First demonstration of 30 eVee ionization energy resolution with Ricochet germanium cryogenic bolometers

The future Ricochet experiment aims to search for new physics in the electroweak sector by measuring the Coherent Elastic Neutrino-Nucleus Scattering process from reactor antineutrinos with high precision down to the sub-100 eV nuclear recoil energy range. While the Ricochet collaboration is currently building the experimental setup at the reactor site, it is also finalizing the cryogenic detector arrays that will be integrated into the cryostat at the Institut Laue Langevin in early 2024. In this paper, we report on recent progress from the Ge cryogenic detector technology, called the CryoCube. More specifically, we present the first demonstration of a 30 eVee (electron equivalent) baseline ionization resolution (RMS) achieved with an early design of the detector assembly and its dedicated High Electron Mobility Transistor (HEMT) based front-end electronics with a total input capacitance of about 40 pF. This represents an order of magnitude improvement over the best ionization resolutions obtained on similar phonon-and-ionization germanium cryogenic detectors from the EDELWEISS and SuperCDMS dark matter experiments, and a factor of three improvement compared to the first fully-cryogenic HEMT-based preamplifier coupled to a CDMS-II germanium detector with a total input capacitance of 250 pF. Additionally, we discuss the implications of these results in the context of the future Ricochet experiment and its expected background mitigation performance.

"I believe this team will change how society views youth in disasters": the EnRiCH Youth Research Team: a youth-led community-based disaster risk reduction program in Ottawa, Canada

SETTING

The Sendai Framework for Disaster Risk Reduction promotes an "all-of-society" approach to disaster risk reduction (DRR). Since 2013, the EnRiCH Research Lab has implemented a community-based, participatory program to promote youth development and engagement in DRR in Ottawa-Gatineau. The EnRiCH Youth Research Team used an existing community education program called the Enrichment Mini-Course Program as a framework to engage youth in DRR. We aim to share the implementation process and lessons learned from this innovative "all-of-society" approach to DRR.

INTERVENTION

The EnRiCH Youth Research Team provides high school and university students with a platform to be heard on disaster and climate change issues. Youth are given opportunities to design and lead knowledge dissemination projects intended to educate members of the community about disaster prevention and preparedness. Students have opportunities to connect with academics, governmental and non-governmental organizations, and public health practitioners to share their ideas on youth participation in DRR in Canada.

OUTCOMES

To date, this public health intervention has produced DRR training modules that can be used as curriculum support by teachers, a children's book on earthquake preparedness, an educational video about youth participation in DRR, and several conference presentations. Members of the team have become well versed in disaster preparedness strategies.

IMPLICATIONS

This program has demonstrated that youth can contribute to DRR through knowledge mobilization, and support public education about disaster preparedness. Offering this opportunity at a grassroots level can support participation by youth by allowing flexibility in design and adaptation to individual environmental and social contexts.

Toxoplasma gondii-specific IgG avidity testing in pregnant women

BACKGROUND

The parasite Toxoplasma gondii can cause congenital toxoplasmosis following primary infection in a pregnant woman. It is therefore important to distinguish between recent and past infection when both T. gondii-specific IgM and IgG are detected in a single serum in pregnant women. Toxoplasma gondii-specific IgG avidity testing is an essential tool to help to date the infection. However, interpretation of its results can be complex.

OBJECTIVES

To review the benefits and limitations of T. gondii-specific avidity testing in pregnant women, to help practitioners to interpret the results and adapt the patient management.

SOURCES

PubMed search with the keywords avidity, toxoplasmosis and Toxoplasma gondii for articles published from 1989 to 2019.

CONTENT

Toxoplasma gondii-specific IgG avidity testing remains a key tool for dating a T. gondii infection in immunocompetent pregnant women. Several commercial assays are available and display comparable performances. A high avidity result obtained on a first-trimester serum sample is indicative of a past infection, which occurred before pregnancy. To date, a low avidity result must still be considered as non-informative to date the infection, although some authors suggest that very low avidity results are highly suggestive of recent infections depending on the assay. Interpretation of low or grey zone avidity results on a first-trimester serum sample, as well as any avidity result on a second-trimester or third-trimester serum sample, is more complex and requires recourse to expert toxoplasmosis laboratories.

