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Field boundaries as barriers to movement of hover flies (Diptera: Syrphidae) in cultivated land.

Field boundaries play an important role as refuges, food sources and corridors for invertebrates and vertebrates, and increasing farmland fragmentation impacts on these functions. However, hedgerows and other structures can also impede dispersal by flying insects. The current work uses the pollen of Phacelia tanacetifolia in hover fly guts as a marker to assess hover fly movement in farm landscapes. In the United Kingdom and New Zealand, Phacelia pollen was found in the guts of Ephisyrphus balteatus and Metasyrphus corollae (United Kingdom) and Melanostoma fasciatum (New Zealand) at distances up to 200 m from the source, when there were no barriers between the flowers and the traps used to catch the flies. The rate of decline over distance in the proportion of flies containing pollen was similar for the two countries. The extent to which four replicated field boundary types impeded hover fly movement was tested using post-and-wire fences, lines of poplars (Populus spp.) with gaps, dense poplars and controls (no potential barriers). Phacelia was planted on one side of each boundary, and along the centre of the control plots. The relative presence of the pollen in flies on both sides of the barriers showed that both types of poplar boundary restricted the movement of the flies, but the fence had no effect. In a separate experiment, gravid females of M. fasciatum were captured at a greater height on a shade-cloth fence than were non-gravid females and males. The implications of this work include the functioning and persistence of metapopulations and the influence of field boundaries on population recovery of beneficial invertebrates following pesticide-induced mortality. If field boundaries contribute to a temporal asynchrony between pest and natural enemy populations, this needs to be considered along with the well-established roles of boundaries as refugia for, and sources of, beneficial arthropods.

Agriculture↗

Oral administration of theophylline to modify pressor responsiveness to angiotensin II in women with pregnancy-induced hypertension.

Normally, women become refractory to the pressor effects of infused angiotensin-II (A-II) early in pregnancy. Gravid women destined to develop pregnancy-induced hypertension (PIH) lose this refractoriness to A-II several weeks prior to the detection of hypertension. Normal pregnant women also lose their A-II refractoriness after treatment with prostaglandin synthetase inhibitors and, in this regard become similar to gravid women who are destined to develop PIH. From this observation, we have concluded that a prostaglandin(s) or a prostaglandin-related substance(s) is likely involved in the mediation of vascular reactivity to A-II during pregnancy. The present study was conducted to ascertain if control of vascular reactivity during pregnancy also involves the cyclic nucleotides. Since theophylline is known to inhibit the action of phosphodiesterase, an action that results in increased cellular levels of cyclic 3',5'-adenosine monophosphate (cAMP), we evaluated the effective pressor dose of A-II before and after the administration of theophylline to women with mild PIH who were beyond the 28th week of gestation. The effective pressor dose of A-II in these women with PIH before theophylline treatment was 7.3 +/- 1.4 ng. times kg.(-1) times min.(-1) (mean and standard error). Following treatment of these women with the equivalent of 500 mg. of theophylline daily for four days, the effective pressor dose of A-II was 16.7 +/- 3.8 ng. times kg.(-1) times min.(-1) (p less than 0.025). These findings are consistent with the view that a prostaglandin(s) synthesized in the arteriole may modulate the vascular refractoriness to A-II by altering the intracellular level of cAMP in vascular tissues.

Angiotensin II↗

Oligohydramnios: clinical associations and predictive value for intrauterine growth retardation.

