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Biomedical subjects

H D Johnson

Publications and source records attributed to H D Johnson.

At least 19 recordsLinked to original sources
PubMed2001

Changes in adolescents' conflict responses associated with consecutive presentation of hypothetical conflict situations.

The advantages of using hypothetical situations are one reason they have been widely used to examine adolescents' responses to conflict situations. One frequently used research protocol involves presenting several conflict scenarios to participants during a single session. However, in real-life situations multiple conflicts rarely occur within short periods of time, and the nature of this presentation may be associated with changes in adolescents' reports of conflict behaviors. Trend analyses of emotional, conflict goal, and conflict tactic responses from grade 8, 10, 12, and college students to consecutively presented conflict situations showed that responses were associated with presentation of the hypothetical situations. Findings revealed an increase in reports of assertive conflict behaviors and a decrease in reports of constructive conflict behaviors with successive situation presentation. Results from the current study suggest that researchers must consider trends in responses when examining findings from successive situation presentation methodologies because adolescent reports of conflict behavior may change as situation presentation proceeds.

Adolescent↗
PubMed2001

Peer conflict avoidance: associations with loneliness, social anxiety, and social avoidance.

Failure to resolve peer conflict is associated with children's reports of loneliness, social anxiety, and social avoidance. Although these relationships are well established, researchers have not examined the association between the avoidance of peer conflict and various adjustment characteristics. The current study examined the association between avoidance of conflict and measures of loneliness, social anxiety, and social avoidance for 59 pupils in Grade 4 (31 boys and 28 girls) and 47 in Grade 8 (22 boys and 25 girls). Volunteers indicated that conflict avoidance based on autonomy, e.g., independence issues, and interpersonal issues, e.g., closeness and cohesion, was associated with scores on loneliness for boys and girls, respectively. Conflict avoidance for emotional and physical well-being and fear of punishment was associated with increased reports of loneliness and social anxiety for children in Grade 4.

Adolescent↗
PubMed1997

Evaluation of the Hemochron 8000 Rx/Dx system for heparin management.

The Hemochron Rx/Dx uses an ACT and a heparin response tube to calculate the heparin dose to identify heparin sensitive/resistant patients. We evaluated the Rx/Dx system in 37 patients to determine if the ACT after the predicted heparin loading dose was adequate to initiate CPB. The mean heparin dose calculated by the Rx/Dx was 31,700 IU +/- 8,700 IU (370 IU/kg) with a mean post ACT of 463 +/- 124 sec. Our standard heparin dose (400 IU/kg) would have given an additional 2,800 IU over the Rx/Dx. Four patients (6.5%) were predicted to be heparin sensitive and all four achieved an ACT over 450 sec. Twenty-one patients (56.8%) were predicted to be resistant and yet failed to raise the ACT over 450 sec in 17 (81.0%). Twelve patients (32.4%) were predicted to have a normal heparin response, and four (33.3%) did not achieve an ACT over 450 sec. In all, 21 patients (56.8%) did not achieve an ACT greater than 450 sec. Each institution should evaluate their heparin loading dose and the resultant ACT. In this study, we found the number of times the Rx/Dx system did not raise the ACT over 450 sec too great to justify the additional expense.

Aged↗
PubMed1995

Intraoperative blood transfusion is a major risk factor for coronary artery bypass grafting in women.

BACKGROUND: Women have been found to have greater mortality from coronary artery bypass grafting than men. Uncertainty exists regarding the causes of the differences in outcomes between men and women after coronary artery bypass grafting. METHODS: From a database of 2,569 patients having coronary bypass grafting we have determined factors that contribute to poorer outcomes in women compared with men. RESULTS: Women were found to have greater mortality, postoperative bleeding, and postoperative pulmonary failure than men (p < 0.05). There was no significant difference between men and women in postoperative renal failure, postoperative infection, postoperative stroke, or intraaortic balloon pump (p = not significant). Patient factors other than sex accounted for all the significant predictors (stepwise logistic regression) of mortality, postoperative bleeding, postoperative renal failure, postoperative pulmonary failure, postoperative stroke, need for intraaortic balloon pump, and postoperative infection (p < 0.05). Poorer outcomes in women are associated with greater need for transfusion during operation. Diabetes is predictive of renal failure and stroke. CONCLUSIONS: Mortality and morbidity is less in men despite their higher preoperative creatinine level, greater incidence of reoperation, lower ejection fraction, and more common atherosclerosis of the ascending aorta.

