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Biomedical subjects

P Yan

Publications and source records attributed to P Yan.

52 records · Page 3Linked to original sources

[Analysis of 110 cases of sacrococcygeal lesions in children].

110 cases of sacrococcygeal lesions seen in the Guangzhou Children's hospital were reviewed. 42 cases were anomalies, 66 cases were tumors and 2 were inflammatory granulomas. As compared to data in western literatures, the morbidity of anomalies in this series was lower than that of tumors, whereas in western reports the morbidity of anomalies was much higher than that of tumors. Another interesting point was that the morbidity of meningocele (MC) in this series was much higher than that of myelomeningocele (MMC) of spina bifida (7:1). According to a study in Australia, the MC:MMC was 1:5. We suggest that endodermal sinus tumor should be considered as an independent entity of there was no other tissue component (organlike component) found in tumor section. We also suggest that if neuroblastoma and/or other immature neuroectodermal component is observed in a teratoma, it should be classified as malignant rather than benign.

Child, Preschool↗

Multi-state Markov models for analysing incomplete disease history data with illustrations for HIV disease.

Multi-state Markov models can be useful in analysing disease history data. We apply the general estimation methods of Kalbfleisch and Lawless to panel data in which individuals are viewed over only a portion of their life history and complete information about transition times between states is unavailable. Methods to assess goodness-of-fit are proposed. To illustrate the methods, we consider models of HIV disease relating important immunological marker measurements to the onset of AIDS.

Acquired Immunodeficiency Syndrome↗

[Cardiotocography admission monitoring and intermittent intrapartum monitoring for fetal distress in labour].

Cardiotocography (CTG) monitoring on admission was performed in 71 patients for 30 to 60 minutes in a semilateral position. Intermittent intrapartum CTG monitoring were performed in 40 of these patients. Admission monitoring might provide information of fetal basic status and predict asphyxia that could develop during labour. There was less intrapartum asphyxia, lower Apgar score, umbilical artery pH < or = 7.10 and meconium stained amniotic fluid in high-score group than that in medium-score group and low-score group (P < 0.05). Admission monitoring had high predictive value of umbilical cord complication in labour and enable to detect them in the early first stage of labour. Fischer's composite score of FHR of admission monitoring was closely related to that of intermittent FHR monitoring in the late first stage of labour. In this study, it is suggested that admission monitoring is a useful, simple, convenient and noninvasive method for screening fetal basic condition. When continuous FHR monitoring is not available, the intermittent intrapartum FHR monitoring in the late first stage of labour is of importance.

Cardiotocography↗

Intravascular hemolysis after mitral valve repair: a word of caution.

The case of a young patient who presented with severe hemolysis after mitral valve repair is presented. Valve repair included chordal shortening, transposition of chordae tendinae, and annular remodelling using a Duran flexible ring. Reoperation and valve replacement were required to control hemolytic anemia. The possible mechanisms leading to such an uncommon complication after plastic repair of the mitral valve are commented on. The scanty literature concerned is reviewed.

Adult↗

A review of patients with a 'normal' coronary angiogram over a 3-year period.

Over a period of 36 months, we detected 54 patients with normal coronary arteries or non-critical coronary artery stenosis within our study series of coronary angiography. We studied these patients to determine their clinical, electrocardiographic, stress testing and angiocardiographic characteristics. We detected among them a preponderance of female sex and a higher incidence of ethnic Indians. The majority of the patients studied had one or more coronary risk factors. 52% had a normal resting ECG. In those with a positive stress test and reports available for review, there is a near equal distribution of horizontal and J-type ST depression. Those patients with a positive treadmill tend to have a higher left ventricular end diastolic pressure (LVEDP) at cardiac catheterization. We also noted in this group of patients a higher proportion with a small distal left anterior descending artery. These patients also tend to have higher LVEDP even in the presence of normal left ventriculogram. Our current series suggests the possibility of raised left ventricular end-diastolic pressure and the presence of a "small distal left anterior descending artery" syndrome in association with patients with a 'false positive' treadmill test.

