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Biomedical subjects

B Luke

Publications and source records attributed to B Luke.

At least 55 records · Page 3Linked to original sources
PubMed1991

The effect of maternal height on birth weight and birth length.

This retrospective study examined the gestational age at which differences were observed between birth weights and birth lengths of infants whose mothers differed by height. Infants whose gestational ages were between 24 and 42 weeks born to women 59-62 inches (150-157 cm) tall were compared to similar infants born to women 66-69 inches (168-175 cm) tall. Significant differences occurred in birth weight and birth length from 35 weeks onward. The infants of the shorter women were symmetrically smaller than the infants of the taller women as the infant ponderal indexes did not differ.

Birth Weight↗
PubMed1991

Gestational age-specific birthweights of twins versus singletons.

In order to more adequately characterize patterns of intrauterine growth retardation in twins, the mean birthweights of all nonanomalous white or black twins born between 24 and 41 weeks of gestation and surviving until discharge over an 11-year period (547 infants) and all similar singletons (19,072 infants) were compared by completed weeks of gestation. Between 24 and 35 weeks of gestation, the mean birthweights for the 547 twins and the 19,072 singletons were comparable and did not consistently differ statistically. From 36 to 41 weeks gestation, however, the difference became large, consistent, and statistically significant for each week at P less than 0.0001. This difference was present among all subgroups of twins, ie, in all males, females, blacks, and whites; it was still evident when the sample was further stratified by both race and sex (black males, white males, black females, white females). These data suggest a pattern of growth retardation in twins compared to singletons which is large, consistent, and statistically significant beginning at 36 weeks gestation. Clinically, these data also suggest the need for ultrasonic examination early in gestation (24-32 weeks) to document normal growth and to provide baseline data, and show the importance of such monitoring later in gestation, specifically after 36 weeks.

Baltimore↗
PubMed1991

Pregravid weight, gestational weight gain and current weight of women delivered of twins.

To determine whether large gestational weight gains result in higher maternal body weight within two years post-partum, we administered an anonymous survey to 423 mothers of twins at the Annual Twinsday Festival in Twinsburg, Ohio, in 1989 and 1990. Data collected included pregravid and current weight, age and parity, gestational weight gain and length of gestation. Data were grouped by patient age (18-24 years, 25-34 years and 35-44 years), parity (primipara or multipara) and length of gestation as preterm (less than 37 weeks) and term (greater than or equal to 37 weeks). Statistical analysis included paired t-tests, unpaired t-tests and chi-square as appropriate. Except for multiparas in the oldest age category, the mean current weight was higher than pregravid weight for each age and age/parity category. Comparison across age categories showed in pattern of increasing pregravid weight with increasing age for the total study sample (all women) and for primiparas; among multiparas, this trend was not as evident. Our findings suggest that large weight gains in twin gestations do not result in higher maternal body weight within two years postpartum. Such gains are associated with better intrauterine growth and should be considered when formulating weight gain recommendations for twin gestations.

Adolescent↗
PubMed1990

The attachment of collagenous ligament to stereom in primary spines of the sea-urchin, Eucidaris tribuloides.

The similar proximal and distal attachments to the stereom of primary spine ligament in the echinoid Eucidaris tribuloides are described, from thin sections and SEM studies on frozen and fractured spine articulations and ligaments from decalcified material. The orthogonal structure of the general stereom is modified on the attachment zones where bundles of collagen cylinders enter approximately hexagonally arranged channels. Straps of collagen extend in parallel series between adjacent bundles via regularly placed ports and collagen loops rather than non-striated 'tendons' pass over skeletal trabeculae. The regular pattern of collagen straps is most evident on the proximal and distal attachment zones. Mechanical features of the non-adhesive mode of attachment are considered, together with similarities and differences between insertion of muscle cells and mutable collagenous tissue (ligament) in echinoderms.

Animals↗
PubMed1990

A prospective survey of reactions to blood tests by children and adolescents.

A sample of 171 children and adolescents aged 3-17 years requiring venepuncture for blood sampling were asked to report on their pain and anxiety and were observed immediately before and during blood drawing. Depending on the measures used, 36-64% of children from 3 to 6 years old experienced moderate to severe distress from blood drawing. Multiple regression analysis revealed that age and the parents' prediction of how upset the child would feel before the blood test was a significant predictor of the observed distress and the self-report of pain. Experience with previous needle procedures did not add significantly to the prediction of distress. Identification of children at high risk to respond poorly to painful medical procedures is discussed.

Adolescent↗
PubMed1990

Monozygotic twinning as a congenital defect and congenital defects in monozygotic twins.

