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Biomedical subjects

C L Shields

Publications and source records attributed to C L Shields.

At least 397 records · Page 22Linked to original sources
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Choroidal osteoma.

This review details the characteristic clinical features, diagnostic approaches, management, and prognosis of the choroidal osteoma. A comprehensive differential diagnosis is organized to help the ophthalmologist differentiate this tumor from conditions which can sometimes be clinically similar, such as amelanotic choroidal melanoma and nevus, metastatic choroidal carcinoma, choroidal hemangioma, metastatic and dystrophic intraocular calcification, and others. The pathology of the choroidal osteoma is illustrated and several theories of the pathogenesis of this tumor including the possibilities of a choristomatous, inflammatory, and hereditary etiology are discussed. The recently recommended therapeutic technique of photocoagulation of subretinal neovascularization associated with choroidal osteoma are discussed.

Choroid Neoplasms↗
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Management of posterior uveal melanoma.

In recent years, there have been a number of advances in the diagnosis and management of patients with malignant melanoma of the posterior uvea (ciliary body and choroid). This review provides a brief update on the current status of diagnostic modalities, such as fluorescein angiography, ultrasonography, computed tomography, magnetic resonance imaging, fine needle aspiration biopsy, and the radioactive phosphorus uptake test. Following that is a more detailed review of the current controversy regarding the natural course of uveal melanomas and the available therapeutic modalities. Current indications, techniques, complications, and results are provided for various forms of management, such as observation, laser photocoagulation, plaque radiotherapy, charged particle radiotherapy, local tumor resection, enucleation, and orbital exenteration.

Brachytherapy↗
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Iris melanoma in a patient with neurofibromatosis.

Neurofibromatosis type 1 (NF1) is a common autosomal dominant hamartomatous disorder, which is considered to be a neurocristopathy. Uveal melanoma, also of neural crest origin, is the most common primary malignant intraocular tumor in adults. The association of NF1 and uveal melanoma is controversial. We present a clinicopathologic report of iris melanoma in a patient with NF1 and review the literature for a possible causal association. To our knowledge, only 18 cases of uveal melanoma, including three cases of iris melanoma, have been reported in association with NF1. On the basis of the prevalence of NF1 (1 in 3000) and the prevalence of uveal melanoma (1 in 13,500), it can be estimated that approximately seven patients with NF1 in the United States would have an associated uveal melanoma by chance alone. We conclude that despite the theoretical possibility of a causal association of uveal melanoma and NF1, it may still be regarded as coincidental in the absence of any strong evidence to the contrary.

Adult↗
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von Hippel-Lindau disease.

In recent years advances have been made in the clinical and genetic aspects of von Hippel-Lindau disease (VHL). Retinal capillary hemangioma is the most common manifestation of VHL disease and, therefore, ophthalmologists are frequently involved in the care of patients with this disease. The incidence of VHL disease is approximately 1 in 40,000 live births. It is estimated that there are approximately 7000 patients with VHL disease in the USA. The inheritance of VHL disease is autosomal dominant with high penetrance. Depending on the clinical circumstances, retinal capillary hemangioma may be managed by observation, laser photocoagulation, cryotherapy, and plaque radiotherapy. Typical extraocular lesions associated with VHL disease are central nervous system hemangioma, renal cyst, renal carcinoma, pancreatic cysts and adenoma, pancreatic islet cell tumors, pheochromocytoma, endolymphatic sac tumor of the inner ear, and cystadenoma of the epididymis and the broad ligament. The life expectancy of affected individuals may be improved by early detection and treatment of varied manifestations with the use of surveillance protocols. Identification of the VHL gene on chromosome 3p25-26 has now made it possible for suspected individuals to undergo genetic testing with a high degree of accuracy. We review herein the ophthalmic manifestations and treatment of retinal capillary hemangioma and systemic findings of the VHL disease.

Brachytherapy↗
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Transscleral choroidal biopsy in the diagnosis of choroidal lymphoma.

