Education level may modify the association between cardiac index and cognitive function among elders with normal ejection function

Background

Lower cardiac index (CI) in elders has been associated with incident dementia, and higher CI has protectively effect with brain aging. In the present study, we investigated the modulating effects of education level and arterial stiffness on the association between CI and cognitive function among older adults.

Methods

A total of 723 elders (≥60 years, 50.1% women) with normal left ventricular ejection fraction (≥50%) were identified from the Cardiovascular Diseases Risk Factor Two-Township Study. CI was calculated from the Doppler-derived stroke volume. We evaluated arterial stiffness by measuring carotid-femoral pulse wave velocity (CFPWV) and global cognitive function by using the Mini-Mental Short Examination (MMSE). Education level was determined by years of formal education.

Results

In linear regression analysis adjusting for age, sex, formal years of education, and CFPWV, CI was significantly positively associated with MMSE (BETA=0.344±0.130, P = 0.0082). In logistic regression analysis adjusting for age, sex, formal years of education, and CFPWV, subjects with a CI≥75 percentile had a significantly lower risk of low MMSE (<26) (OR = 0.495, 95% CI = 0.274–0.896, P = 0.02). In subgroup analysis, higher CI was significantly associated with higher MMSE and lower risk of low MMSE only in elders with ≤ 9 years of formal education. Causal mediation analysis suggests that higher CI maintains higher MMSE in elders with lower education levels whereas higher CFPWV causes lower MMSE in all the elders.

Conclusion

In elders with normal ejection fraction, a higher CI was associated with a lower risk of cognitive function impairment, independent of arterial stiffness, mainly in subjects with a lower education level and possibly a smaller cognitive reserve.

Molecular Identification and Selection of Probiotic Strains Able to Reduce the Serum TMAO Level in Mice Challenged with Choline

Trimethylamine oxide (TMAO) originates from trimethylamine (TMA), which is oxidized in the liver by hepatic flavin-containing monooxygenases (FMO3). TMA is produced by its dietary precursors such as choline, carnitine, and phosphatidylcholine by gut microbiota. TMAO attracts attention, identified as a novel and independent risk factor for promoting obesity, atherosclerosis and cardiovascular disease (CVD), chronic kidney disease (CKD), insulin tolerance, and colon cancer. Probiotics have been considered as live microorganisms, providing benefits to their host when they are given in sufficient quantities and administered continuously. The objective of this study is to suggest a method to select potential probiotic strains to reduce the serum concentration of TMAO in mice fed with choline. In this work, we chose three lactobacilli with strong adherence capability, and fed multistrain formula (MF) to the mice challenged with choline. On days 7, 14, and day 28, it was found that the MF-containing L. amylovorus LAM1345, Lpb. plantarum LP1145, and Lim. fermentum LF33 showed a significant reduction in serum TMAO and TMA levels. For the single strains, LP1145 reduced TMAO on days 14 and 28, and strain LAM1345 reduced TMAO significantly on days 7 and day 14. For strain LF1143 from strain LF33, it showed no significant effect on TMAO and TMA. Thus, MF showed the best effect, which may be due to the additive and synergetic effect and the contribution of strain LP1145 and LAM1345. Finally, for the LAM1345 and LP1145 strains, we used molecular identification and typing methods to assure that these two strains are unique strains. The methods used for LAM 1345 were leader peptidase A (lepA) gene analysis and phylogenetic analysis, while for strain LP 1145and other strains of Lpb. plantarum subsp. plantarum sequences were compared using the whole-genome multilocus sequence typing (wgMLST) method.

Deriving A Novel Health Index Using A Large-Scale Population Based Electronic Health Record With Deep Networks

Health indexes are useful tools for monitoring the health condition of a population and can be used to guide healthcare policy of governments. However, most health indexes are constructed by using statistical methods to summarize recent adverse events (e.g., mortality). Information from these tools may reflect merely the impact of prior health policy holistically and can hardly indicate the most recent dynamics and its impact on future health conditions. As the advancements in medications and medical techniques rapidly evolve, there is a need of new health indexes that can reflect the most recent predictive health condition of a population and can easily be summarized with respect of any sub-population of interest. In this work, we develop a novel health index by using deep learning technique on a large-scale and longitudinal population based electronic health record (EHR). Three deep neural network (DNN) models were trained to predict 4-year event rates of mortality, hospitalization and cancer occurrence at an individual-level. Platt calibration approach was used to transform DNN output scores into estimated event risks. A novel health index is then constructed by weighted scoring these calibrated event risks. This individual-level health index not only provide a better predictive power but can also be flexibly summarized for different regions or sub-populations of interest - hence providing objective insights to develop precise personal or national policy beyond conventional health index.

Predicting Gastrointestinal Bleeding Events from Multimodal In-Hospital Electronic Health Records Using Deep Fusion Networks

Applying machine learning (ML) methods on electronic health records (EHRs) that accurately predict the occurrence of a variety of diseases or complications related to medications can contribute to improve healthcare quality. EHRs by nature contain multiple modalities of clinical data from heterogeneous sources that require proper fusion strategy. The deep neural network (DNN) approach, which possesses the ability to learn classification and feature representation, is well-suited to be employed in this context. In this study, we collect a large in-hospital EHR database to develop analytics in predicting 1-year gastrointestinal (GI) bleeding hospitalizations for patients taking anticoagulants or antiplatelet drugs. A total of 815,499 records (16,757 unique patients) are used in this study with three different available EHR modalities (disease diagnoses, medications usage, and laboratory testing measurements). We compare the performances of 4 deep multimodal fusion models and other ML approaches. NNs result in higher prediction performances compare to random forest (RF), gradient boosting decision tree (GBDT), and logistic regression (LR) approaches. We further demonstrate that deep multimodal NNs with early fusion can obtain the best GI bleeding predictive power (area under the receiver operator curve [AUROC] 0.876), which is significantly better than the HAS-BLED score (AUROC 0.668).

