P1-07-14: Quantum Dot-Labelled Antibodies To Assess HER2 Expression in Breast Cancer

Background: The Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in 18–20% of breast cancers. Herceptin is an effective drug for the treatment of breast cancers expressing high levels of HER2. It is well known that there is a correlation between levels of HER2 expression and response to Herceptin. However a proportion of patients selected for Herceptin treatment do not respond to the drug. The accuracy of the assessment of HER2 levels in breast cancer is therefore important to predict patients’ response to Herceptin therapy. The current techniques in clinical use for the assessment of HER2 are immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH); however both IHC and FISH have several limitations which may result in patient misclassification. A more accurate technique, which can quantify HER2 levels more precisely, could help to improve clinical diagnosis, prediction of prognosis and allow more accurate select individual patients for particular drug therapies.

Materials and Methods: We employed QDs labelled antibodies, laser scanning confocal microscopy and image segmentation techniques to quantify HER2 expression in cases of formalin fixed paraffin embedded breast cancers. Quantum dots (QDs) are a new class of fluorochromes made of semiconductor nanocrystal which have several useful properties for quantitative image analysis. In order to validate the system we used a breast cancer HER2−IHC control tissue array with negative, low, moderate and strong expressing cases, and a tissue microarray containing 60 samples of formalin fixed paraffin embedded breast cancer sections, previously examined by IHC and scored semiquantitatively (0-3+). We then applied this system to quantify HER2 expression a tissue microarray containing 150 primary breast cancers scored as 3+ by IHC from patients treated with Herceptin.

Results: We first demonstrated that the QD system could reliably detect HER2 expression in IHC 3+ cases. A comparison of immunofluorescent staining with conventional immunohistochemistry showed that QDs give more linear and scalable measurements of receptor levels. We also quantified HER2 within a set of 150 breast cancers scored as 3+ by IHC, and we found that HER2 is expressed at very different levels, ranging over fifty fold between individual (IHC3+) cases. We currently are evaluating the correlation between HER2 receptor levels, measured by QDs, and patient's response to Herceptin.

Conclusion: QDs and image analysis can produce a more precise measurement of HER2 levels of expression than IHC. This should help to improve clinical diagnosis, prognosis, identify specific treatments for individual patients and reduce costs associated with Herceptin treatment. This technology may be applied to study other members of the EGF family in breast cancers or more widely as a quantitative measurement of biomarkers in tumours.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-07-14.

Expression of mRNA encoding extracellular matrix glycoproteins SPARC and SC1 is temporally and spatially regulated in the developing cochlea of the rat inner ear

SPARC is a multifunctional extracellular matrix (ECM) glycoprotein that shares partial sequence homology with SC1/hevin. These ECM molecules exhibit calcium-binding properties and modulate cellular interactions. This study examines the expression of SC1 and SPARC mRNA in the developing cochlea of the rat inner ear prior to and after the onset of hearing. At all ages examined, SC1 mRNA is highly expressed in neurons of the spiral ganglion. In contrast, SPARC transcripts are not detected in the spiral ganglion but are enriched in the temporal bone and cartilaginous otic capsule surrounding the cochlea. Both SC1 and SPARC mRNA are expressed in connective tissue elements involved in maintaining ionic homeostasis of cochlear fluids. SC1 mRNA is localized to type III fibrocytes of the spiral ligament (slg) and marginal cells of the stria vascularis, while SPARC mRNA is apparent in the spiral limbus and type I fibrocytes of the slg. At postnatal day 10, SPARC mRNA shows a dramatic change in expression. High levels of SPARC transcripts are induced in Deiters cells (dc) of the organ of Corti. Interestingly, this induction of SPARC mRNA correlates with the onset of hearing. This suggests that SPARC may play a role in calcium regulation in dc when functional maturation of the cochlea is attained and rapid changes in calcium levels are required.

Immunocytochemical localization of HrpA and HrpZ supports a role for the Hrp pilus in the transfer of effector proteins from Pseudomonas syringae pv. tomato across the host plant cell wall

The Hrp pilus, composed of HrpA subunits, is an essential component of the type III secretion system in Pseudomonas syringae. We used electron microscopy (EM) and immunocytochemistry to examine production of the pilus in vitro from P. syringae pv. tomato strain DC3000 grown under hrp-inducing conditions on EM grids. Pili, when labeled with antibodies to HrpA, developed rapidly in a nonpolar manner shortly after the detection of the hrpA transcript and extended up to 5 microm into surrounding media. Structures at the base of the pilus were clearly differentiated from the basal bodies of flagella. The HrpZ protein, also secreted via the type III system, was found by immunogold labeling to be associated with the pilus in vitro. Accumulation and secretion of HrpA and HrpZ were also examined quantitatively after the inoculation of wild-type DC3000 and hrpA and hrpZ mutants into leaves of Arabidopsis thaliana. The functional pilus crossed the plant cell wall to generate tracks of immunogold labeling for HrpA and HrpZ. Mutants that produced HrpA but did not assemble pili were nonpathogenic, did not secrete HrpA protein, and were compromised for the accumulation of HrpZ. A model is proposed in which the rapidly elongating Hrp pilus acts as a moving conveyor, facilitating transfer of effector proteins from bacteria to the plant cytoplasm across the formidable barrier of the plant cell wall.

Differential mRNA expression of the related extracellular matrix glycoproteins SC1 and SPARC in the rat embryonic nervous system and skeletal structure

SPARC is a multifunctional extracellular matrix glycoprotein that shares partial sequence homology with SC1. These extracellular matrix molecules are thought to play important roles in modulating cellular interactions. In vitro, SPARC has been shown to exhibit anti-adhesive activity. In the present investigation, in situ hybridization is used to compare the expression patterns of SC1 and SPARC mRNA in the rat embryo. Results show that SC1 and SPARC expression is spatially and temporally regulated. SC1 mRNA is strongly expressed in the embryonic brain and spinal cord, whereas SPARC mRNA is enriched in craniofacial cartilage and skeletal structures. This differential expression pattern in the rat embryo suggests that SC1 plays an important role in the developing nervous system, whereas SPARC participates primarily in events associated with skeletal development. However at embryonic day 17, SC1 and SPARC mRNA show parallel expression patterns in areas of the cerebellum undergoing cell migratory events.

