Thoracic traction on the trachea: mechanisms and magnitude

Both inspiratory increases and tonic thoracic traction (pull of the thorax) on the trachea [Ttx(tr)] have been shown to improve patency of the upper airway. To evaluate the origins and magnitude of Ttx(tr), we studied 15 anesthetized tracheotomized dogs. We divided the midcervical trachea and attached the thoracic stub to a strain gauge. Ttx(tr), esophageal pressure, and carinal displacement were observed during various conditions. These included unobstructed and obstructed spontaneous breathing, mechanical ventilation at various levels of positive end-expiratory pressure, and progressive hypercapnic stimulation. Observations during spontaneous breathing were performed before and after vagotomy. We found that inspiratory increases in Ttx(tr) were substantial, averaging 81 +/- 8 g force and increasing to 174 +/- 22 g force at an end-expiratory CO2 concentration of 10%. Ttx(tr) did not result simply from the pull of mediastinal and pulmonary structures transmitted through the carina. Changes in intrathoracic pressure acted independently to either draw the trachea into or push the trachea out of the thorax. Thus Ttx(tr) could be explained as the sum of mediastinal traction and force generated by changes in intrathoracic pressure.     

Nonvitellogenic female protein in Musca domestica

During vitellogenesis in Musca domestica, a major hemolymph protein, in addition to vitellogenin, appears preferentially in females. This protein is synthesized by the adult fat bodies, secreted into the hemolymph, and is not taken up by the ovaries during vitellogenesis. We have designated this protein nonvitellogenic female protein (NVFP). It is composed of only one type of polypeptide (M_r=70,000) and occurs in two different forms. Synthesis of NVFP is induced by a protein diet, attaining maximum concentrations in females at the middle of the gonotrophic cycle. In males its maximum concentration never surpasses 10% of the concentration in females. The quantitative variation of the NVFP is cyclic and coincident with the gonotrophic cycles of Musca domestica.     

Current concepts in trauma: 2. The Sunnybrook Medical Centre trauma program: the first 11 years.

Sunnybrook Medical Centre is a tertiary care teaching hospital situated in metropolitan Toronto. Its trauma unit, opened in June 1976, serves the inhabitants of metropolitan Toronto and the surrounding area (approximately 5 million). More than 3200 patients were admitted to the unit between 1976 and 1987. The criteria for admission were age at least 14 years and an Injury Severity Score (ISS) of 16 or greater, two or more significant injuries at anatomically discrete sites when the score on the Abbreviated Injury Scale was 3 or greater, or grade IV shock (systolic blood pressure of 80 mm Hg or less). The number of patients admitted annually to the unit increased over the study period. The survival rate also increased, from 76% in 1976 to 88% in 1987, although the average age and ISS of the patients remained unchanged. Less than 2% of the patients required long-term rehabilitative or chronic care. The patient profile is similar to that seen in other trauma centres in North America. The success of this program is largely the result of expeditious stabilization and transfer from referring hospitals coupled with early definitive surgical intervention.     

Relationship between computerized morphonuclear image analysis and histopathologic grading of breast cancer

A pilot study analyzed the relationship between several morphonuclear parameters and the Bloom-Richardson score for 37 invasive, not-otherwise-specified (NOS) ductal breast carcinomas. The SAM-BA 200 cell image processor and its software were used to measure the nuclear features on Feulgen-stained imprint smears. Two parameters representing the numbers of large and dense chromatin clots and two parameters describing the heterogeneity of the chromatin among nuclei in a specimen evolved in a continuous manner parallel with the Bloom-Richardson score from stages NOS-4 to NOS-8. The systematic measurement of these four parameters on a large series of breast cancers may be able to define an objective and reproducible "scale" of differentiation that could be a helpful tool for pathologists and clinicians.     

Pulsed-field gel analysis of human immunoglobulin heavy-chain constant region gene deletions reveals the extent of unmapped regions within the locus

The human immunoglobulin heavy-chain constant region gene locus is organized in three main gene groups, the physical distances of which are unknown. Different types of gene deletions, originated by unequal crossingover, have been found to encompass one or more genes in the locus. We have analyzed some of these deletions by means of pulsed-field gel electrophoresis, which allows resolution of large DNA fragments. By identifying a fragment containing two of the main gene groups and by observing the size reduction of this fragment in subjects with deletions, we were able to estimate the distance between the two groups and better locate the pseudogene in-between.     

2,3,7,8, tetrachlorodibenzo-p-dioxin induces oxygen activation associated with cell respiration

We have investigated the influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on bioenergetic functions of isolated heart-mitochondria. Electron transfer and energy conservation activities were found to be decreased in the presence of very low amounts of the polychlorinated biphenyl compound (1.5 nmol/mg mitochondrial protein). The effect was greatest when substrates for complex I were used. In this case coupling of oxidative phosphorylation to respiration was drastically diminished, essentially at the expense of state 3 respiration, and P/O values were found around 2 instead of 3. Succinate-related energy conservation remained practically unaffected in the presence of TCDD, suggesting an interference of the toxic compound at coupling site I. SOD plus catalase were found to protect energy-linked respiration from the effect of dioxin indicating the involvement of superoxide radicals and H2O2 in the development of the observed phenomena. The present contribution provides experimental evidence on the formation of these oxygen species in the presence of TCDD. Furthermore, the site of action of TCDD is demonstrated and discussed in relation to the oxygen radical formation observed.