Glucagon-like peptide-1 receptor expression on human eosinophils and its regulation of eosinophil activation.

BACKGROUND: Glucagon-like peptide-1 (GLP-1) and its receptor are part of the incretin family of hormones that regulate glucose metabolism. GLP-1 also has immune modulatory roles. OBJECTIVES: To measure the expression of the GLP-1 receptor (GLP-1R) on eosinophils and neutrophils in normal and asthmatic subjects and evaluate effects of a GLP-1 analog on eosinophil function. METHODS: Peripheral blood samples were taken from 10 normal and 10 allergic asthmatic subjects. GLP-1R expression was measured on eosinophils and neutrophils. Subsequently, the asthmatic subjects underwent allergen and diluent inhalation challenges, and GLP-1R expression was measured. Purified eosinophils, collected from mild asthmatic subjects, were stimulated with lipopolysaccharide (LPS) and a GLP-1 analog to evaluate eosinophil cell activation markers CD11b and CD69 and cytokine (IL-4, IL-5, IL-8 and IL-13) production. RESULTS: Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. Eosinophil, but not neutrophil, expression of GLP-1R is significantly higher in normal controls compared to allergic asthmatics. The expression of GLP-1R did not change on either eosinophils or neutrophils following allergen challenge. A GLP-1 analog significantly decreased the expression of eosinophil-surface activation markers following LPS stimulation and decreased eosinophil production of IL-4, IL-8 and IL-13, but not IL-5. CONCLUSION AND CLINICAL RELEVANCE: Glucagon-like peptide-1 receptor is expressed on human eosinophils and neutrophils. A GLP-1 analog attenuates LPS-stimulated eosinophil activation. GLP-1 agonists may have additional adjunctive indications in treating persons with concomitant type 2 diabetes mellitus and asthma.

The effect of desmopressin on bleeding time and platelet aggregation in healthy volunteers administered ticagrelor.

WHAT IS KNOWN AND OBJECTIVE: Ticagrelor is a reversibly binding and selective P2Y12 -receptor antagonist approved for the prevention of atherothrombotic events in patients with acute coronary syndromes. As bleeding events remain a hazard with antiplatelet therapy, this study investigated the effect of the vasopressin agonist, desmopressin, on ticagrelor-induced bleeding time prolongation. Desmopressin has previously been shown to improve primary haemostasis and is widely used as first-line therapy for individuals with bleeding disorders. METHODS: In a randomized, double-blind, 2-period crossover study, healthy volunteers received ticagrelor (270 mg loading dose; 180 mg bid) for 5 days. On Day 5, desmopressin (0·3 µg/kg) or saline intravenous infusions were administered. The impact of desmopressin on bleeding time, inhibition of platelet aggregation (IPA), platelet function and ticagrelor pharmacokinetic parameters was investigated. RESULTS: Twenty-one volunteers (81% male) were enrolled. Median [range] bleeding times were slightly reduced with ticagrelor plus desmopressin compared with ticagrelor alone (7·50 [3-17] vs. 10·50 [3-25] min at 2·5 h). Median reductions in bleeding time from baseline were generally similar between ticagrelor plus desmopressin compared with ticagrelor alone at all time points. Co-administration of desmopressin had no impact on IPA, although platelet reactivity was significantly increased (von Willebrand Factor antigen: GLS mean AUEC was 4667%.h for ticagrelor plus desmopressin compared with 2750%.h for ticagrelor alone). Desmopressin did not influence the pharmacokinetics of ticagrelor. WHAT IS NEW AND CONCLUSION: Desmopressin had no significant effect on bleeding time or inhibition of platelet aggregation by ticagrelor, although primary haemostatic activity was significantly increased. Ticagrelor pharmacokinetic parameters were not affected by co-administration with desmopressin. Therefore, desmopressin is unlikely to be an effective therapeutic agent for control of the potential bleeding events associated with ticagrelor.

MIF is a common genetic determinant of COVID-19 symptomatic infection and severity.

