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Biomedical subjects

R E Goldstein

Publications and source records attributed to R E Goldstein.

At least 55 records · Page 3Linked to original sources
PubMed1997

Sestamibi parathyroid scanning and preoperative localization studies for patients with recurrent/persistent hyperparathyroidism or significant comorbid conditions: development of an optimal localization strategy.

For patients with previous thyroid or parathyroid surgery and for those with significant comorbid conditions, noninvasive and invasive modalities exist for the preoperative localization of pathologic parathyroid tissue. Formal localization at our institution involves obtaining two studies that are independently positive for the same location. The studies utilized have included ultrasound, CT scans, MRI, technetium-99m/thallium-201 (Tc-Tl) imaging, and more recently, (99m)Tc-sestamibi (20-25 mCi) (MIBI) scans. These were followed by arteriography and/or venous sampling if necessary. From January 1992 through October 1995, 25 patients underwent preoperative parathyroid localization (10 reoperation, 3 grave hypercalcemia, 2 concurrent goiter, 2 cerebral vascular accident, 1 bleeding disorder, and 1 malignant ventricular arrhythmia) and were evaluated prospectively during the changeover from Tc-Tl to MIBI scanning at our institution. A total of 92 studies were obtained. All 25 patients were operated on by a single surgeon, and in each case the parathyroid adenoma was successfully resected with minimal morbidity (1 permanent hypoparathyroid and 1 temporary recurrent laryngeal nerve injury). True positives interpreted preoperatively: MIBI, 14 of 19 (74%); CT scan, 13 of 19 (68%); Tc-Tl, 4 of 8 (50%), ultrasound, 9 of 20 (45%); MRI, 8 of 14 (57%); arteriography, 3 of 7 (43%); venous sampling, 3 of 4 (75%); and positron emission tomography, 0 of 1. There were no false-positive MIBI scans. These results suggest that when formal parathyroid localization is needed in reoperative/complicated patients, 1) MIBI appears to be the most sensitive and specific study, and 2) the MIBI scan should be the initial study in any situation in which preoperative localization is needed. Ultrasound can be useful for patients with significant comorbidities who have not been previously explored. CT or MRI should then be used if further evaluation is needed. If the use of these noninvasive modalities does not produce positive gland localization, selective venous sampling should be utilized as the definitive procedure.

Adenoma↗
PubMed1996

Marked reduction in long-term cardiac deaths with aspirin after a coronary event. Multicenter Myocardial Ischemia Research Group.

OBJECTIVES: We sought to assess the role of aspirin in a precisely defined cohort with coronary disease receiving current therapy. BACKGROUND: Prior results suggest that aspirin modestly decreases cardiac mortality in patients with coronary disease. However, these findings reflect heterogeneous study conditions and earlier management strategies. METHODS: We utilized findings from the Multicenter Study of Myocardial Ischemia, which enrolled 936 subjects 1 to 6 months after an acute myocardial infarction (n = 651 [70%]) or unstable angina (n = 285 [30%]). The follow-up period averaged 23 months, with treatment determined by referring physicians. RESULTS: At enrollment, 751 patients (80%) took aspirin regularly, usually 250 to 325 mg/day. Before enrollment, 291 patients (31%) had thrombolysis, and 352 (38%) had coronary angioplasty. During follow-up, cardiac death occurred in 22 patients, all-cause mortality in 31 and cardiac death or nonfatal myocardial infarction in 70. Each of these outcomes was significantly less frequent among aspirin users. Cardiac death rate was markedly reduced: 1.6% for aspirin users and 5.4% for nonusers (p = 0.005). These differences were not explained by imbalances in predictors of postinfarction risk or therapy other than aspirin (Cox hazard ratio 0.37, p = 0.023). They persisted at least 2 years after enrollment. The difference in mortality rate was particularly prominent after thrombolysis: 0.9% for aspirin users and 8.8% for nonusers (p = 0.004). CONCLUSIONS: Reduction in cardiac deaths among aspirin users is substantially greater than that reported previously. Although derived secondarily, our findings suggest that current practice leads to situations in which aspirin exerts a long-term, life-protecting action, particularly after thrombolysis.

