The Intensive Care Lifeboat: a survey of lay attitudes to rationing dilemmas in neonatal intensive care.

BACKGROUND: Resuscitation and treatment of critically ill newborn infants is associated with relatively high mortality, morbidity and cost. Guidelines relating to resuscitation have traditionally focused on the best interests of infants. There are, however, limited resources available in the neonatal intensive care unit (NICU), meaning that difficult decisions sometimes need to be made. This study explores the intuitions of lay people (non-health professionals) regarding resource allocation decisions in the NICU. METHODS: The study design was a cross-sectional quantitative survey, consisting of 20 hypothetical rationing scenarios. There were 119 respondents who entered the questionnaire, and 109 who completed it. The respondents were adult US and Indian participants of the online crowdsourcing platform Mechanical Turk. Respondents were asked to decide which of two infants to treat in a situation of scarce resources. Demographic characteristics, personality traits and political views were recorded. Respondents were also asked to respond to a widely cited thought experiment involving rationing. RESULTS: The majority of respondents, in all except one scenario, chose the utilitarian option of directing treatment to the infant with the higher chance of survival, higher life expectancy, less severe disability, and less expensive treatment. As discrepancy between outcomes decreased, however, there was a statistically significant increase in egalitarian responses and decrease in utilitarian responses in scenarios involving chance of survival (P = 0.001), life expectancy (P = 0.0001), and cost of treatment (P = 0.01). In the classic 'lifeboat' scenario, all but two respondents were utilitarian. CONCLUSIONS: This survey suggests that in situations of scarcity and equal clinical need, non-health professionals support rationing of life-saving treatment based on probability of survival, duration of survival, cost of treatment or quality of life. However, where the difference in prognosis or cost is very small, non-health professionals preferred to give infants an equal chance of receiving treatment.

Inhibition of nitrification in soil by metal diethyldithiocarbamates.

Nitrification acts as a key process in determining fertilizer use efficiency by crops as well as nitrogen losses from soils. Metal dithiocarbamates in addition to their pesticidal properties can also inhibit biological oxidation of ammonium(nitrification) in soil. Metal [M = V(III), Cr(III), Mn(II), Fe(III), Ni(II), Cu(II), Zn(II) and Co(II)] diethyldithiocarbamates (DEDTC) were synthesized by the reaction of sodium diethyldithiocarbamate with metal chloride in dichloromethane/water mixture. These metal diethyldithiocarbamates were screened for their ability to inhibit nitrification at different concentrations( 10 microg/g soil, 50 microg/g soil and 100 microg/g soil). With increasing concentration of the complex, capacity to retard nitrification increased but the extent of increase varied for different metals. At 100 microg/g soil, different complexes showed nitrification inhibition from 22.36% to 46.45% . Among the diethyldithiocarbamates tested, Zn(DEDTC)2 proved to be the most effective nitrification inhibitor at 100 microg/g soil. Manganese, iron and chromium diethyldithiocarbamates also proved to be effective nitrification inhibitors than the others at 100 microg/g soil. The order of percent nitrification inhibition in soil by metal diethyldithiocarbamates was: Zn(II) > Mn(II) > Fe(III) > Cr(III) > V(III) > Co(II) > Ni(II) > Cu(II).

Peripheral levels of inflammatory mediators in migraineurs during headache-free periods.

