Antagonistic interactions between alleles of the RpII215 locus in Drosophila melanogaster

The RpII215 locus encodes the large subunit of RNA polymerase II (polII). Three of 22 RpII215 alleles cause a synergistic enhancement of the mutant phenotype elicited by mutations in the Ultrabithorax (Ubx) locus. We have recovered and analyzed three new mutations that suppress this enhancement. All three mutations map to the RpII215 locus. In addition to suppressing the Ubx enhancement of other RpII215 alleles, two of the new mutations, JH1 and WJK2, themselves enhance Ubx. RpII215 alleles can be placed into three classes based on their ability to enhance Ubx. Class I alleles, including Ubl, C4, C11, JH1, and WJK2, enhance Ubx when heterozygous with class II alleles, which include wild-type RpII215. Class III alleles, which include amorphic alleles, do not enhance Ubx. The third new mutation, WJK1, is a conditional amorphic allele, which behaves like a class III allele at 29 degrees but like a class II allele at 19 degrees. Another mutant phenotype is caused by certain RpII215 alleles, including all class I alleles. This phenotype is a synergistic enhancement of a mutant phenotype elicited by mutations at the Delta (Dl) locus. Unlike the enhancement of Ubx, the enhancement of Dl is not dependent upon antagonistic interactions between different classes of RpII215 alleles.

Physical identification of branched intron side-products of splicing in Trypanosoma brucei

Every mRNA in trypanosomes consists of two exons, a common 5' capped mini-exon or spliced leader and a coding-exon. All evidence suggests that the exons are joined by trans-splicing of two individual precursor RNAs, the mini-exon donor RNA or spliced leader precursor RNA (medRNA) and the pre-mRNA. We studied intermediates of the splicing reaction using denaturing two-dimensional PAGE and structurally identified a group of small (approximately 180-300 nt) non-polyadenylated, Y-shaped branched RNAs. The branched Y-shaped RNAs contain the 105 nt medRNA derived intron, joined in a 2'-5' phosphodiester bond to small heterogeneously sized RNAs. These non-polyadenylated branched Y-shaped RNA molecules are analogous to the lariat shaped introns of higher eukaryotes and presumably represent the released intron-like by-products of a trans-splicing reaction which joins the mini-exon and the major coding-exon.

Airway pressure-volume curve estimated by flow interruption during forced expiration

The pressure-volume characteristics of the airway downstream to the choke point was estimated with abrupt interruption of airflow at the mouth during forced expiration. The pressure was measured at the mouth and the volume was given by the maximum flow immediately before interruption multiplied by interruption time. The compliance of the airway downstream to the choke point, i.e., a slope of the pressure-volume curve, was 1.04 ml/cmH2O at 50% FVC, and increased in lower lung volumes, in 7 healthy subjects. Whereas, in a case of tracheo-bronchopathia osteochondroplastica, its value decreased markedly.

Mouth pressure curve on abrupt interruption of airflow during forced expiration

The mouth pressure curve after abrupt interruption during forced expiratory maneuver was investigated to evaluate the collapsing state of the airway downstream to the choke point. Immediately after the airflow interruption at the mouth by means of the electromagnetic valve, the mouth pressure suddenly increased (1st phase), followed by a slower rise (2nd phase) within about 100 msec until the pressure reaches the alveolar pressure. The pleural and alveolar pressures remained constant during this process. It was evidenced that, from point of view of mean flow, the airflow flowed at a rate of Vmax through the choke point during the second phase. Thus, it is strongly suggested that the choke point remained at the same point during the 2nd phase. From these results, the 2nd phase of the mouth pressure is expected to represent the specific characteristics for the downstream airway.

Asbestos fibers in human pulmonary and extrapulmonary tissues

The association between asbestos fibers in human lung tissues and those in other extrapulmonary organs was studied by analysing three autopsied cases, one of whom had a high pulmonary asbestos burden, one an intermediate burden, and one a low burden. The amount, types and sizes of asbestos fibers in the tissues of lung, liver, spleen, pancreas, kidney, and gastrointestinal tract were identified and measured by transmission electron microscopy equipped with an energy dispersive X-ray analyser. The following results were obtained: 1) The concentrations of asbestos fibers in extrapulmonary organs tended to increase with that in lung tissues. 2) The types of fibers identified in lungs were approximately consistent with those in other organs. 3) A relatively large range of fiber length was observed in both lungs and other organs. The findings extend and support previous light microscopic studies comparing asbestos bodies in various organs, and may imply that persons with high levels of asbestos in their lungs are also likely to have the same types and high levels of asbestos in their other tissues.

A new method for measuring the pneumotachometer characteristics using a syringe

A new method for determining the nonlinear characteristics of pneumotachometers was developed. This method consists of a computer algorithm analyzing unsteady flows generated by a syringe. We removed the possible influence of the frequency characteristics of the measuring system by inserting an acoustic low pass filter in the path of gas flow. Two types of Fleisch pneumotachometers were tested. For a given volume of 3 l, the error of measured volume is 12.5% in uncorrected series and 0.2% in the corrected.

Chicken glucagon: sequence and potency in receptor assay

Glucagon is a 29 amino acid peptide that is generally highly conserved. Among mammalian glucagons the only one that has been shown to differ significantly is that of the guinea pig which differs from the others in 5 of the 9 COOH-terminus amino acids. The amino acid content and partial sequencing of chicken glucagon had been reported earlier. This report describes the purification and complete amino acid sequencing of chicken glucagon and demonstrates that it differs from the usual mammalian glucagon by the replacement of asparagine at position 28 with serine. Chicken glucagon is indistinguishable from porcine glucagon in the rat liver receptor assay system.

