[Oxygen consumption in the lungs of dogs with external hemorrhage and after reinfusion of blood]

In experiments on 10 dogs with external blood loss and reinfusion it was demonstrated, that in hemorrhagic and posthemorrhagic periods oxygen consumption by the organism is determined not only by O2 demands of the large circulation tissues, but to a great extent by demands in O2 in the system of lesser circulation, what is being evidenced by activation of the metabolic function of the lungs. It turned out that in pathogenesis of postinfusion respiratory insufficiency reactions of lipid oxidation in the lungs play a significant role.

Pharmacokinetic analysis of cloxacillin loss in children undergoing major surgery with massive bleeding

To determine the magnitude of cloxacillin loss during surgical procedures involving significant blood loss and high fluid replacement, we compared the pharmacokinetics of cloxacillin in children during craniomaxillofacial surgery with the disposition of the drug in healthy young adult volunteers with intact circulation. Blood loss during craniofacial operations may exceed blood volume, in some cases by as much as three times. Hemodynamic replacement with electrolyte solutions and blood products, which do not contain the drug, further dilute cloxacillin concentrations. In the patients that we studied, mean drug loss was estimated at 71%. Cloxacillin concentrations in serum fell below the lower range of the MIC for Staphylococcus aureus during significant portions of the surgical procedures. Thus, the traditional dosing of cloxacillin during prolonged operations with massive blood loss is inadequate. A more frequent dosing interval or priming of all replacement fluids with the drug may be required to maintain therapeutic levels. Our findings suggest that massive blood loss is likely to have a dramatic effect on the level of any drug with a small distribution volume. If such a drug is essential to the patient's well-being (e.g., antibiotics, antiarrhythmics, and anticonvulsants), it must be replaced promptly.

Vasopressin and atrial natriuretic peptide release in cardiopulmonary denervated dogs

To assess the effect of cardiopulmonary denervation on the release of arginine vasopressin (AVP) and atrial natriuretic peptide (ANP), either hemorrhage (1.0 ml.kg-1.min-1, for 40 min) or an infusion of 3% dextran in lactated Ringer solution (RL) (3% dextran in RL, 1.0 ml.kg-1.min-1, for 40 min) was carried out in chronic cardiopulmonary denervated (CPD, n = 7) and sham-operated (SO, n = 7) dogs under anesthesia. Plasma AVP increased significantly in both groups during hemorrhage, but its rise was significantly attenuated in CPD dogs. Plasma ANP decreased similarly during hemorrhage in both groups. An infusion of 3% dextran in RL decreased significantly plasma AVP during its whole period in SO dogs, but AVP release was only suppressed in the late period in SO dogs. Plasma ANP increased significantly during its infusion in both groups. These results indicate that cardiopulmonary denervation may attenuate the release of AVP in response to either hemorrhage or blood volume expansion but may not affect the release of ANP in response to the blood volume change. Moreover, a large increase in plasma ANP may attenuate the release of AVP.

A comparison of alpha 1-proteinase inhibitor methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone and specific beta-lactam inhibitors in an acute model of human polymorphonuclear leukocyte elastase-induced lung hemorrhage in the hamster

A pharmacokinetic model is described for testing of polymorphonuclear leukocyte (PMN) elastase inhibitors administered by intratracheal or aerosol dosing of hamsters. Acute lung injury, measured as hemorrhage occurring within hours after intratracheal instillation of human PMN elastase, correlated directly with the amount of active enzyme instilled. Hemorrhage began within minutes of elastase instillation, was maximal within 1 h, and remained constant for up to 5 h subsequently. Therefore, inhibition of hemorrhage was used as an assay of the effectiveness of various PMN elastase inhibitors given by the intratracheal route. Lung hemorrhage could also be induced by intratracheal instillation of other elastolytic enzymes, such as thermolysin, and inhibition of hemorrhage was seen only with inhibitors active against the type of elastase used. Methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone (MeOSuc-AAPV-CMK), as well as alpha 1-proteinase inhibitor (alpha 1PI) but not tosyl-lysine-chloromethylketone (tosyl-lysine-CMK), inhibited the hemorrhage caused by human PMN elastase, but the specific inhibitors of this enzyme had no effect on thermolysin-induced lung hemorrhage. The duration of activity of these compounds as elastase inhibitors in this model correlated directly with the extent of their persistence in lung lavage fluid as determined by HPLC analysis of compound recovered by bronchoalveolar lavage. (ABSTRACT TRUNCATED AT 250 WORDS)

