Radiation therapy of nasopharyngeal carcinoma in East Africa

Results of irradiation, 1 to 3 years after treatment, are presented in 64 cases of nasopharyngeal carcinoma in East Africans. Two types of anatomic point indices are presented. Both correlate well with the results. Prophylactic irradiation of the mediastinum and both axillae was not followed by any evident improvement of the results.     

Effect of perilymphatic fistulas on evoked otoacoustic emissions in the guinea pig

Round window perilymphatic fistulas were surgically created in 20 guinea pigs. Distortion product otoacoustic emissions (DPOAEs) at 2fl - f2 were recorded prior to and immediately following laceration of the round window. The stimuli were equal level sinusoids (f1 < f2) with f2 ranging from 2 to 10 kHz, a fixed f2:f1 ratio of 1.25, and stimulus levels (L2 = L1) ranging from 20 to 80 dB SPL. After an 18-day survival period, emission measurements were repeated, and fluorescein was infused into the cerebrospinal fluid to verify patency or closure of the fistula. Nine animals demonstrated patent fistulas, whereas 11 had closed fistulas. There was a statistically significant reduction in DPOAE amplitude after an acute fistula across all stimulus levels (p < .001). At 18 days the DPOAE amplitudes in animals with healed fistulas could not be differentiated from controls, whereas DPOAE amplitudes in animals with patent fistulas were statistically different from controls (p < .05). The results suggest that evoked otoacoustic emissions may be useful in detecting perilymphatic fistulas.     

Continuous quality improvement in the ICU and the role of a data management system

Quality improvement may be defined as the effort to improve the level of performance of key processes in the ICU. Based on knowledge of the current level of performance and on systematic analysis of organizational aspects of the ICU, quality improvement will include the implementation of standards, the formulation and analysis of quality indicators (e.g. scores, rate of complications such as nosocomial infections) and the possible introduction of data management systems.     

Inhibition of rat Na+/K+-ATPase isoforms by endogenous digitalis extracts from neonatal human plasma

An unique endogenous digitalis-like factor (EDLF) has been previously purified from human newborn cord plasma and its differential effects tested on the three well defined functional isoforms (alpha1, alpha2 and alpha3) of the alpha subunits of Na+/K+-ATPase in rat. EDLF specifically inhibits the enzymatic activity. It differs from ouabain by three criteria: a preincubation with the membranes is required for full activity, no effect on the rat cerebral alpha3 isoform and a steep dose-response curve with the same apparent potency for rat alpha2 and alpha1 isoforms of high (10(-7) M) and low affinity (3 x 10(-5) M) for ouabain. These results indicate that the Na+/K+-ATPase inhibitor involved in the regulation of sodium and body fluid volume and present in neonate and adult human plasmas is distinct from ouabain.     

Modelling the spread of HIV in social networks of injecting drug users

OBJECTIVE: To explore the risk of a future rise of HIV prevalence in populations of injecting drug users (IDU) with low HIV prevalence but continuing risk behaviour, and to study the potential influence of prevention measures on HIV incidence. METHODS: A stochastic simulation model was used to describe a network of long-term buddy relationships in a population of IDU. HIV transmission took place when borrowing injecting equipment from an infected buddy or stranger. The probability of transmission depended on the duration of infection. Individuals remained in the population on average for 10 years. Two surveys amongst IDU in The Netherlands containing information about risk behaviour were used to estimate model parameters. We investigated the effect of different prevention strategies. RESULTS: Below a threshold sharing frequency the epidemic never takes off; above the threshold there is a large stochastic variation in prevalence. After reduction of risk behaviour, HIV prevalence decreases very slowly. Reducing sharing with strangers is more effective than reducing the overall sharing frequency. Prevention focused on new IDU greatly reduces HIV incidence. Reduction of sharing frequency in HIV-positive IDU has no significant influence on HIV incidence at HIV testing rates of 10 and 50% per year, if infectivity is highest during primary infection. CONCLUSIONS: A stabilization of HIV prevalence does not exclude the possibility of a future rise. Predictions about the future course of an epidemic are inherently uncertain. The effect of prevention programmes on HIV prevalence only becomes visible on a long time-scale. Social networks of IDU play an important role in transmission dynamics and success of prevention.