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Biomedical subjects

P C Harrison

Publications and source records attributed to P C Harrison.

At least 19 recordsLinked to original sources
PubMed1999

Anti-LFA-1 alpha reduces the dose of cyclosporin A needed to produce immunosuppression in heterotopic cardiac transplanted rats.

BACKGROUND: Monoclonal antibodies (MAb) against cell adhesion molecules prolong the time to acute rejection of transplanted organs in animals. Postulated mechanisms of action include blockade of trafficking of host leukocytes into or recognizing of effector/target cells within the allograft. We examined whether an anti-ICAM-1 (1A29), anti-LFA-1 alpha (WT.1), or anti-CD-18 (WT.3) could reduce the immunosuppressive dose of cyclosporin A (CsA) when used in combination. METHODS: A rat heterotopic cardiac transplant model with ACI donors and Lewis recipients was used. MAb dose was 3 mg/kg, i.p. with treatment on Days -3 and -1 prior to transplant, followed by daily dosing for 10 days post-transplantation (Tx). Cyclosporin A doses were either 1.5 or 2.75 mg/kg, PO beginning the day of and for 10 days post-Tx. RESULTS: Untreated allografted rats demonstrated a mean rejection time (MRT) +/- SEM of 8.8 +/- 0.6 days. Cyclosporin A at 1.5 and 2.75 mg/kg showed mean rejection times of 8.5 +/- 0.3 (NS) and 20.5 +/- 1.9 (p < 0.05) days, respectively. Monotherapy with 1A29 or WT.3 did not prolong MRT, whereas WT.1 increased MRT to 21.7 +/- 4.3 days (p < 0.05). MAb combination therapy did not extend MRT greater than that demonstrated by WT.1 alone. However, MAb and CsA combination therapy significantly increased MRT with WT.1 and CsA resulting in the greatest extension. WT.1 combination with CsA at 1.5 mg/kg and 2.75 mg/kg increased MRT to > 46.8 +/- 6.3 and > 44.2 +/- 9.4 days, respectively. CONCLUSIONS: Anti-LFA-1 alpha and CsA combination therapy significantly extends the time to rejection of transplanted rat hearts. We conclude that combining an anti-LFA-1 alpha and CsA may be beneficial in prolonging allograft rejection times and in reducing the amount of CsA necessary for immune suppression, thereby minimizing its toxic effects.

Administration, Oral↗
PubMed1998

Cyclosporine dosage can be reduced when used in combination with an anti-intercellular adhesion molecule-1 monoclonal antibody in rats undergoing heterotopic heart transplantation.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) is believed to play a role in acute rejection of allografted tissues. This molecule is involved in the interaction of T cells with antigen-presenting cells expressed on the vascular endothelium of transplanted organs and is involved in the adhesion of inflammatory cells to this endothelium and their subsequent migration into the underlying tissues. METHODS: Rat abdominal heterotopic heart transplantation was used to study the role of ICAM-1 in the rejection process. American Cancer Institute rats were used as donors; Lewis rats were used as recipients. Graft survival was monitored daily via donor heart palpation. Nine groups (n = 6/group) were studied: untreated controls; olive oil; cyclosporine at 1.5, 2.75, and 5.0 mg/kg, respectively; R3.1, a control monoclonal antibody; 1A29, a rat anti-ICAM-1 monoclonal antibody, 3 mg/kg administered intraperitoneally; a combination of 1A29 (3 mg/kg) and cyclosporine (1.5 mg/kg); and a combination of 1A29 (3 mg/kg) and cyclosporine (2.75 mg/kg). RESULTS: Mean rejection time was 8.8 +/- 0.6 days for the untreated allografted controls and 9.7 +/- 1.1 days for the olive oil controls. Cyclosporine (1.5, 2.75, and 5.0 mg/kg) showed mean rejection times of 8.5 +/- 0.3, 20.5 +/- 1.9, and 28.8 +/- 3.6 days, respectively. The 1A29 treatment showed a mean rejection time of 9.3 +/- 0.7 days. Combination therapy of 1A29 and cyclosporine at 1.5 or 2.75 mg/kg demonstrated mean rejection times of 17.7 +/- 3.3 and 29.2 +/- 6.7 days, respectively. Thus 1A29 alone does not prolong cardiac allograft survival; however, combination therapy with either a subthreshold or a moderate dose of cyclosporine significantly extends the time to rejection of heterotopically transplanted rat hearts. CONCLUSIONS: Although monotherapy with an ICAM-1 antagonist alone may not be beneficial in preventing acute rejection episodes after organ transplantation, combination therapy of an anti-ICAM-1 monoclonal antibody may allow for a reduction in the dose of cyclosporine necessary for immune suppression. Such a reduction could lead to a lowering of the incidence of nephrotoxicity and other side effects associated with long-term cyclosporine administration.

