Infective keratitis in soft contact lens wearers.

Eight cases of infective keratitis are reported in wearers of soft contact lenses. Four of them had normal eyes and were wearing lenses on a continual basis. One was wearing a lens continually for therapeutic reasons. Three others were wearing lenses daily or intermittently. The four latter cases were using contaminated lens solutions. Two of the continual lens wearers lost vision to the point of blindness. A significant factor in their bad outcome was the fact that both lived in areas remote from adequate ophthalmic services. Serratia liquefaciens was implicated in one case. This is thought to be the only reported case of corneal abscess due to this organism in the past 16 years. S. marcescens was grown in another case from the lens solutions and carrying case.     

Evidence that autobiographic memory retrieval does not become independent of the hippocampus: an fMRI study contrasting very recent with remote events

Traditional consolidation theory, which seeks to explain how new memories are incorporated into the preexisting neural architecture, stipulates that the hippocampus plays a time-limited role in this process. However, although there is abundant research showing that the hippocampus is necessary for the initial (encoding) phase, there is very little experimental evidence with human subjects proving that the structure ceases to play a role in the retrieval of episodic items from memory stores. To test this hypothesis, we investigated recall activation associated with recent memories (2.5 days) versus remote memories (mean of 8 years) using functional magnetic resonance imaging. In accordance with the multiple memory trace theory, recall of consolidated autobiographic information, represented by the remote condition, was not independent of the hippocampus. Both types of memory retrieval produced significant activation in parahippocampal, prefrontal, and midtemporal gyri, the parietal-temporal junction, and a medial region of cortex spanning the posterior cingulate and precuneus gyri. However, where recent events activated bilateral regions of the caudate nucleus, remote events yielded significantly greater activation within the hippocampus proper. The results challenge traditional consolidation theory, which would predict greater hippocampal activity for recent events. Furthermore, they highlight the interplay between multiple memory systems in the brain. We argue that our particular question format, which encouraged depth of recall and did not require a prescan interview, as well as our delineation of the recent and remote time periods, were the determining factors for the observed pattern of hippocampal activation.     

Hippocampal dampening during a relational memory task

The hippocampus (HPC) has an essential role in relational memory. One task used to test relational memory is the transverse patterning (TP) problem (A+ B-, B+ C-, and C+ A-), which is sensitive to HPC damage across species. Using functional magnetic resonance imaging in humans, the authors observed activation maps and time course data indicating that the HPC is involved in this task, but it is paradoxically less active during the hippocampal-dependent relational memory phase relative to both a hippocampal-independent control memory phase and to a fixation control phase. This suggests that traditional assumptions suggesting that brain regions critical for a task must produce an increased blood oxygen level-dependent response during performance of that task are probably inaccurate and alternative explanations should be entertained.     

Attitudes and roles of general practitioners in the treatment of schizophrenia compared with community mental health staff and patients

Abstract. Background: Most general practitioners (GPs) are currently treating a small number of patients with schizophrenia; however, little is known about GPs experiences in this area. This paper examines the attitudes and roles of Australian GPs in the treatment of schizophrenia and their relationships with specialist services. Methods: A total of 192 GPs ratings of possible sources and forms of help for patients with schizophrenia were compared with the ratings of 50 mental health services (MHS) staff and 129 patients. Comparisons within the health professionals were also made in relation to diagnostic and treatment confidence, perceived roles, and typical problems encountered. Results: Perceived helpfulness ratings were reasonably consistent across groups. However, patients tended to rank close family members as more helpful. GPs and MHS staff reported complementary roles, with a shared responsibility for early detection and relapse prevention. Treatment compliance, and communication and accessibility to specialist agencies were identified as major problems. Conclusions: GPs fulfil a valuable role in the treatment of schizophrenia, which could be enhanced through improved training. Mental health services need to work more effectively with GPs in treating schizophrenia and acknowledge their complementary roles.     