Improving Young Stroke Prediction by Learning with Active Data Augmenter in a Large-Scale Electronic Medical Claims Database

Electronic medical claims (EMC) database has been successfully used for predicting occurrences of stroke and a variety of other diseases. However, inadequate predictive performances have been observed in cases of rare occurrences due to both insufficient training samples and highly imbalanced class distribution. In this work, our aim is to improve stroke prediction, especially for young age group (25-45 year-old) in a large population-based EMC database (552,898 subjects). We learn a young stroke predictive deep neural network model using a novel active data augmenter. The augmenter selects the most informative EHR data samples from old age stroke patients. This approach achieves 9.3% and 8.2% area under the receiver operating characteristic curve (AUC) value improvements compared to training directly with only young age group data and training all age groups data, respectively. We further provide analyses on the AUC values obtained as a function of the training data size, and the amount and the type of augmented data samples.

Development of an intelligent decision support system for ischemic stroke risk assessment in a population-based electronic health record database

BACKGROUND

Intelligent decision support systems (IDSS) have been applied to tasks of disease management. Deep neural networks (DNNs) are artificial intelligent techniques to achieve high modeling power. The application of DNNs to large-scale data for estimating stroke risk needs to be assessed and validated. This study aims to apply a DNN for deriving a stroke predictive model using a big electronic health record database.

METHODS AND RESULTS

The Taiwan National Health Insurance Research Database was used to conduct a retrospective population-based study. The database was divided into one development dataset for model training (~70% of total patients for training and ~10% for parameter tuning) and two testing datasets (each ~10%). A total of 11,192,916 claim records from 840,487 patients were used. The primary outcome was defined as any ischemic stroke in inpatient records within 3 years after study enrollment. The DNN was evaluated using the area under the receiver operating characteristic curve (AUC or c-statistic). The development dataset included 672,214 patients (a total of 8,952,000 records) of whom 2,060 patients had stroke events. The mean age of the population was 35.5±20.2 years, with 48.5% men. The model achieved AUC values of 0.920 (95% confidence interval [CI], 0.908-0.932) in testing dataset 1 and 0.925 (95% CI, 0.914-0.937) in testing dataset 2. Under a high sensitivity operating point, the sensitivity and specificity were 92.5% and 79.8% for testing dataset 1; 91.8% and 79.9% for testing dataset 2. Under a high specificity operating point, the sensitivity and specificity were 80.3% and 87.5% for testing dataset 1; 83.7% and 87.5% for testing dataset 2. The DNN model maintained high predictability 5 years after being developed. The model achieved similar performance to other clinical risk assessment scores.

CONCLUSIONS

Using a DNN algorithm on this large electronic health record database is capable of obtaining a high performing model for assessment of ischemic stroke risk. Further research is needed to determine whether such a DNN-based IDSS could lead to an improvement in clinical practice.

Glitazones and alpha-glucosidase inhibitors as the second-line oral anti-diabetic agents added to metformin reduce cardiovascular risk in Type 2 diabetes patients: a nationwide cohort observational study

Objective

Metformin is the standard first-line drug for patients with Type 2 diabetes (T2DM). However, the optimal second-line oral anti-diabetic agent (ADA) remains unclear. We investigated the cardiovascular risk of various ADAs used as add-on medication to metformin in T2DM patients from a nationwide cohort.

Methods

T2DM patients using different add-on oral ADAs after an initial metformin therapy of > 90 days were identified from the Taiwan National Health Insurance Database. Five classes of ADAs, including sulphonylureas (SU), glinides, thiazolidinediones (TZD), alpha-glucosidase inhibitors (AGI), and dipeptidyl peptidase-4 inhibitors (DPP-4I) were selected for analysis. The reference group was the SU added to metformin. Patients were excluded if aged < 20 years, had a history of stroke or acute coronary syndrome (ACS), or were receiving insulin treatment. The primary outcomes included any major adverse cardiovascular event (MACE) including ACS, ischemic/hemorrhagic stroke, and death. A Cox regression model was used to estimate the hazard ratio (HR) for MACE.

Results

A total of 26,742 patients receiving their add-on drug to metformin of either SU (n = 24,277), glinides (n = 962), TZD (n = 581), AGI (n = 808), or DPP-4I (n = 114) were analyzed. After a mean follow-up duration of 6.6 ± 3.4 years, a total of 4775 MACEs occurred. Compared with the SU+metformin group (reference), the TZD+metformin (adjusted HR: 0.66; 95% CI 0.50–0.88, p = 0.004) and AGI+metformin (adjusted HR: 0.74; 95% CI 0.59–0.94, p = 0.01) groups showed a significantly lower risk of MACE.

Conclusion

Both TZD and AGI, when used as an add-on drug to metformin were associated with lower MACE risk when compared with SU added to metformin in this retrospective cohort study.

Trial registration CE13152B-3. Registered 7 Mar, 2013, retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0663-6) contains supplementary material, which is available to authorized users.

