Biomedical subjects
Publications and source records attributed to C G Jackson.
The ideal management of most paragangliomas is complete surgical excision. Because of technical advances, issues of resectability have given way to issues of functional outcome and postsurgical quality of life. This article reviews the surgical strategy for craniocervical paragangliomas. Intracranial extension, defect reconstruction, and cranial nerve rehabilitation are addressed.
OBJECTIVE: The glomus tumor is an enigmatic middle ear neoplasm commonly delayed in diagnosis. Frequently grouped with its skull base counterpart, surgery and radiation are often recommended as therapy. The objective of this report is to highlight the diagnosis and surgical treatment of this neoplasm in a large series. Tumor control in the long term is defined. STUDY DESIGN: Retrospective case review. SETTING: Private practice-tertiary referral center. PATIENTS: All patients surgically treated for glomus tympanicum tumors from May 25, 1972 to July 3, 1998 (N = 80). INTERVENTIONS: Surgical excision of glomus tympanicum tumors. MAIN OUTCOME MEASURE: Total tumor control in the long term. RESULTS: Surgical treatment resulted in long-term tumor control for the vast majority of the patients studied. CONCLUSIONS: Surgery provides excellent control of glomus tympanicum tumors. It is safe and well tolerated, with minimal morbidity.
OBJECTIVE: The age of modern microsurgery has made resection of glomus tumors with extensive skull base involvement possible. Resection of extensive lesions is not without risk of major complication or new cranial nerve deficit. Because glomus tumors are rare and slow growing, data reflecting recurrence risk after resection using modern skull base techniques are lacking. These factors complicate the accurate definition of efficacy of surgical resection and its functional cost. The object of this review is to determine the current incidence of major complications, the surgical cranial nerve deficit, the long-term control rate, and the recurrence risk in patients undergoing surgical resection of glomus jugulare tumors. STUDY DESIGN: Retrospective case review. SETTING: Private practice tertiary referral center. PATIENTS AND INTERVENTIONS: One hundred seventy-six patients with glomus tumors underwent 182 lateral skull base resections between 1972 and 1998. MAIN OUTCOME MEASURES: Major complications, tumor recurrence, postoperative functional capacity, and factors affecting the incidence of each were assessed. RESULTS: Complete surgical control was achieved in 85% of cases. There were nine cases of recurrence, for a recurrent rate of 5.5% (9/164). Cerebrospinal fluid leakage occurred in 4.5% of cases with intracranial extension. New deficits for cranial nerves IX, X, XI, and XII occurred in 39%, 25%, 26%, and 21% of cases, respectively. Satisfactory functional recovery was achieved in an overwhelming majority of cases. The mortality rate was 2.7% (5/182). CONCLUSIONS: Surgical resection of glomus tumors is established as an effective technique with good functional outcomes and long-term control.
Tracking the movement of insects in their natural habitat is essential for understanding their basic biology, demography, and ethology. A wide variety of markers have been used to assess insect population dynamics, dispersal, territoriality, feeding behavior, trophic-level interactions, and other ecological interactions. The ideal marker should persist without inhibiting the insect's "normal" biology. Furthermore, the marker should be environmentally safe, cost-effective, and easy to use. In this article, we review the current state of knowledge regarding insect marking, document the advantages and limitations of each marking technique, and discuss advances made in marking insects over the past decade.
