Patient views on the implementation of artificial intelligence in radiotherapy

PURPOSE/OBJECTIVE

To date there has been limited research looking at patient views on the implementation of artificial intelligence (AI) in radiotherapy. The aim of this study is to adapt and utilise a validated patient questionnaire to develop an understanding of current patient views on the use of AI in radiotherapy.

MATERIALS/METHODS

An existing questionnaire, developed to assess understanding of patients' views on the implementation of AI in radiology, was adapted to the field of radiotherapy. The questionnaire was distributed to cancer patients receiving radiotherapy treatment between November 2021 and March 2022. Completed questionnaires were analysed to assess patient levels of positivity or negativity towards AI. Results were grouped into five factors, representing underlying patient perspectives, and correlation of factors with demographic variables was assessed.

RESULTS

In total, 95 patients participated. Overall, there was a moderately negative patient view towards the use of AI in radiotherapy. Certain factors drew a more negative response than others, for example patients desire significant personal interaction with healthcare professionals during the course of their treatment. No significant correlation was found between the demographics of age and gender and the strength of views towards the use of AI in radiotherapy.

CONCLUSION

This study has found that there are clear patient concerns around the use of AI in radiotherapy. As the use of AI in this field increases in future years, it will therefore be extremely important to educate and involve patients in the future direction of this technology.

Neuromuscular fatigue and recovery after strenuous exercise depends on skeletal muscle size and stem cell characteristics

Hamstring muscle injury is highly prevalent in sports involving repeated maximal sprinting. Although neuromuscular fatigue is thought to be a risk factor, the mechanisms underlying the fatigue response to repeated maximal sprints are unclear. Here, we show that repeated maximal sprints induce neuromuscular fatigue accompanied with a prolonged strength loss in hamstring muscles. The immediate hamstring strength loss was linked to both central and peripheral fatigue, while prolonged strength loss was associated with indicators of muscle damage. The kinematic changes immediately after sprinting likely protected fatigued hamstrings from excess elongation stress, while larger hamstring muscle physiological cross-sectional area and lower myoblast:fibroblast ratio appeared to protect against fatigue/damage and improve muscle recovery within the first 48 h after sprinting. We have therefore identified novel mechanisms that likely regulate the fatigue/damage response and initial recovery following repeated maximal sprinting in humans.

Endothelial Cells Exposed to Fluid Shear Stress Support Diffusion Based Maturation of Adult Neural Progenitor Cells

Introduction

The neural stem cell (NSC) niche is a highly complex cellular and biochemical milieu supporting proliferating NSCs and neural progenitor cells (NPCs) with close apposition to the vasculature, primarily comprised of endothelial cells (ECs). Current in vitro models of the niche incorporate EC-derived factors, but do not reflect the physiologically relevant hemodynamic state of the ECs or the spatial resolution observed between cells within the niche.

Methods

In this work, we developed a novel in vitro model of the niche that (1) incorporates ECs cultured with fluid shear stress and (2) fosters paracrine cytokine gradients between ECs and NSCs in a spatiotemporal configuration mimicking the cytoarchitecture of the subventricular niche. A modified cone and plate viscometer was used to generate a shear stress of 10 dynes cm^-2 for ECs cultured on a membrane, while statically cultured NPCs are 10 or 1000 μm below the ECs.

Results

NPCs cultured within 10 μm of dynamic ECs exhibit increased PSA-NCAM⁺ and OLIG2⁺ cells compared to progenitors in all other culture regimes and the hemodynamic EC phenotype results in distinct progeny phenotypes. This co-culture regime yields greater release of pro-neurogenic factors, suggesting a potential mechanism for the observed progenitor maturation.

Conclusions

Based on these results, models incorporating ECs exposed to shear stress allow for paracrine signaling gradients and regulate NPC lineage progression with appropriate niche spatial resolution occurring at 10 μm. This model could be used to evaluate cellular or pharmacological interactions within the healthy, diseased, or aged brain.

How to communicate effectively in graduate advising

This paper completes a two-part series on graduate advising that integrates concepts from adult learning, leadership, and psychology into a conceptual framework for graduate advising. The companion paper discussed how to establish a learning-centered working relationship where advisor and graduate student collaborate in different roles to develop the student’s competence and confidence in all aspects of becoming a scientist. To put these ideas into practice, an advisor and a student need to communicate effectively. Here, we focus on the dynamics of day-to-day interactions and discuss (1) how to provide feedback that builds students’ competence and confidence, (2) how to choose the way we communicate and avoid a mismatch between verbal and nonverbal communication, and (3) how to prevent and resolve conflict. Miscommunication may happen out of a lack of understanding of the psychological aspects of human interactions. Therefore, we draw on concepts from Educational Transactional Analysis to provide advisors and students with an understanding of the psychological aspects of graduate advising as a basis for effective communication. Case studies illustrate the relevance of the concepts presented, and four worksheets ( Supplementary Material ) support their practical implementation.

