Transfer of immunoglobulins and antibodies in the hen's egg

The presence of immunoglobulins and antibodies were investigated in the fertile hen's egg during embryogenesis. The egg yolk, egg albumin, amniotic and allantoic fluids, chick embryo serum and intestinal contents were examined for the presence of immunoglobulin and level of antibodies.

Immunoglobulin G was not detected in fresh egg albumin, but appeared in the albumin from the 4th day of embryogenesis and persisted through the 16th day. The antibody profile of egg albumin during embryogenesis attained two peaks, which were separated by a trough on the 8th day of embryogenesis. The immunoelectrophoretic pattern of albumin IgG was different from that of egg yolk IgG.

The IgG of chick embryo serum was of γ₂ mobility on the 12th day of incubation and shifted gradually to the full range of γ₁ and γ₂ mobilities on the 20th day of incubation. Egg-transmitted antibodies appeared on the 12th day of incubation and attained peak values on the 16th day of incubation.

Moderate antibody levels were detected in the amniotic and allantoic fluids from the 12th to the 18th days of incubation.

     

The Canadian National Calibration Reference Centre for In-Vivo Monitoring: thyroid monitoring. Part I: The national inter-comparison programme

This article is the first part of a five-part series covering various aspects of occupational thyroid monitoring. The Canadian National Calibration Reference Centre for In-Vivo Monitoring conducts a thyroid inter-comparison programme that now includes more than 100 facilities. The scope of the programme, begun in 1988, has greatly expanded in the last two years following a considerable effort to locate and inform facilities. This article presents the details of the programme, its results, and the lessons learned. Subsequent articles will discuss sources of errors, methodology, instrumental configuration, and counting geometry optimization.     

Development of a PC-based expert system for lower urinary tract pressure-flow studies

Summary An on-line personal computer (PC)-based expert system was constructed for pressure-flow study of the lower urinary tract. An empty expert-system shell and supplementary programs were used for this system; the latter served to compensate the defects of the shell and are referred to as data programs in this report. The data programs were written in the C programming language and were used for on-line data sampling, data entry using a photoscanner, calculation of parameters, saving and loading of data, graphic display, and printing. The urodynamic pressure-flow expert system necessitates on-line data transfer, since it requires a large volume of data. However, off-line data recorded on paper was also made available for ready input by a photoscanner. Reasonable diagnostic accuracy has been achieved by our new expert system for pressure-flow studies. It should be useful in the clinical setting as well as for teaching urological students.Presented at the 19th Annual Meeting of the International Continence Society, Ljubljana, 1989, and published elsewhere as an abstract (Neurourol Urodyn 8:409–410)     

A comparison of perinatal mortality between ethnic Chinese and ethnic whites: Why the Chinese rate was lower

Objectives. To confirm the observation that has been occasionally reported in the literature that perinatal mortality rate is lower in ethnic Chinese than in ethnic whites, and to assess the reasons for this lower perinatal mortality rate.

Methods. Secondary‐analysis based on published data.

Results. This exercise demonstrates that the perinatal mortality rate was lower in ethnic Chinese than in ethnic whites. The birth weight distribution in ethnic Chinese was more favourable with reduced births at two extremes of the distribution, and the exposure to risk factors for perinatal death by their mothers was also lower.

Conclusion: Perinatal mortality rate is lower in ethnic Chinese than in ethnic whites, and the lower perinatal mortality rate in ethnic Chinese is probably caused by their favourable birth weight distribution and lower exposure to risk factors of perinatal death by their mothers.     

The Canadian National Calibration Reference Centre for In-Vivo Monitoring. Part II: Sources of errors in thyroid monitoring of occupationally exposed personnel

This article, the second of a five-part series covering various aspects of occupational thyroid monitoring, addresses the sources of error that can affect the final result obtained from thyroid monitoring, such as geometry effects (thyroid size, thyroid depth, precision and accuracy of the detector placement, and neck-detector distance). The article also suggests ways in which these errors can be minimized and identifies those errors that are difficult to quantify.     

