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Biomedical subjects

B Hopkins

Publications and source records attributed to B Hopkins.

At least 19 recordsLinked to original sources
PubMed1996

Crying patterns in preterm infants.

Healthy infants born at term cry most in the first three months of life, with a peak and increased crying in the evening during the second month. To determine whether the crying of preterm infants manifests similar features, the pattern of crying from 40 weeks gestational age through 24 weeks corrected age was described for 35 relatively healthy preterm infants born between 28 and 34 weeks gestational age. Despite their additional extra-uterine experience, they still cried significantly more after 40 weeks gestational age, with a peak and evening clustering at 6 weeks corrected age. The age of peak crying was not related to gestational age at birth, weight for gestational age, or a variety of perinatal and neurological indices. The results support the argument that the early-peak pattern is a robust maturational feature of early development and may be universal to human infancy.

Age Distribution↗
PubMed1995

Muscle power, sitting unsupported and trunk rotation in pre-term infants.

Discrepancies between active and passive muscle power are often seen in pre-term infants over the first year. Generally of a transient nature, they are most obvious in the extensor muscles of the trunk where there is a high active muscle power relative to the passive component. While high active muscle power may not be a sign of cerebral palsy, it is our contention that it will impair functions such as unsupported sitting and the ability to rotate in this position. In this study, 20 full-term and 37 healthy pre-term infants were assessed at the (corrected) ages of 39 and 52 weeks for muscle power in the trunk, sitting unsupported and rotation around the body axis while seated. At the age of 39 weeks, all full-term infants could sit without support. In contrast half of the pre-term infants could not sit without support and the majority of them could not rotate the trunk in this position. At 52 weeks the majority of pre-term infants could sit without support, despite having higher active muscle power in the trunk. However this deviant muscle power prevented rotatory movements of the trunk during sitting. The origin of this deviance may reside in the positioning to which pre-term infants are subjected after birth and thus postural management should be directed towards avoidance of extensor positions.

Adolescent↗
PubMed1995

The association of moderate maternal and paternal alcohol consumption with birthweight and gestational age.

Heavy maternal alcohol consumption during pregnancy has been associated with fetal growth retardation, but whether more moderate consumption also is associated remains a controversial issue. We examined moderate consumption in 1233 women with singleton livebirths, by calculating a weighted average of weekly consumption in the first 20 weeks from questions that asked about alcohol consumption before pregnancy, as well as any changes during the first half of pregnancy. The adjusted odds ratio for ("moderate") consumption of three or more drinks per week for low birthweight was 2.6 [95% confidence limits (CL) = 1.2, 5.7], and that for intrauterine growth retardation was 2.3 (95% CL = 1.2, 4.6). Examining the joint effect of smoking with alcohol consumption revealed associations that differed by outcome; we found a synergistic effect for low birthweight, but not for intrauterine growth retardation. Moderate alcohol consumers had an average birthweight decrement of 143 gm, which varied by smoking. There was little association of alcohol consumption with preterm delivery (< 37 weeks). Paternal alcohol consumption was not associated with any of the fetal growth measures after adjustment for other variables.

Alcohol Drinking↗
PubMed1994

Prenatal head position from 12-38 weeks. I. Developmental aspects.

Fetal head position relative to the fetal body was studied longitudinally in 10 uncomplicated pregnancies by means of real-time ultrasound. Registrations were made at 4 weekly intervals from 12 to 36 weeks, and at 38 weeks. The percentage of assessments with optimal visualization of head position for analysis increased with age. The development of head position involved a change from a midline to a lateralized preference. It was only at 38 weeks that a clear lateralized head position was found with the head being held mainly to the right. The degree of intra- and inter-individual variability was considerable, a finding typical of motor behaviour in the healthy fetus. It is hypothesized that this bias is due to neural maturation. The implications of our findings for the subsequent development of hand preference are discussed.

Embryonic and Fetal Development↗
PubMed1994

Prenatal head position from 12-38 weeks. II. The effects of fetal orientation and placental localization.