Roles of cis-acting elements and chromatin structure in Drosophila alcohol dehydrogenase gene expression

The alcohol dehydrogenase (Adh) gene of D. melanogaster is transcribed from two different promoters during fly development: the distal (adult) and the proximal (embryonic-larval). Certain aspects of Adh gene regulation are represented in Drosophila continuous cell lines. We have used Drosophila tissue culture cells in an in vivo transient expression assay to delimit cis-acting sequences affecting Adh expression, and to investigate the role of chromatin structure in Adh gene regulation. These studies show that positive cis-acting elements of the distal promoter can exist in at least 2 alternative chromatin configurations. There is a close correlation between specific transcriptional activity of the Adh distal promoter and a defined, localized chromatin structural change that indicates altered DNA-protein interactions. Thus, chromatin structure appears to play a role in regulating the accessibility of defined positive cis-acting regulatory sequences of Adh to transcription factors and the transcription machinery.

Repeated laparotomy for postoperative intra-abdominal sepsis. An analysis of outcome predictors

To identify factors modifying the outcome of reoperation for intra-abdominal infection, we analyzed the management of 47 patients who underwent repeated laparotomy from July 1980 through July 1985. Overall mortality was 30% (14/47). Factors predictive of death were as follows: age greater than 60 years (86% mortality vs 21% mortality), preoperative vs no organ failure (57% vs 6%), multiple vs single abscess (53% vs 16%), and exploratory vs directed operative approach (39% vs 17%). Although the interval between the primary surgery and reoperation was similar between survivors (13 days) and nonsurvivors (14 days), five (36%) of 14 nonsurvivors were in septic shock and eight (57%) of 15 survivors showed evidence of organ failure prior to reoperation. The median survival period following reoperation in this group was only four days. Computed tomography (CT) and/or ultrasonography were performed to localize a source of infection in 24 patients. In nine (82%) of 11 patients, CT identified the abscess, while ultrasonography was positive in 15 (72%) of 21 patients. Neither the interval to operation nor the mortality was significantly different in patients diagnosed with CT and ultrasonography when compared with those who underwent exploration on the basis of clinical findings. To lower the mortality and to shorten the interval to reoperation in these high-risk patients, noninvasive diagnostic testing and confirmation by percutaneous sampling must be sought before the onset of clinical sepsis and organ failure.

Substrate specificity of anti-epithelial antibodies of pemphigus vulgaris and pemphigus foliaceus sera in immunofluorescence tests on monkey and guinea pig esophagus sections

The indirect immunofluorescent (IF) reactivity of the pemphigus antibodies in sera of 21 cases of pemphigus vulgaris (PV), 15 cases of pemphigus foliaceus (PF), and 14 cases of Brazilian PF (BPF) was compared on 2 substrates, notably monkey esophagus (ME) sections and guinea pig esophagus (GPE) sections. The IF reactions of the pemphigus antibodies of PV could be distinguished from those of PF or BPF by differences in their reactivity on ME and GPE sections in 98% of the cases examined in this study. In most cases, the pemphigus antibodies of PV cases gave higher titers and stronger IF staining reactions on ME sections, while those of PF and BPF cases gave stronger reactions on GPE sections. In addition, most (13 of 21) PV sera react with the lowest 3-4 cell layers of ME sections, while most (13 of 15) PF sera failed to do so but did react with the upper layers of the sections. Importantly, in 8 of the 50 cases examined by IF, the choice of substrate affected the detectability of the pemphigus antibodies, i.e., 4 of 15 PF and 2 of 14 BPF sera reacted only with GPE and 2 of 21 PV sera reacted only on ME. These research findings point to the need for an evaluation of the combined use of ME and GPE in routine diagnostic studies of pemphigus antibodies.

Urinary elimination of acetone in experimental and occupational exposure

Fifteen volunteers were exposed to an acetone vapor concentration of 964-8, 610 mumol/m3 (56-500 mg/m3) for 2-4 h in an exposure chamber. Ten subjects were at rest during the exposure, and five were exposed at alternate rest and light physical exercise. Subsequently 104 workers occupationally exposed to acetone were studied. The relative uptake averaged about 53%, and the ratio of the alveolar concentration to the environmental concentration averaged about 0.28. Both for the experimentally exposed subjects and the occupationally exposed workers the urinary acetone concentration showed a linear relationship to the corresponding environmental time-weighted average concentration. A linear equation also existed between urinary concentrations and the amounts of acetone absorbed. The findings enable a consideration of the urinary concentration of the unaltered acetone as an appropriate exposure indicator and the proposal of a "biological equivalent threshold" to be used in the field of biological monitoring.

Monoamine oxidase: an important intracellular regulator of gastrin release in the rat

The role of monoamine oxidase (MAO) in the meal-induced or amino acid-induced release of gastrin was investigated. Rats that were pretreated with the nonspecific MAO inhibitor nialamide (200 mg/kg) showed a greater rise in meal-induced serum gastrin than did untreated controls. In vitro experiments demonstrated that gastrin secretion from dispersed antral G cells in response to a stimulatory dose of phenylalanine or methylbenzylamine (10 mM) was markedly enhanced if the cells were treated with nialamide. Studies with the more specific MAO inhibitors clorgyline and deprenyl indicated that antral mucosa contained predominantly type A activity. Inhibition of MAO type A with clorgyline, both in vivo and in vitro, resulted in a greater release of gastrin after stimulation by a meal or phenylalanine. It is concluded that MAO may play an important role in the regulation of gastrin release from the G cell by partially controlling the level of amines within the cell.