Lack of evidence for intergenerational reproductive effects due to prenatal and postnatal undernutrition in the female CD-1 mouse

The impacts of adverse environments during the prenatal and/or early postnatal periods may be manifested as functional deficits that occur later in life. Epidemiological studies have shown an association of sub-optimal pregnancy outcomes in one generation with similar events in the following one, a phenomenon termed the "intergenerational effect". Data indicate that the incidence of adverse pregnancy outcomes and/or low birth weight infants is more closely correlated with the mother's perinatal environment than with that during her pregnancy. However, epidemiological studies are inherently limited given the variability of lifestyles, ethnicity, nutritional status, and exposures to environmental factors. An appropriate animal model would permit control of parameters that may be impossible to evaluate in human populations. The current studies investigated the mouse as a possible animal model. Pregnant CD-1 mice were placed on an ad libitum or food-restricted diet (50% normal) throughout gestation to generate control (CON) and intrauterine growth retarded (IUGR) litters. At birth (postnatal day (PD) 1) pups (F1) were cross-fostered to control dams in litters of either 8 (CON) or 16 (postnatal food restriction (FR)). The experimental groups thus generated represented adequate nutrition (CON-CON) and undernutrition during the prenatal (IUGR-CON), or postnatal periods (CON-FR), or both (IUGR-FR). Pups of dams on a restricted diet during gestation had significant IUGR (P<0.001) as compared to controls (birth weights of 1.32 g versus 1.63 g). At weaning, the average weight of the pups was dependent on postnatal litter size and the difference in birth weights between IUGR and CON animals was not a significant factor. CON-CON pup weight was 24.1g and IUGR-CON was 22.2 g as compared to the CON-FR (17.0 g) and IUGR-FR (17.3 g) groups. The difference in weaning pup weights between the FR and CON groups was significant (P<0.01). The F1 FR females did not reach CON female weights at any time point through 11 months after weaning. At PD60, a single breeding period for all groups of females with CON males began and continued for 75 days with 17 opportunities for breeding. Animals that became pregnant during this time were removed and allowed to litter. No significant differences were noted in average F2 litter size or average pup weight at birth: (CON-CON 12.2/1.62 g; IUGR-CON 11.9/1.6 2 g; CON-FR 10.9/1.70 g; IUGR-FR 11.3/1.61 g). We conclude that body weight at birth in the CD-1 mouse is not correlated with growth through the period of weaning (PD28). We did not find any evidence for an intergenerational reproductive effect after developmental undernutrition.

Characterization of the mammalian toxicity of the crystal polypeptides of Bacillus thuringiensis subsp. israelensis

Solubilized crystal polypeptide preparations of Bacillus thuringiensis subsp. israelensis (BTI) were fractionated by immunoaffinity chromatography using a bound monoclonal antibody formed against the 28K crystal polypeptide. The 28K polypeptide was confirmed to be hemolytic and to possess low mosquitocidal activity against Aedes aegypti larvae. By comparison, the 28K polypeptide was more potent than the solubilized BTI crystals in male Swiss Webster mice, as the LD50 values were (p less than 0.05) 0.77 and 2.33 mg protein/kg body wt, respectively. Acute administration of the 28K polypeptide (mg/kg, ip) produced severe hypothermia and bradycardia in the mouse. No evidence for cooperativity between the 28K and other crystal polypeptides was observed. Preliminary histological examination of the mouse hearts exposed to the 28K polypeptide did not reveal any specific lesion, suggesting that the deficient cardiac performance might be a secondary physiological response. Gross pathological examination of mice as well as Sprague-Dawley rats acutely treated with equivalent doses of solubilized BTI crystal preparations revealed focal to segmental reddened and edematous areas within the small intestine. Histopathology indicated that the major lesion was in the jejunum. Contrary to expectations from in vitro hemolysis assays, cytolysis of mouse red and white blood cells was not detectable after in vivo exposure to the BTI solubilized proteins. The present results indicate that the 28K polypeptide is the mammalian toxic component of BTI crystals.

