Bio-based carbonaceous composite materials from epoxidised linseed oil, bio-derived curing agent and starch with controllable functionality

Fully bio-derived thermoset composites were synthesised from epoxidised linseed oil, bio-derived curing agent and starch with controllable functionality (Starbon ®).

Exploring the gap: community pharmacists' perceptions of their current role compared with their aspirations

Objective

To investigate community pharmacy managers' perceptions of their role in providing health care to patients and to compare these with their aspirations for the future.

Method

Fourteen pharmacist managers from one regional area of a UK national multiple pharmacy chain participated in two focus groups.

Key findings

Participants voiced a shared vision of wanting to play a more integral part in the health care of patients. Strategies put forward to embrace a more participative role included delegation of health screening and minor illness clinics from the prescriber to the pharmacist, having more formalised and open channels of communication with prescribers and moving away from performing technical duties, such as the physical assembly of medicines. Participants in both groups showed awareness that apathy and inaction would result in potential opportunities for pharmacy to be lost or passed over to another profession within the primary health care team (PHCT). Two key external obstacles that currently prevented attainment of desired roles were identified: first, a lack of awareness among other health care professionals and the general public about the pharmacist's skills and attributes and, secondly, current UK legislation that limits the potential for community pharmacists to expand their role away from the pharmacy premises.

Conclusions

Participants believed that they could provide a more comprehensive pharmaceutical service if given the chance. However, they believed that implementation of change would be difficult considering the obstacles that needed to be surmounted for change to occur.

Family health services authorities and community pharmacists at the purchaser-provider interface

The views of both purchasers (family health services authorities [FHSAs]) and providers (community pharmacists) were sought on the development of community pharmaceutical services in the light of the 1992 pharmaceutical care report. Questionnaires were posted to the 480 pharmacists in charge of all community pharmacies in Wessex and to the 98 general managers of FHSAs in England and Wales. The questionnaires focused on reactions to those recommendations of the pharmaceutical care report which, if implemented, would have significant implications for the community pharmacist's workload. Both the FHSAs and community pharmacists indicated that, in their view, the skills of the community pharmacist are currently underutilised. Both groups expressed enthusiasm for the pharmaceutical care report recommendations that the following services should be provided: domiciliary services, disposal of unwanted medicines, supply of aids for disabled people, supply of compliance aids and adverse drug reaction reporting. Neither group was enthusiastic about pharmacists providing a therapeutic drug monitoring service from community pharmacies. On other areas, pharmacists were more enthusiastic about the provision of health advice, diagnostic/screening services and treatment protocols, while FHSAs favoured distribution of welfare foods, needle exchange, instalment dispensing and referral forms.

Overall, both the FHSAs and community pharmacists were receptive to the principle of the development of the role of the community pharmacist within the primary health care team but expressed concerns regarding the training and workload implications.

20-Hydroxyecdysone release from biodegradable devices: the effect of size and shape

20-Hydroxyecdysone (20-OH) is a natural compound with many demonstrated effects on the physiological functions of vertebrates, particularly increased protein synthesis. Our study sought a suitable dosage form with continuous release of the drug lasting several weeks for implantation into agricultural animals. Biodegradable microparticles and implants of poly(L-lactic) and poly(DL-lactic) acids were prepared. Oligomers of these materials were synthesized, and a method of melting the binary mixture of the oligomer and 20-OH was employed. The particles were prepared simply by grinding the solidified block of the melt and sieving. Implants were prepared by extruding the melt into silicone tubes, removing the solidified content, and cutting into cylinders of 2 mm diameter and various lengths. A new method of preparation of hollow cylinders by aspirating air into silicone tubes filled with the melt was developed. The experiments demonstrated stability of 20-OH during heat treatment. Release of the active ingredient was tested in static in vitro conditions, analogous to those at the site of implantation, and prolonged drug release was obtained with both types of implant. The hollow implants gave release rates nearest to ideal zero-order kinetics and would appear most appropriate for testing in vivo.

