Integrating infection control into the dental curriculum

The dental profession has possessed traditional standards of cross-infection control but the recent expression of real concerns by both the public and the profession over the transmissibility of infectious diseases in the dental surgery has demanded a formalized and extended approach to teaching cross-infection control in the dental curriculum. Clear curriculum content must be formulated within contemporary Workplace Health and Safety Guidelines and the Strategic Plan of the Dental School or academic health centre. The full integration demands that the area is taught as a discrete entity but recognized as an intrinsic part of each clinical encounter. This paper discusses the structure and integration of cross-infection control into the curriculum at the University of Queensland Dental School.

When oceans meet: a teleost shows secondary intergradation at an Indian-Pacific interface

The Indo-West Pacific is characterized by extraordinary marine species diversity. The evolutionary mechanisms responsible for generating this diversity remain puzzling, but are often linked to Pleistocene sea level fluctuations. The impact of these sea level changes on the population genetic architecture of the estuarine fish Lates calcarifer are investigated via a natural experiment in a region of the Indo-West Pacific known to have undergone considerable change during the Pleistocene. L. calcarifer, a coastline-restricted catadromous teleost, provides an excellent model for studying the effects of sea level change as its habitat requirements potentially make it sensitive to the region's physical history. Evidence was found for a large phylogenetic break (4% mtDNA control region; 0.47% ATPase 6 and 8) either side of the Torres Strait, which separates the Western Pacific and Indian Oceans, although some mixing of the clades was evident. This suggests clinal secondary introgression of the clades via contemporary gene flow. Further, populations on Australia's east coast appear to have passed through a bottleneck. This was linked to the historical drying of the Great Barrier Reef coastal lagoon, which resulted in a significant loss of habitat and forced retreat into isolated refugia. These results suggest that historical eustatic changes have left a significant imprint on the molecular diversity within marine species as well as among them in the Indo-West Pacific.

Adjustment to a low-control situation: Reexamining the role of coping responses

The aim of the study was to test a revised conceptualization of the role of coping in adjustment to a low-control stressor-women's adjustment to a failed in vitro fertilization (NF) attempt. Data were collected prior to the IVF treatment (Time I) and twice after the failed NF attempt (1 to 2 weeks after finding out the results, n = 171, and fi weeks later, n = 139). Initial adjustment was assessed at Time I, whereas measures of coping and both self-report and partner ratings of adjustment were obtained at Times ? and 3. As predicted, escapist strategies and problem-management strategies (mainly at Time ?) were associated with poor adjustment, whereas problem-appraisal coping was associated with better adjustment., There was also support for the proposed positive relationship between adjustment and emotional approach coping (on self-report adjustment).

The deep-sea teleost cornea: a comparative study of gadiform fishes

The corneal structure of three deep-sea species of teleosts (Gadiformes, Teleostei) from different depths (250-4000 m) and photic zones are examined at the level of the light and electron microscopes. Each species shows a similar but complex arrangement of layers with a cornea split into dermal and scleral components. The dermal cornea comprises an epithelium overlying a basement membrane and a dermal stroma with sutures and occasional keratocytes. Nezumia aequalis is the only species to possess a Bowman's layer, although it is not well-developed. The scleral cornea is separated from the dermal cornea by a mucoid layer and, in contrast to shallow-water species, is divided into three main layers; an anterior scleral stroma, a middle or iridescent layer and a posterior scleral stroma. The iridescent layer of collagen and intercalated cells or cellular processes is bounded by a layer of cells and the posterior scleral stroma overlies a Descemet's membrane and an endothelium. In the relatively shallow-water Microgadus proximus, the keratocytes of the dermal stroma, the cells of the iridescent layer and the endothelial cells all contain aligned endoplasmic reticulum, which may elicit an iridescent reflex. No alignment of the endoplasmic reticulum was found in N. aequalis or Coryphanoides (Nematonurus) armatus. The relative differences between shallow-water and deep-sea corneas are discussed in relation to the constraints of light, depth and temperature.

Amino acid synthesis in the symbiotic sea anemone Aiptasia pulchella

Symbiotic Aiptasia pulchella and freshly isolated zooxanthellae were incubated in (NaHCO3)-C-14 and NH4Cl for 1 to 240 min, and samples were analysed by reverse-phase high-performance liquid chromatography (HPLC) and an online radiochemical detector. NH4+ was first assimilated into C-14-glutamate and C-14-glutamine in the zooxanthellae residing in A. pulchella. The specific activities (dpm nmol(-1)) of C-14-glutamate and C-14-glutamine in vivo, were far greater in the zooxanthellae than in the host tissue, indicating that NH4+ was principally incorporated into the glutamate and glutamine pools of the zooxanthellae. C-14-alpha-ketoglutarate was taken up from the medium by intact A. pulchella and assimilated into a small amount of C-14-glutamate in the host tissue, but no C-14-glutamine was detected in the host fraction. The C-14-glutamate that was synthesized was most likely produced from transamination reactions as opposed to the direct assimilation of NH4+. The free aminoacid composition of the host tissue and zooxanthellae of A. pulchella was also measured. The results presented here demonstrate that NH4+ was initially assimilated by the zooxanthellae of A. pulchella.

