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1.
《Annals of botany》1999,83(1):45-50
Apomicts provide the opportunity to investigate the variation in achene size and performance that is due to factors other than genetic differences between achenes. Achene characteristics of a single capitulum from each of 15 biotypes of apomicticTaraxacumwere investigated. Within a capitulum, achene fresh weight ranged from 4.45-fold to 13.74-fold. Overall, 59.8% of achenes germinated. The probability of any one achene germinating was influenced both by its source and by its weight and ranged from 0.049 to 0.902 between capitula and from 0.028 to 0.873 between weight classes. An investigation of the relationship between achene parts in three biotypes identified a linear trend for embryos to acquire a greater proportion of total achene weight as achene weight increases. Although the heaviest achenes showed the best germination, it is predicted that, for a given investment of maternal resources, seedling number would be maximized by producing achenes of a single intermediate weight.  相似文献   

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Relationships between number of eggs (Ng), brood weight (Wg), and body length (L) and weight (W) of females were studied for 16 orders and suborders of Crustacea. The study was based on the authors' observations in the inland waters of the European USSR, in the coastal regions of the fareastern and northern seas and data from V. V. KUZNETSOV (preserved in archives). An extensive literature was also used. The equations describing the relationships (Ng=f(L) and Wg=f(W) are calculated for some species and high taxons. On the average for the superclass (excluding the order Notostraca) the Wg/W ratio appeared to be 0.16. This ratio is markedly different for species of Notostraca. It is supposed that this difference is due to the high metabolic rate of Notostraca.  相似文献   

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Much attention has been paid to the behavioral characteristics of successful weight loss maintenance, but less is known about the cognitive processes that underlie this process. The purpose of this study was to investigate cognitive interference from food‐related cues in long‐term weight loss maintainers (WLM; N = 15) as compared with normal weight (NW; N = 19) and obese (OB; N = 14) controls. A Food Stroop paradigm was used to determine whether successful WLM differed from controls in both the speed and accuracy of color naming words for low‐calorie and high‐calorie foods. A significant group × condition interaction for reaction time was observed (P = 0.04). In post hoc analyses, no significant differences in reaction time across the three groups were observed for the low‐calorie foods (P = 0.66). However, for the high‐calorie foods, WLM showed a significantly slower reaction time than the NW (0.04) and OB (0.009) groups (885 ± 17.6, 834 ± 15.8, 816 ± 18.3 ms, respectively). No significant group differences were seen for number of correct trials in 45 s (P = 0.12). The differential interference among WLM did not appear to generalize to other types of distracters (i.e., nonfood). Overall, findings from this study suggest that WLM differ from OB and NW controls in their cognitive responses to high‐calorie food cues. Future research is needed to better understand why this bias exists and whether and how interventions can change cognitive processes to better facilitate long‐term weight control.  相似文献   

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As many people struggle with maintenance of weight loss, the study of successful weight loss maintainers (SWLM) can yield important insights into factors contributing to weight loss maintenance. However, little research has examined how SWLM differ from people who are obese or normal weight (NW) in brain response to orosensory stimulation. The goal of this study was to determine if SWLM exhibit different brain responses to orosensory stimulation. Brain response to 1‐min orosensory stimulation with a lemon lollipop was assessed using functional magnetic resonance imaging among 49 participants, including SWLM (n = 17), NW (n = 18), and obese (n = 14) controls. Significant brain responses were observed in nine brain regions, including the bilateral insula, left inferior frontal gyrus, left putamen, and other sensory regions. All regions also exhibited significant attenuation of this response over 1 min. The SWLM exhibited greater response compared with the other groups in all brain regions. Findings suggest that the response to orosensory stimulation peaks within 40 s and attenuates significantly between 40 and 60 s in regions associated with sensation, reward, and inhibitory control. Greater reactivity among the SWLM suggests that greater sensory reactivity to orosensory stimulation, increased anticipated reward, and subsequently greater inhibitory processing are associated with weight loss maintenance.  相似文献   

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Evidence is cited showing that overweight is a health hazard, but that this is primarily true only when the excess weight is due to an excess accumulation of adipose tissue. Diagnosis of frank obesity should be established by a careful interpretation of height-weight tables and of all other pertinent data. Although many factors play an etiologic role, obesity can occur only when caloric intake exceeds caloric output, and can be obviated only when this imbalance is reversed. Therefore prevention of weight gain, which should receive increasing attention, and also satisfactory weight loss, both require that caloric output be increased through added physical activity and that caloric intake be decreased through diminished consumption. Success depends on recognizing the fallacy of all misleading misinformation, and on establishing permanent habits of regular exercise and of moderation in eating and drinking. Suggestions are made that can be effective guidelines to a commonsense program of weight control.  相似文献   