Exposure-disease continuum for 2-chloro-2'-deoxyadenosine, a prototype ocular teratogen. 1. Dose-response analysis

BACKGROUND

Treatment of pregnant mice with 2-chloro-2'-deoxyadenosine (2CdA) on day 8 of gestation induces microphthalmia through a mechanism coupled to the p53 tumor suppressor gene. The present study defines 2CdA dosimetry with respect to exposure (pharmacokinetics), p53 protein induction, and disease (microphthalmia).

METHODS

Pregnant CD-1 mice dosed with 0.5-10.0 mg/kg 2CdA on day 8 provided fetuses for teratological evaluation; 2CdA was measured by HPLC in the antimesometrium through 180 min postexposure, and p53 was assessed with immunostaining of the embryo through 270 min. 5'-/3'-RACE was used to sequence the candidate gene for 2CdA bioactivation from target cells.

RESULTS

Microphthalmia appeared first in the dose-response curve. The highest 2CdA dose having no observable adverse effect (NOAEL) was 1.5 mg/kg; the benchmark dose that produced an extra 5% risk of microphthalmia (BMD(5)) was 2.5 mg/kg, and the lower confidence limit (BMDL) was 2.0 mg/kg. Pharmacokinetic parameters for doses encompassing the threshold (1.5-2.5 mg/kg) were modeled at 1.0-1.8 microM (C(max)) and 30-80 microM-min (AUC). The p53 response was not detected below the BMDL; however, a low-grade response appeared 4.5 hr after a teratogenic dose (5.0 mg/kg), and high-grade induction followed an embryolethal dose (10.0 mg/kg). RACE identified a novel splice variant of mitochondrial deoxyguanosine kinase, dGK-3, as the likely candidate for 2CdA bioactivation in the embryo.

CONCLUSIONS

Microphthalmia represented the critical effect malformation of 2CdA. The findings suggest a mitochondrial mechanism for 2CdA bioactivation, leading to an embryonic p53 response only after 2CdA elimination and implying pharmacodynamic coupling to the exposure-disease continuum. Published 2001 Wiley-Liss, Inc.

Thyroid hormone control of preganglionic innervation of the adrenal medulla and chromaffin cell development in the rat. An ultrastructural, morphometric and biochemical evaluation

In the rat, functional connections between the splanchnic nerve and the adrenal medulla are immature at birth and do not become fully competent until the first postnatal week. Neonatal administration of triiodothyronine (T3) accelerates this process, and the present study was undertaken to elucidate the underlying mechanisms. Rats were given T3 (0.1 mg/kg, s.c.) daily for 9 days beginning 1 day after birth. Preganglionic innervation of the adrenal medulla was examined by retrograde axonal transport of horseradish peroxidase (HRP). At 10 days of age, there was an increased number of labeled perikarya in the spinal cord of the hyperthyroid pups. Ultrastructural examination revealed a corresponding increase in synaptic density in the adrenal medulla and in the activity of choline acetyltransferase, a marker for preganglionic cholinergic nerve terminals. These effects were attenuated by 25 days of age, whereupon deficits in HRP-labeled neurons and adrenomedullary synapses were noted. Similarly, replication of chromaffin cells was enhanced transiently in the T3 group during the initial stage of hyperthyroidism, but subsequent long-lasting deficits in cell numbers were noted, along with a corresponding retardation of ontogeny of adrenal catecholamine biosynthesis and storage. Thus, neonatal hyperthyroidism accelerates synaptic development in the sympatho-adrenal axis but suppresses maturation of the target chromaffin cells, ultimately leading to impaired adrenomedullary function.

A self-paced oral feeding system that enhances preterm infants' oral feeding skills

AIM

Very low birth weight (VLBW) infants have difficulty transitioning to independent oral feeding, be they breast- or bottle-feeding. We developed a 'self-paced' feeding system that eliminates the natural presence of the positive hydrostatic pressure and internal vacuum build-up within a bottle during feeding. Such system enhanced these infants' oral feeding performance as monitored by overall transfer (OT; % ml taken/ml prescribed), rate of transfer (RT; ml/min over an entire feeding). This study hypothesizes that the improvements observed in these infants resulted from their ability to use more mature oral feeding skills (OFS).

