Dihydrotanshinone I reduces H9c2 cell damage by regulating AKT and MAPK signaling pathways

Cardiovascular disease is the deadliest disease in the world. Previous studies have shown that Dihydrotanshinone I (DHT) can improve cardiac function after myocardial injury. This study aimed to observe the protective effect and mechanism of DHT on H9c2 cells by establishing an oxygen-glucose deprivation/reoxygenation (OGD/R) injury model. By constructing OGD/R injury simulation of H9c2 cells in a myocardial injury model, the proliferation of H9c2 cells treated with DHT concentrations of 0.1 μmol/L were not affected at 24, 48, and 72 h. DHT can significantly reduce the apoptosis of H9c2 cells caused by OGD/R. Compared with the OGD/R group, DHT treatment significantly reduced the level of MDA and increased the level of SOD in cells. DHT treatment of cells can significantly reduce the levels of ROS and Superoxide in mitochondria in H9c2 cells caused by OGD/R and H2O2. DHT significantly reduced the phosphorylation levels of P38MAPK and ERK in H9c2 cells induced by OGD/R, and significantly increased the phosphorylation levels of AKT in H9c2 cells. DHT can significantly reduce the oxidative stress damage of H9c2 cells caused by H2O2 and OGD/R, thereby reducing the apoptosis of H9c2 cells. And this may be related to regulating the phosphorylation levels of AKT, ERK, and P38MAPK.

Electroacupuncture improves cardiac function after myocardial infarction by regulating the mobilization and migration of endogenous stem cells

OBJECTIVE

The aim of this study was to explore the role and mechanisms of electroacupuncture (EA) in the regulation of chemokines in endogenous stem cell mobilization and myocardial regeneration after myocardial infarction (MI).

METHODS

An MI model was constructed in adult male Sprague-Dawley rats by ligating the left anterior descending coronary artery. After 4 weeks of treatment, echocardiography was used to detect changes in cardiac function, and Masson's trichrome staining was used to detect collagen deposition. In addition, immunofluorescence staining was applied to examine von Willebrand factor (vWF)-positive vessels, the expression of cardiac troponin T (cTnT) and proliferation marker Ki67, and the number of c-kit-positive, C-X-C chemokine receptor type 4 (CXCR4)-positive, and Sca-1-positive endogenous stem cells in the infarcted area. In addition, the expression of stromal cell-derived factor (SDF)-1 and stem cell factor (SCF) was detected.

RESULTS

EA increased the ejection fraction after MI, reduced collagen deposition and cellular apoptosis, and increased the number of blood vessels compared with an untreated model group. EA significantly promoted cellular proliferation, except for myocardial cells, and significantly increased the number of c-kit-, CXCR4- and Sca-1-positive stem cells. Moreover, the expression of SDF-1 and SCF in myocardial tissue in the EA group was significantly higher than that in the (untreated) MI group.

CONCLUSIONS

EA appears to promote angiogenesis and reduce collagen deposition, thus improving the cardiac function of rats with MI. The underlying mechanism of action may involve endogenous stem cell mobilization mediated by SDF-1/CXCR4 and SCF/c-kit.

[Preliminary application of postoperative fast track transfer to intensive care unit for the geriatric hip fractures under enhanced recovery after surgery]