A 57-year-old man with non-Hodgkin's B-cell lymphoma of the abdominal lymph nodes developed moderate cells in the anterior chamber and vitreous, choroidal infiltration, and total nonrhegmatogenous retinal detachment in both eyes while receiving chemotherapy. After a diagnostic vitrectomy in the left eye was nonrevealing, the patient was referred to the oncology service. Fine-needle aspiration biopsy of the choroidal infiltrate was not done because of poor visualization of the choroid through the turbid subretinal fluid. Transscleral choroidal biopsy was performed without complications and disclosed diffuse high-grade B-cell lymphoma and no signs of endogenous infection. Transscleral choroidal biopsy is a useful technique in eyes with choroidal infiltration, especially when hazy media prohibit fine needle biopsy.

Biopsy, Needle↗
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Temperature changes associated with radiofrequency energy-induced heating of bovine capsular tissue: evaluation of bipolar RF electrodes.

SUMMARY: This in vitro study determined the temperature changes associated with radiofrequency (RF) energy-induced heating of bovine capsular tissue using bipolar RF electrodes. Tissue samples were placed in a saline bath (37 degrees C) and RF energy was applied using 2 different types of bipolar electrodes (VAPR T End Effect and Vapor T Side Effect; Mitek, Westwood, MA). Each electrode was activated for 3 seconds at 10 W, 16 W, and 20 W, for 6 separate data acquisitions. Fluoroptic thermometry designed to be unperturbed by RF fields was used to record temperatures on the tissue surface and at depths of 2 mm, 4 mm, and 5 mm, at 1-second intervals before (5 seconds), during (3 seconds), and after (7 seconds) the application of RF energy. The highest mean temperatures were recorded at the tissue surfaces for the different power settings for each RF electrode type, as follows: End Effect: 48.9 degrees C (10 W), 57.0 degrees C (16 W), and 67.3 degrees C (20 W). Side Effect: 51.5 degrees C (10 W), 62.1 degrees C (16 W), and 71.2 degrees C (20 W). All recorded surface temperatures were within the range known to be acceptable for tissue shrinkage. Gradient effects (i.e., higher-to-lower) were observed for the tissue temperatures measured at the different depth positions. None of the temperatures recorded at the different depths were excessive, suggesting that sensitive anatomic structures should not be damaged by RF energy-induced heating under the conditions described above.

Animals↗
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Radiofrequency energy-induced heating of bovine articular cartilage using a bipolar radiofrequency electrode.

Radiofrequency energy is used for thermal-assisted chondroplasty to treat grade II and III chondromalacia with the lowest possible energy setting that achieves the desired result. The purpose of this in vitro study was to determine the temperature changes associated with the use of radiofrequency energy delivered at different settings to bovine articular cartilage using a bipolar electrode. Cartilage samples were placed in a temperature-controlled (37 degrees C) saline bath for the delivery of radiofrequency energy. A fluoroptic thermometry probe was positioned to record the temperatures at the electrode-tissue interface. The electrode was activated for 2 seconds at settings of V2-120, V2-60, V2-40, and V2-20 in two modes: ablation and desiccation. Additionally, the cartilage samples were visually inspected to determine changes in appearance. The highest average temperatures were as follows: ablation mode, 78.5 degrees C (V2-120), 62.6 degrees C (V2-60), 58.1 degrees C (V2-40), and 54.1 degrees C (V2-20); desiccation mode, 71.8 degrees C (V2-120), 61.4 degrees C (V2-60), 57.7 degrees C (V2-40), and 53.3 degrees C (V2-20). There were statistically significant increases in temperatures associated with each of the respective settings. There were no substantial visual changes produced by the V2-20 settings, while the other settings produced a gradation of effects. These data provide information to help guide the use of a bipolar radiofrequency electrode and electrosurgical system for thermal-assisted chondroplasty.

Animals↗
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The patient's view of the pes anserinus transfer operation for rotatory instability of the knee.

A review of 82 patients was performed to ascertain their subjective evaluations of the pes anserinus transfer procedure for rotatory instability of the knee. Analysis demonstrated a slow improvement in symptoms which occurred over a 12-month period. At that time, 62% of the patients had regained 90% of their preinjury confidence in knee stability.

Evaluation Studies as Topic↗
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The Cybex II evaluation of surgically repaired Achilles tendon ruptures.

