Structural comparison of three types of staphylococcal cassette chromosome mec integrated in the chromosome in methicillin-resistant Staphylococcus aureus

The beta-lactam resistance gene mecA of Staphylococcus aureus is carried by a novel mobile genetic element, designated staphylococcal cassette chromosome mec (SCCmec), identified in the chromosome of a Japanese methicillin-resistant S. aureus (MRSA) strain. We now report identification of two additional types of mecA-carrying genetic elements found in the MRSA strains isolated in other countries of the world. There were substantial differences in the size and nucleotide sequences between the elements and the SCCmec. However, new elements shared the chromosomal integration site with the SCCmec. Structural analysis of the new elements revealed that they possessed all of the salient features of the SCCmec: conserved terminal inverted repeats and direct repeats at the integration junction points, conserved genetic organization around the mecA gene, and the presence of cassette chromosome recombinase (ccr) genes responsible for the movements of SCCmec. The elements, therefore, were considered to comprise the SCCmec family of staphylococcal mobile genetic elements together with the previously identified SCCmec. Among 38 epidemic MRSA strains isolated in 20 countries, 34 were shown to possess one of the three typical SCCmec elements on the chromosome. Our findings indicated that there are at least three distinct MRSA clones in the world with different types of SCCmec in their chromosome.

D-beta-hydroxybutyrate protects neurons in models of Alzheimer's and Parkinson's disease

The heroin analogue 1-methyl-4-phenylpyridinium, MPP(+), both in vitro and in vivo, produces death of dopaminergic substantia nigral cells by inhibiting the mitochondrial NADH dehydrogenase multienzyme complex, producing a syndrome indistinguishable from Parkinson's disease. Similarly, a fragment of amyloid protein, Abeta(1-42), is lethal to hippocampal cells, producing recent memory deficits characteristic of Alzheimer's disease. Here we show that addition of 4 mM d-beta-hydroxybutyrate protected cultured mesencephalic neurons from MPP(+) toxicity and hippocampal neurons from Abeta(1-42) toxicity. Our previous work in heart showed that ketone bodies, normal metabolites, can correct defects in mitochondrial energy generation. The ability of ketone bodies to protect neurons in culture suggests that defects in mitochondrial energy generation contribute to the pathophysiology of both brain diseases. These findings further suggest that ketone bodies may play a therapeutic role in these most common forms of human neurodegeneration.

A common silencer element in the SCG10 and type II Na+ channel genes binds a factor present in nonneuronal cells but not in neuronal cells

We have localized a cell type-specific silencer element in the SCG10 gene by deletion analysis. This neural-restrictive silencer element (NRSE) selectively represses SCG10 expression in nonneuronal cells and tissues. The NRSE contains a 21 bp region with striking homology to a sequence present in a silencer domain of the rat type II sodium channel (NaII), another neuron-specific gene. We have identified a sequence-specific protein(s) that binds the SCG10 NRSE, as well as the homologous element in the NaII gene. A point mutation in the NRSE that abolishes binding of this neural-restrictive silencer-binding factor (NRSBF) in vitro also eliminates silencing activity in vivo. NRSBF is present in nuclear extracts from nonneuronal cells but not in extracts from neuronal cells, suggesting that the neuron-specific expression of SCG10 reflects, at least in part, the absence or inactivity of this protein. These data identify the NRSE as a potentially general DNA element for the control of neuron-specific gene expression in vertebrates.

Identification of the differential distribution patterns of mRNAs and consensus binding sequences for mouse DAF-16 homologues

