Human plague in the southwestern United States, 1957-2004: spatial models of elevated risk of human exposure to Yersinia pestis

Plague is a rare but highly virulent flea-borne zoonotic disease caused by the Gram-negative bacterium Yersinia pestis Yersin. Identifying areas at high risk of human exposure to the etiological agent of plague could provide a useful tool for targeting limited public health resources and reduce the likelihood of misdiagnosis by raising awareness of the disease. We created logistic regression models to identify landscape features associated with areas where humans have acquired plague from 1957 to 2004 in the four-corners region of the United States (Arizona, Colorado, New Mexico, and Utah), and we extrapolated those models within a geographical information system to predict where plague cases are likely to occur within the southwestern United States disease focus. The probability of an area being classified as high-risk plague habitat increased with elevation up to approximately 2300 m and declined as elevation increased thereafter, and declined with distance from key habitat types (e.g., southern Rocky Mountain pi?on--juniper [Pinus edulis Engelm. and Juniperus spp.], Colorado plateau pi?on--juniper woodland, Rocky Mountain ponderosa pine (Pinus ponderosa P.& C. Lawson var. scopulorum), and southern Rocky Mountain juniper woodland and savanna). The overall accuracy of the model was >82%. Our most conservative model predicted that 14.4% of the four-corners region represented a high risk of peridomestic exposure to Y. pestis.     

Fowl plague virus adapted to human epithelial tumor cells and human myeloblasts in vitro

Summary A strain of avian influenza A virus, originally isolated from an epidemic among turkeys, was adapted to human cells by serial passages. Four passage levels of the virus were compared with respect to their growth potential in human cell monolayers and their plaque morphology in chick embryo fibroblasts and in HeLa cells. The original virus, never passed in human cells before, was already able to replicate in human cells. Serial passages in human epithelial cells increased this ability. Further serial passages in human myeloblasts resulted in the selection of an apparently stable mutant which grew well in human malignant epithelial cells and even better in diploid human fibroblasts.     

Evaluation of indoor plantings as allergen exposure sources

The role of indoor plantings as allergen sources was assessed by direct sampling of interior air. Homes with 10 or more plants in one room and three University of Michigan greenhouses were studied by means of a dc-powered rotorod and separate Andersen viable sampler collections incubated at 23° and 50° C. Sequential 30 and 60 sec Andersen samples were obtained during 15 min rotorod collections before and during watering of plants as well as during disturbance of foliage by a small fan. Relative humidity averaged 5I % in homes and 78% in greenhouses. Aspergillus fumigatus recoveries were rare. Thermophiles, primarily bacteria, were present at low-to-moderate levels in homes, did not increase with watering or fan in homes, and rose only slightly with disturbance at greenhouse sites. Cladosporium and Penicillium dominated Andersen collections. Watering and fan increased levels of these taxa as well as rotorod recoveries of Alternaria, Epicoccum, and Pithomyces slightly in homes and markedly at greenhouse sites. We conclude that modest numbers of undisturbed house plants contribute minimally to aeroallergen prevalence in homes. However, especially under greenhouse conditions, plantings can harbor abundant fungus growth that may become airborne, especially when agitated directly.     

Biomonitoring human exposure to environmental carcinogenic chemicals

A coordinated study was carried out on the development, evaluationand application of biomonitoring procedures for populationsexposed to environmental genotoxic pollutants. The proceduresused involved both direct measurement of DNA or protein damage(adducts) and assessment of secondary biological effects (mutationand cytogenetic damage). Adduct detection at the level of DNAor protein (haemoglobin) was carried out by ³²P-postlabelling,immunochemical, HPLC or mass spectrometric methods. Urinaryexcretion products resulting from DNA damage were also estimated(immunochemical assay, mass spectrometry). The measurement ofadducts was focused on those from genotoxicants that resultfrom petrochemical combustion or processing, e.g. low-molecular-weightalkylating agents, PAHs and compounds that cause oxidative DNAdamage. Cytogenetic analysis of lymphocytes was undertaken (micronuclei,chromosome aberrations and sister chromatid exchanges) and mutationfrequency was estimated at a number of loci including the hprtgene and genes involved in cancer development. Blood and urinesamples from individuals exposed to urban pollution were collected.Populations exposed through occupational or medical sourcesto larger amounts of some of the genotoxic compounds presentin the environmental samples were used as positive controlsfor the environmentally exposed population. Samples from ruralareas were used as negative controls. The project has led tonew, more sensitive and more selective approaches for detectingcarcinogen-induced damage to DNA and proteins, and subsequentbiological effects. These methods were validated with the occupationalexposures, which showed evidence of DNA and/or protein and/orchromosome damage in workers in a coke oven plant, garage workersexposed to diesel exhaust and workers exposed to ethylene oxidein a sterilization plant. Dose response and adduct repair werestudied for methylated adducts in patients treated with methylatingcytostatic drugs. The biomonitoring methods have also demonstratedtheir potential for detecting environmental exposure to genotoxiccompounds in nine groups of non-smoking individuals, ³²P-postlabellingof DNA adducts being shown to have the greatest sensitivity. ^*Synthesis report on E.U. STEP Contract No. EV5V-CT91-0013 ¹⁴To whom correspondence should be addressed      

