Acousto-optical deflection-based laser beam scanning for fluorescence detection on multichannel electrophoretic microchips

Laser beam scanning driven by an acousto-optical deflector (AOD) is presented for multimicrochannel laser-induced fluorescence (LIF) detection during microchip-based electrophoresis. While fast laser beam scanning for LIF detection on capillary or microchannel arrays can been achieved with galvanometric scanning or a translating stage, it can also be accomplished by using acoustic waves to deflect the laser beam in a manner that is dependent on the acoustic frequency. AOD scanning differs from other approaches in that no moving parts are required, and the scan frequency is faster than conventional approaches. Using a digital/analog (D/A) converter to provide addressing voltages to a voltage/frequency converter, rapidly changing the frequency input to the AOD allows the laser beam to be addressed accurately on a microchip. With the ability to change the frequency on the nanosecond time scale, scanning rates as high as 30 Hz for Windows-based LabView programming are possible, with much faster scan rates achievable if a microprocessor-embedded system is utilized. In addition to spatial control, temporal control is easily attainable via raster scanning or random addressing, allowing for the scanning process to be self-aligning. Since the D/A output voltages drive the scanning of the laser beam over all channels, the software can define addressing voltages corresponding to the microchannel centers and, subsequently, fluorescence data can be collected from only those locations. This method allows for flexible, high-speed, self-align scanning for fluorescence detection in capillary or microchip electrophoresis and has the potential to be applied to a number of applications.

Creating a general practice national minimum data set: present possibility or future plan?

AIM

To assess the feasibility of implementing the recommendations of the New Zealand National Minimum Data Set working party in computerised general practices.

METHOD

Doctors from 12 computerised general practices belonging to the Royal New Zealand College of General Practitioners' Dunedin Research Unit Computer Network participated in the study (five Dunedin practices, four in rural Otago and Southland, and three in Christchurch). A three-month sample of data was extracted from practice computers and evaluated for completeness and compliance to the national minimum data set structure. Rates of recording practice identifier, provider, patient identifiers, sex, ethnicity, government subsidy eligibility, consultation identifier and date, prescriptions and Read codes were calculated for each practice.

RESULTS

Apart from data recorded automatically by computers, there was a wide range in the extent of missing data. Of the data requiring manual computer entry, patient demography and subsidy eligibility were most comprehensively recorded (date of birth 99.9%, sex 99.6%, eligibility to subsidies 98.5%). Data with little immediate clinical or management relevance were poorly recorded (Read codes 32.4% and ethnicity 5.0%).

CONCLUSIONS

It is possible to derive a common minimum data set from different computerised general practices. However some data elements will be missing unless suitable education and support are provided for the doctors and other staff members who record patient information.

Neuroendocrine responses to d-fenfluramine and insulin-induced hypoglycemia in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a disorder characterized by severe physical and mental fatigue and fatiguability of central rather than peripheral origin. We hypothesized that CFS is mediated by changes in hypothalamopituitary function and so measured the adrenocorticotrophic hormone (ACTH), cortisol, growth hormone, and prolactin responses to insulin-induced hypoglycemia, and the ACTH, cortisol, and prolactin responses to serotoninergic stimulation with dexfenfluramine in nondepressed CFS patients and normal controls. We have shown attenuated prolactin responses to hypoglycemia in CFS. There was also a greater ACTH response and higher peak ACTH concentrations (36.44 +/- 4.45 versus 25.60 +/- 2.78 pg ml), whereas cortisol responses did not differ, findings that are compatible with impaired adrenal cortical function. This study provided evidence for both pituitary and adrenal cortical impairment in CFS and further studies are merited to both confirm and determine more precisely their neurobiological basis so that rational treatments can be evolved.

