Biomedical subjects

G J Beck

Publications and source records attributed to G J Beck.

At least 19 recordsLinked to original sources

PubMed1995

Progression of overt nephropathy in non-insulin-dependent diabetes.

The detection of overt albuminuria (> 300 mg/g creatinine) in the absence of azotemia was used to diagnose early nephropathy in 34 Pima Indians with NIDDM of 16 +/- 1 years duration. Differential solute clearances were performed serially to define the course of the glomerular injury over 48 months. At baseline, the GFR (107 +/- 5 ml/min), filtration fraction and sieving coefficients of relatively permeant dextrans (< 52 A) were all depressed below corresponding values in 20 normoalbuminuric Pima Indians with a similar duration of NIDDM. Over the ensuing 48 months the GFR (-34%) and filtration fraction (-13%) in the nephropathic patients declined further. The sieving coefficients of large, nearly impermeant dextrans (> 56 A radius) increased selectively and fractional clearances of albumin and IgG increased correspondingly by > 10-fold. Analysis of the findings with pore theory revealed: (1) a progressive decline in pore density and the ultrafiltration coefficient (Kf); and (2) broadening of glomerular pore-size distribution that resulted in greater prominence of large pores (> 70 A radius). We conclude that increasing loss of intrinsic ultrafiltration capacity is the predominant cause of the early and progressive decline in GFR that follows the development of nephropathy in NIDDM. We speculate that progressive impairment of barrier size-selectivity contributes to but does not fully account for the increasingly heavy proteinuria that is observed early in the course of this disorder.

Adolescent↗

PubMed1995

Dietary protein restriction, blood pressure control, and the progression of polycystic kidney disease. Modification of Diet in Renal Disease Study Group.

In the Modification of Diet in Renal Disease Study, a follow-up (mean, 2.2 yr) of 200 study participants with autosomal dominant polycystic kidney disease (ADPKD) was conducted to determine the effect of lowering protein intake and blood pressure on the rate of decline in GFR. The rate of decline was faster in participants with ADPKD than in persons with other diagnoses, reflecting, in part, faster disease progression in the ADPKD group. Baseline characteristics that predicted a faster rate of decline in GFR in persons with ADPKD were greater serum creatinine (independent of GFR), greater urinary protein excretion, higher mean arterial pressure (MAP), and younger age. In patients with initial GFR values between 25 and 55 mL/min per 1.73 m2, neither assignment to a low-protein diet group nor assignment to a low blood pressure group significantly reduced the rate of decline of GFR in ADPKD participants. Similarly, the decline in GFR was not related to achieved protein intake or MAP. In participants with GFR values between 13 and 24 mL/min per 1.73 m2, assignment to the low MAP group led to a somewhat more rapid decline in GFR. However, the more rapid decline in GFR did not appear to be due to a detrimental effect of low blood pressure or the antihypertensive agents used to reach the low blood pressure goal. Lower protein intake, but not prescription of the keto acid-amino acid supplement, was marginally associated with a slower progression of renal disease.

Adult↗

PubMed1995

Endoscopic retrograde cholangiopancreatography in pregnancy.

BACKGROUND: Pancreaticobiliary disease in pregnancy is relatively uncommon. The frequency of choledocholithiasis in pregnancy requiring intervention has been reported to be as low as one in 1200 deliveries. Traditionally, intervention in these patients has been surgical. Although surgery has an overall low morbidity and mortality for the expectant mother, it carries with it a 4- to 6-wk recovery period and a possibly increased risk of fetal wastage. Published information regarding the role and safety of ERCP in pregnancy is limited. This series of 23 pregnant patients undergoing ERCP was collected from six different medical centers. METHODS: Twenty-three pregnant patients with symptomatic pancreaticobiliary disease underwent a total of 29 ERCPs (three patients had diagnostic ERCP, and 20 had therapeutic ERCP). Fifteen, eight, and six procedures were performed in the first, second, and third trimesters, respectively. The only ERCP complication was pancreatitis in one patient. There was one spontaneous abortion (3 months after ERCP) and one neonatal death; however, casual relationship to ERCP was not apparent. CONCLUSION: Diagnostic and therapeutic ERCP appears reasonably safe and effective in pregnancy. Cautious and selective use of this procedure offers a viable alternative to surgery or observation in patients with emergent pancreaticobiliary problems.

