Search PubMed⌕ Search

Biomedical subjects

S Lee

Publications and source records attributed to S Lee.

At least 1,081 records · Page 60Linked to original sources
PubMed1993

Flexible technique for multiple organ procurement in rats: a training and research tool in transplantation.

Multiple organ procurement techniques are increasingly popular in many transplant centers. This paper describes a technique for multiorgan unit(s) explantation in rats. The procedure involves in situ preliminary dissection, cold perfusion of the thoracic and abdominal organ units as separate procedures, explantation, and finally the ex situ isolation of various organ units as single and/or multiple organ combination units. The procedure is feasible, allows for flexibility in the separation of combination organ units, and is reproducible. The exercise is provided as a training and research tool for clinical and research transplant surgeons. The technique is also presented as an animal model for clinical organ sharing.

Animals↗
PubMed1993

Parathyroid hormone-related protein (PTHrP) gene expression in solid tumours associated with normocalcaemia and hypercalcaemia.

Parathyroid hormone-related protein (PTHrP) is an important humoral factor in the syndrome of humoral hypercalcaemia of malignancy (HHM) and its importance is evident by the many studies examining either PTHrP mRNA expression, intracellular peptide, or circulating PTHrP levels in patients with malignancy. However, the relationship between PTHrP mRNA expression, intracellular localization of peptide, and circulating PTHrP levels in the same group of patients with malignancy has not been examined. This study was carried out to explore this relationship in a group of patients with solid tumours associated with either normocalcaemia or hypercalcaemia. PTHrP mRNA and peptide were localized by in situ hybridization and immunohistochemistry respectively in 26 squamous carcinomas and 15 adenocarcinomas from patients who were either hypercalcaemic or normocalcaemic. Plasma PTHrP1-86 and serum PTH1-84 concentrations were measured by two-site immunoradiometric assays. PTHrP mRNA and peptide were localized in 11 (100 per cent) and 10 (91 per cent) of 11 squamous tumours from hypercalcaemic patients, all of whom had detectable circulating PTHrP levels, and in 14 (97 per cent) and 11 (73 per cent) respectively of 15 squamous tumours from normocalcaemic patients. PTHrP mRNA and peptide were localized in only two (28 per cent) and four (57 per cent) respectively of seven adenocarcinomas associated with hypercalcaemia. Since the majority of squamous tumours synthesized PTHrP irrespective of the calcium status of the patient, this suggests that the clinical expression of tumour-derived PTH-like bioactivity may depend on the rate of secretion of PTHrP rather than gene expression, and that the bioactivity of secreted PTHrP may be modulated by post-translational processing.

Adenocarcinoma↗
PubMed1993

Changes in the host range and growth potential of an HIV-1 clone are conferred by the vpu gene.

vpu, alone among the genes of human immunodeficiency virus type 1 (HIV-1), is unique to this virus, with no analogous reading frame evident in the genomes of either HIV-2 or the related SIVs. Effects of vpu upon levels of virus production from infected cells have been noted, but vpu is dispensable for HIV-1 replication in vitro and its significance in the natural viral life cycle is unclear. We have now identified and characterized a major influence of vpu upon the growth and host cell range of a cloned recombinant HIV-1. This effect required the presence of a second determinant mapping to the 3' end of the env gene, and was not detected in clones incorporating an env gene derived from a different strain of the virus. This indicates that important effects of vpu may have been lost in some experimental systems because of the particular viruses used, and further suggests the involvement of a determinant in the transmembrane glycoprotein of the virus in the action of vpu.

Cell Line↗
PubMed1993

Amplitude and frequency measures of surface electromyography during dual task elbow torque production.

