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Biomedical subjects

A M Clarke

Publications and source records attributed to A M Clarke.

At least 55 records · Page 3Linked to original sources
PubMed1991

Human ultrasonic speech perception.

Bone-conducted ultrasonic hearing has been found capable of supporting frequency discrimination and speech detection in normal, older hearing-impaired, and profoundly deaf human subjects. When speech signals were modulated into the ultrasonic range, listening to words resulted in the clear perception of the speech stimuli and not a sense of high-frequency vibration. These data suggest that ultrasonic bone conduction hearing has potential as an alternative communication channel in the rehabilitation of hearing disorders.

Adult↗
PubMed1991

Species identification and antibiotic resistance patterns of the enterococci.

One hundred and forty isolates were identified using the GPI Card (Vitek Systems) and a conventional biochemical scheme. Agar dilution susceptibility testing was performed and isolates were screened for beta-lactamase production. The GPI Card was accurate in identifying Enterococcus faecalis, but discrepant results were obtained for seven (29.1%) of the 24 non-Enterococcus faecalis isolates. Ampicillin resistance was present in 2.9% of isolates and there were no beta-lactamase producers. There was no vancomycin resistance but 12.1% of isolates showed high-level resistance to gentamicin.

Ampicillin Resistance↗
PubMed1991

In vitro activity of the novel cephalosporin GR69153.

The in vitro activity of GR69153 was compared to that of ceftazidime, ceftriaxone, imipenem and gentamicin against a total of 702 recent clinical isolates. MICs were determined by a standard agar dilution procedure and two inocula (10(4) and 10(8) cfu) were used throughout. GR69153 inhibited 90% of isolates of Escherichia coli, Klebsiella pneumonia and Proteus mirabilis at less than or equal to 0.25 mg/l and 90% of isolates of Pseudomonas aeruginosa at less than or equal to 1 mg/l. Citrobacter freundii (MIC90 16 mg/l), Morganella morganii (MIC90 128 mg/l) and Enterobacter spp. (MIC90 greater than 128 mg/l) were considerably more resistant to GR69153. GR69153 was four-fold more active than ceftazidime against methicillin-sensitive Staphylococcus aureus but was inactive against methicillin-resistant Staphylococcus aureus, Enterococcus faecalis and Bacteroides fragilis group.

Bacteria↗
PubMed1991

Epithelioid angiosarcoma of deep soft tissue: a distinctive tumor readily mistaken for an epithelial neoplasm.

We report eight cases of epithelioid angiosarcoma arising in deep, usually intramuscular soft tissue. All the patients were men (mean age, 58). All the lesions arose in a limb or limb girdle. Cardinal morphologic features were the diffuse, sheetlike growth pattern, with only focally apparent vascular differentiation, and epithelioid tumor cells with a degree of intracytoplasmic vacuolation/lumen formation. Immunohistochemically, all eight cases coexpressed keratin as well as endothelial markers. In three cases, endothelial differentiation was confirmed ultrastructurally. Clinically, deep-seated epithelioid angiosarcomas are high-grade neoplasms that rapidly develop metastases. These findings expand the range of recognized epithelioid endothelial tumors and provide further evidence of keratin expression by such lesions. The presence of intracytoplasmic lumina/vacuoles (sometimes containing red blood cells) combined with the characteristic reticulin pattern and striking positivity for Factor VIII-RAg provide the clearest means of distinction from an epithelial metastasis.

Adult↗
PubMed1991

Serum prostatic acid phosphatase activity and prostate specific antigen when the prostate gland is enlarged.

Serum prostatic acid phosphatase activity and prostate specific antigen levels were measured in the serum of 113 patients undergoing transurethral resection of an enlarged prostate gland, and the results compared with the histological diagnosis. Prostate-specific antigen was found to be the more sensitive indicator of malignancy, but prostatic acid phosphatase was more specific.

Acid Phosphatase↗
PubMed1990

Severe electrical injury from a graphite fishing rod.

High tension electrical injuries have a high morbidity and mortality. Carbon fibre and graphite used in the manufacture of fishing rods gives them superconductor qualities. We report a case which teaches an important lesson not only in the management of such severe injuries, but also in their prevention.

Adolescent↗
PubMed1989

Anastomotic aneurysms of the femoral artery: aetiology and treatment.

The aetiology and treatment of 35 femoral false anastomotic aneurysms in 29 patients presenting over the 4-year period 1984-88 were reviewed retrospectively. The mean interval between primary anastomosis and false aneurysm repair was 6 years (range from 2 weeks to 16 years). Twenty-two (63 per cent) false aneurysms had occurred after previous aortobifemoral bypass grafting for occlusive aortoiliac disease. Seven (20 per cent) presented as acute surgical emergencies. Review of the records of the initial operations revealed that superficial wound infections with positive bacteriological cultures had been present in eight cases (23 per cent) and a further two (6 per cent) had lymph fistulae. Thirty-two false aneurysms were repaired, by simple reanastomosis in 14 cases, interposition grafting in 17 cases and in one case by complete revision to an aortobifemoral bypass graft. The risk of a further operative repair was less (P less than 0.05) following interposition grafting, than after simple revision. False aneurysm repairs, when compared with primary reconstructions done during the same period, were associated with more superficial wound infections (37 versus 10 per cent) and more explorations for haemorrhage within 30 days (19 versus 7 per cent).

