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Notes: Summary Retinoids are known to modulate sebaceous gland activity in humans and animals. The nonpolar arotinoid Ro 15-0778 [(E)-1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-(1-methyl-2-phenylethenyl) naphthalene] does not contain a polar end group and is devoid of the classical retinoid side effects of hypervitaminosis A. The favorable toxicological profile stimulated the evaluation of this arotinoid in animal models of sebum production. In castrated, testosterone-stimulated male rats, Ro 15-0778 is 50 times more potent than 13-cis-retinoic acid in inhibiting the production and subsequent secretion of sebum. The oral ED50 value of Ro 15-0778 is 30μg/kg, while an oral dose of 0.5 mg/kg inhibited sebum secretion nearly 1005. In testosterone-stimulated female rats, Ro 15-0778 inhibits sebum secretion significantly with an oral ED50 of 140 μg/kg and an s.c. ED50 of 75μg/kg. Ro 15-0778 was also evaluated for its ability to prevent testosterone induction of the immature hamster flank organ. The topical ED50 is 0.53 mg/kg and the oral ED50 is 38 mg/kg. This arotinoid is similarly active in mature male hamsters without testosterone treatment. In addition, the retinoid is active topically and orally in reducing the size of the gerbil abdominal sebaceous gland. The compound exhibits no antiandrogenic activity when tested in ventral prostrate and seminal vesicle assays in rats. Additionally, the compound does not have estrogenic activity when tested in the rat uterine weight assay. High doses of Ro 15-0778 in humans did not demonstrate significant sebumsuppressing activity. This study indicates that extra-polation of retinoid data from rodent animal models to activity in human sebaceous glands can not be made with a high degree of certainty. There is a need to develop new, more predictive models for retinoid activity.

Notes: Summary It has been suggested, based on animal experiments and limited human data, that the antihypertensive drug hydralazine might be carcinogenic, and among the sites of concern are the lung and colon. To assess the possible relationship between the use of hydralazine and lung and colorectal cancers in humans, we compared 1006 cases of lung cancer with 3531 hospital control subjects, and 972 cases of colorectal cancer with 3276 controls. Data were collected by interview in hospitals in the United States and Canada. Overall, 1.1% of the lung cancer cases, 1.6% of the colorectal cancer cases, and 1.5% of the controls had used hydralazine. Compared with those who had never used hydralazine, the relative risk estimate of lung cancer for those who first took the drug at least 18 months before hospital admission was 1.1 (95% confidence interval 0.4–2.9). The estimate for use for at least 1 year was 1.4 (0.5–3.8) and for use for at least 5 years the estimate was 0.9 (0.2–4.3). The corresponding relative risk estimates for colorectal cancer were 1.2 (0.5–2.5) for any use, 1.7 (0.8–3.7) for use for at least one year, and 2.4 (0.8–6.9) for five or more years of use. Other antihypertensive treatments and risk factors, including cigarette smoking in the analysis of lung cancer, were taken into account in these estimates. Although the effect of use after long latent intervals could not be evaluated, the results provide no support for the hypothesis that hydralazine use increases the risk of lung cancer. There is also no evidence that hydralazine increases the risk of colorectal cancer, but an effect after extended durations of use cannot be ruled out.

Notes: The high-affinity uptakes of [3H]serotonin, [3H]-glutamate, and γ-[3H]aminobutyric acid were studied using a myelin-free crude synaptosomal fraction prepared from the spinal cords of normal dogs and spastic dogs following sham treatment or dorsal bilateral rhizotomy surgery. Compared to sham-operated controls, rhizotomy surgery of normal dogs produced, after 1 week, a 30% reduction in the Vmax value of [3H]glutamate, but did not alter the uptake of γ-[3H]aminobutyric acid. This treatment also produced a 60% decrease in the Vmax value of [3H]serotonin. Comparison of the effect of rhizotomy surgery on normal and spastic dogs revealed that the spastic group had 60% higher Vmax values for uptakes of [3H]glutamate and γ-[3H]aminobutyric acid. Comparison of sham-operated spastic dogs and rhizotomy-treated spastic animals showed that there was a 25% decrease in the uptake of both amino acids in the rhizotomy-treated spastic group. Overall, the data (a) support the hypothesis that glutamate is the neurotransmitter from some of the primary afferents, and (b) suggest that sprouting of interneuronal amino acid transmitter systems may occur in the spinal cords of spastic dogs.

