Surface Modification of Poly(lactide-co-glycolide) Nanospheres by Biodegradable Poly(lactide)-Poly(ethylene glycol) Copolymers

The modification of surface properties of biodegradable poly(lactide-co-glycolide) (PLGA) and model polystyrene nanospheres by poly(lactide)-poly(ethlene glycol) (PLA:PEG) copolymers has been assessed using a range of in vitro characterization methods followed by in vivo studies of the nanospheres biodistribution after intravenous injection into rats. Coating polymers with PLA:PEG ratio of 2:5 and 3:4 (PEG chains of 5000 and 2000 Da, respectively) were studied. The results reveal the formation of a PLA: PEG coating layer on the particle surface resulting in an increase in the surface hydrophilicity and decrease in the surface charge of the nanospheres. The effects of addition of electrolyte and changes in pH on stability of the nanosphere dispersions confirm that uncoated particles are electrostatically stabilized, while in the presence of the copolymers, steric repulsions are responsible for the stability. The PLA:PEG coating also prevented albumin adsorption onto the colloid surface. The evidence that this effect was observed for the PLA:PEG 3:4 coated nanospheres may indicate that a poly(ethylene glycol) chain of 2000 Da can provide an effective repulsive barrier to albumin adsorption. The in vivo results reveal that coating of PLGA nanospheres with PLA:PEG copolymers can alter the biodistribution in comparison to uncoated PLGA nanospheres. Coating of the model polystyrene nanospheres with PLA:PEG copolymers resulted in an initial high circulation level, but after 3 hours the organ deposition data showed values similar to uncoated polystyrene spheres. The difference in the biological behaviour of coated PLGA and polystyrene nanospheres may suggest a different stability of the adsorbed layers on these two systems. A similar biodistribution pattern of PLA:PEG 3:4 to PEG 2:5 coated particles may indicate that poly(ethylene glycol) chains in the range of 2000 to 5000 can produce a comparable effect on in vivo behaviour.     

Can a house call by a public health nurse improve the quality of the discharge process for geriatric patients?

OBJECTIVE: To determine whether there was any benefit from a single house call by a health visitor (a public health nurse) to an elderly person after discharge home from a geriatric hospital. METHODS: A randomized controlled trial with blind assessments at 28 days was conducted. Subjects included residents of Bath, England, with an average age of 83 years, who were discharged consecutively from a geriatric hospital to their homes. Intervention was a single visit by a health visitor 72 hours after discharge, to ensure the patient was settled at home, or normal post-discharge care. Outcome measures taken at 28 days by a research nurse included survival, hospital readmissions, nursing home admissions, cognitive and physical function, services requested and supplied, and drug therapy. RESULTS: There were no important differences between the intervention and control groups at 28 days on any of the outcome measurements. The control subjects did better than the study subjects on many of the outcome measures. CONCLUSION: A house call by a health visitor to elderly patients after discharge from geriatric wards does not measurably improve the quality of the discharge.     

Modeling breathing-zone concentrations of airborne contaminants generated during compressed air spray painting

This paper presents a mathematical model to predict breathing-zone concentrations of airborne contaminants generated during compressed air spray painting in cross-flow ventilated booths. The model focuses on characterizing the generation and transport of overspray mist. It extends previous work on conventional spray guns to include exposures generated by HVLP guns. Dimensional analysis and scale model wind-tunnel studies are employed using non-volatile oils, instead of paint, to produce empirical equations for estimating exposure to total mass. Results indicate that a dimensionless breathing zone concentration is a nonlinear function of the ratio of momentum flux of air from the spray gun to the momentum flux of air passing through the projected area of the worker's body. The orientation of the spraying operation within the booth is also very significant. The exposure model requires an estimate of the contaminant generation rate, which is approximated by a simple impactor model. The results represent an initial step in the construction of more realistic models capable of predicting exposure as a mathematical function of the governing parameters.     

