Gender differences in psychosocial determinants of hand hygiene among physicians

OBJECTIVE

We investigated gender differences in psychosocial determinants that affect hand hygiene (HH) performance among physicians.

DESIGN

The survey included a structured questionnaire with 7 parts: self-assessment of HH execution rate; knowledge, attitude, and behavior regarding HH; internal and emotional motivation for better HH; barriers to HH; need for external reminders; preference for alcohol gel; and embarrassment due to supervision.

SETTING

The study was conducted across 4 academic referral hospitals in Korea.

PARTICIPANTS

Physicians who worked at these hospitals were surveyed.

METHODS

The survey questionnaire was sent to 994 physicians of the hospitals in July 2018 via email or paper. Differences in psychosocial determinants of HH among physicians were analyzed by gender using an independent t test or the Fisher exact test.

RESULTS

Of the 994 physicians, 201 (20.2%) responded to the survey. Among them, 129 (63.5%) were men. Male physicians identified 4 barriers as significant: time wasted on HH (P = .034); HH is not a habit (P = .004); often forgetting about HH situations (P = .002); and no disadvantage when I do not perform HH (P = .005). Female physicians identified pain and dryness of the hands as a significant obstacle (P = .010), and they had a higher tendency to feel uncomfortable when a fellow employee performed inadequate HH (P = .098). Among the respondents, 26.6% identified diversifying the types of hand sanitizers as their first choice for overcoming barriers to improving HH, followed by providing reminders (15.6%) and soap and paper towels in each hospital room (13.0%).

CONCLUSION

A significant difference in the barriers to HH existed between male and female physicians. Promoting HH activities could help increase HH compliance.

Hand hygiene knowledge, attitude, barriers and improvement measures among healthcare workers in the Republic of Korea: a cross-sectional survey exploring interprofessional differences

BACKGROUND

Hand hygiene (HH) is a fundamental component of infection prevention and control in healthcare settings. This study aimed to identify knowledge, attitude, and barriers to HH according to occupational groups and strategies to increase the rate of HH compliance among healthcare workers (HCWs).

METHODS

This cross-sectional survey was conducted in July 2018 at four university-affiliated hospitals. The survey comprised seven parts with 49 items, including self-reported HH compliance, knowledge, attitudes, behaviours, barriers to HH, and improvement strategies.

RESULTS

A total of 1046 HCWs participated in the survey. The nursing group's self-reported HH compliance rate was the highest, followed by other HCWs and physicians. The scores regarding knowledge, attitudes, and behaviours regarding HH were the highest in the nursing group. The nursing group also had higher internal and emotional motivation scores. Physicians and nurses found HH the most challenging in emergencies, while other HCWs considered skin problems caused by HH products the most significant barrier. Among 12 improvement measures, approximately 20% of the respondents ranked "diversify types of hand sanitisers," "install soap and paper towels in each hospital room," and "change perception through various HH campaigns" as the top three priorities. The physician group deemed the timely reminder of HH compliance as the second most critical improvement measure.

CONCLUSION

Differences in knowledge, attitude and barriers hindering HH compliance and improvement plans were identified for each group. The findings suggest that targeted interventions tailored to the specific needs of different occupational groups may effectively improve HH compliance in healthcare settings.

Current Status of Q Fever and the Challenge of Outbreak Preparedness in Korea: One Health Approach to Zoonoses

Human Q fever, a zoonosis caused by Coxiella burnetii, presents with diverse clinical manifestations ranging from mild self-limited febrile illnesses to life-threatening complications such as endocarditis or vascular infection. Although acute Q fever is a benign illness with a low mortality rate, a large-scale outbreak of Q fever in the Netherlands led to concerns about the possibility of blood transfusion-related transmission or obstetric complications in pregnant women. Furthermore, a small minority (< 5%) of patients with asymptomatic or symptomatic infection progress to chronic Q fever. Chronic Q fever is fatal in 5-50% of patients if left untreated. In South Korea, Q fever in humans was designated as a notifiable infectious disease in 2006, and the number of Q fever cases has increased sharply since 2015. Nonetheless, it is still considered a neglected and under-recognized infectious disease. In this review, recent trends of human and animal Q fever in South Korea, and public health concerns regarding Q fever outbreaks are reviewed, and we consider how a One Health approach could be applied as a preventive measure to prepare for zoonotic Q fever outbreaks.

[Expression and significance of immune checkpoint B7-homolog 4 in endometrial cancer]

