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Distinct developmental patterns of short-term and long-term functioning lymphoid and myeloid precursors defined by competitive limiting dilution analysis in vivo.

Functional abilities of individual marrow precursor cells were defined by competitive limiting dilution without enrichment, tissue culture, or induced marking, manipulations that might affect cell functions. We directly measured long-term repopulating abilities in limiting doses (0.25-1.0 x 10(5)) of genetically marked congenic marrow cells. These were mixed with a standard dose of 4 or 5 x 10(5) competitor marrow cells, which contained a predictable distribution of precursor cells and allowed quantitative assays. Percentages of donor type T and B lymphocytes, granulocytes, platelets, and erythrocytes were measured in recipient blood. Applying the maximum likelihood statistic, concentrations (per 10(5)) of precursors repopulating at least one lineage were: 4.7 and 6.0 after 6 wk, 1.6 and 2.7 after 14 to 15 wk, and 1.2 and 1.9 after 30 to 32 wk; concentrations repopulating at least three lineages were 2.3 and 3.4 after 6 wk, 0.9 and 1.7 after 14 to 15 wk, and 0.9 and 1.3 after 32 wk. Almost all precursors functioning after 14 wk repopulated all lineages. At 6 wk, similar levels of donor cells were produced in recipients of both short- and long-term precursors. However, after 14 to 32 wk, contributions by short-term precursors (about two-thirds of the precursors) dropped to zero, while contributions by long-term precursors (about one-quarter of the precursors) expanded severalfold. The latter permanently repopulated all lineages after 30 to 32 wk, functioning as the most primitive stem cells (PSC) in the immune and myeloid systems. Nearly all the variance in long-term repopulated recipients was explained using the Poisson distribution to calculate donor percentages in a model where each donor and competitor PSC contributed equally.

Animals↗

Effects of short-term and long-term treatment with inhaled corticosteroids on bone metabolism in patients with airways obstruction. Dutch CNSLD Study Group.

BACKGROUND: Recent reports have suggested short-term changes in serum parameters of bone metabolism with inhaled corticosteroids. The relevance of these findings to the balance between bone formation and resorption during years of corticosteroid treatment remains uncertain. METHODS: Two novel markers of bone turnover were first compared with conventional markers in a pilot study and subsequently measured in a long-term double blind study of inhaled corticosteroids. In study I 15 patients were newly started on at least 800 micrograms inhaled corticosteroids daily. At entry and after four weeks serum levels of alkaline phosphatase, osteocalcin, and PICP (procollagen type I carboxy terminal propeptide; a procollagen splice product) were measured as markers of bone formation, as well as the urinary hydroxyproline/creatinine ratio and serum levels of ICTP (type I collagen carboxy terminal telopeptide; a collagen degradation product) as markers of bone resorption. In study II 70 patients with airways obstruction received 800 micrograms beclomethasone daily in addition to terbutaline and 85 received bronchodilators only in a double blind fashion. Serum levels of PICP and ICTP were measured before and after 2.5 years of treatment. RESULTS: In study I a decrease in osteocalcin levels was accompanied by an increase in levels of PICP and a small and non-significant rise in alkaline phosphatase. There were no changes in hydroxyproline or ICTP. In study II no differences were found in serum levels of PICP between the treatment groups; an increase in serum ICTP was found in the group treated without inhaled corticosteroids compared with the group treated with inhaled corticosteroids. CONCLUSIONS: No detrimental long-term effect of inhaled corticosteroids was found with three conventional and two novel parameters of bone metabolism. The results indicate that long-term changes in bone turnover during treatment with inhaled corticosteroids should not be deduced from short-term studies with single serum parameters of bone metabolism, but well designed long-term studies of, for example, bone densitometry should be awaited before quoting detrimental effects of inhaled corticosteroids on bone metabolism.

Administration, Inhalation↗

The support of the long term neurological cripple.

