Salba-chia (Salvia hispanica L.) in the treatment of overweight and obese patients with type 2 diabetes: A double-blind randomized controlled trial.

BACKGROUND AND AIM: Preliminary findings indicate that consumption of Salba-chia (Salvia hispanica L.), an ancient seed, improves management of type 2 diabetes and suppresses appetite. The aim of this study was to assesse the effect of Salba-chia on body weight, visceral obesity and obesity-related risk factors in overweight and obese adults with type 2 diabetes. METHODS: A double-blind, randomized, controlled trial with two parallel groups involved 77 overweight or obese patients with type 2 diabetes (HbA1c: 6.5-8.0%; BMI: 25-40 kg/m2). Both groups followed a 6-month calorie-restricted diet; one group received 30 g/1000 kcal/day of Salba-chia, the other 36 g/1000 kcal/day of an oat bran-based control. Primary endpoint was change in body weight over 6-months. Secondary endpoints included changes in waist circumference, body composition, glycemic control, C-reactive protein, and obesity-related satiety hormones. RESULTS: At 6-months, participants on Salba-chia had lost more weight than those on control (1.9 ± 0.5 kg and 0.3 ± 0.4 kg, respectively; P = 0.020), accompanied by a greater reduction in waist circumference (3.5 ± 0.7 cm and 1.1 ± 0.7 cm, respectively; P = 0.027). C-reactive protein was reduced by 1.1 ± 0.5 mg/L (39 ± 17%) on Salba-chia, compared to 0.2 ± 0.4 mg/L (7 ± 20%) on control (P = 0.045). Plasma adiponectin on the test intervention increased by 6.5 ± 0.7%, with no change observed on control (P = 0.022). CONCLUSIONS: The results of this study, support the beneficial role of Salba-chia seeds in promoting weight loss and improvements of obesity related risk factors, while maintaining good glycemic control. Supplementation of Salba-chia may be a useful dietary addition to conventional therapy in the management of obesity in diabetes. REGISTRATION: clinicaltrials.gov identifier: NCT01403571.

Comparison of flax (Linum usitatissimum) and Salba-chia (Salvia hispanica L.) seeds on postprandial glycemia and satiety in healthy individuals: a randomized, controlled, crossover study.

BACKGROUND/OBJECTIVES: Flax and Salba-chia seeds have risen in popularity owing to their favorable nutrient composition, including a high fiber content. Despite having comparable nutritional profiles, preliminary observations suggest differences in gelling properties, an attribute that may alter the kinetics of food digestion. Thus, we compared the effect of two seeds on postprandial glycemia and satiety scores. SUBJECTS/METHODS: Fifteen healthy participants (M/F: 5/10; age: 23.9±3 years; BMI: 22.2±0.8 kg/m2) were randomized to receive a 50 g glucose challenge, alone or supplemented with either 25 g ground Salba-chia or 31.5 g flax, on three separate occasions. Blood glucose samples and satiety ratings were collected at fasting and over 2-h postprandially. In addition, in vitro viscosity of the beverages was assessed utilizing standard rheological methodology. RESULTS: Both Salba-chia and flax reduced blood glucose area under the curve over 120 min by 82.5±19.7 mmol/l (P<0.001) and 60.0±19.7 mmol/l (P=0.014), respectively, relative to a glucose control. Salba-chia reduced peak glucose (-0.64±0.24 mmol/l; P=0.030) and increased time to peak (11.3±3.8 min; P=0.015) compared with flax. Salba-chia significantly reduced the mean ratings of desire to eat (-7±2 mm; P=0.005), prospective consumption (-7±2 mm; P=0.010) and overall appetite score (-6±2 mm; P=0.012), when compared with flax. The viscosity of Salba-chia, flax and control was 49.9, 2.5, and 0.002 Pa·s, respectively. CONCLUSIONS: Despite the similarities in nutritional composition, Salba-chia appears to have the ability to convert glucose into a slow-release carbohydrate and affect satiety to a greater extent than flax, possibly due to the higher fiber viscosity. Incorporation of either flax or Salba-chia into the diet may be beneficial, although use of Salba-chia may confer additional benefit.

A systematic review and meta-analysis of randomized controlled trials of the effect of barley ß-glucan on LDL-C, non-HDL-C and apoB for cardiovascular disease risk reductioni-iv.