IMPLICATIONS

Although used for about 30 years, T. gondii-specific avidity testing has scarcely evolved. The same difficulties in interpretation have persisted over the years. Some authors have proposed additional thresholds to exclude an infection of <9 months, or in contrast to confirm a recent infection. Such thresholds would be of great interest to adapt management of pregnant women and avoid unnecessary treatment; however, they need confirmation and further studies.

The Promotion of 'Grab Bags' as a Disaster Risk Reduction Strategy

INTRODUCTION

An all-of-society approach to disaster risk reduction emphasizes inclusion and engagement in preparedness activities. A common recommendation is to promote household preparedness through the preparation of a 'grab bag' or 'disaster kit', that can be used to shelter-in-place or evacuate. However, there are knowledge gaps related to how this strategy is being used around the world as a disaster risk reduction strategy, and what evidence there is to support recommendations.

METHODS

In this paper, we present an exploratory study undertaken to provide insight into how grab bag guidelines are used to promote preparedness in Canada, China, England, Japan, and Scotland, and supplemented by a literature review to understand existing evidence for this strategy.

RESULTS

There are gaps in the literature regarding evidence on grab bag effectiveness. We also found variations in how grab bag guidelines are promoted across the five case studies.

DISCUSSION

 While there are clearly common items recommended for household grab bags (such as water and first aid kits), there are gaps in the literature regarding: 1) the evidence base to inform guidelines; 2) uptake of guidelines; and 3) to what extent grab bags reduce demands on essential services and improve disaster resilience.

Local Anesthetic-Induced Methemoglobinemia During Pregnancy: A Case Report and Evaluation of Treatment Options

BACKGROUND

Methemoglobinemia is a well-recognized adverse drug reaction related to the use of certain local anesthetic agents. The mainstay of treatment for methemoglobinemia is i.v. methylene blue, along with provision of supplemental oxygen; however, methylene blue is listed as a category X teratogen. This poses an issue should methemoglobinemia develop during pregnancy.

CASE REPORT

A 35-year-old, 20-week and 5-day gravid female was transferred from an outpatient oral surgeon's office for hypoxia. She was undergoing extraction of 28 teeth and was administered an unknown, but "large" quantity of prilocaine during the procedure. Given this exposure, the concern was for methemoglobinemia. This was confirmed with co-oximetry, which showed 34.7% methemoglobin. The initial treatment plan was methylene blue; however, this drug is a category X teratogen. Thus, an interdisciplinary team deliberated and decided on treatment with high-dose ascorbic acid and transfusion of a single unit of packed red blood cells. The patient was managed with noninvasive ventilation strategies and a total of 8 g ascorbic acid. She was discharged on hospital day 3 with no obstetric issues noted. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Intravenous ascorbic acid appears to be a potential alternative to methylene blue in this patient population. The data surrounding teratogenicity of methylene blue are mostly related to intra-amniotic or intra-uterine administration. In life-threatening cases of methemoglobinemia during pregnancy, the benefits of i.v. methylene blue may outweigh the risks.

Abstract 4011: Effective in situ immunization via local radiation therapy (RT) and tumor-specific immunocytokine (IC): Suppression from distant tumor is blocked by RT or Treg-depleting CTLA-4 antibody

PURPOSE: Use “off the shelf” reagents to eradicate an established tumor and induce a tumor specific T cell response that destroys distant tumor.

PROCEDURES: We have identified a cooperative interaction between local tumor RT, intratumoral (IT) injection of IC hu14.18-IL2 (anti-GD2 hu14.18 mAb linked to IL2), and checkpoint blockade with anti-CTLA4 mAb. C57Bl/6 mice were implanted with 2×106 B78 (GD2+) melanoma in one flank (1-tumor model). In the 2-tumor model, mice received 2×106 B78 3 weeks (w) later in the opposite flank. After 5w the primary (1st) tumor was ∼200mm3, and ∼500mm3 after 7w. The 2nd tumor was ∼ 50mm3 at 5w. At 5w or 7w, mice received single fraction RT (12Gy) to the 1st tumor and 6 days later received 5-daily 50μg injections of IC (IT-IC). When used, anti-CTLA4 was given i.p. on days 3, 6 and 9 after RT.

