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Biomedical subjects

T L Miller

Publications and source records attributed to T L Miller.

At least 73 records · Page 4Linked to original sources
PubMed1990

Urgent care center pediatric telephone advice.

Pediatric telephone advice is sought frequently by members of the community. This study was undertaken to evaluate the quality and accuracy of pediatric telephone advice given by free-standing urgent care centers. One hundred such facilities were telephoned and advice was requested by a research assistant. A case was presented that could have represented a pediatric medical emergency. Overall only 17 centers gave adequate advice. The data suggest that under some circumstances free-standing urgent care center pediatric telephone advice may be inaccurate and inappropriate. Workable policies and protocols for pediatric telephone advice should be instituted by these facilities.

Algorithms↗
PubMed1989

Increase in colonic methanogens and total anaerobes in aging rats.

Methanogens are present in the colons of our local Wistar rat colony. We studied the changes in concentrations of their fecal methanogenic and nonmethanogenic bacteria with age as a model of the development of these communities in humans. We found that the predominant methanogen in the rats is a Methanobrevibacter species. The log of the concentration of total anaerobes increased from 9.8/g (dry weight) at 3.0 weeks of age (shortly after weaning) to 10.7/g (dry weight) at 96 weeks (shortly before the end of the life span). In contrast, the log concentration of methanogens increased from 5.5 to 9/g (dry weight) during the same time period. Therefore, methanogens increased as a percentage of the total anaerobes from 0.005% at 3.0 weeks to 2.0% at 96 weeks. About 12 doublings of the methanogenic population and 3.3 doublings of the nonmethanogenic population took place from weaning until death. The slow increase in the ratio of methanogens to total anaerobes with age followed the same pattern in cecal contents as found in feces. There were no relationships between animal weights or fecal outputs and the increase in total anaerobe and methanogen concentrations in feces. A possible explanation for the slow increase in the Methanobrevibacter species in Wistar rats with age is a gradual shifting of the use of electrons from the reduction of CO2 to acetate by acetogens to the reduction of CO2 to CH4. The results provide the first evidence for an age-related change in the nonmethanogenic bacteria of the colon and supporting microbiological evidence for physiological studies that have shown age-related increases in colonic methane production in humans.

Aging↗
PubMed1989

Constancy of glucose and starch fermentations by two different human faecal microbial communities.

The fermentation of glucose and corn starch by faecal suspensions from two subjects was examined over a three and a half year period. The substrate specificity and products of the faecal fermentations of each subject were relatively stable during this period and were significantly different between subjects. The major soluble end products of fermentation of glucose or starch were acetate, propionate, and butyrate. Hydrogen temporarily accumulated and was subsequently used in fermentations by both subjects. Hydrogen was used without methane production in fermentations of subject 1, but was used for methane formation in fermentations of subject 2. Although the rates of glucose fermentation were similar between both subjects; subject 1 produced a significantly greater molar ratio of propionate than did subject 2. The rate of fermentation of starch by faecal suspensions from subject 1 was faster than that of subject 2. The molar ratio of butyrate was greater for starch fermentations by subject 2, while the molar ratio of propionate was greater with subject 1. Significant differences were found between subjects in molar ratios and concentration of acetate and propionate and concentrations of butyrate in faeces.

Acetates↗
PubMed1988

Activity of the anion exchange protein (band 3) of human erythrocytes as affected by hydroxychloroaromatic chemicals.

The membranous segment of the anion transport protein (band 3) of the human erythrocyte membrane has been shown [T.L. Miller and R.J. Smith, Archs Biochem. Biophys. 250, 128 (1986)] to be destabilized by relatively low concentrations of many hydroxychloroaromatic compounds (HO-Cl chi-Ar), including hydroxychlorodiphenyl ethers (HO-Cl chi-DPE), major contaminants of technical grade pentachlorophenol (PCP). In the present study, HO-Cl chi-DPE also caused a concentration-dependent inhibition of the rate of sulfate exchange mediated by band 3 in human erythrocytes. The most active compound studied, 2-HO-Cl9-DPE, was about nine times more potent in inhibiting sulfate exchange than 2-HO-2',4,4'-Cl3-DPE, the least active compound studied. The potency of HO-Cl chi-DPE as inhibitors of anion exchange generally increased with the degree of chlorination. The concentration-dependent decreases in the sulfate exchange rate elicited by 2-HO-Cl9-DPE and 2-HO-2',4,4'-Cl3-DPE paralleled the effects of these compounds on the stability of band 3.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1988

Fermentation of Insoluble Cellulose by Continuous Cultures of Ruminococcus albus.

