Effect of temperature on heavy metal toxicity to juvenile crayfish, Orconectes immunis (Hagen).

The acute toxicity of four selected heavy metals to juvenile crayfish Orconectes immunis (Hagen) (1-2 g wet body wt. each) at room temperature increased in the following order: cadmium (x3) < copper (x10) < zinc (x2) < lead. The toxicity of these metals to crayfish acclimated at 17, 20, 23/24, and 27 degrees C increased with temperature (by 7-20% between 20 and 24 degrees C and 14-26% between 20 and 27 degrees C) as judged by the lowering of LT(50) (time to kill 50% of test animals at a fixed concentration) values. A 4 degrees C rise in temperature (from 20 to 24 degrees C), which increased the toxicity of copper by about 7%, increased the rate of oxygen consumption by about 34%. Heavy metals inhibited the rate of oxygen consumption at all temperatures. In 20 degrees C-acclimated crayfish, copper caused about 17% inhibition of oxygen consumption compared to about 7-12% by other metals including the most toxic cadmium. A 3-4 degrees C rise in temperature tripled the inhibitory effect of copper (20%), cadmium and zinc (26 and 18%, respectively), but not of lead, on oxygen consumption. A 7 degrees C-rise in temperature (from 20 to 27 degrees C) increased the inhibitory effect of heavy metals, including lead, on oxygen consumption by up to 54% in the case of copper. The data indicate that rising global temperatures (currently 0.60 degrees C) associated with climate change can have the potential to increase the sensitivity of aquatic animals to heavy metals in their environment.

Biodegradation of sediment-bound PAHs in field-contaminated sediment.

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) has been reported to occur under aerobic, sulfate reducing, and denitrifying conditions. PAHs present in contaminated sites, however, are known for their persistence. Most published studies were conducted in systems where PAHs were freshly spiked, and biodegradation was often tested using pure cultures or enrichments. This paper investigated the degradation potentials of PAHs that were present in aged contaminated sediment by indigenous bacteria, where the limited bioavailability of PAHs due to aging played an important role. The sediment and the overlaying water were collected from a contaminated site to prepare sediment-water slurries, and the sediment served as both the media containing PAH substrates and the habitat for the indigenous microorganisms. Reduced sulfur compounds present in the sediment caused rapid oxygen depletion due to extensive activities of sulfur-oxidizing bacteria and could result in a dramatic pH drop. Once oxygen depletion and acidification problems were avoided, substantial removals of two-, three-, four-, and five-ring PAHs were achieved aerobically, though the extent of degradations was smaller than what was reported for freshly spiked PAHs. The amendment of inorganic N and P, co-substrates, or surfactant Triton X-100 did not enhance the level of degradations appreciably. Under denitrifying conditions, no distinct PAH degradation was observed, while the complete denitrification of nitrate to nitrogen occurred stoichiometrically with a concomitant increase in sulfate concentration, indicating the dominance of autotrophic denitrifiers. The addition of ethanol or acetic acid did not stimulate PAH degradation. Substantial PAH degradation attributed to sulfate reduction was only observed for phenanthrene, the low-ring PAH existing in a highest initial concentration. Addition of ethanol or acetic acid did not change this finding. This is the first study to our knowledge that revealed the importance of indigenous bacteria involved in natural sulfur cycling in determining degradation behavior of PAHs.

Effectiveness of an anaerobic granular activated carbon fluidized-bed bioreactor to treat soil wash fluids: a proposed strategy for remediating PCP/PAH contaminated soils.

An integrated system has been developed to remediate soils contaminated with pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAHs). This system involves the coupling of two treatment technologies, soil-solvent washing and anaerobic biotreatment of the extract. Specifically, this study evaluated the effectiveness of a granular activated carbon (GAC) fluidized-bed reactor to treat a synthetic-waste stream of PCP and four PAHs (naphthalene, acenaphthene, pyrene, and benzo(b)fluoranthene) under anaerobic conditions. This waste stream was intended to simulate the wash fluids from a soil washing process treating soils from a wood-preserving site. The reactor achieved a removal efficiency of greater than 99.8% for PCP with conversion to its dechlorination intermediates averaging 46.5%. Effluent, carbon extraction, and isotherm data also indicate that naphthalene and acenaphthene were removed from the liquid phase with efficiencies of 86 and 93%, respectively. Effluent levels of pyrene and benzo(b)fluoranthene were extremely low due to the high-adsorptive capacity of GAC for these compounds. Experimental evidence does not suggest that the latter two compounds were biochemically transformed within the reactor.

