Search PubMed⌕ Search

Biomedical subjects

D R Nelson

Publications and source records attributed to D R Nelson.

At least 127 records · Page 7Linked to original sources
PubMed1995

The effects of roasting temperature applied to whole soybeans on site of digestion by steers: II. Protein and amino acid digestion.

A 4 x 5 Youden square design was used to determine the effect of roasting temperature of whole soybeans on escape of CP from the rumen and disappearance of N from the small intestine in steers. Four steers (average BW 373 kg +/- 30.7) cannulated at the rumen, duodenum, and ileum were fed each of five diets (1.8% of BW) over five periods. The basal diet contained corn silage (50% of diet DM), alfalfa hay (24%), corn-urea premix (6%), corn starch grits (16.6%), and soybean oil (3.4%). Soybeans (16% of diet DM), either raw or heated to an exit temperature of 141, 149, or 157 degrees C in a commercial roaster, replaced the soybean oil and most of the corn starch grits in the soybean-containing diets. Ruminal ammonia N was lower (P < .05) for the basal diet than for the soybean-containing diets. Roasting temperature of whole soybeans had no significant impact on ruminal ammonia N. Total N reaching the duodenum was greater (P < .05) for steers fed the soybean diets than for steers fed the basal diet. Non-bacterial N (dietary N) at the duodenum was increased (P < .05) by feeding soybeans. Soybean N reaching the duodenum decreased with increased roasting temperature. Increased roasting temperature of whole soybeans seemed to make the soybeans more brittle, subsequently increasing degradation of CP in the rumen. However, disappearance of soybean N in the small intestine, as a proportion of the soybean N entering the small intestine, increased with increased roasting temperature. Apparent total tract N digestibility was increased (P < .05) by feeding soybeans. Flow to the duodenum and small intestinal digestibility of total, essential, and nonessential amino acids increased (P < .05) when soybeans were fed and when roasted vs raw soybeans were fed. Under normal roasting conditions, it seemed that little potential for heat damage to the soybean protein existed. Instead, undesirable effects of heating on handling characteristics of the soybeans were reached before the point at which loss of nutritive value occurred. Feeding steers diets containing roasted whole soybeans increased the N and amino acids available to steers over steers fed diets containing raw soybeans due to increased ruminal soybean nitrogen escape and increased small intestinal digestibility.

Amino Acids↗
PubMed1995

Ruminal fermentation and passage of nutrients to the duodenum of lactating cows fed mixtures of corn and barley.

Five Holstein cows were used in a 5 x 5 Latin square design and fed diets containing five different ratios of starch from ground shelled corn and steam-rolled barley. The DMI decreased and both the proportions of OM and starch digested in the rumen increased as barley starch increased in the diet. Corn and barley starches fed in a ratio of 75:25 maximized the proportions of ADF and NDF digested in the rumen. Replacement of 25% of the corn starch with barley starch resulted in the largest increase in the molar percentage of propionate and the largest decrease in the molar percentage of acetate in ruminal fluid. Passage of NAN to the duodenum was not affected by treatment; however, the percentage of nonammonia nonmicrobial N in NAN decreased as barley starch increased. Passage of AA to the duodenum was largest when corn and barley starches were fed in ratios of 100: 0 and 0:100 because of the influence of DMI and microbial protein synthesis. Production of Milk, CP, and SNF was similar when cows were fed diets containing corn and barley starches in ratios of 100:0, 75:25, and 50:50 but was decreased when the ratios were 25:75 and 0:100. Increased production responses of cows when diets contained larger amounts of starch from ground shelled corn were probably due to increased DMI.

Amino Acids↗
PubMed1994

Biomechanical and esthetic considerations for maxillary anterior overdenture abutment selection.

Maxillary canine teeth traditionally have been selected as overdenture abutments. Undesirable aspects associated with the use of maxillary canines as overdenture abutments are described. The use of maxillary lateral incisors as overdenture abutments offers vertical support to the prosthesis, favorable stress distribution, improved esthetics, and preservation of the premaxilla.

Biomechanical Phenomena↗
PubMed1994

Fatal childhood injury patterns in an urban setting.

