Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery.

Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 +/- 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 +/- 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 +/- 15.1 cGy, 9.15 +/- 3.89 cGy, 0.47 +/- 0.3 cGy and 0.53 +/- 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

Corneal nerve damage and regeneration after excimer laser photokeratectomy in rabbit eyes.

PURPOSE: To investigate corneal nerve damage and its subsequent regeneration after excimer laser photokeratectomy in rabbit eyes. METHODS: Corneal photokeratectomy was performed on the right eyes of 34 pigmented rabbits, while the left eyes were used as a control. A Summit UV 200 excimer laser (Summit Technology, Waltham, MA) was used to produce a 100 microns depth phototherapeutic keratectomy (4.5 mm diameter). The rabbits were killed at 0, 1, 2, 3, 4, 5, 7, 8, 10, 15, and 20 days and 1, 2, 3, and 4 months after treatment. Corneal nerve regeneration was investigated using a monoclonal antibody directed against a 150 kD subunit of neurofilaments, in combination with acetylcholinesterase staining. RESULTS: At time 0, the subepithelial plexus had disappeared completely from the photoablated area. One day after treatment, some regenerating nerves sprouting within the treated area were visualized by a monoclonal antibody directed against a 150 kD subunit of neurofilaments. Acetylcholinesterase staining was detectable 7 days later. One month after surgery the subepithelial plexus had already reappeared, but was morphologically disorganized. Four months after treatment, the newly formed subepithelial plexus had considerably thickened in comparison with that of the control eye. CONCLUSIONS: This study shows that corneal nerve regeneration after excimer laser photoablation in rabbit eyes, although more intense, is similar to that produced after other surgical procedures involving the epithelium and the anterior stroma or one of the two.

A multi-center study: clinical practices of HIV infected patients on CAPD/CCPD.

Our statistics reveal the average patient in our study to be a young black male with a history of IVDA with CAPD as the initial dialysis modality. He was most often trained on a mechanical assist device, but he still developed frequent peritonitis episodes, predominantly gram positive. His survival rate was less than 2 years, but he was able to remain independent until he died. Our fears about caring for the HIV infected individual cannot be denied. Even though we may never be truly comfortable when caring for someone with this disease, it is possible to train them to perform home peritoneal dialysis safely and effectively. By doing this, we can preserve the patients' independence and maintain their dignity while they cope with this overwhelming illness.

Training psychiatric patients to discuss medication issues. Effects on patient communication and knowledge of medications.

Psychiatric inpatients were randomly assigned to a medication-related communication skills program or to a control condition that consisted of a medication education program. The medication communication program emphasized learning to ask physicians questions about medications, to describe current problems, and to make relevant requests. Although patients in both groups improved their knowledge of medications, the medication communication skills program had the added impact of teaching patients to ask more questions of a doctor and to engage in longer conversations. Moreover, patients who completed the medication communication program were rated as more assertive, as having acquired more information about a new medication that was prescribed, as having greater social skill, as being more likely to be compliant with medication, and as having greater eye contact. These results suggest that the use of a medication-related communication skills program may be a somewhat novel and effective way to increase patient involvement in treatment and to facilitate the elicitation of information about the prescribed medication regimen.

Teaching job independence and flexibility to mentally retarded students through the use of a self-control package.

We examined mentally retarded individuals' use of picture cues and self-monitoring to initiate a series of tasks of varying type and order. Four severely to moderately retarded high school students participating in a vocational training program were trained to use a picture-cue system. The system consisted of photographs of vocational tasks that were inserted in the assigned order in a photoalbum sheet; self-management was accomplished by marking off each photo after its corresponding task was completed. Students were assigned seven tasks from a pool of 13 each day. Results indicated that the students quickly learned to use the picture-cue system to change tasks throughout their workday without trainer prompts and that performance was maintained as trainer feedback and presence were decreased. At the end of the study, two students who were exposed to novel photographs were able to initiate independently after only minimal training, suggesting that the use of the picture-cue system had become a generalized skill.

Introduction of new technologies to the medical undergraduate curriculum.

