Sexual orientation, use of drugs and risk perception among HIV-positive men in Sao Paulo, Brazil.

The aim of this cross-sectional study, carried out among 250 HIV-positive (HIV+) men who have sex with women, was to describe their risk perception before learning of their HIV+ status and their sexual and drug use behaviour. Of the 250 men, 62.0% were heterosexuals and 38.0% where bisexuals. They most often reported becoming infected through unprotected sex (24.5%) and injecting drug use (11.0%). They were usually tested because they became ill (42.2%). Condom use with women in all episodes of sexual intercourse before HIV+ diagnosis was reported by 22.6% of heterosexuals and 34.7% of bisexuals (P < 0.05). With respect to drug use, 58.0% reported the use of drugs at some period in their lifetime. A higher proportion of individuals who had used drugs perceived themselves at risk (P < 0.05). Findings showed that most HIV+ men who have sex with women, regardless of sexual orientation or injecting drug use, did not use condoms and did not perceive themselves at risk before learning of their HIV+ status, and only undergo testing due to illness. The implications for heterosexual transmission of HIV are discussed.

Analysis of the Interacting Octad System of (12)CH(4).

The octad system of methane (12)CH(4) has been analyzed with a fourth-order (459 parameters) Hamiltonian for energy levels and a third-order (28 parameters) dipole moment expansion for infrared intensities. Nearly 8000 assigned positions and 2500 measured line intensities (obtained with the Fourier transform spectrometer located at Kitt Peak National Observatory/National Solar Observatory) have been considered in the modeling. Infrared (Octad-Ground State) and hot bands (Octad-Dyad) data have been used. While the model does not reproduce the measurements at their inherent experimental precisions, it has been sufficient to interpret and substantially assign this spectral region of methane for the first time in over 30 years of investigation. Copyright 2001 Academic Press.

High-Quality Brewster's Angle Polarizer for Broadband Infrared Application.

We have designed and constructed a linear polarizer for use with visible and infrared radiation. The broadband polarizer consists of four germanium plates arranged in a chevron geometry. Input radiation is incident near Brewster's angle for the first plate such that the reflected beam is preferentially s-wave polarized. This reflected beam is steered subsequently to the successive plates, always intersecting near Brewster's angle. The beam polarization at the output of the device is almost completely s-wave polarized. The ratio of the paraxial flux of the nearly extinguished p-wave polarized light to the s-wave polarized light transmitted through the device is found to be less than 10(-5) for laser illumination at wavelengths of 0.633, 1.32, 3.39, and 10.6 mum. Calculations predict that extinction ratios less than 10(-5) are achievable over the wavelength range from 0.4 mum to beyond 500 mum. Alternative design geometries involving fewer plates are also described along with their advantages and disadvantages.

Maternal protein reserves and their influence on lactational performance in rats. 4. Tissue protein synthesis and turnover associated with mobilization of maternal protein.

The present study was undertaken to investigate the changes in muscle protein turnover involved in the rapid mobilization of protein in rats subjected to severe protein restriction during lactation. Estimates of mammary gland and liver protein synthesis were also made during lactation. Multiparous female Sprague-Dawley rats, caged individually following mating, were offered a high-protein diet (H; 215 g crude protein (N x 6.25; CP)/kg dry matter (DM)) ad lib. until parturition. Following parturition, half the females continued to receive diet H, whilst the remainder were offered a diet low in protein (L; 90 g CP/kg DM) ad lib. On days 2, 4, 8 and 12 of lactation, groups of females were used in the estimation of tissue protein synthesis (flooding dose of [3H]phenylalanine) immediately after a milk sample had been obtained. Rates of muscle protein synthesis were unchanged during lactation in group H. The feeding of diet L during lactation reduced the muscle protein synthesis on day 12 to rates that were lower than group H and also the rate on diet L on day 2 (P < 0.01). However, this fall in muscle protein synthesis was not rapid and muscle fractional synthesis rate (FSR) was different from group H only from day 8 (P < 0.05). Estimated rates of mammary protein synthesis appeared to be generally unchanged by dietary treatment or stage of lactation. Liver FSR was also unchanged by dietary protein supply or stage of lactation. The effect of dietary protein restriction on liver size and protein content during lactation influenced liver absolute synthesis rate (ASR), and on days 8 and 12 of lactation liver ASR was lower in group L than in group H (P < 0.001). The loss of muscle protein in rats fed on diet L during lactation (133 mg) occurred mainly between days 2 and 8 of lactation and was primarily associated with a dramatic increase in degradation (13.0% per d), with the decline in synthesis having a much smaller role. A decline in muscle protein degradation during the latter half of lactation was part of the mechanism that prevented excessive muscle protein catabolism. It is thought that the estimation of mammary protein synthesis in the present study was impaired by the milk sampling procedure previously used.