NEW UNPUBLISHED DATA: For mice bearing a single 200mm3 tumor, RT+ IT-IC results in complete response (CR) in 71% of mice and a tumor-specific memory T cell response. Mice with a single 500mm3 tumor showed slowing of tumor growth, but only 27% CR after radiation + IT-IC. Adding anti-CTLA-4 to RT + IT-IC improved tumor response (73% CR) and survival compared to doublet combinations of these 3 modalities. In contrast, in the 2-tumor model, providing RT + IT-IC to the 1st ∼200mm3 tumor, but not to the distant ∼50mm3 tumor, did not enhance 1st tumor shrinkage compared to RT alone and had no effect on the 2nd 50mm3 tumor. The presence of the 2nd B78 tumor resulted in systemic immune suppression that prevented the local RT and IT-IC from eliminating the 1st tumor. This was tumor specific, as local RT + IT-IC to the 1st ∼200mm3 B78 tumor was still effective in treating the 1st tumor if the 2nd (∼50 mm3 tumor) was the syngeneic but unrelated Panc02 tumor. Delivering RT to both the 1st + 2nd B78 tumors eliminated the inhibitory effect of the 2nd tumor, enabling IT-IC to the 200mm3 tumor to cause eradication of that tumor in 64% of mice. Preliminary PCR analyses of FoxP3 in the 1st tumor showed Tregs are depleted by 1st tumor RT only in mice with 1 tumor and not in mice with 2 tumors. In this 2 tumor model we combined RT + IT-IC of the 1st tumor with anti-CTLA-4. The IgG2b anti-CTLA-4 (which doesn't substantially deplete Tregs) had minimal effect on 1st tumor response to RT + IT-IC. In contrast the IgG2a anti-CTLA-4 (that depletes Tregs) rendered 60% of mice disease-free (durable CR of both the treated 200mm3 and the untreated 50mm3 tumors). Preliminary data, using DEREG mice that enable diphtheria toxin to deplete Tregs, show Treg depletion in the 2 tumor model also enables eradication of both 1st and 2nd tumors in 60% of mice after RT + IT-IC to only the 1st tumor.

CONCLUSIONS: Local RT+ IT-IC can result in long-term tumor eradication of macroscopic tumors via adaptive immunity to the “in situ vaccine”, provided that Treg-associated immune suppression from distant tumor is eliminated by RT or Treg-depletion.

Citation Format: Zachary S. Morris, Emily Guy, David Francis, Monica M. Gressett, Eric A. Armstrong, Shyhmin Huang, Lauryn R. Werner, Stephen D. Gillies, Alan Korman, Jacquelyn A. Hank, Alexander L. Rakhmilevich, Paul M. Harari, Paul M. Sondel. Effective in situ immunization via local radiation therapy (RT) and tumor-specific immunocytokine (IC): Suppression from distant tumor is blocked by RT or Treg-depleting CTLA-4 antibody. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4011.

Symptomatic toxoplasma infection due to congenital and postnatally acquired infection

AIMS

To determine the incidence and severity of symptomatic toxoplasma infection presenting during childhood due to congenital or postnatally acquired infection.

METHODS

Between 2002 and 2004, newly diagnosed children (<16 years) with signs or symptoms of congenital or ocular toxoplasmosis were reported by clinicians to the British Paediatric and Ophthalmic Surveillance Units or by toxoplasma referral laboratories. Confirmed cases were estimated to have a greater than 50% probability of congenital and/or ocular toxoplasmosis, based on clinical and serological findings.

RESULTS

Thirty eight children had confirmed toxoplasma infection. Twenty two (58%) were classified with congenital infection (cumulative incidence for England and Wales 1.62[corrected]/100,000 live births; 95% CI 0.85[corrected] to 2.83[corrected]), of whom 2 (9%) were stillborn, 7 (32%) live births had intracranial abnormalities and/or developmental delay (5 of whom had retinochoroiditis), and 10 (45%) had retinochoroiditis with no other abnormalities reported. A further 16 (42%) children were classified as infected after birth; all had retinochoroiditis.