Complex effects of IL1A polymorphism and calpain inhibitors on interleukin 1 alpha (IL-1 alpha) mRNA levels and secretion of IL-1 alpha protein

Alleles of IL1A-889(C>T) and IL1A+4845(G>T) are in linkage disequilibrium. Interleukin 1alpha (IL-1alpha) is produced as a precursor protein and cleaved at positions 117-118 by calpain, generating a mature protein for export. IL1A+4845 affects amino acids expressed at position 114 and hence may modulate calpain-mediated cleavage. We sought evidence for this mechanism in intact cells. Blood leukocytes from heterozygous donors released more IL-1alpha protein than cells from IL1A(1,1) donors, while release from IL1A(2,2) cells was variable. Genotype did not affect levels of IL-1alpha mRNA, so differential cleavage of the precursor is a feasible mechanism. However, genotype also had no effect on inhibition of IL-1alpha release by pretreatment with calpain inhibitors, and calpain inhibitors reduced IL-1alpha and tumor necrosis factor alpha mRNA levels. Hence, calpain inhibitors probably affect inhibition of signal transduction pathway rather than cleavage of IL-1alpha protein. As ratios of mu-calpain/calpastatin were lowest in heterozygous donors, genetically determined IL-1alpha levels may modulate transcription of calpain and calpastatin. This could reduce the impact of IL1A genotype on IL-1alpha secretion and amplify individual variation in levels generated in culture.

Predictive value for survival of a risk model of two serological markers, beta-2-microglobulin (B2M) and lactic dehydrogenase (LDH), in diffuse large cell lymphoma (DLCL)

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Background: The International Prognostic Index (IPI), the standard tumor risk model in patients (pts) with diffuse large cell lymphoma (DLCL), has 5 factors (age, LDH, performance status, extra nodal sites, and stage). We previously proposed a simpler two-factor model, based on LDH and B2M (JCO10;1989). B2M is a component of HLA class I antigens, expressed in lymphocytes, and a known prognostic indicator in some lymphoid malignancies. The benefits of this model are: objective measures; lab method widely available; simplicity; biologic marker. Methods: We applied the model to a large cohort of DLCL patients with prospective baseline B2M, and treated with doxorubicin-based (chemo) regimens, with and without rituximab. 718 pts with DLCL were sequentially treated at MDACC by IRB approved chemo protocols from 1988–2000. In 2001, rituximab plus chemo (RCHOP) became standard. 311 DLCL pts were sequentially treated with RCHOP from 2001–2005. Cox regression analyses for univariate and multivariate models of IPI factors and B2M were done. Kaplan-Meier survival projections were in three risk categories: low (normal [nl] LDH and B2M); intermediate (either LDH or B2M > nl); or high (LDH and B2M > nl). Results: In both treatment groups, IPI factors and B2M were significant as univariate factors. In the RCHOP group, however, the IPI multivariate model showed age, stage, and extra-nodal sites were not significant risk factors, while B2M and LDH remained highly significant (p<0.01). The 5 year survival projections by risk category were: (*) combines intermediate low and intermediate-high categories Conclusions: This simple two-factor model predicts risk for patients with DLCL, treated with or without rituximab, comparably to the IPI. B2M should be considered an important prognostic indicator in DLCL, particularly in rituximab treated patients. Exploratory analyses to revise the IPI model are indicated.

[Table: see text]

No significant financial relationships to disclose.

R-HCVAD/R-MTX-ARAC is an effective regimen for untreated diffuse large B-cell lymphoma (DLBCL) with aggressive features: M. D. Anderson experience in 40 patients

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Background: R-HCVAD (rituximab-cyclphosphamide, vincristine, dexamethasone, doxorubicin) alternating with R-MTX-ARAC (rituximab, methotrexate-cytarabine) is a chemoimmunotherapy regimen with activity in ALL, mantle cell, and Burkitt’s lymphomas (BL). Histological differentiation between BL, atypical BL, and DLBCL with high-grade features can be difficult. We thus have treated patients with DLBCL with high-grade histological features and/or poor-risk IPI with R-HCVAD. Methods: Forty consecutive patients with information collected prospectively in the NCCN database, treated between 7/2002 and 10/05 at M.D Anderson Cancer Center, and who received at least one cycle are included in this cohort analysis. Characteristics: 18 (45%) male; 18 (45%) HI and High IPI; 25 (62.5%) ↑LDH; 26 (65%) with Stage III/IV; 2 (5%) with PS>1; 8 (20%) with >60 years; 25 (62%) a Ki-67 >90%. Four patients received less than 4 cycles of treatment. Results: ORR was of 100%, with 95% CR/CRu. With a median follow-up of 26 months, 6 patients failed: 1 died in CR of pulmonary embolism while on treatment; 1 patient who achieved CR, had PD before the end of treatment; 1 achieved a PR and was transplanted (is alive in remission); 1 achieved a PR and progressed died of disease; and 2 relapsed (one is in remission after an ASCT). Four patients have died: 3 of disease, 1 of pulmonary embolism. The 3-year OS is 88% (95% CI 77%-99%); 3-year FFS is 71% (95% CI 47%-95%). The 3-year FFS for patients with L/LI risk (3-failures of 22 pts) was 78% (95% CI 52%-100%); and for patients with HI/H IPI (3 failures of 18 pts) 65% (95% CI 27%-100%). Conclusions: R-HCVAD/R-MTC-ARAC is a very active regimen for DLBCL of high grade. Toxicity was mostly hematological. We are currently doing a prospective randomized phase II study comparing this regimen to standard R-CHOP in patients with poor-risk IPI scores.

