The usage of Gellhorn pessary in pelvic organ prolapse and in regards to success, continuity of use and effect on symptoms: a retrospective study of 2 years.

INTRODUCTION: Pelvic organ prolapse (POP) is a condition involving weakened pelvic floor muscles causing organs to protrude. Conservative POP treatment comprises pelvic floor exercises and vaginal pessaries. Besides conservative care, surgery is offered. However, surgery is invasive, risky and unsuitable for those with serious medical conditions. This study aims to assess the acceptance, success and outcomes of the Gellhorn pessary for POP treatment, especially in advanced cases. MATERIALS AND METHODS: The present study is a retrospective cohort study using hospital medical records (patient files) from October 2019 to November 2021 (for 2 years). This study was performed in Malaysian women (n=53) suffering from advanced stages of POP, in which Gellhorn pessaries of diameter (44-76mm) were inserted by trained personnel. Pelvic Floor Distress Inventory-20 (PFDI-20) and Pelvic Floor Impact Questionnaire-7 (PFIQ-7) were used to measure patients' symptoms and quality of life before and after Gellhorn pessary fitting. Patients were reassessed every three months for two years and their satisfaction scores were recorded. RESULTS: We observed a significant difference in pre-test (pre-fitting) and post-test (three months post-fitting) scores on all three subscales and the PFIQ-7 total score. Twentyeight (52.83%) patients continued the use of Gellhorn pessary for at least 24 months, whereas 25 (47.20%) patients discontinued during this period. A retrospective analysis of the patients who discontinued Gellhorn pessary showed that 13 (24.52%) patients gave up the use of pessary for definitive surgery. It is noteworthy to mention here that only one out of the 13 patients who were awaiting surgery, chose surgery and the remaining 12 changed their mind after being fitted with the Gellhorn pessary. Seven (13.20%) patients declined reinsertion due to discomfort and voiding difficulties and refused further intervention, whereas three (5.66%) patients requested a ring pessary. Two (3.77%) patients, requested the removal of pessary due to vesicovaginal fistula and rectovaginal fistula (caused by an impacted pessary). The rate of continued use was 79.24% (42 patients) after 1st year and 52.83% (28 patients) at the end of two years. CONCLUSION: In the current study, the Gellhorn pessary was used to treat stage 3 and 4 POP with significant symptom reduction post-fitting. More than half of the patients continued to use the pessary after 24 months of fitting. Therefore, the Gellhorn pessary can be used as a treatment strategy for stage 3 and 4 POP with reasonable acceptance in the Malaysian population.

Anti-PD-1 therapy in patients with advanced melanoma and preexisting autoimmune disorders or major toxicity with ipilimumab.

Background: Anti-PD-1 antibodies (anti-PD-1) have clinical activity in a number of malignancies. All clinical trials have excluded patients with significant preexisting autoimmune disorders (ADs) and only one has included patients with immune-related adverse events (irAEs) with ipilimumab. We sought to explore the safety and efficacy of anti-PD-1 in such patients. Patients and methods: Patients with advanced melanoma and preexisting ADs and/or major immune-related adverse events (irAEs) with ipilimumab (requiring systemic immunosuppression) that were treated with anti-PD-1 between 1 July 2012 and 30 September 2015 were retrospectively identified. Results: One hundred and nineteen patients from 13 academic tertiary referral centers were treated with anti-PD-1. In patients with preexisting AD (N = 52), the response rate was 33%. 20 (38%) patients had a flare of AD requiring immunosuppression, including 7/13 with rheumatoid arthritis, 3/3 with polymyalgia rheumatica, 2/2 with Sjogren's syndrome, 2/2 with immune thrombocytopaenic purpura and 3/8 with psoriasis. No patients with gastrointestinal (N = 6) or neurological disorders (N = 5) flared. Only 2 (4%) patients discontinued treatment due to flare, but 15 (29%) developed other irAEs and 4 (8%) discontinued treatment. In patients with prior ipilimumab irAEs requiring immunosuppression (N = 67) the response rate was 40%. Two (3%) patients had a recurrence of the same ipilimumab irAEs, but 23 (34%) developed new irAEs (14, 21% grade 3-4) and 8 (12%) discontinued treatment. There were no treatment-related deaths. Conclusions: In melanoma patients with preexisting ADs or major irAEs with ipilimumab, anti-PD-1 induced relatively frequent immune toxicities, but these were often mild, easily managed and did not necessitate discontinuation of therapy, and a significant proportion of patients achieved clinical responses. The results support that anti-PD-1 can be administered safely and can achieve clinical benefit in patients with preexisting ADs or prior major irAEs with ipilimumab.

