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Biomedical subjects

R S Strauss

Publications and source records attributed to R S Strauss.

26 records · Page 2Linked to original sources
PubMed1998

Growth and development of term children born with low birth weight: effects of genetic and environmental factors.

OBJECTIVE: To evaluate the role of intrauterine growth retardation (IUGR) on childhood growth and development, controlling for environmental and genetic factors. METHODS: Women and infants enrolled in the National Collaborative Perinatal Project were analyzed. Weight, length, and IQ were assessed at birth and at 7 years in the entire National Collaborative Perinatal Project population in term infants born with and without IUGR ("population cohort"). To control for genetic and environmental factors, growth and development were also compared in 220 similar-sex term sibling pairs in which one sibling was born with IUGR and one was born without IUGR ("sibling cohort"). RESULTS: At 7 years of age heights and weights of infants born with IUGR remained approximately 0.5 SD less than infants born without IUGR (weight-for-age: p < 0.001, height-for-age: p < 0.001). In the entire National Collaborative Perinatal Project population, IQ (p < 0.001) and Bender-Gestalt (p < 0.001) scores were significantly lower in infants born with IUGR compared with those in infants born without IUGR. There were no significant differences in IQ or Bender-Gestalt scores between siblings born with and without IUGR. However, siblings with IUGR and large deficits in head circumference demonstrated both decreased IQ (p < 0.05) and Bender-Gestalt (p < 0.05) scores. CONCLUSION: Long-term growth deficits associated with IUGR appear largely independent of prenatal or postnatal environmental factors. IUGR had little impact on intelligence and motor development except when associated with large deficits in head circumference.

Body Height↗
PubMed1997

Effects of intrauterine growth retardation in premature infants on early childhood growth.

OBJECTIVE: To evaluate in preterm infants the role of intrauterine growth retardation and infant body proportionality on subsequent childhood growth. METHODS: Preterm infants (818) prospectively enrolled in the Infant Health and Development Program were studied from birth to 36 months of corrected age. Weights and lengths were recorded at eight intervals. Growth parameters were compared in preterm infants with differing body symmetry at birth, defined by length-for-age and weight-for-age. Infants with both low length-for-age and low weight-for-age at birth were categorized as symmetrically growth retarded, and infants with normal length-for-age and low weight-for-age were categorized as asymmetrically growth retarded. RESULTS: Infants born with low length-for-age demonstrated increased growth velocity until 8 months of corrected age (p <0.001). However, infants born with low weight-for-age demonstrated decreased weight-gain velocity compared with preterm infants with appropriate weight for gestational age (AGA) until 40 weeks of corrected age (p <0.001). Heights and weights of infants with either symmetric or asymmetric intrauterine growth retardation remained significantly retarded compared with AGA preterm patients and the National Child Health Survey (NCHS) reference population (p <0.001). Infants born short but with normal weight did not significantly differ from AGA preterm infants in either weight or length at 36 months of corrected age. Preterm infants with both symmetric and asymmetric growth retardation demonstrated limited catch-up growth in weight until age 4 months and then paralleled the AGA preterm patients and the NCHS reference population. Very low birth weight (< or = 1250 gm), gestational age, and a broad-based day-care intervention did not influence growth outcome after control for the presence of intrauterine growth retardation. CONCLUSIONS: Preterm infants with both symmetric and asymmetric intrauterine growth retardation demonstrate limited catch-up growth. Intrauterine growth deficits persist into early childhood.

Body Height↗
PubMed1997

Effects of the intrauterine environment on childhood growth.

