Real time signal processing in the clinical setting

We routinely use a variety of real time signal acquisition, enhancement, and display techniques in the operating room to provide the surgeon with functional information. This enables reduction of surgical morbidity in cases which present a significant risk to the nervous system. Here we present regression based signal processing algorithms which produce considerable signal-to-noise-ratio enhancement with corresponding reduction in the time required to obtain an interpretable neurophysiological signal. We also present the approach we have applied to fault tolerance and distributed data display for our workstation cluster environment.     

Nocturnal evolution of respiratory effort in obstructive sleep apnoea syndrome: influence on arousal threshold

It has been recently described that the overnight increase in maximal end-apnoeic oesophageal pressure (P(oes,max)), considered as an index of the arousal threshold to occlusion, mostly contributes to apnoea lengthening during the night. However, the rise in apnoea duration could also be caused by changes in hypoxaemia, chemosensitivity and upper airway resistance. To better define the relative contributions of each of these factors, we examined the recordings of nine patients. Before apnoea, the mean pulmonary resistance at peak inspiratory flow (RPIF) was computed. During apnoea, all swings in oesophageal pressure (P(oes)) were measured to define the P(oes,max), the increase from the minimum to the maximum (deltaP(oes)), the rate of increase in P(oes) (RP(oes)) and the P(oes) at the first occluded breath (P(oes,1)). A gradual and significant increase in apnoea duration (p=0.02), P(oes,max) (p=0.02) and deltaP(oes) (p=0.006) was present across the night without any changes in oxygen saturation, RPIF, and P(oes,1). The slope of increase in P(oes,max), apnoea duration and deltaP(oes) was correlated with the apnoea/hypopnoea index. We conclude that in obstructive sleep apnoea, the nocturnal rise in apnoea duration is attributable more to an increase in the arousal threshold related to apnoea recurrence than to changes in chemosensitivity and upper airway resistance.     

Race/ethnicity, social class, and prevalence of breast cancer prognostic biomarkers: a study of white, black, and Asian women in the San Francisco bay area

We assessed distributions of breast cancer prognostic biomarkers by race/ethnicity and socioeconomic position among paraffin-embedded tumor biopsy specimens from 135 US women (48 white women, 44 black women, 43 Asian women) diagnosed with breast cancer between 1966 and 1990. No racial/ethnic or socioeconomic differences in distributions were observed for tumor stage, lymph node involvement, estrogen, progesterone, and epidermal growth factor receptors, oncogenes such as Her2/neu and p53, cytoplasmic proteins cathepsin-D and ps2, and two indices of cell growth, Ki67 and DNA ploidy, adjusting for age at diagnosis, menopausal status, place of birth and, for racial/ethnic comparisons, working class composition of census block-group at diagnosis. Black and Asian women, however, were 3.5 times (95% confidence interval [CI] = 1.2, 10.1) and 3.7 times (95% CI = 1.3, 10.6), respectively more likely than white women to have a tumor size of > or = 20 mm, and Asian women were 3.4 times (95% CI = 1.1, 10.4) more likely than black women to be positive for androgen receptor, adjusting for these same factors. No differences in distributions by socioeconomic position were observed for these latter two tumor characteristics. These data suggest that racial/ethnic and socioeconomic disparities in breast cancer survival are unlikely to be explained solely by differential distributions of molecular breast cancer prognostic biomarkers.     

Short-duration nocturnal hypoxemia and persistent pulmonary hypertension

Can daily short-duration hypoxemia (4-8 hours) induce pulmonary hypertension and right ventricular hypertrophy? A clinical model of this type of hypoxemia does exist: isolated nocturnal hypoxemia in patients with obstructive sleep apnea syndrome (OSAS) or chronic obstructive pulmonary disease (COPD). By investigating the pulmonary hemodynamics of these patients, it should be possible to determine whether nocturnal hypoxemia alone can induce pulmonary hypertension. Although nocturnal hypoxemia (in OSAS as well as in COPD) can induce acute episodes of pulmonary hypertension, it would not appear that nocturnal hypoxemia alone would be sufficient to provoke permanent diurnal pulmonary hypertension. This is the conclusion of recent studies concerning diurnal pulmonary hemodynamics in OSAS and COPD patients exhibiting minimal hypoxemia during the day but significant nocturnal desaturation. The therapeutic consequences of these data, particularly in COPD are important: current evidence is insufficient to treat with nocturnal oxygen therapy COPD patients who have minimal diurnal hypoxemia but significant nocturnal desaturation.     

