Repeat gamma knife stereotactic radiosurgery in the treatment of trigeminal neuralgia: A single-center experience and focused review of the literature.

OBJECTIVES: Repeat Gamma Knife stereotactic radiosurgery (GKSR) for refractory trigeminal neuralgia (TGN) is an increasingly common practice. Prior studies have reported varying success rates and incidence of trigeminal nerve dysfunction following repeated GKSR. We report treatment outcomes and toxicity in patients following repeat GKSR for TGN at the University of Alabama at Birmingham (UAB) with a focused review of the literature. METHODS: We retrospectively reviewed medical records of 55 TGN patients re-treated with radiosurgery using the Leksell Gamma Knife® at the University of Alabama at Birmingham between 1996 and 2012. Outcomes were defined using the Modified Marseille Scale. Demographics, prior treatments and symptom duration were correlated with outcomes. RESULTS: Eighteen patients (33%) achieved Marseille Class I or II, 14 (25%) Class III or IV, and 23 (42%) Class V at a mean follow-up of 14.4 months. Twenty-five patients (45%) developed new trigeminal nerve dysfunction after re-treatment. Of these, four (16%) did not develop dysfunction until subsequent microvascular decompression (MVD) for inadequate symptom relief. CONCLUSIONS: Although more than half of the patients undergoing repeat GKSR for refractory TGN maintained excellent or good outcomes (Marseille classes I-IV) at an average follow-up of 14.4 months, neither age, gender, nor pre-treatment duration of symptoms or interval between treatments had a statistically significant effect on outcomes. Following repeat GKSR, patients have increased risk for new-onset trigeminal nerve dysfunction and those undergoing MVD after repeat GKSR may have an increased risk for new-onset trigeminal nerve dysfunction.

Estimating 3-dimensional surface areas of small scleractinian corals.

Stressor-response research on stony corals in the laboratory relies on detecting relatively small changes in the size of coral fragments throughout the course of an experiment. Coral colonies are complex, three-dimensional (3D) communities of organisms, so small changes in size are best detected by changes in 3D surface area. Traditional methods to estimate 3D coral surface area commonly require destruction of the sample, thereby eliminating repeat measurements and the ability to calculate growth rate. However, non-destructive two-dimensional (2D) photogrammetry can be used if defensible relationships with 3D surface area can be established. In this study, 165 coral skeletons representing four stony coral species (Pocillopora damicornis, Madracis mirabilis, Orbicella faveolata, Porites porites) were photographed in 2D (top and side views) and then imaged with 3D laser scanning. Significant linear relationships were found between the 3D surface areas (laser) and the sum of various combinations of top and side view surface areas captured by 2D digital photography. The relationships were very strong for simple colony shapes and more variable as coral fragments increased in size and complexity. This study demonstrates an efficient method for obtaining estimates of 3D coral surface area from non-destructive 2D photogrammetry, allowing measurement of growth rate throughout experimental exposure periods.

Assessing land use, sedimentation, and water quality stressors as predictors of coral reef condition in St. Thomas, U.S. Virgin Islands.

Coral reef condition on the south shore of St. Thomas, U.S. Virgin Islands, was assessed at various distances from Charlotte Amalie, the most densely populated city on the island. Human influence in the area includes industrial activity, wastewater discharge, cruise ship docks, and impervious surfaces throughout the watershed. Anthropogenic activity was characterized using a landscape development intensity (LDI) index, sedimentation threat (ST) estimates, and water quality (WQ) impairments in the near-coastal zone. Total three-dimensional coral cover, reef rugosity, and coral diversity had significant negative coefficients for LDI index, as did densities of dominant species Orbicella annularis, Orbicella franksi, Montastraea cavernosa, Orbicella faveolata, and Porites porites. However, overall stony coral colony density was not significantly correlated with stressors. Positive relationships between reef rugosity and ST, between coral diversity and ST, and between coral diversity and WQ were unexpected because these stressors are generally thought to negatively influence coral growth and health. Sponge density was greater with higher disturbance indicators (ST and WQ), consistent with reports of greater resistance by sponges to degraded water quality compared to stony corals. The highest FoRAM (Foraminifera in Reef Assessment and Monitoring) indices indicating good water quality were found offshore from the main island and outside the harbor. Negative associations between stony coral metrics and LDI index have been reported elsewhere in the Caribbean and highlight LDI index potential as a spatial tool to characterize land-based anthropogenic stressor gradients relevant to coral reefs. Fewer relationships were found with an integrated stressor index but with similar trends in response direction.

