Inability of GSTT1 to activate iodinated halomethanes to mutagens in Salmonella

Drinking water disinfection by-products (DBPs), including the ubiquitous trihalomethanes (THMs), are formed during the treatment of water with disinfectants (e.g., chlorine, chloramines) to produce and distribute potable water. Brominated THMs (Br-THMs) are activated to mutagens via glutathione S-transferase theta 1 (GSTT1); however, iodinated THMs (I-THMs) have never been evaluated for activation by GSTT1. Among the I-THMs, only triiodomethane (iodoform) has been tested previously for mutagenicity in Salmonella and was positive (in the absence of GSTT1) in three strains (TA98, TA100, and BA13), all of which have error-prone DNA repair (pKM101). We evaluated five I-THMs (chlorodiiodomethane, dichloroiodomethane, dibromoiodomethane, bromochloroiodomethane, and triiodomethane) for mutagenicity in Salmonella strain RSJ100, which expresses GSTT1, and its homologue TPT100, which does not; neither strain has pKM101. We also evaluated chlorodiiodo-, dichloroiodo-, and dibromoiodo-methanes in strain TA100 +/- rat liver S9 mix; TA100 has pKM101. None was mutagenic in any of the strains. The I-THMs were generally more cytotoxic than their brominated and chlorinated analogues but less cytotoxic than analogous trihalonitromethanes tested previously. All five I-THMs showed similar thresholds for cytotoxicity at ~2.5 μmoles/plate, possibly due to release of iodine, a well-known antimicrobial. Although none of these I-THMs was activated by GSTT1, iodoform appears to be the only I-THM that is mutagenic in Salmonella, only in strains deficient in nucleotide excision repair (uvrB) and having pKM101. Given that only iodoform is mutagenic among the I-THMs and is generally present at low concentrations in drinking water, the I-THMs likely play little role in the mutagenicity of drinking water.

[Specific features of materials for initial pulpitis treatment]

The aim of the current study was to assess antibacterial and cytotoxic properties of Biodentine (Septodont), Rootdent (TehnoDent) and adhesive Futurabond НР (Voco). Two lines of experiments were carried out using cements water solutions and firm tablet-like samples (made by means of special pattern). Citotoxic activity was tested on NCTC L929 mice line fibroblasts culture. All the examined materials showed antibacterial activity against E. coli, S. aureus, C. albiсans, St. faecalis, mostly evident in Futurabond and the poorest in Biodentine samples. As for cytotoxic properties, Biodentine proved not to suppress metabolic activity stimulating odontotropic impact. The results confirm the analyzed materials to be a useful tool for deep caries lesions and initial pulpitis treatment.

Ability of root canal antiseptics used in dental practice to induce chromosome aberrations in human dental pulp cells

Root canal antiseptics are topically applied to root canals within the pulpless teeth to treat the root canal and periapical infections. Because the antiseptics that are applied to root canals can penetrate through dentin or leak out through an apical foramen into the periodontium and distribute by the systemic circulation, it is important to study the safety of these antiseptics. In the present study, we examined the ability to induce chromosome aberrations in human dental pulp cells of five root canal antiseptics, namely, carbol camphor (CC), camphorated p-monochlorophenol (CMCP), formocresol (FC), calcium hydroxide, and iodoform which are most commonly used in dental practice. Statistically significant increases in the levels of chromosome aberrations were induced by CC, FC, or iodoform in a concentration-dependent manner. Conversely, CMCP and calcium hydroxide failed to induce chromosome aberrations in the absence or presence of exogenous metabolic activation. The percentages of cells with polyploid or endoreduplication were enhanced by FC or iodoform. Our results indicate that the root canal antiseptics that exhibited a positive response are potentially genotoxic to human cells.