Adult↗

PubMed1994

A clinical trial of antioxidant vitamins to prevent colorectal adenoma. Polyp Prevention Study Group.

BACKGROUND: People who consume a diet high in vegetables and fruits have a lower risk of cancer of the large bowel. Antioxidant vitamins, which are present in vegetables and fruits, have been associated with a diminished risk of cancers at various anatomical sites. We conducted a randomized, controlled clinical trial to test the efficacy of beta carotene and vitamins C and E in preventing colorectal adenoma, a precursor of invasive cancer. METHODS: We randomly assigned 864 patients, using a two-by-two factorial design, to four treatment groups, which received placebo; beta carotene (25 mg daily); vitamin C (1 g daily) and vitamin E (400 mg daily); or the beta carotene plus vitamins C and E. In order to identify new adenomas, we performed complete colonoscopic examinations in the patients one year and four years after they entered the study. The primary end points for analyses were new adenomas identified after the first of these two follow-up examinations. RESULTS: Patients adhered well to the prescribed regimen, and 751 completed the four-year clinical trial. There was no evidence that either beta carotene or vitamins C and E reduced the incidence of adenomas; the relative risk for beta carotene was 1.01 (95 percent confidence interval, 0.85 to 1.20); for vitamins C and E, it was 1.08 (95 percent confidence interval, 0.91 to 1.29). Neither treatment appeared to be effective in any subgroup of patients or in the prevention of any subtype of polyp defined by size or location. CONCLUSIONS: The lack of efficacy of these vitamins argues against the use of supplemental beta carotene and vitamins C and E to prevent colorectal cancer. Although our data do not prove definitively that these antioxidants have no anticancer effect, other dietary factors may make more important contributions to the reduction in the risk of cancer associated with a diet high in vegetables and fruits.

Adenomatous Polyps↗

PubMed1994

The effects of dietary protein restriction and blood-pressure control on the progression of chronic renal disease. Modification of Diet in Renal Disease Study Group.

BACKGROUND: Restricting protein intake and controlling hypertension delay the progression of renal disease in animals. We tested these interventions in 840 patients with various chronic renal diseases. METHODS: In study 1, 585 patients with glomerular filtration rates of 25 to 55 ml per minute per 1.73 m2 of body-surface area were randomly assigned to a usual-protein diet or a low-protein diet (1.3 or 0.58 g of protein per kilogram of body weight per day) and to a usual- or a low-blood-pressure group (mean arterial pressure, 107 or 92 mm Hg). In study 2, 255 patients with glomerular filtration rates of 13 to 24 ml per minute per 1.73 m2 were randomly assigned to the low-protein diet (0.58 g per kilogram per day) or a very-low-protein diet (0.28 g per kilogram per day) with a keto acid-amino acid supplement, and a usual- or a low-blood-pressure group (same values as those in study 1). An 18-to-45-month follow-up was planned, with monthly evaluations of the patients. RESULTS: The mean follow-up was 2.2 years. In study 1, the projected mean decline in the glomerular filtration rate at three years did not differ significantly between the diet groups or between the blood-pressure groups. As compared with the usual-protein group and the usual-blood-pressure group, the low-protein group and the low-blood-pressure group had a more rapid decline in the glomerular filtration rate during the first four months after randomization and a slower decline thereafter. In study 2, the very-low-protein group had a marginally slower decline in the glomerular filtration rate than did the low-protein group (P = 0.07). There was no delay in the time to the occurrence of end-stage renal disease or death. In both studies, patients in the low-blood-pressure group who had more pronounced proteinuria at base line had a significantly slower rate of decline in the glomerular filtration rate. CONCLUSIONS: Among patients with moderate renal insufficiency, the slower decline in renal function that started four months after the introduction of a low-protein diet suggests a small benefit of this dietary intervention. Among patients with more severe renal insufficiency, a very-low-protein diet, as compared with a low-protein diet, did not significantly slow the progression of renal disease.

