Dry coupling for whole-body small-animal photoacoustic computed tomography

We have enhanced photoacoustic computed tomography with dry acoustic coupling that eliminates water immersion anxiety and wrinkling of the animal and facilitates incorporating complementary modalities and procedures. The dry acoustic coupler is made of a tubular elastic membrane enclosed by a closed transparent water tank. The tubular membrane ensures water-free contact with the animal, and the closed water tank allows pressurization for animal stabilization. The dry coupler was tested using a whole-body small-animal ring-shaped photoacoustic computed tomography system. Dry coupling was found to provide image quality comparable to that of conventional water coupling.

Photoacoustic microscopy of arteriovenous shunts and blood diffusion in early-stage tumors

Angiogenesis in a tumor region creates arteriovenous (AV) shunts that cause an abnormal venous blood oxygen saturation ( sO2 ) distribution. Here, we applied optical-resolution photoacoustic microscopy to study the AV shunting in vivo. First, we built a phantom to image sO2 distribution in a vessel containing converged flows from two upstream blood vessels with different sO2 values. The phantom experiment showed that the blood from the two upstream vessels maintained a clear sO2 boundary for hundreds of seconds, which is consistent with our theoretical analysis using a diffusion model. Next, we xenotransplanted O-786 tumor cells in mouse ears and observed abnormal sO2 distribution in the downstream vein from the AV shunts in vivo. Finally, we identified the tumor location by tracing the sO2 distribution. Our study suggests that abnormal sO2 distribution induced by the AV shunts in the vessel network may be used as a new functional benchmark for early tumor detection.

Three-dimensional arbitrary trajectory scanning photoacoustic microscopy

We have enhanced photoacoustic microscopy with three-dimensional arbitrary trajectory (3-DAT) scanning, which can rapidly image selected vessels over a large field of view (FOV) and maintain a high signal-to-noise ratio (SNR) despite the depth variation of the vessels. We showed that hemoglobin oxygen saturation (sO2 ) and blood flow can be measured simultaneously in a mouse ear in vivo at a frame rate 67 times greater than that of a traditional two-dimensional raster scan. We also observed sO2 dynamics in response to switching from systemic hypoxia to hyperoxia. 3-DAT-scanning photoacoustic microscopy. Schematic diagram of the 3D scanning stage and method.

Microvascular quantification based on contour-scanning photoacoustic microscopy

Accurate quantification of microvasculature remains of interest in fundamental pathophysiological studies and clinical trials. Current photoacoustic microscopy can noninvasively quantify properties of the microvasculature, including vessel density and diameter, with a high spatial resolution. However, the depth range of focus (i.e., focal zone) of optical-resolution photoacoustic microscopy (OR-PAM) is often insufficient to encompass the depth variations of features of interest—such as blood vessels—due to uneven tissue surfaces. Thus, time-consuming image acquisitions at multiple different focal planes are required to maintain the region of interest in the focal zone. We have developed continuous three-dimensional motorized contour-scanning OR-PAM, which enables real-time adjustment of the focal plane to track the vessels’ profile. We have experimentally demonstrated that contour scanning improves the signal-to-noise ratio of conventional OR-PAM by as much as 41% and shortens the image acquisition time by 3.2 times. Moreover, contour-scanning OR-PAM more accurately quantifies vessel density and diameter, and has been applied to studying tumors with uneven surfaces.

Fully motorized optical-resolution photoacoustic microscopy

We have developed fully motorized optical-resolution photoacoustic microscopy (OR-PAM), which integrates five complementary scanning modes and simultaneously provides a high imaging speed and a wide field of view (FOV) with 2.6 μm lateral resolution. With one-dimensional (1D) motion-mode mechanical scanning, we measured the blood flow through a cross section of a blood vessel in vivo. With two-dimensional (2D) optical scanning at a laser repetition rate of 40 kHz, we achieved a 2 kHz B-scan rate over a range of 50 μm with 20 A-lines and 50 Hz volumetric-scan rate over a FOV of 50  μm × 50  μm with 400 A-lines, which enabled real-time tracking of cellular dynamics in vivo. With synchronized 1D optical and 2D mechanical hybrid scanning, we imaged a 10  mm × 8  mm FOV within three minutes, which is 20 times faster than the conventional mechanical scan in our second-generation OR-PAM. With three-dimensional mechanical contour scanning, we maintained the optimal signal-to-noise ratio and spatial resolution of OR-PAM while imaging objects with uneven surfaces, which is essential for quantitative studies.

