Blood Methemoglobin Research Articles

Relationship between contrast-induced nephropathy and blood methemoglobin levels in acute coronary syndrome patients

Relationship between contrast-induced nephropathy and blood methemoglobin levels in acute coronary syndrome patients

Methaemoglobinaemia due to nitrobenzene poisoning

Abstract Nitrobenzene poisoning presenting as acute methaemoglobinaemia is an uncommon medical emergency. The case of a 17-year-old male with alleged history of consumption of ‘flower all’ (composition-nitrobenzene) is being reported here. At the time of presentation to the emergency department, the patient had cyanosis of lips and feet with Glasgow coma score 12. His pulse was 161/min, blood pressure 70/40 mm Hg and oxygen saturation by pulse oximeter was 72% on room air. His pupils were bilaterally dilated with sluggish reaction. Rest of the physical examination was unremarkable. In view of desaturation, he was intubated and connected to mechanical ventilator. Blood sample taken for arterial blood gas (ABG) analysis was dark brown in colour. ABG showed pH: 7.443, arterial carbon dioxide tension: 27.8 mm Hg, arterial oxygen saturation (SaO2) 95.6% and bicarbonate 18.7 mEq/L. The calculated difference between SaO2 and SPo2 was 23%. Despite being on mechanical ventilation, he continued to have hypoxia. With a suspicion of methaemoglobinaemia, blood samples were sent for methaemoglobin level. Blood methaemoglobin was 13%. The patient was immediately started on injection methylene blue and injection ascorbic acid. Two sessions of haemoperfusion and one session of exchange transfusion were done. He started to improve clinically on day 3. He was gradually weaned off the mechanical ventilator and was discharged in the stable condition after 3 weeks of in hospital stay.

Real-world safety and effectiveness of inhaled nitric oxide therapy for pulmonary hypertension during the perioperative period of cardiac surgery: a post-marketing study of 2817 patients in Japan

ObjectiveTo evaluate the real-world safety and effectiveness of inhaled nitric oxide (INOflo® for Inhalation 800 ppm) for perioperative pulmonary hypertension associated with cardiac surgery in Japan.MethodsThis was a prospective, non-interventional, all-case, post-marketing study of pediatric and adult patients who received perioperative INOflo with cardiac surgery from November 2015–December 2020. Safety and effectiveness were monitored from INOflo initiation to 48 h after treatment completion or withdrawal. Safety outcomes included adverse drug reactions, blood methemoglobin concentrations, and inspired nitrogen dioxide concentrations over time. Effectiveness outcomes included changes in central venous pressure among pediatrics, mean pulmonary arterial pressure among adults, and the partial pressure of arterial oxygen/fraction of inspired oxygen ratio (PaO2/FiO2) in both populations.ResultsThe safety analysis population included 2,817 Japanese patients registered from 253 clinical sites (pediatrics, n = 1375; adults, n = 1442). INOflo was generally well tolerated; 15 and 20 adverse drug reactions were reported in 14 pediatrics (1.0%) and 18 adults (1.2%), respectively. No clinically significant elevations in blood methemoglobin and inspired nitrogen dioxide concentrations were observed. INOflo treatment was associated with significant reductions in both central venous pressure among pediatrics and mean pulmonary arterial pressure among adults, and significant improvements in PaO2/FiO2 among pediatrics and adults with PaO2/FiO2 ≤ 200 at baseline.ConclusionsPerioperative INOflo treatment was a safe and effective strategy to improve hemodynamics and oxygenation in patients with pulmonary hypertension during cardiac surgery. These data support the use of INOflo for this indication in Japanese clinical practice.

Congenital Methemoglobinemia: Thinking Out of a Blue Box

Though cyanosis in a new-born baby is very common in many congenital heart diseases, one of the causes of congenital cyanosis is congenital methemoglobinemia, which is a very rare entity. We are reporting a case of a 19-day-old male newborn who presented with complaints of increased frequency of stool, irritability, cyanosis, and tachypnea. Eventually, he was diagnosed with congenital methemoglobinemia based on his blood methemoglobin level, which was 6.5% of total hemoglobin, and successfully treated with intravenous methylene blue at 2 mg/kg. We discuss the importance of this rare case in the differential diagnosis of congenital cyanosis.

