Association of Metformin With the Development of Age-Related Macular Degeneration

Importance

Age-related macular degeneration (AMD) is a leading cause of blindness with no treatment available for early stages. Retrospective studies have shown an association between metformin and reduced risk of AMD.

Objective

To investigate the association between metformin use and age-related macular degeneration (AMD).

Design, Setting, and Participants

The Diabetes Prevention Program Outcomes Study is a cross-sectional follow-up phase of a large multicenter randomized clinical trial, Diabetes Prevention Program (1996-2001), to investigate the association of treatment with metformin or an intensive lifestyle modification vs placebo with preventing the onset of type 2 diabetes in a population at high risk for developing diabetes. Participants with retinal imaging at a follow-up visit 16 years posttrial (2017-2019) were included. Analysis took place between October 2019 and May 2022.

Interventions

Participants were randomly distributed between 3 interventional arms: lifestyle, metformin, and placebo.

Main Outcomes and Measures

Prevalence of AMD in the treatment arms.

Results

Of 1592 participants, 514 (32.3%) were in the lifestyle arm, 549 (34.5%) were in the metformin arm, and 529 (33.2%) were in the placebo arm. All 3 arms were balanced for baseline characteristics including age (mean [SD] age at randomization, 49 [9] years), sex (1128 [71%] male), race and ethnicity (784 [49%] White), smoking habits, body mass index, and education level. AMD was identified in 479 participants (30.1%); 229 (14.4%) had early AMD, 218 (13.7%) had intermediate AMD, and 32 (2.0%) had advanced AMD. There was no significant difference in the presence of AMD between the 3 groups: 152 (29.6%) in the lifestyle arm, 165 (30.2%) in the metformin arm, and 162 (30.7%) in the placebo arm. There was also no difference in the distribution of early, intermediate, and advanced AMD between the intervention groups. Mean duration of metformin use was similar for those with and without AMD (mean [SD], 8.0 [9.3] vs 8.5 [9.3] years; P = .69). In the multivariate models, history of smoking was associated with increased risks of AMD (odds ratio, 1.30; 95% CI, 1.05-1.61; P = .02).

Conclusions and Relevance

These data suggest neither metformin nor lifestyle changes initiated for diabetes prevention were associated with the risk of any AMD, with similar results for AMD severity. Duration of metformin use was also not associated with AMD. This analysis does not address the association of metformin with incidence or progression of AMD.

A Combined Theory of Change-Group Model Building Approach to Evaluating “Farm to Fork” Models for School Feeding in the Caribbean

There is a scarcity of research on building nutrition-sensitive value chains (NSVCs) to improve diets and nutrition outcomes of populations in the Caribbean. This study contributes to filling this research gap by outlining a participatory approach to evaluating a NSVC model for “farm to fork” (F2F) school feeding in the Eastern Caribbean Island of St. Kitts. Using a combined group model building (GMB) and theory of change (ToC) approach, policy actors and other stakeholders (n = 37) across the school feeding value chain were guided through a facilitated process to evaluate the ToC underlying a series of F2F interventions designed to enhance childhood nutrition. Stakeholders at the workshop engaged collaboratively to create a causal map of interconnected “system factors” that help explain behaviors contributing to unhealthy eating among children that extended well-beyond the original F2F project ToC that had been used to inform interventions. Through this facilitated GMB process, stakeholders proposed additional food system interventions, and identified multiple “impact pathways” and “mediating influences” underlying local availability and consumption of nutritious foods in local school environments. Workshop participants were also able to identify leverage points where community-level efforts, alongside research interventions, may ensure that initiatives for building local NSVCs are ultimately institutionalized. Results of this study suggest that developing NSVCs for school feeding and food systems in the Caribbean requires both locally driven innovation and the leveraging of system-wide resources, with lessons for project intervention strategies.

Abstract P4-16-07: The CHANCE study: Mechanical skin changes among women with non-metastatic breast cancer receiving chemotherapy and endocrine therapy

Background: The persistent effects on skin hydration and elasticity resulting from cytotoxic and endocrine agents used in early stages of breast cancer are poorly understood. The objective of this preliminary analysis of the CHANCE study is to describe the pattern of persistent biomechanical skin changes in non-metastatic breast cancer patients treated with cytotoxic chemotherapies and/or endocrine therapies.