daf-16 is a forkhead-type transcription factor, functioning downstream of insulin-like signals, and is known to be critical to the regulation of life span in Caenorhabditis elegans. Mammalian DAF-16 homologues include AFX, FKHR and FKHRL1, which contain a conserved forkhead domain and three putative phosphorylation sites for the Ser/Thr kinase Akt/protein kinase B (PKB), as well as for DAF-16. To assess the function of the homologues, we examined tissue distribution patterns of mRNAs for DAF-16 homologues in mice. In the embryos, expressions of AFX, FKHR and FKHRL1 mRNAs were complementary to each other and were highest in muscle, adipose tissue and embryonic liver. The characteristic expression pattern remained in the adult, except that signals of FKHRL1 became evident in more tissues, including the brain. In order to clarify whether each DAF-16 homologue had different target genes, we determined the consensus sequences for the binding of DAF-16 and the mouse homologues. The binding sequences for all four proteins shared a core sequence, TTGTTTAC, daf-16 family protein-binding element (DBE) binding protein. However, electrophoretic mobility shift assay showed that the binding affinity of DAF-16 homologues to the core sequence was stronger than that to the insulin-responsive element in the insulin-like growth factor binding protein-1 promoter region, which has been identified as a binding sequence for them. We identified one copy of the DBE upstream of the first exon of sod-3 by searching the genomic database of C. elegans. Taken together, DAF-16 homologues can fundamentally regulate the common target genes in insulin-responsive tissues and the specificity to target genes of each protein is partially determined by the differences in their expression patterns.

Methamphetamine-related psychiatric symptoms and reduced brain dopamine transporters studied with PET

OBJECTIVE

A positron emission tomography (PET) study has suggested that dopamine transporter density of the caudate/putamen is reduced in methamphetamine users. The authors measured nucleus accumbens and prefrontal cortex density, in addition to caudate/putamen density, in methamphetamine users and assessed the relation of these measures to the subjects' clinical characteristics.

METHOD

PET and 2-beta-carbomethoxy-3beta-(4-[(11)C] fluorophenyl)tropane, a dopamine transporter ligand, were used to measure dopamine transporter density in 11 male methamphetamine users and nine male comparison subjects who did not use methamphetamine. Psychiatric symptoms in methamphetamine users were evaluated by using the Brief Psychiatric Rating Scale and applying a craving score.

RESULTS

The dopamine transporter density in all three of the regions observed was significantly lower in the methamphetamine users than the comparison subjects. The severity of psychiatric symptoms was significantly correlated with the duration of methamphetamine use. The dopamine transporter reduction in the caudate/putamen and nucleus accumbens was significantly associated with the duration of methamphetamine use and closely related to the severity of persistent psychiatric symptoms.

CONCLUSIONS

These findings suggest that longer use of methamphetamine may cause more severe psychiatric symptoms and greater reduction of dopamine transporter density in the brain. They also show that the dopamine transporter reduction may be long-lasting, even if methamphetamine use ceases. Further, persistent psychiatric symptoms in methamphetamine users, including psychotic symptoms, may be attributable to the reduction of dopamine transporter density.

The NGF-inducible SCG10 mRNA encodes a novel membrane-bound protein present in growth cones and abundant in developing neurons

We have characterized and sequenced cDNA clones corresponding to the neural-specific SCG10 mRNA. The predicted amino acid sequence is novel and not strongly homologous to that of any known polypeptide. The protein is encoded by two mRNAs that differ in their choice of polyadenylation site. Immunocytochemical localization experiments using an affinity-purified antibody (against an SCG10-TrpE fusion protein) reveal accumulations of punctate staining in the perinuclear cytoplasm, axons, and growth cones of cultured neurons. SCG10 levels are maximal in the embryonic CNS but are dramatically reduced in the adult. Preliminary cell fractionation experiments suggest that the protein is tightly associated with membranes but is not itself an integral membrane protein. The apparent localization and timing of expression of the SCG10 protein are reminiscent of GAP-43, but the sequences of the two polypeptides are unrelated. Cross-hybridizing mRNAs and antigenically related proteins are found in several nonneuronal cell lines that do not express SCG10.

Neural restrictive silencer factor recruits mSin3 and histone deacetylase complex to repress neuron-specific target genes

Accumulative evidence suggests that more than 20 neuron-specific genes are regulated by a transcriptional cis-regulatory element known as the neural restrictive silencer (NRS). A trans-acting repressor that binds the NRS, NRSF [also designated RE1-silencing transcription factor (REST)] has been cloned, but the mechanism by which it represses transcription is unknown. Here we show evidence that NRSF represses transcription of its target genes by recruiting mSin3 and histone deacetylase. Transfection experiments using a series of NRSF deletion constructs revealed the presence of two repression domains, RD-1 and RD-2, within the N- and C-terminal regions, respectively. A yeast two-hybrid screen using the RD-1 region as a bait identified a short form of mSin3B. In vitro pull-down assays and in vivo immunoprecipitation-Western analyses revealed a specific interaction between NRSF-RD1 and mSin3 PAH1-PAH2 domains. Furthermore, NRSF and mSin3 formed a complex with histone deacetylase 1, suggesting that NRSF-mediated repression involves histone deacetylation. When the deacetylation of histones was inhibited by tricostatin A in non-neuronal cells, mRNAs encoding several neuronal-specific genes such as SCG10, NMDAR1, and choline acetyltransferase became detectable. These results indicate that NRSF recruits mSin3 and histone deacetylase 1 to silence neural-specific genes and suggest further that repression of histone deacetylation is crucial for transcriptional activation of neural-specific genes during neuronal terminal differentiation.

