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Biomedical subjects

R L Wolf

Publications and source records attributed to R L Wolf.

At least 19 recordsLinked to original sources
PubMed2006

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy.

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.

Aged↗
PubMed2002

Development of a posterior cerebral artery aneurysm subsequent to occlusion of the contralateral internal carotid artery for giant cavernous aneurysm.

We report a case of a patient who developed a left posterior cerebral artery aneurysm 5 years after balloon occlusion of the right internal carotid artery for a giant cavernous aneurysm. The location of the new aneurysm was outside of the primary collateral pathways to the contralateral, proximally occluded, anterior circulation, illustrating the complexity of hemodynamic factors contributing to the development of intracranial saccular aneurysms. The appearance of an aneurysm in this setting supports the hypothesis that degenerative factors and hemodynamic stresses are important in the etiology of intracranial aneurysms.

Balloon Occlusion↗
PubMed2001

MRI identification of early white matter injury in anoxic-ischemic encephalopathy.

BACKGROUND: Anoxic-ischemic encephalopathy (AIE) affects the gray matter more than the white matter. Recent animal experiments suggest that the white matter is more sensitive to ischemia than previously thought. The authors describe the MRI findings in seven patients with AIE who demonstrate early preferential involvement of the white matter. MATERIALS AND METHODS: A retrospective case series study was performed, including seven patients with AIE who underwent MRI of the brain within 7 days of insult. Demographic information, type of insult, clinical examination findings, EEG findings, and clinical outcome were obtained. MRI studies were reviewed with specific attention to the cortex, deep gray matter, and the white matter structures. Mean apparent diffusion coefficient (ADC) was calculated in regions of interest placed in the cerebellar hemispheres, putamen, thalamus, splenium of corpus callosum, centrum semiovale, and medial frontal cortex. RESULTS: The causes of AIE were cardiac arrhythmias in two patients, myocardial infarction in one, drug overdose in two, carbon monoxide poisoning in one, and respiratory failure and sepsis in one. The median time to MRI was 2.5 days. Symmetric areas of restricted diffusion were found in the periventricular white matter tracts (7/7 patients), the corpus callosum (6/7 patients), internal capsule (5/7 patients), and the subcortical association fibers (3/7 patients). ADC maps confirmed the restricted diffusion. Gray matter involvement was seen in three patients, and was more prominent on conventional imaging sequences compared with diffusion-weighted imaging. A subtle decrease in mean ADC was seen in cortex. CONCLUSIONS: Prominent, symmetric restricted diffusion can occur early after AIE in white matter, whereas gray matter involvement may be less prominent. Further studies involving a larger sample and serial imaging are required to confirm these preliminary findings.

Adult↗
PubMed2001

Ethnic differences in asthma and associated phenotypes: collaborative study on the genetics of asthma.

BACKGROUND: In the Collaborative Study on the Genetics of Asthma, 314 families with 2584 subjects were characterized for asthma and allergy. OBJECTIVE: The purpose of this investigation was to examine clinical heterogeneity observed in asthma and allergic characteristics among 3 ethnic groups (African American, white, and Hispanic family members). METHODS: Pulmonary function parameters and asthma associated phenotypes were compared among the ethnic groups. RESULTS: In comparison with the other groups, African American sibling pairs had a significantly lower baseline FEV(1) percent of predicted (P =.0001) and a higher rate of skin test reactivity to cockroach allergen (P =.0001); Hispanic sibling pairs had significantly more skin reactivity overall (P =.001); and white sibling pairs had significantly lower total serum IgE (P <.05). In addition, there were significantly more relatives with asthma among the African American families than among the white and the Hispanic families (P =.001). CONCLUSION: Although different environmental backgrounds should be considered, these clinical differences could be due to differences in genetic susceptibility among the ethnic groups, such as those suggested by our previous genome screen.

Adolescent↗
PubMed2001

Knowledge, beliefs, and barriers relevant to colorectal cancer screening in an urban population: a pilot study.

A sample of 115 urban, working-class, predominantly minority men and women was interviewed by telephone to assess knowledge, beliefs, and barriers relevant to colorectal cancer (CRC) and CRC screening. More than half (53.9%) were unable to name a CRC screening test. Misconceptions were common. Dispelling inaccurate beliefs, establishing an individual's preference for fecal occult blood tests or flexible sigmoidoscopy, and helping individuals take a proactive role in the receipt of CRC screening are important goals for health education efforts aimed at increasing rates of CRC screening. Participants' willingness to engage in detailed telephone conversations about CRC and CRC screening was encouraging.