Adult↗

Lipid screening in a volunteer population in Singapore.

Coronary risk profile screening was performed in 1065 volunteers during the National Heart Week 1988 as part of the National Heart Association's campaign against the increasing incidence of ischaemic heart disease. Of particular importance was the use of a desktop analyser for lipid screening of total cholesterol and high density lipoprotein (HDL) cholesterol. It was found that the mean serum cholesterol was 211 +/- 39.5 mg/dl, with 62% of the participants having a total cholesterol greater than 200 mg/dl and 23.1% having a total cholesterol greater than 240 mg/dl. For HDL cholesterol, the mean was 48.4 +/- 17 mg/dl, with 18.7% of the participants having a low HDL cholesterol of less than 35 mg/dl. The male Indians had a significantly lower HDL cholesterol compared to male Malays. Three or more risk factors for coronary artery disease was present in 21.7% of Chinese, 41.2% of Malays and 50% of Indians. We conclude therefore that a proportion of this volunteer population, the majority of which have no overt heart disease, is at risk from coronary artery disease from an elevated cholesterol or low HDL cholesterol level. A follow-up of 90 participants who were initially detected to have an elevated cholesterol in 1986, however, showed that only 54.4% still had an elevated cholesterol of greater than 240 mg/dl, thus suggesting that early detection may help to reduce this risk.

Age Factors↗

[Demonstration of intrahepatic HBsAg and HBcAg in chronic liver disease by double staining].

Expression and distribution of intrahepatic HBsAg and HBcAG were studied by double staining immunohistochemical assay in chronic liver disease. HBsAg was homogenously cytoplasmic in typing in 41 and HBcAg was cytoplasmic-membranous in 31 of 46 cases which were known to be positive for both HBsAg and HBcAg intrahepatically. The expressing sites of both HBsAg and HBcAg in 40 of the 46 cases were found to be positive in the same areas of the sections. Interestingly, it was found that intrahepatic HBsAg and HBcAg were often coexistent in the same hepatocyte, and these hepatocytes were considered to be further classifiable into type I and type II according to their distribution. The detective rate of type II cell was significantly higher during the HBV replication stage serologically. HBsAg and HBcAg coexpression in cytoplasm of hepatocyte was noticed to be closely related to active pathological change of the liver cells.

Hepatitis B↗

The cytoplasmic HBVDNA implication: HBV replication or non-replicative status.

Intrahepatocellular HBVDNA was investigated in patients with chronic hepatitis B by in situ hybridization assay, employing biotin-labelled HBVDNA as the specific probe. It was found that HBVDNA was predominantly present in the cytoplasm of hepatocytes. In general the cases with cytoplasmic HBVDNA could be grouped as follows: 1) cytoplasmic HBVDNA coinciding with intrahepatic envelope protein and nucleocapsid component expression, this pattern of the cytoplasmic HBVDNA would be replicative; 2) cytoplasmic HBVDNA accompanied by intrahepatic single HBsAg expression, common to HBVDNA integrated into host genome with only HBsAg being found frequently in liver; 3) with only cytoplasmic HBVDNA, with neither HBsAg nor HBcAg expression, representative for non-replicative status. It is speculated that the reason for the occurrence of the cytoplasmic hybridization signal in cases with non-replicative HBVDNA may be due to DNA-RNA transcript hybrid. The prudent way to evaluate the implication of the cytoplasmic HBVDNA is to consider the combination of HBVDNA location, intrahepatic gene product expression, and HBV markers in the serum.

Cytoplasm↗

Intrahepatic HBVDNA replication and gene products expression correlated with foci of hepatic necrosis.

