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B Lewis

Publications and source records attributed to B Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1995

Quantitative coronary cineangiography for the study of atherosclerosis.

Angiography is the definitive procedure for characterising the extent and course of coronary artery disease. We describe the methodology required to measure, with optimal resolving power, angiographic changes in coronary artery disease. We utilised recent technological developments in image digitization, storage and analysis. The measures of change quantified both diffuse and focal atherosclerosis. Frames from angiographic cine films were digitized at high resolution (1024 x 1024 pixels, 8 bit grey scale) and archived on optical disk. Four radiographic projections were stored to ensure good visualization of as many as possible of a set of ten major arterial segments. Edges of segments and catheter were automatically delineated by computer using a dynamic programming algorithm involving a cost function which contained terms based on edge strength and on continuity. For every digitized radiographic projection, delineation was repeated in three adjacent frames, to improve precision. Edge points for each coronary segment were stored on disk. From these we computed the mean width along the segment (pixels). Scaling to obtain the Mean Absolute Width of the Segment (MAWS, mm) was achieved using catheter dimensions known from micrometry, systematic error due to imaging system line-spread function being corrected using data from computer simulations and phantom studies. Correction for geometric image intensifier distortion was also applied. We used the methodology in a randomized, controlled trial of the effect of lipid-lowering therapy, the St Thomas' Atherosclerosis Regression Study. The fundamental measure of change of disease in each segment was the change in MAWS (delta MAWS). Using in-vitro and in-vivo studies we established that the overall resolving power for one segment delta MAWS was 0.10 mm at 2 mm width and 0.14 mm at 4 mm width. Subsidiary end-points were the change (delta) in minimum absolute width of segment (MinAWS), edge irregularity index (EII) and percent diameter stenosis (%DS). Delta%DS (the conventional angiographic measure of coronary disease) was significantly correlated with change in all indices, closest correlation being seen with delta EII (r = 0.94, p < 0.001).

Arteriosclerosis↗
PubMed1995

Electrogenic sodium absorption and chloride secretion by an inner medullary collecting duct cell line (mIMCD-K2).

The initial segment of the inner medullary collecting duct (IMCDi) absorbs Na+ by an electrogenic mechanism and plays an important role in regulating the composition and volume of the urine. The purpose of the present study was to establish a permanent cell line derived from the IMCDi, which has the ion transport properties of the IMCDi in vivo. To this end, we isolated IMCD cells from the IMCDi of a mouse, Tg(SV40E) Bri 7, transgenic for the early region of SV40 (large T antigen) and established a permanent cell line, mIMCD-K2, by clonal dilution. mIMCD-K2 cells retain many differentiated characteristics of the IMCDi, including amiloride-sensitive electrogenic Na+ absorption stimulated by nanomolar concentrations of aldosterone. Aldosterone (1.5 x 10(-6) M) increased Na+ absorption from 0.2 +/- 0.1 to 4.6 +/- 1.7 microA/cm2. In addition, the cells secrete Cl- by an electrogenic mechanism at a rate of 0.5 +/- 0.1 microA/cm2. We propose that IMCDi cells either absorb or secrete NaCl depending on NaCl homeostasis. The mIMCD-K2 cell line should be useful for studying the cellular mechanisms responsible for electrogenic Na+ and Cl- transport in the IMCDi.

Absorption↗
PubMed1995

Vasopressin and cAMP stimulate electrogenic chloride secretion in an IMCD cell line.