Aspirin↗
PubMed1996

Biotechnology at low Reynolds numbers.

The shrinking of liquid handling systems to the micron and submicron size range entails moving into the area of small Reynolds numbers. The fluid dynamics in this regime are very different from the macroscale. We present an intuitive explanation of how the different physics of small Reynolds numbers flow, along with microscopic sizes, can influence device design, and give examples from our own work using fluid flow in microfabricated devices designed for biological processing.

Biotechnology↗
PubMed1996

The role of high technology in maintaining esthetic restorations.

Computer technology has revolutionized the way the world does business, allowing us to work faster, smarter, and more efficiently than ever before. Within dentistry, that translates to x-rays that use significantly smaller amounts of ionizing radiation, automated periodontal charting and storage devices, and imaging systems. Perhaps the greatest bottom-line benefit, especially in esthetic dentistry, is that these state-of-the-art developments enable dentists and hygienists to more effectively communicate with patients. The future of any restoration is based on the patient's motivation and ability to maintain an efficient oral hygiene routine. Esthetic restorations demand more vigorous home care programs to maximize their esthetic and functional life expectancy. With computerized images on screen, patients can better visualize the treatment that has been done and come to a realization that the restoration's success rests squarely on their shoulders.

Computer Graphics↗
PubMed1995

Prognosis after hospitalization for acute myocardial infarction not accompanied by typical ischemic chest pain. The Multicenter Diltiazem Postinfarction Trial Research Group.

PURPOSE: Although ischemic-type chest pain generally identifies acute myocardial infarction (AMI), some patients are hospitalized for AMI without this symptom. Long-term mortality and morbidity after AMI presenting with alternative warning symptoms have not been examined previously. We therefore assessed the prognostic implications of the absence of typical chest pain as well as other recognized risk predictors in patients hospitalized with AMI. PATIENTS AND METHODS: Data were obtained during the Multicenter Diltiazem Postinfarction Trial. Pain status and other baseline characteristics were determined prospectively by study coordinators according to simple, prespecified criteria. Patients were then examined every 3 to 4 months until trial completion. We applied chi-square methods, life-table analysis, and multivariate analysis to assess the strength and independence of prognostic power associated with each baseline variable. RESULTS: Of 2,464 patients enrolled 3 to 15 days after enzyme-documented AMI, 115 patients lacked typical ischemic-type chest in on presentation (the "nonpainful" group). After 25 months' mean follow-up, cardiac mortality was 20% for nonpainful patients and 10% for 2,349 patients with typical pain (the "painful" group), P < 0.001. Similar increments were seen in total deaths (27% nonpainful versus 13% painful, P < 0.001) and cardiac events, namely, cardiac death or nonfatal reinfarction (24% nonpainful versus 17% painful, P = 0.001). Late congestive heart failure was more frequent (17% nonpainful versus 7% painful, P < 0.001), but unstable angina was less (6% nonpainful versus 16% painful, P = 0.005). At outset, nonpainful patients had more left ventricular dysfunction and diabetes mellitus. However, nonpainful AMI predicted worse outcome even when these problems were absent. Logistic regression confirmed greater cardiac death risk in the nonpainful group (hazard ratio = 2.05) and showed that predictive power of nonpainful status was independent of baseline ejection fraction, Holter data, concomitant diabetes mellitus, and other covariates. CONCLUSIONS: Patients hospitalized with nonpainful AMI are much more likely to experience late cardiac death or congestive heart failure than are patients with painful AMI. In part, this probably reflects more ventricular damage with alternative warning symptoms such as dyspnea. However, our data suggest that defective perception of warning pain also provides a long-term risk to life that is independent of previously known predictors of poor outcome.

Adult↗
PubMed1995

Using air-abrasive technology to diagnose and restore pit and fissure caries.

National Institute of Dental Research surveys indicate that the incidence of pit and fissure caries constitutes a higher proportion of the total caries incidence among U.S. teens and children than in the past. Air-abrasive technology may provide a more conservative alternative in the diagnosis and treatment of pit and fissure caries than traditional techniques using handpieces. The authors review characteristics of pit and fissure lesions and discuss methods for diagnosing and treating these lesions using air-abrasive technology.

