Reduction of Stratospheric Ozone by Nitrogen Oxide Catalysts from Supersonic Transport Exhaust

Although a great deal of attention has been given to the role of water vapor from supersonic transport (SST) exhaust in the stratosphere, oxides of nitrogen from SST exhaust pose a much greater threat to the ozone shield than does an increase in water. The projected increase in stratospheric oxides of nitrogen could reduce the ozone shield by about a factor of 2, thus permitting the harsh radiation below 300 nanometers to permeate the lower atmosphere.

Amino-terminal fragments of mutant huntingtin show selective accumulation in striatal neurons and synaptic toxicity

Huntington disease (HD) is caused by expansion of a glutamine repeat in the amino-terminal region of huntingtin. Despite its widespread expression, mutant huntingtin induces selective neuronal loss in striatal neurons. Here we report that, in mutant mice expressing HD repeats, the production and aggregation of N-terminal huntingtin fragments preferentially occur in HD-affected neurons and their processes and axonal terminals. N-terminal fragments of mutant huntingtin form aggregates and induce neuritic degeneration in cultured striatal neurons. N-terminal mutant huntingtin also binds to synaptic vesicles and inhibits their glutamate uptake in vitro. The specific processing and accumulation of toxic fragments of N-terminal huntingtin in HD-affected striatal neurons, especially in their neuronal processes and axonal terminals, may contribute to the selective neuropathology of HD.

The expanding phenotype of laminin alpha2 chain (merosin) abnormalities: case series and review

Initial reports of patients with laminin alpha2 chain (merosin) deficiency had a relatively homogeneous phenotype, with classical congenital muscular dystrophy (CMD) characterised by severe muscle weakness, inability to achieve independent ambulation, markedly raised creatine kinase, and characteristic white matter hypodensity on cerebral magnetic resonance imaging. We report a series of five patients with laminin alpha2 deficiency, only one of whom has this severe classical CMD phenotype, and review published reports to characterise the expanded phenotype of laminin alpha2 deficiency, as illustrated by this case series. While classical congenital muscular dystrophy with white matter abnormality is the commonest phenotype associated with laminin alpha2 deficiency, 12% of reported cases have later onset, slowly progressive weakness more accurately designated limb-girdle muscular dystrophy. In addition, the following clinical features are reported with increased frequency: mental retardation (~6%), seizures (~8%), subclinical cardiac involvement (3-35%), and neuronal migration defects (4%). At least 25% of patients achieve independent ambulation. Notably, three patients with laminin alpha2 deficiency were asymptomatic, 10 patients had normal MRI (four with LAMA2 mutations reported), and between 10-20% of cases had maximum recorded creatine kinase of less than 1000 U/l. LAMA2 mutations have been identified in 25% of cases. Sixty eight percent of these have the classical congenital muscular dystrophy, but this figure is likely to be affected by ascertainment bias. We conclude that all dystrophic muscle biopsies, regardless of clinical phenotype, should be studied with antibodies to laminin alpha2. In addition, the use of multiple antibodies to different regions of laminin alpha2 may increase the diagnostic yield and provide some correlation with severity of clinical phenotype.

The foetal Leydig cell-- differentiation, function and regulation

The foetal Leydig cell population arises shortly after testicular differentiation at around 12.5 dpc in the mouse and 6 weeks in the human. These cells function, primarily, to produce androgens which are essential for masculinization of the foetus. The origin of the foetal Leydig cells remains uncertain but it has been suggested that adrenocortical cells and foetal Leydig cells may share a common origin in an adreno-genital primordium. Studies in the mouse are beginning to identify factors such as desert hedgehog and platelet-derived growth factor which are required for foetal Leydig cell development. Regulation of foetal Leydig cell function remains uncertain in most species. Unlike the adult population of Leydig cells, the foetal Leydig cells in the mouse do not require luteinizing hormone (LH) to stimulate androgen production. An intact pituitary does appear to be required, however, and adrenocorticotrophic hormone (ACTH) will stimulate foetal Leydig cell function directly suggesting that both LH and ACTH act to maintain Leydig cell function in vivo. In the human LH/hCG is required for foetal Leydig cell function although the cells may also be sensitive to ACTH.

A Picolinic Acid Derivative: A Plant Growth Regulator

4-Amino-3,5,6-trichloropicolinic acid is more toxic to many broad-leaved plants than 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. It is comparable in absorption by foliage, in translocation, and in soil-leaching characteristics; in soil, however, it retains its activity for a longer time.

