Biomedical subjects

B Hopkins

Publications and source records attributed to B Hopkins.

At least 37 records · Page 2Linked to original sources

PubMed1998

Repeated low-level formaldehyde exposure produces cross-sensitization to cocaine: possible relevance to chemical sensitivity in humans.

Sensitivity to chemicals in humans has been proposed to be an acquired disorder in which individuals become increasingly sensitive to chemicals in the environment. A possible link between the manifestation of psychiatric symptoms in individuals claiming sensitivity to chemicals was investigated based on a leading hypothesis put forth by Bell and co-workers (1992) to explain the amplification of symptoms after chemical exposure. The hypothesis is that chemical sensitivities may be akin to sensitization observed in rodents after repeated psychostimulants. Repeated exposure to psychostimulants enhances behavioral activity and the underlying neurochemical responses in specific limbic pathways; a similar sensitization of limbic pathways has been proposed to occur in individuals who become sensitive to chemicals. To test this hypothesis, female Sprague-Dawley rats were exposed to either air or formaldehyde (Form) for 1 h/day for 7 days or 20 days (5 days/week x 4 weeks). Two to 4 days after the last exposure, rats were given a cocaine challenge (= early withdrawal) followed by an additional cocaine challenge 4-6 weeks later (= late withdrawal). No differences in cocaine-induced locomotor activity were noted between groups after 7 days of exposure. However, after 20 days of exposure to Form, vertical activity was significantly elevated at both early and late withdrawal times. These studies demonstrate that behavioral sensitization occurs after long-term, but not short-term, low-level exposure to Form, and lends support to the limbic system sensitization hypothesis of sensitivity to chemicals in humans.

Anesthetics, Local↗

PubMed1998

Muscle power and medical history in high risk preterm infants at 3 months of corrected age.

A group of 73 "high risk" preterm infants was studied at the corrected age of 12 weeks. The infants were categorized according to their medical history in 5 classes conform with the "Neonatal Medical Index" (NMI). Only infants with high-risk for developmental discrepancies with a score of NMI > or = III were included in the study. Apart from pediatric follow-up and an age-adequate neurological examination, special emphasis was put on measuring a specific feature in the development of preterm infants: the relationship between active muscle power and passive tone. These two components of muscle power should be in balance with each other to create stable posture and fluent motility and later co-ordination. Discrepancy between active and passive muscle tone was found in all NMI groups studied and was most outspoken in the legs. Infants in NMI IV and V showed a significantly higher incidence of increased passive tone than the infants in NMI III. When the different regions of the body were studied separately, the infants in NMI IV and V showed significantly increased passive tone in the trunk and shoulders (p 0.009) compared to infants in NMI III, which may constitute an alarm signal of deviant development. The main aim of the study was to provide a clinical method for early detection, subtle enough to select infants most at risk for later functional and neurological problems.

Chi-Square Distribution↗

PubMed1998

Adrenal cortical carcinoma associated with a splenic vein tumor thrombus.

A unique case is reported of a left adrenal cortical carcinoma with a splenic vein tumor thrombus. En bloc radical nephroadrenalectomy, distal pancreatectomy, splenectomy and splenic vein tumor thrombectomy were performed. Reconstruction of the proximal portal vein was required, incorporating a segment of the left renal vein (harvested from the surgical specimen) as a free interposition graft, bridging the defect between the superior mesenteric vein and portal vein. To our knowledge, this is the first reported case of an adrenal cortical carcinoma associated with a splenic vein tumor thrombus. In addition, the described technique used to reconstruct the proximal portion of the portal vein has not been previously reported.

Adrenal Cortex Neoplasms↗

PubMed1998

Head position preference in the human newborn: a new look.

Head position preference was studied in 20 awake newborns who differed in terms of delivery and sex. They were placed supine on a custom-built platform to reduce the effects of gravity and asymmetries in trunk posture and skull shape. A global and a specific scoring method were used, the infants being in State 3 (quiet wakefulness) or 4 (active wakefulness, excluding crying). Delivery and sex did not account for differences in head position. The head turned more often to the right and was maintained longer in this position during State 3, regardless of scoring method. The maintenance of the head in midline was comparable in duration to that reported for infants at 2-3 months when using the global scoring method. This suggests that the neural mechanisms responsible for attaining and maintaining a midline position are present at birth, but are not functionally expressed due to a lack of adequate power in the antigravity muscles of the neck.

