Kinetic Testing Research Articles

Long-term evaluation of coal fly ash and mine tailings co-placement: A site-specific study

This study presents the results of a laboratory investigation conducted to evaluate the efficiency of coal fly ash to control the formation of acid mine drainage (AMD) from mine waste. Site-specific materials, coal fly ash from Atikokan Thermal Generating Station and mine tailings from Musselwhite mine, were mixed at different proportions for the investigation of the drainage chemistry and the optimal mix using static testing (acid–base accounting) and kinetic (column) testing. The acid–base accounting (ABA) results indicated that the fly ash possessed strong alkaline (neutralization) potential (NP) and could be used in the management of reactive mine tailings, thus ensuring prevention of AMD in the long-term. Column tests conducted in the laboratory to further investigate long-term performance of fly ash in the neutralization and prevention of acid mine drainage from tailings similarly showed that mixing fly ash with mine tailings reduces dissolution of many heavy metals from tailings by providing alkalinity to the system. It was found that a fly ash to tailings mass ratio equal to or greater than 15% can effectively prevent AMD generation from Musselwhite mine tailings in the co-placement approach.

Chain-breaking antioxidant activity of reduced forms ofmitochondria-targeted quinones, a novel type of geroprotectors

The chain-breaking antioxidant activities of reduced form of novel type of geroprotectors, mitochondria-targeted quinones (QH(2)) have quantitatively been measured for the first time. To this end, the chain peroxidation of methyl linoleate (ML) in Triton micelles was used as a kinetic testing model. The studied QH(2) were lipophilic triphenylphosphonium cations conjugated by an aliphatic linker to an antioxidant, i.e. a ubiquinol moiety (MitoQH(2)) or plastoquinol moiety (SkQH(2)). The antioxidant activity was characterized by the rate constant k(1) for the reaction between QH(2) and the lipid peroxyl radical (LO(2) (.)) originated from ML: QH(2) + LO(2) (.) --> HQ(.) + LOOH. All the tested QH(2) displayed a pronounced antioxidant activity. The oxidized forms of the same compounds did not inhibit ML peroxidation. The value of k(1) for SkQH(2) far exceeded k(1) for MitoQH(2). For the biologically active geroprotectors SkQ1H(2), the k(1) value found to be as high as 2.2 x 10(5) M(-) (1)s(-) (1), whereas for MitoQH(2), it was 0.58 x 10(5) M(-) (1)s(-) (1). The kinetic behavior of QH(2) suggested that SkQ1H(2) can rather easily diffuse through lipid-water microheterogeneous systems.

Influence of pressurization rate and pressure pulsing on the inactivation of Bacillus amyloliquefaciens spores during pressure-assisted thermal processing.

Pressure-assisted thermal processing (PATP) is an emerging sterilization technology in which a combination of pressure (500 to 700 MPa) and temperature (90 to 120 degrees C) are used to inactivate bacterial spores. The objective of this study was to examine the role of pressurization rate and pressure pulsing in enhancing PATP lethality to the bacterial spore. Bacillus amyloliquefaciens TMW 2.479 spore suspensions were prepared in deionized water at three inoculum levels (1.1 x 10(9), 1.4 x 10(8), and 1.3 x 10(6) CFU/ml), treated at two pressurization rates (18.06 and 3.75 MPa/s), and held at 600 MPa and 105 degrees C for 0, 0.5, 1, 2, 3, and 5 min. Experiments were carried out using custom-fabricated, high-pressure microbial kinetic testing equipment. Single and double pulses with equivalent pressure-holding times (1 to 3 min) were investigated by using the spore suspension containing 1.4 x 10(8) CFU/ml. Spore survivors were enumerated by pour plating, using Trypticase soy agar after incubation at 32 degrees C for 2 days. During short pressure-holding times (< or = 2 min), PATP treatment with the slow pressurization rate provided enhanced spore reduction over that of the fast pressurization rate. However, these differences diminished with extended pressure-holding times. After a 5-min pressure-holding time, B. amyloliquefaciens population decreased about 6 log CFU/ml, regardless of pressurization rate and inoculum level. Double-pulse treatment enhanced PATP spore lethality by approximately 2.4 to 4 log CFU/ml, in comparison to single pulse for a given pressure-holding time. In conclusion, pressure pulsing considerably increases the efficacy of PATP treatment against bacterial spores. Contribution of pressurization rate to PATP spore lethality varies with duration of pressure holding.

