Pulmonary vascular responses to hypoxia and hyperoxia in healthy volunteers and COPD patients measured by electrical impedance tomography

BACKGROUND: Electrical impedance tomography (EIT) is a noninvasive imaging technique using impedance to visualize and measure blood volume changes. STUDY OBJECTIVE: To examine the validity of EIT in the measurement of hypoxic pulmonary vasoconstriction (HPV) and hyperoxic pulmonary vasodilation in healthy volunteers and COPD patients. PARTICIPANTS: Group 1 consisted of seven healthy volunteers (mean age, 46 years; age range, 36 to 53 years). Group 2 comprised six clinically stable COPD patients (mean age, 65 years; age range, 50 to 74 years). INTERVENTIONS: EIT measurements were performed in healthy subjects while they were breathing room air, 14% oxygen (ie, hypoxia), and 100% oxygen (ie, hyperoxia) through a mouthpiece. Maximal impedance change during systole (DeltaZsys) was used as a measure of pulmonary perfusion-related impedance changes. Stroke volume (SV) was measured by means of MRI. In the COPD group, EIT and SV also were determined, but only in room air and under hyperoxic conditions. RESULTS: The data were statistically compared to data for the room air baseline condition. In the volunteers, the mean (+/- SD) DeltaZsys for the group was 352 +/- 53 arbitrary units (AU) while breathing room air, 309 +/- 75 AU in hypoxia (p < 0.05), and 341 +/- 69 AU in hyperoxia (not significant [NS]). The mean MRI-measured SV was 83 +/- 21 mL while breathing room air, 90 +/- 29) mL in hypoxia (NS), and 94 +/- 19 mL in hyperoxia (p < 0.05). In the COPD patients, the mean DeltaZsys for this group was 222 +/- 84 AU while breathing room air and 255 +/- 83 AU in hyperoxia (p < 0.05). In this group, the SV was 59 +/- 16 mL while breathing room air and 61 +/- 13 mL in hyperoxia (NS). Thus, the volunteer EIT response to hypoxia is not caused by decreased SV, because SV did not show a significant decrease. Similarly, in COPD patients the EIT response to hyperoxia is not caused by increased SV, because SV showed only a minor change. CONCLUSION: EIT can detect blood volume changes due to HPV noninvasively in healthy subjects and hyperoxic vasodilation in COPD patients.     

Validation of the NucliSens Extractor in combination with the hepatitis C virus Cobas Amplicor 2.0 assay in four laboratories in the Netherlands utilizing nucleic acid amplification technology for blood screening

BACKGROUND AND OBJECTIVES: Since July 1 1999, four laboratories in the Netherlands have been routinely screening plasma minipools for the release of labile blood components utilizing hepatitis C virus nucleic acid amplification technology (HCV NAT). This report describes the performance evaluation of the HCV NAT method and the quality control results obtained during 6 months of routine screening. MATERIALS AND METHODS: Plasma minipools of 48 donations were prepared on a Tecan Genesis robot. HCV RNA was isolated from 2 ml of plasma by using the NucliSens Extractor and amplified and detected with the Cobas HCV Amplicor 2.0 test system. For validation of the test system the laboratories used viral quality control (VQC) reagents of CLB. RESULTS: Initial robustness experiments demonstrated consistent detection of PeliSpy HCV RNA samples of 140 genome equivalents/ml (geq/ml) in each station of the installed Nuclisens Extractors. Further 'stress' tests with a highly viraemic sample of approximately 5 x 10(6) geq/ml did not contaminate negative samples processed on all Extractor stations in subsequent runs. In the validation period prior to July 1999, 1021 pools were tested with the following performance characteristics: 0.1%, initially false reactive; 0.89%, failure of internal control detection; 0.97%, no eluate generated by the Extractor; and 100% reactivity of the PeliSpy 140 geq/ml control in 176 Extractor runs and a 98% reactivity rate of the PeliSpy 38 geq/ml control in 102 test runs. By testing the PeliCheck HCV RNA genotype 1 dilution panels 49 times, an overall 95% detection limit of 30 geq/ml ( approximately 8 IU/ml) and a 50% detection limit of 5 geq/ml was found by the four laboratories. In the first 6 months of routine screening, the minimum requirement for invalid results (2%) was exceeded with some batches of silica and NucliSens Extractor cartridges. From November 1999 to February 2000, the manufacturer (Organon Teknika) improved the protocol for silica absorption of the Nuclisens Extractor -- the cartridge design as well as the software of the Extractor. During the next 6 months of observation in 2000, the percentages of false initial reactives and invalids were 0.05% and 1.4%, respectively, in 8962 pools tested. Of these invalid results, 0.74% and 0.66% were caused by Extractor failure and negative internal control signals, respectively. The PeliSpy HCV RNA 'stop or go' run control of 140 geq/ml was 100% reactive, but invalid in 16/1375 (1.2%) of cases. The PeliSpy run control of 38 geq/ml for monitoring sensitivity of reagent batches was reactive in 95% of 123 samples tested. CONCLUSIONS: Each of the four HCV NAT laboratories in the Netherlands have achieved similar detection limits that are well below the sensitivity requirements of the regulatory bodies. After improvement of the NucliSens Extractor procedure, the robustness of the test system has proved to be acceptable for routine screening and timely release of all labile blood components.     

