Acquisition of yersinia murine toxin enabled Yersinia pestis to expand the range of mammalian hosts that sustain flea-borne plague

Yersinia murine toxin (Ymt) is a phospholipase D encoded on a plasmid acquired by Yersinia pestis after its recent divergence from a Yersinia pseudotuberculosis progenitor. Despite its name, Ymt is not required for virulence but acts to enhance bacterial survival in the flea digestive tract. Certain Y. pestis strains circulating in the Bronze Age lacked Ymt, suggesting that they were not transmitted by fleas. However, we show that the importance of Ymt varies with host blood source. In accordance with the original description, Ymt greatly enhanced Y. pestis survival in fleas infected with bacteremic mouse, human, or black rat blood. In contrast, Ymt was much less important when fleas were infected using brown rat blood. A Y. pestis Ymt−mutant infected fleas nearly as well as the Ymt+ parent strain after feeding on bacteremic brown rat blood, and the mutant was transmitted efficiently by flea bite during the first weeks after infection. The protective function of Ymt correlated with red blood cell digestion kinetics in the flea gut. Thus, early Y. pestis strains that lacked Ymt could have been maintained in flea-brown rat transmission cycles, and perhaps in other hosts with similar blood characteristics. Acquisition of Ymt, however, served to greatly expand the range of hosts that could support flea-borne plague.

Gel Chromatographic Examination of Serum of Rats and Hamsters Under Artificial and Natural Hibernation

In this study, molecular composition of hamster and rat blood was studied by gel permeation chromatography under natural (NH) and artificial hibernation (AH). The control group was represented by 5 fractions of molecules in hamsters and 7 in rats. The areas under peaks of the fractions similar in molecular weight in hamsters and rats were larger in rats. NH was characterized by appearance of new fractions (1,350, 2,350, and 6,350 Da) and an increase in areas under peaks of the control fractions (1,140 and 1,980 Da). Artificial hibernation in rats led to an increase in areas under peaks of 1,140 Da fraction, a decrease in that of 530 Da, and disappearance of 1290 Da, as well as the appearance of new fractions (650, 830, 950, 2350, and 5110 Da). Two hrs of later AH, the areas under peaks of 1,140 and 1,520 Da fractions were greater and that of 530 Da was lesser; 650, 2,350 and 5,110 Da fractions disappeared, 1,290 Da reappeared and new fraction of 4,030 Da appeared. New fractions of 5,820 and 6,530 Da were found 24 hrs later. In hamsters under AH, the areas under peaks of 1,140, 1,600, and 3,330 Da increased; as well as a new peak in 5,280 Da appeared, both in the control rats and those in 24 hrs after AH.

The Possible Antidiabetic Effect of Ficus carica L. Tablet on lloxan-Induced Diabetes Model in Rats

BACKGROUND: Fig leaves are reported to have an effect on reducing blood glucose levels. However, the use of fresh leaves makes the effects obtained is not measurable and efficient. AIM: The purpose of this research was to determine the antidiabetic potential of ethanol extract of fig leaves and to optimize tablet dosage formulations. METHODS: Four tablet formulas were made using the wet granulation method. Formula I (FI), Formula I (FII), and Formula III (FIII) groups to give a tablet of ethanol extract of fig leaves with a dose of 40 mg, 60 mg, and 80 mg and placebo treatment group. There were eight groups of male rats strain Wistar treated as follows: Normal control, negative control, positive control (metformin tablets), basis group, placebo treatment group, F1, F2, and F3 groups. The antidiabetic activity was evaluated from a decrease in rat blood glucose levels. Previously, rats were induced first using alloxan 150 mg/kg intraperitoneally to damage β-pancreatic cells so that the rats could experience increased blood glucose levels. After giving treatment to each group for 14 days, a rat blood sample was then taken on days 9 and 14, which were then analyzed by the GOD PAP method with readings carried out using a spectrophotometer with a wavelength of 500 nm. RESULTS: The average weight (mg) of FI tablets (617.8 ± 3.21%), FII (629.35 ± 8.16%), and FIII (643.6 ± 6.21%), and placebo tablet (666.45 ± 4.36%). As for the uniformity of size, all formulas have a diameter of 0.9 ± 0.0 (cm). For the hardness values of FI (5.7 kg), FII (1.31 kg), and FIII (3.09 kg), placebo tablet (2.98%). The value of friability FI (1.42%), FII (11.8%), and FIII (0.84%), placebo tablet (1.16%). While the disintegration time of FI (11.02 min), FII (10.10 min), and FIII (17.00 min), placebo tablet (12.23%). As for the uniformity of size, all formulas have a diameter of 0.9 ± 0.0 (cm). Whereas the dissolution rate (DE45) of each formulation decreased with increasing dose of extract, FI (73.73%), FII (74.80%), and FIII (69.80%). The treatment group of the ethanol extract of fig leaves at a dose of 40 mg, ethanol extract of fig leaves at a dose of 60 mg, and ethanol extract of fig leaves at a dose of 80 mg could reduce rats’ blood glucose levels with statistically significant results (p < 0.05) compared to negative group. When it was compared to the positive group, it had significant results with a statistical value (p < 0.05). CONCLUSION: Ethanol extract of fig leaf tablets had a significant effect on lowering rats’ blood glucose levels.

