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Biomedical subjects

D H Thompson

Publications and source records attributed to D H Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Triggered release of hydrophilic agents from plasmalogen liposomes using visible light or acid.

Triggered release from liposomes composed of semi-synthetic 1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphocholine (plasmalogen) lipids has been demonstrated using either aerobic visible illumination or low pH to induce leakage. The photodynamic release system consists of three functional components: (1) small (less than 1000 A) unilamellar plasmalogen vesicles (SUVs) containing encapsulated glucose, (2) oxygen and (3) zinc phthalocyanine (ZnPc) incorporated within the hydrophobic region of the SUV membrane. Irradiation (lambda greater than 640 nm) at 37 degrees C of air-saturated 1-alk-1'-enyl-2-palmitoyl-sn-glycero-3-phosphocholine (PlasPPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (8:1, mol/mol) liposomes at physiologically relevant temperatures results in glucose release rates that are twice those of the corresponding dark control. Photolysis of argon-saturated PlasPPC/DPPC liposomes or of identical vesicles lacking either ZnPc or the plasmalogen vinyl ether bond exhibit glucose release curves which are indistinguishable from the dark control. Irradiation under identical conditions, but in the presence of 100 mM sodium azide, also results in no increased rate of glucose release above that of the dark control. TLC analysis indicates that oxidized lipid species are produced only in air-saturated, irradiated plasmalogen liposomes. The acid lability of the plasmalogen vinyl ether linkage has also been used to trigger release of entrapped calcein. At pH 4.2, the release rate at 37 degrees C is increased 4-fold over rates observed at pH 8. TLC analysis indicates formation of a lysoplasmalogen product. Taken together, these results indicate that both photodynamic and acid triggering can be used to increase plasmalogen liposome permeability and suggest that these liposomes are potentially useful for drug delivery applications.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Innovative materials processing strategies: a biomimetic approach.

Many organisms construct structural ceramic (biomineral) composites from seemingly mundane materials; cell-mediated processes control both the nucleation and growth of mineral and the development of composite microarchitecture. Living systems fabricate biocomposites by: (i) confining biomineralization within specific subunit compartments; (ii) producing a specific mineral with defined crystal size and orientation; and (iii) packaging many incremental units together in a moving front process to form fully densified, macroscopic structures. By adapting biological principles, materials scientists are attempting to produce novel materials. To date, neither the elegance of the biomineral assembly mechanisms nor the intricate composite microarchitectures have been duplicated by nonbiological processing. However, substantial progress has been made in the understanding of how biomineralization occurs, and the first steps are now being taken to exploit the basic principles involved.

Animals↗
PubMed1992

Aerobic and anaerobic microbiology of external otitis.

Microbiological and clinical data from 46 patients with external otitis were retrospectively evaluated. Specimens were processed for isolation of aerobic and anaerobic bacteria. A total of 42 aerobic bacteria, 22 anaerobic bacteria, and 3 Candida albicans organisms were recovered. Aerobic bacteria only were isolated from 31 patients (67%), anaerobic bacteria only were isolated from 8 (17%), and mixed aerobic and anaerobic bacteria were isolated from 4 (9%). C. albicans alone was recovered from two patients (4%), and the organism was mixed with aerobic bacteria in one case (2%). The most common isolates were Pseudomonas aeruginosa (19 instances), Peptostreptococcus species (11), Staphylococcus aureus (7), and Bacteroides species (5). One isolate was recovered from 30 patients (65%), 2 isolates were recovered from 11 (24%), and 3 isolates were recovered from 5 (11%). beta-Lactamase activity was detected in 32 isolates recovered from 27 specimens (59%). These data illustrate the polymicrobial nature of external otitis in one-third of the patients and the role of anaerobic bacteria in one-quarter of them. Further prospective studies are warranted for evaluating the role of anaerobic bacteria in this infection and the therapeutic implications of these findings.