Induction of SC1 mRNA encoding a brain extracellular matrix glycoprotein related to SPARC following lesioning of the adult rat forebrain

SC1 is an extracellular matrix (ECM) glycoprotein related to SPARC which exhibits anti-adhesive properties. ECM molecules are thought to play important roles in influencing cell shape, proliferation and migration during neurogenesis. Following localized injury to the adult rat forebrain, a biphasic induction of SC1 mRNA was apparent, namely a rapid, transient induction at 1 day post-lesion in cortical neurons which border the lesion site followed by a more prolonged induction in astrocytes which are proximal to the wound site. A similar SC1 induction pattern was observed in the hippocampus in response to the injury. SPARC mRNA exhibits a divergent pattern of induction because it is induced in mature blood vessels close to the lesion and in blood vessels which develop following the trauma. Thus mRNAs encoding the related ECM glycoproteins SC1 and SPARC are induced in different cell populations in the adult forebrain during the neural response to localized injury.

A loss of resistance to avirulent bacterial pathogens in tobacco is associated with the attenuation of a salicylic acid-potentiated oxidative burst

The role of salicylic acid (SA) in events occurring before cell death during the hypersensitive reaction (HR) was investigated in leaves of wild-type tobacco Samsun NN and in transgenic lines expressing salicylate hydroxylase (35S-SH-L). Challenge of 35S-SH-L tobacco with avirulent strains of Pseudomonas syringae gave rise to symptoms resembling those normally associated with a compatible response to virulent strains in terms of visible phenotype, kinetics of bacterial multiplication, and escape from the infection site. Compared with responses in wild-type tobacco, both the onset of plant cell death and the induction of an active oxygen species-responsive promoter (AoPR1-GUS) were delayed following challenge of 35S-SH-L plants with avirulent bacteria. The oxidative burst occurring after challenge with avirulent bacteria was visualized histochemically and quantified in situ. H2O2 accumulation at reaction sites was evident within 1 h after inoculation in wild-type tobacco, whereas in 35S-SH-L plants the onset of H2O2 accumulation was delayed by 2-3 h. The delay in H2O2 generation was correlated with a reduction in the transient rise in SA that usually occurred within 1-2 h following inoculation in wild-type plants. Our data indicate that an early transient rise in SA potentiates the oxidative burst, with resultant effects on accumulation of H2O2, plant cell death and also defence-gene induction, factors that together may determine the outcome of plant-pathogen interactions.

Heat shock transcription factors and the hsp70 induction response in brain and kidney of the hyperthermic rat during postnatal development

Heat shock transcription factor (HSF) 1 levels increase in brain regions and decline in kidney during postnatal rat development. In both neonatal and adult rats, levels of HSF1 protein in brain and kidney are proportional to the levels of HSF DNA-binding activity and the magnitude of heat shock protein hsp70 induction after thermal stress. There appears to be more HSF1 protein in adult brain than is needed for induction of hsp70 after thermal stress, suggesting that HSF1 may have other functions in addition to its role as a stress-inducible activator of heat shock genes. HSF2 protein levels decline during postnatal rat development in brain regions and kidney. Gel mobility shift analysis shows that HSF2 is not in a DNA-binding form in the neonatal brain and kidney, suggesting that HSF2 may not be involved in the constitutive expression of hsps in early postnatal development. There is no apparent relationship between levels of HSF2 protein and basal levels of hsp90, hsp70, heat shock cognate protein hsc70, and hsp60.

Selective transport of SC1 mRNA, encoding a putative extracellular matrix glycoprotein, during postnatal development of the rat cerebellum and retina

The selective transport of mRNA species into peripheral processes of cells is an important aspect of gene expression in the nervous system. In this study, we report the transport of SC1 mRNA into the distal processes of Bergmann glial (BG) cells at particular stages of development. SC1 is a putative anti-adhesive extracellular matrix (ECM) glycoprotein that is expressed not only in the developing central nervous system (CNS) but also in the adult brain. The intracellular distribution of SC1 mRNA was examined in two highly laminated neural structures, the cerebellum and retina, during postnatal development and in the adult rat. Our results indicate that SC1 mRNA expression is both spatially and temporally regulated. SC1 message was localized to BG cell bodies at postnatal day 5 (P5) and P10. However, by P15 through to the adult, SC1 mRNA was transported to distal processes of BG cells in the synapse-rich molecular layer (ML) of the cerebellum. In the developing rat retina, SC1 mRNA was expressed in specific neuronal populations by P10, however, transport of SC1 message to the dendrites of these retinal neurons was not detected during development or in the adult. These results indicate neural mechanisms which control the timing and cell type in which selective transport of SC1 mRNA is observed. The localization of SC1 mRNA to the distal processes of BG cells in the synapse-rich ML of the cerebellum could facilitate local control of SC1 protein synthesis which may play roles in synapse formation during development and in synaptic plasticity in the adult.

Heat shock proteins Hsp27 and Hsp32 localize to synaptic sites in the rat cerebellum following hyperthermia

Stressful stimuli activate the heat shock (stress) response in which a set of heat shock proteins (hsps) is induced, which play roles in cellular repair and protective mechanisms. Most studies in the mammalian nervous system have focused on Hsp70, however, the present investigation targets other members of the induced set, namely Hsp27 and Hsp32. In response to hyperthermia, these hsps are strongly induced in Bergmann glial cells in the rat brain and transported into their radial fibers, which project into the 'synaptic-enriched' molecular layer of the cerebellum. Using subcellular fractionation and immunoelectron microscopy, hyperthermia-induced Hsp27 and Hsp32 were detected in synaptic elements and in perisynaptic glial processes. These results suggest that stress-induced Hsp27 and Hsp32 may contribute to repair and protective mechanisms at the synapse.

Localization of the heat-shock protein Hsp70 to the synapse following hyperthermic stress in the brain

Heat-shock proteins are induced in response to cellular stress. Although heat-shock proteins are known to function in repair and protective mechanisms, their relationship to critical neural processes, such as synaptic function, has received little attention. Here we investigate whether the major heat-shock protein Hsp70 localizes to the synapse following a physiologically relevant increase in temperature in the mammalian nervous system. Our results indicate that hyperthermia-induced Hsp70 is associated with pre- and postsynaptic elements, including the postsynaptic density. The positioning of Hsp70 at the synapse could facilitate the repair of stress-induced damage to synaptic proteins and also contribute to neuroprotective events at the synapse.

