Highly stable ultrabroadband mid-IR optical parametric chirped-pulse amplifier optimized for superfluorescence suppression

We present a 9 GW peak power, three-cycle, 2.2 microm optical parametric chirped-pulse amplification source with 1.5% rms energy and 150 mrad carrier envelope phase fluctuations. These characteristics, in addition to excellent beam, wavefront, and pulse quality, make the source suitable for long-wavelength-driven high-harmonic generation. High stability is achieved by careful optimization of superfluorescence suppression, enabling energy scaling.

Limits to compression with cascaded quadratic soliton compressors

We study cascaded quadratic soliton compressors and address the physical mechanisms that limit the compression. A nonlocal model is derived, and the nonlocal response is shown to have an additional oscillatory component in the nonstationary regime when the group-velocity mismatch (GVM) is strong. This inhibits efficient compression. Raman-like perturbations from the cascaded nonlinearity, competing cubic nonlinearities, higher-order dispersion, and soliton energy may also limit compression, and through realistic numerical simulations we point out when each factor becomes important. We find that it is theoretically possible to reach the single-cycle regime by compressing high-energy fs pulses for wavelengths lambda = 1.0-1.3 microm in a beta -barium-borate crystal, and it requires that the system is in the stationary regime, where the phase mismatch is large enough to overcome the detrimental GVM effects. however, the simulations show that reaching single-cycle duration is ultimately inhibited by competing cubic nonlinearities as well as dispersive waves, that only show up when taking higher-order dispersion into account.

Spinal cord injury rehabilitation: the experience of women

STUDY DESIGN

Qualitative study.

OBJECTIVES

To develop the knowledge base regarding women's experiences of spinal cord injury (SCI) rehabilitation.

SETTING

United Kingdom.

METHODS

Qualitative interviews with 10 women from four regional SCI rehabilitation centres were transcribed verbatim and analysed according to grounded theory.

RESULTS

The central psychosocial problem identified for women during SCI rehabilitation was vulnerability. Vulnerability was amplified by lack of privacy within the rehabilitation centre, by negative staff interactions (associated with perceived lack of control and lack of respect) and by women's minority status in the rehabilitation setting, which at times left women feeling marginalized and inferior. Vulnerability was contained by: negotiating privacy and space; receiving support and encouragement from staff, other patients and family; and by adopting a positive attitude.

CONCLUSION

The SCI rehabilitation environment and interactions within it have the potential to influence significantly, either positively or negatively, women's feelings and behaviours as they begin to negotiate a revised identity as a disabled person. There is a need for further research to be carried out in this area in order that women's needs and concerns can be better understood and clinical practice developed accordingly.

Nonlocal explanation of stationary and nonstationary regimes in cascaded soliton pulse compression

We study soliton pulse compression in materials with cascaded quadratic nonlinearities and show that the group-velocity mismatch creates two different temporally nonlocal regimes. They correspond to what is known as the stationary and nonstationary regimes. The theory accurately predicts the transition to the stationary regime, where highly efficient pulse compression is possible.

Therapeutic angiogenesis for patients with limb ischemia by utilization of fibrin meshwork. Pilot randomized controlled study

AIM

The aim of this paper is to assess the feasibility and efficacy of fibrin in inducing neovascularization as an angiogenic substance and/or carrier for vascular endothelial growth factor (VEGF) in patients with limb ischemia.

METHODS

Twenty-three patients with limb ischemia and referred for below the knee amputations were randomized for treatment: group 1, 7 patients received only a saline injection; group 2, 9 received intramuscular injection of fibrin and group 3, 7 received the fibrin composition with deferoxamine and added VEGF(165). The fibrin meshwork was introduced into the popliteal area of the diseased limbs using a dual syringe system (1 contained thrombin solution [1 mg, 5000 U] and 1 contained fibrinogen [1 mg, Baxter Hyland Immuno] solution). In group 3, Deferoxamine (100 microg) and 500 microg of VEGF(165) were added to the fibrinogen solution.

RESULTS

In the control group 5 patients had undergone below the knee amputation at the 3-6 month follow-up. Only 1 patient from Group 2 had below the knee amputation 5 months following Fibrin only administration. Clinical improvement was noted in all 8 patients following fibrin administration and in all 7 patients injected with the fibrin meshwork, deferoxamine and VEGF combination.

CONCLUSION

IM injection of fibrin is safe and appears to be an efficient method to treat limb ischemia. These findings indicate that use of fibrin may be a novel and simple method for inducing therapeutic angiogenesis.