Seven retinal specializations in the tubular eye of the deep-sea pearleye, Scopelarchus michaelsarsi: A case study in visual optimization

The deep-sea pearleye, Scopelarchus michaelsarsi (Scopelarchidae) is a mesopelagic teleost with asymmetric or tubular eyes. The main retina subtends a large dorsal binocular field, while the accessory retina subtends a restricted monocular field of lateral visual space. Ocular specializations to increase the lateral visual field include an oblique pupil and a corneal lens pad. A detailed morphological and topographic study of the photoreceptors and retinal ganglion cells reveals seven specializations: a centronasal region of the main retina with ungrouped rod-like photoreceptors overlying a retinal tapetum; a region of high ganglion cell density (area centralis of 56.1x10(3) cells per mm(2)) in the centrolateral region of the main retina; a centrotemporal region of the main retina with grouped rod-like photoreceptors; a region (area giganto cellularis) of large (32.2+/-5.6 mu m(2)), alpha-like ganglion cells arranged in a regular array (nearest neighbour distance 53.5+/-9.3 mu m with a conformity ratio of 5.8) in the temporal main retina; an accessory retina with grouped rod-like photoreceptors; a nasotemporal band of a mixture of rod-and cone-like photoreceptors restricted to the ventral accessory retina; and a retinal diverticulum comprised of a ventral region of differentiated accessory retina located medial to the optic nerve head. Retrograde labelling from the optic nerve with DiI shows that approximately 14% of the cells in the ganglion cell layer of the main retina are displaced amacrine cells at 1.5 mm eccentricity. Cryosectioning of the tubular eye confirms Matthiessen's ratio (2.59), and calculations of the spatial resolving power suggests that the function of the area centralis (7.4 cycles per degree/8.1 minutes of are) and the cohort of temporal alpha-like ganglion cells (0.85 cycles per degree/70.6 minutes of are) in the main retina may be different. Low summation ratios in these various retinal zones suggests that each zone may mediate distinct visual tasks in a certain region of the visual field by optimizing sensitivity and/or resolving power.

Peptidergic control of gastrointestinal blood flow in the estuarine crocodile, Crocodylus porosus

Peptidergic mechanisms influencing the resistance of the gastrointestinal vascular bed of the estuarine crocodile, Crocodylus porosus, were investigated. The gut was perfused in situ via the mesenteric and the celiac arteries, and the effects of different neuropeptides were tested using bolus injections. Effects on vascular resistance were recorded as changes in inflow pressures. Peptides found in sensory neurons [substance P, neurokinin A, and calcitonin gene-related peptide (CGRP)] all caused significant relaxation of the celiac vascular bed, as did vasoactive intestinal polypeptide (VIP), another well-known vasodilator. Except for VIP, the peptides also induced transitory gut contractions. Somatostatin and neuropeptide Y (NPY), which coexist in adrenergic neurons of the C. porosus, induced vasoconstriction in the celiac vascular bed without affecting the gut motility. Galanin caused vasoconstriction and occasionally activated the gut wall. To elucidate direct effects on individual vessels, the different peptides were tested on isolated ring preparations of the mesenteric and celiac arteries. Only CGRP and VIP relaxed the epinephrine-precontracted celiac artery, whereas the effects on the mesenteric artery were variable. Somatostatin and NPY did not affect the resting tonus of these vessels, but somatostatin potentiated the epinephrine-induced contraction of the celiac artery. Immunohistochemistry revealed the existence and localization of the above-mentioned peptides in nerve fibers innervating vessels of different sizes in the gut region. These data support the hypothesis of an important role for neuropeptides in the control of the vascular bed of the gastrointestinal tract in C. porosus.

Experimental control of single-mode laser chaos by using continuous, time-delayed feedback

Control of chaos in the single-mode optically pumped far-infrared (NH3)-N-15 laser is experimentally demonstrated using continuous time-delay control. Both the Lorenz spiral chaos and the detuned period-doubling chaos exhibited by the laser have been controlled. While the laser is in the Lorenz spiral chaos regime the chaos has been controlled both such that the laser output is cw, with corrections of only a fraction of a percent necessary to keep it there, and to period one. The laser has also been controlled while in the period-doubling chaos regime, to both the period-one and -two states.

