12S-hydroxyeicosatetraenoic acid levels link to coronary artery disease in Type 2 diabetic patients

BACKGROUND

12(S)-Hydroxyeicosatetraenoic acid (12(S)-HETE) is a metabolite of arachidonic acid. 12(S)-HETE is involved in the pathogenesis of atherosclerosis and diabetes. However, the correlation between 12(S)-HETE and coronary artery disease (CAD) in the diabetic patient is unclear.

AIMS

The study investigated the relationship between 12(S)-HETE and CAD in Type 2 diabetes (T2D).

METHODS

Plasma 12(S)- HETE levels were detected by enzyme-linked immunosorbent assay in 103 healthy controls (control), 109 diabetic patients without CAD (diabetic), and 152 diabetic patients with CAD (diabetic-CAD).

RESULTS

12(S)-HETE levels were higher in both diabetic and diabetic-CAD groups compared to control and in the diabetic-CAD group compared to the diabetic group. In the multiple linear stepwise regression analysis, 12(S)-HETE levels correlated independently with CAD, systolic blood pressure, and glycated hemoglobin.

CONCLUSIONS

These results indicate that 12(S)-HETE levels are increased in diabetic patients with CAD, suggesting a role for atherosclerosis in T2D.

Histidine supplementation improves insulin resistance through suppressed inflammation in obese women with the metabolic syndrome: a randomised controlled trial

AIMS/HYPOTHESIS

Increased inflammation and oxidative stress are associated with insulin resistance (IR) and metabolic disorders. Serum histidine levels are lower and are negatively associated with inflammation and oxidative stress in obese women. The objective of this study was to evaluate the efficacy of histidine supplementation on IR, inflammation, oxidative stress and metabolic disorders in obese women with the metabolic syndrome (MetS).

METHODS

A total of 100 obese women aged 33-51 years with BMI ≥ 28 kg/m² and diagnosed with MetS were included following a health examination in the community hospital in this randomised, double-blinded, placebo-controlled trial. Participants were allocated to interventions by an investigator using sequentially numbered sealed envelopes and received 4 g/day histidine (n = 50) or identical placebo (n = 50) for 12 weeks. Participants then attended the same clinic every 2 weeks for scheduled interviews and to count tablets returned. Serum histidine, HOMA-IR, BMI, waist circumference, fat mass, serum NEFA, and variables connected to inflammation and oxidative stress were measured at baseline and 12 weeks. Participants, examining physicians and investigators assessing the outcomes were blinded to group assignment. In addition, the inflammatory mechanisms of histidine were also explored in adipocytes.

RESULTS

At 12 weeks, a total of 92 participants completed this trail. Compared with the placebo group (n = 47), histidine supplementation significantly decreased HOMA-IR (-1.09 [95% CI -1.49, -0.68]), BMI (-0.86 kg/m² [95% CI -1.55, -0.17]), waist circumference (-2.86 cm [95% CI -3.86, -1.86]), fat mass (-2.71 kg [95% CI -3.69, -1.73]), serum NEFA (-173.26 μmol/l [95% CI -208.57, -137.94]), serum inflammatory cytokines (TNF-α, -3.96 pg/ml [95% CI -5.29, -2.62]; IL-6, -2.15 pg/ml [95% CI -2.52, -1.78]), oxidative stress (superoxide dismutase, 17.84 U/ml [95% CI 15.03, 20.65]; glutathione peroxidase, 13.71 nmol/ml [95% CI 9.65, 17.78]) and increased serum histidine and adiponectin by 18.23 μmol/l [95% CI 11.74, 24.71] and 2.02 ng/ml [95% CI 0.60, 3.44] in histidine supplementation group (n = 45), respectively. There were significant correlations between changes in serum histidine and changes of IR and its risk factors. No side effects were observed during the intervention. In vitro study indicated that histidine suppresses IL6 and TNF mRNA expression and nuclear factor kappa-B (NF-κB) protein production in palmitic acid-induced adipocytes in a dose-dependent manner, and these changes were diminished by an inhibitor of NF-κB.