Early Resistance to experimental plague in animals immunized with recombinant plague vaccine

The protective properties of recombinantSalmonella minnesota R595/pFS1 strain soon after immunization (1–3 days) are studied in a model of experimental mouse plague. Unlike the commercial EV strainYersinia pestis vaccine produced at the Saratov Anti-Plague Institute (Mikrob Research-Manufacturing Conglomerate), the experimental recombinant p preparation affords a high level of protection from the 1st day postvaccination, and surpasses the commercial preparation in such parameters as LD₅₀, mean survival time, and percentage of survivors. By the 21st day the protective indexes of both preparations are comparable. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny,Vol. 119, N ^o 1, pp. 54–57, January, 1995 Presented by A. A. Vorob'ev, Member of the Russian Academy of Medical Sciences     

Micronucleus monitoring to assess human occupational exposure to organochlorides

Health surveillance for hazardous situations due to chemical exposure, in particular those which are carcinogenic, requires sensitive monitoring tests. Although experimental studies have shown the genotoxic and carcinogenic effect of several organochlorides, the lack of epidemiologic studies prevents their classification as carcinogenic to human beings. In this context, genotoxicity tests of short duration in human cells gain importance. The relation between the clastogenic effects (chromosome breaks) and cancer induction is already known to the scientific literature. The micronucleus test has been proposed as a good indicator of clastogenesis. In the present study, we evaluated, by means of the micronucleus test, 41 workers of a chemical industry in the state of São Paulo, southeast region of Brazil, who had been exposed to a mixture of chlorinated solvents (carbon tetrachloride, perchloroethylene, and hexachlorobenzene) and 28 workers who had not been exposed. Peripheral lymphocytes stimulated by phytohemagglutinin and with cytokinesis blocked by cytochalasin B were used. The results showed that the exposed workers presented a statistically significant higher frequency of micronuclei than the group which had not been exposed. Environ. Mol. Mutagen. 29: 46–52, 1997 © 1997 Wiley-Liss, Inc.     

Lysis of human and animal fibrins by the plague microbe

Summary Bact.pestis is able to lysate purified fibrin not only of human blood, but also that of animals investigated by the author (pig, sheep, horse, bull, dog, guinea pig, and rabbit). Antifibrinolysins, i.e., fibrin-protective factors, contained in the blood sera of various animals, depress fibrinolysis provoked by B. pestis. The fibrinolytic factor of B. pestis is connected with the microbial cell and does not pass into the nutritive medium.(Presented by the active member AMN SSSR N.N. Zhukov-Verezhnikov) Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 50, No. 7, pp. 51–54, July, 1960     

Historic exposure to plague and present-day frequency of CCR5del32 in two isolated island communities of Dalmatia, Croatia

Aim

To assess the frequency of deletion of 32 base pairs in a CCR5 gene, shown to confer resistance to HIV infection, in two isolated island communities of Dalmatia, Croatia, with different histories of exposure to “plague” during the medieval period and beyond.

Methods

Random samples of 100 individuals from highly isolated communities of Lopar (island of Rab) and Komiža (island of Vis) were selected in 2002 and their DNA was extracted. An extremely high level of 3-generational endogamy was found in both communities (98% and 91%, respectively), indicating very limited gene flow, which was confirmed by available historic records. The two settlements also differed in their historic exposure to plague: between 1449 and 1456, Lopar was decimated by plague, while Komiža remained unaffected. Genotyping of the CCR5 polymorphism was performed using the polymerase chain reaction (PCR) method with primers flanking the region containing 32-bp deletion.

