Biomedical subjects

S Lee

Publications and source records attributed to S Lee.

At least 1,153 records · Page 64Linked to original sources

PubMed1992

Characterization of the statin-like S1 and rat elongation factor 1 alpha as two distinctly expressed messages in rat.

Previously, we reported a rat S1 protein that is antigenically related to statin, a nonproliferating cell-specific marker; however, it shares high homology with the known human elongation factor-1 alpha (EF-1 alpha). To differentiate S1 from rat EF-1 alpha and to study their respective regulation for expression, a rat EF-1 alpha cDNA clone was isolated and characterized. The nucleotide and deduced amino acid sequences of this partial rat EF-1 alpha cDNA are compared with that of human and mouse as well as with rat S1. Both their messages were detected in rat brain by EF-1 alpha- or S1-specific probes. However, the mRNA encoding EF-1 alpha is more abundant than that encoding S1. S1 and EF-1 alpha expression were investigated in the parotid and submandibular glands of untreated rats and those treated with isoproterenol, a proliferation-inducing catecholamine. Quantitative solution hybridization demonstrated a dramatic reduction (approximately 68%) in the S1 mRNA following isoproterenol injection in proliferation-responsive parotid glands and a mild reduction (approximately 20%) of S1 steady-state messages in the proliferation-refractile submandibular glands. A slight increase or no changes of EF-1 alpha levels in both parotid and submandibular glands following isoproterenol treatment are also observed. Therefore, the EF-1 alpha and S1 genes are different genes, both expressed and regulated in vivo, but in differential quantitative and qualitative patterns.

Amino Acid Sequence↗

PubMed1992

Effect of amphipathic peptides with different alpha-helical contents on liposome-fusion.

The peptide-induced fusion of neutral and acidic liposomes was studied in relation to the amphiphilicities evaluated by alpha-helical contents of peptides by means of a carboxyfluorescein leakage assay, light scattering, a membrane intermixing assay and electron microscopy. An amphipathic mother peptide, Ac-(Leu-Ala-Arg-Leu)3-NHCH3 (4(3], and its derivatives, [Pro6]4(3) (1), [Pro2,6]4(3) (2), and [Pro2,6,10]4(3) (3), which have very similar hydrophobic moments, caused a leakage of contents from small unilamellar vesicles composed of egg yolk phosphatidylcholine and egg yolk phosphatidic acid (3:1). The abilities of the peptides to induce the fusion of the acidic liposomes increased with increasing alpha-helical content: in acidic liposomes the helical contents were in the order of 4(3) greater than 1 greater than 2 greater than 3 (Lee et al. (1989) Chem. Lett., 599-602). Electron microscopic data showed that 1 caused a transformation of the small unilamellar vesicles (20-50 nm in diameter) to large ones (100-300 nm). Based on the fact that these peptides have very similar hydrophobic moments despite of decreasing in the mean residue hydrophobicities to some extent, it was concluded that the abilities of the peptides to induce the fusion of liposomes depend on the extent of amphiphilic conformation evaluated by alpha-helical contents of the peptides in the presence of liposomes. For neutral liposomes of egg yolk phosphatidylcholine, all the proline-containing peptides showed no fusogenic ability but weak leakage abilities, suggesting that the charge interaction between the basic peptides and acidic phospholipid is an important factor to induce the perturbation and fusion of the bilayer.

Amino Acid Sequence↗

PubMed1992

Improved detection of antibodies to hepatitis C virus using a second generation ELISA.