Abdomen↗
PubMed1997

Effects of supplemental ascorbic acid on the energy conversion of broiler chicks during heat stress and feed withdrawal.

The objectives of this study were 1) to determine the effects of supplemental ascorbic acid (AA) on the energy conversion of broiler chicks maintained at thermoneutral and potential heat stress temperatures using indirect convective calorimetry; and 2) to determine whether changes in energy conversion are reflected in changes in lipid metabolism. In Experiment 1, 120 2-d-old cockerels, housed in two identical environmental chambers, were maintained under constant light (2.0 +/- 0.2 fc) and recommended thermal conditions (29.6 +/- 0.8 C; 33.4 +/- 8.0% RH) and consumed water and feed ad libitum. Beginning on Day 8 posthatch, one-half of the birds inside each chamber were randomly assigned and received feed supplemented with AA. Beginning on Day 9 posthatch, the temperature inside one chamber was increased to 34 C whereas the other chamber remained thermoneutral. This design resulted in four treatments: 1) thermoneutral (TN: 27.7 +/- 0.8 C; 40.9 +/- 9.4% RH) and 0 mg AA/kg feed (ppm); 2) TN and 150 ppm AA; 3) heat stress (H: 33.8 +/- 0.5 C; 43.3 +/- 7.4% RH) and 0 ppm AA; or 4) H and 150 ppm AA. Also beginning on Day 9 posthatch, birds were randomly assigned to one of three identical, indirect convective calorimeters designed to accommodate TN or H. Oxygen consumption, carbon dioxide production, respiratory quotient, and heat production were evaluated daily for 8 h, through Day 17 posthatch. Following calorimetric measurement, birds were returned to their respective caging unit/chamber for the remainder of the study. Weight gain, feed intake, and gain: feed were also measured over the 9-d study. Heat exposure depressed (P < 0.05) weight gain, feed intake, and gain:feed. Ascorbic acid increased (P < 0.10) weight gain. Oxygen consumption and carbon dioxide and heat production per kilogram0.75 decreased (P < 0.05) with age with no change in the respiratory quotient. Heat exposure lowered (P < 0.001) the respiratory quotient. A temperature by AA interaction was detected in which heat-exposed birds expressed lower (P < 0.10) respiratory quotients when consuming the AA-supplemented diet. In Experiment 2, 18 2-d-old cockerels, housed in an environmental chamber, were maintained under constant light and recommended thermal conditions (29.3 +/- 0.4 C; 41.4 +/- 3.3% RH) and consumed water and feed ad libitum. On Day 9 posthatch, birds were deprived of feed for 24 h with ad libitum access to water supplemented with either 0 or 400 mg AA/L. Blood samples were obtained from each bird before and after feed withdrawal and supplementation. Supplemented birds exhibited elevated (P < 0.01) plasma AA, levels that were not affected by feed deprivation. Feed deprivation increased (P < 0.0001) plasma beta-hydroxybutyrate with no effect of AA, and decreased (P < 0.05) plasma triglycerides in the unsupplemented birds. A feed withdrawal by AA interaction was detected in which plasma triglycerides remained elevated in birds supplemented with AA. These data suggest that supplemental AA influences body energy stores that are used for energy purposes during periods of reduced energy intake.