A small molecular scaffold for selective inhibition of Wip1 phosphatase.

Using a pyrrole-based scaffold, we developed a series of small molecules that mimic the three-dimensional arrangement of the polar and hydrophobic functional groups of the best cyclic-peptide inhibitor. Iterative optimization cycles of design, synthesis and kinetic testing has lead to an effective inhibitor of Wip1, that is selective for this phosphatase over others. The picture shows the structure of the best inhibitor bound to the active site of the enzyme.

Clinical Outcomes of Coracoclavicular Ligament Reconstructions Using Tendon Grafts

Background Numerous techniques for reconstruction of the coracoclavicular ligaments have been developed to treat acromioclavicular joint separations. A new, stronger method to reconstruct the coracoclavicular ligaments using semitendinosus tendon allografts has been previously described. No outcome studies have been published on this new procedure. Hypothesis Reconstruction of the coracoclavicular ligaments using tendon grafts produces excellent functional results. Study Design Case series; Level of evidence, 4. Methods Nine patients underwent coracoclavicular ligament reconstruction using augmented cadaveric semitendinosus tendon allografts after a grade V acromioclavicular separation. All patients were evaluated for range of motion, strength, closed kinetic chain testing, the American Shoulder and Elbow Surgeons Rating Scale, Pennsylvania Shoulder Score, the Simple Shoulder Test, and the Acromioclavicular Joint Separation Questionnaire. Preoperative and postoperative radiographs were compared. Results Range of motion measurements were normal in all motions except a loss of 5° ± 4° (P < .05) in extension. No significant strength deficits were found. Functional closed kinetic chain tests scored comparatively to standardized norms. American Shoulder and Elbow Surgeons Rating scores were 96 ± 5 out of 100; the Pennsylvania Shoulder Scale scores were 97 ± 3 out of 100; the Simple Shoulder Test scores were 11.6 ± 0 out of 12; and Acromioclavicular Joint Separation Questionnaire scores were 28 ± 3 out of 31. Subjects reported an overall subjective satisfaction of 89% ± 7%. Postoperative radiographs showed no loss of reduction of the acromioclavicular joint in any patient. Conclusion Outcome for coracoclavicular ligament reconstructions using augmented semitendinosus tendon grafts was excellent with full recovery of strength, minimal range of motion loss, and no clinical or radiographic loss of reduction of the acromioclavicular joint. Clinical Relevance This procedure provides an excellent treatment for grade V acromioclavicular separations.

English

A geochemical study was completed as part of an Environmental Assessment Report for De Beers Canada Inc. Snap Lake diamond mine located in the Canadian Northwest Territories. The deposit will be mined using underground methods and consists of a diamond bearing planar kimberlite dyke dipping at about 15 degrees, hosted in metavolcanic and granite rock. Processing will include grinding of the kimberlite ore and a gravity separation circuit on this ore which will result in processed kimberlite waste including a coarse fraction and a finer fraction which will be used to produce a cemented paste backfill material. The cemented paste composed of processed kimberlite, dilution rock, and cement is thickened to a paste-like consistency and will be used to fill the mine voids. The study discussed in this paper was completed to evaluate potential leachate chemistry of the alkaline cemented paste backfill material slated for use underground. The laboratory test program included solids testing, short-term leach testing, and longer-term kinetic testing on a variety of cemented paste blends and additives. Results show that the pH of the leachate remained alkaline for subaqueous test cells and decreased over time for sub-aerial test cells. Geochemical speciation modeling using PHREEQC that was completed to further evaluate leachate chemistry for site specific conditions indicated probable solubility constraints due to secondary mineral precipitation for parameters calcium, chromium, manganese and nickel.

