ScRNA-Seq Reveals a Distinct Osteogenic Progenitor of Alveolar Bone

The metabolism and remodeling of alveolar bone are the most active among the whole skeletal system, which is related to the biological characteristics and heterogeneity of the bone mesenchymal stromal cells (MSCs). However, there is a lack of systematic description of the heterogeneity of MSC-derived osteoblastic lineage cells as well as their distinct osteogenic differentiation trajectory of alveolar bone. In this study, we constructed a single-cell atlas of the mouse alveolar bone cells through single-cell RNA sequencing (scRNA-seq). Remarkably, by comparing the cell compositions between the alveolar bone and long bone, we uncovered a previously undescribed cell population that exhibits a high expression of protocadherin Fat4 (Fat4⁺ cells) and is specifically enriched around alveolar bone marrow cavities. ScRNA-seq analysis indicated that Fat4⁺ cells may initiate a distinct osteogenic differentiation trajectory in the alveolar bone. By isolating and cultivating Fat4⁺ cells in vitro, we demonstrated that they possess colony-forming, osteogenic, and adipogenic capabilities. Moreover, FAT4 knockdown could significantly inhibit the osteogenic differentiation of alveolar bone MSCs. Furthermore, we revealed that the Fat4⁺ cells exhibit a core transcriptional signature consisting of several key transcription factors, such as SOX6, which are involved in osteogenesis, and further demonstrated that SOX6 is required for the efficient osteogenic differentiation of the Fat4⁺ cells. Collectively, our high-resolution single-cell atlas of the alveolar bone reveals a distinct osteogenic progenitor that may contribute to the unique physiological characteristics of alveolar bone.

Osteoblastic RAR Inhibition Causes VAD-Like Craniofacial Skeletal Deformity

Retinoid signaling disorders cause craniofacial deformity, among which infants with maternal vitamin A deficiency (VAD) exhibited malformation of the eye, nose, palate, and parietal and jaw bone. Previous research uncovered the pathogenesis of eye defect and cleft palate of VAD in mice, but the studies on craniofacial skeletal deformity met obstacles, and the cell/lineage and underlying mechanism remain unclear. The retinoic acid receptor (RAR) is the key transcription factor in retinoid signaling, but individual knockout cannot simulate pathway inhibition. Here, we conditionally expressed dominant-negative RARα mutation (dnRARα) in osteoblasts to specifically inhibit the transcription activity of RAR in mice, which mimics the craniofacial deformities caused by VAD in clinical cases: hypomineralization of cranial bones, mandibular deformity, and clavicular hypoplasia. Furthermore, we performed 3-dimensional reconstruction based on micro-computed tomography and confirmed the abnormalities in the shape, size, and ossification of craniofacial bones due to osteoblastic RAR inhibition. Histological analysis indicated that inhibition of RAR in osteoblasts impaired both bone formation and bone resorption, which was confirmed by transcriptome sequencing of the calvaria. Furthermore, mechanism investigation showed that inhibition of RAR in osteoblasts directly decreased osteoblast differentiation in a cell-autonomous manner by impairing osteogenic gene transcription and also inhibited osteoclast differentiation via osteoblast-osteoclast crosstalk by impairing Rankl transcription. In summary, osteoblastic RAR activity is critical to craniofacial skeletal development, and its dysfunction leads to skeletal deformities mimicking VAD craniofacial defects, providing a new insight for VAD pathogenesis.

FOXO3 Mediates Tooth Movement by Regulating Force-Induced Osteogenesis

The high prevalence of malocclusion and dentofacial malformations means that the demand for orthodontic treatments has been increasing rapidly. As the biological basis of orthodontic treatment, the mechanism of mechanical force-induced alveolar bone remodeling during orthodontic tooth movement (OTM) has become the key scientific issue of orthodontics. It has been demonstrated that bone mesenchymal stem cells (BMSCs) are crucial for bone remodeling and exhibit mechanical sensing properties. Mechanical force can promote osteoblastic differentiation of BMSCs and osteogenesis, but the key factor that mediates mechanical force-induced osteogenesis during OTM remains unclear. In this study, by performing reverse-phase protein arrays on BMSCs exposed to mechanical force, we found that the expression level of forkhead box O3 (FOXO3) was significantly upregulated during the mechanical force-induced osteoblastic differentiation of BMSCs. The number of FOXO3-positive cells was consistently higher on the OTM side as compared with the control side and accompanied by the enhancement of osteogenesis. Remarkably, inhibiting FOXO3 with repaglinide delayed OTM by severely impairing mechanical force-induced bone formation in vivo. Moreover, knockdown of FOXO3 effectively inhibited the mechanical force-induced osteoblastic differentiation of BMSCs, whereas the overexpression of FOXO3 enhanced this effect. Mechanistically, we revealed a novel regulatory model in which FOXO3 promoted osteocalcin transcription by activating its promoter in cooperation with runt-related transcription factor 2 (RUNX2). We collectively obtained the first evidence that FOXO3 is critical for OTM, where it responds to mechanical force and directly regulates downstream osteoblastic differentiation in an efficient manner.

POS1095 FOOD SOURCES OF DIETARY FIBRE AND RISK OF TOTAL KNEE REPLACEMENT RELATED TO SEVERE OSTEOARTHRITIS, THE SINGAPORE CHINESE HEALTH STUDY

Background:

Although fibre intake was inversely associated with the risk of symptomatic knee osteoarthritis (KOA) in a US study, this association was partially confounded by lower body mass index (BMI) in those with higher fibre intake.

Objectives:

We evaluated the association between fibre intake and its food sources, and the risk of total knee replacement (TKR) due to severe KOA.

Methods:

We used data from the Singapore Chinese Health Study, a prospective cohort study that recruited 63,257 participants aged 45-74 years from 1993 to 1998. At baseline, we assessed diet using a validated 165-item semi-quantitative food frequency questionnaire, together with BMI and lifestyle factors. Incident TKR cases were identified via record linkage with nationwide hospital discharge database through 2017. We used multivariable Cox regression models to compute hazard ratio (HR) and the corresponding 95% confidence interval (CI) for risk of TKR.

Results:

There were 2,816 cases of incident TKR due to severe KOA. Total fibre intake at baseline was not associated with risk of TKR after adjustment for confounders. Among the food sources of fibre, higher intake of legumes was associated with lower risk of TKR in dose-dependent manner; compared with those having the lowest quartile intake, HR (95% CI) was 0.86 (0.76, 0.96) for the highest quartile (p for trend = 0.004). This association was consistent after including BMI in the model, and homogenous across BMI categories. The consumption of other fibre sources, namely grain products, nuts and seeds, soy food, fruits and vegetables, was not associated with risk of TKR.