Adolescent↗
PubMed1992

Spontaneous cerebrospinal fluid rhinorrhea.

The diagnosis of CSF rhinorrhea requires the performance of a thorough history and physical examination. Often no objective findings can be found and further evaluation will be required. In our experience, metrizamide CT cisternography yields the most information for localization of the fistula. When indicated, patients can be protected against meningitis by using prophylactic antibiotics for 4-6 weeks to allow a fistula to close spontaneously. If the fistula fails to close during this time, surgical closure with dural or muscle graft with or without waxing of the bone is the treatment of choice.

Cerebrospinal Fluid Rhinorrhea↗
PubMed1991

Smokers of the future.

Teenagers continue to be initiated into smoking, especially young women. A predictor of smoking is the existence of stressors in their life. The major components of smoking motivation have been found to be similar in young smokers to those found in older smokers, except for the appearance of a group who are resisting the pressures against smoking. There is no evidence that the smokers of the future will be more extreme personality types than the smokers of 10 or more years ago. Changes in demographic characteristics of smokers in the United Kingdom and the United States in favour of relatively more women and more smokers from the poorer socio-economic groups requires investigation into whether this is attributable to different coping requirements in these groups.

Adolescent↗
PubMed1991

Aerobic and anaerobic microbiology of acute suppurative parotitis.

Aspirates of pus from acute suppurative parotitis were studied for aerobic and anaerobic bacteria. Bacterial growth was present in 23 specimens. A total of 36 bacterial isolates (20 anaerobic and 16 aerobic and facultative) were recovered, accounting for 1.6 isolates per specimen (0.9 anaerobic and 0.7 aerobic and facultative). Anaerobic bacteria only were present in 10 (43%) patients, aerobic and facultatives in 10 (43%), and mixed aerobic and anaerobic flora in 3 (13%). Single bacterial isolates were recovered in 9 infections, 6 of which were Staphylococcus aureus and 3 were anaerobic bacteria. The predominant bacterial isolates were S. aureus (8 isolates), Bacteroides sp. (6 isolates, including 4 Bacteroides melaninogenicus group), and Peptostreptococcus sp. (5). beta-Lactamase-producing organisms were recovered from 11 (73%) of the 15 specimens tested. This study highlights the polymicrobial nature and importance of anaerobic bacteria in acute suppurative parotitis.

Acute Disease↗
PubMed1991

Aerobic and anaerobic microbiology of peritonsillar abscess.

Thirty-four aspirates of pus from peritonsillar abscesses that were studied for aerobic and anaerobic bacteria showed bacterial growth. A total 107 bacterial isolates (58 anaerobic and 49 aerobic and facultative) were recovered, accounting for 3.1 isolates per specimen (1.7 anaerobic and 1.4 aerobic and facultatives). Anaerobic bacteria only were present in 6 (18%) patients, aerobic and facultatives in 2 (6%), and mixed aerobic and anaerobic flora in 26 (76%). Single bacterial isolates were recovered in 4 infections, 2 of which were Streptococcus pyogenes and 2 were anaerobic bacteria. The predominant bacterial isolates were Staphylococcus aureus (6 isolates), Bacteroides sp (21 isolates, including 15 Bacteroides melaninogenicus group), and Peptostreptococcus sp (16) and S. pyogenes (10). beta-Lactamase-producing organisms were recovered from 13 (52%) of 25 specimens tested. This retrospective study highlights the polymicrobial nature and importance of anaerobic bacteria in peritonsillar abscess.

Adolescent↗
PubMed1991

Juvenile aggressive fibromatosis: report of three cases and review of the literature.

AF is a non-encapsulated, non-metastasizing fibrous tumor that has a tendency for local recurrence in up to 70% of cases. We suspect possible genetic disposition. Microscopically, AF is a poorly circumscribed fibrous tumor that infiltrates surrounding tissues. It presents as a painless, rapidly growing mass with a predilection for bone destruction. Treatment consists of a carefully planned en bloc resection after biopsy and accurate radiologic evaluation of the extent of the tumor. Radiation therapy and chemotherapy can be used as adjuvant therapy in selected patients. Three patients with AF of the head and neck are described, of which two were found to have congenital disorders of mesodermal development.