Methods: This is an ongoing single-center, prospective, longitudinal cohort study of non-metastatic breast cancer patients treated with cytotoxic chemotherapies and/or endocrine therapies. Objective skin hydration and elasticity measurements of the forearm were measured using Tewameter® (TM 300; Courage & Khazaka) and Cutometer® (MPA 580; Courage & Khazaka) devices under a controlled ambient environment at baseline and 6 months after chemotherapy completion, or one year after initiation of endocrine therapy.

Results: A total of 107 patients were assessed at baseline and follow-up for transepidermal water loss (TEWL) (median age 53, range 26-82) and 106 patients for skin elasticity (median age 53.5, range 26-82). Fifty-three healthy controls were evaluated at baseline with median age 47 (range, 22-73). The mean TEWL at baseline and follow-up among patients were 6.922 g/h/m2 and 8.521 g/h/m2, respectively (p<.0001). Skin firmness (0.420 versus 0.421 mm, p=0.949) and elasticity (77.2% versus 77.4%, p=0.836) did not significantly change during follow-up. When comparing chemotherapy recipients with endocrine therapy recipients, chemotherapy patients had a mildly lower TEWL at follow-up (8.369 versus 8.928 g/h/m2, p=.247) but a greater net increase in TEWL (1.687 versus 1.359 g/h/m2, p=.5) compared to endocrine patients over the study period.

Conclusions: An increase in TEWL was observed in patients receiving cytotoxic and endocrine therapies, suggesting a deterioration of the protective skin barrier possibly attributed to these therapies. No significant changes in skin firmness or elasticity were found in this preliminary analysis. Further studies are needed to elucidate the pathophysiologic mechanisms involved in persistent skin changes after systemic breast cancer therapies.

Objective skin hydration and elasticity in patients receiving breast cancer therapy Control (n=53)Baseline (n=107)Follow-Up (n=107)p-value*TEWL (g/h/m2)9.4626.9228.521<.0001Cutometer Baseline (n=106)Follow-Up (n=106) Immediate recovery, R0 (mm)0.4150.4200.4210.949Gross elasticity, R2 (%)79.3%77.2%77.4%0.836*p-value calculated from baseline and follow-up only

Citation Format: Lacouture ME, Phillips GS, Freites-Martinez A, Patil S, Samuels A, Shapiro J, Kukoyi O, Goldfarb S. The CHANCE study: Mechanical skin changes among women with non-metastatic breast cancer receiving chemotherapy and endocrine therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-16-07.

Childhood Physical and Sexual Abuse in Caribbean Young Adults and Its Association with Depression, Post-Traumatic Stress, and Skin Bleaching

BACKGROUND

The global prevalence of skin depigmentation/skin bleaching among blacks, estimated at 35%, is on the rise and is associated with a host of negative health and medical consequences. Current etiological approaches do not fully capture the emotional and psychological underpinnings of skin bleaching. The current study investigated the potential mediating role of depression, or post-traumatic stress symptoms (avoidance and hyperarousal) on the relationship between childhood physical and sexual abuse (CPSA) and skin bleaching.

METHODS

A total of 1226 university participants (ages 18-30 years and 63.4% female) from three Caribbean countries (Jamaica, Barbados, and Grenada) provided data for the current analysis. They all completed self-reported measures of general demographic information along with the short screening scale for posttraumatic stress disorder (DSM-IV), childhood trauma, and skin bleaching questions.

RESULTS

The prevalence of skin bleaching in our study was 25.4%. Our findings showed that individuals who bleached their skin were more likely to have been abused as children (21.6% versus 13.5%, p<0.001), were more likely to have significant symptoms of trauma (34.1% versus 24.0%, p=0.005), and were more likely to have significant depression (43.7% versus 35.1%, p=0.032). We found that trauma-related hyperarousal symptoms positively mediated the relationship between childhood physical and sexual abuse and skin bleaching (Indirect Effect=0.03, p<0.05), while avoidance (Indirect Effect=0.000, p>0.05) and depressive (Indirect Effect=0.005, p>0.05) symptoms did not.

CONCLUSION

The presence of trauma symptoms and childhood physical and sexual abuse (CPSA) may increase the likelihood of skin bleaching. Findings suggest that further exploration is needed to ascertain if the presence of skin bleaching warrants being also screened for trauma.

The compassionate taking of life and assisted suicide

Mercy killing. Assisted suicide. The dependent patient. Withholding treatment. The practice of medicine and the civil and criminal law. Legal protection for patients and doctors. The role of judges. The role of politicians.

Penile modification in young Thai men: risk environments, procedures and widespread implications for HIV and sexually transmitted infections

OBJECTIVES

To determine the prevalence and types of penile modification and describe the circumstances surrounding this practice among a sample of young methamphetamine users in Thailand.