Occupational exposure to methyl iodide

Little is known about the effects of methyl iodide (MI) on the skin after short-term accidental cutaneous exposure because this type of exposure to MI has rarely been reported. In the present case, asymptomatic vesicles developed within 24 hours of exposure, an acute hemorrhagic eruption developed several days later, and an erythematous edematous eruption and large bullae developed several days after the hemorrhagic eruption. This sequence of findings was remarkably similar to the most recently reported case of short-term accidental MI exposure, and we believe that the findings described and the time course of the findings may be a reproducible phenomenon following this type of cutaneous exposure to MI.

Carbon dioxide digital subtraction angiography-assisted endovascular aortic aneurysm repair in the azotemic patient

OBJECTIVE

This report analyzes the safety and efficacy of carbon dioxide digital subtraction angiography (CO(2)-DSA) for EVAR in a group of patients with renal insufficiency compared with a concurrent group of patients with normal renal function undergoing EVAR with iodinated contrast angiography (ICA).

METHODS

Between 2003 and 2005, 100 consecutive patients who underwent EVAR using ICA, CO(2)-DSA, or both were retrospectively reviewed, and preoperative, intraoperative, postoperative, and follow-up variables were collected. Patients were divided into two groups depending on renal function and contrast used. Group I comprised patients with normal renal function in whom ICA was used exclusively, and group II patients had a serum creatinine >or=1.5 mg/dL, and CO(2)-DSA was used preferentially and supplemented with ICA, when necessary. The two groups were compared for the outcomes of successful graft placement, renal function, endoleak type, and frequency, and the need for graft revision. Comparisons were made using chi(2) analysis, Student t test, and the Fisher exact test.

RESULTS

A total of 84 EVARs were performed in group I and 16 in group II. Patient demographics and risk factors were similar between groups with the exception of serum creatinine, which was significantly increased in group II (1.8 mg/dL vs 1.0 mg/dL P < .0005). All 100 endografts were successfully implanted. Patients in group II had longer fluoroscopy times, longer operative times, and increased radiation exposure, and 13 of 16 patients required supplemental ICA. Mean iodinated contrast use was 27 mL for group II vs 148 mL in group I (P < .0005). Mean postoperative serum creatinine was unchanged from baseline, and 30-day morbidity was similar for both groups. No patient required dialysis. No patients died. Perioperatively, and at 1 and 6 months, the endoleak type and incidence and need for endograft revision was no different between groups.

CONCLUSIONS

CO(2)-DSA is safe, can be used to guide EVAR, and provides outcomes similar to ICA-guided EVAR. CO2-DSA protects renal function in the azotemic patient by lessening the need for iodinated contrast and associated nephrotoxicity, but with the tradeoff of longer fluoroscopy and operating room times and increased radiation exposure.

BIPP madness; an iatrogenic cause of acute confusion

An 81-year-old man, admitted under the Ear, Nose and Throat Team with persistent epistaxis, developed an acute confusional state. He was previously physically independent and mentally competent. Immediate investigations did not reveal a cause for his deterioration. He eventually made a full recovery and returned home. Subsequently, his serum bismuth level was noted to be within the toxic range and was felt to have been the cause of his confusional state.

Transient hypothyroidism in a breastfed infant after maternal use of iodoform gauze

We describe transient hypothyroidism induced in a 2 week-old breastfed infant by maternal use of iodoform gauze for a perirectal abscess. The initial newborn thyroid screen was normal. Low levels of thyroid hormone were discovered during a routine second newborn screen. Thyroid function has since normalized with short-term therapy with thyroxine and after the mother discontinued use of the packing iodoform gauze. This case illustrates the need to avoid iodine-containing products in breastfeeding mothers.

Radicular cyst associated with a primary molar following pulp therapy: a case report

A radicular cyst arising from the primary second molar and causing displacement of the permanent successor to the lower border of the mandible, with accompanying buccal expansion, was examined clinically and radiographically. Extraction of the primary molar and extirpation of the cyst led to uneventful healing. The primary molar had received pulp treatment with therapeutic agents approximately 1.5 years prior to the patient's first visit. The relationship between pulp treatment and rapid growth of the radicular cyst is discussed.

