Functional group characterization of indoor, outdoor, and personal PM: results from RIOPA

Fourier transform infrared (FTIR) spectra of outdoor, indoor, and personal fine particulate matter (PM(2.5)) samples were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study. FTIR spectroscopy provides functional group information about the entire PM(2.5) sample without any chemical preparation. It is particularly important to characterizing the poorly understood organic fraction of PM(2.5). To our knowledge this is the first time that FTIR spectroscopy has been applied to a PM(2.5) exposure study. The results were used to chemically characterize indoor air and personal exposure. Sulfate was strongest in outdoor samples, which is consistent with the generally accepted understanding that sulfate is of outdoor origin. Absorbances attributed to soil dust were also seen in many outdoor and some indoor and personal samples. Inorganic nitrate absorbances were a common feature of many California and some New Jersey samples. Carbonyl absorbances showed substantial variation in strength, number of peaks, and wave number shift between samples, indicating variability in composition and sources. Absorbances attributed to aliphatic hydrocarbon and amide functional groups were enhanced in many personal and indoor samples, which suggested the influence of indoor sources in these homes. We speculate that meat cooking is one possible source of particulate amides.

PRACTICAL IMPLICATIONS

To our knowledge this is the first time that FTIR spectroscopy has been used to characterize the composition of indoor and personal PM(2.5). The presence of sulfate, nitrate, ammonium, soil dust and a number of organic functional groups are all detected in one analysis on filter samples without extraction or other sample preparation. Differences between indoor and outdoor spectra are used to identify spectral features due to indoor-generated PM(2.5). Particularly interesting are the much larger aliphatic absorbances, shifts in carbonyl absorbances, and occasional small amide absorbances found in indoor and personal spectra but rarely in outdoor spectra. These observations are important because organics make up a large portion of PM(2.5) mass and their composition and properties are poorly characterized. The properties and behavior of organic compounds in airborne particles are often predicted based on their functional group composition. This analysis begins the development of a better understanding of the functional group composition of indoor and personal PM(2.5) and how it differs from that of outdoor PM(2.5). Eventually this will lead to an improved understanding of the properties, behavior and effects of PM(2.5) of indoor and outdoor origin.

Localization of ubiquitin carboxyl-terminal hydrolase-L1 in cynomolgus monkey placentas

Ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1) is a restrictedly expressed enzyme in neural and reproductive tissues, and it is considered to have a significant role in reproduction. In the present study, we investigated the localization of UCH-L1 in placenta of cynomolgus monkeys (Macaca fascicularis). UCH-L1 protein was detected in cytotrophoblasts of chorionic plate and villi, and decidual cells of decidua basalis in cynomolgus monkey placenta, and the amount of UCH-L1 protein in whole placenta increased as pregnancy progressed. These results supported that UCH-L1 is necessary for placental and fetal development in primate placenta. This is the first report to demonstrate the presence of UCH-L1 in primate placenta, and the cynomolgus monkey may be a useful model for the study of the functions of the ubiquitin-proteasome system in human pregnancy.

Optimal management for surgically Stage 1 serous cancer of the uterus

OBJECTIVE

To describe the outcomes of patients who have undergone well-conducted surgery and found to have Stage 1 serous uterine cancer.

METHODS

This retrospective cohort study includes women who have been treated for Stage 1 serous cancer of the uterus from 1985 to 2001. Cases were included from the regional cancer centers in Hamilton, London, Sunnybrook Toronto and Cancer Care Manitoba.

RESULTS

Forty-three women met the inclusion criteria: Complete surgical staging (n = 27), surgery followed by pelvic radiation therapy (n = 4), surgery followed by whole abdominal radiation therapy (n = 6), surgery followed by adjuvant chemotherapy (n = 6). Patient age or depth of invasion did not influence survival. Progression free interval was 22 months (SD = 14.29). Recurrence rate was highest for adjuvant chemotherapy (66%). Survival was assessed by treatment modality and a statistically significant poorer survival was seen in the adjuvant chemotherapy group (OR 17.5; 95% CI 1.3-227.6). No comment can be made on a superior treatment regimen given the small numbers in each treatment strata.

CONCLUSION

This study supports the findings of others in the literature. In a group of patients where surgical staging shows limited disease (i.e., surgically Stage 1 disease), then surgery alone appears to be adequate treatment.

T cell receptor-stimulated generation of hydrogen peroxide inhibits MEK-ERK activation and lck serine phosphorylation

Previous studies indicated that antigen receptor (TcR) stimulation of mature T cells induced rapid generation of reactive oxygen species (ROS). The goal of the current study was to examine the role(s) of ROS in TcR signal transduction, with a focus upon the redox-sensitive MAPK family. TcR cross-linking of primary human T blasts and Jurkat human T cells rapidly activated the ERK, JNK, p38 and Akt kinases within minutes, and was temporally associated with TcR-stimulated production of hydrogen peroxide (H(2)O(2)). TcR-induced activation of ERK was selectively augmented and sustained in the presence of pharmacologic antioxidants that can quench or inhibit H(2)O(2) production (NAC, MnTBAP and Ebselen, but not DPI), while activation of JNK and Akt were largely unaffected. This was paralleled by concurrent changes in MEK1/2 phosphorylation, suggesting that ROS acted upstream of MEK-ERK activation. Molecular targeting of H(2)O(2) by overexpression of peroxiredoxin II, a thioredoxin dependent peroxidase, also increased and sustained ERK and MEK activation upon TcR cross-linking. Enhancement of ERK phosphorylation by antioxidants correlated with increased and sustained serine phosphorylation of the src-family kinase lck, a known ERK substrate. Thus, the data suggest that TcR-stimulated production of hydrogen peroxide negatively feeds back to dampen antigen-stimulated ERK activation and this redox-dependent regulation may serve to modulate key steps in TcR signaling.

Preoperative concurrent chemoradiotherapy for stage IIIA non-small cell lung cancer

Thirty-one patients with stage IIIA non-small cell lung cancer (NSCLC) were treated with preoperative concurrent chemoradiotherapy (CCRT) followed by surgery. The treatment protocol could not be completed in eight patients. The acute hematologic toxicities of grade III or IV occurred in 48.4%, (15/31) after the first chemotherapy cycle, and in 39.1% (9/23) after the second cycle. The most common non-hematologic toxicity was radiation esophagitis. Surgery was attempted in 23 patients and successful in 22 patients (resection rate = 71.0%. Pathologic complete response and down-staging were achieved in 13.6% (3/22) and 68.2% (15/22). The median survival period, 2-year overall survival, local control and disease-free survival rates of all 31 patients and of 22 patients who underwent surgery were 19 months, 37.2%, 49.1%, 35.5%, and 19 months, 43.2%, 51.8%, 25.6%, respectively. On the basis of our observations, preoperative CCRT followed by surgery for stage IIIA NSCLC has resulted in outcomes comparable with those in previous reports.