A Manikin Study to Compare Video-Optical Intubation Stylet versus Macintosh Laryngoscope Used by Novice in Normal and Simulated Difficult Airway Intubation

Objective

To compare Macintosh laryngoscope with video-optical intubation stylet on rates and time durations of successful tracheal intubation in normal and simulated difficult airway.

Design

Crossover experimental study.

Setting

Intubation training laboratory.

Methods

A group of novices (58 medical students) attempted intubation on manikin under normal and simulated difficult airway (grade 3 larygnoscopic view) settings using both Macintosh laryngoscope and video-optical intubation stylet. The success rate, duration to intubate and occurrence of complications (oesophageal intubation and incisor breakage) when using the two different devices were measured and compared. The time results were analysed by paired t-test and categorical results by chi square test or Fisher's exact test.

Results

The success rate to intubate difficult airway using video-optical intubation stylet (0.92) was significantly higher than using Macintosh laryngoscope (0.59) (p=0.002). The mean time taken to intubate difficult airway using video-optical intubation stylet was significantly shorter than using Macintosh laryngoscope by 10.90 seconds (p=0.004). Oesophageal intubation rate was significantly higher when using Macintosh laryngoscope to intubate difficult airway compared to video-optical intubation stylet (p=0.002). There was no significant difference on the rate of incisor breakage between the two instruments.

Conclusions

Novice can learn to use both Macintosh laryngoscope and video-optical intubation stylet to intubate successfully after a short training. Video-optical intubation stylet is an effective “Plan B” instrument because it shortens the duration and increases the rate of successful intubation in difficult airway situations.

Two Pregnant Women Presenting with Umbilical Cord Prolapse

Cord prolapse is an obstetric emergency as delay in management is associated with significantly increased neonatal morbidity and mortality. If the accident occurred outside the hospital, many babies would be dead or severely asphyxiated upon arrival in the hospital. The role of Accident & Emergency (A&E) department is to arrive at this diagnosis promptly and deliver appropriate intervention. Immediate cesarean delivery is the treatment of choice. The clinical presentations of two cases with umbilical cord prolapse presenting to our A&E department within two weeks were described. The pathophysiology, risk factors, diagnosis, management as well as outcome were discussed.

A Review on the Management of Acute Gastroenteritis in Children

Acute gastroenteritis represents a frequent cause of morbidity among children in Hong Kong. Despite the large number of potential etiologic agents, principles of management of gastroenteritis are uniform and aim to prevent the two major complications - dehydration and malnutrition. A review of the literature was performed. Selected articles were appraised, graded, and synthesised qualitatively. Statements on recommendations were generated. Current evidence emphasises the use of oral rehydration and the early reintroduction of age-appropriate foods. Apart from these two, important aspects of management reviewed included laboratory investigations, role of anti-diarrhoeal agents, and use of antimicrobial agents. Criteria for admission of high-risk children are also addressed.

Outcome of Out-of-Hospital Cardiac Arrest in a Regional Hospital in Hong Kong

This study evaluated the resuscitation outcome of adult patients presenting with non-traumatic out-of-hospital cardiac arrest (OHCA) to a regional hospital in Hong Kong. Out of 876 patients of non-traumatic OHCA, 12.7% survived to hospital admission. Only 0.5% of the 876 patients survived to hospital discharge and at one year after discharge. The number needed to treat (NNT) for prehospital asystolic cardiac arrest to have one survival to discharge was 795.

A mathematical framework for virtual IMRT QA using machine learning

PURPOSE

It is common practice to perform patient-specific pretreatment verifications to the clinical delivery of IMRT. This process can be time-consuming and not altogether instructive due to the myriad sources that may produce a failing result. The purpose of this study was to develop an algorithm capable of predicting IMRT QA passing rates a priori.

METHODS

From all treatment, 498 IMRT plans sites were planned in eclipse version 11 and delivered using a dynamic sliding window technique on Clinac iX or TrueBeam Linacs. 3%/3 mm local dose/distance-to-agreement (DTA) was recorded using a commercial 2D diode array. Each plan was characterized by 78 metrics that describe different aspects of their complexity that could lead to disagreements between the calculated and measured dose. A Poisson regression with Lasso regularization was trained to learn the relation between the plan characteristics and each passing rate.

RESULTS

Passing rates 3%/3 mm local dose/DTA can be predicted with an error smaller than 3% for all plans analyzed. The most important metrics to describe the passing rates were determined to be the MU factor (MU per Gy), small aperture score, irregularity factor, and fraction of the plan delivered at the corners of a 40 × 40 cm field. The higher the value of these metrics, the worse the passing rates.

CONCLUSIONS

The Virtual QA process predicts IMRT passing rates with a high likelihood, allows the detection of failures due to setup errors, and it is sensitive enough to detect small differences between matched Linacs.