The dynamic behavior of individual microtubules associated with chromosomes in vitro

Mitotic movements of chromosomes are usually coupled to the elongation and shortening of the microtubules to which they are bound. The lengths of kinetochore-associated microtubules change by incorporation or loss of tubulin subunits, principally at their chromosome-bound ends. We have reproduced aspects of this phenomenon in vitro, using a real-time assay that displays directly the movements of individual chromosome-associated microtubules as they elongate and shorten. Chromosomes isolated from cultured Chinese hamster ovary cells were adhered to coverslips and then allowed to bind labeled microtubules. In the presence of tubulin and GTP, these microtubules could grow at their chromosome-bound ends, causing the labeled segments to move away from the chromosomes, even in the absence of ATP. Sometimes a microtubule would switch to shortening, causing the direction of movement to change abruptly. The link between a microtubule and a chromosome was mechanically strong; 15 pN of tension was generally insufficient to detach a microtubule, even though it could add subunits at the kinetochore-microtubule junction. The behavior of the microtubules in vitro was regulated by the chromosomes to which they were bound; the frequency of transitions from polymerization to depolymerization was decreased, and the speed of depolymerization-coupled movement toward chromosomes was only one-fifth the rate of shortening for microtubules free in solution. Our results are consistent with a model in which each microtubule interacts with an increasing number of chromosome-associated binding sites as it approaches the kinetochore.

Activation of the MKK/ERK pathway during somatic cell mitosis: direct interactions of active ERK with kinetochores and regulation of the mitotic 3F3/2 phosphoantigen

The mitogen-activated protein (MAP) kinase pathway, which includes extracellular signal-regulated protein kinases 1 and 2 (ERK1, ERK2) and MAP kinase kinases 1 and 2 (MKK1, MKK2), is well-known to be required for cell cycle progression from G1 to S phase, but its role in somatic cell mitosis has not been clearly established. We have examined the regulation of ERK and MKK in mammalian cells during mitosis using antibodies selective for active phosphorylated forms of these enzymes. In NIH 3T3 cells, both ERK and MKK are activated within the nucleus during early prophase; they localize to spindle poles between prophase and anaphase, and to the midbody during cytokinesis. During metaphase, active ERK is localized in the chromosome periphery, in contrast to active MKK, which shows clear chromosome exclusion. Prophase activation and spindle pole localization of active ERK and MKK are also observed in PtK1 cells. Discrete localization of active ERK at kinetochores is apparent by early prophase and during prometaphase with decreased staining on chromosomes aligned at the metaphase plate. The kinetochores of chromosomes displaced from the metaphase plate, or in microtubule-disrupted cells, still react strongly with the active ERK antibody. This pattern resembles that reported for the 3F3/2 monoclonal antibody, which recognizes a phosphoepitope that disappears with kinetochore attachment to the spindles, and has been implicated in the mitotic checkpoint for anaphase onset (Gorbsky and Ricketts, 1993. J. Cell Biol. 122:1311-1321). The 3F3/2 reactivity of kinetochores on isolated chromosomes decreases after dephosphorylation with protein phosphatase, and then increases after subsequent phosphorylation by purified active ERK or active MKK. These results suggest that the MAP kinase pathway has multiple functions during mitosis, helping to promote mitotic entry as well as targeting proteins that mediate mitotic progression in response to kinetochore attachment.

Polarized light scattering by aerosols in the marine atmospheric boundary layer

The intensity and polarization of light scattered from marine aerosols affect visibility and contrast in the marine atmospheric boundary layer (MABL). The polarization properties of scattered light in the MABL vary with size, refractive index, number distributions, and environmental conditions. Laboratory measurements were used to determine the characteristics and variability of the polarization of light scattered by aerosols similar to those in the MABL. Scattering from laboratory-generated sea-salt-containing (SSC) [NaCl, (NH(4))(2) SO(4), and seawater] components of marine aerosols was measured with a scanning polarization-modulated nephelometer. Mie theory with Gaussian and log normal size distributions of spheres was used to calculate the polarized light scattering from various aerosol composition models and from experimentally determined distributions of aerosols in the marine boundary layer. The modeling was verified by comparison with scattering from distilled water aerosols. The study suggests that polarimetric techniques can be used to enhance techniques for improving visibility and remote imaging for various aerosol types, Sun angles, and viewing conditions.

Laboratory studies of angle- and polarization-dependent light scattering in sea ice

The angle- and polarization-dependent light scattering were measured for oriented first-year and multiyear sea ice taken from the Chukchi Sea near Pt. Barrow, Alaska. The entire Mueller matrix for these samples was determined at 532 nm. Mueller matrices were also determined for artificially grown saline ice samples and melted samples of the respective ice types. Phase functions for thin-slab samples are qualitatively consistent with calculations for scattering from brine inclusions in a solid ice medium and depend strongly on the shape of the scattering sample. Small orientation-dependent effects are observed for scattering from oriented sea ice. A simple model is used to describe qualitatively some features of the measured sea ice Mueller matrices. This model combines the effects of scattering from spherical inhomogeneities and the intrinsic birefringence of pure water ice. A set of Mueller matrix inequalities is presented and used to obtain physical insight into the measurement results.

