Biomedical subjects

W C Lee

Publications and source records attributed to W C Lee.

At least 145 records · Page 8Linked to original sources

PubMed1996

Autoregressive age-period-cohort models.

Age-period-cohort analysis of vital data has received much attention recently, and it is already well known that the exact linear relation of the three time factors creates a non-identifiability problem. Previous studies have shown that the curvature terms of these factors are estimable but the linear trends are not. However, little attention has been paid to the possibility that the effects due to cohort and/or period might change through time stochastically rather than deterministically and hence display a stochastic trend. In this paper, we model the cohort effects as an AR(1) process and use lung cancer mortality data from 1966 to 1990 for males in Taiwan as an example. The parameters are identifiable in the proposed model and the estimates are found to be stable. However, the assumption made in the model should be carefully considered before using our methodology.

Adult↗

PubMed1996

The mitochondria are recognition organelles of cell stress.

The cellular response to stress includes synthesis of specific stress proteins in the presence of a generalized suppression of protein synthesis. The response occurs in intact animals, individually stressed organs of intact animals, donor organs upon removal, regardless of preservation methods, and cells in culture. The molecular biology of stress protein induction is not understood. While stress proteins are beneficial, overall suppression of protein synthesis, if prolonged, is harmful. Since altered energy metabolism is integral to stress induction, we examined the mitochondria to determine if they could provide a possible molecular mechanism for initiating the response. Rat myoblasts were incubated at varying temperatures for up to 120 min in [35 S] methionine. Proteins were separated electrophoretically and newly synthesized proteins visualized autoradiographically. Isolated mitochondria from resting rat myoblasts were then stressed, label incorporation determined, and newly synthesized protein was visualized. Stress sharply suppressed protein synthesis in mitochondria but autoradiograms of stressed mitochondria showed that a single stress protein of 18 kDa was synthesized. Mitochondria independently respond to stress and synthesize a stress protein from their own DNA. This protein may provide an intermediary pathway that links stressful conditions in the environment to the overall response observed in the cell.

Animals↗

PubMed1996

Age-period-cohort analysis of motor vehicle mortality in Taiwan, 1974-1992.

The aim of this study was to examine the effects of age, calendar period of death and birth cohort in motor vehicle mortality in Taiwan over the period 1974-1992. A log-linear model modified from the method of Osmond and Gardner (Stat. Med. 1: 245-259; 1982) was used. Age turned out to be a significant predictor of motor vehicle mortality. The most risky group (over 70 years) had 27.1 and 16.3 times the mortality of the least risky group (5-9 years, 10-14 years) for males and females respectively. The period effect showed a continuously increasing mortality trend since 1974 in females. The pattern in males is similar except that it has slightly leveled off in recent years. The birth cohorts at the highest risk of motor vehicle death were those born between 1979 and 1983 for both sexes. However, males born between 1929 and 1933 also had a high mortality. This analysis provided a better understanding of the trend of mortality from motor vehicle crashes.

Accidents, Traffic↗

PubMed1996

The phenotype and phagocytic activity of macrophages during maedi-visna virus infection.

Macrophages from maedi-visna virus (MVV) infected sheep have been shown to have an activated phenotype from sites of lesions in vivo. Here we have looked at the direct effect of virus infection on macrophage phenotype and activity in vitro by flow cytometry. There was no significant difference in the expression of several surface markers (CD4, CD8, MHC Class I, MHC Class II, lymphocyte function associated antigen(LFA)-1 and LFA-3) on monocyte-derived macrophages (MDM) by 5 days post MVV infection. In contrast the phagocytic activity of MVV-infected MDM for the yeast Candida utilis and erythrocytes was decreased by 5 days p.i. although the surface binding of erythrocytes was not affected. Interestingly, an activated phenotype was seen on alveolar macrophages (AM) from sheep with maedi (surface expression of MHC Class I, Class II and LFA-1 was increased), but there was no difference in the binding and phagocytosis of erythrocytes by these cells. However the binding and phagocytosis of the bacterium, Pasteurella hemolytica was increased with AM from MVV-infected sheep without lesions. Similarly there was no significant difference in the phagocytic and erythrocyte rosetting activity between fresh monocytes from MVV-infected and uninfected control sheep. Therefore the phenotype of macrophages taken from sites of lesions caused by MVV does not correspond to a direct effect by the virus on these cells or to particular activities of the macrophages.

