Search

Following spinal cord injury, the use of electrodes for neurostimulation in animal models has been shown to stimulate muscle movement, however, the efficacy of such treatment is impaired by increased interfacial impedance caused by fibrous encapsulation of the electrode. Sputter-deposited gold-on-polyimide electrodes were modified by potentiostatic electrodeposition of poly(pyrrole-co-3-pyrrolylbutyrate-conj-aminoethylmethacrylate): sulfopropyl methacrylate [P(Py-co-PyBA-conj-AEMA):SPMA] to various charge densities (0–100 mC/cm2) to address interfacial impedance and coated with a phosphoryl choline containing bioactive hydrogel to address biocompatibility at the ABIO-BIO interface. Electrodes were characterized with scanning electron microscopy (surface morphology), multiple-scan rate cyclic voltammetry (peak current and electroactive area), and electrochemical impedance spectroscopy (charge transfer resistance and membrane resistance). SEM analysis and electroactive area calculations identified films fabricated with a charge density of 50 mC/cm2 as well suited for neurostimulation electrodes. Charge transfer resistance demonstrated a strong inverse correlation (−0.83) with charge density of electrodeposition. On average, the addition of polypyrrole and hydrogel to neurostimulation electrodes decreased charge transfer resistance by 82 %. These results support the use of interfacial engineering techniques to mitigate high interfacial impedance and combat the foreign body response towards epidurally implanted neurostimulation electrodes.

Histone chaperones modulate the stability of histones beginning from histone synthesis, through incorporation into DNA, and during recycling during transcription and replication. Following histone removal from DNA, chaperones regulate histone storage and degradation. Here, we demonstrate that UBR7 is a histone H3.1 chaperone that modulates the supply of pre-existing post-nucleosomal histone complexes. We demonstrate that UBR7 binds to post-nucleosomal H3K4me3 and H3K9me3 histones via its UBR box and PHD. UBR7 binds to the non-nucleosomal histone chaperone NASP. In the absence of UBR7, the pool of NASP-bound post-nucleosomal histones accumulate and chromatin is depleted of H3K4me3-modified histones. We propose that the interaction of UBR7 with NASP and histones opposes the histone storage functions of NASP and that UBR7 promotes reincorporation of post-nucleosomal H3 complexes.

The eukaryotic genome is packaged into chromatin. The nucleosome, the basic unit of chromatin, is composed of DNA coiled around a histone octamer. Histones are among the longest-lived protein species in mammalian cells due to their thermodynamic stability and their associations with DNA and histone chaperones. Histone metabolism plays an integral role in homeostasis. While histones are largely stable, the degradation of histone proteins is necessary under specific conditions. Here, we review the physiological and cellular contexts that promote histone degradation. We describe specific known mechanisms that drive histone proteolysis. Finally, we discuss the importance of histone degradation and regulation of histone supply for organismal and cellular fitness.

