A review of the enzymology of arsenic metabolism and a new potential role of hydrogen peroxide in the detoxication of the trivalent arsenic species

This laboratory has studied the enzymology involved in the biotransformation of inorganic arsenic to dimethylarsinous acid (DMA(III)) and in human studies established that monomethylarsonous acid (MMA(III)) and DMA(III) appear in urine of people chronically exposed to arsenic. It appears that only two proteins are required for inorganic arsenic biotransformation in the human, namely, monomethylarsonic acid (MMA(V)) reductase and arsenic methyltransferase. MMA(V) reductase and the unique glutathione transferase omega (hGST-O) are identical proteins. Arsenicals with a +3 oxidation state are more toxic than the +5 species. While methylation of arsenite, MMA(III), and DMA(III) produces less toxic +5 oxidation arsenic species containing an additional methyl group such as MMA(V), dimethylarsinic acid (DMA(V)), and TMAO, a new mechanism involving hydrogen peroxide for detoxifying arsenite, MMA(III), and DMA(III) is proposed based on in vitro experiments.

Oxidation and detoxification of trivalent arsenic species

Arsenic compounds with a +3 oxidation state are more toxic than analogous compounds with a +5 oxidation state, for example, arsenite versus arsenate, monomethylarsonous acid (MMA(III)) versus monomethylarsonic acid (MMA(V)), and dimethylarsinous acid (DMA(III)) versus dimethylarsinic acid (DMA(V)). It is no longer believed that the methylation of arsenite is the beginning of a methylation-mediated detoxication pathway. The oxidation of these +3 compounds to their less toxic +5 analogs by hydrogen peroxide needs investigation and consideration as a potential mechanism for detoxification. Xanthine oxidase uses oxygen to oxidize hypoxanthine to xanthine to uric acid. Hydrogen peroxide and reactive oxygen are also products. The oxidation of +3 arsenicals by the hydrogen peroxide produced in the xanthine oxidase reaction was blocked by catalase or allopurinol but not by scavengers of the hydroxy radical, e.g., mannitol or potassium iodide. Melatonin, the singlet oxygen radical scavenger, did not inhibit the oxidation. The production of H2O2 by xanthine oxidase may be an important route for decreasing the toxicity of trivalent arsenic species by oxidizing them to their less toxic pentavalent analogs. In addition, there are many other reactions that produce hydrogen peroxide in the cell. Although chemists have used hydrogen peroxide for the oxidation of arsenite to arsenate to purify water, we are not aware of any published account of its potential importance in the detoxification of trivalent arsenicals in biological systems. At present, this oxidation of the +3 oxidation state arsenicals is based on evidence from in vitro experiments. In vivo experiments are needed to substantiate the role and importance of H2O2 in arsenic detoxication in mammals.

Polymorphisms in the Human Monomethylarsonic Acid (MMAV) Reductase/hGSTO1 Gene and Changes in Urinary Arsenic Profiles

Large interindividual variability in urinary arsenic profiles, following chronic inorganic arsenic exposure, is well-known in humans. To understand this variability, we studied the relationship between polymorphisms in the gene for human monomethylarsonic acid (MMA(V)) reductase/hGSTO1 and the urinary arsenic profiles of individuals chronically exposed to arsenic in their drinking water. To ensure that we did not overlook rare polymorphisms, not included in the public databases, we amplified and sequenced all six exons of the gene and their flanking regions, using DNA isolated from peripheral blood samples of 75 subjects, living in the vicinity of Torreon, Mexico. Four groups, based on the levels of arsenic (9-100 microg/L) in their drinking water, were studied. We identified six novel polymorphisms and two reported previously. The novel polymorphisms were a three base pair deletion (delGGC) in the first intron; a G > C transversion, leading to a serine-to-cysteine substitution at amino acid 86; a G > T transversion and a A > T transversion in intron 5; a G > A transition resulting in glutamate-to-lysine substitution in amino acid 208; and a C > T transition producing an alanine-to-valine substitution in amino acid 236. Two subjects displayed significant differences in patterns of urinary arsenic; they had increased levels of urinary inorganic arsenic and reduced levels of methylated urinary arsenic species as compared to the rest of the study population. These two subjects had the same unique polymorphisms in hGSTO1 in that they were heterozygous for E155del and Glu208Lys. The identified SNPs may be one of the reasons for the large interindividual variability in the response of humans to chronic inorganic arsenic exposure. The findings suggest the need for further studies to identify unambiguously specific polymorphisms that may account for interindividual variability in the human response to chronic inorganic arsenic exposure.

