Endoscopic management of acute oesophageal variceal bleeding within 12 hours of admission is superior to 12-24 hours.

Background: Acute oesophageal variceal haemorrhage (AOVH) is a medical emergency. The American Association for the Study of Liver Diseases recommends endoscopy management as soon as possible and not more than 12 hours after presentation. The United Kingdom guidelines recommended endoscopy for unstable patients with severe acute upper gastrointestinal bleeding immediately after resuscitation and within 24 hours of admission. We aimed to evaluate the outcome of endoscopic management of AOVH in less than 12 hours compared to 12-24 hours post admission.Methods: 297 patients with AOVH were divided into groups depending on the timing of the endoscopic management: 180 within 12 h of admission and 117 patients at 12-24 hours of admission. Routine clinical and laboratory data were collected.Results: Compared to patients with endoscopic management at 12-24 hours (mean 16 hours), patients with endoscopic management within 12 hours (mean 8.3 hours) of admission had fewer hospital stay days (P = 0.001), significant reduction of ammonia levels (P < 0.0001) and significant improvement in associated hepatic encephalopathy grade 25 (p = 0.048). There were no major clinical events in the 12-hour group, but 8 events in the 12-24 hour group (p < 0.01).Conclusion: Endoscopic management of acute variceal bleeding within 12 hours of admission is superior to endoscopic management at 12-24 hours of admission regarding reduction of hospital stay, ammonia levels, correction of hepatic encephalopathy, re-bleeding and mortality rate, hence, reducing the cost of treatment benefiting patient satisfaction and improving hospital bed availability.

Neuroaxial Infantile Hemangiomas: Imaging Manifestations and Association with Hemangioma Syndromes.

BACKGROUND AND PURPOSE: Infantile hemangiomas are common lesions in the pediatric population; in rare cases, an infantile hemangioma can be detected along the neural axis. The purposes of our study included determination of the incidence, location, and imaging appearance of neuroaxial infantile hemangiomas and their syndromic association. We also assessed additional features of cerebral and cardiovascular anomalies that may be associated with neuroaxial lesions. MATERIALS AND METHODS: A retrospective cohort study was performed, searching the radiology database for patients with segmental infantile hemangiomas referred for assessment of possible hemangioma syndromes. We retrospectively reviewed brain and spine MR imaging studies, with particular attention paid to neuroaxial vascular lesions, as well as the relevant clinical data. Neuroaxial hemangioma imaging findings were described, and comparison of segmental cutaneous infantile hemangioma location with the imaging findings was performed in patients with confirmed hemangioma syndromes and in patients with isolated skin infantile hemangioma. RESULTS: Ninety-five patients with segmental infantile hemangioma were included in the study, 42 of whom had a hemangioma syndrome; of those, 41 had posterior fossa brain malformations, hemangioma, arterial lesions, cardiac abnormalities, and eye abnormalities (PHACE) syndrome and 1 had diffuse neonatal hemangiomatosis. Neuroaxial involvement was detected in 20/42 patients (48%) with hemangioma syndromes and in no subjects with isolated segmental infantile hemangioma (P < .001). The most common intracranial hemangioma location was within the ipsilateral internal auditory canal (83%). CONCLUSIONS: Many pediatric patients with segmental infantile hemangioma in the setting of hemangioma syndromes, especially those with PHACE, had neuroaxial hemangiomas. This finding may potentially lead to requiring additional clinical evaluation and management of these patients.

Preoperative Evaluation of Craniopagus Twins: Anatomy, Imaging Techniques, and Surgical Management.

Craniopagus twins are a rare congenital malformation in which twins are conjoined at the head. Although there is high prenatal and postnatal mortality for craniopagus twins, successful separation has become more common due to advances in neuroimaging, neuroanesthesia, and neurosurgical techniques. Joined brain tissue, shared arteries and veins, and defects in the skull and dura make surgery technically challenging, and neuroimaging plays an important role in preoperative planning. Drawing on our experience from consultation for multiple successful separations of craniopagus twins, we discuss what radiologists need to know about the anatomy, classification, imaging techniques, and surgical management of craniopagus twins.

The role of Caesarean section in childhood asthma.

