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Biomedical subjects

D Major

Publications and source records attributed to D Major.

69 records · Page 4Linked to original sources
PubMed1966

Synapses of horizontal cells in rabbit and cat retinas.

Horizontal cells in the retinas of cats and rabbits are morphologically similar; in both species, two types can be distinguished in Golgistained material. Horizontal cells and their processes are readily recognized in electron micrographs, and many of the horizontal cell processes appear to make synaptic contacts with dendrites and somata of bipolar cells, and probably with other horizontal cells. The synapses of the horizontal cell appear similar to chemical synaptic contacts described throughout the nervous system. With the finding of synaptic contacts, it seems clear that retinal horizontal cells should be classified as neurons.

Animals↗
PubMedDate not supplied

Pumpless respiratory assistance using a membrane oxygenator as an artificial placenta: a preliminary study in newborn and preterm lambs.

Newborns suffering from severe respiratory difficulties and not responding to conventional methods have been successfully treated by extracorporeal circulation with a membrane oxygenator (ECMO). However, the technique needs a highly specialized staff, excellent laboratory support, and continuous surveillance of the procedure to prevent complications. In a series of experiments on newborn and preterm lambs, we have investigated a relatively simpler technique of respiratory support that involves a pumpless arteriovenous bypass by cannulating both umbilical arteries and the umbilical vein. A highly efficient microporous membrane oxygenator (MO) with very low resistance was selected. This type of perfusion that mimics the placental circulation, besides providing an additional amount of oxygen to the blood, has proven to be very effective for CO2 extraction. Before its application in humans, however, improvements in the catheters to be inserted in the umbilical vessels, some modifications in the design of the MO, and improvements in the blood compatibility of all foreign surfaces in contact with blood are needed.

Animals↗
PubMedDate not supplied

[Estimation of PaO2 using pulsatile oximetry and the HbO2 dissociation curve in the premature infant].

An estimation of arterial PO2 from pulse oximetry using oxyhemoglobin dissociation curve. Forty blood specimens were drawn from umbilical arteries of the neonates having a pulse sensor attached to either foot or hand. The sensor was connected to a Nellcor-N100C in twenty cases and to an Ohmeda Biox-3700 for the remaining. Mean birth weight was 1,513 g, mean gestational age 32.4 weeks, and foetal hemoglobin ranged from 54.8 to 100%. Oxyhemoglobin dissociation curves were drawn for each arterial sample to obtain P50 and estimated PO2. The estimated PaO2 was the PO2 corresponding, on the oxyhemoglobin dissociation curve, to the pulse oximeter saturation reading. Mean difference between blood saturation and pulse oximeter saturation of 1.2% was obtained with Nellcor and of 3.9% with Ohmeda. Arterial and estimated PO2 comparison gave a mean + S.E.M. difference of 4.6 +/- 1.3 torr for all cases. This represents less than 8% error in estimating PaO2 from pulse oximetry. We suggest the following polynomial equation Y = 4250 - 10.4X + 0.069X2 for using pulse oximetry (X) to evaluate PaO2 (Y) in premature infants.

Humans↗