No significant financial relationships to disclose.

Functional nicotinic acetylcholine receptor expression on stem and progenitor cells of the early embryonic nervous system

Although the adult brain contains nicotinic acetylcholine (ACh) receptors vital to cortical function, little is known about the assembly of embryonic receptor subunits into functional receptors or their role in fetal brain development. We now report the first evidence of functional nicotinic ACh receptors on stem and progenitor cells of fetal mouse cerebral cortex as early as embryonic day 10.

Functional nicotinic acetylcholine receptor expression in stem and progenitor cells of the early embryonic mouse cerebral cortex

The adult cerebral cortex contains nicotinic acetylcholine (ACh) receptors vital to cortical function. However, little is known about the assembly of embryonic nicotinic receptor subunits into functional receptors or whether they play an active role in cortical development. We now report evidence of functional nicotinic acetylcholine receptor channels in fetal mouse cerebral cortex as early as embryonic day 10 (E10), when the cortex consists of dividing stem and progenitor cells. Patch-clamp electrophysiological measurements indicate that nicotine and ACh evoke sizable inward currents characteristic of nicotinic receptors, that are strongly rectifying with a reversal potential near 0 mV. Three different nicotinic agonists, ACh, nicotine, and dimethylphenylpiperazinium, evoked cytosolic Ca(2+) signals. Agonist-evoked Ca(2+) signals and electrophysiological responses were found in greater than 70% of all E10-E11 cells tested and were blocked by nicotinic receptor antagonists. The Ca(2+) response to nicotinic agonists was markedly prolonged in cells from early embryonic stages relative to later stages of development. alpha3, alpha4, and alpha7 receptor subunit proteins were detected immunocytochemically in cortical cells from E10 to birth. The incidence of each subunit declined with embryonic age, suggesting a role in early development. We discuss the possible function of nicotinic receptors in early cortical development and their role as a target for nicotine in the developmental pathologies associated with the fetal tobacco syndrome.

Multipotent stem cells from the mouse basal forebrain contribute GABAergic neurons and oligodendrocytes to the cerebral cortex during embryogenesis

During CNS development, cell migrations play an important role, adding to the cellular complexity of different regions. Earlier studies have shown a robust migration of cells from basal forebrain into the overlying dorsal forebrain during the embryonic period. These immigrant cells include GABAergic neurons that populate the cerebral cortex and hippocampus. In this study we have examined the fate of other basal forebrain cells that migrate into the dorsal forebrain, identifying basal cells using an antibody that recognizes both early (dlx1/2) and late (dlx 5/6) members of the dlx homeobox gene family. We found that a subpopulation of cortical and hippocampal oligodendrocytes are also ventral-derived. We traced the origin of these cells to basal multipotent stem cells capable of generating both GABAergic neurons and oligodendrocytes. A clonal analysis showed that basal forebrain stem cells produce significantly more GABAergic neurons than dorsal forebrain stem cells from the same embryonic age. Moreover, stem cell clones from basal forebrain are significantly more likely to contain both GABAergic neurons and oligodendrocytes than those from dorsal. This indicates that forebrain stem cells are regionally specified. Whereas dlx expression was not detected within basal stem cells growing in culture, these cells produced dlx-positive products that are capable of migration. These data indicate that the developing cerebral cortex incorporates both neuronal and glial products of basal forebrain and suggest that these immigrant cells arise from a common progenitor, a dlx-negative basal forebrain stem cell.

The development of neural stem cells

The discovery of stem cells that can generate neural tissue has raised new possibilities for repairing the nervous system. A rush of papers proclaiming adult stem cell plasticity has fostered the notion that there is essentially one stem cell type that, with the right impetus, can create whatever progeny our heart, liver or other vital organ desires. But studies aimed at understanding the role of stem cells during development have led to a different view - that stem cells are restricted regionally and temporally, and thus not all stem cells are equivalent. Can these views be reconciled?

Timing of CNS cell generation: a programmed sequence of neuron and glial cell production from isolated murine cortical stem cells

Multipotent stem cells that generate both neurons and glia are widespread components of the early neuroepithelium. During CNS development, neurogenesis largely precedes gliogenesis: how is this timing achieved? Using clonal cell culture combined with long-term time-lapse video microscopy, we show that isolated stem cells from the embryonic mouse cerebral cortex exhibit a distinct order of cell-type production: neuroblasts first and glioblasts later. This is accompanied by changes in their capacity to make neurons versus glia and in their response to the mitogen EGF. Hence, multipotent stem cells alter their properties over time and undergo distinct phases of development that play a key role in scheduling production of diverse CNS cells.

