Neurobehavioral properties of chemical sensitivity syndromes

Chemical sensitivity Syndromes refers to aggregations of symptoms marked by largely subjective neurobehavioral complaints and hypothesized links to immune system dysfunction. The entities reviewed here consist of the Multiple Chemical Sensitivity Syndrome, the Sick Building Syndrome, the Chronic Fatigue Syndrome, and the Gulf War Syndrome. Except for the Chronic Fatigue Syndrome, toxic chemical exposures are accorded a significant role in their etiology. The connections are ambiguous because of the variety of chemical agents cited and, for the most part, the relatively low levels at which exposures occur. Conventional clinical signs are also typically lacking. Explanatory mechanisms include psychiatric diagnoses such as somatization, behavioral mechanisms such as conditioning and generalization, neuropharmacological mechanisms such as sensitization, and psychoneuroimmunological mechanisms such as those involving the hypothalamic-pituitary-adrenal axis. Laboratory animal experimentation and controlled clinical trials, especially with inhaled material, provide the means for exploring the proffered explanations.

Common and specific features of childhood psychopathology

This article describes a conceptual and data-analytic model for characterizing different levels of common and specific features of child psychopathology: common features, which differentiate psychopathology from normality; broadband-specific features, which differentiate internalizing problems (e.g., anxiety, somatization) from externalizing problems (e.g., aggression, hyperactivity); and narrowband-specific features, which differentiate different narrowband syndromes (e.g., anxiety from somatization, hyperactivity from aggression) within each of the broadband syndromes. As an illustration of the model, data for 6 cognitive variables (e.g., global self-worth, causal attributions) are related to 6 psychopathology domains (e.g., aggression, depression) in a sample of 204 children. It is suggested that common features may be related to severity of psychopathology, whereas specific features may be more related to differentiation of psychopathology.

Prenatal cocaine exposure produces gender-specific motor effects in aged rats

This investigation employed a longitudinal analysis of a complex motor skill in rats that were exposed prenatally to cocaine. Offspring were derived from four maternal treatment groups: 50 mg/kg cocaine, their pair-fed controls, 25 mg/kg cocaine, and freely fed controls. Cocaine was administered via gavage from gestation day 6-20. A maternal fostering procedure was used. Pairs of male and female littermates began training when 9, 13, or 19 months old. The behavioral procedure involved fixed-ratio (FR) lever pressing to obtain brief periods of wheel running. The oldest males from the 50 mg/kg, 25 mg/kg, and pair-fed groups performed significantly fewer wheel revolutions per opportunity than females or freely fed males. In general, animals earned fewer opportunities to run as the FR requirement was increased over sessions. However, within each age-by-gender group, subjects from the four treatment groups performed equivalent amounts of lever pressing. The specific effect on the motor aspect of the procedure may have resulted from a reduction of motor coordination, balance, or strength, or a diminished capacity of wheel running to serve as a reinforcing stimulus in a cocaine-sensitive subgroup.

Endonuclease V (nfi) mutant of Escherichia coli K-12

Endonuclease V (deoxyinosine 3' endonuclease), the product of the nfi gene, has a specificity that encompasses DNAs containing dIMP, abasic sites, base mismatches, uracil, and even untreated single-stranded DNA. To determine its importance in DNA repair pathways, nfi insertion mutants and overproducers (strains bearing nfi plasmids) were constructed. The mutants displayed a twofold increase in spontaneous mutations for several markers and an increased sensitivity to killing by bleomycin and nitrofurantoin. An nfi mutation increased both cellular resistance to and mutability by nitrous acid. This agent should generate potential cleavage sites for the enzyme by deaminating dAMP and dCMP in DNA to dIMP and dUMP, respectively. Relative to that of a wild-type strain, an nfi mutant displayed a 12- to 1,000-fold increase in the frequency of nitrite-induced mutations to streptomycin resistance, which are known to occur in A x T base pairs. An nfi mutation also enhanced the lethality caused by a combined deficiency of exonuclease III and dUTPase, which has been attributed to unrepaired abasic sites. However, neither the deficiency nor the overproduction of endonuclease V affected the growth of the single-stranded DNA phages M13 or phiX174 nor of Uracil-containing bacteriophage lambda. These results suggest that endonuclease V has a significant role in the repair of deaminated deoxyadenosine (deoxyinosine) and abasic sites in DNA, but there was no evidence for its cleavage in vivo of single-stranded or uracil-containing DNA.

A risk assessment perspective on the neurobehavioral toxicity of endocrine disruptors

Agents that alter the functional properties of endocrine systems pervade the environment. Their full implications for public health and ecological integrity, however, may not be captured by labels such as "disruptor" because their actions ramify in so many directions. The process by which we describe and evaluate such actions, risk assessment, is also the means by which society judges their significance. It determines the allocation of resources to their investigation and, potentially, control. A full, formal, risk assessment endeavor, in the detail applied to cancer evaluation, still awaits application to endocrine disruptors, however. It will not be as transparent a process because, unlike the conventional risk model based on carcinogens, identification of a chemical as an endocrine disruptor, as is true of neurobehavioral toxicants in general, will not trigger a virtually automatic sequence of policy steps. The primary distinction between cancer and endocrine disruptors and neurotoxicants is the plethora of possible endpoints by which toxicity can be expressed. Cancer is a unitary index. Adverse consequences flowing from exposure to endocrine disruptors can take an almost infinite variety of forms, including neurobehavioral outcomes. In their most troubling manifestations, these emerge as disorders of early development. They can range from deviant patterns of male copulatory behavior to impaired cognitive function. Each of these indices, in turn, exhibits multiple dimensions. Moreover, some aftermaths, as with cancer, might emerge only after long latencies. Different stages of the life cycle following developmental exposure will manifest different outcomes as a consequence. Some adverse effects may arise for the first time in advanced age because it is a period of declining compensatory margins. These multiple facets of neurobehavioral toxicity, and, by extension, their coupling to endocrine disruptors, imply a risk assessment process that corresponds, in many ways, to the global views adopted by ecotoxicologists.

