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Biomedical subjects

M J Feldman

Publications and source records attributed to M J Feldman.

At least 19 recordsLinked to original sources
PubMed2001

Selective alpha(v)beta(3)-receptor blockade reduces macrophage infiltration and restenosis after balloon angioplasty in the atherosclerotic rabbit.

BACKGROUND: alpha(v)beta(3)-Integrin receptors are upregulated in atherosclerotic arteries and play a key role in smooth muscle cell and possibly inflammatory cell migration. We hypothesized that after balloon angioplasty (BA) of atherosclerotic arteries, selective inhibition of the alpha(v)beta(3)-receptor by XT199, a small-molecule, non-peptide-selective alpha(v)beta(3)-receptor antagonist, would reduce restenosis. METHODS AND RESULTS: After induction of focal atherosclerosis, rabbits underwent femoral BA and received XT199 (2.5 mg/kg IV bolus plus 2.5 mg. kg(-1). d(-1) IV; n=19) or vehicle (n=20) for 14 days. At 28 days after BA, the XT199 group had a larger lumen (0.75+/-0.26 versus 0.57+/-0.20 mm(2), P=0.03) and a smaller neointimal area (0.49+/-0.18 versus 0.68+/-0.25 mm(2), P=0.01) than the vehicle group. Angiographic analysis confirmed a 30% to 40% reduction in restenosis. Arteries harvested at 28 days after BA did not show a reduction in intima plus media smooth muscle cell content but did show a 50% reduction in macrophage cell density in the XT199 group (716+/-452 versus 1458+/-989 cells/mm(2), P<0.006). Neovessel density at 28 days was also reduced (23+/-42 versus 58+/-46 vessel cross sections/mm(2), P<0.02). Early after BA (ie, 3 to 7 days), there was a decrease in intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression, indicative of a reduction in vascular cell activation. CONCLUSIONS: Selective alpha(v)beta(3)-receptor blockade for 14 days after BA in the focally atherosclerotic rabbit significantly reduced restenosis and limited macrophage infiltration and neovascularization in the vessel wall.

Actins↗
PubMed2001

Role of substance P and calcitonin gene-related peptide in acid-induced augmentation of opossum esophageal blood flow.

Increased esophageal blood flow may protect against damaging refluxed gastric juices. We have shown that mast cells, histamine, and nitric oxide increase esophageal blood flow in the opossum during acid perfusion. This study examined the roles of substance P and calcitonin gene-related peptide on acid-induced hyperemia and whether the effects of substance P are mediated by mast cells. The opossum distal esophagus was perfused with saline, acid, or capsaicin while blood flow and histamine release were determined. Neuropeptides and neurokinin antagonists were administered parenterally. Only acid or calcitonin gene-related peptide (not substance P or capsaicin) significantly increased blood flow, which was prevented by neurokinin or calcitonin-gene-related peptide antagonists. Acid, substance P, and capsaicin all increased histamine release. Pretreatment with neurokinin antagonists did not affect acid-induced histamine release. We conclude that calcitonin-gene-related peptide is an important mediator of acid-induced esophageal hyperemia, while substance P plays an indirect role.

Animals↗
PubMed2000

Sexual attitudes and associated psychiatric features among youths in a community sample.

OBJECTIVE: Using an epidemiological sample of adolescents, this study examined associations between the acceptability of potential sex partners and psychiatric status. METHOD: Subjects aged 14 to 17 years (N = 161) from the Columbia site of the National Institute of Mental Health (NIMH) Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) Study were grouped according to their responses about the acceptability of youths their age having sex with partners of (1) the opposite sex, (2) neither sex, and (3) either sex. Youths endorsing either sex were compared with youths endorsing the other two types of partners according to psychiatric indicators obtained from the Diagnostic Interview Schedule for Children Version 2.3. RESULTS: Higher-than-expected proportions of male and female youths endorsed sex partners of either sex as potentially acceptable for peers. Youths who did so abused substances and used mental health services more than peers but did not differ in rates of suicidal ideation or attempts. Males endorsing either sex also had higher rates of mood disorders and, compared with males endorsing only the opposite sex, a higher intelligence level. CONCLUSIONS: Attitudes about the potential acceptability of sex partners for peers are associated with psychiatric morbidity and mental health service use in the respondent as well as with intelligence level in males. Youths who endorsed potential sex partners of either sex, especially males, appear to be at higher risk for multiple psychiatric problems.

