Initial Sharp Rise Research Articles

A study on the zeta potential of microcapsules during ageing

Gelatin, methylcellulose and agar microcapsules were prepared with and without suphadiazine. The zeta potential of these microcapsules was measured at regular intervals during ageing at 45 degrees C. An initial sharp rise in zeta potential is followed by a progressive decrease. Zeta potential could prove to be a useful parameter to study the changes occurring in the encapsulating material of microcapsules during ageing.

Monokine production by hypersensitivity (Schistosoma mansoni egg) and foreign body (Sephadex bead)-type granuloma macrophages. Evidence for sequential production of IL-1 and tumor necrosis factor.

The present study examined the potential role of IL-1 and TNF in granuloma formation. Mice were given i.v. injections of Schistosoma mansoni eggs or Sephadex beads to induce synchronous immune T cell-mediated (hypersensitivity type) or nonimmune (foreign-body type) granulomas, respectively. Granuloma macrophages isolated at 2, 4, 8, 16, and 32 days of granuloma formation were evaluated for their capacity to produce IL-1 and TNF in response to 1 microgram/ml LPS. This was related to circulating levels of the acute phase protein, serum amyloid P (SAP) and expression of Ia Ag by monocytes and macrophages. Macrophages from nonimmune bead lesions were generally weak producers of IL-1 and TNF. In contrast, those from T cell-mediated egg lesions produced significant levels of both monokines. Moreover, there was a clear pattern of sequential monokine production such that IL-1 was produced in greatest amounts early (2 to 4 days), whereas TNF was produced later (8 to 16 days). Levels of SAP showed an initial sharp rise following particle embolization, then decreased rapidly in bead injected animals. However, mice with immune granulomas showed a prolonged elevation in SAP levels that corresponded to the period of maximal IL-1 production (2 to 4 days). Macrophage/monocyte Ia Ag expression was greatest at 8 to 16 days, corresponding to the period of TNF production. Bead injected animals showed low levels of Ia expression over the study period. These findings suggest that IL-1 may be important in the early recruitment stages of granuloma formation while TNF may take part in later maintenance or effector functions. The extent of production of both is likely influenced by the local or systemic milieu of lymphokines.

The distribution of malathion and some of its metabolites in tissues of the american cockroach, Periplaneta americana

1. The American cockroach was treated by topical application of 14C-malathion. The distribution of the label within the body tissues was found to be both rapid and extensive. 2. As much as 40% of the applied label was still present superficially in the cuticle even 24 hr post-application. 3. The overall tissue ranking order for 14C label was found to be: foregut > digestive tract contents > skeletal muscle > fat body > hindgut > midgut > nerve cord > brain > malpighian tubules. 4. Malathion, malaoxon and malathion monoacids were detected in the nerve cord plus brain, the digestive tract, skeletal muscle and fat body at 1, 2 and 24 hr after topical application of the insecticide. 5. At 24 hr post-application a significant proportion of malathion remained unmetabolised in all tissues examined. The highest levels of metabolic transformation were found in the digestive tract and fat body. 6. Insects were prostrate 24 hr after topical application of 14C-malathion. In these insects the greatest concentration of malathion and monoacids (expressed in relation to unit tissue wt) was found in the digestive tract. On the other hand, the nerve cord and brain contained the greatest concentration of malaoxon. 7. About 18% of applied 14C-malathion label partitioned into the tissue aqueous phase up to 24 hr after topical application but very little applied label was expired as 14CO 2 or excreted. 8. Although a neurotoxic action may be the cause of prostration and death, the extensive dissemination of malathion and its products belies the concept of any tissue specificity. 9. The haemolymph, after an initial sharp rise in malathion content, maintained a steady malathion level over the 24 hr experimental periods suggesting that the haemolymph is the main distributor of the insecticide to the various body tissues.

Adrenomedullary pressor responses to stimulation of the rostral hypothalamus in the rat: influence of adrenaline-induced vasodilation and reflex cardioinhibition.