STUDY OBJECTIVE: To describe fatal childhood injury patterns in an urban county and evaluate the use of the emergency medical services system. DESIGN: Retrospective chart review of medical examiner files, prehospital and hospital records, and police and fire personnel reports. SETTING: Milwaukee County, Wisconsin, an urban county with a population of approximately 1 million. PARTICIPANTS: All children 15 years old or younger who sustained a fatal injury in 1989 or 1990 (70). RESULTS: House fires were the leading cause of death by injury (34%), followed by firearms (19%), and drowning (11%). Motor vehicle occupant deaths occurred less frequently (7%). One-third of deaths were homicides (48% firearms and 30% assault). Twenty-four percent of deaths were pronounced at the scene, 12% were dead-on-arrival (no emergency department resuscitative efforts), and 37% were dead-on arrival ED resuscitations. Only 27% of victims survived to become inpatients (84% died within 72 hours). Mean scene time (16.1 +/- 7.9 minutes), transport time (9.5 +/- 5.1 minutes), and success rates for prehospital peripheral IV insertion (72%), endotracheal intubation (91%), and intraosseous line (86%) were not significantly different among those who were dead-on-arrival, dead-on-arrival failed resuscitations, or eventual inpatients. CONCLUSION: Fatal childhood injury patterns in this urban setting differed from reported national injury patterns. This study found a higher percentage of deaths from fire, gunshot wounds, and homicides but a lower percentage of motor vehicle-related deaths. Prevention strategies need to address the injury patterns of a particular community. Only a small percentage of victims survived to receive inpatient care following their injuries, suggesting that primary prevention of injury may be the most effective intervention.

Adolescent↗
PubMed1994

Indomethacin suppositories versus intravenously titrated morphine for the treatment of ureteral colic.

STUDY OBJECTIVES: To develop a protocol for the blinded IV titration of morphine and to compare the analgesic efficacy and side effect profile of indomethacin suppositories versus IV morphine in the treatment of acute ureteral colic. DESIGN: Randomized, double-blind, double-dummy, two-period crossover study. SETTING: Emergency department of a central-city, teaching hospital. PARTICIPANTS: Patients 18 to 75 years of age with pain suggestive of ureteral colic. Exclusions included pregnancy, adverse reactions to the study drugs, chronic nonsteroidal anti-inflammatory drug (NSAID) therapy, or any pain medicine taken within four hours of ED admission. INTERVENTIONS: Patients were randomized to one of two groups: indomethacin 100-mg rectal suppository or morphine by IV titration (5-mg loading dose and up to two additional 2.5-mg doses if needed). At the end of 30 minutes, if adequate pain relief had not been obtained, treatment was crossed over. MEASUREMENTS: Verbal analog scale (initial pain) and visual analog pain relief scale. MAIN RESULTS: Seventy-five patients were entered into the study. Only data from those patients with stone presence confirmed by IV pyelogram or stone passage were analyzed. Twenty-four could not be evaluated (23 who did not meet criteria for stone presence and one whose pain resolved spontaneously before study medications could be administered). Of the remaining 51 patients, 31 received indomethacin first and 20 received morphine first. Morphine recipients reported more pain relief at ten minutes (P = .02), but at 20 and 30 minutes, no significant difference (P = .17 and .74, respectively) existed between the two groups. CONCLUSION: IV morphine produced more rapid analgesia than rectally administered indomethacin. There were no significant differences in vital sign changes or number of side effects between the two treatment groups. This study is the first to compare an NSAID with morphine administered by IV titration, considered by many to be the "gold standard" for relief of acute, severe pain. Future studies could evaluate the simultaneous administration of an opioid combined with an NSAID or compare an IV titrated opioid with an IV NSAID.

Adult↗
PubMed1994

Hand washing frequency in an emergency department.

STUDY OBJECTIVE: Previous studies, conducted mainly in ICUs, have shown low compliance with hand-washing recommendations, with failure rates approaching 60%. Hand washing in the emergency department has not been studied. We examined the frequency and duration of hand washing in one ED and the effects of three variables: level of training, type of patient contact (clean, dirty, or gloved), and years of staff clinical experience. DESIGN: Observational. SETTING: ED of an 1,100-bed tertiary referral, central city, private teaching hospital. PARTICIPANTS: Emergency nurses, faculty, and resident physicians. Participants were informed that their activities were being monitored but were unaware of the exact nature of the study. INTERVENTIONS: An observer recorded the number of patient contacts and activities for each participant during three-hour observation periods. Activities were categorized as either clean or dirty according to a scale devised by Fulkerson. The use of gloves was noted and hand-washing technique and duration were recorded. A hand-washing break in technique was defined as failure to wash hands after a patient contact and before proceeding to another patient or activity. RESULTS: Eleven faculty, 11 resident physicians, and 13 emergency nurses were observed. Of 409 total contacts, 272 were clean, 46 were dirty, and 91 were gloved. Hand washing occurred after 32.3% of total contacts (SD, 2.31%). Nurses washed after 58.2% of 146 contacts (SD, 4.1%), residents after 18.6% of 129 contacts (SD, 3.4%), and faculty after 17.2% of 134 contacts (SD, 3.3%). Nurses had a significantly higher hand washing frequency than either faculty (P < .0001) or resident physicians (P < .0001). Hand washes occurred after 28.4% of 272 clean contacts (SD, 2.34%), which was significantly less (P < .0001) than 50.0% of 46 dirty contacts (SD, 7.4%) and 64.8% of 91 gloved contacts (SD, 5.0%). The number of years of clinical experience was not significantly related to hand-washing frequency (P = .82). Soap and water were used in 126 of the hand washes, and an alcohol preparation was used in the remaining six. The average duration of soap-and-water hand washes was 9.5 seconds. CONCLUSION: Compliance with hand washing recommendations was low in this ED. Nurses washed their hands significantly more often than either staff physicians or resident physicians, but the average hand-washing duration was less than recommended for all groups. Poor compliance in the ED may be due to the large number of patient contacts, simultaneous management of multiple patients, high illness acuity, and severe time constraints. Strategies for improving compliance with this fundamental method of infection control need to be explored because simple educational interventions have been unsuccessful in other health care settings.