CNS development: The obscure origins of adult stem cells

Stem cells of the adult central nervous system are the focus of a great deal of attention because of their potential for making new neural cells. A recent study has claimed to identify their in vivo location, but this important issue remains controversial.

Stem cells in the adult mammalian central nervous system

Over the past year, evidence has accrued that adult CNS stem cells are a widespread progenitor cell type. These cells may normally replace neurons and/or glia in the adult brain and spinal cord. Advances have been made in understanding the signals that regulate stem cell proliferation and differentiation. A deeper understanding of the structure of germinal zones has helped us move towards identifying stem cells in vivo. Recent studies suggest that the fate of stem cell progeny in vivo may be linked to the complexity of the animal's environment.

Detection and Differentiation of Phaeoisariopsis griseola Isolates with the Polymerase Chain Reaction and Group-Specific Primers

Specific detection of the two major groups of Phaeoisariopsis griseola(Andean and Mesoamerican) from infected common bean (Phaseolus vulgaris) leaves was achieved by amplification of different-sized DNA fragments with polymerase chain reaction (PCR) using group-specific primer pairs. These primer pairs were designed based on DNA sequences of cloned random amplified polymorphic DNA (RAPD) fragments. Using this method, P. griseola isolates from diverse geographical regions (five countries) were differentiated into the two previously established groups. Various sources of fungal tissue and DNA extraction methods were tested in order to develop a rapid PCR-based method to detect and differentiate P. griseola isolates. A simple and rapid sonication method was developed that allowed for PCR detection of P. griseola from mycelia or synnemata and conidia collected from angular leaf spot lesions on bean leaves.

Stem cells in the embryonic cerebral cortex: their role in histogenesis and patterning

The cytoarchitectural simplicity of the cerebral cortex makes it an attractive system to study central nervous system (CNS) histogenesis--the process whereby diverse cells are generated in the right numbers at the appropriate place and time. Recently, multipotent stem cells have been implicated in this process, as progenitor cells for diverse types of cortical neurons and glia. Continuous analysis of stem cell clone development reveals stereotyped division patterns within their lineage trees, highly reminiscent of neural lineage trees in arthropods and Caenorhabditis elegans. Given that these division patterns play a critical part in generating diverse neural types in invertebrates, we speculate that they play a similar role in the cortex. Because stereotyped lineage trees can be observed from cells growing at clonal density, cell-intrinsic factors are likely to have a key role in stem cell behavior. Cortical stem cells also respond to environmental signals to alter the types of cells they generate, providing the means for feedback regulation on the germinal zone. Evidence is accumulating that cortical stem cells, influenced by intrinsic programs and environmental signals, actually change with development-for example, by reducing the number and types of neurons they produce. Age-related changes in the stem cell population may have a critical role in orchestrating development; whether these cells truly self-renew is a point of discussion. In summary, we propose that cortical stem cells are the focus of regulatory mechanisms central to the development of the cortical cytoarchitecture.

Cancer among first-degree relatives of probands with invasive and borderline ovarian cancer

OBJECTIVE

The familial clustering of ovarian, breast, endometrial, colon; and prostate cancer was compared in first-degree relatives of probands with invasive and borderline ovarian cancer to determine coaggregation.

METHODS

Probands (n=392), who had been patients in the Division of Gynecologic Oncology at Washington University, were ascertained consecutively. Family history on 2192 first-degree relatives was collected by personal interviews of the probands and other family members. Estimates of prevalence of cancers in first-degree relatives of the two proband groups were compared. Survival analysis was used to examine the age-at-onset distribution of each cancer in relatives of invasive probands versus relatives of borderline probands.

RESULTS

Among the relatives were 24 cases of ovarian cancer, 46 cases of breast cancer, 13 cases of endometrial cancer, and 25 and 28 cases of colon and prostate cancer, respectively. There were no significant differences in the prevalence of any of these cancers in relatives of the invasive and borderline probands. Cumulative lifetime risk estimates did not differ between the relatives of the two groups for any cancers. Age-at-onset of ovarian cancer did not differ between probands with positive family histories of the five cancers and those with negative histories. The inability to reject the null hypothesis of no differences in the first-degree relatives of our two study groups might be from insufficient power to detect small differences, given our sample size.

CONCLUSION

These results suggest that relatives of patients with invasive and borderline ovarian cancer might share similar cancer risks and age-at-onset distributions.

Intrinsic programs of patterned cell lineages in isolated vertebrate CNS ventricular zone cells

Using long-term, time-lapse video-microscopy, we investigated how single progenitor cells isolated from the early embryonic cerebral cortex produce neurons and glia over time. Clones of 10 cells or less were produced by short symmetric or asymmetric division patterns, commonly terminating in a ‘pair progenitor’ for two morphologically identical neurons. Larger trees were composites of these short sub-lineages: more prolific neuroblasts underwent repeated asymmetric divisions, each producing a minor neuroblast that typically made (3/4)10 progeny, and a sister cell capable of generating more progeny. Particular division patterns were seen repeatedly. In contrast, glioblasts underwent a prolonged series of symmetric divisions. These patterned lineage trees were generated from isolated cells growing on plastic, suggesting they are largely intrinsically programmed. Our data demonstrate for the first time that CNS progenitor cells have stereotyped division patterns, and suggest that as in invertebrates, these may play a role in neural development.

