A simple method of transmission risk assessment in enzootic foci of Lyme borreliosis

The proposed method consists in examining individual host-seeking vector ticks of the Ixodes ricinus complex by microscopy for borreliae and evaluating the proportion of ticks with more than 100 borreliae. The investigations were carried out in a deciduous oak forest habitat in South Moravia, Czech Republic, over four years (1991–1994). In May (i.e., at the peak of seasonal activity of I. ricinus), about 150 nymphal and 200 adult ticks were examined each year. It was found that annual incidence of human Lyme borreliosis in the region correlated better with the proportion of heavily infected ticks than with the overall infection rate of the ticks.     

Francisella tularensis caused cervical lymphadenopathy in little children after a tick bite: Two case reports and a short literature review

Although Francisella (F.) tularensis is a well-described and understood zoonotic pathogen, its importance in Central Europe is relatively minor and, as such, tularaemia may be missed in the differential diagnosis. The annual incidence of tularaemia in the Czech Republic is relatively stable with up to 100 reported cases per year, except in the epidemic years 1998 and 1999 with 225 and 222 reported cases, respectively. It is, however, higher in comparison with the neighbouring countries. The common route of transmission in Central Europe is handling infected animals. Tularaemia is not commonly recognized as a tick-borne disease. Here we report two rare cases of a tick bite-associated ulceroglandular form of tularaemia in 2.5-year-old and 6.5-year-old children presenting with cervical lymphadenopathy. The unusual and interesting features of those cases are the young age and relatively uncommon route of transmission suggesting possible changes in the epidemiology of tularaemia in the Czech Republic. Therefore, the infection with F. tularensis should be considered in the differential diagnosis after a tick bite even in infants.     

trans,trans-Muconic acid,a reliable biological indicator for the detection of individual benzene exposure down to the ppm level

Summary trans,trans-Muconic acid (2,4-hexadienedioic acid) (t,t-MA) is a minor benzene metabolite which can be used as a biological indicator for benzene exposure. The purpose of the study was to evaluate the limits of use of t,t-MA for detection and quantification of occupational exposures to benzene, particularly on an individual scale, phenol being used as the metabolite of reference. A simple and sensitve method previously described by the authors was carried out to analyse t,t-MA in 105 end-of-shift urinary samples from 23 workers exposed to benzene used as an extraction solvent for concretes recovery in the perfume industry. Good correlations were found between atmospheric benzene and both metabolites (uncorrected or corrected for creatinine) or between the metabolites themselves, with correlation coefficients from 0.81 to 0.91 (P < 0.0001). Correlation-coefficients were not improved after correction for creatinine. The overall individual benzene exposure range, median, and arithmetic mean were respectively 0.1–75, 4.5, and 9.0 ppm with corresponding t,t-MA excretion of 0.1–47.9, 5.2 and 8.9 mg/l (uncorrected) and phenol excretion of 1.4–298, 30.9, and 42.2 mg/l (uncorrected). In the control group (145 determinations for t,t-MA and 76 for phenol from 79 individuals) the range, median, and arithmetic mean were respectively < 0.04–0.66, 0.08, and 0.13 mg/l (uncorrected t,t-MA) and 1.5–42.0, 9.85 and 11.3 mg/l (uncorrected phenol). t,t-MA was far more specific than phenol and could be easily and practically used to estimate with a given probability the upper or lower corresponding benzene concentrations down to around the ppm level. Biological exposure indices for benzene exposure to 10, 5, or 1 ppm could be set at 10, 5, or 1 mg t,t-MA/l (uncorrected).     