An experimental study of the effects of work stress, work control, and task information on adjustment

The present study was designed to examine the main and interactive effects of task demands, work control, and task information on levels of adjustment. Task demands, work control, and task information were manipulated in an experimental setting where participants completed a letter-sorting activity (N = 128). Indicators of adjustment included measures of positive mood, participants' perceptions of task performance, and task satisfaction. Results of the present study provided some support for the main effects of objective task demands, work control, and task information on levels of adjustment. At the subjective level of analysis, there was some evidence to suggest that work control and task information interacted in their effects on levels of adjustment. There was minimal support for the proposal that work control and task information would buffer the negative effects of task demands on adjustment. There was, however, some evidence to suggest that the stress-buffering role of subjective work control was more marked at high, rather than low, levels of subjective task information.

The eyes of deep-sea fish I: Lens pigmentation, tapeta and visual pigments

Deep-sea fish, defined as those living below 200 m, inhabit a most unusual photic environment, being exposed to two sources of visible radiation: very dim downwelling sunlight and bioluminescence, both of which are, in most cases. maximal at wavelengths around 450-500 nm. This paper summarises the reflective properties of the ocular tapeta often found in these animals the pigmentation of their lenses and the absorption characteristics of their visual pigments. Deepsea tapeta usually appear blue to the human observer. reflecting mainly shortwave radiation. However, reflection in other parts of the spectrum is not uncommon and uneven tapetal distribution across the retina is widespread. Perhaps surprisingly, given the fact that they live in a photon limited environment, the lenses of some deep-sea teleosts are bright yellow, absorbing much of the shortwave part of the spectrum. Such lenses contain a variety of biochemically distinct pigments which most likely serve to enhance the visibility of bioluminescent signals. Of the 195 different visual pigments characterised by either detergent extract or microspectrophotometry in the retinae of deep-sea fishes, cn. 87% have peak absorbances within the range 468-494 nm. Modelling shows that this is most likely an adaptation for the detection of bioluminescence. Around 13% of deep-sea fish have retinae containing more than one visual pigment. Of these, we highlight three genera of stomiid dragonfishes, which uniquely produce far red bioluminescence from suborbital photophores. Using a combination of longwave-shifted visual pigments and in one species (Malacosteus niger) a chlorophyll-related photosensitizer. these fish have evolved extreme red sensitivity enabling them to see their own bioluminescence and giving them a private spectral waveband invisible to other inhabitants of the deep-ocean. (C) 1998 Elsevier Science Ltd. All rights reserved.

The eyes of deep-sea fish II. Functional morphology of the retina

Three different aspects of the morphological organisation of deep-sea fish retinae are reviewed: First, questions of general cell biological relevance are addressed with respect to the development and proliferation patterns of photoreceptors, and problems associated with the growth of multibank retinae, and with outer segment renewal are discussed in situations where there is no direct contact between the retinal pigment epithelium and the tips of rod outer segments. The second part deals with the neural portion of the deep-sea fish retina. Cell densities are greatly reduced, yet neurohistochemistry demonstrates that all major neurotransmitters and neuropeptides found in other vertebrate retinae are also present in deep-sea fish. Quantitatively, convergence rates in unspecialised parts of the retina are similar to those in nocturnal mammals. The differentiation of horizontal cells makes it unlikely that species with more than a single visual pigment are capable of colour vision. In the third part. the diversity of deep-sea fish retinae is highlighted. Based on the topography of ganglion cells, species are identified with areae or foveae located in various parts of the retina, giving them a greatly improved spatial resolving power in specific parts of their visual fields. The highest degree of specialisation is found in tubular eyes. This is demonstrated in a case study of the scopelarchid retina, where as many as seven regions with different degrees of differentiation can be distinguished, ranging from an area giganto cellularis, regions with grouped rods to retinal diverticulum. (C) 1998 Elsevier Science Ltd. All rights reserved.

Efficacy of zeta-cypermethrin as pour-on or spray formulations for the control of buffalo fly (Haematobia irritans exigua) in cattle

Objective To determine the efficacy of zeta-cypermethrin in controlling buffalo fly (Haematobia irritans exigua). Design Five field trials in northern and central Queensland. Procedure Zeta-cypermethrin pour-on at 2.5 mg/kg, spray at 62.5 ppm, deltamethrin pour-on and pour-on vehicle were applied to groups of 20 cattle. Buffalo fly counts were conducted three times before treatment and 3, 7, 14, 21, 28 and 35 days after treatment. Results In central Queensland where synthetic pyrethroid resistance in buffalo fly populations was rare, 2.5 mg/kg of zeta-cypermethrin pour-on gave good control of buffalo fly for 4 weeks and was better than a deltamethrin product. A zeta-cypermethrin spray used at 62.5 ppm gave 14 days control. In far-north Queensland where resistance to synthetic pyrethroids and heavy rain was common, the maximum period of efficacy of zeta-cypermethrin pour-on was reduced to 2 weeks. Conclusion In areas where there is low resistance to synthetic pyrethroids among buffalo flies, zeta-cypermethrin pour-on can be expected to give good control for 4 weeks.