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Biomedical subjects

S Lee

Publications and source records attributed to S Lee.

At least 667 records · Page 37Linked to original sources
PubMed1998

CD45 partially mediates heterotypic adhesion between murine leukemia/lymphoma cell line L5178Y and marrow stromal cells.

We raised mAbs to whole L5178Y leukemia/lymphoma (LL) cells to identify adhesion proteins involved in adherence between LL cells and marrow stromal cells. One mAb, 4C, and its subclones 4C.1 and 4C.2 inhibited adherence of L5178Y LL cells to MLT. a nontransformed murine marrow stromal cell line. These MoAbs are directed against CD45RA. Control anti-CD45 mAbs and isotype mAbs were non-inhibitory. Other anti-CD45 mAbs, M1/9.3, RA3-3A1/6.1 and RA3-2C2/1 do not compete with mAb 4C.1 for binding to the L5178Y cell surface, but mAb 4C.1 competes for binding of mAb RA3-2C2/1. Effects of mAb 4C on tyrosine-phosphatase activity of CD45 in L5178Y cells are minimal, suggesting direct involvement of CD45 as an adhesion protein.

Animals↗
PubMed1998

A controlled study of folate levels in Chinese inpatients with major depression in Hong Kong.

BACKGROUND: Although Western and, in particular, British studies have revealed a substantial rate of hypofolatemia in patients with depression, few such studies have been conducted in Asian populations. METHODS: A group of 117 newly admitted inpatients with DSM-III-R major depression and 72 healthy controls underwent blood investigations and psychometric assessments. RESULTS: Patients had a significantly lower mean serum folate level (24.6+/-10.2 vs. 30.3+/-11.4 nmol/l, P < 0.001) but a higher mean erythrocyte folate level (801.8+/-284.6 nmol/l vs. 699.5+/-248.7 nmol/l, P < 0.01) than control subjects. No patient or control subjects had low folate, while only four patients (3.4%) and six control subjects (8.3%) had low erythrocyte folate. Folate levels were not related to patients' age, duration of illness, Hamilton Depression Rating Scale, Beck Depression Inventory and Global Assessment Scale scores, and prior psychotropic drug usage. Both patients and control subjects revealed a high intake of green vegetables. CONCLUSION: Patients' lower serum folate level was likely to be secondary to their depression but, being well in the normal range, should not have aggravated their depressive symptoms. Culturally patterned health beliefs and dietary practices can influence the connection between folate status and depression in different societies. LIMITATIONS: Patients were not drug-free, while the lack of detailed dietary analysis and longitudinal data on folate level and psychiatric outcome tempered the above conclusion. CLINICAL RELEVANCE: Since normofolatemia is normative in Hong Kong, the routine screening of folate levels in Chinese depressive patients is not indicated. However, a double-blind, placebo-controlled trial may be useful for finding out whether Chinese patients will still benefit from folate pharmacotherapy.

Adolescent↗
PubMed1998

Higher earnings, bursting trains and exhausted bodies: the creation of travelling psychosis in post-reform China.

This paper examines the biomedical construction of "travelling psychosis" (TP), a contested psychiatric diagnosis pertaining to a severe mental disturbance that occurs among migrant workers who travel long distance in China's overcrowded trains. Although TP can produce substantial psychiatric morbidity, it is also a socially constructed entity that serves social uses. By subscribing to a ritualistic model of validation and by invoking the rhetoric of scientific authority, Chinese psychiatrists who created TP have been able to accomplish such goals as legitimating its forensic function, securing research funds, enhancing their academic status and raising railway authorities' consciousness about passengers' safety issues. But the "biopsychosocial" paradigm they espouse supplies only a parochial form of social analysis and a spurious sense of comprehensiveness. By privileging proximate risk factors, it fails to address the wider environment of the post-reform political economy that ultimately governs population movement and put migrant workers at risk of health problems. This paper submits that a critical examination of this sanitised biopsychosocial paradigm will enliven biomedical research as well as augment its impact on policy development in China.

Adolescent↗
PubMed1998

Recurrent compartment syndrome of the hand: a case report.