English

Despite numerous shortcomings, kinetic testing incorporating a variety of humidity cell configurations remains an important component of mining waste characterization. The ASTM D 5744-98 and similar devices offer advantages for controlling experimental variables and increasing reproducibility. However, the design is limited in its ability to accommodate very fine-grained process wastes such as autoclave residues due to low permeabilities that restrict fluid movement and may impose diffusion-rate limitations on the oxidation processes. A method has been devised to impregnate fine-grained wastes in a highly permeable fiber substrate that appears to allow excellent access of both air and elution water to individual waste particles. ______________________ 1 Poster paper presented at the 7 th International Conference on Acid Rock Drainage (ICARD), March 26-30, 2006, St. Louis MO. R.I. Barnhisel (ed.) Published by the American Society of Mining and Reclamation (ASMR), 3134 Montavesta Road, Lexington, KY 40502 2 Knight Piesold and Co., Denver, CO 80265-2011. 7 th International Conference on Acid Rock Drainage, 2006 pp 1912-1919 DOI: 10.21000/JASMR06021912

Dipeptide proline diphenyl phosphonates are potent, irreversible inhibitors of seprase (FAPα)

Dipeptidyl peptidase IV (DPP-IV) and seprase belong to a small group of membrane-bound, proline-specific serine proteases, the serine integral membrane proteases (SIMPs). Whilst DPP-IV is the most exhaustively studied peptidase in this class, relatively less is known about the inhibitor/substrate specificity of its close homolog seprase. Additionally, whereas, DPP-IV expression is largely ubiquitous, seprase expression is restricted to tumour and tissue remodelling sites in vivo. Consequently, the highly restricted expression and distribution of seprase potentially make it an excellent therapeutic target for the modulation of neoplastic invasion and metastasis. Against this background, we now wish to report on the design, synthesis, and kinetic testing of a series of dipeptide proline diphenyl phosphonates, against DPP-IV and seprase. The most potent inhibitor of DPP-IV and seprase was found to be Gly-Pro P(OPh) 2, which exhibited overall second-order rate constants of inactivation of 5.24 × 10 5 M −1 min −1 and 1.06 × 10 4 M −1 min −1 against DPP-IV and seprase, respectively. Both proteases displayed differing profiles of susceptibility towards the other members of the series of inhibitors synthesised. In addition, Gly-Pro P(OPh) 2 and Tyr-Pro P(OPh) 2 were found to exert a considerable, dose-dependent anti-invasive effect on the LOX melanoma cell line, in vitro.

Specialized Neuromuscular Training to Improve Neuromuscular Function and Biomechanics in a Patient With Quiescent Juvenile Rheumatoid Arthritis

The purpose of this case report is to describe a novel multidisciplinary approach for evaluating and preparing a patient with quiescent juvenile rheumatoid arthritis (JRA) for safe sports participation. The patient was a 10-year-old girl with a history of bilateral knee arthritis who desired to participate in soccer and basketball. Range of motion and manual muscle testing of the lower extremity were within normal limits. Neuromuscular testing included kinematic and kinetic testing, isokinetic assessment, and postural stability testing. The patient's gait was near normal; however, she had narrowed step width and increased knee flexion at heel-strike. Landing analysis during a box drop vertical jump task showed increased and imbalanced (right versus left lower extremity) peak impact forces. The testing was followed by specialized neuromuscular training (SNT). Following SNT, heel-strike and step width were within normal limits, peak impact forces on the box drop test decreased by 31%, imbalance decreased by 46%, and vertical jump increased 15%. The isokinetic strength ratio between knee flexors and extensors and the overall balance measures were within normal limits and equal bilaterally. Patients with quiescent JRA may have abnormal biomechanics, which could place them at increased risk for injury or future articular cartilage damage. Specialized neuromuscular training may have helped to decrease the patient's risk for future injury or disease progression.