The possible influence of placental localization and fetal orientation on a predominant fetal head position was studied longitudinally in 10 uncomplicated pregnancies from 12 to 38 weeks by means of real-time ultrasound. Throughout gestation, when the fetal vertebral column was oriented to the left side of the mother, head positions to the right and in midline were seen most frequently, whereas a vertebral column to the right was more often associated with a head left position and a head position in midline. These findings support the suggestion that when the fetal vertebral column is in a lateral orientation relative to the mother, one side of the fetal head is more likely to be restricted by the pelvis and backbone of the mother. However, the orientation of the fetal vertebral column does not seem to be a determining factor as the incidence of lateralized head positions increased with age, while the incidence of a vertebral column to the right or left side of the mother remained unchanged. No associations were found between the localization of the placenta and either head position or fetal lie.

Embryonic and Fetal Development↗
PubMed1994

The development of head position preference in preterm infants beyond term age.

Healthy full-term infants show a developmental trend in head position from an initial right-sided preference to one with the head in midline around the age of 12 weeks. We studied the effects of intrauterine growth retardation (IUGR) and the degree of prematurity on both aspects of development from 35 weeks postmenstrual age to 18 weeks corrected age in 35 preterm infants without overt neurological abnormalities and whose gestational ages ranged from 27 to 34 weeks. Our data reveal that, during the preterm period, infants born after pregnancies of 32 weeks or less showed a lack of right-sided preferences for head turning after release from midline but not for the subsequent maintenance of a position. IUGR did not seem to affect either preference. After term age a right-sided preference diminished while a head midline position increased. The latter was not significantly delayed in relation to birth before 32 weeks gestation or IUGR. However, when infants were classified on the basis of neurological differences as reflected in a (mildly) abnormal movement quality, a delay in the attainment of a midline posture was observed, which suggests it is related to a suboptimal neurological condition. This delay, however, was also accounted for by the side-to-side flattening of the skull.

Birth Weight↗
PubMed1994

Prematurity, posture and the development of looking behaviour during early communication.

This study concerns the developing relationship between motor control and looking behaviour in full term (N = 15) and pre-term (N = 29) infants during face-to-face interaction with the mother at 6, 12 and 18 weeks of corrected age. Infants with inborn errors or major medical complications were excluded. In the pre-term infants the development of head and arm postures during interaction differed from the full term pattern, especially in infants born before 32 weeks and/or small-for-gestational age. The full term infants were more advanced than other infants in the ability to grasp an object. These findings were related to group differences in looking behaviour, suggesting that differences in the development of looking behaviour may be (partly) accounted for by differences in the development of motor control.

Communication↗
PubMed1994

Mesh reinforcement increases bursting strength of intestinal anastomoses in steroid-treated rabbits.

We tested the hypothesis that reinforcement of small bowel anastomoses with polyglycolic acid mesh (PGAM) would increase bursting strength in steroid-treated subjects. Twenty-two New Zealand white rabbits weighing 3-4 kg received methylprednisolone 0.2 mg/kg/day IM for 7-13 days preoperatively and until killed 4-5 days postoperatively. Steroid effect was confirmed by a 58.3 per cent decrease in absolute lymphocyte count and a histologic reduction in anastomotic fibroblast proliferation and collagen deposition. Two small bowel anastomoses were performed in each animal using standard two-layer suture technique. One of the two anastomoses, randomly assigned, was circumferentially reinforced with PGAM such that each animal served as its own control. Anastomotic bursting pressures, determined on postoperative Day 4-5, were significantly higher in mesh-reinforced anastomoses (P = 0.003). Histologic examination of the reinforced anastomoses revealed a well-developed layer of fibroblasts and collagen between the PGAM and bowel wall serosa. These results demonstrate that polyglycolic acid mesh reinforcement significantly increases the bursting strength of small bowel anastomoses in steroid-treated rabbits.

Anastomosis, Surgical↗
PubMed1994

The use of minisatellite variant repeat-polymerase chain reaction (MVR-PCR) to determine the source of saliva on a used postage stamp.

In this paper we report the identification of an individual using the MVR-PCR technique on DNA extracted from single and multiple discs (3 mm) punched from a licked stamp attached to an envelope. The individual's code was successfully and uniquely matched to one already present within a database of 500 MVR codes which had been generated in a separate laboratory. The exercise illustrates the suitability of MVR-PCR for forensic samples and demonstrates the power of this rapid and novel identification system.