Glutathione-S-transferase-omega [MMA(V) reductase] knockout mice: Enzyme and arsenic species concentrations in tissues after arsenate administration☆

Inorganic arsenic is a human carcinogen to which millions of people are exposed via their naturally contaminated drinking water. Its molecular mechanisms of carcinogenicity have remained an enigma, perhaps because arsenate is biochemically transformed to at least five other arsenic-containing metabolites. In the biotransformation of inorganic arsenic, GSTO1 catalyzes the reduction of arsenate, MMA(V), and DMA(V) to the more toxic +3 arsenic species. MMA(V) reductase and human (hGSTO1-1) are identical proteins. The hypothesis that GST-Omega knockout mice biotransformed inorganic arsenic differently than wild-type mice has been tested. The livers of male knockout (KO) mice, in which 222 bp of Exon 3 of the GSTO1 gene were eliminated, were analyzed by PCR for mRNA. The level of transcripts of the GSTO1 gene in KO mice was 3.3-fold less than in DBA/1lacJ wild-type (WT) mice. The GSTO2 transcripts were about two-fold less in the KO mouse. When KO and WT mice were injected intramuscularly with Na arsenate (4.16 mg As/kg body weight); tissues removed at 0.5, 1, 2, 4, 8, and 12 h after arsenate injection; and the arsenic species measured by HPLC-ICP-MS, the results indicated that the highest concentration of the recently discovered and very toxic MMA(III), a key biotransformant, was in the kidneys of both KO and WT mice. The highest concentration of DMA(III) was in the urinary bladder tissue for both the KO and WT mice. The MMA(V) reducing activity of the liver cytosol of KO mice was only 20% of that found in wild-type mice. There appears to be another enzyme(s) other than GST-O able to reduce arsenic(V) species but to a lesser extent. This and other studies suggest that each step of the biotransformation of inorganic arsenic has an alternative enzyme to biotransform the arsenic substrate.

Hemodynamic consequences of continuous arteriovenous hemofiltration

Continuous arteriovenous hemofiltration (CAVH) is an extracorporeal treatment in which fluid, electrolytes, and low and middle molecular weight solutes are removed from the blood by ultrafiltration. It is efficacious in the management of acute or chronic renal failure complicated by fluid overload, and following surgery. In this study, cardiac filling pressures, cardiac indices, and BP were monitored in nine patients. A mean of 7 kg of fluid was removed in ten treatments without the induction of hypotension. In nine of ten treatments, cardiac index increased following fluid removal. An increment in myocardial pump function was noted even in patients with low output heart failure. This treatment differs from dialysis in its ability to remove large fluid volumes without compromising cardiac hemodynamics. In addition, CAVH may have a role in treating volume overload patients with renal insufficiency and heart failure resistant to pharmacologic intervention.

Microbeads detection using spin-valve planar Hall effect sensors

In this paper we present a micromagnetic approach to describe the detection of magnetic nanobeads using planar Hall effect sensors. The magnetic beads polarized by a dc magnetic field generate a field, which can affect the magnetization state of spin-valve sensor, leading in principle, to a detectable signal. For magnetic nanobeads we assumed a superparamagnetic behaviour. Three detection geometries are discussed and some specific behaviours were highlighted by micromagnetic simulations. We found that when the polarising field is applied parallel with the sensor surface a very weak signal can be obtained. This is because at working fields, for which the magnetic nanobeads are magnetised, the sensor saturates. We identified other setups that can overcome this shortcoming and deliver a net signal.