Bacterial Infections↗
PubMed1994

Comparative analysis of recovery of cardiopulmonary bypass residual blood: cell saver vs. hemoconcentrator.

For surgical bleeding problems, the cell saver has been used to return shed blood; however, overuse can lead to a deficit in coagulation factors. Its usefulness has gained widespread use in many surgical settings. The hemoconcentrator can aid in raising the hematocrit level while reducing blood utilization where large blood volume and/or large amounts of irrigation are returned to the perfusion circuit. The hemoconcentrator returns red blood cells without removing coagulation factors, unlike the cell saver. In order to determine which method of returning residual blood from the cardiopulmonary bypass circuit is more desirable, blood samples were drawn both pre and post transfusion from 15 cell saver patients, and 14 hemoconcentrator patients. Twelve hour blood loss was recorded in 40 patients within each group. The fibrinogen, platelet count, total protein, albumin and white blood cell count were similar between the two groups, as was the blood loss. The only significant differences found were the post red blood cell count, post hemoglobin, and the delta hematocrit, all being higher in autotransfusion group. In conclusion, returning blood through the hemoconcentrator in the average adult perfusion circuit was not able to significantly raise certain coagulation parameters, nor reduce postoperative bleeding.

Blood Coagulation↗
PubMed1992

Physiologic and immune responses associated with 48-hour fast of pigs.

We sought to determine the effect of 48 hours of fasting on physiologic and immune responses of pigs. Sixteen crossbred barrows, approximately 8 weeks of age, were housed in a controlled environment (21 degrees C, 45% RH) with feed and water ad libitum. After 10 days, eight pigs were fasted for 48 hours with water available ad libitum; the remaining eight received feed and water ad libitum. Blood samples were obtained by venipuncture before fasting, at the end of 48-hour fasting, and 3 and 10 days later. No significant differences in responses to mitogens PHA or Con A were noted in whole blood or isolated lymphocyte cultures. Changes in numbers of leukocytes, neutrophils, and serum cortisol concentrations, but not of lymphocytes, were significant. The results suggested that short-term fasting transiently reduces the number of neutrophils and increases serum cortisol concentrations, with no effect on blastogenic responses of lymphocytes to selected mitogens.

Animals↗
PubMed1991

Determination of heat-exposure effects on the concentration of catecholamines in bovine plasma and milk.

A reversed-phase high-performance liquid chromatographic method with electrochemical detection has been adapted for the determination of picogram concentrations of norepinephrine and epinephrine in bovine plasma and milk. This method has been used to monitor the levels of these catecholamines when lactating cows are exposed to heat stress under controlled conditions. In response to heat stress, epinephrine concentrations in milk and plasma were similar. However, norepinephrine concentrations in milk were one tenth of that in plasma.

Animals↗
PubMed1991

Assessment of thermal status of somatotropin-injected lactating Holstein cows maintained under controlled-laboratory thermoneutral, hot and cold environments.

Two experiments, with a single-reversal design and 12 cows per experiment, were conducted to study the effects of somatotropin on thermal status of lactating cows under laboratory thermoneutral (18 to 22 degrees C, 30-50% relative humidity), hot (24-35 degrees C, 30-50% relative humidity) and cold (-5 (-) +5 degrees C, 50-55% relative humidity) conditions. Throughout the experiment six cows were injected with somatotropin (25 mg/d) and six with sodium bicarbonate. All injections were started the first day of the 30-d natural environmental period (22-35 degrees C and 41-97% relative humidity for summer experiment, and -5 (-) +5 degrees C and 4-25% relative humidity for winter experiment) before the cows were exposed alternatively to laboratory thermoneutral and hot or cold environments. The somatotropin-treated cows had higher energy intake (13 and 17%), heat production (19 and 25%), heat loss (36 and 24%) and milk energy (40 and 49%), than control cows under thermoneutral and hot conditions, respectively. The somatotropin-treated cows had higher heat production (18 and 10%), respiratory heat loss (27 and 17%) and milk energy (14 and 25%) than control cows under thermoneutral and cold conditions, respectively. The increased heat production associated with somatotropin was accompanied by increased heat losses. Part of the increased heat production was attributed to the increased milk energy and energy intake. These results suggest that increased heat production during somatotropin treatment was within the range that could be dissipated by the cows.

