Determination of serum and urinary aluminum by HPLC with fluorometric detection of Al-lumogallion complex

We describe a simple and sensitive HPLC method for quantifying aluminum (Al) in biological fluids by measuring the fluorescence of the Al-lumogallion complex (excitation wavelength 500 nm, emission wavelength 575 nm). Serum samples are deproteinized with 0.83 mol/L perchloric acid and centrifuged; the supernates are mixed with lumogallion reagent. Urine samples are pretreated with sodium hydroxide (2 mol/L) and methanol, kept for 1 h at -20 degrees C, and then centrifuged; the precipitate is resuspended in perchloric acid and mixed with lumogallion reagent, as for serum. The maximal fluorescence complex is formed after 1 h at pH 5 +/- 0.5. The HPLC mobile phase consists of (per liter) 100 mL, of 0.2 mol/L potassium hydrogen phthalate, 220 mL of acetonitrile, and distilled deionized water. The flow rate is 1 mL/min, and the injection volume is 5 microliters. The major aluminum species is eluted at 3.5 min, the lowest detection limit being 0.45 pg. We validated the method with samples collected from normal subjects and from workers occupationally exposed to aluminum. Comparing the results with those by traditional atomic absorption spectrometry of urinary aluminum suggests that the proposed method is reliable.

Determination of serum and urinary aluminum by HPLC with fluorometric detection of Al-lumogallion complex

We describe a simple and sensitive HPLC method for quantifying aluminum (Al) in biological fluids by measuring the fluorescence of the Al-lumogallion complex (excitation wavelength 500 nm, emission wavelength 575 nm). Serum samples are deproteinized with 0.83 mol/L perchloric acid and centrifuged; the supernates are mixed with lumogallion reagent. Urine samples are pretreated with sodium hydroxide (2 mol/L) and methanol, kept for 1 h at -20 degrees C, and then centrifuged; the precipitate is resuspended in perchloric acid and mixed with lumogallion reagent, as for serum. The maximal fluorescence complex is formed after 1 h at pH 5 +/- 0.5. The HPLC mobile phase consists of (per liter) 100 mL, of 0.2 mol/L potassium hydrogen phthalate, 220 mL of acetonitrile, and distilled deionized water. The flow rate is 1 mL/min, and the injection volume is 5 microliters. The major aluminum species is eluted at 3.5 min, the lowest detection limit being 0.45 pg. We validated the method with samples collected from normal subjects and from workers occupationally exposed to aluminum. Comparing the results with those by traditional atomic absorption spectrometry of urinary aluminum suggests that the proposed method is reliable.

Ocular nail gun injuries

PURPOSE

Penetrating ocular trauma resulting from nails can have disastrous visual consequences. Ocular nail gun injuries occur when a nail propelled at high velocity penetrates the globe. The authors report four consecutive patients with ocular injuries resulting from nail guns.

METHODS

Four patients with ocular nail gun injuries are described: one with scleral penetrating injury, one with corneal penetrating injury, and two with perforating (through- and-through) injuries of the globe.

RESULTS

Three of the four patients recovered good visual acuity after surgical intervention.

CONCLUSION

Although dependent on the site of impact, the visual prognosis may be less severe than expected because the nail penetrates the eye at a high velocity such that there are less contusive forces. Adherence to safety precautions involving the use of nail guns as well as the obligatory use of safety glasses should reduce the incidence of these injuries.

Posterior segment neovascularization associated with optic nerve aplasia

PURPOSE

To report the presence of posterior segment neovascularization in eyes with optic nerve aplasia.

METHODS

Three eyes in two patients with clinical optic nerve aplasia were studied.

RESULTS

Examination disclosed posterior segment neovascularization in one eye and progressive posterior segment neovascularization in two eyes.

CONCLUSIONS

Posterior segment neovascularization may occur in association with optic nerve aplasia. Retinal ischemia or retinochoroidal anatomic disorganization, or both, may provide the stimulus for neovascularization in such eyes.

Biomarkers of exposure to low concentrations of benzene: a field assessment

OBJECTIVE

To carry out a comprehensive field investigation to evaluate various conventional and recently developed biomarkers for exposure to low concentrations of benzene.

