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Biomedical subjects

D A Waters

Publications and source records attributed to D A Waters.

13 recordsLinked to original sources
PubMed1995

Echolocation call structure and intensity in five species of insectivorous bats.

Echolocation call intensity was measured in the laboratory for five species of British insectivorous bats in free flight and in the hand. All species showed similar call intensities of between 80 and 90 dB peSPL (peak equivalent SPL) at 1 m during flight except Plecotus auritus, whose call intensity was between 68 and 77 dB peSPL at 1 m. Calls from stationary bats were about 13 dB less intense than calls during flight. A method is proposed to measure the root mean square (rms) amplitude of echolocation calls and, hence, to calculate the energy flux density of the call. The constant-frequency calls of Rhinolophus hipposideros have energy flux densities approximately ten times higher than those of bats using frequency-modulated calls as a result of their longer durations and lower crest factors. It is argued that the low-intensity calls of P. auritus allow it to approach tympanate moths more closely before triggering their escape response.

Animals↗
PubMed1994

Locked intramedullary nailing of humeral shaft fractures. Implant design, surgical technique, and clinical results.

We report our experience with a modified implant and a new technique for locked intramedullary nailing of the humerus in 41 patients. Locking was by cross-screws placed from lateral to medial in the proximal humerus, and anteroposteriorly in the distal humerus. Early in the series, 11 nails were inserted at the shoulder, but we found that rehabilitation was faster after retrograde nailing through the olecranon fossa, which was used for the other 30. We used a closed technique for 29 of the nailings. Of the 41 patients treated, 21 had acute fractures, five had nonunion, and 15 had pathological fractures. Secure fixation was obtained for comminuted and osteoporotic fractures in any part of the humeral shaft, which allowed the early use of crutches and walking frames. Two nails were locked at only one end, and one of these became the only failure of union after an acute fracture.

Adolescent↗
PubMed1993

Identification of genes involved in utilization of acetate and acetoin in Bacillus subtilis.

The Bacillus subtilis ccpA gene has previously been shown to be involved in repression of amyE expression when cells are grown in excess glucose. The region of the B. subtilis chromosome downstream from ccpA was characterized to determine if additional genes involved in carbohydrate metabolism were present. Two open reading frames that exhibited sequence similarity to the Escherichia coli and B. subtilis motA and motB motility genes were found immediately downstream from ccpA; disruption of this region had no effect on growth, sporulation or motility. Two divergent transcriptional units containing the acsA and acuABC genes were also found in this region. The acsA gene encodes acetyl-CoA synthetase, and inactivation of this gene resulted in loss of the ability to utilize acetate as a carbon source for growth or sporulation. Disruption of the acuABC genes resulted in poor growth or sporulation on acetoin or butanediol. The acsA and acuABC promoter sequences were identified by primer extension, and are in close proximity. Two sequences resembling the amyO regulatory target site necessary for glucose repression of amyE were identified in the acsA-acuABC promoter regions.

Acetate-CoA Ligase↗
PubMed1993

Regulation of the Bacillus subtilis acetate kinase gene by CcpA.

The Bacillus subtilis gene encoding acetate kinase was identified on the basis of sequence similarity to the Escherichia coli ackA gene and to a second E. coli gene closely related to ackA. Insertional inactivation of this region of the B. subtilis chromosome resulted in the disappearance of acetate kinase enzyme activity in cell extracts. The ackA gene was mapped to a site close to the ccpA gene, at 263 degrees. The transcriptional start site for B. subtilis ackA was located 90 bp upstream from the start of the coding region, and expression was increased by growth in the presence of excess glucose. Growth of the AckA- mutant was inhibited by glucose, suggesting that acetate kinase is important for excretion of excess carbohydrate. The stimulation of ackA expression by glucose was blocked in a CcpA- mutant, indicating that CcpA, which is required for glucose repression of certain carbon source utilization genes, including amyE, may also be involved in activation of carbon excretion pathways. Two sequences resembling the amyO operator site were identified upstream of the ackA promoter; removal of this region resulted in loss of glucose activation of ackA expression.

Acetate Kinase↗
PubMed1977

Evaluation of the Hemalog D differential leucocyte counter.

The main objectives of the evaluation were to (1) establish 'normal values' for the Hemalog D, (2) compare the Hemalog D with existing manual procedures, and (3) assess the machine's reliability. It proved to be a practical machine in a routine haematology laboratory. Comparison with established techniques showed systematic differences in the total white blood cell count and percentages of lymphocytes. An existing laboratory computer system was used to collect and file the data.

Adult↗
PubMed1975

Diaphragmatic hernia caused by trauma: experience with 35 cases.

Traumatic diaphragmatic hernia often is not recognized after the initial injury. Early recognition of this entity is of utmost importance since obstruction, strangulation, hemorrhage, viscus perforation, pleural fistula and empyema may occur at any time following the diaphragmatic disruption. A high index of suspicion, history of previous thoracoabdominal trauma, physical examination of the chest and roentgenographic evidence should aid in early and definitive diagnosis. Right-sided herniation should be considered in the differential diagnosis of masses about the right lower lung or diaphragm. Bilateral ruptures may also be encountered. Operation should be performed as soon as the diagnosis is made. In general, transabdominal route should be used in acute ruptures while chronic herniation should be approached through the chest.

Adolescent↗