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Biomedical subjects

A Silberberg

Publications and source records attributed to A Silberberg.

81 records · Page 5Linked to original sources
PubMedDate not supplied

Immediate effects on lung function of instilled human surfactant in mechanically ventilated newborn infants with IRDS.

We have studied the effects on lung volume, respiratory mechanics and ventilation during the first hours after instillation of 60 mg/kg of human surfactant into the trachea of 4 very preterm, newborn infants with severe IRDS under mechanical ventilation. Measurements were made with a "face-out" body plethysmograph and a modified nitrogen wash-out method. In addition to a transient decrease in total and alveolar ventilation immediately after the instillation we found an immediate rise in lung volume, but respiratory compliance decreased. These changes lasted less than two hours. Oxygen requirements fell in 3 out of 4 infants. The changes in lung volume and compliance are explained in terms of changes in the shape of the static recoil pressure characteristics of the diseased lungs after treatment. Mechanisms behind the short duration are sought in mode of instillation, dosage, age at treatment, and severity of disease.

Humans↗
PubMedDate not supplied

Clearance of middle ear effusions by the mucociliary system.

There are two extreme types of middle ear effusion leading to hearing loss (a) a rubber-like effusion seen in secretory otitis media and (b) a water-like effusion seen in serous otitis media. The possibility is considered that the degree of crosslinking in these two extreme cases is the basis of an altered mucus transport rate that leads to an accumulation of effusions and hence impaired hearing. It has been shown (King et al., 1974) that the requisite rheological property for transport activity is not unique to mucus structural macromolecules but is found with other polymeric systems that are loosely crosslinked e.g. guaran, polyacrylamide, gelatin and agarose. Studies on one of these systems guaran, indicate that the transport rate is dependent on the degree of crosslinking with a maximum rate found close to the gel point, i.e. in a region where there are very few crosslinks per macromolecule. The finding that mucus from different mucociliary epithelial sources involves a chemically similar structural glycoprotein suggests that differences observed in transport rate between various mucus samples are more likely due to differences observed in transport rate between various mucus samples are more likely due to differences in crosslinking than chemical variations of the glycoprotein units.

Animals↗
PubMedDate not supplied

Intratympanic gas-pressure in cases of SOM and atelectasis.

Direct manometric measurement of gas pressure in the middle ear, by piercing the tympanic membrane with a hollow needle, has been made leak-free. Even so, the rather small negative pressures (a few mm of H2O2) found in cases of secretory otitis media (SOM) and in atelectatic ears, are in error due to a previously unsuspected, significant correction factor. For the proper application of the correction, the volume of the free gas-space in each ear would have to be known. This volume was unavailable to us for the individual ear, yet in cases like ours it ranges between 0.5 to 2.5 ml and therefore an average of 1.2 ml was assumed. Our results, calculated on this basis, were -34 +/- 86 mmH2O and -9 +/- 86 mmH2O for 24 cases of SOM and 32 cases of atelectasis respectively. Like all previous measurements, there too show a large scatter. This is accounted for by two factors (i) the use of the average instead of the individual ear volume, (ii) actual fluctuation in middle ear aeration and therefore of pressure, pointing to the fact that underaeration is a functional disorder rather than an obstruction of the Eustachian tube.

Ear Diseases↗
PubMedDate not supplied

Determination of the pressure drop across an arterial stenosis utilizing angiocinedensitometry.

A method is presented for an evaluation of the hemodynamic significance of a stenotic lesion in the arterial tree.Twenty-three patients were examined with arteriosclerosis obliterans and intermittent claudication of the same severity. Flow velocity data obtained by angiodensitometry and viscosity values calculated from the hematocrit were inserted into the Poiseuille's flow formula to obtain the pressure drop across a stenotic lesion in the left external iliac artery. By the same way, the pressure gradient was calculated in 33 "normal" subjects.The normal pressure gradient along the external iliac artery varied between 23 to 110 dynes/cm(2) (52 ± 24 dynes/cm(2) for mean and S.d), and the normal resistance to flow was 6.08 ± 4.1 dyne sec/cm(5)).Stenotic lesions of similar dimensions gave widely varying pressure drops (114-4,736 dynes/cm(2)) (mean and S.d 1,309 ± 1,224 dynes/cm(2)) indicating a difference in the hemodynamic significance of the various lesions. These values were significantly different (p(t) < 0.001) from the normal values. The resistance across these stenotic lesions ranged between 21 to 768 dyne sec/cm(5) (196 ± 192 dyne sec/cm(5)) for the mean and S.d and this was significantly different from the normal group; p(t) < 0.001.Direct measurement of blood viscosity coupled with angiocinedensitometry at rest and after forced vasodilatation should provide an accurate means of determining the relative significance of a stenotic lesion and distal vessel disease in a given patient on blood flow to the leg.

Arteriosclerosis Obliterans↗