PubMed Health⌕ Search

Biomedical subjects

J R Wagner

Publications and source records attributed to J R Wagner.

At least 19 recordsLinked to original sources
PubMed1992

Endogenous oxidative damage of deoxycytidine in DNA.

Three major oxidation products of 2'-deoxycytidine (dC)--5-hydroxy-2'-deoxycytidine (oh5dC), 5-hydroxy-2'-deoxyuridine (oh5dU), and 5,6-dihydroxy-5,6-dihydro-2'-deoxyuridine (dUg)--were analyzed from enzymatically hydrolyzed DNA with reversed-phase high-performance liquid chromatography coupled to electrochemical detection. oh5dC and oh5dU can be detected with high sensitivity (50 fmol) and selectivity (0-0.2 V) from hydrolyzed DNA. dUg is not electrochemically active but can be measured by dehydrating it into oh5dU. The quantities of oh5dC, dUg, and oh5dU in untreated commercial-grade calf thymus DNA are 10, 10, and 0.75 fmol/micrograms of DNA, respectively. These levels increased substantially when calf thymus DNA was exposed to ionizing radiation, H2O2 alone, H2O2 and combinations of Fe3+ or Cu2+ and ascorbate, near-UV light (365 nm), near-UV light in the presence of menadione, and OsO4, indicating that oh5dC, oh5dU, and dUg are major oxidative DNA damage products. The steady-state levels of these products were determined from freshly extracted rat tissues and ranged from less than 0.5 fmol/micrograms of DNA for oh5dU to about 10 fmol/micrograms of DNA for oh5dC and dUg in liver and kidney and 22 fmol/micrograms of DNA for oh5dC in brain. The levels of oxo8dG were also determined and in general were somewhat lower than the levels of oh5dC. These findings reinforce the link between DNA damage induced by oxidative metabolism and spontaneous mutagenesis leading to cancer and aging.

Animals↗
PubMed1992

Portable ultrasonography in critical care.

A 2-year retrospective analysis of portable ultrasound examinations in the intensive care unit was conducted to evaluate the indications and efficacy of portable sonography. A total of 86 examinations were performed on 79 patients. Of these, 22 per cent of the examinations supported the suspected diagnosis and contributed to treatment. Seventy per cent of the examinations excluded the suspected diagnosis. There was a 9 per cent incidence that yielded unsuspected information that contributed to treatment. Only 8 per cent of the examinations were misleading or proven false. The authors found that with an overall sensitivity of 79 per cent and specificity of 97 per cent, portable ultrasonography is a valuable, relatively inexpensive test in the critical care setting.

Abscess↗
PubMed1992

Sinus lift grafts and endosseous implants. Treatment of the atrophic posterior maxilla.

Patients from multicenters were treated with sinus lift graft operations and placement of implants. Surgical procedures healed uneventfully with minimum pain, swelling, or morbidity. Grafts healed with few complications or failures. Implants placed into the grafts support prosthetic reconstruction and are predictable over time. The question of what graft material to use is discussed. Grafts of non-resorbable HA (Interpore 200), bovine cortical HA (Bio-Oss), resorbable HA (OsteoGen), and freeze-dried demineralized bone powder and granules are presented. Results of biopsy, histometry, backscattered electron microscopy, cell labeling, and special stain suggest consistent bone growth into a variety of graft materials. In the authors' opinion investigation must continue to 1. Determine the healing time for different graft materials. At present, anecdotal evidence suggests that sinus grafts of autogenous bone heal for 4 to 6 months; freeze-dried demineralized bone heals for 12 to 16 months; and alloplastic materials with freeze-dried demineralized bone heal for 9 to 11 months. 2. Evaluate histologic evidence of bone growth into different bone replacement graft materials. 3. Evaluate the long-term follow-up and success of implants placed within sinus grafts. 4. Determine the remodeling potential of different hard tissue graft materials under implant functional loads.

Atrophy↗
PubMed1990

Quinone sensitized electron transfer photooxidation of nucleic acids: chemistry of thymine and thymidine radical cations in aqueous solution.

The 2-methyl-1,4-naphthoquinone (MQ) sensitized photooxidation of nucleic acid derivatives has been studied by laser flash photolysis and steady state methods. Thymine and thymidine, as well as other DNA model compounds, quench triplet MQ by electron transfer to give MQ radical anions and pyrimidine or purine radical cations. Although the pyrimidine radical cations cannot be directly observed by flash photolysis, the addition of N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD) results in the formation of the TMPD radical cation via scavenging of the pyrimidine radical cation. The photooxidation products for thymine and thymidine are shown to result from subsequent chemical reactions of the radical cations in oxygenated aqueous solution. The quantum yield for substrate loss at limiting substrate concentrations is 0.38 for thymine and 0.66 for thymidine. The chemistry of the radical cations involves hydration by water leading to C(6)-OH adduct radicals of the pyrimidine and deprotonation from the N(1) position in thymine and the C(5) methyl group for thymidine. Superoxide ions produced via quenching of the quinone radical anion with oxygen appear to be involved in the formation of thymine and thymidine hydroperoxides and in the reaction with N(1)-thyminyl radicals to regenerate thymine. The effects of pH were examined in the range pH 5-8 in both the presence and absence of superoxide dismutase. Initial C(6)-OH thymine adducts are suggested to dehydrate to give N(1)-thyminyl radicals.

Cations↗
PubMed1990

A new osteoconductive resorbable hydroxylapatite graft material that restores bony defects with viable bone.