Blood Pressure↗

PubMed1992

Stratification of morbidity and mortality outcome by preoperative risk factors in coronary artery bypass patients. A clinical severity score.

OBJECTIVE: To relate morbidity and mortality risk to preoperative severity of illness in patients undergoing coronary artery bypass grafting. DESIGN: Retrospective analysis of 5051 patients using univariate and logistic regression to identify risk factors associated with perioperative morbidity and mortality. Prospective application of models to a subsequent 2-year validation cohort (n = 4069). SETTING: Cleveland Clinic Foundation. PATIENTS: All adult patients undergoing coronary artery bypass graft surgery between July 1, 1986, and June 30, 1988 (reference group), and July 1, 1988, and June 30, 1990 (validation group). MAIN OUTCOME MEASURES: Mortality and morbidity (myocardial infarction and use of intra-aortic balloon pump, mechanical ventilation for 3 or more days, neurological deficit, oliguric or anuric renal failure, or serious infection). MAIN RESULTS: Emergency procedure, preoperative serum creatinine levels of greater than 168 mumol/L, severe left ventricular dysfunction, preoperative hematocrit of 0.34, increasing age, chronic pulmonary disease, prior vascular surgery, reoperation, and mitral valve insufficiency were found to be predictive of mortality. In addition to these factors, diabetes mellitus, body weight of 65 kg or less [corrected], aortic stenosis, and cerebrovascular disease were predictive of morbidity. Logistic regression equations were developed, and a simple additive score for clinical use was designed by allocating each of these risk-factor values of 1 to 6 points. Both methods predict mortality. Increased morbidity was demonstrated with increases in score. CONCLUSIONS: The logistic or clinical models developed are superior to the currently available methods for comparing mortality outcome and provide previously unavailable information on morbidity based on preoperative status. The clinical scoring system is useful for preoperative estimates of morbidity and mortality risks.

Aged↗

PubMed1991

Etiology of motor or sensory stroke: a prospective study of the predictive value of clinical and radiological features.

The diagnostic utility of clinical and radiological features for distinguishing penetrating artery disease from other causes of stroke has been questioned. To address this issue, we prospectively evaluated more than 40 features in 85 patients with pure motor, sensorimotor, or pure sensory syndromes. Nonischemic causes were present in 4 patients. The causes of ischemic stroke in the other 81 patients were penetrating artery disease (32 patients), large artery occlusive disease (17), cardioembolism (12), other causes (8), and undetermined (12). Of the features evaluated, frequent transient ischemic attacks (greater than or equal to 1/day), transient ischemic attacks occurring only within 1 week of stroke, pure motor hemiparesis (similar involvement of face, arm, and leg), pure sensory stroke, and round or oval infarction were associated (p less than 0.05) with penetrating artery disease. However, only pure sensory stroke involving two or more regions of the body and pure motor hemiparesis associated with subcortical infarction of less than 1.5 cm had positive predictive values exceeding 90% for penetrating artery disease. Carotid bruit ipsilateral to an anterior circulation infarction, monoparesis, and striatocapsular infarction had positive predictive values exceeding 90% for causes other than penetrating artery disease; however, half of the striatocapsular infarctions were of undetermined cause. These data suggest that certain clinical and radiological features are useful for distinguishing penetrating artery disease from other causes of stroke.

Aged↗

PubMed1991

Design and statistical issues of the Modification of Diet in Renal Disease Trial. The Modification of Diet in Renal Disease Study Group.