Photoacoustic microscopy of blood pulse wave

Blood pulse wave velocity (PWV) is an important physiological parameter that characterizes vascular stiffness. In this letter, we present electrocardiogram-synchronized, photoacoustic microscopy for noninvasive quantification of the PWV in the peripheral vessels of living mice. Interestingly, blood pulse wave-induced fluctuations in blood flow speed were clearly observed in arteries and arterioles, but not in veins or venules. Simultaneously recorded electrocardiograms served as references to measure the travel time of the pulse wave between two cross sections of a chosen vessel and vessel segmentation analysis enabled accurate quantification of the travel distance. PWVs were quantified in ten vessel segments from two mice. Statistical analysis shows a linear correlation between the PWV and the vessel diameter which agrees with known physiology.

BCR-ABL truncation due to premature translation termination as a mechanism of resistance to kinase inhibitors

7028

Background: The major mechanism underlying imatinib resistance in patients with chronic myeloid leukemia (CML) is clonal expansion of leukemic cells with point mutations in the BCR-ABL tyrosine kinase. We describe three novel ABL premature termination mutations leading to BCR-ABL truncation in leukemia patients with multidrug (imatinib/nilotinib/dasatinib) resistance. Methods: Peripheral blood or bone marrow samples from drug-resistant CML patients were collected. Total nucleic acids were purified and subjected to two rounds of PCR analysis, with the first PCR designed to eliminate amplification of the wild-type, non-translocated ABL gene. Bi-directional sequencing was then performed. HL60 cells (a Ph-negative myeloid leukemia cell line) and peripheral blood of healthy subjects were used as negative controls; a human CML cell line (K562) was used as a positive control. Results: We identified an exon 7 deletion in three CML patients, a 4-nt insertion (908insCAGG) near the exon 5/6 junction in one CML case, and an exon 6 point mutation (997C>T) in one patient with acute lymphoblastic leukemia (ALL). These mutations all create premature stop codons and cause termination at residues 381, 315, and 333, respectively, leading to truncated proteins with only the first quarter of the kinase domain (P-loop) or lacking the C-terminus of ABL including the A-loop. Conclusions: These novel mutations, and the previously documented 35-nt insertion in exon 8, may constitute a new class of mutations that 1) cause truncation of the BCR-ABL kinase; (2) abolish the regulatory element in the ABL kinase domain and the downstream C-terminal region; and (3) confer significant drug resistance.

[Table: see text]

Alternatively spliced truncated BCR-ABL1 protein in CML patients with resistance to kinase inhibitors

7026

Background: We have reported that some patients with imatinib-resistant chronic myeloid leukemia (CML) express an alternatively spliced BCR-ABL mRNA with a 35-bp insertion (BCR-ABL135INS), resulting in the addition of 10 residues and truncation of 653 residues. Molecular dynamic simulation suggested that this truncation and insertion of new 10 AA results in structural changes similar to those seen in BCR-ABL with T315I mutation. Here we evaluate the prevalence of BCR-ABL135INS in imatinib-resistant CML, examine the effect of this mutation on resistance to compared the efficiency of various kinase inhibitors in vitro, and suggest a model for persistent CML and a possible strategy to eradicate residual disease. Methods: Using a sensitive PCR method, we determined the prevalence of the alternatively spliced BCR-ABL135INS mRNA in 288 patients with chronic-phase CML resistant to imatinib. Expression of truncated protein was confirmed by Western blot. We then tested the effectiveness of various kinase inhibitors on human K562 CML cells expressing different levels of BCR-ABL135INS along with wild-type BCR-ABL1. Results: BCR-ABL135INS mRNA was detected in 210 (73%) of the 288 patients. Only 25% of BCR-ABL135INS positive cases showed coexistance of ABL1 kinase point mutation. Immunoprecipitation studies demonstrated that expression of the predicted 143-kD BCR-ABL135INS protein at levels proportional to those predicted by mRNA. Expression of BCR-ABL135INS in K562 cells was sufficient to conferred resistance to imatinib, dasatinib, and nilotinib in a dose-dependant fashion. However, no resistance was detected using aurora kinase inhibitor (MK 0457) or homoharringtonine (HHT). BCR-ABL135INS suppressed imatinib, nilotinib, and dasatinib-mediated dephosphorylation of CRKL, LYN, SRC, and STAT5, but had no effect on MK 0457-mediated dephosphorylation. The combination of imatinib with nilotinib or HHT showed strong synergy, overcoming BCR-ABL135INS-induced resistance in vitro. Conclusions: These findings emphasize the importance of the overlooked alternatively spliced BCR-ABL135INS protein and may provide a strategy to treat resistant disease and eradicate residual CML.