Intrauterine growth retardation (IUGR) is difficult to diagnose before birth. Sonographically diagnosed oligohydramnios has been reported to be highly sensitive and reliable in detecting IUGR in carefully prescreened patients. To evaluate the clinical associations of oligohydramnios and its usefulness as a method of antenatal screening for IUGR on a large obstetric service, the consecutive ultrasound examinations of 2,453 viable singleton pregnancies with intact membranes were surveyed. The 96 (3.9%) pregnancies found to be complicated by oligohydramnios were compared with 96 with the same biparietal diameters, but with normal volumes of amniotic fluid. Mothers with oligohydramnios were younger, of lower parity, and at increased clinical risk for IUGR. Of 96 infants from oligohydramnios-complicated pregnancies, 38 (40%) were small for gestational age (SGA), compared with eight (8%) infants from pregnancies without oligohydramnios. Of 46 SGA births, 38 (83%) were preceded by sonographically diagnosed oligohydramnios (p less than 0.0001). IUGR associated with oligohydramnios tended to occur in young hypertensive gravid women, whereas non-oligohydramnios-associated IUGR tended to occur in gravid women with low prepregnancy weight. With correction for the incidences of oligohydramnios and IUGR in the unselected population, it is shown that four in 10 cases of oligohydramnios would result in SGA births (40% predictive value of an abnormal test), but that only 16% of SGA births would be preceded by sonographically diagnosed oligohydramnios. Eighty-four percent of the cases would be missed. These results suggest that, although the presence of oligohydramnios should increase the clinician's index of suspicion for IUGR, routine sonographic screening to detect oligohydramnios is not warranted.

Adolescent↗

Effect of hypertonic saline on vascular responses to angiotensin II in pregnancy.

Refractoriness to infused angiotensin II is characteristic or normal human and ovine pregnancy; the mechanisms responsible are unclear. In this study, we sought to ascertain in gravid sheep whether hypertonic saline solution alters the vascular responses to angiotensin II, as in gravid women, and to compare the responses of the systemic and uteroplacental vasculature. Dose-response curves were determined. Mean arterial pressure and systemic vascular resistance increased in a dose-dependent fashion before and after hypertonic saline solution; responses were greater after hypertonic saline solution (p less than 0.01). Responses of cardiac output, heart rate, uterine vascular resistance, and uterine blood flow also were dose-dependent, but were unchanged after hypertonic saline solution. Plasma renin activity fell 45% after hypertonic saline solution. Treatment with hypertonic saline solution results in increased pressor responses to angiotensin II that are not a reflection of altered baroreceptor or chemoreceptor reflexes or of the response in the uteroplacental vascular bed. Rather, the increased systemic vascular responsiveness to angiotensin II after hypertonic saline solution appears to be a reflection of other mechanisms, such as alterations in vessel wall dynamics or receptor affinity.

Angiotensin II↗

Calcium levels in normal and hypertensive pregnant patients.

Epidemiologic studies of hypertension in nonpregnant patients have suggested that abnormal calcium metabolism contributes to the genesis of hypertension. We have studied serum ionized calcium, total calcium, phosphorus, magnesium, total protein, and albumin in 16 normal pregnant women, 12 gravid patients with chronic hypertension, and 31 gravid patients with pregnancy-induced hypertension. In contradistinction to the reported difference in ionized calcium between nonpregnant normal and hypertensive patients, we have found no difference in serum ionized calcium between our groups.

Adult↗

Screening for carbohydrate intolerance in pregnancy: a comparison of two tests and reassessment of a common approach.

The usefulness of glycosylated hemoglobin as a prenatal screening test for carbohydrate intolerance was studied in 806 consecutive subjects by correlating glycosylated hemoglobin to 1-hour post-50 gm Glucola plasma glucose levels, 3-hour oral glucose tolerance tests, and perinatal and maternal outcomes. Sixty-seven subjects whose 1-hour post-50 gm Glucola plasma glucose levels were greater than or equal to 150 mg/100 ml underwent 3-hour oral glucose tolerance tests; 12 were diagnostic of carbohydrate intolerance. Compared to carbohydrate-tolerant control subjects, gravid patients with carbohydrate intolerance were older, more obese, had higher 1-hour post-50 gm Glucola plasma glucose and glycosylated hemoglobin levels, and infants with increased birth weight percentiles, depressed 5-minute Apgar scores, and an increased incidence of shoulder dystocia and perinatal mortality. Three of 10 carbohydrate-intolerant patients who were evaluated post partum were found to have previously undiagnosed diabetes. Division of measurements of 1-hour post-50 gm Glucola plasma glucose and glycosylated hemoglobin into normal, borderline, and suspicious groups demonstrated a reduction in discriminatory capability of glycosylated hemoglobin as compared to the 1-hour post-50 gm Glucola plasma glucose. We conclude that laboratory screening for carbohydrate intolerance should be a standard element of the prenatal evaluation; gravid patients found to have carbohydrate intolerance should be reevaluated post partum to rule out overt diabetes, and the 1-hour post-50 gm Glucola plasma glucose test is the preferred means of routine screening for carbohydrate intolerance in pregnancy.