Analysis of Variance↗
PubMed1994

The DnaK homologue of the marine Vibrio sp. strain S14 binds to the unprocessed form of a carbon starvation-specific periplasmic protein.

The Escherichia coli DnaK homologue in Vibrio sp. strain S14 was shown to possess chaperone function for translocation during carbon starvation. This was demonstrated by using the method of co-immunoprecipitation. DnaK co-precipitated with the carbon starvation-specific periplasmic space protein Csp5 three hours after the onset of carbon starvation. Pulse-chasing of the protein with radiolabelled methionine followed by the addition of an excess of unlabelled methionine demonstrated that the Csp5 protein was translocated across the inner membrane. Only the cytoplasmic unprocessed precursor form of Csp5 co-precipitated with DnaK. The non-covalent binding between the two proteins was found to be ATP-dependent, as the addition of ATP released the interaction between DnaK and the precursor form of Csp5, as was shown on silver-stained SDS-polyacrylamide gels and by Western blot analysis. We suggest that DnaK maintains the carbon starvation-inducible protein Csp5 in a translocation-competent form in the cytoplasm.

Adenosine Triphosphatases↗
PubMed1994

Subcellular localization and chaperone activities of Borrelia burgdorferi Hsp60 and Hsp70.

Subcellular locations and chaperone functions of Hsp60 and Hsp70 with flagellin were investigated in Borrelia burgdorferi. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis of fractionated cells showed Hsp60 to be present in the soluble fractions and the Triton X-100 detergent-soluble membrane fraction at growth temperatures ranging from 20 to 37 degrees C. The relative amount of Hsp60 associated with the membrane increased with growth temperature. Hsp70 was found in soluble fractions at growth temperatures between 28 and 37 degrees C, but at 20 degrees C it was also present in the Triton X-100-insoluble membrane fraction. Immunoelectron microscopy revealed that the majority of Hsp60 was localized in the cytoplasm but a detectable fraction (approximately 30%) was associated with the cell envelope. The chaperone functions of Hsp60 and Hsp70 were analyzed by immunoprecipitation of [35S]methionine-labeled cell lysates under nondenaturing conditions in the presence or absence of ATP. Hsp70 was found to bind flagellin at all temperatures tested between 33 and 41 degrees C. This association could be decreased with ATP when cells had been incubated at 41 degrees C during radioactive labeling but not at lower temperatures. Both flagellin and Hsp70 were found to associate with Hsp60, forming a complex of the three proteins. Hsp70 association with this complex could be decreased with ATP, but flagellin binding to Hsp60 was ATP independent at all temperatures studied. Both Hsp70 and flagellin were inaccessible to monoclonal antibodies against them when bound to Hsp60. These studies suggest that in B. burgdorferi, a major function of Hsp60 and Hsp70 is in the molecular processing of flagellin.

Adenosine Triphosphate↗
PubMed1994

Isolation of Borrelia burgdorferi from saliva of the tick vector, Ixodes scapularis.

A method for cultivating and isolating Lyme disease spirochetes, Borrelia burgdorferi, from the saliva of vector ticks, Ixodes scapularis (formerly known as Ixodes dammini), is described. Saliva was collected from partially engorged ticks after application of pilocarpine to induce salivation. B. burgdorferi was isolated from 8 of 14 (57%) of the saliva samples derived from ticks infected with the bacteria, as determined by direct immunofluorescent-antibody assay of tick hemolymph. A comparison of the protein profiles of the salivary isolates and a highly passaged strain (B31) showed that the salivary isolates all lacked a 22-kDa protein known to increase with continuous passage, but exhibited larger amounts of the OspA and OspB proteins than did the highly passaged B31 strain.