Neuroprotection at Drosophila synapses conferred by prior heat shock

Synapses are critical sites of information transfer in the nervous system, and it is important that their functionality be maintained under stressful conditions to prevent communication breakdown. Here we show that synaptic transmission at the Drosophila larval neuromuscular junction is protected by prior exposure to heat shock that strongly induces expression of heat shock proteins, in particular hsp70. Using a macropatch electrode to record synaptic activity at individual, visualized boutons, we found that prior heat shock sustains synaptic performance at high test temperatures through pre- and postsynaptic alterations. After heat shock, nerve impulses release more quantal units at high temperatures and exhibit fewer failures of release (presynaptic modification), whereas the amplitude of quantal currents remains more constant than does that in nonheat-shocked controls (postsynaptic modification). The time course of these physiological changes is similar to that of elevated hsp70. Thus, stress-induced neuroprotective mechanisms maintain function at synapses by modifying their properties.

Sex difference in the relationship of calcium and magnesium excretion to glycaemic control in type 1 diabetes mellitus

In order to assess the variability and possible causes of calcium and magnesium losses in diabetes mellitus, urinary calcium and magnesium excretion were monitored six monthly over a 3-year period in 108 stable, type 1 diabetic patients who were having assessment of their clinical status and glycaemic control over the same period. In the patients studied the ranges of excretion of both calcium and magnesium were considerably wider than our non-diabetic reference ranges but the within subject variation in excretion was high. However, using mean values obtained over the study period, a direct relationship was observed between the excretion of both calcium and magnesium and HbA1 in female patients (P < 0.01) but not in males who had similar HbA1 values. The urinary excretion of calcium and magnesium did not relate to any of the other clinical or biochemical indices measured, including body mass index, daily insulin dose, retinal status or albumin excretion. It is suggested that, in poorly controlled patients, females may have a greater risk than males of developing the complications associated with chronic calcium and magnesium loss.

Cellular localization of the heat shock transcription factors HSF1 and HSF2 in the rat brain during postnatal development and following hyperthermia

The heat shock transcription factor HSF1 mediates the induction of heat shock genes in response to temperature elevation and other traumatic events. The induced hsps play roles in cellular repair and protective mechanisms. Immunocytochemistry revealed that in the unstressed rat, HSF1 was already prepositioned in the nucleus at abundant levels in both neuronal and glial cell types. Following a fever-like temperature, glial cells rapidly induced hsp70 whereas populations of large neurons did not. The lack of hsp70 induction in these neurons in vivo did not appear to be due to deficiencies in levels of nuclear HSF1. During postnatal development of the cerebellum, levels of HSF1 increased progressively from day 1 to 30. Members of the hsp gene set are also constitutively expressed in the unstressed animal and play roles as molecular chaperones. HSF2, which has been proposed as a developmental regulator of constitutive heat shock gene expression, demonstrated a developmental alteration in cellular localization, namely a nuclear distribution in neurons at postnatal day 2 and a cytoplasmic localization at day 30. During postnatal development the overall levels of neural HSF2 declined. This profile showed no obvious correlation with previously observed levels of constitutive hsp expression during postnatal neural development.

Localized changes in peroxidase activity accompany hydrogen peroxide generation during the development of a nonhost hypersensitive reaction in lettuce

Peroxidase activity was characterized in lettuce (Lactuca sativa L.) leaf tissue. Changes in the activity and distribution of the enzyme were examined during the development of a nonhost hypersensitive reaction (HR) induced by Pseudomonas syringae (P. s.) pv phaseolicola and in response to an hrp mutant of the bacterium. Assays of activity in tissue extracts revealed pH optima of 4.5, 6.0, 5.5 to 6.0, and 6.0 to 6.5 for the substrates tetramethylbenzidine, guaiacol, caffeic acid, and chlorogenic acid, respectively. Inoculation with water or with wild-type or hrp mutant strains of P. s. pv phaseolicola caused an initial decline in total peroxidase activity; subsequent increases depended on the hydrogen donor used in the assay. Guaiacol peroxidase recovered more rapidly in tissues undergoing the HR, whereas changes in tetramethylbenzidine peroxidase were generally similar in the two interactions. In contrast, increases in chlorogenic acid peroxidase were significantly higher in tissues inoculated with the hrp mutant. During the HR, increased levels of Mn2+/2, 4-dichlorophenol-stimulated NADH and NADPH oxidase activities, characteristic of certain peroxidases, were found in intercellular fluids and closely matched the accumulation of H2O2 in the apoplast. Histochemical analysis of peroxidase distribution by electron microscopy revealed a striking, highly localized increase in activity within the endomembrane system and cell wall at the sites of bacterial attachment. However, no clear differences in peroxidase location were observed in tissue challenged by the wild-type strain or the hrp mutant. Our results highlight the significance of the subcellular control of oxidative reactions leading to the generation of reactive oxygen species, cell wall alterations, and the HR.

Constitutive expression of heat shock proteins Hsp90, Hsc70, Hsp70 and Hsp60 in neural and non-neural tissues of the rat during postnatal development

Heat shock proteins (Hsps) are a group of highly conserved proteins, that are constitutively expressed in most cells under normal physiological conditions. Previous work from our laboratory has shown that neurons in the adult brain exhibit high levels of Hsp90 and Hsc70 mRNA and protein, as well as basal levels of Hsp70 mRNA. We have now investigated the expression of Hsp90, Hsc70, Hsp60 and Hsp70 in neural and non-neural tissues of the rat during postnatal development, a time of extensive cell differentiation. Western blot analysis revealed constitutive expression of these Hsps early in postnatal development. Developmental profiles of these Hsps suggest that they are differentially regulated during postnatal development of the rat. For example, while levels of Hsp90 decrease somewhat in certain developing brain regions, levels of Hsp60 show a developmental increase, and Hsc70 protein is abundant throughout postnatal neural development. Low basal levels of Hsp70 are also observed in the developing and adult brain. A pronounced decrease in Hsp90 and Hsc70 was observed during postnatal development of the kidney while levels of Hsp60 increased. In addition, tissue-specific differences in the relative levels of these Hsps between brain and non-brain regions were found. Immunocytochemical studies demonstrated a neuronal localization of Hsp90, Hsc70 and Hsp60 at all stages of postnatal development examined as well as in the adult, suggesting a role for Hsps in both the developing and fully differentiated neuron. The developmental expression of subunit IV of cytochrome oxidase was similar to that of Hsp60, a protein localized predominantly to mitochondria.

