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Biomedical subjects

A Puckett

Publications and source records attributed to A Puckett.

32 records · Page 2Linked to original sources
PubMed1997

Fibrous capsule formation in response to ultrahigh molecular weight polyethylene treated with peptides that influence adhesion.

A wide variety of hard tissue substitute materials for reconstruction have been designed for use in dental and orthopaedic procedures. Most of the literature provides information on the osteocompatibility of these materials, and not on soft tissue compatibility. The bone bonding strength of the materials is relatively high, but there seems to be a lack of bonding properties with soft tissue which results in the formation of fibrous encapsulation. This lack of soft tissue bonding can lead to implant failure. Therefore in order to study how artificial materials may remain in the body for long periods of time and remain functional, it is vital to understand the fibrous tissue encapsulation process. Ultrahigh molecular weight polyethylene coated with RGD, RGE, Poly-L-Lysine, or saline was implanted into Sprague Dawley rats either intraperitoneally or subcutaneously for 12 weeks. Aseptic surgical techniques were followed according to standard laboratory procedures. Blood was collected weekly for the first 8 weeks and at 12 weeks, and analyzed for lactate dehydrogenase activity to assess muscle wasting and compatibility. Lactate dehydrogenase activity was elevated at weeks one and two for groups implanted with materials, in comparison to control unoperated animals. From weeks 3-12, the LDH activity was similar in all groups indicating that there was no adverse response to the implanted material. The implants were harvested at the end of 12 weeks, and the fibrous capsule was screened histologically to determine thickness and cell types at the interface. The results clearly showed that the implants that were placed subcutaneously had a less extensive fibrous and vascular tissue formation, than those implanted intraperitoneally. The results also indicated that the location of the implant intraperitoneally, determined the extent of the fibrous tissue formation. The implanted materials coated with RGD and Poly-L-Lysine had thicker fibrous capsule formation than RGE coated implanted at both the subcutaneous and intraperitoneal sites. The results also suggest that the implant-interface contained fewer inflammatory cells when the implants were placed subcutaneously. The overall results indicate that more than surface charge or coating govern the formation of fibrous tissue in vivo.

Amino Acid Sequence↗
PubMed1997

One year histopathological evaluation of fibrous tissue surrounding TCPL implants using adult rats as a model.

Fibrous tissue formation is often used as a screening method to determine the biocompatibility of orthopaedic and dental implanted material. In this investigation, porous implants of tricalcium phosphate-lysine delivery devices were implanted intraperitoneally (IP) using adult male rats as a model. The fibrous tissue surrounding the implant was studied histologically to determine the infiltration of inflammatory cells and other healing components. Fibrous capsular tissues were carefully dissected away from the capsule noting the tissue closest to the implanted material. Evaluation of the sections (5um, H&E) collected from various areas of the implants (n = 5 per group) revealed that: (1) The use of TCPL implants resulted in the formation of three distinct cell layers of fibrous tissue. (2) The fibrous tissue thickness was found to be directly proportional to the duration of the implant. (3) The infiltration of macrophages, polymorphonuclear leukocytes, and fibroblasts were present in all phases studied. (4) Ordered collagen was observed only at the end of the 6, 9, and 12 month phases. (5) Remarkable progression of vascularity was present in the second and third layers of the fibrous tissue. In conclusion, these observations confirm our previous finding using different bioceramic material.

Animals↗
PubMed1992

Post transfusion septicaemia 1980-1989: importance of donor arm cleansing.

AIMS: To determine the prevalence of Pseudomonas fluorescens on the arms of blood donors, and to elucidate one possible cause for its predominance (60% of cases during 1980-89) in exogenous post transfusion septicaemia (PTS). METHODS: Skin swabs were taken from the arms of 782 blood donors and cultured on to heated blood agar. After incubation, Oxidase reagent and the Gram stain were used to select non-fermentative Gram negative rods, which were then subcultured and identified using the Analytical Profile System (API) 20 NE system. RESULTS: Non-fermentative Gram negative rods were found on the arms of 11.7% of donors, Pseudomonas spp on 1.0%, and Ps fluorescens on the arms of 0.3% of donors. CONCLUSIONS: This evidence emphasises the absolute requirement for efficient skin cleansing of blood donors' arms to minimise the risk of exogenous PTS.

