Measurement of kinetic perfusion parameters of gadoteridol in intact myocardium: effects of ischemia/reperfusion and coronary vasodilation

Quantitation of myocardial perfusion is feasible using contrast enhanced magnetic resonance imaging. A method to quantitate myocardial blood flow is provided by the Kety model modified to account for a diffusable tracer such as gadoteridol. In the present study, perfusion parameters of the modified Kety model (partition coefficient and extraction efficiency) were determined for gadoteridol in intact myocardium using a constant flow, isolated, perfused heart model. Perfusion conditions included hearts with normal perfusion, hearts made globally ischemic for 20 min then perfused normally, and hearts whose coronary flow was more than doubled with 9 microM adenosine. T1 relaxation times were rapidly measured at 0.5 T following step increases in perfusate gadoteridol concentration and at steady state. Both the partition coefficient and extraction efficiency were found to be significantly increased in ischemic/reperfused hearts compared to normal. While flow rates in adenosine hearts were too high for accurate extraction efficiency determination using this technique, the partition coefficient was no different between adenosine and normally perfused hearts. The method described in this article allowed the kinetic parameters of the modified Kety model to be determined in intact heart using NMR relaxation time measurements as the basis of the calculation.     

Vascular anastomosis using a biodegradable device with a heat-shrinking sleeve: a preliminary report

PURPOSE: The objective of this study is to present a simple mechanical anastomosis system capable of uniting vessels of differing diameters and to evaluate its applicability. MATERIALS AND METHODS: A new mechanical system for anastomosis of small vessels was used in 30 rabbits to join 100 sectioned carotid arteries and jugular veins. The system is resorbable and consists of a cuff and a shrinkable sleeve. To carry out the anastomosis, one vessel end is pulled through the cuff and everted over it. The second vessel end is then slipped over the everted vessel end and the cuff. A heat-shrinking sleeve is positioned over the site and shrunk to produce permanent fixation. RESULTS: The overall patency rate of the anastomoses was 96.6% in the arteries and 93.3% in veins. Microscopically, the intima-to-intima contact sites were bridged by an endothelial layer in the first postoperative weeks. CONCLUSION: Advantages of the system include a short insertion time, simple instrumentation, a high patency rate, and resorbability. However, the method requires additional vessel length for eversion, and it cannot be used for end-to-side anastomoses.     

Frequency specificity of acoustic evoked potentials of early and intermediate latency with high-pass noise masking

OBJECTIVES: To investigate the effect of intranasal corticosteroids in the treatment of polyps in patients with severe polyposis listed for surgical treatment and to determine the treatment effect on the progression of the disease. DESIGN: A double-blind, randomized, parallel-group, placebo-controlled, 12-week study at a single center. SETTING: A tertiary referral center in London, England. PATIENTS: Thirty-four patients with severe polyposis listed for endoscopic surgical treatment. INTERVENTION: By random allocation, fluticasone propionate aqueous nasal spray (FPANS), 200 microg twice a day; beclomethasone dipropionate aqueous nasal spray, 200 microg twice a day; or placebo nasal spray twice a day was administered. Patients received 2 actuations to each nostril in the morning and in the evening. MAIN OUTCOME MEASURES: Efficacy end points were the need for polypectomy at the end of treatment, the results of acoustic rhinometry, the polyp score, the peak nasal inspiratory flow rate, and an assessment of symptoms. RESULTS: The polyp score was significantly decreased in the FPANS-treated group (P < or = .01). The nasal cavity volume was significantly increased in both the FPANS-treated group and the group receiving beclomethasone compared with placebo (P < or = .01) at the end of treatment. The percentage change in the mean morning peak nasal inspiratory flow rate was greater in the FPANS-treated group, with a significant effect observed at week 2 (P = .01). Nasal blockage was significantly decreased in both active groups compared with the group receiving placebo. No significant difference was observed between the treatment groups in the number of patients requiring polypectomy. CONCLUSIONS: Fluticasone and beclomethasone aqueous nasal sprays are effective in treating the symptoms of severe nasal polyps. There was some evidence that the group treated with FPANS responded more quickly to intervention and that the magnitude of the response was greater than in the group receiving beclomethasone.     

Expression of human leukocyte antigens class I and class II on cultured biliary epithelial cells after cytomegalovirus infection

The influence of cytomegalovirus (CMV) infection on the HLA expression on cultured biliary epithelial cells (BEC) was investigated. CMV-infection augmented expression of HLA class I but not of HLA class II. CMV reduced the IFN-gamma-mediated induction of the de novo expression of HLA class II while the stimulated expression of HLA class I was not impaired. Autologous but not allogeneic PBL responded to CMV-infected BEC. This response resulted in upregulation of HLA class I on BEC which was significantly higher compared with the expression on infected BEC alone or on uninfected BEC cocultured with autologous PBL. The results suggest that CMV modulates the immunogenic potential of BEC, which is important for the HLA and CMV-mediated pathomechanisms in vivo.     