Aged↗
PubMed2001

Quantitative apparent diffusion coefficient measurements in term neonates for early detection of hypoxic-ischemic brain injury: initial experience.

PURPOSE: To determine the utility of using quantitative apparent diffusion coefficient (ADC) values as an objective means of early detection of brain injury caused by hypoxic-ischemic encephalopathy (HIE) in term neonates. MATERIALS AND METHODS: Conventional images, diffusion-weighted images, ADC maps, and clinical charts from 13 term neonates clinically suspected of having HIE were retrospectively reviewed. Four term neonates without HIE served as control subjects. ADC values were calculated in predefined regions in patients and compared with those in control subjects. A Student t test was performed for each region to compare patients and control subjects. RESULTS: Abnormalities were more easily detected on diffusion-weighted images and ADC maps, compared with conventional images. ADC values in patients with HIE were significantly different from those of control subjects in the posterior limb of the internal capsule, corona radiata, posterior frontal white matter, and parietal white matter bilaterally. CONCLUSION: Evaluation of ADC maps can improve conspicuity of hypoxic-ischemic injury in the acute and/or subacute setting (within 12 days of insult), and calculation of ADC values can provide an objective measure of hypoxic-ischemic injury.

Diffusion↗
PubMed2001

Detection of mesial temporal lobe hypoperfusion in patients with temporal lobe epilepsy by use of arterial spin labeled perfusion MR imaging.

BACKGROUND AND PURPOSE: Interictal hypometabolism has lateralizing value in cases of temporal lobe epilepsy and positive predictive value for seizure-free outcome after surgery to treat epilepsy. Alterations in regional cerebral metabolism can also be inferred from measurements of regional cerebral perfusion. The purpose of this study was to determine the feasibility of detecting cerebral blood flow (CBF) asymmetries in the mesial temporal lobes using continuous arterial spin labeling perfusion MR imaging, which is a noninvasive method for calculating regional CBF. METHODS: Twelve patients with medically refractory temporal lobe epilepsy who underwent preoperative evaluation for temporal lobectomy and 12 normal control participants were studied retrospectively. Absolute and normalized mesial temporal CBF measurements were compared between the patient and control groups. Lateralization based on a perfusion asymmetry index was compared with metabolic ((18)[F]-fluorodeoxyglucose positron emission tomography) and hippocampal volumetric asymmetry indices and with clinical lateralization. RESULTS: Mesial temporal CBF was more asymmetric in patients with temporal lobe epilepsy than in normal control participants, although asymmetric mesial temporal CBF was also found in normal participants, with the left side dominant. Ipsilateral mesial temporal CBF was significantly decreased compared with contralateral mesial temporal CBF in patients with temporal lobe epilepsy. Global CBF measurements were significantly decreased in patients compared with control participants. Asymmetry in mesial temporal blood flow in patients persisted after normalization to global CBF. Lateralization using continuous arterial spin labeling perfusion MR imaging asymmetry index significantly correlated with lateralization based on (18)[F]-fluorodeoxyglucose positron emission tomography hypometabolism, hippocampal volumes, and clinical evaluation. CONCLUSION: Continuous arterial spin labeling perfusion MR imaging can detect interictal asymmetries in mesial temporal lobe perfusion in patients with temporal lobe epilepsy. This technique is readily combined with routine structural assessment and potentially offers an inexpensive and noninvasive means of screening for asymmetries in interictal mesial temporal lobe function.

