A Comparison of the Hybrid III and BioRID II Dummies in Low-Severity, Rear-Impact Sled Tests

A BioRID II dummy and a Hybrid III dummy, each representative of a midsize adult male, were tested side-by-side in simulated rear-impact sled tests. In all tests the dummies were restrained by 3-point belt systems. The results of 4 test sets conducted at a nominal change in velocity (deltaV) of 16 km/hr are presented and discussed. In three of the test sets, bucket seats were used. The head restraints were placed in the up-position in two of the three test sets and in the down-position in the third set of tests. In the fourth test set, rigid seats without any head restraints were used. While analyzing the BioRID II data, the presence of an axial neck load acting on the head, which bypassed the upper neck load transducer, was discovered in all the reported tests. The implication of this observation is that the axial force and all the moments measured by the BioRID II upper neck load transducer could be erroneous. A second concern with the BioRID II data was the high frequency noise observed, especially on the T1 acceleration response which is used in the NIC calculation. The 18 Hz filter used to process the T1 acceleration data for the NIC calculation attenuated the peak NIC values by 15% as compared to the SAE 180 filtered values. The unmeasured neck loads and high-frequency noise issues need to be resolved before additional BioRID II testing is done. A third concern with the BioRID II is the initial position of its head in the automotive seating posture. It is higher and more forward than that of the 50(th) percentile adult male.

Intramolecular Mannich reaction in the asymmetric synthesis of polysubstituted piperidines: concise synthesis of the dendrobate alkaloid (+)-241D and its C-4 epimer

[reaction: see text] The intramolecular Mannich reaction of delta-amino beta-keto esters with aldehydes and ketones is a new methodology for the synthesis of polysubstituted piperidines and is illustrated by the concise asymmetric synthesis of the dendrobate alkaloid (+)-241D and its C-4 epimer.

Antibiotic resistant N. gonorrhoeae in Trinidad and Tobago

We tested the susceptibility patterns of 128 N. gonorrhoeae isolates to six antimicrobials; penicillin, tetracycline, spectinomycin, ceftriaxone, ciprofloxacin and azithromycin, and examined whether certain demographic or behavioral factors related to antibiotic use increased the likelihood of infection by a resistant strain. There was a low rate of resistance to penicillin; penicillinase-producing and chromosomal-mediated penicillin resistant gonorrhea were estimated to be 0.8%. A much higher proportion of isolates were resistant to tetracycline (up to 15%). All isolates were sensitive to spectinomycin, ciprofloxacin and ceftriaxone. However, less than 2% of isolates displayed intermediate resistance to both ciprofloxacin and ceftriaxone, and 9% exhibited intermediate resistance to spectinomycin. Patients who had obtained medication before attending the clinic and had taken all of the medication were more likely (p = 0.03) to be infected with a resistant strain of gonococcus. Also, patients who were asked by a clinic doctor to return for a test of cure during an earlier clinic visit, but who did not return were more likely to be infected with a resistant organism (p = 0.006) compared to those who returned at the doctor's request. These findings have important implications for antibiotic use and educational programs in Trinidad and Tobago.

Regulation of interferon-gamma gene expression by nuclear factor of activated T cells

Transcription factors of the nuclear factor of activated T cells (NFAT) family are thought to regulate the expression of a variety of inducible genes such as interleukin-2 (IL-2), IL-4, and tumor necrosis factor-alpha. However, it remains unresolved whether NFAT proteins play a role in regulating transcription of the interferon- gamma (IFN-gamma) gene. Here it is shown that the transcription factor NFAT1 (NFATc2) is a major regulator of IFN-gamma production in vivo. Compared with T cells expressing NFAT1, T cells lacking NFAT1 display a substantial IL-4-independent defect in expression of IFN-gamma mRNA and protein. Reduced IFN-gamma production by NFAT1(-/-)x IL-4(-/-) T cells is observed after primary in vitro stimulation of naive CD4+ T cells, is conserved through at least 2 rounds of T-helper cell differentiation, and occurs by a cell-intrinsic mechanism that does not depend on overexpression of the Th2-specific factors GATA-3 and c-Maf. Concomitantly, NFAT1(-/-)x IL-4(-/-) mice show increased susceptibility to infection with the intracellular parasite Leishmania major. Moreover, IFN-gamma production in a murine T-cell clone is sensitive to the selective peptide inhibitor of NFAT, VIVIT. These results suggest that IFN-gamma production by T cells is regulated by NFAT1, most likely at the level of gene transcription.