Contrasting responses of coral reef fauna and foraminiferal assemblages to human influence in La Parguera, Puerto Rico.

Coral reef biota including stony corals, sponges, gorgonians, fish, benthic macroinvertebrates and foraminifera were surveyed in coastal waters near La Parguera, in southwestern Puerto Rico. The goal was to evaluate sensitivity of coral reef biological indicators to human disturbance. Proxies for human disturbance were measured as distance to town (DTT) and rankings of a low-level sediment contamination gradient analyzed from a previous study. Contaminant rank and DTT showed that percent mud, stony coral taxa richness, reef rugosity, and numbers of invertebrates and sponges were higher at sites closer to human disturbance, but a foraminiferal assemblage index was significantly lower at sites with higher proxies for human disturbance. Fish indicators showed no significant relationships with human activity, but associations between fish community measures and certain measures of stony corals, gorgonians and sponges were found. Contrasting responses between foraminifera and reef organisms may be due to greater exposure and sensitivity of foraminifera to sediment contaminants.

Relationships between tissue contaminants and defense-related characteristics of oysters (Crassostrea virginica) from five Florida bays.

Evidence linking bivalve defense responses with pollutant exposure is increasing. Contaminant effects on immune or defense responses could influence the ability of an organism to resist infectious disease. This study explored relationships between xenobiotic chemicals accumulated in oyster (Crassostrea virginica) tissue and various measures of putative oyster internal defense activities and physiological condition. Defense-related and physiological measurements were made on individual oysters collected from 22 sites at five Florida bays and pooled oyster tissue from each site was analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and certain pesticides. Chemical concentrations, physiological condition, and hemocyte and hemolymph characteristics varied across bays and among sites within a bay. Within-bay comparisons showed that sites with high oyster defense-related activities often had accompanying high tissue concentrations of one or more classes of xenobiotic chemicals. Correlation analysis performed across bays demonstrated significant positive relationships between most defense-related characteristics and at least one contaminant, including various PAH, PCB and trace metal analytes. In combination with other recent studies, these results strengthen the hypothesis that certain xenobiotic chemicals may be associated with elevated oyster hemocyte activities, even though the ultimate influence on disease resistance remains unknown.

A survey of oysters Crassostrea virginica from Tampa Bay, Florida: associations of internal defense measurements with contaminant burdens.

Oysters from 16 sites in Tampa Bay, Florida, were collected during a 6-week period in winter 1993 and analyzed for both biological characteristics and tissue chemical concentrations. Using previous sediment contamination and toxicity data, oyster tissues from the selected sites were expected to exhibit a wide range in both quantity and type of chemicals. Chemical analysis showed tissue concentrations at some of these sites to be greater than national averages, as reported by the National Status and Trends Mussel Watch Program, for total PAH, total PCB, total chlordanes, DDT, Cu, Pb and Zn. Measures of oyster internal defense, including hemocyte density, rate of locomotion and superoxide generation, varied significantly among sites and were generally higher at sites with higher tissue concentrations of xenobiotic chemicals. Potential associations between oyster defense characteristics and accumulated chemical contaminants, either singly or in chemical classes, were explored using correlation analysis and a composited ranking procedure. Positive relationships were found for hemocyte characteristics with certain trace metal (Cu, Sn and Zn) and PAH analytes, whereas negative relationships were found with certain PCB and pesticide analytes. Heightened defenses in contaminated conditions may reflect a hemocyte process for sequestration and detoxification of environmental contaminants. Oysters from four of the 16 sites were additionally collected in June and September 1993 and site-related differences did not closely parallel those obtained in winter. Seasonal environmental factors may have altered contaminant-related differences among sites.

Factors influencing in vitro killing of bacteria by hemocytes of the eastern oyster (Crassostrea virginica).

