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Biomedical subjects

S R Goldstein

Publications and source records attributed to S R Goldstein.

89 records · Page 5Linked to original sources
PubMed1984

Bayesian comparison of cost-effectiveness of different clinical approaches to diagnose coronary artery disease.

The objective of this study was to compare the cost-effectiveness of four clinical policies (policies I to IV) in the diagnosis of the presence or absence of coronary artery disease. A model based on Bayes' theorem and published clinical data was constructed to make these comparisons. Effectiveness was defined as either the number of patients with coronary disease diagnosed or as the number of quality-adjusted life years extended by therapy after the diagnosis of coronary disease. The following conclusions arise strictly from analysis of the model and may not necessarily be applicable to all situations. As prevalence of coronary disease in the population increased, it caused a linear increase in cost per patient tested, but a hyperbolic decrease in cost per effect, that is, increased cost-effectiveness. Thus, cost-effectiveness of all policies (I to IV) was poor in populations with a prevalence of disease below 10%, for example, asymptomatic people with no risk factors. Analysis of the model also indicates that at prevalences less than 80%, exercise thallium scintigraphy alone as a first test (policy II) is a more cost-effective initial test than is exercise electrocardiography alone as a first test (policy I) or exercise electrocardiography first combined with thallium imaging as a second test (policy IV). Exercise electrocardiography before thallium imaging (policy IV) is more cost-effective than exercise electrocardiography alone (policy I) at prevalences less than 80%. 4) Noninvasive exercise testing before angiography (policies I, II and IV) is more cost-effective than using coronary angiography as the first and only test (policy III) at prevalences less than 80%. 5) Above a threshold value of prevalence of 80% (for example patients with typical angina), proceeding to angiography as the first test (policy III) was more cost-effective than initial noninvasive exercise tests (policies I, II and IV). One advantage of this quantitative model is that it estimates a threshold value of prevalence (80%) at which the rank order of policies changes. The model also allows substitution of different values for any variable as a way of accounting for the uncertainty inherent in the data. In conclusion, it is essential to consider the prevalence of disease when selecting the most cost-effective clinical approach to making a diagnosis.

Angiography↗
PubMed1984

Transmural pH gradient in canine myocardial ischemia.

The subendocardium is more susceptible to ischemia than the subepicardium. Studies during critical coronary stenosis have demonstrated subendocardial hypoperfusion relative to the subepicardium and transmural gradients in certain tissue metabolites. Although ischemia causes acidosis, the existence of a transmural pH gradient has never been demonstrated or quantitated. Thus we reduced coronary blood flow to 20 +/- 5% of normal in eight open chest anesthetized (morphine sulfate and pentobarbital) dogs and to 45 +/- 5% in two dogs. We implanted specially designed miniature fiber-optic pH probes in normal and ischemic subendocardium (depth 5.5-8 mm) and subepicardium (depth 3-4 mm). Separate experiments validated use of the fiber-optic pH probe system to measure tissue pH. Although both probes were located in the ischemic zone, there was a large transmural gradient, i.e., from normal pH values (7.36) in the subepicardium to severely acidotic (pH 6.94) 2 mm deeper in the subendocardium. This marked difference in pH between nearby transmural layers may have important implications regarding arrhythmogenesis in the setting of acute myocardial ischemia.

Animals↗
PubMed1983

Hematosalpinx in tubal pregnancy: sonographic-pathologic correlation.

Review of sonograms in 84 patients with documented tubal pregnancies yielded 15 cases with discrete, diffusely echogenic, adnexal masses (18%). All these cases were proven at surgery to represent hematosalpinx containing clotted blood. The characteristic sonographic findings in these cases enabled an accurate preoperative diagnosis in 12 consecutive patients. Hematosalpinx containing clotted blood was seen as a diffusely echogenic adnexal mass accompanied in most cases by areas of high-intensity echoes. Pelvic hemoperitoneum (five cases) was diffusely echogenic due to clotted blood, and its recognition enabled evaluation of the upper abdomen for extension of hemorrhage. The echogenicity of the adnexal mass and pelvic hematoma was similar to that of the uterus, resulting in obscuration of its contour. The following sonographic features are characteristic of tubal pregnancy in the proper clinical setting: (1) absence of intrauterine gestation; (2) diffusely echogenic adnexal mass with areas of high-intensity echoes; and (3) diffusely echogenic hematoma in the pouch of Douglas.

Adnexa Uteri↗
PubMed1983

Subchorionic bleeding in threatened abortion: sonographic findings and significance.

Fifty-six patients with clinical threatened abortion were evaluated by sonography. In six patients, fetal cardiac activity was absent at or beyond 9 weeks of gestation, and fetal death was confirmed in all six cases. In the other 50 patients, fetal cardiac activity was present at or beyond 9 weeks of gestation. In 10 (20%) of these 50 patients, subchorionic bleeding was present in various degrees, appearing sonographically as an extrachorionic crescentic anechoic or complex collection. The final outcome in the 50 patients with fetal cardiac activity was as follows: In the absence of subchorionic bleeding, 100% of the pregnancies progressed to term; in the presence of subchorionic bleeding the positive outcome was reduced to 80%. In addition to signs of fetal life on sonography, subchorionic bleeding is an important factor affecting the outcome of gestations in patients with clinical threatened abortion.