Adult↗
PubMed2000

Low fractional calcium absorption increases the risk for hip fracture in women with low calcium intake. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Decreased ability to absorb calcium with age limits adaptation to low calcium intake and is thought to lead to secondary hyperparathyroidism and increased risk for hip and other fractures. However, the associations between fractional calcium absorption, dietary calcium intake, and risk for fracture have never been studied. OBJECTIVE: To determine whether low fractional calcium absorption in women with low calcium intake increases the risk for subsequent hip and other nonspine fractures. DESIGN: Prospective cohort study. SETTING: Four clinical centers in Baltimore County, Maryland; Portland, Oregon; Minneapolis, Minnesota; and the Monongahela Valley, Pennsylvania. PARTICIPANTS: 5452 nonblack women 69 years of age or older participating in the fourth examination of the Study of Osteoporotic Fractures. MEASUREMENTS: Fractional calcium absorption was measured by using a 3-hour single isotope (45Ca) technique. Incident fractures were identified prospectively and were confirmed by radiographic report. RESULTS: During an average of 4.8 years, 729 women (13%) experienced at least one nonspine fracture; 153 of these women had hip fractures. After adjustment for age, women with lower fractional calcium absorption were at increased risk for hip fracture (relative risk per 1-SD [7.7%] decrease in fractional calcium absorption, 1.24 [95% CI, 1.05 to 1.48]). Women with low fractional calcium absorption and low calcium intake were at greatest risk for subsequent hip fracture; among women whose dietary calcium intake was less than 400 mg/d, those who had fractional calcium absorption at or below the median value of 32.3% had a 2.5-fold (CI, 1.29-fold to 4.69-fold) increase in risk for hip fracture compared with those who had greater absorption efficiency. Fractional calcium absorption was not related to risk for other nonspine fractures (relative risk per 1-SD [7.7%] decrease in fractional calcium absorption, 1.05 [CI, 0.96 to 1.14]). CONCLUSIONS: In elderly women, low fractional calcium absorption in the setting of low calcium intake increases the risk for hip fracture. Our findings support the hypothesis of type II osteoporosis, which postulates that decreased calcium absorption is an important risk factor for hip fracture in older persons.

Aged↗
PubMed2000

Update on the epidemiology of osteoporosis.

Osteoporosis is a major public health problem that affects the entire aging population. This report provides an update on the epidemiology of osteoporosis and its associated fractures. Published studies from 1997 to the present are highlighted. The current US prevalence estimates for osteoporosis, trends in fracture incidence rates, and latest reports on the morbidity, mortality, and costs attributable to osteoporotic fractures are discussed. Recent advances in our understanding of risk factors associated with osteoporosis and related fractures are reviewed. Special attention is paid to the rapid progress being made in the field of genetics, the growing importance of nutrition, and the new questions being raised as to the influence of hormonal factors on bone mineral density and fracture risk. New studies linking osteoporosis to several other important diseases in women including breast cancer, osteoarthritis, and stroke are also reviewed.

Aged↗
PubMed2000

Factors associated with calcium absorption efficiency in pre- and perimenopausal women.

BACKGROUND: The amount of calcium ingested by an individual may affect several chronic conditions, including osteoporosis, hypertension, and colon cancer. However, individuals vary in their ability to absorb the calcium they consume. OBJECTIVE: The purpose of this study was to examine sources of interindividual variation in the efficiency of calcium absorption in women. DESIGN: Fractional calcium absorption was estimated in 142 healthy pre- and perimenopausal women. Dietary habits, lifestyle factors, calciotropic hormones, and vitamin D receptor gene polymorphisms were also assessed. RESULTS: Calcium absorption values averaged 35% and ranged from 17% to 58%. Fractional calcium absorption was positively associated with body mass index (r = 0.22, P = 0.007), dietary fat intake (r = 0.29, P = 0.001), serum 1,25 dihydroxyvitamin D [1,25(OH)(2)D] concentrations (r = 0.23, P = 0. 006), and parathyroid hormone concentrations (r = 0.21, P = 0.015). Fractional calcium absorption was inversely associated with total calcium intake (r = -0.18, P = 0.030), dietary fiber intake (r = -0. 19, P = 0.028), alcohol consumption (r = -0.14, P = 0.094), physical activity (r = -0.22, P = 0.007), and symptoms of constipation (r = -0.16, P = 0.059). In stepwise regression analysis, dietary fat, dietary fiber, serum 1,25(OH)(2)D, and alcohol consumption emerged as independent predictors of calcium absorption, explaining 21.02% of the observed variation. Women in the lowest tertile of the ratio of dietary fat to fiber had 19% lower fractional calcium absorption values than did women in the highest tertile of ratio of dietary fat to fiber (test of trend, P < 0.001). CONCLUSIONS: There is a wide range of calcium absorption values in healthy women. The amount of dietary fat consumed relative to dietary fiber appears to have an important role in determining differences in calcium absorption performance among individuals.