Clinical dietetics changes due to cost-reduction activities in healthcare systems

OBJECTIVE

This study was designed to assess changes in clinical dietetics due to cost-reduction activities in healthcare systems.

SUBJECTS

1,200 ADA members who indicated that they were employed by acute care hospitals in ADA Area 2 states.

DESIGN

A questionnaire about changes in clinical dietetics staffing and clinical dietitians' activities and responsibilities was developed based on qualitative research. Descriptive statistics, t tests, analysis of variance, chi2 tests, and correlations were calculated.

RESULTS

A total of 342 usable questionnaires (28.5%) were returned. More than one third (37.9%) of respondents reported reductions in the number of clinical dietitians, and 32.2% reported increases in the number of part-time clinical dietitians. Most respondents indicated that they were more involved with high-risk patient interventions, had limited time for inpatient instruction, and experienced an increased patient caseload. Although 45.4% of respondents reported diminished job satisfaction due to recent changes in healthcare systems, some changes, such as increased high-risk patient intervention and referrals, were positively correlated with perceived job satisfaction.

DISCUSSION

Thorough review of current clinical dietetics activities/responsibilities and planning before cost-reduction, restructuring activities may maximize staff utilization without decreased job satisfaction of clinical dietetics staff.

Tsetse immune responses and trypanosome transmission: implications for the development of tsetse-based strategies to reduce trypanosomiasis

Tsetse flies are the medically and agriculturally important vectors of African trypanosomes. Information on the molecular and biochemical nature of the tsetse/trypanosome interaction is lacking. Here we describe three antimicrobial peptide genes, attacin, defensin, and diptericin, from tsetse fat body tissue obtained by subtractive cloning after immune stimulation with Escherichia coli and trypanosomes. Differential regulation of these genes shows the tsetse immune system can discriminate not only between molecular signals specific for bacteria and trypanosome infections but also between different life stages of trypanosomes. The presence of trypanosomes either in the hemolymph or in the gut early in the infection process does not induce transcription of attacin and defensin significantly. After parasite establishment in the gut, however, both antimicrobial genes are expressed at high levels in the fat body, apparently not affecting the viability of parasites in the midgut. Unlike other insect immune systems, the antimicrobial peptide gene diptericin is constitutively expressed in both fat body and gut tissue of normal and immune stimulated flies, possibly reflecting tsetse immune responses to the multiple Gram-negative symbionts it naturally harbors. When flies were immune stimulated with bacteria before receiving a trypanosome containing bloodmeal, their ability to establish infections was severely blocked, indicating that up-regulation of some immune responsive genes early in infection can act to block parasite transmission. The results are discussed in relation to transgenic approaches proposed for modulating vector competence in tsetse.

Atypical ductal hyperplasia in stereotactic breast biopsies: enhanced accuracy of diagnosis with the mammotome

There is little literature assessing the incidence of subsequent carcinoma in patients diagnosed with atypical ductal hyperplasia (ADH) by mammotome. We reviewed 216 stereotactic mammotome biopsies (SMBs) and compared the results to the 121 automated tru-cut biopsies (ATC) performed at our breast care center from June 1994 to July 1998. The median age in the mammotome series was 57 years, compared to 56 years in the ATC group. An increase in biopsies for microcalcifications (49% versus 41%) was noted in the SMB series. This was accompanied by an increase in the number of cases with a diagnosis of pure ductal carcinoma in situ (DCIS) (10% versus 4%). Compared to the tru-cut, in which 38% (3 of 8) of the cases diagnosed as atypical hyperplasia (AH) showed DCIS and/or invasive carcinoma on open biopsy, none of the cases diagnosed as AH on mammotome revealed carcinoma on open biopsy. ADH is more accurately diagnosed with SMB than by the ATC method and may not be an indication for subsequent open biopsy.

Dichloroacetate exerts therapeutic effects in transgenic mouse models of Huntington's disease

Dichloroacetate (DCA) stimulates pyruvate dehydrogenase complex (PDHC) activity and lowers cerebral lactate concentrations. In the R6/2 and N171-82Q transgenic mouse models of Huntington's disease (HD), DCA significantly increased survival, improved motor function, delayed loss of body weight, attenuated the development of striatal neuron atrophy, and prevented diabetes. The percentage of PDHC in the active form was significantly reduced in R6/2 mice at 12 weeks of age, and DCA ameliorated the deficit. These results provide further evidence for a role of energy dysfunction in HD pathogenesis and suggest that DCA may exert therapeutic benefits in HD.

Characterization of genes expressed in the salivary glands of the tsetse fly, Glossina morsitans morsitans

Salivary gland products of haematophogous insects including tsetse flies (Diptera: Glossinidia) are involved in antihaemostasis to allow for efficient blood feeding. In addition, salivary products of tsetse are thought to indirectly support the metacyclogenesis and eventual transmission of the African trypanosome protozoan parasites to their mammalian hosts. We have previously characterized the major anticoagulant, Tsetse Thrombin Inhibitor (TTI), from salivary extracts, and described molecular aspects of its cDNA from a Glossina morsitans morsitans salivary gland cDNA library. In addition, a family of two related genes with growth factor and adenosine-deaminase motifs (TSGF-1 and TSGF-2) have also been described. Here, we report on the molecular aspects of three different cDNAs and their putative products expressed in salivary glands: cDNAs TAg5, Tsal1 and Tsal2. The full-length transcript encoded by Tsetse Antigen 5 (TAg5) cDNA is 926 bp excluding the poly(A) stretch, and has an open reading frame of 259 amino acids that can encode for a protein of 28 925 Da. The putative product of TAg5 shows extensive similarities to cDNAs characterized from Drosophila (Agr and Agr2) and sandfly Lutzomyia (LuLoAG5). The cDNAs Tsal1 and Tsal2 are predicted to encode for mature proteins of 45 612 Da (399 amino acids) and 43 930 Da (389 amino acids), respectively, and their putative products exhibit over 42% identity to one another. The N terminus of each putative protein contains a hydrophobic region with signal peptide characteristics indicating that they may be secretory in nature. Transcripts specific for TAg5 and Tsal2 genes can be detected in all developmental stages of tsetse while Tsal1 expression is limited to adult and larval stages. A reverse transcription polymerase chain reaction based amplification approach indicates that TAg5 transcipts can be detected from proventriculus and midgut tissues of the fly in addition to salivary glands, while Tsal1 and Tsal2 expression is restricted to salivary gland and proventriculus. The salivary glands of adult males are found to express higher levels of TAg5 and Tsal2 in comparison to females while no significant sex-based difference is observed for Tsal1 expression. The expression of these cDNAs in different tsetse species (G. m. morsitans, Glossina austeni and Glossina fuscipes) shows wide variations.

