Interaction of positive airway pressure mask magnets with cardiac implantable electronic devices.

STUDY OBJECTIVES: To evaluate for potential interactions between magnetic positive airway pressure (mPAP) masks and cardiac implantable electronic devices (CIEDs) for patients with sleep apnea. METHODS: Adult patients with a CIED who used an mPAP mask were recruited from our sleep clinic to undergo a safety visit at our pacemaker clinic. We tested whether the mPAP interacted with the implanted device at home during normal use and in the clinic during simulated normal use and with direct contact. The magnetic field strength of 6 mPAP masks was tested with a gaussmeter. RESULTS: Of 13 patients tested, 1 (8%), wearing a full face mask (ResMed AirFit F30 [ResMed, San Diego, California]), had a magnet response event (interaction) with direct contact, but no interactions were identified during normal or simulated normal use in any patient. The magnetic field strength of the mPAP masks increased the closer the mask got to the CIED, from 0.4 mT (4 G) at the mask manufacturer's recommended 5.1-cm (2-inch) distance from an implanted medical device up to 291 mT (2,910 G) at 0 cm (0 inches; direct contact). CONCLUSIONS: An mPAP mask may interact with a CIED if placed directly on the skin overlying the CIED. The use of Philips Respironics (Philips, Cambridge, Massachusetts) mPAP masks is now contraindicated in patients with a CIED. Until additional studies are conducted to better document the risks and benefits of mPAP masks, we recommend discouraging patients with CIEDs from using any mPAP mask. CITATION: Ruoff CM, Tashman YS, Cheema KPK, et al. Interaction of positive airway pressure mask magnets with cardiac implantable electronic devices. J Clin Sleep Med. 2023;19(5):941-946.

Evolution and developmental expression of the sodium-iodide symporter (NIS, slc5a5) gene family: Implications for perchlorate toxicology.

The vertebrate sodium-iodide symporter (NIS or SLC5A5) transports iodide into the thyroid follicular cells that synthesize thyroid hormone. The SLC5A protein family includes transporters of vitamins, minerals, and nutrients. Disruption of SLC5A5 function by perchlorate, a pervasive environmental contaminant, leads to human pathologies, especially hypothyroidism. Perchlorate also disrupts the sexual development of model animals, including threespine stickleback (Gasterosteus aculeatus) and zebrafish (Danio rerio), but the mechanism of action is unknown. To test the hypothesis that SLC5A5 paralogs are expressed in tissues necessary for the development of reproductive organs, and therefore are plausible candidates to mediate the effects of perchlorate on sexual development, we first investigated the evolutionary history of Slc5a paralogs to better understand potential functional trajectories of the gene family. We identified two clades of slc5a paralogs with respect to an outgroup of sodium/choline cotransporters (slc5a7); these clades are the NIS clade of sodium/iodide and lactate cotransporters (slc5a5, slc5a6, slc5a8, slc5a8, and slc5a12) and the SGLT clade of sodium/glucose cotransporters (slc5a1, slc5a2, slc5a3, slc5a4, slc5a10, and slc5a11). We also characterized expression patterns of slc5a genes during development. Stickleback embryos and early larvae expressed NIS clade genes in connective tissue, cartilage, teeth, and thyroid. Stickleback males and females expressed slc5a5 and its paralogs in gonads. Single-cell transcriptomics (scRNA-seq) on zebrafish sex-genotyped gonads revealed that NIS clade-expressing cells included germ cells (slc5a5, slc5a6a, and slc5a6b) and gonadal soma cells (slc5a8l). These results are consistent with the hypothesis that perchlorate exerts its effects on sexual development by interacting with slc5a5 or its paralogs in reproductive tissues. These findings show novel expression domains of slc5 genes in stickleback and zebrafish, which suggest similar functions across vertebrates including humans, and provide candidates to mediate the effects of perchlorate on sexual development.

Exogenous iodide ameliorates perchlorate-induced thyroid phenotypes in threespine stickleback.