METHODS

'Feeders and growers' born between 26-29 weeks gestation were assigned to a control or experimental group fed with a standard or self-paced bottle, respectively. They were monitored when taking 1-2 and 6-8 oral feedings/day. OFS was monitored using our recently published non-invasive assessment scale that identifies 4 maturity levels based on infants' RT and proficiency (PRO; % ml taken during the first 5 min of a feeding/total ml prescribed) during bottle feeding.

RESULTS

Infants oral feeding outcomes, i.e., OT, RT, PRO, and OFS maturity levels were enhanced in infants fed with the self-paced vs. standard bottle (p ≤ 0.007).

CONCLUSION

The improved oral feeding performance of VLBW infants correlated with enhanced OFS. This study is a first to recognize that VLBW infants' true OFS are more mature than recognized. We speculate that the physical properties inherent to standard bottles that are eliminated with the self-paced system interfere with the display of their true oral feeding potential thereby hindering their overall oral feeding performance.

Levels of selected organic compounds in materials for candle production and human exposure to candle emissions

Polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) selected chlorinated pesticides, polycyclic aromatic hydrocarbons (PAH) and some volatile organic compounds (VOC) were analysed in the exhaust fumes of candles made from different waxes and finishing materials. To guarantee defined burning conditions a chamber was developed for the sampling of the exhaust fumes. Using a simple exposure model, the inhalative uptake of PCDD/PCDF by an adult person was calculated for different scenarios. It was shown that additional uptake of PCDD/PCDF caused by candle emissions does not contribute significantly to the total daily intake of these compounds. Emissions of PCDD/PCDF, benzo(a)pyrene and the VOC were then compared to limit value for working places. Even when many candles would be burnt at the same time in a small room, concentrations of the compounds investigated stay below 1% of the tolerable limit values.

The effects of adding group-based lifestyle counselling to individual counselling on changes in plasma glucose levels in a randomized controlled trial: the Inter99 study

AIM

This study aimed to assess whether group-based lifestyle counselling offered to a high-risk population subgroup had any effect beyond individual multifactorial interventions on fasting plasma glucose (FPG) and 2-h plasma glucose (2hPG) changes.

METHODS

In a population-based study of 6784 participants, 4053 were determined to be at high risk based on a risk estimate of ischaemic heart disease or the presence of risk factors (smoking, hypertension, hypercholesterolaemia, obesity, impaired glucose tolerance). Of these subjects, 90% were randomized to high-intensity intervention (group A) and 10% to low-intensity intervention (group B). All participants went through health examinations, risk assessments and individual lifestyle counselling. Participants in group A were further offered group-based lifestyle counselling. The intervention was repeated after 1 and 3 years. A total of 2738 participants free of diabetes at baseline (1999-2001) and with at least one FPG and/or 2hPG measurement during 5 years of follow-up were included in the analyses. Differences in changes of plasma glucose between groups A and B were analyzed using multilevel linear regression.

RESULTS

For FPG, crude 5-year changes were significantly different between the two groups (group A: -0.003 mmol/L vs group B: -0.079 mmol/L; P=0.0427). After adjusting for relevant confounders, no differences in FPG changes were observed (P=0.116). Also, no significant differences in the 5-year changes in 2hPG between the two groups were observed (group A: - 0.127 mmol/L vs group B: -0.201 mmol/L; P=0.546).

CONCLUSION

Offering additional group-based intervention to a high-risk population subgroup had no clinical effects on changes in plasma glucose beyond those of individualized multifactorial interventions.