CONCLUSIONS/INTERPRETATION

Histidine supplementation could improve IR, reduce BMI, fat mass and NEFA and suppress inflammation and oxidative stress in obese women with MetS; histidine could improve IR through suppressed pro-inflammatory cytokine expression, possibly by the NF-κB pathway, in adipocytes.

Multidetector computed tomography (MDCT) manifestations of the normal duodenal papilla

OBJECTIVE

This study aimed to investigate Multidetector Computed Tomography (MDCT) manifestations of the normal duodenal papilla, thereby improving the knowledge on the CT manifestations of the normal anatomy of the duodenal papilla.

METHODS

A retrospective study was conducted by reviewing the CT results of 70 normal duodenal papilla cases examined by 64-MDCT. The analysis particularly focused on the position, size, morphology, and enhancement pattern of the duodenal papilla, as well as the ampulla of Vater.

RESULTS

In axial images, the average base diameter of the duodenal papilla was (7.3 ± 1.4)mm, whereas the average height was (6.5 ± 1.8)mm. Majority of the duodenal papilla (52.9%, 37/70) showed a round shape. In most cases (97.1%, 68/70), the duodenal papilla were located at the middle and lower third of the descending duodenum. In 84.3% of the cases (59/70), the arterial phase enhanced CT scan images were optimal for the visualization of the papilla. The "target sign" could be clearly identified from arterial phase images in 71.4% (50/70) of the cases. In 72.9% (51/70) of the cases, the ampulla of Vater had a common channel (Y type).

CONCLUSION

64-MDCT can clearly visualize the normal anatomy of the duodenal papilla and surrounding structures, thereby providing valuable information for the diagnosis and treatment of diseases in this region.

[Pilot study on MRI of human colon adenocarcinoma cells labeled with superparamagnetic iron oxide in vitro]

OBJECTIVE

To study the feasibility of MRI of human colon adenocarcinoma cell line (Lovo) labeled with superparamagnetic iron oxide(SPIO) nanoparticles in vitro.

METHODS

Lovo cells (5 × 10(5) and 1 × 10(6)) were cultured in medium containing different SPIO nanoparticles (50 microl and 500 microl). Transmission electron microscopy was used to observe cellular ultrastructure and to determine the uptake and distribution of particles in Lovo cells at 1-, 3-, 6-hours. MRI of Lovo cells was performed with T1WI, T2WI sequences. Unlabeled cells were used as controls.

RESULTS

Uptake of SPIO nanoparticles occurred within 6 hours. On T1 weighted imaging, there was no significant difference in signal intensity between the experimental groups and the control group. On T2 weighted imaging, there was no significant difference in signal intensity between the experimental groups and the control group after culture of 1 h. Signal intensity began to decrease in 1 × 10(6) Lovo cells labeled with 500 microl SPIO nanoparticle after 3 hours culture. Signal intensity decreased in all the experimental groups after 6 hours culture.

CONCLUSION

Human colon adenocarcinoma cell line (Lovo) can be labeled with SPIO nanoparticles, and the labeled cells can be imaged with MRI equipment.

CT and MR imaging characteristics of infantile hepatic hemangioendothelioma

AIM

This study aims to analyze computed tomography (CT) and magnetic resonance (MR) imaging features of infantile hepatic hemangioendotheliomas before and after treatment.

MATERIALS AND METHODS

CT and MR examinations of seven infants with biopsy proven hepatic hemangioendotheliomas were retrospectively analyzed. The distribution, number, size, imaging appearance, enhancement pattern and post-treatment changes of the tumors were evaluated.

RESULTS

A total of 153 hepatic hemangioendotheliomas were detected on CT (111) and MR (42) imaging. In six infants, 109/111 (98.2%) tumors were hypodense and 2/111 (1.8%) lesions contained calcification on unenhanced CT. On MR imaging, all 42 lesions in one infant were heterogeneously T1-hypointense and T2-hyperintense compared to the normal liver parenchyma. Contrast-enhanced CT and MRI showed peripheral rim (51.6%), uniform (48.4%), fibrillary (33.3%), and nodular (28.8%) contrast enhancement in the hepatic arterial phase. Homogeneous (100%), rim (98.2%) and mixed enhancement patterns were noted in tumors <1.0cm, >2.0cm and 1.0-2.0cm in diameter respectively in the hepatic arterial phase. In three patients who underwent steroid therapy, follow-up CT examination demonstrated tumor size reduction and increased intra-tumoral calcification in two patients.

