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Biomedical subjects

L J Johnson

Publications and source records attributed to L J Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effects of nicotine on the immune response. I. Chronic exposure to nicotine impairs antigen receptor-mediated signal transduction in lymphocytes.

Previous work has demonstrated that chronic exposure of rats to cigarette smoke causes inhibition of the antibody-forming cell (AFC) response and that the particulate phase of cigarette smoke, containing most of the nicotine in cigarette smoke, is essential for immunosuppression. Using intradermally implanted miniosmotic pumps, LEW rats were exposed to nicotine or its principal metabolite, cotinine, at the rate of about 14 micrograms/hr for 3-4 weeks. Serum cotinine levels in nicotine-treated (NT) animals of 219 +/- 40 ng/ml (on Day 10) were comparable to average human smokers. No significant differences between control (CON) and NT animals were observed in the distribution of lymphocyte subsets. However, nicotine, but not cotinine, treatment for 3 to 4 weeks inhibited both the T-dependent and T-independent AFC responses and proliferation to anti-CD3. Con A response was observed in 4-week but not in 3-week NT animals. Cell cycle analysis revealed that upon stimulation with Con A or anti-CD3, in spite of comparable surface expression of IL-2 receptors and class II MHC molecules, significantly fewer NT T cells entered the S and G2/M phases than CON T cells, indicating an arrest in the G0/G1 phase. Furthermore, B and T cells from NT animals were unable to elevate the intracellular calcium levels normally in response to ligation of antigen receptors, although Ca2+ responses of salivary gland cells to acetylcholine were normal. Thus, nicotine may significantly contribute to the immunosuppressive effects of chronic smoking by inducing a state of anergy in lymphocytes and may be related to their impaired response to antigen-induced signaling.

Animals↗
PubMed1994

Weight gain and reproductive performance of spring-born beef heifer calves intraruminally administered oxfendazole.

The effect of oxfendazole (Synanthic) on weight gain and reproductive performance of spring-born heifer calves was evaluated at five locations (IL, IN, MI, MO, ND). Three hundred thirty-eight mixed-breed beef heifers (293.4 kg) blocked by weight and age were randomly allotted to one of two treatments. Treatment 1 heifers were dewormed via intraruminal injection of oxfendazole. Treatment 2 heifers served as a control. Heifers were comingled during the winter phase in semi-confinement during the period from late January to late May (winter phase). Heifers were sorted by treatment at the beginning of the grazing season (approximately May 24, 1991) and remained separate until the end of the study (approximately July 31, 1991; summer phase). Dewormed heifers received oxfendazole (4.5 mg/kg BW) in late January and again 28 and 56 d after the beginning of the grazing season. Fecal samples were taken every 21 d from January through September and assayed for gastrointestinal parasite eggs. Fecal egg counts were similar across treatments at the beginning of the trial (P = .34). Deworming decreased fecal egg counts throughout the trial. Twenty-eight days after initial deworming a significant treatment effect on fecal egg counts was observed (P < .01). Winter ADG was significantly higher (P < .01) for dewormed heifers than for controls (.60 vs .52 kg, respectively). Summer ADG was not different between treatments. Dewormed heifers were 7.4 kg heavier than controls (P < .05) at the end of the trial. Age of puberty was not affected by treatment (P = .64). First-service conception and final pregnancy rates were not different between treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Nutrition and wound healing.

Wound healing is a complex process following injury that ideally will end in complete restoration of the damaged tissue and function. Nutrition is one of the most important determinants in successful wound healing. Proper identification of nutritional deficiencies and rapid intervention will increase the chances of successful wound closure.

Humans↗
PubMed1991

Effect of ammonium carbamate on nutritive and preservative characteristics of high-moisture coastal bermudagrass hay.

