Biomedical subjects

R Yip

Publications and source records attributed to R Yip.

At least 91 records · Page 5Linked to original sources

PubMed1988

Altitude and childhood growth.

To assess the possible influence of altitude on childhood growth in the United States, we used data collected by the Centers for Disease Control Pediatric Nutrition. Surveillance System from eight mountain states to determine the height and weight status of children aged 5 years or younger enrolled in various public health programs between 1982 and 1984. The mean birth weight, height-for-age, weight-for-age, and weight-for-height indicators were found to decline significantly with increasing altitude, starting at an elevation greater than 1500 m (p less than 0.001, ANOVA). The reduction in growth was observed for all age groups and all birth weight groups studied. Part of the observed reduction in growth could be attributed to the lower birth weight of children born at higher altitude. However, the reduced growth status persisted after controlling for birth weight, suggesting the presence of an extrauterine growth retardation effect related to altitude.

Altitude↗

PubMed1988

The roles of inflammation and iron deficiency as causes of anemia.

Inflammatory disease as well as iron deficiency may play an important role in the cause of anemia in the United States. We evaluated the relationships between Fe deficiency, inflammatory disease, and anemia using data from of the First National Health and Nutritional Examination Survey (NHANES I). Fe nutrition index was based on the ratio of serum Fe to Fe-binding capacity (Fe:TIBC) and inflammatory index was based on erythrocyte sedimentation rate (ESR). Groups with the highest prevalence of anemia were younger children, young women, and elderly men. Fe deficiency (low Fe:TIBC) was most common among the anemic children and young women but rare in anemic elderly men. Conversely, inflammation (high ESR) was most common among anemic elderly individuals. The prevalence of anemia was more than twice as high in the lowest than in the highest income group. Relative contributions of Fe deficiency and inflammation to anemia did not differ substantially among income groups.

Adolescent↗

PubMed1988

Birth weight and childhood growth.

Most previous studies of the relationship between birth weight and childhood growth have concentrated on the growth of low birth weight infants. To examine this relationship throughout the full range of birth weights, growth data for children less than 5 years of age from the Tennessee Special Supplemental Food Program for Women, Infants, and Children linked to birth certificate records for 1975 to 1985 were used. Growth status was compared for 500-g birth weight categories from 1,000 g to 4,999 g using mean Z scores and the percentage of children more than 2 SD above or less than 2 SD below the median for height for age, weight for age, and weight for height. Infants with lower birth weights were likely to remain shorter and lighter throughout childhood, especially those who were intrauterine growth retarded rather than premature. Conversely, those infants with higher birth weights were likely to remain taller and heavier and to have a higher risk of obesity. Birth weight is a strong predictor of weight and height in early childhood, not only for low birth weight children but also for those of normal and high birth weight.

Age Factors↗

PubMed1987

Declining prevalence of anemia among low-income children in the United States.

To determine the anemia trends among low-income US children, hematologic measurements obtained from children aged 6 to 60 months who were enrolled in public health programs in six states that were consistently monitored by the Centers for Disease Control Pediatric Nutrition Surveillance System were studied. Overall, the prevalence of anemia has declined steadily from 7.8% in 1975 to 2.9% in 1985. The prevalence of anemia declined significantly among children seen at preenrollment screening visits, as well as those seen at follow-up visits, suggesting a generalized improvement in childhood iron nutritional status in the United States, as well as a positive impact of public health programs. To ensure that the declining trend of anemia was not a function of a change in the population of children enrolled in the surveillance system, Tennessee nutrition surveillance records were further analyzed; these records were linked with birth records to obtain detailed socioeconomic status (SES) information. Even though the SES composition remained stable from 1975 to 1984, the prevalence of anemia has declined significantly within each SES group. These findings indicate a true decline in the prevalence of anemia among low-income children that is likely the result of improvements in childhood iron nutrition.

Anemia↗

PubMed1987

Influence of maternal birth weight on rate of fetal growth and duration of gestation.

Birth certificates of infants born in Tennessee during 1979 to 1984 were linked with the birth certificates of their mothers, who were born in Tennessee during 1959 to 1966 (n = 43,891) to study the association between maternal and infant birth weights. A highly significant association (P less than 0.0001) between maternal and infant birth weights was found for both blacks and whites. Women who weighed 4000 to 4499 g at birth were at lowest risk for delivery of a small for gestational age (SGA) infant (5.9% for whites, 4.8% for blacks). The risk of giving birth to an SGA infant increased with decreasing maternal birth weight, reaching a maximum of 19.8% for white mothers who weighed 2000 to 2499 g at birth, and 20.0% for black mothers who weighed 1000 to 1499 g at birth. In contrast, the rate of preterm birth varied much less by maternal birth weight for both whites and blacks. These data suggest that maternal birth weight exerts a stronger influence on intrauterine growth than on the duration of gestation. Women who were smaller than average at birth should be considered at high risk for delivery of an SGA infant.