Results

The frequency of CCR5del32 in Lopar was 6.0% and in Komiža 1.5% (P = 0.037). A previous study in 303 random Croatian blood donors showed a frequency of CCR5 32bp deletion of 7.1%.

Conclusion

This study does not rule out the possible role of plague in positive selection at CCR5del32. However, analyses of further neighboring isolated island communities need to be made in order to provide more substantial support for this hypothesis.The chemokine receptor CCR5 was shown to be a co-receptor for the macrophage-tropic strains of HIV-1 (1,2). A mutant form of this gene with a 32bp deletion, in its homozygous form, was shown to confer resistance to infection by HIV (1,2). In European populations, this mutant allele is fairly common, with a clear north to south gradient of frequency, ranging from 16% in Mordvinia, Russian Federation, to 4% in Sardinia (3). Slavic populations of central Europe, with the estimated frequency of 10.9% for the Poles (4), 10.7% for the Czechs (5), 8.7% for the Slovenes (6), and 7.1% for the Croatians (7), are placed in the middle of the European gradient, which is expected according to their geographic location. An analysis of flanking microsatellites in multiple populations showed strong linkage disequilibrium between specific microsatellite alleles and the 32-bp deletion (8). This data inferred that most 32-bp deletions originated from a single mutation event, which probably took place in northeastern Europe (8).It was initially thought that the high frequency of the 32-bp deletion allele could not be explained simply by random genetic drift and was probably associated with some selection advantage conferred by either the heterozygous or homozygous mutant allele (8,9). Lucotte et al (10) undertook a comparative analysis of this variant in 40 populations from Europe, the Middle East, and North Africa, and confirmed the clear north-south divide. They concluded that the CCR5 32bp deletion was probably disseminated by the Vikings and that it had a protective effect against smallpox in the period between the 8th and 10th century. However, others hypothesized that the mutation was more recent in origin and under much stronger selection, and that the Yersinia pestis may have had strong selective pressure on European populations during medieval times and beyond, especially between 1347 and 1670 (3,11,12).A number of scientists have recently conducted research in order to provide further support for the “plague hypothesis” or to challenge it. The problem is that the term “plague” is ill defined in this context, as for a long period of human history it was associated with any epidemic that was causing high mortality, and the microbial causes could have been entirely different in each episode (2,9). The bubonic plague, caused by Yersinia Pestis, is only one of several possible examples (9). CCR5 32-bp deletion was identified in 2900-year-old skeletons from the Bronze Age burials in central Germany at the same frequency as in victims of the 14th century pandemic in Lubeck in northern Germany (13,14). Experiments showed no difference in susceptibility to infection and death between CCR5 deficient and normal mice after infection with Yersinia pestis (15), but there may still be a difference in the pathogenesis of Yersinia pestis between mice and men. Furthermore, in vitro experiments of macrophage uptake of Yersinia pestis showed some 30-fold reduction in homozygous mutant mice (16). Some epidemiological models based on highly complex sets of assumptions supported the role of plague (9), the others supported the role of smallpox (17), while some found no evidence of positive selection at all (18). All these studies indicate that the role of the 32-bp deletion in relationship to Yersinia pestis infection is still inconclusive.In this study, we aimed to contribute further evidence to this debate. Due to massive migrations that occurred in Europe since the medieval period, there are very few European populations, located within the same gradient of CCR5del32 frequency, that remained isolated after very differing histories of exposure to plague. However, in Dalmatia, Croatia, some of the island isolates may be unique in exhibiting precisely this set of conditions that may allow testing the hypothesis of plague as a positive selective force on CCR5del32.     

