Effect of amyloid peptides on serum withdrawal-induced cell differentiation and cell viability

Abnormal deposition of amyloid-beta(A beta) peptides and formation of neuritic plaques are recognized as pathological processes in Alzheimer's disease (AD) brain. By using amyloid precursor protein (APP) transfected cells, this study aims to investigate the effect of overproduction of A beta on cell differentiation and cell viability. It was shown that after serum withdrawal, untransfected cell (N2a/Wt) and vector transfected cells (N2a/vector) extended long and branched cell processes, whereas no neurites was induced in wild type APP (N2a/APP695) and Swedish mutant APP (N2a/APPswe) transfected N2a cells. After differentiation by serum withdrawal, the localization of APP/A beta and neurofilament was extended to neurites, whereas those of APP-transfected cells were still restricted within the cell body. Levels of both APP and A beta were significantly higher in N2a/APP695 and N2a/APPswe than in N2a/Wt, as determined by Western blot and Sandwich ELISA, respectively. To further investigate the effect of A beta on the inhibition of cell differentiation, we added exogenously the similar level or about 10-times of the A beta level produced by N2a/APP695 and N2a/APPswe to the culture medium and co-cultured with N2a/Wt for 12 h, and we found that the inhibition of serum withdrawal-induced differentiation observed in N2a/APP695 and N2a/APPswe could not be reproduced by exogenous administration of A beta into N2a/Wt. We also observed that neither endogenous production nor exogenous addition of A beta 1-40 or A beta 1- 42, even to hundreds fold of the physiological concentration, affected obviously the cell viability. These results suggest that the overproduction of A beta could not arrest cell differentiation induced by serum deprivation and that, at least to a certain degree and in a limited time period, is not toxic to cell viability.

Dynamic changes of serum SARS-coronavirus IgG, pulmonary function and radiography in patients recovering from SARS after hospital discharge

Objective

The intent of this study was to examine the recovery of individuals who had been hospitalized for severe acute respiratory syndrome (SARS) in the year following their discharge from the hospital. Parameters studied included serum levels of SARS coronavirus (SARS-CoV) IgG antibody, tests of lung function, and imaging data to evaluate changes in lung fibrosis. In addition, we explored the incidence of femoral head necrosis in some of the individuals recovering from SARS.

Methods

The subjects of this study were 383 clinically diagnosed SARS patients in Beijing, China. They were tested regularly for serum levels of SARS-CoV IgG antibody and lung function and were given chest X-rays and/or high resolution computerized tomography (HRCT) examinations at the Chinese PLA General Hospital during the 12 months that followed their release from the hospital. Those individuals who were found to have lung diffusion abnormities (transfer coefficient for carbon monoxide [D_LCO] < 80% of predicted value [pred]) received regular lung function tests and HRCT examinations in the follow-up phase in order to document the changes in their lung condition. Some patients who complained of joint pain were given magnetic resonance imaging (MRI) examinations of their femoral heads.

Findings

Of all the subjects, 81.2% (311 of 383 patients) tested positive for serum SARS-CoV IgG. Of those testing positive, 27.3% (85 of 311 patients) were suffering from lung diffusion abnormities (D_LCO < 80% pred) and 21.5% (67 of 311 patients) exhibited lung fibrotic changes. In the 12 month duration of this study, all of the 40 patients with lung diffusion abnormities who were examined exhibited some improvement of lung function and fibrosis detected by radiography. Of the individuals receiving MRI examinations, 23.1% (18 of 78 patients) showed signs of femoral head necrosis.

Interpretation

The lack of sero-positive SARS-CoV in some individuals suggests that there may have been some misdiagnosed cases among the subjects included in this study. Of those testing positive, the serum levels of SARS-CoV IgG antibody decreased significantly during the 12 months after hospital discharge. Additionally, we found that the individuals who had lung fibrosis showed some spontaneous recovery. Finally, some of the subjects developed femoral head necrosis.