Human and murine serine-palmitoyl-CoA transferase--cloning, expression and characterization of the key enzyme in sphingolipid synthesis

Serine palmitoyltransferase (SPT, EC 2.3.1.50) is the key enzyme in sphingolipid biosynthesis. It catalyzes the pyridoxal-5'-phosphate-dependent condensation of L-serine and palmitoyl-CoA to 3-oxosphinganine. Human expressed-sequence-tag (EST) clones are similar to the two yeast genes for synthesis of long-chain bases, LCB1 and LCB2, which are believed to encode two subunits of SPT [Buede, R., Pinto, W. J., Lester, R. L. & Dickson, R. C. (1991) J. Bacteriol. 173, 4325-5332; Nagiec, M. M., Baltisberger, J. A., Wells, G. B., Lester, R. L. & Dickson, R. C. (1994) Proc. Natl Acad. Sci. USA 91, 7899-7902]. We have cloned and characterized two complete human and murine cDNA sequences named hLCB1 & mLCB1 and hLCB2 & mLCB2, respectively, similar to the yeast LCB1 and LCB2 genes. Human embryonic kidney cells (HEK 293) transfected with murine sequences of LCB1 (mLCB1) and LCB2 (mLCB2) independently and in coexpression showed an overexpression of the transcripts on the mRNA and protein level. The enzymatic activity of cells expressing mLCB2 alone or coexpressed with mLCB1 was three times higher than the activity of untransfected HEK cells. mLCB1 expression was not required for the synthesis of 3-oxo-sphinganine in mammalian cells. Transcription/translation in vitro yielded mLCB1 (53 kDa) and mLCB2 (63 kDa). The two proteins do not contain a signal peptide nor are they glycosylated. The endogenous and overexpressed SPT activity were both sensitive to common SPT inhibitors. Labeling studies with [1-(14)C]palmitic acid indicated that cell lines transfected with mLCB2 preferentially use the excess sphingoid bases for glucocerebroside and galactocerebroside synthesis. Our results provide conclusive genetic and biochemical evidence that the human and murine LCB2 genes described here encode serine palmitoyltransferase. Further studies will be required to unravel the function of the LCB1 gene in mammalian cells.

Expression of a D2 dopamine receptor antisense RNA in brain inhibits D2-mediated behaviors

Drugs currently used to treat disorders of dopamine-mediated behaviors in the central nervous system are non-selective in that they interact not only with more than one isoform of dopamine receptor but also with receptors for other neurotransmitters. A new strategy to inhibit the actions of individual dopamine receptor subtypes is to inhibit the synthesis of the receptors through the use of oligonucleotides antisense to the transcripts encoding the different receptors. Earlier studies showed that oligodeoxynucleotides antisense to the D1 or D2 dopamine receptor messenger RNAs specifically inhibited the biological actions mediated by these individual isoforms of the dopamine receptor. However, these actions were relatively short-lasting. To determine whether one can achieve long-lasting inhibition of dopamine responses, while still taking advantage of the highly selective nature of an antisense strategy, an expression vector was employed that generates antisense RNA to the transcript encoding the D2 dopamine receptor. A single intrastriatal injection of this vector generated an antisense RNA to the D2 dopamine receptor, selectively reduced the levels of D2 dopamine receptors, and caused selective, long-term inhibition of behaviors mediated by D2 dopamine agonists. Such an antisense RNA strategy may find use in studying the function of dopaminergic receptors and in disorders associated with dopaminergic hyperactivity.

Endocrine disruptors and sexually dimorphic behaviors: a question of heads and tails

Early brain development seems destined to be the territory where questions about the neurotoxicity of endocrine disruptors will be contested, so we ought to clarify how we propose to invade it. Everything else we have learned tells us that the most sensitive indices are likely to be the most subtle, a term we often use to describe the phenomena and domain of neurobehavioral toxicology. It might mean an effect that is small in amplitude, or that requires sensitive measures to detect. One class of effects that might result from environmental exposure to endocrine disruptors reflects both kinds of subtlety. It consists of sexually dimorphic behaviors that seem biologically driven but that could easily masquerade as socially-defined or gender differences. Performances on neuropsychological tests fall into this category. Beyond debates about their origins, such differences tend to be relatively modest in size, especially by the routine criteria adopted by toxicologists. Overwhelmingly, they rely on differences in means accompanied by p values. Such criteria are inappropriate for assessing hypotheses or calculating risks based on the impact of what invariably will be quite low environmental levels. In this arena at least, the quantification of effects should proceed from examinations of distributions. Instead of conventional descriptions based on measures of central tendency, we should instead examine the shapes of distributions, especially the tails. Neuropsychological differences between males and females are amplified and emerge at the extremes, even when sex accounts for no more than a minuscule proportion of the variance. Lead taught a similar lesson about how to quantify population impacts. Furthermore, such differences at the extremes suggest both practical and theoretical implications that can too easily be ignored but that provide paths for fruitful exploration.

Antisense strategies in neurobiology

The use of antisense oligodeoxynucleotides, targeted to the transcripts encoding biologically active proteins in the nervous system, provides a novel and highly selective means to further our understanding of the function of these proteins. Recent studies of these agents also suggest the possibility of their being used therapeutically for a variety of diseases involving neuronal tissue. In this paper we review studies showing the in vitro and in vivo effects of antisense oligodeoxynucleotides as they relate to neurobiological functions. Particular attention is paid to the behavioral and biochemical effects of antisense oligodeoxynucleotides directed to the various subtypes of receptors for the neurotransmitter dopamine. An example is also provided showing the effects of a plasmid vector expressing an antisense RNA targeted to the calmodulin mRNAs in the PC12 pheochromocytoma cell line. The advantages of antisense oligodeoxynucleotides over traditional pharmacological treatments are assessed, and the advantages of using vectors encoding antisense RNA over the use of antisense oligodeoxynucleotides are also considered. We also describe the criteria that should be used in designing antisense oligodeoxynucleotides and several controls that should be employed to assure their specificity of action.

FISH-deletion mapping defines a 270-kb short stature critical interval in the pseudoautosomal region PAR1 on human sex chromosomes

Deletions of the pseudoautosomal region (PAR1) of the sex chromosomes have recently been discovered in individuals with short stature, and a minimal common deletion region of 700 kb within PAR1 has subsequently been defined. We have cloned this entire region, which is bounded by the Xp/Yp telomere, as an overlapping cosmid contig. In the present study, we have used fluorescence in situ hybridization (FISH) to study four patients with X-chromosomal rearrangements, two with normal height and two with short stature. Genotype-phenotype correlations have narrowed down the the critical "short stature interval" to a 270-kb region containing the gene with an important role in growth. A minimal tiling path of 6-8 cosmids bridging this interval is now available for interphase and metaphase FISH and provides a valuable tool for diagnostic investigations of patients with idiopathic short stature.