METHODS

Analyses were carried out on environmental air, unmetabolised benzene in blood and urine, urinary trans, transmuconic acid, and three major phenolic metabolites of benzene: phenol, catechol, and hydroquinone. Validations of these biomarkers were performed on 131 never smokers occupationally exposed to the time weighed average benzene concentration of 0.25 ppm (range, 0.01 to 3.5 ppm).

RESULTS

Among the six biomarkers studied, unmetabolised benzene in urine correlated best with environmental benzene concentration (correlation coefficient, r = 0.76), followed by benzene in blood (r = 0.64). When urinary metabolites were compared with environmental benzene, trans, trans-muconic acid showed a close correlation (r = 0.53) followed by hydroquinone (r = 0.44), and to a lesser extent with urinary phenol (r = 0.38). No correlation was found between catechol and environmental benzene concentrations. Although unmetabolised benzene in urine correlates best with benzene exposure, owing to serious technical drawbacks, its use is limited. Among the metabolites, trans, trans-muconic acid seems to be more reliable than other phenolic compounds. Nevertheless, detailed analyses failed to show that it is specific for monitoring benzene exposures below 0.25 ppm.

CONCLUSION

The overall results suggest that most of the currently available biomarkers are unable to provide sufficient specificity for monitoring of low concentrations of benzene exposure. If a lower occupational exposure limit for benzene is to be considered, the reliability of the biomarker and the technical limitations of measurements have to be carefully validated.

Zidovudine, trimethoprim, and dapsone pharmacokinetic interactions in patients with human immunodeficiency virus infection

Zidovudine is widely prescribed for the treatment of human immunodeficiency virus (HIV) infection. Trimethoprim and dapsone are commonly used in the management of Pneumocystis carinii pneumonia in HIV-infected patients. To examine the pharmacokinetic interactions among these drugs, eight HIV-infected patients (26 to 43 years old) with a mean CD4 count of 524.4 +/- 405.7 cells per mm3 received zidovudine (200 mg), trimethoprim (200 mg), and dapsone (100 mg) as single agents and in two- and three-drug combinations. Blood and urine samples were collected at a specified time and analyzed for zidovudine, zidovudine-glucuronide, trimethoprim, dapsone, and monoacetyl-dapsone concentrations under single-dose and steady-state conditions. Zidovudine did not influence the pharmacokinetic disposition of dapsone or trimethoprim. Dapsone had no effect on the pharmacokinetic disposition of zidovudine. Trimethoprim significantly decreased the renal clearance of zidovudine by 58% (5.0 +/- 1.8 versus 2.1 +/- 0.5 ml/min/kg of body weight [P < 0.05]). There was a concurrent 54% decrease in the mean urinary recovery of zidovudine (11.7 +/- 3.5 versus 5.4 +/- 3.0 [P < 0.05]), and the metabolic ratio was decreased by 78% (0.32 +/- 0.4 versus 0.07 +/- 0.05 [P < 0.05]). The mean area under the concentration-time curve from 0 to 6 h of the zidovudine-glucuronide/ zidovudine ratio was unchanged. We conclude that zidovudine, trimethoprim, and dapsone can be coadministered to patients with AIDS without significant pharmacokinetic interaction. However, in AIDS patients with liver impairment and impaired glucuronidation, doses of zidovudine may need to be decreased.

Urinary homovanillic acid and vanillylmandelic acid in workers exposed to carbon disulfide