Correlation of behavior changes and BOLD signal in Alzheimer-like rat model

To explore a potential means for the early diagnosis of Alzheimer disease, we studied the relationship of resting T2* signal and tau hyperphosphorylation/spatial memory deficit. The rat model with tau hyperphosphorylation and spatial memory deficit was established by bilateral hippocampi injection of isoproterenol (IP). Then, the correlative alteration between resting T2* signal and spatial memory retention was assessed with blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) study and Morris Water Maze test, and Western blot was employed to confirm tau hyperphosphorylation. The analysis showed following results. (1) Tau phosphorylation at Ser396/Ser404 and Ser199/Ser202 was significantly increased in IP-injected rats as detected by PHF-1 and tau-1, respectively. (2) An AD-like spatial memory retention disturbance was induced at 24 h after isoproterenol injection. (3) A sensitivity threshold of resting T2* signal intensity, which separated the IP-treated rats from vehicle control, was obtained by applying linear regression analysis, and an estimated sensitivity statistical threshold was at 32.62. These results suggest that resting T2* signal may serve as a noninvasive quantitative marker in predicting AD-like spatial memory deficits and tau hyperphosphorylation.

[Dynamic changes of immunoglobulin G in convalescents who have suffered from severe acute respiratory syndrome patients]

OBJECTIVE

To investigate the dynamic changes of the antibody specific to severe acute respiratory syndrome (SARS) coronavirus in convalescents who have suffered from SARS.

METHODS

Samples of peripheral blood were collected twice during the first 2 weeks after discharge and then once every 2 - 4 weeks from 310 convalescents of SARS, 131 males and 179 females, aged 18 - 74, discharged from hospitals in Beijing April 3 to June 20 2003 with the average discharge date of June 10, to detect the level of immunoglobulin G (IgG) by ELISA. A curve of level of IgG was drawn to describe the change by the specific month in the year.

RESULTS

Most of the 310 convalescents underwent successive or non-successive testing for 2 - 4 months and 15 were tested for 5 months, 15 for 6 months, and 2 for 7 months. IgG was detected in each sample with the mean of A value of 0.97 +/- 0.37 (0.197 - 1.849). The mean IgG level peaked in July (1.203), about 35 days after discharge, and then gradually declined to 0.857 in December, a decline by 27.3%.

CONCLUSION

All SARS patients generate specific antibody against the coronavirus. However, the antibody level gradually decline with the lapse of time during the convalescence. Long-term surveillance of the change of antibody is necessary.

[Comparative study of clinical characteristics and prognosis of clinically diagnosed SARS patients with positive and negative serum SARS coronavirus-specific antibodies test]

OBJECTIVE

To investigate clinical characteristics and long-term effects of SARS.

METHODS

Clinical characteristics of 197 SARS patients in Xiao Tang-shan hospital were analyzed retrospectively, and prognosis of them were analyzed prospectively.

RESULTS

Among the 197 patients, 153 patients (77.7%) have positive results of serum SARS coronavirus-specific antibodies test, and 44 patients (22.3%) have negative results. The average age of SARS and non-SARS patients were (40 +/- 12) and (31 +/- 12) years, male/female ratio were 1.0:1.6 and 2.1:1.0, average body temperature were (38.5 degrees C +/- 0.3 degrees C) and (38.1 degrees C +/- 0.4 degrees C), median of fever length were 7.0 d (0.4 approximately 50 d) and 2.3 d (0.3 approximately 37 d) respectively. The occurrence of dyspnea, malaise and gastrointestinal symptom were more often in SARS patient than in non-SARS patients. Some patients have residual symptoms (such as cough, fatigue, dyspnea, abnormality of liver function, hyperglycemia and hyperglyceridemia), and only few patients have lung fibrosis.

CONCLUSION

Some patients with other respiratory diseases were misdiagnosed as SARS. There were several obvious differences of clinical characteristics between SARS patient and non-SARS patients. Prognosis of most patients were preciously well, and few still had abnormality of lung function. Residual symptoms of SARS and side effects of drugs used to treat SARS should be discriminated.

[Prognostic analysis of lung function and chest X-ray changes of 258 patients with severe acute respiratory syndrome in rehabilitation after discharge]

OBJECTIVE

To analyze the clinical characteristics and prognostic changes of rehabilitating severe acute respiratory syndrome (SARS) patients through regular lung function tests and lung imaging studies after discharge and to retrospectively analyze the treatment data of these patients.

METHODS

258 discharged SARS patients received regular SARS-Co virus IgG test, lung function test and chest X-ray and/or high resolution computerized tomography (HRCT) examination at General Hospital of PLA two months after discharge, and the treatment data of these patients were retrospectively analyzed.

