Algorithmic robustness to preferred orientations in single particle analysis by CryoEM.

The presence of preferred orientations in single particle analysis (SPA) by cryo-Electron Microscopy (cryoEM) is currently one of the hurdles preventing many structural analyses from yielding high-resolution structures. Although the existence of preferred orientations is mostly related to the grid preparation, in this technical note, we show that some image processing algorithms used for angular assignment and three-dimensional (3D) reconstruction are more robust than others to these detrimental conditions. We exemplify this argument with three different data sets in which the presence of preferred orientations hindered achieving a 3D reconstruction without artifacts or, even worse, a 3D reconstruction could never be achieved.

Parathyroidectomy slows renal function decline in patients with primary hyperparathyroidism.

PURPOSE: Primary hyperparathyroidism has deleterious effects on health and causes nephrolithiasis and osteoporosis. However, it remains unclear whether parathyroidectomy benefits kidney function among patients with primary hyperparathyroidism. METHODS: In this retrospective study, patients with primary hyperparathyroidism receiving parathyroidectomy in a tertiary medical center between 2003 and 2017 were followed up until December 31 2017, death, or requiring renal replacement therapy. Impact of parathyroidectomy on kidney function was examined using longitudinal estimated glomerular filtration rate (eGFR) change scales: single, average, absolute difference, percent change, annual decline rate, and slope. We applied linear mixed-effect model to determine the effect of parathyroidectomy on kidney function. RESULTS: During study period, 167 patients with primary hyperparathyroidism were identified from 498 parathyroidectomized patients, and finally, 27 patients fulfilled our stringent criteria. Median follow-up duration was 1.50 years (interquartile range 1.05-1.81) before surgery and 2.47 years (1.37-6.43) after surgery. Although parathyroidectomy did not affect amount of proteinuria and distribution of eGFR, parathyroidectomy significantly slowed decline rate of eGFR compared with that before surgery (- 1.67 versus - 2.73 mL/min/1.73 m2/year, p < 0.001). More importantly, parathyroidectomy made more beneficial effects on kidney function in patients with age < 65 years and those without chronic kidney disease or hypertension. CONCLUSIONS: Our study showed that parathyroidectomy slows renal function decline irrespective of age or comorbidities, which offers novel insight into the revision of guidelines for surgical indications in primary hyperparathyroidism. Given small sample size, further large-scale controlled studies are warranted to confirm our findings.

Survey on common reference intervals for general chemistry analytes in Hong Kong.

INTRODUCTION: Reference intervals (RIs) are essential tool for proper interpretation of results. There is a global trend towards implementing common RIs to avoid confusion and enhance patient management across different laboratories. However, local practices with respect to RIs lack harmonisation. METHODS: We have conducted the first local survey regarding RIs for 14 general chemistry analytes in 10 chemical pathology laboratories that employ four different analytical platforms (Abbott Architect, Beckman Coulter AU, Roche Cobas, and Siemens Dimension EXL). Analytical bias was assessed by an inter-laboratory results comparison of external quality assurance programmes. RESULTS: Sufficient inter-laboratory and inter-platform agreement regarding the 10 analytes (albumin, alanine aminotransferase, aspartate aminotransferase, chloride, gamma-glutamyl transferase, phosphate, potassium, sodium, total protein, and urea) were demonstrated. However, the RIs were heterogeneous across all laboratories, with percentage differences of the upper RI value of up to 47% for aspartate aminotransferase (absolute difference of 16 U/L), 29% for urea (1.8 mmol/L), and 18% for potassium (0.8 mmol/L). The percentage difference between lower RI values was up to 24% for urea (0.6 mmol/L), 22% for phosphate (0.16 mmol/L), and 8% for total protein (5 g/L). The coefficients of variation of the upper RI values of potassium and sodium were 1.2 times and 1.0 times of their corresponding between-subject biological variation, respectively, representing unnecessary variations that are overlooked and unchecked in current practice. CONCLUSIONS: We recommend the use of common RIs for general chemistry analytes in Hong Kong to prevent interpreter confusion, improve electronic data transfer, and unite laboratory practice. This is the first local study on this topic, and our data can lay the groundwork for increasing harmonisation of RIs across more laboratory tests.

Epidemiological characteristics and associated factors of acute hepatitis A outbreak among HIV-coinfected men who have sex with men in Taiwan, June 2015-December 2016.