Homovanillic acid (HVA) and vanillylmandelic acid (VMA), two end products of dopamine metabolism, were measured in 60 workers exposed to carbon disulfide (CS(2)) in a rayon factory and in 48 unexposed workers. The airborne CS(2) concentrations in eight major exposure zones of the plant were measured monthly over a period of 4 years, from 1990 to 1994. In addition, the exposure concentrations and exposure history of each worker were integrated to estimate the overall lifetime exposure. Industrial hygiene data showed that the geometric mean concentrations of CS(2) in the plant ranged from 2.68 to 20.19 ppm, and more than 15% of the studied population had been repeatedly exposed to CS(2) at concentrations exceeding the ACGIH recommended time-weighted average of 10 ppm. The results showed that there was a significantly lower level and a higher proportion of CS(2) workers with decreased HVA and VMA excretion. However, there were no statistical correlations between the two dopaminergic metabolites and the mean CS(2) concentration, and years of employment. In contrast, significant dose-effect relationships were observed between these two metabolites and the integrated cumulative exposure (ICE) variable. The correlation coefficients for ICE and HVA, and ICE and VMA were -0.35 (p < 0.01) and -0.20 (p <0.05), respectively. These data suggest that chronic exposure to CS(2) was associated with measurable reduction in catecholamine metabolite concentrations. This finding is compatible with the earlier observations in laboratory animals that CS(2) exposures interfere with neurochemical metabolism.

Structure and expression of the tenecin 3 gene in Tenebrio molitor

A genomic DNA fragment encoding tenecin 3, an antifungal protein was cloned from the genomic DNA library of Tenebrio molitor. The DNA sequence analysis showed that the coding region is divided into two exons by an intron of 49 bp in the middle of the putative leader peptide coding region. Southern blot analysis suggests that the gene is present as a single copy. The transcription initiation site was determined by primer extension analysis and S1 mapping. The TATA box and CCAAT box sequences were found at -30, and -121, respectively, from the transcription initiation site. Tenecin 3 mRNA is abundantly expressed in larvae and adults, while little was detected in RNAs from pupae, suggesting that the expression of the tenecin 3 gene is developmentally regulated.

Clinicopathologic features of indocyanine green angiography-imaged, surgically excised choroidal neovascular membranes

OBJECTIVE

The authors describe the clinicopathologic features of surgically excised choroidal neovascular membranes imaged by indocyanine green angiography (ICG).

DESIGN

Fifteen eyes from 15 patients with surgically excised subfoveal choroidal neovascular membranes underwent preoperative and postoperative ICG angiography. All excised membranes were examined by light microscopy for overall configuration and the presence of cellular and extracellular constituents. One membrane was examined by transmission electron microscopy.

RESULTS

Fourteen patients had age-related macular degeneration and one had ocular histoplasmosis syndrome. Constituents in more than 50% of membranes included retinal pigment epithelium (15/15), vascular endothelium (14/15), inflammatory cells (10/15), and basal laminar deposit (8/15). Basil laminar deposit was present only in membranes of patients with age-related macular degeneration. Eleven membranes were located primarily under the retinal pigment epithelium and four were located primarily under the neurosensory retina. There appeared to be no correlation between the ICG appearance and the histopathologic configuration of the membranes.

CONCLUSION

Surgically excised ICG-imaged membranes correspond to subretinal pigment epithelium and subneurosensory retinal choroidal neovascularization.

Atovaquone inhibits the glucuronidation and increases the plasma concentrations of zidovudine

The pharmacokinetic interaction between atovaquone, a 1,4-hydroxynaphthoquinone, and zidovudine was examined in an open, randomized, three-phase crossover study in 14 patients infected with human immunodeficiency virus. Atovaquone (750 mg every 12 hours) and zidovudine (200 mg every 8 hours) were given orally alone and in combination. Atovaquone significantly increased the area under the zidovudine concentration-time curve (AUC) (1.82 +/- 0.62 micrograms.hr/ml versus 2.39 +/- 0.68 micrograms.hr/ml; p < 0.05) and decreased the oral clearance of zidovudine (2029 +/- 666 ml/min versus 1512 +/- 464 ml/min; p < 0.05). In contrast, atovaquone tended to decrease the AUC of zidovudine-glucuronide (7.31 +/- 1.51 micrograms.hr/ml versus 6.89 +/- 1.42 micrograms.hr/ml; p < 0.1) and significantly decreased the ratio of AUC zidovudine-glucuronide/AUC zidovudine (4.48 +/- 1.94 versus 3.12 +/- 1.1; p < 0.05). The maximum concentration of zidovudine-glucuronide was significantly lowered by atovaquone (5.7 +/- 1.5 versus 4.57 +/- 0.97 micrograms/ml; p < 0.05). Zidovudine had no effect on the pharmacokinetic disposition of atovaquone. Atovaquone appears to increase the AUC of zidovudine by inhibiting the glucuronidation of zidovudine.