Perchlorate is a ubiquitous environmental contaminant that has widespread endocrine disrupting effects in vertebrates, including threespine stickleback (Gasterosteus aculeatus). The target of perchlorate is thyroid tissue where it induces changes in the organization, activation, and morphology of thyroid follicles and surrounding tissues. To test the hypothesis that some phenotypes of perchlorate toxicity are not mediated by thyroid hormone, we chronically exposed stickleback beginning at fertilization to perchlorate (10, 30, 100ppm) or control water with and without supplementation of either iodide or thyroxine (T4). Stickleback were sampled across a one-year timespan to identify potential differences in responses to treatment combinations before and after sexual maturation. We found that most thyroid histomorphological phenotypes induced by perchlorate (follicle proliferation, reduced follicle area (adults only), colloid depletion, thyrocyte hypertrophy (subadults only)) were significantly ameliorated by exogenous iodide supplementation. In contrast, treatment with exogenous T4 did not correct any of the thyroid-specific histopathologies induced by perchlorate. Whole-body thyroid hormone concentrations were not significantly affected by perchlorate exposure; however, supplementation with iodide and T4 significantly increased T4 concentrations. This study also revealed an increased erythrocyte area in the thyroid region of perchlorate-exposed adults, while lipid droplet number increased in perchlorate-exposed subadults. Increased erythrocyte area was ameliorated by both iodide and T4, while neither supplement was able to correct lipid droplet number. Our finding on lipid droplets indicates that exposure to perchlorate in early development may have obesogenic effects.

Perchlorate Exposure Reduces Primordial Germ Cell Number in Female Threespine Stickleback.

Perchlorate is a common aquatic contaminant that has long been known to affect thyroid function in vertebrates, including humans. More recently perchlorate has been shown to affect primordial sexual differentiation in the aquatic model fishes zebrafish and threespine stickleback, but the mechanism has been unclear. Stickleback exposed to perchlorate from fertilization have increased androgen levels in the embryo and disrupted reproductive morphologies as adults, suggesting that perchlorate could disrupt the earliest stages of primordial sexual differentiation when primordial germ cells (PGCs) begin to form the gonad. Female stickleback have three to four times the number of PGCs as males during the first weeks of development. We hypothesized that perchlorate exposure affects primordial sexual differentiation by reducing the number of germ cells in the gonad during an important window of stickleback sex determination at 14-18 days post fertilization (dpf). We tested this hypothesis by quantifying the number of PGCs at 16 dpf in control and 100 mg/L perchlorate-treated male and female stickleback. Perchlorate exposure from the time of fertilization resulted in significantly reduced PGC number only in genotypic females, suggesting that the masculinizing effects of perchlorate observed in adult stickleback may result from early changes to the number of PGCs at a time critical for sex determination. To our knowledge, this is the first evidence of a connection between an endocrine disruptor and reduction in PGC number prior to the first meiosis during sex determination. These findings suggest that a mode of action of perchlorate on adult reproductive phenotypes in vertebrates, including humans, such as altered fecundity and sex reversal or intersex gonads, may stem from early changes to germ cell development.

Perchlorate disrupts embryonic androgen synthesis and reproductive development in threespine stickleback without changing whole-body levels of thyroid hormone.