Susceptibility locus for Alzheimer's disease on chromosome 10

The apolipoprotein E (APOE) gene is the only genetic risk factor that has so far been linked to risk for late-onset Alzheimer's disease (LOAD). However, 50 percent of Alzheimer's disease cases do not carry an APOE4 allele, suggesting that other risk factors must exist. We performed a two-stage genome-wide screen in sibling pairs with LOAD to detect other susceptibility loci. Here we report evidence for an Alzheimer's disease locus on chromosome 10. Our stage one multipoint lod score (logarithm of the odds ratio for linkage/no linkage) of 2.48 (266 sibling pairs) increased to 3.83 in stage 2 (429 sibling pairs) close to D10S1225 (79 centimorgans). This locus modifies risk for Alzheimer's disease independent of APOE genotype.

Histone acetylation and hSWI/SNF remodeling act in concert to stimulate V(D)J cleavage of nucleosomal DNA

The ordered assembly of immunoglobulin and TCR genes by V(D)J recombination depends on the regulated accessibility of individual loci. We show here that the histone tails and intrinsic nucleosome structure pose significant impediments to V(D)J cleavage. However, alterations to nucleosome structure via histone acetylation or by stable hSWI/SNF-dependent remodeling greatly increase the accessibility of nucleosomal DNA to V(D)J cleavage. Moreover, acetylation and hSWI/SNF remodeling can act in concert on an individual nucleosome to achieve levels of V(D)J cleavage approaching those observed on naked DNA. These results are consistent with a model in which regulated recruitment of chromatin modifying activities is involved in mediating the lineage and stage-specific control of V(D)J recombination.

Hydrogen peroxide: a key messenger that modulates protein phosphorylation through cysteine oxidation

Ligand-receptor interactions can generate the production of hydrogen peroxide (H(2)O(2)) in cells, the implications of which are becoming appreciated. Fluctuations in H(2)O(2) levels can affect the intracellular activity of key signaling components including protein kinases and protein phosphatases. Rhee et al. discuss recent findings on the role of H(2)O(2) in signal transduction. Specifically, H(2)O(2) appears to oxidize active site cysteines in phosphatases, thereby inactivating them. H(2)O(2) also can activate protein kinases; however, although the mechanism of activation for some kinases appears to be similar to that of phosphatase inactivation (cysteine oxidation), it is unclear how H(2)O(2) promotes increased activation of other kinases. Thus, the higher levels of intracellular phosphoproteins observed in cells most likely occur because of the concomitant inhibition of protein phosphatases and activation of protein kinases.

Accuracy of the Bernoulli equation for estimation of pressure gradient across stenotic Blalock-Taussig shunts: an in vitro and numerical study

Accurate assessment of the pressure gradient (PG) across a modified Blalock-Taussig (mBT) shunt is important in planning for staging to a cavopulmonary anastomosis for many patients with cyanotic congenital heart disease. The mBT shunt Doppler velocity has been used in the simplified echo Bernoulli equation to predict this PG with variable results. The purpose of this investigation is to provide analysis of the flow dynamics through stenotic mBT shunts and to assess the accuracy of Doppler techniques in determining PGs and the presence and location of stenosis. Three-dimensional models of mBT shunts were created, with and without stenosis. In vitro and computational fluid dynamic flow experiments were carried out. In vitro experiments demonstrated that the Doppler-measured PG underestimated catheter-measured PG in the mBT shunt with diffuse stenosis. In nonstenotic mBT and those that had outlet and inlet stenosis, the Doppler-measured PG showed underestimation of catheter PG at low PG and generally improved estimation at higher PG. In the mBT shunt model with inlet stenosis, there was slight overestimation at higher PG. Numerical simulations provide an "observation window" into events occurring in and around mBT shunts showing that the hemodynamics vary significantly. Changing hemodynamic processes are at work through stenotic mBT shunts causing variations in overestimation and underestimation of catheter-measured PG using the simplified echo Bernoulli equation. Our results have relevance to the assessment of patients with mBT shunts, helping to explain some of the discrepancies that investigators have found in the past.

Control of the characteristics of a long-period grating by cladding etching

We have analyzed the effects of the fiber cladding radius on the characteristics of long-period fiber gratings. By etching the cladding of a common single-mode fiber, we verified the characteristics experimentally. When by etching we reduce the cladding radius of a common single-mode fiber on which a long-period refractive-index modulation has been imposed, the coupling strength of the core and the cladding modes increases. In addition, the difference in the propagation constants (for a fixed wavelength) between the core mode and the cladding modes increases; hence the resonant transmission dip wavelengths shift to longer wavelengths. The proposed method can be useful in making and detuning long-period fiber grating filters.

A method for determining the reference effective flow areas for mechanical heart valve prostheses: in vitro validation studies

BACKGROUND

The anatomic opening area (AOA) is usually reported as the primary index of mechanical heart valve function. Because flow contracts immediately distal to an orifice as a result of the vena contracta effect, AOA may not be a good measure of true effective flow area.

METHODS AND RESULTS

Laser flow imaging was used to visualize the contraction in the jet flow stream as it passed through bileaflet mechanical valves under steady and pulsatile conditions. Such visualization allowed clear measurement of the individual vena contracta areas (VCAs) of the 3 valve orifices. VCAs for side orifices were larger (94+/-2% of AOA) than those through the central orifice (34+/-8%). Formation of large radial vortices around the leaflet tips constricted the central orifice flow stream and appeared to be the main reason for smaller central VCA. Total VCA remained constant until approximately 0.5 orifice diameters ( approximately 1.0 cm) downstream, beyond which cross-sectional area increased as a result of entrainment of receiving chamber flow. Total VCA was larger for steady flow (89.6+/-2.7% of AOA) than for pulsatile flow (76.3+/-5.0% of AOA).