The reconstruction and repair of a large mandibular bony defect following an extraction was accomplished using resorbable hydroxylapatite OsteoGen (HA RESORB). The complete repair of the defect and alveolar architecture with dense regenerated bone was achieved prior to the surgical insertion of an endosseous titanium implant. The implant was used for additional support for a long span fixed prosthesis. Histological studies of harvested bone core specimens of the resorbable hydroxylapatite grafts at four months and 14 months are compared and discussed in this report.

Aged↗
PubMed1989

Long-term phorbol ester treatment dissociates phospholipase D activation from phosphoinositide hydrolysis and prostacyclin synthesis in endothelial cells stimulated with bradykinin.

Bovine pulmonary artery endothelial cells (BPAEC) were prelabeled with [3H]choline or [3H]myristic acid to selectively label endogenous phosphatidylcholine. BPAEC were stimulated with ATP and bradykinin (BK), and phospholipase D (PLD) activation was detected as a 4-fold increase in [3H]choline in cells prelabeled with [3H]choline or as a 2- to 3-fold increase in [3H]phosphatidylethanol in cells prelabeled with [3H]myristic acid and stimulated in the presence of ethanol. Pretreatment of BPAEC with 0.1 microM phorbol 12-myristate 13-acetate (PMA) for 22 hr completely inhibited agonist-induced PLD activation, whereas prostacyclin synthesis and [3H]phosphoinositide ([3H]PIns) hydrolysis were enhanced in pretreated cells. Long-term PMA treatment thus dissociates agonist-induced PLD activation from [3H]PIns hydrolysis, and agonist-induced prostacyclin synthesis is not dependent upon PLD activation.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Clinical and histological case study using resorbable hydroxylapatite for the repair of osseous defects prior to endosseous implant surgery.

A clinical case--a follow-up clinical and histological study--is presented in this paper, which describes the use of resorbable hydroxylapatite [OsteoGen (H.A. Resorb), Impladent, Inc., & GBD Marketing Group, Inc., Medical Division, Valley Stream, NY 11580] for the repair of a large mandibular lesion, followed by the placement of an endosseous dental implant six weeks after the graft placement. A comparison of the histological results of four-month and 14-month bone biopsies of resorbable hydroxylapatite grafts is included in this report.

Adult↗
PubMed1989

Aortic graft-enteric fistula and paraprosthetic-enteric fistula: a review.

AGEF/PPEFs are infrequent, life-threatening complications of aortic reconstructive surgery. Early diagnosis requires a high index of suspicion. Whenever a patient with an aortic prosthesis develops gastrointestinal bleeding or manifestations of sepsis, the presence of a fistulous complex should be assumed until proven otherwise. In the vast majority of cases, adequate surgical management requires graft excision with extraanatomic bypass. Widespread retroperitoneal infection precludes any attempt at local revascularization.

Aorta, Abdominal↗
PubMed1987

Specific deprotonation reactions of the pyrimidine radical cation resulting from the menadione mediated photosensitization of 2'-deoxycytidine.

Menadione(2-methyl-1,4-naphthoquinone) was shown to sensitize 2'-deoxycytidine to near ultraviolet light according to two main mechanisms. Reaction of a water molecule with the initially photo-induced pyrimidine radical cation and subsequent addition of molecular oxygen leads to the preponderant formation of the four cis and trans diastereoisomers of 5,6-dihydroxy-5,6-dihydro-2'-deoxyuridine. Pyrimidine ring opening and rearrangement products are also generated through the intermediate 6-hydroxy-5,6-dihydro-2'-deoxyurid-5-yl radical. The competitive deprotonation reaction of the radical cation is likely to involve two sites. Loss of an amino group proton is the likely initial event to explain the formation of 2'-deoxyuridine which is resistant to further photooxidation. The second deprotonation reaction involves the osidic carbon C(1'). The resulting radical will further react with oxygen leading to the release of free cytosine with concomitant formation of 2-deoxy-D-ribono-1,4-lactone. This reaction which is not prevented by hydroxyl radical scavengers constitutes to our knowledge the first example of a pyrimidine radical which is able to initiate selective intramolecular reaction at position 1 within the sugar moiety.

Carbon Radioisotopes↗
PubMed1979

Development of a multifunctional drug file for hospital pharmacy computer applications.

The development of a multifunctional master drug file (MDF) which satisfies initial pharmacy data base requirements and has the capability to support increasingly sophisticated computer applications is described. The computerized purchasing, inventory, drug use review and formulary systems in a 1,100-bed teaching hospital were evaluated to determine which existing data fields should be included in the MDF, Functional requirements for the MDF and 27 data fields, each with its own particular specifications for programming, were identified. A method of data input was designed to create and maintain the file using keypunched Hollerith cards. Data input forms were designed to serve as coding documents for drug file data. Verification of all data in the file can be performed by running a program which lists the contents of each drug recorded. Based on 1975 salary rates, the total cost of the MDF development was $4,010; total time required was 640 hours. Approximately one hour per week is needed to keep the file contents up to date. File design specifications and contents are discussed, with special emphasis on the functional aspects of the MDF. The MDF successfully fulfilled the initaial pharmacy computer system requirements and has the potential to accommodate increasingly sophisticated applications.

Computers↗
PubMed1978

Distributed processing techniques: interface design for interactive information sharing.

The Information Systems Division of the University of Iowa Hospitals and Clinics has successfully designed and implemented a set of generalized interface data-handling routines that control message traffic between a satellite minicomputer in a clinical laboratory and a large main-frame computer. A special queue status inquiry transaction has also been developed that displays the current message-processing backlog and other system performance information. The design and operation of these programs are discussed in detail, with special emphasis on the message-queuing and verification techniques required in a distributed processing environment.

Computers↗