Experiences of Daily Weighing Among Successful Weight Loss Individuals During a 12-Month Weight Loss Study.

The purpose of the study was to describe participants' experience of daily weighing and to explore factors influencing adherence to daily weighing among individuals who were successful in losing weight during a behavioral weight loss intervention. Participants completed a 12-month weight loss intervention study that included daily self-weighing using a Wi-Fi scale. Individuals were eligible to participate regardless of their frequency of self-weighing. The sample ( N = 30) was predominantly female (83.3%) and White (83.3%) with a mean age of 52.9 ± 8.0 years and mean body mass index of 33.8 ± 4.7 kg/m2. Five main themes emerged: reasons for daily weighing (e.g., feel motivated, being in control), reasons for not weighing daily (e.g., interruption of routine), factors that facilitated weighing, recommendations for others about daily weighing, and suggestions for future weight loss programs. Our results identified several positive aspects to daily self-weighing, which can be used to promote adherence to this important weight loss strategy.

Alternative technique or mitigating strategy for sevoflurane-induced neurodegeneration: a randomized controlled dose-escalation study of dexmedetomidine in neonatal rats.

BACKGROUND: Brain injury in newborn animals from prolonged anaesthetic exposure has raised concerns for millions of children undergoing anaesthesia every yr. Alternative anaesthetic techniques or mitigating strategies are urgently needed to ameliorate potentially harmful effects. We tested dexmedetomidine, both as a single agent alternative technique and as a mitigating adjuvant for sevoflurane anaesthesia. METHODS: Neonatal rats were randomized to three injections of dexmedetomidine (5, 25, 50, or 100 µg kg -1 every 2 h), or 6 h of 2.5% sevoflurane as a single agent without or with dexmedetomidine (1, 5, 10, or 20 µg kg -1 every 2 h). Heart rate, oxygen saturation, level of consciousness, and response to pain were assessed. Cell death was quantified in several brain regions. RESULTS: Dexmedetomidine provided lower levels of sedation and pain control than sevoflurane. Exposure to either sevoflurane or dexmedetomidine alone did not cause mortality, but the combination of 2.5% sevoflurane and dexmedetomidine in doses exceeding 1 µg kg -1 did. Sevoflurane increased apoptosis in all brain regions; supplementation with dexmedetomidine exacerbated neuronal injury, potentially as a result of ventilatory or haemodynamic compromise. Dexmedetomidine by itself increased apoptosis only in CA2/3 and the ventral posterior nucleus, but not in prefrontal cortex, retrosplenial cortex, somatosensory cortex, subiculum, lateral dorsal thalamic nucleaus, or hippocampal CA1. CONCLUSIONS: We confirm previous findings of sevoflurane-induced neuronal injury. Dexmedetomidine, even in the highest dose, did not cause similar injury, but provided lesser degrees of anaesthesia and pain control. No mitigation of sevoflurane-induced injury was observed with dexmedetomidine supplementation, suggesting that future studies should focus on anaesthetic-sparing effects of dexmedetomidine, rather than injury-preventing effects.

Increased secretion of exopolysaccharide and virulence potential of a mucoid variant of Salmonella enterica serovar Montevideo under environmental stress.

During an investigation to increase the recovery of Salmonella enterica from Oregano, an increased expression of exopolysaccharide was induced in Salmonella serovar Montevideo. The atypical mucoid (SAL242S) and the non-mucoid (SAL242) strains of Montevideo were compared and characterized using various methods. Serotyping analysis demonstrated that both strains are the same serovar Montevideo. Electron microscopy (EM) of cultured SAL242S cells revealed the production of a prominent EPS-like structure enveloping aggregates of cells that are composed of cellulose. Mucoid cells possessed a higher binding affinity for Calcofluor than that of the non-mucoid strain. Genotypic analysis revealed no major genomic differences between these morphotypes, while expression analyses using a DNA microarray shows that the mucoid variant exhibited heightened expression of genes encoding proteins produced by the SPI-1 type III secretion system. This increased expression of SPI1 genes may play a role in protecting Salmonella from environmental stressors. Based on these observations, Salmonella serovar Montevideo mucoid variant under stressful or low-nutrient environments presented atypical growth patterns and phenotypic changes, as well as an upregulated expression of virulence factors. These findings are significant in the understanding of survival abilities of Salmonella in a various food matrices.