A screening assay for the detection of antibodies to hepatitis C virus (HCV); ORTHO HCV ELISA Test System, Second Generation, was compared with the currently licensed c100-3 based test (ORTHO HCV ELISA Test System). The second generation ELISA differs from the c100-3 based assay in that it detects circulating antibodies to both structural (nucleocapsid) and non-structural (NS3/NS4) HCV proteins. Specimens tested consisted of a cohort of 35 patients diagnosed with non-A, non-B hepatitis (NANBH) and 3971 presumably healthy volunteer blood donors. Second generation ELISA demonstrated significantly greater clinical sensitivity in patients with acute phase NANBH (80% vs. 60%) as well as chronic disease (88% vs. 72%). Additional specimens reactive only in second generation ELISA, demonstrated reactivity to HCV antigens c33c and/or c22-3 in supplemental testing by the Chiron HCV RIBA Assay System. The second generation ELISA also detected additional RIBA reactive volunteer blood donors (0.18% of the population tested) that were nonreactive in first generation ELISA. This data indicated that second generation ELISA would detect approximately 2 additional anti-HCV reactive donors per 1,000 screened. Specificities obtained with this low risk population were 99.6% for first generation and 99.7% for second generation ELISA.

Blood Donors↗

PubMed1992

Insulinotropic potency of lauric acid: a metabolic rationale for medium chain fatty acids (MCF) in TPN formulation.

The need for a better lipid system to satisfy the fuel requirements of patients while avoiding the adverse effects of current systems has led to suggestions that medium chain fatty acids (MCFs) be incorporated into TPN-lipid emulsions. Since clinical situations requiring TPN are associated with metabolic processes mediated by insulin, in the present study we have therefore examined the effects of a variety of medium chain fatty acids on insulin release. Using an isolated perifused mouse islet model, various doses of medium chain fatty acids and the essential fatty acid, linoleic acid, were tested and compared. The possibility of an additive effect of an insulinotropic MCF and linoleate when both are provided together was also examined. Effluent perifusate samples collected on ice during these experiments were assayed for insulin by radioimmunoassay. It was found that the ability of 5 mM of a given MCF to stimulate insulin secretion was dependent upon its chain length. Thus, while adipic acid (C6) had no effect, Caprylic acid (C8) had a minimal effect that was not statistically significant, but capric acid (C10) and lauric acid had very potent effects that were of the same magnitude to the effect of linoleate on insulin secretion. When insulin output was assessed as the mean integrated area under the curve during a 20-min perifusion, 5 mM lauric acid enhanced insulin secretion from a basal 7351 +/- 666 pg to 15,756 +/- 1680 pg (P less than 0.01, n = 5). In the same experiments, 5 mM linoleic acid stimulated insulin release to 11,260 +/- 867 pg (P less than 0.05). When C12 and linoleate were added together, each at a submaximally effective concentration of 2.5 mM, insulin output was 12,712 +/- 1011 pg (P less than 0.05, n = 5), which was not statistically different from the values obtained when the islets were perifused with 5 mM of each fatty acid alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Indium-labeled presensitized T cells for diagnosis of graft rejection.

The aim of this experiment was to test a safe, noninvasive method for necessary, accurate diagnosis of early allograft rejection. Heart-lung allograft was performed heterotopically using Brown Norway (BN) rats as the donor and Lewis (LEW) rats as the recipient. T cell suspensions were prepared from lymphnodes of specifically sensitized LEW rats that had acutely rejected full-thickness BN skin graft. Cell count was adjusted 50 x 10(6) cells/ml. The suspension was incubated in vitro with 111I oxide (1 m Ci-ml). An aliquot of labeled cell suspension containing 40 x 10(6) cells and a total radioactivity of 200 mCi was administered intravenously to each animal 3 and 6 days after heart-lung transplant. The traffic of T cells was followed in vivo and in isolated organs under large field view gamma camera. The gamma camera revealed radioactivity on the graft starting Postoperative Day 5 when the heart was actively beating; no radioactivity was revealed at the site of the isografted organs. The histology showed mild to moderate cellular infiltration parallel to the grade of radioimaging intensity. The injection of indium-labeled presensitized T cells was able to detect the rejection process in an early phase when there are no clinical symptoms of rejection and/or the rejection cascade can be reversed. These results suggest that a similar method can be used in human organ transplantation for early diagnosis of rejection.

Animals↗

PubMed1992

Physical consequences of depression in the stroke patient.