Anastomosis, Surgical↗
PubMed1989

Comparative in vitro activity of lomefloxacin, a new difluoroquinolone.

The in vitro activity of lomefloxacin, a new difluoroquinolone, was compared with that of norfloxacin, ciprofloxacin, gentamicin and ceftazidime against a total of 577 recent clinical isolates. MICs were determined by a standard agar dilution procedure, and two inocula (10(4) and 10(6) CFU) were used throughout. Lomefloxacin inhibited most species of the Enterobacteriaceae, Staphylococcus aureus (including methicillin-resistant strains) and Haemophilus influenzae at less than or equal to 1 mg/l. Pseudomonas aeruginosa (MIC 90, 4 mg/l) was somewhat more resistant, and Pseudomonas maltophilia (MIC 90, 16 mg/l) and the Bacteroides fragilis group (MIC 90, 32 mg/l) were considerably more resistant. Overall, lomefloxacin was as active as norfloxacin, but was two- to eightfold less active than ciprofloxacin against most species tested.

Anti-Infective Agents↗
PubMed1989

In-vitro activity of meropenem against clinical isolates obtained in Canada.

The in-vitro activity of meropenem, a new parenteral carbapenem, was compared with that of imipenem, ceftazidime, cefotaxime, piperacillin, gentamicin and, where appropriate, other antibiotics against recent clinical isolates and characterized beta-lactamase producers. MICs were determined by a standard agar dilution procedure and two inocula (10(4) and 10(6) cfu) were used throughout. Meropenem inhibited 90% of isolates of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, indole-positive Proteus spp., Enterobacter spp., Serratia marcescens and Providencia stuartii at less than or equal to 0.25 mg/l and was four- to 16-fold more active than imipenem against these species. Against the enteric pathogens Salmonella typhi, Shigella sonnei, Yersinia enterocolitica and Campylobacter jejuni, meropenem was four- to eight-fold more active than imipenem, inhibiting all isolates at less than or equal to 0.03 mg/l. Meropenem was also more active than imipenem against Haemophilus influenzae (MIC90 0.06 mg/l) but had similar activity against the Bacteroides fragilis group (MIC90 0.25 mg/l), against Pseudomonas aeruginosa (MIC90 2 mg/l) and against streptococci. Imipenem was four-fold more active than meropenem against Acinetobacter spp. and two- to eight-fold more active against all species of staphylococci tested. Both meropenem and imipenem were inactive against Ps. (Xanthomonas) maltophilia.

Bacteria↗
PubMed1988

Spark-generating properties of electrode gels used during defibrillation. A potential fire hazard.

After a defibrillation attempt started a fire in an oxygen-enriched intensive care unit environment, seven popular electrode gels were tested for spark-generating properties by repeated 360-J electrical discharges into a 50-omega test load. Gels with low initial impedance (7 +/- 1 omega) allowed a high current flow (51 +/- 1 A), maintained a cool temperature (27 degrees C to 33 degrees C), and did not spark. Gels with high initial impedance (125 +/- 14 omega) allowed less current (26 +/- 2 A), heated to 52 degrees C +/- 2 degrees C, liquified, and generated an electrical spark after the fourth or fifth discharge. Federal standards should be developed to identify and label electrode gels that can be used safely for high-current applications such as defibrillation.

Electric Conductivity↗
PubMed1988

Human skull vibratory patterns in audiometric and supersonic ranges.

The attenuation of bone-conducted stimuli across the human skull was determined in audiometric, ultrasonic, and supersonic frequency ranges (250 to 64,000 Hz). An increase in attenuation with an increase in frequency, as well as significant resonance effects, was observed. For the audiometric frequency range, bone conduction stimulation of one side of the head results in almost equal stimulation of the other side. In the ultrasonic and supersonic ranges, the contralateral side is progressively isolated.

Audiometry↗
PubMed1987

In vitro activity of the new 4-quinolone compound Ro 23-6240.

The in vitro activity of the new 4-quinolone Ro 23-6240 was compared with that of pefloxacin, ciprofloxacin, norfloxacin, nalidixic acid and gentamicin against a total of 397 recent clinical isolates. An agar dilution procedure was used to determine MICs and two inocula (10(4) and 10(6) CFU) were used throughout. Ro 23-6240 inhibited most species of the Enterobacteriaceae, Haemophilus influenzae and Staphylococcus aureus (including methicillin-resistant strains) at less than or equal to 1 mg/l. Pseudomonas aeruginosa was somewhat more resistant (MIC 90 4 mg/l) and the Bacteroides fragilis group were considerably more resistant (MIC 90 32 mg/l). Overall Ro 23-6240 was as active as pefloxacin but was two- to eight-fold less active than ciprofloxacin against most species tested.

Anti-Bacterial Agents↗
PubMed1987

Research on mental handicap, 1957-1987: a selective review.

Some of the major advances in research over the last 30 years are outlined. While primarily offering an account of the behavioural sciences as applied to this field, some attention is devoted to major biomedical findings which have revolutionized our potential for preventive action. Mental handicap research has been a powerful influence in changing practices.

Behavior Therapy↗