Carbon monoxide-mediated brain lipid peroxidation in the rat

Clinical and animal data suggest that the pathogenesis of CO poisoning extends beyond the inhibition of hemoglobin function, but no mechanism has been identified. Evidence of neurological compromise, particularly loss of consciousness, has been implicated as a marker for increased mortality and morbidity in clinical reports. Experiments were carried out with rats to assess whether CO exposure may cause brain lipid peroxidation. With the use of two methods, measurement of conjugated dienes and thiobarbituric acid reactivity, brain lipid peroxidation could be documented as a result of exposure to CO at a concentration sufficient to cause unconsciousness. Products of lipid peroxidation were increased by 75% over the base-line values 90 min after CO exposure. Unconsciousness was associated with a brief period of hypotension, so brief that in itself it caused no apparent insult. Lipid peroxidation occurred only after the animals were returned to CO-free air, and there was no direct correlation with the carboxyhemoglobin level. This work may provide an explanation for a number of currently poorly understood clinical observations regarding CO poisoning.

Atropine pharmacokinetics are affected by moderate hemorrhage and hypothyroidism

Atropine is used both to treat a variety of clinical disorders and as an antidote to cholinesterase poisoning. While various conditions affect the physiologic responses to atropine, little is known of the pharmacokinetics of this drug except under resting conditions. Pharmacokinetic studies were performed in mongrel dogs under two experimental conditions, moderate hemorrhage and hypothyroidism, to determine whether im absorption and elimination of atropine (0.05 mg/kg body weight) were affected by changes in hemodynamic or metabolic status. Using a randomized, crossover experimental design, it was found that during hypovolemia the mean volume of distribution was reduced by 22% (2.50 +/- 0.62 vs. 3.21 +/- 0.63 L/kg), with no changes in peak serum level, total atropine availability, elimination half-life, or whole-body clearance. Hypothyroidism was associated with a significant increase in peak serum atropine concentration (26.4 +/- 3.9 vs. 20.6 +/- 4.9 ng/ml) and drug bioavailability (48.5 +/- 8.8 vs. 30.0 +/- 10.7 ng/ml.h), while the clearance was reduced by 39% (426 +/- 34 vs. 696 +/- 187 ng/ml.min). These results suggest that atropine kinetics are not altered appreciably during moderate hemorrhage. In hypothyroidism, alterations in atropine pharmacokinetics may warrant modification of drug dose and frequency of administration.

Effect of vagotomy on brain and plasma atrial natriuretic peptide during hemorrhage

These experiments investigated the change in brain, atrial, and plasma concentrations of atrial natriuretic polypeptide (ANP) after a 33% hemorrhage and the role of vagal nerve input in these changes. In rats, hemorrhage decreased plasma ANP from 246 +/- 48 to 41 +/- 7 pg/ml, but in a hypothalamic tissue block ANP increased from 19.0 +/- 0.9 to 25.5 +/- 0.6 ng/g tissue (P less than 0.05). Bilateral vagotomy was followed by a very large increase in plasma ANP to 703 +/- 198 pg/ml. Atrial pressures, however, fell after vagotomy from 2 +/- 2 to 1 +/- 1 mmHg. Therefore, the effect was not due to increased atrial stretch. Right atrial ANP levels were also elevated by vagotomy, but left atrial ANP concentrations did not change with vagotomy or hemorrhage. After hemorrhage in vagotomized rats, plasma ANP decreased to 79 +/- 6 pg/ml. After vagotomy, the ANP concentration in the hypothalamic block did not rise in response to hemorrhage. The results indicate that the vagus nerves provide a tonic inhibition of ANP levels in atria and plasma. The results cannot be explained by atrial distension. The results show independence of brain and plasma ANP and uncover a tonic vagal inhibition of ANP release.