Rationale: In 2017, the U.S. Centers for Disease Control and Prevention (CDC) developed a new surveillance definition of sepsis, the adult sepsis event (ASE), to better track sepsis epidemiology. The ASE requires evidence of acute organ dysfunction and defines baseline organ function pragmatically as the best in-hospital value. This approach may undercount sepsis if new organ dysfunction does not resolve by discharge. Objectives: To understand how sepsis identification and outcomes differ when using the best laboratory values during hospitalization versus methods that use historical lookbacks to define baseline organ function. Methods: We identified all patients hospitalized at 138 Veterans Affairs hospitals (2013–2018) admitted via the emergency department with two or more systemic inflammatory response criteria, were treated with antibiotics within 48 hours (i.e., had potential infection), and completed 4+ days of antibiotics (i.e., had suspected infection). We considered the following three approaches to defining baseline renal, hematologic, and liver function: the best values during hospitalization (as in the Centers for Disease Control and Prevention’s ASE), the best values during hospitalization plus the prior 90 days (3-mo baseline), and the best values during hospitalization plus the prior 180 days (6-mo baseline). We determined how many patients met the criteria for sepsis by each approach, and then compared characteristics and outcomes of sepsis hospitalizations between the three approaches. Results: Among 608,128 hospitalizations with potential infection, 72.1%, 68.5%, and 58.4% had creatinine, platelet, and total bilirubin measured, respectively, in the prior 3 months. A total of 86.0%, 82.6%, and 74.8%, respectively, had these labs in the prior 6 months. Using the hospital baseline, 100,568 hospitalizations met criteria for community-acquired sepsis. By contrast, 111,983 and 117,435 met criteria for sepsis using the 3- and 6-month baselines, for a relative increase of 11% and 17%, respectively. Patient characteristics were similar across the three approaches. In-hospital mortality was 7.2%, 7.0%, and 6.8% for sepsis hospitalizations identified using the hospital, 3-month baseline, and 6-month baseline. The 30-day mortality was 12.5%, 12.7%, and 12.5%, respectively. Conclusions: Among veterans hospitalized with potential infection, the majority had laboratory values in the prior 6 months. Using 3- and 6-month lookbacks to define baseline organ function resulted in an 11% and 17% relative increase, respectively, in the number of sepsis hospitalizations identified.

Made available in DSpace on 2021-06-25T10:13:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Background: Neurodegeneration is a complex cellular process linked to prompt changes in myelin integrity and gradual neuron loss. Current imaging techniques offer estimations of myelin volumes in lesions/remyelinated areas but are limited to detect subtle injury. Purpose: To investigate whether measurements detected by a signal hierarchically isolated as a function of time-to-echo (SHIFT) MRI technique can determine changes in myelin integrity and fiber axolemma. Study Type: Prospective animal model. Animal Model: Surgically demyelinated spinal cord (SC) injury model in rodents (n = 6). Field Strength/Sequence: Gradient-echo spin-echo at 3T. Assessment: Multicompartment T2 relaxations were computed by SHIFT MRI in 75-microns-resolution images of the SC injury penumbra region 2 weeks post-trauma. G-ratio and axolemma delamination were assessed by transmission electron microscopy (TEM) in intact and injured samples. SC myelinated nerve fraction was computed by SHIFT MRI prospectively and assessed histologically. Statistical Tests: Relations between SHIFT-isolated T2-components and TEM measurements were studied using linear regression and t-tests. Pearson's correlation and significance were computed to determine the SHIFT's sensitivity to detect myelinated fibers ratio in gray matter. Regularized least-squares-based ranking analysis was employed to determine SHIFT MRI's ability to discern intact and injured myelinated nerves. Results: Biexponential signals isolated by SHIFT MRI for intact vs. lesion penumbra exhibited changes in T2, shifting from intermediate components (25 ± 2 msec) to long (43 ± 11 msec) in white matter, and similarly in gray matter regions-of-interest (31 ± 2 to 46 ± 16 msec). These changes correlated highly with TEM g-ratio and axon delamination measurements (P < 0.05). Changes in short T2 components were observed but not statistically significant (8.5 ± 0.5 to 7 ± 3 msec, P = 0.445, and 4.0 ± 0.9 to 7 ± 3 msec, P = 0.075, respectively). SHIFT MRI's ability to detect myelinated fibers within gray matter was confirmed (P < 0.001). Data Conclusion: Changes detected by SHIFT MRI are associated with abnormal intermembrane spaces formed upon mild injury, directly correlated with early neuro integrity loss. Level of Evidence 1. Technical Efficacy Stage 2. Center for Neuroregneration Department of Neurosurgery Houston Methodist Research Institute Houston Methodist Hospital Department of Biological Physics Universidade Estadual Paulista UNESP Division of Arts and Sciences NYU Shanghai NYU-ECNU Institute of Cognitive Neuroscience at NYU Shanghai Center for Neural Science and Department of Psychology New York University Department of Biological Physics Universidade Estadual Paulista UNESP