First human exposure to FSH-CTP in hypogonadotrophic hypogonadal males

BACKGROUND: This is the first report of human exposure to the novel compound follicle stimulating hormone (FSH)-C-terminal peptide (CTP) 'FSH-CTP' (Org 36286), a long-acting recombinant FSH like substance, consisting of the alpha-subunit of human FSH and a hybrid beta-subunit. The latter is composed of the beta-subunit of human FSH and the C-terminus part (CTP) of the beta-subunit of human chorionic gonadotrophin (HCG). METHODS: In this phase I, non-blind, multi-centre study, 13 hypogonadotrophic hypogonadal male subjects were enrolled to test the safety of FSH-CTP in terms of antibody formation in humans. Furthermore, the pharmacokinetic profile of this new compound was determined. Subjects were injected four times with 15 microg FSH-CTP with an interval of approximately 4 weeks between each injection. RESULTS: No drug related (serious) adverse events occurred. No antibodies against FSH-CTP or chinese hamster ovary (CHO)-cell derived proteins were detected and measurement of local tolerance demonstrated that s.c. administration of FSH-CTP is well tolerated and no increase in intensity of injection-site responses was observed after repeated exposure to FSH-CTP. After the first and third injection, FSH-CTP serum concentrations were determined. Overall mean (+/- SD) C(max) was 0.426 (+/- 0.116) ng/ml, mean t(1/2) and AUC(0-infinity) were 94.7 (+/- 26.2) h and 81.5 (+/- 18.8) ng.h/ml respectively. Compared with recFSH (Puregon), the half life of FSH-CTP was increased 2-3 times. Following the first and third injection a clear rise in serum inhibin-B concentrations were observed. CONCLUSIONS: The use of FSH-CTP is safe and does not lead to detectable formation of antibodies. Furthermore, the pharmacokinetic and dynamic profile of FSH-CTP may lead to the development of new, more convenient regimens for the treatment of male and female infertility.     

Adaptive responses of human skeletal muscle to vibration exposure.

The aim of this study was to investigate the effects of whole-body vibrations (WBV) on the mechanical behaviour of human skeletal muscle. For this purpose, six female volleyball players at national level were recruited voluntarily. They were tested with maximal dynamic leg press exercise on a slide machine with extra loads of 70, 90, 110 and 130 kg. After the testing, one leg was randomly assigned to the control treatment (C) and the other to the experimental treatment (E) consisting of vibrations. The subjects were then retested at the end of the treatment using the leg press. Results showed remarkable and statistically significant enhancement of the experimental treatment in average velocity (AV), average force (AF) and average power (AP) (P < 0.05-0.005). Consequently, the velocity-force and power-force relationship shifted to the right after the treatment. In conclusion, it was affirmed that the enhancement could be caused by neural factors, as athletes were well accustomed to the leg press exercise and the learning effect was minimized.     

Nicotine exposure alters in vivo human responses to endotoxin

The alpha 7 nicotinic receptor is reportedly a key element in the cholinergic anti-inflammatory pathway. Because a prototypical ligand for this receptor is nicotine, we studied the in vivo human response to bacterial endotoxin or lipopolysaccharide (LPS) in the context of nicotine or placebo pretreatment. Twelve adult male normal subjects were studied prospectively. Six received overnight transcutaneous nicotine administration by application of a standard patch (7 mg). Six hours later, all subjects were given an intravenous dose of endotoxin (2 ng/kg) and were evaluated for an additional 24 h for circulating levels of inflammatory biomarkers, vital signs and symptoms. The nicotine subjects had elevated blood levels of the nicotine metabolite, continine, prior to and throughout the 24-h post-endotoxin exposure phase. Subjects receiving nicotine exhibited a significantly lower temperature response as well as attenuated cardiovascular responses for 2.5-6 h after LPS exposure. In addition, increased circulating interkeukin (IL)-10 and cortisol levels were also noted in nicotine subjects. These data indicate an alteration in LPS-induced systemic inflammatory responses in normal subjects exposed to transcutaneous nicotine. In this model of abbreviated inflammation, nicotine exposure attenuates the febrile response to LPS and promotes a more prominent anti-inflammatory phenotype.     

Degranulation of human neutrophils after exposure to bacterial phospholipase C

Because an endogenous phospholipase C (PLC) participates in neutrophil activation and because many bacterial pathogens produce PLCs, these studies examined the effect of PLC fromBacillus cereus on the release of the granule enzyme lysozyme from human neutrophils.Bacillus cereus PLC caused dose-dependent lysozyme release, and combined stimulation of neutrophils with PLC and fluoride led to increased secretion. Stimulation of neutrophil degranulation is a potential contributing factor for tissue damage in infections caused by PLC-producing organisms.