Treating inner-city families of homicide victims: a contextually oriented approach

Violence, including youth homicide, has assumed near epidemic proportions in US inner cities, with few signs that such violence is abating. Professionals working with families after the murder of a family member, are faced with the task of helping such families achieve a meaningful restoration of functioning. At the same time, there is a need to prevent retaliatory violence by surviving siblings and other family members. A treatment model will be discussed that uses the basic, theoretical principles of Boszormenyi-Nagy's Contextual Therapy (CT) while incorporating White and Epston's technique of "therapeutic certificates" in work with young people coping with loss via homicide. Case examples, drawn from the author's work at a unique, predominantly African American agency in an urban inner city will be used to illustrate applications of CT principles, and to show how therapeutic certificates can provide tools to clinicians working with this deeply troubling problem.

FGF2 concentration regulates the generation of neurons and glia from multipotent cortical stem cells

The embryonic cerebral cortex contains a population of stem-like founder cells capable of generating large, mixed clones of neurons and glia in vitro. We report that the default state of early cortical stem cells is neuronal, and that stem cells are heterogeneous in the number of neurons that they generate. In low fibroblast growth factor (FGF2) concentrations, most maintain this specification, generating solely neuronal progeny. Oligodendroglial production within these clones is stimulated by a higher, threshold level of FGF2, and astrocyte production requires additional environmental factors. Because most cortical neurons are born before glia in vivo, these data support a model in which the scheduled production of cortical cells involves an intrinsic neuronal program in the early stem cells and exposure to environmental, glia-inducing signals.

Mothers' emotional needs and difficulties after childbirth

OBJECTIVE

To set up and evaluate weekly group sessions for mothers experiencing difficulties after childbirth.

METHOD

These sessions were held at Barwon Region Child Health Centre in Geelong, Victoria, with input from a general practitioner and a clinical psychologist.

RESULTS

Questionnaires confirmed the group sessions were effective in allaying the mothers' concerns about their babies' health, and that the mothers had low self esteem. Records of the meetings indicated that mothers were mainly concerned about their babies' health, anxiety, lifestyle changes, depression, relationship problems, their own health, the birth experience and lack of support. Social factors often predisposed mothers to these problems.

CONCLUSION

There is clearly scope for the general practitioner to be involved in the diagnosis and management of postnatal problems and group sessions are an effective way of achieving this.

Vertebrate neural progenitor cells: subtypes and regulation

Several advances have been made recently in characterizing neural progenitor cells. In vertebrates, multipotential stem cells have been demonstrated in the developing forebrain both in vitro and in vivo, and a class of stem cells has been identified in the adult CNS. Factors that regulate the proliferation and differentiation of subtypes of neural progenitor cells have also been described. In invertebrates, progress has been made in identifying genes involved in neural progenitor cell specification, cell-fate choices and regulation.

Environmental and policy approaches to cardiovascular disease prevention through nutrition: opportunities for state and local action

This article reviews environmental and policy intervention approaches to cardiovascular disease prevention through nutrition and recommends opportunities for state and local health departments to initiate and participate in environmental and nutrition policy initiatives. By addressing these complementary aims, the authors hope to stimulate further efforts to achieve progress in nutrition promotion among state and local health-related organizations. Key categories of opportunity to develop new or expanded nutrition policies and environmental strategies include economic incentives, food assistance and feeding programs, regulations for institutional food service operations, and nutrition services in health care. Environmental strategies to reduce barriers to following dietary guidelines, such as point-of-choice programs and school nutrition programs, should be tailored for local communities and widely disseminated. In addition, current federal policy efforts, notably nutrition labeling rules, will provide a valuable focal point for state and local advocacy, education, and monitoring.

Identification and partial purification of a stage-specific 33 kDa mitochondrial protein as the alternative oxidase of the Trypanosoma brucei brucei bloodstream trypomastigotes

The glycerophosphate oxidase (GPO), the unique terminal oxidase of bloodstream trypanosome (TAO), appears to be functionally similar to the alternative oxidases of some plants and higher fungi. Immunoblotting of mitochondrial proteins of bloodstream trypomastigotes of Trypanosoma brucei with monoclonal or polyclonal antibodies to Sauromatum guttatum (voodoo lily) and Symplocarpus foetidus (skunk cabbage) alternative oxidases respectively revealed two proteins of about 33 kDa (p33) and 68 kDa (p68). These proteins are not present in procyclic trypomastigotes. Electrophoresis under rigorous denaturing conditions indicated p68 to be the dimer of p33. Indirect immunofluorescent studies of bloodstream and procyclic trypomastigotes with monoclonal antibody to plant alternative oxidase also showed the localization of 33 kDa protein in the mitochondria of the bloodstream trypomastigotes. The functional TAO activity could be solubilized efficiently from the mitochondrial membrane of the bloodstream trypomastigotes by 1% NP-40 or 10 mM lauryl maltoside. When fractionated by Superose 12 gel filtration chromatography, p33 was co-purified with the TAO enzymatic activity. The apparent molecular size of the active enzyme complex was found to be 160 kDa. Gradual disappearance of the 33 kDa protein and the TAO enzymatic activity were well correlated during in vitro differentiation of the bloodstream to procyclic trypomastigotes. This study implies that the net biosynthesis of p33, an essential subunit of TAO, is decreased during differentiation from bloodstream to procyclic trypomastigotes.