UBR7 supports nucleotide biosynthesis and NOTCH1-driven T cell acute lymphoblastic leukemia through regulation of PRPS enzymes., Ubiquitin protein ligase E3 component N-recognin 7 (UBR7) is the most divergent member of UBR box–containing E3 ubiquitin ligases/recognins that mediate the proteasomal degradation of its substrates through the N-end rule. Here, we used a proteomic approach and found phosphoribosyl pyrophosphate synthetases (PRPSs), the essential enzymes for nucleotide biosynthesis, as strong interacting partners of UBR7. UBR7 stabilizes PRPS catalytic subunits by mediating the polyubiquitination-directed degradation of PRPS-associated protein (PRPSAP), the negative regulator of PRPS. Loss of UBR7 leads to nucleotide biosynthesis defects. We define UBR7 as a transcriptional target of NOTCH1 and show that UBR7 is overexpressed in NOTCH1-driven T cell acute lymphoblastic leukemia (T-ALL). Impaired nucleotide biosynthesis caused by UBR7 depletion was concomitant with the attenuated cell proliferation and oncogenic potential of T-ALL. Collectively, these results establish UBR7 as a critical regulator of nucleotide metabolism through the regulation of the PRPS enzyme complex and uncover a metabolic vulnerability in NOTCH1-driven T-ALL.

Made available in DSpace on 2019-10-06T15:24:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Several applications of nanoparticles rely on the internalization and accumulation of nanocarriers in specific cell compartments and tissues. However, the methods currently employed for characterizing such processes, although well described, are time consuming and do not provide in vivo information, which is a crucial barrier towards translational applications. Here, we hypothesize that the AC Biosusceptometry technique can be employed to assess cell internalization of magnetic nanoparticles, with possible applications in screening assays to track specific biomarkers and cell types. We tested a simpler and easier alternative to study cell internalization and tissue accumulation after perfusion. We utilized citrate coated, manganese ferrite nanoparticles and evaluated the internalization process in mouse macrophages cells (J774.A1) and in an embryonic neural stem cell culture (E14.5) after differentiation in astrocytes and neurons, to assess internalization specificity. Respecting the particles toxicity limits, we tested different concentration of particles, in different incubation times. Sequentially, we imaged the cell cultures to confirm internalization and nanoparticles localization, labeling nucleus and cell body to assure that the particles were inside the cells. Our results showed a linear behavior on internalization for different doses and an optimum incubation time of 2 h. Departamento de Física e Biofísica Institute of Biosciences Sao Paulo State University (Unesp) Center for Neuroregeneration Houston Methodist Research Institute Departamento de Física Faculdade de Física Ciências e Letras de Ribeirão Preto University of Sao Paulo (USP) Instituto de Física Federal University of Goiás Departamento de Física e Biofísica Institute of Biosciences Sao Paulo State University (Unesp) FAPESP: 2015/14914-0 FAPESP: 2017/00842-2

In the inner ear sensory epithelia, stereociliary hair bundles atop sensory hair cells are mechanosensory apparatus with planar polarized structure and orientation. This is established during development by the concerted action of tissue-level, intercellular planar cell polarity (PCP) signaling and a hair cell-intrinsic, microtubule-mediated machinery. However, how various polarity signals are integrated during hair bundle morphogenesis is poorly understood. Here, we show that the conserved cell polarity protein Par3 is essential for planar polarization of hair cells. Par3 deletion in the inner ear disrupted cochlear outgrowth, hair bundle orientation, kinocilium positioning, and basal body planar polarity, accompanied by defects in the organization and cortical attachment of hair cell microtubules. Genetic mosaic analysis revealed that Par3 functions both cell-autonomously and cell-nonautonomously to regulate kinocilium positioning and hair bundle orientation. At the tissue level, intercellular PCP signaling regulates the asymmetric localization of Par3, which in turn maintains the asymmetric localization of the core PCP protein Vangl2. Mechanistically, Par3 interacts with and regulates the localization of Tiam1 and Trio, which are guanine nucleotide exchange factors (GEFs) for Rac, thereby stimulating Rac-Pak signaling. Finally, constitutively active Rac1 rescued the PCP defects in Par3-deficient cochleae. Thus, a Par3-GEF-Rac axis mediates both tissue-level and hair cell-intrinsic PCP signaling.

