Mapping dopamine D2/D3 receptor function using pharmacological magnetic resonance imaging

RATIONALE

Regulation of dopamine release and synthesis occurs via pre-synaptic dopamine (DA) D2/D3 autoreceptors (DARs). Mapping of DAR function in vivo is difficult and is usually best assessed using invasive measures of DA release, such as microdialysis at discrete sites. We wished to show that pharmacological magnetic resonance imaging (phMRI) may prove useful for this purpose.

OBJECTIVE

To demonstrate that the relative cerebral blood volume (rCBV) changes induced by amphetamine can be modulated by DA D2 receptor antagonists and agonists in a manner consistent with modulation of DAR function and to compare these effects with microdialysis.

METHODS

We used phMRI with iron oxide contrast agents to map changes in rCBV in response to an amphetamine challenge, pre-treatment and post-treatment with varying doses of the D2 antagonist eticlopride and the D2 agonist quinpirole. We also compared the effects of D2 antagonism using microdialysis measurements of DA release.

RESULTS

Antagonism of D2 receptors with eticlopride potentiated rCBV changes induced by amphetamine in the nucleus accumbens and caudate putamen in a dose-dependent manner. The amphetamine-induced increase in rCBV in the accumbens in animals pre-treated with eticlopride was paralleled by a similar percentage increase in DA release measured by means of microdialysis. Conversely, agonism of D2 receptors using quinpirole reduced amphetamine-induced rCBV changes in the caudate putamen and nucleus accumbens. The effects of both quinpirole and eticlopride on amphetamine-induced rCBV changes were largest in the nucleus accumbens.

CONCLUSIONS

These results suggest that phMRI may potentially prove useful to map DAR function non-invasively in multiple brain regions simultaneously.

Mapping interactions between dopamine and adenosine A2a receptors using pharmacologic MRI

Adenosine receptors in the basal ganglia are implicated in regulation of dopamine function and release. We investigated the interactions between dopamine receptors and adenosine receptors in the basal ganglia using pharmacologic MRI (phMRI) in rats. Stimulation of dopamine receptors was achieved using administration of 2 mg/kg of amphetamine. Then we investigated the antagonism of these changes using the selective A2a receptor antagonist 3,7-dimethyl-1-propargylaxanthine (DMPX). Amphetamine alone caused large increases (10-30%) in relative cerebral blood volume (rCBV) in caudate/putamen (CPu), nucleus accumbens (NAcc), thalamus, and frontal and cingulate cortices with changes that persisted for 70-80 min. DMPX alone (5 mg/kg) induced decreases in rCBV (approximately 8-10%) in NAcc, CPu, and olfactory tubercule, with smaller changes in thalamus (-6%) consistent with the regional distribution of A2a receptors. We examined the interactions between amphetamine and DMPX by assessing the effects of DMPX (5 mg/kg) administration 20 min after injection of 3 mg/kg amphetamine. These experiments showed that DMPX immediately decreased the rCBV increase induced by amphetamine in NAcc, CPu, and thalamus but not in cingulate or sensorimotor cortex. Companion microdialysis experiments showed that dopamine release in CPu was decreased in a similar manner. These experiments demonstrate the utility of phMRI for probing, in a noninvasive manner, the temporal and spatial dynamics of neurotransmitter interactions.

Expression of p50 C-terminal Src kinase (Csk) in mouse testis

C-terminal Src Kinase (Csk) is a cytoplasmic tyrosine kinase that phosphorylates a critical tyrosine residue in each of the Src family kinases to inhibit their activities. To investigate the possible regulation of spermatogenesis by Src-Csk loop, the postnatal changes in the expression of Csk were examined in mouse testes. Semiquantitative RT-PCR analysis revealed that Csk mRNA increased during neonatal development and peaked at 2 weeks of age. Following the decrease during pubertal development, Csk expression re-increased in adult testes. In Western blot, immature testes showed higher expression of Csk protein than the pubertal or adult testes. In immature testis, Csk immunoreactivity was largely found in the Sertoli cell and there was no visible difference in the Csk immunoreactivity among the seminiferous tubules. In adult testis, however, a differential Csk immunoreactivity was found among the seminiferous tubules. Intense signal was found in the adluminal cytoplasm of the Sertoli cells bearing the post-meiotic differentiating germ cells, suggesting that Csk may participate in the remodeling of seminiferous tubule during late phase of spermatogenesis. Csk immunoreactivity was also found in the Leydig cells, suggesting the possible regulation of Leydig cell function. Src-Csk loop may participate in the differentiation of the seminiferous epithelia and Leydig cells in mouse testis.

