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Biomedical subjects

R J Mitchell

Publications and source records attributed to R J Mitchell.

At least 73 records · Page 4Linked to original sources
PubMed1989

Mold inversion and abrasion resistance of a type IV stone.

The objective of this study was to determine whether placing the impression and diestone so the impression is on the top during setting affects the resulting die's abrasion resistance. Impressions of a brass bar with a milled 90 degrees edge were obtained by use of a polysulfide impression material in a rigid brass tray. A Type IV diestone was vacuum-mixed and vibrated into the impression. Eight procedures were compared: (1) no inversion; (2) inversion at initial set; (3,4) inversion one or two min before initial set; and (5,6,7,8) inversion 1.5, 3, 5, or 12 min after initial set. Each specimen was abraded 24 hours after mixing. Specimens inverted at 1.5 and 3 min after initial set were significantly more abrasion-resistant than were all other treatments.

Calcium Sulfate↗
PubMed1989

Group-specific component subtypes in the population of Tasmania, Australia.

Plasma specimens from 2,010 blood donors resident throughout the island State of Tasmania, Australia, were examined for group-specific component (GC) sub-types using polyacrylamide gel iso-electric focusing. Subdivision of the island into 8 geographic regions revealed no significant heterogeneity. Comparison of GC allele frequencies with those reported in mainland Australian populations indicated that Tasmanian values lie well within the ranges previously reported.

Alleles↗
PubMed1989

No evidence for an association between glyoxalase 1 and haptoglobin in the white population of Victoria, Australia.

No association between the glyoxalase 1 (GLO1) and haptoglobin (HP) systems was found in a sample of 1,270 white blood donors in the State of Victoria, Australia. This finding is in contrast to previous data for blood donors in Newfoundland, Canada, a population also of Anglo-Irish descent. However, the differences between the joint phenotypic distributions of GLO and HP in the 2 data sets were statistically insignificant.

Australia↗
PubMed1989

Radiolucent halos associated with radiopaque composite resin restorations.

Since the introduction of radiopaque composite resins, clinicians and researchers have occasionally noticed radiolucent halos adjacent to composite restorations. Such halos have frequently been thought to be recurrent caries or voids in the material. Fifteen of 45 radiopaque composite resin restorations placed by students enrolled in a first-year preclinical operative dentistry course exhibited such halos. Micrographs showed that a thick layer of unfilled resin bonding agent was present. These halos were reproduced in other teeth when excess bonding was not blown off. The results indicate the importance of meticulous technique.

Adhesives↗
PubMed1988

Boron fertilization and carbohydrate relations in mycorrhizal and nonmycorrhizal shortleaf pine.

Eight-week-old shortleaf pine seedlings (Pinus echinata Mill.) with and without ectomycorrhizae formed by Pisolithus tinctorius were treated for two to eight weeks with 25 microg borate ml(-1) solution applied either to the soil, or as a foliar spray, or in both ways. Control seedlings were fertilized only with modified Hoagland's solution containing 0.03 microg ml(-1) borate. Five sugars (pinitol, fructose, glucose, myoinositol and sucrose) were quantitated in both mycorrhizal and nonmycorrhizal roots by gas-liquid chromatography. Fertilization with boron increased the total carbohydrate content of mycorrhizal roots except in seedlings receiving foliar applications of boron. Foliar + soil fertilization yielded a 24% increase in total carbohydrates in mycorrhizal roots, whereas foliar fertilization alone decreased the total carbohydrate content. Carbohydrate content of nonmycorrhizal roots was significantly increased only by soil fertilization with boron. Individual sugars were affected less by boron fertilization in nonmycorrhizal roots than in ectomycorrhizal roots. However, significant increases in sugars in response to boron fertilization were observed in both ectomycorrhizal and nonmycorrhizal plants.

Journal Article↗
PubMed1988

Haptoglobin groups and transferrin subtypes in multiple myeloma.

Haptoglobin and transferrin types were determined for 27 multiple myeloma patients and a series of case controls. No association was found between haptoglobin and the disease, which confirms the findings of an earlier investigation. However, we found a significantly increased relative risk of 2.6 for TFC1C1 individuals. It is suggested that the role of transferrin in erythropoiesis and cell proliferation of both malignant and normal cells, may, at least in part, explain the association. Of additional relevance may be the suggestion that TFC1C1 individuals have higher blood iron levels than other subtypes.