METHODS

A mixed methods study was conducted in Chiang Mai, Thailand, in 2005-6. One hundred young men were surveyed for the quantitative study and in-depth interviews were administered to 9 men, 11 women and 1 transgender.

RESULTS

The prevalence of penile modification was 51%, with the most common type being inlaying with muk(s) (61%). The majority of modifications were performed in prison or juvenile detention (80%) by a friend (90%). Motivations for penile modification included peer pressure and perceived enhanced female sexual pleasure. In prison, the practice was veiled in secrecy, the conditions under which modification was performed were unhygienic, sometimes leading to infection, and sharing equipment was common. Men and women reported that condom use was more difficult post modification as condoms were more likely to break or leak and less likely to fit correctly. In addition, sexual intercourse was often painful for the female partner.

CONCLUSION

Penile modification is prevalent in this group of young methamphetamine users and is associated with behaviours and consequences that could facilitate the spread of HIV and other sexually transmitted infections.

A lawyer, thinking of the neuro fraternity, reflects upon recent judicial decisions

This article presents a general review of medico-legal issues that have recently come before the Judges, e.g. consent, negligence, warning the patient of the risks and the convincing expert.

Glass ionomer as an expander of allograft in revision arthroplasty of the hip

The use of glass ionomer as a bone graft expander was investigated in an in vivo model of revision hip arthroplasty. Bone grafts of pure allograft and allograft + glass ionomer particles in a 50:50 by weight mixture were implanted in an ovine hemi-arthroplasty model. Post-operative assessments of locomotor function, radiographic appearance and quantitative changes in mineralisation around the graft were made at 2, 4 and 6 months. Post-mortem assessments of radiographic and histologic appearance of the grafts were made at 6 months. No significant differences were noted in any of the measured or assessed parameters between the two graft types. The glass ionomer particles seemed to be well tolerated within the matrix of new bone, smaller sized particles appearing to be better incorporated than larger ones. The use of particles of glass ionomer as a bone graft expander, in this in vivo model of revision hip arthroplasty, would therefore appear to offer no detriment in performance over pure allograft in the short to medium term.

Effects of combination therapy with PTH and 17beta-estradiol on long bones of female mice

Parathyroid hormone (PTH) is thought to increase trabecular bone mass in postmenopausal women by stimulating osteoblast function. A similar action may contribute to estrogen's protective effect on the skeleton, which we have explored in female mice, in which estrogen induces an exaggerated osteogenic response. In the present investigation, we used this model to determine whether an interaction exists between stimulatory effects of PTH and estrogen on osteoblast function in cancellous bone. An initial dose response study was performed where PTH (hPTH, 1-38) was administered to ten-week-old intact female mice by daily sc injection for 28 days, at doses of 1, 10, 100 microg/kg. In a subsequent study, intact female mice were given PTH and/or 17beta-estradiol (E2) 10 and 40 microg/kg/day respectively. Femoral BMD was assessed by peripheral DXA (PIXImus), and histomorphometry was performed to analyse changes in cancellous and cortical bone. PTH caused a small gain in femoral BMD, and increased the extent of periosteal bone formation surfaces, but had relatively little effect on other skeletal parameters when given alone. As previously found, E2 produced a large increase in femoral BMD, stimulated cancellous and endocortical bone formation, but inhibited periosteal bone formation. In mice treated with combination therapy, a greater increase in femoral BMD was observed compared to that following treatment with either agent alone. No differences in indices of cancellous bone were found between animals treated with E2 compared to the combination group. However, cortical area and periosteal bone formation rate were significantly greater in the latter group. We conclude that PTH and E2 exert an additive effect on bone mass in long bones of female mice, possibly reflecting an ability of PTH to oppose E2-induced suppression of periosteal bone formation.