Back Extensor Muscle Endurance Test Scores in Coal Miners in Australia

Study Design: A cross-sectional analytic study was conducted. Objectives: To collect normative data on back extensor endurance holding times and evaluate the discriminative validity of the Biering–Sorensen test in a group of coal miners in Australia. Summary of Background Data: Low back pain is a common complaint among those working in the Australian coal mining industry. One test that may be predictive of first-time episodes of low back pain is the Biering–Sorensen test of back extensor endurance strength. While this test has been evaluated in overseas sedentary populations, normative data and the discriminative ability of the test have not been evaluated with coal miners. Methods: Eighty-eight coal miners completed a questionnaire for known risk factors for low back pain, performed the Biering–Sorensen test, and undertook a test of aerobic fitness. Data analysis was performed to describe the groups and to determine whether any significant difference existed between those with a past history of low back pain and those without. Results: Significantly lower than expected holding times were found in this group of coal miners (mean 113 s). This result was significantly lower than demonstrated in previous studies (mean 138 s, t ₈₇ = 6.32, p < 0.001). When holding times for those with a past history of low back pain were compared with times for those with no history of low back pain, the difference was not statistically significant (t ₈₆ = 1.56, p = 0.12), nor was there a significant difference in fitness between those with a past history of low back pain and those without (t ₈₆ = 0.47, p = 0.64). Discussion/Conclusions: Coal miners in Australia have lower than normal Biering– Sorensen holding times. This lower back holding time does not differ between coal miners with a past history of low back pain and those without.     

Ubiquitous pollution by n-hexane and reference biological levels in the general population

Summary n-Hexane levels were determined by gas chromatography and mass spectrometry in environmental air and in the alveolar air, blood and urine of a group of subjects aged on average of 38 years who had not been occupationally exposed to this hydrocarbon. n-Hexane was found in all environmental air samples examined (n=49), with the mean concentration being 104 ng/l (limit values, 1–279 ng/l). It was also found in all 49 samples of alveolar air, with the mean concentration being 50 ng/l (variation limit, 1–304ng/l). In 64 samples of urine, n-hexane was found in only 50 samples, with the mean concentration being 1,417 ng/l (limit values, 34–8,820 ng/l). In 77 of the 90 blood samples taken, a mean concentration of 608 ng/l was detected (variation limit, 15–7,684ng/l). Particularly the haematic and urinary concentration showed significant differences among the nine groups of individuals classified according to their work activity. The lowest levels were found in the blood and urine of farmers: 270 and 298 ng/l, respectively. The highest values were found for chemical workers (1,377 and 411 ng/1), respectively printers (585 and 2,691 ng/l respectively), and traffic wardens (740 and 8,820 ng/l, respectively). In all, 95% of the determinations of n-hexane yielded values of < 255 ng/l in environmental samples, < 105 ng/l in alveolar air, < 1,475 ng/l in blood and < 5,875 ng/l in urine. A comparison of these data revealed a significant correlation between environmental levels and alveolar (r/s = 0.769; P<0.00001), haematic (r/s = 0.624; P<0.0002), and urinary (r/s = 0.597; P<0.0005) values for n-hexane.     

Synthesis and in vitro leishmanicidal activity of 2-(1-methyl-5-nitro-1H-imidazol-2-yl)-5-substituted-1,3,4-thiadiazole derivatives

A series of 2-(1-methyl-5-nitroimidazol-2-yl)-5-(1-piperazinyl, 1-piperidinyl and 1-morpholinyl)-1,3,4–thiadiazoles (3a–g) were synthesized and evaluated for in vitro leishmanicidal activity against Leishmania major promastigotes. The leishmanicidal data revealed that compounds 3a–g had strong and much better leishmanicidal activity than the reference drug pentostam. Compound 3c (piperazine analog) was the most active compound (IC₅₀ = 0.19 μM).     

Determination of free amino acids in beers: A comparison of Czech and foreign brands

The content of 16 free amino acids in 35 beers commercially available in Czech Republic was measured using high-performance liquid chromatography method with pre-column derivatization by AccQ·Tag agent and separation in reverse phase column followed by fluorescent detection. Content of proline, which was the amino acid most commonly found, varied in range from 40 to 250 mg/L. Czech beers were characterized by a significantly higher amino acid content in comparison to imported global brands (450.41±27.66 vs. 257.53±46.46 mg/L). Among individual amino acids, nine amino acids were significantly (p<0.01) more concentrated in the Czech beer brands than in the studied foreign brands, and those amino acids were from three distinctive taste groups: bitter tasting amino acid (isoleucine, leucine, lysine, phenylalanine and histidine), bitter sweet amino acids (valine and proline) and salty-umami amino acids (glutamic acid and aspartic acid).     