Intrahepatic HBVDNA of patients with chronic hepatitis B was detected by in situ cytohybridization assay in combination with demonstration of HBsAg and HBcAg expression, and correlated with the foci of hepatic necrosis. It was found that HBsAg and HBcAg expressing sites appeared in the same areas where HBVDNA replicated; when HBsAg and HBcAg simultaneously expressed in the liver, one antigen usually dominated, the other declined. This unbalanced expression may be caused by the gene or transcripts variance which encodes the surface or core antigen, or by the activity of each replication. The other observation is that HBVDNA-positive hepatocytes outnumbered liver cells containing HBsAg and HBcAg in a few cases. It is supposed that a part of cytoplasmic HBVDNA was on replicative phase with gene production expression, on the contrary, another part of cytoplasmic HBVDNA may be out of replication with no gene product expression during chronic hepatitis B. Finally HBsAg and HBcAg expressing sites corresponding to HBVDNA-positive hepatocytes were closely attached to the foci of hepatic necrosis. There was no significant difference in the frequency of HBsAg and HBcAg expression correlating to hepatic necrosis.

DNA Replication↗

Comparison of pre-S1 and pre-S2 proteins in hepatocytes with replication by in situ hybridization assay.

To compare the relationship of pre-S1 and pre-S2 proteins in hepatocytes with HBV replication, HBVDNA in situ hybridization was performed for a group of patients with chronic hepatitis by bio-probe, in conjunction with detection of intrahepatic HBsAg, HBcAg, pre-S1 and-S2 antigens. It was found that the expression of intrahepatic pre-s1 and pre-S2 proteins was visualized as cytoplasmic homogeneous and inclusion types, on some occasions as membranous localization. However, the positive rate for pre-S1 protein was up to 75% (15/20), being significantly higher than that of pre-S2 protein (35%; 7/20) in the same group (P less than 0.05). What in more important, the pre-S1 expression, rather than pre-s2, was in parallel with the presence of intrahepatic HBVDNA and HbcAg. All these findings suggest that the pre-S1 protein might be mainly expressed at the HBV replication phase, thus, to some extent, the detection of pre-S1 protein might complement HBe system and HBVDNA clinical routine.

Biomarkers↗

Morphology, distribution and its significance of intrahepatic HBV DNA in liver disease: a study by in situ hybridization.

A biotin-labeled DNA probe specific for hepatitis B virus (HBV) nucleotide sequences was hybridized in situ to liver tissue of 129 cases with liver disease. It was found that HBV DNA was predominantly visualized in cytoplasm of hepatocytes in three patterns: cytoplasmic compact, discrete and inclusion pattern. Its distribution in parenchyma in the sections of specimens may be defined as lobular, focal and spotty. The detection of intrahepatic HBV DNA depended on two factors, at least in the present study: 1) liver disease activity; chronic active hepatitis (CAH) group had a significant higher prevalence (81%) as compared to cirrhosis, chronic lobular hepatitis (CLH), acute hepatitis and hepatocellular carcinoma (HCC) groups; 2) HBV infection state: HBV DNA was more easily detected in HBeAg positive or intrahepatic HBcAg positive patients than in single HBsAg positive or anti-HBc cases. The findings that hepatocytes expressing HBV DNA, particularly in focal distribution, were closely related to hepatic necrosis sites suggested that HBV replication might occur in conjunction with hepatic necrosis.

DNA Replication↗

Coronary artery disease in the elderly.

In the past 25 years, the mortality rate due to ischaemic heart disease in the United States of America and many other western countries has decreased significantly, whilst that in Singapore has increased steadily and unrelentlessly. Hypertension is also very common in Singapore, with a prevalence rate of 14% in those who are 20 years and above. Ischaemic heart disease and hypertension both increase dramatically with age and these 2 conditions account for a substantial proportion of the mortality and morbidity in elderly subjects, 65 years and above. Ischaemic heart disease often presents certain special problems with regard to clinical presentation, investigation and treatment in the elderly patients. For example, typical chest pain is much less frequent in elderly patients with angina pectoris or acute myocardial infarction compared to their younger counterparts. Elderly patients are also generally much more sensitive to any form of drug therapy. Therefore anti-anginal drugs such as the nitrates, beta-blockers and calcium antagonists and all types of anti-hypertensive drugs must be administered more carefully, with a smaller starting dosage and with careful monitoring of possible side-effects.