CONCLUSION

Infantile hepatic hemangioendotheliomas show some typical imaging features and size-dependent pattern of contrast enhancement on CT and MR imaging, which allow accurate imaging diagnosis and post-treatment evaluation.

Multiphasic MDCT in small bowel volvulus

OBJECTIVE

Evaluate the use of MDCT with 3D CT angiography (CTA) and CT portal venography (CTPV) reconstruction for the diagnosis of small bowel volvulus (SBV).

METHODS

Multiphasic MDCT findings in nine patients (seven males and two females, age range 2-70) with surgically proven SBV were retrospectively reviewed. Non-contrast and double phase contrast enhanced MDCT including 3D CTA and CTPV reconstruction were performed in all the patients. Two experienced abdominal radiologists evaluated the images and defined the location, direction and degree of SBV.

RESULTS

On axial MDCT images, all cases show segmental or global dilatation of small intestine. Other findings include circumferential bowel wall thickening in eight cases, halo appearance and hyperemia in seven cases, whirl sign in six cases, beak-like appearance in six cases, closed loops in six cases and ascites in one case. CTA/CTPV showed abnormal courses involving main trunks of superior mesenteric artery (SMA) and superior mesenteric vein (SMV) in seven cases, with or without distortion of their tributaries. Normal course of SMA but abnormal course of SMV was seen in the other two cases. Of all the nine cases, whirl sign was seen in six cases and barber's pole sign in five cases. Dilated SMV was observed in eight cases and abrupt termination of SMA was found in one case. Compared with surgical findings, the location, direction and degree of SBV were correctly estimated in all cases based on CTA/CTPV.

CONCLUSION

Multiphasic MDCT with CTA/CTPV reconstruction can play an important role in the diagnosis of SBV. The location, direction and degree of SBV can all be defined preoperatively using this method.

The effect of Fe doping on adsorption of CO2/N2 within carbon nanotubes: a density functional theory study with dispersion corrections

An ab initio density functional theory (DFT) study with correction for dispersive interactions was performed to study the adsorption of N(2) and CO(2) inside an (8, 8) single-walled carbon nanotube. We find that the approach of combining DFT and van der Waals correction is very effective for describing the long-range interaction between N(2)/CO(2) and the carbon nanotube (CNT). Surprisingly, exohedral doping of an Fe atom onto the CNT surface will only affect the adsorption energy of the quadrupolar CO(2) molecule inside the CNT (20-30%), and not that of molecular N(2). Our results suggest the feasibility of enhancement of CO(2)/N(2) separation in CNT-based membranes by using exohedral doping of metal atoms.

First principle study of hydrogenation of MgB2: an important step toward reversible hydrogen storage in the coupled LiBH4/MgH2 system

Recent experiments [F. E. Pinkerton, M. S. Meyer, G. P. Meisner, M. P. Balogh, and J. J. Vajo, J. Phys. Chem. C 111, 12881 (2007) and J. J. Vajo and G. L. Olson, Scripta Mater. 56, 829 (2007)] demonstrated that the recycling of hydrogen in the coupled LiBH4/MgH2 system is fully reversible. The rehydrogenation of MgB2 is an important step toward the reversibility. By using ab initio density functional theory calculations, we found that the activation barrier for the dissociation of H2 are 0.49 and 0.58 eV for the B and Mg-terminated MgB2(0001) surface, respectively. This implies that the dissociation kinetics of H2 on a MgB2(0001) surface should be greatly improved compared to that in pure Mg materials. Additionally, the diffusion of dissociated H atom on the Mg-terminated MgB2(0001) surface is almost barrier-less. Our results shed light on the experimentally-observed reversibility and improved kinetics for the coupled LiBH4/MgH2 system.