Birth Certificates↗

PubMed1987

Altitude and birth weight.

The effect of altitude on birth weight was measured with data in U.S. natality records from 1978 to 1981 after correlation with the mean altitude of the mother's resident county. For comparison of the low birth weight (LBW) rate at different altitudes, certain socioeconomic risk factors known to affect birth weight were controlled by the selection of an idealized subpopulation of singleton births. With 500 m gradations for altitude, a curvilinear dose-response relationship of birth weight reduction with increasing altitude was demonstrated (P less than 0.001). In comparison with neonates born at sea level, neonates born at higher altitudes (greater than 2000 m) had a twofold to threefold increase in LBW rate, mainly related to a higher incidence of intrauterine growth retardation. Comparison of the LBW rate on the basis of small geographic divisions in the mountain states showed a positive correlation between the LBW rate and the high altitude. The birth weight frequency distribution curves of the idealized subpopulation at each altitude approximate normal distributions and parallel one another, indicating that altitude has a general effect on all births. Such nearly normal birth weight distributions allowed the determination of altitude-specific LBW cutoff limits that can be used to detect areas of greater risk for LBW but independent of the altitude effect.

Altitude↗

PubMed1987

Developmental changes in calmodulin-kinase II activity at brain synaptic junctions: alterations in holoenzyme composition.

Synaptic junctions (SJs) from rat forebrain were isolated at increasing postnatal ages and examined for endogenous protein kinase activities. Our studies focused on the postnatal maturation of the multifunctional protein kinase designated Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II). This kinase is comprised of a major 50-kilodalton (kDa) and a minor 60-kDa subunit. Experiments examined the developmental properties of CaM-kinase II associated with synaptic plasma membranes (SPMs) and synaptic junctions (SJs), as well as the holoenzyme purified from cytosolic extracts. Large developmental increases in CaM-kinase II activity of SJ fractions were observed between postnatal days 6 and 20; developmental changes were examined for a number of properties including (a) autophosphorylation, (b) endogenous substrate phosphorylation, (c) exogenous substrate phosphorylation, and (d) immunoreactivity. Results demonstrated that forebrain CaM-kinase II undergoes a striking age-dependent change in subunit composition. In early postnatal forebrain the 60-kDa subunit constitutes the major catalytic and immunoreactive subunit of the holoenzyme. The major peak of CaM-kinase II activity in SJ fractions occurred at approximately postnatal day 20, a time near the end of the most active period of in vivo synapse formation. Following this developmental age, CaM-kinase II continued to accumulate at SJs; however, its activity was not as highly activated by Ca2+ plus calmodulin.

Aging↗

PubMed1987

Declining prevalence of anemia in childhood in a middle-class setting: a pediatric success story?

To study trends of anemia among middle-class children, we collected 6,162 hematocrit measurements from the medical records of 2,432 children, ages 9 months through 6 years, as seen at a private pediatric clinic during the past 18 years. A decline in prevalence of anemia was observed during that period. The overall age-adjusted rate of anemia decreased from 6.2% in 1969 to 1973, 5.8% in 1974 to 1977, 3.8% in 1978 to 1981, and 2.7% in 1982 to 1986. The decline was also observed when trends were determined for three age groups using a single hematocrit measurement per child. The 1982 to 1986 prevalences of anemia for various age groups among this middle-class pediatric population were relatively low: 2.8% among 9- to 23-month-old children, 2.4% among 24- to 47-month-old children, and 2.7% among 48- to 83-month-old children. Most of these recent cases of anemia were mild--most were only slightly less than the hematocrit values used to define anemia--and most did not show strong evidence of iron deficiency based on elevated levels of erythrocyte protoporphyrin. We conclude that iron deficiency is now mild and uncommon in these middle-class children. This improved nutritional status with regard to iron is probably related to increased intake of iron among infants and young children during the past two decades. These findings suggest that the recommended screening schedule for iron deficiency with hemoglobin or hematocrit measurements may need to be reassessed for well-defined populations of low-risk children.

Acute Disease↗

PubMed1985

Does iron supplementation compromise zinc nutrition in healthy infants?

Iron supplements are commonly administered to infants in order to prevent iron deficiency. We wished to determine whether iron administration could compromise zinc nutrition as might be suspected from previous studies. Measures of iron nutrition, serum zinc, and serum copper were measured before and after randomization of 291 healthy 1-yr-old infants to a 3 mo course of placebo or iron treatment (30 mg iron as ferrous sulfate given before a meal). There was no significant difference in serum zinc or copper in the two groups before or after treatment; thus iron administration did not result in any evidence of zinc deficiency in a healthy, well-nourished group of T-yr-old infants.

