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Biomedical subjects

N Nguyen

Publications and source records attributed to N Nguyen.

At least 127 records · Page 7Linked to original sources
PubMed1990

Myocardial clearance kinetics of technetium-99m-SQ30217: a marker of regional myocardial blood flow.

SQ30217 is a new, technetium-99m-(99mTc) labeled perfusion agent introduced for cardiac imaging. To evaluate the myocardial tracer kinetics, 99mTc-SQ30217, was injected intracoronarily in open-chested dogs under baseline conditions and after administration of intravenous (i.v.) dipyridamole. Myocardial first-pass retention fraction averaged 0.90 +/- 0.04. Clearance of the tracer occurred in a biexponential manner. Sixty-seven percent of retained activity cleared with a half-time of 2.3 +/- 0.6 min, while the residual activity demonstrated slow clearance. The clearance rate of the rapid phase correlated with myocardial blood flow (r = 0.72, p less than 0.001). Myocardial SQ30217 clearance rate following i.v. injection as determined by dynamic imaging with tomography (SPRINT) averaged 21 +/- 4 min and increased to 13 +/- 4 min following dipyridamole. Thus, 99mTc-SQ30217 is a promising flow tracer with high initial myocardial retention and rapid tissue clearance, which allow repeated flow determinations within short time intervals using advanced SPECT technology.

Animals↗
PubMed1989

Slowed saccades in the acquired immunodeficiency syndrome.

We recorded eye movements using infrared oculography in ten patients with the acquired immunodeficiency syndrome (AIDS) and ten control subjects of similar age. Peak saccadic velocity for the AIDS group was significantly lower than that of the control group for both adducting and abducting saccades (P less than .001). Saccadic duration for the AIDS group was significantly greater than that of the controls for both adducting and abducting saccades (P less than .02 for adduction and P less than .01 for abduction). There was no difference in saccadic latencies between the two groups. We add slowed saccades to the ocular motility manifestations of AIDS. Our study indicated that analysis of ocular motility may be of value in providing early detection of neurologic dysfunction, and may also be an important quantitative measure of the responsiveness of patients to different types of potential therapies.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Eskimo plasma constituents, dihomo-gamma-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid inhibit the release of atherogenic mitogens.

Studies in man and laboratory animals suggest that omega 3 polyunsaturated fatty acid constituents of fish oils have antiatherosclerotic properties. We have studied the effects of several such polyunsaturated fatty acids for ability to modify the in vitro release of mitogens from human platelets. Such mitogens may produce the fibro-proliferative component of atherosclerotic plaques. Both 5,8,11,14,17-eicosapentaenoic acid (20:5 omega 3) and 4,7,10,13,16,19-docosahexaenoic acid (22:6 omega 3), major constituents of fish oils, inhibited adenosine diphosphate-induced aggregation of platelets and the accompanying release of mitogens. These effects are dose dependent. Linolenic acid (18:3 omega 3), the biosynthetic precursor of eicosapentaenoic acid, also inhibited platelet aggregation and mitogen release. Eicosapentaenoic acid also inhibited mitogen release from human monocyte-derived macrophages, which, in vivo, are an additional source of mitogens during atherogenesis. Potent inhibition of human platelet aggregation and mitogen release was also seen with dihomo-gamma-linolenic acid (8,11,14-eicosatrienoic acid 20:3 omega 6), whose levels are reportedly elevated in Eskimos subsisting on marine diets. We conclude that diets that elevate plasma and/or tissue levels of eicosapentaenoic acid, docosahexaenoic acid and dihomo-gamma-linolenic acid precursor gamma-linolenic acid (18:3 omega 6) may exert antiatherosclerotic effects by inhibiting the release of mitogens from platelets and other cells.

8,11,14-Eicosatrienoic Acid↗
PubMed1986

[Polychemotherapy of undifferentiated small cell bronchial cancer. Long-term results].

Long-term results of 2 studies combining etoposide and adriamycin with cisplatin (CAV) or cyclophosphamide (AVE) in small cell lung cancer indicate a 2-year survival rate of 22% and 18% respectively. The complete response rate 2 years after the onset of chemotherapy was 8% (8/98) : 11% (4/36) with CAV and 5% (4/62) with AVE. Among these 8 patients, 2 had a late relapse and one died of an unrelated cause. The actual long-term survival rate was 6% with CAV and 5% with AVE.

Adult↗
PubMed1986

Intravenous propafenone for termination of reentrant supraventricular tachycardia. A placebo-controlled, randomized, double-blind, crossover study.