BACKGROUND: Genetic predisposition to coronavirus disease 2019 (COVID-19) may contribute to its morbidity and mortality. Because cytokines play an important role in multiple phases of infection, we examined whether commonly occurring, functional polymorphisms in macrophage migration inhibitory factor (MIF) are associated with COVID-19 infection or disease severity. AIM: To determine associations of common functional polymorphisms in MIF with symptomatic COVID-19 or its severity. METHODS: This retrospective case-control study utilized 1171 patients with COVID-19 from three tertiary medical centers in the USA, Hungary and Spain, together with a group of 637 pre-pandemic, healthy control subjects. Functional MIF promoter alleles (-794 CATT5-8,rs5844572), serum MIF and soluble MIF receptor levels, and available clinical characteristics were measured and correlated with COVID-19 diagnosis and hospitalization. Experimental mice genetically engineered to express human high- or low-expression MIF alleles were studied for response to coronavirus infection. RESULTS: In patients with COVID-19, there was a lower frequency of the high-expression MIF CATT7 allele when compared to healthy controls [11% vs. 19%, odds ratio (OR) 0.54 [0.41-0.72], P < 0.0001]. Among inpatients with COVID-19 (n = 805), there was a higher frequency of the MIF CATT7 allele compared to outpatients (n = 187) (12% vs. 5%, OR 2.87 [1.42-5.78], P = 0.002). Inpatients presented with higher serum MIF levels when compared to outpatients or uninfected healthy controls (87 ng/ml vs. 35 ng/ml vs. 29 ng/ml, P < 0.001, respectively). Among inpatients, circulating MIF concentrations correlated with admission ferritin (r = 0.19, P = 0.01) and maximum CRP (r = 0.16, P = 0.03) levels. Mice with a human high-expression MIF allele showed more severe disease than those with a low-expression MIF allele. CONCLUSIONS: In this multinational retrospective study of 1171 subjects with COVID-19, the commonly occurring -794 CATT7MIF allele is associated with reduced susceptibility to symptomatic SARS-CoV-2 infection but increased disease progression as assessed by hospitalization. These findings affirm the importance of the high-expression CATT7MIF allele, which occurs in 19% of the population, in different stages of COVID-19 infection.

Lack of significant food effect on the pharmacokinetics of ticagrelor in healthy volunteers.

WHAT IS KNOWN AND OBJECTIVE: Ticagrelor is the first reversibly binding oral P2Y(12) receptor antagonist and has been approved in the European Union and the USA for the reduction of clinical thrombotic events in patients with acute coronary syndromes. This study aimed to assess the effect of food on ticagrelor pharmacokinetics. METHODS: The study was an open-label, randomized, 2-period crossover single-centre trial; 26 healthy volunteers received a single 270 mg (3×90 mg tablets) ticagrelor dose orally following: (i) a 10-h overnight fast; and (ii) after a standard high-fat, high-calorie breakfast. Ticagrelor and AR-C124910XX (a major pharmacologically active metabolite) plasma concentrations were quantified for pharmacokinetic analysis. RESULTS: Ticagrelor median time to maximum concentration (t(max); 2·5 h vs. 1·5 h) was slightly delayed in the fed vs. fasting state. Maximum concentration of ticagrelor (C(max)) was comparable between the two states with 95% confidence intervals (CI) of the geometric least-squares (GLS) mean ratio (0·85-1·03) being within no-effect limits (0·80-1·25). Ticagrelor exposure was slightly higher with food intake; area under the plasma concentration-time curve from zero to infinity (AUC) was 21% higher compared with fasting state (95% CI of GLS mean ratio=1·13-1·30). For AR-C124910XX, AUC (95% CI of GLS mean ratio=0·93-1·07) was unaffected by food consumption. Median t(max) of the metabolite was slightly longer in the fed than fasting state (3·5 h vs. 1·5 h). Mean C(max) for AR-C124910XX was slightly lower (22%) with food intake vs. fasting (95% CI of GLS mean ratio 0·69-0·88). WHAT IS NEW AND CONCLUSION: Food effects on ticagrelor AUC and AR-C124910XX C(max) were small and are considered to be of minimal clinical significance. Thus, ticagrelor can be administered with or without food.

Long COVID syndrome and the lung: how long will it last?

The prevalence and duration of the long-term respiratory complications of COVID-19 infection remains to be elucidated. This short commentary reports on recently published studies in patients post-acute COVID-19 infection in terms of symptom prevalence, physiological and radiological sequela and where only symptoms are present despite investigation. Pulmonary function testing, 6-min walk tests, computed tomography chest and more advanced imaging modalities have been incorporated to reveal the underlying pathophysiology that cause such disabling symptoms in patient with post-acute COVID-9 syndrome (PACS). PACS has a serious impact on people's ability to return to work, affecting the physical, mental, social sphere and with significant healthcare and general economic consequences for them, their families and society.