A self-renewing multipotential stem cell in embryonic rat cerebral cortex

Neuroectoderm cells in the cortical ventricular zone generate many diverse cell types, maintain the ventricular zone during embryonic life and create another germinal layer, the subventricular zone, which persists into adulthood. In other vertebrate tissues, including skin, intestine, blood and neural crest, stem cells are important in maintaining a germinal population and generating differentiated progeny. By following the fates of single ventricular zone cells in culture, we show here that self-renewing, multipotential stem cells are present in the embryonic rat cerebral cortex. Forty per cent of these stem cells produced all three principal cell types of the central nervous system: neurons, astrocytes and oligodendrocytes. Stem cells constituted about 7% of cortical clones; in contrast, over 80% consisted of small numbers of neurons or glia. We suggest that multipotential stem cells may be the ancestors of other cortical progenitor cells that exhibit more limited proliferation and more restricted repertoires of progeny fates.

Isolated rat cortical progenitor cells are maintained in division in vitro by membrane-associated factors

Ventricular zone cells in the developing CNS undergo extensive cell division in vivo and under certain conditions in vitro. The culture conditions that promote cell division have been studied to determine the role that contact with cell membrane associated factors play in the proliferation of these cells. Progenitor cells have been taken from the ventricular zone of developing rat cerebral cortex and placed into microwells. Small clusters of these cells can generate large numbers of neurons and non-neuronal progeny. In contrast, single progenitor cells largely cease division, approximately 90% acquiring neuron-like characteristics by 1 day in vitro. DiI-labeled, single cells from embryonic day 14 cortex plated onto clusters of unmarked progenitor cells have a significantly higher probability (approximately 3-fold) of maintaining a progenitor cell phenotype than if plated onto the plastic substratum around 100 microns away from the clusters. Contact with purified astrocytes also promotes the progenitor cell phenotype, whereas contact with meningeal fibroblasts or balb3T3 cells promotes their differentiation. Membrane homogenates from cortical astrocytes stimulate significantly more incorporation of BrdU by E14 cortical progenitor cells than membrane homogenates from meningeal fibroblasts. These data indicate that the proliferation of rat cortical progenitor cells can be maintained by cell-type specific, membrane-associated factors.

Rat embryonic septal neurons survive and express cholinergic properties in isolation and without nerve growth factor

We studied survival and expression of cholinergic properties in embryonic septal neurons grown in very low density microcultures (1-7 cells per Terasaki well). Even in cultures containing only a single neuron, at least 10% of plated neurons survived for 2 weeks or more in medium containing fetal calf serum or an acid-stable fraction (55,000 Da) of horse serum. Of these surviving neurons, 30-40% stained positively for acetylcholinesterase (AChE) or nerve growth factor (NGF) receptor, even though the culture medium lacked detectable levels of NGF, brain-derived neurotrophic factor, and fibroblast growth factor. Addition of NGF or an antibody against NGF had no effect on either neuronal survival or the percentage of neurons staining positively for AChE or NGF receptor after 18-20 days in vitro. There was no cell division in medium containing the serum fraction, but when 10% fetal calf serum was present cell division occurred in some of the cultures, and in half of these cases at least one of the clonal progeny became AChE-positive. These results demonstrate that some embryonic septal cells can survive at least 2 weeks and develop cholinergic neuronal properties in the absence of other cells or NGF.

Division and differentiation of isolated CNS blast cells in microculture

The mechanism of transformation of the overtly similar cells of the neural plate into the numerous and diverse cell types of the mature vertebrate central nervous system (CNS) can better be understood by studying the clonal development of isolated CNS precursor cells. Here I describe a culture system in which blast cells (cells capable of division) isolated from embryonic day 13.5-14.5 rat forebrain can divide and differentiate into a variety of clonal types. Most clones contain only neurons or glia; 22% contain both neurons and non-neuronal cells. For the division of blast cells, live conditioning cells need to be present indicating that environmental signals influence proliferation. Heterogeneous clones develop in homogeneous culture conditions, so factors intrinsic to the blast cells are probably important in determining the number and type of clonal progeny.