Synthesis and evaluation of A-seco type triterpenoids for anti-HIV-1protease activity

2,3-Seco-dioic acids derived from four different triterpene skeletons were prepared and evaluated for their anti-HIV-1 protease activity. Two A-seco derivatives showed potent inhibitory activity against HIV-1 protease (3c and 3e, IC₅₀ 5.7 and 3.9 μM, respectively), while four other derivatives showed moderate to weak inhibition (3a, 3b, 3d and 3f, IC₅₀ 15.7–88.1 μM). The combination of a 2,3-seco-2,3-dioic acid functional group in ring A and a free acid group at C-28 or C-30 significantly enhanced HIV-1 protease inhibitory activity (3a, 3c–3e, IC₅₀ 3.9–17.6 μM). On the other hand, all A-seco derivatives were found to be very weak inhibitors of HCV, renin and trypsin proteases (IC₅₀ > 80 μM). These findings indicate that A-seco triterpenes with a carboxyl group at C-28 or C-30 are novel and highly selective HIV-1 protease inhibitors.     

Effect of folate–binding protein on intestinal transport of folic acid and 5–methyltetrahydrofolate across Caco–2 cells

Summary Background Milk products are a potential matrix for fortification with synthetic folic acid or natural 5-methyltetrahydrofolate (5–CH₃–H₄folate) to enhance the daily folate intake. In milk, folate occurs bound to folatebinding proteins (FBP). Our previous studies with an in vitro gastrointestinal model showed that 70% of the initial FBP content of the milk product was retained in the duodenal lumen. While folic acid remained bound to FBP after gastric passage, 5–CH₃–H₄folate was mainly present as free folate in the duodenal lumen. Aim of the study To investigate the effect of FBP on the absorption of folic acid and 5–CH₃–H₄folate from the intestinal lumen. Methods The transport of [³H]–folic acid and [¹⁴C]–5–CH₃–H₄folate across enterocytes was studied in the presence or absence of bovine FBP using monolayers of Caco–2 cells grown on semi–permeable inserts in a two–compartment model. The apparent permeability coefficients (P_app) of folic acid and 5–CH₃–H₄folate were determined and compared with the permeability of reference compounds for low (mannitol) and high (caffeine) permeability. Results The transport from the apical to the basolateral side of the Caco–2 cells was higher (P < 0.05) for folic acid (P_app = 1.7*10^–6 cm/s) than for 5– CH₃–H₄folate (P_app = 1.4*10^–6 cm/s) after 2 h incubation to 1 µM folic acid or 5–CH₃–H₄folate test solutions (pH 7). The permeability of folic acid and 5–CH₃–H₄folate across Caco–2 monolayers appeared to be higher (P < 0.05) than that of mannitol (P_app = 0.5*10^–6 cm/s) but lower (P < 0.05) than that of caffeine (P_app = 34*10^–6 cm/s). The addition of FBP to the medium led to a lower (P < 0.05) intestinal transport and cellular accumulation of folic acid and 5–CH₃–H₄folate. Conclusions Compared to the reference compounds, folic acid and 5–CH₃–H₄folate showed a moderate permeability across Caco–2 cells, which indicates that folate absorption from the intestinal lumen is not likely to be complete. The intestinal transport of folic acid and 5–CH₃–H₄folate was found to be dependent on the extent of binding to FBP at the luminal side of the cells.     