Objective: To develop a fast track transfer to intensive care unit (ICU) for the perioperative high-risk elderly patients after hip fracture surgery and analyze the preliminary clinical effect of the application. Methods: From January 2014 to December 2017, before the application of postoperative fast track transfer to ICU, the clinical data of 195 elderly patients with hip fracture were included in a retrospective analysis. Among 195 hip fracture patients, 18 were transferred to ICU post operation (non-fast track group). Multivariate logistic regression analysis was applied to investigate relevant risk factors for transferring to ICU after hip fracture surgery. Based on risk factors acquired from the analysis and clinical experience, the fast track transfer to ICU for the perioperative high-risk elderly patients after hip fracture surgery was constructed according to the preliminary and experiential criteria. From January 2018 to December 2019, the clinical data of 70 patients (fast track group) who were transferred to ICU after hip fracture surgery through the fast track were collected and compared with non-fast track group. Results: Multivariate regression analysis revealed that American Society of Anesthesiologists classification(≥Ⅲ) (OR=4.260, 95%CI:1.157-15.683, P=0.029), pre-hospital stage (≥48 h) (OR=4.301, 95%CI:1.212-15.266, P=0.024), hemoglobin concentration at admission(<90 g/L) (OR=7.979, 95%CI:1.936-32.889, P=0.004), coronary heart disease as one comorbidity(OR=6.063, 95%CI:1.695-21.693, P=0.006) were independent risk factors for transferring to ICU after hip fracture surgery. There were no significant difference in gender, age, fracture type, hemoglobin concentration at admission and time of pre-hospital stage between the non-fast track group and fast track group(all P>0.05). However, the number of comorbidities in the fast track group was significantly higher than that in the non-fast track group (Z=-1.995, P=0.046). The time to surgery, postoperative hospital stay, and length of hospital stay in fast track group were all significantly less than those in non-fast track group (Z=-2.121, -2.726, -3.130, all P<0.05). Also, there were fewer medical consultations needed and fewer patients who stayed in ICU more than or equal to 2 nights in fast track group than that in non-fast track group(all P<0.05). There were no significant difference in the rate of patients who transferred from the general ward to ICU after transferring from ICU to the general ward, the proportion of patients who received more than or equal to 4 departments, operation time, hospitalization expense, mortality during hospitalization, 30-day mortality and 90-day mortality after operation between the two groups(all P>0.05). Conclusions: The fast track constructed in this study can reduce time to surgery, postoperative hospitalization stay and length of hospitalization stay for the perioperative high-risk elderly patients with hip fractures and is a specific clinical application of eras concept based on multidisciplinary team.

[Study on the related factors of esophageal cancer and precancerous lesions in rural residents aged 40-69 years in Shandong Province]

Objective: To analyze the related factors of esophageal squamous cell carcinoma and precancerous lesions among residents aged 40-69 years old in rural areas of Shandong Province. Methods: In October 2018, 300 villages in 13 counties of the Shandong upper gastrointestinal cancerearly diagnosis and treatment projectin 2017 were selected as research areas, and 30 400 residents aged 40-69 were recruited in this study. The demographic characteristics, health status and lifestyle information were collected through the questionnaire survey, and endoscope iodine staining and indicative biopsy methods were used for cancer screening among eligible people.The multivariate logistic regression model was used to analyze the risk factors for esophageal cancer and precancerous lesions. Results: The subjects in this study were (56.42±7.24) years old, including 13 193 males (43.40%).There were 936 cases of esophageal cancer and precancerous lesions (3.08%), including 521 males and 415 females.Compared with women, 40-49 years old, high level education, drinking tap water, regular intake of meat, eggs and milk, and family average annual income more than 30 000 RMB, men (OR=1.90, 95%CI: 1.65-2.19), 60-69 years old (OR=5.28, 95%CI: 4.11-7.30), primary school education or below (OR=1.50, 95%CI: 1.20-1.89), drinking groundwater (OR=1.71, 95%CI: 1.38-2.13), never eating meat, eggs and milk (OR=1.48, 95%CI: 1.22-1.80), and family average annual income less than 30 000 RMB (OR=1.41, 95%CI: 1.16-1.70) would increase the risk of esophageal cancer and precancerous lesions. Conclusion: The gender, age, educational level, annual household income, drinking water source, the frequency of eating meat, egg and milk were related to the occurrence of esophageal cancer and precancerous lesions among 40-69 years old residents in rural areas of Shandong Province.

Electroacupuncture and moxibustion promote regeneration of injured sciatic nerve through Schwann cell proliferation and nerve growth factor secretion