A young man presented with severe symptoms and markedly elevated hand compartment pressures 5 weeks after undergoing successful decompressive fasciotomies for acute compartment syndrome. The patient's initial postoperative course was complicated by reflex sympathetic dystrophy (RSD). It is hypothesized that the vasomotor instability and the periodic vasospastic episodes associated with RSD prompted postischemic swelling and edema and led to the development of this unusual complication.

Adult↗
PubMed1998

Induction of immune-mediated hearing loss in SCID mice by injection of MRL/lpr mouse spleen cells.

Induction of immune-mediated hearing loss in SCID mice by injection of MRL/lpr mouse spleen cells The MRL/lpr mouse, which has a mutation in the Fas gene encoding a cell-surface receptor for apoptosis, shows an accumulation of abnormal immunocompetent cells and SLE-like disease. It has recently been reported that this mouse also manifests sensorineural hearing loss (SHL) with cochlear pathology at 20 weeks of age. We examined the effects of injecting MRL/lpr spleen cells on the development of SHL in severe combined immunodeficient (SCID) mice, which originally develop neither SHL nor cochlear pathology. Immune-mediated SHL and cochlear pathology were, indeed, transferred to the SCID mice by the injection of spleen cells from the MRL/lpr mice. These findings suggest that cell-mediated immunity is involved in the development of SHL and cochlear pathology.

Animals↗
PubMed1998

Use of intravascular ultrasound improves long-term clinical outcome in the endovascular management of atherosclerotic aortoiliac occlusive disease.

PURPOSE: This study was undertaken to determine whether the use of intravascular ultrasound (IVUS) during balloon angioplasty and stenting of atherosclerotic aortoiliac occlusive lesions improved long-term clinical outcome. IVUS has been previously shown to be more accurate than arteriography in evaluating the deployment of stents in both peripheral and coronary arteries. Incomplete stent deployment has been anecdotally identified as a cause of restenosis or occlusion of a treated lesion. To our knowledge, there have been no previous studies that demonstrate whether the use of IVUS will affect the long-term patency rate of stented arterial lesions. METHODS: Between March 1992 and October 1995, 52 patients with symptomatic aortoiliac occlusive disease underwent balloon angioplasty and stenting of their lesions. We retrospectively reviewed these cases to determine whether the use of IVUS influenced the long-term patency rate of these interventions. Follow-up ranged from 1 to 4 years with a mean of 28 months. RESULTS: Fifty-two patients had confirmation of adequate stent deployment by arteriography. IVUS was used in conjunction with arteriography in 36 patients to evaluate stent deployment. Patients in the IVUS-assisted group were slightly younger than those patients who were evaluated solely by arteriography (p < 0.01). No statistical differences were noted between the two groups with respect to coronary artery disease, diabetes mellitus, obstructive pulmonary disease, hypertension, or obesity. Length of hospital stay, number of stents used, and preoperative ankle brachial indexes were comparable in both groups. In the arteriography plus IVUS group, 40% of patients had underdeployed stents by IVUS evaluation, though they appeared adequately expanded by arteriography. No restenoses or occlusions were seen in the arteriography plus IVUS group. Restenosis or occlusion of the stented lesion occurred in 25% of patients evaluated by arteriography alone (p < 0.01). These failures were treated by either thrombolysis or catheter thrombectomy and were then evaluated with IVUS. All were found to have underdeployed stents. Subsequent treatment consisted of adequate redeployment of existing stents using IVUS criteria. These salvaged reconstructions have continued to remain patent. CONCLUSIONS: The use of IVUS may be the best means for assessing adequacy of arterial stent deployment. Our study suggests that the use of IVUS improves the long-term clinical outcome of balloon angioplasty and stented aortoiliac occlusive lesions.

Adult↗
PubMed1998

Effect of alpha-tocopherol, taurine and selenium on the attenuation of ischemia/reperfusion injury of splanchnic organs.