Electrical stimulation (100 Hz, 1 ms, 150 microA, 10 s) of the anterior hypothalamus in chloralose-anesthetized rats evoked a biphasic pressor response consisting of an initial sharp rise in arterial pressure at the onset of stimulation, followed by a second elevation after cessation of the stimulus. This response was accompanied by an increase in plasma noradrenaline and adrenaline levels. Peripheral sympathectomy with guanethidine selectively abolished the primary phase of the biphasic pressor response, while bilateral removal of the adrenal medulla eliminated only the secondary component. After alpha-adrenergic blockade with phentolamine, the primary phase of the stimulation-induced response was reduced while the secondary pressor component was blocked and replaced by a significant hypotension. The intravenous administration of sotalol enhanced the secondary pressor component without affecting the stimulation-induced plasma noradrenaline and adrenaline responses. After treatment with atropine, the secondary pressor effect was also potentiated, as the reflex bradycardia normally associated with the response was eliminated. A subsequent administration of sotalol in these rats further potentiated the secondary pressor component to stimulation. In rats treated with atropine and sotalol, the sympathetic vasomotor and the adrenomedullary pressor responses could be dissociated according to thresholds and stimulus frequency or current-response characteristics. The results suggest that in intact rats, adrenaline-induced vasodilation and reflex cardiac inhibition contribute to either reduce or mask the adrenomedullary component of the biphasic pressor response evoked by stimulation of the anterior hypothalamus. The study also raises the hypothesis of a dual regulation of both components of the sympathetic system in the anterior hypothalamic region.

Similar poststimulatory pressor responses with different mechanisms in response to excitation of the locus coeruleus before and after acute adrenalectomy.

Electrical stimulation of the locus coeruleus in anesthetized rats evoked a biphasic pressor response consisting of an initial sharp rise in blood pressure at the onset of stimulation, followed by a second elevation after cessation of the stimulus. This response, which was accompanied by an increase in plasma noradrenaline and adrenaline levels, was stable and could be easily reproduced over time. Sympathectomy by administration of guanethidine selectively abolished the primary pressor response. beta-Adrenergic blockade by intravenous administration of sotalol enhanced the secondary pressor response without affecting the primary component. Adrenal demedullation performed 24-48 h before the experiments selectively prevented the secondary pressor component. In contrast, acute adrenalectomy carried out during the experiment to impair the adrenomedullary secretions eliminated the secondary pressor response to stimulation of the locus coeruleus only in sympathectomized or in sotalol-treated rats but not in intact rats in which the response persisted. The latter, however, could be abolished by the administration of either guanethidine or sotalol, and it disappeared following repeated stimulation of the locus coeruleus. The study demonstrates that similar poststimulatory pressor responses with different underlying mechanisms can be elicited on excitation of the locus coeruleus before and after acute adrenalectomy in the rat. The results also suggest that intraneuronal adrenaline may be involved in the response evoked in acutely adrenalectomized animals.

Late Paleocene to middle Eocene calcareous nannofossil biochronology from the Shatsky Rise, Walvis Ridge and Italy

The precision of late Paleocene to middle Eocene nannofossil datums is investigated by means of quantitative methods and correlated to the magnetic polarity stratigraphy, using sequences from the Northwest Pacific, Southeast Atlantic and Italy. It is the rule rather than the exception to find tails of very reduced abundances prior to, or after, a range of consistent and higher abundances. The absolutely first or final occurrence of a species, therefore, seldom provides a synchronous datum when material from different geographic areas are compared. On the other hand, synchroneity is often confirmed when the initial sharp rise or the final sharp decline in abundance is used as datum level. The use of datums not employed in the two principal existing nannofossil zonal schemes can substantially improve the biostratigraphic resolution. Two established zonal markers show abundance patterns making them unsuitable as datums: the first occurrences of Ellipsolithus macellus (base NP4, diachronous) and Tribrachiatus nunnii (base NP10 and Paleocene/Eocene boundary, too rare and too short range in open ocean sections). The first occurrence of either Fasciculithus spp. or Sphenolithus spp. is a better marker near the base of NP4. The first occurrence of Discoaster diastypus at 56.6 Ma represents a suitable replacement for recognition of the Paleocene/Eocene boundary.

