A multi-emitter fitting algorithm for potential live cell super-resolution imaging over a wide range of molecular densities.

Multi-emitter fitting algorithms have been developed to improve the temporal resolution of single-molecule switching nanoscopy, but the molecular density range they can analyse is narrow and the computation required is intensive, significantly limiting their practical application. Here, we propose a computationally fast method, wedged template matching (WTM), an algorithm that uses a template matching technique to localise molecules at any overlapping molecular density from sparse to ultrahigh density with subdiffraction resolution. WTM achieves the localization of overlapping molecules at densities up to 600 molecules µm-2 with a high detection sensitivity and fast computational speed. WTM also shows localization precision comparable with that of DAOSTORM (an algorithm for high-density super-resolution microscopy), at densities up to 20 molecules µm-2 , and better than DAOSTORM at higher molecular densities. The application of WTM to a high-density biological sample image demonstrated that it resolved protein dynamics from live cell images with subdiffraction resolution and a temporal resolution of several hundred milliseconds or less through a significant reduction in the number of camera images required for a high-density reconstruction. WTM algorithm is a computationally fast, multi-emitter fitting algorithm that can analyse over a wide range of molecular densities. The algorithm is available through the website. https://doi.org/10.17632/bf3z6xpn5j.1.

A case of a rare variant of Klinefelter syndrome, 47,XY,i(X)(q10).

Klinefelter syndrome is a condition in which a male patient has one Y chromosome and one or more extra X chromosomes. It is the most common sex chromosome disorder. Klinefelter syndrome is distinguished by many clinical features, such as infertility, high gonadotropin and low testosterone levels, increased height, and sparse body and facial hair. We report the case of a 32-year-old man who visited our hospital complaining of male infertility. Semen analysis showed azoospermia, and chromosomal analysis revealed a 47,XY,i(X)(q10) karyotype, which is a rare variant of Klinefelter syndrome. No spermatozoon was found on microdissection testicular sperm extraction, and the testis biopsy histology showed only Sertoli cells and hyalinised seminiferous tubules. 47,XY, i(X)(q10) has an additional isochromosome made of the long arm of the X chromosome, which shares some features of classical Klinefelter syndrome in many aspects, but patients are usually shorter than average height and have normal intelligence. In addition, to the best of our knowledge, no successful sperm extractions from 47,XY, i(X)(q10) patients were reported in the literature. The reports of patients who have undergone microdissection testicular sperm extraction are very rare. Further reports and studies of this chromosomal abnormality are needed.

Post-traumatic stress disorder associated with natural and human-made disasters in the World Mental Health Surveys.

BACKGROUND: Research on post-traumatic stress disorder (PTSD) following natural and human-made disasters has been undertaken for more than three decades. Although PTSD prevalence estimates vary widely, most are in the 20-40% range in disaster-focused studies but considerably lower (3-5%) in the few general population epidemiological surveys that evaluated disaster-related PTSD as part of a broader clinical assessment. The World Mental Health (WMH) Surveys provide an opportunity to examine disaster-related PTSD in representative general population surveys across a much wider range of sites than in previous studies. METHOD: Although disaster-related PTSD was evaluated in 18 WMH surveys, only six in high-income countries had enough respondents for a risk factor analysis. Predictors considered were socio-demographics, disaster characteristics, and pre-disaster vulnerability factors (childhood family adversities, prior traumatic experiences, and prior mental disorders). RESULTS: Disaster-related PTSD prevalence was 0.0-3.8% among adult (ages 18+) WMH respondents and was significantly related to high education, serious injury or death of someone close, forced displacement from home, and pre-existing vulnerabilities (prior childhood family adversities, other traumas, and mental disorders). Of PTSD cases 44.5% were among the 5% of respondents classified by the model as having highest PTSD risk. CONCLUSION: Disaster-related PTSD is uncommon in high-income WMH countries. Risk factors are consistent with prior research: severity of exposure, history of prior stress exposure, and pre-existing mental disorders. The high concentration of PTSD among respondents with high predicted risk in our model supports the focus of screening assessments that identify disaster survivors most in need of preventive interventions.

Barriers to mental health treatment: results from the WHO World Mental Health surveys.