Expression of SC1 is associated with the migration of myotomes along the dermomyotome during somitogenesis in early mouse embryos

SC1 is a secreted glycoprotein with a high amino acid sequence similarity to SPARC (Secreted Protein, Acidic, Rich in Cysteine). SC1 transcripts were first detected in mouse embryos after day 8.5 post coitus (p.c.) in somites at the medial lip of the dermomyotome. Expression of SC1 transcripts by the progenitor cells continued as they began involuting under the dermomyotome and during their migration along the lateral wall of the dermomyotome. After myotome migration was completed, SC1 mRNA expression was downregulated in the trunk region. The data indicate that SC1 expression is restricted to the initial stages of epaxial myotome differentiation and migration, undergoing rapid downregulation prior to myotome emigration from the somitic environment.

SPARC/osteonectin mRNA is induced in blood vessels following injury to the adult rat cerebral cortex

Recently we described the pattern of expression of the anti-adhesive glycoprotein SPARC/osteonectin in the developing and adult brain. SPARC mRNA was present in developing blood vessels during neurogenesis, but was not detected in the mature vasculature. We have now examined the effect of a lesion to the adult rat cerebral cortex on the expression of SPARC by in situ hybridization. SPARC mRNA was increased in the zone proximal to the wound at 3 to 10 days after cortical brain injury. During this period, SPARC was induced in mature blood vessels close to the lesion site and in blood vessels which develop following injury. These results suggest a role for SPARC in the process of angiogenesis following injury to the adult cerebral cortex.

Characterization of the heat shock response in the gills of sea lampreys and a brook lamprey at different intervals of their life cycles

The heat shock response (HSR) was characterized in the gills of two lamprey species that differ with respect to their adult life history. In vivo labelling with [35S]methionine revealed an enhanced synthesis of heat shock proteins (HSPs) having approximate molecular weights of 70 kDa (HSP70) and 90 kDa (HSP90) following heat treatment. Induction of the HSR occurred in larval lampreys (ammocoetes) following temperature elevations of 13-16 degrees C for the parasitic species, the sea lamprey (Petromyzon marinus) and 16-20 degrees C for the nonparasitic species, the brook lamprey (Lampetra appendix). The case in L. appendix represents the greatest increase in temperature required to induce the HSR in gill tissue among aquatic poikilotherms studied to data and induction occurs within a temperature range (25-29 degrees C) not normally experienced by these animals. Western blotting detected the presence of 70 and 90 kDa HSPs and HSP70 levels were greater in post-metamorphic L. appendix than in ammocoetes both before and after heat shock. The HSR of lampreys appears to be induced during times of emergency when large, rapid temperature increases are experienced. The high set-point temperature for induction of the response may be a consequence of both the environments they presently inhabit and their experiences during evolution.

Effect of hyperthermia on the transcription rate of heat-shock genes in the rabbit cerebellum and retina assayed by nuclear run-ons

The induction of heat-shock protein 70 (hsp70) mRNA in the hyperthermic rabbit brain has been examined previously by using Northern blotting and in situ hybridization procedures that measure steady-state levels of mRNA, which may be influenced by transcript stability and transcription rate. In the present investigation, the in vivo transcription rate of hsp70 has been examined by using run-on transcription assays on isolated brain nuclei. A major up-regulation in the transcription rate of hsp70 was observed between 0.75 and 1.50 hours after hyperthermia in the cerebellum and the retina. Gel-mobility shift assays revealed that the time course of conversion of heat-shock transcription factor (HSF1) to a DNA-binding form paralleled the transcriptional induction profile of hsp70. The transcription rates of several nonheat-shock genes were also studied in the hyperthermic brain, and little change was noted relative to the induction of hsp70. Thus, a physiologically relevant increase in temperature of 2.5 degrees C induces a major up-regulation in the in vivo transcription rate of hsp70 in the nervous system with little affect on the transcription rates of other genes.

Developmental analysis of factors binding to the mouse 68-kDa neurofilament promoter

Whole tissue extracts prepared from mouse brain regions at various postnatal ages were characterized for binding of factors to the DNase I hypersensitive site (HSSI) which is located closest to the transcription start site of the 68-kDa mouse neurofilament gene (NF-L). Gel mobility shift assays detected changes in factor binding during postnatal development of the neocortex. Competition experiments suggested that one of the complexes resulted from factor binding to a 9 bp sequence found in both the light and medium neurofilament promoter regions (NF-L/M). Gel mobility shifts performed with an oligonucleotide probe containing the NF-L/M sequence detected two brain-specific DNA-protein complexes, and a third complex in both brain and liver. During cerebellar and neocortical development, one of the NF-L/M complexes was most intense at postnatal day 10 when transcription of the NF-L gene is upregulated.

Differential induction of heat shock mRNA in oligodendrocytes, microglia, and astrocytes following hyperthermia

A time course analysis of hsp70 mRNA induction in response to a physiologically relevant increase in body temperature of 2.6 degrees C was performed in the rabbit forebrain. A protocol that combined in situ hybridization and cytochemistry on the same tissue section was employed to identify reactive glial cell types. Cytochemical markers for astrocytes, microglia, and oligodendrocytes were utilized in combination with a DIG-labelled hsp70 riboprobe, which permitted mRNA localization at high resolution. Four glial cell body-enriched regions of the rabbit forebrain were examined, namely, cortical layer 1, hippocampal fissure, corpus callosum, and fimbria. Maximal hsp70 mRNA induction was observed in 2 and 3 h hyperthermic animals. The colocalization analysis demonstrated that hsp70 mRNA was induced in oligodendrocytes and microglia, but not in forebrain GFAP positive astrocytes. In addition, cell counts were performed which showed that almost all oligodendrocytes induced hsp70 mRNA while a subpopulation of microglial cells responded. These data are consistent with the notion that oligodendrocytes, microglia, and astrocytes exhibit distinct thresholds for activation of the heat shock response following a physiologically relevant increase in body temperature.