Exogenous contrast agent improves sensitivity of gradient-echo functional magnetic resonance imaging at 9.4 T

Relative to common clinical magnetic field strengths, higher fields benefit functional brain imaging both by providing additional signal for high-resolution applications and by improving the sensitivity of endogenous contrast due to the blood oxygen level dependent (BOLD) mechanism, which has limited detection power at low magnetic fields relative to the use of exogenous contrast agent. This study evaluates the utility of iron oxide contrast agent for gradient echo functional MRI at 9.4 T in rodents using cocaine and methylphenidate as stimuli. Relative to the BOLD method, the use of high iron doses and short echo times provided a roughly twofold global increase in functional sensitivity, while also suppressing large vessel signal and reducing susceptibility artifacts. Furthermore, MRI measurements of the functional percentage change in cerebral blood volume (CBV) showed excellent agreement with results obtained at much lower magnetic field strengths, demonstrating that MRI estimates of this quantity are roughly independent of magnetic field when appropriate techniques are employed. The derived field dependencies for relative sensitivity and MRI estimates of the percentage change in CBV suggest that the benefits provided by exogenous agents will persist even at much higher magnetic fields than 9.4 T.

Magnetic resonance spectroscopic analysis of Alzheimer's disease mouse brain that express mutant human APP shows altered neurochemical profile

Transgenic mice that express mutant human amyloid precursor protein (APPTg2576) develop beta-amyloid (Abeta) plaques throughout the cortex starting at 10-12 months of age. We examined the neurochemical profile of APPTg2576 mice using in vitro and in vivo magnetic resonance spectroscopy (MRS); gross abnormalities using magnetic resonance imaging (MRI) and plaque distribution; size and number using immunohistochemistry. Transgenic mice were anesthetized with halothane and scanned at 4.7 T using T2-weighted imaging and in vivo MRS of frontal cortex. In vitro MRS was run from brain extracts of frontal cortex in both APP and wild-type mice. Mice were also perfused and brains were collected and cut for immunohistochemistry. We found that N-acetylaspartate (NAA), glutamate and glutathione were decreased by 17%, 22% and 36%, respectively, in the cerebral cortex of APP transgenic mice at 19 months of age when Abeta deposits are widespread. Taurine was increased 21% compared to wild-type. Decreased levels of NAA and increased levels of taurine are consistent with decreased neuronal viability and increased glial volume, and are similar to findings of decreased NAA and increased myo-inositol in human Alzheimer's disease (AD) brains. Correlation between the severity of Abeta deposition and altered neurochemical profile remains to be studied. Nevertheless, the altered neurochemical profile may be a valuable marker to test therapeutics in this mouse model.

Basal ganglia activity remains elevated after movement in focal hand dystonia

Although previous studies of focal hand dystonia have detected cortical sensorimotor abnormalities, little is known about the role of the basal ganglia in this disorder. We report here that when focal hand dystonic patients performed finger-tapping tasks, functional magnetic resonance imaging showed persisting elevations of basal ganglia activity after the tasks ended. We posit that inhibitory control of the basal ganglia may be faulty in focal hand dystonia, and that the increases we observe in "resting" activity may mask basal ganglia abnormalities in standard imaging contrast analyses.

Immune evasion strategies of Kaposi's sarcoma-associated herpesvirus

To establish lifelong infection in the presence of an active host immune system, herpesviruses have acquired an impressive array of immune modulatory mechanisms that contribute to their success as long-term parasites. Kaposi's sarcoma-associated herpesvirus (KSHV) is the most recently discovered human tumor virus and is associated with the pathogenesis of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. KSHV has acquired a battery of genes to assist in viral survival against the host immune response. These viral gene products target a variety of host immune surveillance mechanisms, including the cytokine-mediated immune response, apoptosis, natural killer (NK) cell killing and T cell-mediated responses. This review summarizes our understanding of the role of these viral proteins in the escape from host immune surveillance, which ultimately contributes to lifelong infection and pathogenesis of KSHV.