Brain↗

PubMed1998

A prospective study of spontaneous abortion: relation to amount and source of drinking water consumed in early pregnancy.

In 1992, we published four retrospective studies, conducted primarily within a single California county, which found higher spontaneous abortion rates among women who drank more tapwater than bottled water in early pregnancy. The current prospective study extends that investigation to other water systems. Pregnant women from three regions in California were interviewed during their first trimester. Multivariate analyses modeled the amount and type of water consumed at 8 weeks' gestation in each region in relation to spontaneous abortion rate. In Region I, which was within the previous study area, the adjusted odds ratio (OR) comparing high (> or = 6 glasses per day) consumption of cold tapwater with none was 2.17 [95% confidence interval (CI) = 1.22-3.87]. Furthermore, when women with high cold tapwater and no bottled water consumption were compared with those with high bottled water and no cold tapwater consumption, the adjusted odds ratio was 4.58 (95% CI = 1.97-10.64). Conversely, women with high bottled water consumption and no tapwater had a reduced rate of spontaneous abortion compared with those drinking tapwater and no bottled water (adjusted OR = 0.22; 95% CI = 0.09-0.51). Neither tap nor bottled water consumption altered the risk of spontaneous abortion in Regions II and III. Although controlling for age, prior spontaneous abortion, race, gestational age at interview, and weight somewhat strengthened the association in Region I, the distribution of these confounders did not vary appreciably across regions. This study confirms the association between cold tapwater and spontaneous abortion first seen in this county in 1980. If causal, the agent(s) is not ubiquitous but is likely to have been present in Region I for some time.

Abortion, Spontaneous↗

PubMed1998

Trihalomethanes in drinking water and spontaneous abortion.

Trihalomethanes (chloroform, bromoform, bromodichloromethane, and chlorodibromomethane) are common contaminants of chlorinated drinking water. Although animal data indicate that these compounds may be reproductive toxicants, little information exists on their relation to spontaneous abortion in humans. We examined exposure to trihalomethanes and spontaneous abortion in a prospective study of 5,144 pregnant women in a prepaid health plan. Seventy-eight drinking water utilities provided concurrent trihalomethane sampling data. We calculated total trihalomethane levels by averaging all measurements taken by the subject's utility during her first trimester. We calculated exposures to individual trihalomethanes in an analogous manner. Women who drank > or = 5 glasses per day of cold tapwater containing > or = 75 micrograms per liter total trihalomethanes had an adjusted odds ratio (OR) of 1.8 for spontaneous abortion [95% confidence interval (CI) = 1.1-3.0]. Of the four individual trihalomethanes, only high bromodichloromethane exposure (consumption of > or = 5 glasses per day of cold tapwater containing > or = 18 micrograms per liter bromodichloromethane) was associated with spontaneous abortion both alone (adjusted OR = 2.0; 95% CI = 1.2-3.5) and after adjustment for the other trihalomethanes (adjusted OR = 3.0; 95% CI = 1.4-6.6).

Abortion, Spontaneous↗

PubMed1998

Evidence for a phase transition in the early development of prehension.

A longitudinal study was conducted to examine the hypothesis that the development of prehension during the first 5 months of life is characterized by the presence of a discontinuous phase transition. Ten infants were observed weekly from 8 to 24 weeks of age. Video recordings were made of movements toward an attractive object which were classified according to two behavioral categories: reaching without grasping and reaching with grasping. The time evolution of the relative incidence of these behavioral categories was analyzed statistically. Evidence was found for a sudden jump from a (developmental) state in which reaching without grasping is predominant to a state in which reaching with grasping is predominant. Evidence was also found for bimodality, inaccessibility, and anomalous variance. In combination, these findings support the hypothesis that the investigated behavioral change constitutes a discontinuous phase transition. The behavioral change in question occurred at the moment in developmental time at which the attractor strength of reaching for objects as such relative to that of other behavioral activities appeared to be increased.

Age Factors↗

PubMed1997

Motor asymmetries in preterm infants at 18 weeks corrected age and outcomes at 1 year.

