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Biomedical subjects

A Stern

Publications and source records attributed to A Stern.

At least 19 recordsLinked to original sources
PubMed1999

Protruding aortic arch atheromas: risk of stroke during heart surgery with and without aortic arch endarterectomy.

BACKGROUND: Stroke occurs in 1% to 7% of heart surgery. Aortic arch atherosclerosis is a risk factor for intraoperative stroke, and endarterectomy has been proposed to prevent stroke during heart surgery in patients with arch atheromas. METHODS AND RESULTS: Intraoperative transesophageal echocardiography was performed in 3404 patients undergoing heart surgery between 1990 and 1996. Use of transesophageal echocardiography was unselected and based on equipment availability. Aortic arch atheromas (>/=5 mm, or mobile) were seen in 268 (8%) patients. They were evaluated for intraoperative stroke (confirmed by a neurologist and cerebral infarction on computed tomography or magnetic resonance imaging). Arch endarterectomy was performed in 43 patients as an adjunct to their cardiac procedure in an attempt to prevent intraoperative stroke. The intraoperative stroke rate in all 268 patients with atheromas was high (15.3%). On univariate analysis, age, previous stroke, and arch endarterectomy were significantly associated with intraoperative stroke. On multivariate analysis, age (odds ratio 3.9, P =.01) and arch endarterectomy (odds ratio 3.6, P =.001) were independently predictive of intraoperative stroke. Mortality rate in all 268 patients was high (14.9%). These patients with atheromas also had a long recovery room, intensive care unit, and total hospital length of stay (48 days). CONCLUSIONS: Patients with protruding aortic arch atheromas are at high risk for intraoperative stroke, significant and multiple morbidity, prolonged hospital stay, and death resulting from heart surgery. Aortic arch endarterectomy is strongly associated with intraoperative stroke; its use should be carefully considered in light of these results.

Aged↗
PubMed1999

Twenty-four-hour access to emergency care for children in managed care.

Children's medical emergencies occur around the clock. In years past, the emergency department, open 24 hours a day, was a familiar site for treating these emergencies. However, in today's health care environment, the scenario can be more confusing. As many families move from a fee-for-service system into a managed care organization (MCO), they may be unclear about what they should do in an emergency involving their child. MCOs want to provide appropriate care, and at the same time, operate within a system designed to contain costs through the establishment of effective health care delivery systems. Providers of emergency services, including specialists in pediatric medicine and emergency medical services responders, also must contend with a different set of problems, including administrative entanglements and concerns about reimbursement for their services. This article continues the white paper series by the Emergency Medical Services for Children Managed Care Task Force.

Adolescent↗
PubMed1999

The built environment as a component of quality care: understanding and including the patient's perspective.

BACKGROUND: Although there has been little systematic assessment of how the built environment of health care facilities affects the quality of care, the built environment is a major element of structure of care--one of three facets of quality. Yet in contrast to the growing trend of using consumer perceptions of both processes and outcomes of care in QI activities, quality assessments of the structure of care do not currently rely on patient feedback. PURPOSE OF PROJECT: During the initial phase of a multiphase project, nine focus groups were conducted in 1997 to identify the salient dimensions of experience from the patient's perspective. The content of these focus groups guided the development of assessment tools in the second phase of the project, which began in February 1998. FINDINGS: Participants in three focus groups that were held in each of three settings--ambulatory care, acute care, and long term care--described in detail a variety of reactions to the built environment. Analysis revealed eight consistent themes in what patients and family member consumers look for in the built environment of health care. In all three settings, they want an environment, for example, that facilitates a connection to staff and caregivers, is conducive to a sense of well-being, and facilitates a connection to the outside world. DISCUSSION: Data derived from the focus group research has guided the development of quantitative survey and assessment tools. For each setting, patient-centered checklists and questionnaires are designed to help institutions set priorities for the improvement of facility design from the patient's perspective.

Facility Design and Construction↗
PubMed1999

A comparative study of the postoperative allogeneic blood-sparing effect of tranexamic acid versus acute normovolemic hemodilution after total knee replacement.