Patterning of functional antibodies and other proteins by photolithography of silane monolayers

We have demonstrated the assembly of two-dimensional patterns of functional antibodies on a surface. In particular, we have selectively adsorbed micrometer-scale regions of biotinylated immunoglobulin that exhibit specific antigen binding after adsorption. The advantage of this technique is its potential adaptability to adsorbing arbitrary proteins in tightly packed monolayers while retaining functionality. The procedure begins with the formation of a self-assembled monolayer of n-octadecyltrimethoxysilane (OTMS) on a silicon dioxide surface. This monolayer can then be selectively removed by UV photolithography. Under appropriate solution conditions, the OTMS regions will adsorb a monolayer of bovine serum albumin (BSA), while the silicon dioxide regions where the OTMS has been removed by UV light will adsorb less than 2% of a monolayer, thus creating high contrast patterned adsorption of BSA. The attachment of the molecule biotin to the BSA allows the pattern to be replicated in a layer of streptavidin, which bonds to the biotinylated BSA and in turn will bond an additional layer of an arbitrary biotinylated protein. In our test case, functionality of the biotinylated goat antibodies raised against mouse immunoglobulin was demonstrated by the specific binding of fluorescently labeled mouse IgG.

Determination of the average orientation of DNA in the octopus sperm Eledone cirrhossa through polarized light scattering

The coupled-dipole approximation has been used to model polarized light-scattering data obtained from the sperm of the octopus Eledone cirrhosa. Mueller scattering-matrix elements (which describe how a sample alters the intensity and degree of polarization of scattered light) were measured as a function of angle. The sample was modeled as a helical fiber believed to correspond to a DNA protein complex. It was necessary to propose an inherent anisotropy in the polarizability of the fiber in order to fit the data. The direction of the principle axes of the polarizability were determined by comparing the model with experimental data. The results suggest that the 2-nm DNA fibers are perpendicular to the thick fiber that defines the helical geometry of the octopus sperm head.

The force exerted by a single kinesin molecule against a viscous load

Kinesin is a motor protein that uses the energy derived from the hydrolysis of ATP to power the transport of organelles along microtubules. To probe the mechanism of this chemical-to-mechanical energy transduction reaction, the movement of microtubules across glass surfaces coated with kinesin was perturbed by raising the viscosity of the buffer solution. When the viscosity of the solution used in the low density motility assay was increased approximately 100-fold through addition of polysaccharides and polypeptides, the longer microtubules, which experienced a larger drag force from the fluid, moved more slowly than the shorter ones. The speed of movement of a microtubule depended linearly on the drag force loading the motor. At the lowest kinesin density, where dilution experiments indicated that the movement was caused by a single kinesin molecule, extrapolation of the linear relationship yielded a maximum time-averaged drag force of 4.2 +/- 0.5 pN per motor (mean +/- experimental SE). The magnitude of the force argues against one type of "ratchet" model in which the motor is hypothesized to rectify the diffusion of the microtubule; at high viscosity, diffusion is too slow to account for the observed speeds. On the other hand, our data are consistent with models in which force is a consequence of strain developed in an elastic element within the motor; these models include a different "ratchet" model (of the type proposed by A. F. Huxley in 1957) as well as "power-stroke" models.

Gay men as victims of nonconsensual sex

Incidents of nonconsensual sexual activity among 930 homosexually active men living in England and Wales are analyzed. Of these men, 27.6% said they had been sexually assaulted or had sex against their will at some point in their lives; one third had been forced into sexual activity (usually anal intercourse) by men with whom they had previously had, or were currently having, consensual sexual activity. The contention that male rape is usually committed by heterosexually identified men, primarily as an expression of power and control, is not supported. Recognition that gay men rape other gay men is needed, both by the gay community and support services for victims.