Animals↗
PubMed1994

Hand washing frequency in an emergency department.

Objectives Previous studies, conducted mainly in ICUs, have shown low compliance with hand-washing recommendations, with failure rates approaching 60%. Hand washing in the emergency department has not been studied. We examined the frequency and duration of hand washing in one emergency department and the effects of three variables: level of training, type of patient contact (clean, dirty, or gloved), and years of staff clinical experience. Design Observational. Setting ED of a 1100-bed tertiary referral, central city, private teaching hospital. Participants Emergency nurses, faculty, and resident physicians. Participants were informed that their activities were being monitored but were unaware of the exact nature of the study. Interventions An observer recorded the number of patient contacts and activities for each participant during 3-hour observation periods. Activities were categorized as either clean or dirty according to a scale devised by Fulkerson. The use of gloves was noted and hand-washing technique and duration were recorded. A hand-washing break in technique was defined as failure to wash hands after a patient contact and before proceeding to another patient or activity. Results Eleven faculty, 11 resident physicians, and 13 emergency nurses were observed. Of 409 total contacts, 272 were clean, 46 were dirty, and 91 were gloved. Hand washing occurred after 32.3% of total contacts (SD, 2.31%). Nurses washed after 58.2% of 146 contacts (SD, 4.1%), residents after 18.6% of 129 contacts (SD, 3.4%), and faculty after 17.2% of 134 contacts (SD, 3.3%). Nurses had a significantly higher hand washing frequency than either faculty (p < 0.0001) or resident physicians (p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cooperative Behavior↗
PubMed1993

Site-directed mutagenesis of the yeast mitochondrial ADP/ATP translocator. Six arginines and one lysine are essential.

The ADP/ATP translocator mediates adenine nucleotide exchange across the inner mitochondrial membrane. ADP/ATP exchange is essential when yeast are grown on a non-fermentable carbon source such as glycerol, but it is not required for growth on glucose. Failure to grow on glycerol is therefore a phenotypic indicator of protein function, and it has been used here to screen site-directed mutants to identify functionally important amino acids in the yeast adenine nucleotide translocator (AAC2). Single mutations of all four charged amino acids in the transmembrane segments of AAC2 (K38A, R96D, R96H, R96L, R96P, R204L, R294A) resulted in loss of function, as did mutations in the matrix arginine cluster (R252I, R253I, R254I). Seven other residues were mutated without affecting growth on glycerol (C73S, C244S, C271S, K179M, K182I, P247G, W235F). The non-functional mutants have been used to select intragenic suppressors to gain further insight into the structure of this membrane transport protein.

Amino Acid Sequence↗
PubMed1993

Function-based mapping of the yeast mitochondrial ADP/ATP translocator by selection for second site revertants.

Structure-function relationships in the yeast adenine nucleotide carrier (AAC2) were probed by genetic selection techniques in Saccharomyces cerevisiae. As described in the preceding paper, yeast require a functional AAC2 (or AAC1) to grow on a non-fermentable carbon source. Mutants of AAC2 that could not grow on glycerol were subjected to selection for spontaneous suppressors. Ile mutants in the 100% conserved matrix Arg triplet R252 to R254 proved amenable to this approach, yielding colonies on glycerol plates at modest frequency. All mutants analyzed were single point mutations within the AAC2 gene at a different site than the Arg cluster. R254I gave the largest number (11) of unique revertants, while R253I gave only four and R252I gave none, thus, there was a gradient of effect in mutations of the Arg cluster. Unexpectedly, 14 of the 15 revertant mutations affected 13 different amino acids in a narrow sector of the AAC2 topological map, near the cytosolic surface. These mutants are proposed to be in, or very near, the membrane on the opposite side from the matrix Arg cluster. Helical wheel projections of the transmembrane segments show, with one exception, that mutations and charged residues fall within half of each helix. These mutants appear either to line the throat of the membrane channel, or to be involved in helix contacts near the cytosolic face of the inner mitochondrial membrane. These suppressors place further limitations on the organization of the nucleotide channel. We present a model of the AAC2 nucleotide channel based on these results. The region defined by these suppressors is dynamically linked to the Arg cluster through the function of the AAC2 protein. Discrete structures defined by multiple revertant mutations will likely be a common feature of similar regain-of-function schemes, especially when applied to membrane transport proteins. We propose these functionally mapped regions of proteins be named morphological units or morphs for short.

Amino Acid Sequence↗