Sex and Gender Differences in Occupational Hazard Exposures: a Scoping Review of the Recent Literature

PURPOSE OF REVIEW

Comparative research on sex and/or gender differences in occupational hazard exposures is necessary for effective work injury and illness prevention strategies. This scoping review summarizes the peer-reviewed literature from 2009 to 2019 on exposure differences to occupational hazards between men and women, across occupations, and within the same occupation.

RECENT FINDINGS

Fifty-eight studies retrieved from eight databases met our inclusion criteria. Of these, 30 studies were found on physical hazards, 38 studies on psychological/psychosocial hazards, 5 studies on biological hazards, and 17 studies on chemical hazards. The majority of studies reported that men were exposed to noise, vibration, medical radiation, physically demanding work, solar radiation, falls, biomechanical risks, chemical hazards, and blood contamination; while women were exposed to wet work, bullying and discrimination, work stress, and biological agents. Within the same occupations, men were more likely to be exposed to physical hazards, with the exception of women in health care occupations and exposure to prolonged standing. Women compared to men in the same occupations were more likely to experience harassment, while men compared to women in the same occupations reported higher work stress. Men reported more exposure to hazardous chemicals in the same occupations as women. The review suggests that men and women have different exposures to occupational hazards and that these differences are not solely due to a gendered distribution of the labor force by occupation. Findings may inform prevention efforts seeking to reduce gender inequalities in occupational health. Future research is needed to explain the reasons for sex/gender inequality differences in exposures within the same occupation.

Ontogeny of aquaporins 1 and 3 in ovine placenta and fetal membranes

A sensitive and highly reproducible method has been used to show that Aquaporin 3 (AQP(3)) mRNA is present in the ovine placenta and chorion from at least 60 days of gestation (term=145-150d) with levels increasing substantially (>16 fold) at 100 days, and remaining constant thereafter. By immuno- and hybridization histochemistry, the epithelial cells expressing AQP(3)were found to be the trophoblast cells. Some AQP(3)was expressed in fibroblasts of the amnion and allantois but none was expressed in the epithelia of these membranes. AQP(1)was expressed in endothelial cells of fetal and maternal blood vessels but not in any epithelial cell of the ovine placenta and fetal membranes. The level of AQP(3)expression is consistent with known ovine placental permeabilities to water, glycerol and urea.

Identification of a novel SNF2/SWI2 protein family member, SRCAP, which interacts with CREB-binding protein

The ability of cAMP response-element binding protein (CREB)-binding protein (CBP) to function as a co-activator for a number of transcription factors appears to be mediated by its ability to act as a histone acetyltransferase and through its interaction with a number of other proteins (general transcription factors, histone acetyltransferases, and other co-activators). Here we report that CBP also interacts with a novel ATPase termed Snf2-Related CBP Activator Protein (SRCAP). Consistent with this activity, SRCAP contains the conserved ATPase domain found within members of the Snf2 family. Transfection experiments demonstrate that SRCAP is able to activate transcription when expressed as a Gal-SRCAP chimera and that SRCAP also enhances the ability of CBP to activate transcription. The adenoviral protein E1A was found to disrupt interaction between SRCAP and CBP possibly representing a mechanism for E1A-mediated transcriptional repression.

Serum cortisol concentrations during low dose dexamethasone suppression test to screen for Cushing's syndrome

Forty four subjects (23 obese controls, 11 patients with possible Cushing's syndrome, and 10 patients with definite Cushing's syndrome) underwent low dose (0 X 5 mg every six hours for two days) dexamethasone suppression tests during which serum cortisol concentration at 0800 and excretion of urinary free cortisol over 24 hours were measured. Serum cortisol concentration fell to below 60 nmol/1 (2 X 2 micrograms/100 ml) in 31 subjects and remained above 250 nmol/1 (9 X 1 micrograms/100 ml) in the 13 others. Excretion of urinary free cortisol showed a similar response, falling to below 110 nmol (40 micrograms)/24 h in 31 and remaining above 180 nmol (65 micrograms)/24 h in the 13 others. There was complete concordance between the two variables in terms of the pattern of response. Serum cortisol concentration fell to below 60 nmol/1 (2 X 2 micrograms/100 ml) in at least 97% (31 of a possible 32) of subjects without Cushing's syndrome. On the other hand, a serum cortisol concentration of above 250 nmol/1 (9 X 1 micrograms/100 ml) after low dose dexamethasone gave a false positive diagnosis of Cushing's syndrome in at most only one of 13 patients (7 X 7%). Measurement of serum cortisol concentration during the low dose dexamethasone test is simpler than, and as accurate and reliable as, measurements of urinary steroids.