Using electroacupuncture and moxibustion to treat peripheral nerve injury is highly efficient with low side effects. However, the electroacupuncture- and moxibustion-based mechanisms underlying nerve repair are still unclear. Here, in vivo and in vitro experiments uncovered one mechanism through which electroacupuncture and moxibustion affect regeneration after peripheral nerve injury. We first established rat models of sciatic nerve injury using neurotomy. Rats were treated with electroacupuncture or moxibustion at acupoints Huantiao (GB30) and Zusanli (ST36). Each treatment lasted 15 minutes, and treatments were given six times a week for 4 consecutive weeks. Behavioral testing was used to determine the sciatic functional index. We used electrophysiological detection to measure sciatic nerve conduction velocity and performed hematoxylin-eosin staining to determine any changes in the gastrocnemius muscle. We used immunohistochemistry to observe changes in the expression of S100—a specific marker for Schwann cells—and an enzyme-linked immunosorbent assay to detect serum level of nerve growth factor. Results showed that compared with the model-only group, sciatic functional index, recovery rate of conduction velocity, diameter recovery of the gastrocnemius muscle fibers, number of S100-immunoreactive cells, and level of nerve growth factor were greater in the electroacupuncture and moxibustion groups. The efficacy did not differ between treatment groups. The serum from treated rats was collected and used to stimulate Schwann cells cultured in vitro. Results showed that the viability of Schwann cells was much higher in the treatment groups than in the model group at 3 and 5 days after treatment. These findings indicate that electroacupuncture and moxibustion promoted nerve regeneration and functional recovery; its mechanism might be associated with the enhancement of Schwann cell proliferation and upregulation of nerve growth factor.

[Immunotherapy of non-Hodgkin's lymphomas (NHL) by anti-CD22 antibody--review]

CD22 is a transmembrane sialoglycoprotein and a member of the immunoglobulin superfamily. Its expression is restricted to the B cell lineage and a vast majority of B cell NHLs. CD22 plays a key role in B cell development, survival, and function. Humanized anti-CD22 antibodies were developed to minimize the immunogenicity and to enhance effector interactions during their developments of diagnostic and immunotherapeutic agent. Preclinical test with anti-CD22 antibodies indicates that a single, conjugated or radiolabeled agent has shown preliminary antitumor activity in patients with recurrent and heavily pretreated NHL. Anti-CD22 antibodies were well tolerated, without dose-dependant toxicity. Anti-CD22 antibodies are currently being evaluated in combination with rituximab, and the early results suggest that the combination of the two antibodies are well tolerated and may result in better clinical activity than the single agent alone. Thus, anti-CD22 antibodies are theoretically good candidates alone and in combination with other drugs in the treatment of B cell malignancies. In this review, the physiologic function and characteristics of CD22 antigen as target molecule of guide therapy for NHL, the types of anti-CD22 antibodies in therapy of NHL and the combination use with other antibodies were summarized.

ProSeal versus the Classic laryngeal mask airway for positive pressure ventilation during laparoscopic cholecystectomy

BACKGROUND

We tested the hypothesis that the ProSeal laryngeal mask airway (PLMA) is a more effective ventilatory device than the Classic laryngeal mask airway (LMA) for laparoscopic cholecystectomy.

METHODS

Eighty anaesthetized, paralyzed patients (ASA 1-2, aged 18-80 yr) were randomly allocated for airway management with the PLMA or LMA. Ease of insertion and efficacy of seal were determined. Peak airway pressures were recorded immediately before and after carboperitoneum to 2.0 kPa. The inspired oxygen concentration and/or the ventilatory variable were adjusted according to a protocol to maintain SpO2 > or = 95% and E'CO2 < 6.0 kPa. Oxygenation was considered suboptimal if SpO2 fell to 94-90% and failed if SpO2 was < 90%. Ventilation was considered suboptimal if E'CO2 was > 6.0-7.3 kPa and failed if E'CO2 was > 7.3 kPa.

RESULTS

First-time insertion success rates were higher for the LMA (40/40 vs 33/40; P = 0.02). Seven patients required two attempts with the PLMA. Oropharyngeal leak pressure was higher for the PLMA [29 (SD 6) vs 19 (4) cm H2O; P < 0.001]. There was a similar, significant increase in peak airway pressure after carboperitoneum for both devices (P < 0.001). Before carboperitoneum, oxygenation and ventilation were optimal in all patients in both groups. After carboperitoneum, oxygenation was optimal in all patients in both groups, but ventilation was suboptimal more frequently with the LMA (8 vs 0; P = 0.01). In three of these eight patients, ventilation failed but was subsequently optimal with the PLMA.

CONCLUSION

The PLMA is a more effective ventilatory device for laparoscopic cholecystectomy than the LMA. We do not recommend the use of the LMA for laparoscopic cholecystectomy.

The intubating laryngeal mask airway in severe ankylosing spondylitis

PURPOSE

To evaluate the use of inhalational induction followed by intubation through the intubating laryngeal mask (ILM) for patients with severe ankylosing spondylitis undergoing elective surgery who prefer airway management under anesthesia.