A tetrazolium dye reduction assay was used to study factors governing the killing of bacteria by oyster hemocytes. In vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. Vibrio parahaemolyticus strains, altered in motility or colonial morphology (opaque and translucent), and Listeria monocytogenes mutants lacking catalase, superoxide dismutase, hemolysin, and phospholipase activities were examined in winter and summer. Vibrio vulnificus strains, opaque and translucent (with and without capsules), were examined only in summer. Among V. parahaemolyticus and L. monocytogenes, significantly (P < 0.05) higher levels of killing by hemocytes were observed in summer than in winter. L. monocytogenes was more resistant than V. parahaemolyticus or V. vulnificus to the bactericidal activity of hemocytes. In winter, both translucent strains of V. parahaemolyticus showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. In summer, only one of the V. parahaemolyticus translucent strains showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. No significant differences (P > 0.05) in killing by hemocytes were observed between opaque (encapsulated) and translucent (nonencapsulated) pairs of V. vulnificus. Activities of 19 hydrolytic enzymes were measured in oyster hemolymph collected in winter and summer. Only one enzyme, esterase (C4), showed a seasonal difference in activity (higher in winter than in summer). These results suggest that differences existed between bacterial genera in their ability to evade killing by oyster hemocytes, that a trait(s) associated with the opaque phenotype may have enabled V. parahaemolyticus to evade killing by the oyster's cellular defense, and that bactericidal activity of hemocytes was greater in summer than in winter.

Microemboli detected by transcranial Doppler monitoring in patients during carotid angioplasty versus carotid endarterectomy.

UNLABELLED: Microemboli, as detected by transcranial Doppler monitoring, have been shown to be a potential cause of strokes after carotid endarterectomy. We retrospectively reviewed 105 patients who underwent transcranial Doppler monitoring during 112 procedures for the treatment of 115 carotid bifurcation stenoses: 40 by percutaneous angioplasty with stenting and 75 by carotid endarterectomy. In PTAS procedures (n = 40), there was a mean of 74.0 emboli per stenosis (range 0-398, P = 0.0001) with 4 neurologic events per patient (P = 0.08). In CEA procedures (n = 76), there was a mean of 8.8. emboli per stenosis (range 0-102, P= 0.0001) with 1 neurologic event per patient (P = 0.08). The post-procedural neurological events in the percutaneous angioplasty with stenting population included two strokes (5.6%) and two transient ischemia attacks (5.6%). Microemboli for each of these cases totalled 133, 17, 29 and 47 (with one shower), respectively. One postoperative carotid endarterectomy patient was noted to have a stroke (1.4%), with 48 microemboli noted during that procedure. The mean emboli rate for percutaneous angioplasty with stenting patients with neurological events was 59.0: without complications it was 85.1. The mean emboli rate for carotid endarterectomy patients without complications was 8.3. Three percutaneous angioplasty with stenting patients had no emboli (7.5%), whereas 29 carotid endarterectomy patients had no emboli (38.7%). CONCLUSION: The percutaneous angioplasty with stenting procedure is associated with more than eight times the rate of microemboli seen during carotid endarterectomy when evaluated with transcranial Doppler monitoring. Larger patient groups are needed to determine if this greater embolization rate has an associated risk of higher morbidity or mortality.

Degradation of weathered oil by mixed marine bacteria and the toxicity of accumulated water-soluble material to two marine crustacea.

Artificially weathered crude oil was degraded by four diverse cultures of mixed marine bacteria under optimized conditions for 7 and 14 days. Loss in total weight of starting oil (30 g) ranged from 6.8-17.3% in biologically active incubations compared with only 0. 9-1.1% in sterile and nutrient-limited controls. In all incubations, both neutral and acidic water-soluble fractions (WSF) were accumulated. In biologically active systems, 50.9-249.0 mg neutral and 63.3-406.8 mg acidic WSF were accumulated whereas only 6.5-11.1 mg neutral and 1.7-2.2 mg acidic WSF were accumulated in control incubations. Analysis by gas chromatography demonstrated that accumulated WSF in biologically active systems contained compounds different from those washed from the starting crude oil. Exposure of grass shrimp (Palaemonetes pugio) embryos to neutral WSF from each of the biologically active cultures resulted in high embryo mortalities relative to sterile and nutrient-limited controls which exhibited >90% hatching success and larval survival. Toxicity of neutral WSF was also demonstrated on larvae of mysids (Mysidopsis bahia). In both cases, toxicity occurred only on exposure to neutral material accumulated by active, oil-degrading cultures and not with material washed from the weathered crude oil. These results imply that unique compounds were accumulated during degradation that may have been responsible for increased toxicity.