Adult↗
PubMed1988

Associations between the two serum proteins haptoglobin and transferrin and leukaemia.

Haptoglobin and transferrin (TF) types were determined for 134 patients with leukaemia of the four most common types: acute lymphocytic (ALL), chronic lymphocytic (CLL), acute myelocytic (AML) and chronic myelocytic leukaemia (CML). The phenotype HP1 was found to have an increased incidence in the total patient group due to an increased incidence in those with AML, ALL and CML compared with controls, but not in those with CLL. Although tests of association applied to each of the samples of the four common types of leukaemia produced no significant chi 2 values, they did indicate that the relative incidence (RI) was just under 2 for the groupings of the acute forms ALL and AML, the myelocytic forms AML and CML and for the combination of ALL, AML and CML, respectively. All these associations were statistically significant (p less than 0.05). Analysis of TF subtypes and leukaemia indicated a significantly increased frequency of TF C1C1 among leukaemia patients compared with controls (p less than 0.005). Analysis of the samples of each of the four common types suggested that while the RI was raised in all but ALL patients, the association was significant only in AML patients (p less than 0.05). However, when the two myelocytic types were combined the RI was 2.3 and the association was highly significant (p less than 0.005). No such association could be detected in the lymphocytic forms.

Alleles↗
PubMed1988

Interaction between AB0 and haptoglobin in a white Australian population.

Blood samples from over 2,200 blood donors resident in the State of Victoria were investigated for the association between the AB0 and haptoglobin (HP) blood systems reported by others. No association between the phenotypes of the 2 systems was found but the distribution of the HP*1 allele varied among AB0 groups, and the difference between those who were group 0 and the other AB0 groups combined was significantly (p less than 0.05). Overall, the findings were similar, but not as pronounced, as those reported in the Hutterites.

ABO Blood-Group System↗
PubMed1988

Gloved and ungloved: performance time for two dental procedures.

This study examines the time required to perform two routine dental procedures requiring fine hand manipulative skills--a pin placement procedure and an endodontic procedure. No significant time difference was noted in performing the procedures while wearing gloves or not wearing gloves. Twelve dentists who had routinely worn gloves for the past 6 months participated, each performing four procedures.

Dental Pins↗
PubMed1986

Boron and ectomycorrhizal influences on indole-3-acetic acid levels and indole-3-acetic acid oxidase and peroxidase activities of Pinus echinata Mill. roots.

The level of indole-3-acetic acid (IAA) in shortleaf pine (Pinus echinata Mill.) roots was increased by inoculation with the ectomycorrhizal fungus Pisolithus tinctorius (Pers.) Coker and Couch. Indole-3-acetic acid oxidase activity was also increased suggesting that the increased level of IAA was the result of increased synthesis. Boron fertilization reduced IAA levels in roots inoculated with P. tinctorius but not in noninoculated roots.

Journal Article↗
PubMed1986

Population genetics of blood group polymorphisms in a sample of newborns from Melbourne, Australia.

Blood from 304 newborn infants of Melbourne, Australia, was examined for 9 polymorphic systems (red cell antigens ABO, MNSs, Rh, Kell, Duffy and Kidd, the red cell enzyme ESD and serum proteins GC and TF) in order to investigate the evolution of the Melbourne gene pool since 1975. Immigration patterns have changed considerably over the past 10 years, especially with an increase in refugees from South-East Asia. Three ethnic categories were identified on the basis of surnames; British Isles, Europe and Middle East, and South-East Asia, with the respective allele/haplotype frequencies of these groups being similar to those found in the source regions. Analysis by an R-matrix indicated that the Asians form a very distinctive subpopulation, but that their influence is minimal to date.

Australia↗
PubMed1985

Serum protein polymorphisms in patients with primary Sjögren's syndrome.

The distribution of 4 serum proteins, the protease inhibitor alpha-1-antitrypsin, haptoglobin, transferrin and group-specific component or vitamin D-binding protein, were examined in 26 patients with primary Sjögren's syndrome and 208 healthy donor controls. No significant associations were found between any of the 4 systems and susceptibility to primary Sjögren's syndrome.

Blood Proteins↗
PubMed1985

GC subtypes and malignant melanoma.

Using polyacrylamide gel isoelectric focusing (PAGIF), group-specific component (GC) subtypes were determined for 64 malignant melanoma patients and 208 controls residing in Victoria, Australia. No association was found, confirming the results of earlier studies.

Adult↗