Comparative tonometric measurements of eye bank eyes.

A comparison was made of the accuracy of the Tono-Pen, Pneumatonometer, and Perkins hand-held tonometers by measuring the hydrostatically controlled intracular pressure from 10 to 50 mm Hg in human eye bank eyes. The open stopcock method was used in which the cannulated eye, the hydrostatic pressure controlling column, and a manometer were continuously open to each other. The Pneumatonometer gave accurate results at 50 mm Hg but overestimated the lower intraocular pressures; whereas, the Perkins gave satifactory results at 10 and 20 mm Hg but underestimated higher intraocular pressures. The Tono-Pen displayed the least deviation from the controlled pressure over the entire range studied. Another aspect of this study involved determining that a therapeutic soft contact lens did not have any noticeably adverse effect on the accuracy of the Pneumatonometer and Tono-Pen tonometers.

Extraspinal abnormalities identified on lumbar spine CT.

Retrospective review of 1517 lumbar CT examinations revealed extraspinal pathology in 22 (1.45%). Retroperitoneal tumors and lymphadenopathy as well as vascular, urinary tract and gynecologic abnormalities were identified. This study demonstrates the need to carefully evaluate the visualized portions of the abdomen and pelvis on all lumbar spine CT examinations even when the patient's symptomatology is suggestive of spinal abnormalities.

Endobronchial lipoma demonstrated by CT.

Endobronchial lipomas are rare, benign neoplasms that are not often diagnosed prior to surgical or bronchoscopic resection. Computed tomography can provide a powerful adjunct to conventional modalities in determining the nature of an endobronchial lesion and may prevent unnecessary surgery.

Natural killer cells in systemic lupus erythematosus. Abnormal numbers and functional immaturity of HNK-1+ cells.

A monoclonal antibody, HNK-1, that detects a differentiation antigen on human granular lymphocytes with natural killer (NK) activity was used to enumerate this subpopulation in the peripheral blood of 14 patients with systemic lupus erythematosus (SLE). Nine patients had severely decreased numbers of HNK-1+ cells, 3 patients had elevated levels of HNK-1+ cells, and 2 patients had appropriate numbers of HNK-1+ cells compared with the levels in 112 normal controls. All SLE patients exhibited low NK killing ability against K562 target cells compared with controls. An increased proportion of the HNK-1+ cells was categorized as immature granular lymphocytes in over 50% of the SLE patients because their HNK-1+ cells coexpressed the OKT3 antigen and contained a paucity of cytoplasmic granules. The numbers of HNK-1+ cells or the HNK-1+ OKT3+ subgroup did not correlate with steroid therapy. This evidence suggests that levels of HNK-1+ lymphocytes are abnormal and functionally immature in most SLE patients. Longitudinal studies conducted over several months on a number of SLE patients demonstrated fluctuations in the ratio of mature and immature HNK-1+ cells and total HNK-1+ cells. Additional patients tested over longer periods of time will have to be studied to determine whether the proportion of mature NK cells (HNK-1+ OKT-) and immature NK cells (HNK-1+ OKT3+) will be useful in predicting the clinical course of disease.

Inhibition of ribonuclease. Efficacy of sodium dodecyl sulfate, diethyl pyrocarbonate, protein ase K and heparin using a sensitive ribonuclease assay.

The effectiveness of several commonly used inhibitors of ribonuclease (RNAase) has been studied using the removal of radio-labelled leucine from leucyl-tRNA as a sensitive assay for RNAase activity. The inhibitors were tested under a variety of conditions, varying the temperature, the pH, and the source of RNAase. When each inhibitor is udes separately in the presence of pancreatic RNAase, sodium dodecyl sulfate (SDS) is the most effective; but during long exposures to temperatures above 0 degrees C considerable amounts of RNA are still degraded. Combination of inhibitors are more effective in preserving RNA; with this assay, a combination of SDS with diethyl pyrocarbonate is the most effective. Proteinase K acts as an inhibitor when used in combination with SDS; however, it has RNAase activity when used by itself. Diethyl pyrocarbonate, when used at the high range of concentrations employed by others for RNAase inhibition, reacts with RNA changing its charge. However, when diethyl pyrocarbonate is used in smaller amounts the effects on RNA are minimal, and when used in combination with SDS it effectively inhibits RNAase.

Genetic mapping of regA mutants of bacteriophage T4D.

SP62, a mutant of bacteriophage T4 shown by Wiberg et al. (1973) to be defective in regulation of T4 protein synthesis, was shown by complementation tests to define a new gene, regA, and by intergenic mapping to lie between genes 43 and 62. The mapping involved crossing SP62 with a quadruple amber mutant defective in genes 42, 43, 62, and 44, selecting all six classes of amber-containing recombinants caused by single crossover events, and then scoring the presence or absence of SP62 in these recombinants. In addition, 15 new, spontaneous regA mutants were isolated, and 13 of these were mapped against each other; a total of eight different mutation sites were thus defined. Most of the new mutants were isolated as pseudorevertants of a leaky amber mutant in gene 62, according to Karam and Bowles (1974), whereas one was identified by virtue of the "white ring" around its plaque, a phenotype possessed by all the regA mutants at high temperature, SP62 was renamed regA1, and the new mutants were named regA2, regA3, etc.