Pulmonary toxicity of trichloroethylene: induction of changes in surfactant phospholipids and phospholipase A2 activity in the mouse lung

Trichloroethylene (TCE) is a common organic solvent in use as a dry cleaning agent as well as an inhalant anesthetic. Nevertheless the effects of this material on the pulmonary surfactant which prevents alveolar collapse at maximal expiration is not known. Therefore, we have examined the effect of TCE on the intra- and extracellular surfactant pools and the activity of phospholipase A2, an enzyme which controls the remodeling of phosphatidylcholine to dipalmitoylphosphatidylcholine, the primary constituent of the pulmonary surfactant. Male CD-1 mice were treated ip with 2500 or 3000 mg/kg TCE. Twenty-four hours later mice were anesthetized and the lungs lavaged. Mice were then killed, the lungs perfused and excised, and subcellular fractions including lamellar bodies prepared. Some lungs were prepared for ultrastructural examination. Phospholipase A2 was assayed in all subcellular fractions. Phospholipid was assayed in the lavage (extracellular surfactant) and the lamellar bodies (intracellular surfactant). TCE (2500 mg/kg) caused selective exfoliation of Clara cells. However, only the dose of 3000 mg/kg TCE produced a significant decrease in the intracellular surfactant phospholipid. Minimal changes occurred in the phospholipid profiles. Phospholipase A2 specific activity was significantly decreased at both dosages within the lung microsomal fraction. In addition after treatment with 3000 mg/kg TCE the enzyme activity in the lamellar body fraction was significantly increased. These data suggest that inhalation of TCE may damage the enzymes which are responsible for synthesizing the pulmonary surfactant resulting in lower amounts of surfactant being stored and available for secretion into the alveolus.

Characterization and comparison of the role of beta-agonists on in vivo and in vitro surfactant-related phospholipid synthesis and secretion by fetal rabbit lung and isolated type II alveolar cells

The role of beta-adrenergic stimulation in surfactant synthesis and secretion was investigated in the fetal lung. Fetuses were treated with isoxsuprine or saline on gestational day 24 by ip injection. Three days later the fetal lungs were lavaged and intracellular surfactant was isolated on a sucrose gradient. Concurrently undifferentiated type II alveolar cells were isolated from 24-day fetal rabbit lung and grown in vitro. In the in vivo portion of the study, examination of surfactant pool sizes revealed that only saline treatment produced a significant elevation in tissue-stored or secreted surfactant compared to untreated controls. Isoxsuprine appeared to inhibit the saline-induced increase. In the case of the intracellular surfactant, the phosphatidylcholine content per gram of lung was significantly increased after saline treatment. In vitro response of isolated type II alveolar cells to isoxsuprine was dependent on prior incubation of the cells for 24 h with conditioned medium. Isoxsuprine stimulated a dose-dependent decrease in the intracellular stores of radioactively labeled DSPC after 24 h of exposure to the drug. A corresponding increase in labeled DSPC in the culture medium was observed. Forth-eight hours after exposure to the drug, those cells that had secreted the highest level of DSPC displayed the highest levels of renewed synthesis of DSPC. This study indicates that the immature fetal lung can be induced to synthesize surfactant-related phospholipid by the stress of laparotomy and/or drug administration. Short-term exposure to beta-agonists is insufficient to stimulate secretion of surfactant stores. In contrast, isolated type II alveolar cells exposed to isoxsuprine respond by secreting DSPC.

Profile of phospholipase A2 activity in subcellular fractions and lamellar bodies of developing, neonatal and adult rabbit lung. Correlation with intracellular levels of disaturated phosphatidylcholine

Phospholipase A2 activity was determined in subcellular fractions and lamellar bodies of fetal, neonatal and adult rabbit lungs. Specific activity in most fractions decreased from the 24th to the 28th day of gestation. All fractions except the mitochondrial and the nuclear fractions exhibited a sharp increase in activity in the newborn lung. Specific activity in the adult lung generally declined in comparison to neonatal values. During gestation total enzyme activity per gram of lung was concentrated in the cytosolic fraction. With the exception of the lamellar body fraction, the total content of phospholipase A2 activity increased dramatically in all fractions from the neonatal lung. The lamellar body fractions displayed both low specific activity and low total enzyme activity during gestation. Specific activity increased dramatically in the neonatal and adult lung but still accounted for only a small fraction of the activity in comparison to the other subcellular fractions. The subcellular content of disaturated phosphatidylcholine (PC) appeared to correlate well with the activity of phospholipase A2 in the neonatal mitochondrial, microsomal and cytosolic fractions. Since decreasing prenatal enzyme levels are associated with increasing disaturated PC content, the alkaline and calcium-dependent phospholipase A2 may not be directly involved in disaturated PC synthesis in the fetus. However, postnatally, the correlation between the pattern of production of disaturated PC and the activity of the phospholipase A2 indicates a role for this enzyme in surfactant-related disaturated PC synthesis.

