Stable flies sense and behaviorally respond to the polarization of light

Insects use their polarization-sensitive photoreceptors in a variety of ecological contexts including host-foraging. Here, we investigated the effect of polarized light on host foraging by the blood-feeding stable fly, Stomoxys calcitrans, a pest of livestock. Electroretinogram recordings with chromatic adaptation demonstrated that the spectral sensitivity of stable flies resembles that of other calyptrate flies. Histological studies of the flies' compound eye revealed differences in microvillar arrangement of ommatidial types, assumed to be pale and yellow, with the yellow R7 and pale R8 photoreceptors having the greatest polarization sensitivity. In behavioural experiments, stable flies preferred to alight on horizontally polarized stimuli with a high degree of linear polarization. This preferential response disappeared when either ultraviolet (UV) or human-visible wavelengths were omitted from light stimuli. Removing specific wavelength bands further revealed that the combination of UV (330-400 nm) and blue (400-525 nm) wavelength bands was sufficient to enable polarized light discrimination by flies. These findings enhance our understanding of polarization vision and foraging behavior among hematophagous insects and should inform future trap designs.

Measuring Mosquito Spectral Sensitivity Using Electroretinograms

Mosquitoes use a variety of cues to locate resources in the world around them, including olfactory, thermal, and visual stimuli. Understanding how mosquitoes perceive these stimuli is important for understanding and investigating mosquito behaviors and mosquito ecology. Specifically, mosquito vision can be studied in many ways, including by using electrophysiological recordings from their compound eyes. Electroretinograms can be used to characterize the spectral sensitivity of a mosquito species, revealing the wavelengths of light they can perceive. Here, we provide details on how to perform and analyze these recordings.

Mosquito (Diptera: Culicidae) Vision and Associated Electrophysiological Techniques

Mosquitoes are considered the world's deadliest animal because of the pathogens they spread. Additionally, they are an unbearable nuisance in many areas. Visual stimuli play an important role in the mosquito life cycle, helping them find vertebrate hosts, floral nectar, and oviposition sites. Here, we review mosquito vision, including its influences on mosquito behavior, the photoreceptors involved, and mosquito spectral sensitivity, as well as provide an overview of techniques used for the analysis of mosquito vision, including electroretinograms, single-cell recordings, and the use of opsin-deficient mutants. We anticipate that this information will be useful for researchers studying mosquito physiology, evolution, ecology, and management.

Mosquito biology: Scents and selectability

Malaria-transmitting mosquitoes are skilled human hunters, selectively choosing their prey based on a complex array of sensory cues. A new study unveils a distinct pattern of preference for human-associated olfactory cues that underlies the selective behavior of these mosquitoes.

Approach trajectory and solar position affect host plant attractiveness to the small white butterfly

While it is well documented that insects exploit polarized sky light for navigation, their use of reflected polarized light for object detection has been less well studied. Recently, we have shown that the small white butterfly, Pieris rapae, distinguishes between host and non-host plants based on the degree of linear polarization (DoLP) of light reflected from their leaves. To determine how polarized light cues affect host plant foraging by female P. rapae across their entire visual range including the ultraviolet (300-650 nm), we applied photo polarimetry demonstrating large differences in the DoLP of leaf-reflected light among plant species generally and between host and non-host plants specifically. As polarized light cues are directionally dependent, we also tested, and modelled, the effect of approach trajectory on the polarization of plant-reflected light and the resulting attractiveness to P. rapae. Using photo polarimetry measurements of plants under a range of light source and observer positions, we reveal several distinct effects when polarized reflections are examined on a whole-plant basis rather than at the scale of pixels or plant canopies. Most notably from our modeling, certain approach trajectories are optimal for foraging butterflies, or insects generally, to discriminate between plant species on the basis of the DoLP of leaf-reflected light.

