A better incision for pectus excavatum repair: avoiding the keloid triangle

The most common approach to the pepair of pectus excavatum and pectus carinatum deformities is via a central transverse submammary incision. The subsequent suprasternal scar is conspicuous and prone to hypertrophic and keloid scarring. To avoid the keloid triangle and to produce a less noticeable scar, we have utilized bilateral inframammary incisions for repairs of five female and two male patients with pectus defects. This approach provides excellent access for cartilage resection, sternotomy, and sternal tupport without increasing opearative time or compromising operative exposure. On follow-up for up to 25 months, all patients have had excellent cosmetic and functional results. Chest wall configuration and stability, wound healing, and scar formation have all been without complication. No keloid or hypertrophic scars have developed. To date, there has been no recurrence of pectus defects. We believe bilateral inframammary incisions are a superior approach for pectus repairs by enchancing cosmesis with less noticeable scars and fewer hypertropic and keloid scars, all without compromising operative exposure or increasing operative time.     

Oxidative stress occurs in perfused rat liver at low oxygen tension by mechanisms involving peroxynitrite

Ethanol increases free radical formation; however, it was recently demonstrated that it also causes extensive hypoxia in rat liver in vivo. To address this issue, it was hypothesized that peroxynitrite formed in normoxic periportal regions of the liver lobule has its reactivity enhanced in hypoxic pericentral regions where the pH is lower. Via this pathway, peroxynitrite could lead to free radical formation in the absence of oxygen. Livers from fed rats were perfused at low flow rates for 75 min. Under these conditions, periportal regions were well oxygenated but pericentral areas became hypoxic. Low-flow perfusion caused a significant 6-fold increase in nitrotyrosine accumulation in pericentral regions. During the last 20 min of perfusion, the spin-trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone was infused and adducts were collected for electron-spin resonance analysis. A six-line radical adduct signal was detected in perfusate. Direct infusion of peroxynitrite produced a radical adduct with identical coupling constants, and a similar pattern of nitrotyrosine accumulation was observed. Retrograde perfusion at low rates resulted in accumulation of nitrotyrosine in periportal regions. Although the magnitude of the radical in perfusate was increased by ethanol, it was not derived directly from it. Both nitrotyrosine accumulation and radical formation were reduced by inhibition of nitric oxide synthase with N-nitro-L-arginine methyl ester, but not with the inactive D-isomer. Radical formation was decreased nearly completely by superoxide dismutase and N-nitro-L-arginine methyl ester, consistent with the hypothesis that the final prooxidant is a derivative from both NO. and superoxide (i.e., peroxynitrite). These results support the hypothesis that oxidative stress occurs in hypoxic regions of the liver lobule by mechanisms involving peroxynitrite.     

Inherent Abnormalities of Fat Cells from Massively Obese Individuals

In vitro investigations into adipose cell dynamics have revealed intrinsic characteristics of massively obese individuals' cells that could contribute to a relatively intractable expanded fat mass. Morbidly corpulent peoples' preadipocytes replicate to a greater degree than those from lean individuals. Coupled with exaggerated differentiation this enhanced growth would result in a greater number of fat cells which would increase adipose tissue mass. The relative resistance to de-differentiation that adipocytes from the massively obese demonstrate would contribute to stability of an increased number of adipocytes further exacerbating the problem. The increased message of an energy sensing protein, the obese gene product, suggests that the morbidly obese are insensitive to its action. Together these attributes provide a strong argument for a significant genetic role in the pathogenesis of obesity.     

Predictive factors of local-regional recurrences following parotid sparing intensity modulated or 3D conformal radiotherapy for head and neck cancer.

BACKGROUND AND PURPOSE: Predictive factors for local-regional (LR) failures after parotid-sparing, Intensity modulated (IMRT) or 3D conformal radiotherapy for head and neck (HN) cancers were assessed. PATIENTS AND METHODS: One hundred and fifty-eight patients with mostly stages III-IV HN squamous cell carcinoma underwent curative bilateral neck irradiation aimed at sparing the parotid glands. Patient, tumor, and treatment factors were analyzed as predictive factors for LR failure. RESULTS: Twenty-three patients had LR recurrence (19 in-field and four marginal). No differences were found in the doses delivered to the PTVs of patients with or without in-field recurrences. In univariate analysis, tumor site was highly predictive for LR failure in both postoperative and definitive RT patients. In postoperative RT patients, pathologic tumor size, margin status, extracapsular extension (ECE) and number of lymph node metastases, were also significantly predictive. Multivariate analysis showed tumor site (oropharynx vs. other sites) to be a significant predictor in all patients, and involved margins and number of involved lymph nodes in postoperative patients. CONCLUSIONS: Clinical rather than dosimetric factors predicted for LR failures in this series, and were similar to those reported following standard RT. These factors may aid in the selection of patients for studies of treatment intensification using IMRT.