Adult↗

Calcium/creatinine ratio and microalbuminuria in the prediction of preeclampsia.

Eighty-eight normotensive gravid women between 24 and 34 weeks of gestation underwent urine evaluation for the presence of microalbuminuria and urinary calcium excretion (calcium/creatinine ratio). Preeclampsia subsequently developed in 83% of patients with a high level of microalbuminuria (greater than or equal to 11 micrograms/ml) and a low calcium/creatinine ratio (less than or equal to 0.04). Conversely, 94% of women who did not demonstrate high microalbuminuria and a low calcium/creatinine ratio remained normotensive at the time of delivery. These results suggest that changes in renal function are present in gravid women who are otherwise free of symptoms in whom preeclampsia will eventually develop. Testing for microalbuminuria and a calcium/creatinine ratio may be a useful screening tool in predicting the subsequent development of preeclampsia.

Albuminuria↗

Plasma exchange for preeclampsia. I. Postpartum use for persistently severe preeclampsia-eclampsia with HELLP syndrome.

The postpartum use of plasma exchange with fresh-frozen plasma was assessed in a group of seven women with severe preeclampsia-eclampsia and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count) that persisted greater than 72 hours after delivery. During the study interval in which a total of 107 gravid women with HELLP syndrome were seen in our referral center, these seven patients (6.5%) demonstrated persistent thrombocytopenia (platelet count usually less than 30,000/mm3), rising lactic dehydrogenase (greater than 1000 IU/L) and evidence of multiorgan dysfunction. The seven case histories emphasize the variety of clinical and laboratory profiles that can be encountered in this small group of gravid women at risk for severe morbidity or mortality. Up to three 3 L plasma exchanges were required to effect permanent disease arrest and reversal. Utilization of the IBM 2997 Cell Separator system permitted bedside performance of procedures with enhanced convenience and optimal medical management. Successful plasma exchange was associated with (1) sustained increases in the mean platelet count at 24, 48, and 72 hours that were 2.2, 3.6, and 4.5 times the preexchange platelet counts and (2) a decreasing trend in lactic dehydrogenase concentrations below 1000 IU/L within 48 hours of exchange plasmapheresis. The current series of patients supports our recommendation that a trial of plasma exchange(s) with fresh-frozen plasma be considered for treatment of the infrequent postpartum case of HELLP syndrome that fails to abate within 72 hours of delivery and in which other evidence develops of an ongoing, widespread, and life-threatening thrombotic microangiopathy.

Adolescent↗

A prospective, randomized comparison of the Pipelle endometrial sampling device with the Novak curette.

This prospective, randomized study compares sample adequacy, pain associated with endometrial biopsy, and correlation of endometrial histologic sampling with hysterectomy histologic results in specimens obtained by the Pipelle (Unimar Inc., Wilton, Conn.) device (N = 149) and the Novak (Miltex, Inc., Lake Success, N.Y.) curette (N = 126). During a 2-year period, patients with abnormal uterine bleeding seen in our ambulatory care facility were enrolled in this trial, unless they did not wish to participate or had a positive pregnancy test result. Patients in both groups were similar with respect to mean gravidity, parity, and menopausal status, although patients in the Novak group were older (43.4 vs 39.1 years, p = 0.005). Patients undergoing Novak biopsy had a mean pain score of 4.36 with 22 of 126 (17%) reporting severe pain, whereas patients undergoing Pipelle biopsy had a mean pain score of 3.21 with only 10 of 149 (6.7%) reporting severe pain (p less than 0.05). These pain scores were not affected by menstrual day, gravidity, parity, or menopausal status. Insufficient tissue was reported in 12.8% of patients in the Pipelle group compared with 9.5% in the Novak group (p greater than 0.05). Fifty patients underwent subsequent hysterectomy. In 48 of 50 (96%), the pathologic results at hysterectomy were in agreement with the histologic findings at endometrial sampling. This clinical trial suggests that Pipelle biopsy appears to be as effective as the Novak curette in obtaining an adequate specimen for histologic analysis and is associated with less pain.