Bacteremia↗
PubMed1991

Caffeine and theophylline as adenosine receptor antagonists in humans.

Substantial in vitro and animal data suggest that methylxanthines, such as caffeine and theophylline, act as adenosine receptor antagonists. To test this hypothesis in humans, we first determined if theophylline would antagonize the effects of adenosine. Intravenous administration of adenosine, 80 micrograms/kg/min, increased heart rate 28 +/- 6 bpm, systolic blood pressure 19 +/- 5 mm Hg and minute ventilation 6.1 +/- 2.2 liters/min. All these changes were significantly attenuated during theophylline administration (17 +/- 3 bpm and 1 +/- 2 mm Hg and 1.6 +/- 0.6 liters/min, respectively, P less than .05), at a dose (10 mg/kg over 1 hr, followed by 1.8 micrograms/kg/min i.v.) that produced plasma theophylline levels of 17 +/- 2 micrograms/ml (94 microM). We then determined if chronic caffeine consumption resulted in upregulation of platelet adenosine receptors in eight normal volunteers. After 7 days of caffeine abstinence, the adenosine analog 5'-N-ethylcarboxamidoadenosine produced a dose-dependent inhibition of thrombin-induced aggregation (EC50 = 69 nM). Subjects then were given caffeine, 250 mg p.o. 3 times a day for 7 days. Actual caffeine withdrawal, that is, virtual disappearance of caffeine in plasma, was apparent 60 hr after the last dose of caffeine. Caffeine withdrawal produced a significant shift to the left of 5'-N-ethylcarboxamidoadenosine inhibition of aggregation (EC50 = 49 nM, P less than .01), implying sensitization and/or upregulation of adenosine receptors as seen after chronic exposure to an antagonist. These results suggest that methylxanthines act as adenosine receptor antagonists in humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1989

Serological screening tests for syphilis in pregnancy: results of a five year study (1983-87) in the Oxford region.

Between 1983 and 1987, 62 out of 76519 pregnancies in 51 mothers had a positive miniaturised Treponema pallidum haemagglutination assay (TPHA) test--1 in 1234, or 0.81 per 1000 births. About two thirds of these mothers had syphilis and the remainder non-venereal treponematoses such as yaws or pinta. Antenatal screening identified 13 patients with previously unknown acquired syphilis, 11 of whom were given antibiotics during pregnancy. There were six fetal losses among the 62 TPHA positive pregnancies, but none had evidence of congenital syphilis. No live born child in this study group showed stigmata of congenital syphilis. It is concluded that despite the current low incidence of syphilis in the United Kingdom it is imperative to continue antenatal serological screening and to emphasise the importance of early adequate treatment of the infection.

Cost-Benefit Analysis↗
PubMed1987

Syphilis screening in the Blood Transfusion Service: a report of four years' experience with the Treponema pallidum haemagglutination assay and the subsequent development of a rapid "spin" method.

A comparison of cardiolipin and a modified Treponema pallidum haemagglutination assay (TPHA) method over a four year period confirmed the superior sensitivity and specificity of TPHA. In 86,495 new donor sera 19 (0.02%) confirmed positive results were detected by TPHA, 10 of which did not react by the cardiolipin test. In 150,789 antenatal samples 49 confirmed positive results were found by TPHA, 30 of which did not react by cardiolipin. No cardiolipin positive, TPHA negative samples were confirmed as positive by the absorbed fluorescence treponemal antibody test, and overall 78% of cardiolipin reactions gave false biological positive results. Cardiolipin tests were continued only because of their speed. A further modification ("spin") of the TPHA has now been developed which is rapid, sensitive, and inexpensive, and in testing 21,807 sera, gave results equivalent to those of the previous "settle" method. Serious consideration should be given to dispensing with cardiolipin tests.

