Release of soluble transferrin receptor from the surface of human leukemic HL60 cells

Information regarding transferrin (Tf) receptor degradation is largely incomplete. HL60 cells were shown to release to their growth medium a Tf-binding protein which could be immunoprecipitated by anti-Tf receptor monoclonal antibodies (MoAbs) B3/25 and OKT9. Soluble Tf receptor was detected in the medium within one hour of replating of cells, and its release was inhibited at 4 degrees C. The affinity of Tf for the soluble receptor released by cells (kd = 2.3 x 10(-10) mol/L) was slightly lower than its affinity for the detergent-solubilized cellular receptor (kd = 1.2 x 10(-10) mol/L). 125I-Tf internalized and released by cells subsequently bound to Tf receptor released by the same cells, and soluble Tf receptor in the conditioned medium (CM) inhibited 125I-Tf binding to intact cells. The soluble Tf receptor isolated from the CM was smaller (78,000 daltons) than the cell surface receptor (94,000 daltons) when analyzed by gel electrophoresis under reducing conditions. Isolated cell membranes readily released soluble receptor; however, this release could be blocked by protease inhibitors. The soluble Tf receptor may represent the extracytoplasmic domain of the cellular Tf receptor released from the surface of HL60 cells through proteolytic cleavage by a membrane-based protease.     

The ora serrata and the spiral of Tillaux. Anatomic relationship and clinical correlation

Conventional teaching states that the spiral of Tillaux marks the location of the ora serrata. On literature review, no source for this was found. This study explores this anatomic relationship. In 20 cadaver eyes, narrow-gauge needles were placed penetrating the center of each rectus muscle insertion, and distance to the ora was measured. Insertions ranged from 2.25 mm posterior to 2.25 mm anterior to the ora, with 90% within 1 mm of it. In ten eyes, distance from the edge of insertion also was measured. Results indicate that the centers of rectus insertions, especially the lateral rectus, approximately overlie the ora, with the edges of the insertions more posterior and variable.     

Pneumothorax and other lung diseases: effect of altered resolution and edge enhancement on diagnosis with digitized radiographs

Prior studies have shown that pneumothorax is one of the more difficult entities to diagnose with digitized radiography. This study was designed to test whether increasing resolution from 1.25 to 2.5 line pairs per millimeter (lp/mm) and image processing (edge enhancement from unsharp masking) would increase accuracy and confidence in the diagnosis of pneumothorax, as well as normal cases and other forms of lung disease. Conventional radiographs were digitized with use of a laser reader and then reformatted as film hard copy. Eleven observers read 35 cases reformatted in three different ways (1.25 lp/mm, 2.5 lp/mm, 1.25 lp/mm unsharp mask). The images with finer resolution (2.5 lp/mm) and unsharp mask images were superior to those with coarser resolution (1.25 lp/mm) for the diagnosis of pneumothorax. There was no difference in diagnostic accuracy for normal patients. For abnormalities other than pneumothorax, the unsharp mask images were significantly worse. Confidence in the diagnosis of pneumothorax and other abnormalities was highest with the finest resolution (2.5 lp/mm).     

How should vasectomy be promoted in Guatemala?

In the article "Evaluation of a Communications Program to Increase Adoption of Vasectomy in Guatemala" by J.T. Bertrand et al (Stud Fam Plann 1987 Nov/Dec), the authors conclude that the use of a male promoter alone was 4 times more cost-effective in increasing the number of vasectomies than the use of radio alone because the costs of the radio program were 4 times higher. This conclusion is questionable for several reasons. 1) The district where the promoter was used alone was twice as large as the radio-only district. 2) In one of the promoter-only districts the same promoter worked throughout the program, but in the other, 3 different promoters had to be recruited and trained, due to high personnel turnover. 3) The initial costs of a radio program may be higher, but 1 program can be broadcast in all districts with little or no extra cost, whereas the costs of a promoter would have to be multiplied by the number of districts. 4) Although the promoter and the radio program produced approximately equal numbers of vasectomies, the radio messages reached over 70% of the people surveyed. Thus, on a national basis, radio broadcasts would be far more cost-effective than the use of salaried promoters in each district.