To assess the antiarrhythmic efficacy of intravenous propafenone, 20 patients with inducible sustained supraventricular tachycardia received propafenone, 2 mg/kg body weight, or placebo in a double-blind, randomized, crossover study. Three patients had intra-atrial reentrant tachycardia, 3 had atrioventricular nodal reentrant tachycardia, and 14 had atrioventricular reciprocating tachycardia associated with the Wolff-Parkinson-White syndrome. Termination of supraventricular tachycardia occurred in 15 of the 20 patients receiving propafenone but 0 of the 11 patients receiving placebo (p less than 0.01). Propafenone prolonged refractoriness and slowed conduction of the atrium, the atrioventricular node, and accessory atrioventricular bypass tracts, and these effects provided antiarrhythmic action to halt tachycardia. No adverse effects were observed in any patient. We conclude that intravenous propafenone is safe and effective in the acute treatment of various forms of reentrant supraventricular tachycardia.

Adult↗
PubMed1985

Invasive candidal balanitis due to a condom catheter in a neutropenic patient.

A 58-year-old man with acute leukemia had balanitis and penile ulceration due to Candida tropicalis after a condom catheter was used because of urinary incontinence. This case illustrates that condom catheters can be associated with serious complications in neutropenic patients and should be used only when absolutely necessary.

Agranulocytosis↗
PubMed1984

Potentiation of neuromuscular blockade by verapamil.

The effects of intravenous (iv) verapamil (0.01 to 1.0 mg/kg) on the constant neuromuscular block produced by an iv infusion of either pancuronium or succinylcholine were studied on the indirectly stimulated gastrocnemius and tibialis-anterior muscles of the rabbit anesthetized with halothane in oxygen. Verapamil alone (n = 6) had no significant effect. However, the drug did significantly potentiate the 50% twitch depression of the gastrocnemius muscle produced by a constant iv infusion of either pancuronium (n = 5) or succinylcholine (n = 5) to 36 +/- 6% and 45 +/- 1% of control, respectively. This effect of verapamil occurred with doses of 0.1 mg/kg for pancuronium and 0.01 mg/kg for succinylcholine; these doses of verapamil were the lowest which produced a significant effect. In contrast, verapamil had no significant effect on the progression of the neuromuscular blockade of either the gastrocnemius or tibialis-anterior muscles produced by alpha-bungarotoxin (n = 5). Verapamil also significantly prolonged the P-R interval of the ECG from a control value of 71 +/- 2 ms to 78 +/- 3 ms at a dose of 0.1 mg/kg and to 93 +/- 6 ms at a dose of 0.3 mg/kg. The possible mechanisms of the neuromuscular actions of verapamil are discussed and it is concluded that verapamil can produce potentiation of either pancuronium- or succinylcholine-induced neuromuscular block at doses within the therapeutic range.

Animals↗
PubMed1982

A comparison of 3,4-diaminopyridine and 4-aminopyridine in the anaesthetized cat.

3,4-Diaminopyridine and 4-aminopyridine were compared in the anaesthetized cat and found to be equiactive in their anti-curare activity. This in vivo similarity is at variance with previous in vitro studies which demonstrate 3,4-diaminopyridine to be more active than 4-aminopyridine at the neuromuscular junction. Possible reasons for the similarity between the two aminopyridines at the in vivo neuromuscular junction are discussed and it is concluded that 3,4-diaminopyridine has only marginal advantages over 4-aminopyridine as a potential anti-curare agent.

4-Aminopyridine↗
PubMed1982

Leprosy downgrading reaction associated with griseofulvin.

A dramatic alteration from clinically subpolar tuberculoid leprosy toward subpolar lepromatous leprosy was observed during griseofulvin therapy in a 29-year-old man, despite apparently normal cell-mediated immunity. To our knowledge, this is the first reported case of a downgrading reaction associated with griseofulvin. It is possible that this reaction was due to inhibition of polymorphonuclear leukocyte chemotaxis by griseofulvin.

Adult↗
PubMedDate not supplied

An approach to ventricular efficiency by use of carbon 11-labeled acetate and positron emission tomography.

BACKGROUND: Positron emission tomography-derived 11C-labeled acetate kinetics have been shown to reflect myocardial oxidative metabolism. The objective of the study was to use this metabolic imaging technique in combination with an evaluation of left ventricular work as an index of ventricular mechanical efficiency. METHODS AND RESULTS: The effects of ventricular ejection fraction and loading on this index were studied quantitatively in a canine experimental model. There was a curvilinear relationship between efficiency and the end-diastolic volume per unit mass (r = 0.84), which appeared to integrate the main determinants of left ventricular mechanical performance successfully and allowed the detection of a decreased ventricular efficiency in acute experimental heart failure. CONCLUSIONS: This approach appears to have the potential to assess the energetic working point of the ventricle in clinical heart disease and follow the effects of therapy. The data demonstrate the feasibility of an estimate of ventricular efficiency that relies on noninvasive data-acquisition techniques.

