Body Weight Of Blood Research Articles

On the use of inhibitors of 4-hydroxyphenylpyruvate dioxygenase as a vector-selective insecticide in the control of mosquitoes.

Blood-sucking insects incorporate many times their body weight of blood in a single meal. Because proteins are the major component of vertebrate blood, its digestion in the gut generates extremely high concentrations of free amino acids. Previous reports showed that the tyrosine degradation pathway plays an essential role in adapting these animals to blood feeding. Inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD), the rate-limiting step of tyrosine degradation, results in the death of insects after a blood meal. Therefore, it has been suggested that compounds that block the catabolism of tyrosine could act selectively on blood-feeding insects. Here, we evaluated the toxicity against mosquitoes of three HPPD inhibitors currently used as herbicides and in human health. Of the compounds tested, nitisinone (NTBC) proved to be more potent than mesotrione (MES) and isoxaflutole (IFT) in Aedes aegypti. NTBC was lethal to Ae. aegypti in artificial feeding assays [median lethal dose (LD50 ): 4.53 μm] and in topical application (LD50 : 0.012 nmol/mosquito). NTBC was also lethal to Ae. aegypti populations that were resistant to neurotoxic insecticides, and to other mosquito species (Anopheles and Culex). HPPD inhibitors, particularly NTBC, represent promising new drugs for mosquito control. Because they affect only blood-feeding organisms, they represent a safer and more environmentally friendly alternative to conventional neurotoxic insecticides. © 2021 Society of Chemical Industry.

The guaiac-based fecal occult blood test in healthy dogs: Evaluation of the effects ofdiet, and the abilityof the test to detect fecal occult blood.

The guaiac-based fecal occult blood test (gFOBt) has been used for human colorectal cancer screening. It can detect the fecal occult blood (FOB) in dogs after oral administration of 20mg of hemoglobin/kg body weight of blood and is influenced by diet. The aims were to evaluate the effect of diet and the ability of gFOBt to detect FOB in healthy dogs after oral administration of autologous blood. Five healthy dogs were fed Purina Hypoallergenic (HA) and Gastrointestinal (EN) diets. Feces were tested with gFOBt before starting diets and at each defecation (hereafter referred to as fecal collection event) throughout the study period. Every 4days, increased doses of autologous blood were administered orally. The whole blood of one dog was progressively diluted with a saline solution, and dilutions were directly tested with the gFOBt, until a negative result was found. Twelve of 185 (6.5%) gFOBt were found to be positive. No associations between diet and gFOBt positivity were found. A significant association was found between the fecal collection event and gFOBt positivity (P<.001) and between doses of blood and gFOBt positivity (P=.048). The lowest dilution ensuring all positive tests was 6.5µgHgb /mL. The gFOBt was not influenced by either the HA or EN diets. The gFOBt positivity was associated with the dose of blood and the fecal collection event. However, caution is needed in the interpretation of results due to the lack of an association between gFOBt positivity and increasing doses of blood in the same dog.

Serotonin triggers cAMP and PKA-mediated intracellular calcium waves in Malpighian tubules of Rhodnius prolixus.

Rhodnius prolixus is a hematophagous insect vector of Chagas disease capable of ingesting up to 10 times its unfed body weight in blood in a single meal. The excess water and ions ingested with the meal are expelled through a rapid postprandial diuresis driven by the Malpighian tubules. Diuresis is triggered by at least two diuretic hormones, a CRF-related peptide and serotonin, which were traditionally believed to trigger cAMP as an intracellular second messenger. Recently, calcium has been suggested to act as a second messenger in serotonin-stimulated Malpighian tubules. Thus, we tested the role of calcium in serotonin-stimulated Malpighian tubules from R. prolixus. Our results show that serotonin triggers cAMP-mediated intracellular Ca(2+) waves that were blocked by incubation in Ca(2+)-free saline containing the cell membrane-permeant Ca(2+) chelator BAPTA-AM, or the PKA blocker H-89. Treatment with 8-Br-cAMP triggered Ca(2+) waves that were blocked by H-89 and BAPTA-AM. Analysis of the secreted fluid in BAPTA-AM-treated tubules showed a 75% reduction in fluid secretion rate with increased K(+) concentration, reduced Na(+) concentration. Taken together, the results indicate that serotonin triggers cAMP and PKA-mediated Ca(2+) waves that are required for maximal ion transport rate.

