PubMed · 10692889
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Y Koak, T A Jeddy, A E Giddings. 1999. Appendico-cutaneous fistula.. https://doi.org/10.1177/014107689909201211
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Previously it was shown that beta(2)-integrins are necessary for slow leukocyte rolling in inflamed venules. In this study, mice that are deficient for either one of the beta(2)-integrins, alpha(L)beta(2) (LFA-1) or alpha(M)beta(2) (Mac-1), were used to determine which of the beta(2)-integrins are responsible for slowing rolling leukocytes. The cremaster muscles of these mice were treated with tumor necrosis factor-alpha and prepared for intravital microscopy. The average rolling velocities in venules were elevated in LFA-1(-/-) mice (11.0 +/- 0.7 microm/s) and Mac-1(-/-) mice (10.1 +/- 1.1 microm/s) compared to wild-type mice (4.8 +/- 0.3 microm/s; P <.05), but were lower than in CD18(-/-) mice (28.5 +/- 2.1 microm/s). When both LFA-1 and Mac-1 were absent or blocked, rolling velocity became dependent on shear rate and approached that of CD18(-/-) mice. In addition, leukocyte adhesion efficiency was decreased in LFA-1(-/-) mice to near CD18(-/-) levels, but decreased only slightly in Mac-1(-/-) mice. Thus, both LFA-1 and Mac-1 contribute to slowing down rolling leukocytes, although LFA-1 is more important than Mac-1 in efficiently inducing firm adhesion.
Identification of thoracoabdominal asynchrony (TAS) during breathing is currently detected by visual coding of records of ribcage (RC) and abdominal (AB) movements. There is thus a need to automate this process in order to save time and improve TAS detection accuracy. We studied 15 infants of 39-49 weeks postconceptional age. RC and AB signals were recorded continuously by inductance plethysmography for 4-24 hr immediately after herniorraphy. In our novel analysis approach, the records were divided into 10 sec epochs, and the equation RC = alphaAB + beta was fit to each epoch, using recursive linear regression with an exponential memory time constant of 1 and 2 sec. This yielded 10 sec signals for alpha corresponding to each epoch. The fraction of time that each alpha signal was positive was taken as a measure of synchrony between RC and AB for that epoch, while asynchrony was indicated by the fraction of time the signal was negative. We also assessed synchrony and asynchrony using a conventional measure known as thoracic delay (TD), which is based on the degree to which the peaks in RC and AB are coincident in time. Using TD as the basis of comparison, we found that our new recursive least squares method gave a positive predictive value of 99%. We conclude that our recursive least squares method is able to accurately identify portions of the RC and AB records that correspond to TAS, and we speculate that it may be useful in automating detection of TAS.
Phrenic nerve stimulation (PNS) can assess airflow dynamics of the upper airway (UA) during wakefulness in man. Using PNS, we aimed to assess the impact of neck flexion and mouth opening in promoting UA unstability. Measurements were made during nasal breathing in seven healthy subjects (ages = 23-39 yr; one woman). Surface diaphragm electromyogram, esophageal pressure referenced to mask pressure, and flow were recorded during diaphragm twitches with neck in neutral position and mouth closed and then with neck flexion and/or mouth opening. Twitches always exhibited a flow-limited pattern. Flow-limiting driving pressure (Pd) and peak Pd were increased by neck flexion (P < 0.01) without significant change in the corresponding flows. UA resistances at these flow values were higher with the neck flexed (P < 0.05). Mouth opening alone did not exert any significant influence. We conclude that the position of the neck has a discernible impact on the flow behavior through the nonphasically active UA faced with a negative Pd.