Distribution of metastatic lymph nodes in colorectal cancer by the modified clearing method

PURPOSE

The aim of this study was to clarify the distribution of lymph node metastasis in colorectal cancer. We also examined the relationship between the primary tumor (T) and the regional node (N) categories of the TNM (primary tumor, regional nodes, metastasis) classification.

METHOD

Lymph nodes of surgical specimens in 311 consecutive patients with colorectal cancer were studied using the modified clearing method.

RESULTS

Lymph node metastasis was seen in 59.2 percent of the total cases. The upward metastasis rate was 30.7 percent. In the longitudinal spread, most of the lymph node metastasis was seen within 10 cm. On the oral side in rectal cancer, there was no metastasis beyond 4 cm. The lateral metastasis rate in rectal cancer was 8.8 percent and in the lower rectum, the rate of cancer within 6 cm from the anal verge or beyond pT3 was much higher.

CONCLUSION

In the TNM classification, there was no significant difference between colon and rectal cancer except pT1 with rectal cancer. In the lower rectal cancer within 6 cm from the anal verge or beyond pT3, there is a high risk of lateral metastasis, and lateral lymph node dissection or radiation therapy should be performed.

Translocation of neonicotinoid insecticides from coated seeds to seedling guttation drops: a novel way of intoxication for bees

The death of honey bees, Apis mellifera L., and the consequent colony collapse disorder causes major losses in agriculture and plant pollination worldwide. The phenomenon showed increasing rates in the past years, although its causes are still awaiting a clear answer. Although neonicotinoid systemic insecticides used for seed coating of agricultural crops were suspected as possible reason, studies so far have not shown the existence of unquestionable sources capable of delivering directly intoxicating doses in the fields. Guttation is a natural plant phenomenon causing the excretion of xylem fluid at leaf margins. Here, we show that leaf guttation drops of all the corn plants germinated from neonicotinoid-coated seeds contained amounts of insecticide constantly higher than 10 mg/l, with maxima up to 100 mg/l for thiamethoxam and clothianidin, and up to 200 mg/l for imidacloprid. The concentration of neonicotinoids in guttation drops can be near those of active ingredients commonly applied in field sprays for pest control, or even higher. When bees consume guttation drops, collected from plants grown from neonicotinoid-coated seeds, they encounter death within few minutes.

A cell type-preferred silencer element that controls the neural-specific expression of the SCG10 gene

SCG10 is a growth-associated protein that is expressed early in the development of neuronal derivatives of the neural crest. We describe here the isolation of the SCG10 chromosomal gene and the identification of regulatory regions that control its expression. The SCG10 transcription unit spans approximately 40 kb. Like other neural-specific genes, SCG10 contains multiple transcription initiation sites. The gene contains a constitutive enhancer-like element in the promoter-proximal region and a silencer located farther upstream. This silencer preferentially suppresses the activity of the enhancer in nonneuronal cells. Furthermore, the silencer is able to confer such preferential suppression upon a heterologous promoter in an orientation-independent manner. These data suggest that the expression of SCG10 in neuronal cells depends predominantly upon specific derepression.