Acquired Methemoglobinemia in the Surgical Intensive Care Unit.

Acquired methemoglobinemia is a potentially lethal medical condition caused by exposure to oxidizing xenobiotics, including antibiotics such as dapsone and inhaled anesthetics such as benzocaine. In this case report, we describe two presentations of acquired methemoglobinemia which presented to our surgical intensive care unit within one month. This highlights the potential connection between an emergent surgery or procedure and the development of methemoglobinemia in an environment where it is presumed that this condition would be extremely rare. High clinical suspicion for methemoglobinemia is warranted if the patient develops cyanosis or a decreased oxygen saturation unresponsive to supplemental oxygen when another etiology is not identifiable. If methemoglobinemia is suspected, a direct measurement of blood methemoglobin levels can be obtained to confirm the diagnosis. Prompt treatment with intravenous methylene blue is highly effective.

Performance, Methane Emission, Nutrient Utilization, and the Nitrate Toxicity of Ruminants with Dietary Nitrate Addition: A Meta-analysis from In Vivo Trials

This study aims to evaluate the effects of dietary nitrate addition on performance, methane emission, nutrient utilization, and the nitrate toxicity of ruminants by using the meta-analysis methodology from in vivo trials. A total of 38 published papers and 139 studies were used. Parameters observed were feed intake, animal performance, enteric methane emission, and nitrate toxicity. Data were subjected to the mixed model methodology. Nitrate doses or forms were treated as fixed factors, while the different studies were treated as random factors. Results revealed that nitrate supplementation significantly decreased the milk protein content, milk fat content, dry matter intake, gross energy intake, the molar proportion of the propionic acid, methane production, and the metabolism of vitamin A in a linear pattern (p<0.05). Moreover, nitrate addition significantly increased nitrate intake, the molar proportion of the acetic acid, the ratio of acetic acid to propionic acid, hydrogen molecule production, microbial protein synthesis, and nitrite blood levels (p<0.05). However, treatments did not affect the milk yield, final body weight, nitrate retention, and blood methemoglobin. There was a significant interaction among the animal types and the nitrate (forms and doses) on the milk protein content, dry matter intake, rumen pH value, total volatile fatty acids, the molar proportion of propionic acid, NH3 concentration, H2 molecule, microbial protein synthesis, metabolism of vitamin A, and the blood methemoglobin. This concludes that nitrate supplementation is an alternative feed additive for mitigating the enteric methane in ruminants without any adverse effects on animals’ health or performance despite its impact on the feed consumption rate.

The emerging trend of suicide using nitrite/nitrate in Victoria, Australia

Over the last 18 months the ingestion of nitrite/nitrate salts as a method of suicide has drastically increased, with a single case identified in 2017 and eight in 2019. Inorganic salts can be difficult to detect using standard instrumental methods regularly used in a forensic toxicology laboratory. Ingestion of nitrite/nitrate salts can directly oxidise haemoglobin to methaemoglobin (MetHb) and lead to methemoglobinemia (elevated met-haemoglobin). Methaemoglobinemia occurs within 1 h of consumption leading to severe tissue hypoxia. MetHb is subject to significant changes postmortem and testing of a blood sample in suspected cases must be conducted promptly. Detection of raised MetHb is non-specific but can be an indicator of nitrate/nitrite consumption. This study reviewed cases suspected of nitrite/nitrate poisoning in an attempt to identify common characteristics that can assist in identifying the cause of death in other suspected cases. Cases were initially identified from Police reports where either sodium nitrite or sodium nitrate salt was present at the scene of the incident. These cases were referred for testing in a specialised laboratory able to conduct nitrite/nitrate analysis in blood and when available urine and stomach contents. Briefly, samples were diluted with deionised water and analysed using flow injection analysis/ion chromatography on a Metrohm Compact IC comparing nitrate/nitrite levels. Blood methaemoglobin levels were measured using co-oximetry in all cases with a suitable postmortem blood sample. The concentrations of nitrite and nitrate in blood, urine or stomach contents were significantly higher in cases suspected of nitrite/nitrate consumption when compared to endogenous baseline levels. Blood concentrations for nitrite ranged from 135–230 mg/L (normal range < 0.2–10.9 mg/L) and for nitrate, 180 to 750 mg/L (normal range 14–115 mg/L). While nitrate is naturally converted to nitrate endogenously, cases involving sodium nitrate ingestion showed a higher proportion of nitrate in stomach contents. Only 5 of the 14 cases had a blood sample suitable for MetHb analysis, with results ranging from 8 to 14% (baseline level < 1.5%). Timely information provided in case circumstances is critical in enabling the collection and testing of samples in suspected nitrite/nitrate poisonings where these cases may otherwise be overlooked and remain undetected. The presence of nitrite/nitrate at elevated concentrations and in addition to raised MetHb may indicate a likely cause of death in the absence of other possible factors.