METHODS

Nine patients undergoing a total of 11 procedures were enrolled in the study. Fentanyl 2 microg*kg(-1), midazolam 0.035 mg*kg(-1) and sevoflurane in oxygen 100% were used for induction. The ILM was inserted when the end-tidal sevoflurane concentration reached 3%. After an effective airway was established, atracurium 0.5 mg*kg(-1) was given. A polyvinyl chloride tube in the reversed position using a blind technique was used to intubate the trachea.

RESULTS

The ILM provided an effective airway on 11/11 occasions at the first attempt. Intubation was successful at the first attempt on 7/11 occasions, at the second attempt on 2/11 and at the third attempt in 1/11. Intubation failed in one patient. The mean (range) minimal oxygen saturation was 99.4% (97-100%). There were no problems with ILM removal.

CONCLUSION

Inhalational induction followed by ILM insertion and blind intubation is a reasonable option in patients with severe ankylosing spondylitis undergoing elective surgery who prefer airway management under anesthesia.

The intubating LMA: a comparison of insertion techniques with conventional tracheal tubes

PURPOSE

To compare the performance of the intubating laryngeal mask airway (ILMA) in assisting blind tracheal intubation with conventional tracheal tubes of different curvatures and the frequency of possible associated complications.

METHODS

After informed consent, 240 ASA I-II adults undergoing elective surgery participated in a randomized, single blind clinical trial to receive blind trachea intubation via ILMA with a conventional tracheal tube curved with normal (Normal group) or reversed (Reverse group) direction. More than three attempts at intubation was regarded as failure. The lowest oxygen saturation during intubation was recorded and postintubation sore throat and hoarseness were evaluated with verbal analog scales.

RESULTS

The overall success rates of intubation with Normal and Reverse groups were not different (96.7% and 94.2% respectively). Successful intubation at the first attempt was higher in the Reverse group than in the Normal group (86.7% vs 75.0%, P=0.033). The incidence of sore throat was higher in the Normal group than in the Reverse group (19.2% vs 9.2% respectively, P =0.042).

CONCLUSIONS

Blind trachea intubation via an ILMA with the conventional curved tracheal tube is feasible and highly successful. Reverse curve direction is preferable at the first attempt of intubation for its higher success rate and lower incidence of complications.

An Enzyme-Bound Bisubstrate Hybrid Inhibitor of Adenylosuccinate Synthetase

Two relatively weak herbicides, hydantocidin phosphate and hadacidin were linked by a C(3) chain to afford a potent inhibitor (the 2S hybrid is shown) of the enzyme adenylosuccinate synthetase. The crystal structures of the bisubstrate-enzyme complexes were determined.

Spinal nitric oxide participates in the control of the blood pressure during graded hemorrhage in the conscious rat

We sought to evaluate the role of spinal nitric oxide (NO) in the control of blood pressure in the conscious animal and determine its possible participation in the progression of hemorrhagic shock. Adult, male Sprague-Dawley rats were chronically prepared with intrathecal, intravenous, and intra-arterial catheters. We first investigated the role of spinal NO on blood pressure control by intrathecal administration of N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME) at 0.37 micromol, 0.74 micromol. or 1.48 micromol. A dose-related increase in blood pressure was observed. We next pretreated animals with intrathecal or intravenous L-NAME at 0.37 micromol and induced the animal to shock by graded hemorrhage. Animals that received vehicle control or intravenous L-NAME had a decrease in blood pressure after 12% of the total circulatory blood volume (TBV) had been removed and developed severe hypotension after 24% TBV was bled. On the other hand, intrathecal pretreatment of L-NAME significantly attenuated the decrease in blood pressure. The blood pressure was maintained until 40% TBV had been withdrawn. We concluded that inhibition of NO synthase, in the spinal cord, increased blood pressure in a dose-dependent manner, and hemorrhagic shock induced by graded hemorrhage may involve an upregulation mechanism of spinal NO synthase in producing severe hypotension in conscious rats.

Dynamic measurement of metabolic function in the rat liver: an application of reverse microdialysis

BACKGROUND

Traditional markers of liver function and microsomal activity tests require regular samplings and tissue removal. The microdialysis technique is a promising tool for pharmacokinetic study without the need for actually removing samples of those tissues and fluids. We verified the possibility of using reverse microdialysis for dynamic monitoring of hepatic metabolic function.

