Near infrared laser-tissue welding using nanoshells as an exogenous absorber

BACKGROUND AND OBJECTIVE: Gold nanoshells are a new class of nanoparticles that can be designed to strongly absorb light in the near infrared (NIR). These particles provide much larger absorption cross-sections and efficiency than can be achieved with currently used chemical chromophores without photobleaching. In these studies, we have investigated the use of gold nanoshells as exogenous NIR absorbers to facilitate NIR laser-tissue welding. STUDY DESIGN/MATERIALS AND METHODS: Gold nanoshells with peak extinction matching the NIR wavelength of the laser being used were manufactured and suspended in an albumin solder. Optimization work was performed on ex vivo muscle samples and then translated into testing in an in vivo rat skin wound-healing model. Mechanical testing of the muscle samples was immediately performed and compared to intact tissue mechanical properties. In the in vivo study, full thickness incisions in the dorsal skin of rats were welded, and samples of skin were excised at 0, 5, 10, 21, and 32 days for analysis of strength and wound healing response. RESULTS: Mechanical testing of nanoshell-solder welds in muscle revealed successful fusion of tissues with tensile strengths of the weld site equal to the uncut tissue. No welding was accomplished with this light source when using solder formulations without nanoshells. Mechanical testing of the skin wounds showed sufficient strength for closure and strength increased over time. Histological examination showed good wound-healing response in the soldered skin. CONCLUSIONS: The use of nanoshells as an exogenous absorber allows the usage of light sources that are minimally absorbed by tissue components, thereby, minimizing damage to surrounding tissue and allowing welding of thicker tissues.     

Systemic activation of integrin alphaVbeta3 in donors with spontaneous intracerebral hemorrhage is associated with subsequent development of vasculopathy in the heart transplant recipient.

BACKGROUND: Recipients of hearts from donors with spontaneous intracerebral hemorrhage (ICH) are at increased risk of allograft vasculopathy compared with trauma donors. We have recently shown that the vitronectin receptor (integrin alpha(V)beta3) is upregulated in transplant vasculopathy. We hypothesized that donor ICH is associated with systemic activation of alpha(V)beta3 in the donor before transplantation. METHODS: We evaluated mRNA expressions of alpha(V)beta3 (TaqMan PCR) in endomyocardial biopsy samples at 1-week post-transplant in 20 recipients from ICH donors and 20 recipients from trauma donors. To investigate whether systemic activation of alpha(V)beta3 was present in the donor before transplantation, alpha(V)beta3 expression was also evaluated in the corresponding donor spleen lymphocytes. All patients underwent serial coronary intravascular ultrasound to evaluate for coronary vasculopathy. The baseline characteristics were similar except for increased donor age in the ICH Group. RESULTS: The ICH Group showed significant increased mRNA expression of alpha(V)beta3 in the heart biopsy samples (3.8-fold, p = 0.012) and in the corresponding donor spleen lymphocytes (3.5-fold, p = 0.014) compared with the Trauma Group. At 1 year, the ICH Group also showed increased progression of coronary vasculopathy. Multivariate regression analysis found that donor lymphocytic alpha(V)beta3 mRNA expression was independently associated with increased risk of vasculopathy (odds ratio, 1.9; 95% CI, 1.21-3.98, p = 0.03). CONCLUSIONS: Our report demonstrates the presence of systemic activation of alpha(V)beta3 in donors with spontaneous intracerebral hemorrhage and its association with the subsequent development of allograft vasculopathy in the recipient.     

The effect of combined Angiotensin-converting enzyme inhibition and calcium antagonism on allograft coronary vasculopathy validated by intravascular ultrasound.

BACKGROUND: Hypertension is a potential risk factor for allograft coronary vasculopathy. We evaluated the efficacy of angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists, and their combined use, on the development of coronary vasculopathy in hypertensive heart transplant recipients. METHODS: Eighty-two heart transplant recipients underwent serial intravascular ultrasound (IVUS) analysis at baseline (within 1 month) and at 1 year after transplantation and were evaluated for the development of coronary vasculopathy. Patients were divided into 4 groups. Nineteen normotensive recipients received no treatment, control (Group A). Hypertensive patients were treated with either ACE inhibitors (Group B, n = 37), calcium antagonists (Group C, n = 16), or both (Group D, n = 10). RESULTS: We found a significant reduction in IVUS indices of coronary vasculopathy in heart transplant recipients who used a combination of an ACE inhibitor and a calcium antagonist compared with recipients who used either drug alone (p < 0.05). This synergistic efficacy was independent of the baseline indices evaluated in a multivariate regression analysis model and was noted despite comparable mean arterial pressure among the 3 hypertensive groups at 1 year, thus suggesting the presence of a synergistic anti-proliferative effect beyond the anti-hypertensive efficacy. CONCLUSIONS: The combined use of an ACE inhibitor and a calcium antagonist is more effective than the individual use of either drug alone on the development of coronary vasculopathy in cardiac transplant recipients. Large randomized clinical trials are warranted to evaluate such a synergistic efficacy.     