Efficacy and toxicity of treatment with the anti-CTLA-4 antibody ipilimumab in patients with metastatic melanoma after prior anti-PD-1 therapy.

BACKGROUND: Recent phase III clinical trials have established the superiority of the anti-PD-1 antibodies pembrolizumab and nivolumab over the anti-CTLA-4 antibody ipilimumab in the first-line treatment of patients with advanced melanoma. Ipilimumab will be considered for second-line treatment after the failure of anti-PD-1 therapy. METHODS: We retrospectively identified a cohort of 40 patients with metastatic melanoma who received single-agent anti-PD-1 therapy with pembrolizumab or nivolumab and were treated on progression with ipilimumab at a dose of 3 mg kg(-1) for a maximum of four doses. RESULTS: Ten percent of patients achieved an objective response to ipilimumab, and an additional 8% experienced prolonged (>6 months) stable disease. Thirty-five percent of patients developed grade 3-5 immune-related toxicity associated with ipilimumab therapy. The most common high-grade immune-related toxicity was diarrhoea. Three patients (7%) developed grade 3-5 pneumonitis leading to death in one patient. CONCLUSIONS: Ipilimumab therapy can induce responses in patients who fail the anti-PD-1 therapy with response rates comparable to previous reports. There appears to be an increased frequency of high-grade immune-related adverse events including pneumonitis that warrants close surveillance.

A case of mixed connective tissue disease with pseudo-pseudo Meigs' syndrome (PPMS)-like features.

Pseudo-pseudo Meigs' syndrome (PPMS) has been reported to be a rare presentation of patients with systemic lupus erythematosus (SLE). However, such a presentation is not common in other forms of connective tissue disease. We presented a case of gross ascites, pleural effusion, and marked elevation of CA-125 level (PPMS-like features) that led to a diagnosis of MCTD. The patient responded to systemic steroid therapy.

Morphological changes in the gills of Heteropneustes fossilis (Bloch) exposed to coal mining effluent water.

Ultrastructural changes in the gills of cat fish Heteropneustes fossilis exposed to coal mining effluent water collected from Rymbai river in Jaintia hills, Meghalaya, India was investigated under scanning electron microscopy (SEM). The pH of effluent water in the river was significantly low (2.5-3.0) due to coal mining activity in the adjacent areas. The dissolved oxygen (DO) was 7.7 mg l(-1) and conductivity 0.93 mS. Morphological changes like dissociation of the epithelium (E) of branchial arches and gill filaments, hypertrophy and disorientation in the array of lamellae were observed in the treated fish, leading to fish death. The primary and secondary gill lamellae (PL and SL) exhibited fusion, distortion and loss of alignment. Some of the gill rackers showed necrosis at certain places. The morphological features of the gills as revealed through SEM were highly deteriorated when compared to control.

Utilizing twins concordance rates to infer the predisposition to myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disorder in which patients experience muscular fatigability due to the presence of anti-acetylcholine receptor (AChR) antibodies which inhibit signal transduction across the neuro-muscular junction. Like all complex disorders, disease is caused by an interaction between genetic and environmental factors. Although several genes have been identified which appear to be associated with MG, both classic twin studies and current multi-gene models are insufficient to explain either disease pathogenesis or inheritance. We examined the literature on MG to determine both mono- and dizygotic twin concordance rates, and used this data to (1) estimate the proportion of the population with underlying genetic predisposition to MG and the frequency of the environmental component and (2) derive the number of inherited genetic regions that are required to confer predisposition to MG. Using a MZ twin concordance rate of 35.5%, and a dizygotic rate of approximately 4-5% (based on family data), the probability of encountering environmental components necessary to develop MG in an individual with genetic predisposition is approximately 52.4%, making the frequency of predisposition (1:5240) roughly twice the rate of incidence. Furthermore, the number of genetic regions co-inherited between affected individuals is between two and four, which may be large haplotypes with interacting activity. Determining these haplotypes, by fully sequencing associated regions in cases and controls to identify mutations present, may therefore be a practically step toward the understanding of complex disease.

Population dynamics of earthworms in relation to soil physico-chemical parameters in agroforestry systems of Mizoram, India.