Animals↗
PubMed1991

Correlation of preoperative factors, severity of disease, type of oxygenator and perfusion times with mortality and morbidity of coronary bypass.

Previous studies have related preoperative status and severity of disease to the outcome of coronary artery bypass surgery. Although increased perfusion and clamp times increase the risk of cardiac surgical procedures, the importance of these factors in relation to the patient's preoperative condition and the severity of disease has not previously been determined. In this study of 1078 patients, we examined the correlation between the patient's preoperative condition, the severity of coronary disease, and duration of perfusion and clamp time, and the type of oxygenator used with the mortality and morbidity associated with coronary artery bypass grafting. One-way analysis of variance and multiple correlation analysis showed that perfusion time, clamp time and nonclamp perfusion time correlated with mortality, perioperative infarction, the use of intra-aortic balloon pump, stroke, renal failure, pulmonary failure, infection, and leg wound complications (p less than 0.05). Perfusion time, clamp time and nonclamp perfusion time did not correlate with postoperative bleeding or sternal wound complications. Nonclamp perfusion time correlated more strongly than any other factor with mortality, perioperative infarction, the use of intra-aortic balloon pump, renal failure, pulmonary failure and infection (p less than 0.05). Clamp time correlated more than any other factor with the development of leg-wound complications (p less than 0.05). The use of a bubble rather than a membrane oxygenator was significantly related to mortality, stroke, infection and leg wound complications by one-way analysis of variance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of somatotropin on milk yield and physiological responses during summer farm and hot laboratory conditions.

The effects of bST on performance and physiological responses of lactating cows was studied under farm summer and laboratory heat conditions. Twelve cows, 90 to 50 d postpartum, were injected with either bST or vehicle solution for 30 d under farm summer and 10 d under either laboratory thermoneutral or heat conditions. Somatotropin increased milk yield by 6.1 (21%), 8.1 (32%), and 7.3 kg (35%) under the farm summer, laboratory thermoneutral, and heat conditions, respectively. Somatotropin also increased milk fat by 15 and 19% and dry matter intake by 16 and 18% under laboratory thermoneutral and heat conditions, respectively. Somatotropin increased the efficiency of feed conversion into milk without any significant changes in body weight and temperatures. Somatotropin reduced plasma concentrations of triiodothyronine and cortisol and had no effect on plasma prolactin and insulin concentrations. Somatotropin did not increase water intake; however, hematocrit was decreased. The results suggest that stimulatory effects of bST on milk production are still observed on heat-stressed cows without any significant indications of additional heat stress.

Animals↗
PubMed1990

Effect of farm and simulated laboratory cold environmental conditions on the performance and physiological responses of lactating dairy cows supplemented with bovine somatotropin (BST).

A study was conducted to evaluate the effect of bovine somatotropin (BST) supplementation in twelve lactating dairy cows maintained in cold environmental conditions. Six cows were injected daily with 25 mg of BST; the other six were injected with a control vehicle. Cows were maintained under standard dairy management during mid-winter for 30 days. Milk production was recorded twice daily, and blood samples were taken weekly. Animals were then transferred to environmentally controlled chambers and exposed to cycling thermoneutral (15 degrees to 20 degrees C) and cycling cold (-5 degrees to +5 degrees C) temperatures for 10 days in a split-reversal design. Milk production, feed and water intake, body weights and rectal temperatures were monitored. Blood samples were taken on days 1, 3, 5, 8 and 10 of each period and analyzed for plasma triiodothyronine (T3), thyroxine (T4), cortisol, insulin and prolactin. Under farm conditions, BST-treated cows produced 11% more milk than control-treated cows and in environmentally controlled chambers produced 17.4% more milk. No differences due to BST in feed or water intake, body weights or rectal temperatures were found under laboratory conditions. Plasma T3 and insulin increased due to BST treatment while no effect was found on cortisol, prolactin or T4. The results showed that the benefits of BST supplementation in lactating dairy cows were achieved under cold environmental conditions.

Animals↗
PubMed1990

Suppressed peripheral blood lymphocyte blastogenesis in pre- and postpartal sheep by chronic heat-stress, and suppressive property of heat-stressed sheep serum on lymphocytes.