Animals↗

PubMed1996

'Hemostatic pause' in pediatric tonsillectomy?

A randomized prospective study was performed on 101 children undergoing dissection tonsillectomy in two different sequences. In the 'pause' sequence, a period of inactivity lasting 1.5 min ('hemostatic pause') with the Boyle-Davis gag relaxed and the fossae packed with gauze swabs was implemented after the tonsils were excised. Hemorrhage was controlled exclusively by ligatures. The duration of tonsillectomy and the number of ligatures used were accurately recorded. The procedure was identical in the 'no pause' group but the pause period was omitted. No reactionary haemorrhage occurred. There was no significant difference in the operating time between the two groups, but the mean number of ligatures required was significantly reduced in the 'pause' sequence. We conclude that 'hemostatic pause' in tonsillectomy reduces the amount of ligatures needed for satisfactory hemostasis.

Child↗

PubMed1996

An epidemiological study of food poisoning in Korea and Japan.

The purpose of this study was to make a comparative epidemiological observation on outbreaks of food poisoning between Korea and Japan, during the period from 1971 to 1990. The mean morbidity rate by fiscal year from 1971 to 1990 was 3.0 per 100,000 population in Korea, and 29.2 in Japan. The mean mortality rate, in Korea was 2.48%, and in Japan, 0.07%. When both morbidity and mortality rates in Korea and Japan were compared during same period, the morbidity rate in Japan was much higher than that in Korea. However, the mortality rate of patients in Korea was much higher than that in Japan. Comparison of food poisoning rates according to food preparation facilities in Korea and Japan was also performed; outbreaks in Korea most frequently involved home-made foods (48% of the total cases), while in Japan, restaurants accorded for 32.7%. Foods most commonly incriminated in Korea were seafood, meat and animal products, grains and vegetables, including mushrooms. In Japan, however, unknown causes, followed by seafood, vegetables, and meat and animal products were the most common. Food poisoning of bacterial origin in Korea was 58.6% of the total case, including Vibrio spp. (37.6%), Salmonella spp. (23.1%), Staphylococcus spp. (14.9%), pathogenic E. coli (6.8%) Clostridium spp. (0.5%) and other species (17.1%). In Japan, the majority of bacterial causes were Vibrio spp. (47.3%), Staphylococcus spp. (24.6%), Salmonella spp. (14.8%), E. coli (3.5%), Clostridium spp. (0.2%) and other species (9.6%). In conclusion, the outbreaks of food poisoning in Korea and Japan may be mainly caused by food handling, and their occurrence may be different according to food sources.

Disease Outbreaks↗

PubMed1996

Electron microscope studies of the replication of a British isolate of maedi visna virus in macrophages and skin cell lines.

The replication of EV1, a British isolate of maedi visna virus (MVV), in macrophages has not previously been studied. We therefore used transmission and scanning electron microscopy (TEM and SEM respectively) to compare the replication of EV1 in macrophages versus skin cell lines. Monocyte-derived macrophages (MDM), alveolar macrophages (AM) and skin cell lines were all permissive for replication by EV1. Virus grew rapidly and to high titers in skin cell lines and mature MDM. However replication was slower in less mature MDM or AM. Virion budding occurred through (i) cytoplasmic membranes only (skin cells), (ii) cytoplasmic and vesicular membranes (MDM) or (iii) vesicular membranes only (AM). This meant that virions accumulated in vacuoles within macrophages. Retroviral intracytoplasmic type A particles were seen in the cytoplasm of AM and MDM infected with strain EV1, but not MDM infected with strain 1514 (an Icelandic MVV strain) and were shown to contain MVV gag antigen by immunogold staining.

Animals↗

PubMed1996

Stress-induced cervical lesions: review of advances in the past 10 years.

