Indications and results of relaxing retinotomy

The authors report their results of a consecutive series of 40 eyes undergoing relaxing retinotomy during vitrectomy to achieve retinal reattachment for the following indications: proliferative vitreoretinopathy (PVR), 21 eyes (52%); trauma, 10 eyes (25%); diabetic retinopathy, 6 eyes (15%); and expulsive choroidal hemorrhage, 3 eyes (8%). Thirty eyes (75%) had undergone previous vitreoretinal procedures. Extended tamponade was achieved in all cases with either silicone oil (27 eyes, 68%) or long-acting gas (13 eyes, 32%). Retinotomy size ranged from 45 degrees to 360 degrees. Intraoperative retinal attachment was possible in all eyes with 33 (83%) achieving total or subtotal retinal attachment including the macula for 5 months or more. Twenty-seven eyes (68%) achieved 3/200 visual acuity or better and 10 (37%) achieved 20/400 or better. Thirteen eyes (32%) failed to achieve 3/200 visual acuity secondary to recurrent detachment (18%), corneal decompensation (8%), macular dysfunction (5%), and glaucoma (3%).     

Opioid agonist affinity in the guinea-pig ileum and mouse vas deferens

The affinity of morphine, normorphine, methadone, Tyr-D-Ala-Gly-MePhe-NH(CH2)2(N-O)(CH3)2 (RX 783030), [D-Ala2,D-Leu5]enkephalin (DADLE), ketazocine and ethylketocyclazocine (EKC) were determined for their pharmacological receptors in two bioassay tissues, the guinea-pig ileum and the mouse vas deferens (MVD). The method involved the use of the irreversible antagonist, beta-chlornaltrexamine (beta-CNA), and the method of partial receptor blockade. The agonist concentration-effect curves were displaced to the right with decreasing maximum effect, a pattern typical of partial, irreversible blockade of receptors. The concentrations of beta-CNA required to produce a rightward displacement in the concentration-effect curves for different agonists, ranged between 2 and 3000 nM. No similarity was found between the IC50 and the dissociation constant (KA), values predicted to be equivalent only if a linear relationship exists between receptor occupation and observed effect; the dissociation constant for the agonists were between 3 and 218 times larger than the IC50 values. When methadone was used as the agonist in the guinea-pig ileum, beta-CNA produced parallel displacement of the concentration-effect curve, regardless of the blocking concentration chosen, preventing the determination of KA for this agonist, in this tissue; this problem was not encountered in the mouse vas deferens. The KA of morphine, RX 783030 and ketazocine were found not to differ in the guinea-pig ileum and mouse vas deferens. As expected, DADLE had significantly different affinity in the two tissues, showing 117-fold lower affinity in the guinea-pig ileum. Surprisingly, the normorphine affinity was found to be 7-fold higher in the guinea-pig ileum. While the difference in affinity of DADLE may be due to the suggested lack of functional delta receptors in the guinea-pig ileum, the difference in affinity seen with normorphine, but not morphine, in the two tissues is difficult to explain. Taken together with the insensitivity of methadone to beta-CNA blockade in the guinea-pig ileum, but not mouse vas deferens, the difference in the affinity of normorphine in these tissues may suggest the possibility of differences in local milieu of mu receptors or of mu receptor subtypes in the two tissues. The results provide fundamental information regarding opioid agonist affinity in two standard bioassays in vitro, and support the view of (1) a difference in receptors activated by DADLE in the guinea-pig ileum (mu) and mouse vas deferens (delta), as well as (2) possible differences in mu-receptors in these tissues.     

Implementation of a Patient Charting System: Challenges Encountered and Tactics Adopted in a Burn Center

The rapid movement of information technologies into health care organizations has raised managerial concern regarding the capability of today's institutions to satisfactorily manage their introduction. Indeed, several health care institutions have consumed huge amounts of money and frustrated countless people in wasted information systems implementation efforts. Unfortunately, there are no easy answers as to why so many health informatics projects are not more successful. In this light, the aim of this study is to provide a deeper understanding of how clinical information systems are being implemented by emphasizing research efforts on the dynamic nature of the process, that is, the “how” and “why” of what happened. Using a case study methodology, we examined the implementation of a patient charting system in the Burn Center of a large, not-for-profit, teaching hospital. Based on an in-depth examination of this implementation, several insights are offered to those who have responsibility for managing complex and risky clinical information system implementation projects.     

The views of medical students and junior doctors on pre-graduate clinical teaching.

A total of 277 third and fourth year medical students and 304 house officers and senior house officers were asked to prioritise the content and methods of clinical teaching. Response rates were poor, but similar to that in market surveys. Bedside teaching and medical clerking were considered the most valuable methods of teaching and training in practical procedures such as venepunctures and urinary catheterisation was seen as valuable. The design of new curricula in medical education will need to accommodate the views of its clients.     

Enhanced stimulus-reward learning by intra-amygdala administration of a D3 dopamine receptor agonist

The amygdala is considered to be a critical neural substrate underlying the formation of stimulus-reward associations, and is known to receive substantial innervation from dopaminergic neurons located within the ventral mesencephalon. However, relat- ively little is known about the function of the mesoamygdaloid dopamine projection in stimulus-reward learning. Recently, we have found post-session intra-amygdala microinjections of d-amphetamine to enhance appetitive Pavlovian conditioning as assessed in a discriminative approach task. In the present study, we have examined the effects of dopamine receptor agonists possessing relative selectivity for the D₁, D₂ and D₃ receptor subtypes in order to examine more fully the role of the mesoamygdaloid dopamine projection in stimulus-reward learning. Thus, subjects were trained to associate an initially neutral stimulus (CS⁺) with 10% sucrose reward (US). A second, control stimulus (CS⁻) was also presented but never paired with sucrose reward. In order to measure specifically the conditioned response to CS⁺/CS⁻ presentation, responding during CS and US presentations was measured separately. Immediately following each training session, subjects received bilateral intra-amygdala infusion of 0.1, 1 or 10 nmol/side of SKF-38393, quinpirole or 7-OH-DPAT. Infusions of SKF-38393 or quinpirole were without effect on CS⁺ approach. However, post-session intra-amygdala infusions of 7-OH-DPAT enhanced selectively CS⁺ approach in a dose-dependent fashion. No dose of any drug affected CS⁻approach, US behaviours, or measures of extraneous behaviour. Subsequent acquisition of a novel conditioned instrumental response was also unaffected. Thus, the present data indicate a selective involvement of the D₃ dopamine receptor subtype in the modulation of stimulus-reward learning by the mesoamygdaloid dopamine projection. Received: 12 December 1996 / Final version: 9 April 1997     

Acquired cystic disease in chronically rejected renal transplants.

Acquired cystic disease has been documented to complicate most forms of chronic renal damage; it has only infrequently been described in transplanted kidneys. Five patients with noncystic ESRD and chronically rejected transplants in which acquired cystic disease arose are reported. The diagnosis of acquired cystic disease was established in examination of transplant nephrectomies from four patients and a core biopsy from the fifth. The allografts were in place from 44 to 80 months; three patients were treated with hemodialysis before the diagnosis of acquired cystic disease, whereas two received peritoneal dialysis. Three of the four patients evaluated had cysts in the native kidneys. Although papillary hyperplasia of lining epithelium was evident in four specimens, only one kidney was the site of neoplasms in the form of multiple small tubular adenomas. No malignant neoplasms were noted in this study or in the few similar previous ones; however, it is possible that chronically rejected transplanted kidneys may harbor neoplasms with the same malignant potential as those in acquired cystic disease in native kidneys.