Previously, we demonstrated that the mIMCD-K2 cell line, derived from the inner medullary collecting duct (IMCD) of a transgenic mouse, secretes Cl- by an electrogenic mechanism [N. L. Kizer, B. Lewis, and B. A. Stanton, Am. J. Physiol. 268 (Renal Fluid Electrolyte Physiol. 37): F347-F355, 1995]. The objective of the present study was to characterize the cellular mechanisms of electrogenic Cl- secretion (IscCl) and to determine whether arginine vasopressin (AVP) and adenosine 3',5'-cyclic monophosphate (cAMP) stimulate IscCl. To this end, we measured IscCl across monolayers of mIMCD-K2 cells mounted in Ussing-type chambers. AVP increased IscCl with a Michaelis constant (Km) of 2.1 +/- 0.7 x 10(-12) M. 1-Desamino-8-D-AVP, a specific V2 receptor agonist, increased IscCl from 3.3 +/- 0.4 to 17.4 +/- 1.3 microA/cm2, 8-(4-Chlorophenylthio)-cAMP, a cell-permanent analogue of cAMP, a second messenger of AVP, increased IscCl from 1.4 +/- 0.3 to 15.2 +/- 1.2 microA/cm2. Furosemide and bumetanide, inhibitors of Na(+)-2Cl(-)-K+ cotransport, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an inhibitor of Cl-/HCO3- exchange, reduced IscCl when added to the basolateral solution. Our data suggest that AVP, via V2 receptors, and the second messenger cAMP stimulate IscCl and that Cl- secretion by mIMCD-K2 cells involves uptake of Cl- across the basolateral membrane by Na(+)-2Cl(-)-K+ cotransport and Cl-/HCO3- exchange and diffusion out of the cells across the apical membrane by cystic fibrosis transmembrane conductance regulator Cl- channels.

Absorption↗
PubMed1995

Selective retention of VLDL, IDL, and LDL in the arterial intima of genetically hyperlipidemic rabbits in vivo. Molecular size as a determinant of fractional loss from the intima-inner media.

To explore possible mechanisms whereby the triglyceride-rich lipoproteins IDL and VLDL may promote atherosclerosis, fractional loss of these lipoproteins from the intima-inner media was measured in vivo in genetically hyperlipidemic rabbits of the St Thomas's Hospital strain and compared with the fractional loss of LDL, HDL, and albumin. These rabbits exhibit elevated plasma levels of VLDL, IDL, and LDL. In each rabbit, two aliquots of the same macromolecule, one iodinated with 125I and the other with 131I, respectively, were injected intravenously on average 24 and 3 hours, respectively, before removal of the aortic intima-inner media. The fractional loss from the intima-inner media of newly entered macromolecules was then calculated. The average fractional losses for VLDL, IDL, LDL, HDL, and albumin in lesioned aortic arches were 0.1%/h (n = 4), -0.2%/h (n = 3), 1.8%/h (n = 4), 11.4%/h (n = 3), and 26.3%/h (n = 1), respectively; in nonlesioned aortic arches fractional losses for IDL, LDL, HDL, and albumin were 1.7%/h (n = 1), 0.6%/h (n = 2), 14.6%/h (n = 3), and 25.9%/h (n = 3). In both lesioned and nonlesioned aortic arches, the logarithms of these fractional loss values were inversely and linearly dependent on the diameter of the macromolecules (R2 = .57, P = .001 and R2 = .84, P < .001), as determined from electron photomicrographs of negatively stained lipoproteins. These results suggest that after uptake into the arterial intima, VLDL and IDL as well as LDL are selectively retained in comparison with HDL and albumin.

Albumins↗
PubMed1995

Family accommodation in obsessive-compulsive disorder.

OBJECTIVE: Family accommodation of patients with obsessive-compulsive disorder, i.e., participation in symptoms and modification of personal and family routines, was assessed in relation to family stress, functioning, and attitudes toward the patient. METHOD: Primary caretakers for 34 patients with obsessive-compulsive disorder were interviewed to assess the nature and frequency of accommodating behaviors. The caretakers also completed several measures of family functioning. RESULTS: Of the 34 spouses or parents, 30 (88.2%) reported accommodating the patient. Family accommodation correlated with poor family functioning, rejecting attitudes toward the patient, and several types of family stress. CONCLUSIONS: Family accommodation of patients with obsessive-compulsive disorder was associated with global family dysfunction and stress. This study suggests that families' efforts to accommodate patients may be intended to reduce patient anxiety or anger directed at relatives.