The mammalian cochlea contains two types of mechanosensory hair cells (HCs) that play different and critical roles in hearing. Inner hair cells (IHCs), with an elaborate presynaptic apparatus, signal to cochlear neurons and communicate sound information to the brain. Outer hair cells (OHCs) mechanically amplify sound-induced vibrations, enabling enhanced sensitivity to sound and sharp tuning. Cochlear HCs are solely generated during development and their death, most often of OHCs, is the main cause of deafness. OHCs and IHCs, together with supporting cells, originate embryonically from the prosensory region of the otocyst, but how HCs differentiate into two different types is unknown1–3. Here we show that Insm1, which encodes a zinc finger protein transiently expressed in nascent OHCs, consolidates their fate by preventing trans-differentiation into IHCs. In the absence of INSM1 many HCs born embryonically as OHCs switch fates to become mature IHCs. In order to identify the genetic mechanisms by which Insm1 operates, we compared transcriptomes of immature IHCs vs OHCs, as well as OHCs with and without INSM1. OHCs lacking INSM1 upregulate a set of genes, most of which are normally preferentially expressed by IHCs. The homeotic cell transformation of OHCs without INSM1 into IHCs reveals for the first time a mechanism by which these neighboring mechanosensory cells begin to differ: INSM1 represses a core set of early IHC-enriched genes in embryonic OHCs and makes them unresponsive to an IHC-inducing gradient, so that they proceed to mature as OHCs. Without INSM1, some of the OHCs upregulating these few IHC-enriched transcripts trans-differentiate into IHCs, revealing the first candidate genes for IHC-specific differentiation.

The synthesis and characterization of a novel polycyclic azaindole based derivative is disclosed, and its binding to JAK2 is described. The compound is further evaluated for its ability to block the EPO/JAK2 signaling cascade in vitro and in vivo.

While several therapeutic options exist, the need for more effective, safe, and convenient treatment for a variety of autoimmune diseases persists. Targeting the Janus tyrosine kinases (JAKs), which play essential roles in cell signaling responses and can contribute to aberrant immune function associated with disease, has emerged as a novel and attractive approach for the development of new autoimmune disease therapies. We screened our compound library against JAK3, a key signaling kinase in immune cells, and identified multiple scaffolds showing good inhibitory activity for this kinase. A particular scaffold of interest, the 1H-pyrrolo[2,3-b]pyridine series (7-azaindoles), was selected for further optimization in part on the basis of binding affinity (Ki) as well as on the basis of cellular potency. Optimization of this chemical series led to the identification of VX-509 (decernotinib), a novel, potent, and selective JAK3 inhibitor, which demonstrates good efficacy in vivo in the rat host versus graft model (HvG). On the basis of these findings, it appears that VX-509 offers potential for the treatment of a variety of autoimmune diseases.

The synthesis and characterization of a series of self-assembling capsules is described. Assembly takes place as a result of the self-complementary hydrogen bonding patterns on the subunit pieces and dimerization occurs in such a manner that the concave surfaces of the two subunits are directed at one another. This feature gives rise to close-shelled capsules which are shown to encapsulate smaller guest species. Selectivity is shown for guests ranging in size from methane to adamantane derivatives. Shape selectivity is shown in special capsules capable of recognizing disc-like molecules such as benzene and cyclohexane. Disproportionation reactions are shown to exist between capsules of slightly different sizes, and these are shown to be controlled by the nature of the guest species. The use of these capsules as reaction chambers is proposed.