Notes: Background Frequent infection in infancy and early childhood has been hypothesized to explain the low prevalence of asthma and other atopic disease among children in developing countries (the so-called ‘hygiene hypothesis’), but the low prevalence in Eastern Europe remains unexplained.Objective To test the hygiene hypothesis in the Republic of Belarus by examining the relationship between gastrointestinal (GI) and respiratory infection and two potentially atopic outcomes in the first 12 months of life: atopic eczema and recurrent wheeze.Methods We carried out two case–control studies nested within a large (n=17 046) randomized trial in Belarus, with cases defined as (1) first occurrence of atopic eczema (n=819) and (2) second episode of wheezing (n=112). Incidence density sampling was used to select four matched controls born within 1 month at the same hospital as the case. Exposure was defined as one or more episodes of GI or respiratory infection (examined separately) with onset 〉7 days before onset of the case's atopic outcome. Analyses controlled for family atopic history, duration of exclusive breastfeeding, sex, birth weight, maternal education, and (for recurrent wheeze) maternal smoking.Results For atopic eczema, prior GI infection occurred in 7.4% of cases vs. 6.0% of controls [adjusted OR=1.27 (0.94–1.72)] and prior respiratory infection in 35.2% vs. 32.6% [adjusted OR=1.14 (95% CI=0.94–1.37)]. For recurrent wheeze, prior GI infection occurred in 9.8% of cases vs. 7.4% of controls [adjusted OR=1.30 (0.60–2.82)].Conclusion Our results do not support the hypothesis that infection protects against atopic eczema or recurrent wheezing in the first 12 months of life.

Notes: We have performed inelastic neutron scattering study of the cerium γ↔α valence transition (T0(approximately-equal-to)150 K) in polycrystalline Ce0.74Th0.26 at the Intense Pulsed Neutron Source (IPNS) of Argonne National Laboratory. An incident neutron energy of 300 meV was used to measure the excitation energy spectra of Ce0.74Th0.26 at 100, 140, 155, and 200 K by chopper spectrometers. By comparing the neutron total scattering of Ce0.74Th0.26 with that of La0.74Th0.26, an isostructural nonmagnetic alloy measured under idential experimental conditions, the magnetic scattering function of Ce0.74Th0.26 averaged over all q in the Brillouin zone, Savemag (Q,E), is derived. We find that the magnetic response of Ce0.74Th0.26 at all temperatures is predominately due to moments of 4f character. The obtained magnetic scattering function in this temperature region consists of a broad quasielastic peak, which is well fitted by a spin relaxational spectral function, namely, a Lorentzian centered at 0 energy. The peak shifts to higher energies and broadens as the temperature is lowered. As the temperature decreases across the transition temperature, the magnetic intensity drops sharply, accompanied by an abrupt broadening of the linewidth corresponding to a spin fluctuation energy much higher than the thermal energy. Γ, the Lorentzian HWHM's, were found to be 16, 25, 63, and 110 meV at T=200, 155, 140, and 100 K, respectively. Within experimental precision, we find no evidence of additional inelastic peaks due to crystal-field excitations. These results are in good agreement with those from an earlier neutron experiment1 using thermal-energy neutrons in which the measured spectra were limited to about 70 meV. The static single-site susceptibility obtained by a Kramers–Kronig analysis agrees well with the bulk susceptibility.1 The 4f occupation per Ce atom, deduced by summing theneutron data from −100 to 230 meV, is about 0.6 and 0.4 for the γ and α phase, respectively. These values are considerably smaller than those obtained from photoemission2 and other measurements.1 This indicates that the neutron experiment did not extend to high enough energies to account for all the intensity. In the high-temperature γ phase the relaxational model represents a reasonable approximation to the spin dynamics. By integrating the Lorentzian scattering function obtained from the fits of the neutron data over an energy interval of −0.1 to 2 eV, we obtained an f occupancy close to unity in the γ phase. For the α phase there is currently no analytical expression of the magnetic scattering function from first-principle calculations. Model calculations3,4 of the ground state (T=0) for a single f impurity in the metal, on the other hand, predicts a magnetic response function having a thresholdlike rise at a finite energy, followed by a long tail extending to high energies. In order to be able to compare with the theory, we have also undertaken the measurements of the magnetic scattering function of Ce0.74Th0.26 at 10 K with an incident neutron energy of 1.2 eV. We find that Savemag shows an inelastic peak at about 138 meV and a tail at higher energies. The line shape of the measured spectrum agrees qualitatively with the single-impurity theory3,5,6 and the result of a recent polarized neutron study7 of α-Ce. By summing the measured magnetic intenstiy up to 500 meV, we estimated a 4f occupancy of 0.76 per Ce atom. The static susceptibility at 10 K and the electronic specific heat coefficient obtained from the neutron data and the theory3,8 agree well with the values obtained from bulk measurements.1,9,10 The above results are also in fair agreement with the electronic spectroscopy data.2 Since the neutron measurements were made using polycrystalline samples, we are unable to detect, if any, coherence effects6,11 due to interaction of the f electrons in the lattice. A detailed report on the inelastic neutron scattering investigations is presented elsewhere.12