Patterns of self-weighing behavior and weight change in a weight loss trial.

BACKGROUND/OBJECTIVES: Regular self-weighing has been associated with weight loss and maintenance in adults enrolled in a behavioral weight loss intervention; however, few studies have examined the patterns of adherence to a self-weighing protocol. The study aims were to (1) identify patterns of self-weighing behavior; and (2) examine adherence to energy intake and step goals and weight change by self-weighing patterns. SUBJECTS/METHODS: This was a secondary analysis of self-monitoring and assessment weight data from a 12-month behavioral weight loss intervention study. Each participant was given a scale that was Wi-Fi-enabled and transmitted the date-stamped weight data to a central server. Group-based trajectory modeling was used to identify distinct classes of trajectories based on the number of days participants self-weighed over 51 weeks. RESULTS: The sample (N=148) was 90.5% female, 81.1% non-Hispanic white, with a mean (s.d.) age of 51.3 (10.1) years, had completed an average of 16.4 (2.8) years of education and had mean body mass index of 34.1 (4.6) kg m(-2). Three patterns of self-weighing were identified: high/consistent (n=111, 75.0% self-weighed over 6 days per week regularly); moderate/declined (n=24, 16.2% declined from 4-5 to 2 days per week gradually); and minimal/declined (n=13, 8.8% declined from 5-6 to 0 days per week after week 33). The high/consistent group achieved greater weight loss than either the moderate/declined and minimal/declined groups at 6 months (-10.19%±5.78%, -5.45%±4.73% and -2.00%±4.58%) and 12 months (-9.90%±8.16%, -5.62%±6.28% and 0.65%±3.58%), respectively (P<0.001). The high/consistent group had a greater mean number days per week of adherence to calorie intake goal or step goal but not higher than the moderate/declined group. CONCLUSIONS: This is the first study to reveal distinct temporal patterns of self-weighing behavior. The majority of participants were able to sustain a habit of daily self-weighing with regular self-weighing leading to weight loss and maintenance as well as adherence to energy intake and step goals.

Comparison of a PCR serotyping assay, Check&Trace assay for Salmonella, and Luminex Salmonella serotyping assay for the characterization of Salmonella enterica identified from fresh and naturally contaminated cilantro.

Salmonella enterica isolated from fresh cilantro samples collected through the USDA/AMS Microbiological Data Program (MDP) were used to compare a PCR serotyping assay against the Check&Trace assay and the Luminex (BioPlex) Salmonella serotyping assay. The study was conducted to evaluate the effectiveness of the three methods for serotyping Salmonella from both enrichment broth cultures and pure Salmonella cultures. In this investigation, Salmonella spp. serotyping was conducted using 24 h enrichment broth cultures and pure Salmonella cultures from cilantro samples, with the PCR serotyping assay. Conversely, the Check&Trace and Luminex for Salmonella assays required pure cultures for Salmonella serotyping. The cilantro samples contained S. enterica serovar Montevideo, Newport, Saintpaul, and Tennessee, identified by the PCR serotyping assay and Check&Trace for Salmonella, but the Luminex assay only identified two of the four serotypes of the cilantro samples. The anticipated impact from this study is that the PCR serotyping assay provides a time- and cost-effective means for screening, identifying and serotyping Salmonella using DNA extracted from 24 h enrichment cilantro samples.

Ethnicity predicts perceptions of smoking and smoking cessation among veterans.

