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Biomedical subjects

M A Lee

Publications and source records attributed to M A Lee.

At least 19 recordsLinked to original sources
PubMed1998

Viral protein R regulates nuclear import of the HIV-1 pre-integration complex.

Replication of human immunodeficiency virus type 1 (HIV-1) in non-dividing cells critically depends on import of the viral pre-integration complex into the nucleus. Genetic evidence suggests that viral protein R (Vpr) and matrix antigen (MA) are directly involved in the import process. An in vitro assay that reconstitutes nuclear import of HIV-1 pre-integration complexes in digitonin-permeabilized cells was used to demonstrate that Vpr is the key regulator of the viral nuclear import process. Mutant HIV-1 pre-integration complexes that lack Vpr failed to be imported in vitro, whereas mutants that lack a functional MA nuclear localization sequence (NLS) were only partially defective. Strikingly, the import defect of the Vpr- mutant was rescued when recombinant Vpr was re-added. In addition, import of Vpr- virus was rescued by adding the cytosol of HeLa cells, where HIV-1 replication had been shown to be Vpr-independent. In a solution binding assay, Vpr associated with karyopherin alpha, a cellular receptor for NLSs. This association increased the affinity of karyopherin alpha for basic-type NLSs, including that of MA, thus explaining the positive effect of Vpr on nuclear import of the HIV-1 pre-integration complex and BSA-NLS conjugates. These results identify the biochemical mechanism of Vpr function in transport of the viral pre-integration complex to, and across, the nuclear membrane.

Biological Transport↗
PubMed1998

Two uterine arterial management methods in laparoscopic hysterectomy.

OBJECTIVE: The purpose of this study was to evaluate whether laparoscopic separation with coagulation of the uterine arteries and uterosacral ligaments can be used in an attempt to improve the operative procedure when hysterectomy is carried out by laparoscopic and vaginal method. METHOD: A prospective study was carried out in 70 women who underwent laparoscopic hysterectomy excluding total laparoscopic hysterectomy. Laparoscopic uterine arterial separation with coagulation (include laparoscopic reperitonization) was performed after laparoscopic detachment of the bladder and resection of the broad ligament (or adnexa) in 39 cases (Group 1). Uterine artery was coagulated by bipolar electrocoagulator and separated from the uterine side wall by scissors. Endoloop tie was applied to the arterial pedicle, if bleeding occurred. Uterine arterial management was performed through the vaginal route (include vaginal reperitonization) after laparoscopic procedure which was finished at the lower part of broad ligament with bladder detachment in 31 cases (Group 2). RESULTS: The average duration of operation was 84.0 min and 101.8 min in Groups 1 and 2, respectively (p < 0.05). The average amount of bleeding was 154.8 ml and 298.4 ml in Groups 1 and 2, respectively (p < 0.05). Hemoglobin decreased in average by 0.9 g/100 ml and 1.6 g/100 ml in Groups 1 and 2, respectively (p < 0.05). CONCLUSION: These results demonstrate that laparoscopic management of uterine arterial pedicles after bladder detachment could reduce the duration of operation time and amount of bleeding in laparoscopic hysterectomy.

Adult↗
PubMed1997

Tissue- and development-specific expression of multiple alternatively spliced transcripts of rat neuronal nitric oxide synthase.

Nitric oxide (NO) functions as an intercellular messenger and mediates numerous biological functions. Among the three isoforms of NO synthase that produce NO, the ubiquitously expressed neuronal NO synthase (nNOS) is responsible for a large part of NO production, yet its regulation is poorly understood. Recent reports of two alternative spliceforms of nNOS in the mouse and in man have raised the possibility of spatial and temporal modulation of expression. This study demonstrates the existence of at least three transcripts of the rat nNOS gene designated nNOSa, nNOSb, and nNOSc, respectively, with distinct 5' untranslated first exons that arise from alternative splicing to a common second exon. Expression of the alternative transcripts occurs with a high degree of tissue and developmental specificity, as demonstrated by RNase protection assays on multiple tissues from both fetal and adult rats. Furthermore, terminal differentiation of rat pheochromocytoma-derived PC12 cells into neurons is associated with induction of nNOSa, suggesting, likewise, development- and tissue-specific transcriptional control of nNOS isoform expression. Physical mapping using a rat yeast artificial chromosome clone shows that the alternatively spliced first exons 1a, 1b, and 1c are separated by at least 15-60 kb from the downstream coding sequence, with exons 1b and 1c being positioned within 200 bp of each other. These findings provide evidence that the biological activity of nNOS is tightly and specifically regulated by a complex pattern of alternative splicing, indicating that the notion of constitutive expression of this isoform needs to be revised.