Notes: Neutron-spin-echo (NSE) experiments were performed on polycrystalline samples of EuxSr1−xS for x=0.4 and 0.54 in the temperature range of 1.2〈T〈10 K and for 0.036〈Q〈0.18 A(ring)−1. The x=0.4 sample exhibits a paramagnetic (PM) to spin-glass (SG) transition near Tg ∼2 K. In the x=0.54 sample, large ferromagnetic correlations develop below 5 K and a SG state appears at lower temperatures. In the NSE experiment, the spin-spin correlation function S(Q,t) is measured directly for times between 0.03〈t〈5 nsec. At low temperatures, both materials exhibit a weak Q dependence in the dynamics and the spins are essentially frozen over the time range explored. On heating the x=0.4 sample, the spins start to fluctuate more rapidly, but no dramatic change occurs around Tg. On heating the x=0.54 sample, S(Q,t) decreases rapidly with time. Near 5 K, S(Q,t) is exponential (e−Γt) with Γ being strongly Q dependent. Measurements of the depolarization of the scattered beam confirms the absence of true long-range ferromagnetic order below Tc.

Notes: We report an inelastic neutron scattering study of the uniaxial dilute antiferromagnets Fe1−xMgxCl2, for x=0.3, 0.45, and 0.6. The first two samples have long-range antiferromagnetic (AF) order. Their spin-wave peaks are broadened by the exchange fluctuations. The x=0.6 sample orders like an Ising spin glass with a very short AF correlation length (ξ≈10 A(ring)). For wavelength λ(approximately-less-than)ξ, spin wave peaks are similar to the dilute antiferromagnets, but for λ(approximately-greater-than)2ξ, the peak sharpens up and becomes resolution limited at the zone center. We give a simple explanation for this behavior.

Notes: Neutron scattering experiments have been performed on a spin-glass CuMn (5 at. %, Tg =27.6 K). Polarized neutron measurements with coarse energy resolution show no change of instantaneous spatial spin correlation below T=60 K. Unpolarized neutron studies with fine energy resolution (ΔE=260 μeV) demonstrate that the slowing down of Mn spin fluctuations occur in the same way for all the wave vectors between 0.2 and 4.0 A(ring)−1. These results indicate that the spatial and dynamic spin correlations are completely decoupled in the spin freezing process. We also study the short-range spatial correlation of the "frozen'' spins at T=5 K using a simple model, and demonstrate the importance of the ferromagnetic coupling between the third nearest-neighbor Mn moments.

Notes: Fe1−xMgxCl2 is a diluted Ising antiferromagnet with competing first- and second-neighbor exchange interactions. For x≈45, the system undergoes a Néel transition at TN ≈7.4 K and a reentrant spin-glass transition at Tsg ≈3.0 K. From neutron scattering experiments we find that (i) the antiferromagnetic Bragg peak persists down to 1.2 K, well below Tsg; and (ii) the diffuse scattering becomes temperature independent below about 6.0 K, with the correlation length frozen at about 2.8 lattice spacings. These results suggest that long-range antiferromagnetic order and spin-glass-like short-range order coexist. Such a behavior is predicted by the infinite-range model for spin glasses with strong uniaxial anisotropy.