Echolucency of carotid plaques correlates with plaque cellularity

OBJECTIVE

To analyse the relationship between carotid plaque echolucency and cellularity.

METHODS

Carotid plaques (14 symptomatic and 16 asymptomatic) were snap frozen after endarterectomy and defined on the basis of their grey-scale-median (GSM), obtained from pre-operative high-definition ultrasonography, as either echolucent (<32) or echogenic (>or=32). DNA and total soluble protein were determined to assess cellularity.

RESULTS

After correcting for wet weight, symptomatic plaques had significantly more DNA (0.400 +/- 0.07 vs 0.335 +/- 0.07 mg/g; p = 0.03) and soluble protein (34.1 +/- 6.6 vs 29.7 +/- 3.4 mg/g; p = 0.03) than asymptomatic plaques. Predominantly echolucent (Grey-Weale classification) plaques had more DNA (0.404 +/- 0.06 vs 0.332 +/- 0.08 mg/g; p = 0.03) than echogenic plaques. Plaques with GSM < 32 also had more DNA (0.386 +/- 0.08 vs 0.319 +/- 0.06 mg/g; p = 0.04) and soluble protein (34.7 +/- 7.3 vs 29.6 +/- 4.2 mg/g; p = 0.03) than those with GSM >or= 32. Inverse relations were found between GSM and plaque DNA (r = -0.47; p = 0.02) and soluble protein (r = -0.45; p = 0.02) as well as between age and DNA (r = 0.39; p = 0.04) and soluble protein (r = -0.50; p = 0.003).

CONCLUSIONS

Echolucency of carotid plaques as assessed by ultrasonography reflects plaque cellularity. This observation support the notion that ultrasonography can be used to identify high-risk plaques and evaluate effect of interventions on plaque structure.

Intravascular ultrasound-guided percutaneous transluminal coronary angioplasty with provisional spot stenting for treatment of long coronary lesions

OBJECTIVES

The purpose of this study was to evaluate the approach of intravascular ultrasound (IVUS)-guided percutaneous transluminal coronary angioplasty (PTCA) with spot stenting (SS) for the treatment of long coronary lesions.

BACKGROUND

Treating long coronary lesions with balloon angioplasty results in suboptimal short- and long-term outcomes. Full lesion coverage with traditional stenting (TS) has been associated with a high restenosis rate.

METHODS

We prospectively evaluated a consecutive series of 130 long lesions (>15 mm) in 101 patients treated with IVUS-guided PTCA and SS. The results were compared with those of TS in a matched group of patients. Coronary angioplasty was performed with a balloon to vessel ratio of 1:1, according to the IVUS media-to-media diameter of the vessel at the lesion site, to achieve prespecified IVUS criteria: lumen cross-sectional area (CSA) > or =5.5 mm(2) or > or =50% of the vessel CSA at the lesion site. The stents were implanted only in the vessel segment where the criteria were not met.

RESULTS

In the SS group, stents were implanted in 67 of 130 lesions, and the mean stent length was shorter than that of lesions in the matched TS group (10.4 +/- 13 mm vs. 32.4 +/- 13 mm, p < 0.005). The 30-day major adverse cardiac event (MACE) rate was similar (5%) for both groups. Angiographic restenosis was 25% with IVUS-guided SS, as compared with 39% in the TS group (p < 0.05). Follow-up MACE and target lesion revascularization rates were lower in the SS group than in the TS group (22% vs. 38% [p < 0.05] and 19% vs. 34% [p < 0.05], respectively).

CONCLUSIONS

Intravascular ultrasound-guided SS for the treatment of long coronary lesions is associated with good acute outcome. Angiographic restenosis and follow-up MACE rates were significantly lower than those with TS.

Local delivery of c-myc neutrally charged antisense oligonucleotides with transport catheter inhibits myointimal hyperplasia and positively affects vascular remodeling in the rabbit balloon injury model