Two studies evaluated the effects of ammonium carbamate (AC) on preservation and digestibility of high-moisture (HM) Coastal bermudagrass (Cynodon dactylon) hay. A 3 X 7 factorial arrangement of treatments in a completely random design was used to estimate the efficacy of AC in laboratory conditions. Treatments were 25, 30, or 35% moisture (M) forage treated with levels (L) of 0, 1.14, 2.28, 3.42, 4.56, 5.70, or 6.84% AC. Nitrogen in forage increased (P less than .01) linearly due to M and L. There was a linear decrease (P less than .01) in ADF N due to M. Neutral detergent fiber decreased (P less than .01) linearly as M increased and increased (P less than .01) linearly with increased L. Acid detergent fiber decreased (P less than .01) linearly due to L. There was an M X L interaction (P less than .01) for hemicellulose (HC) concentrations and total aerobic fungal counts. The digestibility of HM hay treated with a product (ACNH) containing 57% AC was compared to that of untreated hay (UH) and UH plus urea (UHU) when fed to lambs (four lambs per treatment). Digestibility of NDF and hemicellulose (P less than .01) and ADF (P less than .05) was increased for ACNH forage compared with UH or UHU. Ammonium carbamate seems to be beneficial for preserving HM forage, and an admixture containing ammonium carbamate is effective for increasing the digestibility of Coastal bermudagrass hay.

Analysis of Variance↗
PubMed1990

Strategic management: a new dimension of the nurse executive's role.

The growth of corporate orientation for health care structures, with a focus on bottom-line management, has radically altered the role of nurse executives. With the organization's emphasis on performance, productivity, and results, successful nurse executives are now integrating the management of the delivery of nursing care with the management of complex corporate structures and relationships. The editor of Executive Development discusses the rapidly changing expectations and demands of the contemporary nurse executive's work. The nurse executive's role can be viewed from many perspectives: its scope, its value, its structure, its content. Content--"What does the nurse executive do that makes a real difference?"--is the focus here.

Administrative Personnel↗
PubMed1990

The influence of assumptions on effective decision-making.

In a competitive health care environment, the effectiveness of a nurse executive's decisions is enhanced by the use of a systemic set of assumptions. The author explains why this theory of decision-making is important, shows how three sets of assumptions manifest themselves in nursing administration practice, and presents a case study to show how nurse executives can use this theory to improve the effectiveness of their decisions.

Administrative Personnel↗
PubMed1989

The Maine State Patient Education Forum: networking system for a rural area.

Patient education councils are growing and prospering. The Maine State Patient Education Forum is one such council which has gone through a continuing developmental process to meet needs of patient educators in Maine. Involving many organizations and individuals who do patient education, having a clear direction and a common locus, scheduling regular meetings, and participating in national networking have all been ways to vitalize and strengthen the council. Maine as a rural state has found the forum to be a dynamic model to motivate patient educators to maintain flexibility and acquire new concepts so they can continue to provide high quality patient education services.

Health Planning Councils↗
PubMed1989

Evaluation of vitamin K3 feed additive for prevention of sweet clover disease.

Sweet clover poisoning in cattle is caused by an anticoagulant (dicumarol) that is formed in moldy sweet clover hay. Previous experiments with vitamin K3 and vitamin K1 in therapy trials indicated that vitamin K1 was effective in reducing prothrombin times but vitamin K3 was not. As a possible alternative in the use of toxic sweet clover hays, vitamin K3 was evaluated to see if it would prevent hemorrhagic crises when fed to cattle consuming toxic sweet clover hay. Vitamin K3 levels of 0, 0.45, 4.5, 11, and 45 mg/kg body weight/day were fed to 173-235-kg steers consuming toxic (40-50 ppm dicumarol) sweet clover. The 45-mg K3/kg/day supplement was not palatable and had to be discontinued. The 0.45, 4.5, and 11-mg K3/kg/day supplements did not significantly reduce the prothrombin times as compared to the 0-mg K3/kg/day group.

Animals↗
PubMed1985

Vitamin K treatment of sweet clover poisoning in calves.

Dicumarol poisoning was reproduced by feeding naturally spoiled, sweet clover hay, which contained a minimum of 90 ppm dicumarol. Vitamin K1 administered IM was effective in treating the disease at dosages of 1.1, 2.2, and 3.3 mg/kg of body weight. Vitamin K3 treatment by various routes and dosages was ineffective.

Animals↗
PubMed1985

Auditory stimulation, rhythm, and stuttering.