UNLABELLED: Both acute normovolemic hemodilution (NVHD) and tranexamic acid (TA) are potentially useful allogeneic blood conservation strategies after total knee replacement. However, the relative efficacy of these blood-sparing techniques is unknown. Therefore, to compare the postoperative allogeneic blood sparing of NVHD and TA after total knee replacement, we investigated 40 patients in a prospective, single-blinded study protocol. In Group TA, 30 min before deflating the limb tourniquet, an IV infusion of TA, 15 mg/kg, was administered over a 30-min period. Thereafter, a constant IV infusion of 10 mg x kg(-1) x hr(-1) was administered until 12 h after deflation of the limb tourniquet. Before induction of anesthesia, NVHD patients were bled to a target hematocrit of approximately 28%. Intravascular blood volume was maintained with lactated Ringer's solution. All autologous blood was transfused at the end of the surgery. Postoperatively, hematocrit was measured daily. In all cases, a hematocrit <27% was the postoperative transfusion trigger. Before discharge, deep vein thrombosis was excluded by Echo Doppler. Three months after surgery, the incidence of delayed thromboembolic events was assessed. The two groups were demographically comparable. In Group NVHD, 843 mL+/-289 of autologous blood was removed. Despite autologous blood transfusion, during the early postoperative period and until the third postoperative day, the NVHD group had significantly (P < 0.01) lower mean hematocrits when compared with the TA group. Thereafter, because of a significantly (P < 0.0008) greater allogeneic blood requirement in the NVHD group, no statistically significant difference in mean hematocrit recordings was noted among the groups. Blood accumulation in the surgical drain 12 h postoperatively, was significantly (P < 0.0008) higher in the NVHD group (259 mL+/-156) when compared with the TA group (110 mL+/-62). Significantly (P < 0.0008) more allogeneic blood was transfused in the NVHD group (19 U/13 patients) when compared with the TA group (2 U/2 patients). No abnormal Echo Doppler studies were reported. During the 3-mo follow-up period, a deep vein thrombosis and pulmonary embolus were documented in one patient in the NVHD group. We conclude that perioperative hemodynamic stability and allogeneic blood sparing is superior after tranexamic acid administration when compared with normovolemic hemodilution. IMPLICATIONS: For total knee replacement, when compared with normovolemic hemodilution, tranexamic acid administration is associated with superior perioperative hemodynamic stability and allogeneic blood sparing.

Aged↗
PubMed1999

Development of a brief questionnaire for screening for multiple chemical sensitivity syndrome.

The objective of this study was to identify a parsimonious set of questions that has high sensitivity and specificity for screening for individuals with multiple chemical sensitivity (MCS) syndrome. We performed a cross-sectional survey using a case-control design. Subjects were derived from patients seen at an academically based Occupational and Environmental Medicine Clinic. Cases consisted of patients who fulfilled the Cullen definition for MCS. Controls were patients who had diagnoses excluding MCS and asthma and who were matched to cases by age and sex. Cases and controls filled out a screening questionnaire that, among things, elicited responses as to whether and how subjects reacted to 122 different types of environmental exposures. Data from 44 pairs of cases and controls were available for analysis. The average age of cases was 50.2 years, and 91% was female. Among cases, the most common exposure that was purported to incite MCS was 'indoor air quality contaminants (unspecified)' (59%), followed by solvents (27.3%). After randomly excluding five cases and controls, a stepwise selection procedure for two-group discriminant analysis revealed that the main contributors to the discrimination of the remaining cases and controls were self-reported reactions to copy machine emissions, marking pens, aftershave, window cleaner, nylon fabric, pine-scented products, and rayon material. When a positive response to these factors was used as the sole method for discriminating cases from controls, only one of 41 cases was misclassified as a control while none of the controls was misclassified as a case. When the same method was applied to the five excluded cases and five excluded controls, only one of the five cases was misclassified while none of the five controls was misclassified as a case. Among patients with MCS defined by the Cullen criteria in this clinical setting, having a reaction to these seven common potential exposures comprised a parsimonious set of factors that discriminated between MCS patients and age- and sex-matched normal controls. These questions may have utility in screening for individuals with MCS in general population survey studies.

Air Pollution, Indoor↗
PubMed1998

Impaired production of nitric oxide, superoxide, and hydrogen peroxide in glucose 6-phosphate-dehydrogenase-deficient granulocytes.

Since the generation of superoxide and hydrogen peroxide by NADPH oxidase and nitric oxide (NO) by NO synthase (NOS) in granulocytes is NADPH-dependent, we investigated the production of NO, superoxide and H2O2 in glucose 6-phosphate dehydrogenase (G6PD)-deficient human granulocytes. Our results showed that upon stimulation with either 5 microg/ml of lipopolysaccharide (LPS) or 10 microM of phorbol 12-myristate 13-acetate (PMA), the production of nitrite in normal granulocytes was elevated, 252 +/- 135% and 239 +/- 72%, respectively, compared to the resting stage. In contrast, G6PD-deficient granulocytes did not produce more nitrite upon stimulation with either LPS or PMA compared to the resting stage. Western blot analysis indicated a normal expression pattern of inducible NOS in G6PD-deficient granulocytes. In addition, the production of H2O2 and superoxide was also significantly impaired in G6PD-deficient granulocytes compared to control cells. These data demonstrate that G6PD deficiency causes an impairment in the production of NO, superoxide and H2O2.

Erythrocytes↗
PubMed1998

Transesophageal echocardiography in a case of cardiac compression: was it therapeutic?

Cardiac compression is a potentially life-threatening complication of heart surgery. This syndrome often has atypical manifestations, challenging our ability to make a rapid diagnosis and to institute emergent, life-saving treatment. We recently evaluated one such patient who showed cardiac compression caused by an unusual paracardiac mass. The addition of transesophageal echocardiography to the usual transthoracic study may have played more than just a diagnostic role in this case.

