Objective-To determine whether the cerebral cortex contributes to modifying upcoming postural responses to external perturbations when provided with prior warning of the perturbation.Methods-Electroencephalographic (EEG) potentials were recorded from 12 healthy human subjects (21-32 years of age) before perturbing their balance with backward translations of a platform under their feet. The subjects responded with and without a visual cue that warned them 2 seconds before the perturbation (the Cue and No Cue conditions, respectively).Results-Contingent negative variation (CNV) was evident before perturbation onset in only the Cue condition. In the Cue condition, the subjects also produced smaller center of pressure (CoP) displacements than in the No Cue condition. The cue-related difference in the subjects' CNV potentials correlated with the cue-related difference in their CoP displacements. No significant associations existed among the CNV potentials and any cue-related postural adjustments made before the perturbation.Conclusions-Cortical activity before an externally triggered perturbation associates with modifications of the ensuing postural response.Significance-This is the first study to demonstrate a cortical correlate for changes in central postural set that modify externally triggered postural responses based on anticipation.
We developed a mouse monoclonal antibody (ASPM-29, mAb) against spermine (Spm) conjugated to human serum albumin (HSA) using glutaraldehyde-sodium borohydride, for applications in immunocytochemistry (ICC). The antibody specificity was evaluated by an enzyme-linked immunosorbent assay (ELISA) binding test, simulating the ICC of tissue sections. ASPM-29 showed an almost equal immunoreactivity to Spm and spermidine (Spd) but no reactivity to any of the other polyamine (PA)-related compounds tested. By use of this antibody, indirect immunoperoxidase staining was observed in different tissues fixed with glutaraldehyde in combination with borohydride reduction. In contrast, immunoreactivity was quite low in tissues fixed only with glutaraldehyde. Absorption controls indicated that the immunostaining could be completely inhibited by 50 micrograms/ml of Spm or Spd and partially inhibited by N-acetylspermine (Ac-Spm), N1-acetylspermidine (N1-Ac-Spd), or N8-acetylspermidine (N8-Ac-Spd), but was hardly inhibited at all by other PA-related compounds or amino acids. The reactivity of the antibody with Spm conjugated on wells in an ELISA plate was inhibited by micromolar concentrations of Spm, Spd, Ac-Spm, N1-Ac-Spd, or N8-Ac-Spd, in decreasing order, but not by other small molecules. Dense ICC staining was observed in the paranuclear and basal cytoplasm of acinar cells of rat pancreas, submandibular gland and paratid gland, these results being in complete agreement with our recent ICC methods using other mAbs produced against N-(gamma-male-imidobutyryloxy) succinimide-conjugated Spm.
Two monoclonal antibodies (ADM-1-11 and 79-31 mAbs) were raised against daunomycin (DM) conjugated to bovine serum albumin via the cross-linker N-(gamma-maleimidobutyryloxy)succinimide. The monoclonal antibodies (mAbs) specifically detected DM as well as its analogs doxorubicin and epirubicin, but did not react with other anticancer antibiotics, including pepleomycin, mitomycin C, and actinomycin D. The mAbs reacted strongly with glutaraldehyde-conjugated DM in an enzyme linked immunosorbent assay (ELISA) used as a model system for immunocytochemistry as well as in appropriately pretreated sections of tissues from animals injected with DM. No staining occurred in tissues from uninjected animals. In order to perform DM ICC a number of tissue treatment conditions critical to the detection of low molecular weight substances were employed. Uptake of DM was studied in rats after a single i.v. or i.p. administration of the drug. In the heart, accumulation of DM occurred in nuclei and in the cytoplasm. In the kidney, DM immunoreactivity accumulated in all segments of the nephron except for the proximal tubules. Since the proximal tubules are known to be where a variety of transport systems including P-glycoprotein (Pgp) and organic anion-transporting polypeptides (OATPs) in drug interactions occur, the absence of DM accumulation in these segments may reflect a transport phenomenon depending upon such transporters. The availability of methods to study sites of accumulation of DM offers possibilities for understanding toxic side effects of this drug on the heart and kidney. Moreover, the immunocytochemical methodology developed may prove useful for the localization of other low molecular weight drugs that can be fixed in situ by glutaraldehyde.
bWe prepared monoclonal antibodies against N-(␥-maleimidobutyryloxy)succinimide-conjugated vancomycin (VM). The monoclonal antibody was specific for conjugated or free VM. The monoclonal antibody enabled us to develop an immunocytochemical method for detecting the uptake of VM in the rat kidney and liver. Three hours after a single intravenous (i.v.) injection of VM at the therapeutic dose, the immunocytochemistry revealed that VM accumulated in large amounts in both the S1 and S2 segments and in much smaller amounts in the S3 segment of the proximal tubules as well as in the distal tubules and collecting ducts. The drug was detected in the cytoplasm, cytoplasmic irregular granules, nuclei, and microvilli of the proximal tubule cells. The distal tubules and collecting ducts contained scattered swollen cells in which both the nuclei and cytoplasm were heavily immunostained. Twenty-four hours after injection, most of the swollen cells returned back to normal size and had somewhat decreased immunostaining. Also, significant amounts of VM remained accumulated for as long as 8 days postadministration. In the liver, similar drug accumulation was observed in the Kupffer cells and the endothelial cells of the hepatic sinusoids but not in the hepatocytes, suggesting that vancomycin cannot be eliminated via the liver. Immunoelectron microscopic studies demonstrated that in the collecting ducts, uptake of VM occurred exclusively in the lysosomes and cytoplasm of the principal cells and scarcely in the intercalated cells. Furthermore, double fluorescence staining using rats simultaneously administered with VM and gentamicin strongly suggests that both drugs colocalized in lysosomes in the proximal tubule cells of kidneys.
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