-based measurements of infarct size

OBJECTIVES: We sought to prospectively identify patients with stunning and hyperkinesia at hospital discharge on the basis of mismatches between left ventricular (LV) function and infarct size as assessed by technetium-99m (Tc-99m) sestamibi perfusion tomographic imaging. BACKGROUND: Mechanical indexes of LV function may not accurately reflect myocardial damage after acute myocardial infarction (MI) because of myocardial stunning and compensatory hyperkinesia in noninfarct-related territories. Myocardial perfusion techniques are unaffected by these variables. METHODS: Eighty-four patients with acute MI underwent hospital admission and discharge Tc-99m-sestamibi tomographic imaging. Global LV ejection fraction (LVEF) was measured at hospital discharge and 6 weeks later. The perfusion defect size was quantified and expressed as a percentage of the LV. The discharge perfusion defect, which is a measure of infarct size, was used to predict the 6-week LVEF for each patient based on a previously reported regression equation. Patients were classified into one of three groups depending on whether their LVEF at hospital discharge fell within, above or below one standard error (6.8 LVEF points) of the predicted 6-week LVEF. RESULTS: There were 48 patients classified as having a "match" between function and infarct size; these patients demonstrated no significant change in LVEF at 6 weeks. There were 21 patients (25%) classified as "mismatch stunned" who had discharge LVEFs lower than those predicted by infarct size. These patients demonstrated a significant improvement in mean LVEF at 6 weeks (mean [+/-SD] discharge LVEF 0.41 +/- 0.08, 6-week LVEF 0.47 +/- 0.10; p = 0.003). Fifteen patients (18%) were classified as "mismatch-hyperkinetic." The mean LVEF for these patients significantly declined at 6 weeks (discharge LVEF 0.64 +/- 0.06, 6-week LVEF 0.58 +/- 0.09; p = 0.002). There was a marked increase in LVEF within the infarct zone (8 +/- 15 LVEF points; p = 0.03) for patients predicted to have stunning and a marked decline in LVEF outside the infarct zone (9 +/- 15 LVEF points; p = 0.06) in patients predicted to have hyperkinesia. Both discharge LVEF (p < 0.0001) and group classification (p = 0.005) were independent predictors of LVEF 6 weeks later. CONCLUSIONS: Perfusion imaging with Tc-99m-sestamibi can identify post-MI patients at hospital discharge in whom LV function is discordant with the measured infarct size. Patients with stunning have late increases in LVEF; patients with hyperkinesia have late decreases. This methodology, performed at discharge, is predictive of late changes in LV function.