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Biomedical subjects

S S Guo

Publications and source records attributed to S S Guo.

At least 19 recordsLinked to original sources
PubMed2003

Ultrasonic transducers using electron-irradiated vinylidene fluoride-trifluoroethylene copolymers.

Single-element, planar transducers have been fabricated using electron-irradiated poly(vinylidene fluoride-trifluoroethylene) 80/20 mol% copolymers with different electron dosage. Electrical field-induced strain response of copolymer film with 100 Mrad dosage has been studied at 5 kHz and the electrostrictive coefficient was calculated. The transmitting response of the air-backing and epoxy-backing transducers was evaluated with the application of high DC bias voltages. Clear ultrasonic amplitudes and high frequency spectrum (>20 MHz) were observed when driven from a standard ultrasonic voltage source through a decoupling circuit. It has also showed that larger generation of ultrasonic waves will be induced under high DC bias field, which is due to the increase of induced d(33) piezoelectric coefficient. Two different polar bias voltages, positive and negative, were applied to the transducers and inverse waveforms were received, which was coincident with the theoretical analysis of the strain response of electrostrictive film.

Journal Article↗
PubMed2003

Frequent overexpression of cyclin D1 in sporadic pancreatic endocrine tumours.

Pancreatic endocrine tumours (PETs) occur sporadically or are inherited as part of the multiple endocrine neoplasia type-1 syndrome. Little is known about the molecular events leading to these tumours. Cyclin D1, a key regulator of the G1/S transition of the cell cycle, is overexpressed in a variety of human cancers as well as certain endocrine tumours. We hypothesized that similar to other endocrine tumours, cyclin D1 is overexpressed in human sporadic PETs. Cyclin D1 protein overexpression was found in 20 of 31 PETs (65%) when compared with normal pancreatic tIssue. Furthermore, Northern blot analysis suggests that cyclin D1 up-regulation occurs at the post-transcriptional level in some PETs. Because the key cell growth signalling pathways p42/p44/ERK (extracellular signal-regulated kinase), p38/MAPK (mitogen-activated protein kinase), and Akt/PKB (protein kinase B) can regulate cyclin D1 protein expression in other cell types, pancreatic endocrine tumours were analysed with phospho-specific antibodies against the active forms of these proteins to elucidate a tIssue-specific regulatory mechanism of cyclin D1 in PETs. We found frequent activation of the p38/MAPK and Akt pathways, but down-regulation of the ERK pathway, in cyclin D1 overexpressing PETs. This study demonstrates that cyclin D1 overexpression is associated with human sporadic PET tumorigenesis, and suggests that this up-regulation may occur at the post-transcriptional level. These findings will direct future studies of PETs towards cell cycle dysregulation and the identification of key growth factor pathways involved in the formation of these tumours.

Adenoma, Islet Cell↗
PubMed2002

Comparison of percent body fat estimates using air displacement plethysmography and hydrodensitometry in adults and children.

PURPOSE: The purpose of the study was to compare estimates of body density and percentage body fat from air displacement plethysmography (ADP) to those from hydrodensitometry (HD) in adults and children and to provide a review of similar recent studies. METHODS: Body density and percentage body fat (% BF) were assessed by ADP and HD on the same day in 87 adults aged 18-69 y (41 males and 46 females) and 39 children aged 8-17 y (19 males and 20 females). Differences between measured and predicted thoracic gas volumes determined during the ADP procedure and the resultant effects of those differences on body composition estimates were also compared. In a subset of 50 individuals (31 adults and 19 children), reliability of ADP was measured and the relative ease or difficulty of ADP and HD were probed with a questionnaire. RESULTS: The coefficient of reliability between %BF on day 1 and day 2 was 96.4 in adults and 90.1 in children, and the technical error of measurement of 1.6% in adults and 1.8% in children. Using a predicted rather than a measured thoracic gas volume did not significantly affect percentage body fat estimates in adults, but resulted in overestimates of percentage body fat in children. Mean percentage body fat from ADP was higher than percentage body fat from HD, although this was statistically significant only in adults (29.3 vs 27.7%, P<0.05). The 95% confidence interval of the between-method differences for all subjects was -7 to +9% body fat, and the root mean square error (r.m.s.e.) was approximately 4% body fat. In the subset of individuals who were asked to compare the two methods, 46 out of 50 (92%) indicated that they preferred the ADP to HD. CONCLUSION: ADP is a reliable method of measuring body composition that subjects found preferable to underwater weighing. However, as shown here and in most other studies, there are differences in percentage body fat estimates assessed by the two methods, perhaps related to body size, age or other factors, that are sufficient to preclude ADP from being used interchangeably with underwater weighing on an individual basis.