Perchlorate, an environmental contaminant, disrupts normal functioning of the thyroid. We previously showed that perchlorate disrupts behavior and gonad development, and induces external morphological changes in a vertebrate model organism, the threespine stickleback. Whether perchlorate alters these phenotypes via a thyroid-mediated mechanism, and the extent to which the effects depend on dose, are unknown. To address these questions, we chronically exposed stickleback to control conditions and to three concentrations of perchlorate (10, 30 and 100ppm) at various developmental stages from fertilization to reproductive maturity. Adults chronically exposed to perchlorate had increased numbers of thyroid follicles and decreased numbers of thyrocytes. Surprisingly, T4 and T3 levels in larval, juvenile, and adult whole fish chronically exposed to perchlorate did not differ from controls, except at the lowest perchlorate dose, suggesting a non-monotonic dose response curve. We found no detectable abnormalities in external phenotype at any dose of perchlorate, indicating that the increased number of thyroid follicles compensated for the disruptive effects of these doses. In contrast to external morphology, gonadal development was altered substantially, with the highest dose of perchlorate causing the largest effects. Perchlorate increased the number both of early stage ovarian follicles in females and of advanced spermatogenic stages in males. Perchlorate also disrupted embryonic androgen levels. We conclude that chronic perchlorate exposure may not result in lasting adult gross morphological changes but can produce lasting modifications to gonads when compensation of T3 and T4 levels occurs by thyroid follicle hyperplasia. Perchlorate may therefore affect vertebrate development via both thyroidal and non-thyroidal mechanisms.

Acclimation temperature affects the metabolic response of amphibian skeletal muscle to insulin.

Frog skeletal muscle mainly utilizes the substrates glucose and lactate for energy metabolism. The goal of this study was to determine the effect of insulin on the uptake and metabolic fate of lactate and glucose at rest in skeletal muscle of the American bullfrog, Lithobates catesbeiana, under varying temperature regimens. We hypothesize that lactate and glucose metabolic pathways will respond differently to the presence of insulin in cold versus warm acclimated frog tissues, suggesting an interaction between temperature and metabolism under varying environmental conditions. We employed radiolabeled tracer techniques to measure in vitro uptake, oxidation, and incorporation of glucose and lactate into glycogen by isolated muscles from bullfrogs acclimated to 5 °C (cold) or 25 °C (warm). Isolated bundles from Sartorius muscles were incubated at 5 °C, 15 °C, or 25 °C, and in the presence and absence of 0.05 IU/mL bovine insulin. Insulin treatment in the warm acclimated and incubated frogs resulted in an increase in glucose incorporation into glycogen, and an increase in intracellular [glucose] of 0.5 µmol/g (P<0.05). Under the same conditions lactate incorporation into glycogen was reduced (P<0.05) in insulin-treated muscle. When compared to the warm treatment group, cold acclimation and incubation resulted in increased rates of glucose oxidation and glycogen synthesis, and a reduction in free intracellular glucose levels (P<0.05). When muscles from either acclimation group were incubated at an intermediate temperature of 15 °C, insulin's effect on substrate metabolism was attenuated or even reversed. Therefore, a significant interaction between insulin and acclimation condition in controlling skeletal muscle metabolism appears to exist. Our findings further suggest that one of insulin's actions in frog muscle is to increase glucose incorporation into glycogen, and to reduce reliance on lactate as the primary metabolic fuel.

Leeches run cold, then hot.

Food processing is costly, potentially limiting the energy and time devoted to other essential functions such as locomotion or reproduction. In ectotherms, post-prandial thermophily, the selection of a warm environmental temperature after feeding, may be advantageous in minimizing the duration of this elevated cost. Although present in many vertebrate taxa, this behaviour had not previously been observed in invertebrates. Sanguivorous leeches ingest large blood meals that are costly to process and limit mobility until excess fluid can actively be expelled to reduce body volume. When presented with a temperature gradient from 10°C to 30°C, leeches select a temperature that is significantly warmer (24.3 ± 0.9°C, n = 6) than their acclimation temperature (T(a), 21°C). Unfed leeches preferred temperatures that were significantly cooler than ambient (12.8 ± 0.9°C, n = 6). This behavioural strategy is consistent with minimizing the time course of elevated post-feeding energy costs and reducing energy expenditure during fasting. Our observations raise the possibility that thermoregulatory behaviour of this type is an unrecognized feature of other invertebrate taxa.

Acute pesticide poisoning in the U.S. retail industry, 1998-2004.