Purification and cDNA cloning of an antifungal protein from the hemolymph of Holotrichia diomphalia larvae

An antifungal protein (AFP), holotricin 3, was purified from the hemolymph of the coleopteran insect Holotrichia diomphalia larvae. Analysis of its cDNA showed that holotricin 3 is a novel Gly- and His-rich protein consisting of 84 amino acid residues. This protein was similar to AFP, an antifungal protein of Sarcophaga peregrina that was reported previously, in terms of molecular size and high content of Gly and His residues. However, no appreciable sequence similarity was detected between the two proteins.

Evaluation of biomarkers for occupational exposure to benzene

OBJECTIVE

To evaluate the relations between environmental benzene concentrations and various biomarkers of exposure to benzene.

METHODS

Analyses were carried out on environmental air, unmetabolised benzene in urine, trans, trans-muconic acid (ttMA), and three major phenolic metabolites of benzene; catechol, hydroquinone, and phenol, in two field studies on 64 workers exposed to benzene concentrations from 0.12 to 68 ppm, the time weighted average (TWA). Forty nonexposed subjects were also investigated.

RESULTS

Among the five urinary biomarkers studied, ttMA correlated best with environmental benzene concentration (correlation coefficient, r = 0.87). When urinary phenolic metabolites were compared with environmental benzene, hydroquinone correlated best with benzene in air. No correlation was found between unmetabolised benzene in urine and environmental benzene concentrations. The correlation coefficients for environmental benzene and end of shift catechol, hydroquinone, and phenol were 0.30, 0.70, and 0.66, respectively. Detailed analysis, however, suggests that urinary phenol was not a specific biomarker for exposure below 5 ppm. In contrast, ttMA and hydroquinone seemed to be specific and sensitive even at concentrations of below 1 ppm. Although unmetabolised benzene in urine showed good correlation with atmospheric benzene (r = 0.50, P < 0.05), data were insufficient to suggest that it is a useful biomarker for exposure to low concentrations of benzene. The results from the present study also showed that both ttMA and hydroquinone were able to differentiate the background level found in subjects not occupationally exposed and those exposed to less than 1 ppm of benzene. This suggests that these two biomarkers are useful indices for monitoring low concentrations of benzene. Furthermore, these two metabolites are known to be involved in bone marrow leukaemogenesis, their applications in biological monitoring could thus be important in risk assessment.

CONCLUSION

The good correlations between ttMA, hydroquinone, and atmospheric benzene, even at concentrations of less than 1 ppm, suggest that they are sensitive and specific biomarkers for benzene exposure.

Rupture of radial and arcuate keratotomy scars by blunt trauma 91 months after incisional keratotomy

PURPOSE/METHODS

We studied a case in which blunt trauma caused dehiscence of radial and arcuate corneal scars 91 months after incisional keratotomy. The ruptured incisions did not extend beyond the corneoscleral limbus.

RESULTS/CONCLUSIONS

Incisional refractive surgery renders the cornea susceptible to blunt traumatic rupture. This vulnerability results from the intrinsic weakness of the keratotomy wounds. Our case documents that this weakness persists up to 91 months after the operation.

Liquid chromatographic determination of urinary 2-thiothiazolidine-4-carboxylic acid, a biomarker of carbon disulphide exposure

An effective gradient high-performance liquid chromatographic method for baseline separation of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA), with photodiode array detection at 271 nm was described. o-Methylhippuric acid was used as an internal standard (I.S.). A 1-ml urine sample was saturated with 300 mg of sodium sulphate, acidified with 100 microliters of 6 M hydrochloric acid, extracted twice with 2 ml of diethyl ether, and after evaporation, the residue was taken up in 1 ml of 0.1% (v/v) phosphoric acid. The two mobile phases used for gradient elution were: (A) 10 mM ammonium dihydrogenphosphate (pH 3.5) and (B) same concentration of buffer but containing 20% (v/v) of methanol (pH 4.8). The flow-rate was set at 1.0 ml/min. TTCA and I.S. were detected at 2.2 and 9.1 min, respectively. The method was validated with urine samples collected from normal subjects and workers occupationally exposed to carbon disulphide. The present method enables the detection of urinary TTCA at a concentration of 0.025 mg/l. Analytical recovery and reproducibility generally exceeded 90%. The proposed method is considered more sensitive, specific and reliable than other existing methods.

