Optoacoustic imaging with synthetic aperture focusing and coherence weighting

Optoacoustic imaging takes advantage of high optical contrast and low acoustic scattering and has found several biomedical applications. In the common backward mode a laser beam illuminates the image object, and an acoustic transducer located on the same side as the laser beam detects the optoacoustic signal produced by thermoelastic effects. A cross-sectional image is formed by laterally scanning the laser beam and the transducer. Although the laser beam width is generally narrow to provide good lateral resolution, strong optical scattering in tissue broadens the optical illumination pattern and thus degrades the lateral resolution. To solve this problem, a combination of the synthetic aperture focusing technique with coherence weighting is proposed. This method synthesizes a large aperture by summing properly delayed signals received at different positions. The focusing quality is further improved by using the signal coherence as an image quality index. A phantom comprising hair threads in a 1% milk solution was imaged with an optoacoustic imaging system. The results show that the proposed technique improved lateral resolution by 400-800% and the signal-to-noise ratio by 7-23 dB over conventional techniques.

Systemic immunity-enhancing effects in healthy subjects following dietary consumption of the lactic acid bacterium Lactobacillus rhamnosus HN001

OBJECTIVE

To determine the effects of the probiotic lactic acid bacterium, Lactobacillus rhamnosus HN001, on natural cellular immunity when delivered orally in normal low-fat milk (LFM) or lactose-hydrolyzed low-fat milk (LFM-LH).

DESIGN

A three stage, pre-post intervention trial, spanning nine weeks.

SETTING

Taipei Medical College Hospital, Taipei, Taiwan.

SUBJECTS

Fifty-two healthy middle-aged and elderly volunteers (17 males, 35 females; median age 63.5, range 44-80).

INTERVENTIONS

Stage 1 (run-in diet): 25 g/200 mL reconstituted LFM powder, twice daily for 3 weeks. Stage 2 (probiotic intervention): LFM or LFM-LH, supplemented with 10(9) CFUs/g L. rhamnosus HN001 in each case, for 3 weeks. Stage 3 (wash-out): LFM for 3 weeks.

MEASURES OF OUTCOME

In vitro phagocytic capacity of peripheral blood polymorphonuclear (PMN) leukocytes; in vitro tumoricidal activity of natural killer (NK) leukocytes.

RESULTS

Immunological responses were unaffected by the run-in diet of LFM alone. In contrast, the relative proportion of PMN cells showing phagocytic activity increased by 19% and 15%, respectively, following consumption of HN001 in either LFM or LFM-LH; the relative level of NK cell tumor killing activity increased by 71% and 147%. In most cases these levels declined following cessation, but remained above baseline.

CONCLUSIONS

Dietary consumption of L. rhamnosus HN001, in a base of low-fat milk or lactose-hydrolyzed low-fat milk, appears to enhance systemic cellular immune responses and may be useful as a dietary supplement to boost natural immunity.

Enhancing immunity by dietary consumption of a probiotic lactic acid bacterium (Bifidobacterium lactis HN019): optimization and definition of cellular immune responses

OBJECTIVE

To define the cellular basis for immune enhancement by a probiotic lactic acid bacteria strain (Bifidobacterium lactis HN019); and to determine whether immune enhancement can be optimized by delivery in oligosaccharide-enriched low-fat milk.

DESIGN

A double-blind, three-stage before-and-after intervention trial.

SETTING

Taipei Medical College Hospital, Taipei, Taiwan.

SUBJECTS

Fifty healthy Taiwanese citizens (age range 41-81; median 60) randomly allocated to two groups.

INTERVENTIONS

In stage 1 (run-in control stage) all subjects consumed reconstituted low-fat milk (LFM) for 3 weeks; in stage 2 (probiotic intervention) subjects consumed B. lactis in LFM (group A) or B. lactis in lactose-hydrolysed LFM (group B) for 3 weeks; in stage 3 all subjects returned to non-supplemented LFM for a further 3 weeks (washout stage). The innate immune functions of two different leucocyte types (polymorphonuclear (PMN) cells and natural killer (NK) cells) were assessed at four time points via in vitro analyses on peripheral blood samples.

RESULTS

While consumption of LFM alone had no significant effect on immune responses, stage 2 results indicated significantly enhanced PMN cell phagocytosis and NK cell tumour killing activity following consumption of milk containing B. lactis. These increases levelled off following cessation of B. lactis consumption, but remained above the pre-treatment values. Increases in PMN and NK cell activity were greatest among subjects who consumed B. lactis in lactose-hydrolysed LFM.

CONCLUSIONS

Dietary consumption of the probiotic bacterium B. lactis HN019 enhanced immune function of two different types of leucocytes; the degree of enhancement was increased by consuming B. lactis in an oligosaccharide-rich substrate.

SPONSORSHIP

Financial support was provided by the New Zealand Dairy Board.