Maternal protein reserves and their influence on lactational performance in rats. 3. The effects of dietary protein restriction and stage of lactation on milk composition.

The effects of severe protein restriction following parturition on the changes in rat milk composition during lactation were investigated using multiparous female Sprague-Dawley rats caged individually following mating and offered a high-protein diet (H; 215 g crude protein (N x 6.25; CP)/kg dry matter (DM)) ad lib. until parturition. Following parturition, half the females continued to receive diet H, whilst the remainder were offered a diet low in protein (L; 90 g CP/kg DM) ad lib. On days 2, 4, 8 and 12 of lactation groups of females from both dietary treatments were used to provide a milk sample. Milk samples were analysed for their lactose (enzymically), protein (binding to Coomassie blue), lipid (gravimetrically) and mineral (spectrophotometrically) contents. The milk lactose concentration of group H increased with stage of lactation (r2 0.85, P < 0.001). Such an increase was prevented by diet L, and from day 8 of lactation the milk lactose of group L was lower (P < 0.05) than in group H. Group H milk protein concentration did not change during lactation and averaged 90.7 mg/g. Dietary protein restriction reduced the milk protein concentration of group L so that on days 2, 4 and 12 of lactation it was lower (P < 0.05) than that of group H. On day 8 of lactation the milk protein concentration of group L had increased (P < 0.05) and was comparable with that of group H. For group H, milk lipid averaged 166.8 mg/g and was generally unchanged during lactation. Diet L increased (P < 0.01) the milk lipid concentration (205.5 mg/g) compared with diet H and this was also significant on days 4 and 8 of lactation (P < 0.05). Group L milk lipid concentration also increased between days 4 and 8 of lactation (P < 0.05). Milk Na concentration declined during lactation in both dietary groups (P < 0.01) but was unaffected by dietary treatment. Both milk Ca and P concentrations increased (P < 0.01) during lactation in both dietary groups, whilst protein restriction also increased the Ca and P concentrations (P < 0.05). Milk K and Mg concentrations were unaffected by dietary treatment or stage of lactation. This significant alteration in the milk composition of severely protein-restricted dams, while possibly favouring the disposal of greater quantities of energy-yielding nutrients, suggests that equations developed for the estimation of milk production in rats cannot be used under such conditions.

Maternal protein reserves and their influence on lactational performance in rats. 2. Effects of dietary protein restriction during gestation and lactation on tissue protein metabolism and Na+, K(+)-ATPase (EC 3.6.1.3) activity.

Changes in tissue protein synthesis and an associated membrane transport system in rats were investigated during lactation and under conditions of dietary protein restriction. Following mating, female Sprague-Dawley rats (second parity) were caged individually and offered a high-protein diet (H; 215 g crude protein (N x 6.25; CP)/kg dry matter (DM)) ad lib. until day 12 of gestation. Subsequently half continued to receive diet H, whilst the remainder were offered a low-protein diet (L; 65 g CP/kg DM) until parturition. On day 1 of lactation females were then allocated to either diet H or another low-protein diet (L2; 90 g CP/kg DM) which were offered ad lib. until day 13 of lactation, giving four lactation groups HH, LH, HL2 and LL2. On days 1 and 13 of lactation groups of females were used in the estimation of tissue protein synthesis (flooding dose of [3H] phenylalanine) and Na+, K(+)-ATPase (EC 3.6.1.3) activity (polarographically) in skeletal muscle, mammary gland, liver and duodenal mucosa. By day 1 of lactation diet L had reduced fractional and absolute synthesis rates (FSR and ASR) of muscle protein (P < 0.05) and the O2 consumption associated with Na+, K(+)-ATPase, although not significantly (P < 0.10). Rates of protein synthesis in the other tissues studied were not affected on day 1 of lactation by the gestation dietary treatment. By day 13 of lactation the feeding of diet L2 had reduced muscle FSR and ASR of group HL2 to rates that were lower than those on day 1 (P < 0.05), comparable to those of group LL2 and lower than those of groups HH and LH (P < 0.05). Diet H had allowed group LH to increase their muscle protein synthesis compared with that on day 1 (P < 0.05). Muscle Na+, K(+)-ATPase activity on day 13 of lactation was also lower in groups offered diet L2 (P < 0.05). Mammary protein synthesis was increased during lactation with the feeding of diet H (P < 0.05), which was prevented by diet L2 such that rates of groups HL2 and LL2 were lower than those of the two high-protein groups on day 13 (P < 0.01). Mammary respiration and in particular Na+, K(+)-ATPase activity was increased during lactation by the feeding of diet H (P < 0.05). Rates of protein synthesis and respiration in liver and duodenal mucosa were not significantly affected by the gestational or lactational dietary treatments.(ABSTRACT TRUNCATED AT 400 WORDS)

Maternal protein reserves and their influence on lactational performance in rats.