The accumulation of experimental and clinical evidence during the past decade has significantly contributed to the understanding of the role of occlusally generated tensile stress in the etiology of certain noncarious cervical lesions of teeth. More important, this knowledge has led to the understanding of the reasons why traditional restorative treatments of these stress-induced cervical lesions fail. The case of failure can be attributed to the occlusally generated stresses that are concentrated at the cervical region and result in debonding, leakage, retention failure, and, ultimately, restorative failure. With the new understanding, restorative approaches that combine chemical adhesion and restorative materials of appropriate elastic properties show promise of long-term success.

Bite Force↗

PubMed1996

Should nasopharyngeal biopsy be mandatory in adult unilateral glue ear?

Unilateral secretory otitis media is a recognized presenting feature of nasopharyngeal neoplasia. In the two cases presented, biopsy from the nasopharynx revealed an unsuspected underlying adenocarcinoma. The need to biopsy the normal looking post-nasal space is highlighted.

Adenocarcinoma↗

PubMed1996

Complications of paediatric tonsillectomy post-discharge.

A post-operative survey of 291 children was conducted to assess morbidity found at home in the first five days post-tonsillectomy. Analgesic requirement (92.4 per cent), signs of distress (90.4 per cent), otalgia (69.1 per cent), halitosis (66.7 per cent) were common. Physical or behavioural changes (36.8 per cent) and secondary haemorrhage (8.9 per cent) were also prominent features. Nausea was reported in 59 children (20.3 per cent) and delayed return to a normal diet which in turn predisposed to secondary haemorrhage. Return to normal diet was independent of pain. General Practitioners were consulted by 60.6 per cent and more than half were prescribed drugs. The presence of an organized clot in the tonsillar fossa (3.45 per cent) post-operatively did not delay discharge from hospital and none of these patients re-presented with secondary haemorrhage. Based on their child's experience in this study, only one third of the parents approved of day-case tonsillectomy in principle, a finding which has implications for the instigation of day-case tonsillectomy procedures.

Acetaminophen↗

PubMed1996

An audit of prophylactic antibiotic treatment following tonsillectomy in children.

A prospective audit study was undertaken to assess the effect of two different management policies following tonsillectomy in children in this hospital, one of which requires a prophylactic five-day course of oral antibiotics and the other doses not. A total of 95 children were entered into the trial: 54 received post-operative antibiotics and 41 did not. The post-operative recovery was assessed by completion of a parent questionnaire which included the following parameters: degree of patient distress, nausea and vomiting, otalgia, halitosis, pharyngeal bleeding, analgesic requirement, day of return to a regular diet and General Practitioner consultation. There was no significant reduction in any of the morbidity measures in patients treated with antibiotics. I fact, the analgesic requirement and the incidence of otalgia and irritability on Days 6 and 7 and secondary haemorrhage were significantly higher in the antibiotic-treated patients. Although the number of patients included in this study are small, the result suggest that post-operative antibiotics do not improve the outcome of uncomplicated tonsillectomy. Our previous practice of routinely administering antibiotics to post-tonsillectomy children has been discontinued as the consequence of this audit.

Adolescent↗

PubMed1996

Recurrent frontal sinusitis complicating orbital decompression in Graves' disease.

An unusual case of recurrent frontal sinusitis with abscess formation secondary to orbital decompression for Graves' disease is described. The infection was refractory to antibiotics treatment, external drainage and the sinus obliteration procedure. Since the sinus outflow was obstructed by prolapsing tissue following excessive removal of the orbital walls, sinus re-aeration by supporting the prolapsed tissue with a silastic sheet and stenting the sinus drainage tract was attempted. This led to a complete resolution of the infection with an excellent long-term result.

Adult↗

PubMed1996

Cowpox infection of the nose.

A case of cowpox infection presenting as a necrotising cellulitis of the nasal tip and vestibule is reported. Diagnosis was established by identification of the pox virus particles from tissue culture of the nasal biopsy using electronic microscopy and the characteristic lesions on chorio-allantoic membrane produced by the virus. Cowpox of the external nose and transmission of the infection from a dog have not to our knowledge been reported previously.

Adult↗

PubMed1996

Squamous cell carcinoma of the pharynx and larynx presenting as a neck abscess or cellulitis.