The rate at which new educational technologies are introduced is growing at a tremendous pace. This is in large part due to the recommendations of the AAMC Steering Committee on the Evaluation of Medical Education which strongly supported the use of Medical Informatics technologies for education. Some institutions have attempted to implement these technologies; however, a scientific study has not yet been conducted to document their potential benefit. Our attempts to conduct such a study were met with obstacles of resistance from faculty, administration, and students. To overcome these obstacles we have developed a solution which addresses all of the resistance that we encountered. This solution is based upon three premises: 1) adjunct introduction, 2) multicenter studies, and 3) scientific educational benefit analyses.

Diode and Nd:YAG laser contact transscleral cyclophotocoagulation in a human eye: a comparative histopathologic study of the lesions produced using a new fiber optic probe.

We compared the contact cyclodestructive effects (both gross and histologic) achieved with diode and Nd:YAG laser wavelengths (810 and 1064 nm, respectively), using equivalent energy doses, released by means of a new optical delivery system in a human eye that was soon to be enucleated because of a choroidal melanoma. For both lasers, a fiber optic system (400 microns) with a focusing microlens placed at the end of the fiber was used. The center of the beam was placed 1.5 mm from the corneoscleral limbus. At medium (5.2 to 6.6 J) and higher (7.8 J) energy levels, the cyclodestructive thermal damage produced by the diode laser appeared more widespread than that created by the Nd:YAG laser. At lower levels (3.6 to 3.9 J), both laser treatments produced similar lesions. The new delivery system proved to be safe and effective in achieving the desired cyclodestructive effects at both wavelengths.

Endophotocoagulation through perfluorodecalin in rabbit eyes.

Retinal laser endophotocoagulation through perfluorodecalin was studied in six eyes of three Dutch-belted rabbits after vitrectomy. Both the energy density threshold (EDT/50) and the energy threshold necessary to obtain a therapeutic lesion were evaluated. Both argon and semiconductor diode laser endophotocoagulators were used. The amount of laser power energy and the histology of chorioretinal lesions were similar when photocoagulating through perfluorodecalin, compared to photocoagulation through balanced salt citrate-buffered solution. This experimental study indicates that no extra care is necessary when retinal endophotocoagulation is performed through perfluorodecalin, as long as circular spots are obtained and energy is delivered symmetrically to the target site.

Study of photoablation of rabbit corneas by Er:YAG laser.

BACKGROUND AND OBJECTIVE: This work studied the ablation mechanisms of rabbit corneas by the Erbium:YAG laser. The occurrence of thermal and mechanical damages in the tissue as a function of the laser fluence was also investigated. STUDY DESIGN/MATERIALS AND METHODS: The experiments were performed both on enucleated eyes and in vivo. An ultrafast imaging technique was used to investigate the dynamic evolution of the ablation. The treated samples underwent histological and ultrastructural study. RESULTS: A single high fluence laser shot led to the complete removal of the epithelium by a photomechanical effect. In eyes whose epithelium was manually removed, high fluence pulses resulted in evident tears in the stroma, whereas low fluence pulses led to few microns deep incisions, characterized by limited mechanical and thermal damages. CONCLUSION: The photomechanical action plays a significant role in the ablation of the cornea by Erbium laser. Precise control of the fluence is required to avoid cracking phenomena in the stroma.

Understanding delay in treatment for first-episode psychosis.

BACKGROUND: A lengthy delay often occurs between the onset of symptoms of psychotic disorders and initiation of adequate treatment. In this paper we examine the extent to which this represents a delay in individuals contacting health professionals or a delay in receiving treatment once such contact is made. METHOD: Pathways to care were examined in 110 patients of the Prevention and Early Intervention Program for Psychosis in London, Canada. Data were collected using structured interviews with patients, family members, consultation with clinicians and review of case records. RESULTS: Family physicians and hospital emergency rooms were prominent components of pathways to care. Both delay to contact with a helping professional and delay from such contact to initiation of adequate treatment appear to be about equally important for the sample as a whole, but some individuals appear to be at risk for particularly lengthy delay in the second component. Individuals with younger age of onset, or who had initial contact with professional helpers before the onset of psychosis and were being seen on an ongoing basis at the time of onset of psychosis, had longer delays from first service contact after onset to initiation of adequate treatment. The greater delay to treatment for those being seen at the onset of psychosis does not appear to reflect differences in age, gender, symptoms, drug use or willingness to take medication. CONCLUSIONS: Interventions to reduce treatment delay should increase the public's awareness of the symptoms of psychotic illness and the need to seek treatment, but of equal importance is the education of service providers to recognize such illness and the potential benefits of earlier intervention.