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LISSNER, LAUREN, CECILIA KARLSSON, ANNA KARIN LINDROOS, LARS SJOSTROM, BJORN CARLSSON, LENA CARLSSON, AND CALLE BENGTSSON. Birth weight, adulthood BMI, and subsequent weight gain in relation to leptin levels in Swedish women. Obes Res. Objective Leptin seems to be involved in the regulation of energy balance, although little is known about the epidemiology of leptin with respect to prediction of weight gain and incidence of obesity-related diseases. The dual aim of this study is to document characteristics of leptin after long-term storage, and to describe its relation to body weight, from birth to old age, in an ongoing prospective study. Research Methods and Procedures A population-based sample of Swedish women was first examined at the ages of 38 to 60 and re-examined 24 years later. This study used 1358 frozen serum samples that had been stored 29 years for analysis of leptin concentrations and their relation to body weight history. Results Leptin values obtained from stored samples showed the same correlation with relative weight as that seen in a contemporary sample with similar demographic characteristics. Lower self-reported birth weight was associated with higher leptin levels in adulthood (p = 0.01), controlling for age and adult BMI. Prospective analyses revealed that high leptin in 38 to 46-year-olds predicted subsequent long-term weight gain (p = 0.003), although no significant associations were seen in women initially aged 50 or older. Discussion: It is feasible to use frozen serum for studying leptin in relation to obesity and related developments many years later. High leptin level was a risk factor for subsequent weight gain in 38- and 46-year-old women. Retrospective analyses involving birth weight suggest that leptin resistance in adulthood might have fetal origins.  相似文献   

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Objective

To assess whether pre-pregnancy body mass index (BMI) modify the relationship between gestational weight gain (GWG) and child birth weight (specifically, presence or absence of low birth weight (LBW) or presence of absence of macrosomia), and estimates of the relative risk of macrosomia and LBW based on pre-pregnancy BMI were controlled in Wuhan, China.

Methods

From June 30, 2011 to June 30, 2013. All data was collected and available from the perinatal health care system. Logistic regression models were used to estimate the independent association among pregnancy weight gain, LBW, normal birth weight, and macrosomia within different pre-pregnancy BMI groups. We built different logistic models for the 2009 Institute of Medicine (IOM) Guidelines and Chinese-recommended GWG which was made from this sample. The Chinese-recommended GWG was derived from the quartile values (25th-75th percentiles) of weight gain at the time of delivery in the subjects which comprised our sample.

Results

For LBW children, using the recommended weight gain of the IOM and Chinese women as a reference, the OR for a pregnancy weight gain below recommendations resulted in a positive relationship for lean and normal weight women, but not for overweight and obese women. For macrosomia, considering the IOM’s recommended weight gain as a reference, the OR magnitude for pregnancy weight gain above recommendations resulted in a positive correlation for all women. The OR for a pregnancy weight gain below recommendations resulted in a negative relationship for normal BMI and lean women, but not for overweight and obese women based on the IOM recommendations, significant based on the recommended pregnancy weight gain for Chinese women. Of normal weight children, 56.6% were above the GWG based on IOM recommendations, but 26.97% of normal weight children were above the GWG based on Chinese recommendations.

Conclusions

A GWG above IOM recommendations might not be helpful for Chinese women. We need unified criteria to classify adult BMI and to expand the sample size to improve representation and to elucidate the relationship between GWG and related outcomes for developing a Chinese GWG recommendation.  相似文献   

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利用与子粒性状相关的QTL标记分析了10个杂交水稻亲本间(5个不育系和5个恢复系)的遗传差异,结合10个亲本所配25个组合的F1表现,研究了基于子粒QTL分子标记遗传距离与粒重及粒重杂种优势的相关性。结果表明分子标记遗传距离与粒重呈显著正相关(r=0.26*),与对照优势呈显著正相关(r=0.28*),与母本优势呈极显著正相关(r=0.41**)。为分子标记预测杂交水稻杂种优势研究奠定了基础。  相似文献   

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Background

The FTO gene, located on chromosome 16q12.2, and the MAF gene, located on chromosome 16q22-23, were identified as genes harboring common variants with an impact on obesity predisposition. We studied the association of common variants with birth weight, gain of body weight, body mass index (BMI), Ponderal index and relevant neonatal outcomes in a large German cohort of infants with a birth weight below 1500 grams.

Methods

The single nucleotide polymorphisms rs9939609 (FTO gene) and rs1424233 (MAF gene) were genotyped using allelic discrimination assays in a prospective multicenter cohort study conducted in 15 neonatal intensive care units in Germany from September 2003 until January 2008. DNA samples were extracted from buccal swabs according to standard protocols.