Interactions of very long-chain saturated fatty acids with serum albumin

The remarkable binding properties of serum albumin have been investigated extensively, but little is known about an important class of fatty acids, the very long-chain saturated fatty acids (VLCFA; >18 carbons). Although VLCFA are metabolized efficiently in normal individuals, they are markers for and possibly causative agents of several peroxisomal disorders. We studied the binding of [(13)C]carboxyl-enriched arachidic (C20:0), behenic (C22:0), lignoceric (C24:0), and hexacosanoic (C26:0) acids to bovine serum albumin (BSA) by (13)C-NMR spectroscopy. For each VLCFA, the NMR spectra showed multiple signals at chemical shifts previously identified for long-chain fatty acids (12-18 carbons), suggesting stabilization of binding by similar, if not identical, interactions of the fatty acid carboxyl anion with basic amino acid residues. The maximal binding (mol of VLCFA/mol of BSA) and the number of observed binding sites decreased with increasing chain length, from 4-5 for C20:0, 3-4 for C22:0, and 2 for C24:0; we validated our previous conclusion that BSA has only one site for C26:0 (Ho, J. K., H. Moser, Y. Kishimoto, and J. A. Hamilton. 1995. J. Clin. Invest. 96: 1455-1463). Analysis of chemical shifts suggested that the highest affinity sites for VLCFA are low affinity sites for long-chain fatty acids. In competition experiments with (13)C-labeled C22:0 (3 mol/mol of BSA) and unlabeled oleic acid, C22:0 bound to BSA in the presence of up to 4 mol of oleic acid/mol of BSA, but 1 mol was shifted into a different site. Our studies suggest that albumin has adequate binding capacity for the low plasma levels of VLCFA with 20 to 26 carbons, but the protein may not be able to bind longer chain VLCFA.

Variable site of oropharyngeal narrowing and regional variations of oropharyngeal collapsibility among snoring patients during wakefulness and sleep

The oropharynx shows rhythmic caliber changes in accordance with the respiratory cycle. Dynamic imaging of the oropharynx is required to evaluate airway changes associated with snoring and obstructive sleep apnea. The purpose of this study was to determine the sites of narrowing/obstruction and to measure the regional collapsibility of the oropharynx during respiration during the sleep and awake cycles in snoring patients. Seven snoring patients were included for this study. Electron Beam Tomograms of the oropharynx were taken while the patient was awake and asleep, and dynamic views were reconstructed. The site of narrowing or obstruction varied widely among patients and differed from awake to asleep. The mean of smallest minimum cross-sectional area of the oropharynx was 60.38+/-42.97 mm2 in the awake state and 16.90+/-20.43 mm2 in the asleep state. Although the collapsibility of the oropharynx showed considerable regional variations, it increased during sleep at the overall oropharynx. The low retropalatal region showed the smallest minimum cross-sectional area and the highest collapsibility; however, the most prominent changes in the minimum cross-sectional area and collapsibility during sleep were observed in the high retroglossal region.

Promotion of cell cycle progression by basic helix-loop-helix E2A

Normal B-cell development requires the E2A gene and its encoded transcription factors E12 and E47. Current models predict that E2A promotes cell differentiation and inhibits G(1) cell cycle progression. The latter raises the conundrum of how B cells proliferate while expressing high levels of E2A protein. To study the relationship between E2A and cell proliferation, we established a tissue culture-based model in which the activity of E2A can be modulated in an inducible manner using E47R, an E47-estrogen fusion construct, and E47ERT, a dominant negative E47-estrogen fusion construct. The two constructs were subcloned into retroviral vectors and expressed in the human pre-B-cell line 697, the human myeloid progenitor cell line K562, and the murine fibroblastic cell line NIH 3T3. In both B cells and non-B cells, suppression of E2A activity by E47ERT inhibited G(1) progression and was associated with decreased expression of multiple cyclins including the G(1)-phase cyclin D2 and cyclin D3. Consistent with these findings, E2A null mice expressed decreased levels of cyclin D2 and cyclin D3 transcripts. In complementary experiments, ectopic expression of E47R promoted G(1) progression and was associated with increased levels of multiple cyclins, including cyclin D2 and cyclin D3. The induction of some cyclin transcripts occurred even in the absence of protein synthesis. We conclude that, in some cells, E2A can promote cell cycle progression, contrary to the present view that E2A inhibits G(1) progression.