BACKGROUND/OBJECTIVES: There has been recent interest in barley as a therapeutic food owing to its high content of beta-glucan (ß-glucan), a viscous soluble fiber recognized for its cholesterol-lowering properties. The objective of this study was to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the cholesterol-lowering potential of barley ß-glucan on low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B (apoB) for cardiovascular disease (CVD) risk reduction. METHODS: MEDLINE, Embase, CINAHL and the Cochrane CENTRAL were searched. We included RCTs of ⩾3-week duration assessing the effect of diets enriched with barley ß-glucan compared with controlled diets on LDL-C, non-HDL-C or apoB. Two independent reviewers extracted relevant data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed by the Cochran Q-statistic and quantified by the I2 statistic. RESULTS: Fourteen trials (N=615) were included in the final analysis. A median dose of 6.5 and 6.9 g/day of barley ß-glucan for a median duration of 4 weeks significantly reduced LDL-C (MD=-0.25 mmol/l (95% CI: -0.30, -0.20)) and non-HDL-C (MD=-0.31 mmol/l (95% CI: -0.39, -0.23)), respectively, with no significant changes to apoB levels, compared with control diets. There was evidence of considerable unexplained heterogeneity in the analysis of non-HDL-C (I2=98%). CONCLUSIONS: Pooled analyses show that barley ß-glucan has a lowering effect on LDL-C and non-HDL-C. Inclusion of barley-containing foods may be a strategy for achieving targets in CVD risk reduction.

Regulation of the mitogen-activated protein kinase kinase (MEK)-1 by NAD(+)-dependent deacetylases.

Sirtuins are class III deacetylases that regulate many essential processes, including cellular stress, genome stability and metabolism. Although these NAD(+)-dependent deacetylases control adaptive cellular responses, identification of sirtuin-regulated signaling targets remain under-studied. Here, we demonstrate that acetylation of the mitogen-activated protein kinase kinase-1 (MEK1) stimulates its kinase activity, and that acetylated MEK1 is under the regulatory control of the sirtuin family members SIRT1 and SIRT2. Treatment of cells with sirtuin inhibitors, or siRNA knockdown of SIRT1 or SIRT2 proteins, increases MEK1 acetylation and subsequent phosphorylation of the extracellular signal-regulated kinase. Generation of an acetyl-specific MEK1 antibody demonstrates that endogenous acetylated MEK1 is extensively enriched in the nucleus following epidermal growth factor  stimulation. An acetyl-mimic of MEK1 increases inappropriate growth properties, suggesting that acetylation of MEK1 has oncogenic potential.

Viewing and engaging in an art therapy exhibit by people living with mental illness: implications for empathy and social change.

OBJECTIVE: To determine how healthcare professionals, family members and community members responded to an art exhibit created by people living with mental illness. STUDY DESIGN: Phenomenological study with qualitative analysis. METHODS: Forty-six participants with various relationships with people living with mental illness attended an art therapy exhibit and art making workshop. Surveys, response art, reflective writing and discussion groups were used in this qualitative research study. RESULTS: Responses were categorized into four cluster themes: empathic, self-oriented, other-oriented and world-oriented. CONCLUSIONS: Each response category has strengths and weaknesses, indicating implications for increasing awareness and understanding of the artists and mental illness. They also inform educational interventions that can be utilized when using art exhibits for the purpose of confronting bias and stigma towards people living with mental illness.

Psychiatric nurses' attitudes to antipsychotic depots in Hong Kong and comparison with London.

Psychiatric nurses' attitudes to depots have only been explored in the UK. We conducted a cross-sectional attitudinal study for Hong Kong psychiatric nurses and also conducted international comparisons for nurses' views about depots. A pre-existing UK questionnaire on clinicians' attitudes and knowledge regarding depots was updated for the present study. Participants were 98 psychiatric nurses who attended an academic meeting. The majority of respondents had positive views regarding their role in depot administration; most reported that they had sufficient training (84%). However, many did not feel involved in treatment decision making (60%) and other negative views were expressed including: (1) most patients always prefer to have oral (vs. depot) (80%); and (2) force is sometimes required when administering a depot (40%). Interestingly, most reported that patients' friends and family were more accepting of depot (vs. oral) (69%). When compared with a former sample of London community psychiatric nurses, Hong Kong nurses had less favourable patient-focussed attitudes (mean 56% vs. 60%, P = 0.051) and depot-specific attitudes regarding depots (mean 63% vs. 69%, P < 0.001). In conclusion, therefore, international variation exists and encompasses clinical practice aspects for both the patient and the depot formulation per se. Our participants wanted more involvement in treatment decision making.

