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Biomedical subjects

N C White

Publications and source records attributed to N C White.

5 recordsLinked to original sources
PubMed2001

Mechanical and electromagnetic induction of protection against oxidative stress.

Cells and tissues can be protected against a potentially lethal stress by first exposing them to a brief dose of the same or different stress. This "pre-conditioning" phenomenon has been documented in many models of protection against oxidative stress, including ischemia/reperfusion and ultraviolet (UV) light exposure. Stimuli which induce this protective response include heat, chemicals, brief ischemia, and electromagnetic (EM) field exposures. We report here that constant mechanical vibration pre-conditions chick embryos, protecting them during subsequent stress from hypoxia or UV light exposure. Continuously mechanically vibrated embryos (60 Hz, 1 g (32 ft/s2), 20 min) exhibited nearly double the survival (67.5%, P < 0.001) after subsequent hypoxia as compared to non-vibrated controls (37.6%). As a second set of experiments, embryos were vibrated and then exposed to UV light stress. Those embryos that were vibrated prior to UV had nearly double the survival 3 h after UV exposure (66%, P < 0.001) as compared to controls (35%). The degree of protection, however, was dependent on the constancy of the vibration amplitude. When vibration was turned on and off at 1-s intervals throughout exposure, no increase in hypoxia protection was noted. For 50 s on/off vibration intervals, however, hypoxia protection comparable to continuous vibration was obtained. In contrast, random, inconstant mechanical vibration did not induce protection against subsequent UV exposure. These data suggest that to be an effective pre-conditioning agent, mechanical vibration must have a degree of temporally constancy (on/off intervals of greater than 1 s). Further experiments in both models (hypoxia and UV) indicated an interaction between vibration and EM field-induced protection. Vibration-induced hypoxia protection was inhibited by superposition of a random EM noise field (previously shown to inhibit EM field-induced protection). In addition, EM field-induced UV protection was inhibited by the superposition of random mechanical vibration. Thus, the superposition of either vibrational or EM noise during pre-conditioning virtually eliminated protection against hypoxia and UV. This link between EM field exposures and mechanical vibration is consistent with the hypothesis that cells sense these stimuli via a similar mechanism involving counter ion displacement.

Animals↗
PubMed1999

The growth and the control of human immunodeficiency virus in the lung: implications for highly active antiretroviral therapy.

In recent years, it has become apparent that the lung is an important niche for the proliferation of human immunodeficiency virus (HIV), which may have implications for highly active antiretroviral therapy (HAART). The lung itself is a major site for the opportunistic infections associated with the progression to acquired immune deficiency syndrome (AIDS), specifically Pneumocystis carinii, Myobacterium tuberculosis and pyogenic bacteria. These cases of active pulmonary complications are direct indicators of enhanced progression to AIDS-defining illness and increased morbidity and mortality. It is therefore essential that the interaction between the lung and HIV is fully understood. Recent research indicates the lung may be a major sanctuary for the virus, with distinct evolution and replication in contrast to other target organs for HIV. In this review, we will discuss the recent findings of HIV infection, evolution, host factors involved in the control of HIV within the lung and the impact this may have on current therapy.

AIDS-Related Opportunistic Infections↗
PubMed1997

Poisons and panic!

Home management of the majority of poison center callers is safe and cost-effective; but in the absence of poison center consultation, could callers correctly assess the severity of a poisoning? This study was conducted to determine indirectly whether callers can correctly assess the toxicity of a substance involved in a poison exposure by determining whether caller panic levels correlated with the expected toxicity of the exposure. Using a digital call recorder, 100 calls to the National Capital Poison Center involving children < 10 y were reviewed. The panic level of each caller was assessed and scored on a 4-point rating scale and, compared to the toxicity of the substance implicated (also on a 4-point rating scale). Most callers were mothers (85%), most patients were < 4 y (86%), and most exposure routes were ingestions (89%). Although there were only 12 male callers, male callers were significantly more panicked than females. Overall, there was a correlation between the panic level of the poison center callers and the toxicity of the substance involved in the exposure, with the mean panic level increasing as the toxicity increased. However, only 36% of patients had a panic level that was exactly appropriate for the toxicity level. Most callers were more panicked than they needed to be (57%), including 14% of callers who were much more panicked than they needed to be. Seven percent of callers were too calm; they appeared not to understand how toxic the exposure really was. Based on these data, one could predict that the majority of callers were sufficiently panicked that, had the poison center not been available to provide immediate consultation, the callers may have over-reacted and called 911 or gone straight to a hospital. Yet only 1 of the 57 overly-panicked callers was calling about a patient who actually required medical intervention. Of great concern, the 7% of patients who were too calm may have required medical intervention that, due to underestimation of the severity of the exposure, may have been withheld or delayed. Three of these "too calm" cases actually required medical intervention. Although subject to a number of design limitations, this study suggests that callers frequently over-react to poison exposures. In the absence of a well-utilized poison control system, excessive panic may contribute to excessive use of emergency departments and ambulance services and create excessive health care costs for poisoning emergencies.

Attitude to Health↗
PubMed1992

Medical illustration enters the market economy.

The department of medical illustration at the Royal Postgraduate Medical School (RPMS) has been operating as a registered company for just over 1 year. As other similar departments are forced into cost recovery, some may be considering this extra step. This paper sets out some of the pitfalls as well as giving some handy tips which will make the journey down this uneven road a little easier.

Cost Control↗