Alternative Splicing↗
PubMed1997

Angiotensin AT1 receptor inhibition. Effects on hypertrophic remodeling and ACE expression in rats with pressure-overload hypertrophy due to ascending aortic stenosis.

BACKGROUND: We tested the hypothesis that long-term administration of the specific angiotensin II subtype 1 (AT1)-receptor blocker BMS-186295 will regress hypertrophy and modify left ventricular angiotensin converting enzyme (ACE) expression in rats with ascending aortic stenosis. METHODS AND RESULTS: Six weeks after surgery, rats with ascending aortic stenosis were randomized to receive either the AT1-receptor blocker BMS-186295 50 mg.kg-1.d-1 (n = 49), amlodipine 2.5 mg.kg-1.d-1 (n = 48) as a positive control for systemic vasodilation, or no drug (n = 48) and compared with sham-operated rats (n = 39). Drug treatment was continued for 15 weeks. Left ventricular ACE mRNA levels were measured by ribonuclease protection assay. The left ventricular/body weight ratio was increased 43% in hearts from rats with untreated left ventricular hypertrophy (LVH) versus control hearts (P < .05). However, there was no difference in either the left ventricular/body weight ratio (2.78 +/- 0.08 versus 2.81 +/- 0.20 mg/g; P = NS) or myocyte cross-sectional area in the AT1-blocker-treated versus untreated LVH hearts. Amlodipine also showed no effect on regression of hypertrophy. In vivo left ventricular systolic pressure was significantly higher in untreated LVH versus sham-operated rats (193 +/- 8 versus 118 +/- 4 mm Hg; P < .05), and there was a similar severe elevation of left ventricular systolic pressure in the AT1-blocker- and amlodipine-treated LVH groups (189 +/- 9 and 188 +/- 16 mm Hg; P = NS versus untreated LVH). In vivo left ventricular end-diastolic pressure was higher in the untreated LVH than in the sham-operated rats (14.8 +/- 2.3 versus 7.0 +/- 0.5 mm Hg; P < .05). Left ventricular end-diastolic pressure was lower in the AT1-blocker-treated (11.0 +/- 1.7 mm Hg) and amlodipine-treated rats (11.5 +/- 1.8 mm Hg) and was similar to left ventricular end-diastolic pressure in the sham-operated rats (P = NS). Left ventricular ACE mRNA levels were elevated in untreated LVH rats but were normalized in both the AT1-blocker-treated rats and amlodipine-treated rats. CONCLUSIONS: Long-term AT1-receptor blockade did not regress LVH in rats with persistent systolic pressure overload due to ascending aortic stenosis. However, both AT1-receptor blockade and amlodipine improved in vivo left ventricular end-diastolic pressure in association with the normalization of left ventricular ACE mRNA levels.

Angiotensin Receptor Antagonists↗
PubMed1997

Practical issues in physician-assisted suicide.

Support for the participation of physicians in the suicides of terminally ill patients is increasing, and the concrete effects on physician practice of a policy change with regard to physician-assisted suicide must be carefully considered. If physician-assisted suicide is legalized, physicians will need to gain expertise in understanding patients' motivations for requesting physician-assisted suicide, assessing mental status, diagnosing and treating depression, maximizing palliative interventions, and evaluating the external pressures on the patient. They will be asked to prognosticate not only about life expectancy but also about the onset of functional and cognitive decline. They will need access to reliable information about effective medications and dosages. The physician's position on physician-assisted suicide must be open to discussion between practitioner and patient. Protection of the patient's right to confidentiality must be balanced against the need of health care professionals and institutions to know about the patient's choice. Insurance coverage and managed care options may be affected. All of these issues need to be further explored through research, education, decision making by individual practitioners, and ongoing societal debate.