No significant financial relationships to disclose.

Resveratrol and cancer: chemoprevention, apoptosis, and chemo-immunosensitizing activities

The polyphenolic compound Resveratrol is a naturally occurring phytochemical and can be found in many plant species, including grapes, peanuts and various herbs. Several studies have established that Resveratrol can exert anti-oxidant and anti-inflammatory activities. It also has activity in the regulation of multiple cellular events associated with carcinogenesis. This review describes the general properties of Resveratrol including its relationship to estrogen, its effect on lipid metabolism, its cardiovascular effects, and its role on gene expression. Resveratrol has also been examined in several model systems for its potential effect against cancer. Its anti-cancer effects include its role as a chemopreventive agent, its ability to inhibit cell proliferation, its direct effect in cytotoxicity by induction of apoptosis and on its potential therapeutic effect in pre-clinical studies. In addition, Resveratrol has been shown to exert sensitization effects on cancer cells that will result in a synergistic cytotoxic activity when Resveratrol is used in combination with cytotoxic drugs in drug-resistant tumor cells. Clearly, the studies with Resveratrol provide support for the use of Resveratrol in human cancer chemoprevention and combination with chemotherapeutic drugs or cytotoxic factors in the treatment of drug refractory tumor cells.

Competing risk analysis for life table data with known observation times

"Several models have been proposed for the analysis of cohort mortality in the presence of competing risks.... This paper describes a maximum likelihood approach to the analysis of follow up data in life table format for the case of two competing risks--a specific cause and its competing complement. The model developed uses a robust survivorship assumption--the piecewise exponential--and takes into account information on time to death and time to withdrawal." (summary in GER)

The Emergency Medical Treatment and Labor Act as a federal health care safety net program

Despite the greatest economic expansion in history during the 1990s, the number of uninsured U.S. residents surpassed 44 million in 1998. Although this number declined for the first time in recent years in 1999, to 42.6 million, the current economic slow-down threatens once again to increase the ranks of the uninsured. Many uninsured patients use hospital emergency departments as a vital portal of entry into an access-impoverished health care system. In 1986, Congress mandated access to emergency care when it passed the Emergency Medical Treatment and Labor Act (EMTALA). The EMTALA statute has prevented the unethical denial of emergency care based on inability to pay; however, the financial implications of EMTALA have not yet been adequately appreciated or addressed by Congress or the American public. Cuts in payments from public and private payers, as well as increasing demands from a larger uninsured population, have placed unprecedented financial strains on safety net providers. This paper reviews the financial implications of EMTALA, illustrating how the statute has evolved into a federal health care safety net program. Future actions are proposed, including the pressing need for greater public safety net funding and additional actions to preserve health care access for vulnerable populations.

The adhesion receptor CD44 promotes atherosclerosis by mediating inflammatory cell recruitment and vascular cell activation

Atherosclerosis causes most acute coronary syndromes and strokes. The pathogenesis of atherosclerosis includes recruitment of inflammatory cells to the vessel wall and activation of vascular cells. CD44 is an adhesion protein expressed on inflammatory and vascular cells. CD44 supports the adhesion of activated lymphocytes to endothelium and smooth muscle cells. Furthermore, ligation of CD44 induces activation of both inflammatory and vascular cells. To assess the potential contribution of CD44 to atherosclerosis, we bred CD44-null mice to atherosclerosis-prone apoE-deficient mice. We found a 50-70% reduction in aortic lesions in CD44-null mice compared with CD44 heterozygote and wild-type littermates. We demonstrate that CD44 promotes the recruitment of macrophages to atherosclerotic lesions. Furthermore, we show that CD44 is required for phenotypic dedifferentiation of medial smooth muscle cells to the "synthetic" state as measured by expression of VCAM-1. Finally, we demonstrate that hyaluronan, the principal ligand for CD44, is upregulated in atherosclerotic lesions of apoE-deficient mice and that the low-molecular-weight proinflammatory forms of hyaluronan stimulate VCAM-1 expression and proliferation of cultured primary aortic smooth muscle cells, whereas high-molecular-weight forms of hyaluronan inhibit smooth muscle cell proliferation. We conclude that CD44 plays a critical role in the progression of atherosclerosis through multiple mechanisms.

