Abrin poisoning

Abrin is a toxic protein obtained from the seeds of Abrus precatorius (jequirity bean), which is similar in structure and properties to ricin. Abrin is highly toxic, with an estimated human fatal dose of 0.1-1 microgram/kg, and has caused death after accidental and intentional poisoning. Abrin can be extracted from jequirity beans using a relatively simple and cheap procedure. This satisfies one criterion of a potential chemical warfare agent, although the lack of large scale production of jequirity seeds means that quantity is unavailable for ready mass production of abrin for weapons. This contrasts with the huge cultivation of Ricinus seeds for castor oil production. At the cellular level, abrin inhibits protein synthesis, thereby causing cell death. Many of the features observed in abrin poisoning can be explained by abrin-induced endothelial cell damage, which causes an increase in capillary permeability with consequent fluid and protein leakage and tissue oedema (the so-called vascular leak syndrome). Most reported cases of human poisoning involve the ingestion of jequirity beans, which predominantly cause gastrointestinal toxicity. Management is symptomatic and supportive. Experimental studies have shown that vaccination with abrin toxoid may offer some protection against a subsequent abrin challenge, although such an approach is unlikely to be of benefit in a civilian population that in all probability would be unprotected.     

"I get to spend time with my patients": nursing home physicians discuss their role

OBJECTIVES: The purpose of this study was to learn about the role of the nursing home physician, and to begin to identify and articulate key concepts related to the role. DESIGN: A qualitative exploratory methodology was selected. Two medical students interviewed nursing home physicians in person, using open-ended questions. SETTING: The data reflect the nursing home setting. PARTICIPANTS: Twelve physicians who practice full-time or part-time in a nursing home setting were interviewed. Six physicians were fellowship trained and seven were affiliated with an academic medical center. Eight physicians were from an urban area, and four were from a rural area in a Midwestern state. MEASUREMENT: Qualitative data were grouped and coded to develop conceptual categories. RESULTS: Physicians were categorized as "pursuers, inheritors, or practice builders," based on their path to coming to care for nursing home residents. The medical directors among the physicians reported that their role was heavily dependent upon the desires of the nursing home administrator. Students were encouraged to visit many nursing homes to learn about the different ways in which the medical director role can be played out. Physicians reported positive aspects of their role including relationships with residents, families,staff; interesting and meaningful patient care; and autonomy. Less desirable aspects included: staff turnover, difficult expectations, and administrative issues. Although physicians indicated that social and indeed professional stigma are troublesome to people who work in nursing homes, they assured the medical student interviewer that caring for nursing home residents was gratifying and meaningful work. CONCLUSION: The need for physicians to care for the growing number of nursing home residents will continue for decades. Learning more about how physicians come to care for nursing home residents can be used to develop better ways to recruit, train, and retain physicians. Information about what nursing home physicians value about their role can be used to structure more desirable roles.     

Reliability of the electronic early treatment diabetic retinopathy study testing protocol in children 7 to <13 years old

PURPOSE: To assess the test-retest reliability of the electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) visual acuity algorithm using the computerized Electronic Visual Acuity (EVA) tester in children 7 to <13 years old. DESIGN: Test-retest reliability study. METHODS: This multicenter study involved 245 subjects at four clinical sites. As the main outcome measure, visual acuity was measured twice using the E-ETDRS testing protocol on the EVA system, which uses a programmed handheld device to communicate with a personal computer and a 17-inch monitor at a 3-m test distance. RESULTS: Test-retest reliability was high (r =.94 for right eyes and 0.96 for left eyes) and for both right and left eyes, 89% of retest scores were within 0.1 logarithm of the minimal angle of resolution (logMAR) (five letters) of the initial test score and 99% of retests were within 0.2 logMAR (10 letters). Reliability was high across the age range of 7 to <13 years. Based on 95% confidence level estimates, a change in visual acuity of 0.2 logMAR (10 letters) from a previous acuity measure is unlikely to result from measurement variability. CONCLUSIONS: The E-ETDRS protocol using the EVA has high test-retest reliability in children 7 to <13 years of age. Potential advantages include better standardization across multiple sites, the ability to directly capture data electronically with an automatic acuity score calculation, the reduction of potential bias by limiting the tester's role, and the requirement of only a single testing distance for measurements from 20/800 to 20/12. This computerized testing method should be considered when visual acuity is used as an outcome measure in eye research involving children 7 to <13 years old.     

New retinoblastoma tumor formation in children initially treated with systemic carboplatin

PURPOSE: To determine the frequency and timing of new intraocular tumor formation in children with hereditary retinoblastoma initially treated with systemic carboplatin. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: This study included 34 children (57 eyes) with hereditary bilateral retinoblastoma initially treated with systemic carboplatin at the Robert M. Ellsworth Ophthalmic Oncology Center at NewYork-Presbyterian Hospital from 1994 through 2000. MAIN OUTCOME MEASURES: New tumor formation after initial treatment with systemic carboplatin. RESULTS: There were a total of 165 tumors in 57 eyes. There were 63 new tumors in 27 eyes (47%) after administration of systemic carboplatin, for a mean of 1.1 new tumors per eye. The mean patient age at time of new tumor presentation was 9 months, with 57% of new tumors developing within 4 months of carboplatin treatment. Kaplan-Meier analysis showed that children who were treated when younger than 6 months of age were more likely to have new tumors (60%) compared with those treated after 6 months of age (31%; P = 0.0182). CONCLUSIONS: New intraocular tumors continue to develop after systemic carboplatin; most new tumors appeared within 4 months of treatment.     