The term 'long term neurological cripple' is an unattractive and yet an all embracing one, covering a wide spectrum of disorders from spina bifida or cerebral palsy with or without associated epilepsy and behavioural and learning problems, through muscular dystrophy, multiple sclerosis, and motor neurone disease, to the effects of head injury, cerebrovascular lesions and the degenerative disorders of later life such as Parkinson's disease and the senile and presenile dementias. Whilst many of the problems are common to several of these entities, each has its own particular aspects.

Adolescent↗

[The mathematical modelling of Ca2(+)-dependent postsynaptic processes in the hippocampus (the induction of long-term potentiation and long-term depression)].

The computational model was put forward of calcium-dependent posttetanic processes in the dendritic spine of CA3 hippocampal pyramidal neuron which received excitatory and inhibitory afferents. The system of differential equations enables description and evaluation of changes in protein kinase and protein phosphatase activity induced by changes in postsynaptic Ca2+ ion concentration (Cap2+). It was shown that the synaptic efficacy is determined by the ratio between active protein kinases and active protein phosphatase I. According to the proposed model, increase/decrease in Cap2+ concentration relative to the Cap2+ rise, produced by prior stimulation, results in the increase/decrease in the number of phosphorylated ionotropic receptors and in LTP/LTD synaptic efficacy. It follows form the model calculations that the same mechanisms underlie the LTP, LTD, and depotentiation. Some results of experimental study of the hippocampal and neocortical synaptic plasticity are explained and systematized.

Animals↗

Use of multispectral magnetic resonance imaging analysis to quantify erosive changes in the hands of patients with rheumatoid arthritis: short-term and long-term longitudinal studies.

OBJECTIVE: Magnetic resonance imaging (MRI) has been shown to be more sensitive than radiography for detecting bone erosions in rheumatoid arthritis (RA). Semiquantitative scoring based on visual image assessment has been introduced. However, there is considerable interest in true quantitative measures, particularly in the context of clinical trials designed to show differences between treatment groups. This study was undertaken to investigate the use of a new quantitative approach, multispectral (MS) image analysis, for assessing erosive change. METHODS: T1-weighted spin-echo (SE) and fat-suppressed gradient-echo (GE) sequences of metacarpophalangeal joints of the dominant hand were acquired at various time points throughout a 2-year period. MS analysis was applied to all images, resulting in segmentation into a generalized bone and a soft tissue class. Voxel changes from one to the other class identified apparent bone lesion volume change (Delta BLV). MR images were also visually scored for erosions (E score). All analyses were performed separately, on a per-joint basis, for short-term and long-term data sets. RESULTS: Analysis of variance with adjustment for individual effect revealed similar results in the short-term and the long-term studies, using either GE or SE images for visual assessment. Patients with an increase in E score on visual assessment had a significantly higher Delta BLV than those without. CONCLUSION: Temporal MS analysis of MRIs can be used to detect and quantify erosive changes in RA. This semiautomated method may be useful for demonstrating differences between treatment groups in clinical trials.

Adult↗

[The influence of aging on short-term and long-term memory in the continuous recognition paradigm].

The continuous recognition paradigm was employed to examine age-related performance deficit in short-term and long-term memory. Three age groups of people: young, young-old, and old-old, participated in the study, which used words of high and intermediate familiarity. With intervals used as criteria for separation of short-term (STM) and long-term (LTM) memory, hit rate and reaction time (RT) were computed separately. Although not significantly different in STM, hit rate in LTM decreased as the participant got older. No difference in RT for young-old and old-old groups was found for STM and LTM of high familiarity words, but the difference was significant for LTM of intermediate familiarity. RT was longer for intermediate than high familiarity words for both young-old and old-old groups in LTM, and only for old-old group in STM. These results indicated that although age differences in memory performance were not very large, different influence of aging on encoding, storage, and retrieval processes could be inferred.

Adolescent↗

Short-term versus long-term longitudinal changes in processing speed.