The process of monozygotic twinning in animals and humans is presented. In addition, congenital defects in monozygotic twins versus dizygotic twins and singletons is discussed. Overall, the rates of congenital anomalies are higher among whites as compared to blacks, males as compared to females, and multiples as compared to singletons. The highest rates are among infants born to women in the oldest age category and infants with birth weights below 2,000 g. Among white infants, live births in plural deliveries had 22% more congenital anomalies as compared to single live births. Among black infants, the rate was only 4% higher among multiples. It has been suggested that the more frequent occurrence of low birth weight and preterm delivery among multiple births and by race are critical to the higher incidence of congenital anomalies in twins. Newer theories relating the twinning process to congenital anomalies in twins are also presented.

Adolescent↗
PubMed1990

The challenge of maternal phenylketonuria screening and treatment.

All newborn infants, male and female, have been screened for phenylketonuria (PKU) since 1961. Medical therapy is generally continued until age 6. The first cohort of treated females reached reproductive age 15 years ago, and new members are joining this cohort annually. This paper reviews the implications of childbearing in women who were treated for PKU as children and are no longer under treatment. Untreated maternal PKU can lead to mental retardation in utero.

Adolescent↗
PubMed1986

Structure-activity studies of morphiceptin analogs: receptor binding and molecular determinants of mu-affinity and selectivity.

In this study we report the systematic investigation of conformational profiles and electronic properties of a series of analogs of the mu-selective opioid peptide, morphiceptin, together with receptor-binding studies of some of these analogs. In particular, we have investigated the effect of: substitution in the second position, substitution of D-Pro for L-Pro in the second and fourth positions, the addition of an N-methyl group at the third position, and variations in the carboxyl end group. The binding studies confirm the preference of these analogs for mu- versus delta-receptor-binding sites and also indicate differences in mu-receptor affinity among them. The theoretical analyses allow identification of a preferred conformation leading to high mu-receptor affinity and two reliable indicators of relative mu-receptor affinities. These properties are the energy required to obtain the candidate mu-binding conformer and the extent to which each compound overlaps with the highest affinity compound in this conformation. In addition, electronic interactions deleterious to high affinity mu-binding are identified.

Amino Acid Sequence↗
PubMed1986

Theoretical studies of cytochrome P-450. Characterization of stable and transient active states, reaction mechanisms and substrate-enzyme interactions.

The techniques of theoretical chemistry embodied in ab initio and semiempirical quantum mechanical and empirical energy methods have been used to elucidate the relationship between structure, spectra and function of the oxidative metabolizing heme proteins, the cytochrome P-450s, using a recent X-ray structure of a P-450cam-camphor complex. Specifically, the origin of the spin state changes when substrate binds to the oxidized resting state and the nature of the transient biologically active oxygen transfer state have been described. Mechanisms of hydroxylation and epoxidation, the two fundamental oxidative reactions performed by these enzymes, have been deduced and the role of substrate binding and orientation on product distribution investigated.

Binding Sites↗
PubMed1985

Evaluation of a simple immunodiffusion technique for quantitation of platelet-associated immunoglobulin G in childhood immune thrombocytopenias.

Platelet-associated IgG (PAIgG) was quantitated in 33 children with immune thrombocytopenia and platelet counts less than 100 X 10(9)/liter using a simple radial immunodiffusion (RID) assay. Elevated PAIgG levels were found in 76% (16/21) of children with acute idiopathic thrombocytopenic purpura (ITP), 88% (7/8) of children with chronic ITP, and all four children studied with systemic lupus erythematosus and thrombocytopenia. Normal PAIgG values were found in children with the following disorders: malignancy and chemotherapy-related thrombocytopenia; ITP in remission (platelet counts greater than 150 X 10(9)/liter); various nonimmune hematologic disorders and juvenile rheumatoid arthritis, these children having normal platelet counts. In children with acute ITP, elevated PAIgG values at initial presentation fell to within the normal range when clinical remission occurred. The RID assay can be easily established in most hematology laboratories and has the advantage that solubilized "test" platelets used in the assay can be stored frozen prior to analysis. We conclude that this simple technique is of value in the evaluation of childhood thrombocytopenic states and yields results comparable to those reported using more complex antiplatelet antibody assays.

Adolescent↗
PubMed1984

A consideration of height as a function of prepregnancy nutritional background and its potential influence on birth weight.