Characterization and distribution of a phospholipase A2 activity from adult rabbit lung

A phospholipase A2 activity was characterized in adult rabbit lung. This activity was calcium- and deoxycholate-dependent and displayed an alkaline pH optimum. Km and Vmax were 0.176 mM and 256.8 pmoles/min./mg protein respectively. The microsomal fraction displayed the highest enzymatic specific activity; the lowest activity was present in the cytosol. Yet this latter fraction accounted for the majority of the total activity. Although the specific activity was high within the lamellar body fraction this compartment contained only approximately 2% of the total activity. Phospholipase A2 activity was inhibited by bromophenacyl bromide, chlorpromazine and mepacrine in decreasing order of effectiveness. Treatment of the microsomes with increasing concentrations of NaC1 indicated that the lung phospholipase A2 activity was relatively loosely bound to the microsomal membranes and was maximally removed with salt at a concentration only slightly higher than physiological. Addition of calmodulin to the enzyme assay did not significantly alter hydrolysis of labelled phosphatidylcholine.

Changes in translatable poly(A) RNA from differentiated potato tissues transformed with shoot-inducing Ti TL-DNA of Agrobacterium tumefaciens

Two dimensional gel electrophoresis was used to examine differences in steady state total poly(A) RNA from untransformed potato (Solanum tuberosum cv. Maris Bard) and potato transformed with shoot-inducing TL-DNA from A. tumefaciens. RNA was compared from phenotypically very distinct in vitro cultured shoots, more similar grafted plants and tubers. In each case between 200-400 translation products were identified representing the more abundant poly(A) mRNA's. In general, poly(A) RNA from the transformed tissues gave more high molecular weight products. This increase was most evident in poly(A) RNA from shoot cultures. Depending on the tissue examined, 1-5% of the translation products with a molecular weight <43 KD were observed to increase or decrease in abundance. The influence of T-DNA on cellular gene expression in the different transformed potato tissues is discussed in relation to previously determined changes in T-DNA gene expression (particularly of the T-DNA cytokinin gene) and the corresponding changes in endogenous hormone concentrations. It is concluded that some of the specific changes in low molecular weight products are either directly caused by the increased cytokinin levels or are indirectly involved in maintaining the transformed phenotype. re]19850530 rv]19851206 ac]19851210.

Clonal analysis of oligodendrocyte development in culture: evidence for a developmental clock that counts cell divisions

The clonal development of oligodendrocytes was studied by culturing individual oligodendrocyte--type-2 astrocyte (O-2A) progenitor cells on monolayers of type-1 astrocytes, which stimulate O-2A progenitor cells to divide. Oligodendrocytes developed by a proliferative lineage in which clonal progeny differentiated together after a number of cell divisions. Most O-2A progenitor cells had similar cell cycle times (1-2 days), but their proliferative capacity varied greatly: some divided only once while others divided up to eight times before differentiating. sister cells behaved similarly when recultured separately on astrocyte monolayers. These findings are consistent with the cell-division-counting hypothesis previously proposed to explain the timing of oligodendrocyte differentiation. They also unambiguously establish the phenotype of O-2A progenitor cells in vitro and demonstrate that these cells respond directly to growth factors produced by type-1 astrocyte monolayers.

Differentiation of a bipotential glial progenitor cell in a single cell microculture

Although it is known that most cells of the vertebrate central nervous system (CNS) are derived from the neuroepithelial cells of the neural tube, the factors determining whether an individual neuroepithelial cell develops into a particular type of neurone or glial cell remain unknown. A promising model for studying this problem is the bipotential glial progenitor cell in the developing rat optic nerve; this cell differentiates into a particular type of astrocyte (a type-2 astrocyte) if cultured in 10% fetal calf serum (FCS) and into an oligodendrocyte if cultured in serum-free medium. As the oligodendrocyte-type-2 astrocyte (0-2A) progenitor cell can differentiate along either glial pathway in neurone-free cultures, living axons clearly are not required for its differentiation, at least in vitro. However, the studies on 0-2A progenitor cells were carried out in bulk cultures of optic nerve, and so it was possible that other cell-cell interactions were required for differentiation in culture. We show here that 0-2A progenitor cells can differentiate into type-2 astrocytes or oligodendrocytes when grown as isolated cells in microculture, indicating that differentiation along either glial pathway in vitro does not require signals from other CNS cells, apart from the signals provided by components of the culture medium. We also show that single 0-2A progenitor cells can differentiate along either pathway without dividing, supporting our previous studies using 3H-thymidine and suggesting that DNA replication is not required for these cells to choose between the two differentiation programmes.

Coping with spinal cord injury: the family perspective

Little attention has been paid in the literature to the special needs of family members in dealing with the sudden trauma of spinal cord injury and the long-term implications of rehabilitation. Families are often encouraged to participate in rehabilitation plans that do not take their own developmental needs into account. As a result, developmental stresses occur, often expressed as a medical crisis for the spinal cord injured patient. Requests for psychiatric consultation are a frequent initial response of the medical staff to such crisis. Two clinical cases are presented to illustrate this process. Emphasis is placed on family aspects of the cases. Data from family interviews and home visits are used to illustrate the central themes that emerged during consultations. In particular, the data illustrate how family efforts to cope with the needs of their spinal cord injured member have caused them to place inappropriate emphasis on short-term stability of family life, sacrificing, in the process, long-term growth. Recommendations are made regarding the role of the consultation-liaison psychiatrist in the use of this family developmental approach.