Phytohemagglutinin (PHA) and concanavalin A (Con A)-induced blastogenesis of peripheral blood lymphocytes was examined in heat-stressed pre- and postpartal sheep. The peak responses of lymphocytes to PHA and Con A in heat-stressed sheep revealed significant reduction before and after parturition compared with those in the corresponding control animals kept under thermoneutral conditions. Furthermore, the effect of serum from control or heat-stressed sheep on PHA-induced lymphocyte blastogenesis was examined. Supplementation of serum from heat-stressed sheep significantly suppressed the blastogenesis of lymphocytes obtained from healthy sheep, bovine, and human donors. Unlike dexamethasone, heat-stressed sheep serum did not inhibit IL-2 production by PHA-stimulated human peripheral blood lymphocytes. These results indicate that the immunosuppression of heat-stressed sheep is in part mediated by serum factor(s) that can modulate T-cell function in a species nonspecific manner.

Animals↗
PubMed1989

Suppression of T-lymphocyte blastogenesis by ovine trophoblast protein-1 and human interferon-alpha may be independent of interleukin-2 production.

Cells derived from the trophoblast tissue of a day 15 sheep conceptus released substances that inhibit incorporation of [3H]thymidine into phytohemagglutinin (PHA)-stimulated ovine lymphocytes. This effect was partially reversed by addition of antiserum to ovine trophoblast protein-1 (oTP-1), a major secretory product of day 13-21 sheep conceptuses and a protein structurally and functionally related to alpha-interferons (IFN-alpha). Human IFN-alpha, unlike dexamethasone, inhibits phytohemagglutinin-induced lymphocyte blastogenesis without reducing interleukin-2 (IL-2) production by the cultures, and conditioned medium containing IL-2 does not promote [3H]thymidine incorporation into ovine lymphocytes when oTP-1 is present. Thus, oTP-1, by virtue of being an IFN, may have a local immunomodulatory role by selectively inhibiting the proliferative responses of certain maternal immune cells to IL-2.

Animals↗
PubMed1989

Some hormonal characteristics of high and low yielding Holstein cows and water buffaloes located in temperate and subtropical environments.

The present study was carried out on 18 Holstein cows located in Missouri, USA (Holstein-M), 32 Holstein cows located in Egypt (Holstein-E), and 32 Egyptian water buffaloes (Buffaloes-E). Half of each group was high yielders and the other half was low with a mean daily milk yield of 32.2 and 18.6 kg for Holstein-M, 14.6 and 6.7 kg for Holstein-E, and 7.2 and 1.8 kg for Buffaloes-E, respectively. Blood samples were collected after the morning milking. Mean plasma thyroxine and triiodothyronine concentrations were significantly higher in Holstein-M than those in Holstein-E or Buffaloes-E. In all animal groups, the high yielders generally had lower plasma thyroxine and antidiuretic hormone but higher plasma triiodothyronine contents than the low yielders. Buffaloes had lower plasma cortisol and 9-fold higher plasma antidiuretic hormone as compared with the two Holstein groups.

Analysis of Variance↗
PubMed1989

Effect of xylazine in heifers under thermoneutral or heat stress conditions.

A study was performed to assess the effect of xylazine HCl (0.1 mg/kg of body weight, IV) in heifers maintained at thermoneutrality (18 C, 42% humidity) or under heat stress (33 C, 63% humidity) conditions. Xylazine caused 50 and 70% decreases in serum insulin concentrations in the thermoneutral and heat-stressed heifers, respectively. Xylazine-induced hypoinsulinemia was associated with hyperglycemia. In the thermoneutral group, serum glucose concentrations increased from a basal concentration of 75 mg/dl to 150 mg/dl after 15 minutes. In the heat stress group, the serum glucose concentration increased from 65 mg/dl to 105 mg/dl. Hyperglycemia peaked at 2 hours and remained high for 6 hours after xylazine administration. Heat-stressed heifers took a longer time (107 minutes) to stand than did heifers under thermoneutral conditions (41 minutes). The time to regain sensation to pain was significantly prolonged in heat-stressed heifers. Xylazine had no effect on body temperature and respiration rate in heifers under the thermoneutral condition, whereas it markedly induced hyperthermia and suppressed respiration rate in the heat-stressed heifers. Furthermore, the pulse rate was slightly decreased in thermoneutral heifers and was markedly decreased in the heat-stressed heifers.

Animals↗