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Biomedical subjects

B Berkowitz

Publications and source records attributed to B Berkowitz.

At least 19 recordsLinked to original sources
PubMed2001

Advective transport in the percolation backbone in two dimensions.

We show that, in the case of advective transport on the percolation backbone, the relevant structure below the correlation length is an ensemble of tortuous paths, rather than the classical links-nodes-blobs system. These paths are embedded in the few largest blobs that dominate the structure of the backbone. We find numerically that the mean particle displacement differs from the prediction given by classical finite-size scaling arguments. We also show that because of the complex velocity distribution between the paths, the mean first-passage time of the particles cannot be inferred directly from the mean particle displacement.

Journal Article↗
PubMed2001

Analysis of field observations of tracer transport in a fractured till.

We analyze a set of observations from a recently published, field-scale tracer test in a fractured till. These observations demonstrate a dominant, underlying non-Fickian behavior, which cannot be quantified using traditional modeling approaches. We use a continuous time random walk (CTRW) approach which thoroughly accounts for the measurements, and which is based on a physical picture of contaminant motion that is consistent with the geometric and hydraulic characterization of the fractured formation. We also incorporate convolution techniques in the CTRW theory, to consider transport between different regions containing distinct heterogeneity patterns. These results enhance the possibility that limitations in predicting non-Fickian modes of contaminant migration can be overcome.

Chlorides↗
PubMed2001

Studying the outcomes of community-based coalitions.

Community-based coalitions are popular structures for creating community benefits. But desired effects have been reported only for single cases, the overall documented evidence to date for positive coalition outcomes being weak. Methodological obstacles may account for much of the missing evidence, and research possibilities for addressing these obstacles are suggested. Alternative interpretations include the positions that coalitions in general are not effective intervention mechanisms, that traditional scientific methodology is poorly suited for capturing fine-grained coalition outcomes, and that coalitions and similar collaborative organizations are too complex to be adequately evaluated by the methodology that is now available.

Benchmarking↗
PubMed2000

Collaboration for health improvement: models for state, community, and academic partnerships.

The value of approaching health improvement through collaborative models seems self-evident, especially at the community level. A review of the literature, however, reveals a number of challenges in terms of helping us understand precisely what it is that makes collaborative models effective in influencing health. The purpose of this article is to describe important elements of collaboration that state, local, and academic partners may wish to consider when developing models for health improvement. The author will provide examples of collaborative strategies that are emerging from the Turning Point: Collaborating for a New Century in Public Health initiative.

Community Participation↗
PubMed1995

Quantitative analysis of dynamic Gd-DTPA enhancement in breast tumors using a permeability model.

The MRI signal enhancement in a breast tumor, measured as a function of time after a bolus injection of Gd-DTPA, may contain enough information to differentiate malignant from benign tissue. We find a physiological model for measuring capillary permeability and leakage space (P. S. Tofts, A. G. Kermode, measurement of the blood-brain barrier permeability and leakage space using dynamic MR imaging. 1. Fundamental concepts. Magn. Reson. Med. 17, 357-367 (1991)) fits the data well. The enhancement curve is particularly sensitive to the preinjection T1 of the tumor, the dose, and the time of injection. This model may provide a means of characterizing the pathophysiology of breast tumors from the Gd-DTPA enhancement curve.

Breast↗
PubMed1995

Health system reform: a blueprint for the future of public health.

As the state of Washington formulated its health reform legislation, public health successfully advocated for its inclusion as integral to successful reform. The blueprint for public health's role within health reform is The Public Health Improvement Plan. The plan describes standards for the infrastructure and performance required to carry out the core functions of public health. It contains outcome standards, threshold standards, and interventions for key problems currently affecting the health status of Washington residents. The plan also recommends the shared financing and governance responsibilities for public health functions within a reformed health system.

Forecasting↗
PubMed1993

Evaluation of the one-session Eye-movement Desensitization Reprocessing procedure for eliminating traumatic memories.

Eye-movement Desensitization Reprocessing (EMDR) is a relatively new therapy technique originally reported to eliminate traumatic memories (rape, catastrophes) in one session. Early published research has tended to support the technique. However, there is controversy and at least one unpublished recent study by Rothbaum who reported only about one-half of her cases had successful outcomes. The present study was conducted as a preliminary evaluation in 1990. Our results were judged to be unsuccessful in five of eight cases and successful in three cases. Further, the cases with the most pathology improved the least. The techniques, cases, and outcomes are presented to provide additional data on this new and controversial therapeutic technique.

Adult↗
PubMed1991

19F NMR quantitation of lens aldose reductase activity using 3-deoxy-3-fluoro-D-glucose.