CONCLUSIONS

The low burden of symptomatic congenital toxoplasmosis combined with the lack of evidence of an effective treatment support current policy not to offer prenatal or neonatal screening for toxoplasma infection. Primary prevention strategies need to address acquisition of infection in childhood which accounts for half the ocular disease due to toxoplasma infection in children in the UK and Ireland.

The impact of overexpression and deficiency of fatty acid translocase (FAT)/CD36

Fatty acid translocase (FAT)/CD36 has been associated with diverse normal and pathologic processes. These include scavenger receptor functions (uptake of apoptotic cells and modified lipid), lipid metabolism and fatty acid transport, adhesion, angiogenesis, modulation of inflammation, transforming growth factor-beta activation, atherosclerosis, diabetes and cardiomyopathy. Although CD36 was identified more than 25 years ago, it is only with the advent of recent genetic technology that in vivo evidence has emerged for its physiologic and pathologic relevance. As these in vivo studies are expanded, we will gain further insight into the mechanism(s) by which CD36 transmits a cellular signal, and this will allow the design of specific therapeutics that impact on a particular function of CD36.

Polymerase chain reaction for diagnosis of cerebral toxoplasmosis in cerebrospinal fluid in HIV-positive patients

It is important but sometimes difficult to establish a diagnosis of toxoplasma encephalitis (TE) in an HIV-positive immunodeficient patient. The most promising non-invasive method is polymerase chain reaction (PCR) for Toxoplasma gondii in cerebrospinal fluid (CSF). In a retrospective study PCR was used to analyse CSF for the presence of T. gondii DNA in 5 HIV-infected patients with a clinical suspicion of TE (group 1), 8 patients with other HIV-associated symptoms (group 2) and 7 other patients with neurological disorders (group 3). PCR was positive in 2/4 patients with a final diagnosis of TE and negative in all remaining patients in all 3 groups. The 2 patients with positive PCR had a fulminant course and experienced treatment failure. The albumin index was elevated in 4/5 patients in group 1, of whom 3/4 had a final diagnosis of TE, with suspected TE in 1. This small study confirms earlier data indicating that the PCR test has a low sensitivity but a high specificity.

Strategy for diagnosis of congenital toxoplasmosis: evaluation of methods comparing mothers and newborns and standard methods for postnatal detection of immunoglobulin G, M, and A antibodies

In a study involving 14 laboratories supported by the European Community Biomed 2 program, we evaluated immunologic methods for the postnatal diagnosis of congenital toxoplasmosis (CT). Among babies born to mothers who seroconverted to positivity for toxoplasmosis during pregnancy, we analyzed 55 babies with CT on the basis of persistent anti-Toxoplasma immunoglobulin G (IgG) at 1 year of life and 50 control babies without anti-Toxoplasma IgG at 1 year of life in the absence of curative treatment with pyrimethamine-sulfonamides. We tested in-house methods such as the enzyme-linked immunofiltration assay (ELIFA) or Immunoblotting (IB) for the detection of IgG or IgM; these methods allowed comparison of the immunologic profiles of the mothers and the infants. We compared ELIFA and IB with a commercial enzyme immunoassay (EIA) or in-house immunosorbent agglutination assay (ISAGA) for the detection of IgM or IgA. The performances of combinations of methods were also assessed. A cumulative sensitivity of 98% during a 1-year follow-up was obtained with the ELIFA plus ISAGA combination. Only one case of CT was missed by the ELIFA plus ISAGA combination, whereas three cases were missed by the IB plus ISAGA combination, even though 48% of patients with CT were treated with pyrimethamine-sulfonamides, which are known to inhibit antibody neosynthesis. A similar performance was obtained with either ELIFA or IB in combination with EIA. The difference in performance between ELIFA plus ISAGA and IB plus ISAGA was not statistically significant (P = 0.31), and we conclude that both combinations of tests can be used for the diagnosis of CT in newborns.