Conclusion:

Intake of legumes, but not total fibre, was associated with a reduced risk of TKR. Further research is needed to replicate our findings, and to evaluate possible biological mechanisms that could explain the effect of dietary legumes in pathogenesis or progression of KOA.

Table 1.

Hazard ratios (95% confidence intervals) for risk of total knee replacement according to intake of fibre (only shown total fibre and legumes): The Singapore Chinese Health Study (1993-2017).

Quartiles of energy-adjusted food intakeQ1Q2Q3Q4p for trend 1Total fibreMedian, g/day8.559.4312.1917.70Cases/ person-years528/ 275,050712/ 280,456767/ 284,394809/ 287,955Multivariate Model 11.001.08 (0.96, 1.21)1.12 (1.00, 1.26)1.18 (1.05, 1.32)0.003Multivariate Model 21.001.06 (0.95, 1.19)1.09 (0.97, 1.22)1.11 (0.99, 1.24)0.088LegumesMedian, g/day0.110.432.117.01Cases/ person-years638/ 280,170754/ 278,001756/ 280,407668/ 289,275Multivariate Model 11.000.97 (0.87, 1.09)0.95 (0.84, 1.06)0.84 (0.76, 0.94)<0.001Multivariate Model 21.000.98 (0.87, 1.09)0.94 (0.84, 1.06)0.86 (0.77, 0.96)0.004Multivariate Model 31.000.98 (0.87, 1.09)0.95 (0.84, 1.06)0.86 (0.76, 0.96)0.004

1Linear trend was tested by assigning to participants the median value of the quartile and treating this as a continuous variable. 2 The grain products included noodles and pasta, rice, bread and pancakes, breakfast cereals, biscuits and crackers.

Multivariate model 1: adjusted for age at interview, sex, year of interview, total energy intake, dialect, education level

Multivariate model 2: model 1 plus BMI, sitting duration, sleep, physical activity, smoking, history of hypertension, diabetes, coronary artery disease and stroke.

Multivariate model 3: model 2 plus grain products, legumes, nuts and seeds, soy food, fruits and vegetables.

Q = quartile

Disclosure of Interests:

None declared.

Fabrication of a Self-Curling Cuff with a Soft, Ionically Conducting Neural Interface

Direct current (DC) has the potential not only to excite but also to inhibit neurons. This property of DC stimulus has been used for generating peripheral nerve blocks. One translational challenge of DC-based neuromodulation technologies, especially for pain suppression, is that the commercially available cuff electrodes have metal-tissue interfaces that are incapable of delivering DC safely. Passing DC through any metal-tissue interface generates harmful electrochemical products which can damage the target nerve. To address this issue, we present a fabrication process for making self-curling silicone cuffs with paper/agar based, ionically conducting neural interface. We fabricate monopolar as well as bipolar cuffs and demonstrate that the electrode impedances can be easily controlled by modulating the paper/agar channel dimensions. Further, we perform in-vivo implantation of these electrodes on a rat sciatic nerve to qualitatively validate the self-curling action.

Recurrent post-partum rhombencephalitis associated with anti-centromere antibody: a case report

Background

Rhombencephalitis (RE) is a serious condition of the brain with multiple etiologies. We report a unique case of recurrent, postpartum RE that is associated with positive anti-centromere antibody (ACA). A discussion of the case, current literature on autoimmune RE and related autoantibodies are reviewed.

Case presentation

A healthy 33-year-old Caucasian patient (gravida 2, para 2) had two episodes of progressive focal neurological deficits during postpartum periods. Signs and symptoms included right-sided dysmetria, adiadochokinesia, weakness, ataxia, and photophobia. MRI revealed rhombencephalitis involving the mesencephalon of the brainstem. Extensive and comprehensive investigations using blood and cerebrospinal fluid (CSF) were consistently positive only for ACA. The first episode was successfully treated with empiric antimicrobial agents and steroid. Given the negative infectious work up with the prior episode and the nearly identical clinical presentations, the second episode was treated with corticosteroid only. This led to complete resolution of her symptoms and reversal of the brain magnetic resonance imaging (MRI) lesions.

Conclusion

To the author's knowledge, this is the first report of a primary autoimmune RE during postpartum period that is associated with ACA. Immunologic causes should be considered early with any encephalitis. Given the risk of recurrence, relapse, and neurologic deterioration, regular monitoring is recommended, especially for female patients of child-bearing age. Consistent with the current literature on autoimmune RE, steroid seems to be an effective treatment for ACA-associated RE.

Clot Burden Score and Early Ischemia Predict Intracranial Hemorrhage following Endovascular Therapy

BACKGROUND AND PURPOSE

Intracranial hemorrhage is a known complication following endovascular thrombectomy. The radiologic characteristics of a CT scan may assist with hemorrhage risk stratification. We assessed the radiologic predictors of intracranial hemorrhage following endovascular therapy using data from the INTERRSeCT (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography) study.

MATERIALS AND METHODS

Patients undergoing endovascular therapy underwent baseline imaging, postprocedural angiography, and 24-hour follow-up imaging. The primary outcome was any intracranial hemorrhage observed on follow-up imaging. The secondary outcome was symptomatic hemorrhage. We assessed the relationship between hemorrhage occurrence and baseline patient characteristics, clinical course, and imaging factors: baseline ASPECTS, thrombus location, residual flow grade, collateralization, and clot burden score. Multivariable logistic regression with backward selection was used to adjust for relevant covariates.

RESULTS

Of the 199 enrolled patients who met the inclusion criteria, 46 (23%) had an intracranial hemorrhage at 24 hours. On multivariable analysis, postprocedural hemorrhage was associated with pretreatment ASPECTS (OR, 1.56 per point lost; 95% CI, 1.12-2.15), clot burden score (OR, 1.19 per point lost; 95% CI, 1.03-1.38), and ICA thrombus location (OR, 3.10; 95% CI, 1.07-8.91). In post hoc analysis, clot burden scores of ≤3 (sensitivity, 41%; specificity, 82%; OR, 3.12; 95% CI, 1.36-7.15) and pretreatment ASPECTS ≤ 7 (sensitivity, 48%; specificity, 82%; OR, 3.17; 95% CI, 1.35-7.45) robustly predicted hemorrhage. Residual flow grade and collateralization were not associated with hemorrhage occurrence. Symptomatic hemorrhage was observed in 4 patients.

CONCLUSIONS

Radiologic factors, early ischemia on CT, and increased CTA clot burden are associated with an increased risk of intracranial hemorrhage in patients undergoing endovascular therapy.