The Mitochondrial Respiratory Chain Is Partially Organized in a Supercomplex Assembly: KINETIC EVIDENCE USING FLUX CONTROL ANALYSIS

The model of the respiratory chain in which the enzyme complexes are independently embedded in the lipid bilayer of the inner mitochondrial membrane and connected by randomly diffusing coenzyme Q and cytochrome c is mostly favored. However, multicomplex units can be isolated from mammalian mitochondria, suggesting a model based on direct electron channeling between complexes. Kinetic testing using metabolic flux control analysis can discriminate between the two models: the former model implies that each enzyme may be rate-controlling to a different extent, whereas in the latter, the whole metabolic pathway would behave as a single supercomplex and inhibition of any one of its components would elicit the same flux control. In particular, in the absence of other components of the oxidative phosphorylation apparatus (i.e. ATP synthase, membrane potential, carriers), the existence of a supercomplex would elicit a flux control coefficient near unity for each respiratory complex, and the sum of all coefficients would be well above unity. Using bovine heart mitochondria and submitochondrial particles devoid of substrate permeability barriers, we investigated the flux control coefficients of the complexes involved in aerobic NADH oxidation (I, III, IV) and in succinate oxidation (II, III, IV). Both Complexes I and III were found to be highly rate-controlling over NADH oxidation, a strong kinetic evidence suggesting the existence of functionally relevant association between the two complexes, whereas Complex IV appears randomly distributed. Moreover, we show that Complex II is fully rate-limiting for succinate oxidation, clearly indicating the absence of substrate channeling toward Complexes III and IV.

English

In 1995, the U.S. Office of Surface Mining (OSM) and the National Mine Land Reclamation Center (NMLRC) joined with the Interstate Mining Compact Commission, the National Mining Association, academia, and other Federal agencies to form the Acid Drainage Technology Initiative (ADTI). The ADTI partnership seeks to identify, evaluate and develop best science based practices to prevent new acid mine drainage sources and eliminate existing sources. The ADTI partnership developed a management structure to oversee the program and developed action plans to address key technical areas. The ADTI organization consists of a coal mining sector, a metal mining sector and a secretariat, overseen by an Operations Committee. The coal mining sector of ADTI is divided into a prediction working group and an avoidance and remediation working group to implement and coordinate the research strategy. This paper summarizes the results of the coal mining sector efforts since the completion of the avoidance and remediation, and prediction handbooks in 1998 and 2000, respectively, and the status of current activities. The activities have included field verification of acid drainage predictions using acid-base accounting, monitoring and follow up evaluation of acid mine drainage passive and in-situ treatment systems, developing standardized kinetic testing protocols, flooded underground mine pools, and issues related to elevated selenium in streams associated with surface mines.

Amiodarone and optic neuropathy.