Adipose Tissue↗
PubMed2002

Body composition estimates from NHANES III bioelectrical impedance data.

BACKGROUND: Body composition estimates for the US population are important in order to analyze trends in obesity, sarcopenia and other weight-related health conditions. National body composition estimates have not previously been available. OBJECTIVE: To use transformed bioelectrical impedance analysis (BIA) data in sex-specific, multicomponent model-derived prediction formulae, to estimate total body water (TBW), fat-free mass (FFM), total body fat (TBF), and percentage body fat (%BF) using a nationally representative sample of the US population. DESIGN: Anthropometric and BIA data were from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). Sex-specific BIA prediction equations developed for this study were applied to the NHANES data, and mean values for TBW, FFM, TBF and %BF were estimated for selected age, sex and racial-ethnic groups. RESULTS: Among the non-Hispanic white, non-Hispanic black, and Mexican-American participants aged 12-80 y examined in NHANES III, 15 912 had data available for weight, stature and BIA resistance measures. Males had higher mean TBW and FFM than did females, regardless of age or racial-ethnic status. Mean TBW and FFM increased from the adolescent years to mid-adulthood and declined in older adult age groups. Females had higher mean TBF and %BF estimates than males at each age group. Mean TBF also increased with older age groups to approximately 60 y of age after which it decreased. CONCLUSIONS: These mean body composition estimates for TBW, FFM, TBF and %BF based upon NHANES III BIA data provide a descriptive reference for non-Hispanic whites, non-Hispanic blacks and Mexican Americans in the US population.

Adolescent↗
PubMed2002

Cumulative effects of cardiovascular disease risk factors on quality of life.

OBJECTIVES: The Medical Outcomes Study Short-Form Health Survey (SF-36) was used to assess the quality of life for adults who differed in level of risk for cardiovascular disease. METHODS: Subjects were 51 men and 80 women from southwestern Ohio between the ages of 20 and 86 years. Individuals level of risk was based on the culmination of four cardiovascular disease risk factors: hypertension (i.e., systolic BP>or=140 mmHg or diastolic BP>or= 90 mmHg), obesity (i.e., BMI>or=30), high cholesterol (i.e., total cholesterol>or=240 mg/dL), and presence/absence of smoking. RESULTS: Each risk factor was analyzed independently and cumulatively for effects on the SF-36 dimensions (i.e., Physical Functioning, Role-Physical, Bodily Pain, General Health, Vitality, Social Functioning, Role-Emotional, Mental Health). The data suggested that quality of life impairment (indicated by lower scores on the SF-36 dimensions) increased as the number of cardiovascular disease risk factors an individual had increased. CONCLUSIONS: Cardiovascular disease risk factors unknown to the participants had differential effects on the SF-36 dimensions, and quality of life decreased as the number of risk factors individuals had increased.

Adult↗
PubMed2001

[Analysis of the HLA A/B local haplotype among the females of Han nationality in Hunan province].

OBJECTIVE: To investigate and analyse HLA A/B local haplotype gene frequency (HGF) in the females of Han nationality in Hunan. METHODS: HLA-A, B local antigen polymorphisms were investigated via microcytotoxicity assay. Haplotype was inferred by means of linkage disequilibrium parameter. RESULTS: Among the 46 haplotypes, HGF high were: A11-B60 (HGF = 0.1381), A2-B60 (HGF = 0.0861), A24-B48 (HGF = 0.0709). Three haplotype's linkage disequilibrium parameter have significant difference, they are A2-B52, A11-B13, A24-B52. CONCLUSION: The female of Han Nationality of Hunan HLA-A, B especially B local antigen frequency exists difference sompare with Han Nationality in Hunan and other areas in China of mix public of both sexes. When study relativity of the female disease of Han Nationality of Hunan with HAL, should notice HLA distributing particularity, be assure data veracity. Among the 46 haplotypes, A2-B52, A11-B13, A24-B52 three haplotypes exist significant linkage disequilibrium, probably they are own haplotypes at the female of Han Nationality in Hunan.

Adult↗
PubMed2001

Anomalous overexpression of p27(Kip1) in sporadic pancreatic endocrine tumors.