Studies of motor unit recruitment thresholds have demonstrated the existence of task-specific motor units within the muscles controlling the elbow. Two degree-of-freedom (df) task specificity was investigated at higher levels of elbow torque using the amplitude and frequency characteristics of surface electromyography (EMG). Flexion and supination torque data were collected together with EMG from electrode pairs on the brachioradialis (BRAD), biceps brachii short head, and medial and lateral aspects of biceps brachii long head, while subjects (n = 14) performed the following four combinations of isometric tasks: (1) maximum voluntary contraction (MVC) flexion (F) and (2) MVC supination (S), each with a targeted torque of zero in the second df; (3) MVC flexion with targeted MVC supination (FS); and (4) MVC supination with targeted MVC flexion (SF). Median power frequency (MEDF) and root mean square (RMS) amplitude under steady-state torque conditions were calculated and analyzed using ANCOVA models with planned contrasts (alpha = 0.05). A significant main effect for task was found in RMS, but not in MEDF. Contrasts showed a significant increase in RMS response in the dual MVC tasks (FS and SF) over the single MVC tasks of F and S. The lack of frequency changes with alterations in RMS data indicates that the underlying recruitment/rate coding scheme in use for dual-df tasks may be different than in single-df tasks, and provides possible support for the notion of motor unit task groups. Task-by-site interactions were found for both MEDF and RMS, and illustrated that the three biceps sites differed from BRAD in their responses to the F versus S tasks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effects of diflubenzuron and clanfenur on mouse bone marrow cells.

Diflubenzuron (DFB) and Clanfenur (CFN) belong to a group of compounds called Benzoylphenyl Ureas (BPUs). Several BPUs regulate cell growth in insects and/or inhibit growth of B-16 murine melanomas. In view of potential clinical use for these compounds, DFB and CFN were selected as examples of BPUs and tested for effects on hematopoiesis in C57Bl/6 mice housed in a conventional environment. DFB and CFN exhibit anti-tumor activity in mice, cause little or no morbidity and mortality and rather than causing bone marrow suppression, which is usual for anti-cancer drugs, these agents stimulate hematopoiesis in vivo and in vitro. Stimulation in vivo was evidenced by increased (up to 112%) peripheral blood granulocytes 6 days after a single injection and enhanced granulopoiesis (approximately 25%) in bone marrow up to 18 days after treatment. That effects of DFB and CFN were on hematopoietic stem cells were indicated by 47% and 48%, respectively, increases in numbers of CFUs and 97% and 95%, respectively, increases in CFUgm. Further, bone marrow cells treated in vitro contained about twice the number of CFUs and CFUgm as control bone marrow cells. Almost all of the increase in number of spleen colonies, whether derived from donors treated in vivo or bone marrow cells treated in vitro, was accounted for by a corresponding increase in number of undifferentiated colonies. These data indicate that DFB and CFN treatment enhance numbers of pluripotential stem cells both in vivo and in vitro. The mechanism of enhancement, direct or indirect, remains to be determined.

Animals↗
PubMed1993

Side effects of chronic lithium therapy in Hong Kong Chinese: an ethnopsychiatric perspective.

A biocultural study of the side effects of chronic lithium treatment among 70 Hong Kong Chinese psychiatric patients, using a self-report 33-item checklist and semi-structured interviews, revealed an imperfect correspondence between biomedically prescribed and culturally endorsed psychotropic side effects. Although polydipsia and polyuria (47%) were the biomedically most 'real' side effects, they were not usually regarded as bothersome or translated into metaphors to express undesirable side effects. Complaints such as tiredness (38%), drowsiness (36%) and poor memory (31%) were also common but their frequency was significantly lower than that of normal control subjects. The item 'loss of creativity' had no conceptual equivalent in Chinese and was usually misinterpreted. As no patient was aware that lithium was a metal, the side effect 'metallic taste' was variously labelled. Contrary to Western findings, complaints of 'missing of highs', loss of assertiveness and fear of weight gain were rarely encountered. Active elicitation was required for indigenous complaints, with 38% of patients considering lithium to cause mild "hotness." This was readily neutralized by drinking more water which had a "cooling" effect. Expectedly, concurrent neuroleptics and antidepressants amplified most lithium side effects. This study affirms Western data on the biomedically universalizable effects of chronic lithium treatment, but also supports the thesis that culturally constituted cognitive styles affect patients' recognition, labelling, experiencing and reporting the total drug effect. Further, it demonstrates that the lived experience and clinical negotiation of lithium associated side effects reproduce, authenticate, and at times critique, core cultural and moral premises of Western and Chinese societies.