Teratogenicity of methanol following a single oral dose in Long-Evans rats

The teratogenicity of methanol was investigated following a single oral exposure preceded by an equal volume of mineral oil to guard against local gastric irritation. Four groups of pregnant Long-Evans rats were gavaged on day 10 of gestation with the following solutions: 0.0 (n = 13), 1.3 (n = 12), 2.6 (n = 11), and 5.2 (n = 10) mL MeOH/kg. Wilson sectioning (head only), gross necropsy, and Alizarin red skeletal examinations were performed on day 20 of gestation. At 5.2 mL/kg, the dams demonstrated > 20% decrease in weight gain in comparison to the control, which was the only clinical toxic manifestation or histopathologic change noted for the dams. Methanol at all doses failed to produce any significant change in standard reproductive indices (e.g., postimplantation loss). A significant decrease in fetal body weight (11 to 19.5%), however, was associated with prenatal oral ingestion of methanol. Both internal and external examination of the fetuses demonstrated a dose-dependent increase in anomalies [0 = 0.6%, 1.3 mL/kg = 3.7%, 2.6 mL/kg = 7%, 5.2 mL/kg = 16.5% (litter percents)]. The dose-related anomalies were undescended testes, exophthalmia, and anophthalmia. Thus, acute methanol given orally produces anomalies, even when there is no apparent maternal toxic response.

Evidence that therapy works in clinically representative conditions

This article reports a secondary analysis of past therapy outcome meta-analysis. Fifteen meta-analysis provided effect sizes from 56 studies in previous reviews that met 1 of 3 increasingly stringent levels of criteria for clinical representativeness. The effect sizes were synthesized and compared with results from the original meta-analyses. Effect sizes from more clinically representative studies are the same size at all 3 criteria levels as in past meta-analyses. Almost no studies exist that meet the most stringent level of criteria. Results are interpreted cautiously because of controversy about what criteria best capture the notion of clinical representativeness, because so few experiments have tested therapy in clinical conditions, and because other models for exploring the generalizability of therapy outcome research to clinical conditions might yield different results.

Effect of co-occurrence on the referability of internalizing and externalizing problem behavior in adolescents

Assessed the effect of co-occurring versus not co-occurring internalizing and externalizing behavior problems on the reasons parents reported for clinical referral of their adolescent child. Reasons for referral were coded for 181 inpatient adolescents, and parent ratings of internalizing and externalizing behavior were obtained for a general population sample of 500 adolescents. Parents concurrently reported internalizing and externalizing behavior as reasons for referral less frequently (p < .0001) than would be expected given the correlation between these two domains in the general population sample. This suggests that the presence of externalizing problems may decrease parents' concern or awareness of internalizing problems, the presence of internalizing problems may decrease parents' concern or awareness of externalizing problems, or both. Implications for the clinical referral of adolescents and for informal parental efforts at helping their children with externalizing and internalizing problems are discussed.

Pseudoautosomal deletions encompassing a novel homeobox gene cause growth failure in idiopathic short stature and Turner syndrome

Growth retardation resulting in short stature is a major concern for parents and due to its great variety of causes, a complex diagnostic challenge for clinicians. A major locus involved in linear growth has been implicated within the pseudoautosomal region (PAR1) of the human sex chromosomes. We have determined an interval of 170 kb of DNA within PAR1 which was deleted in 36 individuals with short stature and different rearrangements on Xp22 or Yp11.3. This deletion was not detected in any of the relatives with normal stature or in a further 30 individuals with rearrangements on Xp22 or Yp11.3 with normal height. We have isolated a homeobox-containing gene (SHOX) from this region, which has at least two alternatively spliced forms, encoding proteins with different patterns of expression. We also identified one functionally significant SHOX mutation by screening 91 individuals with idiopathic short stature. Our data suggest an involvement of SHOX in idiopathic growth retardation and in the short stature phenotype of Turner syndrome patients.

Perinatal methanol exposure in the rat. II. Behavioral effects in neonates and adults

The use of methanol as a component of automobile fuel will increase perinatal exposures in the general population. Few studies have addressed questions concerning neurotoxicity stemming from such exposures. In the current study, four cohorts of pregnant Long-Evans rats, each cohort consisting of an exposure and a control group, were exposed to 4500 ppm methanol vapor in Rochester-type inhalation chambers for 6 hr daily beginning on Gestation Day 6. Exposure continued for both dams and pups through Postnatal Day 21 (PND 21) to model gestational and neonatal toxicity in humans. Several behavioral procedures were used to assess exposure effects in the offspring. Male-female littermates were studied whenever possible to examine sex differences, with one pair from a litter for each procedure. Exposure to methanol did not affect suckling latency and nipple attachment on PND 5 or performance on an aversive olfactory conditioning procedure on PND 10. Exposure to methanol did alter performances in a motor activity procedure. Methanol-exposed neonates were less active on PND 18, but more active on PND 25 than the equivalent control group pups. Two operant conditioning procedures, not used previously in this context, assayed other littermates as adults. A fixed ratio schedule required the rat to rotate a running wheel a specified number of revolutions to obtain food-pellet reinforcers. When the fixed ratio requirement changed, number of responses (revolutions) per 1-hr session displayed a complex interaction with treatment. Changes in performance over the course of training differed between males and females depending on exposure to methanol. Compared to initial baseline performances, methanol-exposed males showed decreases, and methanol-exposed females increases, in the rate of running. A stochastic spatial discrimination procedure permitted subjects to respond on any three levers, with the probabilities of food-pellet delivery determined by the location of the preceding response. A reinforcement matrix defined the response sequence required to maximize reinforcements. When the matrix was changed, the methanol-exposed subjects responded less efficiently at asymptotic levels of performance than controls. Across procedures, developmental exposure to 4500 ppm methanol vapor was associated with subtle behavioral changes in both neonates and adults.

Experimental strategies for research on multiple chemical sensitivity

Skepticism about the validity of the multiple chemical sensitivity (MCS) syndrome stems in part from the lack of supporting experimental data. Performing the relevant experiments requires investigators to take account of broad variations in sensitivity and the need to establish reproducibility. The research approach best suited for MCS studies is the single-subject design. In contrast with conventional group designs, such designs emphasize repeated observations on individual subjects. Repeated observations of this kind constitute a time series in which successive measurements are serially or autocorrelated. One statistical method that bypasses the serial correlation problem is randomization tests. Explicit time series analyses take account of this aspect and can correct for it to determine the impact of an intervention such as a chemical exposure.