Analysis of Acute Nitrite Exposure on Physiological Stress Response, Oxidative Stress, Gill Tissue Morphology and Immune Response of Large Yellow Croaker (Larimichthys crocea).

Simple SummaryFish are vulnerable to nitrite stress and display variations in physiologic parameter and stress response. In this study, the effects of nitrite on the stress response of large yellow croaker were evaluated. Large yellow croaker were exposed to four (i.e., 0, 29.36, 58.73, and 88.09 mg/L) nitrite concentrations for 48 h. The results of this study indicated that nitrite exposure could induce oxidative stress in the gills and serum of large yellow croaker. The result of immunoglobulin and lysozyme levels indicated that nitrite exposure could cause an immune response in large yellow croaker. In addition, nitrite stress changed the morphology of the gill of large yellow croaker.Nitrite is a common pollutant in aquaculture water, and nitrite toxicity that negatively affects aquatic species is common in aquaculture systems when the water quality is low. Therefore, the present research aimed to evaluate the effect of acute nitrite exposure on the hematological parameters, antioxidant enzymes, immune response, and gill morphology of large yellow croaker (Larimichthys crocea). The fish were randomly separated and exposed to four (i.e., 0, 29.36, 58.73, and 88.09 mg/L) nitrite concentrations for 48 h. The fish blood and gills were collected at 0, 12, 24, 36, and 48 h of nitrite exposure for further analysis. In hematological parameters, the results showed that the levels of hemoglobin, triglyceride, and total cholesterol in blood significantly decreased (p < 0.05) in all nitrite-treated samples after 12 h, while the contents of methemoglobin in blood significantly increased (p < 0.05) in these treatments. After 48 h of nitrite exposure, the levels of cortisol in serum showed a 94.5%, 132.1%, and 165.6% increase in fish exposed to 29.36, 58.73, and 88.09 mg/L nitrite, respectively. The nitrite (i.e., 29.36, 58.73, and 88.09 mg/L) exposure significantly increased (p < 0.05) the levels of antioxidant enzymes (i.e., catalase and glutathione) in the gill and serum after 12 h of exposure compared with the control. The lysozyme levels in serum decreased in the nitrite (i.e., 29.36, 58.73, and 88.09 mg/L) exposure samples. It was found that immunoglobulin levels in the 29.36, 58.73, and 88.09 mg/L nitrite-treated samples (i.e., 1.86, 1.58, and 0.74 μg/mL, respectively) were lower than that of the control (2.56 μg/mL). In addition, the surface of the gill lamellae displayed deformation and contraction after 48 h of nitrite, especially in the fish exposed to 88.09 mg/L nitrite. These results indicate that the nitrite exposure induced the oxidative stress, affected the immune response, and changed the gill morphology, leading to nitrite poisoning in large yellow croaker.

