Dispersal and size fractionation of embryogenic callus increases the frequency of embryo maturation and conversion in hybrid tea roses

Plant regeneration from embryogenic cells of two Rosa hybrida cultivars, Kardinal and Classy, was increased by dispersing embryogenic callus in liquid medium for 3 h followed by size-fractionation to isolate proembryogenic masses that were smaller than 530 microm. Dispersed callus of three cultivars, Kardinal, Classy, and Tineke, produced 61-135 cotyledonary-stage embryos/100 mg fresh weight (FW) as compared to intact callus that had not been dispersed, which produced only zero to three cotyledonary-stage embryos/100 mg FW. Over 500 cotyledonary-stage embryos/100 mg FW callus developed from proembryogenic masses of Kardinal, Classy, and Tineke following 2 months of culture on solidified Murashige and Skoog's basal salts medium supplemented with 0.25% activated charcoal. Cotyledonary-stage embryos of Classy that developed from both dispersed callus and fractionated cells of various sizes showed a significantly higher conversion frequency to plants (28%) than cotyledonary-stage embryos isolated from intact callus (9%). The highest conversion frequencies for Kardinal (50-58%) occurred from cotyledonary-stage embryos that developed from dispersed callus and from the fraction of cells smaller than 850 microm.

Awareness of gambling-related problems, policies and educational programs among high school and college administrators

This brief report summarizes a survey of high school and college representatives and their awareness toward gambling-related problems. The Massachusetts Council on Compulsive Gambling developed a survey instrument to review the policies and training programs of 20 high schools and 10 colleges that were located within the catchment areas of Massachusetts Department of Public Health state-sponsored gambling treatment programs. The results revealed that there is an important discrepancy between the prevalence of gambling-related problems among young people and the awareness of these problems among educators. High school and colleges evidence a paucity of existing gambling-related regulations or policies. There is little opportunity for students and educators to learn within the school setting about gambling and its potential hazards. Without sufficient in-service education and training for faculty and staff, there is little likelihood that this group of educators can engage in the early identification or prevention efforts that are so vital to advancing the health and welfare of young people.

A survey of chronic renal failure in Jamaica

The prevalence of chronic renal failure (CRF)/end stage renal disease and the accessibility of long term renal replacement therapy in Jamaica were evaluated. The study was conducted at six Jamaican healthcare facilities between July 1998 and December 1999 and included 605 patients with CRF. Men with CRF (57% of patients, mean age of 56.7 years) were significantly older than women (mean age 53.2 years). Hypertension was the most commonly associated medical condition (60.8% of patients) followed by diabetes mellitus (31.4% of patients). The estimated crude point prevalence of CRF in persons 20 years and over at the end of 1999 was 327 per million population. More than one-third of patients with CRF (39%) were receiving renal replacement therapy, the most common modality being haemodialysis, and only 1.8% of patients had received kidney transplantation. The prevalence of chronic renal failure was not increased in areas known to have high soil cadmium levels. Chronic renal failure is a significant public health problem in Jamaica and is placing an increasing financial burden on the healthcare sector.

Attention and working memory in resident anaesthetists after night duty: group and individual effects

AIMS

To investigate the effects of a single period of night duty on measures of attention and working memory in a group of residents (registrars) in anaesthesiology. Emphasis was placed on individual deficits using a reference point of the equivalent effect of a blood alcohol concentration (BAC) >0.05% determined by other researchers.

METHODS

There were 33 subjects aged 26-42 years. Night duty was performed on a weekly basis. Baseline assessments were conducted at either 08 15 or 08 55 preceding night duty and repeated 24-25 hours later, just after the completion of duty. Questionnaires included items regarding duration of sleep and the Stanford Sleepiness Scale. A battery of four reaction time (RT) tasks of increasing difficulty, lasting approximately 35 minutes, was administered on a personal computer. These ranged from simple RT to progressively more complex RT tasks incorporating working memory. A significant change was regarded as >15% deterioration in respect of speed or accuracy.

RESULTS

The mean duration of sleep preceding night duty was 7.04 hours and 1.66 hours during the period of night duty. Intergroup comparisons revealed significant prolongation in mean response speed in the first three tests. Mean accuracy was significantly reduced only in respect of the two more complex tests. A >15% deterioration in response speed occurred in up to 30% of subjects on a single task, rising to 52% (17/33) overall. Deterioration occurred in a patchy distribution in most subjects, involving no more than one or two of the four tasks. As regards accuracy, the prevalence of deterioration increased with task complexity.

CONCLUSIONS

Results are in general agreement with previous group analyses. A new dimension was added by the analysis of a broad spectrum of individual response to sleep deprivation. The effects of sleep loss in residents cannot be overlooked, even in a relatively benign work schedule.

Improving the positive predictive value of exercise testing in women

OBJECTIVE

To identify exercise test variables that can improve the positive predictive value of exercise testing in women.

DESIGN

Cohort study.

SETTING

Regional cardiothoracic centre.

SUBJECTS

1286 women and 1801 men referred by primary care physicians to a rapid access chest pain clinic, of whom 160 women and 406 men had ST depression of at least 1 mm during exercise testing. The results for 136 women and 124 men with positive exercise tests were analysed.

MAIN OUTCOME MEASURES

The proportion of women with a positive exercise test who could be identified as being at low risk for prognostic coronary heart disease and the resulting improvement in the positive predictive value.

RESULTS

Independently of age, an exercise time of more than six minutes, a maximum heart rate of more than 150 beats/min, and an ST recovery time of less than one minute were the variables that best identified women at low risk. One to three of these variables identified between 11.8% and 41.2% of women as being at low risk, with a risk for prognostic disease of between 0-11.5%. The positive predictive value for the remaining women was improved from 47.8% up to 61.5%, and the number of normal angiograms was potentially reducible by between 21.1-54.9%. By the same criteria, men had higher risks for prognostic disease.

CONCLUSIONS

A strategy of discriminating true from false positive exercise tests is worthwhile in women but less successful in men.

A potential mechanism for age-related declines in patellar tendon biomechanics

Injuries to soft tissues such as tendons are becoming ever more frequent among the elderly. While increasing levels of activity likely contribute to these injuries, age-related declines in tendon strength may also be important. Whether these declines in biomechanical properties are associated with changes in fibril diameter or collagen type remains in question. In this study, age-related changes were investigated in patellar tendons from young adult rabbits (1-year old, n = 17) and from rabbits at the onset of senescence (4-year old, n = 33). Patellar tendon biomechanics was correlated with both collagen fibril diameter and with the presence of type V collagen, a known regulator of collagen fibril diameter. We hypothesize that (a) aging from I to 4 years results in significant reductions in patellar tendon biomechanical properties, and (b) these age-related declines are associated with smaller fibril diameters and with the presence of type V collagen. Maximum stress declined 25% between I and 4 years of age (100.7 +/- 5.6 MPa and 74.3 +/- 3.4 MPa, respectively, p < 0.0003) (mean +/- SEM) and strain energy density declined 40% (p < 0.001). The distribution of collagen fibrils from 4-year old rabbits was skewed significantly towards smaller diameters compared to fibrils from 1-year old rabbits (p < 0.001). Type V collagen was observed only in the 4-year old rabbit tendons. These correlations suggest that with increasing age after skeletal maturity, type V collagen may help to regulate the assembly and thus diameter of collagen fibrils and thereby adversely affect patellar tendon strength.