Polarized light sensitivity in Pieris rapae is dependent on both color and intensity

There is an ever increasing number of arthropod taxa shown to have polarization sensitivity throughout their compound eyes. However, the downstream processing of polarized reflections from objects is not well understood. The small white butterfly, Pieris rapae, has been demonstrated to exploit foliar polarized reflections, specifically the degree of linear polarization (DoLP), to recognize host plants. The well-described visual system of P. rapae includes several photoreceptor types (red, green, blue) that are sensitive to polarized light. Yet, the roles and interaction among photoreceptors underlying the behavioral responses of P. rapae to stimuli with different DoLP remain unknown. To investigate potential neurological mechanisms, we designed several two-choice behavioral bioassays, displaying plant images on paired LCD monitors, which allowed for independent control of polarization, color and intensity. When we presented choices between stimuli that differed in either color or DoLP, both decreasing and increasing the intensity of the more attractive stimulus reduced the strength of preference. This result suggests that differences in color and DoLP are perceived in a similar manner. When we offered a DoLP choice between plant images manipulated to minimize the response of blue, red, or blue and red photoreceptors, P. rapae shifted its preference for DoLP, suggesting a role for all of these photoreceptors. Modeling of P. rapae photoreceptor responses to test stimuli suggests that differential DoLP is not perceived solely as a color difference. Our combined results suggest that Prapae females process and interpret polarization reflections in a way different from that described for other polarization-sensitive taxa.

Multimodal and multifunctional signaling? - Web reduction courtship behavior in a North American population of the false black widow spider

Males of widow spiders courting on the web of females engage in web-reduction behavior which entails excising a section of the web, bundling it up, and wrapping it with their silk. Males of the false black widow spider, Steatoda grossa, in European populations also produce stridulatory courtship sound which has not yet been studied in their invaded North American range. Working with a North American population of S. grossa, we tested the hypotheses that (1) web reduction by males renders webs less attractive to rival males; (2) deposition of silk by courting males has an inter-sexual (male-female) signal function that enhances their likelihood of copulation; and (3) stridulatory sound is a courtship signal of males. Testing anemotactic attraction of males in Y-tube olfactometer experiments revealed that reduced webs (indicative of a mated female) and intact webs (indicative of a virgin female) were equally attractive to males. Recording courtship behavior of males with either functional (silk-releasing) spinnerets or spinnerets experimentally occluded on the web of virgin females showed that males with functional spinnerets were more likely to copulate with the female they courted. Although males possess the stridulatory apparatus to produce courtship sound, they did not stridulate when courting or copulating on the web of females. Our data support the conclusion that web-reduction behavior of S. grossa males in their invaded North American range has no long-range effect on mate seeking males. Instead, web-reduction behavior has an inter-sexual signaling function that seems to be linked to functional spinnerets of the courting male. The signal produced by a male likely entails a volatile silk-borne pheromone, but may also embody a gauge of his endurance (the amount of time he engages in web reduction causing web vibrations).

Polarization of foliar reflectance: novel host plant cue for insect herbivores

Insect herbivores exploit plant cues to discern host and non-host plants. Studies of visual plant cues have focused on colour despite the inherent polarization sensitivity of insect photoreceptors and the information carried by polarization of foliar reflectance, most notably the degree of linear polarization (DoLP; 0-100%). The DoLP of foliar reflection was hypothesized to be a host plant cue for insects but was never experimentally tested. Here, we show that cabbage white butterflies, Pieris rapae (Pieridae), exploit the DoLP of foliar reflections to discriminate among plants. In experiments with paired digital plant images, P. rapae females preferred images of the host plant cabbage with a low DoLP (31%) characteristic of cabbage foliage over images of a non-host potato plant with a higher DoLP (50%). By reversing the DoLP of these images, we were able to shift the butterflies' preference for the cabbage host plant image to the potato non-host plant image, indicating that the DoLP had a greater effect on foraging decisions than the differential colour, intensity, or shape of the two plant images. Although previously not recognized, the DoLP of foliar reflection is an essential plant cue that may commonly be exploited by foraging insect herbivores.