Disclosure↗
PubMed1997

Depression and mortality in medically ill older adults.

OBJECTIVE: To determine if major depressive disorder influences the survival of older, medically ill veterans. DESIGN: Thirty month follow-up of an inception cohort. SETTING: An academically-affiliated Veterans Affairs Medical Center. PARTICIPANTS: One hundred veterans, half of whom have a depressive disorder, recruited from inpatient medical and surgical units in 1990-1991. At initial evaluation all participants were older than age 65, cognitively intact, and medically but not terminally ill. MEASUREMENTS: Severity of medical illness, functional status, social support and presence of depression were measured at initial evaluation, presence of depression was measured 4 to 6 months after initial evaluation, and survival status was determined at 30 months. Retrospective medical record review was used to determine if patients received depression treatment and to explore whether depressed persons received life-sustaining medical treatment less often than nondepressed persons. RESULTS: At 30 months, 36 of the 100 subjects had died. Only two factors predicted mortality: severity of medical illness and depression. The survival of subjects who had recovered from depression at 4 to 6 months was intermediate to never depressed and continuously depressed subjects. Somatic treatment of depression did not alter outcome. There was no significant difference between depressed and nondepressed in how often life-sustaining medical treatments were withheld or withdrawn. CONCLUSION: Presence of major depression in medically-ill older hospitalized veterans continues to be a risk factor for death 30 months after diagnosis.

Activities of Daily Living↗
PubMed1997

Use of the diagnosis "failure to thrive" in older veterans.

OBJECTIVES: To describe how physicians apply the term "failure to thrive" (FTT) to older patients. Specifically, to describe the clinical presentation, underlying etiologies, diagnostic and therapeutic interventions, and discharge outcomes of veterans having the discharge diagnosis of FTT. DESIGN: Retrospective chart review. SETTING: The Department of Veterans Affairs Medical Center (VAMC), Portland, Oregon, a 400-bed referral and teaching hospital. PARTICIPANTS: All veterans 65 years of age and older admitted to the Portland VAMC from October 1, 1990, through September 30, 1993, whose coded discharge diagnoses included FTT (n = 132). MEASUREMENTS: Medical records were reviewed by a trained abstractor to obtain key data about clinical presentation, etiologies, interventions, and discharge outcomes. RESULTS: Subjects were predominantly male (98%), with a mean age of 76 years +/- 9 years. Weight loss was a key feature: 67% of subjects had evidence of weight loss by study criteria. Anemia was present in 55%, low cholesterol in 50%, and low albumin in 44%. Lymphopenia was common, present in 66% of subjects. Most patients were admitted from home (83%); only 7% came from nursing homes. On admission, the majority (82%) were dependent in at least one ADL, and 36% were cognitively impaired. Cancer was the most common underlying diagnosis (30%), followed by infection (18%), dehydration (13%), and depression (12%). Only 46% of subjects were discharged home, while 34% went to nursing homes. Fourteen percent of subjects died during the hospitalization, an additional 11% died within 30 days after discharge, and 32% died within 1 year after discharge. The subgroup of subjects with cancer and/or infection had increased mortality rates at 30 days and 1 year after hospitalization. CONCLUSION: We conclude that FTT may constitute a discrete syndrome with diagnostic, therapeutic and prognostic implications in older people, but in the absence of consensus about diagnostic criteria, there is a large degree of subjective variation in how physicians apply the term.

Activities of Daily Living↗
PubMed1997

Regulation of bFGF expression and ANG II secretion in cardiac myocytes and microvascular endothelial cells.

