Number Of Live Bacteria Research Articles

Direct and phagocyte-mediated lipid peroxidation of lung surfactant by group B streptococci.

In newborn infants, group B streptococci (GBS) often cause pneumonia, with polymorphonuclear leukocytes (PMN) migrating into the lungs. Because surfactant therapy may be needed in such patients, we evaluated the interaction between GBS or GBS-stimulated PMN and a surfactant preparation (Curosurf) in vitro. The superoxide production of GBS strains or GBS-activated PMN was measured, using the nitroblue tetrazolium (NBT) test and the subsequent lipid peroxidation (LPO) as the content of malondialdehyde (MDA) and 4-hydroxyalkenals (4-HNE). The growth of GBS in surfactant was determined and related to the LPO. Finally, the effect of LPO on surfactant activity, caused by GBS-stimulated PMN, was assessed by measuring dynamic surface tension in a pulsating bubble surfactometer. Curosurf diminished the NBT reduction by both live GBS and GBS-stimulated PMN. Surfactant was peroxidized by reactive oxygen species (ROS) from both GBS and GBS-stimulated PMN in a time-dependent manner. Vitamin E significantly reduced the peroxidation level of surfactant in both cases. Surfactant peroxidation was associated with a reduction in the number of live bacteria. The biophysical activity of Curosurf was impaired by GBS-stimulated PMN, as reflected by increased minimum surface tension during cyclic compression. These findings indicate that Curosurf undergoes LPO by ROS produced by GBS and/or PMN. We speculate that exogenous surfactant preparations should be supplemented with vitamin E or another antioxidant, when given to infants with GBS pneumonia.

Neutrophils from Mycobacterium avium-infected mice produce TNF-alpha, IL-12, and IL-1 beta and have a putative role in early host response.

Recent evidence supports a role for neutrophils in the host defense against Mycobacterium avium. To determine whether the depletion of neutrophils has an effect on the outcome of infection in mice as determined by the number of bacteria in liver and spleen, we administered RB6-8C5 anti-neutrophil antibody intraperitoneally both early and late in the infection. Mice were then observed for 14 days and harvested. The number of viable bacteria in liver and spleen was determined. While administration of RB6-8C5 antibody early in infection resulted in a significant increase in the number of bacteria in organs when compared with mice receiving immunoglobulin control, administration of RB6-8C5 antibody late in infection (week 3) did not have an impact on the bacterial load in tissue. Infection of CD18 knockout mice (with impaired neutrophil function), however, did not show a significant enhancement of M. avium growth when compared with that of wild-type control mice. Neutrophils were found to produce increased amounts of TNF-alpha and IL-12 and IL-1 than control uninfected mice during the initial phase of infection, but not after 2 weeks following infection (although IL-1 beta levels continue elevated). The results suggest that neutrophils may have a role in the early (innate) immune response against M. avium but it is only evident after acute depletion of neutrophils and not in mice with chronic neutrophil impairment.

The roles of intrahepatic Valpha14(+) NK1.1(+) T cells for liver injury induced by Salmonella infection in mice.

To investigate the roles of intrahepatic T cells in liver injury after Salmonella infection, we examined serum alanine transaminase (ALT), histopathology, and bacterial numbers in liver after infection with Salmonella choleraesuis strain 31N-1 in mice genetically lacking TCRalpha beta+, CD4(+), CD8(+), or NK1.1(+)T cells with C57BL/6 background. In control (+/+) mice, serum ALT reached a peak level by day 7 after an intraperitoneal inoculation of 2 x 10(6) CFU Salmonella choleraesuis 31N-1. In TCR-beta-/- mice, liver injury, as assessed by serum ALT level and histological examination, was significantly suppressed on day 7 after Salmonella infection but the numbers of bacteria in liver did not differ from those in normal mice, suggesting that alpha beta T cells are responsible for liver injury induced by Salmonella infection. To further determine which subsets in alpha beta T cells are important for the liver injury, we compared serum ALT level in mice genetically lacking CD4, CD8, beta2-microglobulin (beta2m, IAbeta, or Jalpha281 after Salmonella infection. In CD4(-/-) mice, serum ALT was significantly lower in comparison with control mice, but there was no difference in serum ALT levels in CD8(-/-) and IAbeta-/- mice from that in control mice. Notably, serum ALT levels and pathological lesions in liver were significantly decreased in beta2m-/- or Jalpha281(-/-) mice, which lacked in NK1.1(+) T cells bearing TCR Valpha14-Jalpha281 specific for beta2m-associated CD1d, following Salmonella infection. Taken together, it is suggested that alpha beta T cells bearing NK1.1 and CD4 may be main effector cells for liver injury after Salmonella infection.