The hydrolysis and fermentation of insoluble cellulose (Avicel) by continuous cultures of Ruminococcus albus 7 was studied. An anaerobic continuous culture apparatus was designed which permitted gas collection, continuous feeding, and wasting at different retention times. The operation of the apparatus was controlled by a personal computer. Cellulose destruction ranged from ca. 30 to 70% for hydraulic retention times of 0.5 to 2.0 days. Carbon recovery in products was 92 to 97%, and the oxidation-reduction ratios ranged from 0.91 to 1.15. The total product yield (biomass not included) per gram of cellulose (expressed as glucose) was 0.83 g g, and the ethanol yield was 0.41 g g. The product yield was constant, indicating that product formation was growth linked.

Journal Article↗
PubMed1988

Kinetics of Insoluble Cellulose Fermentation by Continuous Cultures of Ruminococcus albus.

Data from analyses of continuous culture fermentation of insoluble cellulose by Ruminococcus albus 7 were used to derive constants for the rate of cellulose hydrolysis and fermentation, growth yield, and maintenance. Cellulose concentration was 1% in the nutrient reservoir, and hydraulic retention times of 0.5, 1.0, 1.5, 1.75, and 2.0 days were used. Concentrations of reducing sugars in the cultures were negligible (less than 1%) compared with the amount of hydrolyzed cellulose, indicating that cellulose hydrolysis was the rate-limiting step of the fermentation. The rate of utilization of cellulose depended on the steady-state concentration of cellulose and was first order with a rate constant (k) of 1.18 day. The true microbial growth yield (Y) was 0.11 g g, the maintenance coefficient (m) was 0.10 g g h, and the maximum Y(ATP) was 7.7 g of biomass (dry weight) mol of ATP.

Journal Article↗
PubMed1988

Acetate production from hydrogen and [13C]carbon dioxide by the microflora of human feces.

Fecal suspensions from humans were incubated with 13CO2 and H2. The suspensions were from subjects who harbored 10(8) and 10(10) methanogens per g (dry weight) of feces, respectively, and from a subject who did not harbor methanogens. Quantitative nuclear magnetic resonance spectroscopy showed that acetate labeled in both the methyl and carboxyl groups was formed by suspensions from the subject without methanogens and the subject with the lower concentrations of methanogens. The amounts of labeled acetate formed were in agreement with the amounts expected based on measurements of H2 utilization. No labeled acetate was formed by suspensions from the subject with the higher concentrations of methanogens, and essentially all of the H2 used was accounted for by CH4 production. Suspensions from the subject with lower concentrations of methanogens produced both methane and acetate from H2 and CO2. The results indicate that reduction of CO2 to acetate may be a major pathway for microbial production of acetate in the human colon except when very high concentrations of methanogens (ca. 10(10) per g [dry weight] of feces) are present. Double-labeled acetate was also formed from H2 and 13CO2 by fecal suspensions from nonmethanogenic and moderately methanogenic rats.

Acetates↗
PubMed1988

Short chain fatty acid distributions of enema samples from a sigmoidoscopy population: an association of high acetate and low butyrate ratios with adenomatous polyps and colon cancer.

We investigated the distribution of short chain fatty acids (SCFA) in enema samples taken from subjects before sigmoidoscopy as an indicator of possible microbial community differences between subjects subsequently diagnosed as normal or having colonic disorders. The major SCFA in all groups were acetic, propionic, and butyric acids. A significantly higher ratio of acetate to total SCFA and lower ratio of butyrate to total SCFA was found for polyp-colon cancer subjects than for normal subjects. There were no significant differences in the ratios of acetate, propionate, or butyrate between the diverticulosis or inflammatory bowel groups and the normal group. There were no significant sex differences nor were there correlations with the ratios of acetate, propionate or butyrate and age, subject weight, or dry weights of samples. Significant differences in concentrations of individual acids were found between normal and certain diagnostic groups. The difference in proportions of individual SCFA between groups suggest differences in fermentation patterns of the colonic microflora.

Acetates↗
PubMed1987

Bowel cancer characteristics in patients with regional enteritis.

We report 10 carcinomas in 8 patients with regional enteritis. Five of the cancers were in the ileum, 4 in the right colon, and 1 in the rectum. The visualized small bowel cancers appeared as benign strictures in small bowel involved by regional enteritis. Most were poorly differentiated. The colon cancers had a more typical radiographic appearance of malignancy. In some patients with small bowel cancer the malignancy was discovered only on histologic evaluation; the malignant nature of the lesion was not appreciated by radiography or gross examination at surgery.

Adenocarcinoma↗
PubMed1986

Liquid chromatographic assay for cerebrospinal fluid serotonin.

A novel liquid chromatographic method was developed for accurate and precise routine quantification of serotonin in human cerebrospinal fluid. Serotonin is derivatized with an amine-specific reagent leaving its hydroxy group free for electrochemical detection and making it lipophilic enough for efficient extraction into organic solvents. The method is reproducible, linear and free of interferences by endogenous amines other than serotonin. The limit of sensitivity is 100 fmol/ml CSF or 20 parts per trillion. Serotonin concentrations in lumbar cerebrospinal fluid from drug free, depressed patients were in the low nanomolar range.

