Evidence of vascular growth associated with laser treatment of normal canine myocardium

BACKGROUND: Transmyocardial laser revascularization is a new therapy for patients with refractory angina. Although clinical studies suggest that transmyocardial laser revascularization decreases angina and may improve regional blood flow, the underlying mechanisms are not elucidated. We hypothesized that one mechanism may relate to stimulation of vascular growth in laser-treated regions. METHODS: Transmyocardial laser revascularization channels were made with holmium:yttrium-aluminum garnet or carbon dioxide lasers in eight normal canine hearts; animals were sacrificed 2 to 3 weeks later and examined for vascular density and for evidence of smooth muscle proliferation. RESULTS: The original channels were infiltrated by granulation tissue with associated vascularity. Vascular growth was stimulated immediately surrounding the channel remnant as evidenced by an increase in the number of vessels (approximately twice that of the control region) and an increase in the number of vascular cells staining positive for markers of cellular proliferation. CONCLUSIONS: Transmyocardial laser revascularization leads to local vascular growth as early as 2 weeks after treatment. It remains to be determined whether this mechanism contributes to increased regional blood flow or to clinical benefits associated with this novel form of therapy.     

Expression and adaptive regulation of amino acid transport system A in a placental cell line under amino acid restriction

Trans-placental transport of amino acids is vital for the developing fetus. Using the BeWo cell line as a placental model, we investigated the effect of restricting amino acid availability on amino acid transport system type A. BeWo cells were cultured either in amino acid-depleted (without non-essential amino acids) or control media for 1, 3, 5 or 6 h. System A function was analysed using alpha(methyl-amino)isobutyric acid (MeAIB) transcellular transport studies. Transporter (sodium coupled neutral amino acid transporter (SNAT1/2)) expression was analysed at mRNA and protein level by Northern and Western blotting respectively. Localisation was carried out using immunocytochemistry. MeAIB transcellular transport was significantly (P < 0.05) increased by incubation of the cells in amino acid-depleted medium for 1 h, and longer incubation times caused further increases in the rate of transfer. However, the initial response was not accompanied by an increase in SNAT2 mRNA; this occurred only after 3 h and further increased for the rest of the 6-h incubation. Similarly, it took several hours for a significant increase in SNAT2 protein expression. In contrast, relocalisation of existing SNAT2 transporters occurred within 30 min of amino acid restriction and continued throughout the 6-h incubation. When the cells were incubated in medium with even lower amino acid levels (without non-essential plus 0.5 x essential amino acids), SNAT2 mRNA levels showed further significant (P < 0.0001) up-regulation. However, incubation of cells in depleted medium for 6 h caused a significant (P = 0.014) decrease in the expression of SNAT1 mRNA. System L type amino acid transporter 2 (LAT2) expression was not changed by amino acid restriction, indicating that the responses seen in the system A transporters were not a general cell response. These data have shown that placental cells adapt in vitro to nutritional stress and have identified the physiological, biochemical and genomic mechanisms involved.     

Primary malignant fibrous histiocytoma of the lung. Report of a case with bronchial brushing cytologic features

BACKGROUND: Malignant fibrous histiocytoma (MFH) arising primarily in the lungs is rare, and a preoperative diagnosis, as well as a surgical planning, is very important because of the tumor's propensity for vascular invasion and its low incidence of lymph node metastasis. The correct preoperative diagnosis of thoracic MFH is not easy to establish because the small fragments from needle and transbronchial biopsies are often inadequate for a conclusive histologic analysis. A preoperative bronchial brushing cytology suggestion of the diagnosis of primary MFH of the lungs may be helpful in such cases. CASE: A 37-year-old male presented with a large, irregular mass in the inferior and middle lobes on chest roentgenography as well as on computed tomography. Two bronchoscopies were performed, with the diagnosis of undifferentiated large cell carcinoma. After surgical resection a more sophisticated pathologic analysis, including immunohistochemical and ultrastructural studies, revealed a primary MFH of the lungs. Revision of the bronchial brushing cytology disclosed many spindle-shaped cells with a "comet" configuration, strongly suggestive of MFH. CONCLUSION: The bronchial brushing cytology features of spindle-shaped and bizarre, multinucleated giant cells with a comet appearance may be the key to the cytomorphologic diagnosis of MFH.     

Inbreeding and canine mammary cancer: a retrospective study

Using files of the Animal Neoplasm Registry (ANR) in Alameda and Contra Costa Counties, California, we conducted a retrospective study to compare the degree of inbreeding in the ancestry of purebred dogs with mammary and other cancers, and of those without tumors. Wright's coefficients of inbreeding, calculated for all animals in the three groups, ranged from 0.000 to 0.535. The median inbreeding coefficients of the mammary cancer and comparison groups (consisting of other cancers) were approximately twice that of the nonneoplastic group, but neither difference was statistically significant. Dogs with mammary adenocarcinoma and mixed mammary cancer had similar degrees of inbreeding.     

Effect of captopril, losartan, and bradykinin on early steps of insulin action

Insulin initiates its metabolic and growth-promoting effects by binding to the alpha subunit of its receptor, thereby activating the kinase in the beta subunit. This event leads to tyrosyl phosphorylation of its cytosolic substrate, insulin receptor substrate 1 (IRS-1), which in turn associates with and activates phosphatidylinositol (PI) 3-kinase. The clinical use of ACE inhibitors has been associated with increased insulin sensitivity. However, the exact molecular mechanism is unknown. In the present study, we examined the phosphorylation status of the insulin receptor and IRS-1, as well as the association between IRS-1 and PI 3-kinase in the liver and muscle of 20-month-old rats treated acutely with captopril, using immunoprecipitation with antipeptide antibodies to the insulin receptor and IRS-1, and immunoblotting with antiphosphotyrosine and anti-PI 3-kinase antibodies. Insulin stimulation increased receptor autophosphorylation to 462 +/- 253% (P < 0.05) in the liver and 697 +/- 78% (P < 0.001) in the muscle of ACE inhibitor-treated rats. There were also increases to 250 +/- 17% (P < 0.001) and 280 +/- 50% (P < 0.05) in the insulin-stimulated IRS-1 phosphorylation levels in the liver and muscle, respectively, of animals treated with captopril. The insulin-stimulated IRS-1 association with PI 3-kinase rose to 305 +/- 20% (P < 0.001) in liver and 267 +/- 48% (P < 0.05) in muscle. Losartan, an ANG receptor blocker, had no significant effect on insulin-stimulated IRS-1 phosphorylation in both tissues. The acute administration of bradykinin increased insulin-stimulated tyrosine phosphorylation of the insulin receptor and IRS-1 in the liver and muscle. These data demonstrate that ACE inhibitors modulate the early steps of insulin signaling, and that this effect may be simulated by the administration of bradykinin.