RESULTS

80.6% patients (208 of 258 patients) were positive for SARS-Co virus IgG. 21.3% patients (55 of 258 patients) showed lung diffusion abnormity (D(LCO) < 80%pred). Compared to 155 SARS-Co virus IgG positive patients without lung diffusion abnormity and 50 SARS-Co virus IgG negative patients, the 53 SARS-Co virus IgG positive patients with lung diffusion abnormity had longer fever course, higher dosages of glucocorticoid therapy, higher percentage of oxygen therapy and non-invasive ventilation. 51 of the 53 patients with lung diffusion abnormity received lung function test after one month, and the results of D(LCO) improved in 80.4% patients (41 of 51 patients). 40 of 51 patients with lung diffusion abnormity showed lung fibrosis, and the fibrosis decreased in 55% patients (22 of 40 patients) after one month.

CONCLUSIONS

This finding suggests that lung fibrosis caused by SARS mostly occurs in severe patients, and it can resolve spontaneously. D(LCO) may be more sensitive than HRCT in evaluating the fibrotic changes.

Injection of okadaic acid into the meynert nucleus basalis of rat brain induces decreased acetylcholine level and spatial memory deficit

Abnormal hyperphosphorylation of tau and cholinergic deficit occur in the early stage of Alzheimer's disease (AD) and relate to the dementia symptom. Hyperphosphorylation of tau, neurofilament (NF) and other proteins in AD brain appears to be caused by a down-regulation of protein phosphatase 2A (PP2A), but the mechanism leading to cholinergic deficit is still unknown. In this study, we selectively inhibited PP2A by injection of okadaic acid (OA) into the Meynert nucleus basalis of rats. We found that injection of OA induced hyperphosphorylation of tau and NF and decreased acetylcholine (ACh) level in the nucleus basalis of Meynert. These alterations were accompanied by spatial memory deficit in OA-injected rats. We also demonstrated that the OA-induced ACh reduction may be due to a failure of intraneuronal transport of choline acetyltransferase (ChAT) from cell body to the neuronal terminals rather than an alteration of activity of ChAT or acetylcholinesterase. This study suggests that a down-regulation of PP2A may underlie both abnormal hyperphosphorylation of cytoskeletal proteins leading to neurofibrillary degeneration and cholinergic deficiency in AD.

Regulation of Arabidopsis SHY2/IAA3 protein turnover

Auxin/indole acetic acid (Aux/IAA) proteins regulate transcriptional responses to the plant hormone auxin. Gain-of-function mutations in the Arabidopsis SHORT HYPOCOTYL 2 (SHY2/IAA3) gene encoding an Aux/IAA protein increase steady-state levels of SHY2/IAA3 protein and decrease auxin responses, indicating that SHY2/IAA3 negatively regulates auxin signaling. These shy2 mutations also cause ectopic light responses, suggesting that SHY2/IAA3 may promote light signaling. Auxin regulates turnover of the related Auxin-resistant (AXR)2/IAA7 and AXR3/IAA17 proteins by increasing their interaction with the Skp1-Cdc53/cullin-F-box (SCFTIR1) E3 ubiquitin ligase complex. To investigate whether SHY2/IAA3 is regulated similarly, we have used a turnover assay to reveal that axr1 and transport inhibitor resistant (tir)1 mutations affecting SCFTIR1 decrease SHY2/IAA3 turnover. In pull-down assays, SHY2/IAA3 protein interacted with TIR1, the F-box component of SCFTIR1 and with the photoreceptor phytochrome B. Auxin stimulated SHY2/IAA3 interaction with TIR1, whereas the shy2-2 gain-of-function mutation decreased this interaction. Light did not affect the interaction, suggesting that light regulates some other aspect of Aux/IAA gene or protein function. The chemical juglone (5-hydroxy-1,4-naphthoquinone) inhibited the interaction, suggesting that peptidyl-prolyl isomerization may mediate auxin-induced SHY2/IAA3 protein turnover.

[Study on high-rate and low-rate metastatic large-cell lung cancer cell lines via differential display reverse transcript PCR]

BACKGROUND

To investigate the differentially expressed gene profile between high-rate and low-rate metastatic large-cell lung cancer cell lines via differential display reverse transcript PCR (DDRT-PCR).

METHODS

DDRT-PCR was performed in two large-cell lung cancer cell lines with different metastatic ability. The differentially displayed cDNA were cloned and sequenced and compared with the sequences in the GenBank.

RESULTS

Fifty differentially displayed cDNAs were acquired, including 18 function-known genes, 16 function-unknown genes, 16 genomic DNA fragments and 4 ESTs.

