Construction and performance of a new catheter-tip oxygen electrode

A membrane-covered catheter-tip oxygen-electrode system is described, which gives a linear response in the P_o2 range of 0–350 mm Hg. The system is highly stable, free from drift and mechanically safe for application in man. This is accomplished by using a screw cap for fastening the membrane holder, thus preventing the loss of parts and making the electrolyte chamber really fluidtight. Insulation of the platinum wire with glass precludes the possibility of fluid-bridge contact with the silver anode beyond the measuring site at the tip.     

Managing COPD: no more nihilism!

This special issue of Patient Education and Counseling is long overdue. During most of the last two decades asthma, and notably asthma self-management has been in the spotlight, while COPD has had to endure a nihilistic approach. The first sign that interest was shifting to the treatment of COPD came from a few large randomized trials on the use of inhaled corticosteroids (ICS) in COPD. Although these studies demonstrated a moderate effect of ICS in COPD, it has become clear that true improvements in the management of this chronic disease will have to come from behavioral interventions. This special issue of Patient Education and Counseling is dedicated solely to the non-pharmaceutical management of COPD. It addresses many issues related to behavioral therapy, such as smoking cessation, exercise training, nutritional aspects, and self-management programs, including action plans to self-treat exacerbations. With the availability of all the treatment and management options, described in this special issue, a nihilistic attitude toward the patient with COPD is no longer justified.     

Simultaneous perfusion of both coronary arteries and drainage of the coronary sinus in the dog heartin situ

A technique is described for perfusion of the entire coronary arterial system of the dog heart in situ and for drainage of the coronary sinus blood. Both coronary arteries are cannulated without ligation of major ventricular branches and disconnected from the aorta. The cannulas are connected to an extracorporeal system allowing perfusion under controlled pressure, without ill effects to either the heart or the blood. The arterial perfusion system is fed from the femoral arteries of the dog. The coronary sinus is cannulated for draining the blood to a venous reservoir against a controlled pressure. From the reservoir the blood is pumped into a femoral vein. Thus a preparation is obtained in which the interdependency of coronary circulation and performance of the heart has been discontinued. Under careful monitoring of pressures and flows, and of blood temperature, blood gases and plasma electrolytes, the preparation has been kept in excellent condition for up to 7 hrs.     

EXTEROCEPTIVE STIMULATION AS A CONTINGENT FACTOR IN THE INDUCTION AND ELICITATION OF DELAYED TYPE HYPERSENSITIVITY REACTIONS TO 1 CHLORO-, 2-4, DINITROBENZENE IN GUINEA PIGS

This study attempted to determine whether a prior period of “stress” would elicit the sensitization reaction of the skin to topically applied chemical agents. A subthreshold concentration of 1-chloro-, 2-4, dinitrobenzene (DNCB) was applied to the skin of 40 guinea-pigs, 20 of which had been subjected to repetitive electrical shocks throughout the previous 15 minutes. They were examined 24 hours later, and were retested with DNCB at another site after 9 days for signs of delayed sensitization. The stressed animals exhibited a more severe contact-reaction (p <. 01) after the induction test and also after the delayed test.     

Measurement of antibody-mediated binding of human polymorphonuclear leukocytes to HSV-1 infected anchorage fibroblasts

A method for the quantitation of effector cell binding to anchorage fibroblast monolayers infected with HSV-1 is described. Human peripheral blood polymorphonuclear leukocytes (PMN) as effector cells were labeled with chromium-51. Fetal human lung fibroblasts were grown to confluency in microtiter plates, infected with HSV-1 and loaded with anti-HSV antibody. The amount of radiolabeled PMN adhering to the monolayer was determined after appropriate incubation and washings. The effector binding assay was shown to be dependent on specific anti-HSV antibodies, antibody concentration, HSV viral expression, and inoculation time. This assay system is especially useful for the evaluation of effector to target cell conjugate formation when applied to anchorage target cells.     

Keratinocyte-derived growth factors play a role in the formation of hypertrophic scars