Head and neck tumours presenting as a neck abscess or cellulitis are extremely rare. We report two cases of supraglottic squamous cell carcinoma which presented as an abscess in the site of metastatic neck nodes, one of which was occult and a third case of squamous cell carcinoma of the pyriform fossa which presented as cervical cellulitis. Biopsy of the abscess wall at the time of drainage and careful follow-up may lead to an earlier diagnosis of occult carcinoma.

Abscess↗

PubMed1996

Anaplastic thyroid carcinoma presenting as a pharyngeal mass with ball-valve type obstruction of the larynx.

Thyroid tumours can compromise the airway by extrinsic compression or invasion of the trachea or larynx and damage to the recurrent laryngeal nerve. In this report, the pedunculated extension of a large anaplastic thyroid carcinoma penetrated through the posterior hypopharyngeal wall causing a partial ball-valve type obstruction of the laryngeal inlet on inspiration. This unusual pattern of invasion has not been reported previously.

Aged↗

PubMed1996

Analysis of seasonal data using the Lorenz curve and the associated Gini index.

BACKGROUND: Epidemiological inferences about the aetiology of a disease can often be made from its seasonal patterns. However, due to its multifactorial nature, the seasonality component can be obscured by other factors. It is therefore important to develop statistical techniques which are sensitive to minute temporal changes. METHODS: The Lorenz curve and the associated Gini index are applied for characterizing and testing seasonal variations. Computer simulations were conducted to compare the powers of the Gini test and other seasonality tests. We also show that the Gini index can itself be interpreted as a probability related to temporal clustering. RESULTS: The powers of the proposed tests are shown to be higher than or at least comparable to other tests under various conditions. CONCLUSIONS: Though computer-demanding, the proposed method is well-suited for analysing seasonal data.

Anencephaly↗

PubMed1996

Substantial decrease of heat shock protein 90 in ventricular tissues of two sudden-death pigs with hypertrophic cardiomyopathy.

We recently developed a pig model with naturally occurring hypertrophic cardiomyopathy (HCM). To further characterize the biochemical features of high frequency of sudden death affected by this disease, the protein profiles of ventricular tissues were analyzed on normal, HCM, and HCM with sudden-death pigs. By sodium dodecylsulfate-polyacrylamide gel electrophoresis, a protein corresponding to an apparent molecular mass of 90 kDa (p90) was found to be markedly decreased in the HCM-affected tissues of sudden-death pigs, but not in HCM or normal pigs. Further study showed that the primary decrease of p90 in HCM pigs with sudden death was located mainly in the interventricular septum. As determined by the molecular mass and isoelectric point on 2-dimensional gels and Western immunoblot with a specific 90 kDa heat shock protein (HSP90) monoclonal antibody, the unknown protein was identified as HSP90. Our findings indicate for the first time that substantially decreased heart HSP90 is associated with HCM pigs with sudden death. Although the role that HSP90 may play in protecting pigs with HCM from sudden death is still nuclear, the model itself may provide further insight into understanding the role of heat shock proteins in cardiac sudden death.-Lee, W.-C., Lin, K.-Y., Chiu, Y.-T., Lin, J.-H., Cheng, H.-C., Huang, H.-C., Yang, P.-C., Liu, S.-K., Mao, S. J. T. Substantial decrease of heat shock protein 90 in ventricular tissues of two sudden-death pigs with hypertrophic cardiomyopathy.

Animals↗

PubMed1996

Alternative summary indices for the receiver operating characteristic curve.

The receiver operating characteristic curve (ROC) and its associated summary index, the area under the curve (AUC), have recently found an increasingly popular place in medical diagnosis and population screening surveys. Nevertheless, the index may erroneously rate a perfect or nearly perfect marker as having no diagnostic or screening value. In this paper, we propose two new summary indices, the projected length of the ROC curve (PLC) and the area swept out by the ROC curve (ASC), to summarize the ROC curve. Like the conventional AUC, these new indices both have clear probabilistic interpretations and are easily defined geometrically. In addition, they do not suffer from the shortcoming of the AUC. These properties render them good alternatives for evaluating the overall performance of a diagnostic or screening test.

Area Under Curve↗