CONCLUSIONS

The cell lines have different gene expression profiles, and metastasis is affected by multi-gene expression and regulation. Some genes which contribute to the metastasis of lung cancer could be found by DDRT-PCR, and this study gives some new clues to cancer diagnosis and therapy.

Differential inhibition of human cancer cell proliferation by citrus limonoids

Limonoids have been shown to inhibit the growth of estrogen receptor-negative and -positive human breast cancer cells in culture. The primary objective of this study was to test the antiproliferative activity of limonoids (obacunone 17 beta-D-glucopyranoside, nomilinic acid 17 beta-D-glucopyranoside, limonin, nomilin, and a limonoid glucoside mixture), found in high concentrations in mandarin (Citrus reticulata Blanco), against a series of human cancer cell lines. The human cancer cell lines included leukemia (HL-60), ovary (SKOV-3), cervix (HeLa), stomach (NCI-SNU-1), liver (Hep G2), and breast (MCF-7). The growth-inhibitory effects of the four limonoids and the limonoid glucoside mixture against MCF-7 cells were significant, and the antiproliferative activity of the different citrus limonoids was also dose and time dependent. No significant effects were observed on growth of the other cancer cell lines treated with the four individual limonoids at 100 micrograms/ml. At 100 micrograms/ml, the limonoid glucoside mixture demonstrated a partial inhibitory effect on SKOV-3 cancer cells. With use of flow cytometry, it was found that all the limonoid samples could induce apoptosis in MCF-7 cells at relatively high concentrations (100 micrograms/ml). Considering the high concentration needed to induce apoptosis, it is unlikely that this is the primary mechanism of action for the cytotoxic effects seen with limonoids in this study. Further work is needed in this area to establish the mechanism of action of citrus limonoids on human breast cancer cells.

[Cloning of a new cDNA: responded to all-trans retinoic acid in HL-60 cell differentiation]

In this paper a new type of cDNA fragment named as W-1 gene was first cloned and sequenced from ATRA induced HL-60 cells by using differential display PCR (DD-PCR) and DNA sequencing techniques. These differentially expressing products of the gene responding to ATRA were further confirmed by Northern blotting analysis. The results showed that the expressing level of this gene induced by ATRA (10(-6) mol.L-1) for 16 hrs was much higher than that in the control HL-60 cells, but its expression in HL-60 was reduced to an unestimable level after induction of ATRA (10(-6) mol.L-1) for 24 hrs. It suggests that ATRA may increase the expression of W-1 gene during the early stage of HL-60 cell differentiation. The exact mechanism of action is being studied further.

Role of serine/threonine protein phosphatase in Alzheimer's disease

Accumulating evidence indicates that serine/threonine (Ser/Thr) protein phosphatases (PPs), such as PP1, PP2A and PP2B, participate in the neurodegenerative progress in Alzheimer's disease (AD). The general characteristics and pathologic changes of PP1, PP2A and PP2B in AD, and their relations with microtubule-associated proteins, focusing mainly on tau protein, neurofilament (NF), amyloid precursor protein (APP) processing and synaptic plasticity are discussed. Deriving novel insight into the particular topic will attract greater attention to more active investigation and effective therapeutic intervention in the future.

Arabidopsis SHY2/IAA3 inhibits auxin-regulated gene expression

In Arabidopsis, SHY2 encodes IAA3, a member of the auxin-induced Aux/IAA family. Gain-of-function mutations in SHY2/IAA3 cause enlarged cotyledons, short hypocotyls, and altered auxin-regulated root development. Here we show that the gain-of-function mutation shy2-2 decreases both the induction and repression of auxin-regulated genes, suggesting that SHY2/IAA3 acts as a negative regulator in auxin signaling. shy2-2 affects auxin induction of many previously characterized primary response genes, implying that it might repress primary auxin responses. In addition, shy2-2 also affects expression of multiple auxin-nonresponsive genes. Light regulates expression of SHY2/IAA3, suggesting a possible link between light and auxin response pathways.

Synthesis of 9-alkylidene-9H-fluorenes by a novel, palladium-catalyzed cascade reaction of aryl halides and 1-aryl-1-alkynes

In the presence of a palladium catalyst and NaOAc, aryl iodides react with 1-aryl-1-alkynes to afford 9-alkylidene-9H-fluorenes in good yields. The products from this reaction are highly dependent on the base employed. This process appears to involve (1) oxidative addition of the aryl iodide to Pd(0), (2) alkyne insertion, (3) rearrangement of the resulting vinylic palladium intermediate to an arylpalladium species, and (4) aryl-aryl coupling with simultaneous regeneration of the Pd(0) catalyst. Consistent with this mechanism is the fact that 9-alkylidene-9H-fluorenes can also be prepared by the Pd-catalyzed rearrangement of 1,1-diaryl-2-iodo-1-alkenes.