Pictet-Spengler condensation of aldehydes or alpha-keto-esters with 4-(2-anilinophenyl)-7-azaindole (11) or deazapurine (12) gave high yields of the 3,4-fused cyclic compounds. SAR studies, by varying the substituted benzaldehyde components, lead to the discovery of a series of potent JAK2 kinase inhibitors.

The factors determining the L-stereospecificity of the L-lactate dehydrogenase from Bacillus stearothermophilus have been probed by introducing Arg171Trp/Tyr and Gln102Arg mutations. These changes preclude normal 2-keto acid substrate binding via an Arg171-COO - electrostatic interaction and are positioned to induce a reversal of the natural substrate binding mode, thereby leading to D-2-hydroxy acid formation. However, the L-stereospecificities of the mutant enzymes remain unchanged, showing that there are important fail-safe stereospecificity determinants that take over when the key Arg171-COO - binding interaction is removed

Bacillus stearothermophilus lactate dehydrogenase, one of the most thermostable bacterial enzymes known, has had its three-dimensional structure solved, the gene coding for it has been cloned, and the proteincan be readily overexpressed. Two mutants of the enzyme have been prepared. In one, Arg171 was changed to Trp (R171W) and Gln102 was changed to Arg (Q102R). In the other, the mutation Q102R was maintained, but Arg171 was changed to Tyr (R171Y). In addition, an inadvertent C97G mutant was present. Both mutants have been crystallized by the hanging drop vapor diffusion method at room temperature. Bipyrimidal crystals have been obtained against (NH4)2SO4in 50 mM piperazine HCI buffer. The crystals belong to space group P6622 (P6622) (whereas the native enzyme, the structure of which has been solved by Piontek et al., Proteins 7:74–92, 1990) crystallized in the space group (P61) with a = 102.3 A, c = 168.6 A for the R171W, Q102R, C97G triple mutant, and a = 98.2 A; c = 162.1 A for the R171Y, Q102R, C97G mutant. These crystal forms appear to contain one-quarter of a tetramer (Mr 135,000)in the asymmetric unit and have (VM values of 3.8 and 3.3 A3/dalton, respectively). The R171W mutant diffracts to 2.5 A and the R171Y mutant to approximately 3.5 A © 1992 Wiley-Liss, Inc.

Pictet-Spengler condensation of aldehydes or alpha-keto-esters with 4-(2-anilinophenyl)-7-azaindole (11) or deazapurine (12) gave high yields of the 3,4-fused cyclic compounds. SAR studies, by varying the substituted benzaldehyde components, lead to the discovery of a series of potent JAK2 kinase inhibitors.

Constitutive activation of the EPO/JAK2 signaling cascade has recently been implicated in a variety of myeloproliferative disorders including polycythemia vera, essential thrombocythemia and myelofibrosis. In an effort to uncover therapeutic potential of blocking the EPO/JAK2 signaling cascade, we sought to discover selective inhibitors that block the kinase activity of JAK2. Herein, we describe the discovery and structure based optimization of a novel series of 2-amino-pyrazolo[1,5-a]pyrimidines that exhibit potent inhibition of JAK2.

We investigated whether vagal cardiac cholinergic facilitation by nitric oxide (NO) is mediated by cardiac muscarinic receptor subtypes in the vagally innervated rat right atrium in vitro. Experiments were carried out in the presence of atenolol (4 μM). The right vagus was stimulated at 4, 8, 16, 32 Hz; pulse duration 1 ms at 20 V for 20 s; vagal postganglionic activation was achieved using nicotine (0.1, 0.3, 0.5, 1 mM) and the effect on cardiac interval (ms) assessed. Pirenzepine (1 μM), a M1 antagonist, attenuated vagally induced increase in cardiac interval. l -Arginine (0.34 mM) superfused with pirenzepine failed to reverse this attenuation, however, l -arginine applied alone reversed the reduction vagal cardiac slowing. Similarly, sodium nitroprusside (10 μM) applied alone, and not together with pirenzepine, was able to reverse the attenuation of vagal effects caused by pirenzepine. Synthetic MT7 (1 nM) toxin, a selective M1 antagonist confirmed these results. M3 antagonism using para-fluorohexahydrosiladifenidol (p-F-HHSiD) (300 nM) and M4 antagonism with PD 102807 (200 nM) did not affect the vagally induced increase in cardiac interval. Nicotine induced increase in cardiac interval was not altered by pirenzepine. These results show that antagonism of M1 receptors on cardiac vagal preganglionic fibres reduces vagal efficacy which can be recovered by either a nitric oxide synthase substrate or a NO donor.