OBJECTIVES: The present study investigated the peripheral inflammatory changes of the trigeminovascular system by measuring the inflammatory mediators leukotriene B4 (LTB(4)), prostaglandin E2 (PGE(2)), and thromboxane B2 (TXB(2)) in the nasal fluid, as well as saliva, of patients with migraine. BACKGROUND: Migraine has been hypothesized to be as a result of changes in the peripheral or central nervous system or both. It is still unclear whether peripheral changes in the trigeminovascular system are involved in the pathogenesis of migraine. METHODS: Participants were 18 subjects, 9 patients with migraine and 9 controls, matched for age and sex. Each subject took part in one experimental session during which nasal lavage fluid and saliva samples were collected. These samples were analyzed by competitive enzyme immunoassay using goat anti-rabbit polyclonal antibody. RESULTS: With the exception of TXB(2), correlational analyses indicated good correlations between results obtained using nasal lavage or saliva (LTB(4), r(18) = 0.91; PGE(2), r(18) = 0.95). When comparing inflammatory mediators measured in controls and migraineurs, the LTB(4) level was significantly lower in migraineurs, while no differences were found for PGE(2) and TXB(2). CONCLUSIONS: The study demonstrated that nasal lavage, a noninvasive method, can be easily used for investigations of pathophysiological mechanisms of migraine. In addition, the results may indicate that there is no peripheral trigeminal sensitization in the headache-free period of migraineurs compared with controls when PGE(2), LTB(4), and TXB(2) in saliva and nasal lavage samples are measured.

Adolescents with ASCUS: are they a high risk group?

Population demographics, risk behaviors, and compliance rates for the management of an ASCUS (atypical squamous cells of undetermined significance) diagnosis are not well studied in the adolescent population. From June 1994 to December 1996, 1,175 Papanicalou (pap) smears were performed in an urban adolescent clinic on patients age 12 to 18. Of these, 124 (10.5%) were diagnosed with ASCUS or ASCUS with a qualifying statement. A retrospective chart review (n=83) and telephone interview was performed on patients with ASCUS. Ninety-nine percent of enrollees were African American. Comparisons were made between those patients with normal pap smears and those with ASCUS. No statistically significant difference existed pertaining to age at pap smear, age at menarche, age at first coitus, and education level. A positive association was found in the ASCUS group for the presence of sexually transmitted diseases (P < 0.001), number of sexual partners (P < 0.0007), and pregnancy (P < 0.001). Of the 80% of patients who had an ASCUS diagnosis and were referred for colposcopy (n = 62), only 61% attended their appointment (n = 38). Thirty-nine percent of these patients were aware of an abnormal diagnosis after colposcopy. For those that attended colposcopy, 56% were accompanied by a parent. For those who were not compliant with attendance, none cited parental consent for the procedure as a barrier to obtaining treatment. Adolescent females in an urban setting with multiple sexual partners, history of sexually transmitted diseases, and prior pregnancy are at a greater risk for ASCUS on cervicovaginal smear when compared to their age-matched controls. In addition, the adolescent compliance rate for colposcopy is low. We, therefore, recommend that these adolescent females be observed diligently.

Maternal plasma corticotropin-releasing hormone associated with stress at 20 weeks' gestation in pregnancies ending in preterm delivery.

OBJECTIVE: This study tested the hypothesis that maternal stress is associated with elevated maternal levels of corticotropin releasing hormone and activation of the placental-adrenal axis before preterm birth. STUDY DESIGN: In a behavior in pregnancy study, 524 ethnically and socioeconomically diverse women were followed up prospectively and evaluated at 3 gestational ages: 18 to 20 weeks, 28 to 30 weeks, and 35 to 36 weeks. Maternal variables included demographic data, medical conditions, perceived stress level, and state anxiety. Maternal plasma samples were collected at each gestational age. Eighteen case patients with spontaneous onset of preterm labor were matched against 18 control subjects who were delivered at term, and their samples were assayed for corticotropin-releasing hormone, adrenocorticotropic hormone, and cortisol by means of radioimmunoassay. Statistical tests were used to examine mean differences in these hormones. In addition, the relationship between stress level and each hormone was tested with a Pearson correlation coefficient and hierarchic multiple regressions in each group. RESULTS: Patients who had preterm delivery had significantly higher plasma corticotropin-releasing hormone levels than did control subjects at all 3 gestational ages (P <.0001). Analyses did not find any differences in reported levels of stress between 18 to 20 weeks' gestation and 28 to 30 weeks' gestation. A hierarchic multiple regression indicated that maternal stress level at 18 to 20 weeks' gestation and maternal age accounted for a significant amount of variance in corticotropin-releasing hormone at 28 to 30 weeks' gestation, after controlling for corticotropin-releasing hormone at 18 to 20 weeks' gestation (P <. 001). In addition, patients who were delivered preterm had significantly elevated plasma levels of adrenocorticotropic hormone at all 3 gestational ages (P <.001) and significantly elevated cortisol levels at 18 to 20 weeks' gestation and 28 to 30 weeks' gestation (P <.001). CONCLUSION: Maternal plasma levels of corticotropin-releasing hormone are significantly elevated at as early as 18 to 20 weeks' gestation in women who are subsequently delivered preterm. Changes in corticotropin-releasing hormone between 18 to 20 weeks' gestation and 28 to 30 weeks' gestation are associated with maternal age and stress level at 18 to 20 weeks' gestation. Maternal stress and corticotropin-releasing hormone levels may be potential markers for the patient at risk for preterm birth. Activation of the placental maternal pituitary-adrenal axis is consistent with the classic endocrine response to stress.