Basic fibroblast growth factor (bFGF; fibroblast growth factor-2) and angiotensin II (ANG II), among other peptide signaling autacoids (cytokines), are known to regulate the phenotypic adaptation of cardiac muscle to physiological stress. The cell type(s) in cardiac muscle responsible for ANG II synthesis and secretion and the role of endogenous cytokines in the regulation of bFGF induction remain unclear. With the use of confluent, serum-starved, low-passage cultures of cardiac microvascular endothelial cells (CMEC), ANG II could be detected in cellular lysates and in medium conditioned by these cells with the use of high-performance liquid chromatography followed by radioimmunoassay. The secretion of angiotensins by individual CMEC could be detected with a cell-blot assay technique. ANG II secretion was decreased by brefeldin A, an agent that interrupts constitutive and regulated secretory pathways for peptide autacoid/ hormone synthesis, suggesting de novo synthesis, activation, and secretion of angiotensins by CMEC. In primary isolates of adult rat ventricular myocytes (ARVM) and CMEC, ANG II, acting at ANG II type 1 receptors in both cell types, was found to increase bFGF mRNA levels measured by ribonuclease protection assay. Endothelin-1 (ET-1), which is known to be synthesized by CMEC, and bFGF itself, which has been detected in both ARVM and CMEC, increased bFGF transcript levels in both cell types. Interleukin-1beta (IL-1beta), which like ANG II and ET-1 is known to activate mitogen-activated protein kinases in both ARVM and CMEC, increased bFGF mRNA levels only in cardiac myocytes. Thus cytokines such as ANG II, ET-1, bFGF, and IL-1beta locally generated by cellular constituents of cardiac muscle, including CMEC, regulate bFGF mRNA levels in a cell type-specific manner.

Angiotensin II↗
PubMed1997

Role of tissue renin in the regulation of aldosterone biosynthesis in the adrenal cortex of nephrectomized rats.

The aim of the study was to investigate whether the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in the adrenal gland and to explore the mechanisms of this action. Twelve-week-old male Sprague-Dawley rats were studied: 22 rats were maintained on a regular diet; 27 and 22 rats received a low salt diet with and without treatment, respectively, with the angiotensin II (Ang II) AT1-subtype receptor antagonist losartan (10 mg/kg per day). A fraction of each group of rats underwent bilateral nephrectomy (n = 12, 15, and 10, respectively) and was killed 48 hours later. In an additional group of 24 (12 intact and 12 nephrectomized) rats, the effects of the Ang II AT2-subtype receptor antagonist PD123319 were investigated. In intact rats, plasma renin activity (PRA) and adrenal renin activity and expression were progressively raised by salt restriction and losartan, whereas aldosterone synthase mRNA and plasma aldosterone (PA) levels were increased by salt restriction and reduced by losartan. Forty-eight hours after nephrectomy, PRA fell to undetectable levels; in contrast, adrenal renin expression, assessed by semiquantitative reverse-transcriptase polymerase chain reaction (using GAPDH as a standard for gene expression), showed an 18-fold increase and was further increased after salt restriction and losartan (all P < .05). Also, adrenal renin activity was raised after nephrectomy and further increased after salt restriction (P < .05) and losartan. Cytochrome P450 aldosterone synthase expression in the adrenal cortex was stimulated by nephrectomy alone and by nephrectomy combined with low salt intake (P < .05), with consequent increases in PA concentrations. In losartan-treated salt-restricted nephrectomized rats, cytochrome P450 aldosterone synthase expression (P < .05 versus nephrectomy alone and nephrectomy plus salt restriction) and PA concentrations were diminished (P < .05) in spite of the observed increases of adrenal renin expression. The AT2-receptor antagonism did not significantly affect PRA, adrenal renin, and aldosterone biosynthesis and production in either intact or nephrectomized salt-restricted rats. These results demonstrate that the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in vivo. This action is mediated primarily via the Ang II AT1-subtype receptors.

Adrenal Glands↗
PubMed1997

Age at onset and gender of schizophrenic patients in relation to neuroleptic resistance.

OBJECTIVE: The age at onset of schizophrenia for males has usually but not always been reported to be less than that for females. Early onset has also been associated with poor response to neuroleptic treatment and worse long-term outcome. The authors compared age at onset in neuroleptic-resistant and -responsive schizophrenic patients to determine whether the gender difference in age at onset is related to response to neuroleptic treatment. METHOD: The subjects were 322 patients with schizophrenia or schizoaffective disorder who were consecutively admitted to a university hospital-based research program. RESULTS: Analysis of variance showed significant relationship between age at onset and both gender and longterm responsivity to neuroleptic drugs. The mean ages at onset in the neuroleptic-responsive men (mean = 21.2 years, SD = 6.1, N = 75), neuroleptic-resistant men (mean = 19.4 years, SD = 4.7, N = 119), and neuroleptic-resistant women (mean = 20.1 years, SD = 6.3, N = 77) were fairly similar, whereas that of the neuroleptic-responsive women (mean = 24.2 years, SD = 8.7, N = 51) was significantly greater than for all other groups. A simple effects model indicated that male and female neuroleptic-resistant patients did not differ significantly in mean age at onset, whereas male and female neuroleptic-responsive patients did. The effect of gender and neuroleptic responsivity on age at onset was related to schizophrenic subtype. CONCLUSIONS: These results confirm previous data indicating neuroleptic resistance is associated with early onset. The finding that the difference in age at onset between males and females is smaller in neuroleptic-resistant patients than in neuroleptic-responsive patients suggests that neuroleptic-resistant patients differ premorbidly as well as after onset of illness.