Localization of hydrogen peroxide accumulation during the hypersensitive reaction of lettuce cells to Pseudomonas syringae pv phaseolicola

The active oxygen species hydrogen peroxide (H2O2) was detected cytochemically by its reaction with cerium chloride to produce electron-dense deposits of cerium perhydroxides. In uninoculated lettuce leaves, H2O2 was typically present within the secondary thickened walls of xylem vessels. Inoculation with wild-type cells of Pseudomonas syringae pv phaseolicola caused a rapid hypersensitive reaction (HR) during which highly localized accumulation of H2O2 was found in plant cell walls adjacent to attached bacteria. Quantitative analysis indicated a prolonged burst of H2O2 occurring between 5 to 8 hr after inoculation in cells undergoing the HR during this example of non-host resistance. Cell wall alterations and papilla deposition, which occurred in response to both the wild-type strain and a nonpathogenic hrpD mutant, were not associated with intense staining for H2O2, unless the responding cell was undergoing the HR. Catalase treatment to decompose H2O2 almost entirely eliminated staining, but 3-amino-1,2,4-triazole (catalase inhibitor) did not affect the pattern of distribution of H2O2 detected. H2O2 production was reduced more by the inhibition of plant peroxidases (with potassium cyanide and sodium azide) than by inhibition of neutrophil-like NADPH oxidase (with diphenylene iodonium chloride). Results suggest that CeCl3 reacts with excess H2O2 that is not rapidly metabolized during cross-linking reactions occurring in cell walls; such an excess of H2O2 in the early stages of the plant-bacterium interaction was only produced during the HR. The highly localized accumulation of H2O2 is consistent with its direct role as an antimicrobial agent and as the cause of localized membrane damage at sites of bacterial attachment.

Tissue-specific differences in heat shock protein hsc70 and hsp70 in the control and hyperthermic rabbit

The ability to resolve protein members of the hsp70 multigene family by two-dimensional Western blotting permitted the characterization of antibodies which were specific in discriminating constitutively expressed hsc70 isoforms from stress-inducible hsp70 isoforms. This antibody characterization demonstrated that basal levels of hsp70 isoforms were present in the cerebellum of the control rabbit and that these were elevated following hyperthermia, whereas levels of hsc70 were similar in control and hyperthermic tissue. Multiple isoforms of hsp70 were detected but tissue-specific differences were not apparent in various organs of the rabbit. However, species differences were observed as fewer hsp70 isoforms were noted in rat and mouse. In the control rabbit, higher levels of hsc70 protein were present in neural tissues compared to non-neural tissues. Following physiologically relevant hyperthermia, induction of hsp70 was greatest in non-neural tissues such as liver, heart, muscle, spleen, and kidney compared to regions of the nervous system. These studies suggest that the amount of preexisting constitutive hsc70 protein may influence the level of induction of hsp70 in the stress response. Given this observation, caution is required in the employment of hsp70 induction as an index of cellular stress since endogenous levels of hsc70, and perhaps hsp70, may modulate the level of induction.

Intracellular localization of heat shock mRNAs (hsc70 and hsp70) to neural cell bodies and processes in the control and hyperthermic rabbit brain

Heat shock proteins are essential cellular proteins that may play important roles in cellular repair and/or protection. This report focuses on the expression of two members of the hsp70 multigene family, namely, constitutive hsc70 mRNA and stress-inducible hsp70 mRNA in the control and hyperthermic rabbit brain. The intracellular localization of these heat shock mRNAs was examined using high-resolution nonradioactive in situ hybridization. The distribution of hsc70 mRNA and hsp70 mRNA was examined in (1) neuronal cell bodies and their dendritic processes and (2) oligodendrocytes and their cellular processes. In control animals, hsc70 mRNA was detected in the apical dendritic processes and cell bodies of cortical layer II and V neurons, CA3 and CA4 neurons, deep cerebellar neurons, and brainstem neurons. A time course analysis of hsc70 mRNA, after a physiologically relevant increase in body temperature of 2.6 degrees C, revealed more distal transport of this constitutive message into dendrites of these neuronal populations. In the same neuronal populations, basal levels of hsp70 mRNA were observed in the cell body; however, this mRNA was not detected in dendritic processes in control or hyperthermic animals. After hyperthermia, hsp70 mRNA was strongly induced in oligodendrocytes and transported to the processes of these glial cells. The localization of heat shock messages in the processes of these neural cell types could provide a mechanism for local control of synthesis of heat shock proteins in cellular compartments that are remote from the cell body.

The neuronal stress response: nuclear translocation of heat shock proteins as an indicator of hyperthermic stress

Two characteristic features of the heat shock response, (i) induction of hsp70 protein and (ii) nuclear translocation of constitutive hsc70 and stress-inducible hsp70 protein, were utilized as markers of cellular stress in the rabbit brain. Following a physiologically relevant increase in body temperature of 2.7 +/- .3 degrees C, nonneuronal cell types, such as ependymal cells and oligodendrocytes, undergo a stress response as assayed by the above criteria. In contrast, several neuronal cell populations required an increased degree of hyperthermic stress (3.4 +/- .2 degrees C) before exhibiting nuclear translocation of constitutive hsc70 protein. Induction of hsp70 protein was not observed in these neuronal cells at either temperature. The present results suggest that certain neurons in the rabbit brain are buffered against induction of the heat shock response, perhaps due to their high constitutive levels of hsc70 protein.

SC1, a brain extracellular matrix glycoprotein related to SPARC and follistatin, is expressed by rat cerebellar astrocytes following injury and during development

In the nervous system, extracellular matrix components are believed to influence cell shape, proliferation and migration during development and following injury. SC1 is a secreted glycoprotein expressed during neural development and in the adult brain. The molecule shows partial sequence homology to the anti-adhesive extracellular matrix molecule SPARC/osteonectin and to follistatin. We have made a surgical lesion in the adult rat cerebellum and examined changes in SC1 expression at 1 to 14 days after injury. Dual in situ hybridization/immunohistochemistry demonstrated that SC1 mRNA was induced in astrocytes surrounding the wound, reaching maximal levels at 10 days post-lesion. Immunohistochemistry revealed changes in the deposition of SC1 protein in radial fibres of Bergmann glia. SC1 protein was also detected at the border of the lesion, suggesting an association with the glial scar. Double immunohistochemistry with the astrocytic marker GFAP demonstrated that astrocytes also express SC1 during postnatal development.