In the present study we have determined the kinetics of 3-deoxy-3-fluoro-D-glucose (3-FG) as a substrate for the aldose reductase reaction in vitro. In addition, we compared the 3-deoxy-3-fluoro-sorbitol (3-FS) production rates from 3-FG in the intact lens using 19F NMR with conventional aldose reductase determinations in extracts from the same lenses. The affinity of in vitro aldose reductase for 3-FG was approximately 20 times greater (9.3 mM) than that for glucose (188 mM). An excellent correlation between the rate of 3-FS production in the intact canine lens, determined with 19F NMR, and extracted aldose reductase activity was observed. The relatively high affinity of aldose reductase for 3-FG and the correlation of 3-FS production with enzyme activity in the intact lens suggests that 3-FS production from 3-FG detected by 19F NMR could provide an accurate noninvasive determination of aldose reductase activity in the eye lens.

Aldehyde Reductase↗
PubMed1989

Nail changes associated with scleroderma: a case report.

A case report and literature review on the association of nail changes and scleroderma was presented. The exact etiology of these nail changes seen in scleroderma and of the disease entity itself, has not yet been determined. The current treatment regimen, which is at best supportive, was discussed. Proper treatment of the nail changes depends on a good understanding of what to expect as the disease or condition progresses to its later stages. The extent and severity of the onychodystrophy can be correlated with the duration of the disease. Nonetheless, there are still questions that remain to be answered regarding the nail changes associated with scleroderma. For example, are these nail changes the result of Raynaud's phenomenon and its associated arterial insufficiency, or are they a normal sequelae of the integumentary degeneration so characteristic of scleroderma? Whatever the answer may be, it should be recognized that these changes are a source of clinical concern. Practitioners should take note of this clinical entity and record their findings so that these perplexing questions, as well as many others, may be discussed in the future.

Adult↗
PubMed1983

2-nor-leukotriene analogs: antagonists of the airway and vascular smooth muscle effects of leukotriene C4, D4 and E4.

A structural analog of LTD4, 4R-hydroxy-5S-cysteinylglycyl-6Z-nonadecenoic acid (4R, 5S, 6Z-2-nor-LTD1) has been synthesized and pharmacologically characterized. It significantly antagonized the contractile action of LTD4, LTC4 and LTE4 in guinea pig airways. In addition, this compound antagonized the in vitro vasoconstrictive effects of LTD4 in the guinea pig pulmonary artery. The study of a series of structural analogs of 4R, 5S, 6Z-2-nor-LTD1 suggests that the spatial separation of the C-1 (eicosanoid) carboxyl relative to the hydroxyl is a critical determinant in LTD4 agonist/antagonist activity.

Airway Resistance↗
PubMed1983

Potential usefulness of renal vasodilators in hypertension and renal disease: SK&F 82526.

SK&F 82526 and its enantiomers have been shown to increase renal blood flow and decrease renal vascular resistance in the anesthetized dog. The effect of the racemate on lowering systemic blood pressure in the anesthetized dog and the spontaneously hypertensive rat has been shown to be caused by the R-enantiomer with the S-enantiomer being devoid of significant activity on blood pressure. The mechanism by which the R-enantiomer decreases blood pressure is not systemic vasodilatation or prejunctional inhibition of norepinephrine release but appears to result from a unique stimulation of the postjunctional dopamine receptor. Racemic SK&F 82526 also has been shown to increase renal blood flow in an ischemic model of acute renal failure.

Animals↗
PubMed1980

Isolated brain microvessels: preparation, morphology, histamine and catecholamine contents.

A method for the rapid preparation of parenchymal microvessels from rat, rabbit and bovine brains is described. Light and electron microscopic examination of the isolated microvessels showed the smooth muscle and endothelial cells to be intact and substantially free of neutrophil contamination. The observation of 0.2 to 2.0 micron electron dense granules in the adventitial space associated with some of the isolated arteriolar elements and the identification of histamine in microvessel extracts is suggestive of the presence of mast cells in the microvessel preparations. Age-dependent changes in histamine content and an increased histamine content in microvessels from hypertensive rats were noted. Using a sensitive radioenzymatic assay, the catecholamine (CA) contents of microvessels isolated from cow, rat and rabbit were measured. The total CA contents of all microvessel preparations were small (< 0.35 microgram g-1) with norepinephrine being the predominant CA present. A large ratio of dopamine to norepinephrine was found in microvessels from rat and bovine brain. The possible origins of the CAs present in the isolated microvessels are discussed.

Animals↗
PubMed1979

Hypnotic treatment of smoking: the single-treatment method revisited.

The authors replicated Spiegel's single-treatment method by treating 40 self-referred patients in a one-hour hypnosis session for smoking. Their results, a 6-month total abstinence rate of about 25%, were comparable with Spiegel's experience. They recommend future studies that include nontreatment control groups to validate the effects of the hypnotic treatment method of smoking.

Adult↗