Chromatography, Liquid↗
PubMed1986

Thermotropic properties of human erythrocyte membrane proteins as affected by hydroxychloroaromatic compounds.

The thermal stability of the anion transport protein (band 3) and other proteins of the human erythrocyte membrane, as influenced by hydroxychloroaromatic (HO-Cl2-Ar) compounds, was studied by differential scanning calorimetry. Various hydroxychlorodiphenyl ethers (HO-Clx-DPEs) and hexachlorophene, but not pentachlorophenol, caused a marked decrease in the thermal stability of band 3. Most of the other calorimetric transitions of the erythrocyte membrane were only slightly affected. The activity of HO-Clx-DPEs toward lowering the transition temperature of band 3 generally increased with the degree of chlorination, and was somewhat dependent on the position of hydroxyl substitution. At higher concentrations of HO-Clx-DPEs, there was a decrease in the enthalpy change and a broadening of the endothermic transition of band 3. The order of effectiveness of these compounds, as determined from band 3 denaturation temperatures, was similar to the order of potency previously observed for hemolysis of human erythrocytes.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1986

Characteristics of methanogens isolated from bovine rumen.

Six strains of methanogens were isolated from 10(-8) and 10(-9) ml of bovine rumen contents. All strains had the morphologic and physiologic characteristics of Methanobrevibacter spp. Four strains required coenzyme M; two did not. Growth of all strains either depended on or was stimulated by a mixture of isobutyric, isovaleric, 2-methylbutyric, and valeric acids. None of the strains reacted with antiserum against the type strain of Methanobrevibacter ruminantium.

Animals↗
PubMed1986

Incidence of methanogenic bacteria in a sigmoidoscopy population: an association of methanogenic bacteria and diverticulosis.

This study determined the incidence and concentration of methane-producing bacteria in tap water enema samples of 130 individuals taken before sigmoidoscopy. The number of subjects classified in five major colonic groups were as follows: normal colon 36, diverticulosis 57, inflammatory bowel disease 11, colon polyps 34, and colon cancer 11. Some patients were placed in more than one category. Ninety four of the subjects or 72% had methanogenic bacteria ranging in concentration from 6 to about 3 X 10(10)/g dry weight of faeces. The predominant methanogen in all groups was Methanobrevibacter smithii. Chi-square analysis showed that the incidence of methanogens in concentrations of 10(7)/g dry weight of faeces or greater in patients with diverticulosis (58%) was significantly greater than in normal patients (25%). High methanogen concentrations are associated with excretion of methane in the breath.

Adult↗
PubMed1985

Methanosphaera stadtmaniae gen. nov., sp. nov.: a species that forms methane by reducing methanol with hydrogen.

Methanosphaera stadtmaniae is a non-motile, Gram-positive spherical-shaped organism that obtains energy for growth by using hydrogen to reduce methanol to methane. It does not produce methane from hydrogen and carbon dioxide, formate, acetate or methylamines and cannot grow with hydrogen and carbon monoxide, nitrate, fumarate, sulfate or choline. Its pH optimum is 6.5 to 6.9 and its temperature optimum is 36 degrees to 40 degrees C. It is not inhibited by bile salts, inhibitors of the synthesis of folic acid coenzymes, cephalothin or clindamycin but is inhibited by metronidazole, bacitracin, monensin, lasalocid, or bromoethanesulfonate. It requires acetate, carbon dioxide, isoleucine, ammonium, and thiamin for growth and biotin is stimulatory. It does not contain cytochromes and the mol % G + C of its DNA is 25.8. The composition of its cell wall and 16 S rRNA and its immunological fingerprint are consistent with characterization of the organism as a member of a new genus of the family Methanobacteriaceae. The habitat of the type strain is the human large intestine.

DNA, Bacterial↗
PubMed1985

Arthrographically assisted splint therapy.

Occlusal splints are often constructed to aid in treatment of temporomandibular joint meniscus displacement. Techniques for arthrographically locating the point of meniscal displacement and for fabrication of an appropriate occlusal splint are described.

Cartilage, Articular↗
PubMed1985

Evaluation of arthrographically assisted splint therapy in treatment of TMJ disk displacement.

Eighty-two patients with audible clicking were evaluated and treated with splints made by using arthrographic assistance. In the course of this study, it became apparent that the later the opening click, the earlier the closing click. It was not always possible to auscultate or palpate either an opening or a closing click in many patients with arthrographic findings of disk displacement with reduction. Since the opening click was the only audible sound in some patients, clinical judgment alone cannot be used to replace the displaced disk at an optimal mandibular position. The elimination of the opening click does not always signify recapture of the disk. Maxillomandibular and incisal relationships limit the amount of protrusion possible to recapture the displaced disk.

Adolescent↗