Removal of PAHs from highly contaminated soils found at prior manufactured gas operations.

Removal of PAHs from highly contaminated soil found at a manufactured gas site was evaluated using solvent washing with mixed solvents. The following solvents were considered as water miscible co-solvents in mixed solvents: ethanol, 2-propanol, acetone, and 1-pentanol. In batch solvent extraction of soil, ethanol and 2-propanol were selected as primary components of mixed solvents in addition to 1-pentanol. Using ternary solutions containing either ethanol or 2-propanol with a volume fraction of 1-pentanol ranging from 5 to 25% and a water volume fraction ranging from 5 to 30%, ethanol was more effective than 2-propanol in extracting PAHs from soil. A solvent mixture of 5% 1-pentanol, 10% water and 85% ethanol was selected as the extraction solvent. Using a 1g:4ml soil:solvent extraction ratio, extraction kinetics showed that from 65 to 90% of the extractable PAHs were removed within an hour of contact between soil and solvent. Using this 1g:4ml extraction ratio, PAHs were removed in a three-stage cross-current solvent washing process where the same batch of soil was extracted with clean solvent for 1h in each stage. PAH removals in three-stage cross-current solvent washing were comparable to PAH removals obtained with Soxhlet extraction.

Differentiation of hepatic cavernous hemangioma from metastases by rare sequence MR imaging.

In this study, in order to differentiate cavernous hemangioma and hepatic metastases, rapid acquisition relaxation enhanced (RARE) sequence was used. First, in vivo measurements of T1, T2 relaxation times and proton density were obtained using T1, T2 calculation protocol (TOMIKON S50, 0.5T) and multipoint techniques. These measurements were made from regions of interest placed over the liver, spleen (because of similarity of relaxation time values between hepatic metastases and spleen) and cavernous hemangioma (HCH). Based on these intrinsic parameters, T2 curves signal intensity of three different tissues were constructed. At TE = 500 ms, the signal intensity of the liver and spleen has been near zero whereas in HCH, the signal intensity remained. As RARE sequence is very similar to spin echo (SE), by replacing effective TE(ETE) = 500 ms in the RARE equation, two dimensional contrast-to-noise ratio (CNR) contour plots were constructed demonstrating signal intensity contrast between liver-spleen, liver-Hemangioma for two different scan times (3 min, 7.5 s) and pulse timing. Then, optimal RARE factor and inter echo times were obtained in order to have maximum CNR between liver-Hemangioma and minimum CNR between liver-spleen. These optimal parameters were performed on ten normal and five persons with known HCH. Images showed that in both scan times (3 min, 7.5 s); the liver and spleen were suppressed whereas the HCH was enhanced. The image quality in the scan time of 3 min was better than the scan time of 7.5 s. Moreover, in this study, two different sequences were compared: i) Multi-slice single echo (MSSE) for T1 weighted image ii) RARE (ETE = 80 ms) for T2-weighted image. This comparison was done to show maximum CNR between liver-spleen (metastases) and to choose a better sequence for detecting metastases. CNR in the RARE sequence was more than in the MSSE sequence.

Hemangiopericytoma of the ciliary body.

A 60-year-old woman had a ciliary body tumor that resembled an amelanotic malignant melanoma by clinical examination. The magnetic resonance imaging scan correlated with the clinical diagnosis. Because of apparent rapid growth, her eye was enucleated. However, histopathologic examination revealed a highly vascularized, spindle-cell tumor harboring immunoreactive actin and vimentin. Electron microscopy further supported the diagnosis of hemangiopericytoma with smooth-muscle differentiation. To our knowledge, this is the first report of a hemangiopericytoma of the ciliary body.

Pars planitis and autoimmune endotheliopathy.

A migrating endothelial rejection line is the clinical criterion of specific immune reaction in corneal allotransplantation. This line when seen in otherwise intact corneas has been presumed to be an autoimmune endotheliopathy. We have recorded corneal changes similar to autoimmune endotheliopathy in four of ten patients with the diagnosis of pars planitis. These observations suggest that pars planitis may be an autoimmune process directed against the vitreous humor.

