"Rates" of birth defects

The proportion of children born with a particular defect is not a "birth defect rate" but, rather, a prevalence proportion. The implications of confusing a rate and a proportion are discussed in terms of the interpretation of birth defect data. It is recommended that "prevalence proportion" or "prevalence" be used to report the frequency of various defects rather than the often-used "prevalence rate."     

A distributed knowledge-based approach to flexible automation: The contract net framework

This article applied distributed artificial intelligence to the real-time planning and control of flexible manufacturing systems (FMS) consisting of asynchronous manufacturing cells. A knowledge-based approach is used to determine the course of action, resource sharing, and processor assignments. Within each cell there is an embedded automatic planning system that executes dynamic scheduling and supervises manufacturing operations. Because of the decentralized control, real-time task assignments are carried out by a negotiation process among cell hosts. The negotiation process is modeled by augmented Petri nets —the combination of production rules and Petri nets—and is excuted by a distributed, rule-based algorithm.     

Artificial incubation of California condor Gymnogyps californianus eggs removed from the wild

The currrent California condor (Gymnogyps californianus) recovery plan entails increasing the reproductive rate via replacement-clutch manipulation of eggs. During the period from 1983 to 1985, 15 eggs were removed from wild nesting pairs for artificial incubation. The eggs were incubated at a dry bulb temperature of 36.4°C in modified forced-air Lyon Electric incubators. The incubation humidity was adjusted for individual eggs based on weight loss data (water = weight), 25.6–30.0°C wet bulb (41.0–63.0% Relative Humidity (RH)). The chicks were hatched initially under forced-air conditions of 36.1°C dry bulb, 31.1–01.7°C wet bulb (70.0–73.0% RH). In 1984, hatching parameters were changed to still-air conditions, 36.1°C dry bulb (top of the egg), 35.0°C dry bulb (bottom of the egg), 31.1–31.7°C wet bulb (70.0-73.0% RH). Tactile and auditory stimulation was utilized during the pip-to-hatch interval. From among 15 eggs collected, 13 hatched, and 12 condor chicks were raised successfully (hatchability: 86.7%; survivability: 92.3%).     

3-Mercaptopropionic acid administration increases the affinity of [H]Quinuclidinyl benzilate binding to membranes of the striatum and cerebellum

It is known that quinuclidinyl benzilate (QNB) binds specifically and with high affinity to the cholinergic muscarinic receptor and that behaves as a potent antagonist of this receptor.

We have analysed -[³H]QNB binding to rat CNS membranes after the administration of the convulsant 3-mercaptopropionic acid (MP) (150 mg·kg⁻¹, i.p.). The studies were done in rats killed at two stages: during and after seizures. No changes in [³H]QNB binding to hippocampus and cerebral cortex membranes were found. [³H]QNB binding increased about 40 and 80% in striatum and cerebellum membranes, respectively. The changes were observed both in seizure and postseizures states. The study was extended to the assay of [³H]QNB binding kinetic constants in the anatomical areas modified by the convulsant. The analysis of the saturation curves indicated an increase in the binding affinity but no change in the number of binding sites. Hill number values were near the unit suggesting a non-cooperative interaction between the ligand and the receptor, and the labelling of a homogeneous population of receptor sites.

The results suggest the participation of some cholinergic pathways in the development and maintenance of MP-induced seizures.     

Rainbow trout (Oncorhynchus mykiss) neuropeptide Y.

Neuropeptide Y (NPY) has been isolated from brain extracts of the rainbow trout (Oncorhynchus mykiss) and subjected to structural analyses. Plasma desorption mass spectroscopy estimated the molecular mass of the purified peptide as 4303.9 Da. Automated Edman degradation unequivocally established the sequence of a 36 amino acid residue peptide as: Tyr-Pro-Pro-Lys-Pro-Glu-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Pro-Glu-Glu-Leu-Ala-Lys-Tyr-Tyr-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr. The molecular mass calculated from this sequence (4304 Da) is consistent with that obtained by mass spectroscopy. The presence of a C-terminal amide was established by radioimmunoassay. Rainbow trout NPY is identical in primary structure to coho salmon (Oncorhynchus kisutch) pancreatic polypeptide (PP). These data may indicate that, in this group of salmonid fishes, a single member of the NPY/PP peptide family is expressed in both neurons and peripheral endocrine cells.     

Influenza virus hemagglutinin with multibasic cleavage site is activated by furin, a subtilisin-like endoprotease.

Many viruses have membrane glycoproteins that are activated at cleavage sites containing multiple arginine and lysine residues by cellular proteases so far not identified. The proteases responsible for cleavage of the hemagglutinin of fowl plague virus, a prototype of these glycoproteins, has now been isolated from Madin-Darby bovine kidney cells. The enzyme has a mol. wt of 85,000, a pH optimum ranging from 6.5 to 7.5, is calcium dependent and recognizes the consensus sequence R-X-K/R-R at the cleavage site of the hemagglutinin. Using a specific antiserum it has been identified as furin, a subtilisin-like eukaryotic protease. The fowl plague virus hemagglutinin was also cleaved after coexpression with human furin from cDNA by vaccinia virus vectors. Peptidyl chloroalkylketones containing the R-X-K/R-R motif specifically bind to the catalytic site of furin and are therefore potent inhibitors of hemagglutinin cleavage and fusion activity.     