USES OF INTERNA ORGANS FOR BACTERIAL EVALUATION OF POULTRY CARCASSES

Eighteen birds were taken from a flock of line C and A,. They were reared on three types of litters, wood shaving, typha and blady grass until 7 weeks of age. After slaughtering and defeathering the carcasses were kept frozen. samples of breast and thigh muscles,liver and heart tissues were taken from the carcasses as well as samples of litters which were taken before and after rearing. The results showed that wood shaving contained less bacteria (P < 0.05) than the other two, before and after rearing. Litters from pens containing line C had less bacteria counts than that of line A. Samples from carcasses of line C revealed significantly (P <0.05) less bacterial counts than that of line A. Number of bacteria in liver and heart were significantly (P < 0.05) higher than those of breast and thigh muscles in both lines. Therefore, it seems to be advantageous to consider the sampling in internal organs (liver or heart) for determination of carcass" bacterial condition.

Tumour necrosis factor alpha antibody protects against lethal meningococcaemia.

Tumour necrosis factor alpha (TNF-alpha) has been shown to be the principal mediator of Gram-negative bacterial endotoxin-induced shock. Nevertheless, evidence suggests that TNF-alpha plays a beneficial role in controlling bacterial infections when multiplication of the microorganism is required to kill the host. Using an infant rat model of Neisseria meningitidis infection, we found that blood TNF-alpha concentration reaches a peak three hours after intraperitoneal injection of 3 x 10(6) bacteria. Thereafter, the level of TNF-alpha decreased and was undetectable six to eight hours after infection. A correlation was observed between the magnitude of initial TNF-alpha response and a fatal outcome. Pretreatment of the animals with polyclonal anti-TNF antiserum significantly reduced mortality relative to animals pretreated with control serum. However, pretreatment of animals with anti-TNF antibody did not alter the bacterial invasion of the cerebrospinal fluid. Injection of heat-killed bacteria did not cause death and induced lower TNF-alpha levels than the same number of live bacteria. This excludes the possibility that the role of TNF-alpha is to mediate a shock induced by the endotoxin component of the bacterial inoculum. These results indicate that TNF-alpha has a deleterious effect in this model of bacteraemia. Identification of the critical factors that determine the action of TNF-alpha during lethal bacteraemia will lead to a better understanding of these diseases and the development of appropriate therapeutic intervention.

Induction of Metamorphosis of Larvae of the Green Sea Urchin, Strongylocentrotus droebachiensis, by Coralline Red Algae.

The coralline red algae, Lithothamnion glaciale, Phymatolithon laevigatum, P. rugulosum, and Corallina officinalis, induced >85% of laboratory-reared larvae of Strongylocentrotus droebachiensis to metamorphose. Larvae must contact live L. glaciale or its spores for metamorphosis to occur; the inducer is not sensed in the water column. However, aqueous extracts of L. glaciale can induce metamorphosis, suggesting that the inducing factor is chemical. Neither ashed nor boiled L. glaciale induces metamorphosis, indicating that the factor is heat-labile and that thigmotaxis, per se, is not important in the response. The amino-acid, γ-aminobutyric acid (GABA), which induces settlement of other marine invertebrate larvae, also induces significant rates of metamorphosis of S. droebachiensis at concentrations ≥ 10-4 M. A reduction (with antibiotics) in the number of live bacteria on the surface of L. glaciale does not affect the rate of metamorphosis of larvae.