Hepatic denervation alters hemodynamic response to hemorrhage in conscious rats

We investigated the effect of liver denervation on cardiovascular homeostasis. Three days after surgical denervation of the liver, hemodynamic studies (radioactive microsphere method) were conducted in conscious rats. The efficacity of the liver denervation procedure was confirmed by a significant decrease in norepinephrine content in various lobes of the liver. Liver denervation did not affect either systemic or splanchnic resting hemodynamics. However, hemorrhage (2 ml per 100 gm body weight) induced a decrease in cardiac index which was significantly more marked in rats with liver denervation (-62 +/- 3%) than in sham-operated rats (-47 +/- 5%; p less than 0.05). This more severe response to hemorrhage may be due to a lack of portal territory vasoconstriction since the fraction of cardiac output reaching portal territory did not decrease during hemorrhage in rats with liver denervation (16 +/- 1% to 14 +/- 1%) but significantly decreased in sham-operated rats (from 15 +/- 1% to 11 +/- 1%, p less than 0.05), this value being significantly lower, after hemorrhage, in sham-operated rats than in denervated rats. The results confirm the lack of tonic neural influence on hepatic circulation during physiological experimental conditions and indicate that hepatic nerve function has a significant contribution to the overall cardiovascular homeostasis.

Effect of hemorrhage and resuscitation on subcutaneous, conjunctival, and transcutaneous oxygen tension in relation to hemodynamic variables

Subcutaneous (PscO2), conjunctival (PcjO2), and transcutaneous (PtcO2) oxygen tension values were measured in anesthetized dogs subjected sequentially to hemorrhage and reinfusion of the shed blood. Intravascular pressure, hemodynamic variables, and oxygen transport variables were measured simultaneously. During hemorrhage, PscO2 was the first of the PO2 measurements, and among the first set of hemodynamic variables that differed significantly from control values. During continuous bleeding, PscO2 and PcjO2 fell rapidly, the decline of PscO2 and PcjO2 was similar and significantly higher than that found for PtcO2. After reinfusion of shed blood, PscO2 was the last of PO2 measurements, and among the last set of hemodynamic variables, to return to control values. While PaO2 remained constant, PvO2 decreased significantly during hemorrhage and normalized during resuscitation. Unheated instruments for measuring PscO2 and PcjO2 are reliable indicators of peripheral perfusion during hemorrhage and resuscitation. Subcutaneous oxygen monitoring, in particular, seems capable of assessing early blood loss and adequacy of resuscitation after acute hemorrhage, and may be clinically useful.

[Metabolic and immunologic disorders in the pathogenesis of iron deficiency anemia and its complications]

Sixty-five patients with iron deficiency anemia have been examined for lipid peroxidation, antiperoxidation protection and immunoreactivity. It was noted that progression of the disease was associated with developing hypoxia followed by enhancement of lipid peroxidation and derangement of immunity. Origin of complications may be related to abnormal lipid peroxidation and defects in immunity.

[Effect of intravenous laser irradiation of blood on the homeostasis in patients with hemorrhagic pancreatitis]

After intravenous blood exposure to low-intensity radiation of Helium-Neon laser patients with haemorrhagic pancreatitis exhibited inhibition of the blood proteolytic activity; enhancement of free-radical oxidation, kallikrein-kinin system activity, blood oxygen transport, correction of endotoxic pancreatogenic syndrome. In addition, the positive shifts were also observed in the immunological status, morphofunctional characteristics of the red blood cells and hemoglobin, hepatic and renal functions. In severe pancreatogenic endotoxicosis the highest response was achieved with combined use of hemosorption and intravenous laser irradiation.

