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Biomedical subjects

L Clark

Publications and source records attributed to L Clark.

At least 109 records · Page 6Linked to original sources
PubMed1990

Effects of dietary wheat bran fiber on rectal epithelial cell proliferation in patients with resection for colorectal cancers.

A preponderance of carcinogenesis studies in rodents and epidemiologic studies in humans suggests a potential role of dietary fiber in the prevention of colorectal cancer. Recently, wheat bran fiber used as a dietary supplement has been shown to decrease the growth of rectal adenomatous polyps in patients with familial polyposis; however, few studies of high-risk human populations have been attempted to determine the effects of dietary fiber supplementation on markers of carcinogenesis in the colon or rectum. We have designed a one-arm study to evaluate the effects of dietary supplementation with wheat bran fiber [i.e., 13.5 g/day for 8 wk; after 1 mo, 2 g/day (compliance evaluation period)] on [3H]thymidine rectal mucosa cell labeling (i.e., percent of epithelial cells incorporating [3H]thymidine into DNA in intact rectal crypt cells over a 90-min exposure as well as in minced rectal biopsy tissue over a 24-hr exposure) in rectal biopsy specimens. The biopsy specimens were obtained at sigmoidoscopy in 17 compliant patients with a history of resected colon or rectal cancer. We categorized patients as having initially low or initially high [3H]thymidine-labeling indices (i.e., percent of mucosa cells that incorporate [3H]thymidine into DNA during 1.5- or 24-hour in vitro incubations) by using the median baseline labeling index as a cutoff between high and low values. On the basis of a chi-square test used to identify patients with a statistically significant (P less than .001) change, six of the eight patients who initially had high 24-hour outgrowth labeling indices showed a significant decrease in the rectal mucosa biopsy specimens obtained after treatment. An overall 22% decrease was observed in rectal mucosa cell biopsy specimens obtained at study termination (P less than .001). Of the eight patients with initially high total [3H]thymidine-labeling indices in crypt organ culture, four had a significant (P less than .001) decrease from baseline values, one had a significant increase, and three showed no change following the fiber intervention. The wheat bran fiber dietary supplement of 13.5 g/day was well tolerated by this group of older (54-70 yr) patients. Although the [3H]-thymidine labeling index data suggest that the wheat bran fiber supplement can inhibit DNA synthesis and rectal mucosa cell proliferation in high-risk patients, the results of this small pilot study should not be overinterpreted vis à vis the potential role of wheat bran fiber as a chemopreventive agent for colorectal cancer.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1990

Seasonal shifts in odor acuity by starlings.

A passerine bird, the European Starling Sturnus vulgaris, demonstrated a seasonal ability to respond to odor cues. Cardiac conditioned responses were most evident when birds were in breeding condition. Once birds were in nonbreeding condition, responding to odors all but ceased. For birds in breeding condition, threshold sensitivity to the odor cyclohexanone was comparable to levels reported for nonpasserine birds (0.3% vapor saturation or 3.778 x 10(14) molecules/ml). In contrast, the threshold level during the postreproductive phase of the annual cycle was 10% vapor saturation (1.256 x 10(16) molecules/ml), a level high enough to implicate the trigeminal system as the modality mediating chemosensory perception. The strong cyclic responding pattern suggests links between photoperiodically controlled endocrine production, breeding behavior, and olfactory sensitivity.

Analysis of Variance↗
PubMed1990

Quantitation of vitamin K in human milk.

A quantitative method was developed for the assay of vitamin K in human colostrum and milk. The procedure combines preparative and analytical chromatography on silica gel in a nitrogen atmosphere followed by reversed phase high performance liquid chromatography (HPLC). Two HPLC steps were used: gradient separation with ultraviolet (UV) detection followed by isocratic separation detected electrochemically. Due to co-migrating impurities, UV detection alone is insufficient for identification of vitamin K. Exogenous vitamin K was shown to equilibrate with endogenous vitamin K in the samples. A statistical method was incorporated to control for experimental variability. Vitamin K1 was analyzed in 16 pooled milk samples from 7 donors and in individual samples from 15 donors at 1 month post-partum. Vitamin K1 was present at 2.94 +/- 1.94 and 3.15 +/- 2.87 ng/mL in pools and in individuals, respectively. Menaquinones, the bacterial form of the vitamin, were not detected. The significance of experimental variation to studies of vitamin K in individuals is discussed.

Adult↗
PubMed1990

Human antral damage induced by alcohol is potentiated by enprostil.

