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Biomedical subjects

A D Holmes

Publications and source records attributed to A D Holmes.

18 recordsLinked to original sources

Comparison of the API Candida system with the AUXACOLOR system for identification of common yeast pathogens.

Two commercial systems for the identification of yeasts were evaluated by using 159 clinical isolates that had also been identified by conventional biochemical and morphological methods. The API Candida system correctly identified 146 isolates (91.8%), and the AUXACOLOR system correctly identified 145 isolates (91.2%). However, of the 146 isolates identified by the API Candida system, 23 required supplemental biochemical tests or morphological assessment to obtain the correct identification. The AUXACOLOR system gave no identification in 13 cases (8.2%), while the API Candida system gave an unreadable profile in only one case. Incorrect identifications were more common with the API Candida system (12 isolates; 7.5%) than with the AUXACOLOR system (1 isolate; 0.6%).

Automation

In-vitro susceptibility of Cryptococcus neoformans isolates to fluconazole and itraconazole.

The in-vitro susceptibilities of 143 isolates of Cryptococcus neoformans, collected from British patients between 1994 and 1996, to fluconazole and itraconazole were compared with those of 36 isolates collected between 1971 and 1985, 41 isolates collected between 1986 and 1989, and 43 Ugandan isolates collected in 1996. Testing was done with a broth microdilution method in YNB medium supplemented with glucose, incubation at 30 degrees C for 72 h, and an endpoint of 50% inhibition. The results showed that the MIC ranges, MIC50s and MIC90s of fluconazole and itraconazole for C. neoformans isolates from the UK have remained unchanged despite the recent widespread use of triazoles for long-term maintenance of patients with AIDS-associated cryptococcal meningitis. The MIC ranges, MIC50s and MIC90s of the 43 isolates from untreated Ugandan patients with AIDS were similar to those of the British isolates. Examination of our records for 1994-96 revealed six cases in which a four-fold or greater rise in the MIC of fluconazole was associated with relapsed cryptococcal meningitis.

Acquired Immunodeficiency Syndrome

Comparative evaluation of FUNGITEST and broth microdilution methods for antifungal drug susceptibility testing of Candida species and Cryptococcus neoformans.

The FUNGITEST method (Sanofi Diagnostics Pasteur, Paris, France) is a microplate-based procedure for the breakpoint testing of six antifungal agents (amphotericin B, flucytosine, fluconazole, itraconazole, ketoconazole, and miconazole). We compared the FUNGITEST method with a broth microdilution test, performed according to National Committee for Clinical Laboratory Standards document M27-A guidelines, for determining the in vitro susceptibilities of 180 isolates of Candida spp. (50 C. albicans, 50 C. glabrata, 10 C. kefyr, 20 C. krusei, 10 C. lusitaniae, 20 C. parapsilosis, and 20 C. tropicalis isolates) and 20 isolates of Cryptococcus neoformans. Overall, there was 100% agreement between the methods for amphotericin B, 95% agreement for flucytosine, 84% agreement for miconazole, 83% agreement for itraconazole, 77% agreement for ketoconazole, and 76% agreement for fluconazole. The overall agreement between the methods exceeded 80% for all species tested with the exception of C. glabrata (71% agreement). The poorest agreement between the results for individual agents was seen with C. glabrata (38% for fluconazole, 44% for ketoconazole, and 56% for itraconazole) and C. tropicalis (50% for miconazole). The FUNGITEST method misclassified as susceptible 2 of 12 (16.6%) fluconazole-resistant isolates, 2 of 10 (20%) itraconazole-resistant isolates, and 4 of 8 (50%) ketoconazole-resistant isolates of several Candida spp. Further development of the FUNGITEST procedure will be required before it can be recommended as an alternative method for the susceptibility testing of Candida spp. or C. neoformans.

Antifungal Agents

The surgical management of osseous cranial base tumours in children.

BACKGROUND: Osseous cranial base tumours in children present as a diverse collection of both benign and malignant pathologies. Concerns raised by the difficulty in accurate diagnosis and local recurrence of benign lesions and by the long-term sequelae of radiotherapy for malignant cranial tumours (marked local growth disturbances, pituitary dysfunction, visual disturbances, late new tumour induction) prompted an evaluation of surgical resection of cranial base tumours in children, with specific regard to safety, efficacy and aesthetic result. METHODS: A retrospective review was performed of 10 consecutive children presenting with tumours either arising from or eroding into bone of the cranial base who were managed by surgical resection in a 10-year period from 1986 to 1996. The patients demonstrated a great variation in both presentation and pathology. All underwent surgical resection of tumour with reconstruction where indicated. RESULTS: There were no postoperative complications or mortality. All patients remained clinically free of disease at follow-up, which ranged from 17 months to 9 years (mean 6 years and 4 months). CONCLUSION: The aggressive surgical resection and craniofacial reconstruction of cranial base tumours in the paediatric population offers a safe and efficacious mode of treatment that obviates problems of diagnosis and local recurrence for benign lesions and of the long-term sequelae of radiotherapy for malignant lesions.