Evaluation of angiogenesis in colorectal carcinoma with multidetector-row CT multislice perfusion imaging

To evaluate the correlation between 64 multidetector-row CT (64MDCT) perfusion imaging in colorectal carcinoma and microvessel density (MVD) and vascular endothelial growth factor (VEGF), 64MDCT perfusion imaging was performed in 33 patients with pathologically verified colorectal carcinoma. These images were analyzed with perfusion functional software, and time-density curves (TDC) were created for the region of interest (ROI) encompassing the tumor, the target artery and vein. The individual perfusion maps generated indicated blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability-surface area product (PS). MVD and VEGF were evaluated by immunohistochemical staining with anti-CD34 and anti-VEGF, respectively. Correlations between MVD or VEGF with CT perfusion parameters and clinicopathological factors (Dukes' stages, invasion depth, and lymph node and liver metastasis) were also investigated. MVD in the colorectal carcinoma was 22.61+/-9.01 per x200 field. The scores obtained for VEGF expression were 4.15+/-1.09. VEGF staining was positive in 25 of 29 tumors (86.2%). There was no significant correlation between the presence of MVD, VEGF expression and clinicopathological factors (P>0.05). There was also no correlation between MVD, VEGF expression, and any dynamic CT parameters (P>0.05). The BV and MTT were significantly higher in tumors demonstrating serous coat invasion than in those without it (t=-2.63, -2.24, P=0.0137, 0.0331, respectively). BV was also significantly correlated with tumor size (r=0.41, P=0.02). Neither BF nor PS was correlated with clinicopathological factors. In conclusion, 64MDCT perfusion imaging, MVD, and VEGF may reflect angiogenic activity, but no significant correlation among these factors.

Assessment of spiral CT pneumocolon in preoperative colorectal carcinoma

AIM: To investigate the value of spiral CT pneumocolon in preoperative colorectal carcinoma.

METHODS: Spiral CT pneumocolon was performed prior to surgery in 64 patients with colorectal carcinoma. Spiral CT images were compared to specimens from the resected tumor.

RESULTS: Spiral CT depicted the tumor in all patients. Comparison of spiral CT and histologic results showed that the sensitivity and specificity were 95.2%, 40.9% in detection of local invasion, and 75.0%, 90.9% in detection of lymph node metastasis. Compared to the Dukes classification, the disease was correctly staged as A in 6 of 18 patients, as B in 18 of 23, as C in 10 of 15, and as D in 7 of 8. Overall, spiral CT correctly staged 64.1% of patients.

CONCLUSION: Spiral CT pneumocolon may be useful in the preoperative assessment of patients with colorectal carcinoma as a means for assisting surgical planning.

Stability of Supershort Single-Walled Carbon Nanotubes

How short can single-walled carbon nanotubes (SWNTs) be? How stable are such supershort SWNTs (ss-SWNTs)? This work is the first to address these questions. On the basis of binding energy (E(B)), standard heats of formation , and strain energy (E(S)), we found that SWNTs with only one benzene ring in the axial direction, which we refer to as supershort SWNTs (ss-SWNTs), can be thermodynamically stable. On the basis of the data of E(B), , and E(S), the relative stabilities of ss-SWNTs, fullerenes, polycyclic aromatic hydrocarbons, and butadiyne are discussed. This study has laid a theoretical foundation for the possible synthesis of ss-SWNTs.

Tumor angiogenesis and dynamic CT in colorectal carcinoma: Radiologic-pathologic correlation

AIM: To investigate the correlation between microvessel density and spiral CT perfusion imaging in colorectal carcinoma.

METHODS: Thirty-seven patients, with histologically proven colorectal carcinoma, underwent water enema spiral CT scan. The largest axial surface of the primary tumor was searched on unenhanced spiral CT images. At this level, the enhanced dynamic scan series was acquired. Time-density curves (TDC) were created from the region of interest drawn over the tumor, target artery by Toshiba Xpress/SX spiral CT with perfusion functional software. Then the perfusion was calculated. Microvessel density (MVD) was evaluated using immunohistochemical staining of surgical specimens with anti-CD34, and then MVD was correlated with perfusion.