Trichodinid ectoparasites (ciliphora: Peritrichida) of some marine fishes from coastal regions of the Yellow Sea and Bohai Sea

Five species of marine fishes, including two of the main maricultured fishes from coastal regions of the Yellow Sea and Bohai Sea, were examined for ectoparasitic trichodinids. A total of five species of trichodinids belonging to three genera, Trichodina Ehrenberg, 1830, Paratrichodina Lom, 1963 and Trichodinella Srámek-Husek, 1953 were reinvestigated following dry silver impregnation. These were: Trichodina rectuncinata Raabe, 1958, T. jadranica (Raabe, 1958) Haider, 1964, Paratrichodina globonuclea Lom, 1963, P. obliqua Lom, 1963 and Trichodinella lomi Xu, Song & Warren, 1999. Morphometric data and comparative descriptions of these trichodinids are provided along with details of their prevalence and intensity of infestation.

Hybrid HIV/MSCV LTR enhances transgene expression of lentiviral vectors in human CD34(+) hematopoietic cells

HIV-based lentiviral vectors can transduce nondividing cells, an important advantage over murine leukemia virus (MLV)-based vectors when transducing slowly dividing hematopoietic stem cells. However, we find that in human CD34(+) hematopoietic cells, the HIV-based vectors with an internal cytomegalovirus (CMV) promoter express transgenes 100- to 1,000-fold less than the MLV-based retroviral vector murine stem cell virus (MSCV). To increase the expression of the integrated lentivirus, we replaced CMV promoter with that of the Rous sarcoma virus or MSCV and obtained a modest augmentation in expression. A more dramatic effect was seen when the CMV enhancer/promoter was removed and the HIV long-terminal repeat (LTR) was replaced by a novel HIV/MSCV hybrid LTR. This vector retains the ability to transduce nondividing cells but now expresses its transgene (enhanced green fluorescent protein) 10- to 100-fold greater than the original HIV-based vector. When compared under identical conditions, the HIV vector with the hybrid LTR transduced a higher percentage of CD34(+) cells than the MSCV-based retroviral vector (19.4% versus 2.4%). The number of transduced cells and level of transgene expression remain constant over 5-8 weeks as determined by long-term culture-initiating cells, fluoresence-activated cell sorting, and nonobese diabetic/severe combined immunodeficiency repopulation assay.

C-terminal fragment of amyloid precursor protein induces astrocytosis

One of the pathophysiological features of Alzheimer's disease is astrocytosis around senile plaques. Reactive astrocytes may produce proinflammatory mediators, nitric oxide, and subsequent reactive oxygen intermediates such as peroxynitrites. In the present study, we investigated the possible role of the C-terminal fragment of amyloid precursor protein (CT-APP), which is another constituent of amyloid senile plaque and an abnormal product of APP metabolism, as an inducer of astrocytosis. We report that 100 nM recombinant C-terminal 105 amino acid fragment (CT105) of APP induced astrocytosis morphologically and immunologically. CT105 exposure resulted in activation of mitogen-activated protein kinase (MAPK) pathways as well as transcription factor NF-kappaB. Pretreatment with PD098059 and/or SB203580 decreased nitric oxide (NO) production and nuclear factor-kappa B (NF-kappaB) activation. But inhibitors of NF-kappaB activation did not affect MAPKs activation whereas they abolished NO production and attenuated astrocytosis. Furthermore, conditioned media derived from CT105-treated astrocytes enhanced neurotoxicity and pretreatment with NO and peroxynitrite scavengers attenuated its toxicity. These suggest that CT-APP may participate in Alzheimer's pathogenesis through MAPKs- and NF-kappaB-dependent astrocytosis and iNOS induction.

High performance liquid chromatographic analysis of a new proton pump inhibitor KR60436 and its active metabolite O-demethyl-KR60436 in rat plasma samples using column-switching

A fully automated high performance liquid chromatography with column-switching was developed for the simultaneous determination of KR60436, a new reversible proton pump inhibitor, and its active metabolite O-demethyl-KR60436 from rat plasma samples. Plasma sample (50 microl) was directly introduced onto a Capcell Pak MF Ph-1 column (10 x 4 mm I.D.) where primary separation was occurred to remove proteins and concentrate target substances using acetonitrile-potassium phosphate (pH 7, 0.1 M) (2:8, v/v). The drug molecules eluted from MF Ph-1 column were focused in an intermediate column (10 x 2 mm I.D.) by the valve switching step. The substances enriched in intermediate column were eluted and separated on a Vydac 218MR53 column (250 x 3.2 mm I.D.) using acetonitrile-potassium phosphate (pH 7, 0.02 M) (47:53, v/v) at a flow rate of 0.5 ml/min when the valve status was switched back to A position. The method showed excellent sensitivity (detection limit of 2 ng/ml) with small volume of samples (50 microl), good precision and accuracy, and speed (total analysis time 24 min) without any loss in chromatographic efficiency. The response was linear (r2 > or = 0.999) over the concentration range of 5-500 ng/ml.