CONCLUSIONS

This study further clarifies flow dynamics through bileaflet mechanical valves and provides previously unavailable reference information on VCAs for these valves. Such information should aid clinicians in explaining Doppler-derived and catheter-measured pressure discrepancies, validating clinical techniques for quantifying effective flow areas, and optimizing valve size for implantation. The method should also be useful for comparative studies of different valve designs.

Mammalian thioredoxin reductase: oxidation of the C-terminal cysteine/selenocysteine active site forms a thioselenide, and replacement of selenium with sulfur markedly reduces catalytic activity

Mammalian cytosolic thioredoxin reductase (TrxR) has a redox center, consisting of Cys(59)/Cys(64) adjacent to the flavin ring of FAD and another center consisting of Cys(497)/selenocysteine (SeCys)(498) near the C terminus. We now show that the C-terminal Cys(497)-SH/SeCys(498)-Se(-) of NADPH-reduced enzyme, after anaerobic dialysis, was converted to a thioselenide on incubation with excess oxidized Trx (TrxS(2)) or H(2)O(2). The Cys(59)-SH/Cys(64)-SH pair also was oxidized to a disulfide. At lower concentrations of TrxS(2), the Cys(59)-SH/Cys(64)-SH center was still converted to a disulfide, presumably by reduction of the thioselenide to Cys(497)-SH/SeCys(498)-Se(-). Specific alkylation of SeCys(498) completely blocked the TrxS(2)-induced oxidation of Cys(59)-SH/Cys(64)-SH, and the alkylated enzyme had negligible NADPH-disulfide oxidoreductase activity. The effect of replacing SeCys(498) with Cys was determined by using a mutant form of human placental TrxR1 expressed in Escherichia coli. The NADPH-disulfide oxidoreductase activity of the purified Cys(497)/Cys(498) mutant enzyme was 6% or 11% of that of wild-type rat liver TrxR1 with 5, 5'-dithiobis(2-nitrobenzoic acid) or TrxS(2), respectively, as substrate. Disulfide formation induced by excess TrxS(2) in the mutant form was 12% of that of the wild type. Thus, SeCys has a critical redox function during the catalytic cycle, which is performed poorly by Cys.

Comorbid personality impairment in body dysmorphic disorder

Personality impairment was evaluated in 17 body dysmorphic disorder (BDD) patients undergoing a treatment study of clomipramine versus desipramine. Semistructured interviews were administered using both categorical (Structured Clinical Interview for DSM [SCID II]) and dimensional (Dimensional Assessment of Personality Impairment [DAPI]) methods. Personality measures were also correlated with a range of clinical variables (severity of BDD and depressive symptoms, age, duration of illness, and response to treatment). A secondary aim of the study was to provide preliminary validation for the DAPI. Consistent with previous studies, BDD patients showed considerable personality pathology. By SCID II, patients met criteria for a mean of 2.53 personality disorder diagnoses; 87% of patients met criteria for at least 1 diagnosis and 53% for more than 1. Cluster C diagnoses were the most common. Mean scores for the DAPI were 2.63 (3 = mild impairment) to 6.41 (7 = severe impairment), averaging 5.26 (5 = moderate). With regard to the DAPI, the results provided preliminary evidence of good reliability and validity. Moreover, both personality measures were highly intercorrelated. Although SCID II diagnoses correlated with baseline depression (Hamilton Rating Scale for Depression [HRSD]) scores, there were few other significant correlations between personality and other clinical variables. Of note, however, treatment responders demonstrated less personality impairment than nonresponders. The finding that personality measures were highly intercorrelated but, on the whole, not well correlated with other clinical measures supports the distinct and dissociable nature of personality phenomena in BDD. Despite the small sample size, these results suggest that personality impairment appears to be significant factor in BDD and may even play a role in treatment response.

Clomipramine vs desipramine crossover trial in body dysmorphic disorder: selective efficacy of a serotonin reuptake inhibitor in imagined ugliness

BACKGROUND

Body dysmorphic disorder (preoccupation with an imagined or slight defect in appearance) is a common and disabling disorder associated with high rates of delusional symptoms and suicide attempts. Although preliminary studies suggest that serotonin reuptake inhibitors may be effective for body dysmorphic disorder, to date no controlled treatment studies have been published.

METHODS

Forty patients were enrolled and 29 were randomized into a 16-week, double-blind, crossover-design study of clomipramine, a potent serotonin reuptake inhibitor, and active control desipramine, a selective norepinephrine reuptake inhibitor. Outcome measures included specific ratings of body dysmorphic disorder severity, delusionality, and functional impairment.

RESULTS

Clomipramine was superior to desipramine in the acute treatment of body dysmorphic disorder symptoms as measured by assessment of patients' obsessive preoccupation with perceived body defects, repetitive behaviors in response to this preoccupation, and global ratings of symptom severity. Treatment efficacy was independent of the presence or severity of comorbid diagnoses of obsessive-compulsive disorder, depression, or social phobia. Likewise, clomipramine was equally effective regardless of whether the patients had insight or held their dysmorphic misperception with delusional intensity. Clomipramine was also superior to desipramine in improving functional disability.

CONCLUSIONS

Clomipramine is more effective than desipramine in the treatment of body dysmorphic disorder and is effective even among those patients who are delusional.

Construction of a detailed physical and transcript map of the FTDP-17 candidate region on chromosome 17q21

Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is an autosomal dominant condition clinically characterized by behavioral, cognitive, and motor disturbances. Until now, at least 13 different FTDP-17 families that show linkage to chromosome 17q21 have been described. To characterize the FTDP-17 candidate region, flanked by the markers D17S1789 and D17S1804, we constructed a physical map in P1 and PAC clones. A detailed transcript map was generated by positioning known genes and EST clusters to the physical map. In total, we investigated 150 STSs mapped to this region. In addition, novel transcripts were isolated by exon-trapping. We were able to localize 19 known genes and a number of ESTs to this chromosomal region. Furthermore, seven novel genes were identified for which we isolated the full-length sequence.