In Taiwan, an outbreak of acute hepatitis A (AHA) infection has been identified since June 2015. Approximately half of the cases occurred in HIV-infected men who have sex with men (MSM). We used the Taiwan Centers for Disease Control (TCDC)-operated National Disease Surveillance Systems (NDSS) to identify the incidence of AHA during 2011-2016. Between June 2015 and December 2016, a total of 1268 AHA cases were documented, and 601 cases (47.4%) were co-infected with HIV; the majority of whom were MSM (98.4%). Each AHA case was matched to two HIV-infected controls without AHA reported in the NDSS on age (± 5 years), risk factor of HIV infection, HIV diagnosis date (± 30 days) and county/city of residence at HIV diagnosis. Three hundred forty-three HIV/AHA cases were matched to 686 controls. In multivariable conditional logistic regression analysis, a previous gonorrhoea (adjusted OR=1.77, 95% CI 1.16-2.70) and recent (aOR=6.77, 95% CI 4.34-10.55) or remote syphilis report (aOR=3.56, 95% CI 2.48-5.13) were independently associated with AHA. The epidemic persisted till December 2016, and the cases with a new diagnosis of HIV infection after AHA (28/301, 9.3%) increased after July 2016 (P = .001). HIV/AHA cases were centralized in northern and central metropolitan areas and HIV-infected MSM with a recent history of sexually transmitted diseases in Taiwan. We recommend surveillance of associated behavioural and virologic characteristics and HAV counselling and testing for HIV-infected men.

Association between microstructural integrity of frontostriatal tracts and school functioning: ADHD symptoms and executive function as mediators.

BACKGROUND: Deficits in executive function (EF), impaired school functioning and altered white matter integrity in frontostriatal networks have been associated with attention-deficit/hyperactivity disorder (ADHD). However, relationships between impairments in these areas are unclear. Using a sample of youths with and without ADHD, this study examined the association between microstructural integrity of frontostriatal tracts and school dysfunction and the mediating roles of EF and ADHD symptoms in this association. METHOD: The sample included 32 Taiwanese youths with ADHD and 32 age-, sex-, handedness- and IQ-matched typically-developing (TD) youths. Participants were assessed using psychiatric interviews, parent reports on ADHD symptoms and school functioning, and EF measures from the Cambridge Neuropsychological Test Automated Battery (CANTAB). The frontostriatal tracts were reconstructed by diffusion spectrum imaging (DSI) tractography and were subdivided into four functionally distinct segments: caudate-dorsolateral, caudate-medial prefrontal, caudate-orbitofrontal and caudate-ventrolateral tracts. RESULTS: Youths with ADHD, relative to TD youths, showed altered white matter integrity in all four bilateral pairs of frontostriatal tracts (decreased general fractional anisotropy, GFA), had poor attention, vigilance and response inhibition, and showed impaired school functioning. Altered microstructural integrity in frontostriatal tracts was significantly associated with school dysfunction, which was mediated by EF measures of attention/vigilance and response inhibition in addition to inattention and hyperactivity symptoms. CONCLUSIONS: Our findings demonstrate an association between white matter integrity in the frontostriatal networks and school functioning and suggest that EF deficits and ADHD symptoms may be the mediating mechanisms for this association. Future research is needed to test the directionality and specificity of this finding.

Surveillance of avian influenza A(H7N9) virus infection in humans and detection of the first imported human case in Taiwan, 3 April to 10 May 2013.

On 3 April 2013, suspected and confirmed cases of influenza A(H7N9) virus infection became notifiable in the primary care sector in Taiwan, and detection of the virus became part of the surveillance of severe community-acquired pneumonia. On 24 April, the first imported case, reported through both surveillance systems, was confirmed in a man returning from China by sequencing from endotracheal aspirates after two negative throat swabs. Three of 139 contacts were ill and tested influenza A(H7N9)-negative.

Yokenella regensburgei in an immunocompromised host: a case report and review of the literature.

Yokenella regensburgei belongs to the Enterobacteriaceae and shares some biochemical characteristics with Hafnia alvei. A few case reports have suggested that it is an opportunistic pathogen, but there is no strong evidence to support its clinical importance. Until recently, it was difficult to accurately differentiate between Y. regensburgei and H. alvei by use of routine identification techniques. Here, we present a case of soft tissue infection and bacteremia caused by Y. regensburgei, which was successfully treated by intravenous administration of ceftriaxone for three weeks, and review the previous literature.