Objective: To investigate the expression of B7 homolog 4 (B7-H4) and its clinical significance in endometrial cancer. Methods: A total of 833 patients with endometrial cancer admitted to Peking Union Medical College Hospital, Chinese Academy of Medical Sciences from 2009 to 2019, were enrolled. The expression of B7-H4, mismatch repair (MMR), p53, programmed cell death ligand 1 (PD-L1) protein, and CD₈⁺ T lymphocyte density in endometrial cancer tissues were detected by the EnVision two-step method of immunohistochemical staining. First-generation sequencing (Sanger method) was used to determine molecular subtyping of endometrial cancer. The χ² test was used to compare the differences in positive expression rate of B7-H4 protein in endometrial cancer tissues with different clinicopathological features and molecular subtyping, PD-L1 protein expression, and CD₈⁺ T lymphocyte density. Survival analyses [including recurrence-free survival (RFS) and disease-specific survival (DSS)] were performed for 664 patients with follow-up time≥3 months, with a median follow-up time of 31 months (range: 4-121 months), and the Cox proportional hazards regression model was used to analyze the relevant factors affecting the prognosis of patients with endometrial cancer. Results: (1) The median age of 833 patients was 58 years (range: 25-88 years); pathological type: 595 with endometrioid carcinoma, 238 with non-endometrioid carcinoma; surgical-pathological staging: 542 cases at stage Ⅰ, 38 cases at stage Ⅱ, 173 cases at stage Ⅲ, and 45 cases at stage Ⅳ. Molecular subtyping was performed in 590 patients, including 50 with POLE mutation, 163 with mismatch repair defect (MMR-d) type, 246 with nospecific molecular change (NSMP) type, and 131 with p53 mutation subtype. (2) B7-H4 protein was expressed with brownish-yellow stainind in the cell membrane and cytoplasm of endometrial carcinoma, and the positivity rate of B7-H4 protein was 71.5% (596/833). The positivity rates of B7-H4 protein among patients with different age, surgical-pathological stage, tumor grade, pathological type, depth of muscular invasion, presence or absence of lymphovascular space invasion, and molecular subtype were significantly different (all P<0.05). The positivity rates of B7-H4 protein among patients with different PD-L1 protein expression and CD₈⁺ T lymphocyte density were not significantly different (P>0.05). The 5-year RFS (83.9%) and DSS (87.3%) of B7-H4 protein-positive patients had an increasing trend compared with the 5-year RFS (77.2%) and DSS (78.1%) of B7-H4 protein-negative patients, but there were not statistically significant differences (P=0.053, P=0.083). (3) Univariate analysis showed that the 5-year RFS and DSS of patients with different age, tumor grade, surgical-pathological stage, pathological type, depth of muscular invasion, lymphovascular space invasion, and molecular subtype were significantly different (all P<0.01). There were no significant differences in 5-year RFS (P=0.184, P=0.113) and DSS (P=0.549, P=0.247) among patients with different CD₈⁺ T lymphocyte density and PD-L1 protein expression. Further analysis according to molecular subtype, the results of CD₈⁺ T lymphocyte density and PD-L1 protein expression showed that the 5-year RFS and DSS of B7-H4 protein-positive patients were higher than those of B7-H4 protein-negative patients with NSMP subtype, low density of CD₈⁺ T lymphocyte and PD-L1 protein-negative endometrial carcinoma (all P<0.05), however, there was no significant difference in 5-year DSS between B7-H4 protein-positive patients and B7-H4 protein-negative patients with PD-L1 protein-negative endometrial cancer (P=0.060). Multivariate analysis showed that positive expression of B7-H4 protein was an independent factor for 5-year RFS (HR=0.27, 95%CI: 0.09-0.78, P=0.016) and DSS (HR=0.16, 95%CI: 0.05-0.58, P=0.005) in patients with NSMP subtype endometrial carcinoma. In patients with low-density CD₈⁺ T lymphocytes endometrial cancer, positive expression of B7-H4 protein was an independent factor for 5-year RFS (HR=0.45, 95%CI: 0.26-0.80, P=0.006), but it was not an independent factor for 5-year DSS. In patients with PD-L1 protein-negative endometrial cancer, B7-H4 protein was not an independent factor for 5-year RFS. Conclusion: B7-H4 protein expressed highly in endometrial carcinoma tissues, and its high expression is closely related to clinicopathological features, molecular subtype of p53 mutant and NSMP, and the favorable prognosis of patients with low density of CD₈⁺ T lymphocyte immunophenotype endometrial carcinoma.

Multisystem Inflammatory Syndrome in an Adult after COVID-19 Vaccination: a Case Report and Literature Review

As the number of people vaccinated increases, people who complain of adverse reactions continue to occur. We experienced a case characterized by low blood pressure, persistent fever, edema due to increased systemic vascular permeability, and systemic inflammation confirmed by image and laboratory examinations after ChAdOx1 coronavirus disease 2019 (COVID-19) vaccination. The diagnostic criteria for multisystem inflammatory syndrome (MIS) in adults are known as fever of 3 days or more in adults, 2 or more mucocutaneous/gastrointestinal/neurologic symptoms, elevation of inflammatory markers, and clinical/imaging diagnosis of heart failure. A 67-year-old man who was medicated for hypertension and diabetes was admitted complaining of fever, maculopapular rash, diarrhea, headache, chills, and dizziness 6 days after the first vaccination of ChAdOx1 nCoV-19 in Korea. The COVID-19 test was negative but with low blood pressure, leukocytosis, skin rash, pulmonary edema, and increased inflammation markers. His lab findings and clinical course were consistent with those of MIS after COVID-19 vaccination. He was medicated with methylprednisolone 1 mg/kg and diuretics and recovered rapidly. He was discharged after 2 weeks and confirmed cure at outpatient clinic. We report an MIS case after COVID-19 vaccination in Korea.

Predictors of Acute Kidney Injury and 28-Day Mortality in Carbapenem-Resistant Acinetobacter baumannii Complex Bacteremia

Colistin is an, antibiotic used to treat carbapenem-resistant Acinetobacter baumannii complex (CRABC) infection. However, colistin is well known for its nephrotoxicity. To accurately assess the effects of colistin on acute kidney injury (AKI) and 28-day mortality, we investigated the risk factors associated with AKI and mortality in patients with CRABC bacteremia who received or never received colistin. Patients with CRABC bacteremia aged ≥18 years were retrospectively identified for 3 years at five tertiary teaching hospitals. AKI was defined by using the Kidney Disease Improving Global Outcomes criteria. AKI developed in 103 (34.9%) of the 295 patients enrolled patients. AKI developed more frequently in patients who received colistin than in patients who did not (46.7% vs. 29.5%, p = 0.004). Multivariate analysis showed that intravenous colistin usage was an independent risk factor for AKI in these patients. Nonfatal disease, catheter-related bloodstream infection, and administration of colistin were protective factors for 28-day mortality. However, the sequential organ failure assessment score and AKI were associated with poor outcomes. In conclusion, colistin may be a double-edged sword; although it causes AKI, it also reduces 28-day mortality in patients with CRABC bacteremia. Therefore, colistin administration as an appropriate antibiotic may improve CRABC bacteremia prognosis, despite its nephrotoxicity.

Etiology, Characteristics, and Outcomes of Community-Onset Pyomyositis in Korea: A Multicenter Study

Background

Pyomyositis (PM) is a serious soft tissue infection and despite its clinical importance, previous studies have not been able to fully determine the clinical characteristics and microbial epidemiology of PM in Korea, which we therefore aimed to investigate.

Materials and Methods

We retrospectively identified 140 adult patients diagnosed with PM from 13 general hospitals between January 2012 and December 2015. We analyzed the clinical and microbial characteristics of community-onset PM and compared them with community-acquired (CA) and healthcare-associated (HCA) PM.

Results

One hundred eleven organisms were isolated from 96 (68.6%) patients with PM. Staphylococcus aureus (38 patients) was the most common pathogen, followed by streptococci (24 patients), and enteric Gram-negative organisms (27 patients). Methicillin-resistant S. aureus (MRSA) was identified in four (2.9%) patients and in-hospital mortality reached 8.6% (12/140). Enterococci isolates were identified in the HCA PM subgroup only The proportion of MRSA isolates was not comparable between CA and HCA PM subgroups. In the 83 patients with PM infected by monomicrobial pathogens, isolates of Gram-negative organisms were more commonly found in HCA PM subgroup than in CA PM subgroup (47.6% [10/21] of patients with HCA PM vs. 20.7% [12/58] of patients with CA PM; P = 0.01).