Angiotensin-Receptor Blocker, Angiotensin-Converting Enzyme Inhibitor, and Risks of Atrial Fibrillation: A Nationwide Cohort Study

Both angiotensin-receptor blockers (ARB) and angiotensin-converting enzyme inhibitors (ACEI) have protective effects against atrial fibrillation (AF). The differences between ARB and ACEI in their effects on the primary prevention of AF remain unclear. This study compared ARB and ACEI in combined antihypertensive medications for reducing the risk of AF in patients with hypertension, and determined which was better for AF prevention in a nationwide cohort study.Patients aged ≥55 years and with a history of hypertension were identified from Taiwan National Health Insurance Research Database. Medical records of 25,075 patients were obtained, and included 6205 who used ARB, 8034 who used ACEI, and 10,836 nonusers (no ARB or ACEI) in their antihypertensive regimen. Cox regression models were applied to estimate the hazard ratio (HR) for new-onset AF.During an average of 7.7 years' follow-up, 1619 patients developed new-onset AF. Both ARB (adjusted HR: 0.51, 95% CI 0.44-0.58, P < 0.001) and ACEI (adjusted HR: 0.53, 95% CI 0.47-0.59, P < 0.001) reduced the risk of AF compared to nonusers. Subgroup analysis showed that ARB and ACEI were equally effective in preventing new-onset AF regardless of age, gender, the presence of heart failure, diabetes, and vascular disease, except for those with prior stroke or transient ischemic attack (TIA). ARB prevents new-onset AF better than ACEI in patients with a history of stroke or TIA (log-rank P = 0.012).Both ARB and ACEI reduce new-onset AF in patients with hypertension. ARB prevents AF better than ACEI in patients with a history of prior stroke or TIA.

EURO-MUSCULUS/USPRM. Basic scanning protocols for knee

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned knee structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

EURO-MUSCULUS/USPRM. Basic scanning protocols for hip

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned hip structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

EURO-MUSCULUS/USPRM. Basic Scanning Protocols for Ankle and foot

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned ankle/foot structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

EURO-MUSCULUS/USPRM Basic Scanning Protocols for elbow

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned elbow structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

Corrigendum. Early versus delayed passive range of motion exercise for arthroscopic rotator cuff repair: a meta-analysis of randomized controlled trials

Chang KV, Hung CY, Han DS, Chen WS, Wang TG, Chien KL. Early versus delayed passive range of motion exercise for arthroscopic rotator cuff repair: a meta-analysis of randomized controlled trials. Am J Sports Med. 2015;43(5):1265-1273. (Original DOI: 10.1177/0363546514544698 )

EURO-MUSCULUS/USPRM Basic Scanning Protocols for wrist and hand

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned wrist/hand structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

EURO-MUSCULUS/USPRM Basic Scanning Protocols for shoulder

In this protocol, the patient/probe positionings, anatomical drawings and ultrasound images of commonly scanned shoulder structures are described. This practical guide is prepared (with an international consensus of several expert physiatrists) to serve as a uniform/standard approach especially for beginner sonographers.

Mutations in RIT1 cause Noonan syndrome - additional functional evidence and expanding the clinical phenotype

RASopathies are a clinically heterogeneous group of conditions caused by mutations in 1 of 16 proteins in the RAS-mitogen activated protein kinase (RAS-MAPK) pathway. Recently, mutations in RIT1 were identified as a novel cause for Noonan syndrome. Here we provide additional functional evidence for a causal role of RIT1 mutations and expand the associated phenotypic spectrum. We identified two de novo missense variants p.Met90Ile and p.Ala57Gly. Both variants resulted in increased MEK-ERK signaling compared to wild-type, underscoring gain-of-function as the primary functional mechanism. Introduction of p.Met90Ile and p.Ala57Gly into zebrafish embryos reproduced not only aspects of the human phenotype but also revealed abnormalities of eye development, emphasizing the importance of RIT1 for spatial and temporal organization of the growing organism. In addition, we observed severe lymphedema of the lower extremity and genitalia in one patient. We provide additional evidence for a causal relationship between pathogenic mutations in RIT1, increased RAS-MAPK/MEK-ERK signaling and the clinical phenotype. The mutant RIT1 protein may possess reduced GTPase activity or a diminished ability to interact with cellular GTPase activating proteins; however the precise mechanism remains unknown. The phenotypic spectrum is likely to expand and includes lymphedema of the lower extremities in addition to nuchal hygroma.

Moderate Hypothermia (33 °C) Decreases the Susceptibility to Pacing-Induced Ventricular Fibrillation Compared with Severe Hypothermia (30 °C) by Attenuating Spatially Discordant Alternans in Isolated Rabbit Hearts

BACKGROUND

Severe hypothermia (SH, 30 °C) increases the risk of pacing-induced ventricular fibrillation (PIVF) by enhancing spatially discordant alternans (SDA). Whether moderate hypothermia (MH, 33 °C), which is clinically used for therapeutic hypothermia, also facilitates SDA remains unclear. We hypothesized that MH attenuates SDA occurrence compared with that achieved by SH, and decreases the susceptibility of PIVF.

METHODS

Using an optical mapping system, action potential duration (APD)/conduction velocity restitutions and thresholds of APD alternans were determined by S1 pacing in Langendorff-perfused isolated rabbit hearts. In the MH group (n = 7), S1 pacing was performed at baseline (37 °C), after 5-min MH, and after 5-min rewarming (37 °C). In the SH group (n = 9), pacing was also performed at baseline (37 °C), after 5-min SH, and after 5-min rewarming (37 °C). The thresholds of APD alternans were defined as the longest S1 pacing cycle length at which APD alternans were detected.

RESULTS

Although the thresholds of APD alternans were not different between the MH (273 ± 46 ms) and the SH (300 ± 35 ms) (p = 0.281) groups, SDA threshold was shorter (at a faster heart rate) during MH (228 ± 33 ms) than that during SH (289 ± 42 ms) (p = 0.028). At APD alternans threshold, SH hearts showed more SDA than that during MH (SH: 7 hearts, MH: 2 hearts, p = 0.049). SDA could be induced in all 9 SH hearts (100%), while only 4 MH hearts (57%) had SDA (p = 0.029). The PIVF inducibility during SH (44 ± 53%) was higher than that during MH (0%) (p = 0.043).