Adolescent↗
PubMed1997

The Oregon Death With Dignity Act: implementation issues.

Passage of the Oregon Death With Dignity Act in 1994 raises nationally relevant questions for health care organization, state agencies, and clinicians. As debate over physician-assisted suicide continues in the United States, the experiences in Oregon may offer insight into the clinical complexities of legalizing physician-assisted suicide.

Government Regulation↗
PubMed1996

Complementation of methylation deficiency in embryonic stem cells by a DNA methyltransferase minigene.

Previous attempts to express functional DNA cytosine methyltransferase (EC 2.1.1.37) in cells transfected with the available Dnmt cDNAs have met with little or no success. We show that the published Dnmt sequence encodes an amino terminal-truncated protein that is tolerated only at very low levels when stably expressed in embryonic stem cells. Normal expression levels were, however, obtained with constructs containing a continuation of an ORF with a coding capacity of up to 171 amino acids upstream of the previously defined start site. The protein encoded by these constructs comigrated in SDS/PAGE with the endogenous enzyme and restored methylation activity in transfected cells. This was shown by functional rescue of Dnmt mutant embryonic stem cells that contain highly demethylated genomic DNA and fail to differentiate normally. When transfected with the minigene construct, the genomic DNA became remethylated and the cells regained the capacity to form teratomas that displayed a wide variety of differentiated cell types. Our results define an amino-terminal domain of the mammalian MTase that is crucial for stable expression and function in vivo.

Amino Acid Sequence↗
PubMed1996

Critical role of reverse transcriptase in the inhibitory mechanism of CNI-H0294 on HIV-1 nuclear translocation.

HIV-1 replication requires the translocation of viral genome into the nucleus of a target cell. We recently reported the synthesis of an arylene bis(methyl ketone) compound (CNI-H0294) that inhibits nuclear targeting of the HIV-1 genome and thus HIV-1 replication in monocyte cultures. Here we demonstrate that CNI-H0294 inhibits nuclear targeting of HIV-1-derived preintegration complexes by inactivating the nuclear localization sequence of the HIV-1 matrix antigen in a reaction that absolutely requires reverse transcriptase. This drug/reverse transcriptase interaction defines the specificity of its antiviral effect and is most likely mediated by the pyrimidine side-chain of CNI-H0294. After binding to reverse transcriptase, the carbonyl groups of CNI-H0294 react with the nuclear localization sequence of matrix antigen and prevent its binding to karyopherin alpha, the cellular receptor for nuclear localization sequences that carries proteins into the nucleus. Our results provide a basis for the development of a novel class of compounds that inhibit nuclear translocation and that can, in principle, be modified to target specific infectious agents.

Antiviral Agents↗
PubMed1996

Local stress, not systemic factors, regulate gene expression of the cardiac renin-angiotensin system in vivo: a comprehensive study of all its components in the dog.

