Intrapartum Care of a Woman With Aortic Aneurysms

Advances in technology and complex care have enabled women with various health problems to become and remain pregnant. Consequently, health-care practitioners are seeing an increasing number of pregnant women who have aortic aneurysms. This case study describes the culturally sensitive intrapartum care of a Middle Eastern woman with ascending and descending aortic aneurysms.     

A New Low Threshold Platinized Epicardial Pacing Electrode: Comparative Evaluation in Immature Canines

A prospective comparison of pacing and sensing capabilities between the conventional Medtronic Model 4951 platinum-iridium epicardial pacing electrode and a new modified "platinized" version of the same electrode was performed in immature canines to determine if the new electrode design improves pacing in the immature myocardium. The conventional electrode was modified by electroplating platinum black particles onto the surface to increase the effective or true microscopic surface area, yet essentially maintain the same overall geometric electrode size. Both epicardial electrodes were inserted into the right ventricular myocardium with the lead pad sutured to the epicardium, and externalized to the scruff in five puppies (age 3 months). An additional left ventricular lead was implanted to permit chronic pacing following epicardially-induced atrioventricular block. Acute and chronic sensing and pacing capabilities of each externalized electrode were performed at implant and weekly up to 4 months. Histologic examination of each electrode implant site was performed at the end of the study period. At implant, both electrodes exhibited comparable values for sensed R waves, lead impedances, and pacing thresholds. During the study, the platinized electrode exhibited lower pacing thresholds. Analysis of all postimplant data demonstrated this threshold difference to be significantly lower (P less than .01) for the platinized version. Lead impedance and sensing capabilities remained comparable between the two designs. Histologic study demonstrated less fibrotic infiltration at the platinized electrode site. This preliminary evaluation indicates that for the duration of the postimplant study period, the platinized epicardial electrode design was associated with significantly lower thresholds and less fibrosis as a function of time compared to the conventional smooth electrode surface design. The new platinized electrode limits exit block in the developing immature myocardium and permits safe pacing at lower pulse widths and voltages to increase battery life.     

Acute Spermatogenic Effects of Bromoacetic Acids

Chlorine and bromine can react with natural organic substancesin source waters to form haloacetic acids, major disinfectionby-products of water chlorination. Several toxic effects includingtesticular damage have been attributed to the chloroacetic acidsbut little information is available on the bromine analogues.In this report we present the results of acute toxicity andacute spermatotoxicity studies of monobromoacetic acid (MBAA)and dibromoacetic acid (DBAA). In adult male rats the acuteoral toxicity of MBAA was 10-fold that of DBAA (LD50 177 vs1737 mg/kg). No reproductive-related endpoints were affectedin rats given a single dose of 100 mg MBAA/kg or 14 daily dosesof 25 mg MBAA/kg/day. In rats dosed with DBAA, serum testosteronefell to 17% of control 2 days after a single dose of 1250 mg/kgbut returned to control levels by Day 14. Marked effects onsperm motion were seen on post-treatment Days 14 and 28. Degenerativeflagellar changes in cauda sperm were present on Day 14 whileabnormal sperm head shapes and flagellar degeneration were observedin both caput and cauda sperm on Day 28. Histopathology indicatedaltered spermiation at all timepoints as evidenced by retentionof Step 19 spermatids beyond Stage VIII of the cycle of theseminiferous epithelium. Disorganization, distortion, and degenerationof late spermatids were also observed. On Day 14 structuresresembling residual bodies were rarely seen in the testis butwere numerous in the epididymis. Caput sperm counts were decreased on Day 2 and cauda sperm counts were decreased on Days14 and 28. The data indicate that DBAA is a testicular toxicantin the rat with late and elongating spermatids being particularlysusceptible germinal cells.     

The Noninvasive Mouse Ear Swelling Assay: II. Testing the Contact Sensitizing Potency of Fragrances

The Noninvasive Mouse Ear Swelling Assay. I. Refinements forDetecting Weak Contact Sensitizers. THORNE, P. S., HAWK, C,KAUSZEWSKI, S. D., AND GUINEY, P. D. (1991). Fundam. Appl. Toxicol.17, 790–806. The noninvasive mouse ear swelling assay(MESA) is a model for delayed-type hypersensitivity that holdspromise as a testing protocol for allergic contact dermatitis(ACD). The MESA employs only topical sensitization on the abdomenand does not use injections, adjuvants, anesthesia, occlusion,or disruption of the stratum comeum. Five days after induction,the ears are challenged topically and ear swelling measurementstaken at 24,48, and 72 hr indicate the extent of ACD. In thisstudy, refinements of the assay were explored in BALB/cBy miceusing dinitrofluorobenzene (DNFB) and dinitrochlorobenzene (DNCB).A complete dose-response curve was developed for DNFB and thedose which sensitized half the mice in a group (SD50, 0.001%,w/v) was used to test noninvasive enhancement protocols. Severaltriple-dose protocols tested produced no increase in responsivenessand daily dosing showed a trend toward tolerance induction yielding20% positive responses. Dietary vitamin A supplementation produceda dramatic enhancement of the responses: ear thickness increasewas doubled and the SD50 sensitized 94 to 100% of the mice inthe vitamin A groups. We conclude that the MESA allowed identificationof ACD potency for known sensitizers at very low concentrationswhich do not produce ACD with other techniques. The importanceof dose-response studies for avoiding the high-dose reduced-responseregion was also shown. Based on the observation that the vitaminA-augmented MESA was considerably more sensitive than with regularfeed, a companion study (P. S. THORNE, C. HAWK, S. D. KALISZEWSKI,P. D. GUINEY, Fundam. Appl. Tox. 17, 807–820, 1991) presentstests of the enhancements to the MESA developed in this work,using weak sensitizers and complex mixtures.     