Effects of occupation, lifestyle and genetic polymorphisms of CYP1A1, CYP2E1, GSTM1 and GSTT1 on urinary 1-hydroxypyrene and 2-naphthol concentrations

This study was undertaken to determine the effects of occupation, lifestyle and the genetic polymorphisms of cytochrome P450 1A1 (CYP1A1), cytochrome P450 2E1 (CYP2E1) and glutathione S-transferases micro1 (GSTM1) and 1 (GSTT1) on the concentrations of urinary 1-hydroxypyrene (1-OHP) and 2-naphthol among Korean coke oven workers and university students. The study subjects included 90 coke oven workers and 128 university students. A questionnaire was used to obtain detailed data about the work area, smoking habits and food intake of subjects. Associations between urinary polycyclic aromatic hydrocarbon (PAH) concentrations and occupation, smoking status, total airborne PAH level and genetic polymorphisms were tested. Urinary 1-OHP and 2-naphthol concentrations were higher in coke oven workers than in students and correlated significantly with work area. Urinary 2-naphthol concentrations increased with an increase in the level of cigarette smoking in students. Total airborne PAH level correlated with urinary 1-OHP concentration in coke oven workers. Urinary 1-OHP and 2-naphthol concentrations were higher in coke oven workers with the c1/c2 or c2/c2 genotype of CYP2E1 than in those with the c1/c1 genotype. Urinary 2-naphthol concentrations were higher in GSTM1-null workers than in GSTM1-positive workers. In multiple regression analysis CYP2E1 was a significant factor determining urinary 1-OHP concentrations in coke oven workers. CYP2E1 and GSTM1 were significant determinants for urinary 2-naphthol concentrations in coke oven workers and GSTM1 and smoking were prognosticators among university students. Urinary 1-OHP is a better indicator of occupational exposure to PAH in coke oven workers than 2-naphthol, whereas urinary 2-naphthol may be more sensitive for non-occupational inhalation exposure to PAH. In occupationally exposed populations CYP2E1 and GSTM1 appear to play an important role in the metabolism of pyrene and naphthalene. In individuals not occupationally exposed to PAHs GSTM1 and smoking seem to influence the urinary concentration of 2-naphthol.

Counterion-dye staining method for DNA in agarose gels using crystal violet and methyl orange

Sensitive and safe methods for visualization of DNA in agarose gels are described. 0.001% crystal violet dissolved in distilled water was used for DNA staining on agarose gels and it could detect as little as 16 ng of DNA (3 kb, pGem-7Zf/EcoRI) without destaining procedure. The detection limit is four times lower than that of ethidium bromide. To improve the sensitivity, we studied a counterion-dye staining method using methyl orange as a counterion-dye which contributes to reduce excessive background staining by crystal violet. Dye concentration, pH of staining solution, mixing molar ratio of two dyes, and staining times were optimized for the counterion-dye staining. By the staining with a mixed solution of 0.0025% crystal violet and 0.0005% methyl orange in distilled water, 8 ng of the 3 kb DNA in an agarose gel was detected within 30 min.

Generation of a murine single chain Fv (scFv) antibody specific for cucumber mosaic virus (CMV) using a phage display library

With the long-term goal of generating CMV-resistant transgenic plants using antibody genes, a single-chain variable fragment (scFv) antibody that binds to the cucumber mosaic virus was isolated from a scFv phage display library by four rounds of affinity selection with CMV-Mf as an antigen. The scFv has the identical binding specificity to CMV as a monoclonal antibody that is generated by the hybridoma fusion technique, and recognized purified preparations of CMV isolates belonging to either subgroup I or II in immunoblotting. The nucleotide sequences of the recombinant antibody showed that a heavy chain variable region (V(H)) gene belonged to the VH3 subgroup and the kappa light chain variable region (V kappa) came from the Vkappa4 subgroup. Our results demonstrate that the scFv phage display library, an alternative approach to the traditional hybridoma fusion technique, has a potential applicability in the study of plant virus and plant pathology.