Multicenter evaluation of strategies for serodiagnosis of primary infection with Toxoplasma gondii

The diagnostic performance of single-serum assays for toxoplasma-specific immunoglobulin (Ig)M. IgA. IgG, and IgE antibodies and of different combinations of such antibody assays in 20 European reference centers was assessed. A panel of 276 sera, of which 73 came from patients who seroconverted within 3 months (acute infection), 49 from patients who had seroconverted 3-12 months earlier (convalescence), and 154 from subjects who had two IgG-positive samples obtained 12 months apart (past infection), was tested with 20 toxoplasma-antibody assays and 195 combinations. In general, every assay with high diagnostic sensitivity showed low diagnostic specificity, i.e. no assay performed alone could reliably distinguish acute from past infection. Furthermore, no single assay (or combination) could separate convalescence from the other stages of toxoplasma infection. However, excellent diagnostic performances were reached by sequential use of highly sensitive IgM assays and methods examining IgG avidity or stage specificity. IgA or IgM assays were less suitable for confirmation of toxoplasma-IgM positivity. This study documents the strength of test combinations in assessing the stage of toxoplasma infection.

A European multicenter study of immunoblotting in serodiagnosis of lyme borreliosis

A European multicenter study of immunoblotting for the serodiagnosis of Lyme borreliosis showed considerable variation in results obtained from tests with a panel of 227 serum samples. Six laboratories used different immunoblot methods, and a wide range of bands was detected in all the assays. Multivariable logistic regression analysis of data from individual laboratories was used to determine the most discriminatory bands for reliable detection of antibodies to Borrelia burgdorferi sensu lato. These bands were used to construct individual interpretation rules for the immunoblots used in the six laboratories. Further analysis identified a subset of eight bands, which were important in all the laboratories, although with variations in significance. Possible European rules, all closely related, were formulated from these bands, although there was no single rule that gave high levels of sensitivity and specificity for all the laboratories. This is a reflection of the wide range of methodologies used, especially the use of different species and strains of B. burgdorferi sensu lato. The panel of European rules provides a framework for immunoblot interpretation which may be adapted in relation to the characteristics of Lyme borreliosis in local areas.

Respiratory tract viral infections in inner-city asthmatic adults

BACKGROUND

Respiratory tract viral infections (RTVIs) have been identified frequently in association with asthma exacerbations in children, but few studies have shown similar rates of viral infections in adults with asthma. Further studies using newer diagnostic techniques to evaluate the frequency of RTVIs in adults with acute exacerbations of asthma need to be performed.

METHODS

Twenty-nine asthmatic adults were recruited from the pulmonary clinic of an urban county hospital and were followed up in a longitudinal cohort study for signs and symptoms of asthma and RTVI. One hundred twenty-two asthmatic adults presenting to the emergency department (ED) of the same hospital with acute symptoms of asthma underwent evaluation for RTVI in a cross-sectional prevalence study. In both studies, respiratory secretions and paired serum samples were collected from subjects with acute wheezing episodes and evaluated using virus culture, serologic testing, and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

In the longitudinal cohort study, 138 respiratory illnesses, of which 87 were asthma exacerbations, were evaluated; 41% of all illnesses and 44% of asthma exacerbations were associated with an RTVI. In the ED study, 148 asthma exacerbations were evaluated; 55% were associated with an RTVI. An RTVI was identified in 21 (50%) of 42 of the subjects hospitalized in the ED study. Picornaviruses (rhinoviruses), coronaviruses, and influenza viruses were the most commonly identified causes of RTVI. Forty-six (60%) of the 77 picornavirus infections and 22 (71%) of the 31 coronavirus infections were identified only using RT-PCR.

CONCLUSIONS

Asthmatic exacerbations in adults are frequently associated with an RTVI. Identification of such infections often requires newer diagnostic methods, such as virus-specific RT-PCR. The high frequency of RTVIs identified in association with asthmatic exacerbations in adults from the inner city suggests that strategies for the prevention of RTVI should be targeted toward this population.

Detection of the agent of human granulocytic ehrlichiosis (HGE) in UK ticks using polymerase chain reaction

Nymphal Ixodes ricinus ticks collected from woodland areas in South Wales, UK, were tested using the polymerase chain reaction for the presence both of the causative agent of human granulocytic ehrlichiosis (HGE) and Borrelia burgdorferi. Twenty-two of 60 (37%) ticks were found positive in the PCR for B. burgdorferi and 4/60 (7%) for the HGE agent. One tick was found positive both for B. burgdorferi and HGE agent. Our findings imply the presence of the HGE agent in UK ticks and the finding of a tick apparently containing both pathogens underlines the potential for concurrent infection with HGE agent and B. burgdorferi to occur after a single tick-bite. Based on our observations, we conclude that there may be a need to consider a range of pathogens both in laboratory investigation and clinical management of suspected tick-borne disease in the UK, particularly where there is a clinical presentation atypical of Lyme borreliosis alone.