Characterization of DNase I hypersensitive sites in the mouse 68-kDa neurofilament gene

Four brain-specific DNase I hypersensitive sites (HSS) have previously been identified flanking the mouse 68-kDa neurofilament gene within a 1.7 kb upstream sequence which confers neuronal specificity of expression of this gene in transgenic mice. Previously several DNA-binding factors were detected at the HSS closest to the transcription start site (HSS1). However, no major brain-specific factors were identified, suggesting a possible role for the three remaining HSS in conferring tissue-specificity to the NF-L gene. Sequence analysis of the NF-L promoter region demonstrated the presence of an extensive CT repeat and several potential binding sites which are also found in other neurofilament promoters. Gel mobility shift assays revealed a similar but not identical banding pattern with brain and liver nuclear extracts at HSS2, and HSS3, however the banding pattern for HSS4 was predominantly brain-specific. DNase I footprinting revealed several factors binding to the upstream HSS regions in brain and liver nuclear extracts. These include a CCAAT box at HSS2, a novel brain-specific footprint near an adenovirus promoter element E2aE-C beta and a single liver-specific footprint associated with an POU/octamer binding site at HSS4. The presence of brain-specific gel shift bands and tissue-specific footprints associated with HSS4, suggest that this region may play an important role in the regulation of the NF-L gene.

In vivo activation of neural heat shock transcription factor HSF1 by a physiologically relevant increase in body temperature

Molecular mechanisms which underlie the heat shock response have commonly been analyzed using tissue culture systems, with less investigation of the intact mammal. In tissue culture, a temperature elevation of 5 degrees C is required to activate mammalian heat shock transcription factor 1 (HSF1) to the DNA-binding form. We demonstrate that a physiologically relevant increase in body temperature of 2.5 +/- 0.2 degrees C, similar to that attained during fever reactions, is sufficient to activate HSF1 in the rabbit nervous system. Maximal HSF activation, as measured by gel mobility shift assay, was attained at 1 hr with the cerebellum showing the strongest signal. Supershift experiments with antibodies specific to HSF1 and HSF2 demonstrated that the signal reflected activation of HSF1. Western blot analysis showed that cerebellum exhibited high levels of HSF1 protein.

SC1, a SPARC-related glycoprotein, exhibits features of an ECM component in the developing and adult brain

Although extracellular matrix (ECM) components have been shown to play important roles in the development of the CNS, expression generally decreases in the adult brain. This study examines the expression of the SPARC-related glycoprotein SC1 in the rat brain during postnatal development and in the adult. In situ hybridization analysis indicates that expression of SC1 mRNA increases in a caudal to rostral manner as postnatal neural development proceeds and is found at near maximal levels in the adult brain. SC1 mRNA is expressed in glial-enriched areas of the brain at postnatal day 1 (P1) and P5. Between P10 and P20, SC1 mRNA increases in neuron-enriched regions of the hippocampus, dentate gyrus, and cerebral cortex. Immunohistochemistry in the adult shows that SC1 protein is localized to neurons in these regions and to scattered glial cells. Subcellular fractionation demonstrates that the SC1 116/120 kDa doublet is associated with synaptosomes. SC1 is present in the aqueous phase following extraction of membranes with TX-114, suggesting that it is not a transmembrane protein, a property consistent with other adult brain ECM components. Furthermore in cerebellar granule cells grown in culture, high levels of the 120 kDa component are secreted into the media. These results are consistent with the hypothesis that SC1 is an ECM glycoprotein expressed in both the developing and adult brain.

CaM I mRNA is localized to apical dendrites during postnatal development of neurons in the rat brain

In the rat, a single calmodulin (CaM) protein is encoded by three separate genes which produce five different transcripts. The significance of the multiple CaM genes is not known; however, individual CaM transcripts could be targeted to specific intracellular sites. In this report, the cellular distribution of CaM I mRNAs was analyzed in the postnatal rat brain. The 4.0-kb CaM I transcript was present in neuronal cell bodies and also localized to apical dendritic processes. In cerebral cortical neurons, the 4.0-kb CaM I mRNA was detected in apical dendrites at postnatal day (PD) 5 to 15. In hippocampal neurons, this CaM message was present in dendritic processes from PD S to 20, whereas in Purkinje neurons it was detected in dendrites at PD 15 and 20. The presence of the 4.0-kb CaM I mRNA in dendrites of the rat brain supports the notion of targeting transcripts derived from the CaM multigene family to discrete intracellular destinations.

Alteration of CaM I mRNA expression in the developing rat superior colliculus following chronic treatment with an NMDA receptor antagonist

The spatial distribution of CaM I mRNA was investigated in the developing superior colliculus of rats that were chronically treated with the NMDA receptor antagonist AP-5. In control animals, CaM I message was localized in a continuous band of cells that extended across the entire rostro caudal axis of the superficial superior colliculus. Chronic AP-5 treatment resulted in a specific reduction of CaM I message in the caudal colliculus at postnatal day 10. Since normal NMDA receptor function has been implicated in activity dependent synaptic plasticity in the superior colliculus, these results suggest that the regulation of calmodulin may be part of a cascade of events that mediate this plasticity following NMDA receptor activation.

Expression of mRNA species encoding heat shock protein 90 (hsp90) in control and hyperthermic rabbit brain

Northern blot and in situ hybridization were employed to investigate regional and cell type differences in the expression of hsp90 mRNA species in control and hyperthermic rabbit brain. Riboprobes specific to hsp90 alpha and beta mRNA species were utilized in time-course Northern blot studies on cerebral hemispheres and the cerebellum. Following hyperthermia, levels of hsp90 alpha and beta mRNA were elevated in both brain regions; however, the magnitude of induction was more robust in the cerebellum than in cerebral hemispheres. The pattern of expression of hsp90 genes in rabbit brain was analyzed by in situ hybridization. These studies revealed that hsp90 genes are preferentially expressed in neuronal cell populations in the unstressed mammalian brain. The distribution of hsp90 alpha and beta mRNA was similar, though the signal for the latter was stronger. Following hyperthermia, changes were not detected in the pattern of hsp90 beta mRNA expression in the hippocampus. In the cerebellum, a rapid induction of hsp90 beta mRNA was apparent in the neuron-enriched granule cell layer, followed by a delayed accumulation in Purkinje neurons. Unlike hsp70, induction of hsp90 was not detected in glial cells of hyperthermic rabbit brain. The localization of hsp90 to neurons suggests that this heat shock protein plays an important role in neuronal function.

A child with an intra-abdominal testicular teratoma: a case report and review of prepubertal cryptorchid germ cell tumors

OBJECTIVES

We report the case of a tumor in an intra-abdominal cryptorchid testis of a 7-month-old male infant. Torsion of a testicular teratoma was confirmed by pathologic examination. A review was undertaken to identify and characterize other reports of prepubertal cryptorchid germ cell neoplasms.

METHODS

Cases of testicular germ cell neoplasms in association with cryptorchidism in phenotypically normal males were identified through a MEDLINE search of the English literature and review of published bibliographies.