Postoperative chemotherapy in children less than 4 years of age with malignant brain tumors: promising initial response to a VETOPEC-based regimen. A Study of the Australian and New Zealand Children's Cancer Study Group (ANZCCSG)

PURPOSE

Postoperative chemotherapy with indefinite postponement of radiation therapy in children < 4 years old with brain tumors was investigated in a multi-institutional study.

PATIENTS AND METHODS

From 1991 to 1995, 42 patients aged 3 to 47 months (median 20) with brain tumors were enrolled in a 2-phase chemotherapy protocol: 16 patients had medulloblastoma (MB); 8 had supratentorial primitive neuroectodermal tumor (PNET); 14 had ependymoma; and 4 had other tumors. The initial phase was comprised of 4 courses of the 3-drug regimen: vincristine (VCR), etoposide (VP-16), and intensive cyclophosphamide (CPA) in a previously reported schedule (VETOPEC). The continuation phase was comprised of 2-drug courses: A, CPA + VCR; B, cisplatin + VP-16; and C, carboplatin + VP-16, for a total duration of 64 weeks.

RESULTS

Response to VETOPEC was evaluable in 28 patients with postresection residual (25) and/or metastatic (1 M2, 6 M3) tumor. There were 9 complete responses (CR) and 9 partial responses (PR) with a combined CR + PR of 64% (95% confidence interval [CI] 44 to 81). In 12 evaluable patients with MB, CR + PR was 82% (48 to 98); in 6 patients with PNET, 50% (12 to 88); and, in 8 patients with ependymoma, 86% (42 to 99). Of 40 patients eligible for further analysis, 6 remain progression-free at a median of 30 months, 14 are alive at a median of 38 months, 29 have progressed at a median of 7 months (range, 2 to 37 months), and 26 have died. The progression-free and overall survival rates at 36 months are estimated to be 11% (95% CI 1 to 22) and 34% (18 to 50), respectively.

CONCLUSIONS

The initial response to the VETOPEC regimen is encouraging and warrants study of further dose escalation. Survival remains poor with current strategies in this high-risk population.

Altered expression of genes involved in regulation of vitamin A metabolism, solute transportation, and cytoskeletal function in the androgen-insensitive tfm mouse testis

Androgens are essential for the development and maintenance of spermatogenesis, but the underlying mechanisms of androgen action in the testis remain unclear. To help clarify these mechanisms, gene expression was measured in testes of pubertal (20 d old), androgen-insensitive, testicular feminized (Tfm) mice and in normal controls. Using microarrays (Affymetrix chips 430A and 430B), initial data identified a large number of genes down-regulated in the Tfm testis (>4700). These genes were largely of germ cell origin, reflecting the arrest of spermatogenesis that is apparent in the 20-d-old Tfm testis. Subsequent screening in vitro and in silico of this gene set identified 20 genes of a somatic tubular origin that were significantly down-regulated in the Tfm testis and six genes that were significantly up-regulated. Altered expression of these genes was confirmed by real-time PCR, and genes down-regulated in the Tfm testis were shown to be up-regulated in testes of hypogonadal (hpg) mice treated with androgen. In a developmental study using real-time PCR most of the regulated genes showed normal expression during fetal and neonatal development and deviated from control only between 10 and 20 d. In all cases, expression was also reduced in the adult, although interpretation is more complex because of the inherent cryptorchidism in the adult Tfm mouse. Of the total number of somatic genes showing differential expression in the Tfm testis, 50% were associated with three separate groups of genes involved in regulation of vitamin A metabolism, solute transportation, and cytoskeletal function. Thus, effects of androgens on tubular function and spermatogenesis may be mediated in part through regulation of the tubular environment and control of retinoic acid concentrations.

Involvement of cyclic nucleotides in prejunctional modulation of noradrenaline release in mouse atria