The presence of the vagal tachycardia and the effect of vasoactive intestinal polypeptide in the isolated innervated rat atrium were investigated. The right vagus, or cardiac branch, were stimulated at 4, 8, 16 and 32 Hz, pulse duration 1 ms, 20 V, 30 s before atropine and for 1 min after atropine (3 micromol/l), experiments were carried out in the presence of atenolol (4 micromol/l). No significant vagal tachycardia was observed in the presence of atropine, the greatest increase in heart rate was at 16 Hz which was 3+/-1 beats/min (n = 12 rats) (p = 0.052). Baseline heart rates for the control, 226+/-11 beats/min (n = 12 rats) and atropine experiments, 210+/-8 beats/min (n = 12 rats), were not significantly different (p = 0.24). VIP (0.06, 0.12, 0.24 micromol/l) caused a maximum increase of 27+/-13 beats/min (n = 5 rats) after 6 micromol/l VIP which was not significant, two higher concentrations of VIP failed to increase heart rate further. These results show that the vagal tachycardia is not present and that VIP does not cause a significant tachycardia in the rat.

Commerically available yttrium oxide nanopowders were evaluated as starting materials for preparation of transparent materials. The objective is an yttria optical ceramic exhibiting approximately one micrometer grain size to provide increased strength and thermal shock resistance. Three vendors were selected to provide nanoscale powders for testing and evaluation. They were compared to a conventional (5 μm) powder previously used to prepare optical quality ceramic yttria. While all of the selected nanopowders had impurity levels that were too high to allow processing to full transparency, two of the samples were processed to full density and moderate transparency was produced in one. In preparation for processing via Hot Isostatic Press (HIP) samples were sintered to a closed pore state at temperatures as low as 1400 °C, and with soak times as short as 12 minutes at 1550 °C. The use of ultrasonic attenuation as a technique for measuring particle size distributions in slurries was explored and found to be an invaluable tool when colloidally processing nanopowders. Finally, the areas most important for continued improvements were identified.

Renal insufficiency is frequently reported in mutase-deficient methylmalonic acidaemia. We present a case report of a patient with mut– methylmalonic acidaemia who developed chronic tubulointerstitial nephropathy during adolescence. At 24 years of age, she developed end-stage renal failure and underwent renal transplantation. Both plasma and urine methylmalonic acid levels decreased significantly with improved renal function following transplantation. Complications included cyclosporin toxicity and development of diabetes. Renal, metabolic, and clinical status remained improved at 3 years after the kidney transplant.

The substrate specificities of L-alpha-hydroxy acid dehydrogenases, including L-lactate dehydrogenases (L-LDH's), can often be quite broad. However, an LDH with high catalytic activity toward alpha-keto acids with positively charged side chains, such as those containing ammonium groups, has not been described, even though there is evidence from metabolic studies that a natural dehydrogenase with such activity might exist in Nature. L-omega-Amino-alpha-hydroxy acids are important intermediates in the synthesis of pharmacologically active compounds, and enzymatic reduction of omega-amino-alpha-keto acids represents an attractive route to these compounds. Graphics analysis indicated that introduction of acidic amino acids at position 102 of the L-LDH of Bacillus stearothermophilus (BSLDH) would favor binding of such side chain ammonium groups. Accordingly, Q102E and Q102D mutant BSLDH's were constructed and the steady state kinetic parameters determined for these mutants for a broad range of alpha-keto acids, including omega-amino-keto acids. The results obtained show that, compared to WT-BSLDH, these mutants show up to 25-fold improvements in kcat/Km values for omega-amino-alpha-keto acid substrates.