Regulation of cytokine expression in human plasmacytoid dendritic cells by prostaglandin I2 analogues.

Plasmacytoid dendritic cells (pDCs) are critical in controlling adaptive immunity, but the mechanisms governing cytokine expression remain incompletely defined. Analogues of prostaglandin (PG)I(2), such as iloprost, can modulate functions of myeloid dendritic cells, but their involvement in the regulation of human pDCs remains unknown. To this end, the regulatory role of PGI(2) analogues on cytokine expression in pDCs was investigated. Circulating pDCs were magnetically sorted with BDCA-4 cell isolation kits from human peripheral blood mononuclear cells and treated with varying concentrations of iloprost with or without the addition of Toll-like receptor agonists, or an I prostanoid (IP) receptor antagonist, CAY10449. The levels of tumour necrosis factor (TNF)-alpha, interferon (IFN)-alpha and interleukin (IL)-10 were measured by ELISA. Iloprost induced IL-10 expression, but suppressed CpG oligodeoxynucleotide- (or imiquimod-) induced TNF-alpha and IFN-alpha production in pDCs. This effect was reversed by the addition of CAY10449. Forskolin, a cyclic adenosine monophosphate activator, conferred a similar modulating effect to that noted in iloprost-treated pDCs, although a higher concentration of forskolin was required to exert the same effect. Iloprost enhanced interleukin-10 and suppressed Toll-like receptor-mediated tumour necrosis factor-alpha and interferon-alpha production of human plasmacytoid dendritic cells via the I prostanoid receptor and, in part, the cyclic adenosine monophosphate pathway.

Aetiology of cavitary lung lesions in patients with HIV infection.

BACKGROUND: Although many studies have been carried out on pulmonary diseases in HIV-infected patients, studies specifically investigating the aetiologies of cavitary lung lesions are rare. METHODS: HIV-infected patients enrolled in a cohort study who presented with cavitary lung lesions by radiography were identified between June 1994 and March 2008. Medical records and radiological and microbiological data for these patients were retrospectively reviewed using a standardized case collection form. RESULTS: During the 14-year study period, 73 episodes of cavitary lung lesions were diagnosed in 66 of 1790 (3.7%) HIV-infected patients. At the diagnosis of cavitary lung lesions, the median CD4 count was 25 cells/microL (range 1-575 cells/microL). Eighty-one pathogens were considered causative, with fungi being the most common aetiology (42.0%), followed by bacteria (29.6%) and mycobacteria (25.9%). Of the fungal pneumonias, 19 (55.9%) were caused by Penicillium marneffei, 11 (32.4%) by Cryptococcus neoformans, two (5.9%) by Pneumocystis jirovecii, and two (5.9%) by Aspergillus species. During the study period, 11 of 205 patients (5.4%) who were diagnosed as having tuberculosis presented with cavitary lung lesions, compared with 19 of 36 patients (52.8%) with penicilliosis and 11 of 64 patients (17.2%) with cryptococcosis (P<0.0001). The median CD4 count of patients with cavitary lung lesions resulting from tuberculosis (115 cells/microL) was significantly higher than that of patients with cavitary lung lesions resulting from penicilliosis (4 cells/microL) and cryptococcosis (29.5 cells/microL). CONCLUSIONS: Our findings suggest that invasive infections attributable to endemic fungi were the leading cause of cavitary lung lesions among patients in the late stage of HIV infection, and were more common than infections attributable to bacteria and mycobacteria.

Risk factors for incident diabetes mellitus among HIV-infected patients receiving combination antiretroviral therapy in Taiwan: a case-control study.

OBJECTIVES: Recent studies suggest that patients with HIV infection are at increased risk for incident diabetes mellitus (DM). We investigated the incidence and risk factors of DM among HIV-infected patients receiving combination antiretroviral therapy (CART) in Taiwan. METHODS: Incident cases of DM were identified among HIV-infected patients at the National Taiwan University Hospital between 1993 and 2006. A retrospective case-control study was conducted after matching cases with controls for sex, age at HIV diagnosis, year of HIV diagnosis, mode of HIV transmission and baseline CD4 lymphocyte count. A multivariate analysis was performed to identify risk factors for incident DM among HIV-infected patients. RESULTS: In 824 HIV-infected patients eligible for analysis, 50 cases of incident DM were diagnosed, resulting in an incidence of 13.1 cases per 1000 person-years of follow-up. In total, 100 matched controls were identified. Risk factors for incident DM were a family history of DM [odds ratio (OR) 2.656; 95% confidence interval (CI) 1.209-5.834], exposure to zidovudine (OR 3.168; 95% CI 1.159-8.661) and current use of protease inhibitors (OR 2.528; 95% CI 1.186-5.389). CONCLUSIONS: Incident DM was associated with a family history of DM, exposure to zidovudine and current use of protease inhibitors in HIV-infected patients receiving CART in Taiwan.