OBJECTIVE: As indicated by previous studies, children born via Caesarean section may have an increased risk of developing asthma compared with those born via vaginal delivery. The aim of this study is to assess the association between a Caesarean section and the risk of childhood asthma. Methods: This was a case-control study carried out in Basrah, Iraq including 952 children aged 3-12 years. Four hundred and seven asthmatic cases and a control group of 545 age-matched non-asthmatic children were enrolled. Binary logistic regression was used to assess the relationship between asthma and birth via Caesarean section. RESULTS: The mean age of the children was 6.7±2.5 years. Two-hundred eighty-three children (29.7%) were delivered via Caesarean section. The binary logistic regression analysis showed that delivery via Caesarean section was found to be an independent significant risk factor for asthma (OR=3.37; 95% CI=1.76-6.46; p<0.001). In addition, many other risk factors were found to be significant predictors of asthma, including bottlefeeding (OR=27.29; 95% CI=13.54-54.99; p<0.001) and low birth weight (OR=16.7; 95% CI=6.97-37.49; p<0.001). CONCLUSION: Caesarean section is significantly associated with an increased risk of childhood asthma.

Near-Term Decrease in Brain Volume following Mild Traumatic Injury Is Detectible in the Context of Preinjury Volumetric Stability: Neurobiologic Insights from Analysis of Historical Imaging Examinations.

BACKGROUND AND PURPOSE: Neurodegeneration after mild traumatic brain injury may manifest as decreasing regional brain volume that evolves from months to years following mild traumatic brain injury and is associated with worse clinical outcomes. We hypothesized that quantitative brain volume derived from CT of the head, performed for clinical indications during routine care, would change with time and provide insights into the putative neuroinflammatory response to mild traumatic brain injury. MATERIALS AND METHODS: We searched the electronic medical record of our institution for NCCTs of the head performed in patients with mild traumatic brain injury and included those who also underwent NCCTs of the head 1 month to 1 year before and after mild traumatic brain injury for an indication unrelated to trauma. Controls underwent 3 sequential NCCTs of the head with indications unrelated to trauma. The whole-brain and intracranial volume groups were computed using ITK-SNAP. Brain volumes normalized to intracranial volumes were compared across time points using the Wilcoxon signed-rank test. RESULTS: We identified 48 patients from 2005 to 2015 who underwent NCCTs of the head in the emergency department for mild traumatic brain injury and had NCCTs of the head performed both before and after mild traumatic brain injury. Median normalized brain volumes significantly decreased on the follow-up study post-mild traumatic brain injury (0.86 versus 0.84, P < .001) and were similar compared with pre-mild traumatic brain injury studies (0.87 versus 0.86, P = .927). There was no significant difference between normalized brain volumes in the 48 controls. CONCLUSIONS: A decrease in brain volume following mild traumatic brain injury is detectable on CT and is not seen in similar patients with non-mild traumatic brain injury during a similar timeframe. Given the stability of brain volume before mild traumatic brain injury, CT volume loss may represent the subtle effects of neurodegeneration.

Predictive Factors of Liver Dysfunction After Right Hemihepatectomy for Adult Living Donor Liver Transplantation.

BACKGROUND: Living liver donors represent a special group of patients. They are healthy individuals who are exposed to a major surgery, in which the dominant liver proportion is extracted as a graft. Of all potential donor-related morbidities, posthepatectomy liver dysfunction (PHLD) is the most significant as it may be directly related to donor mortality. We aimed to review our data of adult living donor liver transplantation (LDLT) utilizing the right hemiliver grafts to determine the incidence and potential predictors for the development of PHLD, defined according to the International Study Group of Liver Surgery. METHODS: We reviewed the data of all adult living donors who underwent right hemihepatectomy during the period between May 2004 and 2016. RESULTS: During the study period, 434 cases underwent right hemihepatectomy for adult LDLT. We divided our cases into 2 groups according to the occurrence of PHLD. A significant lower residual liver volume and percentage were noted in PHLD group. Longer intensive care unit stay and hospital stay, and more postoperative morbidities, were observed in PHLD group. PHLD occurred in 50 cases (11.5%), and most of them were grade A (47 cases [10.8%]). Two cases (0.5%) had grade B requiring diuretic therapy, and 1 case (0.2%) had grade C requiring ultrasound guided tube drainage and surgical exploration finally. CONCLUSIONS: We should not underestimate the risks of liver donation surgery, especially when utilizing the right hemiliver graft. Donor safety should be ensured by accurate preoperative volumetric assessment of the remnant liver and remnant liver volume limitations must be strictly followed.