Carotid angioplasty.

BACKGROUND: Carotid angioplasty with stenting (PTAS) is now being investigated as an alternative to carotid endarterectomy (CEA). Proven superiority in at least three areas of PTAS will need be accomplished before angioplasty supplants CEA; namely, safety, cost, and durability. METHODS: One hundred and seven patients served as the basis for this previously reported review. Both safety (morbidity and mortality) as well as cost issues were evaluated. Other non-neurologic complications were are also investigated. RESULTS: The in-hospital and 30-day risk of all strokes and death from PTAS was 9.3%, with a 3.6% major stroke and death rate. Minor strokes were found to be statistically more frequent in the PTAS group than with CEA. Nonprofessional fees were more expensive in the PTAS group than CEA ($30,140 versus $21,670). CONCLUSIONS: At the present time PTAS has not proven itself worthy to supplant CEA. The durability of the procedure has not been sufficiently evaluated. Non-neurologic complications are also not trivial with PTAS.

Perkinsus marinus tissue distribution and seasonal variation in oysters Crassostrea virginica from Florida, Virginia and New York.

Perkinsus marinus infection intensity was measured in eastern oysters Crassostrea virginica collected in October and December 1993, and March, May, and July 1994 from 3 U.S. sites: Apalachicola Bay (FL), Chesapeake Bay (VA), and Oyster Bay (NY). Gill, mantle, digestive gland, adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. Samples were separately diagnosed for P. marinus infections by incubation in Ray's Fluid Thioglycollate Medium (RFTM) and subsequent microscopic quantification of purified enlarged hypnospores. At all sampling times and sites, average P. marinus infection intensity (g wet wt tissue-1 or ml hemolymph-1) was lowest in hemolymph samples, and generally highest in the digestive gland. Perkinsus marinus prevalence was 100% at both FL and NY sites for each of the 5 collection times, and, for the VA site, was less than 100% in only 1 month (May 1994). Seasonal intensity patterns and mean total body burdens differed among the sites. Average body burden was highest in VA during October and progressively declined to a minimum in May. This decline was probably due to mortality of heavily infected oysters and diminution of parasite activity associated with colder temperatures and reduced salinities. Intensities varied little during the months of October and December at both the FL and NY sites. Minimum average intensities were observed in March in FL oysters and May in NY oysters. Relatively high P. marinus infection levels that persisted throughout the winter in NY oysters compared with VA oysters could reflect constant high salinity in Long Island Sound which favors parasite activity, and also rapid decline in temperature in the fall that may have prevented epizootic oyster mortalities.

A comparison of carotid angioplasty with stenting versus endarterectomy with regional anesthesia.

INTRODUCTION: Percutaneous transluminal angioplasty with stenting (PTAS) has been considered a potential alternative to carotid endarterectomy (CEA) for stroke prevention. Interventionalists have suggested that PTAS carries less anesthetic risk than CEA. The treatment of carotid stenosis with local or regional anesthesia (LRA) allows direct intraprocedural neurologic evaluation and avoids the potential risks of general anesthesia. METHODS: We retrospectively analyzed the clinical charts of 377 patients who underwent 414 procedures for the elective treatment of carotid stenosis in 433 cerebral hemispheres with LRA between August 1994 and May 1997. Group I (312 hemispheres) underwent PTAS, and group II (121 hemispheres) underwent CEA. RESULTS: The indications for treatment included the following: asymptomatic severe stenosis (n = 272; 62.8%), transient ischemic attack (TIA; n = 100; 23.1%), and prior stroke (n = 61; 14.1%). The early neurologic results for the patients in group I (n = 268) included 11 TIAs (4.1%), 23 strokes (8.6%), and 3 deaths (1.1%). The early neurologic results for the patients in group II (n = 109) included 2 TIAs (1.8%), one stroke (0.9%), and no deaths. The total stroke and death rates were 9.7% for the patients in group I and 0.9% for the patients in group II (P = .0015). The cardiopulmonary events that led to additional monitoring were evident after 96 procedures in group I (32.8%) and 21 procedures in group II (17.4%; P = .002). CONCLUSION: PTAS carries a higher neurologic risk and requires more monitoring than CEA in the treatment of patients with carotid artery stenosis with LRA. The proposed benefit for the use of PTAS to avoid general anesthesia cannot be justified when compared with CEA performed with LRA.