RESULTS: MVD of colorectal carcinomas was 33.11-173.44, mean 87.28, and perfusion was 15.60-64.80 mL/min/ 100 g, mean 39.74 mL/min/100 g. MVD and perfusion were not associated with invasive depth, metastasis and disease stage, and they all decreased with increasing Dukes’ stage, but no significant correlation was found between them (r = 0.18, P = 0.29).

CONCLUSION: There is no significant correlation between MVD and perfusion. Neovascularizaton and perfusion are highly presented in early colorectal carcinoma. CT perfusion imaging may be more suited for assessing tumorigenesis in colorectal carcinoma than histological MVD technique.

Development of a novel indwelling balloon applicator for optimizing light delivery in photodynamic therapy

BACKGROUND AND OBJECTIVE

A human glioma spheroid model is used to investigate the efficacy of different light delivery schemes in 5-aminolevulinic acid (ALA)--mediated photodynamic therapy (PDT). The results provide the rationale for the development of an indwelling balloon applicator for optimizing light delivery.

STUDY DESIGN/MATERIALS AND METHODS

Human glioma spheroids were incubated in ALA (100 or 1000 microg /ml-1) for 4 hours and subjected to various light irradiation schemes. In one set of experiments, spheroid survival was monitored as a function of light fluence rate (5-200 mW cm-2). In all cases, spheroids were exposed to fluences of either 25 or 50 J cm-2. In a second study, the effects of repeated weekly PDT treatments, using sub-threshold fluences, were investigated. One group of spheroids was subjected to three treatments using fluences of 12, 12, and 25 J cm-2. Results were compared to spheroids receiving single treatments of either 12 or 25 J cm-2. A fluence rate of 25 mW cm-2 was used for all three groups of spheroids. In all cases, the effect of a given irradiation scheme was evaluated by monitoring spheroid growth.

RESULTS

Low fluence rates produce greater cell kill than high fluence rates. The minimum effective fluence rate in human glioma spheroids is approximately 10 mW cm-2. Repeated weekly PDT treatments with sub-threshold fluences result in significant cell kill. In spheroids surviving the PDT treatments, growth is suppressed for the duration of the treatment period.

CONCLUSION

The results of the in vitro studies support the development of an indwelling balloon applicator for the delivery of light doses in long term multi-fractionated PDT regimens.

[Bioequivalence of bambuteral and its metabolites terbutaline after oral bambuteral tablet in healthy volunteers by HPLC/MS]

AIM

To study bioequivalence of bambuteral and its metablites terbutaline in 20 healthy male volunteers.

METHODS

A single oral dose of domestic or imported bambuteral tablet was given according to a randomized 2-way cross-over design. The plasma bambuteral and terbutaline concentrations were determined by HPLC/MS.

RESULTS

The pharmacokinetic parameters of domestic and imported bambuteral: AUC0-t were (52 +/- 21) microgram.h.L-1 and (51 +/- 20) microgram.h.L-1, Tmax were (2.9 +/- 0.9) h and (2.6 +/- 0.7) h, Cmax were (6.0 +/- 2.6) microgram.L-1 and (6.2 +/- 2.9) microgram.L-1, T1/2Ke were (11.2 +/- 2.3) h and (11.2 +/- 1.9) h, respectively; terbutaline: AUC0-t were (191 +/- 30) microgram.h.L-1 and (197 +/- 37) microgram.h.L-1; Tmax were (4.2 +/- 1.0) h and (4.2 +/- 1.0) h; Cmax were (10 +/- 5) microgram.L-1 and (10 +/- 4) microgram.L-1; T1/2Ke were (20 +/- 3) h and (21 +/- 4) h, respectively. The bioavaiability of the domestics was 102% +/- 8% (bambuteral) and 100% +/- 12% (terbutaline).

CONCLUSION

The results demonstrate that the two forms of bambuteral and terbutaline were bioequivalent by analysis of variance, two-one sided test and 90% confidential limit.