Spatiotemporal Dynamics of Sporadic Shiga Toxin–Producing Escherichia coli Enteritis,Ireland, 2013–2017

The Republic of Ireland regularly reports the highest annual crude incidence rates of Shiga toxin–producing Escherichia coli (STEC) enteritis in the European Union, ≈10 times the average. We investigated spatiotemporal patterns of STEC enteritis in Ireland using multiple statistical tools. Overall, we georeferenced 2,755 cases of infection during January 2013–December 2017; we found >1 case notified in 2,340 (12.6%) of 18,641 Census Small Areas. We encountered the highest case numbers in children 0–5 years of age (n = 1,101, 39.6%) and associated with serogroups O26 (n = 800, 29%) and O157 (n = 638, 23.2%). Overall, we identified 17 space-time clusters, ranging from 2 (2014) to 5 (2017) clusters of sporadic infection per year; we detected recurrent clustering in 3 distinct geographic regions in the west and mid-west, all of which are primarily rural. Our findings can be used to enable targeted epidemiologic intervention and surveillance.     

Mercury Biomagnification in a Tropical Black Water,Rio Negro,Brazil

The population living along the riverbanks of the Amazon basin depends heavily on fish for nutritional support. Mono-methyl-mercury (MMHg) concentrates in fish, which can contaminate humans, the risk depending not only on fish MMHg concentration but also on the amount of fish consumed. We sampled nine locations of the Rio Negro basin, differing in water pH, Hg concentrations, and dissolved organic carbon (DOC), and determined total Hg from 951 fish samples of species representative of the food web: herbivorous, detritivorous, omnivorous, and piscivorous. Mercury concentrations varied widely in all species but showed a trend that depended on fish feeding strategies. The highest mean concentration was found in the piscivorous species (688.90 ng/g^–1), followed by omnivorous (190.30 ng/g^–1), detritivorous (136.04 ng/g^–1), and herbivorous (70.39 ng/g^–1). Fish Hg concentrations exceeding current safe limits (500 ng/g^–1) for human consumption were found mainly in the piscivorous species (60%). Significant positive correlation between fish weight and Hg concentration was seen for the piscivorous Serrasalmus spp. (n = 326; r = 0.3977; p < 0.0001), Cichla spp. (n = 125; r = 0.4600; p < 0.0001), and Pimelodus spp. (n = 12; r = 0.8299; p = 0.0008), known locally as Piranha, Tucunaré, and Mandi, respectively. However, a negative correlation was seen for nonpiscivorous Potamorhina latior (n = 30; r –0.3763; p = 0.0404) and Leporinus spp. (n = 44; r = –3987; p = 0.0073), known as Branquinha (detritivorous) and Aracu (omnivorous). Fish-Hg concentrations in the acidic waters (pH range, 4.09–6.31) of the Rio Negro habitat, with its wide gradient of Hg concentrations (3.4–11.9 g/L^–1) and DOC (1.85–15.3 mg/L^–1)—but no history of gold mining activity—are comparable to other Amazonian rivers. Opportunity fish catches in the Rio Negro habitat show high muscle-Hg derived from natural sources, but no systematic association with site-dependent geochemistry.     

Parameters of immunological competence in subjects with high consumption of fish contaminated with persistent organochlorine compounds

Summary Consumption of fatty fish species, like salmon and herring, from the Baltic Sea is an important source of human exposure to persistent organochlorine compounds, e.g. polychlorinated dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). Many of these compounds show immunotoxic and hepatotoxic effects in animals. We have now studied immunological competence, including lymphocyte subsets, in 23 males with a high consumption of fish from the Baltic Sea and in a control group of 20 males with virtually no fish consumption. The high consumers had lower proportions and numbers of natural killer (NK) cells, identified by the CD 56 marker, in peripheral blood than the non-consumers. Weekly intake of fatty fish correlated negatively with proportions of NK cells (r _s = –0.32, P = 0.04). There were also, in a sub-sample of 11 subjects, significant negative correlations between numbers of NK cells and blood levels of a toxic non-ortho-PCB congener (IUPAC 126; r _s = –0.68, P = 0.02) and a mono-ortho congener (IUPAC 118; r _s = –.76, P = 0.01). A similar correlation, in 12 subjects, was seen for p,p-DDT (r _s = –0.76, P = 0.01). The corresponding negative correlation, in 13 subjects, with blood levels of PCDD/Fs was not significant (r _s = –0.57, P = 0.07). No significant association was seen between organic mercury in erythrocytes and NK cells. Fish consumption was not associated with levels of any other lymphocyte subset. Neither were there any correlations with plasma immunoglobulins or liver enzyme activities. Our study indicates that accumulation of persistent organochlorine compounds in high consumers of fatty fish may adversely affect NK cell levels.     