[Köhlmeier-Degos disease (Malignant Atrophic Papulosis): a cause of recurrent multiple intestinal perforations]

Malignant Atrophic Papulosis (MAP) or Degos disease is a very rare vasculopathy affecting multiple systems. When associated with gastrointestinal tract or central nervous system involvment, patients with Degos disease have a poor prognosis and a high mortality. We report a case of Degos disease with systemic involvement, which ultimately caused peritonitis, sepsis, and death, despite all treatment. A 29-year-old man was admitted in June 2007 on the surgical ward of our hospital with acute generalized abdominal pain and multiple skin lesions. The patient had an appendectomy at another hospital 6 weeks before the current presentation. The exploratory laparotomy showed 2 perforations of the ileum. After the initial procedure, the patient developed spontaneous recurrent perforations of the small bowel and suffered another 3 reoperations. Neuroradiologic reports described central and peripheral nervous system involvement with progressive clinical deterioration and a meningovascular pattern at cerebral MRI. Despite aggressive treatment the patient died 3 months after the first surgical intervention.

The use of grafting material in rhinoseptoplasty

Grafting is one of the current range of instruments that rhinoplasticians deploy to achieve durable and desired aesthetic and functional outcomes. Grafts can be classified according to anatomical site and, in the vast majority of cases, they involve augmentation rhinoseptoplasty. Visible grafting material is used for aesthetic purposes and functional grafting may involve invisible grafts. This article reviews the more widely described and more common indications for grafts in rhinoseptoplasty. The authors' rhinoseptoplasty philosophy involves a preference for autogenous grafts rather than alloplastic implants to achieve both aesthetically and functionally favourable results, particularly in long-term follow-up. They also prefer grafts in an open approach, reserving graft insertion with an endonasal approach for selected cases. The rate of complications associated with grafting is very low. The aim of this paper is to discuss the relevant anatomy, functional purpose and terminology, and to describe the authors' philosophy for grafting in rhinoseptoplasty.

Day surgery in Romania

AIM

Well know in USA, Australia and then in western European countries, day surgery is still at the beginning in Romania and eastern European countries. In this paper we want to analyze the evolution and actual situation of day surgery in Romania and in County Emergency Hospital Timisoara (CEHT).

MATERIAL AND METHODS

In the implementation of day surgery in our country there were two distinct periods. Between 2007- 2013 the CEHT negotiated its own day surgery baskets with Local Health Insurance Company (LHIC). Starting from 2014 until now, the National Health Insurance Company has established new day surgery baskets which can be negotiated between CEHT and LHIC.

RESULTS

Our study shows that day surgery in CEHT has had an undulating evolution - after a rising development at the beginning it stopped for a few years and now it has an ascendant evolution.

DISCUSSION

In this context, International Association for Ambulatory Surgery (IAAS) has initiated a series of actions to support implementation and development of day surgery in Romania and Eastern European countries. The first action was the support that the International Association for Ambulatory Surgery gave to the Romanian Society of Ambulatory Surgery in organizing on 15-16 September 2013 in Timisoara the course "Day Surgery - Making it Happen Overcoming Obstacles and Barriers". Discussions after the presentation of local realities in Eastern and Western Europe were particularly creative, being the stand in the accelerated development of day surgery in Romania.

CONCLUSIONS

Day surgery and ambulatory surgery have many advantages for patients (increased comfort, lower surgical risk, minimal stress and low anxiety, high satisfaction rate), for hospital (reducing congestion in hospital, enabling it to have a better capacity to deal with serious cases), and for healthcare (increased economic efficiency, cost / patient / surgery is lower than for continuous admissions). Known in our country from 2000, the implementation of day surgery still faces many hardships.

KEY WORDS

Day surgery, ambulatory surgery, Short hospitalization.

Colocutaneous fistula: a rare postoperative complication after surgical treatment of an irreducible left inguinal hernia Case Report

AIM

The colo-cutaneous fistula is an extremely rare post-operative complication of hernias. This type of complication, besides the surgical aspects, raises also a medical-legal problem regarding the production of the fistula and its consequences.

CASE REPORT

The authors present the clinical case of a 65 years old man, J.N., from a rural background, who presented himself in the ambulatory with a colo-cutaneous fistula as a complication which debuted a few weeks after a surgical intervention for an irreducible left inguinal hernia. He was submitted to a surgical reintervention with good results.

DISCUSSION

The main particularity of the present case is the association of the colo-cutaneous fistula with the presence of the oxyuris helmintiasis in the fistulos secretions.

CONCLUSIONS

Even though it was rather difficult to obtain the patient's consent for the surgical treatment, the intervention had very good results leading to the healing of the patient.

KEY WORDS

Colo-cutaneous fistula, Enterobius vermicularis (oxyuris helmintiasis), Post-operative complications of hernia.