Age Factors↗

PubMed1985

Lack of adverse side effects of oral ferrous sulfate therapy in 1-year-old infants.

An evaluation was made of 278 healthy-appearing 1-year-old infants who were tested for iron deficiency to determine the relative frequency of adverse side effects attributable to oral iron treatment. After obtaining parental informed consent, laboratory tests of iron status were performed on venous blood and infants with hemoglobin level greater than 10.5 g/dL were randomly chosen to receive 1.2 mL of ferrous sulfate (FeSO4) drops (about 3 mg of iron per kilogram per day) or equal volume of placebo for 3 months. After 3 months of treatment, infants were to return to the clinic for repeat blood testing, compliance estimation, and evaluation for possible adverse side effects. There was no significant difference (P greater than .50) in the frequency of vomiting, diarrhea, or fussiness in iron-treated infants (6%) compared with placebo-treated infants (9%). Constipation was slightly more frequently reported (P = .03) in placebo-treated infants (9%) than in iron-treated infants (1%). Compliance with therapy was confirmed in 179 completely evaluated infants by the lack of remaining medication at 3 months, the higher incidence (P less than .0001) of dark stools reported among iron-treated infants, and the changes in laboratory tests of iron status. No parents reported dark stools as an adverse effect of therapy. It is concluded that once daily, moderate-dose FeSO4 therapy given to fasting 1-year-old infants results in no more gastrointestinal side effects than placebo therapy.

Administration, Oral↗

PubMed1984

Height and weight status of Indochinese refugee children. An anthropometric study of 1,650 children.

To provide guidelines for assessing growth status of Indochinese refugee children, height and weight measurements were obtained from 1,650 children residing in Lao refugee camps, Cambodian refugee camps, and surrounding Thai villages. These are compared with the few existing growth references for Asian children. In comparison to US growth standards (National Center for Health Statistics/Centers for Disease Control) for children, the mean weight for age and mean height for age of the studied groups are approximately 2 SDs below US means. Weight for height is 0.7 SD below US means. This marked difference in growth status appears to be due to nutritional factors related more to cultural or economic issues affecting these children than to their genetic background. The US growth standards can serve as reference tools in evaluating the growth status of newly arrived Southeast Asian children, if used with the perspective that Southeast Asian children, on a group basis, have different distributions on US growth curves.

Age Factors↗

PubMed1984

Hematocrit values in white, black, and American Indian children with comparable iron status. Evidence to support uniform diagnostic criteria for anemia among all races.

We compared the hematocrit values of 425 black and 164 American Indian children with an equal number of white children who were matched for sex, age, and iron nutrition status based on serum ferritin level. Black children were found to have a mean hematocrit value 0.7% lower than that of white, matched controls. No hematocrit difference was found between American Indian children and their white controls. This finding in blacks is consistent with those of previous series, except the magnitude of the hematocrit difference is smaller. The lower value in blacks may be accounted for by mild thalassemias, which are associated with lower hematocrit values. The use of the same diagnostic criteria for anemia among all races will permit uniform detection of nutritional anemia as well as a greater rate of diagnosis of certain hereditary hemoglobinopathies.

Anemia↗

PubMed1984

Iron deficiency in infants: the influence of mild antecedent infection.

In this study of 467 healthy term infants seen for routine 1-year health maintenance examination, we determined the influence of mild prior infection on the concentration of hemoglobin and other laboratory evidence of iron deficiency. In addition we studied the Hgb response in 261 infants randomized to receive a 3-month course of treatment with either iron or placebo. Infants who had had one or more clinic visits because of infection during the previous 3 months or who were reported as not being entirely well during the past month or who had an elevated sedimentation rate were more likely to have anemia or "low normal" Hgb, higher erythrocyte protoporphyrin and serum ferritin values, and lower serum iron concentration than infants who had been well. Hgb response greater than or equal to 1 gm/dl after iron treatment occurred more commonly in infants who had had prior visits because of infection. The results indicate that upper respiratory and other mild antecedent infections commonly predispose to iron deficiency (probably because of a decrease in iron absorption).

Anemia, Hypochromic↗

PubMed1984

Developmental changes in erythrocyte protoporphyrin: roles of iron deficiency and lead toxicity.

Iron deficiency and lead toxicity both result in increased erythrocyte protoporphyrin. The purpose of this study was to determine the differences in EP concentration, according to age and sex, obtained in the 2nd National Health and Nutrition Examination Survey of the United States and to determine the extent to which EP differences might be related to iron deficiency or lead toxicity. The highest EP concentrations were found in infants and children. Among adults, women had higher EP values than men. Lead toxicity (blood lead greater than 30 micrograms/dl) and low serum iron concentration/total iron binding capacity (Fe/TIBC less than 16%), often in combination, were associated with elevated EP values in infants and children. In women, elevated EP concentration were related primarily to low Fe/TIBC values, whereas in men there was only a weak association with elevated blood lead concentration. Age/sex differences in EP values diminished markedly when the influences of lead toxicity and iron deficiency were excluded by the above criteria.