Myointimal hyperplasia after percutaneous transluminal coronary angioplasty (PTCA) is a key component of the process of restenosis. The c-myc is a critical cell-cycle division protein involved in the formation of neointima. We evaluated the long-term impact of local delivery of c-myc neutrally charged antisense oligonucleotides (Resten-NG) on myointimal hyperplasia after PTCA in a rabbit model. PTCA was performed in the iliac arteries of 25 New Zealand white rabbits, using a Transport catheter at 8 atm for 30 sec, three times; 500 microg Resten-NG (n = 11) or saline (n = 14) was delivered to the PTCA site at 2 atm with the outer balloon for 2 min. The diet was supplemented with 0.25% cholesterol for 10 days before and 60 days after PTCA. Angiography was performed at harvest, and vessels were fixed in formalin, processed, and stained with hematoxylin and eosin (H&E) and Movat. Quantitative angiography showed that local delivery of antisense c-myc at PTCA reduced late luminal loss from 1.8 +/- 0.30 mm in control animals to 0.90 +/- 0.30 mm in the treatment group (P = 0.001). Histological analysis by planimetry showed that intimal areas were 1.67 +/- 0.44 mm(2) and 0.82 +/- 0.32 mm(2) in the control and antisense delivery groups, respectively (P < 0.05). We conclude that local delivery of Resten-NG inhibited myointimal hyperplasia after PTCA in cholesterol-fed rabbits for up to 60 days.

Absence of Chlamydia pneumoniae in surgical specimens of coronary and carotid arteries by polymerase chain reaction

PURPOSE

Several recent articles indicate the renewed interest that Chlamydia pneumoniae is associated with and contributes to arterial diseases. Associations have been established for coronary arteries, carotid arteries and abdominal aortic aneurysms by serological studies, immunofluorescence and DNA-specific testing. The purpose of this study was to determine the presence of C. pneumoniae in coronary artery plaques, carotid artery plaques and old vein grafts that were harvested at the time of surgery.

METHODS AND MATERIALS

Interventions were carried out on patients with carotid artery disease and coronary disease based upon their anatomic findings and symptomatology. Plaques were removed from the carotid arteries with standard endarterectomy techniques. The coronary plaques were removed utilizing blunt dissection to peel the plaque from the coronary artery. Old vein grafts were harvested during repeat surgery by excising the vein grafts. The tissue specimens were analyzed by polymerase chain reaction (PCR).

RESULTS

Ninety-nine specimens from 68 consecutive patients with advanced coronary atherosclerosis with or without cerebrovascular disease were analyzed. We failed to find C. pneumoniae in any of the vascular tissue.

CONCLUSIONS

A large cooperative study involving surgical specimen analysis is needed to assess the role of C. pneumoniae in the etiology of atherosclerosis.

Glycosaminoglycan-lipoprotein interaction

Glycosaminoglycans (GAGs) bound to various proteoglycans (PGs) present in the cardiovascular system have been proposed to perform a wide range of functions. These include conferring viscoelastic properties; interacting with and modulating growth factors and enzymes; and as receptors and co-receptors in lipoprotein metabolism. Binding of apoB-100 lipoproteins, particularly low density lipoproteins (LDL), to GAGs of extracellular matrix PGs in arteries has been proposed to be an initiating event in development of atherosclerosis. This study was initiated with the aim of getting an overview of the binding patterns of different lipoprotein subclasses with individual GAG categories. We thus evaluated the interaction of lipoproteins with GAGs commonly found in the cardiovascular system using a gel mobility-shift assay developed for this purpose. The same procedure was used to measure lipoproteins binding to metabolically [(35)S]-labeled whole PGs prepared from three cell types, arterial smooth muscle cells, THP-1 macrophages and from HepG2 cells. The effect of GAG composition on PGs on lipoprotein binding was evaluated by enzymatic degradation of the carbohydrate chains. Heparan sulfate was found to bind beta very low density lipoproteins (beta-VLDL) and a chylomicron remnant model (beta-VLDL+apoE), but not LDL. Dermatan sulfate was found to bind LDL, but not beta-VLDL or the chylomicron remnant model. Chondroitin sulfate and heparin were found to bind all lipoproteins tested (LDL, beta-VLDL and beta-VLDL+apoE) although with different affinities. We can conclude that each lipoprotein subclass tested binds a specific assortment of the GAGs tested. The observations made contribute to the understanding of new and complex mechanisms by which carbohydrate and lipid metabolism may be linked.

Low-power helium: neon laser irradiation enhances production of vascular endothelial growth factor and promotes growth of endothelial cells in vitro

BACKGROUND AND OBJECTIVE

Numerous reports suggest that low-power laser irradiation (LPLI) is capable of affecting cellular processes in the absence of significant thermal effect. The objective of the present study was to determine the effect of LPLI on secretion of vascular endothelial growth factor (VEGF) and proliferation of human endothelial cells (EC) in vitro.