Assessment of Severity of Methaemoglobinemia Following Fibreoptic Bronchoscopy with Lidocaine

Lidocaine is commonly used for topical anaesthesia during fibreoptic bronchoscopy (FOB) and it can cause methaemoglobinemia. The present study was undertaken to evaluate the severity of post-bronchoscopy methaemoglobinemia while using lidocaine as a topical anaesthetic agent. We prospectively studied consecutive adult patients who underwent diagnostic FOB in our institution. Blood methaemoglobin levels were estimated by co-oximetry before bronchoscopy and one hour after first instillation of lidocaine. Occurrence of symptoms suggestive of mild methaemoglobinemia (i.e., fatigue, palpitation, dizziness, nausea and headache) were recorded in a severity scale before collection of post-bronchoscopy blood samples. A total of 48 adult patients were enrolled in this study. The mean amount of lidocaine used for bronchoscopy during this study was 7.4 +/- 1.4 mg/kg body weight. The mean pre- and post-bronchoscopy methaemoglobin levels were 0.44 mg/mL and 0.80 mg/mL, respectively. After bronchoscopy, severe and very severe symptoms were reported by 2.1% to 10.4% patients. However, severities of the symptoms were unrelated to post-bronchoscopy methaemoglobin level or the amount of lidocaine used during the FOB. Blood methaemoglobin levels following FOB remained within the physiological limits when British Thoracic Society recommended dose of lidocaine was used. However, few patients had symptoms similar to mild methaemoglobinemia after FOB.

Effect of a Phytogenic Feed Additive in Preventing Calves' Diarrhea.

The aims of the present study were to evaluate the preventive and the therapeutic effect of Stodi® as phytogenic feed additive rich in phenolic substances on the calf diarrhea, during the first 24 days of life. A total of 40 calves were included and randomly divided into Group C (control group) and Group T (treated group) with placebo or treatment administration started from the third day of life (T0). Calves belonged to group C received 2 L of warm water, while the calves assigned to group T received 2L of warm water plus 30 g of Stodi®. Solutions administration was maintained until day 21 (T21) that was the end of the experimental period. Calves were weighed at T0 and T21 to assess the average daily gain (ADG). Physical examination and fecal score evaluation were performed daily. The duration of a diarrheic episode, the age of the first diarrhea outbreak (TDE) and the frequency of diarrheic episodes were recorded. Complete blood count, methemoglobin and liver enzymes were evaluated at T0 and at T21 in all the calves by spectrophotometer and clinical chemistry analysis, respectively. Data were analyzed using a mixed model. A Chi-square and a Mann-Whitney test were also performed. No difference was found for ADG between the groups. The difference of mean age at TDE was not statistically significant between C and T group. The number of calves with diarrhea in the C group tended to be higher than that of T group (p = 0.13). Calves in group C spent more days with clinical sign of diarrhea compared to group T (p = 0.016). Complete blood count, methemoglobin and liver enzymes were within the reference ranges. The feed additive Stodi® seemed to be effective in shortening neonatal diarrhea episodes in calves thanks to the administration of 30 g per day of product. The fixed dosage of Stodi® used in our study did not show a preventive effect to reduce the incidence of calf diarrhea.

Cyanosis in a Previously Well Child.

Cyanosis in a Previously Well Child.

Review of potential risks associated with supplemental dietary exposure to nitrate-containing compounds in swine-a paradox in light of emerging benefits.

Calcium nitrate has been reported to benefit reproductive outcomes in sows and their offspring when administered via the feed (15 to 19 mg/kg-body weight [bw]/day) during the periparturient period. Traditionally, dietary nitrate had been considered a methemoglobinemia (MetHb) risk in swine. Similar hazard concerns have existed in humans, but a recent benefit/risk analysis established that nitrate levels associated with well-recognized health benefits outweigh potential risks. A similar benefit/risk perspective in swine was lacking and challenged by sparse published hazard data, often referenced within larger reviews related to all livestock. The objective of this review was to better characterize the potential for adverse health and performance effects reported in the literature for swine consuming nitrate and to provide metrics for evaluating the reliability of the studies reviewed. Supplemental exposure via feed or drinking water was considered for any life stage, dose, and exposure duration. More than 30 relevant studies, including case reports and reviews, examined calcium, potassium, sodium, or unspecified nitrate salts at doses up to 1,800 mg nitrate/kg-bw/day for exposures ranging from 1 to 105 d. The studies primarily evaluated weight gain, blood methemoglobin levels, or vitamin A homeostasis in sows or growing swine. An extensive review of the literature showed reports of adverse effects at low nitrate doses to be of low reliability. Conversely, reliable studies corroborate nitrate intake from feed or drinking water at levels equal to or greater than the European Food Safety Authority’s no-observed-adverse-effect level (NOAEL) for swine of 410 mg nitrate/kg-bw/day, with no MetHb or other adverse effects on reproduction, growth, or vitamin A levels. Using a weight-of-evidence evaluation, we have moderate-to-high confidence that the NOAEL for nitrate supplementation in swine is likely between 600 and 800 mg/kg-bw/day. These levels are several-fold higher than dietary nitrate concentrations (19 mg/kg-bw/day) that are known to benefit birth outcomes in sows. This review elucidates the quality and reliability of the information sources historically used to characterize nitrate in swine feed as a contaminant of concern. Results from this evaluation can assist risk managers (e.g., regulatory officials and veterinarians) in consideration of proposed benefits as well as reassuring swine producers that low-level nitrate supplementation is not anticipated to be a concern.