A second European collaborative study on polymerase chain reaction for Toxoplasma gondii, involving 15 teams

In order to investigate the accuracy and practicability of the polymerase chain reaction (PCR) in the antenatal diagnosis of congenital toxoplasmosis, a collaborative study involving 15 European laboratories was performed under the auspices of the Biomed 2 Programme of the European Community. Each team received 12 aliquots (four negative, eight positive) of 'artificial samples' made of amniotic fluid spiked with tachyzoites of the RH strain of Toxoplasma gondii. Each team performed its own PCR protocol (all were different). Nine of the 15 laboratories were able to detect a single parasite, but two of the 15 found all samples negative. Four of the 15 laboratories found one or more control samples to be falsely positive. This study highlights the lack of homogeneity between PCR protocols and performance and underlines the need for an external quality assurance scheme which could provide 'reference' samples that could be used by any laboratory wanting to establish and maintain an accurate diagnostic test based on PCR.

European Union Concerted Action on Risk Assessment in Lyme Borreliosis: clinical case definitions for Lyme borreliosis

The EU Concerted Action on Risk Assessment in Lyme Borreliosis (EUCALB) has consulted other clinicians and scientists in Europe to produce case definitions of the principal manifestations of European Lyme borreliosis. These case definitions will not only be helpful in supporting its own research interests, but are also intended to assist other clinicians in appropriate management and to support further studies aimed at determining the full clinical spectrum of the disease. The case definitions were achieved after a series of meetings organised by EUCALB with other expert clinicians and scientists from twelve European countries. The definitions and the diagnostic criteria presented thus represent the consensus reached at these meetings. The proposed case definitions consider skin, nervous system, cardiac and musculoskeletal presentations and the role of laboratory investigation in supporting diagnosis.

The spatial distribution of Borrelia burgdorferi-infected Ixodes ricinus in the Connemara region of County Galway, Ireland

Studies were carried out in the Connemara area of County Galway in the west of Ireland in order to determine the abundance and distribution of the tick, Ixodes ricinus and the prevalence of its infection with Borrelia burgdorferi. The tick was very abundant locally, in particular when associated with cattle, sheep and enclosed red deer. Large numbers of ticks not only occurred on the pastures, but also on adjacent roadside verges. No infections with B. burgdorferi could be demonstrated when nymphal ticks were sampled from central areas of the pastures, suggesting that livestock and red deer are probably not significant reservoirs of the spirochaete. Small numbers of infected nymphal and adult ticks were associated with hedges, dry stone walls, the margins of woodland adjoining infested pastures and in woodland from which livestock were excluded. Woodmice (Apodemus sylvaticus) were most numerous in such habitats and the majority were infected with B. burgdorferi.

Acquisition of Borrelia burgdorferi by Ixodes ricinus ticks fed on the European hedgehog, Erinaceus europaeus L

A hedgehog, Erinaceus europaeus, was found to be heavily infested with larval and nymphal Ixodes ricinus in a forest park in Co. Galway, Ireland. A large proportion of the ticks that engorged and detached were infected with the spirochaete, Borrelia burgdorferi, the causative agent of human Lyme borreliosis. The identity of these spirochaetes was confirmed by immunofluorescent assay with B. burgdorferi-specific monoclonal antibody and by polymerase chain reaction test and they were transmitted from the hedgehog to laboratory-reared ticks and from the ticks obtained from the hedgehog to gerbils (Meriones unguiculatus). The high infection rate of the larvae that fed on the hedgehog in comparison with unfed larvae from the same habitat was interpreted as strong evidence that this host species is reservoir competent. Since hedgehogs can evidently feed adult ticks as well as many immature stages, they may well have an important role in the ecology of Lyme borreliosis in some habitats.