STUDY DESIGN/MATERIALS AND METHODS

Cell cultures were irradiated with single different doses of LPLI (Laser irradiance from 0.10 to 6.3 J/cm(2)) by using a He:Ne continuous wave laser (632 nm). VEGF secretion by smooth muscle cells (SMC) and fibroblasts was quantified by sandwich enzyme immunoassay technique. The endothelial cell proliferation was measured by Alamar Blue assay. VEGF and transforming growth factor beta (TGF-beta) expression by cardiomyocytes was studied by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

We observed that (1) LPLI of vascular and cardiac cells results in a statistically significant increase of VEGF secretion in culture (1.6-fold for SMC and fibroblasts and 7-fold for cardiomyocytes) and is dose dependent (maximal effect was observed with LPLI irradiance of 0.5 J/cm(2) for SMC, 2.1 J/cm(2) for fibroblasts and 1.05 J/cm(2) for cardiomyocytes). (2) Significant stimulation of endothelial cell growth was obtained with LPLI-treated conditioned medium of SMC (maximal increase was observed with LPLI conditioned medium with irradiance of 1.05 J/cm(2) for SMC and 2.1 J/cm(2) for fibroblasts.

CONCLUSIONS

Our studies demonstrate that low-power laser irradiation increases production of VEGF by SMC, fibroblasts, and cardiac myocytes and stimulates EC growth in culture. These data may have significant importance leading to the establishment of new methods for endoluminal postangioplasty vascular repair and myocardial photoangiogenesis.

Extent and distribution of in-stent intimal hyperplasia and edge effect in a non-radiation stent population

Intimal hyperplasia within the body of the stent is the primary mechanism for in-stent restenosis; however, stent edge restenosis has been described after brachytherapy. Our current understanding about the magnitude of in vivo intimal hyperplasia and edge restenosis is limited to data obtained primarily from select, symptomatic patients requiring repeat angiography. The purpose of this study was to determine the extent and distribution of intimal hyperplasia both within the stent and along the stent edge in relatively nonselect, asymptomatic patients scheduled for 6-month intravascular ultrasound (IVUS) as part of a multicenter trial: Heparin Infusion Prior to Stenting. Planar IVUS measurements 1 mm apart were obtained throughout the stent and over a length of 10 mm proximal and distal to the stent at index and follow-up. Of the 179 patients enrolled, 140 returned for repeat angiography and IVUS at 6.4 +/- 1.9 months and had IVUS images adequate for analysis. Patients had 1.2 +/- 0.6 Palmaz-Schatz stents per vessel. There was a wide individual variation of intimal hyperplasia distribution within the stent and no mean predilection for any location. At 6 months, intimal hyperplasia occupied 29.3 +/- 16.2% of the stent volume on average. Lumen loss within 2 mm of the stent edge was due primarily to intimal proliferation. Beyond 2 mm, negative remodeling contributed more to lumen loss. Gender, age, vessel location, index plaque burden, hypercholesterolemia, diabetes, and tobacco did not predict luminal narrowing at the stent edges, but diabetes, unstable angina at presentation, and lesion length were predictive of in-stent intimal hyperplasia. In a non-radiation stent population, 29% of the stent volume is filled with intimal hyperplasia at 6 months. Lumen loss at the stent edge is due primarily to intimal proliferation.

Intravascular low-power laser irradiation after coronary stenting: long-term follow-up

BACKGROUND AND OBJECTIVE

A high restenosis rate remains a limiting factor for percutaneous transluminal coronary angioplasty and stenting. The objective of this study was to evaluate the effect of intravascular red laser therapy (IRLT) on restenosis after stenting procedures in de novo lesions.

STUDY DESIGN/MATERIALS AND METHODS

A total of 68 consecutive patients were treated with IRLT in conjunction with coronary stenting procedures. Mean lesion length was 16.5 +/- 2.4 mm. Reference vessel diameter (RVD) and pre-minimal lumen diameter (MLD) were 2.90 +/- 0.15 mm and 1.12 +/- 0.26 mm, respectively.

RESULTS

After treatment, MLD was 2.76 +/- 0.32 mm with no procedural complications or in-hospital adverse events. Angiographic follow-up (n = 61) revealed restenosis in nine patients (14.7%) with rate by artery size of > 3 mm (n = 21) 0%; 2.5--3.0 mm (n = 28) 14.2%; and < 2.5 mm (n = 12) 41.6%.

CONCLUSION

Intravascular red light therapy is safe, feasible, and reduces expected restenosis rate after coronary stenting.