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Biomedical subjects

S H Abrams

Publications and source records attributed to S H Abrams.

7 recordsLinked to original sources
PubMed2005

Feeding a corn oil/sucrose-enriched diet enhances steatohepatitis in sedentary rats.

The current study investigated the combined effects of feeding a high-fat/high-sucrose (HF/HS) diet to rodents rendered sedentary via hindlimb unloading (HU). For 3 wk before HU, male Wistar rats were fed chow or a diet in which 32% of calories were derived from corn oil fat and 48% of calories from sucrose. Feeding continued during an additional 3-wk period of HU. Subsequently, blood samples were collected for determination of circulating leukocyte counts, insulin levels, and portal vein endotoxin. Inflammation, necrosis, and steatosis were assessed in formalin-fixed liver sections. No biochemical or histological evidence of injury was observed in control rats fed chow or HF/HS. HU increased circulating neutrophils and resulted in hyperinsulinemia. Mild hepatic fat accumulation and minimal focal necroinflammation were observed in this group. Feeding HF/HS during HU exacerbated hyperinsulinemia, hepatic steatosis, Kupffer cell content, and cytokine expression. Significant portal endotoxemia was noted in HU rats but was not influenced by HF/HS diet. On the other hand, feeding HF/HS significantly enhanced lipid peroxidation end products in liver of HU rats by approximately threefold compared with chow-fed rats. In summary, these findings demonstrate that feeding a high-calorie diet potentiates steatosis and injury in sedentary HU rats. Mechanisms underlying enhanced injury most likely involved lipid peroxidation. Importantly, these findings suggest that dietary manipulation combined with physical inactivity can be used to model steatohepatitis.

Animals↗
PubMed2000

Novel dental dynamic depth profilometric imaging using simultaneous frequency-domain infrared photothermal radiometry and laser luminescence.

A high-spatial-resolution dynamic experimental imaging setup, which can provide simultaneous measurements of laser-induced frequency-domain infrared photothermal radiometric and luminescence signals from defects in teeth, has been developed for the first time. The major findings of this work are (i) radiometric images are complementary to (anticorrelated with) luminescence images, as a result of the nature of the two physical signal generation processes; (ii) the radiometric amplitude exhibits much superior dynamic (signal resolution) range to luminescence in distinguishing between intact and cracked sub-surface structures in the enamel; (iii) the radiometric signal (amplitude and phase) produces dental images with much better defect localization, delineation, and resolution; (iv) radiometric images (amplitude and phase) at a fixed modulation frequency are depth profilometric, whereas luminescence images are not; and (v) luminescence frequency responses from enamel and hydroxyapatite exhibit two relaxation lifetimes, the longer of which (approximately ms) is common to all and is not sensitive to the defect state and overall quality of the enamel. Simultaneous radiometric and luminescence frequency scans for the purpose of depth profiling were performed and a quantitative theoretical two-lifetime rate model of dental luminescence was advanced.

Dental Enamel↗
PubMed1997

Denturists: do they really provide more affordable care in Ontario?

The 1996 Denturist Association of Ontario fee guide and the Ontario Dental Association Fee Guide for General Practitioners were examined to identify variations in the fees charged for a range of removable prosthodontic services. Fee guides were selected for this analysis as third-party insurers and government dental plans frequently use them to establish fee schedules and levels of reimbursement. However, it is recognized that dentists set their own fees, which may be higher or lower than the fees suggested in the guide. Although the descriptions of the specific services listed in the guides were similar in many cases, no attempt was made to examine variations in the quality of care provided by dentists and denturists, or the approach to treatment offered by their respective professions. The analysis revealed that a number of procedure fees were, on average, 15 per cent higher in the Ontario Dental Association (ODA) fee guide compared to the denturists' fee guide. However, a wide range of prosthetic services, including partial dentures, were less expensive in the ODA fee guide. Based on this analysis, there appears to be no substantial cost differential between the services provided by dentists and denturists six years after the proclamation of the new Regulated Health Professions Act in Ontario, as the denturists have claimed. The denturist association's further claims of greater choice and improved access may also be questionable, and should be reexamined in light of these findings.

Denture Repair↗
PubMedDate not supplied

Diagnosis of pit and fissure caries using frequency-domain infrared photothermal radiometry and modulated laser luminescence.

Non-intrusive, non-contacting frequency-domain photothermal radiometry (FD-PTR or PTR) and frequency-domain luminescence (FD-LUM or LUM) have been used with 659- and 830-nm laser sources to assess the pits and fissures on the occlusal surfaces of human teeth. Fifty-two human teeth were examined with simultaneous measurements of PTR and LUM and were compared to conventional diagnostic methods including continuous (dc) luminescence (DIAGNOdent), visual inspection and radiographs. To compare each method to the others, sensitivities and specificities were calculated by using histological observations as the gold standard. With the combined criteria of four PTR and LUM signals (two amplitudes and two phases), it was found that the sensitivity of this method was much higher than any of the other methods used in this study, whereas the specificity was comparable to that of dc luminescence diagnostics. Therefore, PTR and LUM, as a combined technique, has the potential to be a reliable tool to diagnose early pit and fissure caries and could provide detailed information about deep lesions. Using the longer wavelength (830-nm) laser source, it has been shown that detection of deeper subsurface lesions than the 659-nm probe provides is possible.

Body Temperature↗