Vascular clearance of Borrelia burgdorferi in rats

Radiolabeled Borrelia burgdorferi, the etiologic agent of Lyme disease, injected intravenously into rats are cleared from the vasculature within 1 h of injection. One low passage isolate showed trafficking between the circulation and possibly the vessel walls for the first 2 h after injection. All strains used were resistant to the effects of normal and heat-inactivated rat serum. During the first 2 h after injection, B. burgdorferi can be visualized in, and recovered from, the platelet-rich plasma. B. burgdorferi can adhere to both human and rat platelets in in vitro assays, but an in vivo association with these cells was not apparent. Similarly, none of the strains of B. burgdorferi used induced platelet aggregation. Removal from the circulation into the organs was measured in perfused rats by polymerase chain reaction and autoradiography and in non-perfused rats by organ cultures. These organisms invade organs (heart, kidneys, bladder, liver, spleen, brain) within 1-6 h after injection. Invasion of organs occurred in an apparent random manner; a large amount of radiolabel but no live organisms was excreted in the urine during the first 24 h, suggesting degradation of the inoculum.

Profound reduction in morphine clearance and liver blood flow in shock

In six patients with septic shock apparent liver blood flow was significantly reduced compared with two patients restudied on recovery from shock and a group of four matched unshocked patients undergoing intensive care (287 +/- 23 ml/min vs 870 +/- 164 ml/min; mean +/- SEM). In the shocked patients the elimination half-life of morphine was significantly prolonged (13.2 +/- 3.5 h vs 5.9 +/- 1.4 h; mean +/- SEM) and the systemic clearance of morphine reduced by 53%, in comparison with the non-shocked patients. In both groups, morphine elimination was markedly delayed compared with previously reported observations in normal subjects and surgical patients. Care should be exercised with the use of drugs with a high hepatic extraction ratio in shocked patients.

Factors affecting the response to inhibition of drug metabolism by cimetidine--dose response and sensitivity of elderly and induced subjects

The effect of cimetidine on oxidative drug metabolism was characterised using antipyrine clearance in a group of healthy volunteers. In six subjects cimetidine produced a dose dependent reduction of antipyrine clearance: 400 mg/day (16.8 +/- 2.2%, mean +/- s.e. mean), 800 mg/day (26.3 +/- 1.5%) and 1600 mg/day (33.5 +/- 2.4%). The effect of cimetidine (800 mg/day) was of similar magnitude (approximately 25%) in two groups of six young (21-26 years) and six elderly (65-78 years) subjects. The effect of pretreatment begun just 1 h before administration of antipyrine was similar to that of 24 h pretreatment and that reported for chronic cimetidine pretreatment. The percentage reduction in antipyrine clearance produced by cimetidine 800 mg/day was greater (44 +/- 5 vs 24 +/- 3%; P less than 0.05) in six subjects who had been pretreated with the hepatic enzyme inducer rifampicin (600 mg/day for 21 days) than in the control uninduced state. Although cimetidine was capable of rapidly reversing the effect of rifampicin on antipyrine clearance, following withdrawal of both rifampicin and cimetidine there was still evidence of enzyme induction. These results suggest that the effect of cimetidine on oxidative metabolism is dose dependent, is more marked in enzyme induced subjects, is independent of the duration of pretreatment and is of similar magnitude in young and elderly subjects.

Enzyme induction with rifampicin; lipoproteins and drug binding to alpha 1-acid glycoprotein

Hepatic enzyme induction has been reported to increase lignocaine binding, alpha 1-acid glycoprotein concentration and high density lipoprotein (HDL) cholesterol. In eight volunteers treated with rifampicin for 3 weeks there was no significant alteration in these three variables although their antipyrine clearance was significantly increased. In 10 patients with pulmonary tuberculosis treated with rifampicin (mean 5 months) the degree of serum protein binding of lignocaine, alpha 1-acid glycoprotein and HDL-cholesterol concentration was not different from that of matched control patients. These results suggest that differential induction of these variables may occur.

Lack of effect of ranitidine on the disposition of lignocaine

Cimetidine has been shown to alter the disposition of lignocaine and other drugs that are highly extracted by the liver. In a placebo controlled study ranitidine (150 mg twice daily) did not alter the elimination half-life, systemic clearance or distribution of lignocaine (mg/kg) in six healthy subjects. The interaction with cimetidine appears to be unrelated to histamine H2-receptor antagonism.