Biomedical subjects
S R Lee
Publications and source records attributed to S R Lee.
Magnesium toxicity: bone lesions.
Broiler chicks fed corn-soy rations supplemented with toxic levels of magnesium from one day of age grew poorly, developed diarrhea, and exhibited characteristic skeletal abnormalities. Tibiae from magnesium intoxicated chicks were shortened, thickened, and bowed. Percent tibial ash was greatly reduced. Upon microscopic examination, the bone lesion appeared rachitic as evidenced by widened and lengthened growth plates, excessive osteoid seams on endochandral bone, and osteoid or bone capped metaphyseal blood vessels with very few associated osteoblasts. Tibial calcium to phosphorus mass ratios decreased while tibial magnesium to phosphorus mass ratios increased concomitantly with increased dietary magnesium. Calcium and phosphorus homeostasis was possibly affected as evidenced by a general decrease in size and cellularity of parathyroid glands and a general increase in size and cellularity of ultimobranchial glands.
Isoenzymes of elapid acetylcholinesterases.
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Emergency department staffing to improve patient management.
The emergency department records at the St. Louis County Hospital were reviewed for 1973, 1974, and 1975. The distribution of patients was considered by the day of the week and hour of the day. For the three year period, the daily average showed that one third of patients had been seen by 2:36 pm and two thirds by 8:14 pm. An analysis of peak patient load showed the first peak was around 11:00 am and the second, a higher peak, around 7:00 pm. By day of the week, more patients were seen on Tuesday and Saturday. Using data from such an analysis, emergency department personnel can devise an appropriate staffing pattern for their own situation.
[Handling pitfalls (author's transl)].
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Declining value of alanine aminotransferase in screening of blood donors to prevent posttransfusion hepatitis B and C virus infection. The Retrovirus Epidemiology Donor Study.
BACKGROUND: Since the mid-1980s, blood banks in the United States have screened donors for elevated alanine aminotransferase (ALT) in an effort to prevent posttransfusion hepatitis. The present study was designed to quantitate the residual value of ALT screening following the implementation of hepatitis C virus (HCV) assays. STUDY DESIGN AND METHODS: Two approaches were used. First, a database of 2.3 million donations made by 586,507 volunteer blood donors between 1991 and 1993 was used to compare the incidence of seroconversion to hepatitis B virus (HBV) and HCV marker positivity in donors with elevated ALT values and with normal ALT values. Second, the duration of ALT elevation prior to HBV and HCV seroconversion was determined from 34 well-documented cases of posttransfusion HBV and HCV; elevated-ALT window periods were multiplied by rates of HBV and HCV incidence in donors to project the yield of ALT screening. Predictive value and cost-effectiveness analyses were also performed to compare the value of ALT screening before and after HCV screening was implemented. RESULTS: Both approaches indicate that ALT testing does not detect HBV in the window phase but does currently identify approximately 3 HCV window-phase donations per 1 million donations; this contrasts with ALT detection of approximately 1800 HCV-infectious units per 1 million donations prior to anti-HCV screening. Currently, only 8 in 10,000 donated units with elevated ALT (negative anti-HCV) are infected with HCV. The cost of continued ALT screening was estimated at $7,931,000 per quality-adjusted year of life saved. CONCLUSION: The yield, predictive value, and cost-effectiveness of ALT screening of blood donors have declined dramatically with the implementation of progressively improved anti-HCV assays. ALT screening of volunteer blood donors should be discontinued.
Dental caries and salivary immunoglobulin A in Down syndrome children.
OBJECTIVES: This study investigated the relationship between dental caries and the salivary Streptococcus mutans specific antibodies in Down syndrome children. METHODS: Nineteen children with Down syndrome and 41 normal children aged 8-17 years were selected. The oral health status (dental caries experience, pit and fissure depth, dental arch space, and Simplified Oral Hygiene Index) was examined and unstimulated saliva was collected. The total salivary immunoglobulin A (IgA) and S. mutans specific salivary IgA concentrations were measured using ELISA. RESULTS: The decayed and filled surface index of the deciduous teeth, and the decayed, missing, and filled surfaces index of the permanent teeth in Down syndrome children were significantly lower compared to those in normal children. The salivary S. mutans (serotype g and c) specific IgA concentrations were significantly higher in Down syndrome children than in the normal children. There was no significant difference in the tooth characteristics and oral hygiene between the two groups. CONCLUSIONS: The low caries prevalence in Down syndrome children appears to be due to immune protection caused by the elevated salivary S. mutans specific IgA concentrations.