Discovery of 2,3-diaryl-1,3-thiazolidin-4-ones as potent anti-HIV-1 agents

Design, synthesis and anti-HIV activity of a series of 2,3-diaryl-1,3-thiazolidin-4-ones are reported. Some derivatives proved to be highly effective in inhibiting HIV-1 replication at nanomolar concentrations thereby acting as non-nucleoside HIV-1 RT inhibitors (NNRTIs). SAR studies evidenced that the nature of the substituents at the 2 and 3 positions of the thiazolidinone nucleus largely influenced the in vitro anti-HIV activity of this new class of potent antiviral agents.

Bridging the NFAT and NF-kappaB families: NFAT5 dimerization regulates cytokine gene transcription in response to osmotic stress

The transcription factor NFAT5/TonEBP is evolutionarily the oldest member of the NFAT/Rel family of transcription factors. We show that NFAT5 is uniquely related to NF-kappaB and is the only member of the Rel/NFAT family to be activated by osmotic stress. Like Rel/NF-kappaB proteins but unlike the calcium-regulated NFAT proteins, NFAT5 is constitutively dimeric, and dimerization is essential for DNA binding and transcriptional activity. Using dominant-negative proteins that inhibit NFAT5 dimerization, we show that NFAT5 regulates expression of the TNFalpha and lymphotoxin-beta genes in osmotically stressed T cells. Chromatin immunoprecipitation experiments confirm that NFAT5 binds to the TNFalpha promoter in vivo. We suggest that NFAT5 participates in specific aspects of host defense by upregulating TNF family genes and other target genes in T cells.

Unexpectedly high defibrillation thresholds in an active can implantable cardioverter defibrillator system

This case report describes a patient undergoing defibrillator generator replacement in whom the defibrillation thresholds were significantly higher with a can-active system than with a non-active can system.

Chronic food-restriction alters the expression of somatostatin and growth hormone-releasing hormone in the ovariectomised ewe

Changes in the secretion of GH induced by long-term alterations in nutritional status are thought to result from alterations in somatostatin (SRIF) and growth hormone-releasing hormone (GHRH) at the level of the hypothalamus. To date however, the effect of nutrition on the gene expression of SRIF and GHRH in a species where GH secretion is increased by food restriction, as is the case for the sheep and human, remains unknown. We determined the effect of under-nutrition on the expression of SRIF and GHRH in the hypothalamus of sheep. Ovariectomised ewes were randomly divided into two groups and either fed an ad lib diet (n=6) or a restricted diet of 500 g lucerne chaff per day (food-restricted; n=5) for 7 months. In situ hybridisation was used to study hypothalamic gene expression for GHRH, SRIF and galanin (GAL). The food-restricted animals had elevated plasma concentrations of GH; this was associated with an increase in GHRH mRNA levels in the arcuate nucleus (ARC) and reduced SRIF in the rostral periventricular nucleus and ventromedial hypothalamic nucleus. The level of gene expression of GAL in the ARC and SRIF in the caudal periventricular nucleus was similar in ad lib and food-restricted animals. In conclusion, the effect of chronic food-restriction on the secretion of GH reflects increased GHRH and reduced SRIF synthesis in the hypothalamus.

Synthesis and antitumour activity of 1H,3H-thiazolo[3,4-a]benzimidazole derivatives

A series of 1H,3H-thiazolo[3,4-a]benzimidazoles were synthesized and tested for their in vitro antitumour activity against 60 human tumour cell lines. Some derivatives exhibited both tumour growth inhibition activity and cellular selectivity. In particular, compound 8c, the most active of the series, was very active towards all cell lines at concentrations ranging from 10(-7)-10(-5) M. Compound 4a, on the other hand, was highly selective against the CNS cancer cell line.

7-Chloro-1-(2,6-difluorophenyl)-1H,3H-thiazolo[3,4-a]benzimidazole and 1-(2,6-difluorophenyl)-6-methyl-1H,3H-thiazolo[3,4-a]benzimidazole

The title molecules, C(15)H(9)ClF(2)N(2)S and C(16)H(12)F(2)N(2)S, respectively, display the well known butterfly-like conformation with a flat thiazolobenzimidazole system. In both compounds, the mean plane through the tricyclic system is almost perpendicular to the 2,6-difluorophenyl ring. This arrangement of the aryl group is determined by two intramolecular hydrogen bonds and by an attractive F.S interaction.

New functions for DNA binding domains

How the same transcription factor can be both an activator and a repressor of transcription is a biological mystery. Rao describes work that shows that the structure of the transcription factor may actually change depending on the DNA sequence bound by the factor. This change in structure may influence the binding of activators or repressors of transcription, thus allowing a single transcription factor to have two different activities.

