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Biomedical subjects

E D Brown

Publications and source records attributed to E D Brown.

At least 55 records · Page 3Linked to original sources
PubMed1993

Conformational change and membrane association of the PutA protein are coincident with reduction of its FAD cofactor by proline.

The PutA protein is both the put repressor and a membrane-bound enzyme with proline and delta 1-pyrroline-5-carboxylate dehydrogenase activities. The conditions required for association of purified PutA protein with membrane vesicles suggested that a redox switching mechanism might determine the proportion of PutA protein functioning as a dehydrogenase (Wood, J. M. (1987) Proc. Natl. Acad. Sci. USA 84, 373-377). The FAD cofactor was released from the PutA protein with 1 M KBr at neutral pH. The apoprotein retained delta 1-pyrroline-5-carboxylate dehydrogenase and DNA binding but not proline dehydrogenase activity. Reconstitution with FAD fully restored proline dehydrogenase activity. Proline at a concentration of 0.11 mM caused half-maximal bleaching of the FAD in PutA. Chymotryptic digestion of the PutA protein in the presence and absence of proline demonstrated that the persistence of a 119-kDa protein fragment was characteristic of the reduced protein. Identical digestion patterns were obtained from the apoprotein in the presence and absence of proline. The quantity of the 119-kDa fragment produced varied with proline concentration, yielding a midpoint of 0.056 mM proline. The fraction of PutA protein associated with membrane vesicles was also a function of proline concentration, yielding a titration midpoint of 0.10 mM proline. Membrane binding was thus coincident with both flavin reduction and a change in protein conformation.

Bacterial Proteins↗
PubMed1993

The dependence of the lipolytic activity of Rhizopus arrhizus lipase on surfactant concentration in Aerosol-OT/isooctane reverse micelles and its relationship to enzyme structure.

Aerosol OT, bis(2-ethylhexyl)sodium sulfosuccinate/isooctane reverse micelles were used to investigate the dependence of the lipolytic activity of Rhizopus arrhizus lipase on surfactant concentration. Kinetic constants for the lipolytic reaction were measured in parallel with structural studies using protein fluorescence and circular dichroism (CD) spectroscopy. Km values remained constant throughout the range of AOT concentrations studied. The kcat values decreased with increasing surfactant concentration at constant water-to-surfactant ratio (wo = 11) from 50 mM to 100 mM AOT, but remained constant from 100 to 200 mM AOT. These data suggested an association of the lipase with the micellar membrane. An inflection in the time-course of the reaction was found to be a function of both surfactant and substrate concentrations and was likely an indication of the interfacial nature of the hydrolysis reaction. Structure prediction based on far-UV CD spectral data demonstrated structural reorganization of R. arrhizus lipase upon incorporation into reverse micelles which was characterized by a dramatic increase in beta-sheet and overall accountable secondary structure. Other spectral changes of the lipase upon incorporation into reverse micelles included appearance of fine structure in the near-UV CD spectrum and a blue shift in the fluorescence emission maximum from 336 to 326 nm.

Circular Dichroism↗
PubMed1993

The correlation between two dietary assessments of carotenoid intake and plasma carotenoid concentrations: application of a carotenoid food-composition database.

A newly available carotenoid food-composition database providing specific carotenoid values for > 2300 foods was linked to dietary data on 57 male nonsmokers to examine the association between dietary carotenoid intake and plasma carotenoid concentrations over 3 wk when free-living. Carotenoid intake was estimated from a food-frequency questionnaire (FFQ) and 7 d of food diaries with concurrent analysis of plasma carotenoid concentrations. After adjustment for energy intake, percentage of energy from alcohol, and plasma lipid concentrations, significant diet-plasma correlations for the FFQ and the food diaries (FD) included alpha-carotene (r = 0.29 and 0.43), beta-carotene (r = 0.36 FFQ only), beta-cryptoxanthin (r = 0.46 and 0.44), lutein (r = 0.44 FD only), and lycopene (r = 0.53 FD only). Dietary carotenoid intakes were associated with plasma carotenoid concentrations for all the carotenoids except for beta-carotene when food diaries were used whereas the diet-plasma correlation for the provitamin A carotenoids were consistently significant when the FFQ was used.

Adult↗
PubMed1993

Behavioral marital therapy with and without additional couples relapse prevention sessions for alcoholics and their wives.