First Direct Observation of Runaway-Electron-Driven Whistler Waves in Tokamaks

DIII-D experiments at low density (n_{e}∼10^{19}  m^{-3}) have directly measured whistler waves in the 100-200 MHz range excited by multi-MeV runaway electrons. Whistler activity is correlated with runaway intensity (hard x-ray emission level), occurs in novel discrete frequency bands, and exhibits nonlinear limit-cycle-like behavior. The measured frequencies scale with the magnetic field strength and electron density as expected from the whistler dispersion relation. The modes are stabilized with increasing magnetic field, which is consistent with wave-particle resonance mechanisms. The mode amplitudes show intermittent time variations correlated with changes in the electron cyclotron emission that follow predator-prey cycles. These can be interpreted as wave-induced pitch angle scattering of moderate energy runaways. The tokamak runaway-whistler mechanisms have parallels to whistler phenomena in ionospheric plasmas. The observations also open new directions for the modeling and active control of runaway electrons in tokamaks.

Trophic control of the ornithine decarboxylase/polyamine system in neonatal rat brain regions: lesions caused by 6-hydroxydopamine produce effects selective for cerebellum

Norepinephrine has been hypothesized as a trophic factor influencing postnatal development of the cerebellum. In the current study, neonatal rats were given 6-hydroxydopamine (6-OHDA) to destroy noradrenergic projections and the effects on the ornithine decarboxylase (ODC)/polyamine system were evaluated; ODC initiates the synthesis of polyamines, which are known to control cellular development in the cerebellum, and neonatal ODC activity is regulated in part by beta 2-adrenergic receptors. Intracisternal administration of 6-OHDA resulted in complete and permanent depletion of cerebellar norepinephrine and a deficit in ODC, polyamine levels and cerebellar growth. Subcutaneous administration of 6-OHDA, which caused only a small initial reduction in cerebellar norepinephrine, did not affect ODC and had only minor effects on tissue growth. Indeed, levels of the polyamines tended to be elevated after subcutaneous 6-OHDA, associated with postweaning elevations in norepinephrine, results which are probably indicative of axonal regeneration. In contrast to the effects of 6-OHDA on cerebellar development, neither the intracisternal nor subcutaneous drug treatment had any effect on cerebral cortical polyamines or growth, although the intracisternal treatment did impair ODC activity early in development. These data suggest that postnatal noradrenergic input, acting through the ODC/polyamine pathway, plays a selective role in cerebellar development.

Central and sympatho-adrenal responses to insulin in adult and neonatal rats

In the mature rat, subcutaneous administration of insulin (0.02 IU/g body wt.) produced hypoglycemia and a profound activation of the sympatho-adrenal pathway, as indicated by a marked depletion of adrenal catecholamines. Cellular glucopenia caused by administration of 2-deoxyglucose also produced a sympatho-adrenal response. In contrast, in 2-day-old rats, the systemic injection of insulin evoked only a small depletion of catecholamines even though severe hypoglycemia was present, and 2-deoxyglucose also produced a diminished response. The central administration of insulin at an equivalent dose (0.02 IU/g brain) stimulated brain ornithine decarboxylase activity in both neonates and adults, but was ineffective in evoking hypoglycemia or adrenal catecholamine release. These results suggest that: (a) direct interaction of insulin with its receptors in the central nervous system is not required for activation of the sympatho-adrenal pathway, and (b) the lack of sensitivity of neonatal adrenal catecholamine release to subcutaneous administration of insulin is likely associated with immaturity of splanchnic neurotransmission rather than with absence of central insulin receptors or impaired peripheral responsiveness to insulin.

Behavioral development following daily episodes of mother-infant separation in the rat

Use of dermal or inhalation routes of maternal exposure during the postnatal period in rodent developmental neurotoxicity evaluations would be most practical if dams could be separated from their pups during the exposure period. However, this procedure raises questions concerning the effects of mother-infant separation itself on neurotoxicity endpoints. In the present study, Sprague-Dawley rat pups were either maternally deprived in warm incubators for 6 hr each day (7:00 AM-1:00 PM) or left with their dams (control), from Postnatal Day 4-20 (PND4-20), and were tested on a range of endpoints commonly used in developmental neurotoxicology. These included motor activity (PND13, 17, 19, 21, 29, 60), olfactory learning (PND18) and retention (PND25), T-maze delayed alternation (PND23, 24), acoustic startle response (PND23, 62), and auditory thresholds (PND62). None of the behavioral measures were affected by daily separation. Apparently, interrupting the mother-infant interaction for 6 hr/day has little or no effect by itself on behavioral development, as assessed by these measures.