BACKGROUND: Little is known about the cellular defects and molecular mechanisms leading to pancreatic endocrine tumors (PETs). p27(Kip1) is a universal cyclin-dependent kinase inhibitor (CDKI), which acts as a tumor suppressor and a negative regulator of cell cycle. From previous reports, quiescent cells show high levels of p27(Kip1) expression while neoplastic and proliferating cells show no detectable p27(Kip1) expression. We hypothesize that in malignant sporadic PETs, p27(Kip1) expression would be decreased compared with benign PETs and normal pancreatic tissue. METHODS: Western analysis was performed on 28 PETs (7 malignant, 21 benign), 2 nonendocrine cell lines, and 5 endocrine cell lines. Signal intensities were quantitated using densitometry and standardized to normal pancreas. RESULTS: Unexpectedly, increased p27(Kip1) expression as compared with control was seen in both benign and malignant tumors, as well as in all four pancreatic islet tumor cell lines, but not fibroblast or pituitary cell lines, evaluated. There was no difference in p27(Kip1) level between benign and malignant tumors. CONCLUSION: This represents the first report of anomalous p27(Kip1) overexpression in sporadic PETs, and is part of a growing literature describing the paradoxical overexpression of p27(Kip1) in human tumors that includes other endocrine tumors. These studies suggest a unique molecular pathway leading to endocrine tumorigenesis.

Animals↗
PubMed2001

Management of burn injuries during pregnancy.

Burns suffered during pregnancy is rare and can be a devastating injury. The presence of a fetus creates many special maternal physiological changes, and the burn wound places additional great stress on systems that are already highly modified. Most of the literature has come from developing countries, and most reports from developed countries have come before 1980 and do not reflect the current standard of care. We have compiled a retrospective review of eight patients burned during pregnancy. The total body surface area (TBSA) burned ranged from 1 to 85% in these patients, and all survived the injury. All patients gave birth to healthy children except the most severely burned patient, whose child suffers from cerebral palsy. Based on our experience as well as a review of the literature, management recommendations are proposed. These include: (1) early pregnancy test for all female patients of childbearing age, (2) prompt and aggressive fluid resuscitation, (3) early supplemental oxygen and low threshold for mechanical ventilatory support, (4) early delivery of the fetus if the pregnancy is in the third trimester, and (5) high suspicion for venous thrombosis and sepsis, with early and aggressive treatment.

Adolescent↗
PubMed2001

Age of puberty: data from the United States of America.

In an attempt to determine whether the secular trend toward an earlier onset of puberty has continued over recent decades in the United States of America, published reports concerning the age of attainment of pubertal events have been reviewed. Such reports are very limited and vary in both design and inclusive ages of study subjects. Among females, two recent large cross-sectional studies indicate that fifty percent of females in the United States attain Tanner breast stage 2 at 9.5 to 9.7 years of age. This is younger than previously thought, although adequate earlier studies of girls in the United States are not available for comparison. These two studies also indicate that about 14% of girls attain Tanner stage 2 while 8 years of age; one study extends earlier reporting that about 6% exhibit onset of breast development while 7 years of age. There is no evidence that the age of menarche or the attainment of adult (Tanner 5) breast development has decreased over the past 30 years. The data also suggest an earlier onset of Tanner stage 2 pubic hair but no change in attainment of stage 5. Among males, pubic hair may be appearing at younger ages, but data are inadequate or too inconsistent to allow firm interpretation. The lack of standardization of genital criteria of pubertal onset in the male makes any conclusions regarding secular trends impossible. In summary, earlier secular trends over recent decades related to better health, improved nutrition or socio-economic status, or any putative influence by endocrine disrupters cannot be verified.

Adolescent↗
PubMed2001

Racial differences in the sums of skinfolds and percentage of body fat estimated from impedance in black and white girls, 9 to 19 years of age: the National Heart, Lung, and Blood Institute Growth and Health Study.

OBJECTIVES: This National Heart, Lung, and Blood Institute Growth and Health Study report assesses racial differences in fat patterning in black and white girls ages 9 to 19 years, comparing the sum of triceps and subscapular skinfolds (SSFs) and percentage of body fat (%BF) from impedance as two indices of adiposity. It is hypothesized that racial differences in fat patterning manifest during puberty. RESEARCH METHODS AND PROCEDURES: SSF and %BF were measured annually. Racial differences in SSF and %BF were evaluated by age. Associations between %BF and SSF were evaluated using the Pearson's correlations coefficient. Classification agreement was evaluated using the kappa-statistic. Effects of pubertal stage and race on classification agreement were examined using multivariate models. RESULTS: White girls had a greater mean %BF at 9 to 12 years of age; black girls had a greater %BF thereafter. Black girls had a greater mean SSF at every age. The correlation coefficient between SSF and %BF was 0.79, and there was good agreement between %BF and SSF in separating high (>85th percentile) from not high (kappa = 0.60 for whites and 0.66 for blacks). SSF associated more with %BF in prepuberty and early puberty than in late puberty. DISCUSSION: Despite good correlations between %BF and SSF, the two methods indicate different fat patterns in black and white girls.