Influence of CaCl(2) on Penicillium digitatum, Grapefruit Peel Tissue, and Biocontrol Activity of Pichia guilliermondii

ABSTRACT Interactions between CaCl(2), grapefruit peel tissue, Penicillium digitatum, and the yeast antagonist Pichia guilliermondii strain US-7 were investigated. Application of 68 or 136 mM CaCl(2) to grapefruit surface wounds reduced the incidence of green mold caused by Penicillium digitatum by 43 to 52%. In laboratory tests, a cell suspension (10(7) cells/ml) of Pichia guilliermondii containing either 68 or 136 mM CaCl(2) reduced the incidence of green mold from 27 to 3%. In large scale tests, dip application of 136 mM CaCl(2) with US-7 (10(7) cells/ml) significantly decreased the number of wounds infected by Penicillium digitatum. CaCl(2), with or without yeast cells, stimulated ethylene production in grapefruit tissue. Increasing concentrations of CaCl(2) resulted in decreased spore germination and germ tube elongation of Penicillium digitatum. Pectinolytic activity of crude enzyme preparations of Penicillium digitatum was also inhibited by the presence of increasing concentrations of CaCl(2). US-7 exhibited a strong ability to maintain cytosolic Ca(2+) homeostasis at levels that did not exceed 1.4 muM when exposed to 150 mM CaCl(2). On the other hand, strain 114 of Debaryomyces hansenii, which failed to give any protection against infection by Penicillium digitatum, showed reduced capacity to maintain Ca(2+) homeostasis. The effect of calcium in reducing infection of grapefruit wounds by Penicillium digitatum could be due to direct effects on host tissue (making cell walls more resistant to enzymatic degradation) or the pathogen (interfering with spore germination, growth, and inhibition of fungal pectinolytic enzymes). Alternatively, the ability of US-7 to maintain calcium homeostasis may allow it to grow or assist in its competitive ability in a microenvironment that, because of high levels of calcium ions, is inhibitory to growth of the green mold pathogen.

Regulation of the soxRS oxidative stress regulon. Reversible oxidation of the Fe-S centers of SoxR in vivo

SoxR protein, a transcriptional activator of the soxRS (superoxide response) regulon of Escherichia coli, contains autooxidizable [2Fe-2S] centers that are presumed to serve as redox sensors. In vitro transcription experiments previously demonstrated that only the oxidized form is active. Reduced SoxR was detected in overproducing strains by EPR spectroscopy of suspensions of intact cells. Oxidized Fe-S centers were determined by lysing the cells and treating them with the reducing agent sodium dithionite prior to EPR measurements. In uninduced cells, 90% of the SoxR was in the reduced form. Treatment with the redox cycling agents phenazine methosulfate or plumbagin was accompanied by reversible oxidation of the Fe-S centers. Mutant SoxR derivatives that were constitutively activated existed constitutively in an oxidized state. The results indicate the presence of a cellular pathway for countering the autooxidation of SoxR and confirm the hypothesis that induction of the regulon is mediated by a shift in the redox equilibrium of SoxR rather than by assembly of its Fe-S clusters.

The neural cell recognition molecule F11 is expressed on Müller cells and Schwann cells in vitro

The neural cell recognition molecule F11 is a member of the immunoglobulin superfamily. During development it is expressed on axons in neuropils, and it is implicated in neurite outgrowth and in fasciculation. F11 is a multifunctional protein that interacts with L1/Ng-CAM, Nr-CAM, tenascin-C, tenascin-R (restrictin) and receptor protein tyrosine phosphatase beta. Here we show that F11 is not only expressed on neurons, but also on Müller cells and Schwann cells in vitro. Using two independent cell culture techniques, stratospheroids which represent an in vitro regeneration system of the chicken retina, and purified Schwann cells from chicken sciatic nerve, we show that Müller cells and Schwann cells express F11. On semithin cryosections of stratospheroids we were able to colocalize F11 with the Müller cell markers vimentin and 3A7. Expression of F11 by purified Schwann cells in demonstrated histologically and by immunoblot analysis. These in vitro data suggest the involvement of F11 in glia-neuron or glia-neurite interactions.

Antisense strategies in dopamine receptor pharmacology

Recent advances in molecular biology have provided pharmacologists the opportunity of developing an entirely new type of agent for studying and treating a variety of biological disorders. These agents, termed antisense oligodeoxynucleotides, have as their target the messenger RNAs encoding specific proteins. They act by binding to selected portions of these mRNAs through complimentary interactions and thereby prevent the synthesis of these proteins. These novel pharmacological tools have the promise of being easier to design and being more selective and predictable in their actions. In addition, insofar as agents targeted to receptors for neurotransmitters are concerned, unlike the classical pharmacological agents, these new compounds may not lead to the upregulation of the very receptors the drugs are designed to inhibit. The present review summarizes briefly studies on the effect of oligodeoxynucleotides antisense to the mRNAs encoding the various subtypes of the dopamine receptor. The studies show that oligodeoxynucleotides antisense to the D2 dopamine receptor when intracerebroventricularly into brains of rodents are rapidly taken up into the brain tissue, distributed to brain cells, and produce effects characteristic of highly selective D2 dopamine antagonists. The compounds also produced specific reductions in the levels of D2 dopamine receptor mRNA and D2 dopamine receptors. Similarly, injecting an antisense oligodeoxynucleotide targeted to the D1 dopamine receptor mRNA produces effects characteristic of D1 dopamine receptor antagonists. Other studies using these agents has produced evidence that there is a small pool of receptors that turn over very rapidly and which constitute the functional pool of these receptors. The evidence suggests further that antisense oligodeoxynucleotides inhibit the synthesis of this small functional pool of dopamine receptors, thereby providing an explanation of why there is often a discordance between changes in dopaminergic function and changes in the levels of dopamine receptors. Studies of antisense oligodeoxynucleotides targeted to the other subtypes of dopamine receptor may help reveal the biological roles that these and other newly discovered subtypes of neurotransmitter receptors have. They may also provide an entirely new and potentially more selective therapeutic regimen for altering the functions of these receptors.

nfi, the gene for endonuclease V in Escherichia coli K-12

Endonuclease V is specific for single-stranded DNA or for duplex DNA that contains uracil or that is damaged by a variety of agents (B. Demple and S. Linn, J. Biol. Chem. 257:2848-2855, 1982). Thus, it may be a versatile DNA repair enzyme. The protein was purified to apparent homogeneity, and from its N-terminal sequence, its gene, nfi, was identified. nfi is immediately downstream of hemE, at kb 4208 (90.4 min) on the current chromosomal map of Escherichia coli K-12. This region was cloned, and plasmid insertion and deletion mutants were used to study its molecular organization. Although nfi is the third of four closely spaced, codirectional genes, it is expressed independently.