The influence of height and delivery weight (pregravid and gestational gain), expressed as percent ideal weight for height, upon birth weight was examined in 696 uncomplicated term pregnancies. Each gravida was classified by delivery weight as short, average, or tall. Mean infant birth weight paralleled increasing maternal delivery weight percent in all three height groups, although the effect was most pronounced among gravidas of short stature (r = +0.997). In that group, a 10% increase in delivery weight was reflected by an increase of 127 gm in mean infant birth weight. Among gravidas of average stature, a 10% increase in delivery weight resulted in an increase of 74 gm in mean infant birth weight (r = +0.983). A 10% increase in delivery weight among gravidas of tall stature resulted in an increase of 87 gm in mean infant birth weight (r = +0.938). The incidence of both severe and moderate intrauterine growth retardation was found to be inversely proportional to increasing delivery weight percent among gravidas of short and average stature. Adequate pregravid weight and liberal gains appeared to augment optimal growth in all gravidas studied but were of particular benefit to the infant of the short gravida.

Birth Weight↗
PubMed1982

Acyclovir and vidarabine monophosphate: comparison of iontophoretic and intravenous administration for the treatment of HSV-1 stromal keratitis.

We determined the therapeutic efficacy of iontophoretic application of acyclovir and vidarabine monophosphate (ara-AMP) for the treatment of herpes simplex virus (HSV) type 1-induced stromal keratitis in rabbits. The therapeutic efficacy of intravenous administration of acyclovir was assessed in the same model. Stromal keratitis was produced by intrastromal injection of 10 microliters purified HSV-1, McKrae strain. Treatment began the first day after intrastromal injection. Iontophoresis (0.5 mAmp for four minutes) of 3.4 percent (0.1 M) ara-AMP and 5.0 percent (0.22 M) acyclovir was performed once daily for five consecutive days in two treatment groups. Intravenous administration of 50 mg acyclovir/kg was performed twice daily for eight consecutive days. Intravenous administration of NaCl (0.14 M) and ocular iontophoresis of NaCl (0.14 M) were performed as controls in the two treatment groups. At least two scorers performed a single masked evaluation of the disease severity (lesion scoring) of the conjunctiva, corneal epithelium, stroma, and iris by still lamp examination. The eyes were scored daily for 12 consecutive days, and then every other day up to day 22. Iontophoresis of acyclovir or ara-AMP significantly reduced the course of the disease compared with iontophoresis of NaCl. Intravenous administration of acyclovir significantly reduced the disease compared with intravenous NaCl. This suggests that iontophoresis of acyclovir or ara-AMP either alone or in combination with intravenous administration of acyclovir may be of value in the treatment of HSV-1 stromal keratitis.

Acyclovir↗
PubMed1982

Intracellular localization of lead in tissues of the mute swan.

The aim of this study was to examine the ultrastructure of kidney, liver, blood and intestine of a lead-poisoned bird and compare these with tissues of a healthy bird. From these results it was hoped to reveal that any abnormalities observed were due to lead poisoning and consequently suitable sections were also selected for X-ray analysis. Renal intranuclear inclusions were present in the lead-poisoned swan. X-ray analysis clearly demonstrated that these granules consist of an amorphous mass of lead probably as lead phosphate. Large numbers of electron dense granules were observed in the liver of the lead-poisoned bird and occasionally in the healthy swans liver. X-ray analysis demonstrated that these granules contain iron. Some of the red blood cells of the lead-poisoned swan have opaque granules associated with the plasma membrane, these were not observed in the healthy swan.

Animals↗
PubMed1981

Sodium ion and the neutrotransmitter-stimulated 32P labelling of phosphoinositides and other phospholipids in the iris muscle.

The effects of Na+, other cations and the neurotransmitters, acetylcholine and norepinephrine on 32Pi incorporation into phospholipids of the rabbit iris smooth muscle were investigated [1]. The basal 32P-labelling of phospholipids including phosphatidic acid, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine and the polyphosphoinositides increased with Na+ concentration [2]. The neurotransmitter-stimulated 32P labelling of phosphatidic acid, phosphatidylinositol and phosphatidylcholine is dependent on the presence of extracellular Na+ [3]. The monovalent cation requirement for Na+ specific. Of the monovalent cations Li+, NH+4, K+, Choline+ and Tris, only Li+ partially substituted for Na+ [4]. A significant decrease in 32P labelling of phospholipids in response to acetylcholine was observed when Ca2+ and/or K+ were added to an isoosmotic medium deficient of Na+ [5]. Ouabain, which blocks the Na+-pump, inhibited the basal 32Pi incorporation into phosphatidylcholine and the acetylcholine-stimulated 32P labelling of phosphatidic acid, phosphatidylinositol and phosphatidylcholine [6]. It was suggested that phosphoinositide breakdown is associated with Ca2+ influx as we have previously reported (Akhtar, R.A. and Abdel-Latif, A.A. (1978) J. Pharmacol. Exp. Ther. 204, 655-668) and that the enhanced 32P-labelling of phosphoinositides could be associated with Na+ outflux, via the Na+-pump mechanism.

Acetylcholine↗