Copine-I represses NF-kappaB transcription by endoproteolysis of p65.

Nuclear factor-kappaB (NF-kappaB) is a dynamic transcription factor that regulates important biological processes involved in cancer initiation and progression. Identifying regulators that control the half-life of NF-kappaB is important to understanding molecular processes that control the duration of transcriptional responses. In this study we identify copine-I, a calcium phospholipid-binding protein, as a novel repressor that physically interacts with p65 to inhibit NF-kappaB transcription. Knockdown of copine-I by siRNA increases tumor necrosis factor alpha-stimulated NF-kappaB transcription, while copine-I expression blocks endogenous transcription. Copine-I abolishes NF-kappaB transcription by inducing endoprotease processing of the N-terminus of p65, a process antagonized by IkappaB alpha. Copine-I stimulates endoproteolysis of p65 within a conserved region that is required for base-specific contact with DNA. p65 proteins lacking the N-terminus fail to bind to DNA and act as dominant-negative molecules that inhibit NF-kappaB transcription. Our work provides evidence that copine-I regulates the half-life of NF-kappaB transcriptional responses through a novel mechanism that involves endoproteolysis of the p65 protein.

A luciferase transgenic mouse model: visualization of prostate development and its androgen responsiveness in live animals.

Numerous mouse models of prostate carcinogenesis have been developed, but hitherto there has been no model in which the prostate gland could be imaged in live animals. The transgenic model generated here targeted mouse prostate gland using a firefly luciferase enzyme under the control of a small but highly active and specific supra prostate-specific antigen (sPSA) promoter. We evaluated postnatal prostate development, involution and androgen-induced restoration of prostate growth in adult transgenic mice using bioluminescence imaging. Results of our study showed that: (i) the prostate gland of male offspring did not yield a significant bioluminescence signal until after sexual maturity. Luciferase was detected in the luminal epithelial cells of the ventral and dorsolateral lobes of the prostate gland and caput epididymis, with little or no activity in 18 other organs evaluated. (ii) While a constant high level of bioluminescence was detected in the mouse prostate from 5 to 35 weeks of age, a slight drop in bioluminescence was detected at 36 to 54 weeks. (iii) Upon castration, the luciferase activity signal associated with mouse prostate detected by a cooled charge-coupled device camera was dramatically reduced. This signal could be rapidly restored to pre-castration levels after androgen administration. Androgen-induced luciferase activity subsided to nearly basal levels 5 days following the last injection. These data demonstrate that a bioluminescent mouse model with luciferase activity restricted to the prostate gland under the control of a (sPSA) promoter can be used on a real-time basis in live animals to investigate the development and responsiveness of the prostate gland to exogenously administered androgen. This model can be extended to detect the responsiveness of the prostate gland to therapy and used as a founder strain to visualize tumors in hosts with different genetic backgrounds.

Fear of falling and depressive symptoms in Chinese elderly living in nursing homes: fall efficacy and activity level as mediator or moderator?

Depression is a common problem for many Hong Kong Chinese elderly, especially those living in nursing homes. This study examines the relationship between fear of falling and depressive symptoms as well as the role of participation in physical activity and fall efficacy in the linkage between the fear of falling and depression. A sample of 100 residents living in nursing homes were interviewed. Using multiple regression models, we found that elderly persons who had greater fear of falling tended to report depressive symptoms more frequently after controlling socio-demographic and physical health status variables. In addition, activity involvement and fall efficacy acted as mediators and moderators in the link between the fear of falling and depression. Policy makers and aged care professional practitioners should find these findings valuable in promoting activity to aid in the prevention of depression amongst the elderly population.

Does Danshen improve disability after acute ischaemic stroke?