To determine the contribution of tissue protein reserves to lactational performance, multiparous female Sprague-Dawley rats were mated, caged individually and offered a diet high in protein (215 g crude protein (N x 6.25; CP)/kg dry matter (DM); H) ad lib. until day 12 of gestation. Subsequently half the rats continued to receive diet H while the remainder were offered a diet low in protein (65 g CP/kg DM; L) until parturition. This treatment aimed to produce a difference in carcass protein at parturition. On day 1 of lactation females were allocated to either diet H or a low-protein diet (90 g CP/kg DM; L2) offered until day 13 of lactation, giving four lactation treatment groups HH, HL2, LH and LL2. Groups of females were slaughtered on days 2 and 12 of gestation and days 1 and 13 of lactation and carcass and major organs were analysed. Weight gain of standardized litters was used as an indicator of lactational performance. Maternal carcass protein contents at parturition were 43.5 (SE 1.2) and 38.7 (SE 0.8) g (P < 0.01) for diets H and L respectively. During lactation there was little change in carcass protein content of HH rats while LH rats appeared to replenish their depleted reserves. Food intake or lactational performance did not differ between these two groups. HL2 and LL2 rats lost carcass protein with HL2 rats losing more than LL2 rats (P < 0.05). Intake and lactational performance were reduced compared with that on diet H (P < 0.05) but for the first 6 d of lactation were both greater (P < 0.05) for diet HL2 than for diet LL2. All four groups showed a considerable loss of body fat during lactation which was not affected by diet. The ability of HL2 rats to catabolize more protein and consume more food allowed them to sustain a greater lactational performance. Previous maternal protein depletion had no influence on lactational performance as long as an adequate supply of dietary protein was provided.

Polarization-stabilized 1.15- and 3.39-microm He-Ne lasers.

Two methods for polarization stabilization of an internal-mirror 3.39-microm He-Ne laser are reported. The first relies on a concurrently lasing 1.15-microm transition by fixing the relative amplitude of two orthogonally polarized longitudinal modes that are split by a Rochon prism and detected with separate Si photodiodes. In the second method, two spatially separated orthogonally polarized adjacent 3.39-microm modes are optically balanced, differentially chopped, and recombined on a single InSb photodiode for phase-sensitive detection. The dual-wavelength scheme has been tested by beating against a methane-stabilized 3.39-microm He-Ne laser, which yields maximum excursions of < 0.5 MHz over several hours and comparable reproducibility. The polarization-stabilized He-Ne laser has been used as a reference for a tunable color-center laser molecular-beam optothermal spectrometer and provides a precision of better than 2 MHz.

Torsional Splittings and Assignments of the Doppler-Limited Spectrum of Ethane in the C-H Stretching Region.

The Doppler-limited absorption spectrum of the C-H stretching region of ethane has been recorded at T≃ 119 K with a tunable difference-frequency laser spectrometer. The strong torsional hot band structure at room temperature is eliminated at 119 K, and the enhanced resolution from the Doppler width reduction allows us to observe small torsional splittings. The two fundamentals in the region, v 7, a perpendicular band and, v 5, a parallel band have been essentially completely assigned as have a large number of transitions in the parallel component of the v 8 + v 11 combination band. A number of perturbations of both global and local nature have been observed. The complete spectrum and a listing of transition wavenumbers, intensities and assignments are presented here to facilitate identification and quantitative analysis of ethane in a variety of monitoring applications. Precise ground state rotational constants have been determined from combination differences.

Distribution and ultrastructural characteristics of dark cells in squamous metaplasias of the respiratory tract epithelium.

