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Biomedical subjects

G Barnes

Publications and source records attributed to G Barnes.

137 records · Page 8Linked to original sources
PubMedDate not supplied

Extended length heterobifunctional coupling agents for protein conjugations.

A series of extended length heterobifunctional coupling agents is described. The successive aminocaproic acid homologation of succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate, a known 9-atom long maleimide active ester linker, yielded 16-, 23-, and 30-atom long maleimide active ester homologues. The performance study of these coupling agents in automated microparticle enzyme immunoassays showed that, in the alpha fetoprotein assay, in which the linkers were employed in the construction of the alkaline phosphatase-antibody conjugates, the signal increased 64% when the length of the linker was incremented from 9 atoms to 23 atoms and 82% for the 30-atom long linker as compared with the 9-atom homologue. Similar improvements were observed in the performance of carbohydrate antigen, marker of ovarian cancer (CA-125), immunoassay where the linkers were used for conjugation of the capture antibody anti-CA-125 to the microparticle. Thus, a 300% signal improvement resulted when a 30-atom linker was used instead of the 9-atom homologue. The observed differences in the performance of the conjugates are interpreted as resulting from improved antibody binding and lowering of the steric hindrance of the complementarity-determined region of the antibody when longer coupling agents were used.

Alkaline Phosphatase↗
PubMedDate not supplied

Delta-F508 cystic fibrosis mutation is not linked to intussusception: implications for rotavirus vaccine.

OBJECTIVE: To determine whether the cystic fibrosis (CF) delta-F508 gene mutation predisposes to intussusception, and so selects infants who should not receive rotavirus vaccine. METHODS: Stored neonatal screening blood spots, retrieved from 81 infants with intussusception and from 79 controls, were tested for the presence of the CF delta-F508 gene mutation. RESULTS: Prevalence of the mutation was similar in blood specimens from intussusception patients and from controls. CONCLUSION: Testing for the CF delta-F508 mutation at birth is unlikely to identify infants predisposed to intussusception, and therefore is not relevant to rotavirus vaccine programs.

Australia↗
PubMedDate not supplied

A comparison of predictive and nonpredictive ocular pursuit under active and passive stimulation conditions in humans.

A technique has been developed for the comparison of predictive and nonpredictive ocular pursuit in human subjects, with the objective of estimating the contribution made by predictive processes to the normal pursuit response. Subjects were presented with a target moving at constant velocity in the horizontal plane and instructed to actively pursue the target or to passively stare at it. In the predictive mode (PRD), a step-ramp stimulus with velocity ranging from 12.5 to 50 degrees/s was presented at regular intervals of 1.728 s, in alternating directions, with target exposure durations (PD) that varied from 80 to 640 ms. In the interval between presentations, subjects were in complete darkness. In the nonpredictive mode (RND), similar step-ramp stimuli were presented but with randomized direction and timing of target exposure. In the nonpredictive mode, during both active and passive stimulation, the smooth component of eye velocity was initiated after a mean delay of 125 ms. In the predictive mode, eye velocity started to build up well before target onset, even during passive stimulation. It was found that the time of initiation of this anticipatory response was closely associated with the time at which the target would have changed direction even though the target could not be seen at this time. Eye velocity measured 100 ms after target onset was negligible in the nonpredictive mode, whereas in the predictive mode, it progressively increased with target velocity, reaching a maximum of 18 degrees/s when target velocity was 50 degrees/s and PD was greater than 240 ms. Examination of the difference in the eye velocity trajectories for the predictive and nonpredictive modes indicated that the greatest contribution of prediction occurred approximately 150 ms after target onset and its effects were evident in the predictive response for at least 300 ms. This effect was reflected in the reaction time between target onset and the occurrence of peak eye velocity. In the nonpredictive mode, this progressively increased from 250 ms to 400 ms as PD increased from 80 to 640 ms, whereas in the predictive mode peak velocity occurred an average of 50 ms earlier for all values of PD. The results demonstrate the significant contribution that predictive processes make to normal ocular pursuit behavior and the importance of timing control in this process. They also indicate that this process is not dependent on volitional control, but can be seen as an automatized response during passive stimulation.

Adaptation, Ocular↗
PubMedDate not supplied

Rotavirus vaccines.

Encouraging results have been reported from several large trials of tetravalent rhesus rotavirus vaccine, with efficacy of 70-80% against severe disease. A recent Venezuelan study showed similar results to trials in USA and Europe. The vaccine may soon be licensed in USA. It provides the exciting prospect of a strategy to prevent one of the world's major child killers. Other candidate vaccines are under development including human-bovine reassortants, neonatal strains, non-replicating rotaviruses, vector vaccines and other genetically engineered products. Second and third generation rotavirus vaccines are on the horizon. The need for a rotavirus vaccine is well accepted by paediatricians, but public health authorities need to be lobbied. Other issues which need to be addressed include relative importance of non-group A rotaviruses, possible administration with OPV, the influence of breast feeding, and most importantly, cost. It is essential that rotavirus vaccine is somehow made available to all of the world's children, not just those in developed countries.

Child, Preschool↗