Prediction of pressure surge in a one-component two-phase bubbly flow

Shock phenomena caused by a rapid valve closure in a one-component, two-phase bubbly flow were investigated experimentally using Refrigerant R-113 as the working fluid, and a theoretical analysis was conducted. The pressure transient in a one-component, two-phase bubbly flow is characterized by the existence of an exponential pressure decay just after the initial sharp pressure rise. This phenomenon is due to the mass transfer between the vapor and the liquid, that is, condensation. The profile of the pressure transient at each location along the channel was calculated numerically by solving the fundamental equations. By this analysis, the effects of heat transfer and mass transfer between the two phases were clarified. Simplified estimation methods for the potential surge and the equilibrium pressure rise are presented.

Pancreatic Secretory Proteins in Sera from Rats before and after Induction of Experimental Pancreatitis

This study has traced the behavior of rat anionic trypsin-like immunoreactivity and pancreatic secretory trypsin inhibitor (PSTI) immunoreactivity in the serum of rats undergoing bile-pancreatic duct infusions of buffered solutions with and without the addition of the bile salt taurocholate. Enzymatic analysis of alpha-amylase was also done. A mild pancreatic inflammation followed infusion of buffer alone, as determined by gross inspection of the pancreas and the behavior of serum levels of the above proteins. Animals infused with buffer and 4% taurocholate had major inflammatory changes, including gross hemorrhage into the gland, and marked elevations in serum levels of the three proteins studied. Graphic analysis of the serum levels revealed distinct sharp rises in the serum levels of all three proteins in the taurocholate group. In the buffered saline group only an initial sharp rise was present, followed by a prolonged decrease back towards base-line values. The immunoreactive trypsin in the taurocholate group was present in three fractions with different molecular weights: trypsin in complex with protease inhibitors, trypsinogen, and trypsinogen, and degradation products. PSTI immunoreactivity showed the molecular size of free inhibitor and that of degradation products. The presence of trypsin in complex with protease inhibitors indicates the formation of active trypsin during acute pancreatitis, which is further supported by the presence of degradation products of trypsin and PSTI.

Plant Sensitivity to Endogenous Ethylene in Relation to Species Characteristics

Summary Imposition of water stress either through waterlogging or droughting leads to changes in endogenous ethylene level in both Kalanchoe daigremontana , a CAM-plant, and Caltha polypetala , a hydrophyte. These changes consist of an initial sharp rise followed by a decrease in the level of ethylene. In Kalanchoe and in droughted Caltha the ethylene levels appear to be related to the degree of stress imposed. No such relationship has been observed with waterlogged Caltha .

Pressor responses and adrenomedullary catecholamine release during brain stimulation in the rat.

Electrical stimulation of the diencephalon and rostral mesencephalon produced a biphasic pressor response consisting of an initial sharp rise followed by a more prolonged elevation in blood pressure. Active sites from which comparable responses could be evoked were found in the ventral medial and lateral hypothalamus, in the region of the parafascicularis nucleus, and in the central gray matter and the tegmentum of the mesencephalon. Together with the biphasic pressor response brain stimulation also increased plasma catecholamine (CA) concentrations 10-fold. Either bilateral adrenalectomy or demedullation selectively abolished the secondary phase of the pressor response and greatly reduced the plasma CA response to stimulation. After chemical destruction of the terminals of the sympathetic neurones by intravenous administration of 6-hydroxydopamine (6-OHDA), the primary pressor phase was eliminated whereas the secondary phase as well as plasma CA concentration reached higher levels than in normal rats. 6-OHDA treatment combined with adrenalectomy completely abolished both pressor and CA responses. The results demonstrate that adrenomedullary mechanisms capable of increasing blood pressure significantly can be activated by electrical stimulation of different sites in the diencephalon and mesencephalon.