Enprostil, a synthetic analogue of prostaglandin E2, has been shown to protect the human gastroduodenal mucosa from aspirin injury. This study was designed to determine if enprostil protected against alcohol damage. A double-blind, randomized, cross-over study was performed on eight healthy adult men. After an overnight fast, a gastroscope was inserted and the antral mucosa was sprayed with a 10-mL test solution containing either enprostil (70 micrograms) or its vehicle (control). After 15 minutes, mucosal injury was scored (0-5), and the mucosa was sprayed with 100 mL 80% ethanol. Mucosal injury was scored after a further 15, 20, 25, and 30 minutes. The entire experiment was recorded on video film, which a second endoscopist used to score the damage independently. The two experiments were separated by an interval of 1 week. There was close agreement between the two endoscopists (r = 0.9385), and their scores were averaged. Using Friedman's two-way analysis of variance, a highly significant (P less than 0.00004) increase in injury was demonstrated following enprostil pretreatment. The Wilcoxin signed rank test showed the differences to be significant (P less than 0.05) at every time point. We conclude that enprostil, rather than protecting the human antral mucosa from alcohol injury, appears to potentiate this injury and may itself be damaging in therapeutic concentrations. This unexpected result cannot yet be explained but demands caution in the clinical use of enprostil.

Adult↗
PubMed1990

Spinal opioids: a nursing perspective.

Nursing care of the patient receiving spinal opioids for pain control is reviewed in a comprehensive manner. Selection of patients, nursing management and patient outcomes are discussed. Three pain control techniques are described: epidural opioid injection for cancer pain, epidural opioid infusion for acute postoperative pain, and single dose spinal opioids for postcesarean section pain. Monitoring and pharmacologic aspects common to all three forms of spinal opioid treatment are given, and specific nursing interventions for each therapy are delineated.

Analgesia, Epidural↗
PubMed1990

Cost-effectiveness analysis of paramedic emergency medical services in the treatment of prehospital cardiopulmonary arrest.

STUDY OBJECTIVES: 1) Identification of marginal costs associated with prehospital resuscitation of cardiopulmonary arrest; 2) Determination of cost effectiveness for such resuscitation; and 3) Comparison of cost effectiveness of paramedic care with selected other medical interventions. DESIGN: Retrospective review of 190 cases of out-of-hospital cardiac arrest. SETTING: City limits of a midsized southwestern city. The events studied took place outside of medical facilities. TYPE OF PARTICIPANTS: Victims of out-of-hospital cardiac arrest for whom the EMS system was activated by a 911 telephone request for emergency medical assistance. MEASUREMENTS AND MAIN RESULTS: The cost, including training, personnel, equipment, and response time maintenance, per year of life saved was found to be $8,886.00 for paramedic care. This result was compared with published cost-effectiveness figures for heart transplantation, liver transplantation, bone marrow transplantation, and chemotherapy for acute leukemia. Paramedic care was more cost effective, as measured by cost per year of life saved, than organ transplantation and chemotherapy for acute leukemia. CONCLUSION: Out-of-hospital treatment by paramedics of cardiopulmonary arrest is more cost effective than heart, liver, bone marrow transplantation, or curative chemotherapy for acute leukemia.

Arizona↗
PubMed1990

Interaction of enhancer-binding protein EBP1 (NF-kappa B) with the human immunodeficiency virus type 1 enhancer.

Human EBP1, isolated from HeLa cells, binds to a 10-base-pair (bp) sequence in cellular and viral enhancers that is also recognized by the inducible transcription factor NF-kappa B. Here we describe the interaction of purified EBP1 with the 10-bp repeated sequence that is responsive to signals which activate T cells and which form part of the human immunodeficiency virus type 1 (HIV-1) enhancer. DNase I footprinting indicates that both 10-bp sites on the same molecule, located between -80 and -105 on the HIV-1 long terminal repeat, can be occupied by EBP1, while dimethyl sulfate protection and methylation interference experiments indicate which purine bases are in contact with the protein. The presence of bases which exhibit increased rates of dimethyl sulfate-induced methylation in the presence of EBP1 indicate that interaction of EBP1 with its recognition site is accompanied by distortion of the DNA double helix. Supporting this conclusion is the observation that the polyamine spermidine dramatically increases EBP1 binding to its cognate site on the DNA. Studies with human T cells (Jurkat) and nucleotide stimulation data suggest that EBP1 is the activated form of NF-kappa B in these cells.

Base Sequence↗
PubMed1989

Enhancer binding protein (EBP1) makes base and backbone contacts over one complete turn of the DNA double helix.

The simian virus 40 (SV40) enhancer consists of multiple DNA sequence motifs that represent the binding sites for a large number of trans-acting factors. We have purified one such factor, EBP1, which binds to a region encompassing the "core" of the SV40 enhancer, and appears to be involved in transcriptional activation. The interaction of EBP1 with its recognition site has been analysed by nuclease protection and by a variety of chemical probes. Enhancer sequences protected from cleavage with DNase I in the presence of EBP1 extend from position 232 to 250 on one strand and from 233 to 251 on the other strand. Methylation protection and alkylation interference studies have identified purine bases and backbone phosphate groups that participate in the formation of a specific EBP1-DNA complex. Within a ten base-pair region, every purine base interferes with binding when methylated and six phosphate groups on each strand interfere with binding when the attached oxygen groups are ethylated. "Footprinting" with hydroxyl radicals, generated by the 1,10-orthophenanthroline-copper ion, revealed sugar residues in the binding site that were protected from cleavage in the presence of EBP1. Computer graphics analyses of the contact point data indicate that EBP1 makes base and backbone contacts with the DNA over one complete turn of the DNA double helix, and suggest a model in which EBP1 makes sequence-specific contacts in the major groove, although binding may be influenced by interactions in the minor groove. Comparison of the EBP1 contact points with that of other known DNA-binding proteins indicates that EBP1 employs a unique mechanism to recognize a specific DNA sequence.