BACKGROUND: To examine barriers to initiation and continuation of mental health treatment among individuals with common mental disorders. METHOD: Data were from the World Health Organization (WHO) World Mental Health (WMH) surveys. Representative household samples were interviewed face to face in 24 countries. Reasons to initiate and continue treatment were examined in a subsample (n = 63,678) and analyzed at different levels of clinical severity. RESULTS: Among those with a DSM-IV disorder in the past 12 months, low perceived need was the most common reason for not initiating treatment and more common among moderate and mild than severe cases. Women and younger people with disorders were more likely to recognize a need for treatment. A desire to handle the problem on one's own was the most common barrier among respondents with a disorder who perceived a need for treatment (63.8%). Attitudinal barriers were much more important than structural barriers to both initiating and continuing treatment. However, attitudinal barriers dominated for mild-moderate cases and structural barriers for severe cases. Perceived ineffectiveness of treatment was the most commonly reported reason for treatment drop-out (39.3%), followed by negative experiences with treatment providers (26.9% of respondents with severe disorders). CONCLUSIONS: Low perceived need and attitudinal barriers are the major barriers to seeking and staying in treatment among individuals with common mental disorders worldwide. Apart from targeting structural barriers, mainly in countries with poor resources, increasing population mental health literacy is an important endeavor worldwide.

Age-adjusted relative suicide risk by marital and employment status over the past 25 years in Japan.

BACKGROUND: There have been no longitudinal studies in Japan examining national-level data for suicide risk by marital and employment status. We examined the age-adjusted relative suicide risk (RR) by marital and employment status from national data acquired for all suicides in Japan occurring in the past 25 years. METHODS: All deaths identified as suicides according to ICD-9 and ICD-10 were extracted from vital statistics data of Japan for the years 1980, 1985, 1990, 1995, 2000 and 2005. Population statistics for Japanese residents aged ≥15 years were obtained from the census. RESULTS: Suicide rates for almost all categories analyzed decreased in both genders between 1985 and 1990 and increased between 1995 and 2000, especially among men. Unemployed and divorced men had a consistently higher RR in each year analyzed. Unemployed and divorced women had a higher risk than those in other categories, especially in 2000 and 2005. In women, particularly in 1980, 1985 and 1990, those who were unemployed and never married had a similar RR to those who were unemployed and divorced. CONCLUSIONS: Unemployed and divorced people were at a high risk of suicide over the past 25 years, particularly in 2000 and 2005. Our findings suggest that the effects of divorce and unemployment on suicide risk are synergistic.

Gender and the relationship between marital status and first onset of mood, anxiety and substance use disorders.

BACKGROUND: Prior research on whether marriage is equally beneficial to the mental health of men and women is inconsistent due to methodological variation. This study addresses some prior methodological limitations and investigates gender differences in the association of first marriage and being previously married, with subsequent first onset of a range of mental disorders. METHOD: Cross-sectional household surveys in 15 countries from the WHO World Mental Health survey initiative (n=34493), with structured diagnostic assessment of mental disorders using the Composite International Diagnostic Interview 3.0. Discrete-time survival analyses assessed the interaction of gender and marital status in the association with first onset of mood, anxiety and substance use disorders. RESULTS: Marriage (versus never married) was associated with reduced risk of first onset of most mental disorders in both genders; but for substance use disorders this reduced risk was stronger among women, and for depression and panic disorder it was confined to men. Being previously married (versus stably married) was associated with increased risk of all disorders in both genders; but for substance use disorders, this increased risk was stronger among women and for depression it was stronger among men. CONCLUSIONS: Marriage was associated with reduced risk of the first onset of most mental disorders in both men and women but there were gender differences in the associations between marital status and onset of depressive and substance use disorders. These differences may be related to gender differences in the experience of multiple role demands within marriage, especially those concerning parenting.

Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor.

We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.

Depression-anxiety relationships with chronic physical conditions: results from the World Mental Health Surveys.