Real-time 3-dimensional volumetric ultrasound imaging of the vena contracta for stenotic valves with the use of echocardiographic contrast imaging: in vitro pulsatile flow studies

The purpose of our study was to investigate the utility of real-time 3-dimensional volumetric ultrasound coupled with echo contrast imaging to visualize and quantify effective flow areas for stenotic valves in vitro. Real-time 3-dimensional ultrasound imaging has recently emerged as a promising method for increasing the quantitative accuracy of echocardiography. Since the technique currently does not process Doppler information, its use for quantifying flow has not been studied. However, the use of contrast agents to visualize cardiac flows with the use of echocardiography should allow determination of mass-dependent flow parameters such as effective flow area (vena contracta area) for stenotic lesions. We used real-time 3-dimensional imaging in an in vitro stenotic valve model (areas 0.785 to 1.767 cm2) under pulsatile flow conditions (60 bpm; 40 to 80 mL/beat). An echo contrast agent was used to visualize the distal jet. Real-time 3-dimensional imaging provides simultaneous views of long-axis and short-axis (C-scan) image planes of the jet. The vena contracta was identified and measured by placing the C-scan line immediately distal to the orifice and measuring the cross-sectional flow area. System gain and postprocessing curve shape affected 3-dimensional areas; minimal gain and a custom curve produced best agreement to actual vena contracta areas measured with a previously validated laser method (y = 0.939x + 0.089; r = 0.98; standard error of estimate = 0.158 cm2). We conclude that real-time 3-dimensional ultrasound imaging coupled with a contrast agent can be used as an accurate yet simple clinical means of measuring effective flow areas for stenotic valves.

IL-2-deficient mice raised under germfree conditions develop delayed mild focal intestinal inflammation

Interleukin-2 (IL-2) amplifies immune stimuli and influences B cell differentiation. IL-2-deficient mice spontaneously develop intestinal inflammation if raised under specific pathogen-free (SPF) conditions. We quantitatively determined the aggressiveness and kinetics of gastrointestinal and hepatic inflammation in the presence or absence of viable bacteria in IL-2-deficient mice. Breeding colonies were maintained under SPF and germfree (GF) conditions. Intestinal tissues, serum, and mesenteric lymph nodes were obtained from mice at different ages for blind histological scoring, immunoglobulin measurements, mucosal T cell infiltration, and cytokine secretion. GF IL-2 -/- mice developed mild, focal, and nonlethal intestinal inflammation with delayed onset, whereas the more aggressive inflammation in SPF IL-2 -/- mice led to their death between 28 and 32 wk. Periportal hepatic inflammation was equal in the presence or absence of bacterial colonization. Intestinal immunoglobulin secretion decreased significantly by 13 wk of age in IL-2 -/- mice in both GF and SPF environments. In contrast to other genetically engineered rodents, IL-2 -/- mice develop mild focal gastrointestinal and active portal tract inflammation in the absence of viable bacteria.

Elevated serum vascular endothelial growth factor in children and young adults with Crohn's disease

Vascular endothelial growth factor (VEGF) is a cytokine released by fibroblasts, epithelial cells, and leukocytes that potentiates vascular permeability and growth of new capillaries. Because of these multiple effects, VEGF has been postulated to play a role in the pathogenesis of autoimmune disease, as well as in wound healing. We hypothesized that VEGF was potentially important in mediating the vascular permeability and angiogenesis seen in Crohn's disease, and therefore that VEGF would be increased in the serum of children with Crohn's disease. Serum was obtained from 73 children and young adults with Crohn's disease, 47 with ulcerative colitis, and 29 controls. VEGF levels were measured by enzyme-linked immunosorbent assay. Mean VEGF levels were significantly higher in patients with Crohn's disease (436.4 +/- 37.2 pg/ml) than in ulcerative colitis (306 +/- 41.1 pg/ml) or control (167.8 +/- 29.6 pg/ml) patients. Serum VEGF also correlated significantly with disease activity, being elevated in patients with moderate/severe Crohn's disease and ulcerative colitis. We conclude that serum VEGF is released by inflamed tissues in children with Crohn's disease. This multifunctional cytokine could promote inflammation by increasing vascular permeability or promote wound healing by mediating capillary growth.

B lymphocyte antigen D8/17 and repetitive behaviors in autism

OBJECTIVE

Monoclonal antibody D8/17 identifies a B lymphocyte antigen with expanded expression in rheumatic fever, Sydenham's chorea, and subgroups of obsessive-compulsive disorder and Tourette's syndrome with repetitive behaviors. The authors examined the rate of D8/17 expression in children with autism and its correlation with severity of repetitive behaviors.

METHOD

Blood samples from 18 patients with autism and 14 comparable medically ill children were evaluated for percentage of D8/17-positive B cells by immunofluorescence and for streptococcal antibodies. Severity of repetitive behaviors was also determined.

RESULTS

The frequency of individuals with > or =11% D8/17-positive cells was significantly higher in the autistic patients (78%) than the comparison subjects (21%), severity of repetitive behaviors significantly correlated with D8/17 expression, and D8/17-positive patients had significantly higher compulsion scores than D8/17-negative patients.

CONCLUSIONS

D8/17 expression is high in patients with autism and may serve as a marker for compulsion severity within autism.

Accessibility of nucleosomal DNA to V(D)J cleavage is modulated by RSS positioning and HMG1

B and T cell receptor gene assembly by V(D)J recombination is tightly regulated during lymphoid development. The mechanisms involved in this regulation are poorly understood. Here we show that nucleosomal DNA is refractory to V(D)J cleavage. However, the presence of HMG1, a chromatin-associated nonhistone DNA-binding protein, stimulates V(D)J cleavage of nucleosomal templates. This HMG1 stimulation is differentially affected by the rotational or translational positioning of the recombination signal sequence on the histone octamer, with cleavage of the 12 bp spacer RSS showing sensitivity to rotational position and the 23 bp spacer RSS affected by its displacement from the dyad. These results suggest that V(D)J recombination can be modulated by controlling substrate accessibility and cleavage at the level of an individual nucleosome.

Serotonergic function in social phobia: comparison to normal control and obsessive-compulsive disorder subjects

Eighteen patients with social phobia, 21 normal control subjects, and 42 obsessive-compulsive disorder (OCD) control subjects were challenged with single doses of the partial serotonin agonist oral m-chlorophenylpiperazine (m-CPP) and placebo. Social phobics did not significantly differ from normal or OCD control subjects in prolactin response to m-CPP. There was a significant difference across groups in cortisol response to m-CPP, such that female social phobics had more robust cortisol responses to the m-CPP challenge. Pairwise comparisons only reached trend significance, perhaps due to the relatively small sample sizes. This study offers preliminary evidence for serotonin dysfunction in social phobia, particularly in female social phobics, but needs to be replicated in a larger sample size.