The role of glutathione S-transferase- and cytochrome P450-dependent metabolism in the olfactory toxicity of methyl iodide in the rat

The aim of this study was to investigate the role of metabolic activation in the olfactory toxicity of methyl iodide (MeI). Adult male rats were exposed via nose-only inhalation to 100 ppm MeI for 0-6 h, and non-protein sulphydryl (NP-SH) concentrations determined in selected tissues. Depletion of NP-SH occurred in all tissues, but was most marked and rapid in the respiratory epithelium of the nasal cavity and the kidney. Olfactory, lung and liver NP-SH levels were affected to a lesser extent, and those of the brain declined by only 20-30% over the whole time course. In order to modulate glutathione (GSH) status, animals were pre-treated with (1) phorone plus L-buthionine sulphoximine (BSO), which depleted NP-SH levels in all the tissues examined, or (2) the isopropyl ester of GSH (IP-GSH), which was shown to replenish NP-SH concentrations in all tissues except the liver of animals previously administered phorone. When animals were pre-treated with phorone plus BSO and then exposed to 100 ppm MeI for 2 h, there was a potentiation of the toxicity of MeI as judged by the clinical observations on the animals. In contrast, treatment with IP-GSH prior to and during exposure to MeI for 4 h afforded a marked protection to the olfactory epithelium. In order to inhibit cytochromes P450, animals were pre-treated with cobalt protoporphyrin IX. This decreased hepatic cytochrome P450 concentrations by > 90%, but when animals were then exposed to 100 ppm MeI for 4 h there was no effect on the severity of the olfactory lesion. These results indicate that conjugation of MeI with GSH is a detoxification rather than an activation pathway. Also, there is no major role for cytochrome P450-dependent oxidation in the development of the olfactory lesion.

Hypersensitive allergic reactions to bismuth-iodoform-paraffin paste following ear surgery

The case notes of 185 patients who had bismuth-iodoform-paraffin paste (BIPP) impregnated ribbon gauze used for packing following ear surgery were analysed retrospectively. The incidence of hypersensitive allergic reactions to BIPP was 5.9 per cent and a five-fold increase risk of developing allergic reactions was found in those with previous exposure to BIPP. Where temporalis fascia was used to repair tympanic membrane defects, the incidence of tympanic membrane graft perforations was higher when allergic reactions to BIPP developed post-operatively, compared to non-allergic cases.

Extradural application of bismuth iodoform paraffin paste causing relapsing bismuth encephalopathy: a case report with CT and MRI studies

Bismuth iodoform paraffin paste (BIPP) is used in dressings in ear, nose, and throat, dental, and neurosurgical practice. Neurotoxicity due to absorption of bismuth from the BIPP pack is rare. It is preventable and reversible but likely to be fatal if unrecognised. A case of relapsing but reversible toxic encephalopathy due to a large extradural BIPP pack is reported in a 57 year old Caucasian woman, operated on for a huge basal cell carcinoma of the vertex invading the skull and extradural space. Clinical, neuroradiological (CT and MRI), and biochemical studies are presented and discussed in the light of the available literature.

Internal resorption occurring after accidental extrusion of iodoform paste into the mandibular canal

The precise etiology of internal resorption is unknown but it is generally believed that triggering factors are infection and persistent chronic pulpitis. A case is presented with internal resorption, which developed subsequent to extrusion of iodoform paste from the adjacent tooth into the mandibular canal. According to clinical and radiographic examinations made after 7 years, the tooth was clinically asymptomatic, vital and the internal resorption was arrested without treatment.

