Activation of a heterologously expressed octopamine receptor coupled only to adenylyl cyclase produces all the features of presynaptic facilitation in aplysia sensory neurons.

Short-term behavioral sensitization of the gill-withdrawal reflex after tail stimuli in Aplysia leads to an enhancement of the connections between sensory and motor neurons of this reflex. Both behavioral sensitization and enhancement of the connection between sensory and motor neurons are importantly mediated by serotonin. Serotonin activates two types of receptors in the sensory neurons, one of which is coupled to the cAMP/protein kinase A (PKA) pathway and the other to the inositol triphosphate/protein kinase C (PKC) pathway. Here we describe a genetic approach to assessing the isolated contribution of the PKA pathway to short-term facilitation. We have cloned from Aplysia an octopamine receptor gene, Ap oa(1), that couples selectively to the cAMP/PKA pathway. We have ectopically expressed this receptor in Aplysia sensory neurons of the pleural ganglia, where it is not normally expressed. Activation of this receptor by octopamine stimulates all four presynaptic events involved in short-term synaptic facilitation that are normally produced by serotonin: (i) membrane depolarization; (ii) increased membrane excitability; (iii) increased spike duration; and (iv) presynaptic facilitation. These results indicate that the cAMP/PKA pathway alone is sufficient to produce all the features of presynaptic facilitation.

Synthetic mutants of Clostridium pasteurianum ferredoxin: open iron sites and testing carboxylate coordination.

The entire polypeptide chains for two new Clostridium pasteurianum ferredoxin (Fd) mutants were prepared with the following site-specific substitutions: Cys11Asp and Cys11 alpha-aminobutyric acid (Cys11 alpha-Aba), the latter being a non-naturally occurring amino acid. Standard t-Boc procedures were used for the synthesis and the peptides. The two apoproteins were reconstituted to the 2[4Fe-4S] holoprotein and their spectroscopic, redox and thermal properties were compared with those of native C.pasteurianum Fds. The fully reconstituted Cys11Asp and Cys11 alpha-Aba mutants were initially found to have both clusters intact, i.e. they were 2[4Fe-4S] ferredoxins. The unconventional ligands of Asp and alpha-Aba led to holo-Fds that were not very stable and easily released an iron to form the [3Fe-4S] cluster, presumably through oxidation. The Cys11 alpha-Aba mutant was somewhat more thermally stable than Cys11Asp. In contrast, while both mutants were less stable than the native protein upon exposure to oxygen, the Cys11 alpha-Aba mutant was less stable than Cys11Asp. The Cys11Gly mutant was also prepared, but all attempts, despite repeated and varied experimental conditions, at reconstitution to the Cys11Gly holo 2[4Fe-4S] Fd were unsuccessful, probably because a Gly-Gly sequence is known to break structure. This work, when compared with molecular biological site-specific mutagenesis, shows some of the advantages of chemical/in vitro reconstitution: certain mutants which cannot be detected as holoproteins by site-specific mutagenesis can be formed after all in vitro. Nonetheless, it seems apparent that altering any of the Cys coordination sites of the Fd clusters results in fundamentally more unstable ferredoxins.

Adherence patterns and DNA probe types of Escherichia coli isolated from diarrheal patients in China.

One hundred and seventy-two strains of Escherichia coli isolated from diarrheal patients in Beijing, P.R. China, were analyzed for plasmid DNA profile, HEp-2 cell adherence ability and reactivity to 10 previously described DNA probes. They had not been recognized as pathogenic E. coli in China. Of the 110 strains tested, 76 (69%) contained one or multiple large plasmids. Of the 71 strains with the large plasmids 64 could adhere to HEp-2 cells. Of the 172 strains, 102 (59.3%) were hybridized with at least one of the 10 probes. Of those, seven strains hybridized with enteroaggregative E. coli (EAggEC) probe. Their serotypes were O128 (two strains), O6 (one strain), and O111 (one strain). Three strains were untypable. Six and three strains were hybridized with enteropathogenic E. coli (EPEC) attaching and effacing genes (eae) or EPEC adherence factor (EAF) probe, respectively. Two non-O157: H7 strains hybridized with enterohemorrhagic E. coli (EHEC) probe. Seventy-two strains (41.9%) hybridized with shiga-like toxin 2 or 1 (SLT2 or SLT1) probes. Among the SLT1 or SLT2 probe-positive strains, 54 hybridized with invasive (INV) plasmid probe developed for identification of enteroinvasive E. coli (EIEC) and Shigella species. The INV and SLT probe-positive strains might represent a new variety of verotoxin-producing E. coli (VTEC).

[Brain damage in asphyxiated newborn infants: early diagnosis. A follow-up study].