CONCLUSIONS

Compared with SH, the MH group showed greater attenuation of SDA and decreased the susceptibility of PIVF. Therefore, MH is safer as a procedural guideline for use in clinical therapeutic hypothermia than SH.

KEY WORDS

Cardiac alternans; Conduction velocity; Hypothermia; Optical mapping.

Resistant hypertension, patient characteristics, and risk of stroke

Background

Little is known about the prognosis of resistant hypertension (RH) in Asian population. This study aimed to evaluate the impacts of RH in Taiwanese patients with hypertension, and to ascertain whether patient characteristics influence the association of RH with adverse outcomes.

Methods and Results

Patients aged ≥45 years with hypertension were identified from the National Health Insurance Research Database. Medical records of 111,986 patients were reviewed in this study, and 16,402 (14.6%) patients were recognized as having RH (continuously concomitant use of ≥3 anti-hypertensive medications, including a diuretic, for ≥2 years). Risk of major adverse cardiovascular events (MACE, a composite of all-cause mortality, acute coronary syndrome, and stroke [included both fatal and nonfatal events]) in patients with RH and non-RH was analyzed. A total of 11,856 patients experienced MACE in the follow-up period (average 7.1±3.0 years). There was a higher proportion of females in the RH group, they were older than the non-RH (63.1 vs. 60.5 years) patients, and had a higher prevalence of cardiovascular co-morbidities. Overall, patients with RH had higher risks of MACE (adjusted HR 1.17; 95%CI 1.09–1.26; p<0.001). Significantly elevated risks of stroke (10,211 events; adjusted HR 1.17; 95%CI 1.08–1.27; p<0.001), especially ischemic stroke (6,235 events; adjusted HR 1.34; 95%CI 1.20–1.48; p<0.001), but not all-cause mortality (4,594 events; adjusted HR 1.06; 95%CI 0.95–1.19; p = 0.312) or acute coronary syndrome (2,145 events; adjusted HR 1.17; 95%CI 0.99–1.39; p = 0.070) were noted in patients with RH compared to those with non-RH. Subgroup analysis showed that RH increased the risks of stroke in female and elderly patients. However, no significant influence was noted in young or male patients.

Conclusions

Patients with RH were associated with higher risks of MACE and stroke, especially ischemic stroke. The risks were greater in female and elderly patients than in male or young patients.

Statin Therapy for Primary Prevention of Atrial Fibrillation: Guided by CHADS2/CHA2DS2VASc Score

Atrial fibrillation (AF) is the most common arrhythmia and is associated with increased cardiovascular morbidity and mortality. The anti-arrhythmic effect of statins on AF prevention appears to be highly significant in most clinical studies. However, some discrepancies do exist among different clinical studies. Different clinical settings and types of stains used may explain these differences between trials. The CHADS₂ and CHA₂DS₂VASc scoring systems have been used for stroke risk stratification in AF patients. The recent study suggested that these scores can also be used to guide statin therapy for AF prevention. Patients with higher scores had a higher risk of developing AF and gained more benefits from statins therapy than those with lower scores. This review article focused on the ability of these scores to predict AF prevention by statins.

Falls and Atrial Fibrillation in Elderly Patients

BACKGROUND

Atrial fibrillation is a common heart rhythm disorder in older adults, and its prevalence has increased rapidly in recent years. The health issues associated with atrial fibrillation are not limited to physiological problems, as it also contributes to an increased risk of falls, which may be related to cardiovascular co-morbidities and medication use. The aim of this study was to determine which cardiovascular co-morbidities and medication use are associated with falls in older adults with atrial fibrillation.

METHODS

Four hundred and one patients 75 years of age or older (82.2 ± 0.2 years) were enrolled in a geriatric evaluation and management unit in Taiwan. Events associated with patient falls and medication use were recorded, and comprehensive geriatric assessment was conducted during admission.

RESULTS

Among the study participants, 66 (16.5%) patients had atrial fibrillation and 234 (58.4%) patients had a history of fall. We found a significantly higher prevalence of falls in patients with atrial fibrillation [odds ration (OR) 1.98, 95% confidence interval (CI) 1.08-3.63, p = 0.026] compared with those without atrial fibrillation. Using multivariate logistic regression, we found that benzodiazepine use (OR 18.22, 95% CI 2.71-122.38, p = 0.003), a history of paroxysmal atrial fibrillation (OR 12.18, 95% CI 1.37-108.70, p = 0.025) and hypertension (OR 9.49, 95% CI 1.19-75.57, p = 0.034) were independent factors for falls in atrial fibrillation patients.

CONCLUSIONS

A diagnosis of atrial fibrillation in elderly patients is associated with falls. Benzodiazepine use, history of paroxysmal atrial fibrillation, and hypertension were associated with a high falling prevalence among patients with atrial fibrillation.

KEY WORDS

Atrial fibrillation; Benzodiazepine; Falls; Hypertension.

CHADS(2) score, statin therapy, and risks of atrial fibrillation

OBJECTIVE

Little is known about the effectiveness of statins on primary prevention of atrial fibrillation in elderly patients. This study aimed to evaluate the efficacy of statin treatment for atrial fibrillation prevention in elderly patients with hypertension, and to determine if comorbidity or CHADS(2) (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, prior Stroke or transient ischemic attack) score can predict the effectiveness of statin treatment.