Adipose Tissue↗
PubMed2001

Total body water reference values and prediction equations for adults.

BACKGROUND: The clinical interpretation of total body water (TBW) necessitates the availability of timely comparative reference data. The prediction of TBW volume in renal disease is critical in order to prescribe and monitor the dose of dialysis in the determination of Kt/V. In clinical practice, urea distribution (V) is commonly predicted from anthropometric equations that are several decades old and for white patients only. This article presents new reference values and prediction equations for TBW from anthropometry for white and black adults. METHODS: The study sample included four data sets, two from Ohio and one each from New Mexico and New York, for a total of 604 white men, 128 black men, 772 white women, and 191 black women who were 18 to 90 years of age. The TBW concentration was measured by the deuterium or tritium oxide dilution method, and body composition was measured with a Lunar DXA machine. An all-possible-subsets of regression was used to predict TBW. The accuracy of the selected equations was confirmed by cross-validation. RESULTS: Blacks had larger TBW means than whites at all age groups. The 75th TBW percentile for whites approximated the TBW median for blacks at most ages. The white men and black men and women had the largest TBW means ever reported for healthy individuals. The race- and sex-specific TBW prediction equations included age, weight, and stature, with body mass index (BMI) substituted for weight in the white men. The root mean square errors (RMSEs) and standard errors for the individual (SEIs) ranged from approximately 3.8 to 5.0 L for the men and from 3.3 to 3.6 L for the women. In both men and women, high values of TBW were associated with high levels of total body fat (TBF) and fat-free mass (FFM). CONCLUSION: : TBW in these healthy adults is relatively stable through a large portion of adulthood. There are significant race and sex differences in TBW. These accurate and precise equations for TBW provide a useful tool for the clinical prediction of TBW in renal disease for white and black adults. These are the first TBW prediction equations that are specific for blacks.

Adult↗
PubMed2001

Evaluation of anthropometric equations to assess body-composition changes in young women.

BACKGROUND: Healthy young women who engage in an exercise program may lose fat that is not reflected in body weight changes because of concurrent gains in fat-free mass (FFM). OBJECTIVE: This study addressed the question of how well anthropometry-based predictive equations can resolve these changes. DESIGN: Several widely used skinfold-thickness- or circumference-based equations were compared by using dual-energy X-ray absorptiometry to study 150 healthy young women before and after 8 wk of Army basic combat training (average energy expenditure: 11.7 MJ/d). RESULTS: Women lost 1.2 +/- 2.6 kg fat (mean +/- SD) and gained 2.0 [corrected] +/- 1.5 kg FFM. Fat loss (r = 0.47), but not FFM gain (r = 0.01), correlated with initial fatness. Thus, for many women who lost fat, body weight did not change or increased. Fat loss was associated with a reduction in abdominal circumference but this alone was not a consistent marker of fat loss. One circumference equation and one skinfold-thickness equation yielded the smallest residual SDs (2.0% and 1.9% body fat, respectively) compared with the other equations in predicting body fat. The sensitivity and specificity of the best equations in predicting changes in percentage body fat were not better than 55% and 66%, respectively. CONCLUSIONS: These data suggest that for women, anthropometry can provide better estimates of fatness than body mass index but it is still relatively insensitive to short-term alterations in body composition. Not surprisingly, the circumference equation that includes the most labile sites of female fat deposition (ie, waist and hips instead of upper arm or thigh) proved to be the most reliable.

Absorptiometry, Photon↗
PubMed2001

Molecular and genetic mechanisms of tumorigenesis in multiple endocrine neoplasia type-1.

Multiple endocrine neoplasia type 1 (MEN1) is a rare but informative syndrome for endocrine tumorigenesis. Since its isolation, several groups have begun to determine the role of menin, the protein product of MEN1, in sporadic endocrine tumors as well as tumors of the MEN1 syndrome. Mutations of menin have been reported in more than 400 families and tumors, most of which are truncating mutations, thus supporting the function of menin as a tumor suppressor. The exact function of menin is unknown, but overexpression of menin inhibits proliferation of Ras-transformed NIH3T3 cells. Since menin interacts with proteins from both the TGF beta and AP-1 signaling pathways, perhaps its tumor suppressor function is related to these key cell growth pathways. In this review we will discuss the various clinical manifestations of MEN1 syndrome, potential mechanisms of MEN1 tumorigenesis, and mutations associated with MEN and sporadic endocrine tumors.

Amino Acid Sequence↗
PubMed2001

Sex differences in bone mass acquisition during growth: the Fels Longitudinal Study.

