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Biomedical subjects

D Adams

Publications and source records attributed to D Adams.

At least 37 records · Page 2Linked to original sources
PubMed1991

Dentine hypersensitivity--effects of some proprietary mouthwashes on the dentine smear layer: a SEM study.

Exposed dentine may be sensitive to stimuli depending on the patency of the dentinal tubules. Most abrasive elements tend to produce a smear layer which obturates the dentinal tubules. This layer is easily removed by a number of erosive agents, particularly dietary acids. Mouthwashes are increasingly used and largely investigated for possible benefits to dental health. Rarely do studies assess potential detrimental activity. The aim of the present study was to examine effects of mouthwashes on dentine. Smear layers artificially produced on dentine sections were exposed, for time periods ranging from 3 to 300 min, to mouthrinses alone, or with subsequent brushing for 2 min using water or a fluoride toothpaste. Assessments were made by scanning electron microscopy. Of the nine rinses tested, six produced no consistently observable changes compared to water treated controls at any time period with or without brushing. A hexetidine rinse and a fluoride/antiseptic rinse both exposed tubules after exposure times of 2 h and longer, an effect enhanced by post-treatment brushing. A phenolic antiseptic rinse consistently removed the smear layer from specimens, an effect enhanced by brushing such that after 10 min exposure and 2 min brushing many tubules were open at the surface. The results indicate that the use of some mouthrinses could predispose to excessive tooth substance loss and dentine hypersensitivity, particularly if used prior to toothbrushing. There is a need to determine whether the intermittent use of some mouthrinses produces cumulative effects on dentine.

Benzoates↗
PubMed1991

Parameter optimization and calibration of 19F magnetic resonance imaging at 1.5 Tesla.

Fluorine-19 magnetic resonance imaging is limited by the fact that acquisition times are long and that high concentrations must be used in order to obtain good signal to noise. A significant improvement in signal to noise ratio may be brought about by the addition of Gd-DTPA, a paramagnetic agent which shortens T1. Images of phantoms containing trifluoroacetic acid (TFA) doped with Gd-DTPA were obtained using a standard spin echo sequence in a 1.5 T field. Interpulse times (TR and TE) and Gd-DTPA concentrations were optimized to yield maximum signal to noise ratios. The use of fast-field-echo scans to image fluorine is also demonstrated. Signal averaging successive FFE scans yields good signal to noise and resolution and may find clinical applicability in imaging areas subject to motion.

Calibration↗
PubMed1991

The diagnostic utility of the antibody-coated bacteria test in intubated patients.

PURPOSE: Pilot study to determine if the presence of antibody-coated bacteria (ACB) in sputum specimens obtained from endotracheal tube suctioning would aid in the diagnosis of lower respiratory tract infection (LRTI). PATIENTS AND METHODS: All endotracheally intubated and mechanically ventilated patients for a two-month period were recruited for study. The diagnosis of LRTI was based on a clinical suspicion sufficient enough to start or change antibiotic therapy. Specimens were obtained by blind endotracheal tube suctioning. After processing, sputum smears were stained with fluorescein-labelled antibody to the Fc portion of IgG, IgM, and IgA. More than five fluorescein-labelled bacteria per oil immersion field were considered positive smears. RESULTS: Seventy-one specimens were obtained from 36 patients. Eighteen specimens were positive in 12 patients, all of whom had LRTI. No specimen was positive in patients not diagnosed as having LRTI. The ACB test was positive in 12 of 25 patients with LRTI. Patients with LRTI but negative ACB were more likely to have received prior antibiotic therapy (p less than 0.001). ACB was positive prior to the clinical diagnosis of LRTI in seven of nine patients (av 4.1 days, range 2-6 days) and converted to negative in three specimens obtained seven or more days after starting appropriate antibiotics, while in three specimens it remained positive three-six days post treatment initiation. CONCLUSIONS: The ACB test appears to be highly specific for the presence of LRTI in intubated patients. Sensitivity of the test may be adversely affected by prior antibiotic therapy. A positive ACB test may predict the subsequent development of LRTI. Further study is warranted.

Cross Infection↗
PubMed1990

Reassessment of external insulin infusion pumps.

Continuous subcutaneous insulin infusion (CSII) therapy using external infusion pumps provides an alternative to multiple daily injections (MDI) for insulin-dependent diabetics who require intensive insulin therapy. CSII allows for the delivery of regular insulin continuously at preset basal rates and at bolus doses, which can be varied in response to insulin needs of the patient. Intensive insulin therapy by CSII or MDI was administered to diabetics to improve control of their blood glucose levels and to assess its effects on the development of complications such as retinopathy and nephropathy. CSII appeared to be as effective as MDI in attaining near-normoglycemia and improving metabolic control in patients with insulin-dependent diabetes mellitus who required intensive insulin therapy. It was not clear, however, whether the improved control of the blood glucose levels resulted in the prevention or progression of the diabetic complications. The risks of having adverse effects, such as diabetic ketoacidosis or hypoglycemia, were higher with CSII as compared with MDI; both methods having higher risks of these complications in comparison to conventional insulin therapy. CSII may be beneficial for patients requiring intensive insulin therapy who may need greater lifestyle flexibility with regard to meal timing, work, and recreational scheduling.

Humans↗
PubMed1989

[Platelet antiaggregants in cerebral ischemic pathology].