The objective of this study was to determine if race/ethnicity predicts motivation to quit smoking and preferences for cessation services among smokers serviced by a primarily psychiatric Veterans Affairs hospital. A self-administered survey was given to a convenience sample of smokers (n=146) at the Battle Creek Veterans Affairs Medical Center. Univariate, bivariate and multivariate regression analyses were calculated to determine the association between race/ethnicity and motivation to quit smoking. Forty-two per cent of the sample was non-white. Non-white patients smoked significantly less cigarettes per day as compared with white patients (P=0.002). In the multivariate analyses, compared with whites, non-whites had 3.5 times greater odds of thinking that quitting smoking was extremely/very important to health (P= 0.01), 4.0 times greater odds of thinking of quitting using tobacco products in the next 30 days (P=0.004) and 3.4 times greater odds of being interested in receiving smoking cessation services (P=0.007). Yet, non-white patients were less likely to be interested in intensive nurse counselling and cessation medications. As the number of non-whites continues to increase in the military, novel strategies may be needed to capitalize on the high motivation to quit smoking and preference for non-traditional interventions among non-white smokers treated in Veterans Affairs hospitals.

Comparison between pulsed-wave Doppler- and tissue Doppler-derived Tei indices in fetuses with and without congenital heart disease.

OBJECTIVES: The aim of this study was to compare the right (RV) and left (LV) ventricular Tei indices obtained by pulsed-wave Doppler (PD) and tissue Doppler (TD) methods in fetuses with structurally normal and abnormal hearts. METHODS: This was a retrospective cross-sectional study of 147 fetuses that had a fetal echocardiogram and Tei index measured during a 2-year period. The RV and LV Tei indices were measured using both PD and TD methods. The difference between the two methods of Tei index measurement was tested using paired sample t-test, Pearson correlation coefficient was used to examine their relationship, and the agreement between the methods was tested using Bland-Altman analysis. RESULTS: A total of 87 fetuses had normal hearts and 60 had a congenital heart defect. Both PD and TD Tei indices were measured successfully from at least one ventricle in 123 cases and from both ventricles in 110 cases. The mean TD Tei index was significantly higher than the mean PD Tei index for both ventricles (P < 0.0001). There was a weak but statistically significant correlation between the PD and TD Tei indices of the right ventricle (r = 0.20, P = 0.029), whereas the PD and TD Tei indices of the left ventricle did not correlate significantly (r = 0.04, P = 0.684). When pairs of Tei indices measured by two different methods (123 pairs for the right ventricle and 111 for the left ventricle) were tested with Bland-Altman analysis, the bias and precision were 0.147 and 0.254, respectively, for the right ventricle, and 0.299 and 0.276, respectively, for the left ventricle. CONCLUSIONS: Correlation between Tei indices measured by PD and TD methods is weak and the agreement between individual measurements is poor. Therefore, they should not be used interchangeably in the assessment of fetal cardiac function.

Prediction of outcome of fetal congenital heart disease using a cardiovascular profile score.

OBJECTIVES: Congestive heart failure in fetuses with congenital heart defects (CHD) is associated with high perinatal mortality. The clinical condition can be characterized by five ultrasound markers that comprise the 10-point cardiovascular profile (CVP) score. Our aim was to assess the value of the CVP score in evaluating the condition and in maintaining surveillance of fetuses with CHD. METHODS: We evaluated retrospectively 131 singleton pregnancies with a diagnosis of fetal CHD, which had been assessed by serial echocardiographic examinations, during which the CVP score was obtained. Fetal and neonatal outcomes, including perinatal mortality and Apgar scores, were assessed. RESULTS: Fetuses with a final CVP score or= 8 (87.5% vs. 15.2% mortality; P < 0.0001, chi square = 24.5). Significance was maintained after controlling for birth weight, lag time between the final examination and delivery and the dichotomized 5-min Apgar score (odds ratio, 22.3; P = 0.024). For low Apgar score and mortality, the CVP score had low sensitivity (0.25 and 0.27, respectively) but high specificity (0.98 and 0.99, respectively). The presence of hydrops and severe cardiomegaly were statistically significantly associated with mortality (P < 0.05). CONCLUSIONS: Fetuses with CHD and a CVP score below 8 are at risk of perinatal death. The CVP score may be used to assess the severity of fetal CHD and to plan perinatal management.

Parental perception of children's weight in a paediatric primary care setting.