Determination of carboxyhaemoglobin and methaemoglobin levels in donated blood

To determine the percentages of carboxyhaemoglobin (COHb) and methaemoglobin (MeHb) in donor blood and to compare these levels between smokers and nonsmokers at different time points during blood storage. Blood donors were recruited from Haematology Service, University Hospital Alzira Velano, Alfenas-MG. The blood was kept in collecting ducts (noodles) containing citrate, phosphate and dextrose (CPD) and stored at 4°C throughout the storage period. Since the noodles kept the characteristics of the bags, COHb and MeHb levels were analysed on the day of donation and after 20 days of storage. Levels of COHb and MeHb were determined using spectrophotometric methods. Non-parametric Friedman and Mann-Whitney tests were employed to compare COHb and MeHb levels before and after the storage and groups of smokers and nonsmokers, respectively. Levels of COHb and MeHb in the blood collected from smokers and nonsmokers were statistically different (p&lt; 0.05; Mann- Whitney test) when the samples were analyzed before the storage. In blood of smokers, COHb levels were no different over a 20-day storage period (p= 0.7009; Friedman test). On the other hand, MeHb levels were significant different over a 20-day storage period (p&lt; 0.05). The results suggest the need to regularly assess COHb and MeHb levels in donor blood stored in blood banks.

Dose-response effect of encapsulated nitrate replacing soybean meal on growth performance, ingestive behavior, and blood metabolites of feedlot finishing bulls

ABSTRACT This study addressed the dose-response effect of an encapsulated nitrate product (ENP) replacing soybean meal (SBM) in the finishing period (87-d) of feedlot bulls. One hundred twenty Nellore bulls (340 ± 28 kg of body weight, BW; mean ± SD) were allotted to 20 outdoor pens (6 animals/pen) and assigned to a randomized complete block design with 5 blocks based on initial BW and 4 dietary treatments: SBM, as control; ENP-10, 10 g ENP/kg dry matter (DM; 6.5 g NO3−/kg DM); ENP-20, 20 g ENP/kg DM (13 g NO3−/kg DM); and ENP-30, 30 g ENP/kg DM (19.5 g NO3−/kg DM). Finishing diets (90:10 concentrate to roughage ratio) were formulated to provide similar amounts of nutrients. Animals were gradually and simultaneously adapted over 14 d to ENP and concentrate. Dry matter intake (DMI) reduced linearly (from 9.6 to 8.4 kg/d; P = 0.02) with ENP inclusion. Final BW, average daily gain (ADG), carcass ADG, hot carcass weight, dressing percentage, and fat thickness were not affected (P ≥ 0.12) by treatments. There was a quadratic trend for increased carcass gain:feed (0.121, 0.130, 0.128, 0.127, respectively; P = 0.07). Nitrate concentration in meat increased linearly (3.48, 2.73, 3.98, 6.59 mg NaNO3/kg meat; P = 0.02) with ENP addition, although nitrite was not detected. Time spent eating (min/d) was similar (P ≥ 0.16) among treatments, whereas a linear increase (P = 0.02) was observed for time spent eating per unit of DMI when ENP was fed. There was a trend (P = 0.07) for a quadratic effect in ruminating time per unit of DMI according to ENP increments. Blood methemoglobin before morning feeding increased linearly (P