Corticotrophin-releasing hormone and CRH-binding protein. Differences between patients at risk for preterm birth and hypertension.

BACKGROUND: During pregnancy in the second and third trimester there is a progressive rise in plasma CRH thought to be secreted by the placenta. Plasma CRH-BP inactivates CRH, which may prevent its peripheral action on the maternal pituitary and myometrium. In the last few weeks of pregnancy CRH-BP decreases, thereby causing an increase in free CRH or a CRH/CRH-BP complex available to play a role in the onset of parturition. OBJECTIVE: We tested the hypothesis that differences in CRH, CRH-BP, or a CRH/CRH-BP complex in patients at risk for preterm birth (PTB) and hypertension (HYP) account for the differences in the timing of parturition. METHODS: From a Behavior in Pregnancy Study database, we identified 18 patients who had spontaneous PTB and 23 patients who developed HYP. Both groups were case controlled and matched with patients who delivered at term (Normal). Maternal plasma samples had been appropriately collected from these patients at 18-20, 28-30, and 35-36 weeks gestational age. CRH levels were measured by double antibody RIA kit and the CRH-BP by a immunoradiometric technique. A CRH-BP/CRH dimer complex index was calculated. Statistical analysis was done using Kruskal-Wallis test for two cases. RESULTS: Maternal CRH (pg/ml) in the PTB cases compared to the HYP cases was significantly elevated at all three time periods. Maternal CRH-BP (pg/ml) in the PTB versus HYP cases was significantly lower at all three time periods in the PTB cases compared to the HYP cases. Maternal CRH-BP/CRH dimer complex index was significantly lower in the PTB cases at all three time periods than either the controls or the HYP cases, suggesting excessive CRH. The mean GA at delivery for the PTB cases was significantly lower than the control or HYP cases. CONCLUSIONS: These results suggest that those patients at risk for PTB have significantly elevated CRH, lower CRH-BP, and a reduced CRH-BP/CRH dimer complex index at all three time periods of assessment.

Atypical squamous cells of undetermined significance in the pediatric population. Implications for management and comparison with the adult population.

OBJECTIVE: To determine the significance of an atypical squamous cells of undetermined significance (ASCUS) diagnosis in patients 18 years or younger. STUDY DESIGN: From June 1994 to June 1995, 630 cervicovaginal smears were performed on patients 18 years or younger (mean age 16.4, range 14-18) at University Hospitals of Cleveland. Of these patients, 69 (10.9%) were diagnosed with ASCUS or ASCUS with a qualifying statement. Follow-up cervicovaginal smears, biopsies and charts were reviewed for a 12-18-month period following the initial diagnosis of ASCUS. RESULTS: The study population was sexually active: 63% were gravid, 21% were multigravid, 68% had a history of sexually transmitted diseases (STDs), and 32% had multiple STDs. Follow-up cervicovaginal smears or biopsies were obtained on 46 patients (32 cervicovaginal smears and 14 biopsies/endocervical curettage cases). Mild to moderate dysplasia was identified in 21.6% of patients (10.8% on cervicovaginal smears and 10.8% on biopsies), and a repeat diagnosis of ASCUS was given in 37%. In patients with a repeat diagnosis of ASCUS, a follow-up cervicovaginal smear or biopsy revealed dysplasia in an additional 13%. The overall rate of dysplasia was 34.7%. CONCLUSION: Regardless of age, the diagnosis of ASCUS in a sexually active patient population has significant implications. Furthermore, we recommend that these patients be managed the same way as high-risk adult patients.