Ultraviolet inflorescence cues enhance attractiveness of inflorescence odour to Culex pipiens mosquitoes

Inflorescence patterns of ultraviolet (UV) absorption and UV-reflection are attractive to many insect pollinators. To understand whether UV inflorescence cues affect the attraction of nectar-foraging mosquitoes, we worked with the common house mosquito, Culex pipiens and with two plant species exhibiting floral UV cues: the tansy, Tanacetum vulgare, and the common hawkweed Hieraciumm lachenalii. Electroretinograms revealed that Cx. pipiens eyes can sense UV wavelengths, with peak sensitivity at 335 nm. Behavioural bioassays divulged that UV inflorescence cues enhance the attractiveness of inflorescence odour. In the presence of natural floral odour, female Cx. pipiens were attracted to floral patterns of UV-absorption and UV-reflection but preferred uniformly UV-dark inflorescences. Moreover, Cx. pipiens females preferred UV-dark and black inflorescence models to UV-dark and yellow inflorescence models. With feathers and pelts of many avian and mammalian hosts also being UV-dark and dark-coloured, foraging Cx. pipiens females may respond to analogous visual cues when they seek nectar and vertebrate blood resources.

Compound eyes of the small white butterfly Pieris rapae have three distinct classes of red photoreceptors

The two subspecies of the small white butterfly, the European Pieris rapae rapae and the Asian P. r. crucivora, differ in wing colouration. Under ultraviolet light, the wings of both male and female P. r. rapae appear dark, whereas the wings of male P. r. crucivora are dark and those of females are bright. It has been hypothesized that these sexually dimorphic wing reflections in P. r. crucivora may have induced the evolution of a fluorescing-screening pigment in the violet-opsin-expressing photoreceptors of males, thus facilitating greater wavelength discrimination near 400 nm. Comparing the compound eyes of the two subspecies using genetic, microscopical, spectrographic, and histological methods revealed no differences that would meaningfully affect photoreceptor sensitivity, suggesting that the fluorescing-screening pigment did not evolve in response to sexually dimorphic wing reflections. Our investigation further revealed that (i) the peri-rhabdomal reddish-screening pigments differ among the three ommatidial types; (ii) each of the ommatidial types exhibits a unique class of red photoreceptor with a distinct spectral peak; and (iii) the blue, green, and red photoreceptors of P. rapae exhibit a polarization sensitivity > 2, with red photoreceptors allowing for a two-channel opponency form of polarization sensitivity.

How flies are flirting on the fly

Background

Flies have some of the most elaborate visual systems in the Insecta, often featuring large, sexually dimorphic eyes with specialized “bright zones” that may have a functional role during mate-seeking behavior. The fast visual system of flies is considered to be an adaptation in support of their advanced flight abilities. Here, we show that the immense processing speed of the flies’ photoreceptors plays a crucial role in mate recognition.

Results

Video-recording wing movements of abdomen-mounted common green bottle flies, Lucilia sericata, under direct light at 15,000 frames per second revealed that wing movements produce a single, reflected light flash per wing beat. Such light flashes were not evident when we video-recorded wing movements under diffuse light. Males of L. sericata are strongly attracted to wing flash frequencies of 178 Hz, which are characteristic of free-flying young females (prospective mates), significantly more than to 212, 235, or 266 Hz, characteristic of young males, old females, and old males, respectively. In the absence of phenotypic traits of female flies, and when given a choice between light emitting diodes that emitted either constant light or light pulsed at a frequency of 110, 178, 250, or 290 Hz, males show a strong preference for the 178-Hz pulsed light, which most closely approximates the wing beat frequency of prospective mates.

Conclusions

We describe a previously unrecognized visual mate recognition system in L. sericata. The system depends upon the sex- and age-specific frequencies of light flashes reflecting off moving wings, and the ability of male flies to distinguish between the frequency of light flashes produced by rival males and prospective mates. Our findings imply that insect photoreceptors with fast processing speed may not only support agile flight with advanced maneuverability but may also play a supreme role in mate recognition. The low mating propensity of L. sericata males on cloudy days, when light flashes from the wings of flying females are absent, seems to indicate that these flies synchronize sexual communication with environmental conditions that optimize the conspicuousness of their communication signals, as predicted by sensory drive theory.

Electronic supplementary material

The online version of this article (doi:10.1186/s12915-016-0342-6) contains supplementary material, which is available to authorized users.