UCP1 deficiency increases susceptibility to diet-induced obesity with age

Loss of nonshivering thermogenesis in mice by inactivation of the mitochondrial uncoupling protein gene (Ucp1-/- mice) causes increased sensitivity to cold and unexpected resistance to diet-induced obesity at a young age. To clarify the role of UCP1 in body weight regulation throughout life and influence of UCP1 deficiency on longevity, we longitudinally analyzed the phenotypes of Ucp1-/- mice maintained in a room at 23 degrees C. There was no difference in body weight and lifespan between genotypes under the standard chow diet condition, whereas the mutant mice developed obesity with age under the high-fat (HF) diet condition. Compared with Ucp1+/+ mice, Ucp1-/- mice showed increased expression of genes related to thermogenesis and fatty acid metabolism, such as beta3-adrenergic receptor, in adipose tissues of the 3-month-old mutants; however, the augmented expression was reduced in Ucp1+/+ mice in 11-month-old Ucp1-/- mice fed the HF diet. Likewise, the increased levels of UCP3 and cAMP-dependent protein kinase in the brown adipose tissue of Ucp1-/- mice given the standard diet were decreased significantly in that of Ucp1-/- mice fed the HF diet, which animals showed impaired norepinephrine-induced lipolysis in their adipose tissues. These results suggest profound attenuation of beta-adrenergic responsiveness and fatty acid utilization in Ucp1-/- mice fed the HF diet, bringing them to late-onset obesity. Our findings provide evidence that UCP1 is neither essential for body weight regulation nor for longevity under conditions of standard diet and normal housing temperature, but deficiency increases susceptibility to obesity with age in combination with HF diet.

Human recombinant TNF suppresses lipoprotein lipase activity and stimulates lipolysis in 3T3-L1 cells

Tumor necrosis factor (TNF) has been reported to be identical to "cachectin," a monokine which we have previously proposed as a mediator of the enhanced catabolism observed in patients or animals responding to various invasive stimuli such as infections. Detailed quantitative studies were conducted on the effects of TNF on fatty acid metabolism in 3T3-L1 cells in order to explore the extent of the catabolic effects exerted by TNF compared with those by the crude cachectin. 3T3-L1 adipocytes responded to recombinant human TNF, showing a decrease in LPL activity and an increase in intracellular lipolysis. When TNF in the crude cachectin preparation was completely neutralized with anti-TNF antibody, about 75% of LPL suppression activity in the crude cachectin was absorbed, indicating that most of the mediator responsible for LPL suppression in the crude preparation is TNF. In contrast to the above effect on LPL, TNF markedly increased the lipolysis of stored fat in the cells. The effect on LPL was observed as early as 2 h after the addition of TNF, but enhancement of lipolysis required a time lag of at least 3 h before any increase of glycerol release became apparent. The effective concentrations of TNF for the stimulation of lipolysis were much higher (2.5 to 49 nM) than those for LPL suppression (50 pM to 50 nM), but both were in the same range as the concentration required for tumoricidal effect. These results demonstrate that cachectin is synonymous with TNF and that it plays an important role in the pathophysiology of deranged lipid metabolism through both suppression of LPL and enhancement of lipolysis in patients coping with invasive conditions such as infections.

Identification of a functional silencer element involved in neuron-specific expression of the synapsin I gene

We have identified a functional silencer element (positions -231 to -211) in the human synapsin I gene that selectively represses its transcription in nonneuronal cells. Transfection experiments using synapsin I-luciferase constructs show that site-specific mutations or deletion of this silencer sequence results in expression of the reporter gene in nonneuronal cells. Moreover, the silencer element is capable of conferring repression on a heterologous promoter in nonneuronal cells. Gel-shift assays reveal the presence of a sequence-specific synapsin I silencer-binding protein in nonneuronal cell extracts but not in neuronal cell extracts. Mutagenesis studies of the silencer sequence demonstrate that formation of the specific silencer-protein complex in vitro correlates well with repression of transcription in vivo. These data indicate that the interaction between synapsin I silencer and its binding protein is involved in tissue-specific expression of the synapsin I gene. In addition, our results suggest the existence of at least one additional cis-acting element within the promoter-proximal region (positions -233 to +20) that also contributes to the neuron-specific expression of the synapsin I gene.