Long-term nitric oxide blockade in the pregnant rat: effects on blood pressure and plasma levels of endothelin-1.

OBJECTIVE: Abnormalities in the production of nitric oxide and endothelin-1 have been implicated in the development of preeclampsia. We postulated that long-term nitric oxide synthase inhibition with L-nitro-arginine methyl ester would induce sustained hypertension, a rise in plasma levels of endothelin-1, and fetal growth restriction. STUDY DESIGN: Conscious virgin and pregnant Sprague-Dawley rats received infusions of vehicle or L-nitro-arginine methyl ester (2.5 mg/kg/hr) for 11 days. Mean arterial pressure was assessed serially. On day 21 of gestation (or equivalent in virgin rats) plasma was collected for endothelin-1 levels; pup weight and litter size were determined. Data were analyzed with analysis of variance and regression techniques. RESULTS: Mean arterial pressure was constant in virgin control rats (n = 7) but declined in pregnant control rats (n = 11) as gestation advanced. Nitric oxide synthase inhibition in virgin (n = 10) and pregnant (n = 11) rats caused sustained elevations in mean arterial pressure (165 +/- 7 vs 100 +/- 3 mm Hg, L-nitro-arginine methyl ester vs control virgin rats, p < 0.0001; 149 +/- 5 vs 91 +/- 2 mm Hg, L-nitro-arginine methyl ester vs control pregnant rats, p < 0.0001). L-nitro-arginine methyl ester induced a rise in plasma endothelin-1 levels in virgin (4.4 +/- 0.1 vs 3.5 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001) and pregnant rats (3.0 +/- 0.1 vs 2.6 +/- 0.1 pg/ml, L-nitro-arginine methyl ester vs control, p < 0.0001). Pregnant rats had lower endothelin-1 levels than did virgin rats (p < 0.0001). Mean arterial pressure and endothelin-1 were significantly correlated in pregnant rats. L-nitro-arginine methyl ester decreased pup weight (2.4 +/- 0.4 vs 3.7 +/- 0.2 gm/pup/litter, L-nitro-arginine methyl ester vs control, p < 0.01) and litter size (6.6 +/- 1.3 vs 10.2 +/- 0.9 pups/litter, L-nitro-arginine methyl ester vs control, p < 0.05). CONCLUSIONS: Long-term nitric oxide synthase blockade causes sustained hypertension, elevated levels of endothelin-1, and fetal growth restriction. Although the endocrine and pressor effects are not unique to pregnancy, this model clearly induces some of the changes seen in preeclampsia and may be useful for studying specific interventions.

Adenosine modulates hypoxia-induced atrial natriuretic peptide release in fetal sheep.

The effects of adenosine on atrial natriuretic peptide (ANP) secretion were determined in chronically catheterized fetal sheep (> 0.8 term). Adenosine was infused into the the right jugular vein for 1 h at 8 +/- 0.4 (5 fetuses), 160 +/- 8 (6 fetuses), and 344 +/- 18 micrograms.min-1.kg estimated fetal wt-1. Fetal arterial blood gases and pH were generally unaffected by adenosine, although mean arterial CO2 tension increased transiently by 2-5 Torr and pH fell progressively during the highest rate of infusion. During the intermediate and high infusion rates, fetal hemoglobin concentrations increased by 11-13% and mean fetal heart rate rose by 18% from a control value of approximately 167 beats/min. Mean arterial pressure was not affected during adenosine infusion. Adenosine significantly increased fetal plasma ANP levels, with maximum concentrations 1.80, 2.36, and 2.51 times greater than control means (142-166 pg/ml) for the respective infusion rates of 8, 160, and 344 micrograms.min-1.kg estimated fetal wt-1. In seven fetuses, reducing fetal arterial O2 tension by approximately 9-10 Torr from a control of 23 +/- 1.3 Torr increased plasma ANP concentrations approximately 2.4 times the control mean of 176 pg/min. Adenosine-receptor blockade with 8-(p-sulfophenyl)-theophylline reduced by 50% the maximum hypoxia-induced rise in plasma ANP concentrations. It is concluded that adenosine causes a dose-dependent rise in fetal plasma ANP concentrations and modulates fetal ANP release during hypoxia.