Earthworm population dynamics was studied in two agroforestry systems in the tropical hilly terrain of Mizoram, north-east India, over a period of 24 months, from July 2002 to June 2004. Two sites of agroforestry situated at Sakawrtuichhun (SKT) and Pachhunga University College (PUC) campus, Aizawl, having pineapple as the main crop, were selected for detail studies on population dynamics. Five of the total twelve species of earthworm reported from the state were recorded in the study sites. The density of earthworm ranged from 6 to 243 ind.m(-2) and biomass from 3.2 - 677.64 g.m(-2) in SKT. Comparatively the density and biomass in PUC, which is at relatively higher altitude were lowerwith a range of 0 to 176 ind.m(-2) and biomass from 0 - 391.36 g.m(-2) respectively. Population dynamics of earthworm was significantly correlated with rainfall and physical characters of the soil. Earthworm biomass was significantly affected by rainfall and moisture content of the soil. The influence of chemical factors was relatively less.

Effect of ranitidine on the antiplatelet effects of aspirin in healthy human subjects.

Aspirin is often taken with H2-receptor antagonists. In vitro data suggest that certain antagonists, such as ranitidine, have inhibitory effects on platelet function. There are no reports on the combined effect of aspirin and H2-receptor antagonists on platelet function in humans. Therefore, this study's aim was to evaluate the effects of aspirin, ranitidine, and their combination on platelet function in humans. Ten healthy men aged 34.7 +/- 2 years received aspirin 325 mg/day for 4 days followed by a 9-day washout period, 3 days of ranitidine treatment (150 mg twice daily), and 4 days of dual-drug treatment. Blood samples were drawn at baseline and on the last days of aspirin monotherapy, the washout period, ranitidine monotherapy, and dual-drug treatment. Platelet aggregation was measured in response to 0.5 mg/ml arachidonic acid, 5 and 10 mumol/L adenosine diphosphate, and 1 micro g/ml collagen. The Platelet Function Analyzer 100 test was performed, and blood salicylate levels were measured in 6 subjects. Aspirin caused a marked reduction in platelet aggregation and prolongation of Platelet Function Analyzer 100 closure time. Ranitidine caused a modest decrease in platelet aggregation. Unexpectedly, the combination of aspirin and ranitidine caused less inhibition of platelet aggregation and prolongation of Platelet Function Analyzer 100 time than aspirin alone (p = 0.02 to 0.07 compared with aspirin alone). Blood salicylate levels were lower when subjects took aspirin with ranitidine than when they took aspirin alone (1 +/- 0.8 vs 1.6 +/- 0.7 mg/dl, p = 0.005). In conclusion, ranitidine appears to attenuate the antiplatelet effects of aspirin in healthy volunteers. The most likely mechanism for these findings is a change in the absorption conditions of aspirin in the presence of ranitidine.

Activity and safety of radiotherapy with anti-PD-1 drug therapy in patients with metastatic melanoma.

The anti-PD-1 antibodies nivolumab and pembrolizumab are active in metastatic melanoma; however, there is limited data on combining anti-PD-1 antibody and radiotherapy (RT). We sought to review clinical outcomes of patients receiving RT and anti-PD-1 therapy. All patients receiving anti-PD-1 antibody and RT for metastatic melanoma were identified. RT and systemic treatment, clinical outcome, and toxicity data were collected. Fifty-three patients were included; 35 patients received extracranial RT and/or intracranial stereotactic radiosurgery (SRS) and 21 received whole brain radiotherapy (WBRT) (three of whom also received SRS/extracranial RT). Patients treated with extracranial RT or SRS received treatment either sequentially (RT then anti-PD-1, n = 11), concurrently (n = 16), or concurrent "salvage" treatment to lesions progressing on anti-PD-1 therapy (n = 15). There was no excessive anti-PD-1 or RT toxicity observed in patients receiving extracranial RT. Of six patients receiving SRS, one patient developed grade 3 radiation necrosis. In 21 patients receiving WBRT, one patient developed Stevens-Johnson syndrome, one patient developed acute neurocognitive decline, and one patient developed significant cerebral edema in the setting of disease. Response in irradiated extracranial/intracranial SRS lesions was 44% for sequential treatment and 64% for concurrent treatment (p=0.448). Likewise there was no significant difference between sequential or concurrent treatment in lesional response of non-irradiated lesions. For progressing lesions subsequently irradiated, response rate was 45%. RT and anti-PD-1 antibodies can be safely combined, with no detectable excess toxicity in extracranial sites. WBRT and anti-PD-1 therapy is well tolerated, although there are rare toxicities and the role of either anti-PD-1 or WBRT in the etiology of these is uncertain.

