Cell-cell interactions are important in embryogenesis, in adult physiology and pathophysiology of many disease processes. Co-cultivation of parenchymal and mesenchymal cells has been widely utilized as a paradigm for the study of cell-cell interactions in vitro. In addition, co-cultures of two cell types provide highly functional tissue constructs for use in therapeutic or investigational applications. The inherent complexity of such co-cultures creates difficulty in characterization of cell-cell interactions and their effects on function. In the present study, we utilize conventional "randomly distributed" co-cultures of primary rat hepatocytes and murine 3T3-J2 fibroblasts to investigate the role of increasing fibroblast density on hepatic function. In addition, we utilize microfabrication techniques to localize both cell populations in patterned configurations on rigid substrates. This technique allowed the isolation of fibroblast number as an independent variable in hepatic function. Notably, homotypic hepatocyte interactions were held constant by utilization of similar hepatocyte patterns in all conditions, and the heterotypic interface (region of contact between cell populations) was also held constant. Co-cultures were probed for synthetic and metabolic markers of liver-specific function. The data suggest that fibroblast number plays a role in modulation of hepatocellular response through homotypic fibroblast interactions. The response to changes in fibroblast number are distinct from those attributed to increased contact between hepatocytes and fibroblasts. This approach will allow further elucidation of the complex interplay between two cell types as they form a functional model tissue in vitro or as they interact in vivo to form a functional organ.

3T3 Cells↗

PubMedDate not supplied

A comparison of nasal resistance in white Caucasians and blacks.

Total nasal resistance was measured in 42 white caucasian and 32 black healthy adults by both anterior and posterior rhinomanometry after using a nasal decongestant. The nasal airway resistance was found to be lower in the blacks compared to the caucasians by both anterior and posterior methods. The mean total nasal airway resistance was 0.136 Pa/ cm3/s in the blacks and 0.179 Pa/cm3/s in the caucasians by the anterior method, and 0.134 Pa/cm3/s and 0.161 Pa/cm3/s, respectively, by the posterior method. These differences were highly statistically significant.

Adolescent↗

PubMedDate not supplied

Evaluation of a CCD-based facial measurement system.

This paper describes the configuration and evaluation of a CCD-based biostereometric system at the Department of Orthodontics, Kings College Dental Hospital, London. The system has been designed to allow rapid and accurate measurement of facial soft-tissue shape with a minimum of traditional photogrammetric training. This has been achieved by automatic camera calibration and stereo matching, performed on a Sun Microsystem 3/160 workstation. In summary, the characteristics of the system are: (a) non-contract three-dimensional (3D) measurement of soft-tissue; (b) de-skilled, requiring little or no photogrammetric training; (c) rapid data acquisition, combined with slower off-line processing; (d) processing of resulting 3D surface information to yield cross-sections; (e) surface measurement accurate to within 0.5 mm. Accuracy assessment was performed using a manual electromechanical non-contact measurement device with precision exceeding the requirement of the biostereometric system.

Anthropometry↗

PubMedDate not supplied

A longitudinal study of the SN-mandibular-, Frankfurt-mandibular-, and maxillary-mandibular-plane angles.

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Cephalometry↗