OBJECTIVES: Danshen, a Chinese herb, has been used as a standard treatment for acute ischaemic stroke in China. This study assesses the quality of all randomized control trials (RCTs) comparing Danshen of any preparation to without Danshen (placebo or other western or herbal medicines), and to evaluate its effectiveness in improving disability. MATERIALS AND METHODS: Systematic review through literature search in MEDLINE, Cochrane Library, China Biological Medicine Database and others. The main outcome measure is disability improvement on the Chinese National Disability Scale (CNDS) at 2 weeks after intervention. RESULTS: Of 33 Danshen control trials for acute ischaemic stroke identified in the literature, none were placebo-controlled. Eleven RCTs comparing Danshen with one of seven Western and two herbal medicines met the inclusion criteria for review, however, these studies were of poor quality. Compared with the nine medicines, the effect of Danshen was inferior in five trials and not significantly different in another six trials. For the two trials comparing Danshen with Buflomedil, the combined odds ratio (OR) was 0.27 (95% CI: 0.12-0.61) favouring Buflomedil, but the test of homogeneity revealed heterogeneity (P = 0.083). For the two trials comparing Danshen with Naloxone, the combined OR was 0.16 (95% CI: 0.07-0.40) favouring Naloxone. However, none of the nine medicines per se has been proven effective in post-stroke disability improvement. CONCLUSIONS: The existing Danshen RCTs are not placebo-controlled and are of poor quality, therefore, there is no substantial evidence that Danshen is effective. Systematic review on RCTs comparing Danshen with other medicines does not support the notion that Danshen may be beneficial to disability improvement after acute ischaemic stroke.

Nutritional status of older Tibetans in rural Sichuan China.

OBJECTIVE: To examine the nutritional status of older Tibetans in rural China. DESIGN: Cross sectional study. SETTING: Remote mountainous region of Sichuan province of Western China. SUBJECTS AND METHOD: Forty four male and forty six female Tibetans, over 60 years old were recruited. Body weight, standing height, triceps and bicep skinfold thicknesses (TSF, BSF), mid arm circumference (MAC) and waist circumference (WC) were measured. Dietary intakes were assessed by a twenty-four hour dietary recall. Based on skinfold thicknesses and MAC, total body fat and corrected arm muscle area (CAMA) were calculated by published equations. Their nutritional status and dietary intakes were compared with those of normal older people in Hong Kong and a rural area near Tianjin in the east coast of China. RESULTS: Compared with Hong Kong older women, the Tibetan older women had similar BMI and total body fat, but their CAMA was significantly greater (p<0.01). The Tibetan older men had lower BMI, total body fat (p<0.05), and higher CAMA than the Hong Kong older men (p<0.05). The average calorie intake in the Tibetans was lower than that of older people in Hong Kong and rural Tianjin. Intakes of protein, vitamins and minerals were the lowest in Tibetans and the highest in older people in Hong Kong. CONCLUSIONS: Older Tibetans had more lean mass than Hong Kong older Chinese despite having lower caloric and protein intakes. Older Tibetan women were fatter than their male counterparts, and they were as fat as the older people in Hong Kong, despite having low caloric intakes.

Osteocalcin is incompletely spliced in non-osseous tissues.

Osteocalcin (OC) is known to be a bone tissue-specific protein, expression of which is believed to be controlled by the OC promoter. In this communication, we provided evidence to demonstrate that tissue-specific expression of OC was also regulated at the RNA splicing level. We identified incompletely spliced variants of human OC mRNA, which retain one or more introns during RNA splicing, existing dominantly in non-osseous organs. Northern blot analysis identified two OC RNA transcripts expressed in normal human tissues, but the expression level of the transcripts varied between the tissues. Most non-osseous tissues expressed transcripts with higher molecular weight, prominent in ovary, kidney, pancreas, spleen, thymus, prostate, and testis, than the expected size of OC mRNA as seen in bone marrow. RT-PCR analysis identified up to six OC transcripts in most tissues tested except bone marrow. Sequence analysis showed that four of five RNA variants contained intron 1 in common and the dominant one contained all three introns. MG63, an osteoblastic osteosarcoma cell, expressed only the completely-spliced form of OC, whereas incompletely spliced RNA was dominant in most prostate tumor cells. Combined study of in situ hybridization and immunohistochemistry revealed that OC RNA was highly expressed in prostate tumor epithelial cells while only very low levels of protein were detected, which confirms that there are OC RNA variants in non-osseous tissues. In conclusion, we demonstrated that OC mRNA is also expressed in several non-osseous tissues. However, only bone preferentially underwent the complete splicing event of all three introns. The function of other splicing variants of OC mRNA needs to be further investigated.