Cloning, characterization, and expression of the CIP2 gene induced under cadmium stress in Candida sp

We isolated, sequenced, and expressed a cadmium-induced gene, CIP2, that specifically hybridizes to a mRNA of approximately 950 nucleotides. The CIP2 mRNA was barely present in normal Candida cells, but accumulated at higher levels in cadmium-treated cells. Other heavy metals such as copper, mercury, lead, and manganese had no effect on the expression of the CIP2 gene. CIP2 contains an open reading frame encoding a protein of 203 amino acids. This gene was also activated by an oxidant, diamide. Our results suggest that CIP2 may play a crucial role in the specific cellular response to oxidative stress evolved by the cadmium treatment.

Utility of three-dimensional ultrasound Doppler flow reconstruction of the proximal jet to quantify effective orifice area: in vitro steady and pulsatile flow studies

We examined the utility of three-dimensional (3D) reconstruction of two-dimensional color Doppler images of the proximal jet to quantify the effective area of an orifice in an in vitro model. Steady and pulsatile flows were directed through various orifices; orifice vena contracta areas were quantified with laser flow visualization, thus providing gold standard effective orifice areas. Three-dimensional areas followed vena contracta areas well, although variations in color Doppler gain and 3D gray levels for thresholding produced significant changes in reconstructed images. These variations were minimized by using minimum color gain and 50% gray level threshold. At these settings, 3D areas still overestimated vena contracta areas by approximately 25% because of the poor lateral resolution of the color Doppler system, which caused bleeding of the flow signal past the edges of the proximal jet. Nevertheless, 3D flow images provided a superior format for qualitative and quantitative appreciation of proximal jet shape and dimensions.

Nonsecretory IgA1 autoantibodies targeting desmosomal component desmoglein 3 in intraepidermal neutrophilic IgA dermatosis

Intraepidermal neutrophilic IgA dermatosis, a rare skin disease entity manifested with blisters and pustules clinically and lower epidermal blister, acantholysis, and neutrophilic infiltration pathologically, was first reported in 1985. Although the disease is characterized by IgA autoantibodies targeting the epithelial cell surface component, the target antigen has not been determined. We investigated a patient with this disease by histopathology, direct and indirect immunofluorescence, immunoblotting, and immunoadsorption studies. The pustular lesion was characterized by blister at the lower epidermis, acantholysis, and neutrophilic infiltration. Nonsecretory IgA1 subclass autoantibodies targeting the lower epithelial cell surfaces were detected in the patient's skin and serum. The patient's IgA autoantibodies labeled a recombinant desmosomal protein desmoglein 3 on immunoblotting and the immunolabeling of epithelial cell surfaces was eliminated by preadsorption with desmoglein 3. Thus, desmoglein 3 is identified as a target antigen in intraepidermal neutrophilic IgA dermatosis. The ability of IgA1 autoantibodies to bind neutrophils may be responsible for the prominent neutrophilic infiltration observed histopathologically and for the pustular lesions observed clinically.

Fos-immunoreactive responses in inferior colliculi of rats with experimental audiogenic seizure susceptibility

Audiogenic seizure (AGS) susceptibility is a reflex epilepsy of rodents in which acoustic stimulation evokes wild running attacks and subsequent convulsions. Susceptibility can be induced in non-susceptible strains by treatments causing transient or permanent hearing losses as long as these occur during the neonatal period. The defect which is the basis of susceptibility has been proposed to be a failure of developmental organization of inferior colliculus (IC) into frequency selective zones. That is, high frequency stimuli evoke responses in broader arrays of neurons in ICs of susceptible rats than in those of neonatally untreated (non-susceptible) controls. Nonetheless, this observation has been made only in rats in which susceptibility was induced by exposure to intense noise on postnatal day (PND) 14. By contrast, the present study examines whether unusually broad topographic responses are also characteristic in ICs of rats made susceptible by the neonatal administration of low doses of the ototoxic antibiotic, kanamycin (KM). Patterns of Fos-like immunoreactivity (Foslir) induced by seizures or pure tone stimuli were compared in ICs of adult Wistar rats which neonatally had been (a) sham-treated; (b) noise-exposed on PND 14; or (c) injected on PNDs 9-12 with 100 mg/kg KM. It was found that sound-triggered seizures in the two experimental groups resulted in induction of Foslir primarily within cortical areas of IC. By contrast, pure tones evoked unusually broad responses in the central nucleus of ICs of both susceptible groups but not in those of controls. Additionally, in the KM-treated rats, the range of frequencies evoking abnormal responses extended one octave lower than was characteristic of noise-exposed rats. The earlier schedule of treatments in the KM model may account for this inasmuch as low frequency response domains undergo development at younger ages. The similarity of results in the two models suggests failure of development of frequency selective fields in IC is indeed the common basis of experimentally induced susceptibility to sound-triggered seizures.

A 3' cis-acting element is involved in tumor necrosis factor-alpha gene expression in astrocytes

Tumor necrosis factor-alpha (TNF-alpha) contributes to demyelinating diseases in the central nervous system. Astrocytes, the major glial cells in the CNS, do not constitutively express TNF-alpha, but the TNF-alpha gene is transcriptionally activated in response to a variety of stimuli, including TNF-alpha itself. Because of the importance of TNF-alpha in the CNS, we examined the mechanisms underlying transcriptional regulation of the TNF-alpha gene in astrocytes. In transient transfection assays, a plasmid construct containing 1.3 kilobase pairs (kb) of 5' flanking sequence of the rat TNF-alpha gene showed high basal activity that could not be further enhanced by TNF-alpha stimulation. A "marked" 10-kb TNF-alpha gene construct, which contains the whole TNF-beta gene with 1.2 kb of 5' flanking sequence, 1.1 kb of intergenic sequence, and the whole TNF-alpha gene with 3 kb of 3' flanking sequence, was able to respond to TNF-alpha stimulation. Analysis of a series of 5' and 3' deletion constructs of the marked TNF-alpha genes demonstrated that upstream sequence elements such as NF-kappaB are not required for TNF-alpha induction and that TNF-alpha responsive elements are located in the 3' flanking region of the TNF-alpha gene. We also found that a TNF-alpha-inducible DNase I-hypersensitive (DH) site is present in this 3' region whose deletion abolishes TNF-alpha inducibility of the marked TNF-alpha gene. Electrophoresis mobility shift assays showed that TNF-alpha-inducible nuclear proteins, consisting of p50 and p65 NF-kappaB proteins, specifically bind to two consecutive NF-kappaB binding sites within the 3' DH site. These results indicate that TNF-alpha-induced TNF-alpha gene expression in astrocytes involves p50 and p65 NF-kappaB proteins binding to downstream NF-kappaB sites and concomitant modulation of the chromatin structure.