Arthritis and related musculoskeletal conditions occur with great frequency in the population world wide, causing significant morbidity and, in some instances, increased mortality. Affecting both the young and the old, 15% of the population in the US was estimated in 1995 to have some form of arthritis with an increase to 18% projected by the year 2020 [1]. The economic impact of arthritis and related disorders in the US alone was estimated to be 194.4 billion US dollars in 1992 and future costs are virtually certain to increase given the chronic nature of these diseases, their expanding prevalence and the considerable expense associated with newer therapies [2]. With no cure presently available, the aim of current treatment is to reduce inflammation, ameliorate symptoms and improve functional capacity. Non-steroidal anti-inflammatory drugs (NSAIDs), which suppress the formation of pro-inflammatory prostaglandins by antagonising the action of cyclooxygenase (COX), have been the mainstay of arthritis treatment for hundreds, if not, thousands of years. The clinical use of NSAIDs, however, has long been associated with significant toxicity. The recognition of two COX isoforms, cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), both suppressed by traditional NSAIDs, has led to an expanded hypothesis of NSAID action which consists of two postulates, namely, the efficacy of NSAIDs in the treatment of arthritis is due to the suppression of COX-2, while much of the toxicity associated with non-selective NSAIDs is the consequence of COX-1 suppression. The emergence of agents which selectively inhibit COX-2 has made it possible to clinically evaluate the validity of each of these postulates. In this report, the published experience with selective COX-2 inhibitors in the treatment of mechanical and inflammatory arthropathies is reviewed to examine the premise that isolated COX-2 suppression is comparable in efficacy to the dual COX-1/COX-2 suppression produced by non-selective NSAIDs.
The braconid wasp, Fopius arisanus (Sonan), a biological control agent for Mediterranean fruit fly, Ceratitis capitata (Wiedemann), was studied in coffee, Coffea arabica L. Fopius arisanus, comprised 79.3% of the total parasitoids (7,014) recovered from fruits collected at three small coffee farms. Data from seasonal host/parasitoid studies at a large coffee plantation also suggested that the most effective natural enemy of C. capitata in coffee may now reside in Hawaii. The original parasitoids introduced into Hawaii for C. capitata control (Diachasmimorpha tryoni (Cameron), Tetrastichus giffardianus Silvestri, and Dirhinus giffardii Silvestri) are now rare. Abundance of F. arisanus with respect to other parasitoids collected was influenced by elevation (274, 457, 610 m). Fopius arisanus was the dominant parasitoid at all three elevations, Diachasmimorpha longicaudata (Ashmead) occurred consistently, and T. giffardianus was abundant only at low elevation. The impacts on C. capitata and F. arisanus populations of bait sprays containing malathion, spinosad, or phloxine B applied to coffee were also evaluated. All three bait sprays suppressed C. capitata populations. Spinosad and phloxine B bait sprays appeared less harmful to the wasp than malathion. Fopius arisanus offers the potential for areawide management of C. capitata that includes biological control and integration with more environmentally safe chemical controls such as spinosad and phloxine B bait sprays.
Psoriatic arthritis is a chronic inflammatory arthropathy which can be distinguished from rheumatoid arthritis on the basis of differing patient demographics, genetic predisposition, histopathologic change, radiographic appearance, and clinical course. The cause of psoriatic arthritis remains unknown but appears to be autoimmune in nature as its pathogenesis is characterized by persistent synovial inflammation resulting in damage to the articular cartilage and osteolysis. Compared with rheumatoid arthritis, distinct lymphocyte subpopulations and pro-inflammatory cytokine levels appear to be present within the joint but the importance and therapeutic implications of these differences is uncertain. The clinical presentation of psoriatic arthritis is variable and overlapping patterns of joint involvement affecting both the appendicular and axial skeleton are seen. For patients with mild synovial disease and a favorable prognosis, the use of a nonsteroidal anti-inflammatory drug for symptomatic relief is often sufficient. However, the destructive potential of psoriatic arthritis is increasingly recognized and patients with more synovial disease and radiographic change at presentation appear to be at risk for greater morbidity and increased mortality. Immunomodulating therapy has the potential to suppress joint inflammation and preserve functional capacity but true disease modification has yet to be shown. The toxicity associated with presently available immunomodulatory agents makes careful patient selection and conscientious monitoring essential. The efficacy of methotrexate and sulfasalazine in patients with psoriatic arthritis is well defined while more anecdotal reports of benefit exist for other agents including the antimalarials, azathioprine, colchicine, cyclosporine, and the retinoids. For all treatment regimens, the magnitude of clinical improvement demonstrated to date has been rather small and quite subjective in character with few controlled studies of adequate size and duration having been reported. Emerging biologic therapies, such as those which target tumor necrosis factor, will hopefully provide future treatment options with greater efficacy and improved safety for patients with psoriatic arthritis.
