Umbilical cord haematoma as a complication of intrauterine intravascular blood transfusion

Between October 1985 and February 1989, 49 ultrasound-guided intravascular fetal blood transfusions were performed in 16 patients (14 with rhesus (Rh) isoimmunization, 2 with non-immunologic hydrops fetalis (NIHF)). As an intra-operative complication, perivascular haematoma of the cord occurred in three patients (7 per cent). In two cases, fetal bradycardia necessitated delivery by Caesarean section at 30 and 32 weeks' gestation, respectively. In the third case, fetal bradycardia developed during transfusion, at 31 weeks' gestation, but normalized within 3 min. The baby was delivered as planned at 36 weeks of gestation, after another transfusion at 34 weeks. Dislodgement of the needle tip into perivascular tissue, caused by sudden fetal or maternal movements, is the reason for this complication. The haematoma develops as a result of delayed recognition and continuous transfusion into Wharton' s jelly. Cord haematoma may be diagnosed in time by continuous ultrasound imaging, as illustrated in case 3. To minimize the risk of needle dislodgement during transfusion, sedation of the mother and complete immobilization of the fetus by injecting a short-acting muscle relaxant into the umbilical vessel are recommended.     

Prenatal diagnosis and perinatal management of a fetal ovarian cyst

A case of a prenatally diagnosed fetal ovarian cyst is presented. The pregnancy was complicated only by polyhydramnios, and some degree of fetal bowel obstruction could be recognized on sonogram. The newborn was delivered vaginally in the 39th week of pregnancy, and the cyst was removed by laparotomy on the day of the delivery. The etiology of this rare fetal condition is unknown.     

An assessment of lead absorption from soil affected by smelter emissions

The purpose of this study was to assess the oral bioavailability of lead in soil collected from a former smelter site in Sandy, Utah, USA. Sprague-Dawley rats (approximately 4 weeks of age, 5 of each sex in group) were given either soil lead or lead acetate mixed in a purified diet (AIN-93G ) at four different concentrations for 31 consecutive days. Food consumption measurements were used to compute mean daily lead exposures for the soil lead and lead acetate groups. The lead acetate treatment yielded higher concentrations of lead in the blood and bone than the soil lead treatment. Mean blood lead values ranged from below the detection limit (3 g dL^–1) to 27.25 g lead dL^–1 for the lead acetate groups at dose levels of 0.10–2.91 mg lead kg body weight^–1 and from below the detection limit to 8.8 g lead dL^–1 for the soil lead groups at doses of 0.11–3.43 mg lead kg body weight^–1. At these same doses, mean bone values ranged from 0.52 to 26.92 g lead g^–1 for the lead acetate groups and from 0.64 to 13.1 g lead g^–1 for the soil lead groups. Relative per cent bioavailability was estimated by modelling the dose-blood concentration curves for the lead acetate treatment and the dosed soil lead treatment, and then comparing doses that produce an equivalent blood lead concentration. The ratio of the doses of lead acetate and soil lead that produced the same tissue response (i.e., concentration) provided an index of relative bioavailability. For lead, the bioavailability of soil lead relative to lead acetate was 41% at a blood concentration of 6 g lead dL^–1.     

Tidal-linked behaviour of the shrimp Ligur uvea in a land-enclosed marine pool

At Aldabra Atoll, the shrimp Ligur uvea inhabits a land-locked marine pool which is connected to the sea by a subterranean fissure. The shrimps migrate daily with the tide from a hole in the subterranean labyrinth to a feeding area at the bottom of the pool. The timing of the migration is tidal-linked and independent of light and temperature. With each incoming tide, tagged individuals return to a definite feeding ground. Such homing has not been reported from other L. uvea pools. Feeding activity was quantitatively measured, differences between day and night activity are interpreted as adaptations against predators (terrestrial wading birds). Compared to other L. uvea pools, the shrimps at Aldabra Atoll are exposed to a more rigorous environmental situation, which probably influences the tidal-linked behaviour of the local shrimp population.     

生态旅游的开发合作

定义 围绕这个主题 , 虽然有很多不同的看法 , 笔者却认为 , 由于具有一整套明确目标 , " 生态旅 游 " 应该被认作是一个可以发展的概念 , 没必要把它当作一个市场 ( 市场指得是 " 大自然旅 游 " ) . 因此 , 生态旅游被认定为大自然旅游的一种具有可持续能力的形式 , 力争得到环境 、社会和文化的和谐共处 , 以及创造经济和其他的效益 , 特别是在为当地农村居民造福和自 然保护方面 .     

The causes of the tremble dance of the honeybee,Apis mellifera

Tremble dances are sometimes performed by returning forager bees instead of waggle dances. Recent studies by Seeley (1992) and Kirchner (1993) have revealed that this behaviour is part of the recruitment communication system of bees. The ultimate cause of tremble dances is, according to Seeley (1992), an imbalance between the nectar intake rate and the nectar processing capacity of the colony. This imbalance is correlated with a long initial search time of returning foragers to find bees to unload them. However, it remained unclear whether a long search time is the direct proximate cause of tremble dancing. Here we report that a variety of experimental conditions can elicit tremble dances. All of them have in common that the total search time that foragers spend searching for unloaders, until they are fully unloaded, is prolonged. This finding supports and extends the hypothesis that a long search time is the proximate cause of tremble dancing. The results also confirm the previous reports of Lindauer (1948) and others about factors eliciting tremble dancing.