Dark epithelial basal cells were found in both carcinogen-induced and non-carcinogen-induced squamous metaplasias of the tracheal epithelium. Formaldehyde-induced squamous metaplasias exhibited 4% dark cells in the basal layer. Metaplasias induced by vitamin A deficiency and those induced by dimethylbenz(alpha)anthracene (DMBA) without atypia showed 18--20% basal dark cells. DMBA-induced metaplasias with moderate to severe atypia exhibited 50% basal dark cells. The labeling index of basal cells in metaplastic epithelia, regardless of the inducing agent, was 16--18%, ie, the same as that of the normal esophageal stratified squamous epithelium. The percentage of labeled dark basal cells per total dark cell population was approximately 19% in the non-carcinogen-induced metaplasias and in the DMBA-induced metaplasias without atypia. In the atypical metaplasias induced by DMA this percentage increased to 26. On the basis of ultrastructural observations, five types of dark epithelial cells could be distinguished in the metaplastic epithelia: Type I (ovoid or fusiform dark cell with abundant cytoplasmic filaments, desmosomes, and free ribosomes--dark keratinocyte type); Type II (ovoid or spherical small cell with scant cytoplasm with few organelles--basal respiratory type); Type III (irregular or ovoid, few cytoplasmic filaments and organelles and desmosomes, extremely abundant free ribosomes--dedifferentiated type); Type IV (fusiform or ovoid, large mitochondria, prominent ergastoplasm, secretion droplets--mucous cell type); and type V (irregular shape, organelle remnants, vacuoles, pyknotic nuclei--involutional-cell type). Type I was the predominant cell type in formaldehyde-induced metaplasias and was also commonly seen in DMBA-induced metaplasias without atypia. Type II predominated in metaplasias induced by vitamin A deficiency. Type III was seen in DMBA-induced metaplasias and was the predominant cell type in the atypical epithelial alterations. Type IV cells occurred only in the latter, and Type V cells were occasionally seen in formaldehyde- as well as in DMBA-induced atypical metaplasias. Each type of squamous metaplasia could thus be recognized by a determined numerical distribution of dark cells in the basal layer and a specific pattern of distribution of the ultrastructurally defined dark cell categories.

nu(3) vibrational ladder of SF(6).

From an analysis of the high-resolution spectrum of the 3nu(3) manifold of SF(6) , we have determined the anharmonicity constants to be (in reciprocal centimeters) X(33) =-1.7426, G(33)=0.9188, and T(33) = -0.24635. By using these constants, one can for the first time to our knowledge accurately predict the energies of the lower-vibrational sublevels of the nu(3) ladder and determine the pathways for multiple-photon absorption.

Reestablishment of a mucociliary epithelium in tracheal organ cultures exposed to retinyl acetate: a biochemical and morphometric study.

Tracheal explants derived from vitamin A-deficient rats underwent keratinizine squamous metaplasia in organ culture when grown in serum-free medium. Within 1 d after the addition of 0.1, 2, or 10 microgram retinyl acetate per ml of medium, there was a concentration-dependent increase in the uptake of [3H]glucosamine and [14C]serine into both the total mucous glycoprotein and the principal purified mucin fraction eluted from a DEAE-Sephacel column with 0.2 M NaCl. The stimulation of mucin synthesis continued throughout the 21-d exposure period in a concentration-dependent fashion. It was also found that vitamin A had a greater effect on the incorporation of [3H]glucosamine than on [14C]serine into the secreted mucins, particularly at the higher retinyl acetate concentrations. This result indicated a greater effect of the vitamin on the synthesis of the carbohydrate moiety of the mucins. Morphological analysis by light and electron microscopy demonstrated that the keratinizing squamous epithelium began to revert to a mucus-secreting tissue as early as 24 h after addition of 10 microgram retinyl acetate to the medium. The response was slower with the lower vitamin concentrations. Stereological analysis revealed that the increase in the volume fraction of the Golgi apparatus reached a stable level which could not be altered with continued exposure to retinyl acetate, but that the volume fraction of mucin droplets continually increased and apparently did not reach a maximum in the 21-d exposure period. Conversely, the volume fraction of filament bundles and the number of desmosomes decreased during the vitamin A treatment.

Cutaneous manifestations in rats with advanced vitamin A deficiency.

Specific-pathogen-free rats kept on a vitamin A-deficient diet for approximately 5 months developed cutaneous alterations, especially in the periorbital and eyelid skin. These lesions were characterized grossly by erythema, partial alopecia, and crusting, and histologically by hyperorthokeratinization, acanthosis, and a three-fold increase in incorporation of labeled DNA precursors into the epidermal basal layer. Electron microscopy showed an increased number of Langerhans cells with and without Birbeck granules, as well as the presence of cytoplasmic dense bodies of probable lipid nature in keratinocytes of all epidermal strata. The similarities of these ultrastructural alterations with some features of vitamin A-sensitive human dermatoses point to probable common mechanisms in the pathogenesis of these skin diseases.

Deconvolution of infrared spectra beyond the Doppler limit.

It is shown that the deconvolution method of Van Cittert can be used reliably to enhance the effective spectral resolution by a factor of ~3 with data that exhibit a high SNR (~10(3)) and in which base line variations have been eliminated. Deconvolution of a Doppler-limited spectrum of C(6)H(6) measured on a difference-frequency laser system yielded linewidths of ~1.2 x 10(-3) cm(-1) (compared with the Doppler width of 3.6 x 10(-3) cm(-1) at 203 K). Extensive reliability tests of the deconvolution technique have been performed.

Linear scan control of tunable lasers using a scanning fabry-perot.

A simple technique is described for servo control of the scan rate and drift of tunable cw lasers based on peak position readout in a repetitively swept Fabry-Perot interferometer referenced to a stabilized laser.