Cross-cultural validation of the London Handicap Scale in Hong Kong Chinese.

STUDY OBJECTIVE: To investigate the cross-cultural validity of London Handicap Scale in Hong Kong Chinese. DESIGN: Ratings of the utility of 10 hypothetical health scenarios were given by groups of HK Chinese subjects. Measured scores were compared with calculated scores from published scale weights of London Handicap Scale, which were based on utility ratings made by UK subjects. SETTING: A rehabilitation hospital in Hong Kong. SUBJECTS: A total of 164 HK Chinese, comprising doctors, medical students, nonmedical hospital staff, geriatric day hospital stroke and nonstroke patients, community day-care centre elderly, old age hostel elderly, young disabled inpatients and young community-dwelling disabled citizens. MAIN RESULTS: There was a close correlation between the mean scores of HK subjects and the calculated scores derived from the published UK scale weights, apart from one scenario (Pearson's correlation coefficient r = 0.87 p = 0.001). The correlations were high for all subgroups, between which there was good consensus. Measured utilities were significantly different between subgroups for only one scenario. For this scenario of moderate to severe handicap in mobility, physical dependence, occupation and social integration, but with excellent orientation and economic self sufficiency: (1) older age groups gave better scores than younger age groups (p < 0.0005); (2) subjects with poor subjective health status gave better scores than those with good subjective health status (p = 0.002); (3) subjects related to the medical or hospital field, i.e. doctors, medical students and nonmedical hospital staff, gave worse scores than other subject groups (p < 0.0005). CONCLUSION: The concept of handicap applies across cultures. Perception of severity of selected real life handicap scenarios by HK Chinese were well estimated using scale weights from UK populations developed for the London Handicap Scale. Significant differences in perception of certain handicap scenarios by different population subgroups deserve further study.

Regions of prostate-specific antigen (PSA) promoter confer androgen-independent expression of PSA in prostate cancer cells.

Prostate-specific antigen (PSA) is expressed primarily by both normal prostate epithelium and the vast majority of prostate cancers. Increases in serum PSA during endocrine therapy are generally considered as evidence for prostate cancer recurrence or progression to androgen independence. The mechanisms by which PSA up-regulation occurs in androgen-refractory prostate cancer cells are unknown. In this study, by using LNCaP and its lineage-derived androgen-independent PSA-producing subline, C4-2, we identified two cis-elements within the 5.8-kilobase pair PSA promoter that are essential for the androgen-independent activity of PSA promoter in prostate cancer cells. First, a previously reported 440-bp androgen-responsive element enhancer core (AREc) was found to be important for the high basal PSA promoter activity in C4-2 cells. Both mutation analysis and supershift experiments demonstrated that androgen receptor (AR) binds to the AREs within the AREc and activate the basal PSA promoter activity in C4-2 cells under androgen-deprived conditions. Second, a 150-bp pN/H region was demonstrated to be a strong AR-independent positive-regulatory element of the PSA promoter in both LNCaP and C4-2 cells. Through DNase I footprinting and linker scan mutagenesis, a 17-bp RI site was identified as the key cis-element within the pN/H region. Data from electrophoretic mobility shift analysis and UV cross-linking experiments further indicated that a 45-kDa (p45) cell-specific transcription factor associates with RI in prostate cancer cells and may be responsible for driving the PSA promoter activity independent of androgen and AR. Furthermore, by juxtaposing AREc and pN/H, we produced a chimeric PSA promoter (supra-PSA) that exhibits 2-3-fold higher activity than the wild type PSA promoter in both LNCaP and C4-2 cells.

Osteomimetic properties of prostate cancer cells: a hypothesis supporting the predilection of prostate cancer metastasis and growth in the bone environment.