In a previous experiment, Martin, Siegel, Johnson, and Haroldson (1984) found that stutterers reduced their stuttering under amplified sidetone, but only if the amplified sidetone condition had been preceded by a condition of speaking in noise. The authors speculated that when stutterers were exposed initially to loud noise and its attendant reduction in stuttering, they became "sensitized" to reduced stuttering in any subsequent condition where their auditory feedback was modified. The current experiment tested that hypothesis with 24 adult stutterers divided evenly into three groups. One group of stutterers spoke with no auditory stimulation (quiet), then while receiving 100 dB SPL white noise, and then while receiving amplified sidetone (0, +10, +20 dB SPL). A second group spoke in quiet, then while receiving amplified sidetone, and then while receiving amplified sidetone again. A third group spoke in quiet, then while receiving rhythmic stimulation, and then while receiving amplified sidetone. Relative to vocal intensity in quiet, stutterers spoke with increased vocal intensity during noise, with decreased vocal intensity during amplified sidetone, and with no significant change in vocal intensity during rhythmic stimulation. Relative to stuttering frequency in quiet, subjects spoke with decreased stuttering frequency during loud noise and during amplified sidetone, but only when the amplified sidetone was preceded by the loud noise condition. These results are discussed in terms of the "sensitization" hypothesis.

Acoustic Stimulation↗
PubMed1984

Sidetone amplification, noise, and stuttering.

In the present study, 24 stutterers and 24 matched nonstutterers spoke spontaneously under conditions of quiet, noise (60, 80, 100 dB SPL re .0002 dynes/cm2), and amplified sidetone (0, +10, +20 dB SPL re .0002 dynes/cm2). All 24 stutterers and 23 of the 24 nonstutterers experienced a decrease in vocal intensity from quiet to 20 dB amplified sidetone. All the nonstutterers and 23 of the stutterers experienced an increase in vocal intensity from quiet to 100 dB noise. As a group, the stutterers experienced a significant decrease in stuttering in the noise conditions; however, with regard to the amplified sidetone conditions, only those stutterers who experienced noise first showed a significant reduction in stuttering during amplified sidetone.

Acoustic Stimulation↗
PubMed1982

Alteration in immune complex glomerulonephritis by arachidonic acid.

We employed a model of immune complex glomerulonephritis produced in mice by the daily injection of apoferritin to study the effect of treatment with arachidonic acid (AA). Apoferritin injections produced demonstrable glomerular damage by light microscopy associated with deposition of immunoglobulin along peripheral capillary loops. Treatment with AA 100 micrograms daily resulted in significantly less glomerular damage and a shift inthe location of immune complex deposition to the mesangium. The amount of anti-apoferritin antibody was determined by hemagglutination and found to be significantly decreased in mice treated with AA. Separate studies employing this dose of AA revealed that the number of IgM antibody producing cells to SRBC was not altered by AA.

Animals↗
PubMed1982

Effect of suckling on pituitary responsiveness to gonadotropin-releasing hormone throughout the early postpartum period of beef cows.