Cranial computerized tomographic (CT) scan and serum creatine phosphokinase-BB(CPK-BB) determination were done in 85 asphyxiated newborn infants, in some of them, long-term follow-up study including neurodevelopmental assessment and CT scan were also carried out. The types of early brain damage after perinatal asphyxia included intraparenchymal hemorrhage (IPH), periventricular-intraventricular hemorrhage (PV-IVH), subarachnoid hemorrhage (SAH) and brain edema (BE). Serum CPK-BB levels were elevated within 24 hours after the events of asphyxia, and correlated to the severity of brain damage. These findings were helpful in the early diagnosis of brain damage and estimating its severity and prognosis. The types and severity of brain damage were obviously related to prognosis. The prognosis of infants after SAH and BE were better than those of infants with PV-IVH, and infants with IPH showed the poor results. Follow-up CT scans were performed in 30 infants with brain damage. Abnormal changes included ventricular sulcus dilation, leukomalacia, cyst formation (pseudocyst) and porencephalic cavitation (porencephaly).

[Attempt to evaluate a contraceptive method using fuzzy mathematics: a study on the acceptability of Norplant].

PIP: Life table analysis has been a good method for evaluating the effectiveness of contraceptive methods. However, it does not take into account factors such as safety, reversibility, side effects, acceptability, and costs, which are important aspects of a contraceptive methods. Fuzzy mathematics is an evaluation system that includes those elements. The data of a 1 year follow-up study on 1000 Norplant users were used in the analysis. Included in the fussy sets were a matrix which combined the contraceptive method continuation rate, occurrence of side effects, reversibility, rating of method from a opinion poll, and financial costs with an assigned ranking of acceptability of the method. Weights were assigned to the fuzzy sets, and, after the data manipulation, a value was obtained for a particular method. Results showed that Norplant is in the "easily acceptable" category, the best of 4 categories. As the safety indicator was lacking, it was not included in the analysis. Due to the fact that the indicators to be included in the fuzzy set and the weights given to the indicators are subjective, different variables or weights may produce very different results. Therefore, this contraceptive evaluation method should be used by experienced professionals. The proposed method could also be used to compare different contraceptive methods or the same contraceptive method at different stages and in different geographic areas in terms of effectiveness and acceptability.^ieng

Chitin synthetase from yeast-type cells ofMucor rouxii induced by malonic acid: a screen for antifungal agents and isolation of an active metabolite from an actinomycetes.

In an aerobic medium malonic acid inducedMucor rouxii to produce yeast-type cells exclusively. Chitin synthetase in a cell-free extract from these yeast cells increased its activity upon standing at 28°C or when activated by trypsin. It was similar in stability to that from the yeast cells formed under an atmosphere of N2/CO2 (7∶3 v/v). By using the enzyme activity as a model screen, a competitive inhibitor of chitin synthetase has been isolated from the fermentation broth of an actinomycete isolate.

[Calculation of individual expulsion probability of IUD and its clinical application].

PIP: A study of the probability of individual expulsion of an IUD in the 1st year of use and its clinical application was conducted through multifactor analysis of 1965 IUD users. The product of the study was 2 disk-shaped tables, which a woman uses together to calculate the probability that she might inadvertently expel her IUD. This system takes into account the commonly acknowledged causes for IUD expulsion and accidental pregnancy, such as age, intensity of work, frequency of births and timing of insertion of the IUD in order to calculate the probability. On a 180-degree arc of each table, there are verbal descriptions of these factors, which are diametrically opposite a set of numerical codes. With the smaller table superimposed on the larger, 72 combinations of factors can be achieved by turning the tables and lining up the factors printed on both. Any woman can align the factors that apply to her and then read the codes opposite her particular combination. A separate table gives the probabilities associated with each numerical code. For instance, a 32 year old woman having a medium work load, 3 children, who receive an IUD after having had an abortion, would read her composite code number 3133 from the disks. On the other table, she would see that this number corresponds to a probability of .04. If a woman with a metal ring IUD finds she has a high probability of expulsion, she is counselled to find a more secure method of contraception, given her particular circumstances, or take compensatory measures.^ieng

Amino acid sequence of the variable region of an unusual lambda-type human Bence Jones protein (Lee).

The variable portion of a human lambda-type Bence Jones protein (Lee) has been prepared by limited tryptic digestion. Its amino acid sequence is determined from analysis of tryptic peptides, CNBr cleavage fragments prepared from the reduced-aminoethylated protein. Peptides are aligned by homology to other lambda-type proteins. The Lee L-chain has an unusual extension of two amino acid residues (Val-Thr) at the N-terminus. An idiotypic antibody of Lee can react with two other lambda-type Bence Jones proteins, Meg (V lambda IV) and Cap (V lambda III). Application of the principle of Chou and Fasman to the sequence data indicates that two portions on the surface of the V-region have identical secondary structures similar to the portions of the Meg and Cap lambda-chains. This appears to relate to the idiotypic similarities of the three proteins.