Blastogenic transformation of peripheral lymphocytes with phytohemagglutinin (PHA), conconavalin A (Con A), and pokeweed mitogen (PWM) was studied in 29 patients with rheumatoid arthritis (RA). The PHA response was depressed in a subgroup of RA patients with erosive disease. The Con A response was also depressed and paralleled the PHA response. The PWM response was not depressed. These results lend support to the hypothesis of a functional defect of cellular immunity in RA. It was shown that lymphocyte responsiveness to a single mitogen concentration is not an adequate assessment of the overall responsiveness of the lymphocytes tested.

Adult↗

PubMedDate not supplied

Orthodontic analysis and treatment planning: a suite of programs for performing centroid cephalometrics.

The lateral skull radiograph is essential in the diagnosis of facial dysharmony and the planning and evaluation of corrective orthodontic treatment. The classical cephalometric analysis of the lateral radiograph involves the construction of lines and planes based on anatomical landmarks to form a reference system. A new approach to cephalometric measurement based on centres of area (i.e. centroids) has recently been developed. A suite of programs is described here for performing various types of centroid analysis ranging from a simple analysis of facial and cranial segments to template matching of cyclical curves. Sample runs are presented. Many of the programs are data-driven which means that they can be readily adapted to new situations. The system is currently being re-written to run in a more standardized environment.

Cephalometry↗

PubMedDate not supplied

Simulated workplace protection factor study of powered air-purifying and supplied air respirators.

A study protocol was developed to obtain simulated workplace protection factor (SWPF) data for eleven models of powered air-purifying respirators (PAPRs) and supplied-air respirators (SAR) with hoods and helmets. Respirators were tested in a chamber that allowed the simulation of 12 exercises, including 2 exercises of interest to the pharmaceutical industry. Each respirator was tested by 12 volunteers, and a total of 144 sets of test results were obtained for each device. The testing protocol allowed SWPFs up to 250,000 to be measured (limit of quantification). Median SWPFs for all respirators, except one SAR, were at or above this reporting limit. Lower fifth percentiles were above 100,000, except for one SAR previously noted. An assigned protection factor (APF) was estimated for each respirator by dividing the lower fifth percentile by a safety factor of 25. APFs ranged from 6000-10,000 for PAPRs (including one loose-fitting PAPR) and 3400-10,000 for SARs, with one exception. This SAR had a lower fifth percentile of less than 20 and an estimated APF of 1. Results indicated that most respirators tested could provide a high degree of protection for workers, although one National Institute for Occupational Safety and Health-approved SAR provided minimal, if any, protection. Direct testing in a simulated workplace seems the only method that will assure employers of choosing an adequate SAR. This may be true for other classes of respirators. Furthermore, the historical approach of establishing APFs for classes of respirators, rather than individual models, may not provide adequate protection to the wearer. This is also a serious problem for regulatory agencies seeking to promulgate respirator standard provisions such as APFs for classes of respirators.

Adult↗