Reduced level of calmodulin in PC12 cells induced by stable expression of calmodulin antisense RNA inhibits cell proliferation and induces neurite outgrowth

The role calmodulin plays in the growth and differentiation of nerve cells was assessed by altering the levels of calmodulin in the PC12 rat pheochromocytoma cell line and determining the effects of altering these levels on cellular proliferation and differentiation. Calmodulin levels in the PC12 cells were increased or decreased by transfecting the cells with a mammalian expression vector into which the rat calmodulin gene I had been cloned in the sense or antisense orientation, respectively. The cells transfected with the calmodulin sense gene showed increased levels of calmodulin immunoreactivity and increased levels of calmodulin messenger RNA as ascertained by immunocytochemistry and slot-blot analysis, respectively. Cells transfected with the calmodulin antisense construct showed reduced levels of calmodulin immunoreactivity. Reducing the levels of calmodulin by expression of antisense calmodulin messenger RNA resulted in a marked inhibition of cell growth, whereas increasing the levels of calmodulin by overexpressing calmodulin messenger RNA resulted in an acceleration of cell growth. Transfected PC12 cells having reduced levels of calmodulin immunoreactivity exhibited spontaneous outgrowth of long, stable and highly branched neuritic processes. PC12 cells in which calmodulin was overexpressed showed no apparent changes in cell morphology, but did show an altered response to the addition of nerve growth factor. While nerve growth factor slowed cellular proliferation and induced extensive neurite outgrowth, in parental PC12 cells nerve growth factor induced little or no neurite outgrowth and little inhibition of cell proliferation in transfected cells overexpressing calmodulin. These results indicate that calmodulin is essential for the proliferation of nerve cells and for the morphological changes that nerve cells undergo during differentiation. The study also suggests the possibility that a calmodulin antisense approach may be used to inhibit the proliferation of neuronal tumors.

Intrastriatal administration of an oligodeoxynucleotide antisense to the D2 dopamine receptor mRNA inhibits D2 dopamine receptor-mediated behavior and D2 dopamine receptors in normal mice and in mice lesioned with 6-hydroxydopamine

Previous studies have shown that the intracerebroventricular injection of antisense oligodeoxynucleotides targeted to the mRNAs encoding the different subtypes of dopamine receptors inhibited behaviors mediated by these receptors. The present studies were designed to determine whether such antisense oligodeoxynucleotides could produce similar effects when injected into a discrete brain area. A D2 dopamine receptor antisense oligodeoxynucleotide (D2 antisense) was repeatedly injected into one corpus striatum of either normal mice or mice with unilateral lesions of the striatum induced by 6-hydroxydopamine. In the latter, intrastriatal injection of D2 antisense blocked the contralateral rotational behavior induced by the parenteral administration of the D2 dopamine receptor agonist quinpirole. The inhibitory effect of D2 antisense was dose- and time-related and was reversed upon cessation of D2 antisense treatment. This inhibitory effect was also selective in that D2 antisense treatment inhibited the rotational behavior induced by quinpirole but not that induced by the D1 dopamine receptor agonist SKF 38393 or by the muscarinic cholinergic agonist oxotremorine. Following repeated intrastriatal injections of D2 antisense into normal mice, parenteral administration of quinpirole caused rotational behavior ipsilateral to the side in which the D2 antisense was injected. No such rotational behavior was seen when similarly treated mice were challenged with SKF 38393 or oxotremorine. The quinpirole-induced rotational behavior in mice given intrastriatal injections of D2 antisense disappeared upon cessation of D2 antisense treatment. Repeated intrastriatal administration of D2 antisense also caused a significant reduction in the levels of D2, but not D1, dopamine receptors in striatum, as determined by receptor autoradiography. The levels of D2 dopamine receptors returned to normal upon cessation of D2 antisense treatment. Intrastriatal administration of an oligodeoxynucleotide with randomly placed nucleotides failed to alter the rotational response to quinpirole in either 6-hydroxydopamine-lesioned or normal mice and failed to alter the levels of D2 dopamine receptors in striatum. These results show that selective inhibition of behavioral responses mediated by D2 dopamine receptors can be achieved by the direct injection of a D2 antisense oligodeoxynucleotide into a discrete brain area.

Perinatal methanol exposure in the rat. I. Blood methanol concentration and neural cell adhesion molecules

Although the acute toxicity of methanol is well documented, few studies have addressed the consequences of perinatal exposures to the low concentrations that are expected to arise from its proposed use as a component of automobile fuel. This report describes the general research design of a series of studies, the effects of methanol exposures on blood concentrations in dams and neonates, and indices of brain development. Four cohorts of Long-Evans pregnant rats, each cohort consisting of an exposure (n = 12) and a control (n = 12) group, were exposed whole-body to 4500 ppm methanol vapor or air for 6 hr daily beginning on Gestation Day 6. Both dams and pups were then exposed through Postnatal Day 21 (PND 21). Blood methanol concentrations determined by gas chromatography from samples obtained immediately following a 6-hr exposure reached approximately 500-800 micrograms/ml in the dams during gestation and lactation. Average concentrations for pups attained levels about twice those of the dams. Selected offspring from Cohort 4 were exposed for one additional 6-hr session at ages that extended out to PND 52. Regression analyses showed that the blood methanol concentrations of the pups declined until about PND 48, at which time their levels approximated those of their dams. Such pharmacokinetic differences might increase the risks posed to developing organisms. Light-microscopic analysis showed no significant abnormalities in the brains of the methanol-treated animals. However, assays of neural cell adhesion molecules (NCAMs) in brains of pups sacrificed on PND 4 showed staining for both the 140 and the 180 kDa isoforms to be less intense in the cerebellum of exposed animals. NCAM differences were not apparent in animals sacrificed 15 months after their final exposure.

D2 dopamine receptor antisense increases the activity and mRNA of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in mouse brain

A D2 dopamine receptor antisense oligodeoxynucleotide was administered intracerebrovetricularly to mice twice on the first day and then once daily for 2 days. The animals were killed 2 h after the last injection, and tyrosine hydroxylase and aromatic L-amino acid decarboxylase activities assayed in the corpus striatum, olfactory tubercle and frontal cortex. Tyrosine hydroxylase activity increased in corpus striatum but not in the olfactory tubercle or in the frontal cortex, while the activity of aromatic L-amino acid decarboxylase increased in all three brain regions. The treatment with the antisense oligomer also elevated the mRNA levels for the two enzymes in the midbrain. In contrast, repeated injection of a vehicle or a random oligomer was without effect on enzyme activity or mRNA D2 antisense oligodeoxynucleotides appear to be selective tools to investigate the role of D2 dopamine receptors in brain.