Conclusion

Gram-positive cocci such as S. aureus and streptococci were dominant etiologies in community-onset PM, whereas MRSA appears to an uncommon causative organism of PM in Korea. Enteric Gram-negative organisms should also be considered as major etiologies, especially in HCA PM patient population in Korea.

Infectious Diseases Physician Workforce in Korea

This study aimed to evaluate the infectious disease (ID) physician workforce in Korea. We investigated the acquisition of ID physicians from 1992 to 2019 with their current working place in the Health Care System. We defined ID physicians working at general or tertiary-care hospitals as active ID physicians. A total 275 physicians acquired ID as a sub-specialty. Among the 275, 242 were active ID physicians. The density of active ID physicians was 0.47 per 100,000 population. Of all the 17 administrative districts, 11 (64.7%) fell short of 0.47, and 131 medical institutions employed the service of ID physicians. The median number of beds per adult ID physician was 372 (interquartile range, 280-507). It is essential to secure human resources to respond to emerging infectious diseases and perform the inherent work of ID physicians.

1194. Gender Differences in Psychosocial Determinants of Hand Hygiene Among Doctors

Background

Hand hygiene (HH) is essential in the prevention of hospital-acquired infections. It is known that there are differences in the compliance of HH between men and women but the reason for this phenomenon is unclear.

Methods

A survey on HH was conducted in July 2018 among healthcare workers at four different referral hospitals in South Korea. The differences between male and female doctors were then analyzed. The survey included a structured questionnaire with seven parts: (1) self-assessment of HH execution rate, knowledge, attitude, and behavior regarding HH, (2) internal motivation for better HH, (3) obstacles for HH, (4) emotional motivation, (5) the need for external supervision, (6) preference for alcohol gel, and (7) embarrassment due to supervision.

Results

Of the 1046 healthcare workers that replied to the survey, 201 (19.2%) were doctors, and of these, 129 (63.5%) were men. There was no significant difference between male and female doctors on the questionnaire related to knowledge, attitude, and behavior regarding HH. On the questions regarding internal motivation for better HH, male doctors had a higher tendency to agree that “I would be better at HH if it was related to getting a promotion,” but the results were statistically insignificant (5.08 vs. 4.69, P = 0.08). For the 14 questions about the obstacles for HH, the following five categories showed significantly higher results in men: (1) HH is difficult in emergency situations (4.87 vs. 4.51, P = 0.02), (2) time that could be spent on something more important is wasted on HH (3.12 vs. 2.67, P = 0.008), (3) HH is not a habit (3.26 vs. 2.58, P = 0.002), (4) I often forget about HH situations (3.60 vs. 2.89, P = 0.002), and (5) I do not perform HH because there is no disadvantage when I do not perform it (3.06 vs. 2.42, P = 0.008). In the category “HH causes pain and dryness of hands,” female doctors had a significantly higher tendency to agree (3.62 vs. 4.32, P = 0.003). Among the questions regarding emotional motivation, women had a higher tendency to agree that “Seeing a fellow employee perform bad HH angers me,” but there was no statistical significance (3.73 vs. 4.10, P = 0.07).

Conclusion

There was a significant difference between male and female doctors regarding obstacles for HH. A campaign for HH based on these results could be helpful for increasing HH compliance.

Disclosures

All authors: No reported disclosures.

Early Intravenous Colistin Therapy as a Favorable Prognostic Factor for 28-day Mortality in Patients with CRAB Bacteremia: a Multicenter Propensity Score-Matching Analysis

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is associated with high mortality. One of the strategies to reduce the mortality in patients with CRAB infections is to use intravenous colistin early but the effect of this strategy has not been proven. Therefore, we investigated the association of early colistin therapy with 28-day mortality in patients with CRAB bacteremia.

METHODS

This retrospective multicenter propensity score-matching analysis was conducted in the Korea by reviewing the medical records of adult patients with CRAB bacteremia between January 2012 and March 2015. Early colistin therapy was defined as intravenous colistin administration for > 48 hours within five days after the blood culture collection. To identify the risk factors associated with the 28-day mortality in CRAB bacteremia, the clinical variables of the surviving patients were compared to those of the deceased patients.

RESULTS

Of 303 enrolled patients, seventy-six (25.1%) patients received early colistin therapy. The 28-day mortality was 61.4% (186/303). Fatal or rapidly-fatal McCabe classifications, intensive care unit admission, Sequential Organ Failure Assessment scores ≥ 8, vasopressor use, and acute kidney injury were statistically independent poor prognostic factors. Catheter-related infection and early colistin therapy (adjusted odds ratio [aOR], 0.45; 95% confidence interval [CI], 0.21-0.94) were independent favorable prognostic factors associated with 28-day mortality in patients with CRAB bacteremia. Early colistin therapy was still significantly associated with lower 28-day mortality in the propensity score-matching analysis (aOR, 0.31; 95% CI, 0.11-0.88).

CONCLUSION

This study suggests that early colistin therapy might help reduce the mortality of patients with CRAB bacteremia.

[Feasibility study of blood oxygen level-dependent magnetic resonance imaging in evaluating the response of metastatic lymph nodes of rabbit VX2 tumor to radiotherapy]

Objective: To investigate the feasibility of blood oxygen level-dependent magnetic resonance imaging (MRI) in evaluating the response of metastatic lymph nodes of rabbit VX2 tumor to radiotherapy. Methods: Twenty-eight healthy New Zealand white rabbits which were provided by the Laboratory Animal Center of Soochow University, male or female, 2 to 3 months, weighing 2 to 3 kg, were used to establish the animal model of VX2 tumor popliteal fossa metastatic lymph node, and then were divided into either the radiotherapy group (n=16) or the control group (n=12). The radiotherapy group received a 20 Gy radiotherapy per rabbit, the control group received sham radiotherapy. All rabbits underwent MRI scan on four time points, including before (0 day), 3rd, 7th and 14th days after radiotherapy. The two parameters of size and R(2*) value (s(-1)) of lymph node were measured. At each time point,two rabbits in each group were sacrificed randomly to resect lymph nodes for pathological examination, and two parameters of microvessel density (MVD, strip/HP) and apoptosis index (AI, %) were analyzed. The parameters among the four time points in each group or between the two groups were compared. The correlation of lymph node size and R(2*) value with MVD or AI was analyzed, respectively. Results: A significant size difference was neither between the two groups or among the each time points in each group (P>0.05). The R(2*) of lymph node in the radiotherapy group was (29.6±1.7),(36.8±2.6),(44.8±5.8) and (57.7±6.2) s(-1) at the time points of 0, 3, 7 and 14 days, respectively, showing a gradual increase trend; MVD was (52.3±2.5),(41.0±3.6),(34.0±3.6) and (22.7±2.5) strip/HP respectively, showing a decreasing trend; AI was 12.8%±0.5%,14.9%±0.6%,20.6%±0.5% and 27.5%±0.7% respectively, showing a gradual increase trend (all P<0.05). In the control group, both R(2*) value and AI among the four time points did not change statistically (all P>0.05), but MVD showed a gradual increase trend,(50.0±3.0),(53.0±1.7),(60.3±2.5) and (70.0±2.0) strip/HP, respectively, P<0.05. There were significant differences in R(2*) and MVD at 3, 7 and 14 days, in AI at 7 and 14 days between the two groups (all P<0.05). There was a linear correlation of R(2*) value, but not of size, with MVD and AI (r=-0.87 and 0.94, respectively). Conclusion: Blood oxygen level-dependent MRI can indirectly reflect the hypoxic status of metastatic lymph nodes after radiotherapy, and has potential value in evaluating the response of metastatic lymph nodes to radiotherapy.