Lipopolysaccharide-induced murine lung injury results in long-term pulmonary changes and downregulation of angiogenic pathways.

Acute respiratory distress syndrome is the most severe form of acute lung injury (ALI) and is associated with significant mortality. Lipopolysaccharide (LPS)-induced injury is a valuable murine model of ALI but there is a paucity of data on lung regeneration and the role of angiogenic signaling involving vascular endothelial growth factor (VEGF). Eight-week-old male C57BL/6J mice were randomized to receive intratracheal instillation of either LPS or isovolumetric phosphate buffered saline as a vehicle control. Mice were observed at a single follow-up time-point that was either short-term (24 h or 4 days) or long-term (7 days or 4 weeks). On pulmonary function testing, LPS-treated mice had increased compliance at 4 weeks post-instillation, which correlated with decreased vascularization and with time-dependent, progressive decrease in alveolarization. Treadmill exercise tolerance testing demonstrated impaired performance at 24 h, 4 days and 4 weeks following LPS exposure. On lung protein analysis, LPS instillation decreased VEGF expression at up to 4 weeks, and decreased activation of its key receptor, VEGFR2 at 7 days and 4 weeks post-instillation. Together, these data provide insight on long-term pulmonary functional outcomes 4 weeks after ALI and identify angiogenic proteins as possible therapeutic targets following lung injury.

An in-line digestive cartridge increases enteral fat and vitamin absorption in a porcine model of short bowel syndrome.

BACKGROUND & AIMS: Short bowel syndrome (SBS) occurs after intestinal loss resulting in parenteral nutrition dependence and micronutrient deficiencies, which may lead to life-limiting complications. ALC-078 is a cartridge containing immobilized lipase that connects in-line with enteral feeding sets and digests fats in enteral nutrition (EN). In this study, we evaluate the efficacy of ALC-078 to improve fat and nutrient absorption in a porcine SBS model. METHODS: Fifteen male Yorkshire piglets were assessed. Animals were randomized to no intestinal resection (n = 5), 75% resection (n = 5), or 75% resection + ALC-078 (n = 5). After recovery, animals were treated for 14 days. Piglets received 60% of nutrition from continuous EN and 40% from chow. The degree of fat malabsorption was determined by the coefficient of fat absorption (CFA) following a 72-h stool collection. Body weight, fat-soluble vitamins, and nutritional markers were assessed. RESULTS: Adverse events were similar across the three groups (P = 1.00). ALC-078-treated animals had similar weight gain compared to resected piglets. Resected animals had a lower CFA compared to unresected controls (79.3% vs. 95.2%, P = 0.01) while there was no significant difference in the ALC-078 animals (87.1% vs. 95.2%, P = 0.19). Between Study Days 1 and 15, ALC-078 animals had increased concentrations of vitamin D (12.2 vs. 8.7 ng/mL, P = 0.0006), and vitamin E (4.3 vs. 2.5 mg/L, P = 0.03). These markers did not significantly change in untreated resected animals. CONCLUSION: ALC-078 increases the absorption of fat-soluble vitamins and may improve fat malabsorption. Future studies should determine whether ALC-078 can reduce PN dependence and if these findings translate to human patients with SBS.

A prospective study of screening for musculoskeletal pathology in the child with a limp or pseudoparalysis using erythrocyte sedimentation rate, C-reactive protein and MRI.

PURPOSE: To determine if the detection of musculoskeletal pathology in children with a limp or acute limb disuse can be optimized by screening with blood tests for raised inflammatory markers, followed by MRI. METHODS: This was a prospective observational study. Entry criteria were children (0 to 16 years of age) presenting to our emergency department with a non-traumatic limp or pseudoparalysis of a limb, and no abnormality on plain radiographs. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) blood tests were performed. Children with ESR > 10 mm/hr or CRP > 10 mg/L underwent a MRI scan. When the location of the pathology causing the limp was clinically unclear, screening images (Cor t1 and Short Tau Inversion Recovery) of both lower limbs from pelvis to ankles ('legogram') was undertaken. Data was gathered prospectively from 100 consecutive children meeting the study criteria. RESULTS: In all, 75% of children had a positive finding on their MRI. A total of 64% of cases had an infective cause for their symptoms (osteomyelitis, septic arthritis, pyomyositis, fasciitis, cellulitis or discitis). A further 11% had positive findings on MRI from non-infective causes (juvenile idiopathic arthritis, cancer or undisplaced fracture). The remaining 25% had either a normal scan or effusion due to transient synovitis. ESR was a more sensitive marker than CRP in infection, since ESR was raised in 97%, but CRP in only 70%. CONCLUSION: In our opinion MRI imaging of all children with a limp and either raised ESR or CRP is a sensitive method to minimize the chance of missing important pathology in this group, and is an effective use of MRI resources. We advocate the use of both blood tests in conjunction. LEVEL OF EVIDENCE: Level II.