DNA, Satellite↗
PubMed1993

Human bradykinin B2 receptor: nucleotide sequence analysis and assignment to chromosome 14.

Functional cDNA clones for human bradykinin B2 receptor were isolated from uterus RNA by a polymerase chain reaction (PCR)-based method and by screening a human cosmid library with rat bradykinin B2 receptor probe. We isolated several overlapping clones from the cosmid library, each of which encodes the entire protein coding sequence. The human bradykinin B2 receptor gene codes for a 364-amino-acid protein with a molecular mass of 41,442 Da that is highly homologous to rat bradykinin B2 receptor cDNA (81%). The entire human cDNA sequence was cloned into an expression vector and mRNA was synthesised by in vitro transcription. Applications of bradykinin caused membrane current responses in Xenopus oocytes injected with the in vitro-synthesized mRNA. Preincubation with the potent B2 antagonist, HOE140, prevented this response. The genomic clone is intronless, and we have identified an upstream promoter region and a downstream polyadenylation signal. The human bradykinin B2 receptor gene has been mapped to chromosome 14 using PCR to specifically amplify DNA from somatic cell hybrids.

Amino Acid Sequence↗
PubMed1993

Qualitative changes in general movements and their prognostic value in preterm infants.

Qualitative assessments of general movements have been shown to have considerable power in predicting neurological outcomes in preterm infants with brain damage. In the present study such assessments were made in 35 preterm infants without major neurological problems before term age, born between 27 and 34 weeks gestation, of whom 12 were small-for-gestational-age (SGA). Most infants maintained a normal or (mildly) abnormal quality from 35 weeks postmenstrual age through 6, 12, 18 to 24 weeks corrected age. Seven changed from initially abnormal movements to a normal quality, six of them after 12 weeks. Differences between SGA and appropriate-for-gestational-age infants became less evident with age, particularly after 12 weeks. This was not the case when comparisons were made on the basis of gestational ages below or above 32 weeks. The prediction of neurological and mental outcomes at 1 year also improved after 12 weeks, around which age a major transformation in neural functions occurs. It is concluded that assessments of movement quality are particularly successful in predicting abnormal outcomes in comparison to examinations based on muscle tone and elicited responses.

Age Factors↗
PubMed1993

Mental and motor development in preterm infants: the issue of corrected age.

This paper addresses the question of whether corrected age needs to be applied to both the mental and motor development of preterm infants during the whole of the first year. A neglected problem in this respect is that a precise developmental index cannot be found with very low or very high raw scores. Using an alternative measure of performance (age equivalent deviation score), 36 preterm infants without serious medical or neurological problems were compared with 21 full-term infants on the Dutch version of the Bayley Mental Scale at the corrected ages of 12, 18, 24, 39 and 52 weeks and the Psychomotor Scale at 24, 39 and 52 weeks. Our findings suggest that full correction should be used in assessing the mental development of relatively healthy preterm infants during the second half of the first year. Assessments at earlier ages seem to overestimate the mental abilities of preterm infants, thus indicating that partial correction should be applied at these ages. For motor development during the second half of the first year a partial correction would seem more appropriate. The clinical implications of our findings are discussed.

Aging↗
PubMed1993

Development of muscle power in preterm infants: individual trajectories after term age.

In a longitudinal study individual trajectories were traced for the developing relationship between active and passive muscle power in preterm (n = 37) and fullterm (n = 20) infants from term to 24 weeks (corrected) age. Such trajectories should enable the identification of those infants at highest risk for later neurological dysfunctions. This contention is supported by the findings of this study: those preterm infants who showed marked discrepancies between the two sorts of muscle power or rigidity in both beyond 12 weeks corrected age were most likely to manifest neurological problems at 52 weeks of age.

Female↗
PubMed1993

A longitudinal study of neural maturation and early mother-infant interaction: a research note.