Absorption↗
PubMed1999

Correlates of quantitative ultrasound in the Women's Healthy Lifestyle Project.

Quantitative ultrasound (QUS) assessment of bone is a strong predictor of hip fractures and is currently an FDA-approved tool to identify women at risk of osteoporosis. However, few studies have investigated the lifestyle and genetic correlates of QUS in women. This study investigated the cross-sectional associates of several lifestyle, demographic and genetic factors with calcaneal QUS parameters (broadband ultrasound attenuation (BUA) and speed of sound (SOS)) in 393 women aged 45-53 years. Leisure-time and historical physical activity, dietary calcium and protein, body composition, vitamin D receptor genotypes, menopause status, other health behaviors, calcaneal QUS parameters and bone mineral density (BMD) were assessed at a single clinic visit. Lean mass, recent physical activity and African-American race were the strongest correlates of SOS whereas dietary protein, calcium and recent physical activity were the strongest correlates of BUA. These predictors explained 13% and 6% of the variance in SOS and BUA, respectively. Smoking, alcohol intake, education, hormone replacement therapy, calcium and vitamin D supplements, historical physical activity and vitamin D receptor genotypes were not significantly associated with BUA or SOS. Lean body mass and premenopausal status were the strongest correlates of lumbar BMD whereas lean body mass, physical activity, African-American race and body mass index were significantly related to femoral neck BMD. Physical activity remained predictive of SOS after controlling for lumbar BMD. The spectrum and magnitude of risk factors for SOS and BUA, including lean body mass, physical activity, race, protein and calcium intake, parallel previously observed predictors of BMD.

Black People↗
PubMed1999

The Chicago Asthma Consortium: a community coalition targeting reductions in asthma morbidity.

The problem of asthma in Chicago remains a complex one, and it is too early to know whether any programs and efforts have had a discernible effect, but the Chicago Asthma Consortium continues to expand its membership and to define its mission. The successes have come from harnessing the passion of the individual members to move the projects forward. As the focus of the consortium moves to addressing system-wide problems in asthma care and the delivery of that care, the consortium is undertaking the construction of a guide for future efforts. In this way, the consortium will fulfill its vision of creating a comprehensive, community-wide plan for the management of asthma, impacting on the unacceptable current levels of morbidity and mortality of the disease.

Asthma↗
PubMed1999

Validation of the Brief Pediatric Asthma Screen.

STUDY OBJECTIVES: The purpose of this study was to confirm the validity of a brief screen for pediatric asthma in schools. BACKGROUND: Asthma is the most common chronic disease of childhood, yet the frequency with which this condition is recognized among school-aged children varies widely. Several methods are used to increase the accuracy of detection of asthma, but many are cumbersome and difficult to apply on a large scale. DESIGN: We elected to validate a five-question instrument, the Brief Pediatric Asthma Screen (BPAS), to screen for the presence of asthma among children attending school in Region 5 of the Chicago school district, where the schools report a 2.7% frequency of asthma. The questionnaire was distributed to the parents of grade-school children at the time of report-card pick-up. SETTING: A clinical assessment was performed on a selected group of children whose parents completed the questionnaire in a school and in a hospital outpatient clinic. PARTICIPANTS: Of 4,147 questionnaires that we distributed, 1,796 (43%) were returned. We excluded 341 children (19% of the total sample) whose parents reported that they had been diagnosed with asthma. The remaining pool indicated that the children of 183 responders (10%) had symptoms suggestive of asthma, while 1,272 parents (71%) indicated that their children did not have symptoms of asthma. MEASUREMENTS AND RESULTS: We selected 90 of the respondents who did not indicate that their children had a diagnosis of asthma. Of this group, 81 completed the validation, in which their responses suggested symptoms of asthma (n = 34) or no asthma symptoms (n = 47). The children of these respondents were given a blinded clinical evaluation consisting of history, physical examination, and spirometry. The survey demonstrated a sensitivity of 75% and a specificity of 81.2% for the presence of asthma among those who were unaware of the diagnosis. CONCLUSIONS: The BPAS is brief, can be filled out by parents, and appears accurate in detecting asthma.

Asthma↗
PubMed1998

Are menopausal symptoms associated with bone mineral density and changes in bone mineral density in premenopausal women?