METHODS

Patients aged ≥65 years with hypertension were identified from a National Health Insurance research database (a systemic sampling from 2000 to 2009 with a total of 1,000,000 subjects). Medical records of 27,002 patients were used in this study, in which 2400 (8.9%) were receiving statin therapy. Risk of new-onset atrial fibrillation in statin users and nonusers was analyzed.

RESULTS

During the 9-year follow-up period, 2241 patients experienced new-onset atrial fibrillation. Statin users were younger than nonusers (72.4 vs 73.4 years) but had a higher prevalence of ischemic heart disease, diabetes mellitus, stroke, and chronic renal disease. Overall, statin therapy reduced the risk of atrial fibrillation by 19% (adjusted hazard ratio 0.81; 95% confidence interval, 0.69-0.95; P=.009). Subgroup analysis showed that statin use was beneficial in patients with or without a particular comorbidity. The effectiveness of statins was significant in patients with CHADS(2) score ≥2 (adjusted hazard ratio 0.69; 95% confidence interval, 0.57-0.85; P <.001). However, statin therapy was not as beneficial in hypertensive patients without other cardiovascular comorbidities (CHADS(2) score =1).

CONCLUSION

Statin therapy in elderly patients with hypertension reduces the risk of new-onset atrial fibrillation. Statins are more beneficial in patients with CHADS(2) score ≥2 than in those with score of 1.

Acute massive pulmonary embolism after radiofrequency catheter ablation: a rare complication after a common procedure

A 41-year-old man received an electrophysiological study (EPS) and radiofrequency catheter ablation (RFCA) for atrioventricular reentrant tachycardia (AVRT) in our hospital. Massive pulmonary embolism (PE) with hypotension developed 9 hours after these procedures. After emergent pulmonary angiography and catheter-directed intrathrombus urokinase infusion and clot breaking, the patient recovered well. This case suggests that life-threatening PE may occur in patients who receive EPS, RFCA, or both. An adequate observation time after RFCA and clinical alertness are necessary for immediate diagnosis and treatment. Emergent catheter-directed therapy may be of benefit in some patients with acute massive PE.

An in vivo study of common carp (Cyprinus carpio L.) liver during prolonged hypoxia

Hypoxia induced apoptosis has been studied extensively in many mammalian cell lines but there are only a few studies using whole animal models. We investigated the response of the intact liver to hypoxia in a hypoxia tolerant fish, the carp (Cyprinus carpio, L). We exposed carp to hypoxia for up to 42 days, using oxygen level (0.5 mgO(2)/L) that were slightly higher than the critical oxygen level of carp. There was extensive DNA damage in liver cells, especially during the first week of exposure, indicated by a massive TUNEL signal. However there was no change in cell proliferation, cell number or size, no increase in caspase-3 activity, no increase in single stranded DNA and this, combined with a number of other observations, led us to conclude there was no increase in apoptosis in the liver during hypoxia. There was up-regulation of some anti-apoptotic genes and proteins (Bcl-2, HSP70, p27) and down-regulation of some pro-apoptotic genes (Tetraspanin 5 and Cell death activator). The cells appeared to enter cell cycle arrest, presumably to allow repair of damaged DNA. As there was no change in cell proliferation and cell number, the damaged cells were not entering apoptosis and must have recovered during prolonged hypoxia.

A vaccine against coccidioidomycosis is justified and attainable

Coccidioides is a fungal pathogen of humans which can cause a life-threatening respiratory disease in immunocompetent individuals. Recurrent epidemics of coccidioidal infections in Southwestern United States has raised the specter of awareness of this soil-borne microbe, particularly among residents of Arizona and Southern California, and has galvanized research efforts to develop a human vaccine against coccidioidomycosis. In this review, we discuss the rationale for such a vaccine, examine the features of host innate and acquired immune response to Coccidioides infection, describe strategies used to identify and evaluate vaccine candidates, and provide an update on progress toward development of a vaccine against this endemic pathogen.

Profiling gene expression in Coccidioides posadasii

Coccidioides posadasii is a dimorphic fungal pathogen which grows as a filamentous saprobe in the soil and multicellular parasitic form in host lung tissue. Studies of gene expression profiles during saprobic and parasitic phase development can provide clues about morphogenetic regulation and may lead to the discovery of molecular targets for novel antifungal drugs. Suppression-subtractive hybridization (SSH) and quantitative real-time polymerase chain reaction (QRT-PCR) were used to identify and quantify differential gene expression during in vitro growth of Coccidioides. DNA fragments obtained from the subtraction of cDNA pools derived from the saprobic and parasitic phase RNA preparations were each cloned into an appropriate vector and subjected to sequence analysis. Semi-quantitative, reverse transcription polymerase chain reaction (RT-PCR) experiments were first conducted to assess whether these inserts represented differentially expressed genes. Nucleotide sequences of the partial and full-length genes selected by RT-PCR were obtained by genome walking and rapid amplification of cDNA ends (RACE) methods. QRT-PCR analysis of the expression of these genes during saprobic and parasitic cell growth was then conducted using DNA standard curves normalized to a constitutively expressed control gene. Four C. posadasii genes whose expression is essentially restricted to the parasitic cycle were discovered using this approach. These genes include homologues of OPS1 (encodes opsin-related protein), MDR1 (multidrug resistance protein), ALDR1 (aldehyde reductase), and PSP1 (hypothetical lipid transporter/flippase protein). The combined applications of SSH and QRT-PCR permit global analysis of gene expression patterns in C. posadasii.