Ferrara intrastromal corneal ring segments for severe keratoconus

PURPOSE: Intrastromal Ferrara ring segments were inserted in eyes with severe keratoconus to evaluate safety and efficacy of this procedure. METHODS: Intrastromal Ferrara ring segments were placed in 36 eyes of 35 patients with severe keratoconus, who were evaluated after 12 months of follow-up. All patients had highly disabling visual acuity, contact lens intolerance, and a previous indication for penetrating keratoplasty. Statistical analysis included preoperative and postoperative uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, anterior chamber depth, keratometry, and pachymetry. RESULTS: No patient had a loss of visual acuity. Uncorrected visual acuity improved in 28 eyes (77.78%) and best spectacle-corrected visual acuity improved in 29 eyes (80.56%). Spherical equivalent refraction decreased from -7.29 +/- 3.12 D to -4.80 +/- 3.04 D at 12 months after Ferrara intrastromal ring segment implantation. Corneal topography and ultrasound biomicroscopy showed corneal flattening, demonstrated by thinning of the central cornea and a reduction in anterior chamber depth. Segment decentration occurred in one eye (2.7%), asymmetric positioning of the segments in two eyes (5%), inadequate depth in two eyes (5%), migration of the segments in two eyes (5%), segment extrusion in five eyes (13.8%), conjunctivitis in one eye (2.7%), bacterial keratitis in one eye (2.7%), and hydrops in one eye (2.7%). CONCLUSIONS: With these early results, Ferrara intrastromal ring segments appear to be an alternative for the treatment of severe keratoconus.     

Photoenhanced toxicity of aqueous phase and chemically dispersed weathered Alaska North Slope crude oil to Pacific herring eggs and larvae

The photoenhanced toxicity of weathered Alaska North Slope crude oil (ANS) was investigated in the eggs and larvae of Pacific herring (Clupea pallasi) with and without the chemical dispersant Corexit 9527. Oil alone was acutely toxic to larvae at aqueous concentrations below 50 microg/L total polycyclic aromatic hydrocarbons (tPAH), and median lethal (LC50s) and effective concentrations (EC50s) decreased with time after initial oil exposure. Brief exposure to sunlight (approximately 2.5 h/d for 2 d) significantly increased toxicity 1.5- to 48-fold over control lighting. Photoenhanced toxicity only occurred when oil was present in larval tissue and increased with increasing tPAH concentration in tissue. Ultraviolet radiation A (UVA) treatments were less potent than natural sunlight, and UVA + sunlight caused greater toxicity than sunlight alone. The toxicity of chemically dispersed oil was similar to oil alone in control and UVA treatments, but oil + dispersant was significantly more toxic in the sunlight treatments. The chemical dispersant appeared to accelerate PAH dissolution into the aqueous phase, resulting in more rapid toxicity. In oil + dispersant exposures, the 96-h no-observed-effect concentrations in the UVA + sunlight treatment were 0.2 microg/L tPAH and 0.01 microg/g tPAH. Exposure of herring eggs to oil caused yolk sac edema, but eggs were not exposed to sun and UVA treatment did not cause phototoxicity. These results are consistent with the hypothesis that weathered ANS is phototoxic and that UV can be a significant and causative factor in the mortality of early life stages of herring exposed to oil and chemically dispersed oil.     

The relative sensitivity of four benthic invertebrates to metals in spiked-sediment exposures and application to contaminated field sediment

The relative sensitivity of four benthic invertebrates (Hyalella azteca, Chironomus riparius, Hexagenia spp., and Tubifex tubifex) was determined for Cd, Cu, and Ni in water-only and in spiked-sediment exposures. Survival (median lethal concentrations [LC50s] and the concentrations estimated to be lethal to 25% of test organisms [LC25s]), and endpoints for growth and reproduction (mean inhibitory concentrations [IC25s]) were compared. The sensitivities differed depending on the species and metal, although some trends emerged. In water-only exposures, H. azteca is the most sensitive species to cadmium and nickel, with mean LC50s of 0.013 and 3.6 mg/L, respectively; C. riparius is the most sensitive species to copper, with a mean LC50 of 0.043 mg/L. In the spiked-sediment exposures, the order in decreasing sensitivity to copper is Hyalella = Hexagenia < Chironomus < Tubifex for survival and growth/reproduction. For cadmium, the order in decreasing sensitivity is Hyalella = Chironomus < Hexagenia < Tubifex, and for nickel is Hyalella < Hexagenia < Chironomus < Tubifex. Chironomus riparius and Hexagenia spp. survival can be used to distinguish between toxicity caused by different metals. Species test responses in field-collected sediment(Collingwood Harbour, ON, Canada) were examined in an attempt to determine the causative agent of toxicity throughout, using the established species sensitivities. Sediment toxicity was categorized first by comparing species responses to those established for a reference database. Test responses in the field-collected sediment do not support causality by Cu, a suspected toxicant based on comparison of sediment chemistry with sediment quality guidelines.