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Biomedical subjects

N Williams

Publications and source records attributed to N Williams.

At least 19 recordsLinked to original sources
PubMed1997

A prospective evaluation of central venous blood flow using Doppler ultrasound in patients with a long-term central venous catheter.

Using Doppler ultrasound, we prospectively evaluated the relationship between central venous blood flow and the development of central venous thrombosis in ten patients with a long term central line. The presence of turbulent blood flow around the catheter was followed by the development of central venous thrombosis in two patients but neither had subsequent clinical sequelae. More surprisingly, however, normal blood flow was demonstrated in eight patients, two of whom subsequently developed intravascular thrombi.

Adolescent↗
PubMed1997

Radiological confirmation of intraperitoneal free gas.

Although subdiaphragmatic gas on an erect chest or abdominal radiograph usually indicates the presence of a gastrointestinal perforation, this sign is present in only 60-80% of cases. Other less well known radiographic signs of perforation that may nonetheless be of utmost importance in diagnosis are described. The presence of such signs may then prompt further diagnostic procedures or surgical intervention as appropriate.

Humans↗
PubMed1996

The ATP synthase of Trypanosoma brucei is developmentally regulated by an inhibitor peptide.

The Trypanosoma brucei ATP synthase, like those of other organisms, is composed of two moieties, the membrane bound F0 and the catalytic F1 with each of these parts comprised of multiple subunits. In addition, an endogenous inhibitor peptide of the ATP synthase has been identified from a variety of sources. Previous reports have suggested that the Trypanosoma brucei ATPase may not possess such an inhibitor. Recently, we have isolated an inhibitor peptide fraction from the procyclic form of Trypanosoma brucei by modification of a previously published procedure. This fraction is composed of two dominant polypeptides with estimated molecular weights of 14,000 and 12,000 and an additional polypeptide of 15,000 that may or may not be functionally required. Antibodies raised to the smallest polypeptide showed strong cross reactivity with the other two polypeptides, suggesting that they are related. Antibodies to rat liver inhibitor peptide show cross reactivity with the same polypeptides in crude fractions. The inhibitor peptide fraction strongly suppresses the ATPase activity of membrane bound ATPase in a Mg(2+)-dependent manner and is cold and heat stable. Using antibodies to the smallest polypeptide and rat liver inhibitor peptide we have shown in crude extracts from the three experimental life cycle stages of T. brucei that the inhibitor peptide(s) is developmentally regulated to a modest extent. The pattern of regulation is opposite of the pattern seen for the ATP synthase complex. This suggests that the ATP synthase is stringently controlled in T. brucei in a unique way.

Animals↗