Plant nutrients and the spatiotemporal distribution dynamics of Ceutorhynchus obstrictus (Coleoptera: Curculionidae) and its parasitoids

The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), is an alien invasive pest of canola, Brassica napus L., in North America. Field populations of both adults and larvae are known to be aggregated in their distributions, but the causal mechanism for this clustering is not understood. We investigated the hypothesis that spatial distributions of C. obstrictus adults, larvae, and their parasitoids were directly or indirectly related to host plant quality as indicated by leaf tissue nutrient contents. During the years of 2005 and 2007, these insect populations were sampled in a grid pattern in three commercial fields of B. napus located near Lethbridge, Alberta, Canada. Leaf samples were collected from plants in each grid plot and analyzed for nutrient contents. Spatial patterns and associations among the collected variables were analyzed using Spatial Analysis by Distance IndicEs software. We observed significant spatial associations among C. obstrictus adults, larvae, and parasitoids. The distributions of C. obstrictus adults and larvae were correlated with several plant nutrients, most notably nitrogen and sulfur. Evidence was found for a possible nitrogen-sulfur interaction in which ovipositioning C. obstrictus females appeared to prefer plants with high levels of sulfur and low levels of nitrogen. Spatial tracking of C. obstrictus larvae by its parasitoids was evident in only one field, and this appeared related to comparatively low parasitoid populations in two of the three fields. The associations between C. obstrictus and plant nutrients may have possible applications in fertility management, trap cropping, and precision insecticide application technology.

Multilayer PDMS microfluidic chamber for controlling brain slice microenvironment

A novel three-layer microfluidic polydimethylsiloxane (PDMS) device was constructed with two fluid chambers that holds a brain slice in place with microposts while maintaining laminar perfusate flow above and below the slice. Our fabrication technique permits rapid production of PDMS layers that can be applied to brain slices of different shapes and sizes. In this study, the device was designed to fit the shape and thickness (530-700 microm) of a medullary brain slice taken from P0-P4 neonatal rats. Medullary slices in this chamber spontaneously produced rhythmic, respiratory-related motor output for up to 3 h, thereby demonstrating that brain slice viability was maintained for prolonged periods. This design is unique in that it achieves independent control of fluids through multiple channels in two separate fluid chambers. The laminar flow exhibited by the microfluidic chamber allows controlled solutions to target specific areas of the brain slice based on the input flow rates. To demonstrate this capability, a stream of Na(+)-free solution was focused on one half of a medullary slice to abolish spontaneous neural activity in only that half of the brain slice, while the other half remained active. We also demonstrated that flow of different solutions can be focused over the midline of the brain slice. The multilayer brain slice chamber design can integrate several traditional types of electrophysiology tools that are commonly used to measure neurophysiological properties of brain slices. Thus, this new microfluidic chamber is advantageous for experiments that involve controlled drug or solution delivery at high spatiotemporal resolution.

Enhanced Lactose Cheese Milk does not Guarantee Calcium Lactate Crystals in Finished Cheddar Cheese

Three experimental batches of Cheddar cheese were manufactured in duplicate, with standardization of the initial cheese-milk lactose content to high (5.24%), normal (4.72%, control), and low lactose (3.81%). After 35 d of aging at 4.4 degrees C, the cheeses were subjected to temperature abuse (24 h at 21 degrees C, unopened) and contamination (24 h at 21 degrees C, packages opened and cheeses contaminated with crystal-containing cheese). After aging for 167 d, residual cheese lactose (0.08 to 0.43%) and L(+)-lactate concentrations (1.37 to 1.60%) were high and D(-)-lactate concentrations were low (<0.03%) for all cheeses. No significant differences in lactose concentrations were attributable to temperature abuse or contamination. No significant differences in L(+)- or D(-)-lactate concentrations were attributable to temperature abuse. However, concentrations of L(+)-lactate were significantly lower and D(-)-lactate were significantly higher in contaminated cheeses than in control cheeses, indicating inoculation (at d 35) with heterofermentative nonstarter lactic acid bacteria able to racemize L(+)-lactate to D(-)-lactate. The fact that none of the cheeses exhibited crystals after 167 d demonstrates that high cheese milk or residual lactose concentrations do not guarantee crystal formation. Contamination with nonstarter lactic acid bacteria can significantly contribute to D(-)-lactate accumulation in cheese.