Panton-Valentine leukocidin-secreting Staphylococcus aureus causing severe musculoskeletal sepsis in children. A new threat.

Panton-Valentine leukocidin secreted by Staphylococcus aureus is known to cause severe skin, soft tissue and lung infections. However, until recently it has not been described as causing life-threatening musculoskeletal infection. We present four patients suffering from osteomyelitis, septic arthritis, widespread intravascular thrombosis and overwhelming sepsis from proven Panton-Valentine leukocidin-secreting Staphylococcus aureus. Aggressive, early and repeated surgical intervention is required in the treatment of these patients. The Panton-Valentine leukocidin toxin not only destroys host neutrophils, immunocompromising the patient, but also increases the risk of intravascular coagulopathy. This combination leads to widespread involvement of bone with glutinous pus which is difficult to drain, and makes the delivery of antibiotics and eradication of infection very difficult without surgical intervention.

The value of MRI undertaken immediately after reduction of the hip as a predictor of long-term acetabular dysplasia.

Our aim was to determine whether abnormalities noted on MRI immediately after reduction for developmental dysplasia of the hip could predict the persistance of dysplasia and aid surgical planning. Scans of 13 hips in which acetabular dysplasia had resolved by the age of four years were compared with those of five which had required pelvic osteotomy for persisting dysplasia. The scans were analysed by two consultant musculoskeletal radiologists who were blinded to the outcome in each child. The postreduction scans highlighted a number of anatomical abnormalities secondary to developmental dysplasia of the hip, but statistical analysis showed that none were predictive of persisting acetabular dysplasia in the older child, suggesting that the factors which determine the long-term outcome were not visible on these images.

Emerging monoclonal antibodies as targeted innovative therapeutic approaches to asthma.

Asthma is characterized by discordant responses among cells of the adaptive and innate immune systems. This interplay involves a complex pattern of cytokine-driven processes resulting in cell migration and recruitment, inflammation, and proliferative states. The significant majority of asthmatic patients respond well to conventional inhaled treatments. However, about 5% of asthmatics have severe refractory asthma and account for 50% of the health expenditure on asthma. Human(ized) monoclonal antibodies (hMabs) targeting inflammatory pathways are promising therapeutic agents in asthma management. The anti-IgE hMab omalizumab was the first biologic treatment approved for the treatment of allergic asthma. Potential future strategies and targets include interleukin (IL)-5, IL-4, and IL-13, anti-TSLP, IL-25, and IL-33. hMabs targeting IL-5 have shown great promise in severe refractory asthma with a persisting eosinophilia, and clinical trials with hMabs against IL-13 and IL4Rα have also shown clinical benefit. Studies of hMabs against other cytokines in severe asthma are under way.

Effect of extended diapause on evolution of resistance to transgenic Bacillus thuringiensis corn by northern corn rootworm (Coleoptera: Chrysomelidae).

