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Biomedical subjects

R L Anderson

Publications and source records attributed to R L Anderson.

At least 559 records · Page 31Linked to original sources
PubMed1966

Metabolism of D-mannose in Aerobacter aerogenes: evidence for a cyclic pathway.

Kamel, M. Y. (Michigan State University, East Lansing), and R. L. Anderson. Metabolism of d-mannose in Aerobacter aerogenes: evidence for a cyclic pathway. J. Bacteriol. 92:1689-1697. 1966.-Evidence is presented which suggests a cyclic pathway for the constitutive utilization of d-mannose in extracts of Aerobacter aerogenes PRL-R3. d-Mannose is phosphorylated with d-glucose-6-phosphate to yield d-mannose-6-phosphate and d-glucose. d-Glucose-6-phosphate may be regenerated by isomerization of d-mannose-6-phosphate through d-fructose-6-phosphate, or by phosphorylation of d-glucose with adenosine-5'-triphosphate. The pathway involves the participation of four constitutive enzymes: d-glucose-6-phosphate isomerase, d-mannose-6-phosphate isomerase, a stereospecific d-glucokinase, and a phosphotransferase which phosphorylates d-mannose with d-glucose-6-phosphate, acetyl phosphate, or carbamyl phosphate. The absence of d-mannokinase (adenosine-5'-triphosphate:d-mannose phosphotransferase) activity in extracts of this organism suggests that the pathway may be of functional significance. Also, the pathway accounts for an apparent 2-epimerization of d-mannose to d-glucose that was observed in extracts.

Adenosine Triphosphate↗
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Methodological advances and plans for improving regulatory success for confirmatory studies.

Regulatory success for new medical products requires convincing statistical results from planned analyses for relevant and reliable data from well-designed clinical studies. Statistical methodology has a critical role for such success through strengthening the robustness of study findings to sources of bias, variability and spurious events. Areas of particular importance for statistical methodology include the structure for study design, the schedule and procedures for data collection, and plans for primary data analyses. This paper discusses some challenging statistical issues for these areas and suggests potential strategies for addressing them. The objective of these strategies as well as other methodological advances is the minimization of ambiguity in the findings of confirmatory studies. In this way, their effective use can enhance regulatory success.

Bias↗
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Sonographic demonstration of fetal sacrococcygeal teratoma.

Six cases of sonographically diagnosed fetal sacrococcygeal teratoma (SCT) are presented and illustrate the variable features of fetal SCT. The sonographic findings assisted the parents and perinatal team in making decisions, and in two of the cases the children survived after elective Cesarean section and prompt neonatal resection of the tumors. None of the patients showed signs of malignant degeneration of the teratoma or metastases. Fetal SCT no longer should be considered a uniformly fatal condition. The literature on sacrococcygeal teratoma detected after birth indicates that the mortality rate is correlated with the degree of extension of the tumor. Therefore, the classification of sonographically diagnosed fetal SCT according to its size and position is important for decisions regarding pregnancy management.

Adult↗
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Skin flaps in periorbital reconstruction.

Soft tissue defects of the periorbital region are best repaired with local skin or skin-muscle flaps. Flaps have functional and aesthetic advantages over skin grafts in that they provide a better color and texture match to the thick periorbital skin. The general physiological and biomechanical principles of skin flap survival and orientation are discussed with modification according to peculiarities of the periorbital area. The four basic groups of skin flaps are the sliding flap, advancement flap, rotation flap, and transposition flap. Selected standard and modified designs of each group are illustrated, and each surgical technique is described in stepwise fashion. The specific applications of the flaps to periorbital reconstruction are emphasized. The indications for use of various skin flaps, the local factors involved in flap selection, and proper preoperative planning are also discussed.

Biomechanical Phenomena↗
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Essential blepharospasm and related dystonias.

Essential blepharospasm is an idiopathic disorder of progressive involuntary spasms of the orbicularis oculi and upper facial (corrugator, procerus) muscles. Blepharospasm literally means spasm of the eyelids; however, most patients with blepharospasm also have or will develop squeezing in the lower face and neck muscles (Meige's syndrome, orofacial dystonia, or oromandibular dystonia). Some patients develop dystonic, uncontrolled movements in areas outside the facial nerve distribution (segmental cranial dystonia or craniocervical dystonia). Chronic, forceful squeezing by the periocular muscles becomes debilitating for the patient and leads to functional and cosmetic eyelid deformities. Treatment has included a variety of modalities and oral medications that are of limited efficacy. Botulinum-A toxin injections have delivered the best temporary relief from this disorder, while the periorbital myectomy operation has been shown to give the best long-term results.