Role of endothelial nitric oxide synthase in estrogen-induced osteogenesis

It is well recognized that high-dose estrogen induces a marked osteogenic response in long bones of female mice. In light of evidence which suggests that nitric oxide synthase (NOS) plays a role in regulation of osteoblast activity, we analyzed whether NOS is involved in mediating this response. Intact female mice were administered 17beta-estradiol (E(2)) either alone or in combination with N(G)-nitro-L-arginine methylester (L-NAME) or aminoguanidine (AG), over 24 days. The former inhibits both constitutive and inducible isoforms of NOS, whereas the latter is a selective inhibitor of inducible NOS. Bone mineral density (BMD) of the femur was subsequently measured by dual-energy X-ray absorptiometry (DXA), and histomorphometry performed at the proximal metaphysis on longitudinal tibial sections. As expected, E(2) given alone led to a marked accumulation of cancellous bone at the proximal tibial metaphysis, associated with a significant gain in femoral BMD, and an increase in cancellous mineralizing surfaces as assessed by histomorphometry. Neither L-NAME nor AG affected cancellous histomorphometric indices when given alone. However, when administered in combination with L-NAME, the magnitude of the skeletal response to E(2) was significantly reduced. The tendency for L-NAME to reduce estrogen-induced bone formation within the proximal tibial metaphysis was more marked distally compared with proximally. In contrast, AG showed no tendency to suppress the osteogenic response to E(2). Subsequently, we examined the effect of E(2) administration on expression within mouse femoral bone marrow of endothelial NOS (eNOS), which is the predominant constitutive isoform of NOS within bone. No change in eNOS mRNA levels was observed following E(2) administration, as assessed by reverse transcription-polymerase chain reaction (RT-PCR). Taken together, our results suggest that eNOS plays a role in mediating estrogen-induced bone formation in intact female mice, possibly as a consequence of posttranscriptional regulation of eNOS activity by estrogen.

Effects of high-dose estrogen on murine hematopoietic bone marrow precede those on osteogenesis

High-dose estrogen both stimulates new medullary bone formation and suppresses hematopoiesis in mouse long bones. To determine whether the latter response is a direct consequence of the former, we compared the time course of estrogen's effects on osteogenesis and hematopoietic bone marrow. Flow cytometry was employed to measure hematopoietic subpopulations in bone marrow from femurs of female mice killed at different times after commencing 0.5 mg estradiol/wk to each animal. Estrogen markedly reduced the number of leucocytes (CD11a positive), which had already diminished by 75% after 4 days and had virtually disappeared by 18 days. Specific populations showed a similar pattern of decline after estrogen, including B lymphocytes, monocytes, and endothelial cells. In contrast, the osteogenic precursor population showed a marked increase after estrogen treatment, as assessed by assaying alkaline phosphatase-positive colony-forming units (fibroblastic) ex vivo. However, this rise did not reach significance until 8 days after estrogen administration, suggesting that it follows rather than precedes estrogen's effects on hematopoiesis. We conclude that estrogen does not suppress hematopoiesis in mouse long bones as a direct consequence of its effects on osteogenesis.

Topographic position of forelimb motoneuron pools is conserved in vertebrate evolution

The neuromotor conservatism hypothesis predicts that neuromotor patterns in homologous tetrapod muscles are conserved evolutionarily despite the musculoskeletal modifications of vertebrate limbs. A complete description of the anatomical organization of the neurons innervating homologous limb muscles is a prerequisite to any test of the neuromotor conservatism hypothesis. This study uses the retrograde neuronal tracer WGA-HRP to selectively label the motor neuron pools of seven homologous forelimb muscles in mice (Mus musculus) and iguanas (Iguana iguana): Mm. pectoralis, spinodeltoideus, biceps brachii, lateral and long heads of triceps brachii, and the supraspinatus and infraspinatus (in mice) or their reptilian homolog, the supracoracoideus (in iguanas). In vertebrates, motoneurons are arranged in longitudinal columns of cells in the ventral horn of the spinal cord. Mouse motor pools average 1,952 microns in length, except the pectoralis pool which averaged 2,949 microns in length. Iguana pools average 3,196 microns in length. The number of neurons per pool ranged from 70-199 in mice and from 58-114 neurons in iguanas. In both iguanas and mice the motor pools for the spinodeltoids, biceps, and the supracoracoideus (or its mammalian homologs) lie anterior to the pectoralis and triceps motor pools. In the transverse plane, the pectoralis pool lies medial to those of the triceps. The pools of the biceps and spinodeltoids are located dorsal and lateral to those of the pectoralis and supracoracoideus (or its homologs in mammals). The resulting motor pool maps support the hypothesis that the anatomical organization of motoneurons in ancestral reptiles has been retained in these two tetrapod descendents.

Is high-dose estrogen-induced osteogenesis in the mouse mediated by an estrogen receptor?