Time course of pulmonary artery pressure during sleep in sleep apnoea syndrome: role of recurrent apnoeas

Recent results in animals have suggested that repetition of hypoxaemic stimuli may result in a progressive increase in pulmonary arterial pressure (Ppa). The purpose of the present study was to investigate the effects of recurrent obstructive apnoeas on Ppa. We have, therefore, examined the nocturnal trend of Ppa in seven obstructive sleep apnoea syndrome (OSAS) patients and in five snorers. Mean Ppa was measured before, at the start, at the end and after the selected apnoeas. The analysis was performed for each 1 h period for at least 7 h throughout the night on at least 10 randomly selected apnoeas per hour. In snorers, 100 randomly chosen values were measured during every hour of the night. In the morning after the nocturnal study, the Ppa responses to acute hypoxia and hypercapnia were measured. No Ppa changes throughout the 7 h were found during sleep in snorers [Ppa slope:-0.002+/-0.10 mmHg x h(-1)]. In OSAS patients a small but significant increase in Ppa throughout the night was noted, affecting the values before [Ppa slope: 0.7+/-0.16 mmHg x h(-1)], at the start of apnoea [Ppa slope: 0.530.1 mmHg x h(-1)] as well as at the end [Ppa slope: 0.44+/-0.08 mmHg x h(-1)] and in the postapnoeic period [Ppa slope: 0.55+/-0.1 mmHg x h(-1)]. When we limited the analysis to nonrapid eye movement (NREM) sleep, a trend in progressive Ppa was also present, irrespective of changes in apnoea duration and apnoea desaturation. The Ppa rise during the night was not affected by diurnal Ppa pulmonary vascular response to hypoxia and hypercapnia or indices of sleep apnoea severity. We conclude that in obstructive sleep apnoea, pulmonary artery pressure progressively increases during the night, reflecting the cumulative effects of apnoeas and nocturnal hypoxaemia.     

In-situ-Messung der Stickoxidkonzentration in turbulenten Diffusionsflammen

Zusammenfassung Die laserspektroskopischen Me?methoden laserinduzierte Fluoreszenz und spontane Ramanspektroskopie werden eingesetzt zur Messung der Konzentrationen von Stickoxid, Hydroxyl sowie der chemischen Hauptkomponenten und der Temperatur. Betrachtet wird die thermische Umsetzung von Wasserstoff mit Luftsauerstoff. Es wird die experimentelle Vorgehensweise und Problematik dargestellt. Ebenso wird der Weg der Modellierung und Berechnung turbulenter Verbrennungsvorg?nge am konkreten Beispiel skizziert. Die Annahme chemischen Gleichgewichts stellt sich als ungenügend in der Berechnung der Stickoxid- und Hydroxylkonzentrationen heraus. Eine deutlich bessere Vorhersage wird durch Einführen einer Reaktionsfortschrittsvariablen für das chemische Modell erreicht.     

The other side of scavenger receptors: pattern recognition for host defense

Scavenger receptors bind modified lipoproteins and may play an important role both in normal and in pathological lipid metabolism. A number of different classes of scavenger receptors have been identified and several of these are multiligand receptors. Studies, both in vitro and in vivo, have indicated that at least some of these scavenger receptors may serve as pattern recognition receptors because they are able to bind a wide variety of pathogens. As a consequence, they may play key roles in innate immunity and host defense.     

Absence of detectable human herpesvirus 8 in the semen of human immunodeficiency virus-infected men without Kaposi's sarcoma

The prevalence of human herpesvirus 8 (HHV-8)/Kaposi's sarcoma (KS)-associated herpesvirus was investigated in the semen of 99 human immunodeficiency virus (HIV)-infected men (median CD4 cell count, 357/mm3) by use of a polymerase chain reaction (PCR) assay capable of detecting <10 copies of HHV-8 DNA. Of the subjects, 95 (96%) self-identified as men who have sex with men (MSM), and 3 had a history of clinical KS. Seminal cell specimens were negative for HHV-8 in 98 subjects. None of the 26 without KS (27.1% of 96 tested) who were seropositive for HHV-8 by IFA for latency-associated nuclear antigens had HHV-8 detected in their semen. The only subject with any evidence for seminal HHV-8 DNA was seropositive for HHV-8 and had active KS. HHV-8 was detected in 10 (10.4%) of 96 peripheral blood mononuclear cell specimens. The prevalence of HHV-8 DNA by PCR in semen of HIV-infected MSM without KS is low.     

Mechanical Properties and Bake Hardening Behaviour of two Cold Rolled Multiphase Sheet Steels subjected to CGL Heat Treatment Simulation

In recent years, multiphase steels have become a material of choice for use in the car manufacturing industry owing to their excellent mechanical properties. It is anticipated that in the years to come these steels will show the highest increase in usage. A particular aspect of their potential is that multiphase steels often show good bake hardening (BH) properties. The main factors that govern the microstructures and the properties of these steels are the chemical composition and the production process parameters. In this work two commercial cold rolled sheet steels with different carbon content were investigated. In order to produce dual phase (DP) steels with a ferrite‐martensite microstructure, the as‐received material was subjected to heat treatment simulating continuous galvanising line (CGL) cycles with an overageing zone before the zinc pot. After a first CGL cycle predominantly ferritic microstructures with small amounts of martensite, pearlite and retained austenite were obtained, which resulted in deviations from typical DP properties, e.g. in the occurrence of discontinuous yielding. A higher line speed led to improved mechanical properties. BH prestrain was varied between 0 and 10%. While only very little bake hardening was observed without prestrain, with increasing prestrain the amount of BH was evolving quickly towards larger values of more than 60 MPa. Generally, the BH values were somewhat larger for higher carbon content. Finally, an optimised CGL cycle was simulated at laboratory scale with changes in the process parameters. Thus, characteristic DP microstructures resulting in desired mechanical properties were obtained. For these optimised conditions, BH₂ values in excess of 60 MPa were achieved for both steels investigated.