Adolescent↗
PubMed1998

DXplain on the Internet.

DXplain, a computer-based medical education, reference and decision support system has been used by thousands of physicians and medical students on stand-alone systems and over communications networks. For the past two years, we have made DXplain available over the Internet in order to provide DXplain's knowledge and analytical capabilities as a resource to other applications within Massachusetts General Hospital (MGH) and at outside institutions. We describe and provide the user experience with two different protocols through which users can access DXplain through the World Wide Web (WWW). The first allows the user to have direct interaction with all the functionality of DXplain where the MGH server controls the interaction and the mode of presentation. In the second mode, the MGH server provides the DXplain functionality as a series of services, which can be called independently by the user application program.

Artificial Intelligence↗
PubMed1997

Ethical aspects of competence for sexual relationships: a case of adult sibling incest.

A case of adult sibling incest serves as the occasion to review relevant literature and discuss issues related to competence to consent to sexual relations between adults. The case was presented at ethics rounds at the Massachusetts Mental Health Center (Boston, MA), and the resulting discussion is analyzed as to the decision making with which the treatment team is faced. The relationships among competence and competence assessment, autonomy, morality, and countertransference issues are also considered in this provocative case.

Adult↗
PubMed1997

Esophagitis as the outcome of progressive failures of the defensive repertoire.

Pre-epithelial defences include the coordinated actions of the lower esophageal sphincter and the esophageal muscles, which minimize reflux of gastric contents and promote clearance of refluxed material. The esophageal epithelium also possesses innate resistance to luminal damaging agents and may be protected luminally by a mucus or 'mucus bicarbonate' barrier and possibly a layer of hydrophobic surfactants. These components are derived from submucosal glands located in the submucosal connective tissue and from salivary secretions that may bind to the esophageal surface. Epithelial defences include the glycocalyx, permeability properties of the epithelial cell plasma membrane, junctional barriers to proton permeation through the paracellular pathway and ion transport processes for regulation of intracellular pH. Subepithelial defences involve mainly regulation of blood supply via responses of nerves, mast cells and blood vessels to influxing protons. Although the epithelium can withstand prolonged exposure to physiologically relevant concentrations of acid, the presence of pepsin or bile salts may overcome the permeability barrier, which probably resides in the superficial layers of epithelial cells. Focal destruction of these cells allows access of luminal acid and other aggressive agents to the vulnerable basolateral cell membranes and to the submucosa. The result is lesion production, although an efflux of alkaline plasma may protect the underlying submucosa and allow healing. Salivary-derived epidermal growth factor (EGF) is present in the luminal fluid, and lesion development may also provide access of EGF to receptors within the epithelium and in the underlying vasculature. Accelerated cell proliferation would then contribute to healing. Inflammation and healing should also be viewed as defensive responses, as can the development of Barrett's esophagus, in which the stratified squamous epithelium is replaced by a potentially acid-resistant columnar epithelium. Chronic inflammation and esophagitis only result when this multilayered set of defences is overcome. The challenge for research is to identify those components of the defensive repertoire that are defective in individuals who suffer from chronic esophagitis.

Animals↗
PubMed1996

Mast cells mediate acid-induced augmentation of opossum esophageal blood flow via histamine and nitric oxide.

