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Biomedical subjects

Z C Luo

Publications and source records attributed to Z C Luo.

At least 19 recordsLinked to original sources
PubMed2005

Tracing the origins of "fetal origins" of adult diseases: programming by oxidative stress?

Too small size at birth (due to poor fetal growth and/or preterm delivery) has been associated with substantially elevated risks of the metabolic syndrome (dislipidemia, insulin resistance, hypertension), type 2 diabetes and cardiovascular disease in adulthood. The mechanisms of such "fetal origins" or "programming" of disease phenomenon remain unresolved. Too large size at birth seems also associated with an increased risk. Many known or suspected causes of or conditions associated with adverse (poor or excessive) fetal growth or preterm birth have been associated with oxidative stress. Plausibly, oxidative stress may be a common link underlying the superficial "programming" associations between adverse fetal growth or preterm birth and elevated risks of certain chronic diseases. The mechanisms of oxidative stress programming may be through directly modulating gene expression or indirectly through the effects of certain oxidized molecules. Experimental investigations have well demonstrated the role of redox balance in modulating gene expression, and recent studies indicate that both the insulin functional axis and blood pressure could be sensitive targets to oxidative stress programming. Adverse programming may occur without affecting fetal growth, but more frequently among low birth weight infants merely because they more frequently experienced known or unknown conditions with oxidative insults. As oxidative stress levels are easily modifiable during pregnancy and early postnatal periods (which are plausible critical windows), the hypothesis, if proved valid, will suggest new measures that could be very helpful on fighting the increasing epidemic of the metabolic syndrome, type 2 diabetes and cardiovascular disease. Currently, there are several ongoing large randomized trials of antioxidant supplementation to counter oxidative stress during pregnancy for the prevention of preeclampsia. It would be invaluable if long-term follow-ups of infants born to women in such trials could be realized to test the oxidative stress programming hypothesis in such experimental trial settings.

Birth Weight↗
PubMed2005

An analysis of frequency response for the blood flow of volume pulse in microcirculation.

In this paper, a frequency analysis for the microcirculation model is introduced to find new microcirculation parameters in the frequency domain. By using Bode Plot of transfer function, we found two characteristic parameters of the model: damping ratio xi and break frequency omega(n). By analyzing the variation of xi and omega(n), it enables us to have better understanding of different states of microcirculation. At low damping, 0 or =1, the state of microcirculation will be worse and worse along with the descending of the omega(n). The results of experiments on 120 subjects are consistent with the analytical results of the model.

Analysis of Variance↗
PubMed2002

Swedish population-based longitudinal reference values from birth to 18 years of age for height, weight and head circumference.

UNLABELLED: This study aimed to update growth reference values for height, weight and head circumference in order to reflect the changes in body size in the Swedish population during the past two decades. The data came from a large longitudinal growth study on 3650 full-term healthy Swedish children who were born between 1973 and 1975. All of these 1801 girls and 1849 boys had longitudinal data for height and weight from birth to final height. Comparison with previous Swedish growth reference values based on children born between 1955 and 1958 revealed that there have been secular changes in body size. For instance, at 18 y of age, the updated height and weight reference values are 180.4 cm for males and 167.7 cm for females, i.e. 1.9 cm taller and 5.7 kg heavier for males and 2.3 cm taller and 3.4 kg heavier for females compared with the previous reference values. CONCLUSION: These new growth reference values provide current national standards for growth monitoring and evaluation since the year 2000.

Adolescent↗
PubMed2001

Timing of birth and infant and early neonatal mortality in Sweden 1973-95: longitudinal birth register study.

OBJECTIVE: To assess the impact of time of birth on infant mortality and early neonatal mortality in full term and preterm births. DESIGN: Analysis of data from the Swedish birth register, 1973-95. PARTICIPANTS: 2 102 324 spontaneous live births of infants without congenital malformation. OUTCOME MEASUREMENTS: Absolute and relative risk of infant mortality, early neonatal mortality, and early neonatal mortality related to asphyxia. RESULTS: Infant mortality, early neonatal mortality, and early neonatal mortality related to asphyxia were higher in infants who were born during the night (9 pm to 9 am) compared with those born during the day for 1973-9, 1980-9, and 1990-5. The difference was more dramatic for preterm infants. The largest difference was observed during 1990-5, when there was a 30% increase in early neonatal mortality (relative risk 1.31, 95% confidence interval 1.10 to 1.57) and a 70% increase in early neonatal mortality related to asphyxia (1.70, 1.22 to 2.38) in preterm infants born during the night compared with rates for preterm infants born during the day. A detailed analysis over 24 hours revealed two "high risk" periods: between 5 pm and 1 am and around 9 am. CONCLUSIONS: Infants born during the night have a greater risk of infant and early neonatal mortality and early neonatal mortality related to asphyxia than those born during the day. There has been no improvement over the past two decades. The problem is more serious for preterm births and was even worse in the 1990s. Shift changes and the hours immediately after such changes are high risk periods for neonatal care.