Adult↗
PubMed1995

Psychotherapeutic discourse analysis.

Psychotherapeutic discourse analysis is a significant, largely unexplored, tool for psychotherapist and an ideal data sight for linguists. Increased multidisciplinary research in this area would be particularly fruitful. Conversations, including therapeutic conversations, are far from transparent conduits of information from one person to another. Complicating surface communication is "metacommunication," which takes the form of unconscious conversational styles--culturally influenced rules, norms, and expectations of how a conversation should proceed. If the therapist and the patient are working with different conversational styles, then blocks in communication and understanding are inevitable. Through discourse analysis conversational styles can become more available to awareness for use in the service of therapeutic goals. This paper is an example of a discourse analysis of an individual therapy session. I attempt to bridge the gap between broad psychodynamic treatment strategies and minute micro-conversational strategies that can be used to enhance the therapeutic process.

Adult↗
PubMed1995

The effectiveness of alternative planned durations of residential drug abuse treatment.

Randomized controlled trials were conducted at two residential drug abuse treatment facilities to compare programs that differed in planned duration. One trial compared a 6-month and a 12-month therapeutic community program (n = 184), and the second compared a 3-month and a 6-month relapse prevention program (n = 444). Retention rates over comparable time periods differed minimally by planned treatment duration, and the longer programs had lower completion rates. There was no effect in either trial of planned treatment duration on changes in psychosocial variables between admission and exit or on rates or patterns of drug use at follow-up between 2 and 6 months after exit.

Follow-Up Studies↗
PubMed1995

Dynamic muscle strength as a predictor of bone mineral density in elderly women.

Although muscle strength has been shown to predict bone mineral density (BMD) in older adults, the variance explained by isometric and isokinetic testing has been generally low (< 20%) and limited to only a few exercises and muscle groups. To elucidate the relationship of muscle strength to BMD at multiple sites, and to ascertain the most robust predictor of BMD using isotonic strength testing apparatus, we examined dynamic muscle strength and BMD in 40 healthy elderly women aged 65-82 years. BMD of the spine (L2-4), proximal femur (neck, trochanter, Ward's triangle), forearm (midradius), and whole body were measured by dual-energy X-ray absorptiometry. Dynamic strength (1-RM), utilizing isotonic weight-lifting equipment, was assessed for 10 standard upper and lower body exercises. In stepwise multiple regressions, leg press was the only independent predictor of spine (R2 = 0.11), neck and trochanter (R2 = 0.21 and 0.18), forearm (R2 = 0.21), and whole body BMD (R2 = 0.19), while bench press was an independent predictor of Ward's BMD (R2 = 0.12). The most robust predictor of regional and whole body BMD using isotonic equipment was the leg press, which may reflect overall skeletal health in this population. The portion of variance explained by dynamic muscle strength (11-21%) is similar to that reported when strength is assessed by isometric and isokinetic testing. The relationship of dynamic strength to BMD was not generally site-specific.

Absorptiometry, Photon↗
PubMed1995

Relationships between nutrient intake and progression/regression of coronary atherosclerosis as assessed by serial quantitative angiography.