Glucose kinetics in haemorrhagic hyperglycemia

Haemorrhagic hyperglycemia has been demonstrated to have beneficial effects on fluid homeostasis, and insulin resistance has been reported in vitro after haemorrhage. In the present study the interrelation of peripheral levels of insulin, glucagon, and adrenalin and the rate of glucose disappearance (Rd) in haemorrhagic hyperglycemia were determined in vivo. Rd was determined by single injection of 3-3H-glucose in three groups of postprandial rats: controls, rats submitted to rapid blood loss, and rats receiving a constant 30% glucose infusion. The level of hyperglycemia after bleeding was 22.9 +/- 1.9 mmol x 1(-1) (mean +/- 1 S.E.), and during infusion it was 20.4 +/- 1.4 mmol x 1(-1). The Rd value of controls was 8.2 +/- 0.5 mmol x 100 g-1 x min-1, during glucose infusion it was 34.1 +/- 0.6, and after haemorrhage it was 9.7 +/- 0.4. Both treatments increased insulin levels by greater than 200%. These results show an important role of insulin resistance in causing hyperglycemia after experimental haemorrhage in the rat.

Catecholamine activity in paraventricular hypothalamus after hemorrhage in cats

Temporal changes in catecholamine activity within the paraventricular nucleus (PVN) of the hypothalamus were assessed using in vivo voltammetry after moderate hemorrhage in chloralose-anesthetized cats. Oxidation current was measured with carbon microelectrodes, and the change at +250 mV was used as an estimate of catecholamine activity. The magnitude and directional change in catecholamine activity was assessed for each site during the initial 3 min of blood loss. Of 62 recording sites, 45 sites were located along the rostrocaudal extent of the medial PVN. Fifteen of these 45 sites exhibited an increase, 15 others exhibited a decrease, and the remaining 15 sites exhibited no change in catecholamine activity. The magnitude of change in oxidation current was independent of the magnitude of the decrease in arterial pressure after hemorrhage. Twelve of the 15 sites that exhibited increases in catecholamine activity were located in the caudal PVN along its dorsomedial aspect, whereas the location of sites that exhibited decreases in catecholamine activity were more widely distributed throughout the nucleus. These data are consistent with the hypothesis that an increase in the release of catecholamines within the caudal PVN in response to hemorrhage is facilitatory for the release of adrenocorticotropin and/or vasopressin.

Intestinal blood flow and oxygen consumption: responses to hemorrhage in the developing piglet

Age-related differences in the intestinal hemodynamic and oxygenation responses to arterial hemorrhage were studied in anesthetized and ventilated 1-d, 3-d, 1-wk, and 2-wk-old piglets. Steady-state values of superior mesenteric blood flow, venous pressure, and arteriovenous oxygen difference were obtained before and after 5 and 10 mL/kg arterial hemorrhage. With 5 mL/kg hemorrhage, intestinal blood flow fell significantly below baseline values, but oxygen extraction increased to maintain oxygen uptake at control levels in all age groups. In contrast to 2-wk-old piglets, the intestine of 1-d, 3-d, and 1-wk-old animals could not compensate for the greater reduction in blood flow produced by 10 mL/kg hemorrhage, resulting in a significant reduction in oxygen uptake. Thus, the intestine of developing piglets up to 1 wk of age appears to be at greater risk for tissue hypoxia induced by arterial hemorrhage than that of older animals.