3-Hydroxybutyric Acid↗
PubMed1997

Preference among cooling systems by gilts under heat stress.

A preference experiment was conducted to compare and evaluate the use of three cooling systems by mature gilts. Systems evaluated were snout coolers (S), drip coolers (D), and conductive cool pads (P). Preference for cooling system and pen position were continuously monitored and evaluated during daily heat stress conditions (34.2 +/- 2.8 degrees C), nightly warm conditions (26.6 +/- 2.3 degrees C), and for total time. The physiological variables of respiration rate (RR) and rectal temperature (Tr) were measured at three separate times daily. Gilts naive to the cooling systems were individually housed in pens with three free stalls, each stall containing a different cooling system. After 1 d of warm temperature (27.6 +/- 2.5 degrees C) acclimation, gilts were exposed to 10 h of the heat stress conditions and 14 h of the warm night conditions each day for six consecutive days. Cooling system use was higher during the hot period (80.2%) than during the warm period (66.2%). The conductive cool pad was preferred over the drip cooler (P < .02) and the snout cooler (P < .0002). The preference for the conductive cool pad persisted in the warm period. Cooling system use had a significant effect on Tr and RR (P < .001). The Tr (P < .005) and RR were lower (P < .005) with the use of the conductive cool pad, whereas the drip cooler and snout cooler showed no effect on these variables.

Animal Welfare↗
PubMed1995

Effects of supplemental ascorbic acid on the performance of broiler chickens exposed to multiple concurrent stressors.

An experiment was conducted to determine whether ascorbic acid (AA) increases resistance of female Hubbard x Hubbard broiler chicks to multiple concurrent stressors. Stressors imposed from 10 to 17 d posthatch included 2 x 2 x 2 factorial combinations of beak trimming [(B), sham-operated or beak-trimmed and cauterized], coccidiosis [(C), gavage with 0 or 3 x 10(5) sporulated Eimeria tenella oocysts], and heat stress [(H), 28 vs 33 C]. A starter diet was supplemented with AA to provide 0, 150, or 300 ppm (milligrams per kilogram). This resulted in a 2 x 2 x 2 x 3 factorial design with two six-chick replicates of each of the 24 treatment combinations. Data were analyzed using ANOVA and a level of 95% significance. Ascorbic acid increased feed intake and lowered plasma corticosterone and heterophil:lymphocyte ratios. Heat depressed weight gain and feed intake and elevated heterophil:lymphocyte ratios. Heat and AA interacted to improve weight gain and feed intake and lower heterophil:lymphocyte ratios. Coccidiosis depressed weight gain, feed efficiency, and heterophil:lymphocyte ratios. Coccidiosis and AA interacted to increase feed intake and lower plasma corticosterone and heterophil: lymphocyte ratios. Beak trimming increase heterophil:lymphocyte ratios. Beak trimming and AA interacted to increase feed intake and lower heterophil: lymphocyte ratios. Weight gain and feed efficiency decreased whereas heterophil:lymphocyte ratios increased linearly in unsupplemented birds as a function of stressor "order" (the number of stressors imposed simultaneously) indicating an additive effect of systematically increasing the number of stressors. No changes in feed efficiency or heterophil:lymphocyte ratios were detected as a function of stressor order when AA was provided. Ascorbic acid reduced the slope of the regression equation describing the relationship between weight gain and stressor order. It was concluded that AA, particularly at 150 ppm, enhanced performance of broiler chicks exposed to multiple concurrent environmental stressors.

Animals↗
PubMed1994

Sodium depletion in conscious cynomolgus monkeys attenuates baroreflex sensitivity independently of prostaglandins.