Isolation of Japanese encephalitis virus from mosquitoes collected in Karnataka state, India from 1985 to 1987.

Detection and isolation of Japanese encephalitis (JE) virus using mosquito inoculation and immunofluorescence techniques were attempted from female mosquitoes collected in JE endemic areas of Kolar and Mandya districts of Karnataka state, India, from 1985 to 1987. 65,388 mosquitoes consisting of 19 species in 1541 pools were processed. Of these, 18 pools showed the presence of JE virus antigen. JE virus was isolated from 9 pools, 3 of Culex gelidus, 2 of C. tritaeniorhynchus, and one each of C. quinquefasciatus, C. fuscocephala, C. vishnui and Anopheles peditaeniatus. Isolation of JE virus from C. gelidus, C. fuscocephala, C. quinquefasciatus and An. peditaeniatus is reported for the first time in India.

Microvascular abnormalities in the bulbar conjunctiva of patients with type 2 diabetes mellitus.

OBJECTIVE: To study and quantify microvascular abnormalities objectively in vivo in patients with type 2 diabetes mellitus (T2DM). METHODS: The conjunctival microcirculation in 14 patients with T2DM and in age-matched healthy control subjects without diabetes was videotaped and objectively studied by using computer-assisted intravital microscopy (CAIM), a novel and quantitative real-time technology. RESULTS: Patients with T2DM (N = 14) had significantly (P<0.01) wider conjunctival vessel diameters (71.9 +/- 5.2 mm) than did healthy nondiabetic control subjects (54.0 +/- 4.4 mm). In the study patients, microvascular distribution was significantly (P<0.01) abnormal (36.7 +/- 18.2 versus 45.3 +/- 9.6 cm per unit area, patients versus control subjects), and vessel distribution was uneven on the surface of the bulbar conjunctiva. The arteriole:venule (A:V) ratio in patients with T2DM was extremely variable and differed significantly (P<0.01) from that in the nondiabetic control subjects (A:V approximately 1:2). In addition, a unique sinusoidal (hypertensive) vascular pattern frequently existed in some of the large veins of all study patients with T2DM but in none of the nondiabetic control subjects. CONCLUSION: We identified the presence of microvascular changes (abnormalities) in the conjunctival microcirculation of patients with T2DM. Although all these abnormalities did not appear in the same patient at the same time, the sum total of their presence in each patient correlated significantly with disease severity, as noted in the medical records. The severity of microvascular abnormalities, however, did not correlate with the duration of the disease since diagnosis. CAIM may be a useful objective and quantitative technique for assessing microangiopathy in patients with T2DM. The easy noninvasive accessibility of the conjunctival vessels and the ability to identify and locate the same vessels repeatedly for longitudinal evaluations further emphasize the usefulness of this real-time technology.

Amrita Bindu--a salt-spice-herbal health food supplement for the prevention of nitrosamine induced depletion of antioxidants.

Ayurveda, practised in India, identified a large number of plant components to be used in the diet for the prevention or the delayed development of degenerative disorders. They include some of the commonly used spices, namely pepper and ginger. The Materia Medica includes both naturally occurring and artificially produced salts, as a partial substitute for common salt. Health promoting herbs and spices which are classified pharmacologically as rejuvenating, nourishing, invigorating, cleansing, wound-healing, etc., are used as food additives. Amrita Bindu is a salt-spice-herbal mixture based on these principles and was tested for its effect in maintaining antioxidant defense systems in blood and liver when exposed to a carcinogenic nitrosamine, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Amrita Bindu supplementation prevented MNNG induced depletion of the antioxidant enzymes and the scavenger antioxidants glutathione and vitamins A, C and E. Amrita Bindu provides protection against free radical and reactive oxygen species induced tissue lipid peroxidation and the resultant tissue degeneration.

Influence of maternal nutritional status on mode of delivery and asphyxia neonatorum.

To assess the influence of maternal malnutrition on the mode of delivery and asphyxia neonatorum, a cross sectional survey of 615 women in the age group of 20-28 yrs at the time of delivery was done. Women with chronic ailments and complicated pregnancies were excluded. The mothers were then classified into three groups based on Weight Height Product Index (WHPI) namely well nourished (WN), moderately malnourished (MMN) and severely malnourished (SMN). The proportion of asphyxiated babies among the three groups did not differ (P greater than 0.05). Abnormal deliveries like caesarean section were more common among SMN group compared to WN group ((P less than 0.01). No such difference was made out between MMN and WN groups (P greater than 0.05).

Considerations for subgroups and phenocopies in complex disease genetics.

