9th International Congress on Isozymes, Genes, and Gene Families: an overview

The 9th International Congress on Genes, Gene Families, and Isozymes marked a historic transition in the series formerly known as the International Congress on Isozymes. The name of the congress was changed to reflect the broadened scope of this field and the new directions in which it is moving. To recognize and promote this transition, a number of new features were incorporated into this congress. Accordingly, the broad-based program featured preeminent biologists from 29 different countries. A total of 350 people attended the congress. A special new feature of this congress was the Student/Fellow Program, which was designed to enhance participation by advanced undergraduate and graduate students and postdoctoral fellows. This congress celebrated the progress that has occurred during the past 40 years beginning with studies of isozymes and leading into studies of specific genes and gene families. As we move into the next millennium, it is clear that our field is strongly positioned and will continue to be the focus of exciting and important new research.     

Reward prediction in primate basal ganglia and frontal cortex

Reward information is processed in a limited number of brain structures, including fronto-basal ganglia systems. Dopamine neurons respond phasically to primary rewards and reward-predicting stimuli depending on reward unpredictability but without discriminating between rewards. These responses reflect 'errors' in the prediction of rewards in correspondence to learning theories and thus may constitute teaching signals for appetitive learning. Neurons in the striatum (caudate, putamen, ventral striatum) code reward predictions in a different manner. They are activated during several seconds when animals expect predicted rewards. During learning, these activations occur initially in rewarded and unrewarded trials and become subsequently restricted to rewarded trials. This occurs in parallel with the adaptation of reward expectations by the animals, as inferred from their behavioral reactions. Neurons in orbitofrontal cortex respond differentially to stimuli predicting different liquid rewards, without coding spatial or visual features. Thus, different structures process reward information processed in different ways. Whereas dopamine neurons emit a reward teaching signal without indicating the specific reward, striatal neurons adapt expectation activity to new reward situations, and orbitofrontal neurons process the specific nature of rewards. These reward signals need to cooperate in order for reward information to be used for learning and maintaining approach behavior.     

Trends in mortality of childhood-onset insulin-dependent diabetes mellitus in Leicestershire: 1940-1991

The relative risk of death by calendar date of diagnosis was investigated in a population-based incident cohort of 845 (463 males:382 females) IDDM diagnosed in Leicestershire before the age of 17 years between 1940 and 1989. The mortality status of 844 (99.9%) patients was determined as of the 31 December 1991, representing 14,346 person-years of risk. Trends in relative risk of death were investigated using Cox proportional hazards modelling for within cohort comparisons and age/sex and calendar time adjusted standardized mortality ratios (SMR) using generalized linear modelling for external comparisons. Median age at diagnosis was 10 years (range 3 months to 16 years); median duration of diabetes 15 years (range 1-51 years). Forty-four patients had died (5.2%; median age at death 31 years, range 11-51 years). A further four patients died at presentation (within 24 h) from ketoacidosis and are excluded from all analyses. Calendar date of diagnosis was found to be an important predictor of mortality. Adjusting for attained age there was evidence of a decline in relative risk of death with calendar date of diagnosis of 3.4% (95% CI, 0.005-6.9%) per annum, equivalent to a 32% fall per decade (95% CI, 5-51%), or 84% (95% CI, 21-97) from 1940 to 1989. The data are consistent with a large fall in mortality between the 1940s and 1950s representing over 50% of the total reduction in mortality between 1940 and 1991. Neither sex nor age at diagnosis were significant predictors of mortality. Over the study period 1940-89 the SMR (male and female combined) fell from 981 (541-1556) to 238 (60-953) relative to the general population. This population-based study shows that the prognosis for Type 1 (insulin-dependent) diabetes mellitus has improved markedly over the period 1940-1991.     