Alcohol, smoking and human papillomavirus in laryngeal carcinoma: a Nordic prospective multicenter study

Purpose Human papillomavirus (HPV) has been linked to oropharyngeal carcinomas, but its role in laryngeal squamous cell carcinoma (LSCC) is not clear. A prospective multicenter study based on known tumor-cell percentage of fresh frozen carcinoma biopsies was established to determine the HPV prevalence. Moreover risk factors such as smoking, alcohol abuse, chronic laryngitis and gastroesophageal reflux disease (GERD) were evaluated Methods Fresh-frozen laryngeal cancer biopsies from 108 patients in Finland, Norway, and Sweden were investigated. Patients whose biopsy samples contained at least 20% tumor tissue (N = 69) entered the study. HPV DNA was determined with MY09/11 and GP5+/6+ nested PCR and SPF10 PCR hybridization assay. Patients were examined by an ENT specialist and an extensive questionnaire concerning risk factors was filled in. Results Only three patients (4.4%) harbored HPV DNA in their carcinoma sample. Heavy alcohol drinking was associated with an increased risk of death, advanced-stage disease, and younger age at diagnosis. Chronic laryngitis, GERD, and orogenital sex contacts were rare. Poor oral hygiene was not associated with survival, although it correlated with heavy drinking. Conclusion In our series HPV was not important in LSCC. Heavy drinking led to major mortality in LSCC and promoted early carcinogenesis. This work was supported by grants from Cancer Societies of Finland, Helsinki University Hospital Research Funds, Finnish Dental Society Apollonia, Stockholm Cancer Society and Laryngfonden, Sweden.     

Effects of epoprostenol on right ventricular hypertrophy and dilatation in pulmonary hypertension

OBJECTIVES: To gain more knowledge of changes in main pulmonary artery flow and right ventricular mass and volumes in patients with pulmonary hypertension during epoprostenol therapy. METHODS: Eleven patients (9 women) were evaluated before the start of therapy and every 4 months thereafter. Right and left ventricular volumes and masses were measured by cine MRI. Flow was measured with MRI velocity quantification. At the same times, 6-min walking tests were performed. Right-heart catheterizations were performed at baseline and after 1 year. RESULTS: Right ventricular mass in the patient group was significantly higher from that in a control group of healthy volunteers (95 +/- 26 g vs 42 +/- 10 g, p < 0.05 [mean +/- SD]), whereas the stroke volume was lower (34 +/- 11 mL vs 81 +/- 11 mL, p < 0.05). The greatest improvement in right ventricular stroke volume (to 41 +/- 11 mL, p < 0.05) took place in the first 4 months. During the 1-year follow-up, right ventricular end-diastolic volume and mass did not change, and mean pulmonary artery pressure remained nearly stable at 55 mm Hg at baseline and 53 mm Hg after 1 year. Pulmonary vascular resistance decreased by 12.5% (p = 0.06). CONCLUSIONS: From these data we conclude that epoprostenol lowers pulmonary vascular resistance, leading to an increase in pulmonary artery flow. This increase in pulmonary artery flow corresponds well with the increase in 6-min walking distance and can be noninvasively monitored by MRI (flow quantification). Right ventricular dilatation and hypertrophy are not reversed by epoprostenol therapy, but do not progress either.     

Temperature-induced down-regulation of the glucocorticoid receptor in peripheral blood mononuclear leucocyte in patients with sepsis or septic shock

OBJECTIVE Activation of the hypothalamic-pituitary-adrenal axis is of vital importance during critical Illness. We have studied the adaptive mechanisms which occur at the level of the glucocorticoid receptor in glucocorticoid target tissues in patients with sepsis or septic shock. DESIGN The effects of hypercortlsolaemia, hyperthermia and cellular composition on number of glucocorticoid receptors per cell and their affinity were evaluated, both In vitro and In vivo, In peripheral blood mononuclear leucocytes of control subjects and In patients with sepsis or septic shock. SUBJECTS Fifteen patients (age 25-79) with sepsis or septic shock who were admitted to an Intensive care unit were studied. The control group consisted of 24 healthy laboratory employees. MEASUREMENTS The binding capacity and affinity of the glucocorticoid receptors were measured and compared to clinical data and the plasma Cortisol concentrations. RESULTS Hypercortlsolaemia, in vitro, resulted in a decreased affinity and a decreased binding capacity of the glucocorticoid receptor. In vitro, hyperthermia as well as variations In the cellular composition did not Influence the glucocorticoid receptor. In vivo, there was no change In the number of receptors per cell In patients with sepsis or septic shock as compared to healthy controls. However, a decreased affinity of the glucocorticoid receptor was observed. There was a weak but significant negative correlation between body temperature and the number of glucocorticoid receptors In the patient group. There was no relation between circulating Cortisol concentrations and glucocorticoid receptor affinity and number. CONCLUSIONS There Is no obvious regulation of the number of glucocorticoid receptors by plasma Cortisol concentrations In vivo. The decreased affinity of the glucocorticoid receptor together with the negative correlation between hyperthermia and the number of glucocorticoid receptors In patients with sepsis or septic shock suggest that hypo-thalamlc-pitultary-adrenal axis activation during critical illness Is accompanied by peripheral adaptation in glucocorticoid receptor number and affinity.