The amount of damage resulting from pulmonary aspiration of gastric contents is determined primarily by the acidity of the aspirate. Thus, it has been recommended that the pH of stomach contents of ...pregnant women be increased by the oral administration of antacids prior to anesthesia for delivery. This study was done to investigate the effects of antacid aspiration in dogs and compare these effects with those obtained by trials of aspiration of acid, saline solution, and alkaline saline solution. Mean PaO2 of the saline-treated group had decreased from 81 to 60 torr at 10 min, while that of the alkaline saline-treated group had decreased from 83 to 58 torr. Fractional intrapulmonary physiologic shunt (Qs/Qt) increased in these two groups, from 15 to 34 and from 16 to 42 per cent, respectively. The Qs/Qt had returned to control values in both groups by four hours, and the PaO2 had returned to control values by 24 hours. By contrast, the acid- and antacid-treated groups had decreases in PaO2 values from 77 to 34 torr and from 84 to 46 torr, respectively. Neither group had a return of PaO2 to pre-aspiration level by 24 hours. Likewise, the Qs/Qt increased significantly more in these two groups: 14 to 66 per cent in the acid-treated group and 13 to 47 per cent in the antacid-treated group. These changes persisted throughout four hours. The saline and alkaline saline aspirates produced little histologic damage. The acid aspirate produced hemorrhage, exudates, and edema. However, these changes were no longer present a month later. The antacid aspirate produced a marked bronchopneumonia that was still present as a chronic inflammatory reaction after a month. These findings indicate that antacids can cause pulmonary damage when aspirated.
The variant surface glycoprotein (VSG) gene expression site in Trypanosoma brucei variant 117a has been mapped to a point about 40 kb upstream from the VSG gene. Sequences upstream from the ...previously identified Cully, D.F. et al. (1985) Cell 42, 173-182 expression site associated gene (ESAG-I) have been cloned and a stable 1.3 kb transcript has been localized immediately 5' to ESAG-I. This transcript is in the same orientation and approximately as abundant as the ESAG-I message. A highly conserved region, of which at least 15 copies are present in the genome, has been identified further upstream. A stable transcript corresponding to this region was not detected in variant 117a, but a 1.7 kb transcript was detected in variant 221a. In isolated nuclei, representative sequences from the 117a, expression site were transcribed unidirectionally at similar rates, and transcription was insensitive to alpha-amanitin.
The variant surface glycoprotein (VSG) genes of Trypanosoma brucei may be transcribed from several distinct telomeric expression sites (ESs). The mechanism responsible for regulating potential ...expression sites is unknown. Two members of a pleomorphic family of expression site associated genes (ESAGs) have been cloned and sequenced. By examination of the DNA sequences we inferred that ESAGs encode amphiphilic glycoproteins. Fragments of two ESAGs were inserted into the Escherichia coli expression vectors pATH and pEX. Antisera to the resulting anthranilate synthetase ESAG protein (ESAGP) fusion protein immune precipitated a 46 kDa glycoprotein from detergent extracts of T. brucei. In the presence of tunicamycin, the size of the immune-precipitated protein was reduced to 36 kDa, corresponding to the molecular weight predicted by the ESAG sequence. The 36 kDa and 46 kDa proteins were absent from procyclic culture forms of T. brucei.
Phase and antigenic variation of pilin expression in Neisseria gonorrhoeae result from recombination events in which variant sequences from one of the silent loci (pilS) are transferred to the ...expression locus (pilE). Such rearrangements were originally thought to be gene conversions, but findings showing that phase variation is partially inhibited by DNase I, that piliated (P+) cells are highly competent for DNA uptake and that gonococci readily undergo autolysis in culture, led to the suggestion that pilin variation occurs through transformation by exogenous DNA. We have developed a simple method for the selection of non-piliated (P-) cells and have evaluated naturally occurring P+ to P- transitions. Two primary pathways of pilin variation can be distinguished--transformation-mediated recombination, which is influenced by culture conditions and inhibited by DNase I, and intragenomic reciprocal recombination, which is unaffected by DNase I. Furthermore, we demonstrate that both piliated and revertible P- cells are competent for DNA uptake, an essential prerequisite of the first pathway.
One hundred twenty-six parturients for elective cesarean section under general anesthesia were allocated to either a cimetidine or an antacid group in a randomized, double-blind, multicenter trial. ...The cimetidine-treated group received 300 mg cimetidine orally the evening before the operation and 300 mg intramuscularly between 1 and 3 h preoperatively. The antacid-treated group received 30 ml of Mylanta-II orally on both occasions. Gastric volume, 30 min after induction of anesthesia and 30 min before response to oral commands, was less in the cimetidine-treated group. Gastric pH 30 min after induction was greater in the cimetidine-treated group. The maternal serum level of cimetidine at birth was 1.31 +/- 0.12 micrograms/ml and the umbilical venous level was 0.78 +/- 0.05 micrograms/ml. The neonatal gastric acidity, Apgar scores, and Early Neonatal Neurobehavioral Scale (ENNS) scores were similar in both groups. No maternal or neonatal complication was attributed to treatment.
Abstract
The pathogenic Neisseria have exploited the processes of horizontal DNA transfer and genetic recombination as mechanisms for the generation of extensive protein variation and modulation of ...gene expression. Localized recombinations have been well documented in members of multigene families as have alterations in short repetitive sequences. Here we report an analysis of the chromosomal structure of a defined lineage of Neisseria gonorrhoeae strain MS 11 pilin variants. This study reveals the occurrence of large rearrangements, including the amplification of a 26 kb region and an inversion involving more than a third of the chromosome. Additionally, a restriction site polymorphism that correlates with pilin expression has been observed. These findings highlight the flexibility of the gonococcal genome.
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