Air Pressure↗
PubMed1995

Effects of an acute increase in epinephrine and cortisol on carbohydrate metabolism during insulin deficiency.

This study was undertaken to investigate the effects of an acute increase in the plasma epinephrine level, with or without an accompanying increase in the plasma cortisol level, during selective insulin deficiency on glycogenolysis and gluconeogenesis in conscious overnight-fasted dogs. Experiments consisted of an 80-min tracer and dye equilibration period, a 40-min basal period, and a 180-min experimental period. In all protocols, selective insulin deficiency was created during the experimental period by infusing somatostatin peripherally (0.8 micrograms.kg-1.min-1) with basal replacement of glucagon intraportally (0.65 ng.kg-1.min-1). In EPI+SAL (n = 6), an additional infusion of epinephrine (0.04 micrograms.kg-1.min-1) was infused during the experimental period along with saline. In EPI+CORT (n = 6), hydrocortisone (3.0 microgram.kg-1.min-1) was infused in addition to epinephrine during the experimental period. In SAL+CORT (n = 5), hydrocortisone was infused during the experimental period. In SALINE (n = 5), neither epinephrine nor cortisol was infused. [3-3H]glucose, [U-14C]alanine, and indocyanine green dye were used to assess glucose production (rate of appearance [Ra]) and gluconeogenesis using tracer and arteriovenous difference techniques. During selective insulin deficiency in SALINE, the arterial plasma glucose level increased from 6.0 +/- 0.1 to 15.8 +/- 1.1 mmol/l; Ra increased from 14.7 +/- 0.7 to 24.9 +/- 1.7 mumol.kg-1.min-1. Gluconeogenic efficiency and the conversion of alanine and lactate to glucose increased to 300 +/- 55 and 355 +/- 67% of basal. In EPI+SAL and EPI+CORT, plasma glucose increased from 6.2 +/- 0.1 to 19.8 +/- 0.9 mmol/l and from 6.3 +/- 0.1 to 19.5 +/- 0.9 mmol/l. In EPI+SAL and EPI+CORT, Ra increased from 16.5 +/- 1.1 to 29.3 +/- 3.2 mumol.kg-1.min-1 and from 15.4 +/- 1.3 to 28.3 +/- 2.5 mumol.kg-1.min-1. The rise in gluconeogenic efficiency was similar to the rise that occurred in SALINE, but gluconeogenic conversion increased 17-fold in each of the two epinephrine groups. During the epinephrine infusion, gluconeogenesis accounted for a maximum of 55% of total glucose production as opposed to 31% during insulin deficiency alone. An increase in cortisol alone during insulin deficiency (SAL+CORT) had no effect on glucose level, glucose production, or gluconeogenesis. These results suggest that small increases in the plasma epinephrine level during insulin deficiency can significantly worsen the resulting hyperglycemia through stimulation of both glycogenolysis and gluconeogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Alanine↗
PubMed1994

Exaggerated epinephrine response to hypoglycemia in a physically fit, well-controlled IDDM subject.

Metabolically well controlled insulin-dependent diabetic subjects (IDDM) have deficient autonomic adrenomedullary responses to hypoglycemia. This defect, coupled with the characteristic deficient glucagon response to hypoglycemia, predisposes well-controlled IDDM subjects to an increased incidence of severe hypoglycemic episodes. In this report we describe a physically trained subject with long-duration IDDM (9 years) who was rigorously well-controlled (normal HBA1c), yet had exaggerated epinephrine responses to hypoglycemia compared with normal controls. Steady state epinephrine levels during a low-dose insulin (9 pM/kg/min) hypoglycemic clamp (2.9 +/- 0.1 mM) were approximately 2-fold higher compared with normal controls (10.6 vs. 5.5 +/- 0.7 nM). Epinephrine levels during a high-dose insulin (30 pM/kg/min) hypoglycemic clamp (2.8 +/- 0.1 mM) were also increased compared with normal controls (13.1 vs. 8.8 +/- 0.6 nM). We conclude that physical training in this metabolically well-controlled IDDM subject was associated with an augmented autonomic adrenomedullary response to hypoglycemia.