Aged↗

Current concepts of the pathogenesis and management of diabetic ketoacidosis (DKA).

Diabetic ketoacidosis (DKA) is the commonest endocrine emergency encountered in clinical practice. Although in the last 3 decades the average worldwide immediate mortality has decreased from 10% to 5%, survival has not improved strikingly. The pathogenesis of DKA is currently attributed to a combination of two hormonal abnormalities--a relative insulin insufficiency and stress hormone excess (glucagon, catecholamines, cortisol and growth hormone). Withdrawal of exogenous insulin, pancreatic beta cell failure and insulin resistance are factors leading to relative insulin insufficiency. Factors leading to stress hormone excess include fasting, stress and dehydration. The combination of these two hormonal abnormalities leads to impaired carbohydrate utilization and ketonaemia which in turn results in metabolic acidosis with loss of water through acidotic breaths, rise in plasma lipids, hyperglycaemia and glycosuria leading to osmotic diuresis and further loss of water, excretion of partly neutralised ketoacids via the kidney with loss of cations (Na+ and K+). A net increase in protein catabolism which leads to an increased amino acid flux from muscle and an enhanced load of gluconeogenic precursor to the liver and a rise in blood pyruvate and lactate concentration. The prevention of either of these hormonal abnormalities will prevent the development of DKA. The successful outcome in the treatment of DKA is clearly related to the prompt recognition of the diagnosis and the precipitation factors, the severity of the initial metabolic derangements, the judicious use of fluid and electrolyte replacement, the choice, route and dosage of the insulin therapy and above all the close monitoring and meticulous clinical care of the patient throughout the entire course of the treatment. Current acceptable treatment of DKA include the following: adequate fluid replacement: low dose insulin therapy at frequent intervals; adequate potassium replacement from time of first insulin therapy with ECG monitoring; bicarbonate replacement if pH less than 7.1; broad spectrum antibiotics if infections is suspected and other supportive measures. The role of phosphate and magnesium replacement is still controversial. An awareness of the complications during the treatment of DKA including cerebral edema (paradoxical acidosis), altered central nervous system oxygenation, vascular thrombosis, shock, myocardial infarction, pancreatitis, infection, inhalation of vomitus , overhydration, underhydration , hypoglycaemia, hyperkalemia and hypokalemia all certainly help improve the morbidity and mortality of DKA.

Aged↗

Influence of activity level on vitamin E status in healthy men and women and cardiac patients.

BACKGROUND: Plasma Vitamin E status may indicate protection against cholesterol oxidation. The purpose of this study was to determine if the plasma vitamin E status is influenced by exercise training status or a single session of submaximal exercise. METHODS: The 41 participants were categorized as sedentary, recreational endurance trained, competitive endurance trained, or cardiac rehabilitation patients. Subjects completed a 3-day dietary record. After a 24-hour diet and exercise control period, including a 12-hour fast, venous blood was collected. Plasma was analyzed for total cholesterol, high-density lipoprotein cholesterol (HDL-C), total lipid, vitamin E, and low-density lipoprotein (LDL) vitamin E concentrations. Each subject then exercised on a treadmill at 60% of measured maximal oxygen consumption for 30 minutes. Postexercise samples were collected 5 minutes after the activity. RESULTS: Multivariate analysis of variance and follow-up Tukey post hoc tests indicated that the cardiac rehabilitation group had lower total fat and monounsaturated fat intake in the diet than the other groups, and the competitive-endurance trained group had higher HDL-C levels. Plasma vitamin E was higher in the cardiac rehabilitation group, but the statistical differences disappeared when expressed per unit of plasma total lipid. The vitamin E content of LDL was not different among the groups. A single exercise session did not alter the plasma lipoprotein or vitamin E status. CONCLUSIONS: These results suggest that habitual activity level of healthy individuals or a single session of exercise does not influence the plasma vitamin E or LDL vitamin E concentrations. However, patients in an endurance cardiac rehabilitation program tend to show normal to elevated plasma vitamin E status.

Adult↗