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Biomedical subjects

C F Smith

Publications and source records attributed to C F Smith.

At least 19 recordsLinked to original sources
PubMed1998

Perception of sweetness intensity determines women's hedonic and other perceptual responsiveness to chocolate food.

This study tested 63 women for hedonic and other perceptual responsiveness to a chocolate food. Subjects tasted four chocolate puddings varying in sugar (high and low) and fat (high and low) content and rated them for pleasantness, caloric density, fillingness and flavor intensities. Results emphasised the importance of sweetness intensity in determining women's responses to the chocolate puddings. Women's perception of sweetness intensity was accurate to sugar content and results consistently indicated that their hedonic responses to the chocolate puddings were based on the perceived sweetness. Women's perception of the caloric density of the puddings was based on their perception of the fat content of the puddings; however, interpretation of that finding must be qualified because the subjects' perception of fat content was inaccurate. The women's perception of sweetness intensity accounted for 31% of the variability in fat perception. Women's perception of the intensity of chocolate flavor was also significantly associated with perceived sweetness of the puddings. These data suggest that the women's accurate perception of the sugar content of the chocolate puddings played a primary role in determining their hedonic and other perceptual responses.

Adult↗
PubMed1998

Comparison of the SimPlate total plate count method with Petrifilm, Redigel, conventional pour-plate methods for enumerating aerobic microorganisms in foods.

The SimPlate Total Plate Count (TPC) method, developed by IDEXX Laboratories, Inc., is designed to determine the most probable number of aerobic microorganisms in foods. The 24-h test was compared to the conventional plate count agar (PCA) method, the Petrifilm Aerobic Count plates, and the Redigel Total Count procedure for enumerating microflora in 751 food samples. Results using the SimPlate TPC method were highly correlated (r > or = 0.96) with results from other test methods. Slopes (0.96-0.97) were not significantly different from 1, and y intercepts (-0.03-0.08) were not different from O. The SimPlate has a high counting range (> 1600 most probable number per single dilution), thus requiring fewer dilutions of samples compared to other methods evaluated. Some foods, e.g., raw liver, wheat flour, and nuts, contain enzymes that gave false-positive reactions on SimPlates. Overall, however, the SimPlate TPC method is a suitable alternative to conventional PCA, Petrifilm, and Redigel methods for estimating populations of mesophilic aerobic microorganisms in a wide range of foods.

Aerobiosis↗
PubMed1997

Force output and energy metabolism during neuromuscular electrical stimulation: a 31P-NMR study.

The purpose of this study was to determine the acute physiologic effects of two electrical stimulation protocols commonly used for muscle rehabilitation. Surface electrodes were used to provide 12 stimulations of the calf musculature. In protocol A the duty cycle was fixed at 1:1 (10-second stimulation: 10-second rest); for protocol B it was 1:5 (10-second stimulation: 50-second rest). We continuously recorded isometric plantarflexor force in six healthy male subjects during stimulation using a load cell connected to a foot pedal ergometer. Metabolic changes in the stimulated gastrocnemius muscle were monitored in the supine position using 31P-NMR spectroscopy (Phillips 1.5 tesla NMR machine). Relative changes in phosphocreatine (PCr), inorganic phosphate (Pi), and intracellular pH (pHi) were obtained during stimulation and recovery, using a 1.5 cm RF surface antenna. Over the 12 stimulations, protocol A produced a significantly (p < 0.001), greater force decline (protocol A: 30.4 +/- 1.3%, protocol B: 13 +/- 0.8%); a significantly (p < 0.005), greater increase in Pi/PCr (protocol A: 210%, protocol B: 50%); and a significantly (p <0.001), lower pHi (protocol A: 6.8 +/- 0.16, protocol B: 7.03 +/- 0.12). We conclude that the shorter duty cycle produces more fatigue throughout the stimulation period, possibly as a result of greater intracellular acidosis and reduced availability of the high energy phosphate PCr. The clinical application of this finding relates to the selection of a stimulation protocol that maximizes strength gains in atrophic vs healthy muscle.

Adult↗
PubMed1996

Macular corneal dystrophy in Iceland. A clinical, genealogic, and immunohistochemical study of 28 patients.