Thirty-two patients with 33 complete ruptures of the Achilles tendon with surgical repair were evaluated with the Cybex II isokinetic unit. The evaluations were performed from 6 to 144 months postoperatively. The repaired Achilles tendon had a 16.5% loss of plantarflexion strength and a 17.5% loss of plantarflexion power. The early repairs had a smaller loss of strength and power than late repairs. Twenty-seven of the patients returned to their former level of sports activity.

Achilles Tendon↗
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Correctable elbow lesions in professional baseball players: a review of 25 cases.

In a retrospective study, 20 of 25 professional baseball pitchers (mean age, 24 years; range, 19 to 28 years) who had had a reconstructive surgical procedure on the dominant elbow had satisfactory results (able to return to competitive throwing for one full season or more after surgery). Gentle motion wasinitiated 1 week after the operation on each patient. Exercises for mobilization and muscle strengthening of grip, arm, and shoulder were increased until throwing was initiated 10 to 12 weeks postoperatively. Throwing was gradually increased over several weeks from 30 feet at no more than half speed for 15 min to 60 feet at three-quarter speed. Pitchers were instructed to warm up before throwing and warm down and to continue this practice after they began competitive throwing. The longest period of follow-up had been 4 years (mean, 2.8 years). Four of the 25 pitchers had unsatisfactory results (released from their team in less than one full season because of ineffective pitching and were not picked up by another team). The cause of the release of the other patient-player is controversial. This 25-patient group is too small and the follow-up period is too short for definite conclusions. Our evidence does suggest that surgical procedures directed at medial soft tissue and posterior intra-articular changes carry better prognosis for competitive throwers than other procedures. The radiohumeral articular condition should be evaluated at surgery.

Adult↗
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Staple capsulorrhaphy for recurrent posterior shoulder dislocation.

Recurrent posterior shoulder dislocation or subluxation is uncommon but occurs occasionally in athletes. Ten patients were treated with a posterior shoulder staple capsulorrhaphy. A posterior Bankhart-type-lesion was found in all cases. Eight of the 10 patients had pain relief. The range of motion was usually maintained postoperatively, but no patient returned to his former throwing status. Four patients also had anterior instability. Three patients (30%) had postoperative recurrence of their posterior instability. The two "ligamentous lax" conditions in the series both recurred. The procedure should be supplemented in the "lax" individual. Complications in 4 patients included a painful staple, postoperative adhesions, and symptomatic ectopic bone formation in two patients. Recurrent posterior shoulder dislocation is not a definite indication for operative repair; patients must be carefully selected.

Adolescent↗
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The modification Bristow-Helfet procedure for recurrent anterior shoulder subluxations and dislocations.

A review of 107 cases in which the Bristow-Helfet procedure was done for recurrent anterior shoulder subluxation and dislocation is presented. The redislocation rate was 2% with very few complications. Eighty-nine percent of the patients were satisfied with the procedure. Mean loss of external rotation was 12.6 degrees. Six of the 41 patients with dominant shoulder surgery were capable of throwing in the same manner as they did prior to injury. Five of 24 patients (21%) with a diagnosis of recurrent anterior subluxation continued to have symptoms of instability following surgery. Associated symptoms of posterior or voluntary subluxation may preclude a satisfactory result.

Adolescent↗
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Exercise performance of professional football players.

With the likely hypothesis that the degree to which a football player is physically suited to his position will determine his value as a player, we attempted to describe the characteristics of a given player and position and, from that, to determine the characteristics that make up a first class player in that position. Over a 4-year period 167 football players were examined at the National Athletic Health Institute, Inglewood, California, and grouped according to playing position and class. Position groups were: 1, linemen; 2, linebackers and tight ends; 3, running backs, quarterbacks and kickers; and 4, wide receivers and defensive backs. Classes were: I, rookies (nonstarters); II, veterans (nonstarters); and III, starters (veterans and an occasional rookie). Testing was in two phases, body characteristics and direct measurement of body function. All testing was done in connection with the preseason physical exam. Significant differences were found when data were analyzed by position. Position 1 players were taller, heavier, and had a higher percentage of body fat than players at other positions. These values decreased from Position 1 to Position 4. In terms of cardiovascular fitness the opposite trend was seen. Strength measures were also specific to given position groups. While few differences were seen when data were analyzed by class, one interesting finding was that Class III players (starters) were not only the oldest, but also had the highest level of cardiovascular fitness. Our conclusion is that while size, strength, and endurance are obvious advantages for the successful regular player, there is an unmeasurable quality reflected in the playing ability of the veteran player that is not easily identified in the beginning player.