OBJECTIVE: To determine how parents of overweight children perceived their children's weight status compared with actual body mass index (BMI). METHODS: This descriptive, cross-sectional study assessed parental perception of and concern about weight, diet and physical activity of 3-12-year-olds. BMI values >or=85th and <95th percentile and >or=95th percentile were considered at risk for overweight and overweight respectively. Differences between groups were tested with chi-squared analyses or Fishers exact test as appropriate and further explored using logistic regression analysis. RESULTS: Questionnaires were completed at 612 health maintenance visits (278 girls). Overall, 15% of both boys and girls were at risk for overweight and 22% of boys and 24% of girls were overweight. Forty-nine per cent of parents recognized their overweight children as overweight. Perceptions were more often correct for parents of girls than boys (63% versus 36%, P < 0.001) and for older compared with younger children (61.7% versus 17.5%, P < 0.001). CONCLUSIONS: Parents of overweight children frequently did not perceive their children as exceeding healthy weight standards. Targeting parental perception as a point of intervention is necessary.

Cognitive deficits in school-age children with severe short bowel syndrome.

BACKGROUND/PURPOSE: Improved therapies for the management of short bowel syndrome (SBS) have resulted in the prolonged survival of many children. By early childhood, the physiological sequelae of severe SBS include delayed physical development and metabolic imbalances. However, little is known about how SBS affects brain development. Although many parents report school problems, no controlled study has evaluated the integrity of the central nervous system in SBS children. The purpose of this study was to investigate the neuropsychological status of school-aged SBS children to determine if there were characteristic cognitive impairments that might be amenable to early therapeutic intervention. METHODS: SBS children (n = 8; mean age, 116.9 +/- 21 months) were compared with an age-matched cystic fibrosis (CF) control group (n = 8; mean age, 118.1 +/- 14 months). Groups did not differ in age, grade, or absences. Neuropsychological tests with established sensitivity to CNS integrity compared performance over 6 cognitive domains. Emotional status also was measured. Analyses were completed with 2-tailed t tests. RESULTS: Groups did not differ on tests of intellectual ability and emotional function. Language, memory and learning, and problem-solving testing results indicated no significant group differences. However, the SBS group performed more poorly on measures assessing visual-spatial ability, with P values ranging from .002 to .045. In a subset of subjects, we noted significantly slower left-handed, but not right-handed, performance on measures of finger dexterity and psychomotor speed. CONCLUSIONS: Although emotional status did not differ from that of children with CF, SBS patients showed visual-spatial deficits in the company of preserved language, attention and memory, and executive skills. The specificity and consistency of these findings suggests that right hemisphere CNS changes may occur in children with SBS. This unexpected finding, coupled with the indication of left-sided psychomotor slowing in right-handed subjects, raises the possibility that actual brain impairment, rather than developmental delay accompanying slowed physical growth, accounts for these findings. Longitudinal studies are needed to further clarify this issue. The educational significance of the results is discussed.

Diagnostic status and symptomatic behavior of hard-to-manage preschool children in middle childhood and early adolescence.

Followed 2 cohorts of hard-to-manage preschool children and comparison children without early problems to middle childhood and early adolescence. Children with early problems, especially problems that were still evident at school entry, were more likely to meet diagnostic criteria for an externalizing diagnosis at follow-up. Hard-to-manage children in Cohort 1 with problems that persisted from ages 3 through 9 years were much more likely to meet diagnostic criteria at age 13 than children whose early problems were less stable in elementary school. Similarly, hard-to-manage boys in Cohort 2 whose problems persisted at age 6 were more likely to meet criteria for an externalizing diagnosis at age 9 than hard-to-manage boys whose problems appeared less stable at age 6. Across cohorts, children with persistent problems had higher levels of symptoms and more varied symptoms at ages 3 and 4 and over the course of development.

Regional variation in radionuclide concentrations and radiation dose in caribou (Rangifer tarandus) in the Canadian Arctic; 1992-94.