BACKGROUND & AIMS: Increased esophageal blood flow during reflux episodes may play an important role in mucosal resistance to injury, although the mechanism remains unclear. Decreased stainable mast cells and increased luminal histamine release during acid exposure has been previously documented. Therefore, the role of mast cells, nerves, histamine, and nitric oxide in mediating increased blood flow during acid challenge of the distal esophagus was investigated. METHODS: The effects of the mast cell stabilizers disodium cromoglycate and doxantrazole, the neurotoxin tetrodotoxin, the histamine H1 receptor antagonist promethazine, and the NO synthase inhibitor N omega-nitro-L-arginine methyl ester were examined by monitoring opossum esophageal histamine release and blood flow during perfusion with 100 mmol/L HCl. RESULTS: Luminal acid challenge significantly increased both histamine release and blood flow (P < 0.05). Disodium cromoglycate, promethazine, and N omega-nitro-L-arginine methyl ester attenuated the increase in blood flow to basal (saline-perfused) levels. Tetrodotoxin did not prevent an acute increase in blood flow that rapidly returned to baseline, likely from the ensuing hypotension. CONCLUSIONS: These findings provide evidence that mast cell-derived histamine, acting through an NO-dependent mechanism, plays a central role in the response of the esophageal microcirculation to luminal acid.

Animals↗
PubMed1995

Medical informatics and pediatrics. Decision-support systems.

Decision support is an important area of medical informatics research. Computer-based decision-support tools facilitate diagnosis and the management of patients after a diagnosis has been established. Diagnostic decision-support tools, such as Meditel, Quick Medical Reference, DXplain, Iliad, and PEM-DXP are potentially useful "expert systems." Other management-support tools, such as systems that use clinical practice guidelines to create reminders and alerts, also have been developed and evaluated. We do the following: (1) to provide an overview of diagnostic and management decision-support systems; (2) explore the background of and motivation behind these systems; (3) survey the uses of decision-support technology in office-based and inpatient pediatric practices; and (4) discuss the virtues and problems associated with some of these tools, and current controversies and future goals for computer-based decision support.

Attitude to Computers↗
PubMed1994

Local prophylactic benadryl injections in an attempt to reduce postinstrumental pain.

This study was done to determine the clinical efficacy of a 15-mg diphenhydremine hydrochloride (Benadryl) local injection as a prophylactic treatment in the prevention of pain resulting from initial instrumentation of necrotic teeth. A double-blind study comprised of 37 subjects, each with one nonvital maxillary tooth, was completed in which patients were divided into two equal groups. The experimental group received a local anesthetic of 3% Carbocaine, followed by an additional injection of the antihistamine. The control group received the local anesthetic and an equivalent quantity of sterile saline. Patients recorded their pain levels at various time intervals: preoperatively, immediately postoperatively, and at 3, 7, 12, and 24 h postoperatively. Graphic analysis using a Quatro-Pro spread sheet program showed that there were no significant differences between the groups pain scores. However, there was a correlation between pain and time elapsed after procedure. In both groups, postoperative pain appeared to increase from 3 to 7 h and decrease from 7 to 24 h.

Adult↗
PubMed1991

An approach to evaluating the accuracy of DXplain.

DXplain is a computer-based decision support system which generates a differential diagnosis (ddx) from a given list of clinical manifestations (Barnett et al., J. Am. Med. Assoc. 258 (1987) 67-74). An approach was developed to evaluate the accuracy of the ddx's produced by DXplain. The first step involves the collection of 65 benchmark cases drawn from a variety of sources and authors. Despite their diverse origins, the cases share in common that they are all clinical cases upon which a consulting physician might be asked to produce a differential. This helps to ensure that the evaluation of the system will be done in an environment similar to that in which the system is actually used. In the second step, all cases are reviewed by five board-certified physicians (experts) as well as DXplain. For each case, the evaluators (experts and DXplain) produce a rank-ordered ddx list along with an indication of how strongly each disease was felt to be supported by the case findings. A scoring technique was devised which rewards concordance with the gold standard: a consensus of the evaluators' ddx lists. Each evaluator receives a score which is proportional to the degree of agreement achieved with the consensus on the ddx submitted. Preliminary results on a trial evaluation of 46 cases indicate that DXplain, on average, did well in agreeing with the consensus. Agreement was achieved both in regard to the specific diagnoses listed in the ddx and the degree to which the diseases were felt to be supported by the case findings. A discussion of some important issues in the evaluation of knowledge-based systems is undertaken.

