Advanced glycation end-products and methionine sulphoxide in skin collagen of patients with type 1 diabetes.

AIMS/HYPOTHESIS: We determined whether oxidative damage in collagen is increased in (1) patients with diabetes; (2) patients with diabetic complications; and (3) subjects from the Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) study, with comparison of subjects from the former standard vs intensive treatment groups 4 years after DCCT completion. SUBJECTS, MATERIALS AND METHODS: We quantified the early glycation product fructose-lysine, the two AGEs N (epsilon)-(carboxymethyl)lysine (CML) and pentosidine, and the oxidised amino acid methionine sulphoxide (MetSO) in skin collagen from 96 patients with type 1 diabetes (taken from three groups: DCCT/EDIC patients and clinic patients from South Carolina and Scotland) and from 78 healthy subjects. RESULTS: Fructose-lysine was increased in diabetic patients (p<0.0001), both with or without complications (p<0.0001). Controlling for HbA(1c), rates of accumulation of AGEs were higher in diabetic patients than control subjects, regardless of whether the former had complications (CML and pentosidine given as log(e)[pentosidine]) or not (CML only) (all p<0.0001). MetSO (log(e)[MetSO]) also accumulated more rapidly in diabetic patients with complications than in controls (p<0.0001), but rates were similar in patients without complications and controls. For all three products, rates of accumulation with age were significantly higher in diabetic patients with complications than in those without (all p<0.0001). At 4 years after the end of the DCCT, no differences were found between the previous DCCT management groups for fructose-lysine, AGEs or MetSO. CONCLUSIONS/INTERPRETATION: The findings suggest that in type 1 diabetic patients enhanced oxidative damage to collagen is associated with the presence of vascular complications.

Soil organic carbon sequestration in cotton production systems of the southeastern United States: a review.

Past agricultural management practices have contributed to the loss of soil organic carbon (SOC) and emission of greenhouse gases (e.g., carbon dioxide and nitrous oxide). Fortunately, however, conservation-oriented agricultural management systems can be, and have been, developed to sequester SOC, improve soil quality, and increase crop productivity. Our objectives were to (i) review literature related to SOC sequestration in cotton (Gossypium hirsutum L.) production systems, (ii) recommend best management practices to sequester SOC, and (iii) outline the current political scenario and future probabilities for cotton producers to benefit from SOC sequestration. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.56 Mg C ha(-1) yr(-1) (H(0): no change, p < 0.001). More diverse rotations of cotton with high-residue-producing crops such as corn (Zea mays L.) and small grains would sequester greater quantities of SOC than continuous cotton. No-tillage cropping with a cover crop sequestered 0.67 +/- 0.63 Mg C ha(-1) yr(-1), while that of no-tillage cropping without a cover crop sequestered 0.34 +/- 47 Mg C ha(-1) yr(-1) (mean comparison, p = 0.04). Current government incentive programs recommend agricultural practices that would contribute to SOC sequestration. Participation in the Conservation Security Program could lead to government payments of up to Dollars 20 ha(-1). Current open-market trading of C credits would appear to yield less than Dollars 3 ha(-1), although prices would greatly increase should a government policy to limit greenhouse gas emissions be mandated.

Effect of collagen turnover on the accumulation of advanced glycation end products.