The number of identified genetic variants associated to complex disease cannot fully explain heritability. This may be partially due to more complicated patterns of predisposition than previously suspected. Diseases such as multiple sclerosis (MS) may consist of multiple disease causing mechanisms, each comprised of several elements. We describe how the effect of subgroups can be calculated using the standard association measurement odds ratio, which is then manipulated to provide a formula for the true underlying association present within the subgroup. This is sensitive to the initial minor allele frequencies present in both cases and the subgroup of patients. The methodology is then extended to the χ(2) statistic, for two related scenarios. First, to determine the true χ(2) when phenocopies or disease subtypes reduce association and are reclassified as controls when calculating statistics. Here, the χ(2) is given by (1 + σ * (a + b)/(c + d))/(1 - σ), or (1 + σ)/(1 - σ) for equal numbers of cases and controls. Second, when subgroups corresponding to heterogeneity mask the true effect size, but no reclassification is made. Here, the proportion increase in total sample size required to attain the same χ(2) statistic as the subgroup is given as γ = (1 - σ/2)/((1 - σ)(1 - σc/(a + c))(1 - σd/(b + d))), and a python script to calculate and plot this value is provided at kirc.se. Practical examples show how in a study of modest size (1000 cases and 1000 controls), a non-significant SNP may exceed genome-wide significance when corresponding to a subgroup of 20% of cases, and may occur in heterozygous form in all cases. This methodology may explain the modest association found in diseases such as MS wherein heterogeneity confounds straightforward measurement of association.

Microvascular abnormalities in the bulbar conjunctiva of contact lens users.

Soft contact lenses are commonly used to improve vision acuity or in cosmetic enhancement. We hypothesize that contact lens use can cause inadvertent damage to either the conjunctival microcirculation via direct vasoocclusion when the lens physically interacts with or damages the underlying vessels, or to the bulbar conjunctiva itself when the lens rests unevenly on the surface of the bulbar conjunctiva. Computer-assisted intravital microscopy was utilized to document (via video recording) and objectively quantify (via image analysis) real-time microvascular abnormalities resulting from changes and vessel remodeling in the conjunctival microcirculation in long-term (>2 yrs) contact lens users (n = 102), with non-users serving as control subjects (n = 29). A severity index (SI)--computed as the arithmetic sum of the abnormalities found in the conjunctival microcirculation in each contact lens user--was established for objective comparison with control subjects and critical interpretation. Contact lens user SI was significantly higher than control SI (user = 6.21 ± 1.26; control = 2.31 ± 1.49; p < 0.05), indicative of severe vasculopathy arising from contact lens use. The users also had significantly wider conjunctival vessel diameter (user = 71.25 ± 12.09 µm; control = 52.20 ± 5.10 µm; p < 0.05). Additional abnormalities, including damaged vessels, hemosiderin deposits (from damaged vessels or injury to the surface of the bulbar conjunctiva), vessel sludging, intermittent blood flow, and vessel tortuosity were commonly found in or adjacent to locations where the contact lens physically rested on the underlying conjunctival vessels. These results strongly suggest that microvascular abnormalities and remodeling changes occurred as a result of the inadvertent physical interaction of the lenses with either the underlying conjunctival vessels or the surface of the bulbar conjunctiva in contact lens users.

Genetic divergence and hybrid performance in mung bean.

Genetic divergence in 35 populations (10 parents and 25 F1's) of mung bean was studied by D(2) and canonical analyses. The ten parents formed as many as eight separate clusters, suggesting that the genetic divergence between them was quite substantial. The parent BR-2 was highly divergent from all the other entries. It was found that flowering time, maturity, seed density and seed size (100-seed weight) contributed substantially to the divergence. Canonical analysis supported the divergence pattern obtained by D(2) analysis and the contribution of different characters to genetic divergence. The relationship between genetic divergence (D(2)) and heterosis was evaluated. In general, there was fair agreement between the extent of heterosis and the genetic divergence between the parents.

Mechanism of clastogenic and co-clastogenic activity of cremophore with benzene in mice.