Although estrogen is known to induce new bone formation in the long bones of female mice, this response is only thought to occur following administration of high doses, suggesting that it may not be mediated by a conventional estrogen receptor. To address this question further, we first examined the stereospecificity of this response by comparing the potency of 17beta-estradiol (E(2)) in stimulating cancellous bone formation at the proximal tibial metaphysis of intact female mice with that of the relatively inactive stereoisomer, 17alpha-estradiol (alphaE(2)). We found that E(2) was significantly more potent than alphaE(2), as assessed by histomorphometry. To provide further evidence for an estrogen-receptor-mediated process, we examined whether E(2)-induced osteogenesis in intact female mice could be inhibited by the estrogen receptor antagonist, ICI 182,780 (ICI). Although ICI itself had no effect on histomorphometric indices of the proximal tibial metaphysis when given alone, it significantly inhibited the osteogenic response to E(2). Finally, we examined the dose dependency of E(2)-induced osteogenesis at the proximal tibial metaphysis in intact mice. We found that E(2) stimulated cancellous bone formation in a dose-dependent manner over a wide dose range (i. e., 1-4000 microg/kg per day), with significant increases observed at doses of 4 microg/kg per day and beyond. Our results raise the possibility that estrogen-induced osteogenesis in the mouse represents an estrogen-receptor-mediated response that is not confined solely to supraphysiological estrogen levels.

High-dose estrogen-induced osteogenesis in the mouse is partially suppressed by indomethacin

We recently found that high-dose estrogen induces the formation of new sites of cancellous bone formation within the long bones of intact female mice. To examine whether prostaglandins play a role in mediating this response, we studied whether this is inhibited by coadministration of the cyclooxygenase inhibitor, indomethacin. Eight-week-old intact female mice were divided into four groups of ten, and administered vehicle, 17beta-estradiol (E2), at 500 microg/animal per week and/or indomethacin at 2 mg/kg per day. Animals were killed after treatment for 24 days, and histomorphometric indices subsequently analyzed on longitudinal sections of the proximal tibial metaphysis. As found previously, E2 treatment caused a striking increase in cancellous bone volume, associated with an equivalent increase in the extent of cancellous double-labeled surfaces. In mice treated with both indomethacin and E2, significant reductions in cancellous bone volume and cancellous double-labeled surfaces were observed as compared with animals treated with E2 alone. In contrast, indomethacin did not significantly influence these parameters when given alone. Subregional analysis within the proximal tibial metaphysis revealed that this inhibitory effect of indomethacin was more marked distally as compared with proximally, with the estrogen-induced gain in cancellous bone volume at these sites being reduced by 50% and 25%, respectively. We conclude that estrogen-induced osteogenesis in female mice is partially suppressed by treatment with indomethacin, suggesting that prostaglandin synthesis plays a significant role in mediating this response.

End-stage renal disease in sarcoidosis of the kidney

We describe two cases of black women with biopsy-proven sarcoidosis of the kidney who developed end-stage renal disease. Treatment with high-dose glucocorticoids resulted in a good initial response, followed by progressive deterioration of renal function requiring hemodialysis.

High-dose estrogen induces de novo medullary bone formation in female mice

It is well recognized that, in the mouse, high-dose estrogen induces sclerosis within the shaft of long bones, an action that is largely thought to reflect increased osteoblastic cellular activity. We undertook to characterize this response in more detail, by performing a histologic analysis of the early changes induced by high-dose estrogen in the tibial cavity of young intact female mice. Female mice were sacrificed immediately before or 4, 8, 12, or 24 days after commencing subcutaneous injections of 17beta-estradiol (500 microg/animal/week), and longitudinal tibial sections were subsequently examined. Estrogen was found to cause a rapid gain in cancellous bone, with cancellous bone volume increasing by approximately 50% after 8 days, and by 5-fold after 24 days. Analysis of cancellous double-labeled surfaces revealed that this gain in bone reflected the emergence of new cancellous bone formation sites within the medullary cavity, rather than the reactivation and extension of formation over pre-existing bone surfaces. Comparison of the time course of these changes between proximal and distal regions of the proximal tibial metaphysis suggested that these new cancellous formation sites appear as a rapid wave extending distally from the secondary spongiosa. Alkaline phosphatase (ALP) immunocytochemistry revealed that, by 12 days after estrogen administration, a population of strongly ALP positive cells had appeared throughout the marrow cavity. We conclude that, at the proximal tibial metaphysis of female mice, estrogen-induced medullary sclerosis largely reflects a process of de novo medullary bone formation, possibly mediated by the generation of osteoblasts from bone marrow osteoprogenitor cells.