Impact of on-site social work services on the documentation of client and family-centered information: the experience of Ryan White CARE Act (Title IV) pediatric program sites in Maryland

BACKGROUND

The purpose of this study is to (1) describe client and maternal demographic, social, and medical characteristics of pediatric clients receiving medical and social services at Ryan White (Title IV) program sites, and (2) determine the impact of on-site social work services in documenting client and family-related information used to assess the psychosocial needs of the families affected by human immunodeficiency syndrome and acquired immunodeficiency syndrome (HIV/AIDS).

METHODS

We studied infants born to known HIV-infected women who received HIV-related medical services at a federally funded Title IV Ryan White CARE Act provider site in Maryland. Eligibility criteria included < 24 months of age at time of initial clinic visit, a history of birth to a known HIV-infected woman, and a minimum of one comprehensive clinical visit for medical evaluation at a selected Title IV provider site. Study populations were categorized into three independent clinic cohorts. A pre- and postintervention study design was used to assess the impact of the intervention (i.e., on-site social work activities) on variables of interest. Clinic cohorts were (a) preintervention group (N = 181), from January 1, 1986 to December 31, 1989; (b) initial postintervention group (N = 216), from January 1, 1991 to December 31, 1992; and, (c) long-term postintervention group (N = 197), from January 1, 1993 to March 1, 1994. Client and maternal demographic, social, and medical information were recorded and statistical comparisons between pre- and postintervention clinic cohorts were completed with the use of standard statistical methods.

RESULTS

Pediatric clients were predominantly African American (94%), lived in low-income family units reflected by the prevalence of public assistance programs (i.e., Medicaid), had a high likelihood of Medicaid enrollment (> 80%), and reported a high frequency of social disruption (e.g., protective services interventions and housing difficulties). Greater than half of all medical records documented the "mother" as the client's primary caregiver in the three cohorts (a,b,c, above) pre- and postintervention cohorts, 51%, 65%, and 66.5%, respectively. Over two-thirds of the mothers among all cohorts were reported to have a current or past history of illicit drug use or alcohol abuse, 69%, 62%, and 67.5%, respectively. Postintervention groups, both initial and long term, were significantly more likely than the preintervention group to have documented medical record information relevant to a history of protective services, housing problems, and maternal demographic, social, and clinical information. Maternal HIV-related clinical status and select social factors (e.g., drug use, housing) remained underreported in both postintervention groups.

CONCLUSIONS

Title IV pediatric clinical sites deliver services to a predominantly urban, poor, minority community-the population at greatest risk for pediatric HIV-infection in Maryland. Alternative family members as the primary caregiver for infants and children was common and increased over time. These findings demonstrate that Title IV funded programs have been successful in the documentation of valuable client and maternal information necessary for the development of family-centered clinical and support services to a highly vulnerable population of HIV at-risk or infected infants and children in Maryland.

SoxR, a [2Fe-2S] transcription factor, is active only in its oxidized form

SoxR protein is known to function both as a sensor and as a transcriptional activator for a superoxide response regulon in Escherichia coli. The activity of SoxR was tested by its ability to enable the transcription of its target gene, soxS, in vitro. The activity of the oxidized form was lost when its [2Fe-2S] clusters were reduced by dithionite under anaerobic conditions, and it was rapidly restored by autooxidation. This result is consistent with the hypothesis that induction of the regulon is effected by the univalent oxidation of the Fe-S centers of SoxR. In vivo, this oxidation may be caused by an alteration of the redox balance of electron chain intermediates that normally maintains soxR in an inactive, reduced state. Oxidized SoxR was about twice as effective as reduced SoxR in protecting the soxS operator from endonucleolytic cleavage. However, this difference could not account for a greater than 50-fold difference in their activities and therefore could not support a model in which oxidation activates SoxR by enabling it to bind to DNA. NADPH, ferredoxin, flavodoxin, or ferredoxin (flavodoxin):NADP+ reductase could not reduce SoxR directly in vitro at a measurable rate. The midpoint potential for SoxR was measured at -283 mV.

Human performance during exposure to toluene

PURPOSE

The purpose of this research was to examine the effects of inhalation of toluene on respiratory function and neuropsychological performance of humans.

METHODS

We exposed six healthy adults to 100 ppm toluene or air (control) for 6 h, in a double-blind, randomized fashion, with exposures separated by at least 14 d and including 30 min of exercise at a level that quadrupled minute ventilation. Blood and exhaled air toluene levels were measured before, during, immediately, and 1 and 2 h post-exposure. Lung function was measured before and immediately after exposure. Three repetitions of two computerized neuropsychological tests were performed, including a brief standard neuropsychological battery (ANAM) and a 1-h complex performance test (SYNWORK). Statistical analysis of the psychological data was conducted as a repeated measures ANOVA.

FINDINGS

Following exercise, the mean blood and exhaled air toluene levels averaged 1.5 micrograms and 28 ppm, respectively. Lung function was unchanged post-exposure. On the SYNWORK test, the Composite score obtained over time during toluene exposure was lower than that during room air (F = 29.20, p = 0.005), with the score from the final hour reduced by 10%. On standard neuropsychological tests, latency but not accuracy proved the sensitive measure for five of the seven subtests presented.

CONCLUSIONS

Performance of complex tests and response time to simple brief tests can be disrupted by toluene inhalation at 100 ppm. Differences in performance between air and toluene conditions were greatest after exercise, indicating that physical activity may enhance the response to volatile organic solvents.

Assessment of the composition of bone marrow prior to and following autologous BMT and PBSCT by magnetic resonance

Lumbar bone marrow was assessed by means of magnetic resonance (MR) in 23 examinations of eight patients who underwent autologous bone marrow transplantation (ABMT) or peripheral blood stem cell transplantation (PBSCT). Various imaging and spectroscopic techniques were applied for measurements carried out prior to conditioning for ABMT/PBSCT and in the course of reconstitution and correlated with clinical and blood chemistry data in these patients. The signal intensity from lumbar bone marrow was determined in T1-weighted and water- and fat-selective MR images. The distribution of the magnetic field was demonstrated by a field-mapping method. Localized proton spectroscopy was performed from volume elements of 2 ml located in the central region of vertebral bodies in order to evaluate the fraction of the water signals, the transverse relaxation times T2 of the signals from water and lipids, and the line widths of the spectral signals. Regions of bone marrow after inflammatory conditions or intensive irradiation are shown to be not involved in marrow reconstitution. Additional information about marrow composition was obtained by the magnetic field mapping and by the line widths in the spectra. Considerable alterations of the amount of paramagnetic hemosiderin were revealed following transplantation. Patients with low water signal and strong local inhomogeneities of the magnetic field in the marrow prior to transplantation had a delayed hematopoietic reconstitution compared with the patients lacking these MR features.

