Design and testing of low intensity laser biostimulator

BACKGROUND: The non-invasive nature of laser biostimulation has made lasers an attractive alternative in Medical Acupuncture at the last 25 years. However, there is still an uncertainty as to whether they work or their effect is just placebo. Although a plethora of scientific papers published about the topic showing positive clinical results, there is still a lack of objective scientific proofs about the biostimulation effect of lasers in Medical Acupuncture. The objective of this work was to design and build a low cost portable laser device for stimulation of acupuncture points, considered here as small localized biosources (SLB), without stimulating any sensory nerves via shock or heat and to find out a suitable method for objectively evaluating its stimulating effect. The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the biostimulation effect of lasers used in Medical Acupuncture. METHODS: The proposed biostimulator features two operational modes: program mode and stimulation mode and two output polarization modes: linearly and circularly polarized laser emission. In program mode, different user-defined stimulation protocols can be created and memorized. The laser output can be either continuous or pulse modulated. Each stimulation session consists of a pre-defined number of successive continuous or square pulse modulated sequences of laser emission. The variable parameters of the laser output are: average output power, pulse width, pulse period, and continuous or pulsed sequence duration and repetition period. In stimulation mode the stimulus is automatically applied according to the pre-programmed protocol. The laser source is 30 mW AlGaInP laser diode with an emission wavelength of 685 nm, driven by a highly integrated driver. The optical system designed for beam collimation and polarization change uses single collimating lens with large numerical aperture, linear polarizer and a quarter-wave retardation plate. The proposed method for testing the device efficiency employs a biofeedback from the subject by recording the biopotentials evoked by the laser stimulus at related distant SLB sites. Therefore measuring of SLB biopotentials caused by the stimulus would indicate that a biopotential has been evoked at the irradiated site and has propagated to the measurement sites, rather than being caused by local changes of the electrical skin conductivity. RESULTS: A prototype device was built according to the proposed design using relatively inexpensive and commercially available components. The laser output can be pulse modulated from 0.1 to 1000 Hz with a duty factor from 10 to 90 %. The average output power density can be adjusted in the range 24 – 480 mW/cm2, where the total irradiation is limited to 2 Joule per stimulation session. The device is controlled by an 8-bit RISC Flash microcontroller with internal RAM and EEPROM memory, which allows for a wide range of different stimulation protocols to be implemented and memorized. The integrated laser diode driver with its onboard light power control loop provides safe and consistent laser modulation. The prototype was tested on the right Tri-Heater (TH) acupuncture meridian according to the proposed method. Laser evoked potentials were recorded from most of the easily accessible SLB along the meridian under study. They appear like periodical spikes with a repetition rate from 0.05 to 10 Hz and amplitude range 0.1 – 1 mV. CONCLUSION: The prototype's specifications were found to be better or comparable to those of other existing devices. It features low component count, small size and low power consumption. Because of the low power levels used the possibility of sensory nerve stimulation via the phenomenon of shock or heat is excluded. Thus senseless optical stimulation is achieved. The optical system presented offers simple and cost effective way for beam collimation and polarization change. The novel method proposed for testing the device efficiency allows for objectively recording of SLB potentials evoked by laser stimulus. Based on the biopotential records obtained with this method, a scientifically based conclusion can be drawn about the effectiveness of the commercially available devices for low-level laser therapy used in Medical Acupuncture. The prototype tests showed that with the biostimulator presented, SLB could be effectively stimulated at low power levels. However more studies are needed to derive a general conclusion about the SLB biostimulation mechanism of lasers and their most effective power and optical settings

Evolutionary patterns of two major reproduction candidate genes (Zp2 and Zp3) reveal no contribution to reproductive isolation between bovine species

<p>Abstract</p> <p>Background</p> <p>It has been established that mammalian egg zona pellucida (ZP) glycoproteins are responsible for species-restricted binding of sperm to unfertilized eggs, inducing the sperm acrosome reaction, and preventing polyspermy. In mammals, ZP apparently represents a barrier to heterospecific fertilization and thus probably contributes to reproductive isolation between species. The evolutionary relationships between some members of the tribe Bovini are complex and highly debatable, particularly, those involving <it>Bos </it>and <it>Bison </it>species for which interspecific hybridization is extensively documented. Because reproductive isolation is known to be a major precursor of species divergence, testing evolutionary patterns of ZP glycoproteins may shed some light into the speciation process of these species. To this end, we have examined intraspecific and interspecific genetic variation of two ZP genes (<it>Zp2 </it>and <it>Zp3</it>) for seven representative species (111 individuals) from the Bovini tribe, including five species from <it>Bos </it>and <it>Bison</it>, and two species each from genera <it>Bubalus </it>and <it>Syncerus</it>.</p> <p>Results</p> <p>A pattern of low levels of intraspecific polymorphism and interspecific divergence was detected for the two sequenced fragments each for <it>Zp2 </it>and <it>Zp3</it>. At intraspecific level, none of neutrality tests detected deviations from neutral equilibrium expectations for the two genes. Several haplotypes in both genes were shared by multiple species from <it>Bos </it>and <it>Bison</it>.</p> <p>Conclusions</p> <p>Here we argue that neither ancestral polymorphism nor introgressive hybridization alone can fully account for haplotype sharing among species from <it>Bos </it>and <it>Bison</it>, and that both scenarios have contributed to such a pattern of haplotype sharing observed here. Additionally, codon-based tests revealed strong evidence for purifying selection in the <it>Zp3 </it>coding haplotype sequences and weak evidence for purifying selection in the <it>Zp2 </it>coding haplotype sequences. Contrary to a general genetic pattern that genes or genomic regions contributing to reproductive isolation between species often evolve rapidly and show little or no gene flow between species, these results demonstrate that, particularly, those sequenced exons of the <it>Zp2 </it>and the <it>Zp3 </it>did not show any contribution to reproductive isolation between the bovine species studied here.</p

One-pot enzymatic synthesis of the Gal alpha 1-->3Gal beta 1-->4GlcNAc sequence with in situ UDP-Gal regeneration.

The trisaccharide Gal alpha 1-->3Gal beta 1-->4GlcNAc beta 1-->O-(CH2)8COOCH3 was enzymatically synthesized, with in situ UDP-Gal regeneration. By combination in one pot of only four enzymes, namely, sucrose synthase, UDP-Glc 4'-epimerase, UDP-Gal:GlcNAc beta 4-galactosyltransferase and UDP-Gal:Gal beta 1-->4GlcNAc alpha 3-galactosyltransferase, Gal alpha 1-->3Gal beta 1-->4GlcNAc beta 1-->O-(CH2)8COOCH3 was formed in a 2.2 mumol ml-1 yield starting from the acceptor GlcNAc beta 1-->O-(CH2)8COOCH3. This is an efficient and convenient method for the synthesis of the Gal alpha 1-->3Gal beta 1-->4GlcNAc epitope which pays an important role in various biological and immunological processes