Adult↗
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The effects of electrical stimulation on the quadriceps during postoperative knee immobilization.

Immobilization of the knee after anterior cruciate ligament (ACL) reconstruction results in marked thigh atrophy and decrease in quadriceps strength that may prolong the rehabilitation program of the injured athlete. Fifteen male volunteers undergoing ACL reconstruction were divided into two groups, stimulation (during immobilization) and nonstimulation. Measurements of thigh circumference and isometric quadriceps strength were tested preoperatively, immediately after cessation of cast immobilization (6 weeks), and at 9 and 12 weeks postoperatively. The changes in circumference and strength between the first preoperative test and all subsequent tests were compared for statistical significance (Student's t-test, P less than 0.5) between the two groups. The decrease in quadriceps strength of the stimulation group during immobilization was significantly less than that of the nonstimulation group, although later differences between the two groups were not significant. There were no significant differences in thigh atrophy between the two groups. In conclusion, isometric quadriceps torque decreases resulting from immobilization can be significantly lessened by application of electrical stimulation during immobilization. Electrical stimulation to the quadriceps does not significantly alter thigh circumference changes that occur during immobilization.

Adolescent↗
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Evaluation of residual instability after arthroscopic meniscectomy in anterior cruciate deficient knees.

Forty-five patients who underwent a partial meniscectomy in an anterior cruciate deficient knee were followed from 2 to 9 years. The average age at the time of the meniscectomy was 28.6 years. The majority of the patients were injured in recreational athletics. The subjects were evaluated preoperatively by a questionnaire and clinical examination, both of which were repeated at followup. The efficacy of the postsurgical rehabilitation was monitored with measurement of quadriceps and hamstring strength on the Cybex Dynamometer. All of the patients had a KT-1000 knee ligament arthrometer test at followup that was compared with the clinical examination. Sixty-five percent of the subjects (13 of 20) with a Lachman and pivot shift of +1 returned to their previous activity level without limitation. Of the patients with a KT-1000 compliance index of 1 mm, 70% (11 of 17) returned to the same athletic level. However, only 20% (2 of 11) of the patients with a clinical instability greater than +1 or a compliance index of 2 mm were able to perform without limitation. The location of the meniscal tear did not correlate with the functional outcome. Six patients required ACL reconstruction.

Adult↗
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Repair of distal biceps tendon ruptures in athletes.

Ten athletes with distal biceps tendon ruptures that had been anatomically repaired with a double-incision techniques were reviewed to determine their functional recovery. All of the patients were men, with an average age of 40 years (range, 25 to 49). Eight of the 10 patients were weight lifters or body builders, and 7 had participated on a competitive level at some point in their athletic careers. Six injured their dominant extremity, and 4 their nondominant extremity. Isokinetic muscle testing of supination and flexion was performed in 8 patients and the results were compared to a control group. Followup averaged 50 months (range, 12 to 105). Patients uniformly graded their subjective results as excellent, with a group mean rating of 9.75 on a 10-point scale. All athletes returned to full, unlimited activity. The contour of the biceps muscle was restored in all cases. Isokinetic muscle testing demonstrated that in those patients with a repaired dominant extremity, supination strength and endurance was normal; in flexion, they had normal strength, but averaged 20% less endurance. Testing of the group that had the nondominant extremity repaired revealed a supination strength deficit of 25%, but normal endurance. Flexion strength and endurance were essentially normal in this group. Anatomic repair of a distal biceps tendon rupture gives consistently excellent subjective and good objective results in athletes, particularly for those sports with high strength demands such as weight lifting and body building. Rehabilitation of the operated arm, especially the repaired nondominant extremity, should be emphasized.

Adult↗