OBJECTIVE: To evaluate intradural drilling as a mechanism for the development of postoperative headache after retrosigmoid craniectomy. STUDY DESIGN: A retrospective review of charts was performed on 565 retrosigmoid approaches to the cerebellopontine angle performed between January 1980 and January 1998. Patients treated with retrosigmoid vestibular nerve section without intradural drilling were compared with patients who underwent retrosigmoid removal of vestibular schwannomas in which intradural drilling was performed for exposure of the internal auditory canal. SETTING: Private practice tertiary referral center. PATIENTS: Consecutive patients undergoing retrosigmoid approach between January 1980 and January 1998 were reviewed. MAIN OUTCOME MEASURES: The presence of headache, duration of headache, and severity of headache were noted. RESULTS: In this large series, 54% of patients experienced headaches after vestibular schwannoma removal, and 5% of patients experienced headaches after vestibular nerve section (p < 0.01, chi-square). CONCLUSIONS: Postoperative headache is not a characteristic of retrosigmoid craniectomy in the absence of intradural drilling. Intradural drilling is a probable cause of headache after the retrosigmoid approach. Cranioplasty is not necessary to prevent a high incidence of postoperative headache after retrosigmoid approach.
BACKGROUND: Patients treated with methotrexate for rheumatoid arthritis often improve but continue to have active disease. This study was undertaken to determine whether the addition of etanercept, a soluble tumor necrosis factor receptor (p75):Fc fusion protein (TNFR:Fc), to methotrexate therapy would provide additional benefit to patients who had persistent rheumatoid arthritis despite receiving methotrexate. METHODS: In a 24-week, double-blind trial, we randomly assigned 89 patients with persistently active rheumatoid arthritis despite at least 6 months of methotrexate therapy at a stable dose of 15 to 25 mg per week (or as low as 10 mg per week for patients unable to tolerate higher doses) to receive either etanercept (25 mg) or placebo subcutaneously twice weekly while continuing to receive methotrexate. The primary measure of clinical response was the American College of Rheumatology criteria for a 20 percent improvement in measures of disease activity (ACR 20) at 24 weeks. RESULTS: The addition of etanercept to methotrexate therapy resulted in rapid and sustained improvement. At 24 weeks, 71 percent of the patients receiving etanercept plus methotrexate and 27 percent of those receiving placebo plus methotrexate met the ACR 20 criteria (P<0.001); 39 percent of the patients receiving etanercept plus methotrexate and 3 percent of those receiving placebo plus methotrexate met the ACR 50 criteria (for a 50 percent improvement) (P<0.001). Patients receiving etanercept plus methotrexate had significantly better outcomes according to all measures of disease activity. The only adverse events associated with etanercept were mild injection-site reactions, and no patient withdrew from the study because of adverse events associated with etanercept. CONCLUSIONS: In patients with persistently active rheumatoid arthritis, the combination of etanercept and methotrexate was safe and well tolerated and provided significantly greater clinical benefit than methotrexate alone.
Facial paralysis is a potentially devastating disorder with numerous implications. Multiple entities must be considered in its etiology, and recent advances in microbiology, radiographic imaging, electrodiagnostic testing, and microsurgery have provided great insight into the pathophysiology, diagnosis, treatment, and rehabilitation of the facial nerve. Recent DNA PCR testing has shed new insight into the potential cause for Bell's palsy. This article focuses on the evaluation, differential diagnosis, medical treatment, and rehabilitation of facial nerve pathology with primary emphasis on facial paralysis. Surgical management is also discussed, including reanimation of the paralyzed face.
Acidosis reduces the ability of nitric oxide synthase to generate nitric oxide (NO) from L-arginine (L-arg), even if dietary intake or circulating plasma levels of L-arg are normal. During systemic acidemia, therefore, vascular perfusion in one or more organs may be compromised. Arginine is also a powerful anabolic amino acid. If dietary sources of L-arg are lower than normal, or if the production of NO is reduced even without frank acidemia, then vascular perfusion, and growth, and tissue repair are likely to be compromised. Two conditions in which acidemia is reported to occur, namely slow fetal growth in utero (acidemia is severe) and loss of bone and muscle in microgravity (acidemia is modest), are compared with respect to the accompanying alteration in the balance between acidemia and NO production.