We tested the hypothesis that baroreflex attenuation during sodium depletion is due to increased prostaglandin (PG) levels. We studied baroreflex sensitivity before and after PG synthesis inhibition in conscious cynomolgus monkeys. Arterial pressure and pulse interval (PI) were measured during intravenous infusions of phenylephrine (1-20 micrograms.kg-1.min-1, n = 6) and nitroprusside (1-10 micrograms.kg-1.min-1, n = 7). Infusions were repeated 30 min after indomethacin (Indo, 6 mg/kg iv). The slope (in ms/mmHg) of the mean arterial blood pressure-PI plot was used as an index of baroreflex sensitivity. Plasma renin activity (PRA) was elevated (47.9 +/- 9.7 vs. 8.8 +/- 3.3 ng angiotensin I.ml-1.h-1) after sodium depletion (P < 0.05). Baroreflex sensitivity to hypotension and hypertension was significantly (P < 0.05) attenuated by sodium depletion (3.69 +/- 0.9 vs. 0.9 +/- 0.1 ms/mmHg and 7.38 +/- 0.6 vs. 5.04 +/- 0.9 ms/mmHg, respectively). Indo decreased PRA to 28.6 +/- 5.7 ng angiotensin I.ml-1.h-1 (P < 0.05) in sodium-depleted monkeys and decreased heart rate -21 +/- 3.7 from a baseline of 166 +/- 9.40 beats/min in normal monkeys and -22 +/- 2.9 from a baseline of 191 +/- 7.9 beats/min in low-sodium monkeys (P < 0.05). Indo did not significantly change baroreflex sensitivity in either group. Thus the baroreflex was attenuated in conscious nonhuman primates during sodium depletion; acute PG synthesis blockade did not improve baroreflex sensitivity. Indo decreased heart rate without changing arterial pressure; suggesting that PGs caused a downward resetting of the pressure-heart rate relationship.

Animals↗
PubMed1994

Characterization of the nutritional interactions between organic acids and inorganic bases in the pig and chick.

Four experiments were conducted to characterize the interactions between fumaric (FA), malic (MA), or citric acid (CA) and NaHCO3. In two experiments, seven diets were formulated containing 2.5% FA, MA, and CA, with or without 2.3, 1.9, or 1.4% NaHCO3, respectively, as well as a control diet (no addition of organic acids or NaHCO3) for 28-d-old pigs (Exp. 1, corn-soy protein concentrate-based diet) and 1-wk-old chicks (Exp. 4, corn-soy-based diet). In Exp. 1, at 2 and 4 wk, the FA+NaHCO3 treatment resulted in greater average daily gain (ADG) and feed intake (ADFI) compared with the control (P < .05). In Exp. 2, 28-d-old pigs were fed corn-soy diets with .9, 1.6, and 2.3% NaHCO3 in addition to 2.5% FA. After wk 2, there was a quadratic response in ADG (P < .08) and ADFI (P < .05) when increasing levels of NaHCO3 were added to the diet. This was true at wk 4 for both ADG and ADFI (P < .05). In Exp. 3, finishing pigs were fed corn-soy diets containing 2.5% FA or 2.5% FA + 2.3% NaHCO3 added to a control diet. No effect (P < .05) of FA or NaHCO3 was observed. In Exp. 4, the combination of CA+NaHCO3 or MA+NaHCO3 was superior to FA+NaHCO3 for ADG (P < .08) and ADFI (P < .05) when fed to young chicks.

Animal Feed↗
PubMed1993

Research note: effect of carbonated drinking water on production performance and bone characteristics of laying hens exposed to high environmental temperatures.

An experiment was conducted to determine the effects of providing heat-stressed laying hens with carbonated drinking water on production performance and tibia bone breaking strength. A total of 32 commercial laying hens (89 wk of age) were housed in an environmental chamber and exposed to 1 wk of a constant thermoneutral temperature (21 C), followed by 6 wk of a daily heat stress temperature cycle (34 C for 8 h; 21 C for 16 h). One half of the hens received tap water and the other half were provided carbonated water immediately after housing. Following 6 wk of heat stress temperature exposure, all hens were killed by cervical dislocation and left tibia bone strength measurements were taken. Hen-day egg production, egg weight, egg yield, feed consumption, and feed efficiency did not differ between water treatments; however, egg specific gravity was depressed for hens provided carbonated versus tap drinking water. Left tibia bone breaking strength per 100 g body weight was improved (P < or = .05) for hens provided with carbonated drinking water during exposure to heat stress temperatures. These results suggest that carbonated drinking water may enhance bone integrity by increasing tibia bone breaking strength of older laying hens exposed to a short-term heat stress period.