Isolation and biochemical characterization of hemorrhagic toxin f from the venom of Crotalus atrox (western diamondback rattlesnake)

Hemorrhagic toxin f (HT-f) was isolated from Crotalus atrox (Western Diamondback Rattlesnake) venom by a five-step purification procedure. Homogeneity was established by the formation of a single band in acrylamide gel electrophoresis, isoelectric focusing, and sodium dodecyl sulfate (SDS)-electrophoresis. HT-f has a molecular weight of 64,000 and contains 572 amino acid residues. It contains 1 mol of zinc per mol of protein. Zinc is essential for both hemorrhagic and proteolytic activities. HT-f possesses proteolytic activity hydrolyzing the Val-Asn, Gln-His, Leu-Cys, His-Leu, Ala-Leu, and Tyr-Leu bonds of oxidized insulin B chain. HT-f did not coagulate fibrinogen to fibrin, yet it did hydrolyze the gamma chain of fibrinogen without affecting either the A alpha or B beta chains. This is the first time that a hemorrhagic toxin was shown to have fibrinogenase activity. HT-f was shown to differ immunologically from other hemorrhagic toxins such as HT-a and HT-c. HT-f also possesses lethal toxicity. When zinc was removed the apo-HT-f lost its lethal toxicity. HT-f produced not only local hemorrhage in the skin and muscle, but also produced systemic hemorrhage in internal organs such as the intestine, kidney, lung, heart, and liver.

A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Antiepileptic effects of inhibitors of nitric oxide synthase examined in pentylenetetrazol-induced seizures in rats

The effects of intraperitoneal NG-methyl-L-arginine and N omega-nitro-L-arginine methyl ester, specific inhibitors of nitric oxide (NO) synthase, were examined on the pentylenetetrazol (PTZ)-induced seizures in rats. The incidence and latency for the onset of myoclonic jerks, clonic seizures, and tonic generalized extension were observed as specific parameters among PTZ-induced seizures. Both drugs preferentially suppressed the tonic generalized extension and prolonged the latency for the onset of each parameter, suggesting NO has a significant effect on the PTZ-induced seizure.

Salmonella enteritidis FliC (flagella filament protein) induces human beta-defensin-2 mRNA production by Caco-2 cells

Antimicrobial peptides are crucial for host defense at mucosal surfaces. Bacterial factors responsible for induction of human beta-defensin-2 (hBD-2) mRNA expression in Caco-2 human carcinoma cells were determined. Salmonella enteritidis, Salmonella typhimurium, Salmonella typhi, Salmonella dublin, and culture supernatants of these strains induced hBD-2 mRNA expression in Caco-2 human carcinoma cells. Using luciferase as a reporter gene for a approximately 2.1-kilobase pair hBD-2 promoter, the hBD-2-inducing factor in culture supernatant of S. enteritidis was isolated. The supernatant factor was heat-stable and proteinase-sensitive. After purification by anion exchange and gel filtration chromatography, the hBD-2-inducing factor was identified as a 53-kDa monomeric protein with the amino-terminal sequence AQVINTNSLSLLTQNNLNK, which is identical to that of the flagella filament structural protein (FliC) of S. enteritidis. Consistent with this finding, the 53-kDa protein reacted with anti-FliC antibody, which prevented its induction of hBD-2 mRNA in Caco-2 cells. In agreement, the hBD-2-inducing activity in culture supernatant was completely neutralized by anti-FliC antibody. In gel retardation analyses, FliC increased binding of NF-kappaB (p65 homodimer) to hBD-2 gene promoter sequences. We conclude that S. enteritidis FliC induces hBD-2 expression in Caco-2 cells via NF-kappaB activation and thus plays an important role in up-regulation of the innate immune response.

Comparative study of activities in reactive oxygen species production/defense system in mitochondria of rat brain and liver, and their susceptibility to methylmercury toxicity

The involvement of oxidative stress has been suggested as a mechanism for neurotoxicity caused by methylmercury (MeHg), but the mechanism for MeHg selective toxicity in the central nervous system is still unclear. In this research, to clarify the mechanism of selective neurotoxicity caused by MeHg, the oxygen consumption levels, the reactive oxygen species (ROS) production rates and several antioxidant levels in mitochondria were compared among the cerebrum, cerebellum and liver of male Wistar rats. In addition, the alterations of these indexes were examined in MeHg-intoxicated rats (oral administration of 10 mg/kg day, for 5 days). Although the cerebrum and cerebellum in intact rats showed higher mitochondrial oxygen consumption levels and ROS production rates than the liver, glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities were much lower in the cerebrum and cerebellum than in the liver. Especially, the cerebellum showed the highest oxygen consumption and ROS production rate and the lowest mitochondrial glutathione (GSH) levels among the tissues examined. In the MeHg-treated rats, decrease in the oxygen consumption and increase in the ROS generation were found only in the cerebellum mitochondria, despite a lower Hg accumulation in the mitochondrial fraction compared to the liver. Since MeHg treatment produced an enhancement of ROS generation in cerebellum mitochondria supplemented with succinate substrates, MeHg-induced oxidative stress might affect the complex II-III mediated pathway in the electron transfer chain in the cerebellum mitochondria. Our study suggested that inborn factors, high production system activity and low defense system activity of ROS in the brain, would relate to the high susceptibility of the central nervous system to MeHg toxicity.