Abortion, Threatened↗
PubMed1980

A miniature fiber optic pH sensor for physiological use.

A flexible 0.4-mm-dia pH probe potentially suitable for physiological use has been developed. It is based on the concept of utilizing two single plastic fiber optic strands to illuminate and remotely sense the color change of a dye indicator contained within an acutely implanted sealed cellulosic hollow fiber permeable to hydrogen ions. A supporting electronic module provides tungsten filament illumination, light sensing with a photodiode/operational amplifier, analog and digital circuitry to provide appropriate signal averaging and processing, and a mechanical assembly to enable the optical density measurements to be made both at 560 nm and, for normalization purposes, in the red. Over the physiological pH range from 7.0 to 7.4, the fiber optic probe agrees with a standard glass pH electrode to within 0.01 pH units in buffer solutions, to within 0.017 pH units in heparinized dog blood in vitro, and it has performed successfully while implanted in the jugular vein of a sheep.

Analog-Digital Conversion↗
PubMed1979

The toposcopic catheter: a design for maneuvering through tortuous vessels.

The toposcopic catheter is an everting tube that advances within a vessel without moving over the endothelium. It easily passed through simulated tortuous vessels which other catheters could not negotiate and was also successful in the external carotid, vertebral, hepatic, renal and coronary arteries in dogs. The catheter advances to its full length (30 cm) or until wedged in small peripheral arteries.

Animals↗
PubMed1977

Intracellular recording from pulsating cerebral cortex.

An instrument has been developed for recording intracellulary from cortical neurons in an exposed pulsating brain. The electrode moves with the brain pulsations maintaining the electrode within the impaled cell. Stable recordings have been obtained for up to 20 min.

Animals↗
PubMed1975

An instrument for stable single cell recording from pulsating human cerebral cortex.

An instrument has been developed for positioning microelectrodes near neurons in the exposed pulsating cerebral cortex of man or animals. The electrode moves with the cortex and maintains a fixed relationship with the desired neuron. Stable extracellular single cell recordings have been obtained for 17.5 min from an exposed human brain that pulsated 1.5 mm at the surface.

Cerebral Cortex↗
PubMedDate not supplied

A pharmacological review of selective oestrogen receptor modulators.

Selective oestrogen receptor modulators (SERMs) are structurally diverse non-steroidal compounds that bind to oestrogen receptors and produce oestrogen agonist effects in some tissues and oestrogen antagonist effects in others. SERMs are being evaluated for a number of oestrogen-related diseases, including post-menopausal osteoporosis, hormone-dependent cancers, and cardiovascular disease. Several compounds that exhibit a SERM profile are currently available for clinical use, including clomiphene, tamoxifen, and toremifene (which are triphenylethylenes) and raloxifene (a benzothiophene). Clomiphene is used for the induction of ovulation in sub-fertile women attempting pregnancy. Tamoxifen and toremifene are both used to treat breast cancer. Tamoxifen may have beneficial effects on bone mineral density and serum lipids. The effects of toremifene on serum lipids are similar to that of tamoxifen. Both compounds have stimulatory effects on the endometrium. Raloxifene, indicated for the treatment and prevention of post-menopausal osteoporosis, has beneficial effects on bone mineral density and serum lipids, but does not increase the risk of endometrial hyperplasia or endometrial cancer. Recently, raloxifene was shown to reduce the incidence of vertebral fractures in otherwise healthy women with osteoporosis; in the same study, a reduced incidence of breast cancer was also observed. Similar to oestrogens, SERMs increase the incidence of venous thromboembolism. Several newer compounds that exhibit a SERM profile are also in clinical development, including other triphenylethylenes (droloxifene, idoxifene) and benzothiophenes (LY353381.HCl), benzopyrans (EM-800), and naphthalenes (CP-336,156).

Breast Neoplasms↗
PubMedDate not supplied

A miniature fiberoptic pH sensor potentially suitable for glucose measurements.

A fiberoptic sensor that we have developed for measuring physiologic pH is a potentially useful model for similar probes for other important applications such as monitoring glucose in the body. A fiberoptic probe has important advantages over an electrode in safety, reliability, applicability, and cost. The pH probe is described, with suggested approaches for making a device for glucose measurement.

Fiber Optic Technology↗
PubMedDate not supplied

Selective estrogen receptor modulators: a new category of compounds to extend postmenopausal women's health.

Selective estrogen receptor modulators (SERMs) are a new category of therapeutic agents, which bind with high affinity to estrogen receptors and mimic the effect of estrogens in some tissues but act as estrogen antagonists in others. Tamoxifen, a triphenylethylene derivative, was the first clinically available SERM. It is a potent anti-estrogen in the breast, and its use in breast cancer patients has made it the most widely prescribed antineoplastic drug worldwide. It has estrogen-like activity on bone metabolism, as well as cholesterol reduction. However, its ability to produce proliferation, and polyp formation, and even carcinomas, in the endometrium is well known. A new SERM, raloxifene, a benzothiopene derivative, has a clinical profile similar to tamoxifen's. However, preclinical as well as clinical studies reveal that unlike tamoxifen it is a pure anti-estrogen in the uterus. It has recently been FDA approved for prevention of osteoporosis in postmenopausal women. This report reviews pertinent preclinical and currently available clinical studies about this new SERM and discusses clinical applicability.

Bone Density↗