A novel Raman spectrophotometric method for quantitative measurement of nucleoside triphosphate hydrolysis.

A novel spectrophotometric method, based upon Raman spectroscopy, has been developed for accurate quantitative determination of nucleoside triphosphate phosphohydrolase (NTPase) activity. The method relies upon simultaneous measurement in real time of the intensities of Raman marker bands diagnostic of the triphosphate (1115 cm(-1)) and diphosphate (1085 cm(-1)) moieties of the NTPase substrate and product, respectively. The reliability of the method is demonstrated for the NTPase-active RNA-packaging enzyme (protein P4) of bacteriophage phi6, for which comparative NTPase activities have been estimated independently by radiolabeling assays. The Raman-determined rate for adenosine triphosphate substrate (8.6 +/- 1.3 micromol x mg(-1) x min(-1) at 40 degrees C) is in good agreement with previous estimates. The versatility of the Raman method is demonstrated by its applicability to a variety of nucleotide substrates of P4, including the natural ribonucleoside triphosphates (ATP, GTP) and dideoxynucleoside triphosphates (ddATP, ddGTP). Advantages of the present protocol include conservative sample requirements (approximately 10(-6) g enzyme/protocol) and relative ease of data collection and analysis. The latter conveniences are particularly advantageous for the measurement of activation energies of phosphohydrolase activity.

Horizontal transposition of the vertical rectus muscles for cyclotropia.

PURPOSE: We studied the effect of horizontal transposition of the vertical rectus muscles on incyclotropia and excyclotropia in terms of the amount of correction obtained and the stability of the outcome. METHOD: Preoperative measurements for cyclotropia were compared in 11 patients with measurements during the immediate postoperative period and last follow-up. Excyclotropia was treated with nasal transposition of the inferior rectus muscle and incyclotropia with nasal transposition of the superior rectus muscle, to which we added temporal transposition to the inferior rectus muscle in one patient to enhance the effect. RESULTS: Fusion in all gaze positions was restored in six patients and functional improvement occurred in five. The average effect of horizontal transposition of one vertical rectus muscle for cyclotropia was a correction of 7 degrees in primary position and of 11 degrees in depression. This effect remained stable after a mean follow-up of 17 months, and additional improvement occurred in one patient. One patient developed a hypertropia, eliminated by an additional operation, in the treated eye. CONCLUSIONS: For excyclotropia, nasal transposition of the inferior rectus muscle is a viable alternative to lateral and anterior transposition of the anterior portion of the superior oblique tendon. It becomes the procedure of choice when surgery on the superior oblique tendon is precluded, either by the tendon's congenital absence or by previous surgery on the tendon. Nasal transposition of the superior rectus muscle or temporal transposition of the inferior rectus muscle is ideally suited for incyclotropia. No comparably effective operation exists.

Horizontal transposition of the vertical rectus muscles for treatment of ocular torticollis.

In most instances, a head tilt to either shoulder is caused by hypertropia or cyclotropia and responds well to conventional surgical strengthening or weakening operations on the cyclovertical muscles. Occasionally, an ocular head tilt occurs in the absence of cyclovertical strabismus, in association with congenital nystagmus or without an apparent cause. We have successfully treated four of five such patients by surgically rotating the eye(s) around the sagittal axis. This was accomplished by horizontal transposition of the vertical rectus muscles. No complications were encountered. We present this method as a viable alternative to other surgical approaches to rotate the eyes around their sagittal axis.