METHODS

Adult male Sprague-Dawley rats were used and anesthetized using pentobarbital sodium. Reverse microdialysis was done by implanting a microdialysis probe into the middle lobe of the liver; the probe was then perfused with a lidocaine-containing solution. Concentrations of lidocaine and its major metabolite, monoethylglycinexylidide (MEGX), were measured in the dialysate. Metabolic ability was assessed by dividing the MEGX production by lidocaine administration. Hepatic ischemia-reperfusion and liver cirrhosis models were used to verify its application in dynamic measurement of liver metabolic function.

RESULTS

The implantable microdialysis probe had stable contact with the liver tissue. In normal rats, 4.73 +/- 0.41% of the lidocaine was transformed to MEGX in 20 min. Only 16% of this value was preserved in cirrhotic animals. Hepatic ischemia for 20 min transiently depressed the MEGX formation and did not cause further injury after reperfusion.

CONCLUSION

We confirmed the ability of an implantable microdialysis probe to be in constant contact with the liver tissue and thus deliver a stable transmission of chemicals across a microdialysis membrane for a certain period of time. We also verified the feasibility of reverse microdialysis as a tool for the dynamic measurement of hepatic metabolic function.

Softened endothracheal tube reduces the incidence and severity of epistaxis following nasotracheal intubation

BACKGROUND

Many complications were reported to be related with nasotracheal intubation. Various chemical or mechanical techniques have been proposed to decrease hemorrhage and trauma associated with nasotracheal intubation but the results remain controversial. We conducted a prospective, randomized, single-blind study to elucidate the effect of an endotracheal tube softened with warm water before use on the incidence and severity of epistaxis following nasotracheal intubation.

METHODS

Sixty-two healthy, (ASA class I or II) patients scheduled for elective surgery were randomly assigned into two groups. Patients in the treatment group were intubated with a softened endotracheal tube made possible by heating it in warm water while those in the control group were intubated with unsoftened (intact) tube. Epistaxis was evaluated immediately after intubation and its severity was graded as none, mild, moderate and severe. The use of Magill forceps and postoperative nasal morbidity were also recorded.

RESULTS

The total incidence of epistaxis in the "unsoftened" group was significantly higher than that of "softened" group (76.7% vs. 43.8%, P = 0.0002). The severity of nasal hemorrhage was also significantly lightened in the "softened" group. No technical difficulty was encountered in intubation with a softened endotracheal tube by prewarming. The morbidity referable to nasal intubation, however, did not differ in both groups.

CONCLUSIONS

In conclusion, our study shows that using an endotracheal tube softened by warm water could reduce the incidence and severity of epistaxis during the act of nasotracheal intubation. It is an effective way and worth a try.

The local addition of tenoxicam reduces the incidence of low back pain after lumbar epidural anesthesia

BACKGROUND

Postepidural backache is a common postoperative complaint after lumbar epidural anesthesia. Useful interventions to decrease the incidence of postepidural backache would be helpful.

METHODS

We performed a prospective, randomized, double-blind study to compare the effect of local addition of tenoxicam on the incidence of postepidural backache after nonobstetric surgery. One thousand unpremedicated ASA physical status I or II patients scheduled for hemorrhoidectomy were assigned randomly to tenoxicam or control groups. Patients in the control group received 25 ml lidocaine, 2%, with epinephrine 1:200,000 epidurally and 4 ml lidocaine, 1%, for local skin infiltration. Patients in the tenoxicam group received 25 ml lidocaine, 2%, with epinephrine 1:200,000 epidurally and 4 ml lidocaine, 1%, with tenoxicam (2 mg) 1:2,000 for local skin infiltration. Patients were interviewed at 24, 48, and 72 h postoperatively using a standard visual analog scale for evaluation of postepidural backache. A patient was considered to have postepidural backache when the postoperative visual analog scale score was higher than the preoperative score.

RESULTS

The incidence of postepidural backache in patients in the control group for the 3 days were 22.8%, 17.4%, and 9.2%, all of which were significantly more frequent than observed in the patients in the tenoxicam group (6.8%, 4.0%, and 1.2%, P < 0.01). There was a significant association between backache and multiple attempts at epidural needle insertion.

CONCLUSION

In summary, the local addition of tenoxicam reduced the incidence and severity of postepidural backache.