BACKGROUND: Unlike most other malignancies, prostate cancer metastasizes preferentially to the skeleton and elicits osteoblastic reactions. METHODS: We present a hypothesis, based upon results obtained from our laboratory and others, on the nature of progression of prostate cancer cells and their predilection to growth and metastasis in the bone microenvironment. We propose the hypothesis that osseous metastatic prostate cancer cells must be osteomimetic in order to metastasize, grow, and survive in the skeleton. The reciprocal interaction between prostate cancer and bone stromal growth factors, including basic fibroblast growth factor (bFGF), hepatocyte growth factor/scatter factor (HGF/SF), and especially the insulin growth factor (IGF) axis initiates bone tropism, and is enhanced by prostate secreted endothelin-1 (ET-1) and urokinase-type plasminogen activator (uPA). Growth factors and peptides that have differentiating activity, such as transforming growth factor beta (TGF-beta), parathyroid hormone-related protein (PTH-rp), and the bone morphogenetic proteins (BMPs), can shift local homeostasis to produce the characteristic blastic phenotype, via interaction with prostate-secreted human kalikrein 2 (hK2), and prostate-specific antigen (PSA). This proposal asserts that altering the expression of certain critical transcription factors, such as Cbfa and MSX in prostate cancer cells, which presumably are under the inductive influences of prostate or bone stromal cells, can confer profiles of gene expression, such as osteopontin (OPN), osteocalcin (OC), and bone sialoprotein (BSP), that mimic that of osteoblasts. RESULTS AND CONCLUSIONS: Elucidation of common proteins, presumably driven by the same promoters, expressed by both prostate cancer and bone stromal cells, could result in the development of novel preventive and therapeutic strategies for the treatment of prostate cancer skeletal metastasis. Agents developed using these strategies could have the potential advantage of interfering with growth and enhancing apoptosis in both prostate cancer and bone stromal compartments. The selective application of gene therapy strategy, driven by tissue-specific and tumor-restricted promoters for the safe delivery and expression of therapeutic genes in experimental models of prostate cancer metastasis, is discussed.

Multilevel and motion model-based ultrasonic speckle tracking algorithms.

A multilevel motion model-based approach to ultrasonic speckle tracking has been developed that addresses the inherent trade-offs associated with traditional single-level block matching (SLBM) methods. The multilevel block matching (MLBM) algorithm uses variable matching block and search window sizes in a coarse-to-fine scheme, preserving the relative immunity to noise associated with the use of a large matching block while preserving the motion field detail associated with the use of a small matching block. To decrease further the sensitivity of the multilevel approach to noise, speckle decorrelation and false matches, a smooth motion model-based block matching (SMBM) algorithm has been implemented that takes into account the spatial inertia of soft tissue elements. The new algorithms were compared to SLBM through a series of experiments involving manual translation of soft tissue phantoms, motion field computer simulations of rotation, compression and shear deformation, and an experiment involving contraction of human forearm muscles. Measures of tracking accuracy included mean squared tracking error, peak signal-to-noise ratio (PSNR) and blinded observations of optical flow. Measures of tracking efficiency included the number of sum squared difference calculations and the computation time. In the phantom translation experiments, the SMBM algorithm successfully matched the accuracy of SLBM using both large and small matching blocks while significantly reducing the number of computations and computation time when a large matching block was used. For the computer simulations, SMBM yielded better tracking accuracies and spatial resolution when compared with SLBM using a large matching block. For the muscle experiment, SMBM outperformed SLBM both in terms of PSNR and observations of optical flow. We believe that the smooth motion model-based MLBM approach represents a meaningful development in ultrasonic soft tissue motion measurement.

Vibration sonoelastography and the detectability of lesions.

Vibration sonoelastography has been developed for the detection of hard lesions in relatively soft tissue. The basic concept is to propagate low-amplitude and low-frequency shear waves (with displacements below 0.1 mm and frequencies typically below 1000 Hz) through deep organs, and displaying the vibration response in real-time using advanced color Doppler imaging techniques. A hard inhomogeneity, such as a tumor, will produce a localized disturbance in the vibration pattern, forming the basis for detection even when the tumor is isoechoic on B-scan images. This paper focuses on the important quantitative issues concerning the detectability or inherent contrast of lesions. The specific factors of lesion size, relative stiffness and vibration frequency are studied using theoretical models, finite element methods and experimental measurements on tissue-mimicking materials. The results indicate that detectability increases with vibration (shear wave) frequency; however, loss mechanisms ultimately limit the penetration of higher vibration frequencies (in the kHz range).