The Modification of Diet in Renal Disease Trial is a multicenter randomized clinical trial for men and women aged 18-70 years with chronic renal disease who are not on dialysis and who have not had a kidney transplant. Study participants are randomized in a 2 x 2 factorial design to diets containing different amounts of protein and phosphorus and to two levels of blood pressure control. The prescribed modifications differ depending on the level of a patient's kidney function. The primary outcome variable to compare diet or blood pressure groups is each patient's slope (or the change) in glomerular filtration rate with time. This paper describes the study design with particular emphasis on sample size determination. Special statistical analysis issues that arise with slope as the outcome are also discussed.

Adolescent↗

PubMed1990

A simple, sensitive assay for the spermicide nonoxynol-9 in biological fluids by high-performance liquid chromatography.

A new high-performance liquid chromatographic technique has been developed to quantitate nonoxynol-9 in serum, urine, and vaginal fluid. The method is rapid, involves minimal sample preparation, and can be used to analyze a large number of biological fluid samples. The assay elutes a single nonoxynol-9 peak with no interfering components. This was accomplished using a 10-microns pelicular packed amine column, a normal-phase solvent system, and fluorescence detection. Nonoxynol-9 levels as low as 0.23 micrograms/mL in urine can be detected.

Body Fluids↗

PubMed1990

Utility of radioisotopic filtration markers in chronic renal insufficiency: simultaneous comparison of 125I-iothalamate, 169Yb-DTPA, 99mTc-DTPA, and inulin. The Modification of Diet in Renal Disease Study.

Assessment of glomerular filtration rate (GFR) with inulin is cumbersome and time-consuming. Radioisotopic filtration markers have been studied as filtration markers because they can be used without continuous intravenous (IV) infusion and because analysis is relatively simple. Although the clearances of 99mTc-diethylenetriamine-pentaacetic acid (DTPA), 169Yb-DTPA, and 125I-iothalamate have each been compared with inulin, rarely has the comparability of radioisotopic filtration markers been directly evaluated in the same subject. To this purpose, we determined the renal clearance of inulin administered by continuous infusion and the above radioisotopic filtration markers administered as bolus injections, simultaneously in four subjects with normal renal function and 16 subjects with renal insufficiency. Subjects were studied twice in order to assess within-study and between-study variability. Unlabeled iothalamate was infused during the second half of each study to assess its effect on clearances. We found that renal clearance of 125I-iothalamate and 169Yb-DTPA significantly exceeded clearance of inulin in patients with renal insufficiency, but only by several mL.min-1.1.73m-2. Overestimation of inulin clearance by radioisotopic filtration markers was found in all normal subjects. No differences between markers were found in the coefficient of variation of clearances either between periods on a given study day (within-day variability) or between the two study days (between-day variability). The true test variability between days did not correlate with within-test variability. We conclude that the renal clearance of 99mTc-DTPA, 169Yb-DTPA, or 125I-iothalamate administered as a single IV or subcutaneous injection can be used to accurately measure GFR in subjects with renal insufficiency; use of the single injection technique may overestimate GFR in normal subjects.

Creatinine↗

PubMed1989

Cigarette smoke degrades hyaluronic acid.

Cigarette smoke has been implicated in the pathogenesis of a variety of diseases that affect connective tissues. The effect of the gas phase of cigarette smoke on hyaluronic acid was investigated in vitro. The smoke markedly reduced the chain length of purified hyaluronic acid as assessed by both viscometry and gel chromatography. The hyaluronate exposed to smoke, nevertheless, could aggregate proteoglycans, although the viscosity of the aggregates was lower than in those formed with the unexposed material. The degradation of the hyaluronate was a rapid phenomenon and was inhibited by dimethylsulfoxide, a known scavenger of hydroxyl radicals. We conclude that free radicals in the gas phase of cigarette smoke degrade hyaluronic acid in vitro.