Stimulation of rat heart ornithine decarboxylase by isoproterenol evidence for post-translational control of enzyme activity?

The activity of rat heart ornithine decarboxylase (ODC), the enzyme involved in the initial step of polyamine biosynthesis, was markedly stimulated after isoproterenol treatment, reaching a maximum of about four times the basal value four hours after administration. At all times after isoproterenol, kinetic studies revealed only two forms of the enzyme with Km values for ornithine of 35-50 microM and 190 microM, compared to only one form (190 microM) in the controls. At no time was a form of ODC with an intermediate Kornm detected, nor did dialysis reverse stimulation of activity of enzyme from isoproterenol-treated rats, or increase activity in control preparations; it is therefore unlikely that small molecular activators or inhibitors participate in the stimulation. The time course of Vmax values for the high-affinity component of the enzyme coincided with that of net enzyme activity, indicating that increases of ODC activity in response to isoproterenol might result from a shift of enzyme from its low-affinity state to the high-affinity form, rather than from appearance of additional enzyme molecules. In support of this hypothesis, alpha-difluoromethylornithine, an irreversible ODC inhibitor, displayed identical ID50 values in control and isoproterenol-treated animals, a situation which would not occur if more enzyme were present. These data are consistent with the view that post-translational control mechanisms involving macromolecular factors could operate in regulating cardiac ODC activity.

Behavior of colicins E1, E2, and E3 attached to sephadex beads

Colicins E1, E2, and E3 were covalently attached to Sephadex G-25 beads by cyanogen bromide activation. These immobilized colicins were still active in binding to specific receptors on sensitive and tolerant cells but not to resistant cells which lack such receptors. Bound colicin E3 also retained its ability to inhibit protein synthesis in vitro. Leakage of free colicin from these coated beads was negligible. Assays sensitive to free colicin activity of 1 part in 10(7) of the bound toxin failed to detect any soluble activity. The viability of different cell types bound specifically onto these colicin-Sephadex beads was assayed by using autoradiography based on labeled amino acid uptake. Immobilized E1 killed 90% of bound sensitive cells while less than 10% of sensitive cells bound to E2 and E3 were killed in this assay. These observations agree very well with previously suggested mechanisms which propose that E1, whose target site appears to be at the membrane level, can kill sensitive cells by binding to the cell surface, but that for E2 and E3 penetration of part or all of the molecule is necessary for killing action to be observed.

Nucleoside-mediated mitigation of 5-fluorouracil-induced toxicity in synchronized murine erythroleukemic cells

5-Fluorouracil (5-FU) is a chemotherapeutic agent known to retard embryonic growth and induce cleft palate and limb deformities. The predominant mechanism underlying its toxic action is thought to be inhibition of thymidylate synthetase (TS), and hence thymidine triphosphate (dTTP) synthesis, resulting in alteration of the balance of deoxynucleotide (dNTP) pools and disruption of DNA synthesis. Indeed, previously we demonstrated retarded cell-cycle progression concurrent with a 60% decrease in TS activity in rat whole embryos following maternal exposure to 40 mg/kg 5-FU on Gestational Day 14 and in the murine erythroleukemic cell (MELC) suspension culture following exposure to 5-25 microM 5-FU for 2 hr. In the study described herein, we used high-performance liquid chromatography (HPLC) to demonstrate in both of these model systems that 5-FU exposure results in similar patterns of dNTP perturbations: a prolonged decrease in dTTP and dGTP levels and an increase in dCTP and dATP. In addition, we used centrifugal elutriation to synchronize MELC in the phases of the cell cycle (G0/G1 and early S) most sensitive to 5-FU to investigate the ability of nucleoside supplementation to mitigate 5-FU-induced toxicity. Our data indicate that following a 2-hr exposure to 5-25 microM 5-FU, supplementation with 1-10 microM thymidine (TdR) for 24 hr partially reverses 5-FU-induced toxicity as evidenced by increased cellular proliferation and cell-cycle progression and amelioration of 5-FU-induced perturbations of protein synthesis and cellular membrane permeability compared to unsupplemented 5-FU-exposed cells. However, TdR concentrations >/=100 microM inhibited growth or were cytotoxic. In comparison, supplementation with 10 microM-10 mM of deoxycytidine (CdR) was not toxic, but effected a dose-dependent recovery from 5-FU-induced toxicity. At 1-100 microM, neither deoxyadenosine nor deoxyguanosine supplementation reduced 5-FU-induced toxicity; at higher concentrations, both purine nucleotides inhibited cell growth. Although these results support the hypothesis that 5-FU disrupts the MELC cell cycle by depleting dTTP (a perturbation that is reversible by TdR supplementation), they also indicate that CdR supplementation offers an additional recovery pathway.