Clinical application of dual-phase F-18 sodium-fluoride bone PET/CT for diagnosing surgical site infection following orthopedic surgery

F-18 sodium-fluoride (NaF) bone positron emission tomography (PET/CT) has been used for diagnosing various bone and joint diseases, and, with using dual-phase scan protocol, it could give the same information obtained by the 3-phase bone scintigraphy. The present study aimed to evaluate the diagnostic ability of dual-phase F-18 NaF bone PET/CT in detecting surgical site infection after orthopedic surgery.Twenty-three patients who underwent dual-phase F-18 NaF bone PET/CT under clinical suspicion of surgical site infection of the bone following orthopedic surgery were enrolled in this study. Dual-phase bone PET/CT consisted of an early phase scan performed immediately after radiotracer injection and a conventional bone-phase scan. All dual-phase PET/CT images were visually assessed, and, for quantitative analysis, 6 parameters of dual-phase PET/CT (lesion-to-blood pool uptake ratio, lesion-to-bone uptake ratio, and lesion-to-muscle uptake ratio on both early phase and bone-phase scans) were measured.Surgical site infection was diagnosed in 14 patients of the 23 patients. The sensitivity, specificity, and accuracy of visual analysis of dual-phase F-18 NaF bone PET/CT for diagnosing surgical site infection of the bone were 92.9%, 100.0%, and 95.7%, respectively. Among the 6 parameters, the lesion-to-blood pool uptake ratio on early phase scan showed the highest area under the receiver operating characteristic curve value (0.857, 95% confidence interval, 0.649-0.966), with the cut-off value of 0.88 showing sensitivity, specificity, and accuracy of 85.7%, 88.9%, and 87.0%, respectively.Our study showed the high diagnostic ability of dual-phase F-18 NaF bone PET/CT for detecting surgical site infection following orthopedic surgery. Further studies are needed to compare the diagnostic ability of dual-phase bone PET/CT with other imaging modalities.

Clinical usefulness of two-phase 18F-sodium-fluoride (18F-NaF) bone PET/CT for evaluating treatment response of bone metastases from breast cancer: Case report

We report the case of a breast cancer patient in whom a two-phase ¹⁸F-sodium-fluoride (¹⁸F-NaF) bone PET/CT was useful for detecting hidden bone metastases and assessing treatment response. The patient underwent a two-phase bone PET/CT to evaluate a newly developed lesion found on bone scintigraphy following surgery. In the perfusion and bone phase PET/CT images, focally increased perfusion and bony uptake were found in the sacrum and L5 vertebra, suggesting bone metastases of breast cancer. Therefore, the patient subsequently underwent palliative treatment. In another twoPET/CT studies (each including two-phase bone images) performed after 3and 6months of follow-up, the perfusion phase images showed an improvement of the lesion uptake more clearly than in the bone phase images in the visual and semi-quantitative analyses, and thus the perfusion phase images were more useful for clarifying the treatment response earlier than the bone phase images. This is the first case showing the clinical usefulness of ¹⁸F-NaF bone PET/CT with the perfusion imaging technique for evaluating bone metastases and the therapeutic response of metastatic bone lesions.

Monomicrobial gram-negative necrotizing fasciitis: An uncommon but fatal syndrome

This study aimed to characterize patients with monomicrobial gram-negative necrotizing fasciitis in three university hospitals in Korea. In this study, of the 115 patients with community-acquired necrotizing fasciitis, 67 (58%) had monomicrobial infections: 31 (27%) in the gram-negative group and 36 (31%) in the gram-positive group. The majority of patients in the gram-negative group were infected with Escherichia coli followed by Klebsiella pneumoniae and Vibrio vulnificus. More patients in the gram-negative group showed liver cirrhosis than those in the gram-positive group (39% vs. 14%, P = 0.02). In a multivariable logistic regression analysis, liver cirrhosis (adjusted odds ratio [aOR], 13.7; 95% confidence interval [CI], 2.9-67.0), treatment with antibiotics without surgery (aOR, 10.2; 95% CI, 2.1-48.3), and lower level of albumin (aOR 4.9; 95% CI, 1.6-14.9) were associated with 30-day mortality. Our findings suggest that gram-negative necrotizing fasciitis is more often associated with liver cirrhosis and has poorer outcomes than gram-positive necrotizing fasciitis.

Modified Measles in an Anti-Measles Immunoglobulin G-negative Healthcare Worker who had Received Two Doses of Measles-Containing Vaccine

To date, documentation of two doses of measles-containing vaccine (MCV) has been accepted as confirmation of measles immunity among healthcare workers (HCWs). However, we encountered measles in an HCW who had received two doses of MCV. A patient with measles was admitted to our hospital. Among 62 exposed HCWs, one nurse who had previously received two doses of MCV was shown to be negative for anti-measles immunoglobulin G (IgG), and was confirmed to have measles 14 days after exposure. Based on this experience, we suggest that all HCWs should be tested for anti-measles IgG to confirm their immunity to measles.

2371. Monomicrobial Gram-Negative Necrotizing Fasciitis: An Uncommon but Fatal Syndrome

Background

Necrotizing fasciitis is a rapid progressive and potentially life-threatening infection. Although the relative emergence of non-synergistic single Gram-negative organisms as pathogen could be a therapeutic issue for clinicians, limited studies so far described the characteristics due to the low incidence.

Methods

We retrospectively reviewed clinical data of necrotizing fasciitis patients who were clinically diagnosed between May 2001 and December 2015 in university hospitals of three different cities of the Republic of Korea. We compared clinical characteristics and outcomes of patients with monomicrobial Gram-negative with those of the Gram-positive counterpart.