Adolescent

Analysis of load-relaxation in compressed segments of lumbar spine.

Load-relaxation was measured in 12 segments of human cadaveric lumbar spine. Each segment consisted of an intact intervertebral disc attached to half of its adjacent vertebrae with the posterior elements removed. Six specimens were each compressed at six different strains (corresponding to initial loads of 0.5-2.5 kN) and, for each strain, the load-relaxation was measured for a period of 20 min at room temperature. These load-relaxation curves were used to plot three isochrones for each specimen. All isochrones were linear (r values in the range 0.95-0.99). This result indicated that a linear model could be used to represent load-relaxation. Four specimens were tested at a single strain (corresponding to an initial load of about 2 kN) at 37 degrees C for a period of 4-6 h. Load was plotted against the logarithm of time. The resulting plots did not show any peaks, indicating that relaxation effects did not predominate at any particular times during load-relaxation. However, it was possible to model the load-relaxation as a simple linear system which can be represented as two Maxwell elements in parallel. These elements were characterized by relaxation times of 16 +/- 8 min and 4.6 +/- 0.8 h. Fourier transformation of the load-relaxation curves showed a gradual increase in the storage modulus and a gradual decrease in the loss modulus for frequencies of about 1 Hz and above. At these frequencies, the spine cannot function as a shock-absorber in pure compression.

Aged

Osseointegration in sinus-forming bone.

Osseointegration, using bone-anchored titanium fixtures, is a well-established technique for both intraoral and craniofacial prosthetic rehabilitation. The use of this technique in children can be complicated by craniofacial growth and sinus development. This study evaluates the effects of sinus formation and growth on the fate of osseointegrated titanium fixtures in the growing porcine model. At 3 weeks of age, six Landrace White cross male pigs had a 3.75 x 3.0 mm titanium fixture (Noblepharma) inserted into their right frontal bone where the right frontal sinus would subsequently develop. Preoperative CT scans with three-dimensional reconstructions were used to determine the insertion site. To follow the effects of growth and sinus formation, CT scans with three-dimensional reconstructions and cephalometric radiographs were taken at 1, 3, 6, and 9 weeks postoperatively and at sacrifice. The pigs were sacrificed serially, and direct osteometric measurements were taken to determine skull symmetry. All skulls were sectioned, and osseointegration was determined clinically, radiologically, and histologically with light and scanning electron microscopy. Five of the six fixtures osseointegrated. There were no apparent growth disturbances due to the fixtures. As growth progressed, the osseointegrated fixtures submerged into the frontal bone in a posteroinferior direction to become completely intraosseous 14 weeks after insertion. As the frontal sinus pneumatized, the fixtures remained osseointegrated, but progressive amounts of the fixtures became exposed in the sinus. From this study it would appear that osseointegrated titanium fixtures do not have any effect on calvarial growth and gradually submerge into the growing bone. As sinus development ensues, the fixtures remain integrated but become partially exposed within the sinus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

End-plate displacement during compression of lumbar vertebra-disc-vertebra segments and the mechanism of failure.

Seventeen specimens of lumbar discs, attached to the caudal and cranial halves of the adjacent vertebral bodies, were subjected to a maximum compressive load of 5.5 kN in six stages. The time between each stage was about 15 seconds. At each stage of compression, a radiograph of the specimen was recorded, and the bulging of the end-plate into the caudal vertebra was measured using a displacement transducer. After compression, the ash content of a bone sample and the water content of a sample of the nucleus of the disc were measured for each specimen. Sections through the specimens were examined by light microscopic study. Eight specimens did not fail, although end-plate displacement occurred during compression. The remaining nine specimens experienced fracture or permanent deformation of the end-plate. Specimens that failed had significantly lower rigidity of the end-plate and underlying trabecular bone; this rigidity was correlated with bone ash content.

Adult

Experimental calvarial growth disturbance by micro-plate and screw fixation.

A study was designed to help ascertain the effects of rigid internal fixation in the growing skull. Five piglets underwent plating of the left coronal suture at 3 weeks of age. At the time of surgery metal markers were placed to follow bone growth. Cephalometric radiographs, direct osteometry at sacrifice, gross pathological examination and specimen radiography revealed a localized disturbance of growth. There was a restriction of sutural displacement and appositional bone growth at the site of the plate. Local restriction of sutural growth was almost complete during the experimental period. There was an alteration to a 'mature' suture morphology, without synostosis, of the suture on the plated side not seen on the control side. A plagiocephalic pig was not produced nor was there an orbital deformity. A large local contour deformity developed and by the end of the experimental period the plate had become completely incorporated in bone. These effects were statistically significant as well as clinically significant. The clinical use of this type of fixation in reconstructive surgery of the infant craniofacial skeleton is questioned in light of the result.