RESULTS

A total of 14 cases were identified with testis location provided in 12 patients. Half of the neoplasms were located in abdominal testis, and all of these were associated with torsion, although 2 of 6 patients were asymptomatic. Two patients had tumors in the contralateral normally descended testis. Teratoma was the most frequently encountered tumor type.

CONCLUSIONS

Characteristics of prepubertal cryptorchid testicular germ cell tumors reflect those seen in post-pubertal cryptorchid tumors in location but differ in histologic type. Possible pathogenesis is discussed. Follow-up was not provided in all cases although outcome appears to be good. We believe that these lesions are likely underreported.

Developmental expression of calmodulin mRNA and protein in regions of the postnatal rat brain

The expression of calmodulin (CaM) protein and mRNA was analyzed in specific regions of the rat brain during postnatal development. CaM levels in the adult brain were more abundant in the cerebral hemispheres and thalamus compared to brain stem and superior plus inferior colliculus. All brain regions contained higher CaM protein and mRNA levels than in non-neural tissues such as the kidney. During postnatal development of the brain, maximal levels of CaM protein and CaM I mRNAs were attained at day 10 or 15. Protein levels declined thereafter in the adult in all regions except the thalamus. With respect to products of the rat CaM I gene, the 4.0 kb neural transcript demonstrated a pronounced increase during postnatal development, whereas the 1.8 kb message showed little change.

Localization of constitutive and hyperthermia-inducible heat shock mRNAs (hsc70 and hsp70) in the rabbit cerebellum and brainstem by non-radioactive in situ hybridization

Neural expression of constitutive hsc70 mRNA and hyperthermia-inducible hsp70 mRNA is examined using radioactive and non-radioactive in situ hybridization procedures. A strong induction of hsp70 mRNA was noted in cell populations in cerebellar layers and in the brainstem which demonstrated expression of mRNA encoding proteolipid protein, an oligodendrocyte marker. The non-radioactive in situ hybridization procedure using digoxigenin (DIG)-UTP-labeled riboprobes permitted improved signal localization, and stress-inducible hsp70 mRNA was detected at the cytoplasmic cap areas of individual oligodendrocytes. Cell types which express constitutive members of the hsc/hsp70 multigene family were also identified. Neurons in the brainstem and in the deep white matter and molecular layer of the cerebellum showed expression of hsc70 mRNA while signal was not detected in adjacent glial cells. A neuron-specific enolase riboprobe aided in the identification of neuronal cell types. The non-radioactive DIG riboprobe revealed that hsc70 mRNA was highly localized to the cytoplasm of individual neurons. High constitutive levels of hsc70 in certain neurons may dampen hsp70 induction after hyperthermia in these cell populations.

Expression of heat shock protein 90 (hsp90) in neural and nonneural tissues of the control and hyperthermic rabbit

Tissue-specific differences were apparent in the constitutive level of hsp90 in various body tissues of the unstressed rabbit. Western blotting with monoclonal antibody 29A revealed very low levels in muscle and highest levels in neural regions (cerebellum, cerebral hemispheres, and retina) and in testes and thymus. Intermediate levels were apparent in other tissues such as liver, kidney, heart, and small intestine. Following hyperthermia, induction of hsp90 was not detected with 1-D Western blotting in tissues which demonstrated high constitutive levels; however, elevations were noted in tissues which showed lower constitutive amounts of the protein, such as kidney, heart, and muscle. Immunocytochemical studies revealed that hsp90 is preferentially localized to neuronal cell populations in the rabbit brain and that this pattern does not alter following hyperthermic conditions which result in glial induction of hsp70. In kidney, where constitutive levels of hsp90 are lower than in brain, an induction of hsp90 was noted in renal tubules following hyperthermia.

Expression of low-molecular-weight neurofilament (NF-L) mRNA during postnatal development of the mouse brain

A regional Northern blot analysis demonstrated that the highest levels of NF-L mRNA in the adult mouse brain are present in brain stem followed by mid-brain, with lower levels found in neocortex, cerebellum, and hippocampus. The study was extended to the cellular level over course of postnatal development using in situ hybridization. This developmental analysis revealed that the expression of NF-L mRNA closely follows the differentiation pattern of many large neurons during postnatal neurogenesis. Neurons which differentiate early such as Purkinje, mitral, pyramidal, and large neurons of brain stem and thalamic nuclei, expressed high levels of NF-L mRNA at postnatal day 1. Early expression of NF-L mRNA may be required for the maintenance of the extensive neurofilament protein networks that are detected within the axons of larger neurons. Smaller neurons which differentiate later, such as dentate gyrus granule cells, small pyramidal and granule cells of the neocortex, and granule cells of the cerebellum, exhibit a delayed expression of NF-L mRNA.

SPARC, an extracellular matrix glycoprotein containing the follistatin module, is expressed by astrocytes in synaptic enriched regions of the adult brain

Although extracellular matrix (ECM) glycoproteins play important roles in neural development, their levels are generally believed to decrease in the adult brain. Immunohistochemical analysis indicates that the anti-adhesive ECM glycoprotein SPARC/osteonectin, which contains a follistatin 'module,' is expressed in the adult rabbit nervous system. In the cerebellum, SPARC is present in Bergmann glia, with a strong signal along their radial fibres. SPARC, while enriched in membrane fractions, is not a transmembrane protein. In the hippocampus, colocalization of SPARC is observed in cells which express the astrocytic marker GFAP. The expression of SPARC by a subset of astrocytes, particularly in synaptic enriched areas, suggests a continuing role for the ECM in the adult brain.

Deficient induction of human hsp70 heat shock gene transcription in Y79 retinoblastoma cells despite activation of heat shock factor 1

One of the basic features of the inducible heat shock response is the activation of heat shock factor which results in the rapid transcriptional induction of the heat shock genes. Although it is widely considered that the heat shock response is ubiquitous, several reports have indicated that the transcriptional response can vary in both intensity and kinetics and often in a tissue-specific manner. Of interest have been studies on the expression of heat shock genes in the brain, particularly observations that certain cultured neuronal cells exhibit a diminished heat shock response. We demonstrate that transcription of the gene encoding a 70-kDa heat shock protein (hsp70) is diminished upon heat shock in Y79 human retinoblastoma cells (which are of neuronal origin) despite both the activation of heat shock factor 1 and induced transcription of another heat shock gene, hsp90 alpha. This uncoupling of stress-induced transcription of the hsp70 and hsp90 alpha genes, which are typically coordinately regulated in response to stress, appears to be due to the selective inability of trans-acting factors, including heat shock factor 1, to bind in vivo to the hsp70 promoter as the result of a chromatin-mediated effect.

