instruction:
Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
question:
Abstract: Daylength (photoperiod) influences the rate of reproductive development in the juveniles of some photoperiodic species. Recent studies show that daylength during the prenatal period is perceived by the fetus and that this perception can profoundly influence postnatal reproductive and somatic development. Using the photoperiodic Djungarian hamster, we assessed the role of the maternal pineal gland and its hormone, melatonin, in this prenatal perception of daylength. Maternal pinealectomy eliminated the influence of prenatal photoperiod on testicular and body weights of male pups, suggesting that a product from the maternal pineal gland communicates daylength to the fetus. Infusion of the pineal hormone melatonin into pinealectomized dams for various durations during gestation mimicked the effect of varying the prenatal photoperiod on both testicular and body weights. These results indicate that pineal melatonin is involved in this novel form of communication from mother to fetus.
answer:
Animal


question:
Abstract: We examined the effects of leukotrienes C4 (LTC4) and D4 (LTD4) (1 microgram) on the pulmonary vascular filtration coefficient, a measure of vessel wall conductivity to water, and the alterations in pulmonary vascular resistance (PVR) in isolated-perfused guinea pig lungs. We also assessed whether LTC4 and LTD4 increased the permeability to albumin in cultured monolayers of pulmonary artery endothelial cells. In Ringer-perfused and blood-perfused lungs, LTC4 resulted in increases in pulmonary arterial pressure (Ppa) and the pulmonary capillary pressure (Pcap) measured as the equilibration pressure after simultaneous pulmonary arterial and venous occlusions. Pulmonary venous resistance (Rv) increased to a greater extent than arterial resistance (Ra) in both Ringer-perfused and blood-perused lungs challenged with LTC4. The greater increase in PVR in blood-perfused lungs corresponded with a greater elevation of lung effluent thromboxane B2 (TxB2) concentration. The LTC4-stimulated increase in PVR was prevented by pretreatment with meclofenamate (10(-4) M). LTD4 also induced rapid increases in Ppa and Pcap in both Ringer-perfused and blood-perfused lungs; however, Ppa decreased before stabilizing at a pressure higher than base line. The increases in Rv with LTD4 were greater than Ra. The LTD4-stimulated increases in Ra and Rv also paralleled the elevation in TxB2 concentration. As with LTC4, the increases in Ppa, Pcap, PVR, and TxB2 concentration were greater in blood-perfused than in Ringer-perfused lungs. Pretreatment with meclofenamate reduced the magnitude of the initial increase in Ppa, but did not prevent the response.(ABSTRACT TRUNCATED AT 250 WORDS)
answer:
Albumins


question:
Abstract: In the course of characterizing monoclonal antibodies (MAbs) recognizing cell surface antigens on dispersed human parathyroid cells (dPTCs), we identified one MAb (4F2) that bound avidly to parathyroid cells and had marked effects on parathyroid function. The binding of MAb 4F2 to human adenomatous dPTCs resulted in a marked [53.8 +/- 7.9% (+/- SEM)] reduction in low calcium (Ca)-stimulated PTH secretion to levels equivalent to those in cell suppressed by high extracellular Ca (1.5 mM). Typically, these functional effects were optimal at antibody dilutions of 1:10(4) to 1:10(5). Cell viability was confirmed at the conclusion of each experiment by trypan blue exclusion (greater than 90-95%) and cell surface immunofluorescence. Parallel studies using the Ca-sensitive dye Quin-2 showed that inhibition of PTH secretion in 4F2-treated cells was associated with a concomitant increase in cytosolic Ca (Cai) of 188% in 0.5 mM Ca; these values also approached Cai levels in control cells incubated in high Ca. Mab controls, P3 X 63, which do not bind to dPTCs, and Mab LC7-2, which recognizes a different epitope of the same antigen as 4F2 on dPTCs, did not alter PTH secretion or Cai. Immunoprecipitation of 125I-labeled parathyroid cell extracts with MAb 4F2 demonstrated proteins with mol wt of approximately 145, 85, and 45 under nonreducing conditions and 85 and 45 kilodaltons after reduction with 5% mercaptoethanol. These studies suggest that 1) Mab-4F2 binding to its cell surface antigen inhibits PTH secretion by human adenomatous parathyroid cells in vitro; 2) the alterations in secretory function could be related to by an attendant increase in Cai; 3) the 4F2 antigen on dPTCs is a heterodimeric protein of (approximately) 85K and 45K; and 4) the 4F2 antigen may be an important component of the Ca-sensing and/or signal-transducing mechanism in this cell.
answer:

Adenoma