BACKGROUND: Previous longitudinal studies of cognitive aging have focused on long-term performance changes. A recent surge of research has demonstrated that there are reliable interindividual differences in short-term cognitive performance changes. OBJECTIVE: The present study links these two pathways of cognitive aging research by examining the association between short-term (learning, practice) versus long-term (development) changes in processing speed. METHODS: Data from 963 elderly participants come from the Longitudinal Aging Study Amsterdam (LASA). RESULTS: Nested latent growth curve analyses show that the amount of learning or practice in processing speed at first measurement occasion is positively related (r = 0.72) to individual differences in development of processing speed across 6 years. CONCLUSIONS: Short-term learning or practice gains in processing speed are positively associated with long-term developmental changes in processing speed in the elderly.

Aged↗

Antimicrobial use in long-term-care facilities. SHEA Long-Term-Care Committee.

There is intense antimicrobial use in long-term-care facilities (LTCFs), and studies repeatedly document that much of this use is inappropriate. The current crisis in antimicrobial resistance, which encompasses the LTCF, heightens concerns of antimicrobial use. Attempts to improve antimicrobial use in the LTCF are complicated by characteristics of the patient population, limited availability of diagnostic tests, and the virtual absence of relevant clinical trials. This position paper recommends approaches to management of common infections in LTCF patients and proposes minimal standards for an antimicrobial review program. In developing these recommendations, the position paper acknowledges the unique aspects of provision of care in the LTCF.

Aged↗

Prefrontal grey-matter changes in short-term and long-term abstinent methamphetamine abusers.

Authors explored grey-matter density in 29 methamphetamine abusers and 20 healthy comparison subjects using voxel-based morphometry. Grey-matter density changes and performances on the Wisconsin Card Sorting test (WCST) were also compared between 11 short-term (<6 months) and 18 long-term (>or=6 months) abstinent methamphetamine abusers. Methamphetamine abusers had lower grey-matter density in the right middle frontal cortex (corrected p<0.05) and more total errors in the WCST (p<0.01) relative to healthy comparison subjects. Grey-matter density decrease in the right middle frontal cortex correlated with total errors in the WCST in methamphetamine abusers (r=-0.45). Long-term abstinent abusers had significantly less right middle frontal grey-matter density decrease (p<0.01) and total errors in the WCST (p<0.01) than short-term abstinent abusers, but more than the healthy comparison subjects. We report that methamphetamine abusers have prefrontal grey-matter deficit, which may, in part, recover with long-term abstinence.

Adult↗

[Short-term and long-term prognosis of recession-resection surgery for exotropia].

The short- and long-term results of recession-resection surgery on 141 exotropic patients were analyzed. The corrected angle of exodeviation one week after surgery was not affected by age at surgery, state of binocular vision or the type of intermittent exotropia. The corrected exodeviation was larger when the pre-operative exodeviation exceeded 30 prism diopters or when previous surgery had been performed. Since there was no difference between the angle of deviation at 4 and 8 years postoperatively, the period of four years was considered to be appropriate for long-term assessment. Post-operative exophoria of less than 15 prism diopters were obtained in patients whose short-term results were overcorrected or were under 5 prism diopters of exodeviation. The surgical guideline for exotropia should be determined considering the short-term and the long-term prognosis. It was concluded that the optimal time for surgery was between 5 and 10 years of age.

Adolescent↗

Effectiveness of short-term and long-term zidovudine prophylaxis on detection of HIV-1 subtype E in human placenta and vertical transmission.