Subchronic 90-day feeding studies were conducted on four highly refined white mineral oils to determine any potential for toxicity in Long-Evans rats (20 per sex per dose level) and beagle dogs (4 per sex per dose level). Each oil was fed at dietary dose levels of 300 ppm and 1500 ppm (w/w). No treatment-related effects of toxicological importance were detected in daily observations of general health or in periodic assessments of food consumption and body weight, hematology, serum clinical chemistry, and urinalysis. Observations in dogs suggested that the white oils produced mild laxative effects. Gross and histopathologic examinations, as well as measurements of organ weights, did not reveal any macroscopic or microscopic changes which could be due to treatment. In addition, special staining by Oil Red O of liver, mesenteric lymph nodes, spleen, gastrointestinal tract, stomach, and kidneys indicated no evidence of oil or lipid deposition. A special re-examination of tissues from female and male rats, in response to more recent conflicting data from the Fischer 344 strain, found no histopathologic signs of macrophage accumulation and/or microgranuloma formation in liver, spleen, or mesenteric lymph nodes. These data indicate that repeated exposure to relatively high levels of white mineral oils in the diets does not produce significant subchronic toxicity in Long-Evans rats or beagle dogs.

Corrigendum Corrigendum to ‘‘A novel chemotype of kinase inhibitors: Discovery of 3,4-ring fused 7-azaindoles and deazapurines as potent JAK2 inhibitors” [Bioorg. Med. Chem. Lett. 20 (2010) 153] Tiansheng Wang *, Mark W. Ledeboer *, John P. Duffy, Francesco G. Salituro , Albert C. Pierce, Harmon J. Zuccola, Eric Block, Dina Shlyakter, James K. Hogan, Youssef L. Bennani Vertex Pharmaceuticals Inc., 130 Waverly St., Cambridge, MA 02139-4242, United States

Mice were exposed to various concentrations of volatile hydrocarbons and measurements made of respiratory rate, depth and configuration while the animals were inhaling the agent. Mice were exposed to the volatile hydrocarbons n-pentane, n-hexane, n-heptane or iso-octane. Additional mice were also exposed to the anesthetics diethyl ether or methoxyflurane for comparative purposes. The concentrations used were 1,000; 2,000; 4,000; 8,000; 16,000; 32,000; 64,000 and 128,000 ppm. Exposures were for five minutes. The volatile hydrocarbons from pentane to heptane produced anesthesia and were irritating to the respiratory system. The irritation increased in intensity with the length of the carbon chain. Iso-octane was highly irritating even at the lower concentrations. As the number of carbons increased the anesthetic properties became less and the concentration needed to produce narcosis and respiratory arrest was lower. When respiratory arrest occurred with all off the agents except iso-octane it took place at ...

Human lymphocytes treated In vitro with BZD and DAT were examined for induced chromosome aberrations. While DAT was not metabolised to a clastogen by induced or uninduced rat liver S9, BZD was found to be positive in both the absence and presence of S9. The order of response was: uninduced S9 > no S9 > induced S9.

An enzyme preparation, having ribonuclease activity, has been isolated from livers of fed and fasted rats by extraction with H 2 SO 4 . The enzyme activity is decreased in fed rats compared with fasted ones, as enzyme concentration is increased. This decrease could not be due to inhibition by the glycoprotein inhibitor of ribonuclease since this is destroyed by acid treatment. The inhibition of the ribonuclease-catalyzed reaction observed in fed rats was probably not due to Ca 2+ . The role of this acid-stable ribonuclease in the degradation of rRNA is discussed.