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S Ross

Publications and source records attributed to S Ross.

25 records · Page 2Linked to original sources
PubMed1977

Signal enhancement for detection of specialized atrioventricular conduction system electrograms during open-heart surgery.

A method for signal enhancement of electrograms of the specialized atrioventricular conduction system is presented. This method allows a single electrogram to replace the tracings of bipolar electrograms previously required to ensure recognition of the specialezed conduction system and yet maintains the safety afforded by use of three pairs of recording electrodes. In addition, this new signal is enhanced in magnitude and is always unidirectional (positive). These features are desirable for automated signal recognition. This method therefore provides an important step toward future automation and signal recognition of specialized conduction system electrograms during open-heart surgery.

Animals↗
PubMed1976

Mycoplasma T strains and perinatal death.

In 23 out of 290 perinatal deaths in Addis Ababa, mycoplasma T strains were the only organisms responsible for congenital pneumonia and death. All but 2 of the infants were stillborn, 16 dying during the last six weeks of gestation. Infections apparently occurred through intact fetal membranes.

Animals↗
PubMed1976

Intraoperative recording of the His bundle electrogram in man. An assessment of its precision.

To estimate the effect of distance between the electrode and the signal source on the amplitude of the His bundle electrogram (HBE) recorded during open heart surgery, a specially designed probe, containing six pairs of closely spaced (1 mm) electrodes was placed on the endocardial surface of the right atrium such that each electrode pair was parallel to the course of the His bundle. The amplitude of the HBE recorded through electrodes closest to the His bundle ranged from 0.76 to 2.44 mV, at 1mm from 0.38 to 1.13 mV, at 2mm from 0.27 to 0.86 mV, and at 3 mm from 0.2 to 0.44 mV. Maximal amplitude of HBE decreased by 57% at 1mm, 73% at 2 mm, and 82% at 3mm. The percent decrease was initially rapid, then declined more slowly at distances greater than 1 mm, resembling in form data obtained previously in animal studies by different techniques. Since the maximum HBE was greater than 1.0 mV in nine of 11 patients, and equal to or greater than 1.0 mV in only two of 11 patients at 1 mm, and less than 1.0 mV in all patients 2.0 mm from the maximal HBE, the anatomic location of the His bundle can be estimated from HBE amplitude. Intracardiac electrograms, recorded through closely spaced bipolar electrodes during open heart surgery, afford clinically useful precision in locating the specialized conduction tissue of the heart.

Adolescent↗
PubMed1975

Limulus lysate test for gram-negative bacterial meningitis. Bedside application.

The limulus lysate on cerebrospinal fluid was evaluated in 335 infants and children as a method for the rapid diagnosis of Gram-negative bacterial meningitis. Positive limulus tests were obtained within one hour in 33 of 34 cases of Hemophilus influenzae meningitis; four additional patients with Gram-negative meningitis also showed positive limulus lysate tests. Conversely, 13 patients with Gram-positive bacterial meningitis all yielded negative limulus assays. All 48 cases of aseptic meningitis and 236 children with no meningitis showed negative limulus assays. Antibiotic therapy prior to hospitalization did not vitiate the validity of the test. A bedside adaptation of the limulus test, performed by house officers and medical students, showed approximately 98% agreement with the laboratory assay.

Arachnida↗
PubMed1975

S-adenosylhomocysteine inhibition of three purified tRNA methyltransferases from rat liver.

Three tRNA methyltransferases from rat liver have been fractionated and purified greater than 100-fold. These enzymes have been examined for their sensitivity to inhibition by S-adenosylhomocysteine (SAH). The methyltransferase which forms m2-guanine in the region between the dihydrouridine loop and the acceptor stem of tRNA (m2-guanine methyltransferase I) is least sensitive to SAH inhibition, with a Ki of 8 muM. The enzyme responsible for forming m2-guanine between the dihydrouridine and anticodon loops (m2-guanine methyltransferase II) has a Ki of 0.3 muM, while m1-adenine methyltransferase shows intermediate sensitivity to SAH (Ki = 2.4 muM). All three methyltransferases have similar Km's for the S-adenosylmethionine substrate (1.5-2.0 muM). These results are consistent with the hypothesis that activity of individual tRNA methyltransferases may be controlled by enzyme systems which alter cellular SAH levels.

Adenine↗