Cerebrospinal fluid fistula: detection with MR cisternography.

PURPOSE: Our goal was to assess the role of MR cisternography in the examination of patients with suspected CSF rhinorrhea. METHODS: MR cisternography was performed as a heavily T2-weighted fast spin-echo study with fat suppression and video reversal of the images in 37 patients over a 3-year interval. Twenty-four of the patients subsequently had exploratory surgery for fistula. Statistical analysis of the surgical results was compared with the findings at MR cisternography. RESULTS: MR cisternography showed significant correlation with surgical findings, with sensitivity, specificity, and accuracy of 0.87, 0.57, and 0.78, respectively. CONCLUSION: MR cisternography proved to be an accurate diagnostic imaging technique in the evaluation of suspected CSF rhinorrhea.

A cost comparison of balloon angioplasty and stenting versus endarterectomy for the treatment of carotid artery stenosis.

PURPOSE: Percutaneous transluminal angioplasty with stenting (PTAS) of the carotid artery has been advocated as an alternative treatment for high-grade stenosis. Rationale for this approach includes less morbidity, shorter recovery, and lower cost when compared with carotid endarterectomy (CEA). METHODS: The clinical results and hospital charges of patients who underwent elective treatment for carotid stenosis were reviewed. During a concurrent 14-month period, 218 patients were admitted 229 times for 234 procedures for the treatment of 239 carotid bifurcation stenoses, 109 by PTAS and 130 by CEA. Hospital charges were reviewed for each hospitalization and were categorized according to radiology, operating room, cardiac catheterization laboratory, and all other hospital charges. RESULTS: The combined incidence of postprocedure strokes and deaths were: PTAS, eight strokes (7.7%) and one death (0.9%); CEA, two strokes (1.5%) and two deaths (1.5%). Total hospital charges per admission for the two groups were $30,140 for PTAS and $21,670 for CEA. The average postprocedure length of stay for PTAS was 2.9 days (median, 2 days) and for CEA was 3.1 days (median, 3 days). Cardiac catheterization laboratory charges for the PTAS group were $12,968, whereas the operating room charges for the CEA group were $4263. When hospitalizations that were extended by complications were excluded, the average total charges for the PTAS group (n = 84) dropped to $24,848 (mean length of stay, 1.9 days) and for the CEA group (n = 111) to $19,247 (mean length of stay, 2.6 days). CONCLUSIONS: After evaluating hospital charges, PTAS for the treatment of carotid stenosis cannot currently be justified on the basis of reduced costs alone. With future cost-containing measures, total hospital charges can be reduced in both groups.

Angiography after aneurysm surgery: indications for "selective" angiography.

BACKGROUND: The need for postoperative cerebral angiography to confirm clip placement is largely a matter of the individual surgeon's preference, but in an atmosphere of limited health care resources and rising costs this attitude may need to be changed. METHODS: A series of 312 intracerebral aneurysms harbored in 227 consecutive patients were clipped by a single surgeon (WF) and studied with postoperative selective angiography. Clues were sought to identify which (if any) aneurysms were prone to require postoperative recognition of incomplete or inaccurate clipping. We examined aneurysmal size, patient's sex, age, preoperative Hunt/Hess Grade, and Fisher CT grade, to determine their relationship to poor surgical clipping results (residual aneurysm or major vessel occlusion). RESULTS: There were 13 cases of residual aneurysm (4.2%) and one case of major vessel occlusion (0.3%). Deep midline aneurysms (posterior circulation, anterior communicating artery) and ophthalmic (paraophthalmic) artery regions formed a group of patients with an increased risk of imperfect clip placement (8.2%; 13/157) as compared to patients with aneurysms in other locations (0.6%; 1/155) (p < 0.05). In addition, incompletely obliterated aneurysms proved to have a high rehemorrhage rate in this series. CONCLUSIONS: A retrospective analysis revealed that deep midline aneurysms are more prone to inadequate clipping, and therefore, as a bare minimum represent aneurysms requiring confirmatory postoperative evaluation. This contemporary series can be used as a basis to compare the results from intraoperative angiography.