BACKGROUND: Prior research on the association between affective disorders and physical conditions has been carried out in developed countries, usually in clinical populations, on a limited range of mental disorders and physical conditions, and has seldom taken into account the comorbidity between depressive and anxiety disorders. METHODS: Eighteen general population surveys were carried out among adults in 17 countries as part of the World Mental Health Surveys initiative (N=42, 249). DSM-IV depressive and anxiety disorders were assessed using face-to-face interviews with the Composite International Diagnostic Interview (CIDI 3.0). Chronic physical conditions were ascertained via a standard checklist. The relationship between mental disorders and physical conditions was assessed by considering depressive and anxiety disorders independently (depression without anxiety; anxiety without depression) and conjointly (depression plus anxiety). RESULTS: All physical conditions were significantly associated with depressive and/or anxiety disorders but there was variation in the strength of association (ORs 1.2-4.5). Non-comorbid depressive and anxiety disorders were associated in equal degree with physical conditions. Comorbid depressive-anxiety disorder was more strongly associated with several physical conditions than were single mental disorders. LIMITATIONS: Physical conditions were ascertained via self report, though for a number of conditions this was self-report of diagnosis by a physician. CONCLUSIONS: Given the prevalence and clinical consequences of the co-occurrence of mental and physical disorders, attention to their comorbidity should remain a clinical and research priority.

Plasma homocysteine and MTHFR C677T genotype in levodopa-treated patients with PD.

Plasma homocysteine and cysteine levels were measured in 90 patients with PD with the MTHFR C677T (T/T) genotype. The authors found that the levels of homocysteine-a possible risk factor for vascular disease-were elevated by 60% in levodopa-treated patients with PD, with the most marked elevation occurring in patients with the T/T genotype. Cysteine levels in subjects with PD did not differ from levels in control subjects. In the T/T genotype patients, homocysteine and folate levels were inversely correlated. Increased homocysteine might be related to levodopa, MTHFR genotype, and folate in PD.

Astrocyte-dependent and -independent phases of the development and survival of rat embryonic day 14 mesencephalic, dopaminergic neurons in culture.

A primary neuronal culture was prepared from the ventral mesencephalon, centered on the A8, A9 and A10 dopaminergic nuclei of the embryonic day 14 rat, and studied from 12 h to 28 days. At 12 h after plating, and before cell death ensued, 95% of the cells stained positive for neuron specific enolase; 20% for tyrosine hydroxylase; 5% for vimentin and < 0.1% for glial fibrillary acidic protein. In the presence of the mitotic inhibitor cytosine arabinoside (2.0 microM), neuronal growth and survival were surprisingly normal up to the ninth day in culture, but deteriorated rapidly thereafter. In the absence of a mitotic inhibitor, and in the presence of proliferating but non-confluent glia, the tyrosine hydroxylase positive neurons that survived to the 10th day, had retracted neurites and a rounded soma, suggesting an inhibition of cell development. Those tyrosine hydroxylase positive neurons that survived this adverse phase of development tended to produce elaborate neuritic profiles after the 11th day, coincident with confluence of the astrocyte monolayer at the 12th day. By the 21st day in culture, and persisting up to the 28th day, 60% (61 +/- 10, n = 20) of the surviving neurons stained positive for tyrosine hydroxylase. When plated on an established, ventral mesencephalic monolayer of astrocytes, at the seventh day in culture, neuritic growth and branching of the tyrosine hydroxylase positive neurons were greater, compared with similar neurons grown on poly-D-lysine, and the signs of arrested development (retraction of neurites and rounded soma) seen at the 10th day after plating on poly-D-lysine, were not observed. We conclude that in the primary culture studied, and under the experimental conditions used, the survival of dopaminergic neurons was independent of glia during the first nine days, and critically dependent on glia thereafter. The resurgence of growth of dopaminergic neurons after 10 days in vitro, and their subsequent selective survival in culture, suggest that confluent type-1 astrocytes produce factors that act selectively on the dopaminergic neuronal phenotype. The successful identification of these dopaminergic-specific, neurotrophic factors could lead to an increased understanding of the etiology of Parkinson's disease, and suggest new directions for therapeutic intervention.

An immortalized, type-1 astrocyte of mesencephalic origin source of a dopaminergic neurotrophic factor.

