Biomedical subjects
Publications and source records attributed to D Levy.
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The Hypertension and Lipid Trial (HALT) was undertaken to assess the efficacy and safety of doxazosin, a selective alpha 1- adrenergic blocker, in patients with hypertension in a clinical practice setting. The effects of doxazosin on office blood pressure, changes in lipid profiles, and theoretic coronary disease risk were studied. In an open, noncomparative, multicenter trial, 851 patients were studied for a maximum of 16 weeks. Doxazosin significantly reduced mean sitting systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 15.2/12.5 mm Hg and standing SBP and DBP by 16.1/12.7 mm Hg in the total study population (n = 807; p = 0.0001), with no significant effect on heart rate. Mean total cholesterol levels were significantly reduced by 2.7%, low-density lipoprotein cholesterol levels by 2.4%, and mean triglyceride levels by 3.4% (all p values < 0.05). High-density lipoprotein (HDL) cholesterol levels were essentially unchanged. The mean ratio of total to HDL cholesterol was significantly reduced (p < 0.05). Mean predicted 5-year coronary disease risk was significantly reduced with doxazosin therapy by 14.7% in previously untreated patients (p < 0.0001) and by 1.7% in patients who were previously receiving antihypertensive therapy (p < 0.05). The drug was well tolerated. This study demonstrates that antihypertensive therapy with doxazosin can favorably affect coronary disease risk factors and reduce predicted coronary disease risk.
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This study compares mean Doppler-derived diastolic filling indexes in a variety of disease states in a large, population-based sample. Pulse-wave Doppler was used to examine 880 eligible participants of the Framingham Heart Study. Peak velocity of early flow and late flow, ratio of early to late peak velocities, atrial filling fraction, and early filling wave acceleration and deceleration times were obtained. Multiple linear regression analyses were performed comparing mean values for individuals with hypertension, diabetes, coronary disease, cardiovascular disease, and pulmonary disease. Hypertension was associated with a greater peak velocity late flow (0.027 m/sec; 95% confidence interval, 0.006, 0.047; p = 0.011), and diabetes was associated with a larger mean deceleration time (0.12 sec, confidence interval, 0.002, 0.021; p = 0.016). In multivariate analyses, hypertension continued to show a strong association with altered Doppler diastolic filling patterns, p value 0.009, whereas in diabetes, the multivariate p value was 0.28.
Population-based data from the Framingham Heart Study have served as the basis for adjusting electrocardiographic (ECG) criteria for echocardiographically determined left ventricular hypertrophy (LVH) for two determinants of their sensitivity: body mass index and age. Estimated regression equations that predict echo-derived left ventricular mass from an ECG LVH voltage criterion, body mass index, and age, for 1,468 men and 1,883 women, provide a simple and effective means of adjusting that criterion for these variables. The authors evaluated five different ECG LVH criteria, comparing the performances of their original and adjusted versions within this database. All adjusted criteria significantly outperformed their unadjusted counterparts. Of these five criteria, the Cornell voltage duration product, (RAVL + SV3). QRS interval, exhibited the greatest sensitivity at all levels of specificity for both sexes (39 and 51% sensitivity at 95% specificity in men and women, respectively). Its performance was further evaluated with separate adjustment algorithms developed for lean versus obese and normotensive versus hypertensive men and women. Age and body mass index adjustment produced significant improvements for both lean and obese women and for obese men. A marginal gain in sensitivity was found in lean normotensive men. Within the relatively small subgroup of lean hypertensive men, no improvement was observed. These results suggest that among Caucasian adults, the Cornell voltage duration product adjusted for body mass index and age offers significant improvement for the detection of echocardiographically determined LVH in all but lean men; within the latter group, it loses no sensitivity in comparison with the original criterion.