1-Aminobenzotriazole-Induced Destruction of Hepatic and Renal Cytochromes P450 in Male Sprague-Dawley Rats

1-Aminobenzotriazole (ABT) is a suicide substrate of both hepaticand pulmonary cytochromes P450. The present studies were designedto compare the effects of ABT on hepatic and renal metabolism.Hepatic and renal microsomes and cytosol were prepared frommale Sprague-Dawley rats following ABT pretreatment (0–100mg/kg ip) for various times. Administration of 100 mg ABT/kgproduced profound reductions in P450 content in both liver andkidney within 2 hr; loss of P450 in both tissues persisted forat least 48 hours. ABT-induced destruction of P450 was dose-dependent.Maximal destruction of about 80% of total hepatic P450 occurredat dosages of ABT equal to or greater than 10 mg/kg. Maximaldestruction of about 80% of total renal P450 occurred at dosagesof ABT equal to or greater than 50 mg/kg. In vitro, ABT rapidlyand efficiently destroyed P450 in both hepatic and renal microsomesprepared from naive male Sprague-Dawley rats. Incubation ofhepatic or renal microsomes in vitro with ABT produced detectabledestruction of P450 within 5 min. Maximal destruction of P450occurred within 10 min in both hepatic and renal microsomesduring in vitro incubation with ABT. ABT-induced destructionof P450 in vitro was concentration-dependent. For hepatic microsomes,maximal destruction of about 70% of P450 required concentrationsof ABT equal to or greater than 10 mM. For renal microsomes,maximal destruction of about 80% of P450 required concentrationsof ABT equal to or greater than 10 mM. In both liver and kidney,only P450 content and P450-dependent activities were significantlydecreased. Cytochrome b₅, NADPH cytochrome c reductase, glutathioneS-transferase, glucuronyl transferase, and reduced glutathionecontents were unaltered. These data suggest that ABT selectivelyand effectively destroys both hepatic and renal P450. ABT maybe a useful tool to probe the potential role of P450 in thebioactivation of certain compounds.     

Novel Use of a Vascular Plug to Anchor an Azygous Vein ICD Lead

Vascular Plug for ICD Lead.   We describe the case of a young patient with severe hypertrophic cardiomyopathy and marginal defibrillation thresholds (DFTs) at implant of a standard transvenous implantable cardioverter-defibrillator (ICD) system. The patient subsequently experienced multiple failed ICD shocks during a prolonged episode of spontaneous ventricular tachycardia/fibrillation. Placement of a second single-coil shocking lead in the azygous vein resulted in acceptable DFTs, but the new lead migrated superiorly within hours of the procedure. To stabilize the lead position, a vascular plug was placed in the distal azygous vein, and the shocking lead screw was actively fixated to the meshwork of the device. Subsequent testing confirmed both adequate defibrillation and stable lead position. (J Cardiovasc Electrophysiol, Vol. 21, pp. 99–102, January 2010)     

Maternal Stress in Caring for Children with Feeding Disabilities: Implications for Health Care Providers

The purposes of this study were to compare the stress experienced by mothers of children with feeding disorders to the stress experienced by mothers of children with other childhood disabilities, to compare the stress experienced by mothers of children who are tube-fed with that of mothers of children with disabilities who do not require tube feeding, to ascertain the types of stressors that mothers in both groups experience, and to determine their coping resources. Subjects were mothers of children with disabilities who had recently been discharged or were receiving outpatient care from a private rehabilitation facility in a Midwestern city. The Short Form of the Questionnaire on Resources and Stress instrument and open-ended questions developed by the researchers were used. Results were analyzed using analysis of variance. Results indicate that mothers of children requiring tube feeding experienced significantly greater stress than mothers of children with disabilities who do not require tube feedings. Mothers of children requiring tube feeding also receive less support from family and friends. To assist dietitians, other health care professionals, and university instructors in developing family-centered treatment programs, we recommend including fathers, friends, or relatives in the care and feeding process; discovering ways to include the tube-fed child in family mealtime activities; increasing public awareness of tube-feeding issues; organizing support groups; and educating dietetics students about the unique stresses experienced by mothers of children who are tube-fed.