Search PubMed⌕ Search

Biomedical subjects

R E Christensen

Publications and source records attributed to R E Christensen.

At least 19 recordsLinked to original sources
PubMed1999

Daily boron intake from the American diet.

Interest in boron as a naturally occurring trace element nutrient from the food supply is increasing. Mounting evidence suggests that boron is essential to human beings. This study explores the major food and beverage contributors of boron and estimates of daily boron intake from the American diet. Previous estimates in the literature of dietary boron consumption are based on limited foods and population segments. In this study we provide a more comprehensive assessment of boron consumption by the US population. A boron nutrient database of 1,944 individual foods was developed. These foods represent 95.3% by weight of all foods consumed in the US Department of Agriculture 1989-1991 Continuing Survey of Food Intakes by Individuals (1989-1991 CSFII). The Boron Nutrient Database (version 1.0) was then linked to the 3-day food records of 11,009 respondents to the 1989-1991 CSFII to generate the average daily boron intake for each person. The weighted 5th percentile, median, mean, and 95th percentile boron intakes, respectively, are 0.43, 1.02, 1.17 and 2.42 mg/day for men; 0.33, 0.83, 0.96 and 1.94 mg/day for women; and 0.40, 0.86, 1.01 and 2.18 mg/day for pregnant women. For vegetarian adults, these intakes are 0.46, 1.30, 1.47 and 2.74 mg/day for men and 0.33, 1.00, 1.29 and 4.18 mg/day for women. The top 2 boron contributors, coffee and milk, are low in boron, yet they make up 12% of the total boron intake by virtue of the volume consumed. Among the top 50 boron contributors, peanut butter, wine, raisins, peanuts, and other nuts are high in boron. As more data become available on daily boron requirements, the results of this study may be used to assess whether Americans' daily intake of boron is adequate.

Animals↗
PubMed1995

A retrospective study of eye disease among first grade children in Los Angeles.

BACKGROUND: The prevalence of ocular disease among children in one school district in Los Angeles, California was studied to better understand the types of eye disorders among this population as well as to develop appropriate preventive programs. METHODS: A computer-assisted retrospective analysis of date was performed from charts of 2,204 first grade children examined in the UCLA Mobile Eye Clinic. RESULTS: One or more ocular disorders were observed in 22.3 percent of the subjects. Uncorrected best monocular visual acuity was 20/40 or worse in 3.4 percent of the children. Refractive errors were diagnosed in 15.7 percent of the subjects, astigmatism in 7.6 percent, hyperopia in 6.2 percent, and myopia in 6.0 percent. Color vision deficiencies (red-green) were found in 2.6 percent of boys. The prevalences of heterophorias and heterotropias were 1.2 percent and 1.3 percent, respectively. CONCLUSIONS: The variety of ocular disorders diagnosed in this demographic setting attests to the importance of performing early and effective screening eye examinations for children.

Child↗
PubMed1993

Keratinocyte expression of calprotectin in oral inflammatory mucosal diseases.

Oral mucosal inflammation evolves in response to microbial pathogens and non-infectious antigens which activate humoral and cell-mediated immunologic processes. Most of these disease processes invoke a leukocyte response culminating in cellular infiltration of the submucosa and, to some degree, transmigration into the epithelium itself. Calprotectin, a leukocyte-derived dimeric protein complex that has potent antibacterial and antifungal effects, has recently been identified in skin and mucosal keratinocytes implying that epithelium may biochemically contribute to the overall mechanism of host defense. In this study, the upregulation of calprotectin as assessed immunohistochemically is pursued for oral diseases of immunopathologic, fungal and viral origin. In lichen planus, candidiasis, herpes virus stomatitis, and oral hairy leukoplakia, calprotectin was found to be expressed to a significantly higher level than in normal control mucosal samples.

Antigens, Surface↗
PubMed1992

The distribution of the antimicrobial protein, calprotectin, in normal oral keratinocytes.

Calprotectin is a heterodimeric peptide isolated from neutrophil cytosol that exhibits profound antimicrobial effects. Using monoclonal antibody MAC 387, calprotectin was found to be expressed in oral keratinocytes from normal, non-inflamed oral mucosa. Orthokeratinized sites including the attached gingiva and hard palate expressed low levels of calprotectin with a restricted pattern; immunoreactants were identified only within subcorneal keratinocytes. Parakeratinized mucosa from the lips, soft palate, tongue and buccal mucosa expressed calprotectin in a more widespread, yet variable pattern, immunoreactants being detectable in only a portion of the spinous layer in some cases whereas in others the pattern of expression was more topographically diffuse. Antigen was not detected in basilar and lower strata cells. Both cytoplasmic and nuclear decoration could be identified. The results indicate that oral mucosa harbours an antimicrobial deterrent to micro-organisms that may enhance the physical epithelial barrier of host defence.