Asphyxia Neonatorum↗
PubMed2001

Body mass index reference values (mean and SD) for Swedish children.

UNLABELLED: Body mass index (BMI) is an important indicator of nutritional status. Many studies have been done to present BMI reference values in centile values rather than mean and SD values since its statistical distribution is positively skewed. Both height and weight growth charts are usually available in terms of mean and 1, 2 and 3 SD around the means; it would be of clinical value to produce BMI reference charts in a similar way. The aim of this work was to derive the mean and +/- 1, 2 and 3 SD BMI reference ranges as a supplement to the BMI centile reference values published previously for the same group of Swedish children. The method was based on an age-dependent Box transformation, and the beta-value was given as a third-degree polynomial function over the paediatric age. The BMI reference values can be given from mathematical functions in addition to values for specific ages. CONCLUSION: The BMI reference values and charts derived as described effectively reflect the nature of the variant age-dependent positive skewed statistical distribution of BMI values in the population, and can serve as a valid supplementary tool in the evaluation of growth and nutrition during paediatric years.

Adolescent↗
PubMed2001

Critical growth phases for adult shortness in Hong Kong Chinese.

OBJECTIVES: This study was designed to explore whether the influence of subnormal growth in fetal, infancy, childhood and pubertal phases on adult short stature was the same when comparing privileged and underprivileged populations. METHODS: Data came from two longitudinal growth studies: 1) Hong Kong Chinese children who were born in 1967 (n = 132), and 2) the comparatively more privileged Swedish children who were born in 1973-1975 (n = 2,850). RESULTS: 68% of Hong Kong Chinese children had two or more growth phases subnormal, much higher than the 12.4% for Swedish children. 42.4% of Hong Kong Chinese were short at final height, much higher than the 2.2% for Swedish children. Subnormal growth in any growth phase was associated with an increased risk of adult short stature in both series (p<0.01). After adjustment for mid-parental height, the place of residence (Hong Kong/Sweden) was not significant for adult shortness (p>0.05) in the pooled data. CONCLUSIONS: The impact of subnormal growth in any phase on adult shortness is similar in privileged and underprivileged populations. The much higher prevalence of subnormal growth and consequently adult short stature in developing countries is likely mainly attributable to adverse extrinsic or environmental influences.

Adolescent↗
PubMed2001

[Allele-specific chromosome 9p deletion in oral cancer].

OBJECTIVE: The aim of this study was to investigate the relationship between loss of heterozygosity (LOH) on chromosome 9p and the pathogenesis of oral squamous cell carcinoma (OSCC). METHODS: A total of 24 human OSCC specimens were analyzed for LOH on chromosome 9p using 8 microsatellite markers by means of polymerase chain reaction. RESULTS: In 24 cases of OSCC, LOH on chromosome 9p was identified in 10 of 24 cases (41.67%) with at least one marker. The main LOH were found on 9p21 at locus D9S171 (21.05%) and D9S304 (10.00%). There were also a deletion on 9p22-23 at locus D9S168 (22.22%) and D9S162 (15.38%). However, there was no statistically significant correlation between LOH at these loci with such clinical parameters as pathological types, tumor size and lymph-node metastasis. Microsatellite instability (MSI) is rare for any of the 8 markers in 24 OSCC. No MSI could observed using the common criteria for defining MSI-its detection in two or more markers. CONCLUSION: We found that high frequency of LOH occurred at 9p21-23 band. Their results indicate that more than one tumor suppressor genes at chromosome 9p21-23 region related to a subset of OSCC, while MSI might not be a crucial event.

Carcinoma, Squamous Cell↗
PubMed2000

Critical growth phases for adult shortness.

Previous growth studies have not explored how different growth phases-the fetal, infancy, childhood, and puberty phases-interact with each other in the development of adult shortness. In this paper, the authors attempt to describe the importance of each growth phase for adult shortness and the effect of growth in one phase on other, subsequent phases. The authors analyzed data from a longitudinal population-based growth study of 2,850 healthy, full term Swedish children born between 1973 and 1975. The height values were transformed into a centimeter score (CMS) by subtracting the raw values from the reference mean values for a particular age and sex. Subnormal growth in any growth phase, as defined by a decrease of 3 CMS or more during a growth phase, was associated with significant increased risk for final heights below 0, -6, and -12 CMS. For children with subnormal growth during one, two, and three phases, the percentages for final height below -12 CMS (a standard deviation score of approximately -2) were 0.5%, 9.4%, and 75%, respectively. Most children (57/62) with a final height below -12 CMS had subnormal growth in two or three phases. Height gains during the four growth phases were interdependent. The infancy phase was negatively associated with fetal growth (r = -0.33, p < 0.01); the childhood phase was positively associated with infancy growth (r = 0.21, p < 0.01); and the puberty phase was negatively associated with childhood growth (r = -0.10, p < 0.01).