Abdominal fetal EKG noise removal

Accurate detection of the fetal heart signal (FEKG) early during pregnancy enhances the physician's ability to diagnose possible congenital cardiac defects. However, FEKG acquisition is hampered by excessive noise contamination from the maternal ekg (MEKG) and uterine muscular contraction.

METHODS

A new computerized system was developed to record FEKG and MEKG signals from multiple leads. Removal of noise sources was performed using a blanking procedure, which selectively removes MEKG signal, and signal averaging procedure.

RESULTS

20 subjects showed 11 positive and 9 negative findings of FEKG. Blanking out the maternal QRS complex also removed part of the fetal signal making it unusable. The signal averaging procedure applied to 10-20 maternal QRS's still produced false positive fetal QRS signals. Two of the negative results were from biological noise with QRS type waveform and frequency of 8.75Hz. The depth of the fetus (5-10 cm) and period of gestation (17-40 weeks) had no bearing on finding FEKG.

CONCLUSION

Blanking is not an optimal method for maternal noise removal because of removal of some fetal QRS complex. Averaging is a viable method except in cases where the peak fetal signals are less than 75 micro Volts. Preliminary studies using an adaptive algorithm with the maternal chest EKG as reference promises to be a better solution for maternal EKG removal.

Digital particle image velocimetry (DPIV) measurements of the velocity profiles through bileaflet mechanical valves: in vitro steady

Although velocity profiles downstream of mechanical valves have been measured in-vitro using Laser Doppler Anemometry (LDA), these studies have not measured velocities in the immediate proximity of the leaflets since the LDA technique prevents velocities from being measured in the immediate vicinity of any structure. Laser based Digital Particle Image Velocimetry (DPIV) is a new technique that allows for accurate measurement of an entire two-dimensional velocity field with no beam angulation. DPIV was used to measure two-component velocity vectors immediately proximal and distal to a 25 mm bileaflet mechanical valve (St. Jude) mounted in a transparent steady flow in-vitro model. Measurements of flow similar in Reynolds number (Re) to mitral inflow (Re = 2000-4000) showed clear hemi-elliptical isovelocity convergence zones proximal to each of the three orifices. DPIV measurements of flow distal to the orifice revealed clear vortex rollups generated from the internal ring of the valve with separate velocity profiles immediately distal to the leaflets. These studies prove the feasibility of the DPIV technique to provide accurate velocity measurements of flow profiles through mechanical valves.

When combining intrinsic motivations undermines interest: a test of activity engagement theory

Three studies with elementary school children demonstrated that combining reading with coloring pictures can undermine children's later interest in reading, while also reducing their interest in coloring. Undermining is maximized when an activity is identified as secondary during the initial engagement, but other conditions must also be met as specified by activity engagement theory (Higgins & Trope, 1990): (a) the multiple input activities must be separately identified and considered simultaneously as alternatives, (b) the activity identified as primary during initial engagement must not be perceived as very attractive, and (c) the responses connected to an identified activity during the initial engagement must be activated subsequently. Conditions for enhancing interest in an activity are also considered.

When combining intrinsic motivations undermines interest: a test of activity engagement theory

Three studies with elementary school children demonstrated that combining reading with coloring pictures can undermine children's later interest in reading, while also reducing their interest in coloring. Undermining is maximized when an activity is identified as secondary during the initial engagement, but other conditions must also be met as specified by activity engagement theory (Higgins & Trope, 1990): (a) the multiple input activities must be separately identified and considered simultaneously as alternatives, (b) the activity identified as primary during initial engagement must not be perceived as very attractive, and (c) the responses connected to an identified activity during the initial engagement must be activated subsequently. Conditions for enhancing interest in an activity are also considered.

Differential modulation of astrocyte cytokine gene expression by TGF-beta

In this study, we demonstrate that TGF-beta inhibits TNF-alpha expression, and induces/enhances IL-6 expression by primary rat astrocytes. Treatment of astrocytes with TGF-beta alone had no effect on TNF-alpha mRNA or protein expression; however, TGF-beta suppressed induction of TNF-alpha expression by three different stimuli (IFN-gamma/LPS, IFN-gamma/IL-1 beta, TNF-alpha) at both the protein and mRNA level. The extent of TGF-beta-mediated inhibition was greatest when astrocytes were pretreated with TGF-beta for 6 to 24 h, then exposed to the inducing stimuli. Inhibition of TNF-alpha mRNA steady-state levels by TGF-beta was a result of inhibition of TNF-alpha gene transcription, rather than degradation of the TNF-alpha message. In contrast, TGF-beta alone induced expression of IL-6 by astrocytes and synergized with two other cytokines, IL-1 beta and TNF-alpha, for enhanced IL-6 expression. TGF-beta-induced/enhanced IL-6 expression was mediated by transcriptional activation of the IL-6 gene. These results indicate that TGF-beta is an important regulator of cytokine production by astrocytes under inflammatory conditions in the brain.

Differential modulation of astrocyte cytokine gene expression by TGF-beta

In this study, we demonstrate that TGF-beta inhibits TNF-alpha expression, and induces/enhances IL-6 expression by primary rat astrocytes. Treatment of astrocytes with TGF-beta alone had no effect on TNF-alpha mRNA or protein expression; however, TGF-beta suppressed induction of TNF-alpha expression by three different stimuli (IFN-gamma/LPS, IFN-gamma/IL-1 beta, TNF-alpha) at both the protein and mRNA level. The extent of TGF-beta-mediated inhibition was greatest when astrocytes were pretreated with TGF-beta for 6 to 24 h, then exposed to the inducing stimuli. Inhibition of TNF-alpha mRNA steady-state levels by TGF-beta was a result of inhibition of TNF-alpha gene transcription, rather than degradation of the TNF-alpha message. In contrast, TGF-beta alone induced expression of IL-6 by astrocytes and synergized with two other cytokines, IL-1 beta and TNF-alpha, for enhanced IL-6 expression. TGF-beta-induced/enhanced IL-6 expression was mediated by transcriptional activation of the IL-6 gene. These results indicate that TGF-beta is an important regulator of cytokine production by astrocytes under inflammatory conditions in the brain.