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It has previously been reported that porous-coated root form endosseous dental implants, became well integrated when used in the traditional 2-stage surgical approach. In this study, the placement of the implant in a 1-stage (non-submerged) technique was to be explored. Implants were placed in the mandibles of dogs, and 2 designs were used differing only in that one (experimental) had a 3-mm transgingival extension, permitting it to be exposed to the oral cavity from the outset. 12 (3 per animal) non-submerged implants were placed on 1 side of 4 beagle dogs and 12 control (submerged) implants were placed contralaterally. All implants were allowed to heal for 6 weeks, after which histological preparations were made. 2 of 12 non-submerged implants were lost due to post-operative complications; otherwise, all implants healed uneventfully. Histomorphometric analysis revealed bone-implant contact, as assessed by absolute bone contact (ABC) and contact length fraction (CLF), to be greater for the submerged design, suggesting that bone healing may be delayed with the non-submerged approach. As well, at this early stage of healing, for both implant designs, ABC and CLF were significantly greater on proximal than on buccal and lingual aspects.
In this study, an assessment using modified periodontal indices was done on a group of 48 fully edentulous patients who had each been treated with 3 porous-coated (EndoPore) dental implants and a mandibular overdenture. Parameters assessed included plaque index (PI), sulcular bleeding index (SBI), pocket probing depth (PD), probing attachment level (PAL) and mobility (M) using a Periotest device. At the time of the assessment, all of the patients had passed 3 years of continuous function while 26 had passed 4 years. Approximately 50% of implant surfaces were plaque-free while 79% of surfaces showed no bleeding upon probing. There was no correlation between PI and SBI. The mean PD was 3.1 mm with 64% of sites < or = 3.5 mm. Mobility measurements taken with the Periotest device gave a mean PTV of (-4.35) with 96% of measurements (-0.5). No significant correlations were found between mobility and either PAL or implant length.
Panic attacks are subjectively reported by patients as a cluster of autonomic nervous symptoms. Taken together with the evidence from pharmacological studies focusing on the locus ceruleus and the dorsal raphe nuclei, the hypothesis of brainstem involvement in panic attacks is of major interest. Functional evaluation of the brainstem is carried out using electrophysiological recordings, such as the brainstem evoked potentials. We have investigated the pathophysiology of these parameters in 16 patients fulfilling the DSM III-R criteria for panic disorder (8 females and 8 males) in comparison to a group of 10 normal controls. The patients were found to have two electrophysiological variables significantly different from controls: (a) N3 latency tme was reduced (p < 0.05) and (b) the N3-5 interval was prolonged (p < 0.05). The N3 latency period significantly correlated with the Hamilton Anxiety Scale scores (p < 0.005). N3 is a peak reflecting pontine activation, where the locus ceruleus is located. The N3-5 interval reflects evoked potential passage from the pons to the midbrain. In conclusion, our results support previous studies indicating a dysfunction of the locus ceruleus possibly causing disruption of pons-midbrain transmission in patients suffering from panic disorder.
Since it was established that middle ear (ME) gas composition is closer to venous gas composition than to air, the question arose regarding the composition of gas which enters the ME from the nasopharynx. Using a mass spectrometer, gaseous partial pressure was measured at three locations in the nose and nasopharynx of 6 volunteers. All three locations showed similar gas composition (O2 = 15.7%, CO2 = 4.5%, N2 + Ar = 79.8%) which is similar to expired air. The gas that enters the ME via the Eustachian tube is a mixture closer to the final ME gas equilibrium than is air. This minimizes the changes in steady state ME gas composition incurred by gas influx into the ME.
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We describe a technique to bypass a defective part of an oxygenator unit (venous reservoir or oxygenator part) by connecting a second oxygenator instead of replacing the whole oxygenator unit. If only the oxygenator part has to be replaced, further hemodilution can be avoided. This technique can be performed in very short time and is probably associated with less air embolism.
