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Biomedical subjects

R G Chadwick

Publications and source records attributed to R G Chadwick.

45 records · Page 3Linked to original sources
PubMed1979

Chronic persistent hepatitis: hepatitis B virus markers and histological follow-up.

Twenty-six untreated patients with chronic persistent hepatitis were followed prospectively for one to 17 years (mean 5.6 years). The patients developed no clinical features of chronic liver disease. Raised serum transaminase levels were usually, but not consistently, the only biochemical abnormality; gamma globulin values were normal. Serum markers of past or present hepatitis B infection were found initially in 14 patients: another two developed markers during their follow-up. Nine patients progressed to a mild or moderate chronic active hepatitis as shown by serial needle liver biopsies but there was no evidence of cirrhosis. This progression was not associated with any clinical or biochemical deterioration. Seven of these patients had presented with insidious symptoms, seven had serum markers of hepatitis B infection, and the four who were HBsAg positive had relatively lower serum HBsAg concentrations than did those patients who continued with chronic persistent hepatitis.

Adult↗
PubMed1978

HBsAg-positive chronic liver disease: inhibition of DNA polymerase activity by vidarabine.

Four patients who had chronic liver disease and were positive for hepatitis B surface antigen (HBsAg) were treated with vidarabine, a synthetic purine nucleoside that inhibits DNA polymerase activity in vitro and in vivo. Before treatment all had raised serum DNA polymerase concentrations. Three also had hepatitis B e (HBe) and were shown by electron microscopy to have hepatitis B virus (Dane) particles in their serum. In all patients 10 days' treatment with vidarabine resulted in an immediate loss of DNA polymerase activity. In three patients the activity returned when treatment was stopped. In those three patients Dane particles and HBe antigen persisted during and after treatment; in the fourth patient, who remained negative for DNA polymerase, HBsAg titres fell. Although vidarabine inhibited virus replication, virus particles did not disappear from the blood in these patients, presumably because the particles were cleared only slowly. Similar results with interferon suggest that the virus disappears, and HBsAg titres fall, some weeks after the fall in DNA polymerase activity. Continued treatment may therefore have a sustained effect on viral replication. Whether vidarabine can permanently clear HBsAg and so arrest chronic liver disease remains to be seen, but at the very least it could reduce the spread of infection.

Adult↗
PubMed1978

Chronic active hepatitis, haemolytic anaemia and Listeria monocytogenes bacteraemia.

The association of chronic active hepatitis with haemolytic anaemia is well known. Both conditions may respond to steroid therapy which, in common with other causes of suppressed T-lymphocyte function, predispose to many types of infection. A case is described in which transient Listeria monocytogenes bacteraemia occurred and the patient recovered without antimicrobial therapy.

Anemia, Hemolytic↗
PubMedDate not supplied

Treatment of dentin with polyacrylic acid--a retrospective observational study of the effect upon the durability of glass ionomer restorations.

This paper reports on the results of a material specific, retrospective observational study. It sought to determine the consequence of pretreatment of cavity margins with the conventional glass polyalkenoate Chemfil II prior to restoration with Tooth Cleanser on restoration durability. All restorations were placed and varnished by senior dental students under the supervision of a staff member. Manufacturer recommendations were followed. Data on each restoration was collected and entered into a relational computer database. Data included details of cavity morphology and the use or non-use of Tooth Cleanser. Six years following the study start a manual search of all records was carried out to determine, for those patients continuing to attend the Dental Hospital, the number of failed and surviving restorations. This yielded a dataset of 149 restorations, of which 41 had been placed with the aid of Tooth Cleanser and 108 without. The number of failed restorations was 20 and 62, respectively. Survival analysis by the Kaplan-Meier method revealed median survival times of 2,094 days, when Tooth Cleanser was used and 1,748 days when not. Although 80% survival times of 1111.0 (SE = 6.3) (With Tooth Cleanser) and 285.0 (SE = 3.8) (Without Tooth Cleanser) days were observed, together with a Hazard Ratio of 1.49 (95% Confidence Intervals 0.92 & 2.31), a Logrank test revealed no statistically significant difference between the survival curves (p = 0.12). It was concluded that although there was a trend for the application of Tooth Cleanser to improve the chances of obtaining a dependable restoration, this effect was not statistically significant.

Acrylic Resins↗
PubMedDate not supplied

A retrospective observational study of the effect of surface treatments and cementing media on the durability of gold palatal veneers.

This paper reports on the results of a retrospective observational study that sought to determine both the longevity and effects of surface treatments of gold palatal veneers used to restore tooth surface loss. Details of all gold palatal veneers fabricated from Mattident 60 were sourced from hospital records spanning 11 years and 9 months. The case notes of each individual were accessed and, for each restoration, a note was made of the date and method of cementation, together with the period of patient follow-up. When patients continued their routine checkups, the records were scrutinized closely for evidence of restoration failure. This yielded a data set of 151 palatal gold veneer cementations for which the surface treatments and/or cementing media were known. Survival analysis by the Kaplan-Meier method of alumina blasted veneers revealed median survival times of 4,663 days when cemented with Panavia 21 and 687 days if cemented with Aquacem. Veneers that were alumina blasted, oxidized and cemented with Panavia 21 had a survival probability of 1.0. A Logrank test revealed highly statistically significant differences between the survival curves (p<0.0001). It was concluded that: (1) Alumina blasting the fit surface of a gold veneer prior to cementation with Panavia 21 resulted in a significantly more durable restoration compared to alumina blasting and cementation with Aquacem and no etching of tooth substance. (2) Due to low MST cementing, gold palatal veneers with a conventional glass polyalkenoate cement are not recommended. (3) Pre-treatment of gold palatal veneers by alumina blasting and oxidation prior to cementing with Panavia 21 appears to improve the chances of obtaining a dependable restoration. A greater number of restorations would be required to statistically test this trend.

Acid Etching, Dental↗
PubMedDate not supplied

Maximizing the clinical exposure of dental students to conservative dentistry: design and evaluation of a novel system.

A system has been designed to maximize the clinical experience that dental students receive in the discipline of conservative dentistry. Data on each operative procedure to be carried out for each patient under a student's care is entered into a customized computer database and each student is given a printout of this information every 4 months. Students feel that this system prospectively identifies areas of treatment in which they may lack experience and provides opportunities to review and amend any inaccurate information. This paper explains how the system was set up and administered.

Computer-Assisted Instruction↗