Kinesin swivels to permit microtubule movement in any direction

Kinesin is a motor protein that uses the energy derived from ATP hydrolysis to transport organelles along microtubules. By analyzing the thermal fluctuation of microtubules tethered to glass surfaces by single molecules of kinesin, we have measured the torsional flexibility of the motor protein. The torsional stiffness of kinesin, (117 +/- 19) x 10(-24) N.m.rad-1 (mean +/- SEM), is so low that one kT of energy (approximately 4.1 x 10(-21) J at room temperature) is sufficient to twist a kinesin molecule through more than 360 degrees from its resting orientation. Consistent with this flexibility, motility assays show that one or more kinesin molecules can move a microtubule equally well in any direction. These results explain how a motor on the surface of an organelle can rapidly bind to and capture a microtubule irrespective of the organelle's orientation. Furthermore, the flexibility ensures that several motors can efficiently work together even though they are randomly oriented on the surface of an organelle rather than being in precise arrays like the motors of muscle and cilia.

Changes in condom use by gay men

Cross sectional and longitudinal data on condom use among homosexually active men is presented. Data pertain to two waves of interviewing (1987/8 and 1991) from Project SIGMA, a large longitudinal study of male homosexual behaviour in the light of HIV. Aggregate changes across the time-period indicate an increase in condom use for both insertive and receptive anal intercourse, particularly with casual partners. Condom use is still much more prevalent with casual rather than regular partners. Longitudinal analysis show considerable changes at the individual level, with almost a third of men changing their practices. Half of those decreased their risk behaviours, whilst the other half increased them. Less than 1% used condoms for fellatio in the year preceding the 1991 interview, but 8.3% had used other barriers during sex, primarily for hygiene and fun reasons, rather than as disease prophylaxis. Some implications are drawn for condom promotion and HIV prevention.

Sex role separation in sexual diaries of homosexual men

OBJECTIVE

To measure types of sex role prevalence in common and risk-related behaviours among gay men for modelling HIV transmission.

DESIGN

Cohort study of 385 homosexually active men recording sexual diaries over 1-month periods.

METHODS

Measures of incidence of behavioural sex roles for masturbation, fellatio, anal intercourse and anilingus by relationship type, derived from 1-month sexual diary data.

RESULTS

Low behavioural role rigidity for masturbation and fellatio, but higher rigidity for anal intercourse and anilingus. Participants with no regular partner showed a relatively low frequency of anal intercourse, whereas those in closed relationships showed a high frequency.

CONCLUSION

Although anal intercourse shows a certain degree of behavioural role rigidity, this rigidity is not large enough to conclude that gay men exclusively engage in either an active or a passive role. Typical rates for exclusive active and passive roles for anal intercourse during the month the diaries were recorded were in the range of 12-15%; the dual role was significantly higher.

The testing of saliva samples for HIV-1 antibodies: reliability in a non-clinic setting

AIMS

To assess the reliability of saliva samples as a means of testing for HIV-antibodies outside clinic settings.

METHODS

Men taking part in a non-clinic longitudinal study of homosexually active men provided samples of saliva and blood. Sera were screened using a competitive ELISA (Wellcozyme) and positive sera were confirmed by an indirect ELISA (Abbott). Saliva samples were screened either using an IgG captive radioimmunoassay or an amplified ELISA.

RESULTS

A total of 534 paired saliva and blood samples were tested. Overall sensitivity was 96.2% and specificity was 100%. None of the saliva tests were falsely positive for HIV-1 antibodies.

CONCLUSIONS

HIV-1 saliva tests can reliably be used in a non-clinic or field setting. However, if results are to be given to respondents, it is necessary to offer adequate counselling and consider the mechanisms for referral and follow-up for those that are found to be HIV-1 antibody positive.

No connection between alcohol use and unsafe sex among gay and bisexual men

OBJECTIVE

To investigate the relationship between alcohol use and unsafe sexual behaviour.

METHODS

The paper discusses data collected from 461 gay and bisexual men interviewed in England and Wales by Project SIGMA during 1991-1992. These data were collected during face-to-face interviews using retrospective weekly diary techniques and include details of all sexual sessions and alcohol use. The 819 reported sexual sessions with other men are divided into those that involved alcohol use (30.6%) and those that did not.

RESULTS

Differences in the incidence of HIV risk behaviours between sexual sessions that involved alcohol use and those that did not are small, and none are statistically significant. Furthermore, for those men who engaged in sexual behaviour whilst under the influence of alcohol, the quantity of alcohol consumed had no effect on sexual behaviour.

CONCLUSIONS

Among gay and bisexual men, sex under the influence of alcohol is no more likely to be unsafe than sex among men who have not consumed alcohol.

