华蟾蜍毒素对离体豚鼠输精管的作用

华蟾蜍毒素(华蟾素)使离体豚鼠输精管产生剂量依赖性收缩反应,利血平化豚鼠输精管及冷藏输精管对华蟾素反应减弱。给酚妥拉明、维拉帕米后,输精管对华蟾素反应均受抑制,溴苄胺可使反应潜伏期缩短。结果提示华蟾素收缩输精管反应可能与其促进肾上腺素能神经末稍NA释放有关。     

Frozen algae as food for Daphnia magna Straus in toxicity testing.

As EC validity criteria for the production of Daphnia magna neonates in standard toxicity tests set fecundity minima which must be attained, it is important that culture conditions provide an adequate ration of high quality food. Maintaining a steady supply of fresh algae can be problematical so the possibility of using frozen food was investigated. The performance of three generations of D. magna fed on diets of fresh or frozen Chlorella was compared. There were no significant effects on fecundity due to food type or generation. Cumulative fecundity (over 21 days) on fresh or frozen food exceeded 120 neonates per female and satisfied that EC validity criterion (60 neonates per female). In addition criteria relating to survival and variability were met. We conclude that frozen Chlorella are an acceptable substitute for fresh algae.     

Cerebrovascular accidents complicating pregnancy and the puerperium

The decreasing incidence of direct causes of maternal death over the past half century has led to a heightened awareness of nonobstetric factors responsible for maternal mortality. For example, cerebrovascular accidents are an important nonobstetric cause of maternal morbidity and mortality. During the 6.5-year period from 1984 to mid-1990, we encountered 15 women in whom pregnancy or the puerperium was complicated by an acute cerebrovascular accident. Six of these women had hemorrhagic strokes and nine had ischemic strokes. During this same time, approximately 90,000 women were delivered at Parkland Memorial Hospital, and thus the incidence of stroke was about one in 6000 pregnancies. Chronic hypertension or preeclampsia was causative in three cases of hemorrhagic stroke. It is important that 20% of the women died as a result of stroke, and of the 12 survivors, 40% have residual neurologic deficits. An aggressive work-up to define the etiology of stroke is necessary in order to implement cause-specific management, with subsequent reduction in morbidity and mortality.     

Parasellar syndrome caused by plasma cell leukemia

A 71-year-old man had incomplete third cranial nerve palsy caused by plasma cell leukemia and a parasellar plasmacytoma. This is the first reported case of plasma cell leukemia in which a central nervous system sign was the initial manifestation. Only one previous case of intracranial plasmacytoma associated with plasma cell leukemia has been reported. The characteristics of intracranial plasmacytomas and of plasma cell leukemia are discussed.     

1-Methylnicotinamide stimulates cell growth and inhibits hemoglobin synthesis in differentiating murine erythroleukemia cells

Exposure of murine erythroleukemia cells (MELCs) to nicotinamide (NA) or its synthetic analog N′-methylnicotinamide (N′-MN) reduces cell growth and induces terminal differentiation, marked by increased heme and globin accumulation. On the contrary, 1-methylnicotinamide (1-MN), the primary metabolite of excess NA, was found to stimulate cell growth and reduce spontaneous differentiation of cultured MELCs. Log phase MELCs exhibited up to 50% higher cell density above untreated cells when cultured for up to 96 h with 2.5 mM 1-MN. When combined with NA or several chemically-unrelated inducers of hemoglobin synthesis in cultured MELCs, 1-MN reduced the globin mRNA levels and heme accumulation by 40–80%. 1-MN was able to inhibit heme production if present during only the first 24–48 h after NA exposure. Pre-treatment with 1-MN could not confer resistance of cells to effects of NA, suggesting the inhibition is reversible. Commitment to differentiate in semisolid medium by the most potent inducer, 5 mM N′-MN, was inhibited up to 95% by 2.5 mM concentrations of 1-MN. It appears that 1-MN has opposing effects on growth and induction of differentiation than those seen in MELC cultures exposed to NA or N′-MN.