Vaccination route, infectivity and thioglycollate broth administration: effects on live vaccine efficacy of auxotrophic derivatives of Salmonella choleraesuis

An aromatic-dependent, therefore non-virulent, derivative of a mouse-virulent strain of Salmonella choleraesuis previously shown not to be effective as a live vaccine when given intraperitoneally (i.p.) to lty s mice, was administered to BALB/c mice. Two doses given i.p. or by feeding did not protect against i.p. or oral challenge with 50 to 5000 LD 60 of the virulent ancestor strain. By contrast two doses given intravenously (i.v.) gave almost complete protection against i.p. or oral challenge with 500 LD 50 and some protection against larger doses. The number of live bacteria (cfu) in the liver and spleen 24 h after administration of the live vaccine was less than 1% of the number inoculated i.p., but c. 25% of the number injected i.v. The number of cfu in the gut 24 h after oral vaccine administration was only c. 10 −5 of the number fed. Administration of thioglycollate broth i.p. 5 days before i.p. vaccination increased recovery of live vaccine cfu in the liver and spleen and its protective efficacy. In each case the live vaccine did not multiply extensively in vivo. We have previously shown that a purine- and a thymine-requiring derivative of S. choleraesuis were each considerably attenuated but unlike the aro derivative were effective as i.p. live vaccines in mice. Doses of these strains ( c. 10 4 cfu) found protective were administered i.p. to BALB/c mice. Each strain multiplied extensively in the liver and spleen to c. 10 7 cfu by day 6. All these results are in agreement with a correlation of protective efficacy of a live vaccine with the persistence of a large number of the vaccine bacteria in the liver and spleen for several days.

Increased susceptibility to Escherichia coli infection in mice pretreated with Corynebacterium parvum.

The contribution of activated macrophages to protection against Escherichia coli was studied in mice treated intravenously with Corynebacterium parvum 7 days before infection. C. parvum-treated mice showed increased phagocytic activity and enhanced resistance to Listeria infection. In contrast, these mice showed increased susceptibility to a subsequent challenge with E. coli that correlated closely with a reduction in the LD50 of lipopolysaccharide (LPS) in these mice. The peritoneal macrophages obtained from C. parvum-treated mice had a strong ability to phagocytize and kill E. coli in in vitro experiments. A rapid decline in the number of bacteria in the liver of C. parvum-treated mice was observed in the early period of infection. However, the number of bacteria in liver and spleen increased progressively to a lethal dose from 6 hr after infection. At this time, a significant increase in beta-glucuronidase, a lysosomal acid hydrolase, was found in the serum of these mice. In vitro experiments revealed that the peritoneal macrophages from C. parvum-treated mice were highly susceptible to the cytotoxic effect of LPS after 6 hr of incubation with LPS. It is suggested that the hypersensitivity of activated macrophages to the cytotoxic effect of endotoxin derived from E. coli may be partly responsible for the increased susceptibility of C. parvum-treated mice to E. coli infection.