Platelet aggregation inhibitors have been more extensively and better studied than all other treatments used in the prevention of cerebral ischaemia. It has been demonstrated that both aspirin (300 mg/day) and ticlopidine (500 mg/day) are effective in the secondary prevention of cerebral ischaemic accidents associated with atherosclerosis, with a 20 and 30 p. 100 respectively reduction of risk. At the moment, there is no evidence that these compounds are effective in the primary prevention or treatment of cerebral infarction in the acute phase. The best way of preventing thromboembolic stroke of cardiac origin is to treat the responsible heart disease and prescribe anticoagulants. However, several studies are in progress to evaluate the effectiveness of aspirin in the primary and secondary prevention of cerebral thromboembolism due to non-valvular atrial fibrillation.

Arteriosclerosis↗
PubMed1989

Permeability studies on protective gloves used in dental practice.

The recent guidelines issued by the DHSS and the BDS recommend that to prevent cross-infection gloves should be worn by dentists and their assistants whilst treating all patients. Little information is available on the permeability of the various types of glove available; this pilot study was therefore conducted, to test five commonly used brands of gloves for permeability to air, electrolytes, dye and bacteria. Tests were carried out before and after using the gloves for varying periods. From these studies it was found that only one brand of glove passed all the tests before wearing. After wearing the gloves for up to 3 hours, between 20% and 50% of the gloves, depending on type, allowed bacteria to pass across the glove. The visual test was less critical than the ion passage and bacterial tests, in that some gloves without obvious perforations allowed ions and bacteria to pass through.

Coloring Agents↗
PubMed1989

Dentine hypersensitivity. The development and evaluation of a replica technique to study sensitive and non-sensitive cervical dentine.

Studies of extracted teeth have shown that teeth exhibiting dentine hypersensitivity have larger numbers of widened dentinal tubules at the dentine surface compared to non-sensitive teeth. Many compounds used in the treatment of dentine hypersensitivity are thought to achieve therapeutic benefit by tubule occlusion, but there has been almost no attempt to prove such action in vivo. These studies systematically determined whether the dentine surface could be evaluated non-invasively, by a scanning electron microscopic replica technique. Employing a silicone rubber impression method in vitro, the surface detail of dentine could be accurately replicated, with surface scratches, tubules and intratubular structures on the original reproduced on the replica. With attention to method, similar accuracy was achieved in vivo, particularly when tubules were open on the dentine surfaces of the original. The method would appear useful for the study of the dentine surface in cases of dentine hypersensitivity and could prove the first objective method of studying the effects of treatment agents used in the treatment of this painful condition.

Acid Etching, Dental↗
PubMed1989

Acute myeloradiculitis due to cytomegalovirus as the initial manifestation of AIDS.

A 26 year old male intravenous drug abuser presented with rapidly progressive paraplegia and total incontinence. CSF examination showed elevated protein level and pleocytosis. HIV testing was positive. Anti CMV titres were mildly elevated in serum and CSF. Death occurred 26 days after the onset of neurological signs. Necrotic and inflammatory lesions with numerous inclusion bodies characteristic of CMV were found in the roots of the cauda equina, conus terminalis and lumbar segments of the spinal cord. CMV subependymal encephalitis and HIV encephalitis were also present.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Xenobiotic metabolism in motor neuron disease.

Debrisoquine, carbocysteine, and paracetamol were selected as safe drugs to investigate the ability of the liver's microsomal system to oxidise carbon, oxidise sulphur, and conjugate sulphate in patients with motor neuron disease (MND), other hospital patients, and healthy volunteers. Subjects with poor sulphur-oxidising and sulphur-conjugating activities were heavily over-represented in the MND group.

Acetaminophen↗
PubMed1988

The metabolism of aromatic ring fission products by Bacillus stearothermophilus strain IC3.

Bacillus stearothermophilus IC3 degraded the meta cleavage product of catechol, 2-hydroxymuconic semialdehyde, to pyruvate and acetaldehyde via the 4-oxalocrotonate pathway. The pathway was identical to those previously delineated in several mesophilic organisms. However, all the enzymes showed activity at 55 degrees C and other properties (substrate specificities and effects of metal ions) also differed from those displayed by the mesophilic enzymes. All enzymes of this meta cleavage pathway, except the 2-hydroxy-6-oxohepta-2,4-dienoate hydrolase and 4-hydroxy-2-oxovalerate aldolase activities, were induced by growth on phenol.

Catechols↗
PubMed1988

Treatment of massive acute pulmonary embolism. The use of low doses of intrapulmonary arterial streptokinase combined with full doses of systemic heparin.

The efficacy of low-dose, locally administered streptokinase (SK) combined with full therapeutic systemic doses of heparin was investigated. Seven patients with angiographically proven massive acute pulmonary embolism were treated. Streptokinase, 10,000-20,000 units/hour, was administered directly into the left or right pulmonary artery for 9 to 24 hours. Heparin was administered concurrently. The number of unperfused segments of the infused lung shown on the lung scan decreased from 5 +/- 2 to 2 +/- 1 after 12-24 hours (p less than .01). No change was shown in the contralateral lung. The angiographic index of severity score in the infused lung decreased from 16 +/- 1 to 9 +/- 4 (p less than .01). The partial pressure of oxygen in arterial blood improved within four hours. In spite of the low doses of streptokinase, however, two major bleeding episodes occurred that required blood transfusion. In conclusion, low dose intrapulmonary streptokinase, combined with intravenous heparin, may provide a therapeutic option in patients with life-threatening massive acute pulmonary embolism in whom full dose lytic therapy may be hazardous, although even low dose lytic therapy was associated with risk.

Aged↗