Evaluation of oral administration of chestnut tannins in preventing calf diarrhoea

We evaluated the preventive effects of the oral administration of chestnut tannins (Castanea sativa) together with its potential metabolic effect on calf diarrhoea. Forty Italian Friesian female calves were included and divided into Group C (control group) and Group T (tannin-treated group). From the third day of life (T0) for the following 56 days (T56), calves from Group C received 2 L of warm water, while 10 g of chestnut tannin powder extract were added to Group T. Calves were weighed at birth and at T56. Daily faecal score evaluation was performed according to the literature. The age at diarrhoea onset (TDE) and the duration of the diarrhoeic episode were recorded. Blood methaemoglobin and liver enzymes were evaluated weekly starting from T0 to T56 by spectrophotometer and clinical chemistry analysis, respectively. The t-Student and chi-square tests were performed. The TDE was higher (p = .04) in Group T than in Group C (12.0 ± 8.2 and 7.7 ± 3.8 days, respectively). There were no differences for ADG between the groups. Group C spent 24.4% of the whole period with diarrhoea, whereas Group T experienced diarrhoea for 18.9% of the period (p = .001). All the blood and serum analytes were within physiological values. The administration of tannins in calves from the third day of life seemed to delay the onset of diarrhoea by almost four days, suggesting effective preventive action of chestnut tannins. HIGHLIGHTS The oral administration of chestnut tannins in calves seemed to delay the onset of diarrhoea by almost four days, thus showing a preventive effect. The oral administration of chestnut tannins may lead to a better and shorter recovery of the calf, thus decreasing the use of antibiotics.

Nitrate-nitrite toxicosis associated with duckweed (Portulaca Oleracea L.) (Portulacaceae) consumption in a herd of sheep in Kenya

Background: Nitrate-nitrite toxicosis associated with the consumption of duckweed (Portulaca oleracea L.) (Portulacaceae) was diagnosed in a small herd comprising of 11 sheep in Korayo Sub Location, Rangwe Sub County of Homabay County in Kenya. Methods: The clinical signs were dyspnea, froth from the mouth, labored breathing, incoordination, tachycardia, increased urination, neck, fore and hind limb distension, aggressive movements, bloat, convulsions, and coma, before death. Results: All the 11 sheep died of intoxication before institution of therapy. Brownish mucous membranes and chocolate colored and poorly clotted blood were the significant necropsy observations. Mild pulmonary edema was characterized by the presence of limited froth in the trachea and bronchioles. At postmortem, the liver of the sheep was grossly congested, and the cardiac pericardium was inflamed. There was gastritis, enlarged, and congested kidneys with pin-point hemorrhages. Diphenylamine tests carried out on the fed duckweed and on ruminal duckweed contents were positive for nitrates. Duckweed (Portulaca oleracea) fed on sheep had 7.4% nitrate on dry matter basis (DM), whereas ruminal contents had 5.38% nitrate on DM basis. Chocolate-colored blood collected during postmortem had a methemoglobin fraction of 86%. Nitrate levels in pastures of 0.5% and above have been shown to be potentially dangerous, with acute poisoning likely to occur at times when the levels are above 1%. Death in sheep can occur when blood methemoglobin levels are in the range of 67%–90%. Conclusion: The observations from the present study are indicative of death in a herd of sheep due to nitrate-nitrite poisoning associated with the consumption of duckweed (Portulaca oleracea).