To investigate the clinical, perimetric, contrast sensitivity and visual evoked potentials findings in patients on longterm treatment with amiodarone. We enrolled 14 patients (age range 47-78 years, mean age 62.7 years) on chronic amiodarone therapy (mean cumulative dose of 519 g), and 14 age-matched control subjects. Participants were submitted to ophthalmological examination, kinetic visual field testing (Goldmann), standard achromatic automated perimetry (central 30-2, Humphrey), computerized isoluminant chromatic contrast sensitivity (CCS) and pattern visual evoked potentials evaluation (VEP). Data from baseline, 6-month and 1-year follow-up examinations were analysed. The main outcome measures were: initial and final corrected visual acuity; corneal, optic disc and fundus abnormalities; mean deviation (MD) and pattern standard deviation (PSD) central 30-2 perimetry parameters; visual field loss on kinetic perimetry; indices of CCS (tritan, protan and deutan axes), and pattern VEP latency (L-VEP) and VEP amplitude (a-VEP). We found a statistically significant difference between the patients and controls' baseline L-VEP and a-VEP measurements (p < 0.001). We found no significant correlation between prolonged L-VEP and duration of amiodarone use (r = 0.07). After a 1-year follow-up, we evidenced an average increment in L-VEP of 1.96 ms and a-VEP measurements showed a decline of 0.69 micro V. In cumulative dose-specific analyses, mean differences between baseline and 12-month L-VEP measurements were more evident in those taking higher than 200 g cumulative amiodarone doses (p = 0.03). We found abnormal tritan CCS results in 19 eyes (68%). Of these, four eyes belonged to patients with no ocular disease (diabetes, cataracts). No significant differences were observed between the baseline and 12-month clinical eye examinations, central 30-2 perimetry and CCS results. We found a significant prolongation in pattern L-VEP and a significant reduction in pattern a-VEP in patients on longterm treatment with amiodarone compared to control subjects. Nevertheless, current data are insufficient to recommend appropriate methods of visual screening.

Acid Drainage Technology Initiative: Continuing Progress in Coal Related Topics

In 1995, the U.S. Office of Surface Mining (OSM) and the National Mine Land Reclamation Center (NMLRC) joined with the Interstate Mining Compact Commission, the National Mining Association, academia, and other Federal agencies to form the Acid Drainage Technology Initiative (ADTI). The ADTI partnership seeks to identify, evaluate and develop "best science" based practices to prevent new acid mine drainage sources and eliminate existing sources. The ADTI partnership developed a management structure to oversee the program and developed action plans to address key technical areas. The ADTI organization consists of a coal mining sector, a metal mining sector and a secretariat, overseen by an Operations Committee. The coal mining sector of ADTI is divided into a prediction working group and an avoidance and remediation working group to implement and coordinate the research strategy. This paper summarizes the results of the coal mining sector efforts since the completion of the avoidance and remediation, and prediction handbooks in 1998 and 2000, respectively, and the status of current activities. The activities have included field verification of acid drainage predictions using acid-base accounting, monitoring and follow up evaluation of acid mine drainage passive and in-situ treatment systems, developing standardized kinetic testing protocols, flooded underground mine pools, and issues related to elevated selenium in streams associated with surface mines.

Test–Retest Reliability of Lower Extremity Functional Tests after a Closed Kinetic Chain Isokinetic Testing Bout

Context:Athletes are often examined for return to sports using a functional-testing algorithm. No research has determined whether a closed kinetic chain (CKC) isokinetic testing bout influences the reliability of functional tests.Objective:To determine whether a concentric CKC isokinetic test bout alters test–retest reliability of lower extremity functional testing.Design:Subjects participated in velocity-spectrum CKC isokinetic bouts on 2 days 1 week apart.Setting:Hospital-based clinic.Participants:28 normal subjects (mean age 26.7 years, height 27.2 cm, weight 75.8 kg).Analysis and Results:Means and SDs were determined. Intraclass correlation coefficients were used to calculate test–retest reliability and between days 1 and 2 ranged from .91 to .98.Conclusions:Even after a CKC isokinetic test bout, test–retest reliability of functional tests is very high. Future research should determine test–retest reliability of functional tests for patients with lower extremity pathology.

PH dependence of the reduction of dioxygen to water by cytochrome c oxidase. 2. Branched electron transfer pathways linked by proton transfer.

