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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
PubMed1991

Obesity in Mexican-American preschool children--a population group at risk.

This research built on our previous work focusing on the Mexican-American population as one group at risk for the development of obesity. The purpose of this study was to explore the relationship among knowledge of nutrition, feeding practices, values, and select demographic variables of Mexican-American mothers and obesity in their preschool children. One hundred forty-three mothers of children were recruited to participate. Each mother was interviewed and asked to complete questionnaires regarding maternal nutrition knowledge, maternal feeding practices, weight locus of control, and ideal infant body habitus. Compared to thin infants and their mothers, obese children had a significantly greater mean birth weight and their mothers had a significantly greater body mass index. Analysis of responses to the ideal infant body habitus scale revealed that mothers of obese children selected a chubby baby as ideal significantly more often than mothers of nonobese children. The data collected from this study can alert public health nurses to children at risk for obesity.

Chi-Square Distribution↗
PubMed1991

Self-reported eating disorders of black, low-income adolescents: behavior, body weight perceptions, and methods of dieting.

This study identified black, low-income adolescents who thought they had anorexia nervosa or bulimia nervosa, identified behaviors common to those who thought they had the disorders, and compared their actual and perceived body weight as well as methods of dieting. Of the 1,930 students in grades 7-12 who participated, about 12% thought they might have an eating disorder. These students also reported having food-related behaviors similar to individuals with eating disorders and which differed significantly from those reported by their peers. Gender was more likely to affect food behavior than age. Though most students were within their expected weight range, those with self-reported eating disorders perceived themselves to be heavier more often than their peers and when their actual weights were compared, they were more likely to weigh more. Of those who had dieted to lose weight, fasting was the most frequently reported restrictive method used.

Adolescent↗
PubMed1991

Interleukin-7 retroviruses transform pre-B cells by an autocrine mechanism not evident in Abelson murine.

In this study, we have constructed retroviral vectors expressing the interleukin-7 (IL-7) cDNA and have used infection with these retroviruses to express this cytokine endogenously in an IL-7-dependent pre-B-cell line. Infection with IL-7 retroviruses, but not with a control retrovirus, resulted in the conversion of the cells to IL-7 independence. The frequency at which this occurred, together with data on vector expression levels, indicated that secondary events were required for factor independence in this system. Southern analysis showed that the IL-7-dependent clones harbored unrearranged copies of the vector proviruses. The factor-independent cells produced variable quantities of IL-7 as measured by an IL-7-specific bioassay, and their proliferation could be substantially inhibited by a neutralizing antibody directed against IL-7, indicating that a classical autocrine-mechanism was responsible for their transformation. These IL-7-independent cells were tumorigenic, in contrast to the parental IL-7-dependent cells or those infected with a control vector. These results showed that IL-7 could participate in the malignant transformation of pre-B cells. However, neither of two Abelson murine leukemia virus (A-MuLV)-transformed pre-B-cell lines expressed detectable IL-7 mRNA, at a level of sensitivity corresponding to less than one molecule of mRNA per cell. Moreover, the proliferation of the A-MuLV transformants was unaffected by addition of the IL-7 antisera under conditions in which parallel experiments with IL-7 virus-infected cells resulted in greater than 70% growth inhibition. Thus, transformation of pre-B cells by A-MuLV was not associated with a demonstrable autocrine loop of IL-7 synthesis. These results show that IL-7 can participate in the malignant transformation of pre-B cells and suggest studies aimed at assessing the role of autocrine production of IL-7 in the generation of human leukemias and lymphomas.

Animals↗
PubMed1991

Superoxide dismutase polyethylene glycol improves survival in hemorrhagic shock.

Oxygen free radicals are known to form after reperfusion of ischemic tissue. To test the role and importance of oxygen free radicals in hemorrhagic shock, an animal model of hemorrhagic shock and resuscitation was utilized. Sprague-Dawley rats were anesthetized with halothane and then subjected to approximately 50 per cent blood volume hemorrhage (30 cc/kg), followed by a 60 min shock period. Resuscitation was performed over 1 hour with lactated ringers (LR) at a volume of two times blood loss (60 cc/kg). This model results in a survival rate of 25 per cent over 72 hrs. Using this model, animals were randomized to receive either LR, Superoxide Dismutase-Polyethylene Glycol (SOD-PEG) (15,000 units/kg) with LR or Catalase-Polyethylene Glycol (CAT-PEG) (175,000 units/kg) with LR. The group treated with SOD-PEG demonstrated significantly increased survival rates vs the group treated with LR (67% vs 25%, P = 0.02). The group treated with CAT-PEG demonstrated no significant improvement in survival when compared to the LR-treated group (20% vs 24%). These data suggest that treatment directed toward oxygen free radicals and reperfusion injury may play an important role in hemorrhagic shock resuscitation.

Animals↗
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

Starlings as herbalists: countering parasites and pathogens.

The avian nest protection hypothesis explains the widespread behavior of incorporating fresh green plant material into an otherwise dry nest matrix as an evolutionary adaptation. Species that exhibit this behavior tend to breed in previously inhabited nest sites and experience high ectoparasite and pathogen loads. Metabolites in the green plants control parasite and pathogen populations and decrease the effects of these agents on nestlings. The choice of plants is not arbitrary. In the case of European starlings, a nonrandom subset of available vegetation is selected, and it is these plants that have the largest impact on ectoparasite and pathogen populations. Experimental and observational evidence suggests that starlings select plants on the basis of chemosensory cues.

Journal Article↗
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↗