Molten globule monomer to condensed dimer: role of disulfide bonds in platelet factor-4 folding and subunit association

Platelet factor 4 (PF4) exhibits high affinity for heparin and exists as a tetramer in solution under physiologic conditions. Reduction of the two disulfide bridges in PF4 increases the protein's dissociation constant for heparin approximately 20-fold and shifts the highest apparent aggregation state from tetramer to dimer as evidenced by gel filtration, chemical cross-linking, and 1H-NMR studies. 1H-NMR spectra of reduced PF4 monomers generally show narrower, less dispersed, upfield-shifted NH and alpha H resonances, suggesting the presence of an unfolded monomer state. Reduced PF4 monomer folding, however, is evidenced by the presence of about 12 relatively long-lived backbone NHs and by CD spectra that indicate conservation of overall secondary structure. These data suggest the presence of a molten globule-type state. Urea denaturation shifts this apparent molten globule to a fully unfolded state characterized by more random coil-like resonance shifts. The reduced PF4 dimer state yields NMR and CD data consistent with preservation of tertiary structural folds found for the native species. In this regard, the reduced PF4 folding transition is thermodynamically linked with dimer formation which stabilizes tertiary structure. Monomer-dimer association equilibria for reduced PF4 essentially follow the same pH and salt titration trends as reported previously for native PF4 dimers [Mayo, K. H., & Chen, M. J. (1989) Biochemistry 28, 9469-9478], indicating that that dimer interface is generally conserved in the absence of disulfide constraints. Reduced PF4 tetramers are not apparent under any conditions investigated, suggesting that disulfides are necessary for efficient antiparallel beta-sheet alignment between dimer pairs.

Maintenance of open gay relationships: some strategies for protection against HIV

The role of sexual exclusivity (monogamy) in relation to HIV, and the use of rule making in non-exclusive (open) relationships, are discussed. Data from interviews with 387 homosexually active men are presented. The most common sexual/relational configuration amongst these men is that of open relationships. Sexual non-exclusivity was found to be associated with longer relationships, and a greater age difference between partners. The strategies some of these men are using to maintain sexually non-exclusive relationships are outlined. These rules pertain both to interpersonal dynamics and HIV prevention. Differing epidemiological significance of the rules and some implications for health education are discussed.

The sexual behaviour of young gay men in England and Wales

Much research has concluded that young gay men are at disproportionately higher risk of HIV infection through unsafe sexual behaviour. This paper is the first report on this particular group in the UK. As part of a larger cohort study, 111 young (less than 21) gay and bisexual men were interviewed about their sexual behaviour, knowledge of AIDS and HIV, particularly safer sexual practices and other factors. Three per cent had not had sex and 13% had not had anal intercourse with a man at the time of interview. Forty-five per cent had sexual experience with a woman and 34% had engaged in vaginal intercourse. The average age at first homosexual experience was just under 15 years and this is higher than other age groups in the cohort. Median number of male partners in the year before interview was 5, with 1 of whom anal intercourse occurred. Sexual repertoire was relatively restricted compared to older men. Condom use was slightly more consistent and levels of knowledge not significantly different. From these findings, the contention that young gay men are at higher risk of HIV infection through risky sexual behaviour is not supported.

Light scattering by Prorocentrum micans: a new method and results

Striking light-scattering behavior was observed from a marine dinoflagellate, Prorocentrum micans. Measurements of the angular dependence of the 16 Mueller matrix elements were performed on single cells with a polarization-modulation nephelometer by using a new method for cell immobilization. First the dinoflagellate cells were immobilized in a transparent silica gel containing alcohol, and then a second liquid was diffused into the gel to match the index of refraction of the gel network, thereby producing a transparent support medium that scatters less than one tenth the amount of light scattered by a single cell at 90 degrees . Measurements of scattering by a single cell revealed that all 16 matrix elements were significantly nonzero and different from each other. All matrix elements have an extremely rich, reproducible structure that is highly dependent on cell orientation. The matrix elements symmetrically across the diagonal were not equivalent. Striking features of the measurements are the large peak values of S(13), S(14), and other off-diagonal block elements. We believe that this is the first report of such scattering signals by single, suspended marine microorganisms.