Medicolegal aspects of managing deliberate self-harm in the emergency department

Deliberate self-harm is a common reason for people to present to hospital. The management of this problem can cause ethical and legal difficulties to clinicians. This article describes a case of deliberate self-harm which we have used to illustrate answers to commonly asked questions about this difficult area. We make a case for such patients to be treated against their will under common law unless the use of the mental health act is clearly indicated. The Privacy Act appears to prohibit clinicians informing families about an episode of deliberate self-harm if the patient refuses consent. Clarification of "imminent threat to life or health" in the Privacy Act is needed.

Low dose amitriptyline in ankylosing spondylitis: a short term, double blind, placebo controlled study

OBJECTIVE

To define the effect of low dose amitriptyline on fatigue, pain, and stiffness in patients with ankylosing spondylitis (AS).

METHODS

One hundred consecutive patients with AS were randomized to receive low dose amitriptyline up to 30 mg nightly or placebo for 2 weeks. Patients were assessed by the Bath Ankylosing Spondylitis Disease Activity (BASDAI) and Functional (BASFI) Indices pre and post-treatment.

RESULTS

Eighty-eight patients (44 amitriptyline, 44 placebo) completed the study. Eight (5 amitriptyline, 3 placebo) stopped treatment because of side effects (e.g., drowsiness, dryness of mouth) and 4 provided insufficient data. Compared to placebo, the patients taking amitriptyline showed significantly greater improvement in restful sleep (66 vs 20%; p < 0.001) and their disease activity scores [BASDAI amitriptyline 1.18 (23%) vs placebo 0.52 (10%); p = 0.024]. All other variables showed a trend to greater improvement by amitriptyline, although the differences were not statistically significant.

CONCLUSION

(1) In a 2 week study, low dose amitriptyline significantly improved sleep in AS and was well tolerated; (2) as defined by BASDAI, there was a significant reduction in disease activity with amitriptyline; (3) compared to placebo, there was a nonsignificant trend toward improvement in function; and (4) in spite of improvement in pain, fatigue, and sleep with amitriptyline, stiffness was not increased.

Influence of air inhomogeneities in radiosurgical beams

The effect of air inhomogeneity on dose distribution in small diameter beams used in stereotactic radiosurgery (SRS) has been investigated. The measurements of the surface dose and central axis dose were made for a 6 MV photon beam with a diamond detector which has suitable radiologic properties for such measurements. Measurements made in a uniform density solid water phantom and in the presence of four air gaps indicate significant dose perturbation immediately beyond the air-solid water interface. The reduction in dose at the surface for a 12.5 mm diameter field is 11%, 17%, 23% and 33% for air gap thicknesses of 3, 4.6, 6 and 9.2 mm, respectively. The corresponding dose reduction for a 25 mm diameter field is 3%, 4%, 7% and 13%, respectively. The ratio of the dose with and without air inhomogeneity is highly dependent on field diameter and approaches 1.0 as the field diameter increases from 12.5 mm to 40 mm. The dose perturbation also increases with increase in air inhomogeneity thickness for all field diameters investigated. A dose buildup phenomenon is observed beyond the air gap with a shallow dmax of approximately 4-6 mm. Beyond the buildup region, a higher dose value compared to a homogeneous phantom is observed at all depths due to reduced photon attenuation in the air gap. The dose profiles beyond the air gap, measured with radiographic films, demonstrate no significant increase in the beam diameter but a pronounced broadening of the beam penumbra (80%-20% and 90%-10%) leading to enhanced dose outside the primary beam geometric edge and reduced dose inside the edge. The dose enhancement outside the beam edge increases with increase in air gap thickness.

Defining the personality disorders: description of an Australian database

OBJECTIVE

We seek to improve the definition and classification of the personality disorders (PDs) and derive a large database for addressing this objective.

METHOD

The paper describes the rationale for the development of a large set of descriptors of the PDs (including all DSM-IV and ICD-10 descriptors, but enriched by an additional 109 items), the design of parallel self-report (SR) and corroborative witness (CW) measures, sample recruitment (of 863 patients with a priori evidence of personality disorder or disturbance) and preliminary descriptive data.

RESULTS

Analyses (particularly those comparing ratings on molar PD descriptions with putative PD dimensions) argue for acceptable reliability of the data set, while both the size of the sample and the representation of all PD dimensions of interest argue for the adequacy of the database.

CONCLUSIONS

We consider in some detail current limitations to the definition and classification of the PDs, and foreshadow the analytic techniques that will be used to address the key objectives of allowing the PDs to be modelled more clearly and, ideally, measured with greater precision and validity.