Blepharospasm↗
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Some changes in gastro-intestinal metabolism and in the urine and bladders of rats in response to sodium saccharin ingestion.

In rats fed sodium saccharin in the diet changes in urine composition, increased bladder-tissue mass and, in males only, an accumulation of minerals in the bladder tissue have been observed. In this report evidence is presented that indicates that these changes are a consequence of the effects of sodium saccharin in the gastro-intestinal tract and are not due to systemic sodium saccharin. Sodium saccharin has been shown to inhibit gastro-intestinal enzymes that digest carbohydrates and proteins and to increase caecal absorption of mineral ions. The significance of these findings to saccharin-associated bladder tumorigenesis is discussed.

Animals↗
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The effects of high dietary levels of sodium saccharin on mineral and water balance and related parameters in rats.

The effects of sodium saccharin (NaS) treatment on mineral and water balance and a number of related parameters were studied over a 10-day period in 7-month-old Charles River CD rats. Eight groups of 10 male and 10 female rats were studied. In four of the groups the rats were the F1 offspring of rats that had been exposed to NaS at 1, 3, 5 or 7.5% in the diet and the offspring were treated with the same dietary levels of NaS as their parents. Prior treatment in two other groups was modified in order to evaluate the role of in utero exposure to NaS on the study parameters: rats in one group were only exposed in utero via dams fed diets containing 5% NaS while treatment in the other group did not include in utero exposure, but was started at birth via dams fed diets containing NaS and continued at a dietary concentration of 5% NaS. Second-generation rats in another group were fed diets containing 5% sodium hippurate (NaH), a compound with a number of physical and chemical properties similar to those of NaS; this group was included in order to evaluate the specificity of NaS and/or the effect of sodium on the study parameters. A group of untreated rats served as controls. Treatment-related effects were observed in most study parameters. In addition, a number of differences between male and female rats in baseline values and/or in response to NaS administration were observed. With increasing dietary levels of NaS body weights decreased, but there were increases in water consumption, faecal water content, and caecal weights. NaS treatment resulted in increased urine volume and decreased urine osmolality, changes in urine mineral concentrations (increased sodium, decreased potassium and zinc) and increases in fresh and dry bladder weights, bladder-tissue hydration, and mineral concentrations (sodium, potassium, magnesium and zinc) in bladder tissue. The parameters in which clear sex-related differences in baseline values were observed were body weight, food and water consumption, urine volume, urine osmolality, fresh bladder mass, bladder-tissue hydration and the concentrations of sodium, potassium, magnesium and zinc in the bladder tissue. With the exception of urine osmolality, the values were higher in females. Differences between males and females in response to treatment were observed for NaS consumption (increased in females), caecal weight (increased in females), NaS concentration in the urine (increased in males), and the concentration of sodium, potassium, magnesium and zinc in the bladder tissue (increased in males).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
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Comparison of the responses of male rats to dietary sodium saccharin exposure initiated during nursing with responses to exposure initiated at weaning.

In an attempt to define the role of exposure to sodium saccharin (NaS) during early life on the subsequent development of bladder tumours, we compared the responses of male rat pups to exposure to 5% dietary NaS initiated at parturition with those to exposure initiated at weaning. We also compared the effects of exposure from parturition to NaS given in a low-carbohydrate (L-CHO) diet with those of NaS in rat chow. NaS ingestion by the dam was associated with low saccharin concentrations in the pups' urine and had no effect on the caecal or bladder mass in the suckling pups. In the 10 wk after weaning, the rats ingesting NaS in chow showed decreased weight gain and increases in feed consumption, mass of caecal contents and tissue, urine output, bladder mass, relative water consumption (g water consumed/g feed consumed) and bladder hyperplasia. Except for bladder hyperplasia these effects were generally greater in the rats exposed to NaS from parturition than in those exposed only from weaning. The animals exposed to NaS in the L-CHO diet had the highest level of urinary saccharin but showed no bladder hyperplasia. The significance of these findings to the role of pre-weaning saccharin exposure in bladder tumorigenesis is discussed, and it is concluded that the effects on urinary parameters and the bladders of rats exposed to NaS during suckling and weaning may be secondary to the effects of NaS on the gastro-intestinal tract.