Hemoglobin polymerization in sickle cells studied by circular polarized light scattering

We have studied intracellular polymerization of hemoglobin S in suspensions of small populations of sickle cells using circular polarized light scattering. We argue that the preferential scattering of right circular polarized light (as expressed by measurements of the S14 Mueller scattering matrix element) directly reflects the amount of polymer inside cells. This technique has made it possible to investigate the effect of oxygen tension, cell density and osmotic stress on intracellular hemoglobin polymerization. Using S14 to determine hemoglobin polymer, we show that the polymer increases with deoxyhemoglobin concentration, that cells containing higher hemoglobin concentrations show significantly more polymer than cells containing less hemoglobin, and that polymerization occurs in sickle-trait cells in hypertonic solutions as the oxygen tension in the suspension is reduced. We also present kinetic measurements of polymerization, including that induced by osmotic shock. Finally, we demonstrate that the total light scattered (S11 Mueller scattering matrix element) that is routinely measured simultaneously with S14 can be used to estimate the percent of reduced (deoxy) Hb in the sample. These experiments demonstrate the potential of this technique to monitor hemoglobin polymerization simultaneously with oxygen dissociation under a wide variety of physiological conditions.

Sexual partners, penetrative sexual partners and HIV risk

This paper argues that the notion of sexual partners per se is insufficient for estimating levels of HIV risk behaviour or changes in HIV risk over time, even though it is a crucial element of most epidemiological models of HIV. The concept of a penetrative sexual partner (PSP) is introduced as a considerably more accurate measure of HIV risk. Using data from a longitudinal study of 930 homosexually active men in England and Wales, this paper demonstrates that variation in numbers of PSPs (and thus HIV risk) is not related to variation in the gross numbers of sexual partners.

Inhibition of tumor growth in mice by an analogue of platelet factor 4 that lacks affinity for heparin and retains potent angiostatic activity

An analogue of human platelet factor 4 (PF4) lacking affinity for heparin was specifically designed to evaluate the importance of this property in the antitumor effects of recombinant PF4. The purified protein, recombinant PF4-241 (rPF4-241), failed to bind heparin but retained the ability to suppress the growth of tumors in mice. Daily intralesional injections of rPF4-241 significantly inhibited the growth of the B-16 melanoma in syngeneic mice without direct inhibitory effects on B-16 cell growth in vitro. Similar antitumor effects were observed with the human colon carcinoma, HCT-116, grown in nude mice, indicating that the inhibitory activity was neither tumor-type specific nor T-cell dependent. rPF4-241 inhibited endothelial cell proliferation in vitro with dose dependence similar to the native sequence rPF4. Both rPF4 and rPF4-241 inhibited angiogenesis in the chicken chorioallantoic membrane. The analogue, however, was inhibitory at lower concentrations than rPF4 in the chorioallantoic membrane system and its inhibitory effects were not abrogated by the presence of heparin. The present findings support the conclusion that both rPF4 and rPF4-241 inhibit tumor growth by suppression of tumor-induced neovascularization. The finding that this activity is independent of heparin binding may allow the development of PF4-based angiostatic agents with reduced toxicity and improved bioavailability. These results also suggest that PF4 may play a more specific role in modulation of blood vessel development than previously recognized.

Expression and purification of active recombinant platelet factor 4 from a cleavable fusion protein

A synthetic gene for human platelet factor 4 (hPF4) has been expressed at high levels as a fusion protein in Escherichia coli. The hPF4 sequence has been cleaved from the fusion protein by cyanogen bromide treatment and purified by column chromatography. Like hPF4, our recombinant hPF4 (rhPF4) is tetrameric under physiological conditions, binds heparin, and inhibits angiogenesis. Extensive purification to remove trace amounts of uncleaved fusion protein completely from the desired product rhPF4 was difficult. We have exploited recombinant DNA technology by modifying the fusion moiety to accomplish separation. This type of modification, which did not affect expression level, could be applied to other recombinant fusion proteins.

Changes in sexual behaviour in a large cohort of homosexual men in England and Wales, 1988-9

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Condom use in a large cohort of homosexually active men in England and Wales

As part of a prospective study of the seroprevalence of HIV, a cohort of 930 men were interviewed regarding their condom use. Of the 270 respondents that engaged in insertive anal intercourse in the month preceding interview 38.9% always used a condom, 49.6% never used one, and 11.5% sometimes used one. Of the 254 respondents that engaged in receptive anal intercourse in the same time period 42.5% always used a condom, 45.7% never used one, and 11.8% sometimes used one. Compared to other research the proportion of respondents who always use a condom for anal intercourse is relatively high, though use is by no means universal. Condom use is more widespread and consistent with casual rather than regular sexual partners, and it is significantly more common within open rather than monogamous relationships. Out of a wide range of other factors only geographical location (London against outside), marital status, perceived HIV status, number of sexual partners, and how seriously respondents take safer sex are correlated with condom use.