The effects of concomitant phenytoin administration on the steady-state pharmacokinetics of quetiapine

Quetiapine fumarate ('Seroquel') is a newly introduced atypical antipsychotic with demonstrated efficacy in the treatment of positive and negative symptoms of schizophrenia. It is extensively metabolized, predominantly by cytochrome P450 3A4. Therefore, concurrent administration of drugs that induce or inhibit this enzyme may affect quetiapine pharmacokinetics. This study demonstrated that the potent cytochrome P450 enzyme-inducer phenytoin did indeed have a marked effect on the metabolism of quetiapine, resulting in a 5-fold increase in clearance when administered concomitantly to patients with DSM-IV-diagnosed schizophrenia, schizoaffective disorder, or bipolar disorder. These results indicate that dosage adjustment of quetiapine may be necessary when the two drugs are given concurrently and that caution may be required when administering other drugs that inhibit or induce cytochromes, particularly P450 3A4.

The stability of cytokeratin 18 in human liver cells during colchicine-induced microtubule disruption

The cytoskeleton plays important roles in cell function and is therefore implicated in the pathogenesis of many human liver diseases, including malignant tumors. The stability of cytokeratin proteins during tumor transformation in human hepatocellular carcinoma has been studied with a molecular approach previously. The results demonstrate that the cytokeratin is modulated in human hepatocellular carcinoma. Besides this, three low molecular weight cytokeratin molecules (named HCC CK) are found. This indicates that these HCC CKs have undergone modulation from the human hepatocyte cytokeratin 18. We also checked the cytokeratin profile of the human hepatoma cell line PLC/PRF/5 with the same methods to ensure the HCC CK molecules are produced by modulation but not protein degradation. The stability of cytokeratin molecules was studied by a different approach. The cytokeratin compositions of human liver cells (Chang cell line) were analysed under the effects of microtubule-disrupting drug (colchicine) by SDS-PAGE, Western blot, immunoprecipitation using a commercially available monoclonal anti-cytokeratin 18 antibody and immunofluorescent staining. Within 1 h of treatment, the microtubule began to collapse and the filamentous structure was shortening. The microtubule had almost collapsed and became fragmented to form a lattice-like network after 24 h of treatment. The cytokeratin was modulated after long-term (24 h) treatment of colchicine, and the molecular weight became 14 kD and the antigenicity was lost. The stability of cytokeratin molecules was related to the intact microtubule network, after disruption of the microtubule the cytokeratin would be modulated. The intact microtubule network was a stabilizing factor of cytokeratin 18 in human liver cells.

Translational upregulation of X-linked inhibitor of apoptosis (XIAP) increases resistance to radiation induced cell death

Inhibitory regulators of apoptosis play a critical role in the responsiveness of tumour cells to cytotoxic agents. The X-linked inhibitor of apoptosis protein (XIAP) is a member of a novel family of Inhibitor of Apoptosis (IAP) proteins. Here we show that acute low dose ionizing irradiation results in the translational upregulation of XIAP that correlates with an increased resistance to radiation in non-small cell lung carcinoma. This upregulation is mediated by an internal ribosome binding mechanism via an IRES element located within a XIAP 5' UTR. Transient overexpression of XIAP rendered human carcinoma cells resistant to low dose gamma-irradiation. By contrast, the antisense targeting of XIAP resulted in increased cell death following irradiation advocating a distinct role for XIAP in radiation resistant phenotype of human cancers. Oncogene (2000) 19, 4174 - 4177

Single-dose pharmacokinetics of quetiapine in subjects with renal or hepatic impairment

1. The atypical antipsychotic quetiapine ('Seroquel') provides equivalent efficacy to the typical antipsychotics chlorpromazine and haloperidol in the short-term treatment of schizophrenia. Moreover, the incidence of extrapyramidal symptoms associated with quetiapine treatment is equivalent to that observed with placebo treatment, which may lead to increased patient compliance with quetiapine compared with typical antipsychotics. 2. This report presents the results from two small studies aimed at determining the pharmacokinetics of quetiapine in nonpsychotic subjects with renal or hepatic impairment. Equal numbers of impaired subjects and healthy control subjects were administered a single, 25 mg dose of quetiapine, and plasma concentrations were determined up to 48 hr after dosing. 3. No clinically significant differences were found when the pharmacokinetic parameters for subjects with renal or hepatic impairment were compared with those for healthy control subjects. The results indicate that dosage adjustment of quetiapine may be unnecessary in psychotic patients with decreased renal function. 4. In subjects with hepatic impairment related to alcoholic cirrhosis, the results suggest that no change is needed in the recommended quetiapine starting dose (25 mg). However, because of a noted inter-subject variability in the clearance of quetiapine in the cirrhotic group, it is recommended that dose escalation be performed with caution in patients with hepatic impairment. 5. The single dose of quetiapine 25 mg generally was well tolerated in nonpsychotic subjects in good health or with either renal or hepatic impairments. Quetiapine also had no effect on the endogenous creatinine clearance of renally impaired or healthy control subjects.

