Asparaginase Potentiates Glucocorticoid-Induced Osteonecrosis in a Mouse Model

Osteonecrosis is a common dose-limiting toxicity of glucocorticoids. Data from clinical trials suggest that other medications can increase the risk of glucocorticoid-induced osteonecrosis. Here we utilized a mouse model to study the effect of asparaginase treatment on dexamethasone-induced osteonecrosis. Mice receiving asparaginase along with dexamethasone had a higher rate of osteonecrosis than those receiving only dexamethasone after 6 weeks of treatment (44% vs. 10%, P = 0.006). Similarly, epiphyseal arteriopathy, which we have shown to be an initiating event for osteonecrosis, was observed in 58% of mice receiving asparaginase and dexamethasone compared to 17% of mice receiving dexamethasone only (P = 0.007). As in the clinic, greater exposure to asparaginase was associated with greater plasma exposure to dexamethasone (P = 0.0001). This model also recapitulated other clinical risk factors for osteonecrosis, including age at start of treatment, and association with the systemic exposure to dexamethasone (P = 0.027) and asparaginase (P = 0.036). We conclude that asparaginase can potentiate the osteonecrotic effect of glucocorticoids.     

Maintenance of gynodioecy in Wurmbea biglandulosa (Colchicaceae): gender differences in seed production and progeny success

 In gynodioecious species, females contribute genes to future generations only through ovules, and to persist in populations they must have a compensatory advantage compared with hermaphrodites that reproduce via ovules and pollen. This compensation can result from greater fecundity and/or superior success of progeny from females. We examined differences in seed production and progeny success between females and hermaphrodites in the geophyte Wurmbea biglandulosa to explain the maintenance of females. Females produced more ovuliferous flowers and had more ovules per flower than did hermaphrodites but this did not necessarily result in greater fecundity, in part because seed production of females was pollen-limited. Over four years in one population, open-pollinated females produced 1.32 more seeds than open-pollinated hermaphrodites (range 1.09–1.63). In two other populations examined for one year only females produced 1.07 and 0.79 as many seeds as hermaphrodites. Seed production of open-pollinated females and hermaphrodites was only 55% and 73% that of cross-pollinated plants, respectively, indicating that both genders were pollen-limited but females more so than hermaphrodites. Open-pollinated seeds from females were 1.18–1.27 times more likely to germinate than seeds from hermaphrodites. No gender differences existed in seedling growth or survival. Hermaphrodites were self-compatible, but selfed seed set was only 80% that of crossed seed set. Crossed seed set of females and hermaphrodites did not differ. Assuming nuclear control of male sterility, relative female fitness is insufficient to maintain females at their current frequencies of 17%, and substantial female fitness advantages at later life-cycle stages are required. Received May 4, 2001 Accepted February 25, 2002     

An evaluation of the peripheral leukocyte migration inhibition test as a correlate of delayed cutaneous hypersensitivity.

The leukocyte migration inhibition test was used to study the in vitro response to PPD of peripheral blood leukocytes from six Mantoux-positive and five Mantoux-negative volunteers. All tests were performed using both micro and macro versions of the test. Results with the two techniques were usually, but not always similar. Subjects were tested weekly for 6 weeks and variation in the degree of inhibition was noted from week to week. Leukocytes from Mantoux-positive subjects sometimes did not have significant migration inhibition while those from Mantoux-negative subjects sometimes did. Despite this variation the Mantoux-positive subjects both as a group and in most cases individually, had significantly greater mean migration inhibition than the Mantoux-negative subjects. These results suggest that sequential testing rather than a single determination may provide a more meaningful index of cellular immunity.     

The effect of stratification on in vitro protein synthesis in seeds of Pinus lambertiana

Incorporation of ¹⁴C-phenylalanine in $\text{in vitro}$ systems from sugar pine ($\text{Pinus lambertiana}$) seeds was studied. Embryo ribosomes from both dry and stratified seeds supported incorporation (431 and 326 pmoles, respectively, of phenylalanine per mg ribosome) when combined with an embryo pH 5 fraction from stratified seeds. Female gametophyte ribosomes from dry seeds were active (302 pmoles phenylalanine incorporated per mg ribosome) but lost 61 percent of their capacity to support protein synthesis after 35 hours' stratification. The pH 5 fraction from embryos increased in capacity to support incorporation as stratification progressed up to 60 days (398 pmoles phenylalanine per mg ribosome when ribosomes were from 90-day stratified embryos) while the pH 5 fraction from female gametophytes was never active.     

Retraction fibers and leucocyte chemotaxis

Calculation of the attractant concentrations during leucocyte chemotaxis allows the possibility of a multiple-receptor model in which receptors on retraction fibers and the cell body can detect gradients by the absolute differences in concentration between receptors.     

Neuropsychological consequences of volatile substance abuse: a population based study of secondary school pupils.

OBJECTIVE--To examine the effects of volatile substance abuse on neuropsychological functioning. DESIGN--A sample of index children and matched controls were identified by a two stage procedure. Firstly, over 5000 secondary school pupils completed a screening questionnaire, and, secondly, a sample of those who acknowledged volatile substance abuse and a matched sample of those who denied the practice were assessed in detail by means of (a) individually conducted interviews and (b) toxicological examination of breath samples (to exclude those intoxicated at the time of testing). SETTING--16 Local education authority secondary schools in London. SUBJECTS--160 Pupils aged 13-16: 80 index children who had abused volatile substances to the point of intoxication at least once (confirmed by interview) and 80 controls (confirmed by interview) matched for school year, sex, and ethnic background. MEASUREMENTS AND MAIN RESULTS--Neuropsychological functioning tests provided 35 main outcome measures and were administered blind. Data on educational test performance before substance abuse began were obtained retrospectively. Information on potentially confounding social factors, such as number of siblings, tenure of housing, and parents'' socioeconomic and employment state was also obtained. The index children performed significantly less well than the controls in tests of vocabulary, verbal intelligence quotient, full scale intelligence quotient, and a measure of impulsivity. When background social disadvantage was taken into account these differences were no longer significant. There were no significant associations between performance on psychological testing and frequency of abuse, and relations with other aspects of the children''s history of abuse were generally weak or unsystematic. Comparisons between the results of these tests and of educational tests taken before substance abuse produced equivocal findings. CONCLUSION--Volatile substance abuse, as commonly practised by secondary school pupils, is unlikely to result in neuropsychological impairment.     

Patterns of primary care of patients infected with human immunodeficiency virus.

To determine the patterns of care of patients infected with the human immunodeficiency virus (HIV), data from 2 sources were analyzed. Initial data obtained from the Washington State HIV/Acquired Immunodeficiency Syndrome (AIDS) Epidemiology Unit indicate that 46% of patients with class IV AIDS were seen by physicians who reported fewer than 5 patients with AIDS, and 68% of all Washington physicians who reported treating patients with AIDS have reported only 1 patient. Subsequent data obtained from a questionnaire distributed in 4 Northwest states suggest that 74% of primary care internists and 73% of family practitioners have some experience in caring for patients with HIV infection, but most of these physicians report fewer than 6 patients in the past 2 years. Although most providers seeing large numbers of HIV-infected patients in their practices were based in the region''s major metropolitan area, 59% of the internists and 55% of the family practitioners surveyed outside of the metropolitan area had seen at least 1 HIV-infected patient in their practices. These results suggest that primary care physicians with relatively little experience treating HIV infection are providing care for a large number of HIV-infected persons. Further study is needed to determine the extent and quality of care provided.