This study evaluated whether alcoholics who received couples relapse prevention (RP) sessions in the year after short-term behavioral marital therapy (BMT) did better than those who did not receive additional RP. Couples (n = 59) with an alcoholic husband, after participating in weekly BMT couples sessions for 5 months, were assigned randomly to receive or not receive 15 additional conjoint couples relapse prevention (RP) sessions over the next 12 months. Outcome measures were collected before and after BMT and at quarterly intervals for the year after BMT. Significant improvements in the alcoholics' drinking and the couple's marital adjustment occurred from before to after BMT replicating results of our own and other's earlier studies of BMT with alcoholics, and outcomes remained significantly improved through 12-months follow-up independent of the amount of aftercare received. Given these favorable outcomes overall, the present study provided a stringent test of the hypothesized utility of RP. As predicted, alcoholics who received RP after BMT had more days abstinent and fewer days drinking, maintained their improved marriages better and used behaviors targeted by BMT more than those who received BMT alone. The prediction that greater continued use of behaviors targeted by BMT would be associated with better outcomes irrespective of the amount of aftercare received also was supported. The final prediction that couples with more severe alcohol and marital problems at study entry would show the greatest additional benefit from RP was not supported. The relatively clear-cut findings favoring RP may be due to the fact that RP in this study was an intensive, multifaceted booster maintenance intervention delivered in a couples format over a lengthy period of time. Moreover, the present results occurred during the time that couples were still getting RP. Limitations to the generalizability and interpretation of the results are discussed.

Adult↗
PubMed1992

Redesigned purification yields a fully functional PutA protein dimer from Escherichia coli.

Proline utilization by Escherichia coli and Salmonella typhimurium requires expression of genes putP (encoding a proline transporter) and putA. Genetic data indicate that the PutA protein is both put repressor and a respiratory chain-linked dehydrogenase. We report a redesigned purification procedure as well as the physical characteristics and biological activities of the PutA protein purified from E. coli. The purified protein was homogeneous as determined by electrophoresis performed under denaturing and nondenaturing conditions. Its N-terminal sequence corresponded to that predicted by the DNA sequence. We showed copurification of proline and delta 1-pyrroline-5-carboxylate dehydrogenase activities. Purified PutA protein bound put DNA in vitro in an electrophoretic band-shift assay and it could be reconstituted to inverted membrane vesicles, yielding proline dehydrogenase activity. The Stokes radius and Svedberg coefficient of the protein were determined to be 7.1 nm and 9.9 S, respectively. These hydrodynamic data revealed that the protein in our preparation was dimeric with a molecular mass of 293 kDa and that it had an irregular shape indicated by the friction factor (f/f0) of 1.6.

Bacterial Proteins↗
PubMed1992

Plasma carotenoid response to chronic intake of selected foods and beta-carotene supplements in men.

We determined serial changes in four major plasma carotenoid fractions (alpha-carotene, beta-carotene, lutein/zeaxanthin, and lycopene) in 30 men consuming defined daily doses of carotenoids from foods (broccoli, carrots, or tomato juice) or from purified beta-carotene in capsules (12 or 30 mg) for 6 wk while fed a controlled diet. Compared with baseline, beta-carotene increased in the 30- and 12-mg-capsule and carrot groups whereas alpha-carotene increased in the carrot group and lutein increased in the broccoli group. Lower lutein concentrations in recipients of beta-carotene capsules suggested an interaction between these two carotenoids. Lycopene declined in all groups except the tomato-juice group. Total carotenoid concentration changes only reflected the large increases in beta-carotene concentrations and not the smaller changes observed in other individual carotenoids. Overall, purified beta-carotene produced a greater plasma response than did similar quantities of carotenoids from foods sources. However, some foods increased plasma concentrations of certain carotenoids.

Adult↗
PubMed1991

A kinetic and equilibrium study of the denaturation of aspartic proteinases from the fungi, Endothia parasitica and Mucor miehei.

Kinetic and equilibrium analyses of the denaturation of Endothia parasitica and Mucor miehei aspartic proteinases were performed using enzyme activity and ultraviolet absorption as indices of denaturation. Denaturation of these proteinases was shown to be irreversible, suggesting that the conformations of these aspartic proteinases may be predetermined in their zymogens. Thermal and guanidine hydrochloride denaturation of these proteinases produced first-order, two-state, kinetic behaviour. Equilibrium unfolding transitions of these proteinases were highly cooperative but not entirely coincident in the two indices employed, suggesting some deviation from two-state character. Oxidation to remove 37.8% of the carbohydrate of M. miehei glycoproteinase with sodium metaperiodate resulted in a substantial decrease in both kinetic and equilibrium stabilities without modification of the amino acid composition or specific activity. In addition, gel filtration subsequent to equilibrium studies indicated that partial removal of the carbohydrate from M. miehei proteinase promoted autolysis under denaturing conditions.