The intrauterine environment plays a critical role in childhood growth. Infants exposed to acute malnutrition in early pregnancy are more likely to be obese in later life. Similarly, children exposed to hyperglycemia in utero are also more likely to develop insulin intolerance and obesity during childhood. The mechanisms underlying these changes are not understood. However, animal experiments suggest that severe overnutrition or undernutrition during pregnancy may affect hypothalamic development, or pancreatic beta-cell development. The effects of cigarette smoking on childhood growth can best be explained by the increased risk of intrauterine growth retardation. In contrast, alcohol ingestion during pregnancy leads to a syndromic decrease in childhood head circumference, stature, and weight. The effects of cocaine are most likely multifactorial, since cocaine ingestion tends to covary with tobacco use, alcohol use, opiate use, and low socioeconomic status. The most striking effects of the intrauterine environment on childhood growth are seen in children with intrauterine growth retardation. These children remain significantly lighter and shorter than their peers. Efforts to reverse intrauterine growth retardation have been disappointing, and at times risky. However, caloric supplementation in undernourished populations may be of significant benefit. The use of growth hormone promises to reduce some of the height deficits in children with intrauterine growth retardation. However, to date there is no evidence suggesting changes in final height in children with intrauterine growth retardation who receive growth hormone.

Adolescent↗
PubMed1989

Orotate phosphoribosyltransferase from yeast: studies of the structure of the pyrimidine substrate binding site.

The pH dependencies of both the forward and reverse orotate phosphoribosyltransferase (ORPTase)-catalyzed reactions have been examined and determined to be dissimilar, with maximal activity for the forward reaction near to pH 8. The maximal activity of the reverse pyrophosphorolysis was observed between pH 6.5 and 7.5. Appropriate pK values were determined using computer fitting exercises. One such pK value (equal to 8.6) suggested the presence of lysine residues at the OPRTase active site. Incubations of OPRTase with the substrate analog, uracil 6-aldehyde, in the presence of sodium borohydride, suggested that this compound is a covalent modifier of OPRTase lysine residues, and substrate protection studies provided evidence that the affected lysine residues were located near to both the phosphoribosyl 1-pyrophosphate (PRibPP) and the orotate binding sites. Similar studies with pyridoxal 5-phosphate and labeled sodium borohydride as modifiers have revealed that two modified active site lysine residues per OPRTase subunit account for the loss of 90% of the enzymatic activity with this reagent. We suggest that essential lysine residues, along with divalent metal ions, are located at the OPRTase active site, and form ion-pair bonds with anionic PRibPP and orotate as these substrates bind to the enzyme. We also report that 5-azaorotate is an alternate substrate for OPRTase (Km = 75.5 +/- 0.1 microM) leading to formation of an unstable nucleotide product).

Affinity Labels↗
PubMed1987

Orotate phosphoribosyltransferase and hypoxanthine/guanine phosphoribosyltransferase from yeast: nuclear magnetic relaxation studies of the structures of enzyme-bound phosphoribosyl 1-pyrophosphate.

Nuclear magnetic relaxation rate measurements have been performed on the protons and phosphorus atoms of phosphoribosyl 1-pyrophosphate (PRibPP) in the presence and absence of paramagnetic chromium(III), cobalt(II), and manganese(II) ions. The longitudinal relaxation rates were then used to calculate interatomic distances between the magnetic nuclei and these paramagnetic probes, from which was devised a conformation of the PRibPP-metal ion complex in solution. Thereafter, the experiments were accomplished in the presence of Mn(II) and a series of orotate phosphoribosyltransferase (OPRTase) and hypoxanthine/guanine phosphoribosyltransferase (HGPRTase) concentrations, and from these data were estimated the distances between Mn(II) and the PRibPP nuclei at the active sites of these two enzymes from yeast. Comparisons between the Mn(II)-PRibPP conformation in solution and this structure at the active sites of OPRTase and HGPRTase revealed that the metal ion remained coordinated with the pyrophosphate group of PRibPP in all instances, whereas the overall distances between the ribose ring and Mn(II) at the enzyme active sites were approximately 1 A further from the metal ion. Model building studies also revealed that the 5'-phosphate group of PRibPP is positioned directly over the ribose ring in solution and at the OPRTase and HGPRTase active sites and may protect the 1'-carbon of PRibPP against on-line displacements of pyrophosphate under these conditions, where the PRibPP-to-Mn(II) concentration ratio is greater than 2000.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypoxanthine Phosphoribosyltransferase↗