Synthesis, biological activity, pharmacokinetic properties and molecular modelling studies of novel 1H,3H-oxazolo[3,4-a]benzimidazoles: non-nucleoside HIV-1 reverse transcriptase inhibitors

New 1H,3H-oxazolo[3,4-albenzimidazoles (OBZs) were synthesized as HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTI) to extend the structure-activity relationships observed for an early series of related 1H,3H-thiazolo[3,4-a]benzimidazole derivatives (TBZs). The new compounds showed inhibitory activity against the replication of various HIV-1 strains, including NNRTI-resistant strains. Testing of a representative OBZ derivative in an HPLC assay on biological fluids, indicated that the sulphur substitution appreciably improved the metabolic stability of the TBZ compound. In addition, molecular modelling studies demonstrated that OBZs, TBZs and other NNRTIs have similar structural properties, that is a butterfly-like conformation, which is a key structural requirement for reverse transcriptase inhibition.

Partners in transcription: NFAT and AP-1

Combinatorial regulation is a powerful mechanism that enables tight control of gene expression, via integration of multiple signaling pathways that induce different transcription factors required for enhanceosome assembly. The four calcium-regulated transcription factors of the NFAT family act synergistically with AP-1 (Fos/Jun) proteins on composite DNA elements which contain adjacent NFAT and AP-1 binding sites, where they form highly stable ternary complexes to regulate the expression of diverse inducible genes. Concomitant induction of NFAT and AP-1 requires concerted activation of two different signaling pathways: calcium/calcineurin, which promotes NFAT dephosphorylation, nuclear translocation and activation; and protein kinase C (PKC)/Ras, which promotes the synthesis, phosphorylation and activation of members of the Fos and Jun families of transcription factors. A fifth member of the NFAT family, NFAT5, controls the cellular response to osmotic stress, by a mechanism that requires dimer formation and is independent of calcineurin or of interaction with AP-1. Pharmacological interference with theNFAT:AP-1 interaction may be useful in selective manipulation of the immune response. Balanced activation of NFAT and AP-1 is known to be required for productive immune responses, but the role of NFAT:AP-1 interactions in other cell types and biological processes remains to be understood.

Transcriptional regulation in lymphocytes

Lymphocytes have been used to investigate many cellular processes, including lineage commitment, differentiation, proliferation and apoptosis. The transcription factors that mediate these processes are often expressed broadly in many cell types. The emerging theme is one of cell-type-specific regulation, affecting not only the functional activation of transcription factors but also their access to appropriate regions of DNA.

Gene regulation mediated by calcium signals in T lymphocytes

Modulation of many signaling pathways in antigen-stimulated T and B cells results in global changes in gene expression. Here we investigate the contribution of calcium signaling to gene expression in T cells using cell lines from two severe-combined immunodeficiency patients with several cytokine deficiencies and diminished activation of the transcription factor NFAT nuclear factor of activated T cells. These T cells show a strong defect in transmembrane calcium influx that is also apparent in their B cells and fibroblasts. DNA microarray analysis of calcium entry-deficient and control T cells shows that Ca2+ signals both activate and repress gene expression and are largely transduced through the phosphatase calcineurin. We demonstrate an elaborate network of signaling pathways downstream of the T cell receptor, explaining the complexity of changes in gene expression during T cell activation.

Signaling between the actin cytoskeleton and the postsynaptic density of dendritic spines

The dendritic spine may be considered a fusion of a specialized actin-based structure akin to filopodia and lamellopodia, with an excitatory postsynaptic density containing glutamate receptors and signal-transducing machinery. This specialized neuronal microdomain is the site of the majority of excitatory synaptic contacts in the mammalian brain. Regulation of spine morphology, composition, and stability are likely to contribute to long-lasting changes in synaptic efficacy. Thus, understanding the function and regulation of dendritic spines is a fundamental problem ranging from molecular through behavioral neurobiology. A complete understanding of dendritic spines will require a knowledge of all the molecular components and how these components interact. Here we wish to accomplish two goals: to catalog many of the known components of hippocampal dendritic spines and suggest how these may contribute to spine function; and to compare dendritic spines with other actin-based structures, namely lamellopodia, filopodia, microvilli, and stereocilia, to gain some insight into possible common vs. specialized mechanisms of regulation of the shape, motility, and longevity of these actin-based structures.

Simultaneous pancreas-kidney transplantation at the University of Pittsburgh

Analysis of the SPK program at the University of Pittsburgh has led to a number of observations: 1. Under tacrolimus-based immunosuppression, without antibody induction, it has been possible to achieve (a) One- and 3-year actuarial patient survival rates of 98% and 95% (b) One- and 3-year actuarial kidney survival rates of 95% and 87% (c) One- and 3-year actuarial pancreas survival rates of 86% and 80% 2. Steroid withdrawal has been achieved in over half of the successfully transplanted recipients, with excellent outcomes and a low rate (4.7%) of subsequent rejection. 3. Bone marrow augmentation has been associated with (a) less rejection (b) less pancreatic graft loss to rejection (c) an increased ability to withdraw steroids 4. Rejection has been associated with a rising serum lipase. 5. Renal allograft rejection in SPK patients with elevated serum lipase levels has been seen in the setting of normal renal function. 6. Enteric drainage has been associated with a reasonably low complication rate. 7. SPK transplantation is a successful therapeutic option in selected type I diabetics with end-stage renal disease.

Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: isolated channels between scars allow "focal" ablation

BACKGROUND

The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD).

METHODS AND RESULTS

Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan procedure in 6). Electroanatomic right atrial maps were obtained during 15 MacroATs in 13 patients, focal AT in 1 patient, and atrial pacing in 2 patients without stable AT. A large area of low bipolar voltage (</=0.5 mV) involved most of the free wall in all patients and contained 2 to 7 dense scars or lines of double potentials, forming 29 narrow channels (width </=2.7 cm) between scars in all but 1 patient, who had a single scar and only focal AT. All 15 MacroATs were propagated through narrow channels. Ablation within the channel eliminated all 15 MacroATs with 1 to 3 (median 1) radiofrequency applications. Ablation was performed in 9 other channels identified during MacroAT (5 patients) and in 5 channels identified during atrial pacing (2 patients). Conduction block was obtained across 28 of 29 channels. After ablation, reproducible sustained right AT was not induced in any patient. During follow-up (median 13.5 months), new MacroATs, atrial fibrillation, or palpitations occurred in 3 of 16 patients.

CONCLUSIONS

MacroAT after SR-CHD requires a large area of low voltage containing >/=2 scars forming narrow channels. Ablation within the channels eliminates MacroAT.

Oxidative stress and antioxidants in epilepsy

In the present study, erythrocyte membrane lipid peroxidation, the percentage hemolysis, erythrocyte enzymes superoxide dismutase (SOD), glutathione peroxidase (GP), glutathione reductase (GR), catalase, and plasma vitamin C, vitamin E, vitamin A and ceruloplasmin activities and concentrations were determined in 29 epileptic patients and 50 normal controls. Ten patients who were treated with phenobarbital and who did not get convulsions for 1 year were considered for followup. Lipid peroxidation and percentage hemolysis in patients with epilepsy was significantly higher when compared to controls. Moreover, plasma ceruloplasmin concentrations were also markedly increased in these cases. Erythrocyte GR and plasma vitamin C and A concentrations were significantly lower in epileptics when compared to controls. In the followup patients, the erythrocyte GR was significantly higher than their pre-treated condition. Furthermore, the plasma vitamin A, E and C concentrations have attained the normal range. This study indicates that the antioxidant status in blood of epileptic patients which was low compared to controls, improved after treatment, suggesting that free radicals may be implicated in epilepsy.

Proenkephalin and opioid mu-receptor mRNA expression in ovine hypothalamus across the estrous cycle

The neural mechanism underlying the preovulatory surge of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) is thought to include reduced opioid inhibition of GnRH secretion (disinhibition). Possible mechanisms for disinhibition include reduced endogenous opioid peptide or receptor mRNA expression. Proenkephalin and opioid mu-receptor mRNA expression were measured by in situ hybridization using 35S-labeled cRNA probes and computer-assisted grain counting in hypothalamic nuclei of ovary-intact ewes (n = 4) killed on day 10 of the luteal phase or 24 or 48 h into the follicular phase. In a second experiment, proenkephalin and mu-receptor mRNA expression were compared in ewes killed on day 10 of the luteal phase or during the preovulatory LH surge. Cells expressing proenkephalin mRNA were more widely distributed in ovine hypothalamus than previously described. In the periventricular nucleus, there was a significant reduction in the grain count per cell and the number of labeled cells during the follicular phase and during the LH surge, as compared to the luteal phase. In the ventromedial hypothalamus, there was a significant reduction in the grain count per cell during the follicular phase and LH surge as compared to the luteal phase, but no change in the number of labeled cells. No differences in proenkephalin mRNA expression were detected in the medial septum, diagonal band of Broca, preoptic area, anterior hypothalamic area or paraventricular nucleus across the estrous cycle. Cells expressing opioid mu-receptor mRNA were also widely distributed. No difference in mu-receptor mRNA expression was detected in the medial septum, diagonal band, medial preoptic area, anterior hypothalamus or bed nucleus of the stria terminalis across the cycle. We conclude that in sheep, proenkephalin gene expression in the periventricular nucleus and ventromedial hypothalamus is reduced during the follicular phase and at the time of the LH surge. This may be part of the neural mechanism underlying the GnRH/LH surge in this species.