Chromatography, Gel↗

PubMed1989

The role of prostacyclin in the mesenteric traction syndrome during anesthesia for abdominal aortic reconstructive surgery.

Mesenteric traction syndrome consists of sudden tachycardia, hypotension, and cutaneous hyperemia, and frequently occurs during mesenteric traction in patients undergoing abdominal aortic aneurysm (AAA) reconstructive surgery. The etiology and clinical impact of this phenomenon are unknown, but the symptoms suggest a release of vasoactive materials from the mesenteric vascular bed. Thirty-one patients who underwent AAA surgery were studied. Mesenteric traction was accompanied by a decrease in systolic (p = 0.005) and diastolic (p less than 0.05) blood pressures, and in systemic vascular resistance (p less than 0.005), and was accompanied by an increase in heart rate (HR) (p less than 0.005), and cardiac output (p = 0.01). These hemodynamic changes coincided with an increase (p less than 0.001) in plasma concentrations of 6-keto-prostaglandin F1 (6-K-PGF1). No apparent change was found in prostaglandin E2, thromboxane B2, and histamine concentrations. The concentration of 6-K-PGF1 was correlated with diastolic blood pressure (r = -0.52, p less than 0.005) and HR (r = 0.65, p less than 0.001). Cutaneous hyperemia was observed in 58% of the patients. In an additional six patients, who had taken aspirin daily before AAA surgery, no significant changes were observed in the hemodynamic measurements or 6-K-PGF1 concentrations. These data suggest that mesenteric traction syndrome may be mediated at least in part by a selective release of prostacyclin.

6-Ketoprostaglandin F1 alpha↗

PubMed1989

Neurologic complications of endocarditis: a 12-year experience.

We reviewed the neurologic complications in 113 patients with native and 62 patients with prosthetic valve endocarditis. Neurologic complications occurred with the same frequency (35.3% vs 38.7%) and distribution among the two groups. Death occurred in 20.6% of patients with neurologic complications and in 13.6% of patients without neurologic complications (p = 0.23). Staphylococcus aureus endocarditis correlated statistically with the development of neurologic complications (p less than 0.01) and death (p less than 0.01). Among 50 patients discharged from the hospital after receiving only medical treatment for native valve endocarditis, and followed for a mean period of 48 months, there was one patient with mitral valve prolapse and stroke. We conclude that (1) neurologic complications occur with the same frequency in native and prosthetic valve endocarditis, (2) S aureus endocarditis increases the risk of neurologic complications and death, (3) mortality is not significantly increased in patients with neurologic complications, and (4) an episode of treated native valve endocarditis does not increase the natural history of stroke in valvular disease.

Anticoagulants↗

PubMed1989

Smoking and cotton dust effects in cotton textile workers.

Cotton textile workers have an increased prevalence of both obstructive and restrictive lung function patterns compared with control subjects. Similar abnormal patterns may occur with respiratory diseases of other etiologies, notably those associated with cigarette smoking. The shape of the maximum expiratory flow volume (MEFV) curve has been used to characterize patterns of lung function abnormality. To better evaluate the respiratory effects of cotton dust exposure and to contrast them with those of cigarette smoking, we defined a new functional parameter (angle beta) related to the shape of the MEFV curve. We compared 477 cotton textile workers, both current smokers and never smokers, 45 years and older, with 932 similarly aged control subjects from three communities. Smokers, regardless of their occupational exposure or sex, have smaller beta values than nonsmokers. Cotton textile workers, despite a greater prevalence of abnormal lung function, have beta values that do not differ from those of persons without occupational exposure to cotton dust. We suggest that morphologic patterns of flow volume curves reflect separate effects of cotton dust exposure and smoking and may be related to different sites of airway injury.

Aged↗

PubMed1989

The effect of subarachnoid hemorrhage on blood and CSF atrial natriuretic factor.