Acetic Acid↗
PubMedDate not supplied

Scintigraphic evaluation of cardiac autonomic innervation.

Alterations in cardiac autonomic neuronal function have become the focus of intense research in various cardiovascular diseases. Both single-photon emission tomography (SPECT) and the positron emission tomography (PET) imaging techniques in combination with radio-labeled neurotransmitters and receptor ligands have become available for the scintigraphic visualization of presynaptic and postsynaptic neuronal function. Several clinical studies have shown changes in tracer distribution in different clinical conditions, such as ischemic heart disease, congestive heart failure, malignant arrhythmias, heart transplantation, and in patients with diabetes. In patients with congestive heart failure, previous in vitro investigations have concentrated on the postsynaptic level of the sympathetic innervation. However, alterations in presynaptic nerve function have been demonstrated with scintigraphic investigations by decreased presynaptic tracer retention. Moreover, correlation between scintigraphic findings and clinical outcome was shown in patients with heart failure, providing important prognostic information superior to conventional risk assessment. In conclusion, scintigraphic evaluation by SPECT and PET allows functional characterization of cardiac presynaptic and postsynaptic neurons. Regional tracer uptake can be used as an index for the integrity of innervation in various diseases. Newer tracer approaches may allow the noninvasive quantification of neuronal function by PET.

Autonomic Nervous System↗
PubMedDate not supplied

Effect on coronary artery flow reserve and resistance in the remote area after acute coronary artery occlusion in the pig model.

BACKGROUND: It has been reported that vasodilator function in remote myocardial regions supplied by "angiographically normal" coronary arteries is impaired in patients after acute myocardial infarction (MI). The aim of this study was to determine whether coronary artery flow reserve and coronary artery resistance in remote, nonischemic areas are also altered in experimental MI. METHODS: Experiments were performed in anesthetized pigs. In group 1 infarction was induced by ligation of the left-anterior descending artery (LAD); group 2 consisted of sham-operated animals. Hemodynamic parameters, coronary artery resistance, and myocardial blood flow (MBF) were measured before and 4 hours after MI under rest and during infusion of adenosine. RESULTS: Coronary artery dilation by adenosine caused a similar increase in MBF before and 4 hours after coronary artery occlusion. Resting MBF after acute MI was not altered, although a significant reduction (15%; P < .04) in mean aortic pressure was observed compared with baseline. Coronary artery resistance was significantly reduced by adenosine (P < .04) before MI, as well as at 4 hours after MI (P < .03). Coronary artery flow reserve was not adversely affected. The sham-operated animals showed similar results without any significant differences between the two study groups. CONCLUSION: This study indicates that an acute MI in pigs did not increase coronary artery resistance in the remote area after MI and therefore did not adversely affect coronary artery flow reserve in the nonischemic vascular bed. Further studies are necessary to fully understand the exact mechanism of the alterations in remote flow reserve of patients after MI.

Adenosine↗
PubMedDate not supplied

Parent-child agreement in prepubertal depression: findings with a modified assessment method.

OBJECTIVE: Lack of or low parent-child (P-C) agreement is a well-documented problem in child psychopathology assessment. This study proposed to improve this agreement by using a modified assessment approach. METHOD: Ninety-three depressed prepubertal children, aged 6 to 12 years, and their mothers underwent an assessment procedure that combined multiple assessment measures given separately to child and mother (Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present Episode [K-SADS-P], Children's Depression Inventory, and traditional psychiatric interviews), confrontation of either and/or both informants with intra- and interinformant discrepancies, and senior clinician's "best estimate" clinical judgment to solve discrepant ratings. Correlational statistics (r, kappa, and z) were used to compare child's with mother's ratings on 20 K-SADS-P depressive symptoms. RESULTS: The major hypothesis, that using our assessment procedure, P-C agreement would be significant and moderately high (r and kappa = .40 or higher), was confirmed. The second hypothesis on dissociation of P-C agreement on behavioral versus ideational symptoms was partially confirmed; the third hypothesis on adverse effects of maternal "depression" on P-C agreement was not confirmed. CONCLUSION: Our assessment method has potential clinical application in enhancing diagnostic reliability of childhood depression assessment.

Adult↗