Seroprevalence of HIV-1 infection in a cohort of homosexually active men

A non-clinic cohort of 525 homosexually active men from London and South Wales were recruited in 1988 for a study by interview of sexual behaviour. A sample of blood was tested for HIV-1 antibodies. Seropositivity in London was 9.2% compared with 3.4% in South Wales. Men who were not regular STD clinic attenders had a lower rate of seropositivity than did those who were regular attenders. Men who were seropositive reported more sexual partners with whom they had anal intercourse and also reported more episodes of syphilis. Overall, rates of seropositivity were lower than those reported by studies from STD clinics.

Reentrant tachycardia in a thin layer of ventricular subepicardium: effects of d-sotalol and lidocaine

Ventricular tachycardia (VT) was induced by premature stimulation or fast pacing in 14 Langendorff-perfused rabbit hearts whose left ventricular endocardial and intramural cells had been selectively killed by freezing. VTs were caused by apparent reentrant excitation in the surviving thin (1 mm thick) subepicardial layer of anisotropically oriented cells having ostensibly normal membrane characteristics. During VT, 100 microM d-sotalol (seven hearts) or 30 microM lidocaine (seven hearts) was added to the perfusate. Electrophysiological variables were measured before and during drug exposure at both slow (S1 = 300 ms) and fast (S1 = 150-180 ms) pacing rates. Sotalol prevented VT reinduction in six of seven preparations, compared to only two of seven with lidocaine. Lidocaine prolonged the functional refractory period (FRP) and slowed conduction velocity (CV). Lidocaine prolonged the wavelength of the cardiac impulse (= FRP x CV) by 18% at slow rates but reduced it by 21% at fast rates. Sotalol, however, since it increased the FRP without reducing CV, caused wavelength prolongation at both rates (43% at slow rates, 26% at fast rates). Thus, this VT model may provide an important contrast of class I and class III drug action, with the drug effects on wavelength predicting susceptibility to VT induction.

Heterosexual behaviour in a large cohort of homosexually active men in England and Wales

This paper seeks to outline the range and type of heterosexual behaviour in a large non-clinic cohort of homosexually active males. A cohort of 930 homosexually active men were interviewed as part of a prospective study of the seroprevalence of HIV. The paper indicates that over 60% of these men have had at least one sexual experience with a female and that about 90% of these males have engaged in vaginal intercourse with a female. Twelve per cent of the cohort had sexual contact with females in the last year, and 5% had sex with females, in the month preceding interview. Amongst these behaviourally bisexual males the number of female partners is significantly lower than the number of male partners. However, the proportion of female partners with whom penetration occurs is very much higher than for male partners.

Inhibition of angiogenesis by recombinant human platelet factor-4 and related peptides

Recombinant human platelet factor-4 (rhPF4), purified from Escherichia coli, inhibited blood vessel proliferation in the chicken chorioallantoic membrane in a dose-dependent manner. Treatment of several cell types with rhPF4 in vitro suggested that the angiostatic effect was due to specific inhibition of growth factor-stimulated endothelial cell proliferation. The inhibitory activities were associated with the carboxyl-terminal, heparin-binding region of the molecule and could be abrogated by including heparin in the test samples, an indication that sulfated polysaccharides might modulate the angiostatic activity of platelet factor-4 in vivo. Understanding of the mechanisms of control of angiogenesis by endogenous proteins should facilitate the development of effective treatments for diseases of pathogenic neovascularization such as Kaposi's sarcoma, diabetic retinopathy, and malignant tumor growth.

Induction of antigen-specific antibody responses in primed and unprimed B cells. Functional heterogeneity among Th1 and Th2 T cell clones