A sapecin homologue of Holotrichia diomphalia: purification, sequencing and determination of disulfide pairs

We purified and characterized a sapecin homologue, named holotricin 1, from the hemolymph of immunized larvae of a coleopteran insect, Holotrichia diomphalia. We determined its complete amino acid sequence and three disulfide pairs. Holotricin 1 consisted of 43 amino acid residues and showed potent antibacterial activity against gram-positive bacteria, but antibacterial activity against gram-negative bacteria was not obvious.

Ovadendron sulphureo-ochraceum endophthalmitis after cataract surgery

PURPOSE

We examined an 82-year-old woman with delayed-onset endophthalmitis caused by an opportunistic pathogen, Ovadendron sulphureo-ochraceum.

METHODS

Tissue obtained during vitrectomy was cultured and examined by light and electron microscopy. An enucleation specimen was examined by light microscopy.

RESULTS

The patient had fungal endophthalmitis, with O. sulphureo-ochraceum present in the lens capsule. The eye developed a necrotizing scleritis secondary to O. sulphureo-ochraceum. The patient failed to respond to intravitreous, subconjunctival, and systemic amphotericin B, and the eye was enucleated.

CONCLUSION

In this case of O. sulphureo-ochraceum as a human pathogen, the organism caused endophthalmitis after cataract extraction.

Aflatoxin B1-induced 8-hydroxydeoxyguanosine formation in rat hepatic DNA

A time- and dose-dependent increase in 8-hydroxydeoxyguanosine (8-OHdG) was observed in rat hepatic DNA after a single i.p. injection of aflatoxin B1 (AFB1). It was also found that pre-treatment with selenium or deferoxamine significantly reduced 8-OHdG level in AFB1-administered rats. In contrast, no reduction in 8-OHdG concentration was found in vitamin E-pre-treated rats. These results provide evidence that AFB1 causes oxidative DNA damage in rat liver, which may involve hydroxyl radicals as the initiating species. It is postulated that AFB1-induced oxidative DNA damage (8-OHdG formation) may constitute an important pathway in AFB1 hepatocarcinogenesis.

Fatigue of Cord-Rubber Composites

Fatigue failure mechanisms and their dependence on cyclic loading frequency were assessed in the case of a nylon fiber-reinforced elastomer matrix composite representing the actual carcass of bias aircraft tires. Under uniaxial tension, the angle-plied composite specimens were subjected to a considerably large interply shear strain before failure. The composite specimens exhibited infinite fatigue life when stress amplitude was below a threshold level, i.e., fatigue endurance limit. Under cyclic stresses exceeding the endurance limit, localized damage in the form of fiber-matrix debonding and matrix cracking was formed and developed into the delamination eventually leading to gross failure of the composite. The process of damage accumulation was accompanied by a continuous increase of cyclic strain as well as temperature. Fatigue lifetime and the resistance to damage accumulation of aircraft tire carcass composite were strongly influenced by cyclic frequency. The use of higher frequency resulted in shorter fatigue lifetimes at a given stress amplitude and lower endurance limit. The extent of xdynamic creep at gross failure, which is defined as the increase of cyclic strain beyond initial elastic deformation, was roughly independent of stress amplitude under the frequency of 1 Hz, but decreased with higher stress amplitude when the frequency was raised to 10 Hz. Obviously a critical level of dynamic creep exists for gross failure of the composite and this level appears to be independent of the stress amplitude at low frequency. When the frequency is sufficiently high, heat generation due to hysteretic loss is expected to degrade the materials. In this situation, the critical level of dynamic creep for gross failure seems to be reduced by the loss of matrix flexibility as well as fiber-matrix bonding strength, with the degree of reduction becoming greater under higher stress amplitude.