Adolescent↗

PubMed1984

Age-related changes in laboratory values used in the diagnosis of anemia and iron deficiency.

Laboratory results from the Second National Health and Nutrition Examination Survey (NHANES II) were used to define age-related changes in laboratory values that are related to the diagnosis of anemia and iron deficiency. Analyses included Hb, hematocrit, red blood cell count, red cell indices, iron, total iron-binding capacity, transferrin saturation, and erythrocyte protoporphyrin. Computation of median values and 95% ranges by age and sex for each laboratory test were performed on 15,093 subjects between 1 and 74 yr of age who had complete laboratory data on venous blood, after excluding those subjects with an abnormality in one or more of three other laboratory tests. Age-related changes in laboratory measurements, such as those described herein, must be taken into consideration in order to optimize the identification of individuals with anemia and iron deficiency.

Adolescent↗

PubMed1984

Prevalence and causes of anemia in the United States, 1976 to 1980.

We estimated the prevalence of anemia in the United States from the results of the Second National Health and Nutrition Examination Survey ( NHANES II, 1976 to 1980). Reference ranges for Hb were first derived from 11,547 subjects in whom laboratory values for serum iron/iron-binding capacity, mean corpuscular volume, and erythrocyte protoporphyrin were all normal (greater than or equal to 16%, greater than or equal to 80 fl, and less than or equal to 75 micrograms/dl red blood cells, respectively). Using these reference standards, the prevalence of anemia (Hb values below the 95% reference range for age and sex) among the 15,093 subjects with complete laboratory results was highest in infants (5.7%), teenage girls (5.9%), young women (5.8%), and elderly men (4.4%). The pattern of laboratory abnormalities in anemic subjects indicated that iron deficiency predominated as a cause in infants and young women in contrast to inflammatory disease in the elderly.

Adolescent↗

PubMed1983

Evidence of peroxidative damage to the erythrocyte membrane in iron deficiency.

The mechanism responsible for reduced red blood cell (RBC) survival in iron deficient infants or animals is unknown. To investigate the possible role of membrane peroxidation in iron-deficiency anemia, we studied RBC membrane lipids and proteins of rats fed iron-deficient (2 ppm Fe) and control (50 ppm Fe) diets between 21 and 41 days of age. Thin-layer chromatography of lipids showed that iron-deficient rats' RBC contained a novel phospholipid (1.9% of the total phospholipid) which moved between phosphatidylserine and phosphatidylethanolamine. Detailed studies showed that this PL is a Shiff's base adduct of phosphatidylserine, phosphatidyl-ethanolamine, and malonyldialdehyde, an end product of lipid peroxidation. Polyacrylamide gel electrophoresis of RBC proteins of iron-deficient rats also showed presence of high molecular protein complexes similar to that formed in in vitro malonyldialdehyde-treated RBC. To examine the role of such membrane cross-linking on in vivo RBC survival, we have studied survival of in vitro malonyldialdehyde-treated RBC in rabbits, 51Cr-T 1/2 of 5 microM malonyldialdehyde-treated RBC, which contained about the same amount of phospholipid/malonyldialdehyde adducts, was reduced to 6 days as compared to 11 days of sham-treated RBC. The in vitro study suggests that peroxidative damage results in significant reduction in RBC T 1/2 and may be analogous to decreased RBC survival in iron-deficient infants and animals.

Anemia, Hypochromic↗

PubMed1983

Developmental changes in serum ferritin and erythrocyte protoporphyrin in normal (nonanemic) children.

We studied 4039 children who were 6 months to 12 yr of age to characterize developmental variations of serum ferritin and erythrocyte protoporphyrin. Age-related descriptive statistics were derived. The -2 SD value for serum ferritin was found to increase progressively from 12 to 21 micrograms/1 with increasing age, while the +2 SD value for erythrocyte protoporphyrin was found to decrease progressively from 65 to 42 micrograms/dl whole blood with increasing age. While the mean serum ferritin value was found to continue to rise throughout the first 12 yr of life, erythrocyte protoporphyrin values were highest at 1 to 2 yr of age, then fell to essentially constant levels after 4 to 6 yr of age. These relationships, as well as the linear relationship of increasing hematocrit and serum ferritin with increasing age, suggest that the rise of hematocrit with age, as previously observed, is associated with improving storage and availability of iron for heme synthesis.

Age Factors↗