Mechanisms of carcinogenicity of methyl halides

Methyl chloride, bromide, and iodide are used as methylating agents. These compounds are mutagenic in short-term tests and do not require activation by exogenous S9 mix. In DNA-binding studies performed in rats and mice, 14C-labeled methyl chloride was given by inhalation, and methylation of DNA bases was examined. The compound did not lead to specific DNA adducts. In particular, methylation of DNA bases was not observed. In contrast, methyl bromide and methyl iodide, upon oral and inhalation administration to rats and mice, caused systemic DNA methylation. Specifically, 3-methyl-adenine, 7-methyl-guanine, and O6-methyl-guanine were formed. Long-term inhalation bioassays have been performed in rats and mice with methyl chloride and methyl bromide. Methyl chloride induced renal tumors, but only in male mice at the highest concentration tested (1000 ppm). Under these special conditions, a number of secondary effects occur subsequent to glutathione depletion in the target tissue, resulting in DNA damage (DNA-protein cross-links and probably DNA single-strand breaks). The particular coincidence of secondary high-dose effects precludes a risk extrapolation to man. Methyl bromide did not induce tumors in rats and mice when administered by inhalation. However, experimental data point to a possible local carcinogenic effect on the rat forestomach when the compound is given by gavage. A factor that accounts for the discrepancy between systemic DNA methylation and apparent noncarcinogenicity upon inhalation might be the preference of 7-N over O6 methylation of guanine. An extrapolation of the negative rodent inhalation bioassay of methyl bromide to man might be problematic because rodents metabolize methyl bromide very quickly whereas in humans there is a particular subpopulation that only poorly metabolizes the compound ("nonconjugators"). Such individuals can be characterized by incubation of erythrocytes with methyl chloride or methyl bromide and measurement of the substrate decline. Methyl iodide has been tested, with positive outcome, in early carcinogenicity bioassays not based on modern methodology. However, these results, along with the proven systemic methylating potency of methyl iodide, argue in favor of a carcinogenic effect of the compound.

Influence of endodontic materials on the bonding of composite resin to dentin

We assessed the bond strength of a composite resin to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 15 min or 48 h with a 1-mm layer of a variety of materials. The products were mechanically removed and a composite resin cylindrical specimen bonded to the dentin surface using the Prisma universal bond system. After 7 days immersion at 37 degrees C in water, the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. Statistical analysis showed that some materials (Grossmans Cement, IRM, Maisto's slowly resorbable paste) reduced the strength of the bond or even precluded bonding. It is necessary to develop techniques that will eliminate this when restoring endodontically treated teeth.

Tissue necrosis after using an arsenical endodontic preparation: a case report

A case is reported of severe loss of alveolar bone in the maxilla, as a result of leakage into the tissues of an arsenical paste from the pulp chamber of an endodontically 'treated' tooth. The history of the use of arsenic in dentistry is discussed, as are the hazards inherent in the use of this outmoded and dangerous medicament.

BIPP induced methaemoglobinaemia

Bismuth subnitrate, one of the constituents of BIPP is known to cause methaemoglobinaemia. Ten patients had blood estimations for methaemoglobin levels before and after nasal packing with BIPP impregnated gauze. Only one patient exhibited abnormal levels of methaemoglobin and this was most probably the result of the large quantity of BIPP used. It is unlikely that significant methaemoglobinaemia occurs during the routine use of BIPP in the nose.

Radiographic evaluation of intraosseous implants of endodontic materials

Following several case reports of cyst development after endodontic treatment of decidous teeth, the osseous response to formaldehyde- or phenol-based materials was evaluated by a standardized radiographic technique. Endodontic medicaments contained in Teflon carriers were implanted between feline deciduous canine and molar teeth and the permanent successional teeth. Persistent radiolucency surrounding formocresol implants and sequestration of Kri-paste implants were noted in contrast to apparent bony healing around the zinc oxide-eugenol controls and those implants containing glutaraldehyde. These results suggest a greater tissue tolerance to glutaraldehyde-containing agents in contrast to the more traditional endodontic agents used in deciduous teeth.

Bipp: a case of toxicity?

Ribbon gauze impregnated with bismuth iodoform paraffin paste is a dressing used in both oral and ENT surgery. A case is presented in which it was implicated in increased postoperative morbidity highly suggestive of a toxic state.