In predisposed individuals, wound healing can lead to hypertrophic scar or keloid formation, characterized by an overabundant extracellular matrix. It has recently been shown that hypertrophic scars are accompanied by abnormal keratinocyte differentiation and proliferation, and significantly increased acanthosis, compared with normal scars. This study addressed the question of whether the development of normal and hypertrophic scars is regulated by differences in the growth factor profiles of both the epidermis and the dermis. The presence of interleukin-1alpha (IL-1alpha), IL-1beta, tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), transforming growth factor-beta1 (TGF-beta1), and basic fibroblast growth factor (bFGF) was investigated in biopsies taken from breast reduction scars at 3 and 12 months following surgery. The samples were analysed by immunohistological methods and categorized as scars that remained hypertrophic (HH), became normal (HN) or remained normal after 12 months (NN). The epidermal expression of IL-1alpha was significantly increased in NN scars compared with HN and HH scars 3 and 12 months following operation, whereas the dermal expression showed no difference. PDGF was significantly increased in the dermis of normal scars after 3 months and in both the epidermis and the dermis of hypertrophic scars after 12 months. IL-1beta, TNF-alpha, TGF-beta and bFGF showed no differences. It is hypothesized that impaired production of keratinocyte-derived growth factors, such as IL-1alpha, leads to a decrease in the catabolism of the dermal matrix, whereas augmented epidermal PDGF production leads to increased formation of the dermal matrix in hypertrophic scars. These observations support the possibility that the epidermis is involved in preventing the formation of hypertrophic scars.     

The pulmonary CO diffusing capacity according to Bates and according to Filley in patients with unequal ventilation

The pulmonary CO diffusing capacity (d l, co) was determined according to Filley et al., by these authors' method and according to Bates et al. in 24 patients with unequal ventilation without severe diffusion disturbances. Under the influence of the unequal ventilation, the Filley method yielded too high D values, while the values according to Bates were too low. The D values obtained by the authors' method were in between the above two extremes.In patients with unequal ventilation, the d value calculated by one of these methods affords little information as to the presence or absence of a diffusion disturbance, and no information on the extent of this diffusion disturbance. Only if D(F) is much too low is there a possibility of a disturbance in diffusion. A normal D(B) or D(K) indicates the probability of absence of a diffusion disturbance.     

High-performance liquid chromatography of the neuroactive steroids alphaxalone and pregnanolone in plasma using dansyl hydrazine as fluorescent label: application to a pharmacokinetic-pharmacodynamic study in rats

This report describes a rapid and sensitive analytical method for the quantification of the neuroactive steroids alphaxalone and pregnanolone in rat plasma using derivatization with dansyl hydrazine as fluorescent label. The method involves protein precipitation, alkaline derivatization and extraction of the compounds and internal standard pregnenolone with dichloromethane, followed by isocratic reversed-phase high-performance liquid chromatography on a 3-microm Microsphere C18 column with fluorescence detection at wavelengths 332 nm and 516 nm for excitation and emission, respectively. The mobile phase consists of a mixture of 25 mM acetate buffer (pH 3.7)-acetonitrile (45:55, v/v for alphaxalone and 40:60, v/v for pregnanolone) with a flow-rate of 1 ml/min. The total run time was approximately 35 min. In the concentration range of 0.010-10 microg ml(-1), the intra- and inter-assay coefficients of variation were less than 17% for both methods. In 50 microl plasma samples the corresponding limits of detection were 10 ng ml(-1) (signal-to-noise ratio=3). The utility of the analytical method was established by analyzing plasma samples from rats, which had received an intravenous administration of 5 mg kg(-1) alphaxalone or pregnanolone. Values for clearance, volume of distribution at steady state and terminal half life were 71.9 ml min(-1) kg(-1), 814 mg kg(-1) and 13.5 min for alphaxalone and 69.2 ml min(-1) kg(-1), 1,638 ml kg(-1) and 27.8 min for pregnanolone, respectively. Due to its simplicity and sensitivity this method can be used on a routine basis for pharmacokinetic analysis of neuroactive steroids.     

A computer program for calculating the acid-base parameters in samples of blood using a mini-computer

Summary A computer program is presented and evaluated, which calculates all acid-base parameters from data provided by either the indirect Astrup method or the direct method using empirical formulae derived from the Siggaard-Andersen curve nomogram. The program is implemented on a PDP 8 in a multi-user FOCAL environment and can be adapted to other electronic calculators.     

Multisensory integration mechanisms in haptic space perception

It has been argued that representations of peripersonal space based on haptic input are systematically distorted by egocentric reference frames. Interestingly, a recent study has shown that noninformative vision (i.e., freely viewing the region above the haptic workspace) improves performance on the so-called haptic parallel-setting task, in which participants are instructed to rotate a test bar until it is parallel to a reference bar. In the present study, we made a start at identifying the different sensory integration mechanisms involved in haptic space perception by distinguishing the possible effects of orienting mechanisms from those of noninformative vision. We found that both the orienting direction of head and eyes and the availability of noninformative vision affect parallel-setting performance and that they do so independently: orienting towards a reference bar facilitated the parallel-setting of a test bar in both no-vision and noninformative vision conditions, and noninformative vision improved performance irrespective of orienting direction. These results suggest the effects of orienting and noninformative vision on haptic space perception to depend on distinct neurocognitive mechanisms, likely to be expressed in different modulations of neural activation in the multimodal parietofrontal network, thought to be concerned with multimodal representations of peripersonal space.