Recent time-resolved optical absorption studies in our laboratory have indicated that the putative peroxy intermediate formed during the reduction of dioxygen to water by cytochrome oxidase (P(R)) is a pH-dependent mixture of compound A, P, and F [Van Eps, N., et al. (2003) Biochemistry 42, 5065-5073]. This conclusion is based on a kinetic analysis of flow-flash time-resolved data using a unidirectional sequential scheme with five apparent lifetimes. To account for this observation, we propose a more complex kinetic model that consists of branched pathways, one branch producing the 607 nm P form and the other the 580 nm F form. The two pathways are interconnected, and the rate of exchange between the two is pH-dependent. The kinetic analysis and testing of the new model involves a novel algebraic approach which transforms the intermediates of the complex branched scheme into intermediates comparable to those derived on the basis of a sequential model. The branched model reproduces the experimental data very well and is consistent with a variety of experimental observations. The two branches may arise from two structurally different CO or O(2) conformers or protein conformers, which could lead to different accessibilities of proton donors to the binuclear center.

Rapid integrity assessment of rat and human epidermal membranes for in vitro dermal regulatory testing: correlation of electrical resistance with tritiated water permeability

An approach is presented that allows for rapid selection of robust rat and human epidermal membranes for use on in vitro dermal regulatory studies. Tritiated water (THO) permeability was correlated with electrical resistance (ER) and the results used to propose ER values to judge membrane integrity. Rat and human epidermal membranes were prepared and mounted onto in vitro glass static diffusion cells (0.64 cm 2) maintained at 32 °C. THO permeability coefficients (Kp) were determined and compared with ER measurements. Electrical resistance was also determined for various in vitro cell exposure areas from 0.64 cm 2 to 2.54 cm 2. Our results show that rat epidermal membrane THO Kp values exhibited a lognormal distribution with a median value of 2.76×10 −3 cm/h. Human epidermal membrane THO Kp values were best described by a Weibull distribution with a median value of 1.13×10 −3 cm/h. The corresponding median electrical resistance measurements were 5.59 kΩ for rat and 23 kΩ for human epidermal membranes. Based on the widely used and accepted single point THO Kp thresholds of ⩽2.5×10 −3 cm/h (rat) and ⩽1.5×10 −3 cm/h (human), the corresponding ER values of ⩾5.87 kΩ and ⩾17.1 kΩ were calculated and proposed as acceptable benchmarks for pre-qualifying membranes. In our research exploring the relationship between ER and exposure area we report that an inverse relationship exists between ER and in vitro cell exposure area; as cell area increased, ER decreased. The use of electrical resistance provides a rapid and reliable method for evaluating the integrity of rat and human epidermal membranes for in vitro dermal kinetic testing.

Articular cartilage contact pressure after tibial tuberosity transfer. A cadaveric study.

Medial transfer of the tibial tuberosity has been commonly used for treatment of recurrent dislocation of the patella and patellofemoral malalignment. In this study, six fresh human cadaveric knees were used. Static intrajoint loads were recorded using Fuji Prescale pressure-sensitive film for contact pressure and contact area determination in a closed kinetic chain knee testing protocol. Peak pressures, average contact pressures, and contact areas of the patellofemoral and tibiofemoral joints were calculated on native intact knee specimens and after tibial tuberosity transfer. All native intact knee specimens had a normal Q angle. Medialization of the tibial tuberosity significantly increased the patellofemoral contact pressure. Medial displacement of the tibial tuberosity also significantly increased the average contact pressure of the medial tibiofemoral compartment and changed the balance of tibiofemoral joint loading. The results of our study suggest that caution should be used when transferring a patellar tendon in the face of a preexisting normal Q angle as this will result in abnormally high peak pressure within the tibiofemoral joint. Overmedialization of the tibial tuberosity should be avoided in the varus knee, the knee after medial meniscectomy, and the knee with preexisting degenerative arthritis of the medial compartment.

Visual field deficits in conventional anterior temporal lobectomy versus amygdalohippocampectomy. Egan RA, Shults WT, So N, Burchiel K, Kellogg JX, Salinsky M. Neurology 2000;55:1818–1822.