Two-cytochrome metabolic model for carotid body PtiO2 and chemosensitivity changes after hemorrhage

O2 microelectrode measurements were made in the cat carotid body (CB) at normal control blood pressures (C) and after hemorrhage (H) to reduce mean arterial blood pressure [C, 98.7 +/- 4.6 (SE) mmHg; H, 58.1 +/- 1.8; P less than 0.001; paired t test; n = 9 cats]. Mean tissue PO2 (PtiO2) was significantly lower (C, 78.4 +/- 3.0 Torr; H, 65.3 +/- 4.8; P less than 0.01). Except for two experiments with good autoregulation, the decrease in PtiO2 correlated with the reduction in blood pressure (r = 0.791, P less than 0.005). Measurements of O2 disappearance curves (DCs) and sinus nerve discharge (ND) were obtained after blood supply was occluded for 30-45 s (56 C DCs, 44 H DCs). Disappearance rates (dPO2/dt) were significantly slower after hemorrhage (C, -7.52 +/- 0.47 Torr/s; H, -6.60 +/- 0.44; P less than 0.01), decreasing by 0.656 Torr/s for each 10 Torr fall in PtiO2 (r = 0.626, P less than 0.05). Resting ND before occlusion increased during hypotension (11.6 +/- 2.9% of control, P less than 0.01) and correlated with the decrease in PtiO2 (r = -0.792, P less than 0.005). A computer simulation was performed for a two-cytochrome metabolic model with a second, low-O2-affinity oxidase in addition to normal oxidative metabolism. The effects of cat oxyhemoglobin and blood pH on the O2 DC measurement were also taken into account. The simulation for the two-cytochrome model was consistent with our experimental data and predicts reductions in blood flow and O2 metabolism with hypotension after hemorrhage that have similarities, as well as aspects that disagree, with previous reports in the literature.

Potentiated cortisol response to paired hemorrhage: role of angiotensin and vasopressin

Potentiated adrenocorticotropin (ACTH) and cortisol responses occur after the second of two small hemorrhages (hems) spaced 24 h apart in the dog. To test whether increased responses of other hormones might be associated with this effect, we examined plasma renin activity (PRA), angiotensin II (ANG II), and vasopressin after paired 10% hem (H1 and H2) spaced 5 h apart in chronically prepared conscious dogs. Cortisol secretion increased after each hem, and the response to H2 was larger (P less than 0.05; H1 peak at 6.8 +/- 1.3 micrograms/min vs. H2 peak at 18.3 +/- 5.3 micrograms/min). ACTH did not change after H1 but increased after H2, and the H2 response was larger (P less than 0.01). Vasopressin increased after each hem, and the H2 response was larger (P less than 0.01). The time courses of ACTH and vasopressin responses were similar after H2 (significant increases by 8 min). PRA and ANG II increased by 4 min after each hem, and although the difference was small the early PRA and ANG II responses were greater after H2. Blood volume and hem volume did not differ between hems. Hemodynamic responses to the hems were not different. We conclude that, although the PRA and ANG II respond rapidly enough after hem to influence pituitary responses, the slightly greater responses of these factors to H2 are not responsible for greatly increased pituitary-adrenal responses to H2. On the other hand, the markedly potentiated vasopressin response to H2, which parallels that of ACTH, suggests that vasopressin may mediate the increased ACTH responses to H2.

Effect of transection on the blood-spinal cord barrier of the rat after isolation from descending sources

The disruption of descending pathways and subsequent release of vasoactive neurotransmitters may contribute to the abnormal vascular permeability observed after spinal cord injury. Therefore, the relationship between disruption of long descending fiber tracts in the rat spinal cord and the development of blood-spinal cord barrier breakdown to the protein horseradish peroxidase (HRP) was evaluated. This was accomplished by first transecting the cord in order to deplete transmitter stores in the distal (caudal) segments. One month after this isolation procedure, a second transection was made several segments distal to the first transection. The axial distribution of barrier permeability to HRP was evaluated at both the light and electron microscopic levels in this 'isolated cord' preparation. Camera lucida drawings, delineating the distribution of tracer leakage in the spinal cord, were used to quantify the extent of protein extravasation. Vascular leakage of the tracer was identified as early as 1 h postinjury but was restricted to segments adjacent to the second transection. By 1 day after injury, protein extravasation was more marked, as compared to the earlier time points, and axial spread of barrier breakdown occurred along more distal vascular sites. Abnormal permeability to HRP was confirmed at the ultrastructural level where the protein was present within vesicles in the endothelium and the surrounding smooth muscle layer and basal lamina. The tracer was also identified in the cytoplasmic compartment of neurons and glia and within the adjacent extracellular space.