Toxicity of the organophosphate chemical warfare agents GA, GB, and VX: implications for public protection

The nerve agents, GA, GB, and VX are organophosphorus esters that form a major portion of the total agent volume contained in the U.S. stockpile of unitary chemical munitions. Congress has mandated the destruction of these agents, which is currently slated for completion in 2004. The acute, chronic, and delayed toxicity of these agents is reviewed in this analysis. The largely negative results from studies of genotoxicity, carcinogenicity, developmental, and reproductive toxicity are also presented. Nerve agents show few or delayed effects. At supralethal doses, GB can cause delayed neuropathy in antidote-protected chickens, but there is no evidence that it causes this syndrome in humans at any dose. Agent VX shows no potential for inducing delayed neuropathy in any species. In view of their lack of genotoxicity, the nerve agents are not likely to be carcinogens. The overreaching concern with regard to nerve agent exposure is the extraordinarily high acute toxicity of these substances. Furthermore, acute effects of moderate exposure such as nausea, diarrhea, inability to perform simple mental tasks, and respiratory effects may render the public unable to respond adequately to emergency instructions in the unlikely event of agent release, making early warning and exposure avoidance important. Likewise, exposure or self-contamination of first responders and medical personnel must be avoided. Control limits for exposure via surface contact of drinking water are needed, as are detection methods for low levels in water or foodstuffs.

The stability of binocular fixation during reading in adults and children

The authors recorded the binocular eye-movements of children and adults while they read single words appropriate for their reading ability. Normal data were obtained from nine- to 11-year-old primary-school children and adults, because very little is known about changes in binocular vergence during reading. These normal data were compared with those from poor readers of the same age who had passed or failed the Dunlop Test. On average, normal children made larger vergence errors while they fixated words than did adults. There were no differences between the groups of children, therefore the authors conclude that poor vergence control during reading fixations is not the immediate cause of the non-word error effect found among children who fail the Dunlop Test.

Effect of Pseudomonas aeruginosa rhamnolipids on mucociliary transport and ciliary beating

Pseudomonas aeruginosa rhamnolipid causes ciliostasis and cell membrane damage to rabbit tissue, is a secretagogue in cats, and inhibits epithelial ion transport in sheep tissue. It could therefore perturb mucociliary clearance. We have investigated the effect of rhamnolipid on mucociliary transport in the anesthetized guinea pig and guinea pig and human respiratory epithelium in vitro. Application of rhamnolipid to the guinea pig tracheal mucosa reduced tracheal mucus velocity (TMV) in vivo in a dose-dependent manner: a 10-microgram bolus caused cessation of TMV without recovery; a 5-micrograms bolus reduced TMV over a period of 2 h by 22.6% (P = 0.037); a 2.5-microgram bolus caused no overall changes in TMV. The ultrastructure of guinea pig tracheal epithelium exposed to 10 micrograms of rhamnolipid in vivo was normal. Application of 1,000 micrograms/ml rhamnolipid had no effect on the ciliary beat frequency (CBF) of guinea pig tracheal rings in vitro after 30 min, but 250 micrograms/ml stopped ciliary beating after 3 h. Treatment with 100 micrograms/ml rhamnolipid caused immediate slowing of the CBF (P less than 0.01) of human nasal brushings (n = 7), which was maintained for 4 h. Mono- and dirhamnolipid had equivalent effects. The CBF of human nasal turbinate organ culture was also slowed by 100 micrograms/ml rhamnolipid, but only after 4 h (CBF test, 9.87 +/- 0.41 Hz; control, 11.48 +/- 0.27 Hz; P less than 0.05, n = 6), and there was subsequent recovery by 14 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors in social perception: seating position

Ss made 8-point scale ratings of 5 target individuals photographed while seated at a rectangular table. Occupancy of the head position (rather than side locations) was consistent with higher ratings on all of the following scales: (1) Talkativeness, (2) Persuasiveness, (3) Leadership, (4) Self-confidence, (5) Friendliness, and (6) Intelligence. The occupant of the head position was also considered to “contribute most” to the group's performance. Sommer's (1967) hypothesis that status and/or dominance ascribes to an individual automatically as a function of the location he occupies was supported. Results were interpreted to demonstrate a “halo effect” reflecting cultural standards and traditions regarding the organization of social space. Some suggestions for future studies were presented.