Variable impact of tizanidine on the medium latency reflex of upper and lower limbs

Sudden limb displacement evokes a complex sequence of compensatory muscle activity. Following the short-latency reflex and preceding voluntary reactions is an epoch termed the medium-latency reflex (MLR) that could reflect spinal processing of group II muscle afferents. One way to test this possibility is oral ingestion of tizanidine, an alpha-2 adrenergic agonist that inhibits the interneurons transmitting group II signals onto spinal motor neurons. We examined whether group II afferents contribute to MLR activity throughout the major muscles that span the elbow and shoulder. MLRs of ankle muscles were also tested during walking on the same day, in the same participants as well as during sitting in a different group of subjects. In contrast to previous reports, the ingestion of tizanidine had minimal impact on MLRs of arm or leg muscles during motor actions. A significant decrease in magnitude was observed for 2/16 contrasts in arm muscles and 0/4 contrasts in leg muscles. This discrepancy with previous studies could indicate that tizanidine's efficacy is altered by subtle changes in protocol or that group II afferents do not substantially contribute to MLRs.

The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density

Objectives

Bisphosphonates (BP) are the first-line treatment for preventing fragility fractures. However, concern regarding their efficacy is growing because bisphosphonate is associated with over-suppression of remodelling and accumulation of microcracks. While dual-energy X-ray absorptiometry (DXA) scanning may show a gain in bone density, the impact of this class of drug on mechanical properties remains unclear. We therefore sought to quantify the mechanical strength of bone treated with BP (oral alendronate), and correlate data with the microarchitecture and density of microcracks in comparison with untreated controls.

Methods

Trabecular bone from hip fracture patients treated with BP (n = 10) was compared with naïve fractured (n = 14) and non-fractured controls (n = 6). Trabecular cores were synchrotron scanned and micro-CT scanned for microstructural analysis, including quantification of bone volume fraction, microarchitecture and microcracks. The specimens were then mechanically tested in compression.

Results

BP bone was 28% lower in strength than untreated hip fracture bone, and 48% lower in strength than non-fractured control bone (4.6 MPa vs 6.4 MPa vs 8.9 MPa). BP-treated bone had 24% more microcracks than naïve fractured bone and 51% more than non-fractured control (8.12/cm²vs 6.55/cm²vs 5.25/cm²). BP and naïve fracture bone exhibited similar trabecular microarchitecture, with significantly lower bone volume fraction and connectivity than non-fractured controls.

Conclusion

BP therapy had no detectable mechanical benefit in the specimens examined. Instead, its use was associated with substantially reduced bone strength. This low strength may be due to the greater accumulation of microcracks and a lack of any discernible improvement in bone volume or microarchitecture. This preliminary study suggests that the clinical impact of BP-induced microcrack accumulation may be significant.

Cite this article: A. Jin, J. Cobb, U. Hansen, R. Bhattacharya, C. Reinhard, N. Vo, R. Atwood, J. Li, A. Karunaratne, C. Wiles, R. Abel. The effect of long-term bisphosphonate therapy on trabecular bone strength and microcrack density. Bone Joint Res 2017;6:602–609. DOI: 10.1302/2046-3758.610.BJR-2016-0321.R1.

Heel reconstruction with parallel fibular osteoseptocutaneous flap

Reconstruction of heel defects can be challenging and requires careful consideration in restoring both the functional and aesthetic deficit. This study assessed the use of parallel fibular osteoseptocutaneous flap to repair composite heel defects. Follow-up of the 4 patients included in this study ranged from 24 months to 3 years after their operation. The flap survival rate was 100% in all patients, with good coverage of the heel defects. Postoperative complication was one -superficial wound infection. Union of the graft with the host bone was achieved in all patients at an average of 6 months (range : 5-10 m/onths). The parallel fibular osteoseptocutaneous flap is thus a reliable means of reconstruction of composite bone and soft-tissue -defect in the heel region.

Ecological analyses of the associations between injury risk and socioeconomic status, geography and Aboriginal ethnicity in British Columbia, Canada

BACKGROUND

The current study examines what factors contribute to higher injury risk among Aboriginal peoples, compared to the total British Columbia (BC) population. We explore socioeconomic, geographic, and cultural factors, and combinations of these factors, that contribute to increased injury risk for Aboriginal peoples. This follows from our previously reported findings of improvements in injury risk over time for both the total and Aboriginal populations.

DATA AND METHODS

We use provincial population-based linked health care databases of hospital discharge records. We identify three population groups: total BC population, and Aboriginal populations living off-reserve, or on-reserve. For each group we calculate age and gender-standardized relative risks (SRR) of injury-related hospitalization, relative to the total population of BC, for two 5-year time periods (1999-2003, and 2004-2008). We use custom data from the 2001 and 2006 long-form Censuses that described income, education, employment, housing conditions, proportion of urban dwellers, proportion of rural dwellers, and prevalence of Aboriginal ethnicity. We use multivariable linear regression to examine the associations between the census characteristics and SRR of injury.

RESULTS

The best-fitting model was an excellent fit (R(2) = 0.905, p < 0.001) among the three population groups within Health Service Delivery Areas of BC. We find indicators in all three categories (socioeconomic, geographic, and cultural) are associated with disparity in injury risk. While the socioeconomic indicators (income, education, housing, employment) were shown to be highly correlated, only living in housing that needs major repair and occupational hazardousness, along with rural residence and Aboriginal ethnicity, remained in the final model. Our data show that cultural density is not associated with injury risk for Aboriginal peoples, and that living off-reserve is associated with reduced injury by improving socioeconomic and geographic conditions (compared to living on-reserve). Finally, our analyses show that Aboriginal status itself is associated with injury risk.

CONCLUSIONS

Our findings confirm previous research indicating that geographical differences differentiate injury risk, including for Aboriginal populations, and that socioeconomic determinants are associated with health risks. Our analyses showing that Aboriginal status itself contributes to injury risk is new, but we can only speculate about pathway, and whether the causes are direct or indirect.

Homocysteine induces glyceraldehyde-3-phosphate dehydrogenase acetylation and apoptosis in the neuroblastoma cell line Neuro2a

High plasma levels of homocysteine (Hcy) promote the progression of neurodegenerative diseases. However, the mechanism by which Hcy mediates neurotoxicity has not been elucidated. We observed that upon incubation with Hcy, the viability of a neuroblastoma cell line Neuro2a declined in a dose-dependent manner, and apoptosis was induced within 48 h. The median effective concentration (EC₅₀) of Hcy was approximately 5 mM. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) nuclear translocation and acylation has been implicated in the regulation of apoptosis. We found that nuclear translocation and acetylation of GAPDH increased in the presence of 5 mM Hcy and that higher levels of acetyltransferase p300/CBP were detected in Neuro2a cells. These findings implicate the involvement of GAPDH in the mechanism whereby Hcy induces apoptosis in neurons. This study highlights a potentially important pathway in neurodegenerative disorders, and a novel target pathway for neuroprotective therapy.

