Detachment of tobacco-smoke-material carriers from surfaces by turbulent air flow.

The influence of tobacco-smoke-material (TSM) on the detachment of microparticles from surfaces by turbulent air flow was investigated experimentally. Both clean and dusty glass surfaces were subjected to TSM either before or after the deposition of 64 microm to 76 microm-diameter stainless steel microparticles onto the surfaces. The TSM was generated by mechanically puffing research-grade cigarettes inside a smoking box that contained the surfaces. Microparticle detachment characteristics were studied in a wind tunnel using video microphotography. Measured nicotine concentration was used to determine the amount of TSM deposited on a surface.The 5% and 50% threshold velocities for detachment were used to quantify the effect of TSM on microparticle detachment. These velocities were compared with those obtained using a clean surface with no TSM exposure. The effect of TSM exposure on microparticle detachment depended significantly on whether exposure occurred before or after microparticle deposition. TSM exposure before microparticle deposition had little effect. TSM exposure after deposition delayed detachment to much higher velocities. The presence of dust on the surface with TSM also delayed detachment and increased the variability in the detachment velocities as compared to the case of a clean surface with no TSM exposure.

Established immunity precludes adenovirus-mediated gene transfer in rat carotid arteries. Potential for immunosuppression and vector engineering to overcome barriers of immunity.

Preclinical arterial gene transfer studies with adenoviral vectors are typically performed in laboratory animals that lack immunity to adenovirus. However, human patients are likely to have prior exposures to adenovirus that might affect: (a) the success of arterial gene transfer; (b) the duration of recombinant gene expression; and (c) the likelihood of a destructive immune response to transduced cells. We confirmed a high prevalence (57%) in adult humans of neutralizing antibodies to adenovirus type 5. We then used a rat model to establish a central role for the immune system in determining the success as well as the duration of recombinant gene expression after adenovirus-mediated gene transfer into isolated arterial segments. Vector-mediated recombinant gene expression, which was successful in naive rats and prolonged by immunosuppression, was unsuccessful in the presence of established immunity to adenovirus. 4 d of immunosuppressive therapy permitted arterial gene transfer and expression in immune rats, but at decreased levels. Ultraviolet-irradiated adenoviral vectors, which mimic advanced-generation vectors (reduced viral gene expression and relatively preserved capsid function), were less immunogenic than were nonirradiated vectors. A primary exposure to ultraviolet-irradiated (but not nonirradiated) vectors permitted expression of a recombinant gene after redelivery of the same vector. In conclusion, arterial gene transfer with current type 5 adenoviral vectors is unlikely to result in significant levels of gene expression in the majority of humans. Both immunosuppression and further engineering of the vector genome to decrease expression of viral genes show promise in circumventing barriers to adenovirus-mediated arterial gene transfer.

Adenovirus-mediated gene transfer into normal rabbit arteries results in prolonged vascular cell activation, inflammation, and neointimal hyperplasia.

Adenovirus vectors are capable of high efficiency in vivo arterial gene transfer, and are currently in use as therapeutic agents in animal models of vascular disease. However, despite substantial data on the ability of viruses to cause vascular inflammation and proliferation, and the presence in current adenovirus vectors of viral open reading frames that are translated in vivo, no study has examined the effect of adenovirus vectors alone on the arterial phenotype. In a rabbit model of gene transfer into a normal artery, we examined potential vascular cell activation, inflammation, and neointimal proliferation resulting from exposure to replication-defective adenovirus. Exposure of normal arteries to adenovirus vectors resulted in: (a) pronounced infiltration of T cells throughout the artery wall; (b) upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in arterial smooth muscle cells; (c) neointimal hyperplasia. These findings were present both 10 and 30 d after gene transfer, with no evidence of a decline in severity over time. Adenovirus vectors have pleiotropic effects on the arterial wall and cause significant pathology. Interpretation of experimental protocols that use adenovirus vectors to address either biological or therapeutic issues should take these observations into account. These observations should also prompt the design of more inert gene transfer vectors.

Physiology of the lateral decubitus position and one-lung ventilation.

OLV is most frequently utilized to provide a quiet field for the performance of many different surgical procedures. In some patients, severe hypoxemia may result, mandating the implementation of other therapies to provide adequate oxygenation. This paper has reviewed the physiological consequences of the lateral position that may contribute to the hypoxemia and the techniques we utilize at our institution for establishing OLV, maintaining OLV, and treating hypoxemia during OLV. Our technique is performed with the goal of maintaining adequate gas exchange and protecting the ventilated lung from potential overdistension and injury. It remains for future study to determine if the use of a lung protective strategy during intraoperative OLV offers any benefit to patients at risk for postoperative lung injury, such as those undergoing major lung resections.