Results

1946 infants were successfully genotyped at FTO and 2149 infants at MAF. Allele frequencies were not significantly different from other European cohorts. The polymorphisms were in Hardy-Weinberg equilibrium. The polymorphisms did not show associations with birth weight, BMI and Ponderal Index at discharge, and weight gain, neither testing for a dominant, additive nor for a recessive model.

Discussion

Since an association of the polymorphisms with weight gain has been demonstrated in multiple populations, the lack of association in a population of preterm infants with regular tube feeding after birth and highly controlled feeding volumes provides evidence for the hypothesis that these polymorphisms affect food intake behavior and hunger rather than metabolism and energy consumption.  相似文献   

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Objective: To determine the effect of orlistat, a new lipase inhibitor, on long‐term weight loss, to determine the extent to which orlistat treatment minimizes weight regain in a second year of treatment, and to assess the effects of orlistat on obesity‐related risk factors. Research Methods and Procedures: This was a 2‐year, multicenter, randomized, double‐blind, placebo‐controlled study. Obese patients (body mass index 28 to 43 kg/m2) were randomized to placebo or orlistat (60 or 120 mg) three times a day, combined with a hypocaloric diet during the first year and a weight maintenance diet in the second year of treatment to prevent weight regain. Changes in body weight, lipid profile, glycemic control, blood pressure, quality of life, safety, and tolerability were measured. Results: Orlistat‐treated patients lost significantly more weight (p < 0.001) than placebo‐treated patients after Year 1 (6.6%, 8.6%, and 9.7% for the placebo, and orlistat 60 mg and 120 mg groups, respectively). During the second year, orlistat therapy produced less weight regain than placebo (p = 0.005 for orlistat 60 mg; p < 0.001 for orlistat 120 mg). Several obesity‐related risk factors improved significantly more with orlistat treatment than with placebo. Orlistat was generally well tolerated and only 6% of orlistat‐treated patients withdrew because of adverse events. Orlistat leads to predictable gastrointestinal effects related to its mode of action, which were generally mild, transient, and self‐limiting and usually occurred early during treatment. Discussion: Orlistat administered for 2 years promotes weight loss and minimizes weight regain. Additionally, orlistat therapy improves lipid profile, blood pressure, and quality of life.  相似文献   

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PURPOSE OF REVIEW: Low-fat high-carbohydrate diets for weight loss have been challenged by alternative dietary approaches such as low-carbohydrate, high-protein or low glycaemic index. This review summarizes recent evidence on short-term metabolic effects and long-term adherence. RECENT FINDINGS: Very low carbohydrate freely fed diets containing less than 60 g carbohydrate per day appear more effective at inducing weight loss over 6 months than low-fat kilojoule-controlled diets although long-term compliance to both are equally poor. The LDL-cholesterol level did not increase in most studies and triglyceride levels fell dramatically in all studies, although none of the studies measured lipids in energy balance. Direct comparisons of the long-term efficacy and safety of low-fat and low-carbohydrate ad libitum diets are needed. High-protein diets with moderate levels of both fat and carbohydrate and diets low in glycaemic load are emerging dietary strategies, with medium-term benefits having been demonstrated in individuals with insulin resistance. Diets low in glycaemic index require larger studies to establish their efficacy for weight loss and cardiovascular disease risk reduction. SUMMARY: A variety of dietary approaches to achieve weight loss are consistent with metabolic improvements in cardiovascular risk in the short term. Long-term efficacy may depend on the intensity of education and frequency of follow-up more than the dietary composition per se.  相似文献   

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LOWE, MICHAEL R, KAREN MILLER-KOVACH, NEMA FRYE, AND SUZANNE PHELAN. An initial evaluation of a commercial weight loss program: short-term effects on weight, eating behavior, and mood. Obes Res. 1999;7:51–59. Objective : This paper describes an initial, 4-week evaluation of a commercial weight loss program. Research Methods and Procedures : Respondents (n = 985) to newspaper advertisements in two metropolitan areas were assigned to 4 weeks of either the Weight Watchers program or to a Self-Help condition. Weight loss, psychological vitality, and eating behavior were evaluated before and after the 4-week intervention. Results : Weight Watchers participants showed greater improvements than Self-Help participants on all measures; weight losses averaged 1.87 and 0.77 kg, respectively. The superior outcomes shown by Weight Watchers participants on measures of vitality and eating behavior were still evident when extent of weight loss was controlled. Weight losses across different sites, incomes, and levels of obesity were similar. Discussion : Although the present study's intervention and outcome assessments were short-term, the promising results obtained suggest that longer term studies should be undertaken.  相似文献   

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