Rat embryonic d 14 (E14) mesencephalic cells, 2.5% of which are glioblasts, were incubated in medium containing 10% of fetal bovine serum for 12 h and subsequently expanded in a serum-free medium using basic fibroblast growth factor (bFGF) as the mitogen. On a single occasion, after more than 15 d in culture, several islets of proliferating, glial-like cells were observed in one dish. The cells, when isolated and passaged, proliferated rapidly in either a serum-free or serum-containing growth medium. Subsequent immunocytochemical analysis showed that they stained positive for GFAP and vimentin, and negative for A2B5, O4, GalC, and MAP2. Serum-free conditioned medium (CM) prepared from these cells caused a fivefold increase in survival and promoted neuritic expansion of E14 mesencephalic dopaminergic neurons in culture. These actions are similar to those exerted by CM derived from primary, mesencephalic type-1 astrocytes. The pattern of expression of the region-selective genes; wnt-1, en-1, sis showed that 70% of the cells were heteroploid, and of these, 50% were tetraploid. No apparent decline in proliferative capacity has been observed after 25 passages. The properties of this cell line, named ventral mesencephalic cell line one (VMCL1), are consistent with those of an immortalized, type-1 astrocyte. The mesencephalic origin of the cell line, and the pattern and potency of the neurotrophic activity exerted by the CM, strongly suggest that the neurotrophic factor(s) identified are novel, and will likely be strong candidates with clinical utility for the treatment of Parkinson's disease.

The homozygous C677T mutation in the methylenetetrahydrofolate reductase gene is a genetic risk factor for migraine.

Increased homocysteine levels are associated with various pathological conditions in humans, including stroke and cardiovascular disorders. Homocysteine acts as an excitatory amino acid in vivo and may influence the threshold of migraine headache. Frosst et al. [1995] reported an association between the homozygous C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene and serum homocysteine levels. This study was designed to determine the prevalence of the MTHFR mutation in Japanese patients with migraine and tension-type headache (TH). Seventy-four patients with migraine headaches (22 with aura and 52 without aura), 47 with THs, and 261 normal controls were recruited. Genotyping of MTHFR C677T polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism. We detected that the incidence of the homozygous transition (T/T) in migraine sufferers (20.3%) was significantly higher than that in controls (9.6%). Moreover, the frequency of the T/T genotype in individuals with migraine headaches with aura was remarkably high (40.9%). The MTHFR T allele was more frequent in the migraine group than in the control group. Our results support the conclusion that the MTHFR gene, causing mild hyperhomocysteinemia may be a genetic risk factor for migraine. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:762-764, 2000.

Monospecific antiserum to rat spermidine synthase and its application to rat tissues and several mammals.

Monospecific antiserum to rat spermidine synthase was prepared by immunization of rabbits with purified enzyme protein from rat prostate, and its usefulness for analysis of spermidine synthase protein in not only rat tissues but also several other mammals was demonstrated by Western blotting and immunotitration of the enzyme activity. Application of the antiserum for elucidating the relationship between the enzyme activity and protein in normal rat tissues strongly suggested that marked difference in spermidine synthase activity among rat tissues depends solely on the difference in the amount of enzyme protein. Also, application of the antiserum for analyzing spermidine synthase from liver of mouse, rat, guinea pig, pig, and human, showed that the enzymes had a similar subunit molecular weight of 35,000 and a cross-reactivity with the antiserum, exhibiting almost the same immunoreactivity to mouse enzyme as to rat enzyme. Thus, it was suggested that the antiserum would be useful for further studies of mammalian spermidine synthase from the viewpoints of enzymology and molecular biology.

Effects of transforming growth factors on dopaminergic neurons in culture.

It was recently reported that TGF-beta 1 either had no significant effect on or increased the survival of dopaminergic neurons in culture. TGF-beta 2 and TGF-beta 3 were reported to cause increased survival or to greatly inhibit survival. The transforming growth factors are a highly pleiotropic group of compounds, and the above results suggest that their actions may be critically dependent on the conditions of the assay. We have therefore tested these compounds under optimal conditions of culture, in a medium containing a low (2.5%) concentration of fetal bovine serum. TGF-beta 2 and 3 inhibited neuronal (MAP2-pos) survival only at the highest concentration (10 ng/ml) tested, while inhibition of survival of dopaminergic neurons was observed at 1.0 and 10 ng/ml. These results therefore suggest that the inhibitory action of TGF-beta 2 and 3 on the survival of dopaminergic neurons in culture, under the experimental conditions outlined, may be relatively specific.