Pharmacokinetics, tolerability, and clinical effectiveness of quetiapine fumarate: an open-label trial in adolescents with psychotic disorders

BACKGROUND

This is the first investigation of the pharmacokinetics, tolerability, and efficacy of quetiapine fumarate in adolescents with chronic or intermittent psychotic disorders.

METHOD

Ten patients with DSM-IV chronic or intermittent psychotic disorders (ages 12.3 through 15.9 years) participated in an open-label, rising-dose trial and received oral doses of quetiapine twice daily (b.i.d.), starting at 25 mg b.i.d. and reaching 400 mg b.i.d. by day 20. The trial ended on day 23. Key assessments were pharmacokinetic analysis of plasma quetiapine concentrations and neurologic, safety, and efficacy evaluations.

RESULTS

No statistically significant differences were observed between 100-mg b.i.d. and 400-mg b.i.d. quetiapine regimens for total body clearance, dose-normalized area under the plasma concentration-time curve, or dose-normalized premorning- or postmorning-dose trough plasma values obtained under steady-state conditions after multiple-dose regimens. No unexpected side effects occurred with quetiapine therapy, and no statistically significant changes from baseline were observed for the UKU Side Effect Rating Scale items that were rated. No serious adverse events or clinically important changes in hematology or clinical chemistry variables were reported. The most common adverse events were postural tachycardia and insomnia. Extrapyramidal side effects improved, as evidenced by significant (p < .05) decreases from baseline to endpoint in the mean Simpson-Angus Scale total scores and Barnes Akathisia Scale scores. Quetiapine improved positive and negative symptoms, as shown by significant (p < .05) decreases from baseline to endpoint in the mean Brief Psychiatric Rating Scale total score, the Clinical Global Impressions-Severity of Illness scale, and the Modified Scale for the Assessment of Negative Symptoms summary score.

CONCLUSION

Quetiapine pharmacokinetics were dose proportional in adolescents and were similar to those previously reported for adults. Quetiapine was well tolerated and effective in the small number of adolescents studied.

Phosphine-induced oxidative damage in rats: attenuation by melatonin

Phosphine (PH(3)), from hydrolysis of aluminum, magnesium and zinc phosphide, is an insecticide and rodenticide. Earlier observations on PH(3)-poisoned insects, mammals and a mammalian cell line led to the proposed involvement of oxidative damage in the toxic mechanism. This investigation focused on PH(3)-induced oxidative damage in rats and antioxidants as candidate protective agents. Male Wistar rats were treated ip with PH(3) at 2 mg/kg. Thirty min later the brain, liver, and lung were analyzed for glutathione (GSH) levels and lipid peroxidation (as malondialdehyde and 4-hydroxyalkenals) and brain and lung for 8-hydroxydeoxyguanosine (8-OH-dGuo) in DNA. PH(3) caused a significant decrease in GSH concentration and elevation in lipid peroxidation in brain (36-42%), lung (32-38%) and liver (19-25%) and significant increase of 8-OH-dGuo in DNA of brain (70%) and liver (39%). Antioxidants administered ip 30 min before PH(3) were melatonin, vitamin C, and beta-carotene at 10, 30, and 6 mg/kg, respectively. The PH(3)-induced changes were significantly or completely blocked by melatonin while vitamin C and beta-carotene were less effective or inactive. These findings establish that PH(3) induces and melatonin protects against oxidative damage in the brain, lung and liver of rats and suggest the involvement of reactive oxygen species in the genotoxicity of PH(3).

Existence of optical solitons on wavelength division multiplexed beams in a nonlinear fiber

A simple analytic expression for the initial fundamental optical solitons on wavelength division multiplexed (WDM) beams in a nonlinear fiber has been found. For an ideal fiber with no loss and uniform group-velocity dispersion (GVD) in the anomalous GVD region, the initial form is [1+2(M-1)](-1/2) sech(tau), where M is the number of WDM beams and tau is the normalized time. Computer simulation shows that these initial pulses on WDM beams in this fiber will propagate undistorted without change in their shapes for arbitrarily long distances. The discovery of the existence of solitons on WDM beams presents the ultimate goal for optical fiber communication on multiple wavelength beams in a single fiber.