Adolescent↗
PubMed1993

Ultrastructure of endothelial cell necrosis in classical erythema nodosum.

As evidence of vascular involvement in classical erythema nodosum unassociated with Behçet's disease, the occurrence of endothelial cell necrosis based on the development of dark cell degeneration was observed by electron microscopy in the vasculature of the dermis and subcutaneous fat. The incidence of endothelial cell necrosis in all segments of the microcirculatory system was roughly 20% in three of 12 patients. The remaining nine patients showed a very low rate of necrosis, including two patients in whom endothelial cell necrosis was totally absent. The presence of necrotic endothelial cells that are forced out and eliminated by neighboring intact endothelial cells into the vascular lumen is closely associated with thrombus formation in the cutaneous vasculature. The incidence at which endothelial cell necrosis occurs in classical erythema nodosum is not always high; however, it is concluded that endothelial cell necrosis may play a significant role in the pathogenesis of erythema nodosum.

Adult↗
PubMed1993

New reagents for spectral titration of active site of chymotrypsin.

The reaction of alpha-chymotrypsin (ChT) with 2-phenyl-(E)-[4-(E)-cinnamylidene]oxazolin-5-one (E-PCO) or 2-phenyl-(Z)-[4-(E)-cinnamylidene]oxazolin-5-one (Z-PCO) at pH 4.5 and 25 degrees C led to the quantitative accumulation of the corresponding acyl-ChT intermediate. Very large changes in molar extinction coefficient were observed in the visible region during the conversion of the oxazolinones to the acyl-ChT intermediates. This afforded a reliable method for the spectral titration of ChT in the visible region. Both E-PCO and Z-PCO were stable under these conditions and did not cause any complication in the titration of the active site.

Chymotrypsin↗
PubMed1993

Apoptosis and signal transduction: clues to a molecular mechanism.

Apoptosis, or programmed cell death, plays an essential role in specific cell deletion during normal embryonic and adult development in vertebrate and invertebrate species. Recent evidence suggests that signal transduction pathways governing cellular proliferation and cell cycle progression also mediate the physiological response to changes in the extracellular environment that trigger the anti-proliferative state characteristic of apoptosis.

Animals↗
PubMed1993

Direct percutaneous pouch cystostomy with endoscopic lithotripsy for calculus in a continent urinary reservoir.

Continent urinary reservoirs are an accepted mode of urinary diversion in appropriate patients. Such procedures are associated with long-term complications. A patient who underwent a continent urinary diversion (modified Indiana pouch) 4 years ago for a neurogenic bladder presented with a large irregular calculus in the pouch. Endoscopic attempts to remove the calculus through the stoma were unsuccessful and extracorporeal shock wave lithotripsy failed to fragment the pouch calculus. Finally, an endoscopic approach through a direct percutaneous pouch cystostomy, and use of ultrasonic and electrohydraulic probes resulted in successful fragmentation and removal of the calculus.

Adult↗
PubMed1993

Fat phobic and non-fat phobic anorexia nervosa: a comparative study of 70 Chinese patients in Hong Kong.

A mixed retrospective-prospective study of 70 Chinese anorexic patients in Hong Kong shows that although they were similar to Western anorexics in most other ways, 41 (58.6%) of them did not exhibit any fear of fatness throughout their course of illness. Instead, these non-fat phobic patients used epigastric bloating (31.4%), no appetite/hunger (15.7%) or simply eating less (12.9%) as legitimating rationales for food refusal and emaciation. Compared to fat phobic anorexics, they were significantly slimmer pre-morbidly (P < 0.0001) and were less likely to exhibit bulimia (P = 0.001). The possible explanations for the absence of fat phobia and the interpretive dilemma this provokes are discussed from historical, pathoplastic and cultural anthropological perspectives. It is argued that anorexia nervosa may display phenomenological plurality in a Westernizing society, and its identity may be conceptualized without invoking the explanatory construct of fat phobia exclusively. As non-fat phobic anorexia nervosa displays no culturally peculiar features, it is not strictly speaking a Western culture-bound syndrome, but may evolve into its contemporary fat phobic vogue under the permeative impact of Westernization. Its careful evaluation may help clarify the aetiology and historical transformation of eating disorder, foster the development of a cross-culturally valid taxonomy of morbid states of self-starvation, and exemplify some of the crucial issues that need to be tackled in the cross-cultural study of mental disorders.