Comparison of rapid card agglutination test with the complement fixation test for diagnosis of Anaplasma marginale infection in Cattle in Colombia

Three hundred and thirty-nine serum samples collected from nine Holstein-Friesian calves before and during natural infection with Anaplasma marginale on the north coast of Colombia were used to compare the complement fixation (CF) and rapid card agglutination tests (CT) for the diagnosis of anaplasmosis. The positive agglutination of the CT always developed several days after the first CF reaction but then persisted. In contrast, the CF test showed an initial sharp rise in titer but then showed fluctuations between trace and 1 : 80 titers. The results indicated that under field conditions the CT was the simpler and more reliable test for the diagnosis of anaplasmosis in a single animal. The CF test remains useful in experimental situations where the earliest knowledge is required of the magnitude of immunological response to challenge.

Effects of glucagon on the splanchnic and the systemic circulation

1. 1. Dogs were treated with an intravenous injection of 2 mg of glucagon. Hepatic, celiac, and superior mesenteric arterial blood flows and concomitant cardiac output rates were measured. Local and total peripheral resistance was calculated. Heart rate, systemic arterial pressure, central venous pressure, and portal venous pressure were measured. Also, blood sugar, potassium, and blood gases were determined. 2. 2. Hepatic, celiac, and superior mesenteric arterial flows increased 41, 69 and 85 per cent, respectively, whereas concomitant cardiac output rates increased 36, 51 and 42 per cent, respectively. Local and total peripheral resistance significantly decreased. Heart rate increased and systemic arterial pressure declined. 3. 3. Although flows in the hepatic, celiac, and superior mesenteric beds were increased at a rate greater than that of cardiac output, the main effect of the hormone in increasing flow was secondary to its myocardial stimulatory effects. Only the superior mesenteric arterial bed had significant increase of flow out of proportion to the rise in cardiac output. 4. 4. Blood sugar increased sharply. The serum potassium showed an initial sharp rise after glucagon injection that was followed by a sharp fall which correlated with the appearance of hyperglycemia.

The etiology of acute brain swelling following experimental head injury.

T hE pathophysiology of acute head injury has been studied in experimental animals by numerous investigators. Occasionally cercbrospinal fluid pressure has been recorded, usually from the lumbar subarachnoid space or cisterna magna, and there has been uniform agreement tha t prolonged, severe intracranial hypertension does not occur following experimental concussion. An initial sharp rise in intracranial pressure, concomitant with the blow, has been studied in some detail, but this is quite transient, and any subsequent rise in intracranial pressure has been found to be inconstant and moderate in degree. In contrast to the observations in animals, a marked increase in intracranial pressure secondary to brain swelling is commonly observed in patients with head injuries, and this has been generally a t t r ibuted to the rapid development of cerebral edema. If severe brain swelling occurs, intracranial pressure must increase, but we have been unable to find a previous explanation for the failure to observe significant intracranial hypertension following experimental head injury. In prior experiments we presented evidence that the rise in intracranial pressure produced by expansion of an intracranial mass causes cerebral vasodilatation. The vasodilatation increases cerebral blood volume and produces a further rise in intracranial pressure. As this process continues, a very great increase in intracranial pressure may occur rapidly due to intense cerebrovascular congestion. As the difference between the arterial and intracranial pressures decreases, cerebral blood flow falls, and irreversible cerebrovascular dilatation ultimately occurs due to ischemic vasomotor paralysis, l~ The purpose of this preliminary report of our experience with experimental

Extreme-Pressure Lubrication and Wear. The Influence of Contact Stress on Metallic Wear

The wear of a steel pin terminating in a truncated 120° cone rubbing on the flat surface of a rotating disk was studied in relation to the initial contact stress. With white oil as the lubricant, three ranges of initial contact stress were employed: 152,000–157,000 psi, 67,000–76,000 psi and 47,000 psi. Typical time-dependent wear curves for the two higher pressure ranges were multistage in character, showing first a sharp rise in the amount of wear, then a levelling-off and finally a transition to rapid wear again. At 47,000 psi initial contact stress, wear was a linear function of time. A compounded extreme-pressure lubricant was studied at 250,000 psi and at 148,000–156,000 psi initial contact stress. The time-dependent course of wear in these cases showed only two stages: the initial sharp rise and the levelling-off. The significance of the early phases of an experiment on metallic wear with respect to the mechanism of extreme-pressure lubrication is discussed.