2,2-Dimethyl-4,5-diaryl-3(2H)furanone derivatives as selective cyclo-oxygenase-2 inhibitors

A series of 2,2-dimethyl-5-[4-(methylsulfonyl)phenyl]-4-phenyl-3(2H)furanones was prepared and evaluated for their ability to inhibit cyclo-oxygenase-2 (COX-2).

Broad bean wilt virus Causes Necrotic Symptoms and Generates Defective RNAs in Capsicum annuum

ABSTRACT A virus was isolated from hot pepper (Capsicum annuum cv. Hyang Chon) growing in Korea and displaying necrotic spots or streaks on leaves and stems followed by stunting and death of plants. Morphological and host range analyses of extracts from infected plants suggested that the causal agent of disease was a Broad bean wilt virus (BBWV), and the virus was tentatively named a Korean isolate of BBWV (BBWV-K). When the isolate was back-inoculated onto hot pepper plants, it induced symptoms similar to those of naturally infected hot pepper in the field. Two coat proteins (CPs) of 44 and 22 kDa, corresponding to a large CP and a small CP, respectively, were identified from the virus, and both reacted specifically with polyclonal antibody to BBWV 2. The complete nucleotide sequences of RNA 1 and RNA 2 of the isolate were determined from cDNA clones. The deduced amino acid sequence data from the putative proteins encoded by RNA 1 and 2 of the BBWV-K indicated a closer relationship with the isolates of BBWV 2 than BBWV 1. However, sequence comparison of the 5' noncoding regions of the viruses differentiates BBWV-K from other BBWV 2 isolates. Another distinctive feature of the BBWV-K is that it generates defective RNAs in hot pepper exhibiting necrotic symptoms, which is the first report of defective RNAs in the Fabavirus genera of BBWVs.

Inhibition of natural killer cell-mediated cytotoxicity by Kaposi's sarcoma-associated herpesvirus K5 protein

Kaposi's sarcoma-associated herpesvirus (KSHV) K3 and K5 proteins dramatically downregulate MHC class I molecules. However, although MHC class I downregulation may protect KSHV-infected cells from cytotoxic T lymphocyte recognition, these cells become potential targets for natural killer (NK) cell-mediated lysis. We now show that K5 also downregulates ICAM-1 and B7-2, which are ligands for NK cell-mediated cytotoxicity receptors. As a consequence, K5 expression drastically inhibits NK cell-mediated cytotoxicity. Conversely, de novo expression of B7-2 and ICAM-1 resensitizes the K5-expressing cells to NK cell-mediated cytotoxicity. This is a novel viral immune evasion strategy where KSHV K5 achieves immune avoidance by downregulation of cellular ligands for NK cell-mediated cytotoxicity receptors.

The collagen repeat sequence is a determinant of the degree of herpesvirus saimiri STP transforming activity

Herpesvirus saimiri (HVS) is divided into three subgroups, A, B, and C, based on sequence divergence at the left end of genomic DNA in which the saimiri transforming protein (STP) resides. Subgroup A and C strains transform primary common marmoset lymphocytes to interleukin-2-independent growth, whereas subgroup B strains do not. To investigate the nononcogenic phenotype of the subgroup B viruses, STP genes from seven subgroup B virus isolates were cloned and sequenced. Consistent with the lack of oncogenic activity of HVS subgroup B viruses, STP-B was deficient for transforming activity in rodent fibroblast cells. Sequence comparison reveals that STP-B lacks the signal-transducing modules found in STP proteins of the other subgroups, collagen repeats and an authentic SH2 binding motif. Substitution mutations demonstrated that the lack of collagen repeats but not an SH2 binding motif contributed to the nontransforming phenotype of STP-B. Introduction of the collagen repeat sequence induced oligomerization of STP-B, resulting in activation of NF-kappaB activity and deregulation of cell growth control. These results demonstrate that the collagen repeat sequence is a determinant of the degree of HVS STP transforming activity.