The effect of molasses nitrate lick blocks on supplement intake, bodyweight, condition score, blood methaemoglobin concentration and herd scale methane emissions in Bos indicus cows grazing poor quality forage

Context The Australian government has approved a greenhouse gas (GHG) offset method that requires cattle to consume nitrate in the form of a lick block. Field studies demonstrating the effectiveness of this methodology have not been previously reported. Aims This experiment was conducted to determine the effects on productivity and health when nitrate lick blocks were provided as a supplement to grazing beef cattle. We hypothesised that beef cattle given access to nitrate lick blocks would have similar productivity compared with cattle offered urea lick blocks. Methods Bos indicus breeding cows (n = 76) grazed a 467-ha paddock near Charters Towers, Queensland, between May and November 2014. A two-way remote automatic drafting system enabled allocation of cattle to different treatments while grazing in a common paddock. Treatments were 30% urea lick blocks (30U), or molasses nitrate lick blocks (MNB). At monthly intervals liveweight (LW), body condition score (BCS), and blood methaemoglobin concentration were recorded. Estimates of individual supplement intake were made on three separate occasions using a lithium marker technique. Results Mean daily supplement intake (±s.e.m.) of 30U (122 ± 13 g) was greater (P &amp;lt; 0.001) than MNB (67 ± 8 g). Lesser MNB intake was associated with greater variability for individual supplement intake, a greater proportion of non-consumers of supplement during July (P &amp;lt; 0.05) and reduced voluntary supplement intake until October (P &amp;lt; 0.001). Increasing MNB consumption during October and November was accompanied by elevated blood methaemoglobin concentration (P &amp;lt; 0.001). It was estimated that cattle offered MNB had insufficient supplementary nitrogen intake throughout the study to resolve rumen degradable nitrogen deficiency from grazed forage. Consequently, cattle provided access to MNB demonstrated conceptus free liveweight loss and lesser BCS compared with cattle treated with 30U (P &amp;lt; 0.001). Conclusion Nitrate lick blocks were ineffective as a dual-purpose non-protein nitrogen supplement and methane mitigant for beef cattle grazing poor quality forage. Further field experiments are required to determine if there may be situations where this GHG offset methodology is efficacious. Implications Caution is advised in implementing GHG mitigation methods that involve the use of nitrate lick blocks.

P1052ASUPPRESSION OF BLOOD COAGULATION ON THE SURFACE OF A DIALYSIS MEMBRANE USING A DIALYSATE CONTAINING 800 PPM OF NITRIC OXIDE

Abstract Background and Aims Activation of platelets and leukocytes when blood comes in contact with a dialysis membrane surface leads to increased oxidative stress and release of proinflammatory cytokines, which may result in complications in dialysis patients. Within the blood vessels, nitric oxide (NO) generated by nitric oxide synthase on the endothelial cells suppresses both aggregation/activation of platelets and migration/adhesion of leukocytes. We previously showed in a rat hemodialysis model that NO (800 ppm) gas added to the dialysate can suppress blood coagulation on the surface of a dialysis membrane. The aim of the present study was to determine, using a rat hemodialysis model, the appropriate concentration of NO that would most effectively prevent blood coagulation without causing any adverse effects. Method Male Sprague Dawley rats weighing 300 to 400 g were used for the experiments. After the rats were anesthetized (isoflurane, 1.5%-3.0%), extracorporeal circulation was established by removal of blood from the carotid artery and returning it to the tail vein. During the experiment, the blood flow rate was kept at 1.0 mL/min, and the dialysate flow rate at 3 mL/min. Heparin was administered by bolus injection (0.7 unit/g-mouse) at the start of the hemodialysis, and no further heparin was added during the 4-hour hemodialysis session. A cellulose triacetate membrane and polymethylpentene membrane were used for making the small dialyzer and gas exchanger, respectively (the prototype module was manufactured by NIPRO, Co., Japan). NO (200 ppm, 400 ppm, or 800 ppm) was added to the dialysate via the gas exchanger in the NO groups, and N2 gas was added to the dialysate in the control group. During the experiment, the arterial pressure, dialyzer inlet pressure, venous pressure, activated whole blood clotting time (ACT) and methemoglobin (met-Hb) concentration were measured. After circulation, the amount of coagulated blood was measured by the hemoglobin (Hb) content and lactate dehydrogenase (LDH) activity in the eluate from the residual blood clotting in the dialyzer. Results The 4-hour hemodialysis session achievement rate was highest in the NO-800 ppm group (control, 54%; NO-200 ppm, 66%; NO-400 ppm, 77%; NO-800 ppm, 85%). The blood met-Hb content was below 10% in all the NO groups. The Hb content and LDH activity in the eluate were significantly lower in the NO groups than in the control group. These results indicate that addition of higher concentrations of NO was associated with a lower likelihood of coagulation on the dialyzer and in the dialysis circuit and a higher likelihood of smooth and successful 4-hour dialysis sessions. Addition of NO was associated with little risk of adverse effects such as met-Hb accumulation and reduction of blood pressure. Therefore, 800 ppm is considered as the most appropriate concentration of NO to be added to the dialysate for effectively inhibiting blood coagulation without causing any adverse effects. Conclusion Our experiment in a rat hemodialysis model showed that 800 ppm was the most appropriate concentration of NO to be added to the dialysate to suppress blood coagulation on the surface of the dialysis membrane without causing any adverse effects.