Utilisation of computers for 1991 census data--the issues and the status.

"This article focuses on the various possible advantages and the issues involved in the use of microcomputers in census data processing. While highlighting the advantages, the present limitations and the factors to be viewed for caution are also...described. Finally, the 1991 [Indian] Census publication and data dissemination programme...[is] given."

Atrial natriuretic peptide metabolism during pregnancy in the rat.

OBJECTIVE: Our purpose was to determine whether plasma clearance rates and production rates of atrial natriuretic peptide 99-126 are altered during pregnancy in the rat. STUDY DESIGN: Twelve virgin and 12 late-pregnant chronically instrumented, conscious, unrestrained Sprague-Dawley rats were studied. Mean arterial pressure, heart rate, and plasma atrial natriuretic peptide levels were measured before and during a 40-minute continuous infusion of atrial natriuretic peptide (10 ng/kg/min). RESULTS: Control mean arterial pressure was 106 +/- 5 mm Hg in virgin rats versus 97 +/- 4 mm Hg in pregnant rats. Atrial natriuretic peptide infusion did not significantly affect mean arterial pressure in either group of animals but decreased heart rate in virgin rats. Basal plasma atrial natriuretic peptide levels were significantly higher in virgin than in pregnant rats (107 +/- 10 vs 78 +/- 7 pg/ml, respectively, p < 0.05). Atrial natriuretic peptide infusion significantly increased plasma levels in both groups to similar (183 +/- 19 and 154 +/- 14 pg/ml, virgin vs pregnant rats). Calculated plasma clearance rates were similar in virgin and pregnant rats (166 +/- 27 vs 155 +/- 17 ml/kg/min). Estimated production rates of atrial natriuretic peptide were higher in virgin then in pregnant rats (15.1 +/- 1.4 vs 11.4 +/- 1.1 ng/kg/min, p < 0.05). CONCLUSIONS: Plasma atrial natriuretic peptide levels are lower in chronically instrumented near-term pregnant rats compared with levels in virgin rats. This is not related to differences in plasma atrial natriuretic peptide clearance rates but rather to a decrease in production rates in late pregnancy.

Endothelium-derived relaxing factor inhibition and the pressor response to norepinephrine in the pregnant rat.

OBJECTIVE: To determine whether endothelium-derived relaxing factor (EDRF) plays a role in the blunted pressor response to norepinephrine that is characteristic of normal pregnancy. METHODS: Eleven pregnant (mean +/- standard error of the mean 18 +/- 1 days of gestation) and 11 virgin conscious, unrestrained Sprague-Dawley rats with long-term indwelling vascular catheters were studied. Mean arterial pressure (MAP) and heart rate were measured in response to continuous infusions of either vehicle (5% dextrose) or increasing concentrations of norepinephrine (25, 100, and 200 ng/kg/minute) before and after administration of NG-monomethyl-L-arginine (LNMMA), a specific inhibitor of EDRF synthesis. RESULTS: Baseline MAP was lower in pregnant than in virgin rats (96 +/- 3 versus 105 +/- 3 mmHg; P < .05). Before LNMMA administration, the pregnant rats exhibited a significantly blunted pressor response to increasing concentrations of norepinephrine compared to that of virgin rats (P < .005). Given alone, LNMMA produced a greater increase in baseline MAP in virgin rats than in pregnant rats (rise in MAP of 44 +/- 2 versus 31 +/- 2 mmHg; P < .001). However, LNMMA abolished the blunted pressor response to norepinephrine in the pregnant animals and did not significantly affect the pressor response to norepinephrine in virgin rats. Heart rate responses to increasing concentrations of norepinephrine in the presence and absence of LNMMA were not significantly different in the two groups of animals. CONCLUSION: Stimulated EDRF production may contribute to the blunted pressor response to norepinephrine characteristic of pregnancy in the rat.