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 16: bone graft extenders and substitutes

Despite the large volume of animal data regarding the use of synthetic bone graft substitutes or extenders, there are very few data regarding the use of these substances for fusion in lumbar degenerative disease. The best available data indicate that rhBMP-2 is a viable alternative to autograft bone for interbody fusion procedures. This same substance may also be a viable alternative to autograft for PLF; however, definitive medical evidence is not yet available. There is little, if any, medical evidence to support the use of other biological agents at the present time. As promising new compounds are brought to market, well-designed cohort studies and randomized trials will be required to determine the actual usefulness of these compounds in clinical practice. It is important not to generalize the results obtained with one preparation or application to different preparations or applications. The use of synthetic calcium phosphate ceramics as graft extenders appears to be reasonable in certain situations. The medical evidence available regarding their use is limited and of poor quality. Further study will be required to establish their utility for use in spinal fusion.     

Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 6: magnetic resonance imaging and discography for patient selection for lumbar fusion

Discography is an exquisitely sensitive but not specific diagnostic test for the diagnosis of discogenic low-back pain. The restriction of the definition of a positive discographic study to one that elicits concordant pain from a morphologically abnormal disc improves the definition's accuracy. Fusion surgery based on discography alone, however, is not reliably associated with clinical success. Therefore, discography is not recommended as a standalone test for treatment decisions in patients with low-back pain. Magnetic resonance imaging is a sensitive and noninvasive test for the presence of degenerative disc disease. Discography should not be attempted in patients with normal lumbar MR images. Discography appears to have a role in the evaluation of patients with low-back pain, but it is best limited to the evaluation of abnormal interspaces identified on MR imaging, the investigation of adjacent-level disc disease, and as a means to rule out cases of nonorganic pain from surgical consideration.     

Juvenile posttraumatic high-flow priapism: Current management dilemmas

High-flow priapism results from disruption of the intercavernosal artery resulting in an arteriocavernosal fistula and is rarely encountered in the pediatric and adolescent population. Clinically it manifests as a painless, prolonged erection after perineal trauma. Treatment has ranged from expectant management to open surgical exploration with vessel ligation. Internal pudendal arteriogram and superselective embolization with autologous blood clot has emerged as a safe and effective treatment modality in the young male population. Here the authors present 3 patients with high-flow priapism and discuss management of this rare clinical entity.     

Management of postoperative infections after the minimally invasive pectus excavatum repair

Purpose

Pectus excavatum is frequently repaired using the minimally invasive placement of a substernal bar (Nuss procedure). Infectious complications after the Nuss procedure are potentially devastating. To date, the management of postoperative infectious complications has not been well described.

Methods

A retrospective review of all patients (N = 168) who underwent the Nuss procedure from January 1, 1997, to October 1, 2003, at our institution was performed. Six patients (4%) had postoperative infections, and their medical records were reviewed.

Results

Of the 6 patients, 5 underwent operative drainage for wound abscesses that developed 2 to 76 weeks postoperatively. The other patient developed cellulitis 12 months postoperatively and was treated effectively with antibiotics alone. Recurrent infections were treated in 3 of 6 patients, one of whom eventually required removal of the bar resulting in a mild, residual pectus excavatum defect. One of 6 patients has had the substernal bar removed electively. The remaining 4 continue to be without clinically apparent infection at this time and are over 1 year removed from their infection.

Conclusions

Although uncommon, infectious complications after the Nuss procedure require complex management strategies. Despite recurrent infection in some cases, most infectious complications occurring after the minimally invasive repair can be effectively treated without having to remove the substernal bar.     

Passive Pneumatic Stabilization Device for Assisting in Reduction of Femoral Shaft Fractures

Abstract During treatment of femoral shaft fractures, not only the actual fracture reduction but also the retention of the achieved reduction is essential. Substantial forces may apply to the bone fragments, due to multidirectional muscular contraction. Furthermore, forces from manipulation of one bone fragment may be transferred over the soft tissues onto the other fragments, thus hindering accurate fracture reduction. Once a sufficient reduction has been achieved, this position must be retained whilst definitive internal fixation is performed. Conventional methods comprise mounting patients on a traction table and applying manual distraction or employing special distraction devices, such as the AO distractor device. These approaches, however, only insufficiently stabilize both main fragments. For example, on the traction table the proximal femoral fragment can pivot around the hip joint thus complicating precise reduction. A novel pneumatic stabilization device to assist surgeons during operative procedures is described. This passive holding device “Passhold” connects to one main fragment through a minimally invasive bone interface and statically locks the fragment’s position. Thereafter, only the other main fragment is manipulated to achieve reduction. Mutual interference of the reciprocal fragment positions, due to soft-tissue force transfer during manipulation, is avoided. The authors examined the stability of the novel retention device on a test rig and proved its functionality under sterile settings using cadaver tests. It is concluded that this device largely facilitates the operative procedure in femoral shaft fractures, is sufficiently stable and ergonomically suitable for intraoperative deployment.