Metabolism and activation of cyclopenta polycyclic aromatic hydrocarbons in isolated human lymphocytes, HL-60 cells and exposed rats

The metabolism of radiolabelled benz(j)aceanthrylene (B(j)A) was studied in suspensions of isolated human peripheral mononuclear blood cells (lymphocytes), using high performance liquid chromatography (HPLC). The only known metabolite found after 24 h exposure to 30 microg/ml (120 microM) B(j)A, was B(j)A-1,2-dihydrodiol, representing approximately 35% of the total metabolites formed. B(j)A, benz(l)aceanthrylene (B(l)A) and benzo(a)pyrene (B(a)P) all caused DNA adducts in human lymphocytes, as well as in the human promyelocytic cell line HL-60 cells, as measured by the 32P-postlabelling technique (30 microg/ml, 24 h). The total DNA adduct levels in human lymphocytes exposed to B(j)A, B(l)A or B(a)P were 0.13 +/- 0.03, 1.10 +/- 0.62 and 0.37 +/- 0.10 fmol/microg DNA, respectively, and similar levels were obtained in HL-60 cells (0.18 +/- 0.14, 0.97 +/- 0.35 and 0.29 +/- 0.17 fmol/microg DNA, respectively). For each compound, the human lymphocytes and HL-60 cells in addition showed similar DNA adduct patterns. Cells exposed to B(j)A revealed only one DNA adduct, which, judged by its TLC properties, resulted from B(j)A-1,2-epoxide. As measured by the alkaline filter elution technique, only low levels of single strand DNA breaks (SSB) were observed in both human lymphocytes and HL-60 cells after exposure to B(j)A, B(l)A or B(a)P (24 h, 30 microg/ml). By adding cytosine-1-beta-D-arabinofuranoside (Are C) and hydroxyurea (HU) 1 h prior to analysis to prevent strand break rejoining, some increase in SSB (2-3 times) was observed in the lymphocytes. Co-incubation of human lymphocytes with liver microsomes from PCB-treated rats for 1 h and exposure to B(j)A or B(l)A, increased the DNA adduct levels in the lymphocytes to 12.3 and 37.8 fmol/microg DNA, respectively. A large increase in SSB was also observed, whereas no such increase was observed after co-incubation with human liver microsomes. In vivo exposure of rats to 30 mg/kg B(j)A (i.p.) for 24 h revealed one major DNA adduct in lymphocytes and lung tissue (only one of three rats showed an adduct in liver tissue), apparently resulting from B(j)A-1,2-epoxide. The total DNA adduct level in the lymphocytes was 0.09 fmol/microg DNA, and in lung tissue between 0.10 and 0.62 fmol/microg DNA. Overall, the present data suggests that oxidation at the cyclopenta-ring is an important activation pathway for B(j)A in rats as well as in humans.     

InGaP/InGaAs HFET with high current density and high cut-offfrequencies

Doped channel pseudomorphic In_0.49Ga_0.51P/In _0.20Ga_0.80As/GaAs heterostructure field effect transistors have been fabricated on GaAs substrate with 0.25 μm T-gates and self-aligned ohmic contact enhancement. By introducing the channel doping and reducing the series resistances, a high current density of 500 mA/mm is obtained in combination with cut off frequencies of f_T=68 GHz and f_max=160 GHz. The channel doping did not affect the RF-performance of the device essentially, which is additionally reflected in noise figures below 1.0 dB with an associated gain of 14.5 dB at 12 GHz     

Kriechermüdungsverhalten warmfester Stähle bei betriebsähnlicher Hochtemperaturdehnwechselbeanspruchung

Creep fatigue behaviour of heat resistant steels under service- type strain cycling at high temperature On three typical heat resistant steels the creep fatigue behaviour is investigated up to about 10 000 h test duration using a service-type strain cycle. In a creep fatigue life analysis the cyclic deformation behaviour and the applicability of the generalized damage accumulation rule are investigated and possibilities of long-term creep fatigue prediction are studied.     

Increased incidence of mumps orchitis in adolescence and adulthood--sequelae of low vaccination rate?

In recent years, mumps orchitis has become a rarely reported disease. However, since October 1994 a clear increase in the incidence of this disease has been observed. At four hospitals in the Saarland, Germany, 45 cases of mumps orchitis in adolescents and adults were diagnosed in this period. In addition to the case history and clinical findings, the diagnosis was confirmed by an increased IgM titer. None of the patients had been previously vaccinated. The main reason for this was a lack of parental knowledge of the necessity for this vaccination, one which has almost no side effects. The goal of this study is to describe the disease, present our own results, and indicate the need for vaccination. In addition to providing information, a further aim of the study is to increase the motivation of adolescents and adults for vaccination. Although many treatments for mumps have been published in recent years, the most successful therapy is still prophylactic vaccination.