A noninvasive method for determining patterns of milk intake in the breast-fed infant

A noninvasive adaptation of the test-weighing method has been devised for continuously monitoring milk intake in breast-fed infants. This procedure consists of counting the number of swallows from videotaped sessions of individual feeds and correlating them to the corresponding pre- and postnursing weights of the infants. The method has been tested on four nursing sessions in twins aged 1 1/2 to 2 1/2 months. A high correlation was found between swallow counts and weight gain of the babies. The patterns of milk intake as monitored by these two parameters were similar. This method has the advantage of not disrupting the natural nursing process because test-weighing during the feeding session is not necessary. In addition, it allows for longitudinal studies and uses relatively simple equipment, i.e., a balance and a video camera. It is further suggested that monitoring swallowing in the manner described herein may be a valuable addition to studies on sucking behavior in human infants. Finally, it is noted from the data presented that the pattern of milk transfer in a mother breast-feeding twins is different from that observed in mothers breast-feeding singletons who were monitored by means of a cross-sectional test-weighing procedure.

Purification, characterization, and structural elucidation of the active moiety of the previously called "suppressor activating factor (SAF)"

Upon extensive purification of the serum-free supernatant produced by a mutant T cell line (6T-CEM), an immunosuppressive activity was found to reside in an oxidized product of spermine, spermine dialdehyde (SDA). The activity was purified to homogeneity from a serum-free supernatant by using gel filtration chromatography and reverse-phase C18 HPLC. Fast Atom Bombardment (FAB) mass spectral analysis revealed its MW to be 202 and Electron Impact (EI) analysis of the acetylated material identified the purified molecule to be spermine. In the presence of human or rodent plasma, spermine exhibited no immunosuppressive activity up to 2 mg/ml. However, when assayed in the presence of FCS, which contains polyamine oxidase (PAO), spermine is oxidized to its corresponding dialdehyde which is active at 0.1 microM/ml. We have previously described a high molecular weight suppressor activating factor (SAF) found in the serum-containing supernatant of the 6T-CEM cell line. Our preliminary biological data suggest that SDA is probably responsible for the immunosuppressive activities previously observed for the SAF. The strong affinity of SDA for proteins and thiocompounds may account for the apparent high MW previously reported for SAF.

Prevalence and predictors of premature discontinuation of dual antiplatelet therapy after drug-eluting stent implantation: importance of social factors in Asian patients

AIM

Premature discontinuation of antiplatelet therapy is an independent predictor of late stent thrombosis. We sought to determine the prevalence and predictors of premature discontinuation of antiplatelet therapy after drug-eluting stent implantation among patients in Asia.

METHODS

A total of 207 consecutive patients who underwent drug-eluting stent implantation at our institution was followed up after 1 year. Premature discontinuation of antiplatelet therapy was defined as omission of aspirin and/or clopidogrel for 1 week or more.

RESULTS

Four (1.9%) patients died and the remaining 203 patients formed the study population. Prevalence of premature discontinuation of antiplatelet therapy was 12.8% (n= 26, aspirin, n= 12; clopidogrel, n= 9; both, n= 5). The median duration between stent implantation and discontinuation of antiplatelet therapy was 2.8 months. Reasons for discontinuation included cost (n= 1), gastric discomfort (n= 1), allergy (n= 3), bleeding (n= 3), advice from doctors (n= 7) and no reason (n= 11). Logistic regression showed that living alone was the only independent predictor of premature discontinuation of dual antiplatelet therapy (50.0% vs 11.3%, P= 0.001).