Identity priming consistently affects perceptual fluency but only affects metamemory when primes are obvious

Perceptual fluency manipulations influence metamemory judgments, with more fluently perceived information judged as more memorable. However, it is not always clear whether this influence is driven by actual experienced processing fluency or by beliefs about memory. The current study used an identity-priming paradigm-in which words are preceded by either matched (identical) or mismatched primes-to examine the 2 influences. Participants named and made judgments of learning (JOLs) for critical words and then completed a memory test. In Experiment 1, we briefly presented the primes and found a priming effect on naming latencies but not on JOLs. In Experiment 2, we presented the primes for longer durations and, again, found an effect on naming in addition to an effect on JOLs. A mediation analysis revealed that naming latencies did not account for the prime-JOL relationship. This pattern of results demonstrated a manipulation of perceptual fluency that influenced JOLs only when belief-based information was readily available.

Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone

A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications.

Combined supercontinuum source with >200 W power using a 3 × 1 broadband fiber power combiner

We report an incoherently combined near-infrared supercontinuum (SC) source with >200  W output power using a 3×1 broadband fiber power combiner. A broadband fiber power combiner is designed and theoretically investigated. The power transmission efficiencies of light at different wavelengths of the combiner are calculated, and the combiner is verified to be capable of combining broadband sources efficiently. Then a combiner is fabricated. Three ∼70  W near-infrared SC sources are constructed and then, using the combiner, a >200  W near-infrared SC source is obtained. Conclusively, using incoherently combining method we can obtain a high-power SC source, and the thermo-management can be realized easily. We believe that this is a suitable method to obtain a higher-power SC source.

Comparison of testing approaches for Clostridium difficile infection at a large community hospital

Multiple diagnostic approaches are available for Clostridium difficile infection (CDI); current guidelines support two-step testing (2ST) as the preferred approach. We retrospectively evaluated the impact of switching from toxin enzyme immunoassay (EIA) to 2ST, and then to polymerase chain reaction (PCR), on CDI rates, test utilization and CDI treatment at a 900-bed tertiary care community teaching hospital. All inpatients tested for CDI between December 2008 and February 2011 were included. A positive toxin EIA or PCR was diagnostic of CDI; 2ST was performed using glutamate dehydrogenase EIA, followed by PCR if positive. Repeat tests within 8 weeks on the same patient were considered part of the same testing episode. Data were collected electronically and studied in aggregate from 9725 unique inpatients tested for CDI, representing 20 836 individual tests. PCR detected 41% more patients with CDI than toxin EIA (p <0.0001), and 15% more than 2ST (p 0.02), corresponding to higher hospital-onset and community-onset CDI rates. The number of CDI tests performed per patient decreased by 48% with PCR (p <0.0001) compared with toxin EIA. For patients with CDI, time to the first positive test result was shortest with PCR. For patients without CDI, a negative PCR, but not 2ST, was associated with 22% fewer CDI treatment days, compared with toxin EIA (p <0.0001). Compared with both toxin EIA and 2ST, PCR detected more CDI patients faster and with less frequent testing, and negative PCR results were associated with less empirical CDI treatment.

Predictors of decrease in ankle-brachial index among patients with diabetes mellitus

AIM

Screening for peripheral arterial disease, a complication among patients with diabetes, is performed by periodic assessment of ankle-brachial index. We aimed to study the degree of ankle-brachial index change over time and factors associated with significant change.

METHOD

We assessed difference between two ankle-brachial index measurements over time in a consecutive series of 82 patients with Type 2 diabetes. All patients had ankle-brachial index > 0.9 but ≤ 1.3 for the first measurement, and significant ankle-brachial index decrease was defined as a decrease of > 0.1 in the follow-up measurement compared with the baseline.

RESULTS

The mean follow-up duration was 27.6 (median 30.0) months. Significant ankle-brachial index decrease was seen in 20.7% of patients, including 5% with follow-up ankle-brachial index of ≤ 0.9, consistent with the diagnosis of peripheral arterial disease. After adjusting for age and gender, higher baseline HbA(1c) and serum creatinine levels, increase in follow-up serum LDL cholesterol levels compared with baseline and history of retinopathy were predictors of significant ankle-brachial index decrease.

CONCLUSIONS

Our study suggests that, within two years, one in five patients with diabetes and a normal ankle-brachial index may have significant progression of peripheral arterial disease. Annual ankle-brachial index assessment and better control of hyperlipidaemia may thus be required for at-risk patients with poor glycaemic control, renal impairment and retinopathy.

BCR/ABL and IL-3 activate Rap1 to stimulate the B-Raf/MEK/Erk and Akt signaling pathways and to regulate proliferation, apoptosis, and adhesion

The Ras family small GTPase Rap1 is activated by hematopoietic cytokines, such as interleukin (IL)-3, to induce beta1 integrin-mediated cell adhesion or by the BCR/ABL fusion tyrosine kinase to stimulate the MEK/Erk signaling pathway. Here, we demonstrate that the abrogation of Rap1 activation by SPA-1, a Rap1-specific GAP, inhibits activation of B-Raf, MEK, Erk, and Akt in a murine hematopoietic cell line, Ton.B210, stimulated with IL-3 or inducibly expressing BCR/ABL. Furthermore, Rap1 inactivation had an inhibitory effects on proliferation and survival of Ton.B210 cells, which were more remarkable when cells were stimulated by BCR/ABL than by IL-3. Induction of BCR/ABL expression increased adhesion of Ton.B210 cells to fibronectin in a manner at least partly dependent on its kinase activity, and Rap1 inhibition by SPA-1 partially inhibited BCR/ABL-induced adhesion of cells. Thus, IL-3- or BCR/ABL-induced activation of Rap1 may play important roles in regulation of cell proliferation and survival through activation of the B-Raf/MEK/Erk and Akt signaling pathways and in induction of integrin-mediated cell adhesion. Furthermore, as compared with IL-3, BCR/ABL is more dependent on Rap1-mediated signaling to induce cell proliferation and survival and, thus, Rap1 may represent an attractive target for novel therapies for leukemias caused by BCR/ABL.

