Biomedical subjects

K S Mix

Publications and source records attributed to K S Mix.

6 recordsLinked to original sources

PubMed2001

A synthetic triterpenoid selectively inhibits the induction of matrix metalloproteinases 1 and 13 by inflammatory cytokines.

OBJECTIVE: To address the effects of a novel synthetic triterpenoid, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), on the induction of matrix metalloproteinases 1 and 13 (MMP-1, MMP-13) by inflammatory cytokines. METHODS: Human chondrosarcoma cells stimulated with inflammatory cytokines (interleukin-1beta [IL-1beta], tumor necrosis factor alpha) were used to study the effects of CDDO on the induction of MMPs and the invasion of cells through a collagen matrix. RESULTS: CDDO selectively reduced the induction of MMP-1 and MMP-13 at the levels of messenger RNA and protein. Treatment with CDDO prior to cytokine stimulation enhanced this inhibition, and we demonstrated that CDDO functions at the level of transcription. Additionally, CDDO reduced IL-1beta-mediated invasion of cells through a collagen matrix. CONCLUSION: This study demonstrates that CDDO is a novel inhibitor of MMP-1 and MMP-13 gene expression mediated by inflammatory cytokines. Thus, CDDO may have therapeutic potential for the inhibition of joint degradation in osteoarthritis.

Bone Neoplasms↗

PubMed1999

Preschoolers' recognition of numerical equivalence: sequential sets.

The present study was designed to investigate whether 3- to 5-year-olds can recognize numerical equivalence for comparisons involving sequentially presented sets. The relation between accurate numerical-equivalence judgments and acquisition of the conventional counting system also was explored. The results indicate that children recognize numerical equivalence for static sets earlier than for sequential sets. Furthermore, memory for the number of sequentially presented objects emerges earlier than memory for the number of sequential events. Finally, conventional counting ability is linked to success on comparisons involving sequential sets but not on those involving static sets. The implications of these findings for models of nonverbal quantification are discussed.

Child Development↗

PubMed1999

Early fraction calculation ability.

Three- to 7-year-olds' ability to calculate with whole-number, fraction, and mixed-number amounts was tested using a nonverbal task in which an amount was displayed and then hidden (J. Huttenlocher, N. C. Jordan, & S. C. Levine, 1994). Next, an amount was added to or subtracted from the hidden amount. The child's task was to determine the hidden amount that resulted from the transformation. Although fraction problems were more difficult than whole-number problems, competence on all problem types emerged in the early childhood period. Furthermore, there were striking parallels between the development of whole-number and fraction calculation. This is inconsistent with the hypothesis that early representations of quantity promote learning about whole numbers but interfere with learning about fractions (e.g., R. Gelman, 1991; K. Wynn, 1995, 1997).

Age Factors↗

PubMed1997

Numerical abstraction in infants: another look.

This article examines an important finding from the literature on infant numerical competence. The finding, reported by P. Starkey, E. S. Spelke, and R. Gelman (1990), was that infants looked longer toward a visual display that was equal in number to an auditory set. In Experiment 1, when the procedures described by P. Starkey et al. were followed and duration was held constant across auditory sequences that varied in number, infants looked longer toward the display that was not numerically equivalent to the auditory set. In Experiment 2, when the rate and duration of the auditory sequences were varied randomly within infants, no significant preference for either the equivalent or nonequivalent visual display was shown. These results raise questions about P. Starkey et al.'s claims that infants can represent the numerosity of sets in different modalities and then perform one-one correspondence computations over them.

Attention↗

PubMed1996

Do preschool children recognize auditory-visual numerical correspondences?

The present study investigated the ability of 3- and 4-year-old children to perform tasks which require matching sets of sounds to numerically equivalent visual displays. We found that 3-year-olds performed at chance on the auditory-visual matching task, while 4-year-olds performed significantly above chance. There is evidence that mastery of the linguistic counting system is related to success on this task. These findings are unexpected given previous research reporting that 6-8-month-olds can detect the numerical equivalence between a set of sounds and items in a visual display.

Age Factors↗

PubMed1995

The effects of MK801 on place conditioning.

The appetitive properties of MK801 were investigated using the conditioned place preference paradigm. Male Sprague-Dawley rats received conditioned place preference training for a four-day period. The conditioning box consisted of three chambers with distinctive visual and tactile cues, separated by removable doors. On alternating days rats received MK801 (0.05, 0.1, 0.25, 0.5 and 0.75 mg/kg) paired with one side of the chamber and saline paired with the other side. On the fifth day, rats were placed in the center chamber and the time spent in each chamber, as well as entries into each chamber were recorded by a trained observer. MK801 produced a conditioned place preference for side paired with drug for the four highest doses. Contrary to previous findings, these results indicate that MK801 is appetitive at doses higher than has previously been assumed.

Animals↗