Evaluation of low dose prostaglandin E1 treatment for ductus dependent congenital heart disease

This study reports our experience with low-dose prostaglandin E₁ (PGE₁) treatment of 91 newborns with ductus dependent congenital heart disease (CHD). PGE₁ efficacy, side-effects as well as the cardiovascular and respiratory profile of the patients were analysed. PGE₁ doses > 0.02 g/kg per minute were used for only 5.3% of the total 23 656 h of treatment. The mean systolic blood pressures did not differ from the normal mean for patients with cyanotic CHD, while the diastolic values were lowered. Respiratory support was required only during 13.7% of the total treatment time. Apnoeas occurred in 21 (38%) of the 55 spontaneously breathing infants, who all had a cyanotic CHD. The incidence of apnoeas was lower during treatment with doses < 0.01 g/kg per minute.     

Growth factor regulation of integrin-mediated cell motility

Summary Cell motility, a primary component of tumor cell invasion, is a continuum of sequential events in which the cell extends pseudopodia, forms nascent attachments, assembles and contracts the cytoskeleton, and finally, as it translocates forward, disengages distal adhesions. What triggers cells to move? Substratum contact mediated by integrin adhesion receptors is important, but other signals such as chemokinetic factors appear to be required for continued crawling. It is now apparent that integrins do not simply bind cells to matrix in a Velcrolike fashion, but also are potent signaling molecules. Initial engagement of integrins induces their condensation into focal contacts, forming anchors to the extracellular matrix and discrete signal-transducing complexes on the cytoplasmic surface. A number of growth factors, through either autocrine or paracrine pathways, can activate the cellular machinery that mobilizes the cell. Thus, these two classes of receptors - the integrin receptors that bind specific extracellular adhesion molecules, and growth factor receptors that bind their respective ligands - can regulate cell locomotion. Not surprisingly, there is cross-talk between integrin and growth factor receptors that occurs through their common intracellular signaling pathways. In this way, each receptor type can either amplify or attenuate the other's signal and downstream response. An example of growth factor-induced motility is the epithelial-mesenchymal transition induced by hepatocyte growth factor/scatter factor (HGF/SF). When bound to its receptor, the c-met proto-oncogene product, HGF/SF induces a phenotypic conversion that appears to be an important aspect of tumor progression in malignant carcinomas. The motogenic response produced by HGF/SF in carcinoma cells occurs in discrete steps in which integrins and focal adhesion kinase (p125^FAK) are first recruited to focal contacts. This is rapidly followed by cell spreading, disruption of focal adhesions and cell-cell contacts, and, finally, cell crawling. The precise mechanism by which growth factors such as HGF/SF and its receptor induce this motogenic response and modulate integrin function has not been clearly defined but appears to involve several signaling pathways. Understanding the process by which growth factor and integrin receptors interact and regulate motility may suggest novel targets for therapeutic intervention.     

Lung counting: a function to fit counting efficiency of a lung counting germanium detector array to muscle-equivalent-chest-wall-thickness and photon energy using a realistic torso phantom

A function has been developed that will fit counting efficiency to chest wall thickness, adipose content of the chest wall, and photon energy. The adipose content of the chest wall is removed as a variable by use of the derived quantity: muscle equivalent chest wall thickness. The function has been tested on experimental data sets obtained from the LLNL and JAERI torso phantoms using a variety of germanium detector lung counting systems. The function is applicable over the range of existing phantoms and the range of equipment types tested. Subtle differences between the detector systems are shown by differences in the fit parameters. This analysis could be a useful addition to lung counting analysis software. The LLNL and JAERI phantoms have very similar counting characteristics as evidenced by the similarity of the function parameters when measured using a single detector system.     

Error-related processing during a period of extended wakefulness

The nature of error detection as manifested by the error-related negativity was examined in both a Sternberg memory search task and a visual search task. Both tasks were performed in conditions with consistent or varied stimulus-response mapping and loads of three or six letters. After subjects were trained extensively in all conditions, they performed the tasks throughout the night without sleeping. The data suggest that the effectiveness of error detection decreases over time because of a decrease in the quality of perceptual processing. Error detection also suffers when performance requires more search-related resources. In both cases, the representation of the correct response is compromised. These results indicate that error detection depends on the same perceptual and cognitive processes that are required for correct performance.