OBJECTIVES/HYPOTHESIS: To ascertain the incidence of malignancy in a large glomus and skull base series and to compare the clinical course of such patients with those who do not have malignant skull base lesions. STUDY DESIGN: Retrospective review of all skull base surgery cases treated at the Otology Group between 1970 and 1995. RESULTS: In a series of 175 jugulotympanic glomus tumors, 9 cases (5.1%) were identified. The surgery required for their extirpation is more extensive than nonmalignant glomus tumors. Attendant deficits and mortality from these procedures are accordingly greater. Five-year survival in this limited population was 72%. Prolonged periods of survival are possible with distant metastases. CONCLUSIONS: This rate of malignancy should advocate against a watchful, waiting approach. Radiation therapy is not advocated as a primary modality for this type of tumor, as it may lead to recurrence/persistence with either subsequent malignant degeneration and metastases or local recurrence.
BACKGROUND: The deconditioning syndrome from prolonged bed rest (BR) or spaceflight includes decreases in maximal oxygen uptake (VO2max), muscular strength and endurance, and orthostatic tolerance. In addition to exercise training as a countermeasure, +Gz (head-to-foot) acceleration training on 1.8-2.0 m centrifuges can ameliorate the orthostatic and acceleration intolerances induced by BR and immersion deconditioning. PURPOSE: Study A was designed to determine the magnitude and linearity of the heart rate (HR) response to human-powered centrifuge (HPC) acceleration with supine exercise vs. passive (no exercise) acceleration. Study B was designed to test the hypothesis that moderate +Gz acceleration during exercise will not affect the respective normal linear relationships between exercise load and VO2max, HR, and pulmonary ventilation (VEBTPS). Study C: To determine if these physiological responses from the HPC runs (exercise + on-platform acceleration) will be similar to those from the exercise + off-platform acceleration responses. METHODS: In Study A, four men and two women (31-62 yr) were tested supine during exercise + acceleration and only passive acceleration at 100% [maximal acceleration (rpm) = Amax] and at 25%, 50%, and 75% of Amax. In Studies B and C, seven men (33+/-SD 7 yr) exercised supine on the HPC that has two opposing on-platform exercise stations. A VO2max test and submaximal exercise runs occurred under three conditions: (EX) exercise (on-platform cycle at 42%, 61%, 89% and 100% VO2max) with no acceleration; (HPC) exercise + acceleration via the chain drive at 25%,50%, and 100% Gzmax (35%, 72% and 100% VO2max); and (EXA) exercise (on-platform cycle at 42%, 61%, 89%, and 100% VO2max) with acceleration performed via the off-platform cycle operator at +2.2+/-0.2 Gz [50% of max (rpm) G]. RESULTS: Study A: Mean (+/-SE) Amax was 43.7+/-1.3 rpm (mean = +3.9+/-0.2, range = 3.3 to 4.9 Gz). Amax run time for exercise +acceleration was 50-70 s, and 40-70 s for passive acceleration. Regression of X HR on Gz levels indicated explained variances (r2) of 0.88 (exercise) and 0.96 (passive). The mean exercise HR of 107+/-4 (25%), to 189+/-13 (100%) bpm were 43-50 bpm higher (p < 0.05) than comparable passive HR of 64+/-2 to 142+/-22 bpm, respectively. Study B: There were no significant differences in VO2, HR or VEBTPS at the submaximal or maximal levels between the EX and EXA runs. Mean (+/-SE) VO2max for EX was 2.86+/-0.12 L x min(-1)(35+/-2 ml x min(-1) x kg(-1)) and for EXA was 3.09+/-0.14 L x min(-1) (37+/-2 ml-min(-1) x kg(-1)). Study C: There were no significant differences in the essentially linear relationships between the HPC and EXA data for VO2 (p = 0.45), HR (p < 0.08), VEBTPS (p = 0.28), or the RE (p = 0.15) when the exercise load was % VO2max. CONCLUSION: Addition of + 2.2 Gz acceleration does not significantly influence levels of oxygen uptake, heart rate, or pulmonary ventilation during submaximal or maximal cycle ergometer leg exercise on a short-arm centrifuge.