Fetal hematopoietic alterations after maternal exposure to ethylene glycol monomethyl ether: prolymphoid cell targeting

Ethylene glycol monomethyl ether (EGME), which is extensively used in the chemical industries, has been associated with hematologic disorders in both humans and experimental animals. EGME is metabolized to the active compound methoxy-acetic acid (MAA), which readily crosses the placenta and impairs fetal development. However, little is known about the effect of maternal EGME exposure on the development of fetal immunity. In the present report, in utero treatment with EGME was found to alter expression of murine thymocyte and liver fetal cell-surface markers. Pregnant mice were exposed to 100, 150, or 200 mg/kg EGME from gestational days (gd) 10 to 17 and offspring examined on gd 18. Significant thymic atrophy and cellular depletion were found in EGME-exposed fetal mice. Flow cytometric analysis indicated that EGME treatment resulted in decreased percentages of CD4+8+ thymocytes and increased percentages of CD4-8- thymocytes. In vitro exposure to MAA did not result in decreased thymocyte viability or proliferation. These data suggest that EGME, in addition to producing thymic hypocellularity, may inhibit thymocyte maturation. EGME also reduced the percentage of CD45+ leukocytic cells present in fetal liver, an alteration that appeared to be largely manifested by decreased numbers of CD45R+ and CD44dim prolymphoid cells. In vitro MAA exposure of fetal liver cells enriched for lymphoid precursors resulted in significant inhibition of proliferation. Reconstitution of irradiated hosts with gd 18 fetal liver cells from vehicle and EGME-exposed syngeneic donors demonstrated impaired ability of the EGME-treated fetal liver to repopulate the host spleen with B or T lymphocytes. These data suggest that EGME-induced immunosuppression may result from targeting of multiple hematopoietic compartments. Further, the present data indicate that fetal liver prolymphocytes may represent sensitive targets of EGME exposure.

Asbestos stimulates IL-8 production from human lung epithelial cells

Studies have indicated that soluble products, including chemotactic factors, released by activated lung macrophages and fibroblasts are critical mediators in the pathogenesis of asbestos-induced pulmonary fibrosis. We provide evidence that mediators produced by lung epithelial cells in response to asbestos may also contribute to lung disease. In the present study, the carcinogenic and fibrogenic fibers, chrysotile and crocidolite asbestos, were shown to directly stimulate the human pulmonary type-II epithelial cell line, A549, and to a lesser degree primary human bronchial epithelial cells, to elicit the chemotactic cytokine IL-8 in the absence of endogenous stimuli such as IL-1 and TNF. That the membrane signaling events responsible for asbestos-induced IL-8 production are distinct from those responsible for IL-8 induction by cytokines was confirmed by using membrane-stabilizing agents and protein synthesis inhibitors. Stimulation was not observed with nonfibrogenic fibers, wollastonite and titanium dioxide, and was the direct result of asbestos-induced initiation of transcription. Asbestos failed to stimulate the release of TNF, IL-1 beta, or monocyte chemoattractant protein-1 in A549 or primary bronchial epithelial cells, indicating that cytokine secretion by asbestos is highly selective. However, a slight release of IL-1 alpha, probably preformed, was released in human bronchial epithelial cells. These data suggest that epithelial cells may, in addition to macrophages and fibroblasts, be an important effector cell in the immunopathogenesis of asbestos-associated diseases and in particular, in the neutrophilic infiltration that is commonly observed after asbestos exposure.

Asbestos stimulates IL-8 production from human lung epithelial cells

Studies have indicated that soluble products, including chemotactic factors, released by activated lung macrophages and fibroblasts are critical mediators in the pathogenesis of asbestos-induced pulmonary fibrosis. We provide evidence that mediators produced by lung epithelial cells in response to asbestos may also contribute to lung disease. In the present study, the carcinogenic and fibrogenic fibers, chrysotile and crocidolite asbestos, were shown to directly stimulate the human pulmonary type-II epithelial cell line, A549, and to a lesser degree primary human bronchial epithelial cells, to elicit the chemotactic cytokine IL-8 in the absence of endogenous stimuli such as IL-1 and TNF. That the membrane signaling events responsible for asbestos-induced IL-8 production are distinct from those responsible for IL-8 induction by cytokines was confirmed by using membrane-stabilizing agents and protein synthesis inhibitors. Stimulation was not observed with nonfibrogenic fibers, wollastonite and titanium dioxide, and was the direct result of asbestos-induced initiation of transcription. Asbestos failed to stimulate the release of TNF, IL-1 beta, or monocyte chemoattractant protein-1 in A549 or primary bronchial epithelial cells, indicating that cytokine secretion by asbestos is highly selective. However, a slight release of IL-1 alpha, probably preformed, was released in human bronchial epithelial cells. These data suggest that epithelial cells may, in addition to macrophages and fibroblasts, be an important effector cell in the immunopathogenesis of asbestos-associated diseases and in particular, in the neutrophilic infiltration that is commonly observed after asbestos exposure.

Conditional immortalization of neuronal cells from postmitotic cultures and adult CNS

To determine whether postmitotic neurons can be immortalized by oncogenic transduction, we used two approaches involving conditional expression of a temperature-sensitive SV40 large T antigen (Tts). Initially, Tts was introduced into E17 rat embryonal hippocampal cells that were then cultured at the non-permissive temperature to enrich for postmitotic pyramidal neurons, and subsequently cloned at the permissive temperature. One clonal line (HMR10-3) expressed neuron-specific proteins upon differentiation, was capable of generating action potentials, and formed synapses with primary rat neurons in co-culture. Replating of these postmitotic cells at the permissive temperature resulted in reversible loss of neurofilament expression. Conditionally immortalized cell lines were also generated from the brain of an adult mouse carrying an inducible Tts transgene. These lines proliferated in a T antigen-dependent manner and expressed neuron-specific proteins upon differentiation at the non-permissive temperature. These results suggest that postmitotic neurons can be induced to enter the cell cycle without losing their commitment to a neuronal lineage.