Gamma-emitting radionuclides and 210Po, an alpha-emitting product of the 238U decay chain, were analysed in tissues from 16 caribou (Rangifer tarandus) collections in the Canadian North between 1992 and 1994. The study was conducted to determine the regional variability of anthropogenic and natural radionuclides in Canadian caribou, and to estimate the background radiation dose to caribou tissues. 137Cs, 40K, 210Pb and 210Po were consistently found in most herds. Mean muscle 137Cs varied from below detection limits on Banks Island to 231 Bq kg-1 wet weight (ww) in the Beverly herd in the central Arctic. Comparison of 1992-94 levels with published values from the 1960s and 1980s showed that 137Cs in caribou is declining with an effective half-life (Teff) of 9.9 years. The highest mean bone and liver 210Pb activities were observed on south Baffin Island, which included one bone sample with 3800 Bq kg-1 ww of 210Pb and 3070 Bq kg-1 ww of 210Po. The distribution of 137Cs and 210Pb between herds was attributed to higher atmospheric deposition rates between 60 and 65 degrees N, and changes in plant community structure and lichen species composition. The highest mean absorbed dose (30 mGy year-1) was observed in 1993 in the liver of caribou from Lake Harbour. This dose translated into a weighted absorbed dose of 300 mGy year-1, assuming a radiation weighting factor (wR) of 10 to account for the increased biological efficiency of alpha particles for deterministic effects. The Lake Harbour site also had the highest individual weighted absorbed dose in bone (810 mGy year-1) and liver (530 mGy year-1) in the study. There was no significant relationship between bone 210Pb activity and age for individual or pooled herds, indicating that the estimated doses are probably present throughout the lifetime of the caribou. Because some herds number several hundred thousand individuals, collective doses may also be very high. As yet, there have been no reports of observable effects due to these relatively high exposures and many of the herds continue to thrive and increase in size.

Testosterone autoregulation of its biosynthesis in the rat testis: inhibition of 17 alpha-hydroxylase activity.

Using the in vitro perfused rat testis, the effects of testosterone (T) on its own biosynthesis, and in particular on the inhibition of specific steroidogenic step(s) in the biosynthetic pathway from cholesterol to T, were examined. Rat testes perfused in vitro for 1 hour with medium containing 1.5 microM T secreted significantly less T than control testes in response to physiologic or maximal luteinizing hormone (LH) stimulation. To locate the site(s) of this rapid inhibition, the effects of arterial T infusion on steroidogenesis by testes also infused with pregnenolone (PREG), progesterone (PROG), 17 alpha-hydroxyprogesterone (17-PROG), or androstenedione (ADIONE) were measured by summing all the possible reaction products from each substrate. This approach allowed us to examine the effect of T in situ on the reactions: LH-stimulated PREG secretion; PREG to PROG; PROG to 17-PROG; 17-PROG to ADIONE; and ADIONE to T. Only PROG to 17-PROG (17 alpha-hydroxylase activity) was inhibited by arterial T infusion. A kinetic examination of the PROG to 17-PROG reaction demonstrated that the specific inhibition by T was competitive. The apparent km for PROG in this system was 16.0 microM, whereas the apparent ki of T was 1.6 microM, indicating a relatively high degree of sensitivity of the reaction to T. Taken together, these data confirm that T is able to regulate its own synthesis and indicate that this autoregulation is the result of rapid, specific inhibition by T of 17 alpha-hydroxylase activity.

Hamster Leydig cells are less sensitive to ethane dimethanesulfonate when compared to rat Leydig cells both in vivo and in vitro.