Function of basonuclin in increasing transcription of the ribosomal RNA genes during mouse oogenesis

Active protein synthesis during early oogenesis requires accelerated transcription of ribosomal RNA genes (rDNAs). In response to this demand, rDNAs are amplified more than 1000-fold early in Xenopus oogenesis. Here, we report evidence that rDNA is not amplified in mouse oocytes, but these cells may instead employ the zinc-finger protein basonuclin, a putative rDNA transcription factor, to enhance rRNA synthesis. This conclusion is based on observations that basonuclin is localized in the nucleolus in the mouse oocyte early in its growth phase, when rRNA transcription is highly active; and that the binding sites of basonuclin zinc fingers on the human and mouse rDNA promoters are homologous. In a co-transfection assay, basonuclin can elevate transcription from an rDNA promoter, and its zinc-finger domain can inhibit RNA polymerase I transcription, as detected by a run-on assay, in growing mouse oocytes.

The C/EBP bZIP domain can mediate lipopolysaccharide induction of the proinflammatory cytokines interleukin-6 and monocyte chemoattractant protein-1

C/EBPalpha, beta, and delta are all expressed by bone marrow-derived macrophages. Ectopic expression of any of these transcription factors is sufficient to confer lipopolysaccharide (LPS)-inducible expression of interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) to a B lymphoblast cell line, which normally lacks C/EBP factors and does not display LPS induction of proinflammatory cytokines. Thus, the activities of C/EBPalpha, beta, and delta are redundant in regard to expression of IL-6 and MCP-1. Surprisingly, the bZIP region of C/EBPbeta, which lacks any previously described activation domains, can also confer LPS-inducible expression of IL-6 and MCP-1 in stable transfectants. Transient transfections reveal that the bZIP regions of C/EBPbeta, C/EBPdelta, and, to a lesser extent, C/EBPalpha can activate the IL-6 promoter and augment its induction by LPS. Furthermore, the transdominant inhibitor, LIP, can activate expression from the IL-6 promoter. The ability of the C/EBPbeta bZIP region to activate the IL-6 promoter in transient transfections is completely dependent upon an intact NF-kappaB-binding site, supporting a model where the bZIP protein primarily functions to augment the activity of NF-kappaB. Replacement of the leucine zipper of C/EBPbeta with that of GCN4 yields a chimeric protein that can dimerize and specifically bind to a C/EBP consensus sequence, but shows a markedly reduced ability to activate IL-6 and MCP-1 expression. These results implicate the leucine zipper domain in some function other than dimerization with known C/EBP family members, and suggest that C/EBP redundancy in regulating cytokine expression may result from their highly related bZIP regions.

[The percentage of hepatitis B virus precore A83 mutant and its dynamicchange in fulminant hepatitis B]

OBJECTIVE

In order to clarify whether hepatitis B virus precore A83 mutant is related to the pathogenesis of fulminant hepatitis B or not.

METHODS

The percentage of hepatitis B virus precore A83 mutant and the quantity of HBV DNA in sera from 9 patients with fulminant hepatitis B were assayed by the method of densitometry after mispairing PCR-restriction fragment length polymorphism (mpPCR-RFLP) and quantitative PCR, respectively.

RESULTS

The HBV precore A83 mutant was found in sera of 6 out of 9 (66.7%) fulminant hepatitis patients while none of them were infected with the mutant strain alone, and all were mixed with wild strain. The percentage of the mutant over fifty percent is only in 2 cases in whom one was 59.3% (survival) and another 64.8% (died). The percentage below 31.0% was in 4 cases and all of them died. It was observed that appearance or disappearance of the A83 mutant and its dynamic change of percentage were consistent with the fluctuation of HBV DNA level but there was no correlation statistically (r=0.602, 0.583; P>0.05).

CONCLUSION

The mutant strain alone has little correlation to the occurrence of fulminant hepatitis. It might be merely a accompaniment to follow the replication of HBV under the highly immune pressure.