Experimental study of pulpotomy with calcium hydroxide-iodoform paste in dogs' immature permanent teeth

To investigate the healing process and continuous root development following pulpotomy with improved calcium hydroxide-iodoform paste, the authors performed an experimental study of pulpotomy in immature permanent teeth. Thirty five incompletely formed root canals in dogs were used, and radiographical and histopathological observations were made. The results lead to the conclusion that pulpotomy with improved calcium hydroxide-iodoform paste is a very effective treatment for immature permanent teeth.

Overfilling of the root. A case report

In this report, attempts have been made to present as an interesting case report overfilling of the root canal, which is one of the most important errors caused by a dentist. The iodoform paste that was applied as a result of canal treatment, which was performed on the left mandibular second premolar, did not only overfill the apical lesion of that tooth but also extended as far as the apical region of the left mandibular second molar. In the periapical and panoramic radiographs, it is seen that the overfilled canal filling material extended as far as the angulus region of the mandible. It is also observed that the canalis mandibularis was not affected by this process and that the overfilled canal paste extended through the trabeculae of the mandibular bone. The fact that the paste disappeared after a short period of time supports the view that the canal filling material was the iodoform paste, which was resorbed.

BIPP allergy causing facial paralysis

The present case appears to be the first recorded in which BIPP sensitivity led to a delayed post-operative facial palsy.

[Pathogenesis of hyperlipidemia and fatty liver of rabbits induced by methyl iodide. Increased synthesis and secretion of triglyceride in the liver]

Male Japanese white rabbits were injected subcutaneously with methyl iodide (57 mg/kg body weight/day) on two successive days and their lipid metabolism was investigated 48 hr after the last injection. The plasma triglyceride levels increased from the preinjection average of 56.1 mg/dl to 246.0 mg/dl on an average, the individual values being greatly variable. Analysis of lipoprotein profile of plasma showed a significant increase of very low density lipoproteins (VLDL). Lipolytic activities in postheparin plasma did not change. However, rates of triglyceride secretion into plasma, measured by Triton WR 1339 injection method, were significantly higher in the animals treated with methyl iodide than in the controls. Histological investigation of the liver showed diffuse fat deposits in the hepatocytes without any destructive and inflammatory changes. The results indicate that hyperlipidemia and fatty liver of rabbits induced by methyl iodide is related to the elevation of triglyceride synthesis and its secretion in the liver.

[Iodine-induced hypothyroidism (author's transl)]

Excessive administration of iodine over a long period may cause hypothyroidism in suitably disposed individuals and provoke the formation of a goiter. The underlying reason for this is the pathological lack of adaptation of the thyroid gland to high doses of iodine with persisting inhibition of hormone production through excess of intracellular iodine (Wolff-Chaikoff effect). Asthmatic patients--as in the case described - are usually affected, when they have taken iodine-containing expectorants over a long time. Provocation of an iodine-induced hypothyroidism by the recently required iodine prophylaxis of endemic goiter is not to be expected because the quantities of iodine lie within the physiological range.

Waldenströms macroglobulinaemia and intravenous contrast media

In vivo and in vitro studies have been performed in a group of patients with immunoproliferative diseases to evaluate the risk of serious reactions due to serum jelling after intravenous injection of iodinated contrast media. Sol-jell convertion and/or turbidimetric variations have not been observed when either sera or plasmas have been mixed with variable amounts of a methylglucamine salt of ioglycamic acid (MGI) and other compounds. In addition, no side-effects have been clinically recorded in three patients with Waldenströms macroglobulinaemia (WM) whose sera and/or plasmas had been studied in vitro, when they have been submitted to intravenous contrast examinations. The results suggest that there is not an evidence of a relationship between iodinated contrast media and fatal reactions due to sol-jell alterations in patients with WM and therefore a radiological examination using contrast media may be carried out in those patients.