The parasitic cell wall of Coccidioides immitis

Coccidioides immitis is a human respiratory pathogen characterized by a parasitic cycle that is unique among fungi that cause systemic mycoses. Biochemical, molecular and immunological studies of the cell wall of C. immitis have focused on three distinct events of parasitic cell differentiation: isotropic growth, segmentation and endosporulation. Current investigations of each developmental phase in vitro include the identification, expression analysis, and disruption of synthase and hydrolase genes that are suspected to have key roles in morphogenesis. Temporal expression of families of beta-glucosidase and chitinase genes are of particular interest because their products may participate in wall modification during both isotropic growth and endosporulation and, thereby, represent potential molecular targets for novel antifungal drugs. Furthermore, our immunological studies of these and other isolated parasitic cell-wall components have resulted in the identification of antigens with demonstrated impact on host response to coccidioidal infection. C. immitis has proved to be an excellent model for fungal cell-wall research.

Recombinant urease and urease DNA of Coccidioides immitis elicit an immunoprotective response against coccidioidomycosis in mice

Coccidioides immitis antigens which stimulate a T helper cell 1 (Th1) pathway of host immune response are considered to be essential components of a vaccine against coccidioidomycosis. Recombinant urease (rURE) and recombinant heat shock protein 60 (rHSP60) of C. immitis were expressed in Escherichia coli and tested as vaccine candidates in BALB/c mice. A synthetic oligodeoxynucleotide which contained unmethylated CpG dinucleotides and was previously shown to enhance a murine Th1 response was used as an immunoadjuvant. T cells isolated from the spleens and lymph nodes of the rURE- and rHSP60-immune mice showed in vitro proliferative responses to the respective recombinant protein, but only those T lymphocytes from rURE-immunized mice revealed markedly elevated levels of expression of selected Th1-type cytokine genes. BALB/c mice immunized subcutaneously with rURE and subsequently challenged by the intraperitoneal (i.p.) route with a lethal inoculum of C. immitis arthroconidia demonstrated a significant reduction in the level of C. immitis infection compared to control animals. rHSP60 was much less effective as a protective antigen. Evaluation of cytokine gene expression in lung tissue and levels of recombinant urease-specific immunoglobulins (immunoglobulin G1 [IgG1] versus IgG2a) in murine sera at 12 days after challenge provided additional evidence that immunization with rURE stimulated a Th1 response to the pathogen. Urease was further evaluated by expression of the URE gene in a mammalian plasmid vector (pSecTag2A.URE) which was used to immunize mice by the intradermal route. In this case, 82% of the vector construct-immunized animals survived more than 40 days after i.p. infection, compared to only 10% of the mice immunized with the vector alone. In addition, 87% of the pSecTag2A.URE-immunized survivors had sterile lungs and spleens. These data support the need for further evaluation of the C. immitis urease as a candidate vaccine against coccidioidomycosis.

Cloning and expression of the gene which encodes a tube precipitin antigen and wall-associated beta-glucosidase of Coccidioides immitis

We report the structure and expression of the Coccidioides immitis BGL2 gene which encodes a previously characterized 120-kDa glycoprotein of this fungal respiratory pathogen. The glycoprotein is recognized by immunoglobulin M tube precipitin (TP) antibody present in sera of patients with coccidioidomycosis, a reaction which has been used for serodiagnosis of early coccidioidal infection. The deduced amino acid sequence of BGL2 shows 12 potential N glycosylation sites and numerous serine-threonine-rich regions which could function as sites for O glycosylation. In addition, the protein sequence includes a domain which is characteristic of family 3 glycosyl hydrolases. Earlier biochemical studies of the purified 120-kDa TP antigen revealed that it functions as a beta-glucosidase (EC 3.2.1.21). Its amino acid sequence shows high homology to several other reported fungal beta-glucosidases which are members of the family 3 glycosyl hydrolases. Results of previous studies have also suggested that the 120-kDa beta-glucosidase participates in wall modification during differentiation of the parasitic cells (spherules) of C. immitis. In this study we showed that expression of the BGL2 gene is elevated during isotropic growth of spherules and the peak of wall-associated BGL2 enzyme activity correlates with this same phase of parasitic cell differentiation. These data support our hypothesis that the 120-kDa beta-glucosidase plays a morphogenetic role in the parasitic cycle of C. immitis.

Disruption of the gene which encodes a serodiagnostic antigen and chitinase of the human fungal pathogen Coccidioides immitis

Disruption of genes in medically important fungi has proved to be a powerful tool for evaluation of putative virulence factors and identification of potential protein targets for novel antifungal drugs. Chitinase has been suggested to play a pivotal role in autolysis of the parasitic cell wall of Coccidioides immitis during the asexual reproductive cycle (endosporulation) of this systemic pathogen. Two chitinase genes (CTS1 and CTS2) of C. immitis have been cloned. Preliminary evidence has suggested that expression of CTS1 is markedly increased during endospore formation. The secreted CTS1 chitinase has also been shown to react with patient anti-Coccidioides complement-fixing (CF) antibody and is a valuable aid in the serodiagnosis of coccidioidomycosis. To examine the role of CTS1 in the morphogenesis of parasitic cells, the CTS1 gene was disrupted by a single, locus-specific crossover event. This resulted in homologous integration of a pAN7.1 plasmid construct that contained a 1.1-kb fragment of the chitinase gene into the chromosomal DNA of C. immitis. Results of Southern hybridizations, immunoblot analyses of culture filtrates using both CTS1-specific murine antiserum and serum from a patient with confirmed coccidioidal infection, an immunodiffusion test for CF antigenicity, and substrate gel electrophoresis assays of chitinase activity confirmed that the CTS1 gene was disrupted and nonfunctional. This is the first report of a successful targeted gene disruption in C. immitis. However, loss of CTS1 function had no effect on virulence or endosporulation. Comparative assays of chitinase activity in the parental and Deltacts1 strains suggested that the absence of a functional CTS1 gene can be compensated for by elevated expression of the CTS2 gene. Current investigations are focused on disruption of CTS2 in the Deltacts1 host to further evaluate the significance of chitinase activity in the parasitic cycle of C. immitis.