Carotid endarterectomy performed after progressive carotid stenosis following angioplasty and stent placement. Case report.

Carotid endarterectomy (CEA) is the treatment of choice for asymptomatic and symptomatic disease causing greater than 60% internal carotid artery (ICA) stenosis. Recently, percutaneous transluminal angioplasty (PTA) with stent placement has been investigated as a therapeutic option for the treatment of ICA stenosis. In this report the authors document CEA performed after PTA with stent placement and describe the pathological findings. A standard CEA was performed. The surgical intervention was more difficult secondary to the following variables: the length of the exposure necessary to dissect out the metallic stent, the difficulty with opening and cutting the artery, and the care required to remove the stent to avoid vessel wall perforation. Pathological examination of the specimen demonstrated classic atherosclerotic changes revealing persistence of native disease. The metallic stent was embedded within the plaque. Many questions remain unanswered regarding the physiological and biological changes that occur in the carotid vessel wall after PTA with stent placement. It is concluded that CEA of a stent-containing carotid artery is feasible and should be considered as an alternative when recurrent stenosis occurs after PTA.

Screening for ocular hemorrhages in patients with ruptured cerebral aneurysms: a prospective study of 99 patients.

BACKGROUND: Terson's syndrome (vitreous hemorrhage) and other ocular hemorrhages (retinal hemorrhages) have been reported to occur in up to 40% of patients with ruptured cerebral aneurysms. Because microsurgical vitrectomy can safely restore vision in patients with visual loss secondary to Terson's syndrome, we hypothesized that prospectively screening a selected group of patients with aneurysms would result in a higher rate of vitrectomy in patients with more extensive subarachnoid hemorrhage. METHODS: Ninety-nine patients with ruptured cerebral aneurysms were prospectively screened for Terson's syndrome and other forms of ocular hemorrhage by an ophthalmologist. Follow-up data were obtained for seven of eight cases of Terson's syndrome, and vitrectomy was performed for visual restoration when indicated. RESULTS: Ocular hemorrhages were present in 17% of patients with ruptured cerebral aneurysms, and Terson's syndrome was present in 8% of patients. Screening of patients with histories of transient or prolonged comas sensitively identified patients with ocular hemorrhages in 100% of the patients with Terson's syndrome and 89% of the patients with other ocular hemorrhages. Fifty-five percent of the patients in the overall series had histories of transient or prolonged comas, and 53% (specificity) of those patients had ocular hemorrhages. Two of the eight patients with Terson's syndrome underwent vitrectomy, with dramatic improvement in vision. No other ocular hemorrhages required surgery. CONCLUSIONS: Ophthalmological screening of patients with histories of transient or prolonged comas after ruptured cerebral aneurysms very sensitively identifies patients with ocular hemorrhages, which are relatively common in patients with subarachnoid hemorrhage treated in an academic neurosurgical practice. The present study underestimates the true incidence of Terson's syndrome in that patients who died shortly after their subarachnoid hemorrhage were not included. Vitrectomy for patients who do not exhibit spontaneous improvement in vision results in a dramatic reversal of blindness.

Developmental toxicity of three carrier solvents using embryos of the grass shrimp, Palaemonetes pugio.

Embryos of the grass shrimp (Palaemonetes pugio) have shown sensitivity to the water soluble fraction of number 2 fuel oil. To determine the possible use of carrier solvents in grass shrimp bioassays, detailed concentration-response experiments for ethanol (EtOH), dimethylsulfoxide (DMSO), and acetone were performed and LC50 values were obtained using two test methods. The 4-d assay included development prior to the time of hatch through the time of hatch, a critical life stage of these embryos. The 12-d assay included development from the tissue cap stage embryos (late gastrula) through two days post-hatch. The average 4-d LC50s for EtOH, DMSO, and acetone were 12.07, 22.57, and 6.78 g/L, whereas the average 12-d LC50s were 3.63, 12.33, and 6.94 g/L, respectively. The coefficient of variation for each test was less than 25.2%. Based on concentration-response curves, the maximum allowable limit of EtOH, DMSO, and acetone to be used as a carrier in the grass shrimp embryo toxicity studies should be <1, <6, and <4 g/L, respectively.