Antigens, Surface↗
PubMed1992

Results of inpatient and outpatient cataract surgery. A historical cohort comparison.

PURPOSE: The transition from inpatient to outpatient cataract surgery during the last decade was not accompanied by prospective investigation of its effect on visual outcomes or surgical complications. The authors performed this study to assess the impact of this transition on surgical results. METHODS: The authors reviewed 600 extracapsular cataract extractions performed by 4 experienced ophthalmic surgeons during a 36-month period; in 300 cases, patients were hospitalized after surgery (inpatient group), and, in 300 cases, patients were never hospitalized (outpatient group). The same surgical techniques were used in all cases. Visual outcome and rates for operative and postoperative complications were compared. RESULTS: There were no statistically significant differences between the inpatient and outpatient groups for visual acuity. Excluding patients with pre-existing nonlenticular ocular disease, a best-corrected visual acuity of 20/40 or better was achieved in 93.1% of inpatient cases and in 97.2% of outpatient cases 6 months after surgery. Postoperative, clinically apparent cystoid macular edema was more common in the inpatient group (P = 0.03); however, after exclusion of patients with diabetes, hypertension, age younger than 65 years, and eyes with pre-existing nonlenticular disease, there was no statistically significant difference between groups. No significant differences in rates for other operative and postoperative complications were identified, including wound dehiscence, unplanned postoperative filtering blebs, infectious endophthalmitis, retinal detachment, persistent iridocyclitis, glaucoma, and corneal edema. CONCLUSION: This study does not demonstrate that the transition to outpatient cataract extractions has had an adverse effect on surgical outcomes.

Aged↗
PubMed1991

The effects of Nd:YAG laser iridotomy on the corneal endothelium.

We studied 18 eyes of 18 patients undergoing Nd:YAG laser peripheral iridotomy for occludable anterior chamber angles. A Q-switched laser was used for all treatments. Preoperative and postoperative pachymetry and corneal endothelial cell counts were obtained centrally, in the nontreated superonasal quadrant, and in the treated superotemporal quadrant. No significant differences were found between preoperative and postoperative corneal thickness at any site. A small decrease in endothelial cell count (95 cells/mm2) at the treated site was statistically significant (P = .04).

Cell Count↗
PubMed1990

Biometric variables in patients with occludable anterior chamber angles.

Biometric studies of the ocular dimensions in eyes with narrow anterior chamber angles provide insight into the pathophysiology of pupillary block and may show which eyes are more prone to develop angle-closure glaucoma. We reviewed the records of 56 patients with occludable angles examined between 1980 and 1984. Initial biometric data obtained on the patients included corneal diameter, anterior chamber depth, lens thickness, and ocular axial length. The average length of follow-up was five years. Of 54 patients with complete clinical records, 20 (37%) eventually required peripheral iridectomy after a mean duration of 16 months from the initial examination. Cox's survival analysis showed a strong correlation between shortened duration to peripheral iridectomy and increasing lens thickness/ocular axial length ratio factor (P = .03). No other variables were significantly related to outcome. This suggests that the lens thickness/ocular axial length ratio may be useful as a predictor of clinical outcome in narrow-angle glaucoma.

Anterior Chamber↗
PubMed1990

Glaucoma in patients with uveitis.

The records of 100 patients (161 eyes) with uveitis were reviewed retrospectively to determine the prevalence of increased intraocular pressure, the forms of uveitis most commonly associated with glaucoma, and the forms that require specific glaucoma therapy. Secondary glaucoma was present in 23 patients (31 eyes): three of 24 patients with acute uveitis (three eyes, 12% of acute uveitis patients) and 20 of 76 patients with chronic uveitis (28 eyes, 26% of chronic uveitis patients). Eighteen patients (26 eyes, 78% of glaucoma patients) with chronic uveitis required long-term medical therapy to control intraocular pressure. Three patients (three eyes, 12% of glaucoma patients) with acute uveitis required short-term therapy to control intraocular pressure. The remaining two patients had transient increases in intraocular pressure that did not require treatment or that responded to treatment of intraocular inflammation alone. One patient with chronic uveitis (two eyes, 4% of glaucoma patients) required filtering surgery. At least five patients (eight eyes, 22% of glaucoma patients) had glaucomatous visual field defects. The results of this survey are consistent with the concept that secondary glaucoma is a management problem in patients with anterior segment inflammation and chronic rather than acute uveitis. An algorithm for the management of increased intraocular pressure in patients with uveitis is proposed.

Acute Disease↗
PubMed1989

A clinical evaluation of the BioPen.