Living-Donor Liver Transplantation in Hepatitis C Virus Era: A Report of 500 Consecutive Cases in a Single Center.

BACKGROUND: Living donor liver transplantation (LDLT) is considered a safe alternative to deceased donor liver transplantation (DDLT). In Egypt, DDLT program is still awaited, making LDLT the only hope for patients with end-stage liver disease, mainly due to chronic hepatitis C virus (HCV) infection. The current study is conducted to evaluate our experience of LDLT and discuss the lessons learned from 500 consecutive cases in HCV area. METHODS: We reviewed the data of patients who underwent LDLT at Gastrointestinal Surgery Center, Mansoura University during the period between May 2004 and March 2017. RESULTS: During the study period, 500 cases underwent LDLT at our unit. The median age was 51 years, and most of our cases were males (446, 89.2%) and had HCV infection (453, 90.6%). The median MELD score was 15. Median ICU stay was 5 days, and hospital stay was 22 days. Postoperative morbidities occurred in 220 cases (44%). Early mortality occurred in 69 patients (13.8%), and late mortality occurred in 45 patients (9%). The 1-, 3-, 5-, and 7-year overall survival rates of all cases were 80.9%, 78.2%, 75.7%, and 75%, respectively. Preoperative creatinine, worm ischemia, blood transfusion, ICU stay, postoperative morbidities, and small for size syndrome were independent predictors for overall survival. CONCLUSIONS: In countries lacking DDLT, LDLT is the only effective alternative. LDLT requires a teamwork to achieve successful outcomes. LDLT should only be performed in centers with the adequate experience to avoid and decrease the hazards related to this procedure.

Mechanism-based PK/PD modeling of the respiratory depressant effect of buprenorphine and fentanyl in healthy volunteers.

The objective of this study was to characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship of buprenorphine and fentanyl for the respiratory depressant effect in healthy volunteers. Data on the time course of the ventilatory response at a fixed P(ET)CO(2) of 50 mm Hg and P(ET)O(2) of 110 mm Hg following intravenous administration of buprenorphine and fentanyl were obtained from two phase I studies (50 volunteers received buprenorphine: 0.05-0.6 mg/70 kg and 24 volunteers received fentanyl: 0.075-0.5 mg/70 kg). The PK/PD correlations were analyzed using nonlinear mixed effects modeling. A two- and three-compartment pharmacokinetic model characterized the time course of fentanyl and buprenorphine concentration, respectively. Three structurally different PK/PD models were evaluated for their appropriateness to describe the time course of respiratory depression: (1) a biophase distribution model with a fractional sigmoid E(max) pharmacodynamic model, (2) a receptor association/dissociation model with a linear transduction function, and (3) a combined biophase distribution-receptor association/dissociation model with a linear transduction function. The results show that for fentanyl hysteresis is entirely determined by the biophase distribution kinetics, whereas for buprenorphine hysteresis is caused by a combination of biophase distribution kinetics and receptor association/dissociation kinetics. The half-time values of biophase equilibration (t(1/2, k(eo))) were 16.4 and 75.3 min for fentanyl and buprenorphine, respectively. In addition, for buprenorphine, the value of k(on) was 0.246 ml/ng/min and the value of k(off) was 0.0102 min(-1). The concentration-effect relationship of buprenorphine was characterized by a ceiling effect at higher concentrations (intrinsic activity alpha=0.56, 95% confidence interval (CI): 0.50-0.62), whereas fentanyl displayed full respiratory depressant effect (alpha=0.91, 95% CI: 0.19-1.62).

The over-expression of P-glycoprotein in K-562 and DAUDI cells, is associated with a high susceptibility to NK and LAK cells.