BACKGROUND: The frequency of different types of macular corneal dystrophy (MCD) was determined in Iceland where MCD accounts for one third of every penetrating keratoplasty. METHODS: The authors determined the serum levels of antigenic keratan sulfate (aKS) in 27 patients with MCD and 53 unaffected family members by an enzyme-linked immunosorbent assay that uses an anti-KS monoclonal antibody (5-D-4). The authors also stained sections from 37 corneal buttons (including 2 regrafts) from 23 patients with MCD by the avidin-biotin complex method using the same anti-KS monoclonal antibody. RESULTS: Based on the serum analyses, 22 patients had MCD type I and 5 had MCD type II. The corneas from patients without detectable KS in the serum lacked immunohistochemical reactivity to the anti-KS antibody. Every MCD cornea examined from individuals with normal serum KS levels showed KS reactivity. All 53 unaffected siblings and parents carrying the recessive gene had normal serum KS levels. CONCLUSIONS: Macular corneal dystrophy types I (78.6%) and II (21.4%) both occur in Iceland. Members of affected sibships had only one of these types, not both. Nine patients with MCD type I and four persons with MCD type II belonged to a large pedigree in which individuals have been traced as far back as the beginning of the 16th century. The linking of patients with MCD types I and II in an inbred pedigree suggests that both types may be manifestations of the same abnormal gene rather than independent entities. The serum KS levels were not helpful in detecting heterozygous MCD carriers.

Adolescent↗
PubMed1995

Arthroscopic shoulder surgery with three different laser systems: an evaluation of laser applications.

Twelve cadaveric shoulder arthroscopies were performed to evaluate the use of lasers as an adjunctive tool in arthroscopic shoulder surgery. The three most common lasers historically used in orthopedic surgery were examined: Holmium:YAG, Neodymium:YAG, and the CO2. The following parameters were evaluated for each laser system: (1) ease of use of the laser system and handpiece; (2) ability to excise and trim bursae, synovium, ligament, tendon, bone, and articular cartilage; and (3) ability to contract ligaments and capsule by heat transfer. None of these lasers efficiently cut bone, whereas all three systems readily debrided the soft tissues around the shoulder. The free-beam Ho:YAG and CO2 systems heat contracted soft tissues with more control than the contact Nd:YAG. The fiberoptic delivery system of the Neodymium:YAG and Holmium:YAG laser performed well in the saline arthroscopy, and the CO2 delivery system was cumbersome. Overall, the CO2 system removed tissue better than the others, but its difficult use favored the Holmium laser as the best overall current laser system for shoulder arthroscopy.

Aluminum Silicates↗
PubMed1995

In vitro analysis of laser meniscectomy.

Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air.

Adult↗
PubMed1995

A spectrophotometer analysis of light absorption in the human meniscus.

The spectrophotometer analysis of light absorption curves in human meniscal tissue showed a reproducible series of graphs for varying tissue thickness, age, zone, and sectioning plane. These data show water as the essential reason for light absorption in the infrared portion of the light spectrum. The excimer laser in the ultraviolet region, and wavelengths around 2000 nm in the infrared region, appeared to provide the best wavelength match for laser energy transfer and the cutting or ablating of meniscal tissue. On-going research into clinical applications should focus on these wavelengths.

Absorption↗
PubMed1995

The biological effects of carbon dioxide laser surgery on rabbit articular cartilage.

A pulsed carbon dioxide laser made predetermined superficial and deep (subchondral) lesions through arthrotomies on the femoral condyles of adult New Zealand rabbits. Twenty rabbits, including controls, were divided into acute, 1-, 3-, 6-, and 12-month sacrifice groups. Early sacrifice groups showed some fibrous ingrowth from the deep lesions, but not the superficial lesions, and this was not seen in the 6- or 12-month groups. Cells below and adjacent to the laser lesions appeared viable when compared with controls. In each group studied, no histologic evidence of healing or fibrous covering in the superficial or deep laser lesions was found. No adverse clinical effects (synovitis, infection) were found in the laser groups, and the laser permitted excellent depth control during vaporization. However, the authors caution against irradiating articular cartilage.

Animals↗
PubMed1994

The effects of the neodymium laser on meniscal repair in the avascular zone of the meniscus.