Proliferating and differentiating Schwann cell cultures from embryonic chick sciatic nerve maintained for months in vitro without antimitotics or growth factors

In general, the available methods for culturing Schwann cells require specific antibodies and/or the addition of antimitotics to suppress fibroblasts, plus various factors to support their growth. Moreover, the maximal culture period of Schwann cells normally is limited to a few weeks. Here, three easy novel methods to culture Schwann cells from embryonic chick sciatic nerve are presented, that require no growth factors or agents elevating intracellular cAMP. In contrast to the conventional antimitotic treatment with cytosine arabinoside, we use D-valine to suppress fibroblasts. Our modified medium C leads within a few days to highly enriched Schwann cell cultures (culture I). Passage into a serum-reduced medium D allows for differentiating longterm cultures (culture II). In cultures I and II, the rate of cell division is low. However, after passage into serum-containing SC-medium, proliferation increases within one week to high levels (culture III). Cultures II and III can be grown for several months, during which time spontaneous immortalization can occur. The high purity of the cultures of about 95% is assessed using glia-specific antibodies for S-100 antigen, HNK-1 epitope, glia fibrillary acidic protein (GFAP), galactocerebroside (Gal C) and 3A7. These culture procedures are easy to perform and are suitable for differentiation, proliferation and coculturing experiments.

The intersection of risk assessment and neurobehavioral toxicity

Neurobehavioral toxicology is now established as a core discipline of the environmental health sciences. Despite its recognized scientific prowess, stemming from its deep roots in psychology and neuroscience and its acknowledged successes, it faces additional demands and challenges. The latter, in fact, are a product of its achievements because success at one level leads to new and higher expectations. Now the discipline is counted upon to provide more definitive and extensive risk assessments than in the past. These new demands are the basis for the appraisals presented in the SGOMSEC 11 workshop. They extend beyond what would be offered in a primer of methodology. Instead, these appraisals are framed as issues into which what are usually construed as methodologies have been embedded.

Developmental neurotoxicity of methanol exposure by inhalation in rats

The possibility of widespread methanol exposure via inhalation stemming from its adoption as an automotive fuel or fuel component arouses concerns about the potential vulnerability of the fetal brain. This project was designed to help address such concerns by studying the behavior of neonate and adult rats following perinatal exposure to methanol vapor. Four cohorts of pregnant Long-Evans hooded rats, each cohort consisting of an exposure and a control group, were exposed to 0 parts per million (ppm) (control) or 4,500 ppm methanol vapor for six hours daily beginning on gestation day (GD) 6 with dams and pups then being exposed postnatal day (PND) 21. Exposures took place in 2-m3 Rochester-type inhalation chambers while the animals remained in their plastic breeder cages. Prenatal and postnatal blood methanol concentrations were determined by gas chromatography. Blood methanol concentrations of the dams, measured immediately following a six-hour exposure, were approximately 500 to 800 micrograms/mL throughout gestation and lactation. Average blood methanol concentrations of the pups were about twice those of the dams. Because such results appeared consistently across the other cohorts, we decided to obtain additional data with Cohort 4. Once it had undergone the standard exposure protocol, we selected sets of extra pups from those that had not been assigned previously to the adult phase of behavioral testing. Each set was exposed once, at ages that extended out to PND 52, for one additional six-hour session of exposure to 4,500 ppm methanol. The blood methanol concentrations of these pups declined until about PND 48, at which time they approximated those of the dams. These findings might be accounted for by a process of metabolic maturation in the pups that remains to be identified.

Uptake and distribution of fluorescein-labeled D2 dopamine receptor antisense oligodeoxynucleotide in mouse brain

To determine the uptake and distribution of oligodeoxynucleotides in brain, a 20-mer phosphorothioated oligodeoxynucleotide complementary to a portion of the D2 dopamine receptor mRNA was fluorescently labeled with fluorescein isothiocyanate (FITC) and injected into the lateral cerebral ventricles of mice. At various survival times after the injection, the brains were removed, fixed, sectioned, and viewed under a fluorescent microscope. The results showed that the oligodeoxynucleotide was rapidly taken up into the brain. Initially the label was relatively diffusely spread throughout the interstitial spaces of the brain, then became redistributed to the cellular compartments. The signal extended from those forebrain nuclei located immediately in contact with the ventricles, such as the corpus striatum, septum, and hippocampus, to areas further removed from the ventricles, such as the cerebral cortex, nucleus accumbens, and substantia nigra. When the FITC-labeled D2 antisense oligodeoxynucleotide was given once daily for 4 d, the signal intensity seen 24 h after the last injection appeared to be of greater intensity overall compared to that seen after a single injection. At early time-points the oligodeoxynucleotide signals appeared to be punctuated and were found in cell bodies as well as in proximal dendritic processes. However, not all cells were equally labeled, suggesting an uneven uptake and accumulation of the D2 antisense into the various cell types. At later time-points the fluorescent signal appeared granular; at these times the injected material was largely degraded. These studies show that a D2 dopamine receptor antisense oligodeoxynucleotide is rapidly taken up from cerebral ventricles into brain, becomes widely distributed throughout the brain tissue to areas far removed from direct contact with the ventricles, and appears to accumulate to a different extent in the various brain areas and cell types.

Bridging the gap between laboratory and clinic in child and adolescent psychotherapy

Meta-analyses of laboratory outcome studies reveal beneficial effects of psychotherapy with children and adolescents. However, the research therapy in most of those lab studies differs from everyday clinic therapy in several ways, and the 9 studies of clinic therapy the authors have found show markedly poorer outcomes than research therapy studies. These findings suggest a need to bridge the long-standing gap between outcome researchers and clinicians. Three kinds of bridging research are proposed and illustrated: (a) enriching the research data base on treatment effects by practitioners in clinical settings--including private practice and health maintenance organizations, (b) identifying features of research therapy that account for positive outcomes and applying those features to clinical practice, and (c) exporting lab-tested treatments to clinics and assessing their effects with referred youths. If these bridging strategies were widely adopted, despite the numerous obstacles described herein, real progress might be made toward more effective treatment in clinical practice.