Radiation therapy toxicity to the skin.

Radiation therapy has been integral to cancer patient care. The skin is an intentional and unintentional target of therapy, and is sensitive to the volume of normal tissue in the radiation therapy treatment field, daily treatment dose (fractionation), and total treatment dose. We must understand the relationship of these factors to patient outcome as we move toward hypofractionation treatment strategies (radiosurgery). Chemotherapy agents and prescription medications may influence therapy-associated sequelae. Understanding this may prevent significant injury and discomfort. This article reviews established platforms of radiation therapy and sequelae associated with skin therapy. Interactions with other agents and possible predisposition to sequelae are reviewed. Skin cancer resulting from treatment and disease processes associated with possible limited outcome are also reviewed.

Generic velpatasvir plus sofosbuvir for hepatitis C virus infection in patients with or without human immunodeficiency virus coinfection.

BACKGROUND: Data are limited regarding the effectiveness and safety of generic velpatasvir plus sofosbuvir (VEL/SOF) for hepatitis C virus (HCV) in patients with or without human immunodeficiency virus (HIV) coinfection. AIM: To evaluate the effectiveness and safety of generic VEL/SOF-based therapy for HCV infection in patients with or without HIV coinfection in Taiwan. METHODS: Sixty-nine HIV/HCV-coinfected and 159 HCV-monoinfected patients receiving 12 weeks of generic VEL/SOF with or without ribavirin (RBV) for HCV were prospectively enrolled. The anti-viral responses and the adverse events (AEs) were compared between the two groups. The characteristics potentially related to sustained virological response 12 weeks off therapy (SVR12 ) were analysed. RESULTS: The SVR12 was achieved in 67 HIV/HCV-coinfected patients (97.1%; 95% CI: 90.0%-99.2%) and in 156 HCV-monoinfected patients (98.1%; 95% CI: 94.6%-99.4%) receiving VEL/SOF-based therapy, respectively. The SVR12 rates were comparable between HIV/HCV-coinfected and HCV-monoinfected patients, regardless of pre-specified baseline characteristics. One hundred twenty-two (53.5%) and seven (3.1%) patients had baseline resistance-associated substitutions (RASs) in HCV NS5A and NS5B regions, but the SVR12 rates were not affected by the presence or absence of RASs. One (1.4%) and five (3.1%) patients in the HIV/HCV-coinfected and HCV-monoinfected groups had serious AEs. No patient died or discontinued treatment due to AEs. The eGFR remained stable throughout the course of treatment in HIV/HCV-coinfected patients receiving anti-retroviral therapy containing tenofovir disoproxil fumarate (TDF). CONCLUSIONS: Generic VEL/SOF-based therapy is well-tolerated and provides comparably high SVR12 rates for HCV infection in patients with and without HIV coinfection.

The effect of radiation therapy on normal tissue function.

As more patients are treated for their primary malignancy with cure or increased disease-free intervals, injury to normal tissues will become more detectable and an important endpoint for study. Future protocols will probably be modified based on toxicity endpoints. In Hodgkin's disease, current protocols use response-based treatment strategies to limit therapy. The objective is to provide the same level of tumor control and follow normal tissue endpoints for outcome analysis. DVH analysis has improved the ability to analyze endpoint data for normal tissues. These image-guided platforms will provide the infrastructure needed to continue efforts in improving the delivery of radiation therapy.

Evaluation of a new transcutaneous bilirubinometer in Chinese newborns.