Retinal Microvascular Patency in the Diabetic Rat

To study whether the patency to erythrocytes in retinal microvessels of diabetic rats is reduced or blocked before the vessels lose their patency to plasma flow. Methods: We used recognized techniques to induce diabetic and galactose related microvascular retinal lesions in rats: (1) alloxan induction (2) streptozotocin induction (3) galactose-containing diet. The rats were followed up to 17 months. We used our vascular trichrome technique to observe the effects of the ongoing diabetes on the retinal microcirculation. Results: A focal leakage of a plasma-borne fluorescent dye was noted around the junction of the deep retinal capillaries and the ascending venules to the superficial retinal circulation in the streptozotocin and alloxan diabetic rats by the 14th month, and, by the 16th month, retinal capillary non-perfusion and retinal vascular malformations were present. The affected vessels showed patency to microspheres (0.2 μm in diameter) but no perfusion of erythrocytes. No such changes were seen in the galactose-fed rats. Conclusions: (1) The location between the deep retinal capillary net and the ascending venules may be the site of early vascular leakage in the diabetic rat model, (2) the erythrocytes’ passage in the affected retinal microcirculation was blocked before the development of complete blockage to plasma in diabetic rats. The logical assumption that during the development stage of retinal capillary occlusion there may be a transient stage of microvascular insufficiency was examined. The lathyrogen, imino-diproprionitrile (IDPN), had previously been effective for creating a fast-developing model of retinal vasculopathy. Using that model, we demonstrated a stage in which the retinal microvasculature was blocked to erythrocytes but not to plasma [1]. However, we questioned the applicability of our findings to more slowly developing microvasculopathies, such as diabetic retinopathy. We designed the current study to examine the presence of such stage in slowly developing microvasculopathy. Animal models that are known to induce “diabetic retinopathy-like” changes used [2–4]. The diabetic animals were followed for a period of 17 months. Starting at the 12th month, a few animals of each group were killed and the retains were examined with our trichrome method [1] for relative capillary patency to erythrocytes and plasma, for functionality of endothelial cells, and for disturbances in the blood–retinal barrier. The results of this study support the hypothesis that retinal microvascular insufficiency does exist as a temporary stage that precedes the development of complete capillary blockage in long-term developing rat models of diabetic retinopathy.     

Beta irradiation: new uses for an old treatment: a review

Beta radiation has a long history as a treatment modality in ophthalmology. It is a convenient and practical method of applying radiation and has the advantage of minimal tissue penetration. There has been a recent resurgence in the use of beta radiation in other areas in medicine, such as the prevention of restenosis after coronary artery stenting. Beta radiation has been shown in vitro and in vivo to inhibit proliferation of human Tenon's fibroblasts, which enter a period of growth arrest but do not die. Effects on the cell cycle controller p53 have been shown to be important in this process. In ophthalmology, beta radiation has been used widely for the treatment of pterygium and is under evaluation for treatment of age-related macular degeneration and for controlling wound healing after glaucoma drainage surgery. In this latter role, beta radiation may be particularly appropriate for use in developing countries to improve the results of trabeculectomy while potentially avoiding some of the side effects of other antimetabolites.     

ROC analysis of statistical methods used in functional MRI: individual subjects

The complicated structure of fMRI signals and associated noise sources make it difficult to assess the validity of various steps involved in the statistical analysis of brain activation. Most methods used for fMRI analysis assume that observations are independent and that the noise can be treated as white gaussian noise. These assumptions are usually not true but it is difficult to assess how severely these assumptions are violated and what are their practical consequences. In this study a direct comparison is made between the power of various analytical methods used to detect activations, without reference to estimates of statistical significance. The statistics used in fMRI are treated as metrics designed to detect activations and are not interpreted probabilistically. The receiver operator characteristic (ROC) method is used to compare the efficacy of various steps in calculating an activation map in the study of a single subject based on optimizing the ratio of the number of detected activations to the number of false-positive findings. The main findings are as follows: Preprocessing. The removal of intensity drifts and high-pass filtering applied on the voxel time-course level is beneficial to the efficacy of analysis. Temporal normalization of the global image intensity, smoothing in the temporal domain, and low-pass filtering do not improve power of analysis. Choices of statistics. the cross-correlation coefficient and t-statistic, as well as nonparametric Mann-Whitney statistics, prove to be the most effective and are similar in performance, by our criterion. Task design. the proper design of task protocols is shown to be crucial. In an alternating block design the optimal block length is be approximately 18 s. Spatial clustering. an initial spatial smoothing of images is more efficient than cluster filtering of the statistical parametric activation maps.     

Physiological arousal and sensation-seeking in female fruit machine gamblers

Aims. To examine changes in physiological arousal, as indexed by heart rate, during fruit machine gambling while controlling for the confounding effect of movement and as a function of winning and losing, and to examine relationships between sensation-seeking, self-reported arousal during gambling, heart rate during gambling and frequency of gambling. Sample, design and measurements. Heart rate and subjective arousal were recorded in a sample of 32 female fruit machine players before, during and after the gambling process. At baseline measures were taken of sensation-seeking, self-reported arousal during gambling and frequency of gambling. A simulation of the behaviour used to operate fruit machines was used during baseline measurement. Findings. Significant increases in heart-rate over movement controlled baselines were observed within participants during gambling, but only in those who won during play. No correlations between HR levels and subjective arousal were found. However, striking negative correlations between sensation-seeking and frequency of gambling, and between subjective arousal and frequency were present. Conclusions. Gambling alone is not enough to induce increases in HR levels for female fruit machine gamblers; the experience of winning or the anticipation of that experience is necessary to increase HR levels. In addition sensation-seeking appears to be negatively associated with this kind of gambling behaviour.