It has been reported that ethane dimethanesulfonate (EDS) is a Leydig cell toxicant that affects rats and hamsters (Kerr et al., 1987), while, in contrast, the Leydig cells of mice are relatively insensitive to the toxicant. In the rat, there is a rapid decline in levels of testosterone (T) within hours after EDS administration. However, T production, spermiogenesis, and fertility are restored within a few weeks as new Leydig cells are formed from undifferentiated cells in the interstitium of the testis. In an earlier study, we found, as expected, that ejaculated sperm counts (ESCs) reached a nadir 10 days after adult rats were dosed with EDS at 65 mg/kg ip along with serum and testicular T, testis and seminal vesicle weights, and in vitro T production, while, in contrast, EDS at 65 mg/kg had no effect on these endpoints in the Syrian hamster (Gray et al., 1992). In the current study, when EDS was administered to 6, 12, and 18 month old hamsters at 100 mg/kg, it produced subtle effects on serum T and sex accessory gland weights, while dramatic effects were seen in similarly exposed rats. In addition, when testes were examined by light microscopy all treated rats displayed severely reduced Leydig cell numbers, while, in contrast, only one-third of the EDS-treated hamsters were affected, having moderately reduced Leydig cell numbers. In support of the histological data, 3 beta-HSD enzyme activity was reduced by 99% of control in EDS-treated rats, but it was reduced by only 35% of control in EDS-treated hamsters. An in vitro analysis of the effects of EDS on LH-stimulated T production by quartered testes demonstrated that the hamster testis was less sensitive to the direct effects of EDS than the rat testis. The IC50 after 3 hr in culture was greater than 1800 micrograms EDS/ml for the hamster quarter testes, while the IC50 for the rat quarter testes was 320 micrograms EDS/ml. In summary, these results demonstrate in vivo and in vitro that Leydig cells of hamsters are less sensitive to EDS than those of the adult rat.

The requirement of the testis in establishing the sensitivity of the canine prostate to develop benign prostatic hyperplasia.

A long-term study on the requirement of the testis in establishing the sensitivity of the canine prostate to develop benign prostatic hyperplasia (BPH) was conducted using 23 aging beagles both with and without their testes. The dogs had received long-term restoration of testosterone and estrogen through silicone implants. When young beagles (0.5 to 1 year of age) were castrated and normal serum testosterone and estrogen levels restored during aging to 5 years, only 50% of these dogs developed BPH in the absence of their testes as opposed to 100% BPH development in intact controls. In addition, two-thirds of the prostates in the treated groups were remarkably reduced in size, being smaller than any prostate observed in the intact controls. If, following castration, the steroid restoration was withheld for 4 years during aging and subsequently administered starting at 5 years of age and continuing for a 6-month period, none of the animals developed complex BPH. Moreover, two-thirds of the prostate glands were reduced in size by more than 60% and were atrophied in spite of the maintenance of normal prostatic tissue dihydrotestosterone levels. Regardless of the time of steroid restoration to a castrate beagle, the periurethral zone of the canine prostate exhibits various degrees of atrophy indicating functional regions within the canine prostate that are sensitive to the requirements of the testes during aging. This study implicates the importance of the testis in increasing the probability and/or sensitivity for the full development of canine BPH.

In vivo model for chronic direct intratesticular drug administration.

The efficacy and toxicity of a new method for chronic direct intratesticular drug infusion were assessed in a rat model. To this end, luteinizing hormone (LH) or buffer was infused via miniosmotic pumps for 14 days directly into the parenchyma of Copenhagen rat testes. The surgical manipulation and direct infusion of buffer did not have any apparent adverse effect upon either spermatogenesis or steroidogenesis as measured by testis weight, homogenization-resistant spermatid count, and in vitro response of the testes to a maximally stimulating concentration of LH. Histologic studies revealed only a localized inflammatory response in the testis around the Silastic tubing leading from the mini-osmotic pump to the testis. The biologic efficacy of direct infusion into the testis was assessed by determining the ability of mini-osmotic pump-infused LH to maintain steroidogenesis for 14 days in animals whose pituitary function was suppressed by simultaneous subcutaneous placement of testosterone/estradiol capsules. Steroidogenesis was found to be maintained quantitatively in testes infused with an appropriate dose of LH. At a given LH dose, the directly infused testes were found to produce fivefold more testosterone than contralateral testes and 10-fold more testosterone than testes from rats receiving systemic administration of the same dose of LH. We conclude that the miniosmotic pump system is a useful means to chronically administer a high concentration of LH, and presumably other agents, to the testis without any significant adverse effects.

Hard-to-manage preschool boys: symptomatic behavior across contexts and time.