To elucidate the direction and magnitude of effects of nutrition on coronary artery disease (CAD), the relation between nutrient intake and angiographic changes were examined in the course of a controlled dietary trial. Ninety men with symptomatic CAD and serum cholesterol greater than 232 mg/dL were entered into a randomized controlled trial of a lipid-lowering diet, or of diet plus cholestyramine, compared with usual cardiac care. Of those in the first and second groups, 50 patients completed the trial and are the subject of this report. Quantitative coronary angiography was performed at baseline and at 39 months. From repeated dietary assessment during the trial, mean nutrient intakes were computed, and their relationships with change of coronary artery narrowing were analyzed. Progression of coronary disease was directly, strongly and independently associated with intake of saturated fatty acids of chain length 14-18. This was not fully explained by the effects of saturated fat in raising serum cholesterol; after adjustment for low density lipoprotein cholesterol level, stearic acid (C18:0) intake remained independently predictive of progression. No 'protective' effect of linoleic, linolenic or eicosapentaenoic acid was demonstrable. Intake of trans fatty acids was directly related to progression. Together with the favourable treatment effects on angiographic appearance and clinical end-points, these findings provide further support for a causal role of saturated fats in CAD; restriction of foods containing such fats should be emphasized as part of regimens aimed to reduce progression of coronary atherosclerosis.

Adult↗
PubMed1995

Hiring and selection: the Australian experience.

The Australian health care system has forced fundamental changes in expectations of leaders and management competencies required to thrive in a cost-constrained environment. By learning from the Australian experience, US managers can incorporate new ideas into reshaping our future leaders.

Australia↗
PubMed1995

Successful treatment of heparin-associated thrombocytopenia and thrombosis using Hirulog.

Heparin-associated thrombocytopenia is a serious medical problem, especially when the patient requires continued anticoagulation. Hirulog is an immediate-acting intravenous anticoagulant that can be substituted for heparin. A new use of Hirulog in the treatment of life-threatening heparin-associated thrombocytopenia with thrombosis (HATT) is presented. Two patients suffering from the HATT syndrome were successfully treated with Hirulog to prevent further thrombosis. A third patient had developed heparin-associated thrombocytopenia after coronary artery bypass surgery in the past and was subsequently treated with Hirulog during a peripheral angioplasty procedure. Hirulog was an effective and predictable anticoagulant for these patients and was free from adverse effects.

Aged↗
PubMed1994

A coordinated, communitywide program in Monroe County, New York, to increase influenza immunization rates in the elderly.

BACKGROUND: Despite the efficacy of influenza vaccination in preventing complications of influenza, rates of immunization among high-risk populations remain low. The Monroe County (New York) Influenza Vaccination Demonstration was a communitywide, collaborative effort to increase the rates of influenza immunization to greater than 60% in elderly Medicare recipients. METHODS: The local health department, university medical center, and practicing physicians collaborated to develop a communitywide demonstration directed to all Medicare part B enrollees 65 years of age or older, multiple coordinated approaches were used over a 4-year period (1988 to 1992). Most providers, including public agencies, private providers, hospital outpatient facilities, nursing homes, and insurance providers, were enrolled in a comprehensive program that included centralized claims processing, vaccine distribution and promotion, and extensive provider and public education efforts, including a special urban outreach program. An office-based, denominator-driven physician incentive project was also evaluated. RESULTS: The demonstration project resulted in a 1991 influenza immunization rate of 74.3% among 88,811 Medicare enrollees 65 years of age or older. The increase in immunization rate occurred primarily among the patients of private physicians. CONCLUSION: A communitywide, collaborative approach can succeed in achieving high rates of influenza immunization.

Aged↗
PubMed1994

Nutrient intake and progression of coronary artery disease.

The relation between nutrient intake and progression of coronary artery disease was examined in 50 men receiving a lipid-lowering diet or usual care in the St. Thomas' Atherosclerosis Regression Study. Nutrient intake was assessed by diet history. Changes in coronary angiograms were measured by quantitative image analysis. In univariate linear regression analysis progression of disease over 39 months, as measured by decrease in minimum absolute width of coronary segments, was directly related to dietary energy (p < 0.001) and to the absolute intakes of total fat (p < 0.001), saturated fat (p < 0.001), monounsaturated fat (p = 0.016) and cholesterol (p = 0.06). No significant associations were seen with polyunsaturated fat, carbohydrate, protein, fiber, alcohol or with the ratio of intakes of polyunsaturated fatty acids to saturated fatty acids. In multiple linear regression analysis the associations of change in minimum absolute width of coronary segments with total or saturated fat persisted when adjusted for plasma low-density lipoprotein cholesterol concentration, age, weight, blood pressure, smoking or treatment group assignment. The findings suggest that in middle-aged men, progression of CAD is strongly influenced by intake of saturated fatty acids, an effect mediated in part by mechanisms other than the influence of this nutrient on plasma cholesterol and low-density lipoprotein cholesterol.