Nanofluidic channels fabrication and manipulation of DNA molecules

Nanofluidic channel arrays, which have a width of about 40 nm, depth of 60 nm and length of 50 mum, were created using a focused-ion-beam milling instrument on a silicon nitride film swiftly and exactly, as is necessary. Stained -DNA molecules were put inside these sub-100 nm conduits by capillary force and they were stretched and transferred along these conduits, which were dealt with activating reagent Brij aqueous solution in advance. The movements of DNA molecules in these channels were discussed. These nano-structure channels may be useful in the study and analysis of the statics as well as the dynamics of single biomolecules.

A strict-late viral promoter is a strong tumor-specific promoter in the context of an oncolytic herpes simplex virus

Confinement of transgene expression to target cells is highly desirable in gene therapy. Current strategies of transcriptional targeting to tumors usually rely on tissue-specific promoters to control gene expression. However, such promoters generally have much lower activity than the constitutive viral promoters. We have explored an alternative approach, using a strict-late viral promoter (UL38p) in the context of an oncolytic herpes simplex virus (HSV) for tumor-selective gene expression. As with many DNA viruses, the genomic transcription of HSV is a tightly regulated molecular cascade in which early and late phases of gene expression are separated by viral DNA replication. In particular, some of the late transcripts are categorized as strict-late, whose expression depends rigorously on the initiation of viral DNA replication. Our in vitro and in vivo characterization showed that in normal nondividing cells, where the oncolytic HSV has limited ability to replicate, the UL38p has minimal activity. However, in tumor or cycling cells where the virus can fully replicate, transgene expression from UL38p was almost as high as from the cytomegalovirus immediate-early promoter. These results suggest that delivery of therapeutic genes driven by UL38p through an oncolytic HSV may be an effective approach to gene therapy for malignant diseases.

Emergency department asthma: compliance with an evidence-based management algorithm

BACKGROUND

Recent surveys in emergency medicine departments show inadequacies in many aspects of acute asthma management.

OBJECTIVE

The objective of this study was to evaluate the adherence to management algorithm for acute asthma in the emergency department which focused on evidence-based treatment steps rather than documentation and patient classification.

METHODS

A retrospective audit of consecutive adult patients with acute exacerbations of asthma in the emergency medicine department of a university hospital managed in the context of a clinical algorithm.

RESULTS

We collated information from 344 episodes of acute asthma (94% of total) over a 4-month period. The first-line treatment was nebulised bronchodilators in 97%, combination of salbutamol and ipratropium bromide in 93% and the combination in recommended dosages in 87%. Systemic corticosteroid treatment was administered to 82% of patients. A further course of systemic corticosteroid was prescribed at discharge for 94% of patients. Overall, 93% of patients received some form of systemic corticosteroid treatment. The admission rate was 35.2%, and was significantly higher in women and the elderly. Of those who were admitted, 46.2% received > or = 3 nebulised treatments and 69% received intravenous hydrocortisone.

CONCLUSIONS

In the management of acute asthma, we found excellent compliance with specific treatment steps based upon clinical evidence. However, adherence to second-line treatment was less satisfactory. Nevertheless, whenever second-line treatment was complied with, reasonable outcomes were achieved. It may be more appropriate to emphasise evidence-based treatment rather than extensive documentation.

Human esophageal cancer cell death mediated by apoptosis-inducing nucleosides from CD57+HLA-DRbright natural suppressor cell line

We approached the induction of apoptosis in human esophageal cancer cells (T.Tn) by apoptosis-inducing nucleosides (AINs) from CD57+HLA-DRbright-natural suppressor (57.DR-NS) cell line originated in decidua. The 57.DR-NS cells generated apoptosis in T.Tn cells by AINs released into the cultures. We isolated a series of AINs by high performance liquid chromatography (HPLC) from 57.DR-NS cell culture fluids. Each AIN and its mixture induced apoptotic cell death in T.Tn cells, detected by DNA fragmentation in agarose gels, terminal deoxynucleotide transferase mediated dUTP-nick end labeling (TUNEL) method and accumulation of sub-G1 DNA content with flow cytometry. Furthermore, we found the occurrence of DNA strand breaks followed by the activation of caspase-3 during AINs-induced apoptosis in T.Tn cells. Thus, we validated that AINs could induce apoptosis in T.Tn cells mediated through DNA strand breaks and activation of caspase-3.

Gene expression of inducible nitric oxide synthase in injured spinal cord tissue

OBJECTIVE

To investigate gene expression of inducible nitric oxide synthase (iNOS) in injured spinal cord tissue of rats.

METHODS

Thirty-six adult Sprague-Dawley rats were divided randomly into six groups: a normal group and five injury groups, six animals in ea ch group. Animals in the injury groups were killed at 2, 6, 12, 24, 48 hours after injury, respectively. A compression injury model of spinal cord was established according to Nystrom B et al, and gene expression of iNOS in spinal cord tissue was examined by means of reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Gene expression of iNOS was not detectable in normal spinal cord tissue but was seen in the injury groups. The expression was gradually up -regulated, reaching the maximum at 24 hours. The expression at 48 hours began to decrease but was still significantly higher than that at 2 hours.

CONCLUSIONS

iNOS is not involved in the normal physiological activities of spinal cord. Expression of iNOS is up-regulated in spinal cord tissue in response to injury and the up-regulation exists mainly in the late stage after injury. Over-expression of iNOS may contribute to the l ate injury of spinal cord.

[Application of rapid detection for Mycobacterium tuberculosis with phage splitting assay]

OBJECTIVE

To study the significance of rapid identification for Mycobacterium tuberculosis with phage splitting assay.

METHODS

Strains of Mycobacterium tuberculosis, non-tuberculosis mycobacterium, non-mycobacterium and samples of sputum with pulmonary tuberculosis were rapidly detected by phage spot technique.

RESULTS

The strains of Mycobacterium tuberculosis H37Rv, bovis and africanum were all positive. The results of 10 strains of non-tuberculosis mycobacterium and 7 strains of non-mycobacterium were negative. All of 30 clinical isolates from the patients of the pulmonary tuberculosis were positive. 19 of 20 sputum specimen of pulmonary tuberculosis, which were all positive detected by smear and culture, were positive. There were 15 specimen positive in 21 sputum with negative tested by smear and positive by culture. Besides, 5 of 19 sputum specimen with negative by smear and culture were positive detected by this method.

CONCLUSION

The phage splitting assay can be used for rapid identification of Mycobacterium tuberculosis, which possesses high specificity and sensitivity for detection of Mycobacterium tuberculosis in sputum specimen.

Decontamination issues for chemical and biological warfare agents: how clean is clean enough?