Indocyanine green and fluorescein angiography of surgically excised macular choroidal neovascularizations: correlations with histopathologic and ultrastructural findings.

BACKGROUND: Informations are expected from the histopathological study of surgically excised choroidal neovascular membranes (CNMs), particularly in relation to the angiographic aspects of vascular architecture. METHODS: Fluorescein and indocyanine green (ICG) angiograms were studied together with the histopathological features of 12 surgically excised subfoveal CNMs in eyes affected by age-related macular degeneration (ARMD). RESULTS: Instead of the early and delayed diffuse hyperfluorescence secondary to CNMs observed on fluorescein angiography (seven were well defined, five scar evolved), ICG revealed (a) very early hypofluorescence of the membrane bulk over the fluorescence of the outer choroidal vascular bed and (b) late hyperfluorescence gradually increasing and partially defining the border of membranes. CNMs with well-defined hyperfluorescent aspects were characterized by fibrovascular bulk lined on one side by retinal pigment epithelium. Fibrosis reaction predominated over the vascular components in scar-evolved membranes. CONCLUSIONS: Fluorescein and ICG angiographic differences in the appearance of CNMs could depend on (a) the morphological structure and size of the CNM (b) its location within the chorioretinal layers and (c) different molecular characteristics of the dyes used.

Fibroma aponeurótico calcificante / Calcifying aponeurotic fibroma

Se reporta una joven paciente oriunda de Paraguay, con lesión en platillo ungueal de hallux izquierdo, previamente intervenida en su país por FAC, quien fue sometida nuevamente a cirugía, confirmándose así la sospecha clínica de recaída local del tumor.

This case is the report of a young patient from Paraguay that presented with a lesion in the nail plate of the left hallux. The patient underwent surgery in her country with a diagnosis of calcifyng aponeurotic fibroma. The new surgery performed confirmed a local recurrence of the tumor.

Tungiasis / Tungiasis

We present a ten years' old patient immune competent, with multiple lesions of tungiasis in both feet, that consult when she returned of her vacations in Paraguay. We make a brief description of the topic.

Se presenta una paciente de 10 años de edad inmunocompetente con lesiones múltiples de tungiasis en ambos pies, que consulta al regreso de sus vacaciones en Paraguay. Se efectúa una breve revisión del tema.

Ameloblastoma o adamantinoma / Ameloblastoma or adamantinoma

Se relata el caso de un paciente de 26 años de edad, con deformidad facial, que presenta un tumor gingivoyugal posterior derecho con imágenes oteolíticas en los estudios radiológicos simples y en la resonancia magnética, con histopatología e inmunohistoquímica de ameloblastoma. La terapéutica fue quirúrgica con amplio margen. Motiva la presentación la escasa frecuencia de presentación de este tumor.

It is present a ameloblastoma case, tumour of rare case on a patient of 26 years old in who development the process on the maxilla. It is realized a revision of the neoplastic characteristic and it is comment the result of the surgical treatment realized at the patient.

Descubriendo el pseudoxantoma elástico / Discovering the elasticum pseudoxanthoma

Enfermedad hereditaria rara, el pseudoxantoma elástico es un trastorno genético del tejido conectivo, que se caracteriza por fragmentación de las fibras elásticas y posterior calcificación de éstas afectando dermis, vasos sanguíneos y la membrana de Bruch de retina. El patrón de herencia es muy variable, lo que hace posible que esta enfermedad pueda estar subdiagnosticada. La escasa incidencia de esta patología justifica la presentación de dos casos que tuvieron solamente manifestaciones cutáneas.

Hereditary disease does not frequent pseudoxanthoma elastic; is a genetic upheaval of the conective weave, that characterizes by fragmentation of elastic fibers and later calcification of these, affecting dermis, blood vessels and membrane of Bruch of retina. The inheritance pattern is very variable which causes that disease; can be subdiagnosed. The litlle incidence of this pathology, causes that in our professional experience we have been able to diagnose two cases in which the manifestations were cutaneous.