CD4+ T cells have been recently divided into two subsets. The functions of these subsets are thought to be distinct: one subset (Th1) is responsible for delayed type hypersensitivity responses and another (Th2) is primarily responsible for induction of antibody synthesis. To more precisely define the roles of both subsets in humoral immune responses, we examined the ability of a panel of nominal antigen specific Th1 and Th2 clones to induce anti-TNP specific antibody synthesis in TNP-primed or unprimed B cells. Four of nine Th1 clones induced little or no antibody synthesis with TNP-primed B cells. However, five other Th1 clones were very effective at inducing IgG anti-TNP plaque-forming cell (PFC) responses in primed B cells. One of these Th1 clones was analysed in detail and found to also provide helper function for unprimed B cells. Cognate B-T cell interaction was required for induction of both primary and secondary responses with this clone, indicating that a Th1 clone could function as a "classical" Th cell. The seven IL-4 producing Th2 clones examined were also heterogeneous in their ability to induce antibody secretion by TNP-primed B cells. Although four of the Th2 clones induced IgG and IgM anti-TNP PFC responses, two Th2 clones induced only IgM and no IgG antibody, and another clone failed to induce any anti-TNP PFC. All Th2 clones failed to induce any anti-TNP PFC. All Th2 clones produced high levels of IL-4, but "helper" Th2 clones produced significantly greater amounts of IL-5 than "non-helper" Th2 clones. These studies indicate that some IL-2- and some IL-4-producing T cell clones can induce TNP-specific antibody in cell clones can induce TNP-specific antibody in primed and unprimed B cells, and that Th1 and Th2 clones are heterogeneous in their ability to induce Ig synthesis. Therefore, although T cell clones can be classified as Th1 or Th2 types according to patterns of IL-2, IFN-gamma, or IL-4 synthesis, the functional capacity to induce antibody synthesis cannot be predicted solely by their ability to secrete these lymphokines.

Induction of antigen-specific antibody responses in primed and unprimed B cells. Functional heterogeneity among Th1 and Th2 T cell clones

CD4+ T cells have been recently divided into two subsets. The functions of these subsets are thought to be distinct: one subset (Th1) is responsible for delayed type hypersensitivity responses and another (Th2) is primarily responsible for induction of antibody synthesis. To more precisely define the roles of both subsets in humoral immune responses, we examined the ability of a panel of nominal antigen specific Th1 and Th2 clones to induce anti-TNP specific antibody synthesis in TNP-primed or unprimed B cells. Four of nine Th1 clones induced little or no antibody synthesis with TNP-primed B cells. However, five other Th1 clones were very effective at inducing IgG anti-TNP plaque-forming cell (PFC) responses in primed B cells. One of these Th1 clones was analysed in detail and found to also provide helper function for unprimed B cells. Cognate B-T cell interaction was required for induction of both primary and secondary responses with this clone, indicating that a Th1 clone could function as a "classical" Th cell. The seven IL-4 producing Th2 clones examined were also heterogeneous in their ability to induce antibody secretion by TNP-primed B cells. Although four of the Th2 clones induced IgG and IgM anti-TNP PFC responses, two Th2 clones induced only IgM and no IgG antibody, and another clone failed to induce any anti-TNP PFC. All Th2 clones failed to induce any anti-TNP PFC. All Th2 clones produced high levels of IL-4, but "helper" Th2 clones produced significantly greater amounts of IL-5 than "non-helper" Th2 clones. These studies indicate that some IL-2- and some IL-4-producing T cell clones can induce TNP-specific antibody in cell clones can induce TNP-specific antibody in primed and unprimed B cells, and that Th1 and Th2 clones are heterogeneous in their ability to induce Ig synthesis. Therefore, although T cell clones can be classified as Th1 or Th2 types according to patterns of IL-2, IFN-gamma, or IL-4 synthesis, the functional capacity to induce antibody synthesis cannot be predicted solely by their ability to secrete these lymphokines.

Experimental determinations of Mueller scattering matrices for nonspherical particles

Measurements have been made to determine all sixteen elements of the Mueller scattering matrix for two types of nonspherical particles. Rounded particles of ammonium sulfate and nearly cubic particles of sodium chloride in the 0.1-1.0-mum size range have been prepared by nebulizing salt water solutions and drying the droplets. Scanning electron micrographs are used to determine size distributions used in Mie calculations of all matrix elements. The expected symmetry of the scattering matrices across the diagonal was confirmed, and the expected eight of the sixteen elements were found to be zero within measurement accuracy. The rounded particles were found accurately to obey Mie theory, while the cubic particles were poorly described by Mie theory for some matrix elements and some angles. Total intensity and linear polarization measurements are presented also for a series of increasing sizes of rounded and cubic particles. A discussion of the effect of nonsphericity on the various matrix elements is given, and applications of these results are given to analysis of particle properties in the laboratory, the clouds of Venus, reflection nebulae, the zodiacal light, and atmospheric particulates.