OBJECTIVE: To evaluate the use of a new transcutaneous bilirubinometer (JM-103 Minolta Airshields) for detection of hyperbilirubinaemia in term or near-term healthy Chinese newborns. METHODS: Transcutaneous bilirubin (TcB) was used to screen for severe hyperbilirubinaemia in newborn infants. Blood was taken for total serum bilirubin (TSB) measurement if the initial TcB level was higher than the 40th centile in Bhutani's nomogram. Paired TcB and TSB results were then reviewed over 6 months. The correlation as well as the mean difference between the two methods were calculated. The clinical application of TcB with Bhutani's nomogram in the prediction of severe hyperbilirubinaemia in low-risk, medium-risk and high-risk thresholds for phototherapy was also analysed. RESULTS: 997 paired TcB and TSB measurements were evaluated in term or near-term newborns. TcB was significantly correlated with TSB, with a correlation coefficient of 0.83 (p<0.001). Their mean difference was 21.7 micromol/l (SD 21.2, p<0.001), with the 95% limits of agreement between -19.9 and 63.3 micromol/l. In both low-risk and medium-risk thresholds for phototherapy, using the 75th centile of Bhutani's nomogram as threshold, TcB could identify all cases and had a sensitivity and negative predictive value of 100% each, a specificity of 56% and positive predictive value of 23%. For high-risk cases, using the 75th centile as cut-off, the sensitivity and negative predictive value were reduced to 86.7% and 97.0%, respectively. CONCLUSION: An accurate point-of-care bilirubin analyser facilitates bilirubin screening and avoids unnecessary blood tests. Although using the transcutaneous bilirubinometer JM-103 might result in a significant difference between TcB and TSB measured in Chinese newborns, combining the use of TcB and the 75th centile in Bhutani's nomogram as the cut-off level can identify all cases of significant hyperbilirubinaemia.

The epidermal growth factor receptor is required to maintain the proliferative population in the basal compartment of epidermal tumors.

Previous studies using keratinocytes from epidermal growth factor receptor (EGFR)-deficient mice revealed that the EGFR is not required for papilloma formation initiated by a mutant rasHa gene, although the tumors that develop are very small (A. A. Dlugosz et aL, Cancer Res., 57: 3180-3188, 1997). The current study used a combination of bromodeoxyuridine pulse-chase, proliferating cell nuclear antigen distribution, and differentiation marker analysis to reveal the following: (a) the EGFR was required to maintain the proliferative population in the basal cell compartment of papillomas; (b) in the absence of EGFR, cycling tumor cells migrated into the suprabasal compartment and initiated the differentiation program prematurely; and (c) these changes were associated with cell cycle arrest. Further analysis of v-rasHa-transformed EGFR-deficient keratinocytes in vitro indicated that such cells migrated more on and attached less to extracellular matrix components. Together, these studies reveal that an essential function for the EGFR pathway in squamous tumors is to maintain a proliferative pool of basal cells and prevent premature terminal differentiation.

The worldwide spread of ciprofloxacin-resistant Shigella sonnei among HIV-infected men who have sex with men, Taiwan.

Ciprofloxacin-resistant shigellosis outbreaks among men who have sex with men (MSM) have not been reported in Asia. During 3 March to 6 May 2015, the Notifiable Disease Surveillance System detected nine non-imported Shigella sonnei infections among human immunodeficiency virus (HIV) -infected Taiwanese MSM. We conducted a molecular epidemiological investigation using a 1 : 5 matched case-control study and laboratory characterizations for the isolates. Of the nine patients, four reported engagement in oral-anal sex before illness onset. Shigellosis was associated with a syphilis report within 12 months (adjusted odds ratio (aOR) 8.6; 95% CI 1.05-70.3) and no HIV outpatient follow-up within 12 months (aOR 22.3; 95% CI 2.5-201). Shigella sonnei isolates from the nine patients were all ciprofloxacin-resistant and the resistance was associated with S83L and D87G mutations in gyrA and S80I mutation in parC. The nine outbreak isolates were discriminated into two closely related pulsed-field gel electrophoresis (PFGE) genotypes and seven 8-locus multilocus variable-number tandem repeat analysis (MLVA8) types that suggest multiple sources of infections for the outbreak and possible under-recognition of infection among Taiwanese MSM. The outbreak isolates were characterized to be variants of the intercontinentally transmitted SS18.1 clone, which falls into the globally prevalent phylogenetic sub-lineage IIIb. Inter-database pattern similarity searching indicated that the two PFGE genotypes had emerged in the USA and Japan. The epidemiological characteristics of this outbreak suggest roles of risky sexual behaviours or networks in S. sonnei transmission. We urge enhanced surveillance and risk-reduction interventions regionally against the interplay of HIV and shigellosis among MSM.