The principal islet of the coho salmon (Oncorhyncus kisutch) contains the BB isoenzyme of creatine kinase

The importance of creatine kinase (E.C. 2.7.3.2) in endocrine tissues has been generally overlooked. Using a specific radiometric assay, we have demonstrated the existence of CK in the Brockmann body (principal islet) of the Coho salmon. We have purified this protein from insular tissue and concurrently purified CK from brain and muscle of the salmon. Purification characteristics, immunological cross-reactivity, and N-terminal sequence analysis have demonstrated that the predominant cytosolic CK from the Brockmann body is indistinguishable from the BB (brain) isoenzyme. Immunocytochemical studies indicated that the enzyme resides in the endocrine parenchyma. Phosphocreatine may serve as a reservoir of energy in the islet and augment its capacity to secrete hormones. The induction of CK-BB in the islet by other hormones could influence the secretion of insular hormones. Interorgan flux of the substrate creatine may be an undescribed mechanism of physiological regulation.     

Immature maize spikelets develop and produce pollen in culture

Immature maize spikelets have been successfully grown in vitro. Culture conditions were refined to maximize development of normal pollen grains. Kinetin was not required for normal development, in contrast to the absolute requirement for this plant growth regulator for in vitro tassel development. Development occured in all stages sampled, from premeiosis to postvacuolation, and there was no lag in progression through the various stages of development as compared to greenhouse-grown material. Cultured spikelets produced pollen that appeared morphologically normal, accumulated starch and had the normal two sperm nuclei and single vegetative nucleus.     

PHYLOGENY OF THE SUBFAMILIES OF THE FAMILY BRACONIDAE (HYMENOPTERA: ICHNEUMONOIDEA): A REASSESSMENT

Abstract— The recently published phylogeny of Braconidae by Quicke and van Achterberg is reassessed. Character-state definitions and character polarities are evaluated, and more rigorous methods are suggested. Our results indicate that there are many more parsimonious solutions to their data set, the consensus of which differs substantially from their results. Based on our reassessment, little can be said about the relationships among braconid subfamilies. Consensus trees show the cyclostomes as a largely unresolved basal grade. The two other major lineages which have been proposed, the helconoids and microgastroids, are somewhat better resolved, but not consistently so. Relationships among the helconoids vary considerably depending on the parameters used for parsimony analysis.     

The fate of female donor blastodermal cells in male chimeric chickens.

In previous experiments in our laboratories, chickens that are chimeric in their gamete, melanocyte, and blood cell populations have been produced by injection of dispersed stage X blastodermal donor cells into the subgerminal cavity of stage X recipient embryos. In some experiments, donor cells were transfected with reporter gene constructs prior to injection as a preliminary step in the production of transgenic birds. Chimerism was assessed by test mating, observation of plumage, and DNA fingerprinting. Methods were sought that would provide a relatively rapid analysis of the spatial distribution of descendants of donor cells in chimeras to assess the efficacy of various methods of chimera construction. To date, the sex of donor and recipient embryos was not known and, therefore, numerous mixed sex chimeras must have been constructed by chance, since donor cells were usually collected from several embryos rather than from individual embryos. The presence of female-derived cells was determined by in situ hybridization using a W-chromosome-specific DNA probe, using smears of washed erythrocytes from 16 phenotypically male chimeric chickens ranging in age from 4 days to 42 months posthatching. The proportion of female cells detected in the erythrocyte samples was zero (eight samples) or very low (0.020-0.083%), although 1% of the erythrocytes from a phenotypically male chick that was killed 4 days after hatch were female-derived. The low proportions of female-derived cells were surprising, considering that most of these chimeras had been produced by the injection of cells pooled from several donor embryos and most recipients had been exposed to gamma irradiation prior to injection, thus dramatically enhancing the level of incorporation of donor cells into the resulting chimeras. By contrast, 0-100% of the erythrocytes were female-derived in blood samples taken at 10 days of incubation from the chorioallantois of seven phenotypically normal male embryos that resulted from the injection of blastodermal cells pooled from five embryos into irradiated recipient embryos. Approximately 70% of the erythrocytes in a blood sample from a phenotypically normal female chimeric embryo were female-derived, and 100% of the erythrocytes examined from an intersex embryo bearing a right testis and a left ovary were female-derived. These results indicate that female-derived cells can contribute to the formation of erythropoietic tissue during the early development of what will become a phenotypically male chimeric embryo. It would appear, therefore, that female-derived cells are blocked in development or destroyed, or certain male-female combinations of cells may be lethal prior to hatching.(ABSTRACT TRUNCATED AT 400 WORDS)