CONCLUSION

Among Asian patients who have undergone drug-eluting stent implantation, 12.8% discontinued dual antiplatelet therapy within 12 months. Living alone is associated with a fivefold increase in risk of premature drug discontinuation.

Sensitivity and specificity of the extended scale for dementia

The Extended Scale for Dementia was introduced as a test for grading the intellectual function of patients with dementia. Its use in discriminating demented patients from nondemented control subjects has been explored. The test had a sensitivity of 93% and a specificity of 96% in patients over the age of 65 years, but the sensitivity fell to 75% in those younger than 65 years. The scale may be useful, particularly for patients over the age of 65 years, in helping to distinguish dementia from normality.

When pacemakers fail: an analysis of clinical presentation and risk in 120 patients with failed devices

Although pacemaker recalls are common, the optimal mechanism for risk assessment and triage of patients at risk for sudden loss of device system function is unknown. A retrospective chart review of 120 patients with factory proven failed devices was performed. Logistic regression analysis was used to determine clinical correlates of emergency room versus outpatient clinic presentation at time of device failure. Twenty-two patients (18%) presented to emergency and 98 (82%) to clinic. Sixty-three devices had no device output at the time of presentation. Multivariate logistic regression analysis revealed that antiarrhythmic drug use (odds ratio: 7.4, 95% CI: 2.0-28.0), atrioventricular nodal disease as an indication for pacing (odds ratio: 2.8, 95% CI: 1.2-3.0), and female gender (odds ratio: 2.2, 95% CI: 1.0-4.5) were the only significant correlates of emergency room presentations. Pacemaker dependency (escape heart rate < 40 beats/min) did not correlate with location of presentation even though no device output at the time of presentation was associated with emergency room presentation (odds ratio: 2.5, 95% CI: 1.1-5.8). Neither the presence of structural heart disease nor symptoms at the time of device implantation (syncope or presyncope) were correlated with location of presentation upon unexpected device failure. Although there were no deaths in the 120 failed devices studied, there were 26 deaths in the total group of 227 patients with recalled devices that could not be studied. Antiarrhythmic drug use, electrocardiographic pacing indication, and female gender may be more sensitive predictors of emergency room presentation and significant symptoms in the event of unanticipated pacemaker failure. The inability of any retrospective analysis to accurately assess mortality in the setting of pacemaker system failure underscores the need for prospective databases in recall situations.

Prenatal alpha-difluoromethylornithine treatment: effects on postnatal renal growth and function in the rat

DFMO (alpha-difluoromethylornithine) is a specific irreversible inhibitor of ornithine decarboxylase (ODC), a key enzyme in the biosynthesis of polyamines, which in turn control macromolecule synthesis during cell proliferation. The current study was designed to investigate the effects of inhibition of ODC during discrete prenatal periods on renal growth and function. We administered 5 doses of 500 mg/kg DFMO or saline s.c. to timed pregnant Sprague-Dawley rats at 12 hr intervals beginning on gestation days (GD) 11, 14, or 17. Half the dams were killed on GD 20 for fetal morphological analyses and half were allowed to go to term. Renal function was assessed on postnatal days (PD) 3, 6, 10, and 14 by tests of basal renal clearance and urinary concentrating ability, and on PD 42-44 we measured serum chemistries. All three gestational treatment regimens resulted in postnatal deficits in general growth. Only in the GD 11-13 treatment group was there evidence of embryotoxicity and neonatal renal pathophysiology. Fetal weights and urogenital morphology were altered following GD 14-16 treatment and there were persistent deficits of renal growth. GD 17-19 treatment was associated only with transient postnatal deficits of renal growth. Thus, inhibition of ODC during critical prenatal periods induced distinct developmental effects. However, there were no associations between impaired renal growth and function. These data indicate that general tissue growth is not always a predictor of physiological development and support the necessity of multifaceted approaches to the understanding of adverse developmental effects.