Results

A total of 115 patients with community acquired necrotizing fasciitis were identified. Among them, monomicrobial infections were 67 (58%) cases: 31 (27%) in the Gram-negative group and 36 (31%) in the Gram-positive group. The majority of Gram-negative group was E. coli followed by K. pneumonia and V. vulnificus. There were more cases of the Gram-negative group showing liver cirrhosis (39% vs. 14%, P = 0.02) and bacteremia (52% vs. 16%, P = 0.02). A total of 23 (10%) patients died within 30 days, including 15 (19%) in the Gram-negative group and 8 (10%) in the Gram-positive group (P = 0.02). In multivariable logistic regression, liver cirrhosis (adjusted odds ratio [aOR], 13.7; 95% confidence interval [CI], 2.9–67.0), treatment with antibiotics without surgery (aOR, 10.2; 95% CI, 2.1–48.3), and lower level of albumin (aOR 4.9; 95% CI, 1.6–14.9) were significantly associated with 30-day mortality.

Conclusion

Our findings suggest that necrotizing fasciitis caused by Gram-negative pathogen more often associated with liver cirrhosis and has poorer outcomes than the Gram-positive counterpart.

Disclosures

All authors: No reported disclosures.

1157. Optimal Isolation Periods Based on Time Interval to Elimination of Scabies After Topical Agent in the Real Clinical Practice

Background

Scabies reemerged globally as the ninth of most highly prevalent skin diseases from 1990 to 2010. Existing topical agents, like permethrine and lindane are highly effective showing 95% or more therapeutic response. Patient isolation is only recommended for one day after treating with topical agents. However, there is little evidence-based recommendation on optimal isolation period after treatment in healthcare settings to prevent secondary infection.

Methods

All patients who were diagnosed from 2008 to 2017 with scabies at a referral university hospital in Seoul, Republic of Korea were analyzed. We investigated the time interval between symptom onset and diagnosis of scabies. The period from the application of topical agents and clinical resolution was also analyzed.

Results

A total of 23 patients were diagnosed with scabies. There was no crusted scabies such as Norwegian scabies. Seventy percent of these patients were referred from long-term care facilities. Median number of treatment was three times per patient (Interquartile range [IQR], 2–3). Time interval between the onset of symptoms and the diagnosis of scabies was median 4 days (IQR, 2–14). Median isolation period was 13 days (IQR, 8–15). Dermatologist confirmed successful treatment of 16 patients, the median time until confirmation was 15 days (IQR, 8–17). Three patients discontinued isolation before dermatologist’s confirmation. After re-evaluation by a dermatologist, one of the three was re-isolated due to persistent scabies infestation.

Conclusion

Scabicides are highly efficacious, but repeated microscopic examination for confirming elimination is strongly recommended. Optimal isolation period should be individualized based on the repeated dermatologic examination.

Disclosures

All authors: No reported disclosures.

Therapeutic outcome of spinal implant infections caused by Staphylococcus aureus: A retrospective observational study

Spinal implant infection is a rare but significant complication of spinal fusion surgery, and the most common pathogen is Staphylococcus aureus. It is difficult to treat due to this pathogen's biofilm-forming ability and antibiotic resistance. We evaluated the therapeutic outcome of treatments for S aureus spinal implant infections. We retrospectively reviewed all patients with S aureus spinal implant infections at 11 tertiary-care hospitals over a 9-year period. Parameters predictive of treatment failure and recurrence were analyzed by Cox regression. Of the 102 patients with infections, 76 (75%) were caused by methicillin-resistant S aureus (MRSA) and 51 (50%) were late-onset infections. In all, 83 (81%) patients were managed by debridement, antibiotics, and implant retention (DAIR) and 19 (19%) had their implants removed. The median duration of all antibiotic therapies was 52 days. During a median follow-up period of 32 months, treatment failure occurred in 37 (36%) cases. The median time to treatment failure was 113 days, being <1 year in 30 (81%) patients. DAIR (adjusted hazard ratio [aHR], 6.27; P = .01) and MRSA infection (aHR, 4.07; P = .009) were independently associated with treatment failure. Rifampin-based combination treatments exhibited independent protective effects on recurrence (aHR, 0.23; P = .02). In conclusion, among patients with S aureus spinal implant infections, MRSA and DAIR were independent risk factors for treatment failure, and these risk factors were present in the majority of patients. In this difficult-to-treat population, the overall treatment failure rate was 36%; rifampin may improve the outcomes of patients with S aureus spinal implant infections.

Natural prognosis of carbapenem-resistant Acinetobacter baumannii bacteremia in patients who did not receive appropriate antibiotic treatment: A retrospective multicenter study in Korea

Carbapenem-resistant Acinetobacter baumannii (CRAB) infection is a major issues in current era. The aim of study was to investigate the natural prognosis and prognostic factors associated with 28-day mortality in patients with CRAB bacteremia who were not receiving appropriate antibiotic treatment.Adult patients with CRAB bacteremia were retrospectively identified between April 2012 and March 2015 at 5 tertiary hospitals in Republic of Korea. Patients who were transferred to another hospital within 28 days of onset of bacteremia and who receive appropriate antibiotics more than 48 hours were excluded. We investigated prognostic factors associated with 28-day mortality in patients with CRAB bacteremia without appropriate antibiotic treatment.Of enrolled 205 patients, 143 (69.8%) patients died within 28 days after blood culture. Of patients with 28-day mortality, 88.9% (127/143) of patients died within 5 days. Of 78 patients who survived more than 5 days, the 28-day mortality was 20.5% (16/78). Diabetes mellitus (adjusted odds ratio [aOR] 3.81, 95% confidence interval [95% CI] 1.19-12.20), immunocompromised (aOR 8.72, 95% CI 2.62-29.70), sequential organ failure assessment (SOFA) ≥ 10 (aOR 13.87, 95% CI 3.70-51.96), vasopressor use (aOR 7.03, 95% CI 1.79-27.60), and pneumonia (aOR 4.44, 95% CI 1.67-11.78) were found to be the factors independently associated with the 28-day mortality.The 28-day mortality in patients with CRAB bacteremia without appropriate treatment was high, although some patients could survive. Severity and underlying conditions were important prognostic factors in patients with CRAB bacteremia.