Corneal endothelium in penetrating keratoplasty.

Specular microscopy of endothelium after corneal transplantation has often shown a sharp reduction in its number density immediately after surgery and long-term cell loss during the next three to four years in addition to continuous morphologic changes. We examined flat preparations of the endothelium of three corneal buttons removed three weeks, eight weeks, and 11 months after penetrating keratoplasty and compared them to similar preparations from the corneal rims of the respective donors. We did not find significant morphologic changes, and direct endothelial cell counts disclosed an endothelial cell loss of 3.8% at three weeks, 2.6% at eight weeks, and 5.6% at 11 months after keratoplasty. We believe the lack of endothelial cell loss and absence of morphologic changes in these specimens are direct results of our surgical technique.

In vitro enhancement of anterior chamber GVH reactions.

The injection of sensitized allogeneic lymphocytes into the anterior chamber of the rabbit eye results in a local graft-verus-host reaction, with focal destruction of the corneal endothelium. This experimental model permits in vitro manipulation of effector cells, and the study of the mechanisms involved in corneal graft rejection. The authors now show that the in vitro activation of sensitized lymphocytes is a one-way mixed lymphocyte reaction yields "supersensitized" effector cells which are quantitatively enriched and qualitatively altered to yield more severe and more rapid endothelial target cell destruction.

Diurnal variation in corneal endothelial morphology.

Transient changes in the corneal endothelium were the earliest detectable response to low atmospheric oxygen in experimental animals. Similar changes have been reported after hard and soft contact lens wear. We describe widespread transient cell changes by wide-field specular microscopy in the normal corneal endothelium after 12 hours of a light eye patch. The relative anoxia of lid closure during normal sleep appears to be the cause of observable changes. This observation questions the safety of extended wear contact lens over a prolonged period of time, and its significance to age-related endothelial cell density reduction and cornea guttata remains to be seen.

Specular microscopy of hard contact lens wearers.

Wide-field specular microscopy, slit-lamp examination, and pachometry were performed on 22 successful hard contact lens wearers and 22 controls matched for age, race, sex, and refractive error. A minimum of 600 cells per control and 1200 per contact lens wearer were manually digitized from the specular photomicrographs. Frequency distributions of cell areas were compared between the two groups using the parameters of mean, median, standard deviation, coefficient of variation, skewness and kurtosis. Slit-lamp examination was normal and there was no significant difference in corneal thickness between the patient group and the control group. Comparison of mean, median, and standard deviation also revealed no significant difference, but skewness (P less than .001), kurtosis (P less than .001) and coefficient of variation (P less than .004) were greater in the hard contact lens wear group. Hard contact lens wearing time correlated with increasing pleomorphism (P less than .05). Specular microscopy also revealed morphologic changes including deep stromal striae, intra- and extracellular "blackout" areas, and clustering of extremely small and large cells. The possible relationship between endothelial hypoxia and structural stromal changes are discussed.

Ocular effect of neodymium-YAG laser.

We aimed a high-powered pulsed neodymium-YAG laser incrementally from air to the anterior portion of the vitreous in rabbits to evaluate its effect on the corneal endothelium, the lens, and the dynamics of intraocular fluid. Corneal endothelium damage occurred as much as 3.5 mm away from the site of optical breakdown. The degree of tissue damage was inversely proportional to the distance from the site of optical breakdown, and the damage pattern at a given distance was the same whether the optical breakdown was anterior or posterior to the corneal endothelium. A single 4-mJ shot (mode-locked train) of laser light causes disintegration and liquefaction of the lens in a spherical area 300 micron in diameter. The damage extends posteriorly to a distance of 450 micron. The effect of this explosion denatures the surrounding cortical fibers for an area of 50 to 80 micron. Increased intraocular pressure was noted in all instances of anterior or posterior capsulotomy, probably as a result of the release of liquefied cortical material and mechanical obstruction of the chamber angle. No increase in intraocular pressure occurred when the lens capsule remained intact.

Corneal grafts in the second eye.