Basal Metabolism↗
PubMed1994

Treponematosis and Lyme borreliosis connections: explanation for Tchefuncte disease syndromes?

A convergence of evidence from macroscopic, radiographic and histologic examination indicates that treponemal infection was present in the 16ST1 Tchefuncte Indian burial population, dated 500 B.C. to 300 A.D. Pattern and nature of lesions suggests that chronic infection induced by variants of the spirochete Treponema pallidum, causing endemic syphilis and/or yaws, resulted in third-stage osseous response. It is suggested that Tchefuncte Indians acquired partial immunity to treponemal infection by exposure to a variant of the related spirochete, Borrelia burgdorferi, the causative agent of Lyme disease. Partial immunity would help explain the relatively mild expression of the treponemal disease process in the 16ST1 skeletal population and the apparent absence of venereal syphilis. Presence of the Borrelia burgdorferi spirochete might be linked to a single incidence of juvenile rheumatoid arthritis.

Arthritis, Juvenile↗
PubMed1994

Ergot induced peripheral vascular insufficiency, non-interventional treatment.

We report a case of ergotamine tartrate induced severe vasospasm in the renal arteries and the arteries of the lower extremities. Classic features seen on peripheral angiography make the diagnosis. Anticoagulation, thrombolysis, vasodilation, steroids, and prostaglandin inhibitors all have been successfully used to treat symptomatic ergot induced arterial vasospasm. Although balloon angioplasty of ergot induced vasospasm has been described in case reports, ergot vasospasm is a self limited and medically treatable condition that does not require peripheral mechanical intervention, unless the immediate threat of necrosis and gangrene exists.

Adult↗
PubMed1994

Recovery of neuromuscular function after atracurium and pancuronium maintenance of pancuronium block.

The study was undertaken to determine whether a neuromuscular blockade induced with pancuronium but maintained with atracurium was associated with a shorter time to complete recovery after administration of neostigmine than if the blockade was maintained with pancuronium alone. Anaesthesia consisted of thiopentone, N2O/O2/enflurane and fentanyl, and the neuromuscular blockade, induced by pancuronium 0.1 mg.kg-1 was monitored by the force of contraction of adductor pollicis during major abdominal surgery lasting 2-5 hr. In 24 patients--Group 1--atracurium 0.07 mg.kg-1 was repeated when the first twitch of the train-of-four (TOF) returned to 25% of control (T1/TC 25). In 28 patients--Group 2--pancuronium 0.015 mg.kg-1 was given at similar recovery of T1/TC. At the end of surgery, neostigmine 0.07 mg.kg-1 and glycopyrolate 0.015 mg.kg-1 were given to reverse the residual neuromuscular blockade which was indicated by a T1/TC of less than 25% in all patients. The time from injection of the reversal drugs to a TOF ratio of 70% was similar in both groups (Group 1, 11.6 +/- 7.6 min; Group 2, 10.1 +/- 6 min; P = NS), but the recovery index was smaller in Group 2 (Group 1, 4 +/- 2.6 min; Group 2, 2.61 +/- 1.2 min; P < 0.05). Furthermore, there was no difference between groups in the duration of action of each redose. The study showed that when compared with pancuronium, equipotent doses of atracurium were not associated with (a) a shorter time to complete recovery from a neuromuscular blockade induced with pancuronium or (b) a shorter duration of action.

Adult↗