Animals

The use of tissue expansion for immediate breast reconstruction after mastectomy.

A series of 139 patients who had a total mastectomy underwent breast reconstruction using the method of tissue expansion. In 127 patients a tissue expander was inserted at the time of mastectomy and in 12 patients this was done as a delayed procedure. The reconstruction was successfully completed in 87% of cases and the patient acceptance of this method of reconstruction has been high. We believe that tissue expansion should be offered to all women having immediate reconstruction after total mastectomy and that it also has a significant role in delayed breast reconstruction after mastectomy.

Adult

Cephalometric and anthropomorphic observations of Binder's syndrome: a study of 19 patients.

Binder's syndrome (maxillonasal dysplasia) is a disorder characterized by nasomaxillary hypoplasia. To ascertain the extent of underdevelopment of the midfacial skeleton and soft tissues, 19 of 29 patients with Binder's syndrome were retrospectively evaluated, both with cephalometry and anthropometry. Ten females and nine males were placed collectively into three age groups: 6 years, 10 years, and 16 to 17 years. Cephalometric measurements disclosed a short anterior cranial base (S-N), a normal length of the vertical maxilla (SE-PNS), a decreased horizontal maxilla (PNS-A, Co-A), a recessed orbitale (SNO), and a high-normal mandibular length (Co-Gn). Anthropometry revealed a large nasofrontal angle, acute nasal inclination and nasolabial angle, decreased nasal prominence (Sn-Prn), a decreased columellar length (C-Sn), and a normal vertical nose (N-Sn) and upper lip (Sn-Sto) length.

Adolescent

Arteriovenous malformation in the mandible of a young child.

Arteriovenous malformations rarely occur in the jaws, particularly in the very young child. The vascular and haemodynamic nature of the lesion is important in determining treatment and providing for a favourable prognosis, particularly in the high-pressure malformations. If the lesion is unstable and active, that is, there is enlargement, pain, bleeding or ulceration, successful treatment will depend upon early pre-operative embolization and surgical extirpation of the lesion. A 4-year old boy is presented who had a moderately active arteriovenous malformation of the left mandibular body. Angiography disclosed an arteriovenous malformation supplied by the inferior alveolar, lingual and facial arteries on the left side with no contralateral contribution. Pre-operative embolization via selective catheterization of the major arterial feeder was performed. Five days later, the involved portion of the mandible was resected and a corticocancellous bone-graft was placed. The 6-month follow-up disclosed no evidence of new arterial feeders or contralateral involvement.

Arteriovenous Malformations

Maxillonasal dysplasia (Binder's syndrome): a critical review and case study.

Binder's syndrome (maxillonasal dysplasia) is a disorder of unknown etiology characterized by nasomaxillary hypoplasia and a 40-50% association of an underdeveloped frontal sinus and cervicospinal abnormalities. The midfacial retrusion is similar to that in chondrodysplasia punctata, resulting in confusion regarding diagnosis. This paper outlines the distinguishing features of Binder's syndrome, the treatment considerations, and presents 24 patients seen and treated. The facial and skeletal characteristics and developmental findings are emphasized to affirm the diagnosis of Binder's syndrome. A familial finding of Binder's features in five patients raises the possibility of a genetic mechanism, a previously undisclosed finding.

Abnormalities, Multiple

Effects of porcelain/alloy interfacial diffusion zones on thermo-mechanical strain.

Chemical bonding between dental porcelains and alloys results from interdiffusion of porcelain and metal ions. An interfacial diffusion zone is created which, most likely, has properties different from those of bulk materials. The changed interface might affect experimental measurements of thermo-mechanical strain. To determine the magnitude and conditions under which this would occur, the interface was modeled as the intermediate layer of a three-layered porcelain-veneered split-metal ring. Layer thicknesses and coefficients of thermal expansion were varied, and the effects on gap change after cooling through 500 degrees C were calculated. Results are presented in a series of 14 Figs., ten curves each, which depict not only interfacial effects, but are extended for use in interpretation of the effects of properties of opaques and glazes as well. Under most conditions, the interface will not affect experimental measurements; some special exceptions are noted.

Chemical Phenomena

Use of the temporalis muscule flap in blanking out orbits.

We report the use of the temporalis muscle as a transposition flap to obliterate the orbit in 5 patients. In 4 of the cases we split the muscle coronally and passed the anterior part through a window in the lateral orbital wall. In two of these patients, skin grafts were put on both sides of the temporalis muscle-fascia flap, to restore nasal lining and to cover the facial surface simultaneously. In the remaining patients, the muscle was split sagittally to provide a large surface for coverage. The temporalis muscle flap is a versatile one for filling orbits after exenteration.

Adult