Increased survival of dopaminergic neurons by rasagiline, a monoamine oxidase B inhibitor.

Both deprenyl and rasagiline (R(+)-N-propargyl-1-aminoindane mesylate), at a concentration of 1-10 microM, increased survival in vitro of rat E14 mesencephalic dopaminergic neurons that had been primed with 10% serum for 12 h (p < 0.05). Rasagiline, but not deprenyl, also increased total neuronal (MAP2-positive) survival (p < 0.05) Under serum-free conditions, rasagiline, but not deprenyl, retained its neuroprotective action on dopaminergic neurones. GABAergic neurons were not affected by either deprenyl or rasagiline. Clorgyline, an MAO-A inhibitor, did not exert any of these effects. The protective action of rasagiline on dopaminergic neurons, even under stringent serum-free conditions, is striking, and warrants further investigation for a role in the treatment of Parkinson's disease.

GAPDH knockdown rescues mesencephalic dopaminergic neurons from MPP+ -induced apoptosis.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) has a number of diverse functions apart from glycolytic function. We explored the possible involvement of GAPDH in 1-methyl-4-phenylpyridinium (MPP+)-induced death of mesencephalic dopaminergic neurons (MDNs) in culture. MPP+ (10 and 20 microM, 24 h) exposure selectively decreased the survival of tyrosine hydroxylase positive (TH+) MDNs, which manifested apoptotic features including shrinkage of the cell body, chromatin condensation and nuclear fragmentation. Two types of GAPDH antisense oligonucleotides almost completely rescued MDNs from MPP+ toxicity. GAPDH was strongly expressed in apoptotic TH+ neurons, and MPP+ exposure significantly increased the percentage of TH+ neurons in which GAPDH is over-expressed. Confocal microscopic analysis demonstrated the nuclear accumulation of GAPDH in neurons undergoing MPP+-induced apoptosis. These results suggest that MPP+ causes apoptosis of MDNs, concomitant with the over-expression and nuclear accumulation of GAPDH.

Standardized methods to bioassay neurotrophic factors for dopaminergic neurons.

The search for specific neurotrophic factors that will eventually be used to reduce or arrest the rate of degeneration of dopaminergic neurons in Parkinson's disease is being pursued by first testing the ability of putative compounds to increase the survival of dopaminergic neurons in primary cultures of the fetal, ventral mesencephalon. This research has intensified in recent years. The experimental procedures used by different laboratories in these studies differ widely, and meaningful comparisons of the results obtained are accordingly difficult to make. Some important experimental variables include the age of the fetal tissue used; the dissection technique used to isolate the ventral mesencephalon; the percentage of dopaminergic neurons present in the culture initially; handling of the tissue during dissection; the technique used to disperse the cells; the use of serum; the technique of plating the cells; the attachment factors used; detachment and loss of cells during the staining procedure; the age of the cultures at the time of analysis; the uneven distribution of cells at the time of analysis and the use of imaging techniques in the analysis. We show that when the E14 rat embryo is used, it is possible to consistently obtain a culture with 20% of tyrosine hydroxylase-positive neurons. Neither the plating density in the range of 7.8 x 10(3) to 1.25 x 10(5) cells/cm2, nor the percentage of serum in the growth medium affected the percentage of cells that expressed TH initially, at 4 or 12 h after plating. When the cells were plated as 25 microliters droplets, called microislands (area approximately 12.5 mm2), and allowed to attach before additional growth medium was added, cell density remained uniform at the center of the microisland for the duration of the culture. Restriction of the analysis of cell survival to the center of the microisland therefore helped to decrease the variability in counting that could occur when cells are dispersed over a larger area. In contrast, in an 8-well chamber slide or 35 mm petri dish, in which the whole area is plated, cell density was consistently higher at the edge (edge effect), versus the centre, by a factor of about three. The use of microisland cultures also has the additional benefit of increasing by a factor of about five the number of individual cultures that can be set up per liter, and a proportionate reduction in the number of animals used per experiment. When the percentage of serum in the growth medium was 0% always, or 10% for the first 12 h, and 0% thereafter, or 10% always, the number of TH-pos neurons per field (using a x 20 objective, column factor 1.25; area 320 microns2) after 5 days in culture (DIV5) was < 1,3-8 and 14-22, respectively. Under the same experimental conditions, the number of neurons (MAP2-positive) per field was 5-8, 18-30 and 45-65 (N = 10 in all cases), respectively. Serum deprivation therefore has a highly deleterious effect on neuronal survival in culture. We suggest that cultures that were exposed to serum at any stage of the experiment, should not be referred to as "serum-free', since even a brief exposure to serum exerts a protective effect on neurons, and especially on dopaminergic neurons. Instead, the percentage and kind of serum used, the exact usage, and the duration of exposure of the cells to serum should be stated. Finally, it is suggested that where possible, an imaging system with manual count and journaling capabilities be used in the analysis. The methods described are illustrated by dose-response curves of the neurotrophic effects of BDNF, NGF-beta and IL-6 versus percentage survival on dopaminergic neurons, when grown in serum-free medium throughout.