A Rare Case of Congenital Methemoglobinemia with secondary polycythemia- Case Report and Literature Review

Congenital heart diseases are common cause of congenital cyanosis with polycythaemia. Congenital methemoglobinemia is a rare cause of lifelong cyanosis with polycythemia. Congenital methemoglobinemia is caused either by enzyme deficiency or by an abnormal Hb (Hb M). Asymptomatic despite presence of severe cyanosis indicates this rare disorder. We are reporting a rare case of polycythemia with cyanosis due to congenital methemoglobinemia. The patient was referred to our centre and attended Hematology OPD (out-patient department) when his routine CBC revealed erythrocytosis. At that time, we found him severely cyanosed especially apparent on lips, tongue, hands and feet. He was diagnosed as a case of congenital methemoglobinemia with 38% blood methemoglobin level (normal value-0.00-2.00%). On view of life long persistent cyanosis, without any cardiopulmonary and neurological abnormality, consanguinity of parent’s marriage, dark colored blood with high methemoglobin level, a final diagnosis of Type I enzyme deficiency congenital methemoglobinemia was made. He was treated with oral ascorbic acid 250 mg twice daily. At follow up after 6 months his skin color improved and RBC count returned to normal. We are reporting this case of congenital methemoglobinemia for the first time in Bangladesh to emphasize the importance of this rare entity in the differential diagnosis of asymptomatic cyanosis with polycythemia.

Resuscitation with macromolecular superoxide dismutase/catalase mimetic polynitroxylated PEGylated hemoglobin offers neuroprotection in guinea pigs after traumatic brain injury combined with hemorrhage shock

BackgroundPolynitroxylated PEGylated hemoglobin (PNPH, aka SanFlow) possesses superoxide dismutase/catalase mimetic activities that may directly protect the brain from oxidative stress. Stabilization of PNPH with bound carbon monoxide prevents methemoglobin formation during storage and permits it to serve as a carbon monoxide donor. We determined whether small volume transfusion of hyperoncotic PNPH is neuroprotective in a polytrauma model of traumatic brain injury (TBI) plus hemorrhagic shock. Guinea pigs were used because, like humans, they do not synthesize their own ascorbic acid, which is important in reducing methemoglobin.ResultsTBI was produced by controlled cortical impact and was followed by 20 mL/kg hemorrhage to a mean arterial pressure (MAP) of 40 mmHg. At 90 min, animals were resuscitated with 20 mL/kg lactated Ringer’s solution or 10 mL/kg PNPH. Resuscitation with PNPH significantly augmented the early recovery of MAP after hemorrhagic shock by 10–18 mmHg; whole blood methemoglobin was only 1% higher and carboxyhemoglobin was 2% higher. At 9 days of recovery, unbiased stereology analysis revealed that, compared to animals resuscitated with lactated Ringer’s solution, those treated with PNPH had significantly more viable neurons in the hippocampus CA1 + 2 region (59 ± 10% versus 87 ± 18% of sham and naïve mean value) and in the dentate gyrus (70 ± 21% versus 96 ± 24%; n = 12 per group).ConclusionPNPH may serve as a small-volume resuscitation fluid for polytrauma involving TBI and hemorrhagic shock. The neuroprotection afforded by PNPH seen in other species was sustained in a species without endogenous ascorbic acid synthesis, thereby supporting potential translatability for human use.