Forskolin stimulates cyclic AMP synthesis, lowers intraocular pressure and increases outflow facility in rabbits.
The intracellular pathway by which beta-adrenergic agonists and antagonists affect aqueous humor dynamics involves the intracellular mediator, cyclic AMP. We have therefore tested the activity of forskolin, a direct activator of adenylate cyclase, in rabbits. Following a 15 min in vitro incubation in the presence of forskolin (15 microM) and isobutylmethylxanthine, a 10 fold increase in cyclic AMP was found in both rabbit iris-ciliary body and scleral-trabecular rings relative to controls. Following an intracameral injection of forskolin (10 micrograms) a time-dependent decrease in intraocular pressure was observed, which reached a mean decrease of 5 mm Hg at 4 hr in unanesthetized rabbits. Outflow facility was measured in anesthetized rabbits by constant pressure perfusion before injection and 1 hr after injection of either forskolin (10 micrograms) or control vehicle. Forskolin caused an approximate doubling of outflow facility (0.41 microliter/min/mm Hg) compared to the preinjection mean value. Control vehicle, ethyl alcohol, caused a statistically insignificant increase in outflow facility. At this concentration of forskolin, the integrity of the blood-aqueous barrier was normal as measured by protein and fluorescein entry into the aqueous humor. These results indicate that agents which directly activate adenylate cyclase are effective at increasing outflow facility and decreasing IOP.
A simple procedure for preparing and staining undecalcified sections of avian growth plate and metaphysis.
This report describes an inexpensive, rapid technique for preparing 4-micron-thick undecalcified sections of avian growth plate and metaphysis using paraffin embedment, rotary microtomes, and disposable knives. Sections were stained by von Kossa's technique with a hematoxylin-and-eosin counterstain.
Experimental rickets in broilers: gross, microscopic, and radiographic lesions. II. Calcium deficiency.
Day-old broiler chicks were fed a calcium-deficient diet for 30 days. Gross, microscopic, and radiographic examinations of the proximal tibiotarsus were done at 2, 3, and 4 weeks of age. In 2-week-old chicks, the growth-plate proliferating-prehypertrophied zone (P-PHZ) was variably lengthened and disorganized, cartilage columns of the degenerating hypertrophied zone and metaphyseal primary spongiosa were shortened, and bone spicules of the secondary spongiosa were bordered by increased osteoid. In 3-week-old chicks, lesions were either similar or more pronounced, with the additional finding of metaphyseal peritrabecular fibrosis. In 4-week-old chicks, the P-PHZ decreased in relative length, osteoid seams and fibrous connective tissue were less prominent, and tibial dyschondroplasia-like lesions were present. Results demonstrated that dietary calcium deficiency produced rachitic lesions, that the lesions were very different from those of phosphorus deficiency or calcium excess, and that the lesions were variable over time.
Experimental rickets in broilers: gross, microscopic, and radiographic lesions. III. Vitamin D deficiency.
Day-old broiler chicks were fed a vitamin D-deficient diet for 30 days. Gross, microscopic, and radiographic examinations of the proximal tibiotarsus were done at 2, 3, and 4 weeks of age. In 2-week-old chicks, there was variable lengthening and disorganization of the proliferating-prehypertrophied zone (P-PHZ), resorption of cartilage spicules in the degenerating hypertrophied zone and primary spongiosa, and lengthening of bone spicules in the secondary spongiosa; many bone surfaces were lined with increased osteoid. In 3-week-old chicks, there was a tendency for the P-PHZ to decrease in relative length and for cartilage spicules to increase in length. In 4-week-old chicks, however, there was marked lengthening of the P-PHZ, resorption of cartilage spicules, and replacement of the metaphysis with irregularly oriented islands of woven bone, osteoid, and loose fibrous connective tissue.
Experimental rickets in broilers: gross, microscopic, and radiographic lesions. I. Phosphorus deficiency and calcium excess.
Day-old broiler chicks were fed diets high in calcium or low in phosphorus for 30 days. Chicks in both groups had similar gross, microscopic, and radiographic lesions. At 2 weeks, the growth-plate degenerating hypertrophied zone (DHZ) and metaphyseal primary spongiosa were lengthened and decreased in radiopacity. Metaphyseal vessels extended to the growth-plate hypertrophied zone (HZ), and osteoid seams were widened. At 3 and 4 weeks, lesions were similar; however, folding fractures were common and cartilage columns of the metaphysis were thinned and replaced with increased woven bone.