Chelating alkoxy-N-heterocyclic carbene complexes of silver and copper

Incorporation of an alkoxide functional group into an N-heterocyclic carbene (NHC) ligand allows the synthesis of the first anionic NHC chelating ligands, which react to give the first neutral, molecular silver(I) alkoxide carbene complex, and a copper(I) derivative containing the first nonmacrocyclic, square planar Cu(I) centres.

Inorganic-organic interpenetrating frameworks: 4,4'-bipyridine N,N'-dioxide as a bridging hydrogen-bond acceptor

4,4'-Bipyridine N,N'-dioxide (L) acts as a hydrogen-bond acceptor in the compounds ([M(NO3)2(H2O)4].L2) (M = Co, Ni) to form doubly-interpenetrated framework materials with sixfold topological connectivity.

Bis(mu-2-cyanopyridine-N:N')bis[(2-cyanopyridine-N)silver(I)] bis(tetrafluoroborate): an anion-linked molecular ladder

In the title compound, [Ag(2)(C(6)H(4)N(2))(4)](BF(4))(2), the Ag(I) cations adopt distorted trigonal-planar coordination geometries. The Ag(I) centres are linked via two bridging 2-cyanopyridine ligands to give a centrosymmetric dinuclear complex in which the Ag(I) coordination environment is completed by monodentate non-bridging 2-cyanopyridine ligands. Bridging Ag...F(BF(2))F...Ag interactions link the dinuclear cations into molecular ladders.

Diels-Alder adducts of medium-ring carbocyclic dienes prepared by rearrangement of catalytically generated cyclic oxonium ylides

The novel bicyclic and tricyclic systems dimethyl (4aS*,6S*)-6-methoxy-7-oxo-4a,5,6,7,8,9-hexahydro-2H-benzocycloheptene-3,4-dicarboxylate, C(16)H(20)O(6), (I), dimethyl (4aS*,6R*)-6-methoxy-7-oxo-4a,5,6,7,8,9-hexahydro-2H-benzocycloheptene-3,4-dicarboxylate, C(16)H(20)O(6), (II), (3aS*,9R*,10aS*,10bR*)-9-methoxy-2-oxa-1,3a,4,6,7,8,9,10,10a,10b-decahydro-3H-cyclohepta[e]indene-1,3,8-trione, C(14)H(16)O(5), (III), and (1S*,2R*,9S*,10aR*)-9-methoxy-8-oxo-1,2,3,5,6,7,8,9,10,10a-decahydrobenzocyclooctene-1,2-dicarboxylic acid, C(15)H(20)O(6), (IV), have been crystallographically characterized, allowing the determination of the relative configuration of the stereogenic centres. The poor quality of the dicarboxylic acid crystals necessitated the use of synchrotron radiation.

Dynamic equilibria in the products of intramolecular Buchner additions of diazoketones to aryl rings bearing methoxy substituents

Rhodium carboxylate catalyzed aromatic addition reactions of a range of diazoketones bearing methoxy-substituted aryl rings have been explored. While the existence of norcaradiene-cycloheptatriene equilibria in related compounds is well established, the aromatic addition products in this study display more complex dynamic equilibria due to conjugation with the methoxy group; the experimental evidence for this is discussed in detail. In the azulenone products 21-26 derived from p-methoxy-substituted diazoketones 14-16, the diastereomers interconvert via a spiro intermediate 39. A related mechanistic process in the azulenones 43-46 derived from the o-methoxy-substituted diazoketones 17, 18 interconverts regioisomers, explaining the conflicting reports for the regioselectivity of the cyclization of diazoketone 1. With the m-methoxy-substituted diazoketone 19, involvement of the methoxy group through a different pathway results in fragmentation of the azulenone to form the tetralone 47. With the azulenones 21-26 exclusive trapping of the norcaradiene associated with the less thermodynamically stable diastereomers in a cycloadduct with N-phenylmaleimide is observed. Due to the presence of the activating methoxy substituent on the aromatic ring, the aromatic addition reactions of the diazoketones studied were not very sensitive to the nature of the rhodium catalyst.