Effect of cerebral embolus size on the timing of cardiac surgery for infective endocarditis in patients with neurological complications

The optimal timing of cardiac surgery remains unclear for patients with neurological complications of infective endocarditis (IE). However, neuroimaging findings may allow more refined clinical decision-making. We analyzed clinical and advanced neuroimaging data for 135 patients with IE who had preoperatively diagnosed ischemic cerebral complications (86 patients) or hemorrhagic complications (49 patients), between January 1997 and May 2013. The effect of early surgery (within 3 and 7 days of ischemic and hemorrhagic complications respectively) on in-hospital mortality and 1-year adverse outcomes (mortality, relapse, or new embolic events) was estimated. Small cerebral emboli (≤2 cm) led to early surgery (cases with ischemic complications: 57% vs 26%, p = 0.04; cases with hemorrhagic complications: 56% vs 13%, p = 0.02). Early surgery was not significantly associated with increased rates of in-hospital mortality and 1-year adverse outcomes among patients with ischemic complications (14% vs 9%, odds ratio [OR] 1.67, 95% confidence interval [CI] 0.44-6.38, p = 0.52; 17% vs 14%, OR 1.27, 95% CI 0.39-4.14, p = 0.7 respectively). Only 1 patient (4%) with hemorrhagic complications experienced in-hospital mortality in the early surgery group, and early surgery was not significantly associated with 1-year adverse outcomes (21% vs 12%, OR 1.93, 95% CI 0.41-9.16, p = 0.46). The risks of in-hospital mortality and 1-year adverse outcome were not increased, even if cardiac surgery had been carried out earlier than previously described. Our findings suggest that early surgery, when indicated, may be performed for patients with IE and neurological complications, especially if the cerebral embolus has a diameter of ≤2 cm.

Is the Initial Size of Tuberculous Lymphadenopathy associated with Lymph Node Enlargement during Treatment?

There are little data on the changes in lymph node (LN) size during the treatment of tuberculous lymphadenopathy (TB LAP). This study aimed to provide data on LN changes during treatment. Between March 2014 and December 2015, 20 patients who were diagnosed with cervical TB LAP were enrolled. LN enlargement within two months (50%, 4/8 vs. 8.3%, 1/12; P = 0.04) was more frequently observed in patients with initial LN size ≥ 7.5 cm². Enlarged LNs were excised in three patients owing to pain and fistula formation. Initial LN size may be associated with LN enlargement during treatment.

[Effect of snow sports on knee cartilage maturation in children and adolescent with MRI quantitative analysis Zhang]

Objective: To evaluate the effect of snow sports to the knee cartilage maturation of children and adolescent with quantitative analysis of 3.0 T MRI. Methods: Twenty children and adolescent who underwent snow sports training more than 6 months (11 males and 9 females) were recruited and named with sports group, and twenty children and adolescent who live regularly without any exercise (10 males and 10 females) were recruited as control group from June 2014 to June 2015.Each group was divided into subgroups according to their gender.Both groups were scanned by 3.0 T MR.According to the loading features of knee articular cartilage in snow sports, medial femoral condyle, lateral femoral condyle, medial tibial condyle and lateral tibial condyle were divided into subareas.T₂ values and cartilage thickness were measured in all areas. Results: The median ages of the sports group and control group were 14.2 and 13.6 years old, which showed no statistical difference between two groups.The BMI of the sports group and control group were 18.3 and 17.9 kg/m^2, which showed no statistical difference between two groups.Both in sports group and control group, the thickness and T₂ values of all areas showed significant differences between man and women in each group (all P<0.05). The cartilage thickness of sports group was higher than control group (P<0.05). The T₂ values showed no statistical difference in anterior central, posterior central of femoral condyles and anterior, central areas of tibial condyles between sports group and control group(P≥0.05). The T₂ values of anterior part of posterior femur and posterior areas of tibial condyle in sports group was higher than control group (P≥0.05). Conclusion: Gender difference may be an important effect factor of cartilage thickness. Scientific snow sports training maybe has positive influence for cartilage maturation of children and adolescent.

Clinical features and treatment outcomes of septic arthritis due to Mycobacterium massiliense associated with intra-articular injection: a case report

Background

There are increasing reports on nosocomial Mycobacterium massiliense infection, but septic arthritis and osteomyelitis because of that microorganism is rare. This report focuses on the clinical aspects of M. massiliense arthritis outbreak concurrent with soft tissue infection.

Case presentation

An outbreak of septic arthritis among patients who had been injected at a single clinic occurred in South Korea between April and September 2012. This may be associated with repeated injection of triamcinolone contaminated with M. massiliense. Nine of the Korean patients visited our hospital complaining of painful swelling of the knees. During treatment course, patients are suffered from soft tissue abscess around the injection site. Acid-fast bacilli culture for infected tissue was positive in five patients, and polymerase chain reaction for non-tuberculous mycobacteria was positive in four patients. They were treated with antibiotics, repeated arthroscopic surgeries, incision and drainage for a long time. All patients were eventually cured but three patients have suffered from a decreased range of motion.

Conclusion

Early clinical suspicion and microbiological diagnosis are key factors in reducing morbidity since septic arthritis with M. massiliense manifests late after the injection and treatment of it is a laborious process.

Late paradoxical lymph node enlargement during and after anti-tuberculosis treatment in non-HIV-infected patients

SETTINGS

A tertiary referral centre in South Korea.

OBJECTIVE

To investigate the incidence, clinical characteristics and outcomes of late paradoxical response (>4 months after the initiation of anti-tuberculosis treatment) during and after anti-tuberculosis treatment in non-human immunodeficiency virus (HIV) infected patients with lymph node tuberculosis (TB).

DESIGN

We retrospectively reviewed the medical records of non-HIV-infected patients with lymph node TB between 1997 and 2007, and prospectively enrolled patients with newly diagnosed lymph node TB between 2008 and 2013.

RESULTS

Of 467 patients with confirmed and probable lymph node TB, 83 (18%) displayed a paradoxical response: 57 of these (69%) were classified as early and 26 (31%) as late paradoxical response. Patients with late paradoxical response (median 12 months) received more prolonged anti-tuberculosis treatment than those with early (median 9 months, P < 0.001) or no paradoxical response (median 9 months, P < 0.001). The frequency of post-treatment lymph node enlargement increased progressively from those without any paradoxical response (6%), through those with an early response (12%) to those with a late response (23%).

CONCLUSIONS

Paradoxical response presents late in about one third of non-HIV-infected patients with lymph node TB who experience a response. Although anti-tuberculosis treatment is commonly prolonged in patients with late paradoxical response, post-treatment lymph node enlargement is more frequent in these patients.

[Correlation between susceptibility weighted imaging manifestation and serum cystatin C for delayed graft function]

OBJECTIVE

To explore the correlation between susceptibility weighted imaging (SWI) manifestation and serum cystatin C level for delayed graft function (DGF).