Development of the single microelectrode current and voltage clamp for central nervous system neurons.

The development of a single microelectrode clamping circuit for central nervous system preparations is presented. The efficacy of the circuit in both current and voltage clamp modes is demonstrated by investigating the membrane properties of cat spinal motoneurons. Results are compared with those obtained using conventional techniques and reveal that this technique can be more readily applied to central nervous system neurons. The constraints invovled in employing this system to study time-varying events are also discussed.

Variation in human semen viscoelastic properties with respect to time post ejaculation and frequency of ejaculation.

The present study concerns the rheological characterization of the coagulation-liquefaction process of human semen. Results obtained using a multiple point capillary viscometer reveal marked variations in the elasticity and viscosity of an individual's semen with time immediately following ejaculation and frequency of ejaculation. Similarity among all cases examined for each material property is revealed by relating times post ejaculation to semen liquefaction time, thereby coupling liquefaction time with specific material property values. Further, the final state of liquefied semen is found to be characterized by Newtonian behavior (mean absolute viscosity = 3.37 centipoise). The semen's liquefaction time and ejaculate volume are determined to be functions of the frequency of ejaculation. Steady state ejaculate volume is found to decrease linearly with increasing ejaculation frequency, thereby providing a measure of glandular secretory rate. When collectively considered, these findings provide possible means for monitoring an individual's glandular behavior over an extended period of time and comparing such behavior to established standards.

University performance, gender and the rural health workforce: an analysis of nursing students.

The relationship between student gender and performance was examined in first year students enrolled in the Bachelor of Nursing course at Charles Sturt University from 1991 to 1995. A greater proportion of female students achieved passing grades in subjects studied when compared to male students, irrespective of the subject discipline area. Furthermore, a significantly greater proportion of female than male students passed nursing subjects; however, no statistically significant differences in performance were detected in the proportion of male or female students in either science or humanities subjects.

Perceptions of health and their relationship to symptoms in African American women with type 2 diabetes.

Diabetes mellitus is an incurable disease and a major cause of mortality and morbidity. Diabetes disproportionately affects members of minorities who suffer from higher rates of complications and greater disability (Cowie & Eberhardt, 1996). The purpose of this study was to (a) describe the symptoms of African American women with Type 2 diabetes and examine the relationship among diabetes-related symptoms; (b) document complications of diabetes and perceptions of health and functioning; and (c) examine the relationship between duration of diabetes and age at diagnosis and perceived health. A convenience sample of 75 African American women with Type 2 diabetes were interviewed. A 44-item questionnaire measured selected demographic variables, symptoms, documented complications, and their perceived relationship to diabetes. The SF-20 was used to measure perceptions of health status. Data show that African American women with Type 2 diabetes have a wide variety of symptoms and poor perceptions of their general health and physical functioning.

Seeding of vascular grafts with genetically modified endothelial cells. Secretion of recombinant TPA results in decreased seeded cell retention in vitro and in vivo.

BACKGROUND: Seeding of small-diameter vascular grafts with endothelial cells (ECs) genetically engineered to secrete fibrinolytic or antithrombotic proteins offers the potential to improve graft patency rates. METHODS AND RESULTS: Sheep venous ECs were transduced with a retroviral vector encoding human tissue plasminogen activator (TPA). The ECs were seeded onto 4-mm-ID synthetic (Dacron) grafts. Retention of the seeded ECs was measured 2 hours after placement of the seeded grafts both in vitro in a nonpulsatile flow system and in vivo (in sheep) as femoral and carotid interposition grafts. On exposure to flow in vitro, ECs transduced with TPA were retained at a significantly lower rate (median, 67%) than either untransduced ECs (81%) or ECs transduced with a control retroviral vector producing beta-galactosidase (beta-Gal) (80%) (P < .05 for TPA versus either control). On implantation in vivo, ECs transduced with TPA were retained at a very low rate (median, 0%), significantly less than the retention of ECs transduced with the beta-Gal vector (32%; P < .00001). Decreased in vivo retention of ECs transduced with TPA correlated modestly with increased in vitro cellular passage level (r2 = .48; P < .0001) but not with in vivo blood flow rate (P = .45). Addition of the protease inhibitor aprotinin to the cell culture and graft perfusion media resulted in a significant (P < .05) increase in in vitro retention of ECs transduced with TPA. CONCLUSIONS: Increased TPA expression significantly decreases seeded EC adherence in vitro and in vivo. Gene therapy strategies for decreasing graft thrombosis may require expression of antithrombotic molecules that lack proteolytic activity.