We evaluated the susceptibility to natural killer (NK) or lymphokine activated killer (LAK) cell-mediated cytolysis of two pairs of drug sensitive/resistant tumor cell lines which were extensively characterized at phenotypic and genotypic level. In the DAUDI cell system, the acquired capability of tumor cell variants to grow in the presence of a relatively high concentration of vinblastine (VBL) is associated with a marked increase to NK and LAK susceptibility. In contrast in the K-562 cell system, no correlation between drug-resistance, P-glycoprotein expression and susceptibility to NK or LAK activity seems to occur.

Superovulation and embryo quality in beef cows using PMSG and a monoclonal anti-PMSG.

The long half-life of pregnant mare serum gonadotrophin (PMSG) reduces its application in the superovulation of cattle; thus, a monoclonal antibody to PMSG (anti-PMSG) was administered at the onset of estrus to increase the number of transferable embryos. Angus, Hereford and Angus x Hereford cows (n = 149) 3 to 9 yr old were assigned randomly to one of three dosages of PMSG (1500, 3000 or 6000 IU) with or without an equivalent dosage of anti-PMSG. Embryos were collected nonsurgically on Day 8 (estrus = Day 0), and all cows were ovariectomized on Day 9. The percentage of cows exhibiting estrus and ovulating decreased (P<0.05) with an increasing dosage of PMSG (82, 76 and 44% for 1500, 3000 and 6000 IU, respectively). Ovarian and total corpora lutea (CL) weight increased (P<0.001) linearly as PMSG dosage increased, but were reduced (P<0.001) curvilinearly by anti-PMSG, resulting in a PMSG by anti-PMSG interaction (P<0.001); the interaction was also significant (P<0.05) for ovulation rate (14.0 vs 14.3, 21.5 vs 24.4 and 29.2 vs 6.6 CL for 1500, 3000 and 6000 IU PMSG, without vs with anti-PMSG, respectively). Anti-PMSG increased (P<0.001) the number of small ovarian follicles (1 to 3 mm diameter) and decreased (P<0.001) the number of large follicles (>10 mm) at ovariectomy; the number of large follicles increased (P<0.001) with PMSG dosage. The number of total and transferable embryos recovered did not differ among PMSG and anti-PMSG dosages; however, the percentage of transferable embryos decreased (P<0.01) with increasing PMSG dosage. In general, neither PMSG dosage nor anti-PMSG influenced embryo quality.

A novel approach to identify responder subgroups and predictors of response to low- and high-dose capsaicin patches in postherpetic neuralgia.

BACKGROUND: Treatment of chronic pain conditions is commonly assessed at specific endpoints at preset times during or after treatment by analysis of the total study population. An alternative approach is the identification of specific patient subgroups characterized by differential response patterns in their analgesic response and to determine the presence of significant predictors of effect. METHODS: Data from four double-blind, randomized controlled trials on the efficacy of topical capsaicin 8% (Qutenza) versus an active control (capsaicin 0.04%) in patients with postherpetic neuropathic pain were combined. Longitudinal pharmacodynamic, mixture and covariate analyses were performed on the pooled dataset. RESULTS: Data from 1248 patients treated with Qutenza (n = 722) or topical low-dose capsaicin 0.04% (n = 526) were successfully analysed. Five distinct response subgroups were detected with different treatment efficacies, including a group of non-responders, a group showing partial analgesic effect and a group showing full analgesic effect. Active control and Qutenza had similar response profiles, but the proportional distribution of patients among the five response groups was in favour of Qutenza, with 40% less non-responders and 25% more patients showing a full analgesic response. For Qutenza, important predictors of efficacy were efficacy of lidocaine pretreatment and greater pretreatment pain score variability. CONCLUSIONS: The analyses indicate the existence of different response groups to treatment with Qutenza and an active control patch that may possibly be related to different pain mechanisms among these groups, despite a presumed common underlying disease process, and that require different treatment approaches among subgroups.

Alleviation of reproductive toxicity of gossypol using selenium supplementation in rams.