Collagen molecules in articular cartilage have an exceptionally long lifetime, which makes them susceptible to the accumulation of advanced glycation end products (AGEs). In fact, in comparison to other collagen-rich tissues, articular cartilage contains relatively high amounts of the AGE pentosidine. To test the hypothesis that this higher AGE accumulation is primarily the result of the slow turnover of cartilage collagen, AGE levels in cartilage and skin collagen were compared with the degree of racemization of aspartic acid (% d-Asp, a measure of the residence time of a protein). AGE (N(epsilon)-(carboxymethyl)lysine, N(epsilon)-(carboxyethyl)lysine, and pentosidine) and % d-Asp concentrations increased linearly with age in both cartilage and skin collagen (p < 0.0001). The rate of increase in AGEs was greater in cartilage collagen than in skin collagen (p < 0.0001). % d-Asp was also higher in cartilage collagen than in skin collagen (p < 0.0001), indicating that cartilage collagen has a longer residence time in the tissue, and thus a slower turnover, than skin collagen. In both types of collagen, AGE concentrations increased linearly with % d-Asp (p < 0.0005). Interestingly, the slopes of the curves of AGEs versus % d-Asp, i.e. the rates of accumulation of AGEs corrected for turnover, were identical for cartilage and skin collagen. The present study thus provides the first experimental evidence that protein turnover is a major determinant in AGE accumulation in different collagen types. From the age-related increases in % d-Asp the half-life of cartilage collagen was calculated to be 117 years and that of skin collagen 15 years, thereby providing the first reasonable estimates of the half-lives of these collagens.

Leukoencephalopathy in small cell lung cancer patients receiving prophylactic cranial irradiation.

The cases of 283 small cell lung cancer patients who received treatment with combination chemotherapy with or without prophylactic cranial irradiation (PCI) were reviewed to determine the incidence of leukoencephalopathy. The overall incidence was 10%. Of all patients receiving PCI, 17% developed neurotoxicity, and of those receiving PCI and surviving greater than or equal to 1.5 years, 37% suffered neurologic sequelae. In those receiving PCI but surviving less than 1.5 years, the incidence of neurotoxicity was 4%. The mean time interval between the end of PCI and the onset of neurotoxicity was 17 months (range 2-63 months). The PCI dose ranged from 2600-3600 cGy. None of the patients not receiving PCI developed neurotoxicity. The incidence of neurotoxicity in long-term survivors (greater than or equal to 1.5 years) with respect to PCI dose was less than or equal to 3000 cGy (25%), 3200 cGy (56%), 3600 cGy (36%). Almost all of the patients getting PCI also received lomustine, an agent associated with DNA repair inhibition and synergism with DNA damaging agents such as ionizing radiation or alkylating agents. Under the conditions of our study, PCI was associated with an unacceptable risk of neurotoxicity. Until further information is forthcoming, one should proceed with caution when using PCI in conjunction with lomustine.

Necrotic lung and bronchopleural fistula as complications of therapy in lung cancer.

Seven patients developed a lung abscess and bronchopleural fistula after undergoing aggressive treatment of their lung cancer with radiotherapy +/- chemotherapy. These complications were preceded by a prodrome of recurrent bronchitis with increasing refractoriness to antibiotics, weight loss, fever, and generalized debilitation. Delays in definitive diagnosis and treatment often resulted from concern about the patients guarded cancer prognosis and misinterpretation of involved areas on x-rays and scans as being secondary to cancer rather than manifestations of treatment toxicity. Early surgical treatment utilizing local muscular flaps for bronchial stump reinforcement and restoration of chest wall continuity can successfully remedy these complications.

Treatment toxicities in long-term survivors of limited small cell lung cancer.

A total of 211 patients with limited small cell lung cancer were assessed retrospectively for long-term toxicities, treatment-related deaths, and second primaries. All had received treatment with various combinations of doxorubicin, vincristine, cisplatin, lomustine, cyclophosphamide, and etoposide with or without split-course thoracic radiotherapy (4,000 cGy/10 fractions) and/or split-course prophylactic cranial irradiation (3,600 cGy/10 fractions). Sixty-eight (32%) of the patients survived longer than 1.5 years and formed the basis of this study. Debilitating pulmonary, cardiac, and neurologic toxicity was noted in 12%, 14%, and 15%, respectively, of long-term survivors. These complications were the result of aggressive combined modality therapy. Certain drugs appeared to cause additive toxicity when combined with radiation. Three patients developed new primary tumors of squamous cell origin. Attention must be directed to defining the safest way to employ aggressive combined modality treatment for these patients.