BACKGROUND: Splanchnic artery occlusion shock is caused by increased capillary permeability and cellular injury precipitated by oxygen derived free radicals following ischemia and reperfusion of splanchnic organs. The purpose of this study was to assess the role of several well-known oxygen-derived free radical scavengers in ameliorating or preventing this syndrome. STUDY DESIGN: Anesthetized rats were subjected to periods of occlusion of the visceral arteries and reperfusion. Tocopherol, taurine, selenium or a 'cocktail' of these three agents was injected subcutaneously for 4 consecutive days prior to operation. Mean arterial blood pressure was measured throughout the experimental period. Fluorometry and technetium-99m pyrophosphate counting of the visceral organs were performed as well as a histologic grading system for intestinal viability. RESULTS: Final mean arterial blood pressure associated with the 'cocktail' and selenium groups was 79.1 +/- 27.4 mmHg and 83.6 +/- 17.8 mmHg, respectively. These values were significantly higher than the control group, 40.8 +/- 11.4 mmHg (P < 0.05). Similar patterns of the benefit of selenium in contrast with the other groups were obtained with fluorescein perfusion, radioisotopic activity and histologic analysis. CONCLUSION: Pretreatment with selenium of splanchnic ischemia and reperfusion in the rat improves mean arterial blood pressure and microcirculatory visceral perfusion. Further analysis of the precise protective mechanism of selenium for reperfusion injury will enable visceral organs to withstand the consequences of increased capillary leakage and oxidant injury.

Animals↗
PubMed1998

Lipitoids--novel cationic lipids for cellular delivery of plasmid DNA in vitro.

BACKGROUND: Although synthetic nonviral vectors hold promise for the delivery of plasmid DNA, their gene-transfer efficiencies are far from matching those of viruses. To systematically investigate the structure-activity relationship of cationic lipids, a small library of cationic lipid-peptoid conjugates (lipitoids) was synthesized. The compounds were evaluated for their ability to form complexes with plasmid DNA and to mediate DNA transfer in vitro. RESULTS: Lipid-peptoid conjugates were conveniently prepared in high yield using solid-phase synthesis. Several lipitoids condensed plasmid DNA into 100 nm spherical particles and protected the DNA and DNase digestion. A subset of lipitoids with a repeated (aminoethyl, neutral, neutral) sidechain trimer motif conjugated with dimyristoyl phosphatidyl-ethanolamine (DMPE) mediated DNA transfer with high efficiency. CONCLUSIONS: Automated solid-phase synthesis of cationic lipids allowed the rapid synthesis of a diverse set of transfection reagents. The most active compound DMPE-(Nae-Nmpe-Nmpe)3 (Nae, N-aminoethyl glycine; Nmpe, N-p-methoxyphenethyl-glycine) is more efficient than lipofectin or DMRIE-C (two commercial cationic lipid transfection reagents) and is active in the presence and absence of serum. The activity in the presence of serum suggests potential for applications in vivo.

3T3 Cells↗
PubMed1998

Phase analysis in high-frequency oscillation.

UNLABELLED: In an oscillating system driven by a sine wave pump, the resonance frequency of the respiratory system can be determined using phase analysis. At resonance frequency, when elastance and inertance cancel out, flow becomes in-phase with resistance. In premature infants with respiratory distress syndrome, owing to surfactant deficiency, localized areas of hyperinflation and collapse develop, resulting in complex changes in overall pulmonary mechanics. We investigated the effect of measuring resonance frequency of the respiratory system by phase analysis at different points of the respiratory cycle: end of inspiration, end of expiration, mid-inspiration and mid-expiration. Ten ventilated premature infants with respiratory distress syndrome were studied, gestational age ranged from 24 to 30 weeks (mean 27.6 weeks) and birth weight ranged from 0.7 to 1.505 kg (mean 0.984 kg). RESULTS: The resonance frequency was consistently higher when measured at the end of inspiration compared with the end of expiration. The expected trend of phase variation, that is, negative below the resonance frequency and positive above, was most consistently found when analysis was done at the end of inspiration. CONCLUSIONS: These findings were most likely a result of the complexity of pulmonary mechanics in the surfactant-deficient lungs, rendering the single compartment model we based our theory on inadequate. However, phase analysis performed at the end of inspiration seemed to produce the most reliable and consistent results.

Biomedical Engineering↗
PubMed1998

Production of digoxigenin-labelled RNA probes and the detection of cytokine mRNA in rat spleen and brain by in situ hybridization.