The objective of this study was to evaluate the reproductive toxicity of gossypol and the possible counteracting effect of selenium supplementation in rams. Twenty-five mature crossbred (Barki × Rahamni) rams were randomly divided into 5 equal groups. The first group served as a control (no gossypol in diet). The second and third groups received diets containing free gossypol of 9 and 14 mg·kg(-1) BW·d(-1)(low level and high level of gossypol), respectively. The fourth and fifth groups received the same diets given to the second and third groups, respectively, with an oral administration of 1 mg selenium (as sodium selenite) daily for each animal. Results showed reductions in ejaculate volume (P = 0.028), percentage of dead sperm (P = 0.003), total functional sperm fraction (P < 0.001), and blood serum concentration of testosterone (P < 0.001) in the presence of both levels of gossypol inclusion. Furthermore, high level of gossypol reduced forward motility (P < 0.001) and semen initial fructose concentration (P = 0.002) and increased abnormal-head sperm (P = 0.003) and blood serum concentration of triiodothyronine (P = 0.006). Regardless of selenium supplementation, increasing level of free gossypol in diet resulted in a significant decrease in the percentage of forward motility (P = 0.037) and significant increases in the mean values of sperm concentration (P < 0.001), total sperm output (P = 0.002), percentage of total abnormal sperm (P = 0.058), and abnormal-head sperm (P = 0.016). On the other hand, regardless of levels of gossypol inclusion, selenium supplementation resulted in significant increases in libido (P < 0.001), mean values of ejaculate volume (P < 0.001), percentage of forward motility (P = 0.019), total sperm output (P < 0.001), total functional sperm fraction (P < 0.001), semen initial fructose concentration (P = 0.031), and blood serum concentrations of both testosterone and triiodothyronine (P < 0.001). In conclusion, free gossypol in diet induced adverse effects on semen quality in rams, but selenium supplementation successfully counteracts most of the hazardous effects of gossypol on semen characteristics.

Guidelines for the quality control of population pharmacokinetic-pharmacodynamic analyses: an industry perspective.

Quality population modeling and simulation analyses and reports are something every modeler desires. However, little attention in the literature has been paid to what constitutes quality regarding population analyses. Very rarely do published manuscripts contain any statement about quality assurance of the modeling results contained therein. The purpose of this manuscript is to present guidelines for the quality assurance of population analyses, particularly with regards to the use of NONMEM from an industrial perspective. Quality guidelines are developed for the NONMEM installation itself, NONMEM data sets, control streams, output listings, output data files and resultant post-processing, reporting of results, and the review processes. These guidelines were developed to be thorough yet practical, though are not meant to be completely comprehensive. It is our desire to ensure that what is reported accurately reflects the collected data, the modeling process, and model outputs for a modeling project.

Buprenorphine induces ceiling in respiratory depression but not in analgesia.

BACKGROUND: We measured the effect of two weight adjusted i.v. doses (0.2 mg per 70 kg and 0.4 mg per 70 kg) of the potent opioid buprenorphine on analgesia and respiratory depression in healthy volunteers. The aim of the study was to compare buprenorphine's behaviour with respect to the occurrence of ceiling (or apparent maximum) in these typical micro-opioid protein-(MOP) receptor effects. METHODS: Ten subjects (5 males) received 0.2 mg per 70 kg, 10 others (5 males) 0.4 mg per 70 kg i.v. buprenorphine. Steady-state inspired minute ventilation at a fixed end-tidal Pco(2) of 7 kPa was measured before drug infusion and at regular intervals after drug infusion. Experimental pain was induced using transcutaneous electrical stimulation and a gradually increasing current. Pain tolerance was measured at regular intervals before and after drug infusion. The studies lasted 8 h. RESULTS: After infusion of the drug ventilation showed a rapid decline and reached peak depression between 150 and 180 min after drug administration. This effect was dose-independent with respect to timing and magnitude. At peak respiratory depression minute ventilation was 13.1 (sd 1.8) litre min(-1) in the 0.2 mg group vs 12.0 (sd 1.3) litre min(-1) in the 0.4 mg group (n.s.). At buprenorphine 0.2 mg a small short-lived analgesic effect was observed with a maximum increase in pain tolerance current of 6.7 (sd 2.8) mA occurring at 75 min after drug administration. Peak analgesic effect was 29% above baseline current. In contrast, buprenorphine 0.4 mg caused a large and long-lived analgesic effect with a maximum increase in pain tolerance current of 23.8 (sd 7.4) mA occurring at 130 min after drug administration. Peak analgesic effect was 160% above baseline current (0.4 vs 0.2 mg, P<0.01). CONCLUSIONS: While buprenorphine's analgesic effect increased significantly, respiratory depression was similar in magnitude and timing for the two doses tested. We conclude that over the dose range tested buprenorphine displays ceiling in respiratory effect but none in analgesic effect.