Preschool boys identified by their parents and/or teachers as active, inattentive, and impulsive (N = 69) at age 4 were compared with boys without problems (N = 43) on observational measures of symptom-related behaviors, obtained across contexts (home, laboratory, and preschool). Problem boys differed from comparison boys on measures of activity/inattention, noncompliance, and impulsivity obtained in the 3 settings. At a 2-year follow-up, when they were 6 years old, problem boys continued to differ from comparison boys on laboratory measures of activity and impulsivity; there also was some stability in these symptomatic behaviors. Implications of these findings for the emergence and persistence of externalizing problems in preschool boys are addressed.

Effects of ethane dimethanesulfonate (EDS) on adult and immature rabbit Leydig cells: comparison with EDS-treated rat Leydig cells.

Ethane-dimethanesulfonate (EDS) has been shown to selectively kill Leydig cells and depress testosterone production in adult rats. A recent study has shown that immature rat Leydig cells are less sensitive to EDS exposure. There is evidence that the rabbit metabolizes EDS to methane sulfonic acid more rapidly than does the rat, reducing exposure to the parent compound. In the study reported here, we examined the effects of EDS on the Leydig cells in both adult and immature rabbits and compared the effects found with those previously reported in the rat. In vivo, EDS exposure demonstrated that Leydig cells from adult rabbits were affected, with both serum and interstitial testosterone production depressed. EDS effects in adult rabbits and rats were compared by exposing explants of testicular parenchyma to EDS in vitro and evaluating testosterone production. With this procedure, the rabbit testis was less sensitive to EDS treatment than the rat, with a 50% reduction rate (EC50) achieved with 2026 microM EDS for the rabbit and with 336 microM EDS for the rat. Perfusion of adult and immature rabbit testis with 430 microM EDS demonstrated the insensitivity of the immature testis to EDS exposure: adult testosterone production was reduced 50% in 3.5 h, whereas no diminution was found in the immature rabbit. EDS exposure of interstitial cell preparations further demonstrated the insensitivity of immature rabbit Leydig cells, with an EC50 of 4397 microM compared to an EC50 of 1137 microM EDS in adult preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of [14C]ethane dimethanesulfonate in immature and adult male rats following an acute exposure.

In the adult rat, ethane dimethanesulfonate (EDS) reduces testosterone (T) production by killing Leydig cells. Studies have also shown that acute EDS administration produces transient infertility and epididymal effects. Although these later effects were believed to be indirect results of the reduced Leydig cell T production, it was recently found that the epididymal effects were partially a direct result of in vivo EDS treatment. In contrast to the Leydig cells of the adult rat, immature Leydig cells are affected by EDS only at doses four- to sixfold higher than those that affect mature Leydig cells. In fact, the Leydig cells of the adult rat seem to be uniquely susceptible to the cytotoxic effects of EDS. Steroidogenesis in other organs, like the adrenal and ovary, are unaffected in vivo at doses that eliminate T production in males. In addition, studies have shown that doses of EDS that kill Leydig cells in vitro, isolated from the testes of adult rats, have no effect on similarly exposed hepatocytes. Hence, it was the objective of this study to describe the distribution and temporal fate of EDS in target (testes and epididymides) and nontarget tissues in immature and adult male rats and to determine if this information would explain either the age- or tissue-related susceptibility to EDS. We have concluded from this study that tissue distribution, integrated in vivo EDS dose, and differences in EDS metabolism are not the only factors contributing to the difference in sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial tachycardia in infants and children: electrocardiographic classification and its significance.

An electrocardiographic classification of atrial tachycardia and its significance in children has not been reported. We reviewed the clinical histories and 12-lead surface electro-cardiograms (ECG) of 21 children with atrial tachycardia. Atrial rate and P-wave axis were determined for each patient. Some patients had features of typical atrial flutter (AF). Tachycardia was classified by atrial rate < 340/min or atrial rate > 340/min. Children with atrial tachycardia rate > 340/min consistently responded to conservative treatment (digoxin and/or cardioversion) without recurrences (p < 0.05 and p > 0.025); whereas in children with atrial rate < 340/min, only one case responded to conservative therapy. P-wave axis had no prognostic significance for either group. Additionally, high atrial rate (> 340/min) during tachycardia was noted in early infancy, compared to older children and adults, and probably represents the function of age. Classification of atrial tachycardia by rate is clinically useful for planning therapy and predicting response in children.