Bilateral subacromial bursitis with macroscopic rice bodies: ultrasound, CT and MR appearance

The radiological findings of ultrasound, CT and MR of a case of bilateral subacromial bursitis with macroscopic rice bodies is described. The previous literature is also reviewed.

Synthesis and evaluation of eight aminodeoxy trisaccharide inhibitors for N-acetylglucosaminyltransferase-V

N-Acetylglucosaminyltransferase-V is an important enzyme controlling the branching pattern of N-linked oligosaccharides. This enzyme recognizes the trisaccharide octyl 2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1-->2)-alpha-D-mannopyranosyl -(1-->6)-beta-D-glucopyranoside (5) as a substrate and adds a beta-linked GlcNAc residue to OH-6 of the central alpha-Man unit. Eight analogs of 5 were chemically synthesized where C-6 of the alpha-Man residue in 5 was deoxygenated, and structurally diverse modifications were introduced at C-4 of the same residue. The key intermediate prepared for this purpose was octyl 2-acetamido-2-deoxy-beta-D- glucopyranosyl-(1-->2)-4-amino-4,6-dideoxy-alpha-D-mannopyranosyl- (1-->6)-beta-D-glucopyranoside (7a) where the original 4'-amino group was readily derivatized on the unprotected sugar. The eight analogs 7a-7h were evaluated as inhibitors for GlcNAcT-V, both isolated (from hamster kidney) and cloned (from rat kidney). All of the compounds were found to be competitive inhibitors with Ki in the range of 3-106 microM. The conclusion of this work is that recognition of acceptor 5 does not involve contact of the C-6--C-4 end of the alpha-Man residue with the protein in the E-I (or E-S) complex.

New synthetic trisaccharide inhibitors for N-acetylglucosaminyltransferase-V

The trisaccharide octyl 2-acetamido-2-deoxy-beta-D-glucopyranosyl -(1-->2)-alpha-D-mannopyranosyl-(1-->6)-beta-D-glucopyranoside (5) is an acceptor substrate for N-acetylglucosaminyltransferase-V (EC 2.4.1.155) which adds a beta-GlcNAc residue to OH-6 of the central Man-residue. In the present work, 10 analogues of 5, each missing the potentially reactive OH-6 group, were chemically synthesized. The key intermediate used was octyl 2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1-->2)-6-amino-6-deoxy-4-O -methyl-alpha-D-mannopyranosyl-(1-->6)-beta-D-glucopyranoside (6a), which was synthesized in stepwise fashion by sequential coupling of protected monosaccharide residues. The 6'-amino group in 6a, was then selectively derivatized by either acylation or alkylation with hydrophobic, hydrophilic, charged, aromatic and potential covalently inactivating groups. The 10 trisaccharide analogues thus produced were evaluated for inhibition against GlcNAcT-V isolated from hamster kidney. All of the compounds were competitive inhibitors with Ki values ranging from 21 to 297 microM. These results indicate that acceptor substrate (or inhibitor)-enzyme complex does not involve critical recognition contacts at the position of transfer.

N-methyl-N'-nitroguanidine: irritation, sensitization, and acute oral toxicity, genotoxicity, and methods for analysis in biological samples

Currently, N-methyl-N'-nitroguanidine (MNG) is being considered by the U.S. Air Force Armament Laboratory for use in explosive formulations. A mammalian toxicity profile has been performed which includes the analysis of chemical impurities and an assessment of the potential for the metabolism of MNG to 1-methyl-3-nitro-1-nitrosoguanidine (MNNG). Potential in situ gastric conversion of MNG to MNNG is a toxicological concern because MNNG is both mutagenic and carcinogenic. The compound was also evaluated in several bioassays to assess its potential genotoxic activity. The acute oral toxicity was determined in male and female Fischer 344 rats administered a single dose of MNG in corn oil. The maximum suspension of MNG that could be delivered, 1 mg MNG/kg body weight, produced no signs of toxic stress during the 14-day observation period. The primary eye and skin irritation potential of MNG was determined in female New Zealand white rabbits using the Draize technique. MNG produced no irritation to intact skin but did produce mild conjunctival irritation. The response of a single guinea pig to the dermal sensitization evaluation indicated that MNG is a weak sensitizer. The results of three genetic tests indicated that MNG does not interact with genetic material. Gastric contents and feces from treated animals showed no evidence of conversion of MNG to MNNG.