METHODS

The conventional MRI, SWI and serum cystatin C of 27 cases with DGF in nephrotransplantation center in Third Affiliated Hospital of Suzhou University from September 2014 and August 2015 were retrospectively analyzed.By contrasting conventional MRI images of transplanted kidney in DGF, the imaging manifestations of benign tumors such as cysts and angiomyolipomas were excluded on SWI images, and then making the renal cortex as the reference, if the abnormal signal lesions were found in the transplanted kidney, the location and signal intensity would be analyzed. The differences in serum cystatin C level between DGF groups without and with abnormal signal lesions were compared by using independent-sample t-test.The correlation between SWI manifestation and serum cystatin C level for DGF was assessed with Spearman rank correlation analysis.

RESULTS

A total of 15 cases were found without abnormal signal lesions and the average value of their serum cystatin C level was (2.92±0.44) mg/L.A total of 12 cases were found with abnormal low signal lesions located at junctional zone between cortex and medulla, and the average value of their serum cystatin C level was (6.91±0.96) mg/L. The differences in serum cystatin C level between the two DGF groups were statistically significant (t=-4.040, P=0.000). There was a positive correlation between the abnormal low signal lesions on SWI and serum cystatin C level (r=0.660, P=0.000).

CONCLUSION

The status of renal function impairment could be reflected by being with or without abnormal signal lesions on SWI. A relatively big renal function impairment may be predicted by the appearance of abnormal low signal lesions at junctional zone between cortex and medulla on SWI.

Diagnostic Usefulness of IFN-Gamma Releasing Assays Compared With Conventional Tests in Patients With Disseminated Tuberculosis

IFN-gamma releasing assays (IGRAs) such as T-SPOT.TB assay and QuantiFERON-TB In-Tube (QFT-GIT) have yielded promising results for the diagnosis of tuberculosis (TB). However, little is known about the usefulness of these assays for diagnosing disseminated TB. We therefore compared their usefulness with traditional tests in patients with disseminated TB. All adult patients with suspected disseminated TB were prospectively enrolled at a tertiary hospital in an intermediate TB-burden country during a 6-year period. Disseminated TB was defined as involvement of the bone marrow or ≥2 noncontiguous organs, or presence of miliary lung lesions. A total of 101 patients with confirmed and probable disseminated TB were finally analyzed. Of these 101 patients, 52 (52%) had miliary TB and the remaining 49 (48%) had nonmiliary disseminated TB. In addition, 63 (62%) had no underlying disease. Chronic granuloma with/without necrosis, acid-fast bacillus staining, Mycobacterium tuberculosis PCR, and culture for M tuberculosis were positive in 77% (41/53), 43% (43/101), 70% (67/96), and 72% (73/101), of the patients, respectively. The T-SPOT.TB assay was positive in 90% (91/101) of them. The sensitivity of the T-SPOT.TB assay in patients with miliary TB (90%) was similar to that in patients with nonmiliary TB (90%) (P > 0.99). In a subgroup analysis of the 58 patients in whom both QFT-GIT and the T-SPOT.TB results were available, the sensitivity of QFT-GIT (67%) was lower than that of T-SPOT.TB (95%) (P < 0.001). In conclusion, T-SPOT.TB assay may be a helpful adjunct test for disseminated TB.

Necrotizing fasciitis in three university hospitals in Korea: a change in causative microorganisms and risk factors of mortality during the last decade

Background

Necrotizing fasciitis is a life-threatening infectious disease with rapidly progressive involvement of the affected site. Because of the high mortality rate of this disease, early diagnosis, surgical exploration, and administration of appropriate antibiotics are necessary. The present study aimed to further review the changes in the clinical and microbiological characteristics of necrotizing fasciitis using patients' medical records from consecutive databases of 3 hospitals in Korea.

Materials and Methods

In this study, we retrospectively reviewed the medical records of patients with necrotizing fasciitis who were clinically diagnosed between May 2001 and February 2012 in 3 university hospitals in Korea. In total, the data of 83 patients were analyzed, including those of 20 patients from our previous study in 2006. An organism found in a blood culture or surgical specimen was regarded as a causative organism.

Results

Of the 83 patients, 68(81.9%) had community-acquired infections. Ninety microorganism species were indentifed by culture. Streptococcus was the most commonly identified pathogen. Non-fermentative gram-negative bacteria and Candida species have recently emerged, especially in immunocompromised hosts.

Conclusions

Gram-positive organisms are still the most common pathogens of necrotizing fasciitis. However in our study, various gram-negative bacteria with different levels of susceptibility to antibiotics, as well as Candida species, were responsible for the necrotizing fasciitis. Initial empirical antimicrobial agents for necrotizing fasciitis should be considered depending on the individual patient's condition.

Risk Factors for Mortality in Patients with Acinetobacter baumannii Bacteremia

Background

Acinetobacter baumannii, an opportunistic nosocomial pathogen that can cause significant morbidity and mortality, has emerged as a worldwide problem. The aim of this study was to evaluate the risk factors for mortality in patients with A. baumannii bacteremia.

Materials and Methods

We retrospectively evaluated 118 patients who had A. baumannii bacteremia between July 2003 and December 2011. The aim of this study was to identify the 30-day mortality in patients with A. baumannii bacteremia and relevant risk factors.

Results

The bacteremia-related 30-day mortality rate was 34.1%. Univariate analysis revealed that the risk factors for mortality included malignancy, longer hospital stay before bacteremia, intensive care unit (ICU) stay at the time of bacteremia, mechanical ventilation, use of a central venous catheter, unknown origin of bacteremia, bacteremia due to pneumonia, antimicrobial resistance to carbapenems, and elevated Acute Physiology and Chronic Health Evaluation II and Pitt bacteremia scores. Multivariate logistic regression analysis revealed that resistance to carbapenems (odds ratio [OR]: 4.01, 95% confidence interval [CI]: 1.51 to 0.68, P = 0.005), need for mechanical ventilation (OR: 3.97, 95% CI: 1.41 to 11.13, P = 0.005), and presence of malignancy (OR: 4.40, 95% CI: 1.60 to 12.08, P = 0.004) were significantly related to mortality risk.

Conclusions

Risk factors such as resistance to carbapenems, mechanical ventilation, and presence of malignancy were found to be associated with high mortality rates in the patients with A. baumannii bacteremia.

Chlamydial infection during trachoma monitoring: are the most difficult-to-reach children more likely to be infected?

OBJECTIVES

During mass antibiotic distributions for trachoma, certain individuals are difficult to locate and go untreated. These untreated individuals may serve as a source of community reinfection. The importance of this difficult-to-locate, untreated population is unclear. We sought to determine whether individuals who are difficult to locate were more likely to be infected with ocular chlamydia than those who were easier to locate.