Non-radioactive in situ hybridization is a sensitive method for determining the site of production for secretory molecules such as cytokines. We report here on the central and peripheral induction of proinflammatory cytokines by endotoxin, and outline procedures for the generation and application of rat-specific digoxigenin (Dig)-labelled RNA probes for the localization of mRNA by in situ hybridization. Rats were injected either intravenously (i.v.) or intracerebroventricularly (i.c.v.) with vehicle or lipopolysaccharide (LPS) and sacrificed at various time intervals post-injection. Rats were then perfused with 4% paraformaldehyde and the spleens and brains were removed and cryoprotected in 30% sucrose. Dig-labelled, rat-specific, antisense and sense RNA probes were generated by in vitro transcription from PCR-derived templates. Positive staining with all the antisense probes was cytoplasmic, whereas the sense probes showed no staining. Numerous tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta) mRNA positive cells were observed in the marginal zone and in the red pulp of the spleen after iv LPS injections, whereas sections from saline-treated animals showed minimal cytokine mRNA expression. Cells positive for TNF-alpha and IL-1beta mRNA were detectable in the brain after i.c.v. injections of LPS, but not after icv injection of vehicle. An antisense probe for c-fos was utilized in these studies as a positive control for our procedure due to its anatomically specific expression in the rat brain after LPS. In conclusion we have demonstrated that in situ hybridization with Dig-labelled RNA probes is an efficient, sensitive and reliable tool to localize cytokine mRNA production in rat tissue.

Actins↗
PubMed1998

Identification of class B and class C floral organ identity genes from rice plants.

The functions of two rice MADS-box genes were studied by the loss-of-function approach. The first gene, OsMADS4, shows a significant homology to members in the PISTILLATA (PI) family, which is required to specify petal and stamen identity. The second gene, OsMADS3, is highly homologous to the members in the AGAMOUS (AG) family that is essential for the normal development of the internal two whorls, the stamen and carpel, of the flower. These two rice MADS box cDNA clones were connected to the maize ubiquitin promoter in an antisense orientation and the fusion molecules were introduced to rice plants by the Agrobacterium-mediated transformation method. Transgenic plants expressing antisense OsMADS4 displayed alterations of the second and third whorls. The second-whorl lodicules, which are equivalent to the petals of dicot plants in grasses, were altered into palea/lemma-like organs, and the third whorl stamens were changed to carpel-like organs. Loss-of-function analysis of OsMADS3 showed alterations in the third and fourth whorls. In the third whorl, the filaments of the transgenic plants were changed into thick and fleshy bodies, similar to lodicules. Rather than making a carpel, the fourth whorl produced several abnormal flowers. These phenotypes are similar to those of the agamous and plena mutants in Arabidopsis and Antirrhinum, respectively. These results suggest that OsMADS4 belongs to the class B gene family and OsMADS3 belongs to the class C gene family of floral organ identity determination.

Cloning, Molecular↗
PubMed1998

Goodness-of-fit tests for the additive risk model with (p > 2)-dimensional time-invariant covariates.

This paper presents methods for checking the goodness-of-fit of the additive risk model with p(> 2)-dimensional time-invariant covariates. The procedures are an extension of Kim and Lee (1996) who developed a test to assess the additive risk assumption for two-sample censored data. We apply the proposed tests to survival data from South Wales nikel refinery workers. Simulation studies are carried out to investigate the performance of the proposed tests for practical sample sizes.

Biometry↗
PubMed1998

Phase II study of carboplatin in blast crisis of chronic myeloid leukemia: Eastern Cooperative Oncology Group Study E1992.