We develop a population genetics model for the northern corn rootworm, Diabrotica barberi Smith & Lawrence, to examine the effect of extended diapause on the evolution of resistance to transgenic Bacillus thuringiensis (Bt) corn, Zea mays L. We model conditions found in the center of the extended diapause problem along the Minnesota-South Dakota-Iowa borders. The proportion of resistance alleles in eggs oviposited after 15 simulated years is used to measure the evolution of resistance. Sensitivity analysis indicates that although population genetics parameters (fecundity, initial egg density, density-dependent larval survival, random mating, insecticide mortality, and gene expression) affect the evolution of resistance, product characteristics (e.g., Bt toxin dose) and farmer management practices (e.g., insecticide use on refuge corn and rotation pattern) generally have a larger impact on the development of resistance. Exceptions to this generalization exist: 1) if the resistance allele is dominant, resistance evolves quickly; 2) the level of random mating is an important determinant of how quickly resistance evolves for a theoretical high dose product; and 3) small differences in insecticide mortality imply large differences in resistance for medium- and low-dose products with high levels of Bt corn adoption and a predominance of 1- and 2-yr corn rotations. When extended diapause spreads into a new area, it typically reduces resistance to Bt corn, assuming Bt corn is used only on continuous corn. In the study region where extended diapause already exists, increasing extended diapause (increasing hatch rates after two or three winters while holding total hatch constant), tends to increase resistance because the resistance increasing effect of the hatch rate after two winters dominates the resistance decreasing effect of the hatch rate after three winters. However, this is not always the case, because combinations of rotation pattern, toxin dose, and soil insecticide use exist for which the net effect of extended diapause decreases resistance. Results are interpreted as a combination of two offsetting effects. First, extended diapause injects older alleles with lower resistance allele frequencies into the breeding population, which slows resistance. Second, extended diapause speeds the population's recovery from perturbations (reduces the undercompensating density dependence of population dynamics), which accelerates resistance.

Economic analysis of dynamic management strategies utilizing. Transgenic corn for control of western corn rootworm (Coleoptera: Chrysomelidae).

We studied management strategies for western corn rootworm, Diabrotica virgifera virgifera LeConte, using transgenic corn, Zea mays L., from both a biological and an economic perspective. In areas with and without populations adapted to a 2-yr rotation of corn and soybean (rotation-resistant), the standard management strategy was to plant 80% of a cornfield (rotated and continuous) to a transgenic cultivar each year. In each area, we also studied dynamic management strategies where the proportion of transgenic corn increased over time in a region. We also analyzed management strategies for a single field that is the first to adopt transgenic corn within a larger unmanaged region. In all areas, increasing the expression of the toxin in the plant increased economic returns. In areas without rotation-resistance, planting 80% transgenic corn in the continuous cornfield each year generated the greatest returns with a medium toxin dose or greater. In areas with alleles for rotation-resistance at low initial levels, a 2-yr rotation of nontransgenic corn and soybean, Glycine max (L.) Merr., may be the most economical strategy if resistance to crop rotation is recessive. If resistance to crop rotation is additive or dominant, planting transgenic corn in the rotated cornfield was the most effective strategy. In areas where rotation-resistance is already a severe problem, planting transgenic corn in the rotated cornfield each year was always the most economical strategy. In some cases the strategies that increased the proportion of transgenic corn in the region over time increased returns compared with the standard strategies. With these strategies the evolution of resistance to crop rotation occurred more rapidly but resistance to transgenic corn was delayed compared with the standard management strategy. In areas not managed by a regional norm, increasing the proportion of transgenic corn and increasing toxin dose in the managed field generally increased returns. In a sensitivity analysis, among the parameters investigated, only density-dependent survival affected the results.

Inhibition of Uptake1 by dopexamine hydrochloride in vitro.

1 Dopexamine hydrochloride, a compound under evaluation for the acute treatment of heart failure, was examined in vitro for its ability to prevent neuronal uptake of noradrenaline. 2 Despite possessing only weak beta 1-adrenoceptor agonist activity in paced guinea-pig left atria, dopexamine hydrochloride was only 23 times less potent than isoprenaline in augmenting responses of field-stimulated atrial preparations. 3 This potent effect was not observed in field-stimulated atria depleted of noradrenaline by reserpine and in the presence of cocaine was greatly reduced (1 microM) or abolished (50 microM). 4 Dopexamine hydrochloride (3 microM) potentiated the inotropic effect of exogenous noradrenaline in paced atria, thereby resembling cocaine (10 microM) and dopamine (30 microM), both of which are known inhibitors of Uptake. 5 The sodium-dependent uptake of [3H]-noradrenaline into rabbit brain synaptosomes was prevented by dopexamine hydrochloride (IC50 26 nM) and cocaine (IC50 108 nM), as well as by two other catecholamines used in the treatment of heart failure, dopamine (IC50 270 nM) and dobutamine (IC50 380 nM). 6 The cardiac stimulant effect of dopexamine hydrochloride reported in dogs and in patients with heart failure, may therefore be due in part to potentiation of endogenous catecholamines.

FPL 63012AR: a potent D1-receptor agonist.