A series of 51 patients with bilateral penetrating corneal grafts was followed for 1-12 years to assess the effect of the second eye corneal graft on the incidence of allograft rejection. In 33 patients (66 eyes) who had avascular grafts, there was no significant increase in the incidence of allograft rejection reaction after corneal transplantation in the second eye. In 18 patients (36 eyes) who had vascularized corneas, there was a twofold increase in the incidence of allograft rejection in the second as well as in the first corneal graft. Based on this observation and other reports cited in the literature, we offer contraindications for grafting of the second eye.

Coagulation properties of intraocular humors and cerebrospinal fluid.

Clinical observations indicated a prompt cessation of episcleral capillary bleeding after exposure of those tissues to aqueous humor during intraocular surgery. Based on this observation, both aqueous and vitreous humors were obtained from eyes provided by an eye bank and from human eyes prior to intraocular surgery. Samples of cerebrospinal fluid also were obtained from two patients, one with optic atrophy and another with nutritional amblyopia. A total of 49 specimens were studied. Aqueous humor shortened the average ear lobe puncture bleeding time from 4.74 +/- 0.2 to 1.13 +/- 0.1 minutes. Varying dilutions of aqueous humor, up to a dilution of 1:16, shortened prothrombin and partial thromboplastin times when compared with normal control plasma without aqueous. Vitreous humor shortened partial thromboplastin time but had no effect on prothrombin time. The effect of cerebrospinal fluid on prothrombin and partial thromboplastin times was similar to the aqueous, but to a lesser degree.

Presumed autoimmune corneal endotheliopathy.

Two men (58 and 19 years of age) had an unusual recurrent, bilaterally symmetric disease process involving the cornea. It is characterized by stromal edema progressing centrally from the periphery in otherwise normal eyes. The corneal edema in each instance was closely associated with slowly moving linear keratic precipitates accompanied by the destruction of the endothelium, with minimal anterior chamber reaction. There was no history of herpetic keratitis or trauma, and serologic tests for syphilis were negative in both cases. A similar pattern of linear endothelial destruction has been reported heretofore only in association with corneal allograft rejection. This clinical pattern, the cytologic findings for the aqueous humor (macrophages and lymphocytes), and the rapid response to corticosteroid therapy suggested that an autoimmune process was the underlying cause of this disease.

Desquamation of corneal endothelial cells.

The process of wound healing of rabbit corneal endothelium involves the desquamation of significant numbers of endothelial cells, which may be found floating freely in the aqueous. It is suggested that this may be a general phenomenon of corneal endothelial wound healing, which accompanies the release of endothelial-cell attachments to Descemet's membrane and to neighboring cells during mitosis, allowing some of the cells to "fall of" into the anterior chamber. The possibility is discussed that such endothelial desquamation may contribute to had sensitization to he histocompatibility antigens of penetrating corneal grafts.

Advantage of underweight.

Exposure measurements made during a diagnostic radiological study revealed that heavy set patients pay a higher price in absorbed dose than lighter people.

Cytogenetic effects of contrast material in patients undergoing excretory urography.

Acentric chromosome fragments produced in cells by irradiation or other agents give rise to micronuclei in daughter cells. The micronuclei can be counted readily in large numbers of cells which provides a sensitive measure of chromosome aberrations. Previous studies have shown that the presence of contrast material enhances the radiation-induced yield of micronuclei in vitro. This may be due to the dose enhancement effect and the chemical action of contrast media or their derivatives. Micronuclei were scored in peripheral blood lymphocytes obtained from 26 patients before and after excretory urography (ExU). The results show a consistent and significant increase in the counts after ExU amounting to about one third of the counts blood samples before the examination. We have also measured radiation exposures in this group and estimated an average exposure to the circulating lymphocytes of about 0.2R (0.52 X 10(-4) C/kg). We conclude that the contrast medium contributed significantly to the increase in micronuclei.

Transfer of bacterial infections by donor cornea in penetrating keratoplasty.

A 45-year-old man died of Hogdkin's disease complicated by peritonitis and possible septicemia. His corneas were used for transplant in a 26-year-old man with advanced keratoconus and a 42-year-old man with vascularized central leukoma of old herpetic keratitis. Both recipients developed a fulminating endophthalmitis with Pseudomonas aeruginosa. We believe that the donor corneas, although clinically normal, were heavily infected, with signs of inflammation possibly suppressed by the Hodgkin's disease.