Postmenarcheal adolescent girls performed resistance training (RT) for 26 weeks, which consisted of 4 sets of 13 exercises of varying and progressive intensity performed 3 times weekly on hydraulic resistance machines. Bone mineral was assessed by dual photon absorptiometry. Resistance training resulted in significant increases (pre-post) in biceps curl (21.4%), triceps press (21.5%), knee extension (25.1%), knee flexion (52.8%), and squat press (21.5%) strength. There were no significant differences between RT and control (C) groups initially, and no significant effects of training (pre-post) for total body (TB) or lumbar spine (LS) bone mineral content (BMC) or bone mineral density (BMD). The largest increases in LS bone mineral occurred during the first 13 weeks, and although not significant, the increases in LS BMC (g) (3.9 vs. 5.9%), LS BMC (g.cm-1) (2.6 vs. 5.9%), LS areal BMD (g.cm-2) (1.48 vs. 4.75%), and LS bone mineral apparent density (BMAD, g.cm-3) (0.47 vs. 4.13%) were greater in the RT compared with the C group during this period. In conclusion, resistance training resulted in a trend towards a transient increase in LS bone mineral during the first 13 weeks, but despite significant strength gains, there were no significant changes in TB or LS bone mineral after 26 weeks of training.
Membrane protein folding patterns can be divided into several classes based on their orientation and the topogenic sequences that regulate their insertion into the ER membrane. The orientation of membrane proteins is regulated by charge distribution in the polypeptide chain as well folding characteristics of the N-terminal domain. Protein targeting characteristic are determined by several sequence motifs found in the C- and N-terminal domains as well as by oligomerization. Several proteins, such as Pgp, ductin, CP450s and mEH, have been shown to exhibit more than one topological orientation in the ER which can result in protein targeting to more than one cell compartment as well as the expression of multiple biological functions.
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Fusafungine is a peptide antibiotic mixture composed of several enniatins and active against Gram-positive bacteria. Ionophoric properties of fusafungine have been studied in liposomes by measuring protoncation exchange by both fluorescence and 31P-nuclear magnetic resonance (NMR) and have been compared to those of its constituent enniatin peptides. Fusafungine, as well as enniatins, transport cations through a mobile carrier mechanism selective for K+ vs. Na+ and involving two antibiotic molecules. The transport efficiencies of the various enniatins appear to be related to their hydrophobicity, in agreement with a previously proposed "sandwich" transport model. The ionophoric properties of crude fusafungine may be involved in its antibiotic action and its local therapeutic properties.
Electrocardiographic left ventricular (LV) hypertrophy has long been known to be associated with an abnormal ST-segment response to exercise; this association has been considered to represent a false-positive finding. There is a paucity of data relating echocardiographic LV mass to exercise ST-segment responses and other exercise parameters. As part of a routine evaluation, 1,408 men and 1,618 women from the Framingham Heart Study who were free of clinical cardiac disease underwent echocardiography and exercise treadmill testing according to the Bruce protocol at the same clinic visit. Abnormal ST-segment responses were defined both by standard criteria and the delta ST/heart rate index. LV mass was calculated from M-mode echocardiography. Echocardiographic LV hypertrophy was associated with an abnormal delta ST/heart rate index (in men, odds ratio [OR] 1.78, 95% confidence interval [CI] 1.05 to 3.01, p = 0.03; in women, OR 2.13, 95% CI 1.31 to 3.44, p = 0.002) but not with an abnormal response according to standard criteria. Echocardiographic LV hypertrophy was also associated with a lower likelihood of achieving an age-predicted target heart rate (in men, OR 0.45, 95% CI 0.31 to 0.65, p < 0.001; in women, OR 0.53, 95% CI 0.37 to 0.76, p < 0.001) and with a lower exercise capacity. Despite these associations, echocardiographic LV hypertrophy was associated with a higher peak heart rate-systolic blood pressure double product. In conclusion, echocardiographic LV hypertrophy is associated with an abnormal ST-segment response, a lower likelihood of achieving target heart rate, decreased exercise capacity, and an increased double product, which is a reflection of myocardial oxygen demand.
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