3-Hydroxybutyric Acid↗
PubMed1994

The effects of acute hypercortisolemia on beta-hydroxybutyrate and glycerol metabolism during insulin deficiency.

The present study was undertaken to determine whether an acute physiologic rise in plasma cortisol during selective insulin deficiency would have significant effects on glycerol and beta-hydroxybutyrate metabolism in conscious overnight-fasted dogs. Each experiment consisted of a two hour dye equilibration period, a 40 minute basal period, and a 3 hour experimental period. A continuous infusion of indocyanine green dye for blood flow estimation was initiated at the start of the equilibration period and continued throughout the experiment. In both of two protocols selective insulin deficiency was created during the experimental period by infusing somatostatin peripherally (0.8 microgram/kg-min) with basal replacement of glucagon intraportally (0.65 ng/kg-min). In the test protocol (CORTISOL, n = 5), 3.0 micrograms/kg-min of hydrocortisone was infused during the experimental period. In the control protocol (SALINE, n = 5), saline was infused. Net hepatic balances were determined using the (A-V) difference technique. During selective insulin deficiency alone (SALINE), the arterial blood glycerol level increased from 81 +/- 19 to 140 +/- 11 microM (p < 0.01) and net hepatic glycerol uptake (NHGlyU) tended to increase from 2.3 +/- 0.3 to 3.3 +/- 0.6 mumol/kg-min (0.05 < 0.1). The arterial plasma free fatty acid (FFA) level remained unchanged at 1041 +/- 35 microM. The arterial beta-hydroxybutyrate (BHOB) level increased slightly from 21 +/- 4 to 29 +/- 5 microM while net hepatic beta-hydroxybutyrate production (NHBP) remained unchanged (1.0 +/- 0.2 mumol/kg-min). During acute hypercortisolemia with selective insulin deficiency (CORTISOL), similar changes occurred in the arterial blood glycerol level and net hepatic glycerol uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1994

Effects of chronic hypercortisolemia on carbohydrate metabolism during insulin deficiency.

This study was undertaken to further investigate the effect of acute selective insulin deficiency on glycogenolysis and gluconeogenesis occurring during chronic physiological hypercortisolemia in conscious overnight fasted dogs. After an 80-min tracer and dye equilibration period and a 40-min basal period, selective insulin deficiency was created during the 180-min experimental period by infusing somatostatin peripherally (0.8 micrograms.kg-1.min-1) with basal replacement of glucagon intraportally (0.65 ng.kg-1.min-1). In the cortisol group (n = 5), a continuous infusion of hydrocortisone (3.5 micrograms.kg-1.min-1) was begun 5 days before the experiment. In the saline group (n = 5), there was no infusion of cortisol. [3-3H]glucose, [U-14C]alanine, and indocyanine green dye were used to assess glucose production and gluconeogenesis using tracer and arteriovenous difference techniques. During selective insulin deficiency in the saline group, the arterial plasma glucose level (Glc) increased from 109 +/- 2 to 285 +/- 19 mg/dl; glucose production increased from 2.7 +/- 0.2 to 4.5 +/- 0.3 mg.kg-1.min-1. Gluconeogenic efficiency and conversion of alanine to glucose (Conv) increased by 300 +/- 55 and 356 +/- 67%. During selective insulin deficiency in the cortisol group, Glc increased from 117 +/- 3 to 373 +/- 50 mg/dl; glucose production increased from 3.3 +/- 0.5 to 6.9 +/- 0.7 mg.kg-1.min-1. Gluconeogenic efficiency and Conv increased by 268 +/- 41 and 393 +/- 75%, respectively. The maximal glycogenolytic rate increased significantly more in the cortisol group than in the saline group, accounting for the difference in glucose production. These results suggest that, even during chronic hypercortisolemia, acute insulin deficiency has more pronounced effects on glycogenolysis than gluconeogenesis.

Alanine↗
PubMed1994

Air-abrasive technology: its new role in restorative dentistry.

Air-abrasive technology has re-emerged in dentistry. The history, characteristics and clinical applications of this approach are reviewed, including advantages and limitations for the removal of stain, enamel, dentin and decay. Air-abrasive technology may be especially suited for use in bonded restorations.

Air Pressure↗