Animals↗
PubMed1993

Assessment of practice readiness through PMLexis.

Attempts are being made to unify state licensing examinations through the efforts of the National Board of Podiatric Medical Examiners and LGR Examinations of State College, PA. This company has revised the Virginia examination and increased its validity and reliability. A history and a description of the examination are given.

Education, Medical↗
PubMed1991

Effect of peripheral foot cooling on metabolic rate and thermoreregulation of fed and fasted chicken hens in a hot environment.

An experiment with a factorial arrangement of treatments was conducted to determine the effect of ambient and water-cooled roost temperatures on metabolic rates of fasted and fed Columbian Plymouth Rock hens. Indirect open circuit calorimetry was used to determine oxygen consumption and carbon dioxide production rates by the hens. Experiments during the thermoneutral period were conducted at 25 +/- 1 C for both ambient and roost temperature treatments. Experiments during the heat-stress period were conducted at an ambient temperature of 35 +/- 1 C. Roost temperatures of 20 +/- 1 (water-cooled roost) and 34 +/- 1 C were provided. Fasting was for at least 40 h; fed hens were fasted, then gavaged with 20 g of sucrose dissolved in 20 mL of distilled water. The metabolic rates were consistently higher in fed than fasted hens for all temperature treatments. The respiratory quotient responses were significantly influenced by feeding status of hens but not by ambient or roost temperature treatments. Cooled roosts in the 35 +/- 1 C environment provided metabolic rates 19% lower. The rectal temperatures of heat-stressed fasted and fed hens with a 34 +/- 1 C roost were elevated 1.20 and 1.32 C, respectively, whereas those of hens with the 20 +/- 1 C water-cooled roosts increased only .22 and .28 C during the heat-stress period, respectively. Hens on the 20 +/- 1 C roost did not initiate thermal panting, whereas those on the 34 +/- 1 C roost panted vigorously. It is concluded that the water-cooled roost partially alleviated heat stress by lowering metabolic rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of sodium aluminosilicate on phosphorus utilization by chicks and laying hens.

Three experiments were conducted to evaluate the effects of sodium aluminosilicate (SAS) on performance of chicks and laying hens fed diets varying in nonphytate P (NPP), phytate, and fiber content. In two chick growth experiments a corn and soybean meal diet and a phytate and fiber-free casein-dextrose diet were used. These diets contained .1% NPP and 1.1% Ca and were fortified with 0, .05, or .10% P from KH2PO4 and 0 or .5% SAS. A 3 x 2 factorial arrangement of treatments was used. Sodium aluminosilicate supplementation significantly (P less than .05) depressed growth of chicks fed the corn and soybean meal diets containing 0 or .05% supplemental AP. Sodium aluminosilicate addition decreased (P less than .05) tibia ash and total tibia P (tibia weight x P concentration) in both chick experiments, with the effect being greater for chicks fed the corn and soybean meal diet. In the laying hen experiment, birds were fed corn and soybean meal diets containing NPP levels of .1, .45, or 1.8% and SAS levels of 0 or 1.0%. Egg production and egg yield were depressed (P less than .05) by feeding diets containing .1 or 1.8% NPP, and egg specific gravity was decreased (P less than .05) by feeding 1.8% NPP. Addition of SAS to the .1% NPP diet caused a large reduction (P less than .05) in egg production, egg weight, and feed efficiency, whereas SAS supplementation of the 1.8% NPP diet had no significant effect. Sodium aluminosilicate supplementation increased (P less than .05) egg specific gravity for hens fed the .1 and 1.8% NPP diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Silicates↗
PubMed1991

Performance evaluation of heat-stressed commercial broilers provided water-cooled floor perches.