Production of dopaminergic neurons for cell therapy in the treatment of Parkinson's disease.

Dopaminergic cell therapy is a potential viable treatment for Parkinson's disease. However, lack of a well-characterized cell preparation of known phenotypic composition containing a high percentage of dopaminergic neurons, has prevented a definitive, controlled, pilot clinical trial from being conducted. We report the successful in vitro expansion of rat E12 mesencephalic progenitors to produce 5-fold the normal number of dopaminergic neurons. The expanded neurons (MAP2+) were detached, resuspended, and formed into small aggregates of 10-200 neurons containing 25-50% of dopaminergic neurons (TH+) that will likely be optimal for use in successful cell therapy. After storage in DPBS, in 0 mM Ca(2+) for up to 24 h at room temperature, aggregated cells were still 90% viable. These results demonstrate that it might be feasible to use a similar protocol to expand human dopaminergic progenitors in vitro. If successful, the requisite large numbers of dopaminergic neurons required to conduct a pilot clinical trial for Parkinson's disease will be produced in vitro. Indications are that the cells can be maintained at optimal viability for the duration of the neural transplantation procedure, under real operating conditions.

C1-esterase inhibitor reduces infarct volume after cortical vein occlusion.

In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood flow (rCBF) decreased after occlusion, and was about 50% of baseline after 2 h. No difference was noted between experimental groups. Mean arterial blood pressure (MABP) and arterial blood gases were likewise unaffected by the treatment. However, administration of C1-INH had significantly reduced infarct volume by 72%, as evaluated after 5 days survival. Thus, the neuroprotective effect cannot be explained by an improvement of cerebral perfusion but rather by protection of the parenchyma in the penumbra.

Oligodendrocyte-type-2 astrocyte (O-2A) progenitors increase the survival of rat mesencephalic, dopaminergic neurons from death induced by serum deprivation.

When a primary culture of E16 rat striatal cells was grown in a serum-free medium, treatment with basic fibroblast growth factor (bFGF, 10 ng/ml) caused the generation of the progenitor cell for oligodendrocytes and type-2 astrocytes (O-2A). Immunostaining tests confirmed that > 90% of the cells were positive for A2B5, and < 5% positive for glial fibrillary acidic protein (GFAP). When E14, mesencephalic, dopaminergic neurons were co-cultured with established O-2A progenitor cells in a serum-free growth medium, the survival of tyrosine hydroxylase-positive (TH+) neurons increased 23-fold and 668-fold at the 5th and 10th days, respectively, compared with control cultures plated on poly-D-lysine. Conditioned medium from the O-2A progenitor cultures also decreased the death of TH+ neurons. The mitotic inhibitor, cytosine arabinoside (1.0 microM), did not block the protective effect of the O-2A progenitor cells. O-2A progenitor cells produce a potent, soluble factor, that mediates the increased survival of dopaminergic neurons in vitro.