Comparison of the respiratory effects of intravenous buprenorphine and fentanyl in humans and rats.

BACKGROUND: There is evidence from animal studies suggesting the existence of a ceiling effect for buprenorphine-induced respiratory depression. To study whether an apparent ceiling effect exists for respiratory depression induced by buprenorphine, we compared the respiratory effects of buprenorphine and fentanyl in humans and rats. METHODS: In healthy volunteers, the opioids were infused i.v. over 90 s and measurements of minute ventilation at a fixed end-tidal PCO2 of 7 kPa were obtained for 7 h. Buprenorphine doses were 0.7, 1.4, 4.3 and 8.6 microg kg(-1) (n=20 subjects) and fentanyl doses 1.1, 2.1, 2.9, 4.3 and 7.1 microg kg(-1) (n=21). Seven subjects received placebo. In rats, both opioids were infused i.v. over 20 min, and arterial PCO2 was measured 5, 10, 15 and 20 min after the start of fentanyl infusion and 30, 150, 270 and 390 min after the start of buprenorphine infusion. Doses tested were buprenorphine 0, 100, 300, 1000 and 3000 microg kg(-1) and fentanyl 0, 50, 68 and 90 microg kg(-1). RESULTS: In humans, fentanyl produced a dose-dependent depression of minute ventilation with apnoea at doses > or = 2.9 microg kg(-1); buprenorphine caused depression of minute ventilation which levelled off at doses > or = 3.0 microg kg(-1) to about 50% of baseline. In rats, the relationship of arterial PCO2 and fentanyl dose was linear, with maximum respiratory depression at 20 min (maximum PaCO2 8.0 kPa). Irrespective of the time at which measurements were obtained, buprenorphine showed a non-linear effect on PaCO2, with a ceiling effect at doses > 1.4 microg kg(-1). The effect on PaCO2 was modest (maximum value measured, 5.5 kPa). CONCLUSIONS: Our data confirm a ceiling effect of buprenorphine but not fentanyl with respect to respiratory depression.

Simultaneous quantitative analysis of ketanserin and ketanserinol in plasma by RP-HPLC with fluorescence detection.

A sensitive and selective high-performance liquid chromatographic assay for the quantification of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT-1 solid-phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 x 4.5 mm, 3 micro m particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9-methanol-acetonitrile (52:40:8, v/v/v). Detection was performed with fluorescence detection (lambda(ex) = 332 nm and lambda(em) = 410 nm). Calibration curves were linear (r(2) = 0.999) in the range 0-400 ng/mL for both ketanserin and ketanserinol. The repeatability coefficient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefficient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantification for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed.

Expression of lymphocyte homing receptor gene is lost in multi-drug-resistant variants of human T-lymphoblastoid CCRF-CEM cells.

The 2.2-kb human cDNA clone PBL32, encoding for the lymphocyte homing receptor (LHR) was used to study the expression of this determinant in multi-drug-resistant (MDR) variants of human T-lymphoblastoid CCRF-CEM (CEM) cells. LHR is significantly associated with the drug-sensitive phenotype, its expression being progressively and quantitatively reduced in MDR variants of CEM cells according to the extent of drug resistance.

The effect of exposure to direct solar radiation on the semen characteristics of the male rabbit.

Three groups of cross-bred bucks (Baladi X standard breeds) were exposed to solar radiation for three hours per day during an 8-week experimental period in June and July and were compared with a control subgroup of the same age. Each subgroup (experimental and control) comprised 10 bucks, totalling 60 bucks. The effects were determined and assessed during the 28-week period following the experiment. The exposure to solar radiation at 5 or 12 weeks of age caused a delay in the onset of puberty. In all three groups, the concentration of sperms and the fructose content were decreased. There was a marked increase in the proportion of abnormal or dead sperms and in the methylene blue reduction time. The young animals were most affected by the exposure.