Atrial natriuretic factor (ANF) is a diuretic natriuretic peptide hormone produced by both the heart and brain which has been postulated to play a role in the hemodynamic and sodium instability that frequently follows subarachnoid hemorrhage (SAH). Levels of ANF were measured in 12 patients with nontraumatic SAH and nine control patients with unruptured cerebral aneurysms. At surgery, the mean plasma ANF level (+/- standard deviation) of the SAH group was significantly higher than that of the control group (158.1 +/- 83.8 vs. 57.8 +/- 45.3 pg/ml, respectively; p = 0.01). There was no significant difference in serum sodium concentration, blood pressure, or central venous pressure between these groups. Nine patients with SAH due to aneurysm rupture had plasma ANF levels similar to those in three patients with SAH due to other causes. Four patients with moderate to severe SAH had significantly higher mean cerebrospinal fluid (CSF) ANF values (17.7 +/- 12.8 pg/ml) than five patients with minimal SAH (0.6 +/- 0.9 pg/ml) or the control group of nine patients (3.7 +/- 1.3 pg/ml) (p less than 0.05). Five patients with moderate to severe SAH had significantly higher plasma ANF values (202.6 +/- 72.2 pg/ml) than five with minimal SAH (86.8 +/- 29.2 pg/ml) or the control group (57.8 +/- 45.3 pg/ml) (p less than 0.05). Plasma ANF values were substantially higher than CSF ANF content in the SAH group (p less than 0.01) and in the control group (p = 0.05). From these data it is concluded that: 1) plasma ANF is elevated significantly after SAH; 2) this rise appears unrelated to the cause of hemorrhage, serum sodium concentration, blood pressure, or central venous pressure, but is related to the extent of the hemorrhage; 3) ANF concentrations in the CSF are significantly lower than in plasma, and are elevated after moderate to severe SAH; and 4) the source of CSF ANF is probably the plasma, and the source of plasma ANF is likely the heart.

Adult↗

PubMed1988

Percutaneous transluminal angioplasty for shepherd's crook right coronary artery stenosis.

Angiograms from 1,043 consecutive patients undergoing right coronary artery angioplasty were reviewed to determine the incidence of "shepherd's crook" origin of the right coronary artery. Primary results, complications, and technical difficulties were compared with a control group. Fifty-one patients (4.9%) were found to have this anatomic variation. Compared with a control group, the primary success rate was lower (86% vs. 98%) and the incidence of procedural difficulties was higher (33% vs. 13%). Technical problems led to the use of more guiding catheters and more guidewires per patient than in the control group. Thus, coronary angioplasty of shepherd's crook right coronary artery imposes technical problems and is associated with less than an optimal primary success rate.

Angiography↗

PubMed1988

Uncontrolled trial of cryofiltration in rheumatoid arthritis.

In an open trial of cryofiltration in rheumatoid arthritis at our institution, 19 patients received 464 treatments; the intensive schedule of ten treatments in 5 weeks was completed in 14 of the 19, and excellent to good clinical response was achieved in ten of these. The combined results demonstrated significant reductions in Ritchie index, morning stiffness, and 50-foot-walk time in the intensive treatment period, as well as significant increases in hand grip strengths. In the maintenance treatment period treatment frequency was individually selected and at less frequent intervals. Changes in clinical parameters were notably less. Although significant correlations were observed between the percent change in clinical parameters and the percent change in biochemical and hematological parameters, no consistent pattern was found. The favorable results of this trial and other uncontrolled trials has led to a two-center double-blind controlled trial of cryofiltration in rheumatoid arthritis that is now in progress.

Adult↗

PubMed1988

The effect of antenatal surgery on postnatal palatal growth in sheep.

It has been suggested that repair of skin and mucosal wounds carried out in animals in utero leaves little or no trace of the operative procedure when examined at birth. This study examined the palates of lambs affected surgically in utero postnatally for scarring and transverse palatal growth. Nineteen pregnant sheep were affected at 120 days gestation. Surviving lambs followed for 6 months demonstrated altered palatal morphology.

Animals↗