Risk of osteoporosis in later life may be determined during adolescence and young adulthood. The present study used longitudinal data to examine the accumulation of bone mineral content (BMC) and bone mineral density (BMD) in Caucasian subjects ages 6-36 yr. Growth in BMC and BMD (measured by dual X-ray absorptiometry; Lunar, Madison, WI) of 94 males and 92 females was monitored for a mean period of 4.29 yr. The main findings were that there were no sex differences in BMC or BMD during the prepubertal stage; however, females had significantly higher BMD of the pelvis and BMC and BMD of the spine during puberty, and postpubertal males generally had significantly higher BMC and BMD than their female counterparts. In addition, the longitudinal rate of bone accumulation in both sexes increased rapidly during childhood and adolescence and was nearly complete at the end of puberty. Finally, peak BMC and BMD was achieved between the ages of 20 and 25 and occurred earlier in females than in males. The rates of growth and timing of peak bone mass as reported here define the crucial period during which intervention protocols should be developed for maximizing skeletal mass to prevent the development of osteoporosis.

Absorptiometry, Photon↗
PubMed2001

Childhood body composition in relation to body mass index.

OBJECTIVE: The aim is to describe body composition in relation to body mass index (BMI; body weight/stature(2)) to provide health care professionals insight into the meaning, significance, and limitations of BMI as an index of adiposity during childhood. METHODS: Data from 387 healthy, white children 8 to 18 years of age from the Fels Longitudinal Study were analyzed. Measurements were scheduled annually and each child was examined 1 to 11 times, totaling 1748 observations. Total body fat (TBF) and fat-free mass (FFM) were determined from hydrodensitometry. Stature and weight were measured using standard methods and BMI and the components of BMI, TBF/stature(2), and FFM/stature(2) were calculated. Analyses included correlations between BMI and body composition variables; age-related patterns of BMI, TBF/stature(2), and FFM/stature(2); and annual changes in BMI, TBF/stature(2), and FFM/stature(2). RESULTS: Generally, correlations between BMI and body composition variables were strong and significantly different from zero. Means for BMI throughout childhood were similar for boys and girls, although significantly larger values were observed for girls at ages 12 to 13 years. Age-related patterns of TBF/stature(2) and FFM/stature(2) differed between sexes. In each sex, annual increases in BMI were driven primarily by increases in FFM/stature(2) until late adolescence, with increases in TBF/stature(2) contributing to a larger proportion of the BMI increases in girls than in boys. CONCLUSIONS: Unlike adults, annual increases in BMI during childhood are generally attributed to the lean rather than to the fat component of BMI. Because the properties of BMI vary during childhood, health care professionals must consider factors such as age and sex when interpreting BMI.

Adipose Tissue↗
PubMed2001

[Prospect of the Advanced Life Support Program Breadboard Project at Kennedy Space Center in USA].

The Breadboard Project at Kennedy Space Center in NASA of USA was focused on the development of the bioregenerative life support components, crop plants for water, air, and food production and bioreactors for recycling of wastes. The keystone of the Breadboard Project was the Biomass Production Chamber (BPC), which was supported by 15 environmentally controlled chambers and several laboratory facilities holding a total area of 2150 m2. In supporting the Advanced Life Support Program (ALS Program), the Project utilizes these facilities for large-scale testing of components and development of required technologies for human-rated test-beds at Johnson Space Center in NASA, in order to enable a Lunar and a Mars mission finally.

Biomass↗
PubMed2001

[Feasibility of the use of degraded inedible biomass of plants as a nutrient liquid for hydroponic cultivation].

Objective. To demonstrate that the recycled liquid, which originated from lettuce inedible biomass degraded by fixed microorganism (correction of microorgannism) and enzyme, can be used as a nutrient solution for lettuce hydroponic cultivation. Method. After biologically degrading the weighted, oven-dried and milled leaves and roots of lettuce in a biological reactor under aerobic condition, the original effluent and its supplemented effluent were used as nutrients for lettuce hydroponic cultivation. Result. The average dried weight (ADW) of lettuce from the original effluent group was approximately half of that from the control group, and the ADW from supplemented effluent group was about equal to that from the control group; some qualities of the lettuce such as a relatively lower content of NO3- from both the original effluent group and the supplemented effluent one improved, and some of those such as a relatively higher content of NO2- dropped. Conclusion. The biologically-degraded effluent was able to be used as nutrient solution for lettuce hydroponic cultivation, although the effects of the inorganic ion-supplemented effluent were much better; the plants of lettuce from the biologically-degraded effluent were safely edible.

Biodegradation, Environmental↗