Cremophore E1 (CR), a frequently used solubilizer and emulsifier in the pharmaceutical, cosmetic and animal-raising industries, is made up of ethylene oxide and castor oil. Since ethylene oxide has been shown to be a potent genotoxic agent, we have studied the clastogenic activity of CR and its co-clastogenic activity with benzene (BZ) in mice. Male CD1 mice were divided into untreated, vehicle control and experimental groups. Mice in the experimental groups were treated orally with 0.03, 0.3 or 3% CR in water, 440 mg/kg BZ in olive oil, BZ plus the three different doses of CR (1 h apart) or BZ plus 3% CR separated by 1, 3 and 5 h intervals. Mice were killed at 30 h after the treatment for the single-treatment groups and after the first treatment for the combined treatment groups. Bone marrow cells were harvested for determination of micronuclei (MN) frequencies in polychromatic erythrocytes (PCE). The presence of known genotoxic metabolites of benzene (phenol and trans,trans muconic acid) was quantitated in collected urine. The effect on hepatic cytochrome P450 isoenzyme expression in livers of treated mice were also analyzed. We found that CR did not induce any significant or dose-dependent increase in MN. However, CR enhanced the clastogenic activity of BZ in a dose-dependent manner (from 41.6 to 47.3, 60.5 and 67.1 MN/1000 PCE respectively; P less than 0.05). The combined treatment showed an inverse time-dependent change in MN frequencies when CR was administered at 1, 3 and 5 h after BZ (41.6 to 67.1, 43.4 and 42.0 MN/1000 PCE respectively). The enhancement effect of CR is apparently due to its ability to induce significantly the cytochrome P450I family when CR was administered 1 h after treatment with BZ. However, no positive synergistic effect was observed when the combined treatment intervals were extended to 3 and 5 h. Enhanced induction of these isoenzymes is correlated with increased metabolic activation of BZ to excrete increased amounts of trans,trans muconic acid, the putative active metabolite of BZ, in urine. Our integrated study demonstrates that an apparently innocuous agent that is consumed by the general population can enhance the genotoxic activity of a ubiquitous environmental carcinogen. The potential existence of this type of interaction in our daily lives is frequently overlooked and should be investigated.

Disturbances in cellular features and elemental homeostasis in the integument of a freshwater fish Channa punctatus (Bloch) in relation to hydrogen ion concentration of polluted water.

Scanning electron microscopy revealed that the cellular and morphological defects in the integument of Channa punctatus, associated with heavy metal and other environmental pollution was related to a significant extent to the hydrogen ion concentration of the water. At low pH, the epidermis showed severe lesions, and the scale lost its attachment with the skin, due to lepidontal alterations of the circuli. Atomic absorption spectroscopic analysis of the tissue indicated disturbances in the homeostasis of several elements, which probably played a major role in causing the cellular and morphological defects. Experimental monitoring of the pH of the polluted water to near-neutral, reduced significantly the extent of cellular and morphological defects and disturbances in elemental homeostasis.

Intracellular catalase inhibition does not predispose rat heart to ischemia-reperfusion and hydrogen peroxide-induced injuries.

The objective of this study was to determine whether inhibition of intracellular catalase would decrease the tolerance of the heart to ischemia-reperfusion and hydrogen peroxide-induced injuries. Isolated bicarbonate buffer-perfused rat hearts were used in the study. Intracellular catalase was inhibited with 3-amino-1,2,4-triazole (ATZ, 1.5 g/kg body weight, two hours prior to heart perfusion). In the ischemia-reperfusion protocol, hearts were arrested with St. Thomas'II cardioplegic solution, made ischemic for 35 min at 37 degrees C, and reperfused with Krebs-Henseleit buffer for 30 min. The extent of ischemic injury was assessed using postischemic contractile recovery and lactate dehydrogenase (LDH) leakage into reperfusate. In the hydrogen peroxide infusion protocol, hearts were perfused with increasing concentrations of hydrogen peroxide (inflow rates 0.05-1.25 mumol/min). Inhibition of catalase activity (30.4 +/- 1.8 mU/mg protein in control vs 2.4 +/- 0.3 mU/mg in ATZ-treated hearts) affected neither pre-ischemic aerobic cardiac function nor post-ischemic functional recovery and LDH release in hearts subjected to 35 min cardioplegic ischemic arrest. Myocardial contents of lipid hydroperoxides were similar in control and ATZ-treated animals after 20 min aerobic perfusion, ischemia, and ischemia-reperfusion. During hydrogen peroxide perfusion, there was an increase in coronary flow rate followed by an elevation in diastolic pressure and inhibition of contractile function in comparison with control hearts. The functional parameters between control and ATZ-treated groups remained unchanged. The concentrations of myocardial lipid hydroperoxides were the same in both groups. We conclude that inhibition of myocardial catalase activity with ATZ does not predispose the rat heart to ischemia-reperfusion and hydrogen peroxide-induced injury.