Elevated levels of benzene-related compounds in the urine of cigarette smokers

Benzene exposure causes leukemia and lymphomas. Recent epidemiological findings have also shown an association between cigarette smoking and an increased risk of leukemia. However, further evidence is required to document the biological plausibility of this association. In evaluating this link, it is important to note that cigarette smoke contains benzene and various pyrolytic compounds, among other carcinogens. This study aims to determine the uptake of benzene by measuring 3 benzene-related compounds in cigarette smokers and non-smokers. Urinary concentrations of catechol (CAT), hydroquinone (HQ), and trans,trans-muconic acid (tt-MA) were measured by high-performance liquid chromatography (HPLC) with fluorimetric and UV detection, respectively. The results showed that these compounds were present in all urine samples. However, the concentrations were significantly higher in smokers than in non-smokers. The mean level of urinary tt-MA was 0.19 +/- 0.09 mg/g creatinine for 46 male smokers and the corresponding value for 40 non-smokers was 0.14 +/- 0.07 mg/g creatinine. The mean concentrations of HQ and CAT were 0.81 +/- 0.4 and 3.51 +/- 2.6 mg/g creatinine for smokers, and 0.45 +/- 0.4 and 1.94 +/- 1.2 mg/g creatinine for non-smokers, respectively. These results suggest that cigarette smoking is associated with a significant additional exposure to benzene and its related compounds. Furthermore, significant correlations were observed between the concentrations of cotinine, the metabolite of nicotine, and the above compounds. These findings suggest that the exposure originated from cigarette smoking.

Determination of benzene and its metabolites: application in biological monitoring of environmental and occupational exposure to benzene

Methods for the biological monitoring of benzene and its metabolites in exhaled air, blood and urine are reviewed. Analysis of benzene in breath can be carried out by using an exhaled-air collection tube and direct analysis by GC or GC-MS; however, this technique is less reliable when compared to analysis using blood or urine. For the determination of non-metabolized benzene in blood and urine, GC head-space analysis is recommended. Phenol, the major metabolite of benzene can be monitored by either HPLC or GC methods. However, urinary phenol has proved to be a poor biomarker for low-level benzene exposure. Recent studies have shown that trans,trans-muconic acid, a minor metabolite of benzene can be determined using HPLC with UV detection. This biomarker can be used for detection of low-level benzene exposure. Urinary S-phenylmercapturic acid is another sensitive biomarker for benzene, but it can be detected only by GC-MS. Hydroquinone, catechol and 1,2,4-benzenetriol can be measured using HPLC with either ultraviolet or fluorimetric detection. Nevertheless, their use for low-level assessment requires further studies. Eventually, for the assessment of health risks caused by benzene, biological-exposure reference values need to be established before they can be widely used in a field setting.

Adjunctive folinic acid with trimethoprim-sulfamethoxazole for Pneumocystis carinii pneumonia in AIDS patients is associated with an increased risk of therapeutic failure and death

Ninety-two AIDS patients with Pneumocystis carinii pneumonia (PCP) were randomized to receive folinic acid or matching placebo in conjunction with trimethoprim-sulfamethoxazole in a prospective, double-blind trial. Neither frequency of dose-limiting toxicity (26% vs. 37%; P = .4) nor time to occurrence (P = .7) was associated with folinic acid use. Although incidence of neutropenia was lower in patients receiving folinic acid (23% vs. 47%; P = .03), time to occurrence of neutropenia did not differ (P = .4). Seven (7.6%) of 92 patients with confirmed PCP met criteria for therapeutic failure, and 5 (6%) died during therapy. Surprisingly, folinic acid use was associated with a higher rate of both therapeutic failure (15% vs. 0; P = .01) and death (11% vs. 0; P = .06). Time to therapeutic failure was shorter and probability of death greater in patients receiving folinic acid (P = .005, P = .02, respectively), even when adjusted for baseline arterial oxygen pressure, serum lactate dehydrogenase, respiratory rate, CD4 cell count, and peak serum level of trimethoprim or sulfamethoxazole.