Two-photon laser scanning microscopy of epithelial cell-modulated collagen density in engineered human lung tissue

Tissue remodeling is a complex process that can occur in response to a wound or injury. In lung tissue, abnormal remodeling can lead to permanent structural changes that are characteristic of important lung diseases such as interstitial pulmonary fibrosis and bronchial asthma. Fibroblast-mediated contraction of three-dimensional collagen gels is considered an in vitro model of tissue contraction and remodeling, and the epithelium is one factor thought to modulate this process. We studied the effects of epithelium on collagen density and contraction using two-photon laser scanning microscopy (TPLSM). TPLSM was used to image autofluorescence of collagen fibers in an engineered tissue model of the human respiratory mucosa -- a three-dimensional co-culture of human lung fibroblasts (CCD-18 lu), denatured type I collagen, and a monolayer of human alveolar epithelial cell line (A549) or human bronchial epithelial cell line (16HBE14o(-)). Tissues were imaged at days 1, 8, and 15 at 10 depths within the tissue. Gel contraction was measured concurrently with TPLSM imaging. Image analysis shows that gels without an epithelium had the fastest rate of decay of fluorescent signal, corresponding to highest collagen density. Results of the gel contraction assay show that gels without an epithelium also had the highest degree of contraction (19.8% +/- 4.0%). We conclude that epithelial cells modulate collagen density and contraction of engineered human lung tissue, and TPLSM is an effective tool to investigate this phenomenon.

The porcine and lagomorph septal cartilages: models for tissue engineering and morphologic cartilage research

Interest in reconstruction and modification of the facial cartilaginous frameworks using advanced technology and instrumentation is growing rapidly. Despite this maturing interest, no animal model has been established to provide morphologic cartilage tissue with similar characteristics to human septum in suitable quantities. The objective of this study was to characterize porcine and lagomorph (rabbit) nasal septal cartilage tissue. Both models share great similarity with their human counterpart and provide a low-cost, high-volume, and easily obtained source of bulk cartilage tissue. We present a technique for harvesting intact septal cartilages from these species, and characterize select cellular, metabolic, and physical properties using pulse-chase radiolabeling, flow cytometry, and mechanical analysis. Our selective evaluation of key tissue properties establishes these species as appropriate animal models for nasal septal cartilaginous surgery.

Photodynamic therapy of human glioma spheroids using 5-aminolevulinic acid

The response of human glioma spheroids to 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) is investigated. A two-photon fluorescence microscopy technique is used to show that human glioma cells readily convert ALA to protoporphyrin IX throughout the entire spheroid volume. The central finding of this study is that the response of human glioma spheroids to ALA-mediated PDT depends not only on the total fluence, but also on the rate at which the fluence is delivered. At low fluences (< or = 50 J cm-2), lower fluence rates are more effective. At a fluence of 50 J cm-2, near-total spheroid kill is observed at fluence rates of as low as 10 mW cm-2. The fluence rate effect is not as pronounced at higher fluences (> 50 J cm-2), where a favorable response is observed throughout the range of fluence rates investigated. The clinical implications of these findings are discussed.

Photodynamic therapy of human glioma spheroids using 5-aminolevulinic acid

The response of human glioma spheroids to 5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) is investigated. A two-photon fluorescence microscopy technique is used to show that human glioma cells readily convert ALA to protoporphyrin IX throughout the entire spheroid volume. The central finding of this study is that the response of human glioma spheroids to ALA-mediated PDT depends not only on the total fluence, but also on the rate at which the fluence is delivered. At low fluences (< or = 50 J cm-2), lower fluence rates are more effective. At a fluence of 50 J cm-2, near-total spheroid kill is observed at fluence rates of as low as 10 mW cm-2. The fluence rate effect is not as pronounced at higher fluences (> 50 J cm-2), where a favorable response is observed throughout the range of fluence rates investigated. The clinical implications of these findings are discussed.

In vitro and in vivo comparison of argon-pumped and diode lasers for photodynamic therapy using second-generation photosensitizers

BACKGROUND AND OBJECTIVE

Three prototype microchannel-cooled stacked diode array lasers were compared with the currently used conventional argon ion laser-pumped tunable dye lasers for suitability as light sources in photodynamic therapy (PDT) treatment.