A phenoxyl radical complex of copper(II)

A new N,O-bidentate pro-ligand (HL), [ML2] (M = Cu, Zn) and [CuL2][BF4] have been synthesised; [CuL2].4DMF and [CuL2][BF4].2CH2Cl2 have been crystallographically and spectroscopically characterised; these data indicate that [CuL2]+ cations are constituted as [Cu2+(L.)(L-)]+ and involve the phenoxyl radical L..

Group 5 imido complexes derived from diamido-pyridine ligands

Reaction of the vanadium(V) imide [V(NAr)Cl(3)(THF)] (Ar = 2,6-C(6)H(3)(i)()Pr(2)) with the diamino-pyridine derivative MeC(2-C(5)H(4)N)(CH(2)NHSiMe(2)(t)()Bu)(2) (abbreviated as H(2)N'(2)N(py)) gave modest yields of the vanadium(IV) species [V(NAr)(H(3)N'N' 'N(py))Cl(2)] (1 where H(3)N'N' 'N(py) = MeC(2- C(5)H(4)N)(CH(2)NH(2))(CH(2)NHSiMe(2)(t)()Bu) in which the original H(2)N'(2)N(py) has effectively lost SiMe(2)(t)()Bu (as ClSiMe(2)(t)()Bu) and gained an H atom. Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl(3)(py)(2)] (M = Nb or Ta, R = (t)()Bu or Ar) and the dilithium salt Li(2)[N(2)N(py)] (where H(2)N(2)N(py) = MeC(2-C(5)H(4)N)(CH(2)NHSiMe(3))(2)), and these yielded the six-coordinate M(V) complexes [M(NR)Cl(N(2)N(py))(py)] (M = Nb, R = (t)()Bu 2; M = Ta, R = (t)()Bu 3 or Ar 4). The compounds 2-4 are fluxional in solution and undergo dynamic exchange processes via the corresponding five-coordinate homologues [M(NR)Cl(N(2)N(py))]. Activation parameters are reported for the complexes 2 and 3. In the case of 2, high vacuum tube sublimation afforded modest quantities of [Nb(N(t)()Bu)Cl(N(2)N(py))] (5). The X-ray crystal structures of the four compounds 1, 2, 3, and 4 are reported.

4-Ethynyl-1,2-methylenedioxybenzene at 150 K

The title compound, C(9)H(6)O(2), contains two moderate C-H.O hydrogen bonds. That involving the terminal alkyne gives rise to chains along the b axis. The other hydrogen bond occurs over a centre of symmetry, leading to dimers. The combination of the two interactions gives rise to rings, each comprising six molecules, which are part of infinite sheets in the bc plane.

Enantioselective reduction of prochiral ketones by catecholborane catalysed by chiral group 13 complexes

LiGaH4, in combination with the S,O-chelate 2-hydroxy-2'-mercapto-1,1'-binaphthyl (MTBH2), forms an active catalyst for the asymmetric reduction of prochiral ketones, with catecholborane as the hydride source. Enantioface differentiation is on the basis of the steric requirements of the ketone substituents. Aryl/ n-alkyl ketones are reduced in 90-93% ee and RC(O)Me (e.g. R = iPr, cycloC6H11, tBu) in 60-72% ee. Other borane sources and alternative catalyst structures based on indium do not form enantioselective catalysts.

Dichloromaleic anhydride

Although molecules of the title compound, 3,4-dichloro-2,5-dihydrofuran-2,5-dione (dichloromaleic anhydride, C(4)Cl(2)O(3)), (I), possess approximate non-crystallographic C(2v) symmetry, the two chlorine substituents deviate from the ring plane. Their deviations are in the same direction, but with values of 0.0356 (17) and 0.0167 (17) A, they differ significantly in magnitude. The closest intermolecular contact is of 2.888 (2) A between a carbonyl O atom and the C atom of a carbonyl group, with the O.C direction orthogonal to the C=O bond [O5.C2(i)=O2(i) 93.6 (2) degrees; symmetry code: (i) $3 \over 2$ - x, -(1/2) + y, z]. These contacts form infinite chains of molecules running parallel to the crystallographic b direction.