A Modified Exercise-induced Feeling Inventory for Chronic Training and Baseline Profiles of Participants in the Activity Counseling Trial

An earlier study reported on the development of a scale to measure feeling states during acute bouts of exercise: the Exercise-induced Feeling Inventory (EFI-A). The present study reports on the psychometric properties of a revised scale to assess responses to habitual or chronic physical activity: the EFI-C. The EFI-C was administered during baseline testing to 830 sedentary men and women patients with a mean age of 51.5 years. Factor analytic procedures revealed that the EFI-C consisted of two factors, one assessing pleasant feeling states and a second that taps the unpleasant experience of physical exhaustion. Both subscales have excellent internal consistency reliability coefficients (0.90) and are reasonably stable over time, having test-retest coefficients in excess of 0.70. The scales correlated in expected directions with related constructs and in preliminary analyses showed an anticipated pattern of sensitivity to physical activity interventions. Mean scores for various demographic groups are reported. Future research should examine whether the EFI-C is a predictor of adherence to physical activity and its potential role in mediating the positive mental health effects of physical activity.     

Presurgical assessment and surgical treatment for epilepsy

In the last ten years, dramatic advances in surgical treatment options and techniques have allowed surgical intervention for patients who would otherwise not have been considered as surgical candidates. In this article, a multidisciplinary, logical decision algorithm for a rational approach to surgical treatments is outlined. A carefully considered hierarchy is presented that provides for maximized seizure improvement outcomes. Topics presented include temporal lobectomy, detailed discussion of dominant temporal lobectomy and speech-sparing techniques, neocortical resection, the use of subdural electrode array, depth electrodes, and strip electrodes, multiple subpinal transection, vagus nerve stimulation, and corpus callosotomy. The application of these various techniques to maximize surgical outcome are discussed.     

Computed tomography of the lacrimal drainage system: retrospective study of 107 cases of dacryostenosis.

PURPOSE: To evaluate the role of computed tomography in patients with dacryostenosis. METHODS: One hundred seven cases of dacryostenosis (94 patients) were assessed by thorough clinical and lacrimal history and examination, and lacrimal region computerized tomography (CT). The lacrimal drainage system examination included the state and position of the puncta; Jones testing; lacrimal syringing; and, in the latter half of the study, telescopic nasal endoscopy. The patients were drawn from the hospital outpatients and private office of the operating lacrimal surgeon in this series (I.C.F.). Of the 107 cases, 79 either underwent dacryocystorhinostomy surgery or had this planned. RESULTS: In 14 of the 107 cases (12 patients), preoperative CT led to an alteration of patient management, usually referral to an otolaryngologist for further evaluation or treatment. In addition to the detection of two tumors extrinsic to the sac, conditions such as ethmoiditis, lacrimal sac mucoceles, soft tissue opacity in the nasolacrimal duct, gross nasal polyposis, fungal sinusitis, and a dacryolith were observed by CT. CONCLUSION: Similar to the role of functional endoscopic sinus surgery in otolaryngology, CT imaging will become increasingly important in the assessment of many patients with symptoms of lacrimal drainage obstruction.     

Visual outcome following penetrating globe injuries with retained intraocular foreign bodies

BACKGROUND: In our institution the occurrence of endophthalmitis related to intraocular foreign bodies has been rare. In this review we analyse the outcome of eyes with retained intraocular foreign bodies presenting to two vitreoretinal surgeons over nearly 7 years. METHODS: Review of the records of 26 patients who presented to two surgeons in a tertiary care vitreoretinal service in Toronto between January 1989 and November 1995. Information documented included mechanism of injury, time from injury to definitive surgery, entry site, presence of vitreous hemorrhage, type of surgery performed, initial and final visual acuity, and development of endophthalmitis. RESULTS: All the injuries occurred in male patients, with a mean age of 36.1 (range 15 to 55) years. Most of the injuries occurred in the workplace, and in most cases (17 [65.4%]) the mechanism of injury was "metal on metal." The entry site was via a perforating wound of the cornea in 16 cases (61.5%). Almost all cases were repaired within 48 hours by means of pars plana vitrectomy. Concurrent lensectomy was required in 18 cases (69.2%) for lens damage at the time of the original injury. Vitreous hemorrhage was present in 22 cases (84.6%). One patient (3.8%) manifested clinically apparent endophthalmitis, which responded to intravitreal antibiotic therapy. Nineteen eyes (73.1%) had a final visual acuity of 6/24 or better. Eyes with coexisting or subsequent retinal detachment had significantly worse vision than those without retinal detachment (p < 0.001). INTERPRETATION: The incidence of endophthalmitis in our series is lower than that in other published series. Prompt definitive treatment was associated with a good prognosis in most cases.