Didanosine ester prodrugs: Synthesis, albumin binding properties and pharmacokinetic studies in rats

Three half-ester derivatives 10–12 of 5′-O-2′,3′-dideoxydidanosine (DDI, 1) have been synthesized. The compounds exhibited excellent correlation between partition coefficients Log P and relative in vitro bovine serum albumin binding. Using high-performance liquid chromatography–mass spectrometry (LC–MS), DDI (1) was quantitatively determined in rat plasma after intravenous injection of the azelaic acid monoester derivative (11) of DDI. The pharmacokinetic data obtained for DDI were consistent with literature. The pharmacokinetic profile of 11 showed no significant difference in AUC_0–360 or curve shape compared to the parent drug DDI (1). The data indicate that the prodrug was converted to DDI within minutes after administration. High relative protein binding in vitro holds a promise for validity of the concept using more stable linker bonds.     

Trajectories of Food Choice Motives and Weight Status of Malaysian Youths during the COVID-19 Pandemic

Stay-at-home orders have abruptly altered food purchasing behaviour, dietary habits, and food choice motives. Therefore, this study aims to investigate the trajectory of food choice motives and their associations with the weight status of Malaysian youths in the time of COVID-19. Socio-demographic information and anthropometric measurements were self-reported by the respondents, while the food choice motives were assessed using a validated 38-item food choice questionnaire (FCQ). Of the 1013 Malaysian youths, 48.6% gained weight due to the confinement, with an average weight gain of 3.90 ± 2.92 kg. On the other hand, 47.0% to 73.0% of the youths changed their food choice motives in the time of COVID-19. Of the 10 motives, convenience (48.5%) had the largest percentage increase, followed by weight control (47.0%) and health (45.3%). Moreover, the mean scores of health (t = −3.324, p = 0.001), convenience (t = −5.869, p < 0.001), weight control (t = −7.532, p < 0.001), natural content (t = −5.957, p < 0.001), ethical concern (t = −4.419, p < 0.001) and price (t = −3.737, p < 0.001) were significantly higher during the pandemic compared to pre-pandemic. Findings from the multinomial regression model revealed that youths highly concerned for weight control were more likely to be in the weight loss category (Adjusted odds ratio (AOR) = 1.633, Confidence Interval (CI) = 1.230–2.168, p = 0.001). Conversely, those who gained weight due to the pandemic confinement highly valued natural content in foods (AOR = 0.653, CI = 0.481–0.886, p = 0.006) when making their food choices in this unprecedented pandemic. In conclusion, Malaysian youths made healthier food choices to mitigate the risk of COVID-19 infection.     

Acid precipitation effect on anion transport of the Atkins Reservoir,Massachusetts

The anion concentration of the water in the precipitation reservoir and its watershed of Atkins Reservoir, Massachusetts was studied. In the precipitation study, the NO₃ ^– and SO₄ ^2– levels increased with a pH drop andvice versa, but the Cl^– was interfered with by regional marine air masses. The average pH of precipitation and the reservoir were 3.85 (SD=±0.89) and 6.08 (SD= ±0.18), respectively. The average alkalinity of the reservoir was very low; 0.88 mg/L CaCO₃ (SD= ±0.68). The precipitation and reservoir concentrations of anions were: F^– (0.5 and 0.2 ppm), Cl^– (2 and 4 ppm), and SO₄ ^2– (7 and 7.8 ppm), respectively. The NO₃ ^– level in the precipitation (4 to 6 ppm) was at least an order higher than the reservoir (0.2 to 0.4 ppm) and this was due to selective NO₃ ^– uptake by terrestrial plants. About 50% of the samples collected at the bottom of the reservoir were high in NO₃ ^– where organic decomposition would be expected. The response of the SO₄ ^2– and and Cl^– levels to pH drop in the reservoir inlet study followed a SO₄ ^2– retention-Cl^– release mechanism. The F^– concentration in the precipitation and reservoir was not dependent on pH changes. The lack of F^– in soil samples adjacent to the reservoir indicated that the F^– in the reservoir came primarily from precipitation.     