This study was a phase II evaluation of the activity of carboplatin in patients with Philadelphia chromosome positive accelerated or blastic phase of CML. Carboplatin, 250 mg/m2/day as an intravenous continuous infusion was given for 5 days, for a total dose of 1250 mg/m2 per course. If necessary, a second induction course could be given, and patients achieving complete remission were to receive an additional consolidation cycle at the same dose. Thirty-six patients were eligible and evaluable. There were five complete and three partial remissions for an overall response rate of 22% (95% CI 10.1-39.1%). The complete remission rate was 13.9% (95% CI 4.7-29.9%). The median remission duration was 3 months (range 1.4-8.94 months) and the median survival on study for all patients was 3.5 months (95% CI, 2.4-11.4 months). The median survival of responders was 12.8 months (95% CI, 3.6-17.2 months). Three eligible patients survived 2.0, 2.5 and 3.5 years following carboplatin therapy. Carboplatin has activity in blast crisis of CML, but responses are brief. Response did allow one patient to proceed to bone marrow transplantation and two other patients to continue therapy for chronic phase disease before returning to blast crisis. Activity in combination regimens should be explored.

Adult↗
PubMed1998

Relocating elderly people and nursing staff from the NHS to the independent sector.

The results of the study reported here highlight the difficulties and potential problems facing re-provision programmes of mental health services. Relocation of services affects not only patients and staff, it also has implications for the education of staff and managers. Without appropriate preparation for relocation, the potential negative effects for older patients could be life threatening. For the staff, relocation could mean new ways of working for which they may not have been prepared. The current educational format does not appear to be sensitive enough to adapt to the pace of policy changes. The management process of re-provision programmes requires more than financial accounting. Preparation for relocation of patients and staff is of paramount importance to achieve the maximum benefits.

Adult↗
PubMed1998

Influence of carbon monoxide, and its interaction with nitric oxide, on the adrenocorticotropin hormone response of the normal rat to a physico-emotional stress.

We determined whether the gas carbon monoxide (CO) altered the adrenocorticotropin hormone (ACTH) response to mild inescapable electrofootshocks, and whether it interacted with nitric oxide (NO). Peripheral injection of the NO synthase (NOS) inhibitor Nwnitro-L-arginine-methylester (L-NAME), a compound which readily crosses the blood-brain barrier, produced the expected blunting of the ACTH response to the shocks. This effect was mimicked by other arginine analogues such as L-nitroarginine (L-NNA) and NG-methyl-L-arginine (NMMA). The subcutaneous (s.c.) administration of the heme oxygenase (HO) blockers tin mesoporphyrin (SnMP) or tin protoporphyrin (SnPP) significantly decreased brain HO levels, indicating that both compounds had penetrated the brain. Blood pressure showed a modest increase in response to SnMP, and no change after SnPP. SnMP and SnPP both decreased shock-induced ACTH release, though the magnitude of this effect was slightly less than that of L-NAME. The influence of SnPP was further augmented in rats with concomitant blockade of NO formation, which suggests that both NO and CO are necessary for the full response of this axis to electrofootshocks. Finally, the ability of SnPP to significantly blunt the expression of the mRNA for the immediate early gene NGFI-B in the paraventricular nucleus (PVN) of rats exposed to shocks, indicates that the influence of CO was exerted on hypothalamic neuronal activity. Collectively, our results show that NO and CO exert a stimulatory effect on the HPA axis response to mild electrofootshocks, and that at least part of this influence takes place on hypothalamic neurons and/or their afferents.

Adrenocorticotropic Hormone↗
PubMed1998

Immunoblot analysis of a 10 kDa antigen in cyst fluid of Taenia solium metacestodes.

The diagnostic value of a 10 kDa subunit of 150 kDa protein in cyst fluid (CF) of Taenia solium metacestodes was evaluated. Immunoblot analysis revealed that most sera from patients with neurocysticercosis recognized the 10 kDa subunit strongly (209/217 cases, 84.6%), while a few sera from individuals with other parasitic diseases including alveolar echinococcosis (AE, 2/20, 10%) and cystic echinococcosis (CE, 2/25, 8%) showed faint reactions. Sera of cases with other parasitic diseases, especially AE and CE, exhibited cross reactions against other bands in CF. Both differential immunoblot and immunoprecipitation analyses showed that the 10 kDa subunit was the most specific to cysticercosis and highly antigenic, whereas other components at 20-40, 64, 95 and 106 kDa in CF were cross-reactive. IgG subclass ELISA and immunoblot demonstrated that both IgG4 and IgG1 reactions were predominant in neurocysticercosis and recognized the 10 kDa.

Animals↗