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Biomedical subjects

M J Roberts

Publications and source records attributed to M J Roberts.

At least 55 records · Page 3Linked to original sources
PubMed1991

Anistreplase in early acute myocardial infarction and the one-year follow-up.

Of consecutive patients seen with first myocardial infarction (88 of whom were treated out-of-hospital by mobile coronary care staff), 139 received 30 units of intravenous anistreplase at a mean of 101 minutes (range 35-180) from onset of symptoms. Thrombolysis in myocardial infarction patency grade 2 or 3 was found in 76/91 (83.5%) patients. At 3-4 months after hospital discharge, the mean global left ventricular ejection fraction and mean infarct-related regional third ejection fraction declined with increasing delay to anistreplase. For the first, second and third hour administrations, global ejection fraction was 54%, 50% and 45% (P = 0.002) and for regional third ejection fractions 49%, 43% and 41% (P = 0.02) respectively. Of the patients, 130 were reviewed at approximately 1 year: reinfarction had occurred in 9, 6 had undergone coronary angioplasty and 1 had coronary arterial bypass grafting performed since discharge. Mean global left ventricular ejection fraction was 52% and mean infarct-related regional third ejection fraction was 51%. Thus, intravenous anistreplase induces high rates of arterial patency. Global and regional third ejection fractions decline with increasing delay in the time of administration of anistreplase. Mortality and morbidity is low in the first year.

Adult↗
PubMed1991

Controlled release microparticles for vaccine development.

The primary and secondary sera IgG antibody responses to ovalbumin (OVA) entrapped in biodegradable poly(lactide-co-glycolide) (PLGA) microparticles were compared with the responses obtained with soluble OVA. In addition, OVA in PLGA microparticles was also administered after dispersion in an immunostimulatory vehicle, Freund's incomplete adjuvant (FIA). The primary IgG responses to OVA in microparticles/FIA were significantly greater than the responses to soluble OVA from day 14 to day 42, when booster immunizations were administered. From day 49 to the end of the study at day 84, the responses to OVA, both in microparticles alone and in microparticles/FIA, were significantly greater than the responses to soluble OVA. Nevertheless, the responses obtained for OVA in microparticles or microparticles/FIA were, in general, not as high as those obtained with OVA in Freund's complete adjuvant.

Animals↗
PubMed1991

Variables influencing the repair strength of dental composites.

Differences in the flexural strength of composites (P-30) repaired with four different adhesive techniques were determined and compared to the flexural strength of unrepaired specimens. Besides investigating the effects of differences in repair methods, both the effect of composite age at repair time and the effect of water storage on flexural strength were evaluated. No significant differences were found between specimens which had been stored for different times (1 or 60 days) before they were repaired. All specimens, including the unrepaired ones, became weaker with time in water. After both 90 and 360 days at 37 degrees C in water, the strength of the repaired specimens ranged between 25 and 50% of the strength of the unrepaired specimens. The weakest group was the one which had been repaired after acid etching, water rinsing, and air drying only.

Acid Etching, Dental↗
PubMed1991

Excretion of indomethacin in breast milk.

1. The excretion of indomethacin into breast milk and subsequent exposure of infants was studied in 16 women and seven of their infants. The median milk:plasma ratio in seven patients where there were measurable drug concentrations in both milk and plasma was 0.37. 2. Total infant dose, assuming a daily milk intake of 150 ml kg-1 and 100% absorption, ranged from 0.07% to 0.98% (median = 0.18%) of the weight adjusted maternal dose. 3. Plasma samples were obtained in seven infants. In six of these, indomethacin concentrations were below the sensitivity of the assay (less than 20 micrograms l-1), while one infant had a plasma indomethacin concentration of 47 micrograms l-1. 4. No adverse effects due to indomethacin were reported in the infants.

Adult↗
PubMed1990

Transient release of lipid peroxides after coronary artery balloon angioplasty.

Free radical production may cause myocardial damage during reperfusion of ischaemic myocardial tissue; when free radicals interact with polyunsaturated fatty acids or their esters, lipid peroxides are produced. A product of lipid peroxidation, malondialdehyde, was measured in 10 subjects with stable angina who underwent angioplasty of a proximal high-grade stenosis (over 90%) of the left anterior descending coronary artery. In all subjects the duration of balloon occlusion was 60 s. Blood was withdrawn from the great cardiac vein immediately before balloon inflation (T0), immediately after balloon deflation (T60), 15 s after balloon deflation (T75), and 1 min after balloon deflation (T120). There was a significant increase in malondialdehyde at T60 compared with T0 for the first balloon inflation (mean increase 0.3 mumol/l [95% confidence limits 0.1, 0.5]), and at both T60 (0.31 mumol/l [0.15, 0.47]) and T75 (0.22 mumol/l [0.04, 0.40]) for the second balloon inflation. This model could be used to assess antioxidant effects of drugs.

Adult↗
PubMed1990

Effects of tumor necrosis factor alpha and beta on resorption of human articular cartilage and production of plasminogen activator by human articular chondrocytes.