Expression of the gene encoding the extracellular matrix glycoprotein SPARC in the developing and adult mouse brain

The pattern of expression of the SPARC gene was examined during postnatal development of the mouse brain using in situ hybridization. At postnatal day 3 (P3), a strong signal representing SPARC mRNA was apparent in boundary layers such as the pia mater and the lining of the ventricles. By P12, increased levels of SPARC mRNA were noted in the cerebellum, midbrain and brain stem with a lower signal in more frontal areas, a pattern which was retained in the adult. This pronounced caudal versus frontal difference in SPARC mRNA levels was confirmed by Northern blot analysis. At P3, SPARC mRNA was detected in developing blood vessels in the cerebral cortex, suggesting a role for SPARC in angiogenesis. During development of the cerebellum, expression of SPARC mRNA became highly restricted to the Purkinje cellular layer and in the adult was localized to Bergmann glial cells rather than Purkinje neurons.

One year comparative trial of metformin and glipizide in type 2 diabetes mellitus

Forty-eight diabetic subjects with diet-failed Type 2 mellitus, aged 40-69 years, were randomised to metformin (24 patients) or glipizide (24 patients) therapy, and followed prospectively for 12 months. Most subjects were obese. Metformin gave better fasting plasma glucose control compared to glipizide at 24 (p < 0.01), 36 (p < 0.05) and 52 weeks (p < 0.05) with a lower HbA1 concentration at 52 weeks (p < 0.05). Metformin treated patients lost weight whereas glipizide treated subjects gained weight. The weight change between the treatment groups reached significance at 4 weeks (p < 0.05) and was highly significant (p < 0.001) at 8, 12, 24, 36 and 52 weeks. There were no significant changes in either fasting plasma lipid or blood lactate levels in either the metformin or glipizide treated groups. Both drugs caused a similar reduction in albumin excretion rates. In conclusion, metformin gave better glycaemic control than glipizide, with weight loss rather than weight gain in obese Type 2 patients.

Induction of heat shock (stress) protein 70 and its mRNA in the normal and light-damaged rat retina after whole body hyperthermia

In situ hybridization and immunocytochemistry were used to investigate the distribution of the 70 kDa heat shock or stress protein (hsp70) and its mRNA in specific layers of the retina of adult rats at 0, 4, 18, and 48 or 50 hr after a brief whole body hyperthermic treatment. Induction of hsp70 mRNA was noted in the photoreceptor layer of the retina within 4 hr after hyperthermia. Pronounced accumulation of inducible hsp70 immunoreactivity was observed in cytoplasmic extensions of the photoreceptor cells, especially the inner segment zone which attained peak levels at the 18 hr time point. Selective destruction of photoreceptors by light damage prior to hyperthermia inhibited the post-hyperthermic rise in newly synthesized retinal hsp70. Our results suggest that the photoreceptor cell layer is the primary site of synthesis of hsp70 in the rat retina and that the greatest increase in hsp70 immunoreactivity following such a hyperthermic stress occurs in that layer. This stress response of the photoreceptors is discussed in relation to their location and function in the retina.

Developmental expression in the rat cerebellum of SC1, a putative brain extracellular matrix glycoprotein related to SPARC

In the nervous system, extracellular matrix (ECM) molecules have been shown to have effects on cell migration, process outgrowth and the survival of neurons. Recently we have described the molecular cloning of SC1, a putative brain extracellular matrix glycoprotein, showing partial similarity to the ECM glycoprotein SPARC/osteonectin. We have now examined the expression of SC1 during the development of the rat cerebellum at both the protein and mRNA levels. Our results indicate that SC1 is both temporally and spatially regulated during this process. Bergmann glial cells express SC1 mRNA and the resultant protein is deposited along the length of their radial fibres during the process of granule cell migration in the developing cerebellum. SC1 mRNA and protein is also found in the adult cerebellum, concentrated in the Bergmann glial cells and their radial processes, indicating that this putative ECM molecule continues to play roles in the central nervous system after migration and proliferative events have ceased.

Temporal and spatial distribution of heat shock mRNA and protein (hsp70) in the rabbit cerebellum in response to hyperthermia

We have previously investigated the expression of hsp70 genes in the hyperthermic rabbit brain at the mRNA level by Northern blot and in situ hybridization procedures. Our studies have now been extended to the protein level utilizing Western blot and immunocytochemistry. Using an antibody which is specific to inducible hsp70, a prominent induction of hsp70 protein in glial cells of hyperthermic animals was noted. In particular, Bergmann glial cells in the cerebellum are strongly immunoreactive while adjacent Purkinje neurons are immunonegative. Extension of our in situ hybridization studies to a time course analysis revealed that the initial glial induction events were followed by a delayed accumulation of inducible hsp70 mRNA in Purkinje neurons at 10 hr post-heat shock. In control animals, high levels of constitutively expressed hsc70 mRNA and protein were observed in Purkinje neurons. Similar hsc70 and hsp70 mRNA observations were also made in neurons of the deep cerebellar nuclei and in motor neurons of the spinal cord. Our results suggest that these neuronal cell types accumulate hsp70 mRNA in response to hyperthermic treatment; however, the response is delayed when compared to the rapid response seen in glial cells. The high constitutive levels of hsc70 in certain neuronal cell types may play a role in the initial dampening of the hsp70 induction response in these cells.

Modulation of a neuronal calmodulin mRNA species in the rat brain stem by reserpine

Reserpine evokes transsynaptic impulse activity by depleting catecholaminergic neurotransmitters in the rat brain. Previous studies suggest a relationship between catecholaminergic activity and calmodulin concentration. In this report we employ Northern blot analysis to examine the effect of a single subcutaneous injection of reserpine on levels of calmodulin mRNA species which are preferentially expressed in neurons of the rat brain. Regional differences in mRNA levels were also investigated by in situ hybridization and drug-induced changes were noted particularly in specific regions of the rat brain stem. The riboprobe used in the in situ hybridization study recognized a 4.0 kilobase neuronal calmodulin mRNA species (NGB1), which was derived from the rat CaM1 gene. A calmodulin radio-immunoassay was utilized to demonstrate a drug-induced increased in calmodulin protein levels in a region which included the brain stem.