Antiretroviral treatment with zidovudine (ZDV) from the 14th week until the end of pregnancy has markedly reduced the vertical transmission rate of HIV-1 in Europe and North America. A shorter duration of treatment has reduced this rate in Africa and Southeast Asia to a lesser degree. In Southeast Asia, subtype E is the major subtype rather than subtype B as in Western countries. The goals of this study were to determine the optimal duration of ZDV prophylaxis for subtype E and to confirm its effectiveness at the histologic level. Fifty pregnant women seropositive for HIV-1 subtype E were given ZDV prophylaxis consisting of 300 mg administered twice daily, switching to 300 mg administered every 3 hours from the onset of labor until delivery. Twenty-seven received "short-term" ZDV lasting 14 to 35 days before delivery, whereas the other 23 received "long-term" ZDV lasting 62 to 92 days. The effectiveness of ZDV prophylaxis was assessed by detection of HIV-1 in the placenta using in situ polymerase chain reaction (PCR). All babies in this study were tested up to one year of age. Three were not positive until after one month of age, but one was positive as a neonate. Four neonates were positive for HIV-1 as detected by PCR on peripheral blood, including one in the neonatal period. All cases were from the short-term prophylaxis group. Decidual glandular epithelial cells were the only cell type in the placenta that expressed HIV proviral DNA under ZDV prophylaxis. Sixty-seven percent of placentas in the short-term ZDV group showed more than occasional positive cells compared with 22% in the group receiving long-term ZDV prophylaxis (P < 0.02). This is first study to compare the effectiveness of short-term and long-term ZDV prophylaxis with respect to the presence of HIV in the placenta. Our study shows that longer (at least 60 days) prophylaxis is more effective in reducing HIV expression in the placenta and is associated with reduced transmission to neonates.

Anti-HIV Agents↗

Ethical considerations of the short-term and long-term health impacts, costs, and educational value of sustainable development projects.

There are over 800 seventh to tenth grade students at the College d'Enseignment Generale (CEG) School in Azové, Benin. Like most children in the developing world, these students lack access to clean water and basic sanitation facilities. These students suffer from parasitic infection and health ailments which could be directly offset with short term aid to supply water and medical aid. Promoting proper sanitation and providing the technology to implement water and wastewater treatment in the community will decrease childhood and maternal disease and mortality rates in Azové. However, these measures may take several years to implement and will require a significant investment in the infrastructure of the school. Is it ethical to spend 10,000 dollars towards the long-term goals of providing water and sanitation to the students of CEG Azové, compared to spending the same amount on short-term relief efforts? This paper addresses the ethical dilemma of dealing with immediate medical needs in developing countries while trying to implement sustainable technologies. The views and frustration of students working on the project are discussed, as they realize the monetary and short-term impacts on human health when implementing sustainable technologies. The opportunity costs associated with the education principles of sustainable development were also considered. The anticipated costs and health impacts in the short-term and long-term will be evaluated for a period of 1, 2, 5 and 10 years. Sustainable development requires a new way of thinking, and a long-term approach. These problems will require the dedication of a new generation of engineers, working hand-in-hand with local communities and governments, social scientists, economists, businesses, human rights organizations, other non-government organizations, and international development organizations. Design projects encourage the professional and ethical development of engineers through hands-on involvement in national and international development projects.

Child↗

Coexistence of muscarinic long-term depression with electrically induced long-term potentiation and depression at CA3-CA1 synapses.

Our laboratory recently characterized a form of long-term depression (LTD) at CA3-CA1 synapses mediated by M1 muscarinic receptors (mAChRs), termed muscarinic LTD (mLTD). mLTD is both activity and NMDAR dependent, characteristics shared by forms of synaptic plasticity thought to be relevant to learning and memory, including long-term potentiation (LTP) induced by high-frequency stimulation (HFS-LTP) and long-term depression induced by low-frequency stimulation (LFS-LTD). However, it remains unclear whether mLTD can occur sequentially with these electrically induced forms of hippocampal plasticity or whether mLTD might interact with them. The first goal of this study was to examine the interplay of mLTD and HFS-LTP. We report that mLTD expression does not alter subsequent induction of HFS-LTP and, further, at synapses expressing HFS-LTP, mLTD can mediate a novel form of depotentiation. The second goal was to determine whether mLTD would alter LFS-LTD induction and/or expression. Although we show that mLTD is occluded by saturation of LFS-LTD, suggesting mechanistic similarity between these two plasticities, saturation of mLTD does not occlude LFS-LTD. Surprisingly, however, the LFS-LTD that follows cholinergic receptor activation is NMDAR independent, indicating that application of muscarinic agonist induces a change in the induction mechanism required for LFS-LTD. These data demonstrate that mLTD can coexist with electrically induced forms of synaptic plasticity and support the hypothesis that mLTD is one of the mechanisms by which the cholinergic system modulates hippocampal function.

2-Amino-5-phosphonovalerate↗