Effect of percutaneous transluminal coronary angioplasty on circulating endothelin levels.

Percutaneous transluminal coronary angioplasty (PTCA) is frequently associated with vasoconstriction involving large vessels as well as microcirculation, but the potential mechanisms remain poorly defined. In this study, we tested the hypothesis that endothelial disruption during PTCA is associated with an increase in circulating levels of endothelin, a potent endothelium-derived vasoconstrictor peptide. Circulating levels of endothelin and other potential vasoactive mediators such as atrial natriuretic factor, epinephrine and norepinephrine were measured immediately before and after PTCA in 23 patients with coronary artery disease. Although there was no change in the endothelin levels after angiography alone (43 +/- 5 vs 44 +/- 7 pg/ml, p = 0.5), there was a significant increase after PTCA (32 +/- 8 to 37 +/- 10 pg/ml, p < 0.005). The increase in endothelin was associated with a significant increase in atrial natriuretic factor (78 +/- 57 to 129 +/- 131 ng/ml, p = 0.01) and a decrease in epinephrine and norepinephrine levels (111 +/- 64 to 59 +/- 36 pg/ml, p = 0.005, and 1,131 +/- 500 to 811 +/- 311 pg/ml, p = 0.003, respectively). Circulating levels of endothelin did not correlate with the percent coronary stenosis before or after PTCA or the presence or absence of angiographically visible thrombus. These findings suggest that endothelial injury during PTCA may be associated with increased circulating levels of endothelin and its counter-regulatory hormone, atrial natriuretic factor, and also with a reciprocal decrease in epinephrine and norepinephrine levels. Thus, these humoral changes may modulate changes in coronary vascular tone after PTCA.

Effect of pregnancy on the vasodepressor response to atrial natriuretic factor.

OBJECTIVE: We attempted to determine whether pregnancy alters the vasodepressor response to both physiologic and pharmacologic infusions of atrial natriuretic factor 99-126. STUDY DESIGN: Ten virgin and 10 pregnant (17 +/- 1 days of gestation) conscious, unrestrained Sprague-Dawley rats with chronic indwelling vascular catheters were studied. Mean arterial pressure and heart rate were measured in response to steady-state infusions of either saline solution or increasing concentrations of atrial natriuretic factor (range 5 to 2560 ng.kg-1.min-1). RESULTS: Basal mean arterial pressure was significantly lower in pregnant rats than in virgin rats (89 +/- 3 vs 97 +/- 2 mm Hg, p < 0.02). Atrial natriuretic factor induced significant dose-dependent decreases in mean arterial pressure and heart rate in virgin and pregnant rats (p < 0.001). The hypotensive effects of atrial natriuretic factor were blunted in the pregnant rats only in response to the highest concentrations of atrial natriuretic factor administered (-27 +/- 3 mm Hg in pregnant rats vs -43 +/- 3 mm Hg in virgin rats, p < 0.005). CONCLUSIONS: The vasodepressor response to physiologic infusions of atrial natriuretic factor was not affected by pregnancy status. However, pharmacologic infusions of atrial natriuretic factor resulted in a blunted vasodepressor response in the pregnant animals. This may be due to alterations in vascular atrial natriuretic factor receptors, changes in the clearance rate of atrial natriuretic factor, or the modulating effects of other vasoactive hormones.

Atrial natriuretic factor: the effects of pregnancy and a high-salt diet on atrial levels.