The objective of this assessment is to determine what level of cleanup will be required to meet regulatory and stakeholder needs in the case of a chemical and/or biological incident at a civilian facility. A literature review for selected, potential chemical and biological warfare agents shows that dose information is often lacking or controversial. Environmental regulatory limits or other industrial health guidelines that could be used to help establish cleanup concentration levels for such agents are generally unavailable or not applicable for a public setting. Although dose information, cleanup criteria, and decontamination protocols all present challenges to effective planning, several decontamination approaches are available. Such approaches should be combined with risk-informed decision making to establish reasonable cleanup goals for protecting health, property, and resources. Key issues during a risk assessment are to determine exactly what constitutes a safety hazard and whether decontamination is necessary or not for a particular scenario. An important conclusion is that cleanup criteria are site dependent and stakeholder specific. The results of a modeling exercise for two outdoor scenarios are presented to reinforce this conclusion. Public perception of risk to health, public acceptance of recommendations based on scientific criteria, political support, time constraints, and economic concerns must all be addressed in the context of a specific scenario to yield effective and acceptable decontamination.

[Taxol-induced apoptosis in Jurkat T cell lymphoma cell line and its molecular mechanisms]

OBJECTIVE

To observe whether antimicrotubular drug taxol can induce apoptosis in Jurkat T cell lymphoma cell line and the role of bcl-2 gene family in this process.

METHODS

Different concentrations of taxol were used to treat Jurkat cells. Cell morphology was observed under light and electron microscope. Flow cytometry and electrophoresis were used to analyze DNA contents and DNA fragments. bcl-2 gene family proteins and mRNAs were studied by immunohistochemistry and semi-quantitative RT-PCR technique.

RESULTS

Taxol could inhibit Jurkat cell growth. Within a certain range of treating time and dose, cells were induced apoptosis with a time and dose related manner. The expressions of bax protein and mRNA were increased and bcl-x(s) mRNA became detectable after taxol treatment.

CONCLUSION

Taxol can specifically induce Jurkat cell apoptosis. It might provide a theoretical basis for clinical treatment and a good model for studying apoptotic gene modulation. Bax and bcl-x(s) participate in the taxol induced apoptosis of Jurkat cells.

[Studies on the toxicity of polymer of glycolide and lactide(PLGA) and the anti-fertility effect of levonorgestrel(LNG)]

PLGA(9:1), a chemical degraded from biomaterials, has been subjected to the tests of acute toxicity, irritations on conjunctiva and muscle, haemolysis in vitro and allergic reaction of mice and rats. The anti-fertility effect of PLGA-LNG microphere composite on the same animals also has been tested. The studies demonstrated that PLGA had fine biological compatibility without side effects such as toxicity, irritations on conjunctiva and muscle, pyrogenicity, haemolysis in vitro and allergic reaction. The contraception period of mice lasted 11.5, 34.6 and 81.2 days respectively after the subcutaneous (s.c.) injection of PLGA-LNG microphere which contains LNG 5, 10 and 20 mg/kg separately. The intramuscular(i.m.) injection of PLGA-LNG microphere containing LNG 13.6, 19.8 and 30 mg/kg respectively could keep the estrus of rats supressed for 76.3, 104.1 and 131.8 days. The injections of PLGA-LNG microphere through s.c. or i.m. showed more significant effects than the same dosages of PLGA-LNG micro-crystal. These results suggest that PLGA-LNG microphere injection has long-term anti-fertility effect.

Diet survey of two cultural groups in a coastal British Columbia community

OBJECTIVES

As part of a larger study of polychlorinated dibenzodioxin (PCDD) and dibenzofuran (PCDF) pollution, to describe and compare Aboriginal and non-Aboriginal residents' recalled diets.

METHODS

We surveyed a stratified random sample aged 25 to 64 years: forest products mill employees (n = 84), Aboriginal reserve residents (n = 78), and other residents (n = 80). We administered a questionnaire on intake of fish/seafood, wild game and plants, domesticated animal meat and eggs, dairy products, vegetable oils and cereals; age, gender, childbearing, lactation, residence and smoking. We measured height and weight.

RESULTS

Reserve residents ate less seafood, but more fish roe, eulachon grease, smoked salmon, clams and sea urchins, more deer organs, hamburger meat, pork, fried chicken, and hot-dogs, but less rabbit, beef steaks/roasts, high-fibre cereals, potato chips, bread, cheese and milk.

CONCLUSIONS

We cannot yet quantify PCDD and PCDF intakes. The wild food consumption data are unique and may be useful for risk assessments in the target population and similar communities.

New concepts and advances of immobilization of long bones

OBJECTIVE

To present some new concepts in the treatment of fractures and bone defects of long bones with internal fixation.

METHODS

Animal experiments, mechanical tests and clinical analyses were done.

RESULTS AND CONCLUSIONS

Reduction of fracture should be perfect, bone defect can be reconstructed by intramedullary and extramedullary bone graft. Relatively rigid fixation at the early stage and elastic fixation at the later stage are beneficial not only for fracture healing, but also for bone remodeling. In order to avoid complications including non-union, immobilization syndrome of the bone and joint, and implant failure, radiographs should be taken periodically; if there is any bone resorption, weight-bearing should be restricted.

The relationship of lead in soil to lead in blood and implications for standard setting

As part of a soil lead regulation process, this review was conducted to determine the association between lead in soil and established human health effects of lead or validated biomarkers of lead exposure. We reviewed only studies where soil exposure could be distinguished from other sources of lead and whose design could reasonably be used to infer a causal relationship between soil lead and either biomarkers or health effects. No such studies of health effects were found. Studies describing a quantitative relationship between soil lead and blood lead did meet our criteria: 22 cross-sectional studies in areas with polluted soil; and three prospective studies of soil lead pollution abatement trials. The cross-sectional studies indicated that, compared to children exposed to soil lead levels of 100 ppm, those exposed to levels of 1000 ppm had mean blood lead concentrations 1.10-1.86 times higher and those exposed to soil lead levels of 2000 ppm had blood lead concentrations 1.13-2.25 times higher. The prospective studies showed effects within the ranges predicted by the cross-sectional studies. Differences in results between studies were surprisingly modest and likely explainable by random sampling error, different explanatory variables included in data analyses and differences in methods of measuring lead in environmental specimens.