Persisting asymmetries in the motility and posture of preterm infants after term age is a common finding, but their diagnostic and prognostic significance has proved to be difficult to interpret. It has been claimed that if an asymmetry is of central origin, then it should be most prominently detectable in infantile reactions that persist beyond the age when they should have disappeared. We hypothesis that motor asymmetries in preterm infants without a major risk for neurological problems may stem from a high degree of active muscle power in the trunk that continues to be present after 12 weeks corrected age. In order to test this hypothesis, 34 preterm infants with a low risk for neurological complications were compared to a group of 17 fullterm infants at 18 weeks of (corrected) age for the presence or absence of motor asymmetries. None of the full-term infants showed asymmetrical motor behaviour, while within the preterm group a significant number did, in particular those who were small for gestational age. A significant relationship between motor asymmetries and a high degree of muscle power in the trunk at this age was found in the preterm group. Asymmetrical active muscle power at 18 weeks had a good predictive value for asymmetrical locomotor, hand and eye functions at 52 weeks.

Eye Movements↗

PubMed1997

An instrument to measure independent walking: are there differences between preterm and fullterm infants?

In clinical practice walking independently has always been considered a major milestone in development. Nevertheless, little attention has been paid to the quality of movement expressed in the first attempts at walking free. Even when children achieve walking within a normal time range, some of them show features that are deviant. Early walking is difficult to judge, but at the same time may provide a sensitive means for detecting possible developmental impairments. The main aim of this paper is to provide a standardized clinical instrument for the qualitative assessment of early walking in a structured free field situation and to compare preterm and fullterm infants. All subjects were assessed 14 days after being able to walk 5 meters independently. The study group consisted of 52 children, of whom 33 were born prematurely (further distinguished in terms of being small- or appropriate-for-gestational age), and 19 were born fullterm. Judgments of walking performance were made in terms of optimal, near-optimal, near-poor, or poor. After correction for age, the preterm group was still later in the onset of walking, but more importantly, showed a qualitatively different pattern of locomotion. Those who were the youngest and small-for-gestational age were overrepresented in the near-poor and poor categories of walking.

Analysis of Variance↗

PubMed1997

Winnicott and the capacity to believe.

Like Freud's, Winnicott's writing displays an enormous interest in words, in their histories as well as their current usage. The author discusses his use of two words, 'capacity' and 'belief' combined in the phrase 'capacity to believe'. What Winnicott has to say about this capacity sheds light on the nature of both religious and cultural experience generally. The paper's argument has two strands that are woven together throughout. The first is Winnicott's concern for words and how a knowledge of their roots can enrich their current meaning. The second is his concern for the nature of belief, the 'capacity to believe', and his conviction that in exploring this capacity psychoanalysis might have something to teach religion. These concerns are interrelated in a number of ways in Winnicott's writing and are ultimately connected with his notion of a 'cultural field', a place to grow, where 'inventiveness', even verbal inventiveness, is 'just one more example ... of the interplay between separateness and union', that is the separateness of individual language users but also their union through the language they share.

Bipolar Disorder↗

PubMed1996

The organization of leg movements in preterm and full-term infants after term age.

In a sample of 13 full-term and 10 preterm infants, the development of kicking movements was studied at 6, 12, and 18 weeks (corrected) age. In healthy full-term infants some characteristics are strikingly stable, such as the duration of the flexion and extension phase and the within-joint organization. These parameters did not differ in preterm compared to full-term infants. For other features, however, developmental changes and differences were observed. Full-term infants tended to decrease their kick frequencies slightly with age. In preterm infants much higher initial kick rates were found, followed by a steep decrease, which resulted in kick frequencies comparable to the full-term levels after the (corrected) age of 12 weeks. There is a tight coupling between the movements in the different joints of the leg in full-term newborns. Preterm infants, in contrast, initially show much lower cross-correlations between hip and ankle and between knee and ankle. This is particularly the case for those preterm infants who were born before 32 weeks gestation. Again, the differences resolved after the age of 12 weeks, which might be related to a transformation in neural functions reported previously around this age. The initial differences in the characteristics of kicking appeared to be more readily explainable by differences in neurological condition than by contrasts in leg volume or postural control.

Birth Weight↗

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↗