BACKGROUND: The influence of non-ionic osmols on thermoregulation is unclear. HYPOTHESIS: Hyperglycemia will attenuate the rise in exercise core temperature. METHODS: Dehydrated by 4-h of water immersion (34.5 degrees C) to the neck, 6 men, (35+/-SD 7 yr) participated in each of three trials where 2.0 g x kg(-1) body wt of oral glucose (33.8% weight per volume) was consumed followed by 80 min supine rest (Glu/Rest), or 70 min supine cycle exercise at 62.8%+/-SE 0.5% (1.97+/-0.02 L x min(-1)) peak O2 uptake, followed by 10 min supine recovery with prior (Glu/Ex) or without glucose (No Glu/Ex) ingestion. Blood samples were taken periodically for measurement of Hb, Hct, Na+, K+, Osm, and glucose; mean skin (Tsk) and rectal (Tre) temperatures, and sweating rate (resistance hygrometry) and skin blood velocity (laser Doppler) were measured intermittently. RESULTS: Mean percent changes in plasma volume (p<0.05) for the exercise trials were not different: -12.3+/-2.2% (No Glu/Ex) and -12.1+/-2.1% (Glu/Ex). Mean (+/-SE) pre-exercise plasma [glucose] for Glu/Ex was higher than that of No Glu/Ex (108.4+/-3.9 vs. 85.6+/-1.6 mg x dL(-1), respectively, p<0.05). Glu/Ex vs. No Glu/Ex data, respectively, at the end of exercise indicated that: Tre was lower by 0.4 degrees C (38.2+/-0.2 vs. 38.6+/-0.1 degrees C, p<0.05), Tsk was lower (32.0+/-0.3 vs. 32.4+/-0.2 degrees C, p<0.05), forearm sweating rate was lower (0.94+/-0.09 vs. 1.05+/-0.07 mg x cm(-2) x min(-1), p<0.05); and head (temporal) skin blood velocity was not different (1.67+/-0.21 vs. 1.51+/-0.24 Hz x 10(3), NS). CONCLUSIONS: Elevation of plasma [glucose] prior to supine submaximal exercise in dehydrated men attenuates the increase of Tre without alteration of heat production, total body sweating, serum electrolytes and osmolality, or exercise-induced hypoglycemia: the mechanism may be enhanced peripheral blood flow that could enhance body heat loss.
BACKGROUND: Vagal paragangliomas (VPs) arise from paraganglia associated with the vagus nerve. Approximately 200 cases have been reported in the medical literature. Because of their rarity, most information regarding these tumors has arisen from case reports and small clinical series. OBJECTIVE: To detail the clinicopathologic features of 46 patients with VP with an emphasis on the role of a multidisciplinary skull base team in both the successful extirpation and rehabilitation. DESIGN: Retrospective review of 46 patients with VP managed by a single skull base team. SETTING: An academic tertiary medical center. RESULTS: Forty-six patients were treated over a 20-year period (1978-1998). Ten (22%) demonstrated intracranial extension. There was a history of familial paragangliomas in 9 (20%) of the patients. The incidence of multicentric paragangliomas was 78% in patients with familial paragangliomas vs 23% in patients with nonfamilial paragangliomas. Management of this group of 46 patients consisted of surgery (n = 40), radiation therapy (n = 4), and observation (n = 2). The operative approach consisted of a transcervical excision often combined with a transtemporal or lateral skull base approach as dictated by the tumor extent. Postoperative cranial nerve deficits were common, and, as such, aggressive rehabilitation was a vital component in the management of these tumors. CONCLUSIONS: The management of VP and its associated cranial nerve deficits remains a difficult clinical problem. Options for treatment include surgical resection, radiation therapy, and, in selected cases, observation. Surgical extirpation requires a multidisciplinary skull base team to achieve complete tumor resection. Radiation therapy is reserved for elderly patients and patients at risk for bilateral cranial nerve deficits. Rehabilitation of cranial nerve deficits is an integral part of the management of VP.