Epidemiology of childhood bacterial meningitis in Poland. Incidence of bacterial meningitis with special reference to Haemophilus influenzae type b among children 0-59 months old in the former Kielce and Bydgoszcz districts in Poland in 1998-1999

Population based surveillance was undertaken to assess the incidence of meningitis caused by Haemophilus influenzae type b in children 0–59 months old in Kielce and Bydgoszcz districts in Poland in 1998 and 1999. The cases were prospectively identified in pediatric and neuroinfection wards of local hospitals where all cases of children with suspected meningitis are referred in both districts. The mean annual incidence of meningitis caused by Haemophilus influenzae type b in children 0–59 months old in Kielce district during the study period was estimated at 3.1 per 100,000 per year (10.3% of cases of bacterial meningitis with confirmed etiology). In Bydgoszcz district, the annual incidence was 9.7 per 100,000 (50% of confirmed cases). These estimations are lower than reported in most Western European countries before the immunization against Hib was introduced. Small numbers of Hib vaccinations reported from both districts do not seem likely to have influenced the data significantly.     

Annual decline of ventilatory capacity and change in acute respiratory response in hemp exposure over a 10-year period

Summary A follow-up study of the effect of exposure to hemp dust on respiratory function over a 10-year period (1963–1973) was conducted in 24 female non-smoking hemp workers. The prevalence of byssinosis in 1973 (70.8%) was found to be significantly higher than 10 years earlier in 1963 (33%) (P<0.01). The prevalence of all other chronic respiratory symptoms was also considerably increased. In the control group the prevalence of all chronic respiratory symptoms was practically the same during both surveys.In hemp workers, there was a significant acute fall over the work shift in FEV_1.0 (1-second forced expiratory volume) and FVC (forced vital capacity), both in 1963 and 1973 (P<0.01), except in the group of workers who did not have byssinosis either in 1963 or in 1973. The lowest mean annual decline of FEV_1.0 within the 10-year period was found in the group without byssinosis in both 1963 and in 1973 (27 ml), followed by the group without byssinosis in 1963 but with byssinosis in 1973 (38 ml). The largest annual decline was observed in the subjects with byssinosis during both surveys (55 ml). The mean annual FEV_1.0 decline in the control group was 22 ml.     

Stability and change in structural social relations as predictor of mortality among elderly women and men

In a follow-up study of 70–95years old women and men (n = 911) we studied the association between change and stability in three structural aspects of social relations (contact frequency, contact diversity, cohabitation status) from 1986–1990 and mortality after the next four years in 1994. Women aged 70–74years who developed low contact frequency or developed small contact diversity showed significantly higher mortality, adjusted OR_freq: 3.78 (1.08–13.20), adjusted OR_div: 3.79 (1.24–11.58). Women aged 70–74years with continuously low contact frequency showed an increased mortality compared to women constantly experiencing high contact frequency, adjusted OR: 2.75 (1.04–7.26). A tendency in the same direction for sustained small contact diversity was found, adjusted OR: 1.98 (0.70–5.61). Among women aged 75+ years no impact of frequency and diversity was demonstrated, whereas continuously living alone was a significant predictor of mortality, when compared to women continuously living with somebody, adjusted OR: 2.57 (1.29–5.09). In men, we found a significantly increased mortality among those who developed high contact frequency and developed large contact diversity OR_freq: 3.91 (1.02–14.94) and OR_div: 6.04 (1.30–28.03). In summary, we found rather larger age differences in the strength of the association between change in structural social relations and mortality. Furthermore, the associations seemed stronger among women than men, which may however mainly be explained by the small number of men in our cohort.