Role of an aquaporin in the sheep tick Ixodes ricinus: Assessment as a potential control target

Ticks undergo tremendous osmoregulatory stress as they take on up to 100 times their body weight in blood, returning about 75% of the ingested water and ions via their saliva into the host. We postulated that water channels, or aquaporins, involved in this mass water transport might be good targets for acaricide development. An aquaporin ( IrAQP1) identified in the sheep tick, Ixodes ricinus, was present only in tissues involved in mass water flux, namely the gut, rectal sac and especially abundant in the salivary glands. IrAQP1 was localised by in situ hybridisation in specific cell and acini types, possibly Type III acini, but absent from the type I acini that are responsible for rehydration of ticks in the non-feeding phase. Gene knockdown of IrAQP1 in isolated salivary glands completely inhibited dopamine-stimulated secretion. Further, IrAQP1 knockdown adult females had 50% reduced body weight gains over the first 5 days feeding on an artificial feeding apparatus and 21% at the point of engorgement on hosts. Haemolymph osmolarity was increased in the IrAQP1-knockdown ticks. Importantly, the blood volume ingested per body weight was reduced by 30%. Overall, it would appear that water passage from the gut to the saliva was disrupted and tick guts were simply too “full” to ingest more blood. However, double-stranded RNA interference of IrAQP1 did not affect mortality of the ticks which successfully fed to detachment at day 9. Overall, our data indicate that IrAQP1 plays a pivotal role in blood meal water handling through the gut and salivary gland, and although its disruption by double-stranded RNA interference dramatically affects feeding performance, ticks remained feeding on the host with subsequent potential pathogen transmission and, therefore, IrAQP1 is not a suitable candidate target for tick control.

Mechanistic aspects of the metabolism of 1,3-dichloropropene in rats and mice.

1,3-Dichloropropene (DCP) is used in agriculture for the control of nematodes in a variety of food crops. The major routes of metabolism for this halogenated aliphatic compound involve conjugation with glutathione and oxidation to carbon dioxide. An additional, minor route of metabolism proposed for this compound involves epoxidation to the corresponding 1,3-dichloropropene oxide (DCPO). Recent in vivo studies have provided evidence for the formation of DCPO in mice following intraperitoneal (ip) administration of 350-700 mg of DCP/kg, which is equal to, or exceeds, the reported oral LD(50) for this compound in mice [Schneider, M., et al. (1998) Chem. Res. Toxicol. 11, 1137-1144]. The potential for epoxidation of DCP in rats and mice at lower doses administered orally was therefore examined. Following oral administration of 100 mg of DCP/kg of body weight to F344 rats and B(6)C(3)F(1) mice, no DCPO was found in the liver or blood 0-90 min postdosing at a relatively low detection limit (10 ng/g of tissue). Only very low levels of DCPO were seen following ip administration of 100 mg of DCP/kg of body weight in blood of B(6)C(3)F(1) mice. Substantial levels of DCPO were only seen as a metabolite of DCP following ip administration of 700 mg of DCP/kg to B(6)C(3)F(1) or Swiss-Webster mice. Significant nonlinearity of DCP epoxidation was evident following ip administration, with approximately 130-fold less DCPO in mice given 100 vs 700 mg/kg. The time course of DCPO formation could only be followed for 76 min, due to 100% mortality in Swiss-Webster mice at the 700 mg/kg dose level. The formation of measurable DCPO in mice was also accompanied by acute hepatic damage following ip administration of 100 or 700 mg of DCP/kg to mice. In contrast, no evidence of acute toxicity was noted in mice treated with 100 mg/kg via oral gavage. These data suggest that measurable epoxidation of DCP to DCPO, in the rodent, occurs only at relatively high dose levels which result in acute hepatic injury or death. It was concluded that findings of DCPO formation at lethal doses administered via bolus internal injections do not reflect DCPO formation at lower doses administered via the natural portal of entry.