Cardiac hypertrophy is associated with altered expression of the components of the cardiac renin-angiotensin system (RAS). While in vitro data suggest that local mechanical stimuli serve as important regulatory modulators of cardiac RAS activity, no in vivo studies have so far corroborated these observations. The aims of this study were to (i) examine the respective influence of local, mechanical versus systemic, soluble factors on the modulation of cardiac RAS gene expression in vivo; (ii) measure gene expression of all known components of the RAS simultaneously; and (iii) establish sequence information and an assay system for the RAS of the dog, one of the most important model organisms in cardiovascular research. We therefore examined a canine model of right ventricular hypertrophy and failure (RVHF) in which the right ventricle (RV) is hemodynamically loaded, the left ventricle (LV) is hemodynamically unloaded, while both are exposed to the same circulating milieu of soluble factors. Using specific competitive PCR assays, we found that RVHF was associated with significant increases in RV mRNA levels of angiotensin converting enzyme and angiotensin II type 2 receptor, and with significant decreases of RV expression of chymase and the angiotensin II type 1 receptor, while RV angiotensinogen and renin remained unchanged. All components remained unchanged in the LV. We conclude that (i) dissociated regional regulation of RAS components in RV and LV indicates modulation by local, mechanical, not soluble, systemic stimuli; (ii) components of the cardiac RAS are independently and differentially regulated; and (iii) opposite changes in the expression of angiotensin converting enzyme and chymase, and of angiotensin II type I and angiotensin II type 2 receptors, may indicate different physiological roles of these RAS components in RVHF.

Angiotensin II↗
PubMed1996

Legalizing assisted suicide--views of physicians in Oregon.

BACKGROUND: Since the Oregon Death with Dignity Act was passed in November 1994, physicians in Oregon have faced the prospect of legalized physician-assisted suicide. We studied the attitudes and current practices of Oregon physicians in relation to assisted suicide. METHODS: From March to June 1995, we conducted a cross-sectional mailed survey of all physicians who might be eligible to prescribe a lethal dose of medication if the Oregon law is upheld. Physicians were asked to complete and return a confidential 56-item questionnaire. RESULTS: Of the 3944 eligible physicians who received the questionnaire, 2761 (70 percent) responded. Sixty percent of the respondents thought physician-assisted suicide should be legal in some cases, and nearly half (46 percent) might be willing to prescribe a lethal dose of medication if it were legal to do so; 31 percent of the respondents would be unwilling to do so on moral grounds. Twenty-one percent of the respondents have previously received requests for assisted suicide, and 7 percent have complied. Half the respondents were not sure what to prescribe for this purpose, and 83 percent cited financial pressure as a possible reason for such requests. The respondents also expressed concern about complications of suicide attempts and doubts about their ability to predict survival at six months accurately. CONCLUSIONS: Oregon physicians have a more favorable attitude toward legalized physician-assisted suicide, are more willing to participate, and are currently participating in greater numbers than other surveyed groups of physicians in the United States. A sizable minority of physicians in Oregon objects to legalization and participation on moral grounds. Regardless of their attitudes, physicians had a number of reservations about the practical applications of the act.

Adult↗
PubMed1996

Relapse following clozapine withdrawal: effect of neuroleptic drugs and cyproheptadine.

The objective of this study was to report the effect of the slow withdrawal of clozapine from 19 patients with neuroleptic-responsive schizophrenia at the end of a 2-year clinical trial of clozapine and to compare this with the results of naturalistic discontinuation of clozapine treatment in 64 neuroleptic-resistant schizophrenic patients. Nineteen neuroleptic-responsive schizophrenic patients who received clozapine were withdrawn from clozapine by tapering it over 3-week period with and without the addition of a typical neuroleptic. Fifteen of the 19 neuroleptic-responsive patients experienced the return of psychotic symptoms during or after the clozapine taper, which were most severe in the ten patients in whom the withdrawal of clozapine was carried out without prior addition of neuroleptic treatment. Addition of a neuroleptic prior to clozapine withdrawal prevented the emergence of positive symptoms during clozapine withdrawal in each of eight patients. Nevertheless, psychotic symptoms emerged, usually within a week after discontinuing clozapine, in six of the eight patients. Neuroleptic treatment, with or without an anticholingergic drug, was much less effective in treating positive symptoms in these patients immediately after the clozapine withdrawal than it had been 2 years previously. Cyproheptadine, a non-selective serotonin receptor antagonist, augmented the antipsychotic effect of neuroleptics in each of four patients who relapsed following withdrawal from clozapine and relieved extrapyramidal symptoms in a fifth patient. The frequency of relapse following withdrawal of clozapine in 64 neuroleptic-resistant patients was significantly lower (25/64, 39.1%) than in the neuroleptic-responsive patients.

Adult↗