Thirty mature New Zealand white rabbits were divided into four surgical groups, and a 3- to 4-mm incision was made in the inner avascular zone of the central third of the medial meniscus. In group I, the tear was not treated by lasering or suturing. In group II, the tear was sutured. Group III was given four different doses of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation with no suturing. Group IV underwent meniscal suturing followed by the same four different laser irradiation doses. The animals were killed at 2, 4, and 6 weeks, with gross and histologic evaluation of the healing responses by group and time. The overall results showed no healing of this meniscal tear in the avascular zone. Suturing generally showed increased cellular infiltration. The varying doses of the Nd:YAG lasing demonstrated no gradient effect, and no "welding" of menisci was noted. The maximum cellular inflammatory response was noted in the sutured and lased menisci, reinforcing the importance of a stable meniscal environment for healing meniscal tears.

Animals↗
PubMed1994

Communicable hysteria?

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Acquired Immunodeficiency Syndrome↗
PubMed1993

Synthesis and structure-activity relationships of some 6 beta-acrylamido penicillins.

Syntheses are described for penicillins (4b approximately 4i, 5a and 5b) which possess a 6 beta-(2-heteroaryl-3-substituted)-propenamido side-chain of fixed geometry. In vitro results for these compounds against a range of Gram-positive and Gram-negative bacteria showed in most cases good stability against both penicillinase and TEM-1 beta-lactamase; analogues (4b approximately 4i) bearing a 2-(2-aminothiazol-4-yl) unit showed the best intrinsic activity, the cyclohexyl compound (4b) being the most promising. The 1-acetoxyethyl ester (6) of 4b was also prepared; in experimental animal studies the in vivo properties of this compound compared favourably with cefuroxime axetil and are reported together with selected in vivo data for the other compounds.

Animals↗
PubMed1992

Selectivity profile of the alpha 2-adrenoceptor antagonist efaroxan in relation to plasma glucose and insulin levels in the rat.

The effects of efaroxan (RX 821037A; 2-[2-(2-ethyl-2,3-dihydrobenzofuranyl)]-2-imidazoline HCl) at alpha 1- and alpha 2-adrenoceptors were investigated in isolated tissues, pithed rats and conscious rats. In isolated tissues, efaroxan competitively antagonised the inhibitory effects of p-aminoclonidine in the electrically stimulated (0.1 Hz) rat vas deferens, (pA2 = 8.89) and the contractile effects of phenylephrine on the rat anococcygeus muscle (pA2 = 6.03). Efaroxan had a selectivity ratio (alpha 2/alpha 1) of 724 compared to a value of 182 for idazoxan. In pithed rats, the i.v. doses of efaroxan (mumol/kg) producing 2-fold shifts in dose-response curves for UK-14,304 at prejunctional cardiac alpha 2-adrenoceptors and postjunctional vascular alpha 2-adrenoceptors, and for cirazoline at postjunctional vascular alpha 1-adrenoceptors, were 0.05, 0.13 and 2.96, respectively. In conscious fasted rats, prazosin (5 mg/kg p.o.) increased resting glucose levels and exacerbated the hyperglycaemic effects of UK-14,304 and adrenaline. In contrast, efaroxan (1-5 mg/kg p.o.) had little effect on resting plasma glucose but markedly antagonised the hyperglycaemic actions of UK-14,304 and adrenaline. Efaroxan increased resting plasma insulin levels and markedly potentiated the rise in insulin levels produced by adrenaline; this latter effect was prevented by the co-administration of propranolol. These results demonstrate that efaroxan is a potent and selective alpha 2-adrenoceptor antagonist and provide further support for the involvement of alpha 2-adrenoceptors in glucose homeostasis.

Adrenergic alpha-Antagonists↗
PubMed1991

Synthesis and biological evaluation of 14-alkoxymorphinans, V: 6-Deoxyocyprodime, an opioid antagonist with decreased mu receptor selectivity in comparison to cyprodime.

N-Cyclopropylmethyl-4,14-dimethoxymorphinan (4) and N-cyclopropylmethyl-4-hydroxy-14-methoxymorphinan (5) have been prepared from cyprodime (1) by Wolff-Kishner reduction. Pharmacological studies (mouse vas deferens and guinea pig ileum preparations) revealed that there was no significant decrease of 4 in antagonist activity but in mu selectivity when compared with 1. The phenol 5 showed partial agonism at mu, kappa and delta receptors.

Animals↗
PubMed1991

(-)-N,N'-but-2-ene-1,4-diylbimorphinans.

N,N'-But-2-ene-1,4-diylbimorphinans 1-3 have been synthesized and pharmacologically evaluated. Bimorphinans 1 and 3 show opioid antagonist activity and preference for mu and kappa opioid receptors in mouse vas deferens and guinea pig ileum preparations.

Animals↗