San-Huang-Xie-Xin-Tang attenuates inflammatory responses in lipopolysaccharide-exposed rat lungs.

In this study, the potential anti-inflammatory effect of San-Huang-Xie-Xin-Tang (SHXT) and its main component baicalin on LPS-induced lung injury were investigated and compared to the profile of dexamethasone (DEXA) in a pre-clinical animal model. Post-treatment with SHXT (75 mg/kg), baicalin (1.5 mg/kg) and DEXA (0.5 mg/kg), significantly inhibited LPS-induced hypotension, lung edema and acute survival rates. Western blotting analysis results indicated that all of them significantly inhibited LPS-induced iNOS, TGF-beta, p38MAPK, and ICAM-1 expressions in the lung tissues. Results from ELISA analysis showed that SHXT, baicalin and DEXA all decreased plasma levels of IL-1beta, TNF-alpha, and MCP-1 caused by LPS. Based on these findings, SHXT and baicalin decreased plasma concentrations of IL-1beta, TNF-alpha, MCP-1, and expressions of TGF-beta, ICAM-1, phosphorylated p38 MAPK, and iNOS, which were associated with lung injury and lethality. These evidences indicated that SHXT and baicalin showed strong anti-inflammatory activity, similar to that observed for DEXA, and therefore implicated that herbal SHXT might be therapeutically useful for the treatment of endotoxic lung injury.

Electron wedges for radiation therapy.

PURPOSE: Brain tumors can be advantageously treated with electron over photon radiation, by exploiting the rapid fall-off in dose with depth. This advantage could be further enhanced by utilizing multiple electron beams. However, in some beam configurations, wedged dose profiles would be necessary for the dose uniformity. Unlike photons, shaped pieces of material placed in electron beam severely degrade the energy, give additional scattering and, therefore, are suboptimal. The purpose of this study was to create wedged electron fields, using intensity modulation. The combination of electron wedges enables a more uniform coverage of brain tumors with a reduced dose to normal tissue. METHODS AND MATERIALS: Intensity modulation was performed for 10 to 50 MeV electrons using a narrow scanning elementary beam of a racetrack Microtron accelerator, delivering radiation pulses with coordinates and intensities prescribed by a custom scan matrix. Dispensing more pulses (or longer pulses) within the field to increase the local dose, one can sharpen the penumbra at depth and generate wedged dose distributions of arbitrary angle as well as many other desired profiles. We modulated the electron beams, measured dose distributions using film in an anthropomorphic phantom, and compared the results with conventional techniques. RESULTS: Intensity modulation of electron beams decreases the 50-90% penumbra at depth by 40% and increases the flatness by 80%. Wedged profiles at depth can be created for any angle up to about 70 degrees, depending on the beam energy. Multiple modulated electron beams give smaller 20-70% but larger 70-100% isodose regions than photon beams. CONCLUSIONS: Electron beams can improve dose distributions in brain compared to the same number of photon beams, reducing the 20-70% isodoses region in normal tissue by 30%. Intensity modulation significantly improves the dose distribution from combined electron beams providing a sharper penumbra, better conformity, and reduced margin.

The effect of single doses of radiation on mouse spinal cord.

We have used a mouse model to study spinal cord injury following single doses (12 to 75 Gy) of radiation. The spinal cord (T9,10-L4,5) of C3Hf/Sed//Kam mice was irradiated and response graded using four levels of neurological change. Findings were: (a) the doses required to paralyze 50% of animals (ED50) were 19.79, 20.77, and 21.85 Gy for mild, partial, and complete paralysis, respectively, as measured 200-360 days after radiation. (b) Most damage was progressive but it was not necessarily so; after doses up to 28 Gy recovery was occasionally seen. (c) Latency depended on the dose and the level of damage. Following doses around the ED50, paralysis occurred between 180 to 300 days. (d) There were significant fluctuations in the dose-latency relationship at doses less than 35 Gy. Latency may be not a reliable endpoint to compare biological effects of radiation in this dose range. (e) The radiosensitivity of mouse spinal cord was similar to that reported for rats. (f) Histologically, demyelination was the dominant lesion in the paralyzed animals. We conclude that the mouse is a good animal model to study radiation damage to the spinal cord, at least when a 2.2 cm length is irradiated.