The past literature suggests the hypothesis that depression is associated with decreased physical functional ability in stroke patients. On a medical rehabilitation ward, 21 stroke patients were evaluated for depression by psychiatric interview and self-report, and were also rated on the Barthel's Functional Index (BFI). The hypothesis was supported: Patients scoring 17 or higher on the Beck Depression Inventory (BDI) (N = 7) had lower initial scores on the BFI than patients with lower BDI scores. There was a trend for these seven depressed patients to improve more slowly as ascertained by the BFI. Depression was suggested to lower functional ability by increasing fatigue, hopelessness, and decreasing motivation.

Activities of Daily Living↗

PubMed1992

Thyroid abnormalities during chronic lithium treatment in Hong Kong Chinese: a controlled study.

Fifty Chinese psychiatric patients on chronic lithium treatment and the same number of sex- and age-matched control outpatients were assessed by a thyroidologist and underwent laboratory investigations. Lithium patients had a higher rate of goitres (50% vs 10%, P < 0.0001) and a higher mean TSH level (P < 0.005) than controls. Thyroid antibodies were detected in 7 older manic-depressive patients as opposed to 1 control, but not in patients with recurrent unipolar mania. Five patients, but no controls, had single or multiple episodes of hyperthyroidism, which was followed in 2 of them by biochemical hypothyroidism. It is suggested that variations in iodine status, dietary goitrogens, immunogenetic makeup and their complex interactions with chronic lithium treatment may contribute to ethnically different patterns of thyroid abnormalities.

Adolescent↗

PubMed1992

Folate concentration in Chinese psychiatric outpatients on long-term lithium treatment.

Among 46 Chinese and mostly manic-depressive (85%) outpatients attending a lithium clinic in Hong Kong, virtually no patients had low serum (0%) or erythrocyte (2%) folate. Their mean folate levels did not differ from lithium-free outpatients. Although serum folate correlated negatively with lithium dose (P less than 0.002) and serum level (P less than 0.01), lithium treatment probably did not by itself cause low folate. Folate level was not related to diagnosis, duration of mental illness, other drug usage or spot affective morbidity. Patients with a good response to lithium in the previous one year had a higher mean serum folate level than those with unsatisfactory response (P less than 0.05). These data suggest that folate deficiency is uncommon among Chinese psychiatric outpatients, but support recent evidence that folate at high concentrations enhances lithium prophylaxis.

Ambulatory Care↗

PubMed1992

An examination of the mitomycin C induction of chromosome polymorphisms in cultures of Plasmodium falciparum.

Cloned parasites of the FCR3 strain of Plasmodium falciparum that survived treatment with either mitomycin C or ethidium bromide were grown and subcloned. The chromosomes of 10 cloned isolates from each population were analysed by contour-clamped homogenous electric field gel electrophoresis. Eight of 10 isolates from the mitomycin C-treated population contained a detectable polymorphic chromosome change while none of the isolates from the ethidium bromide-treated population did. One of the polymorphic changes involved chromosome #4. A pyrimethamine resistant derivative of FCR3, FCR3-D5, that had previously been shown to contain a single nucleotide change in the dihydrofolate reductase-thymidylate synthase (DHFR-TS) gene but no detectable chromosome polymorphisms, was sequentially treated with mitomycin C and a higher concentration of pyrimethamine than the strain had previously been shown to be resistant to in order to determine if there was a correlation between the selection of chromosome #4 polymorphisms and the applied selective pressure. Most of the cloned survivors of this treatment were found to contain chromosome polymorphisms that involved chromosome #4, the chromosome on which the DHFR-TS gene is located. The polymorphic changes were usually different in the different isolates. The selection of mitomycin C-treated, pyrimethamine resistant strains with chromosome #4 polymorphisms will be discussed.

Animals↗

PubMed1992

A novel microbial sensor using luminous bacteria.

A novel microbial sensor system that uses luminous bacteria was developed for the determination of both glucose and toxic compounds. The sensor system consisted of a membrane with luminous bacteria immobilized upon it and a photomultiplier. Measurements were based on the in vivo intensity of the light emitted by the bacteria, as this is affected by their environment. A linear relationship was observed between increased luminescence and concentrations of glucose between 0.05 mM and 0.55 mM. The relative standard deviation was 10% for 0.55 mM glucose (n = 10). Toxic compounds such as benzalkonium chloride, sodium dodecyl sulphate and chromium(VI) were also detected by measuring the decrease in luminescence in their presence.