Adult↗
PubMed1993

How abnormal is the desire for slimness? A survey of eating attitudes and behaviour among Chinese undergraduates in Hong Kong.

Using the 40-item Eating Attitudes Test and other self-report questions, a two-stage screening survey of 1020 (F 646, M 374) Chinese bilingual university students in Hong Kong showed that although female students were 'underweight' by Western standard, the majority of them and nearly all female students above a body mass index of 20.5 kg/m2 were cognitively inclined to diet and weigh less, albeit without being driven to actual weight control behaviour. In contrast, most male students and a minority of constitutionally thin female students clearly wished to gain weight. While a number of items were culturally inappropriate, factor analysis supported the overall cross-cultural conceptual validity of the EAT. The principal factor, reflecting dieting concerns, correlated positively with the current body mass index. Among the high scorers, only three female students with partial syndrome bulimia nervosa were identified, yielding a low prevalence of 0.46% for the spectrum of eating disorders. It is argued that the desire for slimness is widespread but its intensity and pathogenic potentiality vary across cultures. In the relative absence of obesity, it may not lead to more eating disorder.

Adolescent↗
PubMed1993

Lithium-associated transient thyrotoxicosis in 4 Chinese women with autoimmune thyroiditis.

Four Chinese female patients who suffered from manic-depressive disorder and underlying autoimmune thyroiditis developed transient episodes of thyrotoxicosis during maintenance lithium therapy. Endocrinologically speaking, three of them had "Hashitoxicosis", while the other had silent lymphocytic thyroiditis. Albeit rare among Western patients, such lithium-associated thyroid dysfunctions appeared to be more likely to occur in Hong Kong Chinese. They seemed to involve multiple aetiological factors, such as autoimmune thyroid disease, the toxic and immunomodulatory roles of lithium and perhaps genetic and dietary factors. Because of their self-limiting nature, the importance of avoiding unnecessary and potentially deleterious antithyroid treatment is emphasised.

Adolescent↗
PubMed1993

In vivo kinematics of the cervical spine. Part I: Development of a roentgen stereophotogrammetric technique using metallic markers and assessment of its accuracy.

A technique for simultaneous roentgen stereophotogrammetry (RS) was developed, and its accuracy was assessed. In vitro models fabricated from dried cadaveric C4 and C5 vertebrae were used to simulate the motion behavior of the cervical spine. Metallic markers made of Vitallium beads (diameter < 0.3 mm) were implanted into the posterior and anterior surfaces of each vertebra at surgically accessible locations to simulate the bead placement for both posterior and anterior surgical approaches to the cervical spine. A series of roentgen stereo pairs were obtained to systematically assess the accuracy (validity) of displacement measurements in anteroposterior (AP) translation, axial rotation, and flexion/extension. In addition, the effects of soft tissue density on the accuracy of the system were investigated by obtaining a series of roentgen stereo pairs with the experimental model immersed in a water bath. The coordinates of the metallic markers on the radiographs were then digitized by two raters who were not informed of the actual motion (i.e., blind study). The results indicated a high accuracy throughout the study. Overall root mean square errors were 0.07 mm for AP translation, 0.08 degrees for axial rotation, and 0.14 degrees for flexion/extension. The corresponding accuracy estimates (R2 values by linear regression analysis) were very high (0.992, 0.998, and 0.995) when the measurement results were compared with the actual displacements. The water bath did not affect measurement accuracy, indicating that soft tissue density should have little effect on the accuracy of the technique for in vivo applications. This system appears to be an accurate and reliable method for assessment of simulated in vivo cervical spine motion, regardless of the rater. The technique has been further used in in vivo assessment of cervical spine kinematics in one patient to confirm the efficacy of the developed technique.