1. FPL 63012AR is a D1-receptor agonist in the dog kidney, 10 times as potent as dopamine, reducing renal vascular resistance by 20% with an intra-arterial dose of 0.42 nmol kg-1. 2. No prejunctional inhibitory D2-receptor agonist activity was detected in either the isolated ear artery of the rabbit or in the conscious dog as D2-receptor-mediated emesis. 3. Unlike dopamine, FPL 63012AR had no significant agonist activity at alpha 1-, alpha 2-, beta 1- or beta 2-adrenoceptors. 4. FPL 63012AR is a potent inhibitor of [3H]-noradrenaline uptake (Uptake1) into brain synaptosomes, with an IC50 of 29.5 nM, i.e. 9.2 times more potent than dopamine. 5. The ability to block Uptake1, in the anaesthetised dog was confirmed by inhibition of the tyramine-induced pressor and inotropic responses. 6. Intravenous infusion of FPL 63012AR in anaesthetized and conscious dogs (0.3 to 3 nmol kg-1 min-1) reduced vascular resistance and increased blood flow to the kidney which was accompanied by hypotension and tachycardia. 7. It is concluded that FPL 63012AR is an example of a novel class of potent agonists at the D-receptor. Such compounds may have the potential for use clinically in improving renal perfusion and reducing afterload.

Evaluation of a commercial DNA purification system for plasmid analysis of nosocomial bacterial pathogens.

This study evaluated the Promega Magic Minipreps (MM) (Promega Corporation, Madison, WI) DNA purification system for use in plasmid analysis of common nosocomial bacterial pathogens. The MM system is a kit that includes lysis solutions and buffers and incorporates a minicolumn of DNA binding resin for recovery of plasmid DNA. The MM system was used according to the manufacturer's directions to recover plasmids for agarose gel electrophoresis from clinical isolates of Acinetobacter calcoaceticus, Enterobacter cloacae, and Klebsiella pneumoniae. For Salmonella enteritidis and Staphylococcus aureus, lysozyme and lysostaphin, respectively, were used for pretreatment. Plasmid DNA from ten isolates could be recovered in approximately one hour with very little manipulation and no phenol/chloroform extractions and was suitable for restriction endonuclease digestion. Compared with a standard miniprep protocol, the MM system was much easier to perform and resulted in significant cost savings due to a 50% reduction in technologist time. The authors conclude that the MM system is a convenient and cost-effective method for clinical microbiology laboratories for recovering plasmid DNA from nosocomial bacterial pathogens.

Isolation of Borrelia burgdorferi from skin biopsy specimens of patients with erythema migrans.

Procedures for the cultural isolation and identification of Borrelia burgdorferi from skin biopsy specimens are described. B. burgdorferi was isolated from 24 of 34 skin biopsy specimens from patients with erythema migrans. Eight of the culture-positive patients had single, primary lesions and 16 had multiple, secondary lesions. The 17 male and 7 female patients were 2 to 70 years old. Biopsy samples were obtained from erythematous or normal-appearing skin within 1 cm of the peripheral aspect of the lesion. Twenty-three of the isolates were detected within 8 days of incubation in Barbour-Stoenner-Kelly medium with no antimicrobial agents. The identities of the isolates were determined by reactivity with monoclonal antibodies H9724 and H5332. Cultivation of B. burgdorferi from skin lesions suggestive of erythema migrans is a practical and clinically relevant procedure. Clinical isolates and corresponding patient sera and urine will contribute to efforts to improve existing immunoserologic testing methods and develop new assays to diagnose Lyme borreliosis.

An evaluation of media for transport of tissues infected with Borrelia burgdorferi.

Currently, the best medium for culture of Borrelia burgdorferi, the etiologic agent of Lyme disease, is Barbour-Stoenner-Kelly (BSK), or its modifications. This medium is complex, expensive, and laborious to prepare. A recent report suggested that a less expensive and simpler medium, hypertonic Columbia broth, might be useful as a transport medium for human tissues infected with B burgdorferi. To test this observation, hypertonic Columbia broth, Amies broth, distilled water, physiologic saline, phosphate-buffered saline (PBS), and modified Stuart medium were compared with BSK II as transport media, using ear and tail tissue samples from B burgdorferi-infected laboratory mice and using holding times and temperatures simulating actual transport conditions. The results showed BSK II to be markedly superior to the other media tested, although B burgdorferi remained viable in a few tissue samples held at room temperature in hypertonic Columbia broth, physiologic saline, or PBS for up to 2 days. Barbour-Stoenner-Kelly II continues to be the best medium for transport of tissues infected with B burgdorferi.