Bacteria↗

PubMed1992

Detection of depression in the stroke patient.

The literature suggests the hypothesis that nonpsychiatrists will underrecognize depression in evaluations of stroke patients. On a medical rehabilitation ward, 15 stroke patients were evaluated for depression by psychiatric interview and self-report. Charts were examined for detection of depression by the rehabilitation team. The hypothesis was supported: in contrast to psychiatric interview (68% depressed) and self-report (Beck Depression Inventory, 50% depressed), none of the patients were described as depressed in chart notes by the rehabilitation team (excluding the psychiatrists). Psychiatrists should develop ongoing interactions with primary care physicians to improve detection of poststroke depression and other depressions on medical wards.

Aged↗

PubMed1992

Perceptions of emergency care by the elderly: results of multicenter focus group interviews.

STUDY OBJECTIVE: To determine the elderly's perception of emergency care and to identify specific problems and solutions. DESIGN: Focus group interviews. SETTING AND TYPE OF PARTICIPANTS: Community senior citizen centers in Boston; Los Angeles; Pittsburgh; Youngstown, Ohio; and Norwalk, Connecticut. Senior citizens who had had emergency care in the past year participated. MEASUREMENT AND RESULTS: Participants were satisfied with their overall medical care. Long waits were a hardship for patients and their families. The elderly are not familiar with the process of emergency care. They were frightened by their injury or illness. Their anxiety was not allayed until they were informed of the nature of their illness and what their treatment and disposition was to be. The emergency department environment frequently made them uncomfortable. There was considerable confusion caused by the billing process. CONCLUSIONS: The elderly would benefit from prior or concurrent education regarding emergency care. Staff should be more sensitive to the anxiety felt by the elderly, should explain the reasons for delays in care, and what to expect. Patients should be informed of the nature and seriousness of their illness as soon as possible. Family and friends may be encouraged to stay with patients. The billing process needs to be clarified and simplified.

Aged↗

PubMed1992

Molecular aspects of the calbindins.

Studies from our laboratory concerning regulation of calbindin include regulation by 1,25-dihydroxycholecalciferol [1,25(OH)2D3], receptor regulation as a possible mechanism for modulating calbindin's response to hormone, tissue specific regulation and regulation by factors other than 1,25(OH)2D3. With regard to receptor regulation, we found that the induction of calbindin mRNA in intestine and kidney by 1,25(OH)2D3 is not accompanied by a corresponding alteration in vitamin D receptor (VDR) mRNA in the vitamin D-deficient, low calcium rat. However, in the vitamin D-replete rat, administration of 1,25(OH)2D3 results in an induction of both calbindin and VDR mRNA in these tissues. These results suggest the presence of an inhibitor of 1,25(OH)2D3-mediated receptor up-regulation in the vitamin D-deficient, low calcium animal. Glucocorticoids can also regulate calbindin gene expression. Dexamethasone treatment (50 micrograms.100 g body weight-1.d-1 for 4 d) results in a 75% decrease in rat intestinal calbindin-D9k mRNA. This decrease may be related to the inhibition of intestinal calcium absorption previously observed after glucocorticoid administration. Kidney calbindin-D28k mRNA is unaffected by glucocorticoid treatment, indicating tissue specificity of the glucocorticoid response. To evaluate more precisely the means whereby 1,25(OH)2D3 and other modulators can influence calbindin gene expression, we isolated the chromosomal gene for calbindin-D28k by screening a mouse genomic library in cosmid. Ros 17/2.8 cells were transfected with recombinant plasmids in which the mouse calbindin promoter is fused to the reporter gene encoding chloramphenicol acetyltransferase. Deletion studies have enabled us to identify sequence elements in the mouse calbindin-D28k gene that confer basal activation and a hormone inducible response.

Animals↗

PubMed1992

Coagulopathy and catecholamines in severe head injury.