BACKGROUND: The relationship between menopausal symptoms and bone mineral density (BMD) was examined in 290 premenopausal women, ages 44-50 years, participating in a randomized clinical trial of a dietary and exercise intervention: The Women's Healthy Lifestyle Project. METHODS: Information on hot flashes (presence, absence), menstrual cycles (irregular, regular) and menstrual flow per period (variable, same) over the past 6 months was collected at entry. Participants reporting at least one menopausal symptom were classified as symptomatic and compared to those having no symptoms. Bone mineral density (BMD) at the lumbar spine (L1-L4), total hip and whole-body were made at baseline and at 30 months using a dual-energy X-ray absorptiometer (Hologic QDR 2000 densitometer). RESULTS: Baseline BMD at the spine, hip and whole-body were significantly reduced in women reporting menopausal symptoms compared to asymptomatic women, after adjustment for age, weight and intervention status (all p < 0.05). Women with irregular menstrual cycles had greater annualized rates of bone loss at the spine and hip than asymptomatic women (spine, -0.77 (1.6)% per year vs. -0.19 (1.0)% per year, p = 0.0043; hip, -0.37 (1.1)% per year vs. -0.04 (1.0)% per year, p = 0.061), after adjustments for age, percent change in weight, intervention status, and baseline BMD. Similar findings were not found for whole-body BMD. CONCLUSIONS: These results suggest that menopausal symptoms are useful for the effective identification of premenopausal women at higher risk of low BMD and perhaps, of osteoporosis.

Absorptiometry, Photon↗
PubMed1998

Chicago Asthma Consortium.

The Chicago Asthma Consortium is a group that oversees and attempts to improve the outcomes for the asthmatic population of the city of Chicago and is designed to respond to the perceived needs of this community. It has more than 300 members who operate through six standing committees and in its first year of operation, the Chicago Asthma Consortium has seen notable successes, such as the effecting of a change in a restrictive policy on medication use by students in the Chicago public schools. We describe here the details of the function of the Chicago Asthma Consortium and give examples of its effectiveness in dealing with this common, yet complex, disease.

Asthma↗
PubMed1997

Extremity veins: evaluation with fast-spin-echo MR venography.

The authors evaluated a flow-independent magnetic resonance (MR) imaging technique in extremity veins with slow flow that relies on the prolonged T2 of blood to create angiographic contrast. A commercially available heavily T2-weighted fast-spin-echo sequence was optimized for MR venography in volunteer and phantom studies. Good depiction of venous anatomy was routinely obtained with the optimized method. Fast-spin-echo MR venography allowed evaluation of slow-flow systems such as the calf and forearm veins.

Adult↗
PubMed1997

Vitamin D receptor gene polymorphisms, bone turnover, and rates of bone loss in older African-American women.

Bone mineral density (BMD) is under genetic control. Some studies in Caucasian and Asian women suggest that polymorphisms in the vitamin D receptor (VDR) gene are associated with BMD and the rate of postmenopausal bone loss. We determined if similar associations exist in 101 African-American women aged 65 years and older (71 +/- 5 years, mean +/- SD). We also examined the relation between VDR genotype and fractional 45Ca absorption and markers of bone formation (osteocalcin) and resorption (N-telopeptides) in these women. BMD was measured at the proximal femur and whole body at baseline and after 1.9 +/- 0.4 years (femur only) on a Hologic QDR-2000 densitometer using dual-energy X-ray absorptiometry. Calcaneal BMD was measured with single x-ray absorptiometry. VDR gene polymorphisms were defined by the endonucleases BsmI, ApaI, and TaqI. These polymorphisms were not associated with BMD at any skeletal site or with markers of bone turnover. There was a significant interaction between age and VDR genotype where the oldest women (> 70 years) with the TT genotype experienced greater hip bone loss than women with the TT genotype (-2.1%/year vs. -0.4%/year, respectively), whereas heterozygous women experienced an intermediate rate of bone loss (-1.3%/year). Women homozygous for the B allele had 14% lower fractional 45Ca absorption compared with women homozygous for the b allele, although this difference was not statistically significant (p = 0.08). We conclude that VDR gene polymorphisms are not associated with BMD or indices of bone turnover in this population of older African-American women. However, DNA sequence variation in the VDR gene or a nearby locus may influence intestinal calcium transport and the rate of postmenopausal bone loss in African-American women.

Absorption↗