Aged↗
PubMed1998

International population movements and public health in the Mekong region: an overview of some issues concerning mapping.

Geographical Information Systems (GIS) have many important applications in local, regional and global situation analysis, especially in relation to planning and implementation thereof. The complex issues involved in population movement between neighboring countries offer a good example of the assistance that GIS applications can provide to transborder public health planning. The Greater Mekong Subregion (GMS) involves 6 countries, among which greatly increased population movement is occurring for a variety of reasons. This movement carries with it high risks of disease dispersal and thus presents a major challenge to disease control. This paper addresses the questions of sources, access and presentation of a wide variety of data that is needed by planners to develop more appropriate cooperative approaches to public health management in the GMS, with the main focus on contributions from mapping.

Asia, Southeastern↗
PubMed1997

Alendronate inhibition of protein-tyrosine-phosphatase-meg1.

Alendronate (4-amino-1-hydroxybutylidene-1,1-bisphosphonate) is a potent bisphosphonate that inhibits osteoclastic bone resorption and has proven effective for the treatment of osteoporosis. Its molecular mechanism of action, however, has not been defined precisely. Here we report that alendronate is a potent inhibitor of the protein-tyrosine-phosphatase-meg1 (PTPmeg1). Two substrates were employed in this study: fluorescein diphosphate and the phosphotyrosyl peptide src-pY527. With either substrate, alendronate was a slow binding inhibitor of PTPmeg1. Among the other bisphosphonates studied, alendronate was more potent and selective for PTPmeg1. The hydrolysis of fluorescein diphosphate by PTP epsilon and PTPmeg1 was sensitive to alendronate, with IC50 values of less than 1 microM; PTPsigma, however, under the same conditions, was inhibited by only 50% with 141 microM alendronate. Similarly, with the src-pY527 substrate, alendronate inhibition was also PTP dependent. Alendronate inhibited PTPmeg1 with an IC50 value of 23 microM, PTPsigma with an IC50 value of 2 microM, and did not inhibit PTP epsilon at concentrations up to 1 mM. The alendronate inhibition of these three PTPs and two substrates is consistent with the formation of a ternary complex comprised of enzyme, substrate, and inhibitor. PTP inhibition by hisphosphonates or vanadate was diminished by the metal chelating agent EDTA, or by the reducing agent dithiothreitol, suggesting that a metal ion and the oxidation of a cysteine residue are required for full inhibition. These observations show substrate- and enzyme-specific PTP inhibition by alendronate and support the possibility that a certain PTP(s) may be the molecular target for alendronate action.

Alendronate↗
PubMed1997

Palladium or platinum exacerbates hydroxyl radical mediated DNA damage.

Strand breakage of supercoiled pBR322 DNA by a Fenton system is increased in the presence of palladium or platinum (Pt) ions. Neither Pd nor Pt ions can substitute for iron in the Fenton system. We have obtained several lines of evidence that Pd and Pt ions in the presence of a Fenton system can augment the production of OH., as monitored by a spectrophotometric method quantifying hydroxylated salicylate or by a fluorometric method quantifying catechol production. Furthermore, the promoting effect of both metal ions on OH. production was substantiated by the identification of multiple hydroxylated products of salicylate [2,3-dihydroxybenzoate (A), 2,5-dihydroxybenzoate (B), and catechol (C)] using HPLC. The concentrations of A, B, and C produced in the control were 4.5, 8.0, and 2.0 microM, respectively; whereas, their respective concentrations increased to 23.6, 42.0 and 10.0 microM with the addition of Pd ions. The observed phenomenon was further confirmed by the identification of HO-DMPO spin adducts using ESR spectroscopy. Taken together, our data suggest that the mechanism of Pd or Pt ion-mediated exacerbation of DNA damage by a Fenton system is due to the promotion of OH. production by these metal ions.

DNA Damage↗
PubMed1997

Hemin-induced membrane sulfhydryl oxidation: possible involvement of thiyl radicals.

Sublytic levels (microM) of hemin destabilized RBC membrane as indicated by ghost fragmentation pattern using a laser viscodiffractometer. Furthermore, electron microscopic study shows that 5 microM of hemin induced echinocytic transformation whereas higher hemin concentration (40 microM) induced spherocytic transformation. In addition, hemin oxidized sulfhydryl groups in a dose dependent fashion and Electron Spin Resonance study suggests that such oxidation may involve a thiyl radical. Moreover, sulfhydryl compounds enhanced hemin-induced lipid peroxidation. Desferroxamine could prevent hemin-induced sulfhydryl oxidation as well as hemin-induced decrease in membrane stability. In contrast, vitamin E could effectively prevent hemin-induced lipid peroxidation but could not prevent hemin-mediated membrane destabilization.

Deferoxamine↗