STUDY DESIGN/MATERIALS AND METHODS

The PDT response of Chinese hamster ovary (CHO-K1) cells in culture and SMT-F tumor bearing mice treated with chloro-aluminum sulfonated phthalocyanin (CASPc), benzoporphyrin derivative mono-acid (BPD-MA), and lutetium texaphyrin (Lutex) was determined using each laser light source. Survival of the CHO cells was measured using a cloning assay. Tumor regression/eradication was used to assess response in the mice.

RESULTS

Both sources of laser light produced comparable PDT responses in the two systems tested.

CONCLUSION

It would be possible to replace the currently used argon ion laser-pumped dye laser systems with the diode lasers tested.

In vitro and in vivo photosensitizing capabilities of 5-ALA versus photofrin in vascular endothelial cells

BACKGROUND AND OBJECTIVE

The objective of the present study was to evaluate the feasibility of photodynamic therapy (PDT) for complicated hemangiomas. The photosensitizing activities of 5-aminolevulinic acid (5-ALA) and Photofrin were evaluated in vitro with human dermal microvascular endothelial cells (MEC) and in vivo with the chicken cox comb.

STUDY DESIGN/MATERIALS AND METHODS

The in vitro absorption and photosensitizing activities of 5-ALA and Photofrin were examined in a MEC culture system. The percentages of MEC killed by different drug concentrations at a wavelength of 630 nm were measured by either live/dead or lactate dehydrogenase-released assays. Similarly, the in vivo biological activities of 5-ALA and Photofrin exposed to different total light dosages at 630 nm were studied by determining the amount of necrosis produced in chicken combs.

RESULTS

MEC incubated with 5-ALA at a concentration of 35 microg/ml and exposed to laser light at 630 nm at a power density of 100 mW/cm2 showed a 50% cell kill. MEC incubated with Photofrin at a concentration of 3.5 microg/ml and exposed to laser light at 630 nm at a power density of 100 mW/cm2 showed a 50% cell kill. Chicken combs that received 200 mg/kg of 5-ALA exposed to laser light at 630 nm at a power density of 100 mW/cm2 had an injury depth of 362.5+/-27.6 microm at histologic examination. Combs exposed to a power density of 100 or 120 mW/cm2 showed injury depths of 732.5+/-29.1 and 792.5+/-36.0 microm, respectively. Chicken combs that received 2.5 mg/kg of Photofrin exposed to laser light at 630 nm at a power density of 80 mW/cm2 had an injury depth of 535.6+/-22.3 microm at histologic examination. Combs exposed to a power density of 100 or 120 mW/cm2 showed injury depths of 795.8+/-32.5 and 805.2+/-49.1 microm, respectively.

CONCLUSION

Both 5-ALA and Photofrin have the capability to destroy MEC in vitro and vasculature in vivo. However, Photofrin achieved a higher degree of cell kill and tissue destruction at lower drug concentrations and at lower power densities.

Ephrins stimulate or inhibit neurite outgrowth and survival as a function of neuronal cell type

The Eph family of tyrosine kinase receptors and ligands play key roles in cell segregation and axon targeting in the developing nervous system. Interactions between the ligands and receptors cause repulsion or degeneration of receptor-positive axons from several brain regions including the retina, hippocampus, thalamus, and midbrain dopaminergic system. We extend these previous observations by showing that three A-ephrins also negatively regulate the growth of neurites from striatal and olfactory neurons. In addition to negative effects, however, we also report a trophic activity of the A-ephrins: Ephrin-A2 and A5 promote survival and neurite outgrowth of sympathetic neurons. These observations provide support to the notion that ephrins may function as either negative or positive signals in the developing nervous system.