The development of postural control of the head and of looking towards and looking away from the mother is described; the age relationship between attainment of postural head control and looking towards the mother is investigated and the relation between smiling and "pleasure" vocalizations to looking towards and away is examined. Twelve normal, full-term mother-infant pairs participated in this home-based study. En face interaction was video-taped for maximally 15 min at 3, 6, 9, 12, 15 and 18 (or 21) weeks. We conclude that postural head control constitutes an important prerequisite for the emergence of socially directed behaviours during en face interaction.

Attention↗
PubMed1993

Effects of birthweight status and gestational age on the quality of general movements in preterm newborns.

It is hypothesised that individual differences in nervous system functioning, undetected by a neurological examination, are reflected in the quality of spontaneous movements of preterm newborns. Given this hypothesis it is expected that a short pregnancy duration and IUGR will be related to an abnormal movement quality. These expectations were confirmed in a group of 37 small-for-gestational-age and appropriate-for-gestational-age preterm newborns with gestational ages ranging from 27 to 34 weeks without serious perinatal complications and for whom no overt neurological abnormalities could be detected based on the evaluation of elicited responses and tonus at the postmenstrual age of 35 weeks. The quality of general movements was adversely affected by both IUGR and a pregnancy duration below 32 weeks. Newborns with an abnormal movement quality also had significantly lower obstetrical optimality scores. Previous research has shown these scores to be related to the neurological condition of the newborn. We conclude that observations of movement quality, being neither intrusive nor time consuming, may constitute a useful addition to the neurological assessment of preterm newborns without serious perinatal complications.

Birth Weight↗
PubMed1993

Pharmacological characterization of cloned human NK-2 (neurokinin A) receptor expressed in a baculovirus/Sf-21 insect cell system.

Using the novel ligand [4,5-3H-Leu9]neurokinin A ([4,5-3H-Leu9] NKA) in a receptor binding assay, we characterized the pharmacology of a cloned neurokinin NK-2 receptor from human lung (hNK-2R), expressed in baculovirus-infected Sf-21 insect cells. Functional hNK-2R cDNA clones were isolated from human lung using a polymerase chain reaction-based methodology. hNK-2R was cloned into pAcYM1, a vector designed to couple expression to the polyhedrin promoter, and the recombinant baculovirus was isolated and used to infect Sf-21 insect cells. hNK-2R expression levels were monitored by Northern blots and 125-I-NKA binding assays. Isolates demonstrating the highest specific binding of 125-I-NKA were grown and membrane preparations from high-speed centrifugations were prepared from both hNK-2R-expressing and wild-type virus-infected cells. [3H]NKA bound in a protein-dependent, saturable (Bmax = 820 +/- 167 fmol/mg of protein), and highly specific (88 +/- 5%) manner to hNK-2R, but not to membranes from cells infected with wild-type virus (14 +/- 8%, 7 +/- 10 fmol/mg of protein). [3H]NKA binding was rapid (k1 = 0.085 nM-1 x min-1) and reversible (t1/2 = 4-5 min). Equilibrium binding experiments demonstrated binding to a mixture of receptors in high and low affinity states (Kd1 = 2.28 +/- 0.26 nM and Kd2 = 266 +/- 91 nM). Binding to hNK-2R was greatly enhanced (400%-600%) by Ca2+ and Mg2+ (EC50 values of 30 microM and 140 microM, respectively), whereas guanosine-5'-O-(3'-thio)triphosphate and guanosine-5'-(beta, gamma-imido)diphosphate were inhibitory. Competition experiments with agonists also demonstrated binding to high and low affinity states, with the following order of potency: NKA > [Nle10]NKA(4-10) > [beta-Ala8]NKA(4-10) >> substance P; Senktide and the NK-1 antagonist CP96,345 (10 microM) did not inhibit binding. Inhibition of binding by selective NK-2 antagonists was consistent with a single affinity state and demonstrated the following order of affinity: SR48,968 >> MEN10,376 > L659,877 > R396. These data suggest that infection of Sf-21 cells with baculovirus expression vector harboring the cDNA of hNK-2R resulted in expression of high affinity, G protein-coupled hNK-2R, with pharmacological selectivity compatible with the NK-2A receptor subtype.

Animals↗