The chronic and relatively acute changes in blood volume that occur during pregnancy and post partum may be associated with alterations in the content of atrial natriuretic factor in the atria. We measured the concentration of atrial natriuretic factor in the right and left atria of virgin, pregnant, and postpartum Sprague-Dawley rats by radioimmunoassay as well as the concentration of atrial natriuretic factor in the atria and plasma of term pregnant rats on a high-salt diet. Neither right nor left atrial concentrations of atrial natriuretic factor were elevated during pregnancy in animals on a normal diet, but both were increased during the first 2 days after delivery. Term pregnant rats on a high-salt diet showed a small increase in atrial natriuretic factor levels in the left atria only, without any change in plasma atrial natriuretic factor levels. We conclude that relatively acute changes in fluid and electrolyte balance are more likely than chronic ones to be associated with alterations in atrial natriuretic factor concentrations in the atria.

Perinatal factors influencing atrial natriuretic peptide levels in umbilical arterial plasma at the time of delivery.

Little is known about atrial natriuretic peptide metabolism or secretion in the human fetus. The purpose of this study was to determine if both the placenta and umbilical vessels are possible sites of atrial natriuretic peptide metabolism and to evaluate the effects that labor, route of delivery, prolonged pregnancy, preeclampsia, and fetal distress have on umbilical arterial atrial natriuretic peptide levels. We found that plasma atrial natriuretic peptide levels in the umbilical artery are significantly greater than those in the vein (p less than 0.001). Umbilical arterial and umbilical venous atrial natriuretic peptide levels were higher in plasma samples collected immediately at delivery when compared with those obtained 10 minutes later (p less than 0.001). Umbilical arterial atrial natriuretic peptide levels were elevated in pregnancies complicated by preeclampsia and fetal distress (p less than 0.01). Labor, route of delivery, and prolonged pregnancy had no effect on umbilical arterial atrial natriuretic peptide levels. We propose that both the placenta and umbilical vessels contain atrial natriuretic peptide receptors that are involved in the clearance or metabolism of atrial natriuretic peptide. The increased umbilical arterial atrial natriuretic peptide levels present in preeclampsia and fetal distress may reflect an attempt by the fetus to regulate blood flow.

Plasma atrial natriuretic peptide levels during the rat estrous cycle, pregnancy, and puerperium.

The rat has been used as a model for studying the changes that occur in maternal blood volume and renal function during pregnancy. The role, if any, that atrial natriuretic peptide plays in regulating these changes is unknown, and little information is available on atrial natriuretic peptide levels at different stages of gestation in the rat. In this study we measured plasma atrial natriuretic peptide levels by radioimmunoassay in the rat at each stage of the estrous cycle, during the last 2 weeks of pregnancy, and in the early postpartum period. Atrial natriuretic peptide levels did not change during the estrous cycle. Atrial natriuretic peptide levels were low on days 10 to 15 of gestation but rose to become significantly higher than nonpregnant levels on days 16 to 18. On day 21 shortly before delivery, levels were similar to nonpregnant values. Postpartum, atrial natriuretic peptide levels rose immediately and remained elevated for the next 48 hours. These findings suggest that factors other than blood volume may mediate plasma atrial natriuretic peptide levels during pregnancy and the postpartum period.

Adult body weight of indigenous and crossbred ewes under semi-arid conditions in India.

Data on adult body weight of ewes belonging to Nali, Chokla breeds and their crosses (F1) with Rambouillet and Soviet Merino raised under semi-arid conditions in India were analysed. The ewes belonged to 5 distinct age groups ranging from 16.5 to 64 months. Nali and Chokla were significant lighter than all the 4 crossbred groups. There were no significant differences in body weight between crossbred groups except in the case of Soviet Merino x Chokla group which was the lightest and differed significantly from all other groups. Rambouillet crosses were heavier than Merino crosses but the difference was statistically significant only on Rambouillet x Chokla and Merino x Chokla. The improvement in body weight in crossbreds over native sheep ranged between 9.3 and 21.88%. The increase in live weight was significant only up to 49 months.