Animals↗
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Inhibition of the serosal sugar carrier in isolated intestinal epithelial cells by saccharin.

Isolated intestinal cells accumulate certain monosaccharides via an Na+-dependent, active transport system localized in the brush-border membrane, and release sugar molecules at the basolateral boundary via a facilitated diffusion, passive system. Work described here indicates that sodium saccharin (25-130 mM) has little if any direct effect on the active transport system, but that the passive transport system is inhibited by saccharin. A short period of exposure (10-60 min) is required for expression of the effect, which is detectable at saccharin concentrations as low as 10 mM. At 100 mM-sodium saccharin, as much as 50% inhibition occurs. Saccharin also appears to act as a weak metabolic inhibitor. The basis of the 'non-specific' effect is not understood, but it can compromise the capacity of the epithelial cells to form sugar gradients. When a sugar is accumulated that satisfies both transport systems (for example 3-O-methylglucose) the effect of saccharin on the passive transport system is the predominant one, and the cells establish a higher sugar gradient than that observed in the absence of saccharin. The 'non-specific' metabolic effect is manifested as an inhibition of sugar gradient formation when sugars that satisfy only the active system (such as alpha-methylglucoside) are accumulated.

Animals↗
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Blepharospasm-oromandibular dystonia associated with a left cerebellopontine angle meningioma.

Blepharospasm-oromandibular dystonia is characterized by the presence of spasms of the orbicularis oculi (blepharospasm) and of the lower facial or oromandibular muscles. A patient with this syndrome is presented in which a left cerebellopontine angle meningioma appeared to act as a triggering mechanism for the development of this disorder. On the basis of this report, we recommend that physicians search for this tumor in patients with this disorder.

Cerebellar Neoplasms↗
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Maternal perceptions of lead poisoning in children with normal and elevated lead levels.

INTRODUCTION: The purpose of this study was to examine mothers' perceptions of the severity and susceptibility of their children to lead poisoning and to determine if a correlation existed between mothers' knowledge of lead poisoning and their children's blood lead levels. It was thought that mothers of children with lead poisoning (lead levels > or = 10 micrograms/dL) would score lower on a test of their perceptions and knowledge of lead poisoning than would mothers of children with normal lead levels (lead levels < or = 9 micrograms/dL). METHOD: A cross-sectional study comparing scores of a questionnaire completed by mothers whose children had elevated blood lead levels and mothers whose children had normal blood lead levels was conducted. RESULTS: No difference was found in the median test score between the 2 groups. For the correct responses on a question-by-question comparison, significant difference existed between groups; however, the percentage of correct responses was not always greater for the mothers of children with normal blood lead levels. DISCUSSION: Mothers' perceptions and knowledge of lead poisoning were not associated with their children's blood lead levels.

Adult↗
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Susceptibility of nosocomial urinary tract infections caused by multiply resistant gram-negative bacilli: potential use of antimicrobials "resistant" by disc-diffusion testing for controlling epidemics.

Protracted hospital-based epidemics of urinary tract infection and bacteremia due to multiply resistant gram-negative bacilli have become an increasingly common and serious problem. Failure to control such outbreaks stems partly from inability to eradicate a key reservoir, the catheterized bladder. Since eradication of bacteriuria in noncatheterized patients can be achieved with single doses of antimicrobials and correlates with urinary rather than with serum antibiotic concentrations, drugs to which an organism appears resistant by disc-diffusion testing, if excreted in the urine in high concentrations, might also prove useful in eliminating catheter-associated bacteriuria. Alternatively, urinary antiseptics, for which antimicrobial sensitivity testing is not usually done, might be effective. To test this hypothesis we determined the minimum inhibitory concentrations (MICs) of 45 multiply resistant Proteus, Serratia, Klebsiella, and Pseudomonas strains isolated in 13 recent epidemics of nosocomial urinary tract infections against 10 selected antimicrobials and urinary antiseptics, and compared these MICs with expected urinary concentrations of each drug. For each genus tested, MICs for at least two antimicrobials or urinary antiseptics were well below easily achievable urinary drug concentrations. Zone size criteria often predicted which drugs had MICs below achievable urinary levels. Little difference was found between MICs determined in Mueller-Hinton broth and in urine. During an epidemic, simultaneous treatment of all patients with bacteriuria by administration of a urinary antiseptic or an antibiotic that achieves high concentrations in urine, in conjunction with brief catheter removal, might prove useful in controlling any further infection.

Anti-Bacterial Agents↗