Effects of chronic beta-blockade on compensatory mechanisms during acute isovolaemic haemodilution in patients with coronary artery disease

We have compared compensatory mechanisms during acute isovolaemic haemodilution of 12 ml/kg body weight of blood with hydroxyethyl starch (450,000/0.7) exchange, in non-beta-blocked and beta-blocked patients with coronary artery disease. During haemodilution, mean concentrations of haemoglobin decreased from 12.8 (SEM 0.2) to 10.1 (0.1) g dl-1 (P < 0.01). Only beta-blocked patients had an increase in cardiac index (P < 0.01); in non-beta-blocked patients, cardiac index remained constant. In both groups oxygen extraction increased (P < 0.01), but the increase tended to be greater in non-beta-blocked patients (P = 0.06). Oxygen consumption was maintained in both groups. There were no ECG signs of myocardial ischaemia. We conclude that beta-blocked and non-beta-blocked patients with coronary artery disease tolerated well moderate haemodilution to a haemoglobin value of approximately 10 g dl-1, however, compensatory haemodynamic mechanisms differed fundamentally between the two groups.

Effects of Hemorrhagic Stress on Several Blood Parameters in Adult Rainbow Trout (Salmo gairdneri)

Blood was removed from ten adult rainbow trout (Salmo gairdneri) on a sequential daily (7 days), weekly (4 weeks), and monthly (1 month) schedule and analyzed for hematocrit, plasma protein, acid phosphatase (AP), lactic dehydrogenase (LDH), and creatine phosphokinase (CPK). Of the parameters examined, hematocrit, lactic dehydrogenase, and creatine phosphokinase were found to be the most significant indicators of stress due to repeated sampling. We showed that, under conditions similar to those of this investigation, daily and weekly sampling of approximately 0.2% of the body weight in blood produced decidedly deleterious effects of the test organisms. Starvation was a secondary stressor and is believed to have had an influence on blood characteristics as the study entered its later phases.

The Blood Volumes of Some Representative Molluscs*

ABSTRACT The reports of measurements of the blood volume of molluscs found in the literature are few in number and represent, in most cases, incidental observations rather than results of specific investigations. Leitch (1916) obtained by the bleeding of Planorbis a volume of blood which was 33% of the tissue weight. In 1931, Borden determined the blood volume of Planorbis corneus using the Weicker method and obtained a value of 58% of the total tissue weight. This higher value is to be expected, since it is impossible to remove all the blood from an animal by simple bleeding. In 1950, Martin &amp; Huston, using the inulin dilution method, reported the blood volume of Aplysia californicus to be 83·3% of the total weight. This is not surprising since Aplysia has a very extensive haemocoele, and more than half the body weight in blood can be drained in a few minutes from a single incision into the animal.

The life duration of the red blood cell of the macacus rhesus monkey

Abstract 1.1. A method is given for making permanent preparations of reticulocytes in monkey blood. 2.2. Curves are presented showing daily reticulocyte counts in two control and eight experimental animals, covering periods of from 120 to 170 days. 3.3. Two types of blood depletion were employed to stimulate hemopoesis: (1) withdrawal of large amounts (1 per cent of the body weight) at one operation and (2) fractional withdrawal of 5 per cent of the body weight in blood, at intervals of 72 hours (usually four operations). 4.4. The splan of life of the red blood cell of the macacus rhesus monkey was determined by autonomous blood replacement following hemorrhage. When this method is employed, a spontaneous reticulocyte shower occurs from 94 to 117 days later, indicating a reaction to the mass disappearance of the block of red cells originally mobilized to replace those lost by hemorrhage. The time lapse between the induction of the hemorrhage and the peak of the spontaneous reaction is interpreted to be the life span of the red blood cell in this animal. We realize that from these figures must be deducted the latent period of reaction, which in the monkey was found to be from two to four days.