Dynamics of Biochemical and Cytological Parameters of Rat Blood in Simulated Chronic Alimentary Methionine-Induced Homocysteinemia

Under the conditions of a chronic methionine diet (daily addition of amino acids to food (0.15 g/100 g) and water (1% solution)) during 2–12 weeks, the dynamics of liver tests, infl ammatory changes in the blood and blood lipids was monitored. It was found that a methionine diet (MD) leads, starting from 4 weeks of MD, to medium hyperhomocysteinemia, an increase in liver enzymes (AsAT – 1.73, AlAT – 1.5 times, p<0.05) and bilirubin (by 62.25%), which indicates the formed hepatopathy. Further (12 weeks of MD), the condition is aggravated by an abnormality of excretory liver function and the development of cholestasis (an increase in alkaline phosphatase by 1.65, bilirubin – by 3.31 times, p<0.05).

Poor vector competence of the human flea, Pulex irritans, to transmit Yersinia pestis

Background The human flea, Pulex irritans, is widespread globally and has a long association with humans, one of its principal hosts. Its role in plague transmission is still under discussion, although its high prevalence in plague-endemic regions and the presence of infected fleas of this species during plague outbreaks has led to proposals that it has been a significant vector in human-to-human transmission in some historical and present-day epidemiologic situations. However, based on a limited number of studies, P. irritans is considered to be a poor vector and receives very little attention from public health policymakers. In this study we examined the vector competence of P. irritans collected from foxes and owls in the western United States, using a standard protocol and artificial infection system. Methods Wild-caught fleas were maintained in the laboratory and infected by allowing them to feed on human or rat blood containing 2 × 108 to 1 × 109Y. pestis/ml. The fleas were then monitored periodically for infection rate and bacterial load, mortality, feeding rate, bacterial biofilm formation in the foregut (proventricular blockage), and ability to transmit Y. pestis after their single infectious blood meal. Results P. irritans were susceptible to infection, with more than 30% maintaining high bacterial loads for up to 20 days. Transmission during this time was infrequent and inefficient, however. Consistent with previous studies, a low level of early-phase transmission (3 days after the infectious blood meal) was detected in some trials. Transmission at later time points was also sporadic, and the incidence of proventricular blockage, required for this mode of transmission, was low in fleas infected using rat blood and never occurred in fleas infected using human blood. The highest level of blockage and transmission was seen in fleas infected using rat blood and allowed to feed intermittently rather than daily, indicating that host blood and feeding frequency influence vector competence. Conclusions Our results affirm the reputation of P. irritans as a feeble vector compared to rodent flea species examined similarly, and its vector competence may be lower when infected by feeding on bacteremic human blood. Graphic abstract

Development of Simultaneous Determination Method of a Pregnan Steroid with Gestagenic Activity – Gestobutanoil and Two its Metabolites in Rat Serum

Introduction. Gestobutanoil is a synthetic pregnane steroid with gestagenic activity. Gestobutanoil has two pharmacologically active metabolites (AMOL and megestrol acetate). This implies the need for a detailed study of the kinetics of metabolites. It is rational to combine the study of the pharmacokinetics of gestobutanoil and its metabolites (AMOL and megestrol acetate). The simultaneous determination of several analytes in the rats’ serum can be carried out using chromatography-mass-spectrometry.Aim. Development of an analytical method for the simultaneous determination of gestobutanoil and two its metabolites in a biomatrix (rat serum).Materials and methods. The following methods were used to determine gestobutanoyl and two its metabolites in a biological matrix: GC-MS, HPLCESI-MS, HPLC-ESI-MS with derivatization, HPLC-APCI-MS.Results and discussion. When working with GC-MS, the chromatographic peaks of gestobutanoyl, AMOL, and megestrol acetate were strongly blurred and superimposed on each other, which is apparently due to the thermolability of the substances. The GC-MS method was abandoned in favor of HPLC. Analytes were separated by HPLC gradient elution on a C18 column. ESI ionization did not give typical protonated ions of gestobutanoyl and AMOL, and the intense signals of their cationized ions and fragment ions, which were observed in the spectra of AMOL and gestobutanoyl, could not ensure the reproducibility of the spectra, since the conditions of their formation are not suitable for routine analysis. Derivatization of analytes to form oximes and substituted hydrazones did not give the expected reaction products for HPLC-ESI-MS. APCI made it possible to remove intense cationized ions from the spectra of gestobutanoyl and AMOL and to increase the reliability of the method. The HPLCAPCI-MS technique was reproduced on model rat blood serum.Conclusion. An HPLC-MS method was developed for the simultaneous determination of gestobutanoyl, megestrol acetate, and AMOL. The technique was tested on a model rat blood serum containing all three analytes.

THE CONTENT OF SULFUR-CONTAINING AMINO ACIDS AND RELATED COMPOUNDS IN THE BLOOD PLASMA OF RATS WITH DIFFERENT TYPES OF ALCOHOL INTOXICATION

Background. Change of the content of sulfur-containing amino acids and their metabolites is one of the pathochemical mechanisms of alcohol intoxication. Purpose of the study. To study the effect of chronic and intermittent alcohol intoxication on the content of sulfurcontaining amino acids and related compounds in the rat blood plasma. Material and methods. Thirty white outbred rats weighing 180-220 g. The content of free amino acids and biogenic amines was determined by HPLC. Results. A 14-day chronic alcohol intoxication was accompanied by a significant decrease in the level of methionine and an increase in the level of homocysteine in the blood plasma. The concentration of glutathione increased by 5%. In the intermittent alcohol intoxication IAI-4 group, the homocysteine content also increased, as did the level of homoserine and cystathionine in the IAI-1 group. Conclusions. Сhronic and intermittent alcohol intoxications cause similar violations of the level of sulfur-containing amino acids and their metabolites in the rat blood plasma.