Blood Donors↗
PubMed1982

Modification of the system of screening for antisyphilis antibodies in a blood transfusion centre, featuring a miniaturisation of the Treponema pallidum haemagglutination assay.

A modified, miniaturised version of the Fujizoki Treponema pallidum haemagglutination assay (TPHA) is described. The method is fast, sensitive, specific, and very economical. During a test period of one year, use of the method gave rise to a 67% increase in confirmed positives among new donor sera and a 112.5% increase among the antenatal sera over the numbers that would have been detected using a cardiolipin test alone. With the new donor sera, the rate of confirmed positives detected during the test period was 150% greater than that of 1980, when a cardiolipin test alone was used (0.05 greater than p greater than 0.02 (chi 2 test)).

Antibodies, Bacterial↗
PubMedDate not supplied

Morphometric evaluation of tissue-implant reaction associated with ALCAP and TCP bioceramics in vivo.

The purpose of this investigation was to correlate the thickness of the fibrous capsule and the various histological components surrounding aluminum-calcium phosphate (ALCAP) and tricalcium phosphate (TCP) bioceramics at the subcutaneous (sc) and intraperitoneal (ip) implantation sites. The rational of conducting this investigation is to further elucidate the mechanisms of tissue-implant interaction. Thirteen Sprague-Dawley adult male albino rats were randomly divided into three groups. Animals in groups I and II (n = 5/group) were implanted at both ip and sc implantation sites with either ALCAP or TCP ceramics, respectively. Animals in group III (n = 3) were not implanted and served as the intact control for the comparative purposes. At 90 days postimplantation, the animals in all groups were euthanized (Ketamine/Zylazane) and the fibrous tissue surrounding the ceramic devices was retrieved. After routine histological processing, sections (5 microm) of tissue was stained with hematoxylin and eosin (H&E) and evaluated using light microscopy. With the exception ofneutrophils, at both implantation sites, the fibrous tissues surrounding the TCP bioceramics demonstrated greater capsular thickness, more vascularity, and more macrophages, fibroblasts, and collagen than those surrounding the ALCAP ceramic. Data obtained from this investigation provided further insights into the differences in the tissue-implant responses of calcium-phosphate-based ceramics and the cellular composition of the fibrous tissue reaction found at sc and ip implantation sites.

Abdomen↗
PubMedDate not supplied

The effect of incremental versus bulk fill techniques on the microleakage of composite resin using a glass-ionomer liner.

Incremental placement of composite resin has been suggested to reduce microleakage, particularly at the gingival margin of class 5 cervical restorations. It has become clinically advantageous to place a glass-ionomer liner over dentin to further minimize microleakage resulting from a bond between the dentin and glass ionomer, and glass ionomer and resin. The objective of this study was to compare the microleakage behavior of three hybrid composite/bonding agent systems using bulk and incremental filling techniques utilizing a glass-ionomer liner. This was accomplished in vitro using freshly extracted bovine incisors and a Ca45 radioisotope and autoradiography. Sixty bovine incisors were divided into six experimental groups of 10 specimens per group. Class 5 preparations were cut at the cementoenamel junction and restored with the appropriate combination of Herculite XR/Bondlite, P50/Scotchbond 2, or Pertac Hybrid/Pertac Bond. All teeth were lined with the glass ionomer Ketac Bond before the final restoration was placed. The samples were finished and stored for 24 hours in distilled water before thermocycling. The samples were tested for microleakage using a Ca45 radioisotope technique and autoradiography. Incisal (enamel) and gingival (dentin) margins were scored separately for microleakage but grouped for statistical analysis. Results were analyzed using the Kruskal-Wallis H test. Pertac Hybrid exhibited more leakage than Herculite XR or P50. The difference between microleakage of bulk and incremental filling techniques was only significant for P50.

Analysis of Variance↗