Transcutaneous oxygen tension measurements during hemorrhagic hypoperfusion using Trendelenburg and the pneumatic antishock garment

Transcutaneous oxygen tension (PtCO2) was observed during hemorrhagic hypoperfusion using four therapeutic modalities: pneumatic antishock garment (PASG), 20 degrees Trendelenburg positioning, combined PASG-Trendelenburg, and whole blood infusion. Anesthetized mongrel dogs were mechanically ventilated. A heated transcutaneous oxygen sensor was applied to the skin overlying the sternum. Animals were bled over 10 min of 25% of their calculated blood volume. A therapeutic intervention was applied at the onset of hemorrhage (PASG, Trendelenburg, PASG-Trendelenburg or control). All animals were observed for 20 min, then during a 10-min shed blood reinfusion period, and for 20 min thereafter. PtCO2 was measured continuously and the following were measured serially: cardiac output, mean arterial pressure (MAP), mixed venous oxygen tension (MvO2), and arterial oxygen tension (PaO2). Cardiac index (CI) and the oxygen extraction ratio were calculated. PtCO2 decreased immediately after hemorrhage in all animals. Control values remained consistently below values for active interventions during this time. All groups regained baseline levels of PtCO2 after reinfusion of shed blood volume. PaO2 remained nearly constant during all experiments. MAP and CI fell in all groups following hemorrhage but did so less precipitously in the PASG group. The PASG and PASG-Trendelenburg groups showed the greatest increase in CI during reinfusion. These results suggest that when PtCO2 is relied upon as an indicator of adequacy of resuscitation during moderate hemorrhagic shock, that cutaneous perfusion may be improved by the PASG or Trendelenburg position, and that perfusion is most effectively restored by blood infusion.

Hemorrhage produces abnormalities in lymphocyte function and lymphokine generation

Hemorrhage has been shown to produce abnormalities in lymphocyte function, particularly in the proliferative response to mitogens such as PHA and Con A. In order to better examine the hemorrhage-induced alterations in immune function, we determined the effects of blood loss in mice without any surgical manipulation on lymphocyte populations and subpopulations, cellular activation, and lymphokine production. Hemorrhage induced no changes in cell numbers in the spleen, thymus, lymph nodes, and bone marrow. No alterations in the relative percentages of B (B220+, mu+) and T (Lyt-1+, Lyt-2+, T3+, L3T4+) cell subpopulations were found in any organ after blood loss. Significant decreases in splenocyte proliferation in response to Con A, IL-2R expression and blast formation occurred after hemorrhage. IFN-gamma production increased 24 and 48 h post hemorrhage. Decreases in IL-2, IL-3, and IL-5 generation were present 2 h after blood loss. IL-2 production remained significantly decreased for 48 h posthemorrhage, then increased to more than twice normal levels 72 h posthemorrhage, and subsequently returned to prehemorrhage values. These results demonstrate that hemorrhage produces widespread alterations in immune function without affecting lymphocyte population and subpopulation numbers.

Studies on monoamine levels in rat myocardium in different stresses

Albino rats were exposed to isolation, haemorrhagic, and psychic stress. The myocardial norepinephrine (NE), epinephrine (E), dopamine (DA), 5-hydroxytryptamine (5HT) and 5-hydroxy indole acetic acid (5HIAA) were quantitatively estimated at varying periods of time. The results indicate that 5HT, E, and DA are the common denominators in various types of stress and show similar qualitative changes in all the stresses studied whereas norepinephrine shows both quantitative and qualitative differences in the various stresses studied indicating thereby a differential modulatory mechanisms operating for the release of noradrenaline.