1 In mouse isolated atria previously incubated with [3H]-noradrenaline, 8-bromo-cyclic AMP (3-270 microM) produced a concentration-dependent increase in the fractional stimulation-induced outflow of radioactivity. 8-Bromo-cyclic GMP induced a lesser increase in the stimulation-induced outflow. 2 The phosphodiesterase inhibitors: M&B 22948 (90 microM); ICI 63197 (30 and 90 microM) and 3-isobutyl-1-methylxanthine (90 microM) increased the fractional stimulation-induced outflow. Together these results indicate that cyclic AMP may have a modulatory effect on noradrenaline release. 3 The inhibition of the stimulation-induced outflow produced by clonidine (0.03 microM) and its facilitation produced by phentolamine (1 microM) were unaltered in the presence of 8-bromo-cyclic AMP (90 microM). However, in the presence of 8-bromo-cyclic AMP (270 microM), the facilitatory effect of phentolamine was enhanced, but the inhibitory effect of clonidine (0.03 microM) was unaltered. In the presence of ICI 63197 (30 microM) the inhibitory effect of clonidine (0.03 microM) was unaltered, but the facilitatory effect of phentolamine (1 microM) was slightly enhanced. 4 Isoprenaline (0.003-0.1 microM) enhanced the fractional stimulation-induced outflow, an effect blocked by propranolol (0.1 microM). In the presence of 8-bromo-cyclic AMP (90 microM), the facilitatory effect of isoprenaline (0.01 microM) was blocked. In the presence of ICI 63197 (30 microM) the facilitatory effect of isoprenaline (0.003 microM) was potentiated. 5 These results suggest that whereas beta-adrenoceptor-mediated enhancement of noradrenaline release is linked to the stimulation of adenylate cyclase and enhanced formation of cyclic AMP, alpha-adrenoceptor-mediated inhibition of noradrenaline release is not linked to inhibition of adenylate cyclase activity.

Oropharyngeal dysphagia in esophageal cancer before and after transhiatal esophagectomy

Although dysphagia is the predominant symptom of esophageal cancer, the nature of the swallowing deficit remains unclear, particularly regarding an oropharyngeal motor component. The present study examined the oropharyngeal swallow in patients with esophageal cancer before and following transhiatal esophagectomy. Videofluoroscopic data were obtained from ten patients with esophageal cancer before and following transhiatal esophagectomy as they swallowed 2-, 5-, and 10-cc aliquots of liquid and puree, and 0.5 and 1 tsp of solid. Each swallow was rated on 36 parameters by three independent judges. Swallow-related hyoid bone movement, computed from digitized segments of the videofluoroscopic data, was compared pre- and postsurgically. All patients showed at least mild abnormality of the oropharyngeal swallow preoperatively. Abnormalities involved all stages of swallowing in nine of the ten patients; however, the oral preparatory/oral stage was relatively more impaired than the pharyngeal stage in the majority of patients. Postsurgically, all patients exhibited at least a mild oropharyngeal swallowing impairment. New or increased postoperative deficits involved the pharyngeal stage of swallowing, whereas oral stage abnormalities were generally improved or unchanged following surgery. Swallow-related hyoid kinematics were highly variable both before and following surgery. Anterior hyoid bone excursion was significantly reduced postoperatively in one patient and significantly increased in one patient. Patients with esophageal cancer exhibit oropharyngeal dysphagia, with different profiles of abnormality before and following esophagectomy.

Toxicological effect of engineered nanomaterials on the liver

The liver has a crucial role in metabolic homeostasis, as it is responsible for the storage, synthesis, metabolism and redistribution of carbohydrates, fats and vitamins, and numerous essential proteins. It is also the principal detoxification centre of the body, removing xenobiotics and waste products by metabolism or biliary excretion. An increasing number of studies have shown that some nanomaterials (NMs) are capable of distributing from the site of exposure (e.g. lungs, gut) to a number of secondary organs, including the liver. As a secondary exposure site the liver has been shown to preferentially accumulate NMs (>90% of translocated NMs compared with other organs), and alongside the kidneys may be responsible for the clearance of NMs from the blood. Research into the toxicity posed by NMs to the liver is expanding due to the realization that NMs accumulate in this organ following exposure via a variety of routes (e.g. ingestion, injection and inhalation). Thus it is critical to consider what advances have been made in the investigation of NM hepatotoxicity, as well as appraising the quality of the information available and gaps in the knowledge that still exist. The overall aim of this review is to outline what data are available in the literature for the toxicity elicited by NMs to the liver in order to establish a weight of evidence approach (for risk assessors) to inform on the potential hazards posed by NMs to the liver.

A novel homozygous mutation of the myelin Po gene producing Dejerine-Sottas disease (hereditary motor and sensory neuropathy type III)

We have previously reported that heterozygosity for myelin Po gene mutations were associated with Charcot-Marie-Tooth disease type 1B (CMT1B) or Dejerine-Sottas disease. We investigated the Po gene in a family with clinical Dejerine-Sottas disease and found two children were homozygous for a deletion of Phe 64. The parents were heterozygous first cousins with subclinical CMT1B and slow nerve conduction velocities. These results suggest that the effect of homozygous Phe 64 deletion on impairment of myelination is dosage-dependent. Clinical phenotype and/or myelin impairment may be determined both by the type of mutation and by the dosage of mutated gene.