Magnetization transfer in hemopoietic bone marrow examined by localized proton spectroscopy

The sensitivity of hemopoietic bone marrow to magnetization transfer is analyzed in 15 healthy volunteers and seven patients with different hematological disorders (inflammation, plasmacytoma, hemopoietic reconstitution after bone marrow transplantation). To obtain sufficient signal-to-noise ratio, a 90 degrees - 180 degrees - 180 degrees double spin echo (PRESS) single voxel spectroscopic method was combined with pulsed magnetization transfer. Several spectra were recorded from each volume element inside the vertebral marrow, alternately with and without prepulses for magnetization transfer. Water signals from marrow with increased content of extracellular water due to inflammation or edema revealed less magnetization transfer effects than marrow with increased intracellular water content due to high cellularity. The preliminary results show magnetization transfer to be a promising tool for the clinically important characterization of the water composition in red bone marrow.

Antigen-independent reactivation of anti-E, years after allogeneic bone marrow transplantation: a case report

Nine years after allogenic bone marrow transplantation a strong anti-E was observed in a patient transplanted with bone marrow from his HLA-identical brother. This IgG anti-E, with a titre of 4000, was detected together with autoantibodies to red blood cells and platelets and was not induced by transfusion with E+ cells. The hypothesis is proposed that the anti-E represents either antigen-independent desuppression of the donor immune system sensitized at the time of bone marrow transplantation by E antigens in the recipient, or antigen-independent memory B-cell activation by Epstein-Barr virus infection.

Localization of fruit tree viruses by immuno-tissue printing in infected shoots of Malus sp. and Prunus sp

Immuno-tissue printing protocols for the localization of apple chlorotic leaf spot virus (ACLSV), stem grooving virus (SGV) and plum pox virus (PPV) in shoots of Prunus and Malus in vitro have been established for routine diagnosis in a virus elimination program. Since these viruses belong to different virus genera, the protocols were adapted according to the properties of the virus under investigation. Accumulation of ACLSV was highest in the base of the stem and decreased towards the apex of the shoots. ACLSV was found in the epidermis, the cortex, in the vascular bundles, but seldom in the pith tissue of in vitro apple shoots. ACLSV immuno-tissue printing was as sensitive as ELISA and the intensity of color signals in immuno-tissue prints correlated with absorbance values by two-step ELISA. SGV could be detected by immuno-tissue prints at infectivity levels, where it reacted negative in ELISA. SGV accumulated in the vascular bundles, occurred locally in the parenchymatic tissue, was found in high amounts in young leaves near the meristem, but not within the meristem. PPV was detected in all tissue types of stem sections with an irregular pattern reflecting the in vivo situation causing problems with detection. Discrimination of poorly and heavily infected shoots was possible with the naked eye.

D2 dopamine receptor antisense oligodeoxynucleotide inhibits the synthesis of a functional pool of D2 dopamine receptors

In vivo administration of an antisense oligonucleotide targeted toward the D2 dopamine (DA) receptor mRNA (D2 AS) markedly inhibited D2 receptor-mediated behaviors but produced only a relatively small reduction in the levels of D2 DA receptors in mouse striatum. This apparent dissociation between DA receptor-mediated behaviors and the levels of D2 DA receptors was addressed by inhibiting the total number of D2 DA receptors by intraperitoneal administration of the selective, irreversibly acting D2 DA receptor antagonist fluphenazine-N-mustard (FNM) and then determining the effects of D2 AS, administered intracerebroventricularly, on the rate of synthesis of D2 DA receptors and on the recovery of D2 receptor-mediated behaviors. FNM inactivated approximately 90% of D2 DA receptors within 4 hr of treatment, after which the receptors returned to normal levels by approximately 8 days. D2 AS treatment significantly inhibited the rate of recovery of D2 DA receptors in striatum of FNM-treated mice. FNM treatment also produced a number of behavioral alterations, including catalepsy, and the inhibition of stereotypic behavior induced by the D2/D3 DA receptor agonist quinpirole. Both of these behaviors returned to normal within 8 days after FNM treatment. D2 AS treatment delayed the restoration of these FNM-induced behaviors. Thus, it reduced the rate of disappearance of the cataleptic behavior induced by FNM and significantly delayed the restoration of the stereotypic behavior induced by quinpirole. The changes induced by D2 AS on D2 receptor-mediated behaviors were reversed on cessation of D2 AS treatment. A random oligomer given in the same amount and for the same length of time as that of the D2 AS had no significant effects on either D2 DA receptor synthesis or DA receptor-mediated behaviors. These studies demonstrate that in vivo administration of D2 AS decreased the rate of recovery of D2 DA receptors and inhibited the recovery of D2 DA receptor-mediated behaviors after irreversible receptor inactivation and suggest that D2 AS treatment inhibits the synthesis of a functional pool of D2 DA receptors.

Bridging the gap between laboratory and clinic in child and adolescent psychotherapy

Meta-analyses of laboratory outcome studies reveal beneficial effects of psychotherapy with children and adolescents. However, the research therapy in most of those lab studies differs from everyday clinic therapy in several ways, and the 9 studies of clinic therapy the authors have found show markedly poorer outcomes than research therapy studies. These findings suggest a need to bridge the long-standing gap between outcome researchers and clinicians. Three kinds of bridging research are proposed and illustrated: (a) enriching the research data base on treatment effects by practitioners in clinical settings--including private practice and health maintenance organizations, (b) identifying features of research therapy that account for positive outcomes and applying those features to clinical practice, and (c) exporting lab-tested treatments to clinics and assessing their effects with referred youths. If these bridging strategies were widely adopted, despite the numerous obstacles described herein, real progress might be made toward more effective treatment in clinical practice.

Magnetic resonance imaging reveals a markedly inhomogeneous distribution of marrow cellularity in a patient with myelodysplasia

A 47-year-old male patient with myelodysplasia showed increasing values of serum lactate dehydrogenase (up to 3500 units/l) and an increasing blast count. Several biopsies (taken from the posterior iliac crest) revealed marked hypocellularity. In contrast, magnetic resonance imaging of the marrow demonstrated an inhomogeneous distribution of marrow with hypocellular and also large hypercellular areas not detected by cytological and histological analysis. A location for biopsy of hypercellular marrow was provided by T1-weighted and water-selective magnetic resonance imaging. The findings in the patient were compared with those in a matched healthy volunteer.