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961.
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Intrauterine fetal growth restriction (IUGR) is an important pregnancy complication associated with significant adverse clinical outcome, stillbirth, perinatal morbidity and cerebral palsy. To date, no uniformly accepted management protocol of Doppler surveillance that reduces mortality and cognitive morbidity has emerged. Aortic isthmus (AoI) evaluation has been proposed as a potential monitoring tool for IUGR fetuses. In this review, the current knowledge of the relationship between AoI Doppler velocimetry and preterm fetal growth restriction is reviewed. Relevant technical aspects and reproducibility data are reviewed as we discuss AoI Doppler and its place within the existing repertoire of Doppler assessments in placental insufficiency. The AoI is a link between the right and left ventricles which perfuse the lower and upper body, respectively. The clinical use of AoI waveforms for monitoring fetal deterioration in IUGR has been limited, but preliminary work suggests that abnormal AoI impedance indices are an intermediate step between placental insufficiency-hypoxemia and cardiac decompensation. Further prospective studies correlating AoI indices with arterial and venous Doppler indices and perinatal outcome are required before encorporating this index into clinical practice. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
966.
We examined the temporal variation of lysosomal enzyme activities and lysosomal membrane stability in two stocks of blue
mussels (Mytilus edulis L., 1758) from the Magdalen Islands which differ in their susceptibility to summer mass-mortality. The activity of lysosomal
enzymes reflects the autolytic capacity which could be used during the transfer of reserves between storage and reproductive
tissues or for mobilisation of reserves for energy requirements. The peak of lysosomal enzyme activities in mantle tissue
in June 1992 probably was related with autolysis of storage cells to support maturation of the developing gametes. A second
peak of lysosomal enzyme activity which occurred in mid- August of 1992 and 1993 may help to cover energetic requirements
of maintenance metabolism during this period of high temperatures and reduced food quality. Measures of the destabilization
of lysosomal membranes in the digestive gland confirmed that mussels showed a significant stress response in mid-August. Mussels
from the stock with a higher susceptibility to summer mortality underwent a longer period of stress and accumulated less glycogen
between spawning and the stressful period in mid-August than mussels from the more resistant stock. In conclusion, our field
observations demonstrate high activities of lysosomes not only in spawning periods but also during stressful periods of high
temperatures and reduced food quality.
Received: 23 September 1997 / Accepted: 11 June 1998 相似文献
967.
968.
Seasonal variations of heavy metal contamination in river Gomti of Lucknow city region 总被引:2,自引:0,他引:2
Lohani MB Singh A Rupainwar DC Dhar DN 《Environmental monitoring and assessment》2008,147(1-3):253-263
The present study deals with the seasonal variations in the concentrations of heavy metals namely chromium, lead and mercury by using spectrophotometric methods. The water samples were collected at regular intervals from five selected sites of river Gomti in the pre-monsoon period (months of February-May) and the post monsoon period (months of October-January). The concentrations of chromium (VI) and mercury (II) were determined by using Genesys-10 UV-VIS Spectrophotometer while lead (II) concentrations were determined using Atomic Absorption Spectrophotometer, Perkin-Elmer 5000 model. The concentrations of all the three metals were found to be higher in the pre-monsoon period than in the post-monsoon period. The statistical analysis of the data was discussed in both the seasons in terms of mean, standard deviation and coefficient of variation. 相似文献
969.
970.
J. B. Lewis 《Marine Biology》1998,130(4):651-662
Dipolydora armata (Langerhans, 1880) is a small (4 to 5 mm) spionid polychaete found burrowing in the calcareous hydrozoan Millepora complanata Lamarck, 1816, on coral reefs at Barbados, West Indies. It excavates complex networks of interconnecting burrows and forms
aggregations of worms in cavities within branches of the coral. Adult worms have a mixed feeding mode (suspension feeding
and deposit feeding). Size–frequency distributions of worms in branch samples suggest that they mature in a single year and
that reproduction occurs throughout the year. Burrow openings on the surface of the coral develop distinctive, erect spines
caused by combined growth of worm tubes and host tissue. Millepore zooids were absent in the vicinity of tube openings and
on spines, and thus the potential feeding surface of the coral will be reduced in heavily colonized branches. Burrows and
openings were densest at the bases of millepore branches where weakening of the skeleton would be expected to occur. The absence
of openings near the branch tips suggests difficulty in larval settlement there, amongst stinging zooids. Reproduction␣and
larval development of the worms were examined, and a sequence of larval stages from one to 20 segments and a juvenile stage
of 22 segments are described. Eggs are deposited in brood sacs attached to the burrow wall, and the larvae feed upon nurse
eggs (adelphophagy). The presence of larvae and juveniles occurring free in the burrows suggests that larval development may
be completed within the host coral as an alternative or in addition to a planktonic larval phase. Lack of provisional larval
setae, early development of adult capillary setae, production of special spermatophores and a protracted breeding cycle in
D. armata are all traits which would favour complete development within the host skeleton.
Received: 6 March 1997 / Accepted: 25 October 1997 相似文献