The objective of this study was to compare pituitary responsiveness to gonadotropin-releasing hormone (GnRH) throughout the early postpartum period (PP) in beef cows suckling in single calf vs cows which had calves removed at birth. The experiment utilized 48 cows in a 2 X 4 factorial. Main effects studied were suckling status (suckled or nonsuckled) and days PP (d 3, 10, 20 or 30). Covariates studied were pre-treatment concentrations of progesterone (P), estradiol-17 beta (E), luteinizing hormone (LH) and follicle stimulating hormone (FSH). Suckled (S) cows nursed one calf, while nonsuckled (NS) cows had calves removed at birth. Treatment was a single im injection of 100 micrograms GnRH dissolved in saline. Pre-GnRH plasma concentrations of E, P, LH and FSH and post-treatment plasma concentrations of LH and FSH were determined at 15 min intervals (-30 to 360 min) in blood samples collected via jugular cannulae. Post-treatment plasma concentrations of P were determined at 6 (n = 23) or 8 (n = 23) days after treatment to monitor ovarian response. Concentrations of E, LH and FSH before GnRH injection did not differ (P greater than .1) between S and NS cows at any PP stage and data were pooled for statistical analyses. Pre-treatment LH, but not FSH, increased (r = .43; P less than .002 (with days PP and concentrations of LH were greater (P less than .05) at 30 d than at 3 d PP. Pre-treatment P was greater (P less than .05) in NS than in S cows on d 30 PP and P was correlated (r = .51; P less than .01) with days PP in NS cows. However, the frequency of cows exhibiting plasma P greater than or equal to 1 ng/ml prior to GnRH was low on all days studied and was similar for both groups. LH release after GnRH was correlated with increasing days PP in both S (r = .73; P less than .001) and NS (r = .61; P less than .002) cows, Releasable FSH was not related to days PP in either group. Mean peak LH and total LH released were greater (P less than .025 and P less than .05), respectively) in S than in NS cows at 30 d PP. Mean peak FSH and total FSH released were greater (P less than .05 and P less than .07, respectively) at 10 and 30 d PP in S cows than in NS cows. Pre-treatment E, but no P, LH or FSH was positively related (P less than .01) to GnRH-mediated LH release in both groups. When pre-treatment E was partitioned into separated regressions for S (ES) and NS (ENS) cows, increased pituitary LH response in S cows on d 30 appeared to be due in part to a greater sensitivity of S cows to E modulation. We found no evidence to suggest that pituitary responsiveness per se is decreased in beef cows suckling a single calf.

Animals↗
PubMed1981

Occurrence and range of dicumarol concentrations in sweet clover.

The dicumarol concentration in 272 cured sweet clover samples from 4 counties in North Dakota was determined. Dicumarol concentrations ranged from 0 to 164.7 mg/kg of sweet clover, with 64.6% of the 272 samples containing less than 10 mg/kg. Round bales were significantly (P less than 0.05) higher in dicumarol concentration (mean of 22.9 +/- 3.10 mg/kg) than were stacks or silage (means of 1.8 +/- -6.3 mg/kg and 0.6 +/- 2.1 mg/kg, respectively). The outer section of core samples taken from round bales contained significantly (P less than 0.0021) higher concentrations of dicumarol than did the inner section of the core, with means of 30.8 mg/kg and 16.6 mg/kg, respectively. A significant (P less than 0.0001) correlation existed between crude protein and dicumarol values (r = 0.44).

Animal Feed↗
PubMed1980

The effects of allowing participants in a juvenile drug program to extend their participation in the program.

The practice of allowing juvenile participants in a drug intervention program to extend their participation in the program was examined. The program's therapists felt that such additional participation would be therapeutically beneficial to the juveniles, but at the same time it would deny other juveniles entrance into the program. The results suggest that the practice of allowing participants to attend additional groups in programs which are rather highly structured is not beneficial, and in some cases may result in a loss of the gains made during the initial group.

Adolescent↗
PubMed1980

Bone-seeking properties of Tc-99m carbonyl diphosphonic acid, dihydroxy-methylene diphosphonic acid and monohydroxy-methylene phosphoinic acid: concise communication.

Carbonyl diphosphonic acid, dihydroxy-methylene diphosphonic acid and monohydroxy-methylene diphosphonic acid were synthesized and labeled with Tc-99m. Their chemical structures were confirmed and their bone-seeking relationships were compared with those of Tc-99m MDP in experimental animals. MKonohydroxy-methylene diphosphonic acid was found to have higher bone affinity and faster blood clearance than MDP, whereas carabonyl diphosphonic acid and dihydroxy-methylene diphosphonic acid demonstrated lower bone affinity and slower blood clearance than MDP.

Animals↗
PubMed1978

Effects from past solid waste disposal practices.

This paper reviews documented environmental effects experience from the disposal of solid waste materials in the U.S. Selected case histories are discussed that illustrate waste migration and its actual or potential effects on human or environmental health. Principal conclusions resulting from this review were: solid waste materials do migrate beyond the geometric confines of the initial placement location; environmental effects have been experienced from disposal of municipal, agricultural, and toxic chemical wastes; and utilization of presently known science and engineering principles in sitting and operating solid waste disposal facilities would make a significant improvement in the containment capability of shallow land disposal facilities.

Environmental Pollution↗