A family of polynuclear cobalt and nickel complexes stabilised by 2-pyridonate and carboxylate ligands

The synthesis and structural characterisation of a series of cobalt and nickel cages are reported. Eight of these structures contain a [M10(mu3-OH)6(eta2, mu3-xhp),(eta2, mu2-O2CR)6]2+ core (where M = Co or Ni; xhp = 6-chloro- or 6-methyl-2-pyridonate: R = Me, Ph, CHMe2, CH2Cl, CHPh2 or CMe3), where the ten metal atoms describe a centred-tricapped-trigonal prism (ttp). The cage contains six hydroxide ligands around the central metal, and the exterior is coated with pyridonate and carboxylate ligands. For four of the cages additional metal centres are found attached to the upper and/or lower triangular faces of the trigonal prism, generating dodeca- and undecanuclear cages. Three further cages are reported that contain a metal core based on an incomplete centred-tetraicosahedron. These cages involve trimethylacetate as a ligand in company with either 6-methyl-2-pyridonate or 6-chloro-2-pyridonate. Comparison of these latter structures with the trigonal prisms reveal that they can be described as a pentacapped-trigonal prism missing one edge. Magnetic studies of three of the nickel cages with trigonal prismatic cores show spin ground states of S = 8, 4 and 2 for Ni12, Ni11 and Ni10 cages, respectively.

Theory of Reasoned Action predicts milk consumption in women

OBJECTIVE

To determine the factors influencing the consumption or avoidance of milk in women.

SUBJECTS/SETTING

One hundred women completed food frequency questionnaires and a milk attitudes questionnaire framed within the Theory of Reasoned Action and performed sensory evaluations of different milk samples.

STATISTICAL ANALYSES

Differences among milk types were assessed using 2-way analysis of variance and least-significant-difference mean comparison procedures. Correlation and multiple regression analyses, and standardized partial regression coefficients, were used to determine the contribution of each component of the model in predicting behavior.

RESULTS

Mean age of the 100 subjects was 39 years (range = 20-70 years). Milk consumption among subjects was low; 23 subjects indicated that they seldom or never drank milk. Data from the dairy frequency questionnaire showed that the primary milk for 42%, 36%, 27%, and 18% of the milk drinkers was skim, 2%, 1%, and whole, respectively (subjects could indicate more than 1 type of milk consumed). The Theory of Reasoned Action indicated that health and familiarity belief items were most associated with attitudes toward milk consumption. Skim milk had significantly lower scores for taste and texture belief items than 1%, 2%, and whole milk (P < .05), yet more subjects reported that they drank skim milk (42%) than the other milk types. Sensory evaluation demonstrated that subjects linked whole milk significantly more than skim milk (P < .05).

CONCLUSIONS/APPLICATIONS

Some people continue to consume skim milk for reasons other than beliefs about taste and texture or actual sensory preference. This study identifies important factors contributing to milk consumption such as beliefs, attitudes, and sensory evaluation, which can be used to develop a specific framework in which to examine other components of milk consumption behavior.

Falls in the elderly

Falls are a common cause of admission to a geriatric unit, and yet the approach to the elderly faller remains unsatisfactory. This article outlines the epidemiology of falls, the age-related physiological changes that may contribute to the risk of falling and the classification and causes of falls, and discusses the evaluation and management of this problem.