We conducted a clinical trial on the Oculab BioPen, a portable, handheld applanation instrument designed to measure ocular axial lengths. We compared the measurements obtained from the BioPen with those obtained from the Ultrascan Digital B System IV from CooperVision. Accuracy and reproducibility were assessed in vitro by performing ten measurements with each instrument on a precalibrated 25.8-mm plastic test block. The in vivo reproducibility of the BioPen was evaluated by performing five serial readings on each eye of 58 patients. Keratometry measurements were also recorded to determine whether the BioPen provided consistent readings regardless of corneal curvature. We found the BioPen to be as accurate and reproducible as the Ultrascan Digital B in vitro and in vivo. Corneal curvature had no effect on the in vivo reproducibility of the BioPen.

Clinical Trials as Topic↗
PubMed1989

Effect of DMBA on oral cancer development in hamsters with latent HSV-1 infections in trigeminal ganglia.

This study examined the effect of 7, 12-dimethyl-benz(a)anthracene (DMBA), polycyclic aromatic hydrocarbon carcinogen, on pathologic changes in buccal pouch mucosa of hamsters with latent herpes simplex virus type 1 (HSV-1) infections in their trigeminal ganglia. Of the pouches receiving DMBA treatment, the average number of tumors per pouch was significantly higher (p less than 0.01) in pouches of animals with HSV-1 infections as compared to those that received DMBA only. Of the pouches receiving DMBA, the average cumulative tumor diameter (the sum of the tumor diameters in each group divided by the number of pouches in that group) was notably greater in animals with latent HSV-1 than in animals that had not been infected; however, this difference was not significant. The DMBA-treated hamsters that had latent infections also displayed a higher severity and prevalence of histopathologic changes in their pouch mucosa. This study indicates that latent HSV-1 and DMBA show synergism in the development of tumors and precancerous histopathologic changes in hamster buccal pouch mucosa. An unexpected finding was that among the HSV-1 infected animals, 95% of the ganglia from animals treated with DMBA showed latent HSV-1 virus on explanation culture, whereas only 10% of the ganglia from infected animals that received mineral oil, rather than DMBA, contained latent virus.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Effects of argon laser iridotomy on the corneal endothelium.

We studied 14 eyes of 14 patients undergoing argon laser peripheral iridotomy for occludable (narrow) anterior chamber angles. Preoperative and postoperative pachymetry and corneal endothelial cell counts by specular microscopy were obtained centrally and in both the treated and nontreated superior quadrants. No significant differences were found between preoperative and postoperative measurements of corneal thickness and endothelial cell counts in any area.

Argon↗
PubMed1987

Glomangiosarcoma with metastasis to the maxilla.

A thorough review of the literature disclosed very little information on glomangiosarcoma with no reported cases of verified metastases. We present a case which may be the first instance of oral metastatic glomangiosarcoma to be reported in the literature.

Adult↗
PubMed1986

The electroretinogram in advanced open-angle glaucoma.

Fourteen patients with advanced open-angle glaucoma were evaluated prospectively by electroretinography and the results were compared with normal controls who were matched for age and sex. All glaucoma patients had visual acuity of 20/50 or better, cup-to-disc ratios of 0.7 or greater in at least one eye, and visual field loss consistent with advanced glaucoma. Numerous electroretinographic parameters were significantly abnormal when compared with the control group.

Adult↗
PubMed1985

Inhibition of the epinephrine-induced reduction of intraocular pressure by systemic indomethacin in humans.

In a prospective, randomized, double-masked study, 2% epinephrine applied topically twice each day for two weeks to the eyes of patients with glaucoma or ocular hypertension caused an 8.1 +/- 1.4-mm Hg (mean +/- S.E.M.) reduction of intraocular pressure in placebo-treated patients, but only a 1.9 +/- 0.6-mm Hg decrease in patients treated with 25 mg of orally administered indomethacin four times each day (P less than .0005). Systemic treatment with indomethacin for one week did not significantly increase intraocular pressure by itself (baseline, 19.7 +/- 0.6 mm Hg, vs 20.1 +/- 1.4 mm Hg after indomethacin treatment). When indomethacin treatment was discontinued in those patients receiving topical epinephrine, there was a further significant (P less than .05) reduction in intraocular pressure compared with the placebo-treated group. Since the ocular hypotensive effect of topically applied epinephrine is inhibited by indomethacin, a cyclo-oxygenase inhibitor, these results suggest that this reduction of intraocular pressure is at least partially mediated by the endogenous production of prostaglandins, or other cyclo-oxygenase products, and that the intraocular pressure of glaucoma patients undergoing epinephrine therapy may increase when systemic cyclo-oxygenase inhibitors such as indomethacin or aspirin are taken.

Administration, Oral↗