OBJECTIVES: Suboccipital craniotomy is a frequently used surgical approach for removal of cerebellopontine angle (CPA) tumors. A frequently cited consequence, however, is the high incidence of postoperative headaches. Much has been written regarding prevention of these headaches, but little has been written of their treatment. The authors review their extensive experience in suboccipital tumor removal and the medical management of postoperative headache, highlighting the recent use of a regimen of divalproex sodium and verapamil. STUDY DESIGN: Retrospective chart review. METHODS: The charts of a consecutive series of patients having suboccipital craniotomies for CPA tumors were reviewed. Presence, duration, and severity of headache were noted. Medical treatments and their effectiveness were also noted. RESULTS: Between 1980 and 1997, 228 patients underwent suboccipital craniotomy for removal of CPA tumors. Of these patients, 124 (54.4%) complained of headache. For 62 (27.2%) the headaches persisted for more than a year after surgery. Twenty-nine patients (12.7%) received no relief from any medication. Ten of these patients received a regimen of divalproex sodium and verapamil, with all patients obtaining significant relief. CONCLUSION: Headache is a significant problem with the suboccipital approach for acoustic tumor removal. The majority of patients that complain of headache can be adequately treated with nonsteroidal anti-inflammatory drugs (NSAIDs). If pain is unrelieved by NSAIDs, treatment becomes problematic. The authors' early experience with divalproex sodium/verapamil is encouraging and deserves further investigation as a treatment for these refractory cases.
OBJECTIVE: To statistically identify factors most important in affecting CN7 outcome in lateral skull base surgery for benign lesions. STUDY DESIGN: A retrospective review of 217 nonmalignancy lateral skull base procedures from 1970 to 1995 at the Otology Group in Nashville. METHODS: Charts were reviewed for epidemiology, histopathology, staging, type of CN7 mobilization (none, short, long, severance with reanastomosis, and resection), preoperative and postoperative CN7 function, surgery performed, and survival. RESULTS: Average House-Brackman (HB) scores for mobilizations were as follows: short, 1.65: long, 2.74: and grafting, 4.33. Factors found to affect outcome in a statistically significant fashion were preoperative HB score, staging, type of CN7 manipulation, and surgical approach. Meningiomas were found to have a worse outcome than glomus tumors. CONCLUSIONS: Complete resection of tumors should be performed with minimal manipulation of the facial nerve based on regional anatomy and tumor anatomy.
PURPOSE: The purpose of this study was to determine the test-retest reliability of an isometric handgrip exercise protocol designed to evaluate heart rate and arterial pressure responses in individuals with multiple sclerosis (MS). METHODS Three males and eleven females, aged 24 through 51, performed isometric handgrip contractions at 30% of maximal voluntary contraction (MVC) to the point of fatigue (defined as inability to maintain the target force for three consecutive seconds). During this exercise, rate of perceived exertion (RPE) was recorded every 30 s. Heart rate and beat-to-beat systolic, diastolic, and mean arterial pressures were recorded continuously throughout the duration of exercise. Surface EMG was monitored continuously via loudspeaker to provide feedback on extraneous muscular activity. Each subject performed three trials. A repeated measures ANOVA was used to calculate interclass reliability estimates for each dependent variable. RESULTS: Reliability estimates for MVC and time to fatigue were 0.98 and 0.84, respectively. Reliability estimates for the following dependent variables at the point of fatigue were: RPE, 0.90; delta HR, 0.97; delta systolic pressure, 0.92; delta diastolic pressure, 0.87; and delta MAP, 0.88. CONCLUSIONS: We conclude that this isometric handgrip protocol is a reliable method for evaluating heart rate and blood pressure responses in MS patient.