Adolescent↗
PubMed2000

Foetal size to final height.

UNLABELLED: It is well known that some adult diseases, such as cardiovascular diseases, may be programmed during foetal life. It is not clear, however, whether final height may be predicted from foetal growth. A longitudinal cohort of full-term healthy Swedish babies (n = 3,650) was followed up from birth to maturity in a population-based growth study. Length or height and its changes were analysed from birth to 18 y of age; 2,807 children, with data available on birth length, final height and parental height, were included in this analysis. The result clearly shows that length at birth relates to final height. In terms of standard deviation scores (SDS), the mean difference in length at birth from the mean was greatly decreased in final height, but retained the same order as was seen at birth. In terms of centimeter difference from the reference mean values, the difference in length at birth remained roughly stable into final height. For instance, babies 5 cm above or below the mean birth length will end up approximately 5 cm above or below the mean in final height. Parental height-a surrogate value of the genetic final height potential of an individual-is shown to influence postnatal growth in height strongly. However, the difference from the mean in length at birth remained into adulthood within the same midparental height group. CONCLUSION: This study reveals that trends in foetal linear growth continue into maturity. Foetal growth is a significant predictor of postnatal growth. Final height is dependent on both the magnitude of foetal growth and the genetic potential in stature, and appears to some extent to be programmed from foetal growth.

Adolescent↗
PubMed2000

Fetal size to final height in Hong Kong Chinese children.

OBJECTIVES: It has been known that size at birth is important for postnatal growth and final height. However, there are few data in the literature on the difference in height growth patterns from fetal size to final height between less privileged and more privileged populations. The aim of this study was to describe the important features in height growth from birth to maturity in an underprivileged Hong Kong Chinese cohort in comparison to a more privileged Swedish cohort. METHODS: The longitudinal height growth data from birth to maturity in full-term healthy Hong Kong Chinese children (n=132) who were born in 1967 were analyzed, and compared with those for Swedish children who were born in 1973-75 (n=3650). RESULTS: Children with longer birth length achieved taller adult stature with respect to their target height. The mean final height retained the same order as that of the mean length at birth for various birth length groups. All children in the Hong Kong Chinese series showed catch-down height growth during the first 2 years of life, in contrast to the catch-up in smaller babies and catch-down in larger babies for the Swedish series. The growth deficit for the Hong Kong Chinese was -0.9 SDS at birth, -1.8 SDS at 2.0 years of age, -2.1 SDS at 8 years of age, and -1.7 SDS at final height. CONCLUSIONS: Fetal size is important for postnatal growth and attained final height with respect to a child's familial genetic potential in stature, not only for privileged populations, but also for underprivileged populations. However, children in underprivileged populations experience a persistent increasing growth deficit during infancy and childhood. Special attention should be given to monitor their growth status in early years and to institute appropriate intervention programs.

Adult↗
PubMed1999

A comparison of target height estimated and final height attained between Swedish and Hong Kong Chinese children.

Target height, the genetic potential in stature, is commonly estimated by the corrected midparental height (CMH) method. A new model for estimating target height has recently been introduced based on a large, Swedish, population-based study. The aim of this study was to compare the validity of the two methods for estimating target height in Hong Kong Chinese children. The Hong Kong Chinese were more than 10 cm shorter than the Swedes in stature. The secular increase in height over the two generations, however, was 4.2-4.8 cm for the Hong Kong Chinese, much larger than that of the Swedes (0.7-1.0 cm). The two populations are thus at different stages in the secular trend. The new model derived from Swedish population for estimating target height was shown to be applicable to Hong Kong Chinese children; the mean of residual final height values was close to zero (-0.15 cm, p = 0.74). However, the mean of residual final height was significantly above the expected value of zero (4.5 cm, p<0.0001) when the CMH method was applied to the data, which implies an underestimation bias of 4.5 cm. Consequently, if the CMH method is used to estimate target height and evaluate growth hormone treatment responses in short children, it may inflate the treatment response by 4.5 cm. In conclusion, the recently proposed model for target height estimation offers a better alternative for estimating target height in Hong Kong Chinese children and for assessing growth-promoting treatments.

Bias↗
PubMed1999

[A method of detecting respiratory rate with a high-sensitivity capacitance transducer].

Objective. To introduce a simple and low cost respiratory rate detection method. Method. A high-sensitivity capacitance transducer and corresponding detecting system were used in the system. Result. Satisfactory signals were obtained at the upper portion of the right thorax with the method. Conclusion. It could be used widely. It can be used to comprise the respiratory module in multi-parameter patient monitoring, or be used alone to detect respiratory rate.