OBJECTIVE: This study was conducted to describe the national magnitude and characteristics of acute pesticide poisoning among workers and customers in retail establishments. METHODS: Analyses included retail employees 15-64 years of age and customers with acute pesticide poisoning identified from the Sentinel Event Notification System for Occupational Risks-Pesticides (SENSOR-Pesticides) and California Department of Pesticide Regulation from 1998 to 2004. Pesticide poisoning incidence rates and incidence rate ratios (IRR) were calculated. RESULTS: A total of 325 cases of acute pesticide poisoning were identified. Of these cases, 287 (88%) were retail employees and 38 (12%) were customers. Overall, retail employees had a significantly lower acute pesticide poisoning incidence rate compared with non-agricultural, non-retail employees (IRR=0.53; 95% confidence interval 0.47, 0.59). However, significantly elevated pesticide poisoning incidence rates were observed for four retail occupations (janitors, stock handlers/baggers, bakery/deli clerks, and shipping/receiving handlers). In addition, workers employed in two retail industry sectors (farm supply stores and hardware stores) had significantly elevated acute pesticide poisoning incidence rates. Incidence rates among the retail employees demonstrated a quadratic trend, monotonically decreasing from 1998 to 2000 and monotonically increasing from 2000 to 2003. The rates appear to have leveled off in 2003 and 2004. CONCLUSIONS: Preventive measures to decrease acute pesticide poisoning incidence in the retail sector include adoption of unbreakable and tear-resistant container requirements, increased utilization of integrated pest management strategies, and advisement to store managers, employees, and customers about poisoning prevention.

Correlates of physical activity among pregnant women in the United States.

INTRODUCTION: Physical activity recommendations for pregnant and nonpregnant women have been issued, but little data exist to compare the extent that these women are meeting the recommendation levels. METHODS: A population-based, cross-sectional study using data from the 1994, 1996, 1998, and 2000 Behavioral Risk Factor Surveillance System evaluated the physical activity recommendations met by pregnant and nonpregnant women. The study population included women who were 18-44 yr of age. Random digit dialing, telephone surveys were used to assess all information. Pregnant and nonpregnant women were categorized into five mutually exclusive groups based upon their level of physical activity in the past month: vigorous activity (meeting guidelines) moderate activity (meeting guidelines), moderate or vigorous activity (not meeting guidelines), irregular activity, or no physical activity. RESULTS: Nonpregnant women were more likely than pregnant women to meet the vigorous or moderate physical activity recommendations. Walking was the most common activity among pregnant and nonpregnant women (52 and 45%, respectively). Pregnant women meeting the moderate or vigorous physical activity recommendations were more likely to be younger, nonhispanic white, more educated, not married, nonsmokers, and to have higher incomes. CONCLUSION: Many pregnant women do not appear to be meeting the physical activity recommendations. Healthcare providers should further encourage the promotion of physical activity during uncomplicated pregnancies.

The effect of oxygen and adenosine on lizard thermoregulation.

A regulated decrease in internal body temperature (Tb) appears to play a protective role against metabolic disruptions such as exposure to ambient hypoxia. This study examined the possibility that Tb depression is initiated when low internal oxygen levels trigger the release of adenosine, a neural modulator known to influence thermoregulation. We measured selected Tb of Anolis sagrei in a thermal gradient under varied ambient oxygen conditions and following the administration of the adenosine receptor antagonist 8-cyclopentyltheophylline (CPT). The average decrease in Tb observed following exposure to hypoxia (<10% O2) and following exhaustive exercise were 5 degrees and 3 degrees C, respectively, suggesting a role of oxygen availability on initiation of regulated hypothermia. When A. sagrei were run to exhaustion and recovered in hyperoxic (>95% O2) conditions, exercise-induced Tb depression was abolished. Administration of CPT similarly abolished decreased Tb due to both exercise and hypoxia. Trials using Dipsosaurus dorsalis indicate that elevated ambient oxygen during exercise does not influence blood pH or lactate accumulation, suggesting that these factors do not initiate changes in thermoregulatory setpoint following exhaustive exercise. We suggest that when oxygen is limiting, a decrease in arterial oxygen may trigger the release of adenosine, thereby altering the thermoregulatory setpoint.