Aspartic Acid Endopeptidases↗
PubMed1989

Plasma carotenoids in normal men after a single ingestion of vegetables or purified beta-carotene.

Changes in seven plasma carotenoids were measured in 30 men for 11 d after ingesting a single dose of pure beta-carotene or a high carotenoid vegetable. A controlled, low-carotenoid diet was fed in a crossover design. Maximum plasma concentrations of beta-carotene occurred 24-48 h after dosing with beta-carotene (12 or 30 mg) or carrots (270 g). A large intake of broccoli (600 g) or tomato juice (180 g) did not change any plasma carotenoids. We concluded that 1) normal subjects vary widely, three to fourfold, in efficiency of carotenoid absorption; 2) peak plasma response to beta-carotene in a capsule occurs at 24-48 h; 3) a large single intake of carrots produces a small increase in plasma beta-carotene but single intakes of broccoli or tomato juice do not change plasma carotenoids; and 4) plasma response to pure beta-carotene is greater than the response to a similar amount of beta-carotene in carrots.

Absorption↗
PubMed1989

Concentrations of carotenoids, retinol, and tocopherol in plasma, in response to ingestion of a meal.

Field studies and epidemiological surveys may necessitate obtaining a blood sample from a nonfasted subject for nutritional assessments. We measured the effect of a standardized test meal, eaten after an overnight fast, on the concentrations of seven carotenoid fractions, retinol, and tocopherol in plasma of eight healthy adults. The 790-calorie test meal did not alter the measured concentrations. We conclude that blood sampled up to 4 h after breakfast can be validly used for these measurements.

Adult↗
PubMed1988

Carotenodermia in men with elevated carotenoid intake from foods and beta-carotene supplements.

We evaluated the relation between plasma levels of carotenoids and carotenodermia in 30 men receiving carotenoid supplementation for 42 d. Five subjects each were randomly assigned to one of six treatment groups: 30 mg purified beta-carotene supplement, 12 mg beta-carotene supplement, 272 g cooked carrots, 300 g cooked broccoli, 180 g tomato juice, and placebo. Definite carotenodermia was observed only in the five subjects who took 30 mg of purified beta-carotene daily. Carotenodermia was first noted between 25 and 42 d after supplementation and persisted from 14 to greater than 42 d posttreatment and was observed only after plasma total carotenoid levels exceeded 4.0 mg/L. These observations may be useful to investigators planning clinical trials with beta-carotene and to clinicians assessing the significance of carotenodermia in men taking beta-carotene supplements or following diets high in carotenoid-containing foods.

Adult↗
PubMed1988

Effects of storage and handling conditions on concentrations of individual carotenoids, retinol, and tocopherol in plasma.

We investigated the effects of storage and handling on measured values for carotenoids, retinol, and tocopherol in plasma. We found no significant differences in the concentrations of these analytes measured in plasma samples that were frozen immediately after separation as compared with replicate samples maintained at room temperature in the dark for 24 h. Analytes were stable in solvents for at least 18 h at 23 degrees C after extraction. Purging samples with nitrogen gas before freezing had no detectable beneficial effects. All analytes were stable in plasma stored at -70 degrees C for at least 28 months or at -20 degrees C for five months. By 15 months the concentrations of carotenoids were significantly less (P less than 0.05) in plasma stored at -20 degrees C than in plasma stored at -70 degrees C, while retinol and tocopherol concentrations were not significantly different. Concomitant with the decrease in carotenoids was the appearance of unidentified peaks in the ultraviolet. Adding ascorbic acid or butylated hydroxytoluene antioxidants to the precipitating solvent did not alter the losses of carotenoids or alter the appearance of unidentified peaks. Under appropriate conditions, plasma carotenoids, retinol, and tocopherol are stable for more than two years.

Ascorbic Acid↗
PubMed1985

Comparison of indices used to detect hypoventilation during sleep.

Because there is no uniform method of measuring the severity of sleep apnea, we compared respiratory indices calculated from airflow and oxyhemoglobin saturation (SaO2) signals in 16 subjects during a night's sleep. Airflow was measured with a loosely fitting pneumotachograph or thermister and the following indices calculated manually: total apneas (A) and hypopneas (H); A and H per hour of sleep; total A H time; average duration of A H episodes, and A H index (the product of 2 and 4). SaO2 was measured with a Hewlett-Packard ear oximeter and the following indices calculated with a microcomputer; total number of desaturation (D) episodes; D episodes per hour of sleep; average maximum D; D index (the product of 7 and 8); SaO2 50 (1), and SaO2 10(1). There was a significant correlation among all indices; the highest correlation was between total A and H and total D (r = 0.97). We conclude that SaO2 indices calculated with a microcomputer correlate well with flow indices.