Biopsy↗

Reconsideration of the effects of selfing on the viability of Hymenolepis nana.

A single cysticercoid of Hymenolepis nana was orally administered to an SPF-ICR strain mouse which was congenitally free of H. nana. Gravid proglottids of the resulting adult worm (parental generation) were fed to flour beetles, Tribolium confusum. Six or 14 days later, one cysticercoid from the beetles was fed to each mouse. Gravid proglottids were subsequently recovered and fed to beetles as above. This procedure was repeated for more than 20 generations. H. nana can survive repeated selfing and has been maintained for at least 27 generations. No decrease in the proportion of cysticercoids into adults with repeated selfing was observed in our experiments. Our results appear to conflict somewhat with results reported previously. This discrepancy may be due to a difference in mice used as experimental hosts, although some other causal factors, e.g. fluctuation of infective rate or difference in the varieties of H. nana strain used cannot be excluded.

Animals↗

Insulin resistance of late pregnancy does not include the liver.

Hyperinsulinemia was required to preserve normal intravenous glucose tolerance in late pregnancy in the rat (18 to 21 days' gestation). To evaluate the site and mechanism of this insulin resistance, insulin binding and action were measured in hepatocytes freshly isolated from control and gravid animals. As expected, glucose concentrations were lower, insulin levels were higher, and hepatocyte size increased in the pregnant animals. Insulin binding was similar in liver cells from the two groups. No difference was found in sensitivity or responsiveness of insulin-stimulated net 14C-glucose incorporation into glycogen in the hepatocytes from the control and gravid rats. These results suggest that the well-documented, but ill-defined, insulin antagonism of late pregnancy does not include the liver and is a postreceptor defect, most likely residing in muscle tissue.

Alanine↗

Ovarian and plasma PGE and PGF levels in naturally ovulating brook trout (Salvelinus fontinalis) and the effects of indomethacin on prostaglandin levels.

Plasma and ovarian levels of PGE and PGF were measured by radioimmunoassay in naturally ovulating brook trout (Salvelinus fontinalis). At 12 hours post-ovulation, PGF levels in plasma and ovarian tissue were significantly elevated over levels in gravid controls. Plasma PGF levels were still elevated 5-7 days post-ovulation. Indomethacin treatment (10 micrograms/gm body weight) of ovulatory brook trout significantly decreased plasma and ovarian PGF levels by 12 hours post-ovulation. No significant differences were observed in plasma PGE levels, though gravid controls contained significantly elevated ovarian PGE levels as compared to ovulated fish.

Animals↗

Effects of prostaglandin F2 alpha prostaglandin E2 and arachidonic acid on the induction of oviposition in vivo and in vitro in oviparous lizards.

Gravid females of four different species of oviparous lizard were treated in vivo with varying doses of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 or arachidonic acid (AA). In contrast to previous studies examining birds and viviparous lizards, no dosage induced oviposition in any of the treated females. All females, however, did exhibit behaviors associated with oviposition. Intact oviducts removed from gravid females and placed in organ culture did oviposit when treated with 30 or 100 ng PGF2 alpha/ml of culture media. Arachidonic acid at similar concentrations also was effective in stimulating birth. These data suggest that prostaglandins can stimulate oviposition in oviparous lizards but further suggest that their action may be inhibited by oviducal innervation until just prior to natural birth.

Animals↗

Fetal development and gestational changes in Bos taurus and Bos indicus genotypes in the tropics.