Screening for limonoid glucosides in Citrus tangerina (Tanaka) Tseng by high-performance liquid chromatography-electrospray ionization mass spectrometry

A screening method for limonoid glucosides in the peel of Citrus tangerina (Tanaka) Tseng, which utilizes high-performance liquid chromatography (HPLC) with diode-array detection and interfaced to electrospray ionization mass spectrometry, has been developed. In this way, the UV-Vis spectra and the mass spectra indicate the presence of limonoid glucosides without the necessity of isolating the individual compounds. Two major limonoid glucosides--obacunone glucoside (OG) and nomilin glucoside (NG)--were identified in the methanol extract of the peel. The two limonoid glucosides were taken as the target and isolated by means of preparative HPLC on a C18 reversed-phase column with an acidic acetonitrile-water mobile phase. The structures of OG and NG were further confirmed by nuclear magnetic resonance spectrometry.

Effects of air pollution on children's respiratory health in three Chinese cities

During the winter of 1988-1989, parents of 2,789 elementary-school students completed standardized questionnaires. The students were 5-14 y of age and were from three urban districts and one suburban district of three large Chinese cities. The 4-y average ambient levels of total suspended particles in the three cities differed greatly during the period 1985-1988: Lanzhou, 1,067 microg/m3; urban Wuhan, 406 microg/m3; Guangzhou, 296 microg/m3; and suburban Wuhan, 191 microg/m3. The authors constructed unconditional logistic-regression models to calculate odds ratios and 95% confidence intervals for prevalences of several respiratory symptoms and illnesses, adjusted for district, use of coal in the home, and parental smoking status. There was a positive and significant association between total suspended particle levels and the adjusted odds ratios for cough, phlegm, hospitalization for diseases, and pneumonia. This association was derived from only the 1,784 urban children and, therefore, the authors were unable to extrapolate it to the suburban children. The results also indicated that parental smoking status was associated with cough and phlegm, and use of coal in the home was associated only with cough prevalence (alpha = 0.05).

Parametric modeling in food package defect imaging

A novel approach in food package defect detection is proposed based on system identification theory, in which the channel defect detection problem can be regarded as the conventional system identification problem, i.e., estimation of the system impulse response based on the input-output sequence using parametric and nonparametric models. The well-known parametric model ARX has been investigated in this paper. The data are collected with a focused ultrasound transducer (17.3 MHz, 6.35-mm diameter, f/2, 173 microm -6 dB pulse-echo lateral beam width at the focus) scanned over a rectangular grid, keeping the packages in the focus. Performance is measured in terms of detection rate, image contrast, and contrast-to-noise ratio. The results using the ARX model are compared with previous image formation techniques and also compared with the non-parametric method, i.e., spectral analysis. The results show that the ARX model has the comparable detection rate as RFCS and higher detection rate than BAI and RFS (except 6-microm air-filled channel in plastic trilaminate film) for channel in plastic trilaminate film. The ARX model has achieved the moderate contrast enhancement and ranks second in contrast-to-noise ratio enhancement among the compared techniques. The ARX model has a low detection rate for channel defects in aluminum trilaminate film, which shows that its performance is material-dependent. Finally, the parametric method, ARX model demonstrates better performance than the non-parametric method, spectral analysis for food package defect detection.

High contrast ultrasound images of defects in food package seals

Previous work to detect defects in food packaging seals using pulse-echo ultrasound inspired the backscattered amplitude integral (BAI) imaging technique, which could reliably identify channels with diameters 38 microm or larger at a center frequency of 17.3 MHz (lambda=86 microm). The current study presents two new processing techniques that more reliably reveal smaller channels ( approximately 6 microm in diameter). The RF sampling technique (RFS) displays a single, time-gated, pressure value from the received (not envelope-detected) RF waveform at each transducer position. The RF correlation technique (RFC) calculates the correlation coefficients of the RF signals with a reference signal that does not pass through a channel. The correlation coefficient can be calculated for the entire RF signal (RFCE) or over a short segment of the RF signal (RFCS). The performance of these imaging methods for detecting channel defects is investigated for plastic and aluminum foil trilaminate films with 6, 10, 15, 38, and 50 microm channels filled with water or air. Data are collected with a focused ultrasound transducer (17.3 MHz, 6.35 mm in diameter, f/2, 173 microm -6 dB pulse-echo lateral beamwidth at the focus) scanned over a rectangular grid, keeping the package in the focus. Performance is measured using detection rates, image contrast, and contrast-to-noise ratio (CNR). Both RFS and RFCS have improved detection rates relative to BAI for channels 15 microm or smaller. The RFCS technique is the most effective at smoothing the background, leading to the greatest CNR improvements.