Humans↗
PubMed1984

Treatment of obstructive sleep apnea with continuous nasal airflow delivered through nasal prongs.

We describe a new device for treating obstructive sleep apnea (OSA) which is similar to nasal CPAP, but less cumbersome. The device consists of a 7 mm diameter flexible tube terminating at one end in nasal prongs covered with foam cylinders. The foam cylinders are compressed, inserted into the nostrils and released, forming a tight seal. The other end of the catheter is attached to a compressor delivering between 7 and 15 L/min of air. We studied four men and two women with OSA, the first night without treatment and the following night with continuous nasal airflow. A desaturation index was calculated by multiplying the average number of desaturation episodes per hour of sleep times the average maximum desaturation per episode. With continuous nasal airflow there was a significant decrease in all parameters (p less than .025). We conclude that continuous nasal airflow decreased oxyhemoglobin desaturation in patients with OSA and may be useful in patients with mild-to-moderate OSA and in patients who do not tolerate nasal CPAP.

Adult↗
PubMed1984

Evaluation of tuberculosis control programs: some national trends.

Increasing numbers of tuberculosis control programs compile information about the number, location, bacteriologic status, and chemotherapy status of tuberculosis patients within their jurisdiction. Reports from these programs show that during the 1970s the prevalence of patients requiring supervision decreased three times faster than the incidence of tuberculosis; this decline occurred because low relapse rates among patients who had received adequate therapy allowed the recommended duration of follow-up after completion of therapy to diminish from lifetime to none. The prevalence of patients hospitalized for tuberculosis decreased four times faster than the incidence of tuberculosis because the duration of hospitalization decreased from many months to a few weeks and because a small proportion of patients were hospitalized. Future declines in these two program aspects are expected to be much smaller and should parallel the decline in morbidity more closely. Other measures of program performance have shown a less favorable trend and suggest an impeded flow of information to the health department from other persons or agencies involved in the care of tuberculosis.

Antitubercular Agents↗
PubMed1983

Tuberculosis among Indochinese refugees in the United States.

Surveys of state tuberculosis control programs revealed that of the 262,602 Indochinese refugees who entered the United States in 1979 and 1980, approximately 1.5% either had tuberculosis at the time of entry or developed it by the end of 1980; another 18% were placed on preventive therapy. The refugees comprised 5.3% of the nationally counted cases during the two-year period. Age- and sex-specific incidence rates among Indochinese refugees were 30 to 200 times higher than those for other persons in the United States. For refugees who arrived in 1979, the incidence of tuberculosis during 1980 (231 per 100,000) was only one third the incidence during 1979 (719 per 100,000). For refugees who entered the United States in 1980, the incidence during 1980 was 480 per 100,000. Bacteriologic confirmation of the diagnosis was reported for only 26% of refugees, compared with 79% of other patients with tuberculosis in the United States, suggesting overdiagnosis of tuberculosis among refugees. However, age-specific rates of bacteriologically positive tuberculosis were still 14 to 70 times higher for refugees than for the United States as a whole.

Adolescent↗
PubMed1983

Pulmonary infiltrates following butane 'fire-breathing'.

Rapidly progressive bilateral pulmonary infiltrates occurred in a 19-year-old man following an unusual hydrocarbon abuse. The acute illness was the result of a "trick" known as "fire-breathing." Fire-breathing involves filling the oral cavity with butane gas, from an ordinary butane cigarette/cigar lighter, and exhalation of the volatile vapors over an open flame producing a flame-throwing effect. Because of the pulmonary toxic reaction, this activity could have a serious or even fatal outcome.

Adult↗
PubMed1982

Sleep fragmentation in the elderly: relationship to daytime sleep tendency.

Sleep in the elderly is known to be disturbed, and many elderly persons also complain of daytime sleepiness. The present study assessed sleep and waking behavior in 12 male (aged 63 to 86) and 12 female (ages 63 to 82) subjects. Sleep stages, respiration, and movement were recorded at night, and daytime sleep tendency was measured using the Multiple Sleep Latency Test during a single 24-hour period. Daytime sleepiness did not correlate with total sleep time or any sleep stage, but was significantly correlated with measures of sleep fragmentation. The latter included transient arousals, a measure of less than 15-sec awakenings, and sleep-related respiration disturbance. These findings suggest that fragmented nocturnal sleep is a significant cause of reduced daytime well-being in elderly individuals. The continuity of both sleep and wakefulness appears to be disrupted with age. Experimental strategies for achieving a rational sleep hygiene are discussed.

Aged↗