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Biomedical subjects

R W Johnson

Publications and source records attributed to R W Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1993

Central and peripheral prostaglandins are involved in sickness behavior in birds.

Many of the behavioral manifestations of mammals and birds following infection are now recognized as important mechanisms for maintaining homeostasis and promoting recovery. To investigate the role of prostaglandins (PGs) in the behavioral and physiological effects of lipopolysaccharide (LPS) in birds, chickens were injected with indomethacin (Ind) peripherally (IP, 5 mg) or centrally (ICV, 100 micrograms) and their behavior and body temperature following a challenge IP injection of LPS (2.5 mg) were assessed at 1 and 2 h, respectively. Pretreatment with Ind IP or ICV completely inhibited the hyperthermia caused by LPS. Ind injected IP but not ICV significantly attenuated the LPS-induced anorexia. The drowsiness caused by LPS was completely inhibited by Ind injected IP and partially inhibited by Ind administered ICV. These results are interpreted to indicate that LPS induces hyperthermia in the chicken by activating a PG system in the brain. Peripheral PGs appear to be involved in the anorectic response to LPS, whereas drowsiness caused by LPS may involve both peripheral and central PGs. These data are consistent with the hypothesis that multiple PG systems are activated during the acute-phase response, which may explain the dissociation between mechanisms controlling the behavioral and physiological responses to infection.

Animals↗
PubMed1993

Sickness behavior in birds caused by peripheral or central injection of endotoxin.

Recent evidence indicates that many of the physiologic, metabolic, and behavioral responses that accompany infection in mammals are important for maintaining homeostasis and promoting recovery. In the present report, we have extended this concept to birds by demonstrating that LPS injected IP reduces feed intake, increases somnolence, decreases plasma [Fe] and [Zn], increases plasma [Cu], and elevates plasma corticosterone. To determine if any of these effects could be mediated centrally, LPS was injected intracerebroventricularly (ICV). Whereas peripheral injection of LPS caused a modest increase in body temperature, the hyperthermic effect of LPS injected ICV was intense and long lasting. This hyperthermia following ICV injection of LPS was accompanied by only a transient reduction in food intake and elevation in somnolent activity, with no change in plasma [Fe] or [Zn]. Both peripheral and central injections of LPS increased plasma corticosterone, but the increase caused by peripherally administered LPS was sixfold higher than that caused by LPS injected centrally. Collectively, these data show that chickens respond to both peripheral and central injections of endotoxin by reducing food consumption, increasing somnolence, becoming febrile, and elevating plasma corticosterone. However, the magnitude of these responses depends upon whether LPS acts at central or peripheral sites.

Animals↗
PubMed1993

The association between a positive T and B cell flow cytometry crossmatch and renal transplant failure.

Between January 1989 and June 1991 329 consecutive cadaveric renal transplants were carried out at this centre and, of those, 36 (10.9%) have failed. In order to assess whether the use of flow cytometry crossmatching (FCXM) would have predicted these failures, we carried out a retrospective T and B cell FCXM study comparing the failure group with a control group of 30 recipients carefully selected from patients transplanted during the same period. The number of first and second transplants in the control and failure groups was 25,5 and 23,8 respectively with six of the controls and three of the failures having panel reactive lymphocytotoxic antibodies > 50%. Stored donor material was available for 31 of the 36 failures. Two colour FCXM was performed using R-phycoerythrin-conjugated antihuman CD3 and antihuman CD19 to identify T and B cells respectively. For each recipient, three pretransplant and one post-transplant sera were tested against lymphocytes from the recipient's kidney donor. A fluorescein isothiocyanate conjugated F(ab')2 rabbit antihuman IgG was used to detect recipient IgG alloantibodies bound to donor T and/or B cells. There were no T or B cell FCXM positive (+) results in the control group whereas 11 of the 31 (35%) failures overall and nine of the 23 (39%) who failed within three months were T and B cell FCXM+ pretransplant (p = 0.0002). Seven of the nine FCXM+ results in the early failure group were with historic sera and two with historic and current sera.(ABSTRACT TRUNCATED AT 250 WORDS)

B-Lymphocytes↗
PubMed1993

Spontaneous movement of bullets in the brain.

We report two patients in whom bullets in the brain migrated into the adjacent lateral ventricle and moved freely as a consequence of gravity. A review of the literature suggests that the spontaneous migration of intracerebral bullets is influenced by cerebral softening, the specific gravity of the bullet compared with brain tissue, and the sink function of the cerebral ventricles. In patients undergoing the surgical removal of intracerebral or intraventricular bullets, it is recommended that an x-ray be obtained after the final positioning of the head.

Adolescent↗
PubMed1992

Effect of stem water content on sap flow from dormant maple and butternut stems: induction of sap flow in butternut.