Weights of the gravid uterus and fetus as well as the fetal measurements were determined at slaughter for 107 Bos taurus cows grazed on improved pastures and for 70 Bos indicus cows grazed on native pastures in northern Australia. The stage of gestation was assessed from palpation per rectum in early-to-mid gestation and at slaughter and from fetal development characteristics at slaughter. The age and breed of the cow and the sex of the fetus did not significantly affect any of the uterine components or fetal measurements. Growth curves had dominant, positive linear components but negative quadratic ones, which improved the fit, particularly for the later stages of gestation. Uterine components and fetal measurements were highly correlated (0.94 to 0.99). For Bos taurus cows, there were higher estimates at birth for weights of the gravid uterus and the fetus, but estimates for other fetal measurements were similar to those for Bos indicus cows. Major fetal growth occurred during the third trimester, with the length of the foreleg tending to change relatively slowly and the head width quite fast during the first trimester. Correction factors for cow liveweight to adjust to commonality for non-pregnancy were 5, 7, 10, 14, 20, 29, 43 and 65 kg for Bos taurus and 2, 4, 6, 10, 15, 23, 35 and 51 kg for Bos indicus at 2 to 9 months of gestation.

Journal Article↗

Biodegradable estradiol microspheres do not affect uterine involution or characteristics of postpartum estrus in mares.

Quarterhorse mares were used to investigate effects of estradiol-17beta on uterine involution, duration of estrus, interval to ovulation, and fertility achieved by breeding on the first postpartum estrus. On the day of foaling, mares were injected with biodegradable poly (DL-lactide) microspheres containing either 100 mg estradiol-17beta (25 mares) or no drug (27 mares). The treatment period was considered to last for 12 to 15 d. Estrus was determined by teasing mares (n=16) with a stallion. Ovulation was detected by transrectal ultrasonographic examination of ovaries (n=48). On Days 6, 11 and 16 post partum, transrectal ultrasonography was used to measure cross-sectional diameters of the uterine body, uterine horns, and fluid within the uterine lumen (n=28). Uteri were swabbed for bacteriologic culture, and uterine biopsies were obtained from the previously gravid uterine horn on Days 11 and 16 post partum, for assessment of endometritis and morphometric analysis of endometrial histioarchitecture (n=19). Twenty-two mares were bred on foal-heat, and pregnancy was determined by transrectal ultrasonography on 14 to 16 and 30 to 35 d after breeding. With only one exception (diameter of previously gravid uterine horn on Day 11), mean values for all measures of uterine involution did not differ between treatment groups (P > 0.05). No differences were detected between treatment group means for length of estrus or interval to ovulation (P > 0.05). No differences were detected between treatment group liklihoods for recovery of potential bacterial pathogens, presence of endometritis, or presence of intrauterine fluid at 11 or 16 d post partum (P > 0.05). Pregnancy rate of mares treated with estradiol (5 11 ; 45%) was not different from that of control mares (9 11 ; 82%; P > 0.05). Estradiol treatment did not hasten uterine involution, increase duration of estrus, delay ovulation, or increase fertility in these postpartum mares.

Journal Article↗

Side of gestation in dairy heifers affects subsequent sperm transport and pregnancy rates after deep insemination into one uterine horn.

Effects of side of previous gestation on sperm transport and pregnancy rates after deep cornual insemination were evaluated in 1686 Friesian cows in their first lactational period. Only single ovulating animals were used. At insemination, semen was deposited deep into the uterine horn ipsilateral or contralateral to the preovulatory follicle. A total of 876 cows (52%) ovulated in the ovary ipsilateral to the postgravid horn, and 810 cows ovulated in the contralateral ovary. Semen was deposited into the previously nongravid uterine horn of 832 cows, and into the gravid horn of 854 cows. The pregnancy rate was higher (P < 0.00001) for semen deposition into the previously nongravid horn (46.6%) than for semen deposition into the gravid horn (35.7%). For inseminations ipsilateral to the side of impending ovulation, pregnancy rates were higher (P = 0.0004) when ovulations occurred on the opposite side to the postgravid horn than on the same side. Pregnancy rates were higher (P = 0.002) for contralateral inseminations when ovulations occurred on the same side to the postgravid horn than on the opposite side; they were higher (P = 0.0001) for total ipsilateral than for total contralateral inseminations. There was no difference between ipsilateral and contralateral inseminations (P = 0.64) when ovulation occurred ipsilateral to the postgravid horn, but pregnancy rates were higher (P < 0.00001) when ipsilateral insemination was carried out into the nonpostgravid horn. Results indicate that the side of gestation in dairy heifers affects subsequent pregnancy rates after deep insemination into one uterine horn, possibly by affecting sperm transport.