INFECTION OF CLETHRIONOMYS G. GLAREOLUS SCHREB. (RED MICE) WITH MYCOBACTERIUM TUBERCULOSIS INJECTED INTRAVENOUSLY

Groups of red mice were injected intravenously with doses varying from 11 viable units to about 108 viable units of a virulent strain of M. tuberculosis grown in Dubos Tween medium and dispersed by means of ultrasonics. The course of the infection was determined by quantitative culture from the organs of animals killed at various times after the injection and by the survival times of animals that died spontaneously. Quantitative culture showed that the tubercle bacilli multiplied strongly in the organs during the first 2–3 weeks after the injection. Multiplication then ceased completely in liver, spleen and lungs; in the lymph glands the bacilli continued to multiply but at a very slow rate. After the period of initial multiplication, the number of bacteria in liver and spleen decreased gradually during the whole experimental period (1 year), although it varied considerably from animal to animal after the second month. In the lungs, the number remained almost constant in the animals injected with large doses, but in those given doses ≥ 104 viable units, it became reduced from the second month, and in some cases the bacteria disappeared completely. Total elimination of the bacteria was also observed in the liver and spleen of a few animals but never in the lymph glands. The mean survival times of animals injected with the four largest doses were prolonged from 81 to 310 days the smaller the dose. In the animals injected with doses ≥ 104 viable units, the mean survival times, which were independent of dosage, were not significantly different and not significantly less than those of a group of non‐infected animals. The macroscopical tuberculous lesions were small in all groups. Enlargement of the spleen, slightly enlarged lymph glands and possibly tubercles in the lungs were the most frequent findings. The number of bacteria in the organs was large in all animals injected with the large doses, but only in about half of those given small doses.

A method for studying the integral functionals of stochastic processes with applications: I. Markov chain case

The subject of this paper is the study of the distribution of integrals of the type where {X(t); t ≧ 0} is some appropriately defined continuous-time parameter stochastic process, and f is a suitable non-negative function of its arguments. This subject has also sometimes been labelled as “the occupation time or the sojourn time problem” in literature. These integrals arise in several domains of applications such as in the theory of inventories and storage (see Moran [14], Naddor [15]), in the study of the cost of the flow-stopping incident involved in the automobile traffic jams (see Gaver [8], Daley [3], Daley and Jacobs [4]). The author encountered such integrals while studying certain stochastic models suitable for the study of response time distributions arising in various live situations. In fact in [19], it was shown that such a distribution is equivalent to the study of an integral of the type (1). Again, in the study of response of host to injection of virulent bacteria, Y(t) with f(X(t), t) = bX(t), with b > 0, could be regarded as a measure of the total amount of toxins produced by the bacteria during (0, t), assuming a constant toxin-excretion rate per bacterium. Here X(t) denotes the number of live bacteria at time t, the growth of which is governed by a birth and death process (see Puri [16], [17] and [18]).

STUDIES ON EXPERIMENTAL TYPHOID : THE DISTRIBUTION OF MICROORGANISMS IN THE COURSE OF INFECTION WITH S.ENTERITIDS AND THEIR PATHOIOGICAI STUDIES OF INFECTED MICE ORGANS

In the course of infection of mice with S.enteritidis, the distribution of microorganisms in the mice organs were studied. When the mice were infected with 10-7 and 10-5mg of virulent strain 116-54, the number of infected bacteria in the blood and liver was determined by stamp method.The results were shown in Fig. 2 and 3. 24 or 48 hours after the infection the number of bacteria in blood and liver decreased. But 3 days after the infection bacteria increased.The number of bacteria was also determined by plate counting method. As shown in Fig.4 and 5, the number of bacteria in the liver and blood decreased and reached minimum 6 hours after the infection. From this time the number of bacteria increased.The number of bacteria in 1 g of liver was always 100 times that in 1 ml of blood in the course of the infection.The histopathological studies of mice organs were described. The results were shown in figures.

The petoscope: A new principle in photoelectric applications

Stable and long-term nitric oxide (NO) releasing polymeric materials have many potential biomedical applications. Herein, we report the real-time observation of the crystallization process of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), within a thermoplastic silicone-polycarbonate-urethane biomedical polymer, CarboSil 20 80A. It is demonstrated that the NO release rate from this composite material is directly correlated with the surface area that the CarboSil polymer film is exposed to when in contact with aqueous solution. The decomposition of SNAP in solution (e.g. PBS, ethanol, THF, etc.) is an apparent first-order reaction proportional to the SNAP concentration. Further, catheters fabricated with this novel NO releasing composite material are shown to exhibit significant effects on preventing biofilm formation on catheter surface by Pseudomonas aeruginosa and Proteus mirabilis grown in CDC bioreactor over 14 days, with a 2 and 3 log-unit reduction in the number of live bacteria on their surfaces, respectively. Therefore, the SNAP-CarboSil composite is a promising new material for antimicrobial catheters, as well as other biomedical devices.