Equipment Design↗
PubMed1998

Cardiokymograph system with a capacitance transducer and its preliminary application in the measurement of heart wall movement.

A novel cardiokymograph system is introduced. The new system features a capacitance transducer with increased sensitivity and can be used in multichannel measurements. The novelty of this technique is the injection of a current into the patient coupled with the use of a capacitive displacement transducer and the possibility of multichannel monitoring. It provides for the possibility of removing breath noise when some signal processing technique, such as adaptive filtering, is used. Further investigation is needed to demonstrate clinical significance and pathologies.

Adult↗
PubMed1998

Target height as predicted by parental heights in a population-based study.

The corrected midparental height method was introduced by Tanner in 1970 (Tanner method) and is commonly used to estimate target height in children to evaluate the effectiveness of growth-promoting therapies. It has not been established if the equation used to compute target height should be the same for children with short, normal, or tall parents. In this study, we examined the predicted target height values by parental heights in a large population-based study (n = 2402). A simple linear function of midparental height (x) was proposed to estimate target height (y): y = 45.99 + 0.78x (boys), y = 37.85+0.75x (girls), with a 95% predicted interval of about +/-10 cm. The prediction model was similar for boys and girls in SD scores (SDS), and was not affected by assortative mating or difference in parental heights. The model may underestimate the potential stature by about 2 cm for children with midparental height below -2 SDS, or 163 cm. In comparison, the Tanner method may lead to a 6-cm error in underestimating target height for these children. The function would be a better choice than the Tanner method for estimating target height in the clinical evaluation of growth promotion treatments because it is common that short children also have short parents. Children with very short parents will usually be much taller than their parents in adult stature, and we believe that a different function should be developed. The results support the proposed nondominant, non-sex-linked, polygenic inheritance in stature. The estimated heritability values were 0.75-0.78 in cm or 0.55-0.60 in SDS.

Adult↗
PubMed1998

Length and body mass index at birth and target height influences on patterns of postnatal growth in children born small for gestational age.

OBJECTIVE: Previous growth studies on children born small for gestational age (SGA) indicate that birth length, weight, and target height are important predictors for postnatal catch-up growth in SGA. Their influences on different phases of catch-up growth are still not described. The aim of this study was to clarify the influences of target height, length, and nutritional status at birth on different phases of postnatal catch-up growth (infancy, childhood, puberty) in SGA and the long-term consequences. METHODS: Data were obtained from a longitudinal population-based growth study on Swedish children (N = 2815). Primary outcome measurements include heights, the changes in height standard deviation scores (SDS) during various phases of growth and relative risk for adult shortness. RESULTS: The difference in final height in children born SGA was attributable to their difference in target height and the magnitude of catch-up growth during the first 6 months of life, rather than the difference in length or body mass index (BMI) at birth. Length at birth showed negative influence on catch-up growth during infancy (0 to 2 years of age), but no significant influence thereafter. The BMI or weight for length SDS at birth showed no significant influence on catch-up growth during any growth phase. Target height showed positive influence on catch-up growth from the onset of childhood. Neither target height nor length and BMI at birth showed any significant influence on catch-up growth during puberty. The magnitude of catch-up growth during infancy, especially the first 6 months of life, is most critical in decreasing risk at adult shortness. We confirmed that the SGA group had a sevenfold greater risk for adult shortness than the non-SGA group (relative risk = 7.31; 95% confidence interval: 3.96-13.52). However, approximately 40% of children who were below -2 in height SDS at 2 years of age remained short at final height in both SGA and non-SGA groups. The mean height SDS of children born SGA increased by 1.65 from birth to final height, but the length deficit in centimeters at birth (-5.4 cm) persisted into adulthood (-5.9 cm). CONCLUSIONS: BMI at birth is not related to postnatal catch-up growth in infants born SGA, but birth length and target height are important. The genetic influence on catch-up growth appears to start from the onset of childhood. Being born short or becoming short during the first 2 years of life is similar in terms of risk for adult short stature.

Body Height↗
PubMed1994

[Body surface dynamic monitoring of respiratory muscles in patients with cor pulmonale].

Electromyography (EMG) of diaphragm (Edi) and intercostal muscle (Ein) in 30 healthy volunteers and 28 patients with cor pulmonale or pulmonary fibrosis were analysed. The results show that (1) there is no obvious activity of Ein to be observed and the frequency spectra are stable when the healthy volunteers breath quietly, (2) the activity of Ein and the amplitude of Edi increase when patients are in compensation stage, (3) the patients with serious respiratory failure, the amplitude of Edi decreases remarkably, (4) the frequency spectras of Edi appear wave-like changes with the breathing pattern of patients.

Adult↗