Green fiber lasers: an alternative to traditional DPSS green lasers for flow cytometry.

Green and yellow diode-pumped solid-state (DPSS) lasers (532 and 561 nm) have become common fixtures on flow cytometers, due to their efficient excitation of phycoerythrin (PE) and its tandems, and their ability to excite an expanding array of expressible red fluorescent proteins. Nevertheless, they have some disadvantages. DPSS 532-nm lasers emit very close to the fluorescein bandwidth, necessitating optical modifications to permit detection of fluorescein and GFP. DPSS 561-nm lasers likewise emit very close to the PE detection bandwidth and also cause unwanted excitation of APC and its tandems, requiring high levels of crossbeam compensation to reduce spectral overlap into the PE tandems. In this article, we report the development of a new generation of green fiber lasers that can be engineered to emit in the range between 532 and 561 nm. A 550-nm green fiber laser was integrated into both a BD LSR II cuvette and FACSVantage DiVa jet-in-air cell sorter. This laser wavelength avoided both the fluorescein and PE bandwidths and provided better excitation of PE and the red fluorescent proteins DsRed and dTomato than a power-matched 532 nm source. Excitation at 550 nm also caused less incidental excitation of APC and its tandems, reducing the need for crossbeam compensation. Excitation in the 550 nm range, therefore, proved to be a good compromise between 532- and 561-nm sources. Fiber laser technology is, therefore, providing the flexibility necessary for precisely matching laser wavelengths to our flow cytometry applications.

Practice-based randomized controlled-comparison clinical trial of chiropractic adjustments and brief massage treatment at sites of subluxation in subjects with essential hypertension: pilot study.

OBJECTIVE: To determine the feasibility of conducting a randomized clinical trial in the private practice setting examining short- and long-term effects of chiropractic adjustments for subjects with essential hypertension compared with a brief soft tissue massage, as well as a nontreatment control group. DESIGN: Randomized controlled-comparison trial with 3 parallel groups. SETTING: Private practice outpatient chiropractic clinic. PATIENTS: Twenty-three subjects, aged 24 to 50 years with systolic or diastolic essential hypertension. INTERVENTIONS: Two months of full-spine chiropractic care (ie, Gonstead) consisting primarily of specific-contact, short-lever-arm adjustments delivered at motion segments exhibiting signs of subluxation. The massage group had a brief effleurage procedure delivered at localized regions of the spine believed to be exhibiting signs of subluxation. The nontreatment control group rested alone for a period of approximately 5 minutes in an adjustment room. MAIN OUTCOME MEASURES: Cost per enrolled subject, as well as systolic and diastolic blood pressure (BP) measured with a random-0 sphygmomanometer and patient reported health status (SF-36). Pilot study outcome measures also included an assessment of cooperation of subjects to randomization procedures and drop-out rates, recruitment effectiveness, analysis of temporal stability of BPs at the beginning of care, and the effects of inclusion/exclusion criteria on the subject pool. RESULTS: Thirty subjects enrolled, yielding a cost of $161 per enrolled subject. One subject was later determined to be ineligible, and 6 others dropped out. In both the chiropractic and massage therapy groups, all subjects were classified as either overweight or obese; in the control group there were only 2 classified as such. SF-36 profiles for the groups were similar to that of a normal population. The mean change in diastolic BP was -4 (95% confidence interval [CI]: -8.6, 0.5) in the chiropractic care group, 0.5 (95% CI: -3.5, 4.5) in the brief massage treatment group, and -4.9 (95% CI: -9.7, -0.1) in the no treatment control group. At the end of the study period, this change was -6.3 (95% CI: 13.1, 0.4), -1.0 (95% CI: -7.5, 15.6), -7.2 (95% CI: -13.3, -1.1) in the 3 study groups. The mean improvements in the chiropractic care and no treatment control groups remained consistent over the follow-up period. CONCLUSIONS: This pilot study elucidated several procedural issues that should be addressed before undertaking a full-scale clinical trial on the effects of chiropractic adjustments in patients with essential hypertension. A multidisciplinary approach to recruitment may need to be used in any future efforts because of the limited subject pool of patients who have hypertensive disease but are not taking medications for its control. Measures need to be used to assure comparable groups regarding prognostic variables such as weight. Studies such as these demonstrate the feasibility of conducting a full-scale 3-group randomized clinical trial in the private practice setting.