Biomedical subjects

G Scott

Publications and source records attributed to G Scott.

At least 307 records · Page 17Linked to original sources

PubMedDate not supplied

[Isolation and characterization of the ALP1 protease from Aspergillus fumigatus and its protein inhibitor from Physarium polycephalum].

It is known that Aspergillus fumigatus secretes a serine protease ALP1 of the subtilisin family in the presence of extracellular protein substrates. We found conditions of A. fumigatus culturing that provide a high ALP1 activity inside cells without induction by extracellular proteins. The identity of the properties of the secreted and intracellular enzymes was shown. A thermostable protein inhibitor of the ALP1 protease was isolated from the plasmodium of the myxomycete Physarum polycephalum. Its molecular mass is 32-33 kDa. The inhibitor inhibits the ALP1 protease activity with IC50 of 0.14 microM. This protein was also shown to be a less efficient inhibitor of the activity of HIV-1 protease (IC50 2.5 microM). The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

Animals↗

PubMedDate not supplied

In vivo detection of applied electric currents by magnetic resonance imaging.

Magnetic resonance imaging is very sensitive to magnetic field variations. This inherent sensitivity can be exploited to measure small electric currents flowing in the human body. This report describes an experiment in which the magnetic fields produced by small currents applied to the forearm of a living subject have been detected in the tissue. It shows how such measurements have been used to measure current density. The suggested technique is used to measure one component of a current density in a saline solution in vitro.

Electric Conductivity↗

PubMedDate not supplied

Elimination of action potentials blocks the structural development of retinogeniculate synapses.

Although the influence of electrical activity on neural development has been studied extensively, experiments have only recently focused on the role of activity in the development of the mammalian central nervous system (CNS). Using tetrodotoxin (TTX) to abolish sodium-mediated action potentials, studies on the visual system show that impulse activity is essential both for the normal development of neuronal size and responsivity in the lateral geniculate nucleus (LGN), and for the eye-specific segregation of geniculo-cortical axons. There have been no anatomical studies to investigate the influence of action potentials on CNS synaptic development. We report here the first direct evidence that elimination of action potentials in the mammalian CNS blocks the growth of developing axon terminals and the formation of normal adult synaptic patterns. Our results show that when TTX is used to eliminate retinal ganglion-cell action potentials in the cat from birth to 8 weeks, the connections made by ganglion cell axons with LGN neurones, retinogeniculate synapses, remain almost identical morphologically to those in the newborn kitten.

Action Potentials↗

PubMedDate not supplied

Brief report: relationship between HIV infection and WPPSI-R performance in preschool-age children.

OBJECTIVE: To determine the neurodevelopmental effects of perinatally acquired HIV infection on children of preschool age. METHODS: Participants included 40 children infected with HIV between the ages of three and five and an equal number of noninfected controls individually matched according to ethnicity, age, sex, and prenatal drug exposure. Participants were administered the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), upon which an analysis of subtest distribution was conducted. RESULTS: Whereas both groups evidenced mean IQ and subtest scores significantly below published norms, an effect for HIV group status was not found when a factor combining Performance IQ (PIQ) and Verbal IQ (VIQ) was analyzed. However, the group infected with HIV scored significantly lower than controls on the Block Design subtest. CONCLUSIONS: Gross cognitive deficits are not evident among preschool children infected with HIV relative to matched controls. However, this study does provides some evidence for more focal deficits. Further investigation with older children should be conducted.

Case-Control Studies↗

PubMedDate not supplied

Night waking in 1-year-old children in England.

A national sample of 1500 mothers of 1-year-old children received a postal questionnaire concerned with the sleeping patterns of their children. The response rate was 69%. Seventeen per cent of mothers reported that their 1-year-old presented a moderate or severe sleep problem and 26% said their child woke at night on at least five nights a week. While these two measures correlated, 10% of those who reported their infant woke on at least five nights a week did not consider this to be a problem. Neither sex of infant, social class, method of infant feeding or numbers of house moves were associated with sleep problems. The pattern of results strongly suggest an association between night waking and other sleeping difficulties and stress for mothers. This was indicated by the association we found with complaints about housing, overcrowding, more negative attitudes toward motherhood, lower assessments of maternal well-being, lack of practical support from partners, the use of more negative adjectives to describe their baby and more frequent feelings of being dominated by their baby. While these associations may be explained by the stresses of living with a night-waking baby, it is also likely that a mother who is feeling somewhat depressed and negative toward her baby is more likely to see night waking as significant and as a problem. There were class differences in how parents coped with a shortage of space. Middle-class parents were more likely to put a baby in with a sibling while working class parents more often had the baby in their own room. Middle-class parents were more likely to leave a night-waking baby to cry.

England↗

PubMedDate not supplied

The contusion index: a quantitative approach to cerebral contusions in head injury.

A quantitative means of assessing contusions of the brain (the 'contusion index') following head injury has been devised. Its derivation and application to a consecutive series of 151 cases are described.

Brain Concussion↗

PubMedDate not supplied

Does cerebral vasospasm result from denervation supersensitivity?

This study examined the role of denervation supersensitivity in the development of cerebral vasospasm. Adrenergic denervation of cat basilar artery was accomplished by resection of the superior cervical ganglia or by injection of 6-hydroxydopamine into the cisterna magna. In vivo dose-response characteristics were determined for normal and for denervated arteries, and no significant differences were found between topical applications of serotonin, norepinephrine, epinephrine, fresh blood, or incubated blood. In addition, analysis of cat blood incubated in vitro revealed that the levels of serotonin, norepinephrine, and epinephrine diminished over time, whereas levels of hemoglobin and methemoglobin increased up to Day 14. The results of this study indicate that adrenergic denervation is not the cause of cerebral vasospasm and that, whatever the mechanism, hemoglobin is far more likely to play a role than are the other agents.

Animals↗

PubMedDate not supplied