Visual field defects occur frequently after temporal lobe surgery for epilepsy because of the location of the optic radiations in the temporal lobe. The traditional surgery employed is anterior temporal lobectomy (ATL), often resulting in contralateral homonymous superior quadrantanopias. Another surgical procedure, amygdalohippocampectomy (AH), solely removes the epileptogenic mesial temporal lobe structures including the hippocampus, uncus, and amygdala, presumably sparing the lateral temporal lobe anatomy and, hence, the optic radiations. The objective of this study was to evaluate and identify the incidence of visual field defects after ATL versus AH. All patients had intractable seizures and mesial temporal sclerosis, small tumors localized to only the uncus, amygdala, or hippocampus, or no known pathology. Post-operative kinetic field testing using the 14e isopter on a Goldmann perimeter was performed 30 days or more after surgery. Of 29 patients examined, 14 underwent AH and 15 had ATL. Four of 14 AH patients (28%) had a visual field defect at 10 degrees from center and 11 of 14 (78%) had a visual field defect at 40 degrees. One of 15 ATL patients (7%) had a visual field defect at 10 degrees from center and 11 of 15 (73%) had a visual field defect at 40 degrees. There was no significant difference between surgery types. Although it was hoped that AH would cause fewer or no visual field defects when compared with ATL, this was not the case. The mechanism of injury from both procedures is presumably direct trauma to the optic radiations while accessing the mesial temporal lobe structures. Interestingly, all patients in the study were asymptomatic for their visual field defects.—Nancy J. Newman

Families of clustered microsatellites in a conifer genome.

Microsatellite clustering may account for genetic maps which do not coalesce into the expected number of linkage groups. Microsatellite organization within the large genome of Pinus taeda (1C = 20,000 Mb) was determined by (1) testing whether repeat motifs were sequestered within the low-copy DNA kinetic component and (2) testing for repeat motif clusters within DNA fragments regardless of copy number. Within the low-copy kinetic component, either (AC)n or (AG)n repeat units were present in 32% of sequences. No repeat motifs were found in the total genome control. Clustered repeat motifs were frequent; the (ATG)n triplet repeat motif was located upstream from a CG-rich trinucleotide microsatellite in 26 out of 44 microsatellite sequences. Fourteen of the clustered (ATG)n sequences could be assembled into four microsatellite sequence families based on similarities in the flanking regions. Consistent with the DNA turnover model, family members shared similar flanking regions but differed in repeat motif composition and length.

Goldmann perimetry in acromegaly: A survey of 307 cases from 1951 through 1996

Objective Because visual pathway lesions are a common complication of pituitary tumors, visual field examinations in patients with acromegaly were studied. Proportion and outcome of visual field defects in patients with acromegaly were evaluated. Design Large, retrospective case series. Participants We reviewed 307 cases of acromegaly seen from 1951 through 1996 at a single referral center. Methods Kinetic visual field testing had been performed with the Goldmann perimeter, and the frequency of visual field defects and their correlation with other clinical manifestations and characteristics of the adenoma were examined. Main outcome measures Repeat visual field examinations. Results Of the 307 patients included in the analysis, a visual field defect that could be attributed to the pituitary adenoma was observed in 62 (20.2%) during follow-up. Visual field defects were bilateral in 38 (61.3%) of these cases. Patients with visual field abnormalities were significantly younger ( P = 0.04), had larger tumors ( P < 0.001), had more suprasellar extensions ( P < 0.001), and had higher levels of growth hormone in their serum ( P = 0.04) than patients free of visual field defects. At the end of the follow-up period, visual field examination remained abnormal in 32 (10.4%). Return to a normal visual field examination after treatment was more frequently observed in patients who were less than 40 years of age at the time of diagnosis ( P = 0.004). Secondary empty sella syndrome was the main cause of visual field defects after treatment. Abnormal visual field, either at the time of diagnosis or during follow-up, decreased from 27% of patients between 1951 and 1975 to 15.4% of patients between 1976 and 1996, when modern neuroimaging techniques became available. Conclusions Endocrinologic and neuroimaging follow-up of patients with acromegaly should be accompanied by ophthalmic assessment. Factors predictive of visual field defects have been identified.