High dose baclofen is neuroprotective but also causes intracerebral hemorrhage: a quantal bioassay study using the intraluminal suture occlusion method

Agonists of the GABA-A receptor are neuroprotective after experimental stroke, but studies of GABA-B agonists have contradicted each other. To further investigate whether GABA-B agonists may be neuroprotective, we devised a quantal bioassay using the intraluminal occlusion method of inducing reversible cerebral ischemia. Subjects underwent middle cerebral artery occlusion for varying amounts of time, ranging from 5 to 90 min. Behavioral outcome was measured 48 h later with a quantal observational scale: score of abnormal given for any one of asymmetric forepaw flexion on tail lift, asymmetric grip, circling, reduced exploration, seizures, or death. To the grouped response data the logistic equation was used to find the ED50, the duration of occlusion that caused one-half of the subjects to be abnormal. To find the potency ratio for each drug, we divided the ED50 for treatment by that for vehicle. We administered baclofen, a GABA-B agonist, intraperitoneally 5 min after the onset ofischemia. Baclofen (20 mg/kg) was neuroprotective (potency ratio of 3.0, P < 0.05), but a lower dose (10 mg/kg) was not. However, both doses of baclofen caused significantly more intracerebral hemorrhages than control. In awake animals, both baclofen doses caused significant increases in mean arterial pressure, but no changes in other cardiorespiratory variables. The glutamate antagonist MK-801, the GABA-A agonist muscimol, and hypothermia were all protective using the bioassay (potency ratios ranging from 1.5 to 3.0). We conclude that although baclofen (20 mg/kg) may be neuroprotective, its utility is complicated by postischemic hypertension and cerebral hemorrhages.

Blood lead levels in children aged 24 to 36 months in Vancouver

OBJECTIVES

To determine the blood lead levels in children and to identify risk factors for elevated levels.

DESIGN

Cross-sectional study.

SETTING

Vancouver.

PARTICIPANTS

Random sample of children aged 24 to 36 months, born and still resident in Vancouver. The sample was stratified proportionally by the median annual family income in the census tract where each family resided.

OUTCOME MEASURES

Blood lead levels and risk factors for elevated blood lead levels, determined from a questionnaire administered to parents.

RESULTS

Of the children in the sample, 42% (178/422) were ineligible or could not be located. Of the remaining children, 73% (177/244) participated and adequate blood specimens were obtained from 172. The mean blood lead level was 0.29 mumol/L (standard deviation 0.13 mumol/L). (A blood lead level of 1 mumol/L is equivalent to 20.7 micrograms/dL.) The lowest level was 0.06 mumol/L, and the highest was 0.85 mumol/L. Of children with adequate samples, 8.1% (14/172) had blood lead levels of 0.48 mumol/L or higher, and 0.6% (1/172) had a level higher than 0.72 mumol/L. The logarithms of the levels were normally distributed, with a geometric mean (GM) of 0.26 mumol/L (geometric standard deviation 1.56). Of approximately 70 possible predictors of blood lead levels analysed, those that showed a statistically significant association (p < 0.05) with increased blood lead levels were soldering performed in the home as part of an electronics hobby (GM blood lead level 0.34 mumol/L, 95% confidence interval [CI] 0.27 to 0.39 mumol/L), aboriginal heritage (GM blood lead level 0.33 mumol/L, 95% CI 0.28 to 0.39 mumol/L), dwelling built before 1921 (GM blood lead level 0.32 mumol/L, 95% CI 0.28 to 0.37 mumol/L), age of water service connection to dwelling (predicted blood lead level 0.00087 mumol/L [95% CI 0.00005 to 0.00169 mumol/L] higher per year since service connection) and decreased stature (predicted blood lead level 0.018 mumol/L [95% CI 0.0353 to 0.0015 mumol/L] higher for every standard deviation below the age-specific mean height).

CONCLUSIONS

This study found much lower blood lead levels in children than those found in previous Canadian studies. The authors believe that this result is not an artefact due to differences in population sampling or methods of collection of blood specimens. The study showed no clear risk factors for elevated blood lead levels: although a few factors had a statistically significant association with increased blood lead levels, the differences in levels were small and unimportant.

New restriction endonuclease CviRI cleaves DNA at TG/CA sequences

A new type II restriction endonuclease, CviRI, was isolated from virus XZ-6E infected chlorella cells. CviRI is the first restriction endonuclease to recognize the sequence 5'-TGCA-3' and cleaves DNA between the G and C residues to produce blunt-end termini. Methylation of the adenine or cytosine in 5'-TGCA-3' sequences prevents CviRI cleavage. Due to its sequence specificity, CviRI may be especially useful for detecting mutant alleles of many heritable human genetic diseases.

Strategies for determining occupational exposures in risk assessments: a review and a proposal for assessing fungicide exposures in the lumber industry

To select an exposure monitoring protocol for assessing the occupational risk of fungicides in the lumber industry, the main strategies for determining exposures for risk assessment were reviewed. A survey of lumber industry work sites using fungicides observed the methods of application and opportunities for exposure. In addition, a review of existing measurement data was done. These investigations indicated that fungicide application techniques and process locations were varied from site to site, such that it would be extremely difficult to select a few representative locations for quasi-experimental studies, as is usually done in agricultural pesticide exposure assessment. Existing measurement data mainly describe exposures to fungicides no longer in use, and do not cover the range of application techniques or process technology observed in the survey. A probability sample of the exposed population was therefore proposed.

Liquid hybridization analysis of TSH receptor mRNA in normal and abnormal human thyroid tissues

Radiolabeled human TSH receptor (hTSHR) cRNA probes encoding nucleotides 37-2298 and 37-209, with unlabeled sense RNA control segments, were used in a liquid hybridization assay and found to be highly specific and sensitive enabling detection of 0.5 fmol of hTSHR mRNA. Using normal human thyroid monolayer cell cultures we calculated that the average number of TSHR mRNA transcripts was 95 +/- 5 per cell under in vitro basal conditions. We found no significant difference between the hTSHR mRNA concentrations of intact normal human thyroid tissue (n = 4) and specimens from patients with multinodular goiter (n = 5) and Graves' disease thyroid tissues (n = 5) (23.0, 25.2, and 27.6 fmol of hTSHR and mRNA/mg total cellular RNA, respectively). However, there was a relative deficiency of hTSHR mRNA in some samples of thyroid papillary carcinoma tissue (n = 5) (12 fmol of hTSHR mRNA/mg total RNA, p < 0.05). The hTSHR 37-2298 probe was fully protected in normal and abnormal thyroid tissues, consistent with the absence of large deletions or insertions in the hTSHR mRNA transcripts but additional bands were present, consistent with the production of splicing variants.