Sap flow from excised maple stems collected over the winter (1986/87) was correlated with stem water content. Stem water content was high in the fall (>0.80) and decreased rapidly during 2 weeks of continuous freezing temperatures in late winter (<0.60). Exudation of sap from stem segments subjected to freeze/thaw cycles was small (<10 mL/kg) in the fall, but substantial exudation (45-50 mL/kg) occurred following the decline in water content. These observations are consistent with Milburn's and O'Malley's models (J.A. Milburn, P.E.R. O'Malley [1984] Can J Bot 62: 2101-2106; P.E.R. O'Malley, J.A. Milburn [1983] Can J Bot 61:3100-3106) of sap absorption into gas-filled fibers during freezing. Exudation volume was increased 200 to 300% in maple stems originally at high water content (>0.80) after perfusion with sucrose and dehydration at -12 degrees C. Sap flow was also induced in butternut stem segments after the same treatment. Thus, sap flow may not be unique to maples. Sap flow could not be increased in stem segments dehydrated at 4 degrees C. Migration of water molecules from small ice crystals in fibers to larger crystals in vessels while stems were frozen may account for increase exudation after dehydration at -12 degrees C. This would result in preferential dehydration of fibers and a distribution of gas and sap favorable for stem-based sap flow.

Journal Article↗
PubMed1991

Detection of anti-epithelial cell antibodies in association with pediatric renal transplant failure using a novel microcytotoxicity assay.

We have developed a microcytotoxicity assay allowing sera to be screened for anti-epithelial cell cytotoxic antibodies. Cells from the epithelial cell line A549 were cultured overnight in Terasaki trays prior to the addition of the sera to be screened. Using this assay, 63 pediatric recipients of 78 renal transplants have been studied retrospectively. Seventeen transplants carried out in 13 patients were found to be associated with the production of antibodies reactive only against epithelial cells (AEC). Eleven of these transplants failed as compared with 19 failures out of 52 transplants not associated with AEC production (Fisher's p = 0.04). We conclude that transplantation in the face of pre-existing AEC should be approached with caution.

Autoantibodies↗
PubMed1991

Effects on chick performance of ammonia and heat stressors in various combination sequences.

The purpose of the present study was to evaluate the effects of previous experience with a stressor on chicks' subsequent performance when exposed later to the same stressor or to a different stressor. Performance was measured in chicks exposed to aerial ammonia, environmental heat, or both in reciprocal sequences in two consecutive periods. Four (2 x 2 factorial) treatment combinations of ammonia [0 ppm (a) or 125 ppm (A)] and heat [30 C (h) or 36.5 C (H]) stressors were imposed in each of two consecutive 4-day periods, giving a total of 16 treatments. Weight gain (G), feed intake (F), and the gain:feed ratio (G:F) in Periods 1 (Days 9 to 13 posthatch) and 2 (Days 13 to 17 posthatch) were analyzed. Stressors decreased performance in both periods, but the effect was greater in Period 2. Synergism between A and H in Period 2 decreased chicks' G, F, and G:F in Period 2. Stress-depressed productive traits in Period 1 were succeeded in Period 2 not by residual negative effects but by compensatory responses: prior exposure to stressors in Period 1 was not detrimental to the chicks' subsequent G or G:F in Period 2. For example, chicks switched from Treatment ah in Period 1 to AH in Period 2 had lower G in Period 2 than did those going from either Ah, aH, or AH in Period 1 to AH in period 2. It was concluded that exposure to stressors early on enhanced the chicks' ability to cope with the same or with different stressors later and that compensatory responses occurred as the result of short-term exposure to stressors.

Ammonia↗
PubMed1991

Costs of occupational injury and illness in Pennsylvania.

A variety of state and federal data sources are used to estimate two critical components of the annual economic costs of occupational injuries and illnesses in Pennsylvania: foregone earnings of affected workers and medical costs. Foregone earnings costs resulting from occupational injuries and illnesses are estimated at between $1.22 billion and $2.02 billion in 1988. A number of potential adjustments to these estimates widen the range considerably. Estimates of medical costs range from $740 million to $797 million. Combining these two estimates gives total estimated costs of $1.96 billion to $2.82 billion.

Accidents, Occupational↗
PubMed1991

Congenital ptosis. Long-term results of treatment using lyophilized fascia lata for frontalis suspensions.

This report extends a prospective collaborative study published in 1982 of congenital ptosis repair using lyophilized human fascia lata to investigate the permanency of banked human fascia lata. Fifty-six patients are described with a mean postoperative follow-up of 7.2 years and a median follow-up of 8.3 years. Significant recurrence of ptosis was documented in 24 of 56 (43%) patients. New failures continue to be recognized even in the eighth postoperative year. Life table and survival analysis predicts a success rate from frontalis suspension surgery using lyophilized human fascia lata of 90% at 2 to 3 years, 70% at 5 to 6 years, and 50% at 8 to 9 years.

Blepharoptosis↗
PubMed1991

Evaluation of the fiber-optic antibody-based fluoroimmunosensor for DNA adducts in human placenta samples.

This paper presents the application of a fiber-optic antibody-based fluoroimmunosensor (FIS) for measuring DNA adducts of benzo[alpha]pyrene in human placenta samples. The FIS combines the excellent specificity of the antigen-antibody reaction, the high sensitivity of laser excitation, and the versatility of fiber-optic technology. The FIS was used to detect benzo[alpha]pyrene tetrol (BPT) after release from DNA by mild acid hydrolysis. These placenta samples contained one molecule of adduct per 10(7) base pairs. The limit of detection of the FIS for BPT is about 14 amol (14 x 10(-18) mol).

Benzo(a)pyrene↗