Proteoglycan synthesis in porcine nasal cartilage grafts following Nd:YAG (lambda = 1.32 microns) laser-mediated reshaping

Mechanically deformed morphologic cartilage grafts undergo temperature-dependent stress relaxation during sustained laser irradiation resulting in stable shape changes. In this study, porcine nasal septal cartilage specimens were evaluated for viability by measuring the incorporation of Na2(35)SO4 into proteoglycan (PTG) macromolecules in whole tissue culture following laser-mediated reshaping. Synthesis rates of PTG were determined by scintillation counting lyophilized specimens and normalizing these values by total protein content. Positive controls were established by inducing chondrocyte apoptosis using prolonged exposure to nitric oxide (NO). In chondrocytes, apoptosis induced using NO resulted in significantly lower PTG synthesis rates compared to untreated native specimens. Cartilage specimens were irradiated with light emitted from a Nd:YAG laser (25 W/cm2, lambda = 1.32 microns) while recording simultaneously radiometric surface temperature, internal stress and back-scattered light intensity from a probe laser. Each specimen received one, two or three sequential laser exposures. The duration of each exposure was determined from real-time measurements of characteristic changes in back-scattered light intensity that correlate with accelerated stress relaxation. A 5 min time interval between each laser exposures allowed the cartilage specimen to return to thermal equilibrium. Average PTG synthesis rates decreased with successive laser exposures, though these were always higher than baseline rates established for NO-treated tissues, suggesting that laser-mediated cartilage reshaping acutely does not eliminate the entire population of viable chondrocytes. The reduction in PTG synthesis is correlated with the time-temperature-dependent heating profile created during laser irradiation, supporting our hypothesis that careful monitoring of laser dosimetry is required to ensure chondrocyte viability.

Development of a tetracycline controlled gene expression system in the parasitic protozoan Giardia lamblia

Giardia lamblia is a very common intestinal protozoan pathogen of humans. Recent development of gene transfection systems in G. lamblia has allowed constitutive expression of selected genes in the organism. To extend the uses of DNA transfection in G. lamblia, an inducible gene expression system was developed by integrating the bacterial tet operator-repressor elements into an episomal DNA transfection vector. Tetracycline-responsive promoters with insertions of multiple tet operator sequences in the vicinity of a synthetic ran promoter were tested for their inducibility of a luciferase reporter gene expression. Stable cell lines transfected with individual plasmid constructs were established under drug selection. By assaying luciferase activity in transfected cells in response to tetracycline, an inducible promoter with insertion of two tet operators downstream of the adjacent synthetic ran promoter was found to confer a 10-fold inducibility in gene expression with co-expression of the tet-repressor driven by a gdh promoter. To further improve its inducibility, several other synthetic promoter contexts were also tested to increase expression of the tet-repressor gene. An optimal inducibility of 50-fold was obtained when a synthetic alpha-giardin promoter was used. Fine tuning of luciferase expression was achieved by adjusting the concentration of tetracycline and duration of drug exposure. The inducible gene expression system provides us an easy way to manipulate the level of gene expression in G. lamblia in a controllable manner that could not previously be achieved.

Identification and characterization of a ran gene promoter in the protozoan pathogen Giardia lamblia

The promoter elements that regulate transcription initiation in Giardia lamblia are poorly understood. In this report, the promoter of the Giardia ran gene was studied using a luciferase expression plasmid pRANluc+ to monitor transcription efficiency. An AT-rich sequence spanning -51/-20 relative to the translation start site of the ran gene was identified and was found to be required for efficient luciferase expression by deletion and mutation mapping of pRANluc+. The -51/-20 sequence was also sufficient for promoter activity as revealed from studies on a 32-base pair synthetic promoter derived from this region. Deletion mapping of the synthetic promoter revealed two minimal promoter elements, -51/-42 and -30/-20, sufficient for 6- and 30-fold luciferase expression above background, respectively. The transcription start sites on luc+ messenger RNA were determined by the position of the synthetic promoter in the luciferase expression plasmids as shown by primer extension experiments. Results from electrophoretic mobility shift assays revealed multiple DNA-protein complexes upon binding of nuclear proteins with either DNA strand but not the double-stranded DNA derived from the ran promoter. Our results delineate the first promoter sequence of the Giardia gene (ran), which provides an excellent model for future studies on transcription regulation in this protozoan parasite.