Quantitative analysis of eotaxin and RANTES messenger RNA in nasal polyps: association of tissue and nasal eosinophils

OBJECTIVES/HYPOTHESIS

Nasal polyps develop in the ethmoidal and middle turbinate area, often in relation to inflammatory conditions. Their exact etiology and pathogenesis are still under debate. Histologically, the polyps are infiltrated by a number of inflammatory cells, with eosinophil predominating in most specimens. This finding suggests that the nasal polyp is an inflammatory growth that is controlled by the local environment. The chemokines eotaxin and RANTES (regulated on activation normal T cell expressed and secreted) have been postulated to be involved in the recruitment and activation of eosinophils to certain inflamed tissues. The purpose of this study was to investigate eotaxin and RANTES mRNA expression in nasal polyps and its effect on tissue and nasal eosinophils.

METHODS

Nasal polyps (917 allergic and 30 nonallergic cases) were obtained from endoscopic sinus surgery, and 15 normal inferior turbinates also were taken. Immunohistochemical staining for eosinophils and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) tests for eotaxin and RANTES mRNA expression were performed, and the concentration of nasal eosinophil cationic protein (ECP) was measured.

RESULTS

The amounts of eotaxin mRNA in the allergic nasal polyps were 11.4 times higher and the levels in the nonallergic polyps were 6.4 times higher than in the normal inferior turbinate. However, the RANTES mRNA expression did not show any differences among the three groups. Tissue eosinophilia and nasal ECP levels were significantly correlated with eotaxin mRNA level but not with RANTES mRNA expression.

CONCLUSION

Nasal polyp eosinophilic infiltration and activation correlate mainly with increased eotaxin gene expression rather than with RANTES expression.

Esterification of free fatty acids in adipocytes: a comparison between octanoate and oleate

Medium-chain triacylglycerols (MCT) are present in milk, coconut oil and other foods, and are used therapeutically in special diets for certain disorders of lipid and glucose utilization. Recently, it has become apparent that MCT are not only oxidized in the liver, but are also present in lymph and fat tissue, particularly after chronic treatment. To evaluate the influence of MCT on metabolism in fat cells, we compared incorporation of octanoate and oleate into cellular triacylglycerols of 3T3-L1 adipocytes as well as their effects on preadipocyte differentiation. We found that less octanoate than oleate was stored and that more octanoate than oleate was oxidized. Octanoate was esterified to a greater extent at the sn-1,3 position of glyceryl carbons than at the sn-2 position, whereas the opposite was true for oleate. Glycerol release from fat cells pre-treated with octanoate was also greater than from cells pre-treated with oleate, presumably related to the preferential release of octanoate from the sn-1,3 position. Octanoate was not incorporated into lipids in undifferentiated cells and did not induce differentiation in these cells, whereas oleate was readily stored and actually induced differentiation. Incorporation of octanoate into lipids increased as cells differentiated, but reached a maximum of about 10% of the total stored fatty acids. If these effects in vitro also occur in vivo, substitution of octanoate for oleate or other long-chain fatty acids could have the beneficial effect of diminishing fat-cell number and lipid content.

Chemical degradation of tobacco mosaic virus followed by infectivity assay, reverse transcription-polymerase chain reaction and gel electrophoresis

In order to determine the detection limit for chemically treated virions by gel electrophoresis, reverse transcription-polymerase chain reaction (RT-PCR) and infectivity assay, tobacco mosaic virus (TMV) exposed to various concentrations of chemicals was studied. When virions were exposed to 0.2 N HCl for 30 mins, partially degraded TMV particles were observed by gel electrophoresis. Under the same exposure, a major RT-PCR amplified DNA product corresponding to the target size of 806 bp, which decreased as a function of time, could be detected for up to 60 mins of exposure. When virions were treated with NaOH (0.02 N or higher normality) for 5 mins, partially degraded virions were detected by gel electrophoresis, exhibiting multiple band patterns. Exposure of the virions to 0.1 N NaOH for 5 mins revealed severely degraded viral RNA, but disappearance of the amplified RT-PCR products was apparent during 30-60 mins of exposure. Therefore, these data showed clearly the difference in the detection limit of gel electrophoresis and that of RT-PCR for the degraded viral RNA. In addition, the infectivity assay showed that the number of local lesions in Nicotiana rustica were significantly reduced by more than 95% when the virus was exposed to 0.2 N HCl for 15 mins or 0.1 N NaOH for 10 mins. From these results we conclude that loss of infectivity was not related to that of PCR product. Other chemical disinfectants such as phenol or formalin were also found to be effective to reduce the virus infectivity, but a corresponding degradation of viral RNA was detected by neither gel electrophoresis nor RT-PCR.