We examined the effects of recombinant human tumor necrosis factor (TNF) on human articular cartilage and chondrocytes in culture. Both TNF alpha and TNF beta stimulated cartilage matrix breakdown during prolonged culture and elevated the levels of plasminogen activator (PA) activity in both the supernatants and cell layers of cultured chondrocytes. Characterization of the PA activities by immunochemistry and by zymography following gel electrophoresis indicated that human chondrocytes produce both urokinase-type PA and tissue-type PA in response to TNF. The addition of both interleukin-1 and TNF alpha or TNF beta to chondrocyte cultures demonstrated a synergism between these cytokines in the generation of PA activity in the culture supernatants and cell layers. Our results suggest that both activated lymphocytes and monocytes may contribute to the cartilage destruction of inflammatory arthritis through their stimulation of chondrocytes with TNF beta and TNF alpha, respectively. Since PA is the only neutral proteinase reported to be elevated in TNF-stimulated chondrocyte cultures, it could have an important role in TNF-mediated cartilage destruction.

Cartilage, Articular↗
PubMed1990

Influence of water exposure on the tensile strength of composites.

The objective of this study was to investigate whether water storage causes permanent damage to composites by determining how the tensile strength of nine different composite materials changes with both water storage and water storage followed by dehydration. Eighteen samples (ASTM-D Specification 1708-66) of each of the nine materials were prepared and divided into three groups of six samples each. Group I was stored dry at 60 degrees C, while Groups II and III were stored in distilled water at 60 degrees C. After six months, Groups I and II were subjected to tensile testing, while Group III was transferred to a desiccator and dehydrated for two weeks at 60 degrees C before this group was tested in tension. Mean values, pooled by storage group independent of material, revealed a significant (p less than 0.05) reduction in strength for both Groups II and III relative to Group I. These findings prove that water has an irreversible effect on most dental composites. A comparison of Group II with Group III data revealed that the samples which were aged in water and tested (Group II) were significantly (p less than 0.05) weaker than the dehydrated samples (Group III). However, some products within Group III did not show any tendency to recover their strength after dehydration.

Composite Resins↗
PubMed1989

Comparison of three techniques for measuring wear of dental restorations.

Measurements of impression profiles, profilometer registrations, and scanning electron microscopy (SEM) photogrammetry of metal dies simulating worn restorations were compared as possible techniques for measuring and recording the wear rate of tooth restorations. The results showed that measurements of impression profiles and SEM photogrammetry gave the most accurate results adjacent to regions simulating steep cavity margins, whereas the profilometric technique gave erroneous results in these regions. These errors were related to interference between the conical stylus tip and the steep edges. Moreover, photogrammetry was time-consuming and complex and did not result in better overall precision than with the other evaluation techniques. These drawbacks with SEM photogrammetry were related to complex use of software and low precision of crucial hardware components such as SEM tilt stage and digitizer.

Dental Materials↗
PubMed1989

Palatal rugae.

Explore the source record for details and available documents.

Journal Article↗
PubMed1988

Evaluation of a new, shorter method of administration of adrenergic aerosols in the treatment of asthma.

Approximately 15 to 20 minutes are usually required to administer adrenergic agents by nebulization in the treatment of asthma. But young children often do not tolerate these prolonged treatment periods. A "5-breath" method was found to provide comparable improvements in pulmonary function and result in minimal and comparable side effects, but required only one minute to administer. The "5-breath" method may, therefore, be the method of choice in the young or otherwise uncooperative patients.

Administration, Inhalation↗
PubMed1987

Recording schedule II drug use in a decentralized drug distribution system.

A decentralized system for Schedule II controlled substance distribution and accounting that does not rely on proof-of-use sheets is described. Controlled substances are kept in a vault in the central pharmacy; technicians assigned to work in the controlled substances vault are responsible for monitoring, ordering, and storing these medications. The narcotic vault technicians also prepare narcotic boxes that are used by technicians in patient-care areas to transport and issue Schedule Ii substances to nursing units. Twice during each morning and evening shift, technicians in patient-care areas visit each nursing station, replenish the unit's stock of Schedule II medications, and document on a narcotic use form all doses that have been administered since the last technician visit. Nurses leave small cards preprinted with patients' names and room information in the narcotic drawers to alert technicians to administered doses of Schedule II substances; the technicians are responsible for reconciling medications missing from the drawers with doses recorded in patients' medication administration records as being administered. Periodic audits are performed to ensure that actual inventories and the recorded information are correct. The decentralized system for distribution and accounting of Schedule II substances has been successful in increasing the flexibility of inventories on individual nursing units and ensuring maximal pharmacy department control over the dispensation of these medications.

Humans↗
PubMed1986

Formulary management to reduce cost: P & T committee strategies.

The hospital pharmacy can achieve cost reductions through a variety of means. These include controlling personnel costs, conducting systems and facilities design analyses, operating shared services, controlling inventory, and assisting the P & T Committee in implementing and operating a hospital formulary system. The type of formulary system within an institution and the effectiveness of the P & T Committee both influence cost saving programs in acquiring and dispensing therapeutic agents. Strategies effective in developing a workable formulary and ways in which the P & T Committee can encourage cost-effective drug acquisition and use are outlined.

Cost Control↗
PubMed1986

Palatal rugae in Swazi, southern Africa.

In a sample of Swazi (47 males and 70 females) the palatal rugae were studied and the results compared with those in the literature. The rugae are generally strong and show considerable complexity. Strength of ridges is associated with arch height, which suggests common factors in development.

Adolescent↗