Atlanto-Axial Joint↗
PubMed1993

The prevalence and nature of lithium noncompliance among Chinese psychiatric patients in Hong Kong.

Based on the multiple criteria of serum lithium level, patients' subjective report and doctors' impression in the previous year, a noncompliance rate of 30% was found among 50 Chinese patients on chronic lithium treatment in Hong Kong. Of numerous variables analyzed, only lithium monotherapy, younger age, and earlier age of onset were significantly associated with noncompliance. Exploratory interviews documented the multidimensionality of lithium noncompliance. They argued against statistical attempts to establish a universal clinical formula for the prediction of lithium noncompliance, and underscored the personal, social and medical contexts in which illnesses were lived and treatments used. For cultural reasons, familiar Western rationales for legitimating lithium noncompliance, such as missing of highs, loss of assertiveness, loss of creativity, and excessive fear of weight gain, were rarely encountered. After 1 1/2-years of attendance and with specific interventions at the lithium clinic, the noncompliance rate decreased from 30% to 14%. The important role of a parent-child-dominated Chinese kinship system in the chronic care of psychiatric patients is also discussed.

Adolescent↗
PubMed1993

Reduction by combination prophylactic therapy with CMV hyperimmune globulin and acyclovir of the risk of primary CMV disease in renal transplant recipients.

CMV-seronegative recipients of kidneys from CMV-seropositive donors (D+/R+) are at highest risk for developing clinical CMV disease. Even with routine prophylactic use of low-dose acyclovir we had a CMV disease incidence of 26% (5/19) in these patients. Published studies using either acyclovir or CMV hyperimmune globulin (HIG) alone as prophylaxis have also shown clinical disease in 20-30% of D+/R+ patients--less than controls but still significantly greater than in comparable CMV+ recipients (R+). The purpose of this study was to determine whether the risk of primary CMV disease in D+/R- patients was reduced by prophylaxis with combined CMV-HIG and low-dose acyclovir as follows: CMV-HIG (Immuno) 1 ml/kg i.v. immediately prior to transplantation and at 3-week intervals for 6 months; acyclovir 600 mg/day p.o. for 3 months. A total of 361 consecutive renal transplants were studied prospectively. All D+/R- pts (n = 73) received CMV-HIG and acyclovir, the others (91 D+/R+, 74 D-/R+, 123 D-/R-) received only low-dose acyclovir. The incidence of clinical CMV disease, CMV-related graft loss, graft and patient survival, and the influence of ALG and OKT-3 were analyzed and compared between groups. Of the 361 patients only 18 (5%) developed CMV disease, with 5 CMV-related graft losses. CMV disease occurred in only 10% of the D+/R- patients, lower than in previously reported studies. Significantly the incidence was as low as in CMV+ recipients of kidneys from both CMV+ (6%) and CMV- (7%) donors. Use of OKT-3 for steroid-resistant rejection increased the risk of developing CMV disease: 11/50 (22%) receiving OKT-3 developed CMV disease vs. only 7/311 (2%) who did not (P < 0.001); 11/18 (61%) with CMV disease had received OKT-3. ALG induction immunosuppression did not increase the risk of CMV in patients who subsequently received OKT-3. No patient developed CMV disease after discontinuing prophylaxis. There were no complications related to either CMV-HIG or acyclovir use. Compared with all other patients, the D+/R- group had superior graft survival at 1 and 3 years (94% vs. 87% and 86% vs. 74%, P < 0.05) but similar patient survival. Combined CMV-HIG and low-dose acyclovir appear to be better than either agent alone in preventing primary CMV disease in CMV- patients who receive CMV+ kidneys. Low-dose oral acyclovir (600 mg/day) may be as effective in preventing CMV disease as higher-dose prophylactic regimens, at least when accompanied by CMV-HIG.(ABSTRACT TRUNCATED AT 400 WORDS)

Acyclovir↗