Central alveolar hypoventilation in neurosarcoidosis

Although the lung is almost always involved in sarcoidosis and respiratory failure is not uncommonly caused by intrinsic lung disease, chronic alveolar hypoventilation on the basis of neurosarcoidosis has not been previously described. This report describes the case of a 42-year-old woman with sarcoidosis and documented involvement of the lungs, muscle, peripheral nerves, and skin. She presented with ventilatory failure and a vital capacity of 700mL and required hospitalization for intubation and mechanical ventilation. After failing ventilator weaning attempts and requiring continuous ventilatory assistance, she was extubated to continuous use of noninvasive intermittent positive pressure ventilation (IPPV). She eventually weaned to nocturnal-only use of noninvasive IPPV. However, her PaCO2 remained elevated during daytime hours despite the fact that her vital capacity had returned to 3,600mL. She was not obese, and her oxyhemoglobin saturation (SaO2) was normal on room air. Subsequent attempts to discontinue nocturnal nasal IPPV resulted in marked nocturnal decreases in SaO2 and return of symptoms. This case illustrates successful noninvasive management of an apparently unique occurrence of central alveolar hypoventilation caused by neurosarcoidosis.     

Equivalent oxygen percentage as a function of hydration in hydrogel lenses: an in vivo study

Although many investigations have examined the parameters of hydrogel lens hydration loss, the in vivo effect (in humans) on lens oxygen behavior has not been characterized previously. Human subjects wore 2 different lenses (a thin, 38% water polymacon lens and a thin, 55% water bufilcon lens) for 5-min periods under either fully hydrated (i.e., with saline regularly applied to the lens) or partially hydrated (i.e., with "normal" wear of 1 blink every 5 s) conditions. An equivalent oxygen percentage (EOP) technique and a gravimetric method were used to determine lens oxygen behavior and hydration, respectively. The hydration results demonstrate that significant lens dehydration occurs during the partially hydrated (normal blink rate) condition compared to the in situ, fully hydrated situation. A corresponding, statistically significant diminution in oxygen equivalency was also observed.     

Estimating room temperatures from fires along walls and in corners

Determination of temperatures associated with room fires provides a means of assessing an important aspect of fire hazard: the likelihood of the occurrence of flashover. Layer temperatures in excess of 600°C have been associated with the occurrence of flashover. A data correlation has previously been presented to estimate layer temperatures for fires burning in the center of rooms. For fires in corners and along walls, restricted entrainment results in higher layer temperatures than predicted by the previous correlation. Modification factors for the previous correlation are developed to extend its applicability to wall and corner burning geometries. The present analysis suggests that a fire in a corner may cause flashover with only half the heat release rate necessary for a fire burning in the center of a room. Reference: Frederick Mowrer and Robert Williamson, Estimating Room Temperatures from Fires along Walls and in Corners,Fire Technology, Vol. 23, May 1987, pp. 133–145.     

A STUDY ON THE PERFORMANCE OF THE CATALYTIC POROUS-WALL THREE-PHASE REACTOR

A theoretical investigation of a catalytic porous-wall reactor in which gaseous and liquid reactants approach each other from opposite sides of the catalyst is undertaken. Equations for the annular liquid-channel are coupled with those for the catalytic wall and solved numerically and analytically using a simplified model. For the model reaction under study, the main design and operation parameters which affect reactor performance are the Thiele modulus, Peclet number, width of the liquid channel and the inlet concentration of the reactant in the liquid phase.

The effect of reactor configuration is peculiar to the cylindrical geometry because the thickness and relative location of the catalytic wall as well as the selection of the liquid and gas channels can influence the reactor performance. Thin-walled catalyst tubes have larger effectiveness factors and as the tube radius approaches that of the reactor, conversion in the reactor increases especially when the liquid is saturated with the gaseous reactant. Concentration of the liquid reactant in the feed has a significant effect if the reactant is depleted at some point inside the catalyst wall. Since the reaction zone width can be adjusted by changing the feed composition, this might have important implications with respect to selectivity.