Effects of prolonged strenuous exercise on plasma levels of atrial natriuretic peptide and brain natriuretic peptide in healthy men

BACKGROUND

Now that marathon racing is growing in popularity, many thousands of enthusiastic athletes are participating in various ultramarathons all over the world each year. However, it remains controversial whether such a sport contributes to the promotion of health. The occurrence of transient cardiac dysfunction and irreversible myocardial injury has been reported in association with such exercise in healthy individuals. Brain natriuretic peptide (BNP) is a cardiac hormone, as is atrial natriuretic peptide (ANP), and its measurement has been widely used for clinical evaluation of cardiac dysfunction. However, little is known about the response of plasma BNP to prolonged strenuous exercise. We hypothesized that confirmation of minimal cardiac dysfunction or myocardial injury may be made by measurements of plasma BNP.

METHODS

Levels of plasma ANP, BNP, catecholamines, blood lactate, and serum cardiac troponin T (cTnT) were determined before and after a 100-km ultramarathon in 10 healthy men to examine the effects of the exercise on levels of ANP and BNP and correlations between the natriuretic peptides and cTnT as a marker for myocardial damage.

RESULTS

Whereas all variables significantly increased after the race, increased levels of ANP and BNP were most strongly correlated with increases in cTnT levels. The cTnT level after the race was greater than the upper reference limit in 9 of 10 men.

CONCLUSIONS

Such exercise significantly increased ANP and BNP levels in healthy men, and the increases could be partially attributed to myocardial damage during the race.

An ESR-CT imaging of the head of a living rat receiving an administration of a nitroxide radical

Three-dimensional ESR imaging of a living rat has been performed by an L-band ESR system, which is composed of an L-band ESR spectrometer, a field gradient coil, and a data processor. The imaging was carried out by Lauterbur's method. A nitroxide, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (Carbamoyl-PROXYL), was used as an imaging agent in saline solution at a concentration of 0.2 M and administered intraperitoneally to obtain a constant concentration in the head for about an hour. It took about 40 min to obtain one set of ESR-CT images. The cross-sectional images were made, both as coronal and horizontal images. In the images of the rat head the nitroxide-rich region was clearly distinguished from the deficient region. The nitroxide-deficient areas corresponded well to the brain of the rat.

Stress protein-induced immunosuppression: inhibition of cellular immune effector functions following overexpression of haem oxygenase (HSP 32)

This is the first report on suppression of immune effector functions following upregulation of heat shock protein 32 (HSP 32), known as haem oxygenase (HO-1). Here we evaluated the effect of cobalt-protoporphyrin (CoPP)-induced HO-1 expression on cell-mediated immune responses. Administration of CoPP to CBA mice resulted in overexpression of HO-1 in the spleen, liver and kidneys. In vitro measurements of T cell-mediated and NK-cell-mediated cytotoxicity in spleens from CoPP-treated animals demonstrated a severe suppression of their effector functions while administration of Zn-PP or vitamin B12 had no effect. Furthermore, CoPP therapy decreased the lymphoproliferative alloresponse and differentiation of cytotoxic T cells. Inhibition of proliferation appeared to be due to cell growth arrest with an increased number of cells staying in G0/G1 phase. Despite the suppressed proliferative response, IL-2 production in the MLR was not inhibited. In contrast, CoPP decreased the production of IL-10, IFN-gamma and TNF-alpha. In vivo, CoPP prolonged the survival of heterotopic heart allografts in mice. The immunosuppressive effects following CoPP-mediated upregulation of HO-1 were similar to those observed after peptide-mediated upregulation of HO-1. The results indicate that overexpression of HO results in the inhibition of several immune effector functions and thus provides an explanation for stress-induced immunosuppression.