Immune response to a hapten of fluorescein isothiocyanate (FITC) in a single BALB/c strain mouse was analyzed by two-dimensional affinity electrophoresis (2D-AEP). Anti-FITC antibodies were induced by immunization with FITC-conjugated bovine serum albumin. The antibodies were separated into a large number of spots of IgG due to differences in their isoelectric points(pI) and binding affinities to the FITC ligand. These spots consisted of IgG families which were composed of several spots having an identical affinity to the ligand but a different pI. The spots were not clearly detected in the antiserum taken on day 7 after the primary immunization, but on day 21 the spots of IgG were clearly detected, with a high diversity and specificity for the ligand. The size and number of IgG spots were markedly increased by the secondary immunization; however, the third immunization did not increase the size and number of IgG spots. The IgG spots of each family were specifically stained with an antimouse IgG subclass antibody. Furthermore, a monoclonal antibody (FL-D6) was separated by 2D-AEP into a single family which consisted of seven IgG1 spots having an identical affinity to FITC but different pIs. Therefore, each of the IgG families of anti-FITC antibodies in the antiserum can be generated by a single clone of anti-FITC antibody-producing cells. The substitution of dextran T2000 or lipopolysaccharide for bovine serum albumin as a carrier for FITC induced much smaller amounts of anti-FITC antibodies with a low diversity but high specificity to FITC.

Animals↗

PubMedDate not supplied

Flow velocity of the cortical vein and its effect on functional brain MRI at 1.5T: preliminary results by cine-MR venography.

The purpose of this study is to demonstrate the effect of altering flow velocity of cerebral cortical veins as the source of the signal change observed in functional magnetic resonance imaging (fMRI) of the brain. 10 healthy volunteers were examined after instructions in self-paced hand grasping. Experiments were performed using a 1.5-Tesla whole body MR scanner with a conventional two-dimensional gradient echo sequence (TR/TE/flip angle 400/60/40, first order flow rephased, reduced band width 8 Hz/pixel). Flow velocity measurements were performed for the cortical veins which corresponded to the activated areas depicted on fMRI. Velocity was estimated from the cine-MR venography (cine-MRV) with a tagging technique. Flow phantom studies were performed to delineate the effect of flow velocity differences upon the subtraction images of fMRI. The cine-MRV revealed increased flow velocity of the cortical veins during activation in seven volunteers, with a mean velocity difference of 15 mm/sec. Flow phantom studies suggested that the increased flow velocity may result in changes of the flow signal profile due to oblique flow displacement. Subtraction of the two images with different flow profiles produces flow signal enhancement. Increased flow velocity of the cortical veins during the activation is an important factor which contributes to the signal of fMRI.

Adult↗

PubMedDate not supplied

delta-aminolevulinic acid dehydratase in low level lead exposure.

No statistically significant correlation was observed between log delta-aminolevulinic acid dehydratase (ALAD) activity and blood lead levels (Pb-B) in rural or urban habitants (p greater than .5 and P greater than .1, respectively) in whom no occupational source of lead was known. However, when the values the the two groups were pooled, there was a fairly good negative correlation (r = 0.509, P less than .01). Stepwise correlation coefficient analysis indicated the existance of a threshold value of Pb-B (around 15 mug/100 ml) below which ALAD activity had nor orderly relationship with the Pb-B. In contrast with married couples, parents and their children showed a remarkably high interrelationship in values of ALAD. It is concluded that in low level lead exposure primarily genetic factors influence the activity of ALAD and, thus ALAD is useful for the evaluation of lead exposure only when the lead level is higher than the threshold.

Absorption↗