Structure of the thromboxane receptor antagonist EP 092

7-(3-[1-(4-Phenylthiosemicarbazono)ethyl]-bicyclo[2.2.1]hept-2- yl)-5-heptenoic acid, C23H31N3-O2S, Mr = 413.7, monoclinic, P2(1)/a, a = 12.9650 (7), b = 11.2081 (6), c = 16.8941 (12) A, beta = 110.452 (5) degrees, V = 2300.2 A3, Z = 4, Dx = 1.194 g cm-3, Mo K alpha, lambda = 0.71073 A, mu = 1.55 cm-1, F(000) = 888, T = 298 K. Final R = 0.0472 with 2778 independent data. EP 092 is a thromboxane receptor antagonist akin to many other analogues of the thromboxane A2 [Wilson & Jones (1985). Adv. Prostaglandin Thromboxane Leukotriene Res. 14, 393-425].

Falls by elderly people at home: prevalence and associated factors

Of 1042 individuals aged 65 years and over who were successfully interviewed in a community survey of health and physical activity, 35% (n = 356) reported one or more falls in the preceding year. Although the overall ratio of female fallers to male fallers was 2.7:1, this ratio approached unity with advancing age. Mobility was significantly impaired in those reporting falls. Asked to provide a reason for their falls, 53% reported tripping, 8% dizziness and 6% reported blackouts. A further 19% were unable to give a reason. There was no association between falls and the use of diuretics, antihypertensives or tranquilizers, but a significant association between falls and the use of hypnotics and antidepressants was found. Discriminant analysis of selected medical and anthropometric variables indicated that handgrip strength in the dominant hand and reported symptoms of arthritis, giddiness and foot difficulties were most influential in predicting reports of recent falls.

The extent of individual responsibility for an independent old age

Encouragement of a degree of personal responsibility for the maintenance of health by individuals and communities is being increasingly advocated by planners of health care. With the increasing numbers of people reaching old age it is particularly desirable that individuals be made aware of potential measures that may ensure a reasonably independent old age. In the course of a study to identify the defining characteristics of referred geriatric patients in a teaching hospital, a number of recurring factors emerged that seemed to favour the retention of independence among the subjects studied as controls. These were adequate retirement planning, the timely development of satisfying interests, the prior adoption of a healthy lifestyle, the sensible use of health services and the presence of adequate family and community support systems. Six cases are described to illustrate the presence or absence of such factors, and these are discussed against the background of the respective degrees of responsibility to be expected of the individual and of society in securing and maintaining independence in old age.

Identification and definition of the geriatric patient in a teaching hospital

A consulting service in geriatric medicine was established at Groote Schuur Hospital on 1 November 1981. The first 100 patients referred were compared with 100 patients of 65 years of age and over, selected randomly from the wards from which the referrals were coming, with a view to identifying characteristics of the geriatric patient appropriate to local needs. The findings are discussed against a background of the requirements for adequate care of the elderly, the need to teach geriatric medicine to those whose functions include care of the elderly, and some of the wider social implications in ensuring as equitable a distribution of service as possible. In conclusion a definition of the geriatric patient is offered.

A Lamp for Cancer Phototherapy

The lamp described comprises a 1000 W incandescent filament source, long- and short-wave pass filters, and a non-imaging reflector system. The output of 24 W in the 620-720 nm band is delivered through a 53 mm diameter aperture with a maximum divergence half-angle of 60�. Refracting components may be fitted to modify the output angular or intensity distribution. This lamp has been used to irradiate several different types of malignant tumour in human patients, following intravenous injection of the photoactive drug haematoporphyrin derivative, causing selective necrosis of the malignant tissue. The clinical results are regarded as encouraging.

Phototherapy of human tumours using haematoporphyrin derivative

Photoradiation therapy (phototherapy) is a recently introduced treatment for malignant tumours, which depends on the activation of a photoreactive drug selectively localized to tumours. An experience in 27 patients with haematoporphyrin derivative is described. The haematoporphyrin derivative was activated by light of 630-nm wavelength, which was delivered to cutaneous tumours from a specially designed incandescent lamp and to deep tumours through a quartz fibre from a laser system. Tumours were eradicated in five patients and incomplete tumour destruction was observed in 14 others. The only significant side effect was temporary cutaneous photosensitivity. This form of treatment has considerable potential, particularly when other treatments have either failed or cannot be applied. However, it is premature to formulate indications for its use. Rapid technological developments can be anticipated which will greatly enhance the efficacy of photodynamic destruction of tumours.