Evidence of increased gluconeogenesis during hemorrhage in fed and 24-hour food-deprived rats

Food withdrawal 24 hr before hemorrhage has been shown to increase experimental post-hemorrhage mortality, and survival is associated with the degree of hyperglycemia. Lack of hyperglycemic response has been attributed to depleted glycogen reserves after 24-hr food withdrawal. To investigate the effect of short-term food deprivation on glucose metabolism during hemorrhagic stress, glucose production (rate of appearance, Ra), glucose uptake (rate of disappearance, Rd), glucose clearance, and glucose recycling were investigated in fed and 24-hr food-deprived rats under basal conditions, and during hemorrhagic hypotension using 3-H3-U-C14-glucose. During hemorrhage, blood glucose levels were higher in fed rats. Hemorrhage induced a decrease in glucose clearance irrespective of nutritional state in both 24-hr starved animals and rats in the postprandial state. Calculated glucose recycling increased in both groups after hemorrhage. The results indicate that hemorrhagic stress induces a rapid increase in gluconeogenesis, as reflected by increased glucose recycling.

The effect of repetitive haemorrhage on plasma cortisol, beta-endorphin and N-terminal pro-opiomelanocortin in conscious sheep

We measured the effect of repeated haemorrhagic stress, performed on four consecutive days in conscious adult sheep, on the plasma concentrations of cortisol and ACTH-related peptides to determine whether the pituitary-adrenal response was altered by stress repetition. Peptides from the C-terminus of the ACTH pro-hormone was measured by beta-endorphin RIA. Glycopeptides derived from the N-terminus of the ACTH pro-hormone were measured by tau 3-MSH RIA. The immunoreactive tau 3-MSH in sheep plasma was found to have an apparent molecular weight of approximately 10,000 by gel chromatography through Sephadex G-75, which is similar to the size of the major circulating form of pro-tau-MSH found in human and rat plasma. Daily haemorrhage consistently elevated plasma concentrations of cortisol and pro-tau-MSH. There was no significant difference in the daily responses of either cortisol or pro-tau-MSH when considered individually. However, there was a significant change over the four days in the relationship between the cortisol and pro-tau-MSH responses, as judged by analysis of variance of the difference in daily z-scores of cortisol and pro-tau-MSH. This trend indicated a relative increase in the secretion of pro-tau-MSH from the pituitary compared to the cortisol response, and suggested that repeated exposure to stressful stimuli may alter the pituitary-adrenal-axis.

Biological half-time in rats exposed to nickel monosulfide (amorphous) aerosol by inhalation

This study reports the biological half-time of amorphous nickel monosulfide(NiS(A)) aerosol retained in rat lungs. Wistar male rats were exposed to NiS(A) aerosols (mass median aerodynamic diameter:4.0 microns) for a single 4 h exposure, or for 7 h/d, 5 d/wk for 1 mo. The average exposure concentrations were controlled at 107 mg/m3 for the single exposure and at 8.8 mg/m3 for the repeated exposures by a dust generator consisting of a continuous fluidized bed with an overflow pipe and a screw feeder. After the exposures, the nickel contents in the rat organs, blood, and urine were measured and histopathological examinations were performed. The biological half time of NiS(A) in rat lungs was 20 h, which was extremely shorter than 21 mo of green nickel oxide (NiO(G)). There were no malignant tumors in any of the exposure groups.

Effects of hemorrhage on interleukin-1 production

Depression of lymphocyte proliferative response occurs after trauma and hemorrhage. Because abnormalities in interleukin-1 (IL-1) production can result in depression of mitogen-induced lymphocyte proliferation, we investigated the effects of unanesthetized hemorrhage on IL-1 generation. The capacity of peripheral blood monocytes to produce IL-1 increased more than five fold by 2 h after loss of 30% of the total blood volume and returned to normal by 12 h after hemorrhage. Removal of 15% of total blood volume did not result in any alterations in IL-1 production. These results show that the diminished lymphocyte proliferative response which occurs after unanesthetized hemorrhage was not due to decreased IL-1 production. The increase in IL-1 generation which occurs shortly after severe hemorrhage may play a role in mediating the acute phase reaction which follows hemorrhage and trauma.