A study was conducted to determine whether water-cooled floor perches would be utilized by commercial broilers exposed to a constant hot ambient environment; and subsequently, whether utilization of these perches would improve performance beyond those provided uncooled floor perches. A total of 330 day-old commercial broiler chicks were randomly allocated to six pens (2.44 m2) in an environmentally controlled facility and maintained in a thermoneutral brooding environment for 16 days. Following this period, 240 birds were selected on a body weight basis and randomly assigned to the six pens. A perch constructed from steel pipe (2.44 m length, 5.0 cm diameter) was then placed diagonally on the litter covered floor of each pen. The birds were first exposed to a thermoneutral period (27.7 C), during which time cooling of the perches in three replicate pens was initiated by circulating tap water. The other three experimental pens received ambient perches. Ambient temperature was then raised to 32.6 C for the following 4 wk. The results of the present study showed that utilization of water-cooled perches by broilers was greater (P less than or equal to .01) than ambient perch utilization throughout the 32.6 C period. Average daily gain was greatest (P less than or equal to .01) for broilers exposed to cool perches. Additionally, they consume more feed (P less than or equal to .05), on a daily basis, than those given ambient perches during the heat-stress period. Broilers exposed to water-cooled perches also had a more efficient gain to feed ratio (P less than or equal to .01). At the completion of the study, final body weight and total body weight gain were greater (P less than or equal to .05) for broilers given water-cooled perches compared with those exposed to ambient perches. Total amount of feed consumed and total feed efficiency were only moderately affected (P less than or equal to .10) by perch treatments. These results indicated that water-cooled perches were beneficial in improving broiler performance during periods of high environmental temperatures.

Animals↗
PubMed1991

Effect of roost temperature on performance of chickens in hot ambient environments.

A split-plot experiment was conducted in thermally controlled chambers using Columbian Plymouth Rock chickens to determine the effect of water-cooled roosts on performance in hot ambient conditions. The birds were subjected to 25 +/- 1, 35 +/- 1, and 25 +/- 1 C ambient temperature treatments for 2, 3, and 2 wk, respectively. Roost temperature treatments were either cool (20 +/- 1 C) or air-equilibrated (25 +/- 1 or 35 +/- 1 C). The performance parameters evaluated were percentage hen-day egg production, egg weight, feed intake, feed conversion, fertility, and hatchability. Birds subjected to the water-cooled roost treatment had consistently higher performance than birds using the air-equilibrated roost under all three ambient temperatures. Both ambient and roost temperature treatments significantly influenced percentage hen-day egg production, average daily feed intake, and percentage hatchability (P less than or equal to .05). However, the biggest differences in performance were observed during the heat-stress period. Decreases in performance during the heat-stress period from the thermoneutral control values were: 5.95 and 13.1 percentage points for hen-day egg production, 22.2 and 34.8 percentage points for average daily feed intake, and 5.17 and 15.38 percentage points for hatchability in water-cooled and air-equilibrated roost treatments, respectively. The ambient and roost temperature treatments did not significantly affect egg weight, feed conversion, or percentage fertility. The improved performance with water-cooled over air-equilibrated roost treatments, especially during heat-stress periods, indicates that the water-cooled roosts minimized the deleterious effects of heat stress through conductive heat loss from the birds to the roost.

Air Conditioning↗
PubMed1990

Influence of carbonated drinking water on tibia strength of domestic cockerels reared in hot environments.

To determine the effects of heat stress and drinking water treatments on physical characteristics of skeletal tissue, tibias of cockerels ranging in age from 4 to 11 weeks were tested for breaking strength. Birds were subjected to either a thermoneutral environment (21 +/- 2 C) or a hot environment (37 +/- 2 C) and supplied with either tap or carbonated drinking water. Breaking strength of tibias was reduced in the hot environment; however, consumption of carbonated drinking water in the hot environment resulted in bone strength comparable with that associated with thermoneutral environment (both types of water). Also, bones from birds of the carbonated water-37 C treatment group had less phase breaks and tended to separate with a single break. Results indicate that hot environment and carbonated drinking water not only affect the previously reported morphologic and chemical characteristics of developing bone, but also their physical attributes.