The prospective study reported here evaluated the relationship between coagulopathy, catecholamines, and outcome in severe head trauma. Thirty-six trauma patients (10 with penetrating injuries, 26 with blunt injuries, 50% overall mortality) were evaluated. These patients had severe head trauma (Glasgow Coma Scale score less than 9). Blood was analyzed for platelet count, prothrombin time (PT), partial thromboplastin time (PTT), and fibrinogen, D-dimer, antithrombin III, protein C, and protein S levels. A 24-hour urine sample was collected for vanillylmandelic acid (VMA), normetanephrine, and metanephrine determinations. A control group of five patients undergoing elective neurosurgery was also studied. Statistically significant differences between head injury survivors and nonsurvivors were present for platelet count, PT, and fibrinogen activity. There were no differences in the results of the other coagulation tests or in urinary catecholamine levels. The trauma patients differed from the elective neurosurgery patients with regard to D-dimer levels, PT, PTT, protein C levels, and urinary normetanephrine concentrations. Head trauma patients have a coagulopathy that is absent in patients following elective neurosurgical procedures. The coagulopathy may correlate with poor survival in head trauma and may be related to a catecholamine surge.

Blood Coagulation Tests↗

PubMed1992

Cytokinins and auxins control the expression of a gene in Nicotiana plumbaginifolia cells by feedback regulation.

Both cytokinin (N6-benzyladenine [BA]) and auxin (2,4-dichlorophenoxyacetic acid [2,4-D]) stimulate the accumulation of an mRNA, represented by the cDNA pLS216, in Nicotiana plumbaginifolia suspension culture cells. The kinetics of RNA accumulation were different for the two hormones; however, the response to both was transient, and the magnitude of the response was dose dependent. Runoff transcription experiments demonstrated that the transient appearance of the RNA could be accounted for by feedback regulation of transcription and not by the induction of an RNA degradation system. The feedback mechanism appeared to desensitize the cells to further exposure of the hormone. In particular, cells became refractory to the subsequent addition of 2,4-D after the initial RNA accumulation response subsided. A very different response was observed when the second hormone was added to cells that had been desensitized to the first hormone. Under such conditions, BA produced a heightened response in cells desensitized to 2,4-D and vice versa. These findings support a model in which cytokinin further enhances the auxin response or prevents its feedback inhibition. The hormone-induced RNA accumulation was blocked by the protein kinase inhibitor staurosporin. On the other hand, the protein phosphatase inhibitor okadaic acid stimulated expression, and, in particular, okadaic acid was able to stimulate RNA accumulation in cells desensitized to auxin. This suggests that hormone activation involves phosphorylation of critical proteins on the hormone signaling pathway, whereas feedback inhibition may involve dephosphorylation of these proteins. The sequence of pLS216 is similar to genes in other plants that are stimulated by multiple agonists such as auxins, elicitors, and heavy metals, and to the gene encoding the stringent starvation protein in Escherichia coli. It is proposed that this gene family in various plants be called multiple stimulus response (msr) genes.

Amino Acid Sequence↗

PubMed1992

Mexiletine and propafenone: a comparative study of monotherapy, low, and full dose combination therapy.

The electrophysiological effects of combination therapy of mexiletine and propafenone were assessed using standard 12-lead electrocardiogram (standard ECG), signal-averaged ECG (SAECG), and ambulatory ECG in 31 patients with ventricular arrhythmias. All patients underwent mexiletine monotherapy (M-mono), propafenone monotherapy (P-mono), low dose combination therapy (low M+P), and full dose combination therapy (full M+P). Full M+P increased the PQ interval and QRS duration to the same extent as P-mono did. Low M+P increased PQ interval and QRS duration to a lesser extent than P-mono and full M+P did. P-mono and full M+P significantly decreased root mean square (RMS) and increased f-QRS in SAECG, while M-mono and low M+P showed only a weak trend. SAECGs with late potentials increased in number with treatments; 9 in predrug control, 11 on M-mono, 15 on P-mono, 10 on low M+P, and 14 on full M+P. The percent suppression of frequent premature ventricular contractions (PVCs) (> 1,000/day) with M-mono, P-mono, low M+P, and full M+P were 46.4 +/- 9.0, 56.6 +/- 10.4, 64.4 +/- 9.2, and 71.4 +/- 7.1, respectively, and those of frequent couplets (> 10/day) were 58.3 +/- 17.7, 62.6 +/- 23.6, 87.5 +/- 6.2, and 92.1 +/- 4.0, respectively. Thus, full dose combination of mexiletine and propafenone exhibited the maximum antiarrhythmic efficacy without enhancement of effects on standard ECG and SAECG. Low dose combination therapy showed better antiarrhythmic efficacy in association with lesser effects on standard ECG and SAECG compared with propafenone monotherapy.