Adolescent↗
PubMed1990

Separation of the enantiomeric intermediates of some platelet-activating factor analogues on a naphthylalanine-type Pirkle column.

A chiral high-performance liquid-chromatographic separation method was developed for the analysis of some glycerol-based, ether-linked platelet-activating factor precursors. Using a D-naphthylalanine-type Pirkle-column and tetrahydrofuran-hexane eluents, the retention-structure relationships were determined for a large number of glycerol ether derivatives. The derivatives leading to the highest chiral selectivity factors in the analytical separations were surveyed for their applicability in large-scale isolation of chiral synthetic intermediates.

Alanine↗
PubMed1985

Computerized axial tomography versus complex motion as a predictor of surgical findings in middle ear and mastoid cholesteatoma.

In order to evaluate the efficacy of polytomography and computerized tomography in the prediction of surgical findings in cases of suspected cholesteatoma of the middle ear and mastoid, we evaluated preoperatively 52 ears by both radiographic methods. We utilized a check list of 14 radiological signs or surgical findings to generate measures of sensitivity and specificity. The strengths of each radiographic method are outlined and the considerable weaknesses in predictive value are discussed.

Cholesteatoma↗
PubMed1982

Granulocytic sarcoma (chloroma) initially seen as acute mastoiditis.

Granulocytic sarcoma (chloroma) is a localized tumefaction of immature granulocytes that is typically seen in association with myelogenous leukemia. The primitive cell population seen in biopsy material may be misinterpreted as histiocytic lymphoma or other sarcoma unless additional studies are performed. We saw a 36-year-old woman with promyelocytic leukemia in remission who had the signs and symptoms of an acute coalescent mastoiditis. Histologic examination of the surgical specimen, however, demonstrated a granulocytic sarcoma. Our case exemplifies some of the difficulties that may be encountered in the diagnosis of granulocytic sarcoma and illustrates the point that symptoms of an inflammatory process in a patient with a diagnosis of leukemia must be regarded with a degree of suspicion.

Adult↗
PubMed1982

Primary small cell (oat cell) carcinoma of the larynx associated with an IgD multiple myeloma.

Primary small cell (oat cell) carcinoma of the larynx is a rare condition. We report a case of primary oat cell carcinoma of the subglottic larynx associated with a synchronous IgD multiple myeloma (an unreported association). An increased incidence of carcinoma associated with plasma cell disorders has been reported, and the theories of this association are discussed. In a review of the reported cases, the most successful management of oat cell carcinoma of the larynx appears to incorporate a combination of radiotherapy and chemotherapy. Our case was treated with a combination of protocols used for oat cell carcinoma of the larynx and multiple myeloma. At 24 months after diagnosis, the patient is free of oat cell carcinoma, and the multiple myeloma is under control.

Carcinoma, Small Cell↗
PubMed1979

An open technique of pleural biopsy in the diagnosis of tuberculous effusions.

To assess an open technique of pleural biopsy as an aid to diagnosis in pleural disease 107 African patients with radiological evidence of pleural effusion underwent biopsy. In 87 there was radiological evidence of an effusion but not of underlying lung disease; 73 patients (84%) in this group were ultimately diagnosed as suffering from tuberculosis and of these 56 (77%) had a positive pleural biopsy. There was a heavy male predominance of tuberculous infection (male:female ratio approximately 5:1) and half of the patients were aged 21 to 30 years. In the 20 patients with radiological changes in the lung a diagnosis was established by biopsy in 13 cases. Four of these were tuberculous and a further two cases of tuberculosis were established on clinical grounds.

Biopsy↗