Animals↗
PubMed1988

Reversal of depressed miduterine arterial flow during hyperthermia-induced respiratory alkalosis.

The influence of ambient and arterial PCO2 on miduterine arterial flow of pregnant sheep acutely exposed to hot environments was investigated. Five mixed-breed ewes between 120 and 130 days of gestation were subjected to hot environments (increasing from thermoneutral 23 to 40 degrees C), and arterial blood pH, PCO2, and PO2 were determined at 5-min intervals. Respiratory rate, heart rate, rectal temperature, blood pressure, and miduterine arterial flow were continuously monitored prior to and during elevation of ambient air temperature. When miduterine arterial flow had decreased to 50% of thermoneutral control levels, ambient air CO2 was increased to 2.5%. Elevated ambient inspired CO2 caused a reversal in arterial pH and PCO2 to near thermoneutral levels. Miduterine arterial flow increased to 77% of the control levels following the elevated ambient PCO2 period. Respiratory rate also decreased when ambient CO2 was increased but remained 136% greater than the thermoneutral control level. All other parameters remained near their heat stress (40 degrees C) level during the elevation of ambient CO2. These data indicate that heat-stress-induced depression of miduterine arterial flow is vasoactively regulated, and cause-effect related to both arterial pH and PCO2, and thermoregulatory shunting of blood to heat-dissipating surfaces.

Alkalosis, Respiratory↗
PubMed1987

Membrane-associated interleukin 1 activity on human U937 tumor cells: stimulation of PGE2 production by human chondrosarcoma cells.

Membrane-associated interleukin 1 (IL 1) activity was induced on the human macrophage tumor cell line, U937, by pretreatment with phorbol myristic acid (PMA). Incubation of PMA-treated, paraformaldehyde-fixed U937 cells with the murine cell line D10.G4.1 in the presence of concanavalin A caused an increase in DNA synthesis as measured by the uptake of tritiated thymidine. Paraformaldehyde-fixed U937, not pretreated with PMA, showed little or no activity. A rabbit polyclonal antibody directed against human IL 1 neutralized all membrane-associated IL 1-like activity, as measured by the inhibition of D10.G4.1 cell proliferation. PMA-treated U937 caused a pronounced enhancement of PGE2 production from a human chondrosarcoma cell line, SW-1353. Membrane-associated IL 1 induced a more potent PGE2 response than did a maximal concentration of soluble IL 1. Rabbit antihuman IL 1 neutralized membrane-bound IL 1 induction of PGE2. The data presented here raise the possibility that membrane-bound IL 1 may play a primary role in the pathophysiology of the inflammatory disease process.

Cell Membrane↗
PubMed1987

Heart rate, blood pressure, cardiac output, and total peripheral resistance of single comb White Leghorn hens during an acute exposure to 35 C ambient temperature.

Two experiments were undertaken to determine selected cardiovascular responses of laying hens to a thermal challenge at 35 C ambient temperature. In the first, six Single Comb White Leghorn (SCWL) hens were exposed to 35 C and changes in systolic and diastolic blood pressure, heart rate, respiratory rate, and rectal temperatures were determined. In the second, seven SCWL hens were exposed to 35 C and changes in cardiac output, total peripheral resistance, blood pressure, heart rate, respiratory rate, and rectal temperature were monitored. In the first experiment heart rate and blood pressure decreased. In the second experiment there was a 58% increase in cardiac output and a 50% decrease in total peripheral resistance accompanied by a 9% decrease in mean blood pressure. Changes in cardiovascular tone preceded respiratory adjustments during acute heat challenges. This may represent one of the most efficient means of heat dissipation for the bird.

Animals↗