Base Sequence↗
PubMed1989

Sequence requirement for specific interaction of an enhancer binding protein (EBP1) with DNA.

Short DNA sequence motifs have been identified in viral and cellular enhancers which represent the binding sites for a variety of trans- acting factors. One such HeLa cell factor, EBP1, has been purified and shown to bind to sequences in the SV40 enhancer. The PRDII element in the human beta-interferon gene regulatory element (IRE) shows strong sequence similarity to the EBP1 binding site in the SV40 enhancer. We demonstrate here that EBP1 binds to its sites in the SV40 enhancer and IRE in a similar manner, making base specific contacts over one complete turn of the DNA double helix. Mutational analysis of the EBP1 sites in the IRE and SV40 enhancer has identified the DNA sequence requirements necessary for specific EBP1/DNA complex formation. In addition, 34 DNA sequences related to the EBP1 binding site were analysed for their ability to bind EBP1. Sequences constituting high affinity binding sites possess the sequence 5'-GG(N)6CC-3'. Single base pair changes in the region between the conserved Gs and Cs can generally be tolerated although it is clear that these intervening bases contribute to binding affinity. Mutations in the recognition site which could lead to gross structural changes in the DNA abolish EBP1 binding.

Animals↗
PubMed1989

A randomized trial of laparoscopy and transvaginal ultrasound-directed oocyte pickup for in vitro fertilization.

Ninety-four (94) couples undergoing IVF for the usual spectrum of clinical reasons and who were suitable for either laparoscopic or vaginal ovum pickup (OPU) were randomly assigned at the commencement of 166 treatment cycles to one of two OPU procedures. Both patient and clinician were informed of the allocation. If either wished to change this, then that cycle was eliminated from the trial. After a period of 15 months, 103 cycles were appropriate for analysis, of which 64 had been subject to ultrasound and 39 to laparoscopic OPU. Patients in the two groups did not differ significantly in terms of age or diagnosis, and the treatment cycles did not differ significantly in terms of stimulation used, commencing or maximum estradiol (E2) concentrations, E2 per follicle aspirated, or characteristics of the semen used for IVF. The rate of oocyte recovery (number of oocytes obtained per follicle aspirated), the average number of embryos available for transfer, and the pregnancy rate per oocyte recovery procedure did not differ significantly in the two groups. Ovum recovery for IVF using vaginal aspirations and ultrasound guidance is as efficacious as that which uses laparoscopy.

Female↗
PubMed1989

Evaluation of a worksite wellness program: impact on exercise, weight, smoking, and stress.

This study evaluated the effects of a wellness program at the workplace in relation to its impact on exercise, weight, smoking, and stress of the employee participants. A quasi-experimental design was selected in which data were collected at three specific intervals: before and immediately after program completion, and three months after program completion. The sample consisted of experimental and control groups. Persons (n = 59) who did participate in the wellness program made up the experimental group, and those (n = 49) who did not participate in the wellness program served as controls. Descriptive statistics were used to summarize the data. No significant differences were noted between participants and nonparticipants in the areas of exercise, weight, smoking, and stress between the initial evaluation and after completing the wellness program. The areas of stress reduction and increased exercise were emphasized more in the participants than the nonparticipants, however.

Adult↗
PubMed1989

Perceived home care needs of cancer patients and their caregivers.

The purpose of this study was to identify perceived home care needs of outpatients receiving treatment for cancer and their caregivers. The purposive subsample consisted of 16 subjects, 8 patients receiving treatment as outpatients and their 8 caregivers. Two interview guides, one for the patients and the other for their caregivers, were based on the Neuman Systems Model to assess patient and caregiver stressors The data were analyzed in relation to intrapersonal stressors (within the individual), interpersonal stressors (between the individual and others), and extrapersonal stressors (between the individual and the environment) Several stressors within each category were identified by both the patients and caregivers. Intrapersonal stressors included treatment uncertainty and role change, the interpersonal stressor of lack of social support, and the extrapersonal stressors of lack of transportation and limited finances. In addition, patients identified specific intrapersonal stressors in relation to their situation. These included assistance in coping with physical restrictions resulting in subsequent anger and depression. On the other hand, intrapersonal stressors identified by the caregivers included support in coping with the added responsibilities in relation to patient care, the fear of being alone, guilt, and the interpersonal stressor of limited knowledge regarding the patient situation. The stressors identified by both the patients and caregivers can serve as a beginning means to explore the needs encountered by this population group.

Aged↗