Identification of developmentally regulated genes in the somatic cells of the mouse testis using serial analysis of gene expression

To identify genes developmentally regulated in the somatic cells of the testis, serial analysis of gene expression (SAGE) has been used to generate gene expression profiles from these cells in the fetal and adult mouse. To avoid germ cell transcripts, a fetal SAGE library was generated from germ cell-free fetal Wv/Wv mice, and an adult SAGE library was generated from adult testes depleted of germ cells with busulfan. The combined SAGE libraries contained 147570 tags identifying 12976 unique transcripts. Of these transcripts, 3607 were present in only the fetal library and 3941 were present in only the adult library. Most of the abundant differentially expressed tags in the adult testis library were from characterized genes, whereas 3' rapid amplification of complementary ends was required to identify most differentially expressed tags in the fetal library. These fetal tags were mostly associated with uncharacterized UniGene clusters. These data provide a comprehensive and quantitative analysis of gene expression in the somatic cells of the fetal and adult testis (including unknown transcripts) and identify genes differentially expressed in these cells during testis development. These differentially regulated genes are likely to provide insight into mechanisms regulating testis function both during development and in the adult animal.

Prejunctional beta-adrenoceptors in rabbit pulmonary artery and mouse atria: effect of alpha-adrenoceptor blockade and phosphodiesterase inhibition

In rabbit isolated pulmonary artery previously incubated with [3H]-noradrenaline, isoprenaline (0.3 microM) had no effect on the stimulation-induced outflow of radioactivity. However, if the phosphodiesterase inhibitor ICI 63,197 (30 microM) or the alpha-adrenoceptor blocker phentolamine (1 microM) was present, then isoprenaline significantly enhanced the stimulation-induced outflow, an effect blocked by propranolol (0.1 microM). ICI 63,197 (30 microM) but not phentolamine significantly enhanced the stimulation-induced outflow of radioactivity. In mouse isolated atria previously incubated with [3H]-noradrenaline and stimulated at a frequency of 10 Hz, isoprenaline had no effect on the stimulation-induced outflow of radioactivity; this is in contrast to its release-enhancing effects at stimulation frequencies of 4 Hz and 2 Hz. The facilitation of stimulation-induced outflow by isoprenaline at 4 Hz was blocked by propranolol (0.08 microM) which, by itself, had no effect on the stimulation-induced outflow. At a stimulation frequency of 2 Hz in mouse atria the facilitatory effect of isoprenaline (0.01 microM) was significantly greater in the presence of ICI 63,197 (30 microM) which, by itself, had no effect on the stimulation-induced outflow. Similarly, the facilitatory effect of isoprenaline was significantly greater in the presence of phentolamine (1 microM) but, in this case, phentolamine significantly enhanced the stimulation-induced outflow. These results suggest that facilitatory prejunctional beta-adrenoceptors are present in both rabbit pulmonary artery and mouse atria. The effects of the phosphodiesterase inhibitor ICI 63,197 suggest that they are linked to adenylate cyclase in both tissues and we propose that the ability of phentolamine to facilitate the release and enhance the effect of isoprenaline may be due to the blockade of alpha-adrenoceptor inhibition of adenylate cyclase. This latter proposition needs further investigation.

Antipicornavirus activity of substituted phenoxybenzenes and phenoxypyridines

Phenoxybenzenes and phenoxypyridines were prepared and tested for the effect of substituents on antipicornavirus activity. The most active compound, 2-(3,4-dichlorophenoxy)-5-nitrobenzonitrile (8), demonstrated broad-spectrum antipicornavirus activity. Compound 8 and several analogues each given orally prior to and during infection protected mice against an otherwise lethal challenge with coxsackievirus A21.

Newly recognized vital nitrogen cycle

Soil and sea bacteria produce a small amount of nitrous oxide (N(2)O); a small part of this N(2)O is photochemically converted to nitric oxide (NO) in the stratosphere. This process has recently been shown to be the principal source of the active oxides of nitrogen (NO and NO(2)) in the stratosphere. The active oxides of nitrogen catalytically destroy ozone, and NO and NO(2) appear to be a principal factor in the natural ozone balance. Stratospheric ozone is the only effective shield for the surface of the Earth against the harsh ultraviolet radiation between 300 and 250 nm. Thus, soil bacteria indirectly control the intensity of ultraviolet radiation reaching the Earth's surface. This subcycle of the major nitrogen cycle involves a relatively small amount of nitric oxide, estimated to be between 0.26 and 1.2 x 10(9) kg of NO per year on a worldwide basis. A recent estimate of the future nitric oxide emission in the stratosphere by the Concord supersonic transport is 0.37 x 10(9) kg/year on a world-wide basis, which is similar to the amount estimated from the natural source.