Arrhythmias, Cardiac↗

PubMed1992

The Epstein-Barr virus (EBV) nuclear antigen 1 BamHI F promoter is activated on entry of EBV-transformed B cells into the lytic cycle.

In Epstein-Barr virus (EBV)-positive Burkitt's lymphoma cell lines exhibiting the latency I form of infection (i.e., EBV nuclear antigen 1 [EBNA1] positive in the absence of other latent proteins), the EBNA1 mRNA has a unique BamHI Q/U/K splice structure and is expressed from a novel promoter, Fp, located near the BamHI FQ boundary. This contrasts with the situation in EBV-transformed lymphoblastoid cell lines (LCLs) exhibiting the latency III form of infection (i.e., positive for all latent proteins), in which transcription from the upstream Cp or Wp promoters is the principal source of EBNA mRNAs. We carried out cDNA amplifications with oligonucleotide primer-probe combinations to determine whether Fp is ever active in an LCL environment. The results clearly showed that some LCLs express a Q/U/K-spliced EBNA1 mRNA in addition to the expected Cp/Wp-initiated transcripts; this seemed inconsistent with the concept of Cp/Wp and Fp as mutually exclusive promoters. Here we show that Fp is indeed silent in latency III cells but is activated at an early stage following the switch from latency III into the virus lytic cycle. Four pieces of evidence support this conclusion: (i) examples of coincident Cp/Wp and Fp usage in LCLs are restricted to those lines in which a small subpopulation of cells have spontaneously entered the lytic cycle; (ii) transcripts initiating from Fp can readily be demonstrated in spontaneously productive lines by S1 nuclease protection; (iii) the presence of Fp-initiated transcripts is not affected by acyclovir blockade of the late lytic cycle; and (iv) infection of latently infected LCLs with a recombinant vaccinia virus encoding the EBV immediate-early protein BZLF1, a transcriptional transactivator which normally initiates the lytic cycle, results in the appearance of the diagnostic Q/U/K-spliced transcripts.

Antigens, Viral↗

PubMed1992

Prevalence of tardive dyskinesia, tardive dystonia, and respiratory dyskinesia among Chinese psychiatric patients in Hong Kong.

OBJECTIVE: Only scanty information on the prevalence of tardive dyskinesia in Chinese patients has been available. This study was undertaken to examine the prevalence of tardive dyskinesia, tardive dystonia, and respiratory dyskinesia in Chinese psychiatric patients in Hong Kong. METHOD: All inpatients of a mental hospital in Hong Kong, except those in the admission and children's wards, were surveyed with the Abnormal Involuntary Movement Scale, and standard research criteria were used to establish the diagnosis of tardive dyskinesia. In addition, patients were screened for tardive dystonia, according to published criteria, and for respiratory dyskinesia by physical examination and laboratory tests. RESULTS: Among the 917 patients surveyed, the prevalence rates were 9.3% for tardive dyskinesia, 0.4% for tardive dystonia, and 1.2% for respiratory dyskinesia. With multivariate analysis, greater age and a lower current dose of antipsychotic, but not the presence of mood disorder, were factors found to be significantly associated with tardive dyskinesia. CONCLUSIONS: The prevalence rates were much lower than those found in Western studies. This may indicate that there is an ethnic difference in the prevalence of these conditions. Prospective cross-cultural studies are necessary to explore this possibility.

Adolescent↗