Immunomodulatory activity of a novel nucleoside, 7-thia-8-oxoguanosine. II. Characterization of induced effector cells and the mechanism of induction

In a preceding paper we characterized the in vivo and in vitro induction of cytotoxic effector cells elicited by a novel synthetic immuno-stimulator 7-thia-8-oxoguanosine (7T8OG)2. In the present study we further characterized the cells responsible for the induced cytotoxicity and the mechanisms together with the lymphokines mediating the immunological response to 7T8OG. Removal of macrophages from 7T8OG activated spleen cell suspensions by various methods resulted in a significant increase in cytotoxicity to YAC-1 targets. 7T8OG induced effectors did not exert cytotoxic effect on macrophage sensitive P815 target cells. In vivo activated effectors when incubated with anti-asialo-GM1 antibody plus complement lost completely their ability to lyse YAC-1 targets. Together, these findings indicate that the 7T8OG induced effector cells are not macrophage like. Spleen cells from nude mice were readily activated by 7T8OG. The induced effectors were resistant to complement mediated lysis using anti-L3T4, anti-Lyt1 or anti-Lyt2 antibodies. Pretreatment of spleen cells with macrophage depleting agents both, in vitro and in vivo and subsequent activation of cells by 7T8OG resulted in effectors with reduced cytotoxicity. When injected in vivo, 7T8OG induced strong IFN production which paralelled the kinetics of NK cell activation. Furthermore, antibodies to alpha & beta-IFN but not to gamma-IFN diminished the induction of the cytotoxic activity. Although these findings suggest that activation of NK cells by 7T8OG is most likely to be mediated by alpha & beta-IFN involvement of other cytokines can not be ruled out.

Successful immunotherapy of murine melanoma metastases with 7-thia-8-oxoguanosine

We have recently reported that a synthetic nucleoside, 7-thia-8-oxoguanosine (7T8OG) is a potent activator of a number of effectors which are involved in anti-tumor immune responses. 7T8OG was found to induce interferon (IFN) production, to activate asialo-GM1 positive (AGM+1) killer cells, and to enhance specific antibody responses. In the present study, we investigated the effect of 7T8OG on growth of the murine pulmonary B16 melanoma and on formation of metastases. C57BL/6 mice were injected i.p. with 50-150 mg/kg 7T8OG before or after i.v. inoculation of B16 melanoma tumor cells, and 17-19 days after tumor inoculation, the number of metastases in the lungs were counted. 7T8OG given systemically in a single or a divided dose 24 h prior to the challenge of tumor cells reduced the number of lung tumor metastases by 89-99% which is highly significant as compared to untreated control (P less than 0.001). Occasional extra pulmonary tumor growth in the thoracic cavity and neck lymph node was also completely inhibited. The reduction in the number of tumor nodules was dose dependent. A single dose of 150 mg/kg of 7T8OG was also effective in inhibiting the growth of 3-5 day old metastatic tumors. The cytotoxic activity of killer cells induced in vivo by 7T8OG was completely abolished by in vitro treatment of cells with anti-AGM1 antibody plus complement. Administration of anti-AGM1 antibody following the 7T8OG treatment completely abrogated the anti-tumor effect of 7T8OG, resulting in a massive increase in the number of tumor foci in the lungs. Administration of carageenan or silica followed by injection of 7T8OG caused a significant increase (P less than 0.01) in the number of pulmonary tumor nodules compared to treatment with 7T8OG only. These findings indicate that activated macrophages or perhaps their cytokine (tumor necrosis factor) also contribute to the host tumor defense by 7T8OG.

Potentiation of the efficacy of murine L1210 leukemia vaccine by a novel immunostimulator 7-thia-8-oxoguanosine: increased survival after immunization with vaccine plus 7-thia-8-oxoguanosine

We have investigated the ability of a novel immunopotentiator, 7-thia-8-oxoguanosine (7T8OG) to increase the efficacy of a weakly immunogenic murine L1210 leukemia vaccine. The vaccine was prepared by irradiating L1210 leukemia cells in a cesium source with a total of 6000-R dose. DBA/2 mice were treated with 150 mg/kg 7T8OG and/or with vaccine consisting of 10(7) irradiated cells. In combination therapy, mice first received the vaccine and then were injected with 75 mg/kg 7T8OG 2 h and 4 h after vaccination. One week after the last treatment all mice were inoculated with 10(4) live leukemia cells intraperitoneally. Control, untreated mice (n = 66) injected with 10(4) live leukemia cells had a mean survival time +/- standard error of 10.5 +/- 0.2 days. Treating mice (n = 66) with one, two or three doses of 7T8OG administered i.p. 1 week apart did not increase survival (mean survival time = 10.7 days). Mice immunized with one, two or three doses of vaccine had 14.5 +/- 1.1, 45.4 +/- 6.2 and 68.3 +/- 10.6 days mean survival, respectively. 7T8OG-stimulated vaccination increased the survival dramatically. The best survival was noted when the mice were treated with 2x (vaccine + 7T8OG). Immunization of mice (n = 30) with this treatment regimen increased the mean survival to 156 +/- 10.0 days. Over 90% of mice that were treated this way had a cumulative survival time greater than 160 days. In contrast, only 12% of the mice immunized twice with the leukemia vaccine alone survived over 160 days. These results suggest a rationale for the use of this immuno-potentiator with various vaccines for a more effective immunization.

Immunoenhancing properties and antiviral activity of 7-deazaguanosine in mice

The nucleotide analog 7-deazaguanosine has not previously been reported to possess biological (antiviral or antitumor) properties in cell culture or in vivo. Up to 10(5) U of interferon per ml was detected in mouse sera 1 to 4 h following oral (200-mg/kg of body weight) and intraperitoneal (50-mg/kg) doses of the compound. 7-Deazaguanosine also caused significant activation of natural killer and phagocytic cells but did not augment T- and B-cell blastogenesis. Intraperitoneal treatments of 50, 100, and 200 mg/kg/day administered 24 and 18 h before virus inoculation were highly protective in mice inoculated with lethal doses of Semliki Forest or San Angelo viruses. Less but still significant survivor increases were evident in treated mice infected with banzi or encephalomyocarditis viruses. In most cases, the degree of antiviral activity was similar to that exhibited by the biological response modifier 7-thia-8-oxoguanosine. 7-Thia-8-oxoguanosine was more potent than 7-deazaguanosine against encephalomyocarditis virus in mice, however. Oral efficacy was achieved with 7-deazaguanosine treatments of greater than or equal to 100 mg/kg against all virus infections, whereas 7-thia-8-oxoguanosine is reported to be devoid of oral activity in rodents. Thus, 7-deazaguanosine represents the first reported orally active nucleoside biological response modifier exhibiting broad-spectrum antiviral activity against particular types of RNA viruses.