METHODS

We monitored 12 Ethiopian communities 1 year after a third annual mass azithromycin treatment for trachoma. Conjunctival swabbing for chlamydial RNA was performed in a random sample of children from each community. If insufficient numbers of children were enrolled on the first monitoring day, we returned on subsequent days.

RESULTS

Of the 12 communities, 10 required more than one monitoring day. On average, 16.1% (95% CI 7.9-30.0) of children were enrolled after the initial day. Evidence of chlamydia was found in 7.1% (95% CI 2.7-17.4) of 0- to 9-year-old children. No ocular swabs collected after the initial day were positive for chlamydial RNA. Children examined after the initial monitoring day were significantly less likely to have ocular chlamydial infection than children seen on the initial day; Mantel-Haenszel common OR = 0 (95% CI 0-0.77).

CONCLUSIONS

In a setting of repeated annual mass azithromycin treatments, after approximately 80% of individuals have been located in a community, extra efforts to find absent individuals may not yield significantly more cases of ocular chlamydia.

Effects of random potential on transport

The effects of random potential on the transport of two systems, which are the motion of motor proteins along a biopolymer and the thermally assisted vortex diffusion in layered high-Tc superconductors, are investigated, respectively. It is found that the effects of the random potential on the transport process as the amplitude of random potential increased are much more remarkable than those as the correlation length of random potential increased. The amplitude and the correlation length of random potential play opposing roles in the transport of the systems.

Biomechanical properties and a kinetic simulation model of the smooth muscle I2 in the buccal mass of Aplysia

The muscle I2 is a smooth muscle from the buccal mass of the marine mollusc Aplysia californica whose neural control, in vivo kinematics, and behavioral role have been extensively analyzed. In this study, we measured the activation and contractile dynamics of the muscle in order to construct a Hill-type kinetic model of the muscle. This is the first study to our knowledge, of Aplysia muscle contractile dynamics. The isometric force-frequency relationship of I2 had a frequency threshold of about 6-8 Hz, and its force output saturated at 20-25 Hz, properties that match the high frequency (20 Hz) bursts generated by the B31/B32 neurons that innervate it. Peak isometric force was generated at about 118% of the in situ relaxed length. These results and I2's estimated in vivo kinematics suggest that it generates maximum force at the onset of protraction. The muscle tension during iso-velocity lengthening and shortening was an asymmetric function of velocity. Short range stiffness and yielding responses were observed in lengthening, whereas muscle tension decreased smoothly in shortening. These visco-elastic properties suggest that the I2 muscle can serve to brake forceful retraction movements. A Hill-type model, parameterized from the measurements, captured many of the mechanical properties of I2. Our results provide a quantitative understanding of the biomechanical significance of the muscle's neural control and provide a basis for simulation studies of the control of feeding behavior.

Isolation and characterization of a cDNA encoding the cysteine proteinase inhibitor, induced upon flower maturation in carnation using suppression subtractive hybridization

The suppression subtractive hybridization (SSH) method was used to isolate differentially expressed genes during carnation flower maturation. Five cDNA clones, designated as carnation flower maturation-induced (CFMI), were verified as flower maturation-induced cDNAs. Sequence analysis of five CFMI (CFMI-5, CFMI-6, CFMI-7, CFMI-9, and CFMI-10) clones revealed that one of the clones, CFMI-5, showed high sequence similarity to the cysteine proteinase inhibitor gene, predicted to be involved in flower maturation. The full length cDNA clone CFMI-5 was 531 nucleotides (nts) long and consisted of an open reading frame of 294 nucleotides, encoding a 98 amino acid protein, 12 nucleotides of 5'-untranslated region and 3'-untranslated region (225 nts) with a poly(A)+ tail. The predicted CFMI-5 amino acid sequence had a conserved sequence Gln-Val-Val-Ala-Gly, which corresponds to the active site of proteinase inhibition. Northern blot analysis revealed tissue-specific expression of CFMI-5 transcripts, as the transcripts were expressed preferentially in petals and styles. A PCR-based cDNA subtraction method, termed suppression subtractive hybridization, was identified as a rapid method to screen differentially expressed genes in a short time.

A nonisometric kinetic model for smooth muscle

We have modeled the nonisometric contractile dynamics of smooth muscle by modifying a four-state model of actin and myosin bonds originally proposed by Hai and Murphy to simulate the isometric contractions of vertebrate smooth muscle. The model includes a latch bridge, which cycles more slowly than regular cross bridges. We generalized this model to represent the calcium-regulated processes of vertebrate and invertebrate smooth muscles. We added length dynamics by assuming length-dependent bonding and unbonding rates for the cross bridges. The calculation of the cross-bridge length distribution was simplified by assuming a Gaussian distribution, as first done by Zahalak for skeletal muscle. To test the performance of this model, we simulated isometric and nonisometric responses of different kinds of smooth muscle, including vascular smooth muscle, airway smooth muscle, molluscan catch muscle (anterior byssus retractor muscle), and Aplysia I(2) muscle. The model captures the economical force maintenance property at the later stages of isometric muscle contraction and responses to imposed lengthening and shortening movements.

Interactive program for spectral and area analysis of compound action potentials of A-fiber and C-fiber

An interactive program was described to correct the baseline wandering of the compound action potentials (CAPs) of C-fiber, to calculate the area and the peak amplitude of CAPs, and to analyze their spectral distribution. Using this program, we found the optimal bandpass of the filter for recording CAPs to be from 10 Hz to 3 kHz.

Canine intervertebral disks: correlation of anatomy and MR imaging

Because the structure, maturation, and degeneration of canine intervertebral disks resemble those of humans, the authors developed a model of acute intervertebral disk degeneration in dogs. Herniated disks of 18 dogs were examined with magnetic resonance (MR) imaging and then sectioned with a freezing microtome. On the basis of their morphologic appearance in the freezing microtome sections, most of the lumbar intervertebral disks could be categorized as one of six types. Each type has characteristic features and a distinctive appearance on MR images. Findings of this study--including decreased signal intensity from the intervertebral disk, altered signal intensity in contiguous bone marrow, bulging of the anulus fibrosus, herniation of the nucleus pulposus, and contrast enhancement after intravenous administration of gadolinium diethylenetriaminepentaacetic acid (DTPA)--resemble observations from human clinical studies. Classification of degenerating disks and identification of MR imaging characteristics of each type may improve the interpretation of MR images and recognition of early disk degeneration in humans.