[Stapled vs. hand-sewn colorectal anastomosis in complicated colorectal cancer--a retrospective study]

Emergens in colorectal pathology are in most cases by complications of cancer. The prognosis for colorectal cancer is poor when this pathology is addressed in emergency situations because, on one hand, of the organ specific structure, blood supply, septic content and, on the other hand, because of the special group of patients with this pathology: aged, immunosuppressed and with various comorbidities. The high rate of postoperative complications of these patients requires a specific management. The development and improvement of medical devices has brought to the surgeons new products among which mechanice devices for anastomoses. In this study we compared two groups of operated patients (with hand sutured and stapled anastomoses) who presented as emergences with complications of colorectal cancer.

MATERIAL AND METHOD

Retrospective clinical study with a total of 72 patients who underwent a colorectal resection procedure in emergency in our clinic (Emergency Hospital Bucharest) over a period of 2 years (2007-2008).

RESULTS

The 72 patients who required emergency surgery were randomly assigned to 2 categories according to the type of anastomosis: hand sutured (group 1, n = 34) and stapled (group 2, n = 38). Age, sex, comorbidities, and tumor staging were comparable in both groups. The emergency was represented by obstruction (56.94%), hemorrhage (8.33%) and perforation (34.72%). The mortality (10.5% vs. 8.8%) and orbidity rate (20.83% vs. 15.27%) was higher in the stapled anastomosis group. The average duration of the surgical procedure performed in emergency was also quantified and was 118 min. (group 2) vs. 236 min. (group 1) respectively.

CONCLUSION

Comparison did not disclose any significant difference in the number of complications in these two groups. Anastomosis is safe in emergency colorectal surgery and the reduction of the operative time may also improve the outcome of these patients.

[Management for pseudoaneurysm of cystic artery with an arterio-biliary fistula after laparoscopic cholecystectomy: a rare case of hemobilia]

Although laparoscopic cholecystectomy is considered to be the gold standard for treatment for symptomatic cholelithiasis, it is associated with an increased risk of biliary and vascular injury compared to the traditional technique. Massive hemobilia is a rare but potentially life-threatening cause of upper gastrointestinal hemorrhage. Arterio-biliary fistula is an uncommon cause of hemobilia. We describe a case of cystic artery pseudo-aneurysm causing arterio-biliary fistula and presenting as severe melaena and cholangitis that occurred 7 months after laparoscopic cholecystectomy. Gastroduodenoscopy failed to establish the exact source of bleeding and hepatic artery angiography and selective embolization of the pseudo-aneurysm successfully controlled the bleeding. Pseudo-aneurysm of the hepatic artery is mostly iatrogenic due to biliary intervention, as demonstrated in this case. Transarterial embolization is considered the first line of intervention to stop the bleeding for most causes of hemobilia. Hemobilia is a rare complication that should be considered when managing patients with bleeding or jaundice even several months after laparoscopic cholecystectomy.

[Laparoscopic approach in gallbladder agenesis--an intraoperative surprise]

INTRODUCTION

The congenital absence of the gallbladder in the absence of biliary atresia is extremely rare, world literature recognizing only 413 cases. The aim of this study is to clarify the diagnostic and therapeutic approach of this rare condition.

METHOD

There were retrospectively analyzed the first 2 cases of gallbladder agenesis admitted and surgically approached in the Emergency Hospital, Bucharest.

RESULTS

The first case (woman, 23 years old) had typically biliary complaints at admission, shrinked gallbladder and lithiasis on ultrasound. There was a laparoscopic approach but we didn't find any gallbladder. After a non-therapeutic laparoscopy the biliary symptoms disappeared. In the second case (woman, 52 years old) the admission was for upper abdominal quadrant colicative pain and the transparietal abdominal ultrasound showed chronic cholecystitis. Common bile duct dilatation was revealed during laparoscopy. After conversion to laparotomy there was performed intraoperative colangiography, but no other biliary pathology was revealed. The initial complaints also disappeared after surgery.

CONCLUSIONS

We find the laparoscopic approach an effective method for the diagnosis of gallbladder agenesis. Postoperative Magnetic Resonance Cholangiopancreatography represents a very useful imagistic tool to rule out an intrahepatic gallbladder.