Journal Article↗

The developmental toxicity of orally administered oxytetracycline in rats and mice.

Timed-pregnant CD rats and CD-1 mice were dosed by gavage with oxytetracycline hydrochloride (OXT) in corn oil on gestational days (gd) 6-15 (0, 1200, 1350, or 1500 mg/kg/day for rats; 0, 1325, 1670, or 2100 mg/kg/day for mice). Deaths among treated females occurred in a dose-related manner in all OXT dose groups (2-7%, mice; 5-24%, rats), but no maternal deaths occurred in the vehicle control groups. Significant dose-related decreases in maternal weight gain during treatment, as well as for corrected gestational weight gain (i.e., maternal gestational weight gain minus gravid uterine weight), were observed at all doses in rats but not in mice. Gravid uterine weight was reduced in a dose-related manner only in mice, with the high-dose group significantly reduced compared to the control group. At termination (gd 20, rats; gd 17, mice), the status of uterine implantation sites was recorded and live fetuses were weighed. Fetuses were examined for external, visceral, and skeletal abnormalities. There were no significant effects of OXT in either species on the incidence of postimplantation loss (resorptions plus dead fetuses) or malformations. In both species, there was a significant trend toward reduced fetal body weight, and each group of rats receiving OXT was significantly reduced compared to the control group. Administration of OXT during organogenesis at doses exceeding the therapeutic range for humans produced maternal and fetal toxicity, but did not produce any treatment-related increase in malformations.

Animals↗

The developmental toxicity of diethylene glycol dimethyl ether in mice.

Diethylene glycol dimethyl ether (diEGdiME) is structurally related to several compounds which produce reproductive and developmental toxicity, including teratogenicity in laboratory animals. In the present study, diEGdiME (0, 62.5, 125, 250, or 500 mg/kg/day) was administered by gavage in distilled water to timed-pregnant CD-1 mice during major organogenesis [gestational days (gd) 6-15]. Clinical status of treated females was monitored daily during treatment and on gd 17. At sacrifice (gd 17), pregnancy was confirmed by uterine examination for 20-24 dams per group; each live fetus was examined for external, visceral, and skeletal malformations. No maternal deaths, morbidity, or treatment-related clinical signs were observed. Reduced maternal weight gain during treatment at greater than or equal to 250 mg/kg/day was primarily attributed to compromised pregnancy status resulting in reduced gravid uterine weight. Maternal weight gain during gestation corrected for gravid uterine weight, and relative liver weight (% body weight) were not affected. Average fetal body weight/litter was significantly reduced at greater than or equal to 125 mg/kg/day. The percentage of postimplantation loss/litter (5, 8, 7, 12, and 50% for control through high dose) and the percentage of malformed live fetuses/litter (0.4, 0, 2, 24, and 96%) were significantly increased at greater than or equal to 250 mg/kg/day. Developmental defects involved primarily the neural tube, limbs and digits, craniofacial structures, abdominal wall, cardiovascular system, urogenital organs, and both the axial and appendicular skeleton. In summary, oral administration of diEGdiME during major organogenesis did not produce any distinctive signs of maternal toxicity, but did produce selective and profound adverse effects upon fetal growth, viability, and morphological development at greater than or equal to 125 mg/kg/day.

Abnormalities, Drug-Induced↗