Algorithms↗
PubMed1991

Enhancing subject recruitment for nursing research.

Nursing research most often requires human subjects. Consequently, an essential component in planning and conducting research entails recruitment of subjects who knowledgeably consent to participate. A well-established theoretical base exists regarding sampling techniques and procedures for research methods. The operationalization of the theory into practical terms may be of interest to the clinical nurse specialist (CNS) who frequently assumes a leadership role to both conduct nursing research in practice settings and to advise other nurses interested in conducting research. The recruitment efforts in four different nursing studies were compared and contrasted in an effort to determine effective and efficient approaches to this issue. Sample populations included nurse practitioners, patients, nurse aides, and nurse educators. Methods of recruitment included direct contact, mail, and telephone contact. While the settings, purposes, and designs of the studies varied, some common elements regarding subject recruitment were suggested. The recruitment methods have been described, along with the implication in terms of practical application for conduct of nursing research by CNSs.

Communication↗
PubMed1991

The sensitivity of medical diagnostic decision-support knowledge bases in delineating appropriate terms to document in the medical record.

A pertinent, legible and complete medical record facilitates good patient care. The recording of the symptoms, signs and lab findings which are relevant to a patient's condition contributes importantly to the medical record. The consideration and documentation of other disease states known to be related to the patient's primary illness provide further enhancement. We propose that developing sets of disease-specific core elements which a physician may want to document in the medical record can have many benefits. We hypothesize that for a given disease, terms with high importance (TI) and frequency (TF) in the DX-plain, QMR and Iliad knowledge bases (KBs) are terms which are used commonly in the medical record, and may be, in fact, terms which physicians would find useful to document. A study was undertaken to validate ten such sets of disease-specific core elements. For each of ten prevalent diseases, high TI and TF terms from the three KBs mentioned were pooled to derive the set of core elements. For each disease, all patient records (range 385 to 16,972) from a computerized ambulatory medical record database were searched to document the actual use by physicians of each of these core elements. A significant percentage (range 50 to 86%) of each set of core elements was confirmed as being used by the physicians. In addition, all medical concepts from a selection of full text records were identified, and an average of 65% of the concepts were found to be core elements.(ABSTRACT TRUNCATED AT 250 WORDS)

Artificial Intelligence↗
PubMed1991

An information synthesis to evaluate nurse practitioner effectiveness.

An information synthesis was conducted at the Department of Veterans Affairs Medical Center, Buffalo, New York, to determine the extent to which nurse practitioner (NP) effectiveness had been established in the existing literature. Three hundred fifty documents were reviewed by experts and 102 documents were deleted from the analysis phase. Fifty-six documents referred to as the Better Studies contained the most relevant and valid findings and were compared with a model developed to represent NP effectiveness. NPs were found to effectively provide a wide range of health care services. They can function as independent health care providers as well as collaborative members of the health care team. NPs have been found to have a positive influence on patient-related outcomes. There should be continued use and support of NPs in health care delivery systems. Recommendations for additional study are presented.

Delivery of Health Care↗
PubMed1991

Increasing productivity by developing alliances.

Collaborative alliances among nurses may provide a feasible and satisfying opportunity to increase the productivity of nurses. Inherent in successful alliances are the development of trust, compatibility, commitment, and mutality of benefits. The development of collaborative relationships among clinical research nurses, a research methodologist, and a nurse educator resulted in several federally funded grants and publications. The alliances described here cross disciplines and institutions and demonstrate the enhanced productivity that can result from such efforts.

Education, Nursing↗