A major cell surface antigen of Coccidioides immitis which elicits both humoral and cellular immune responses

Multinucleate parasitic cells (spherules) of Coccidioides immitis isolates produce a membranous outer wall component (SOW) in vitro which has been reported to be reactive with antibody from patients with coccidioidal infection, elicits a potent proliferative response of murine immune T cells, and has immunoprotective capacity in a murine model of coccidioidomycosis. To identify the antigenic components of SOW, the crude wall material was first subjected to Triton X-114 extraction, and a water-soluble fraction derived from this treatment was examined for protein composition and reactivity in humoral and cellular immunoassays. Protein electrophoresis revealed that the aqueous fraction of three different isolates of C. immitis each contained one or two major glycoproteins (SOWgps), distinguished by their molecular sizes, which ranged from 58 to 82 kDa. The SOWgps, however, showed identical N-terminal amino acid sequences, and each was recognized by sera from patients with C. immitis infection. Antibody raised against the purified 58-kDa glycoprotein (SOWgp58) of the Silveira isolate was used for Western blot and immunolocalization analyses. Expression of SOWgp was shown to be parasitic phase specific, and the antigen was localized to the membranous SOW. The water-soluble fraction of SOW and the purified SOWgp58 were tested for the ability to stimulate proliferation of human peripheral monocytic cells (PBMC). The latter were obtained from healthy volunteers with positive skin test reaction to spherulin, a parasitic-phase antigen of C. immitis, and from volunteers who showed no skin test reaction to the same antigen. The SOW preparations stimulated proliferation of PBMC from skin test-positive but not skin test-negative donors, and the activated cells secreted gamma interferon, which is indicative of a T helper 1 pathway of immune response. Results of this study suggest that SOWgp is a major parasitic cell surface-expressed antigen that elicits both humoral and cellular immune responses in patients with coccidioidal infection.

Sequence, expression and functional analysis of the Coccidioides immitis ODC (ornithine decarboxylase) gene

The ornithine decarboxylase (ODC) gene of the human respiratory fungal pathogen, Coccidioides immitis (Ci) was cloned, sequenced, chromosome-mapped, and expressed in Escherichia coli (Ec). The genomic, cDNA and translated sequences are presented. Transformation of an ODC null mutant strain of Ec (EWH 319) with the Ci ODC gene was conducted to confirm function of the protein encoded by the fungal gene. Activity of the enzyme by the bacterial transformant was inhibited by 1, 4-diamino-2-butanone (DAB), a known inhibitor of eukaryotic ODC. Temporal expression of the Ci ODC gene during the parasitic cell cycle is constitutive, based on results of RT PCR. However, results of enzyme activity assays of cell homogenates obtained at different stages of parasitic cell development in vitro showed that the functional protein is present only during periods of isotropic growth and segmentation, and these morphogenetic events can be arrested by the addition of DAB. The observed absence of a difference in steady-state mRNA transcript amounts, and the developmentally correlated variation in levels of enzyme activity, suggest a translational or post-translational mechanism of ODC regulation. Since no PEST sequence was detected in the Ci ODC, enzyme regulation by programmed protein degradation as reported for many other eukaryotic ODCs may not occur in this case. ODC activity appears to play a key role in the morphogenesis of Ci, and the enzyme could be a rational target for therapy of disseminated coccidioidomycosis.

Calcium and low-dose aspirin prophylaxis in women at high risk of pregnancy-induced hypertension

OBJECTIVE

The objectives of the study were to confirm the validity of using oscillometric measurement of MAP in the left lateral position to identify those at high risk for developing pregnancy-induced hypertension (PIH), and to assess and compare the efficacy of prophylaxis with low-dose aspirin or calcium supplementation in high-risk patients.

STUDY DESIGN

A prospective study in pregnancy; 500 normotensive, primigravid Chinese women were recruited in the second trimester of pregnancy on the basis of 80 mm Hg > or = MAP < 106 mm Hg in the antenatal clinic. They were then screened by Dinamap in a research setting, measuring MAP in the left lateral position after rest and using a cutoff value of 60 mm Hg for inclusion in the randomized study. Randomization was divided into three groups: control, low-dose aspirin, and calcium supplementation. After delivery, patients were classified as either having remained normotensive or having developed PIH, with or without proteinuria.

RESULTS

The incidence of both proteinuric and nonproteinuric PIH was significantly lower in patients screened out as low risk than in those selected as high risk using a critical value of 60 mm Hg for left lateral MAP (p < 0.05). The incidence of proteinuric PIH was significantly lower in patients given low-dose aspirin than in the control group (p < 0.05). However, the confidence intervals for the effect were wide, comparable with aspirin having no effect or leading to a 16-fold reduction in the risk of preeclampsia. For those given calcium supplementation, the reduction was not significant. There was no significant difference in the incidence of nonproteinuric PIH between the control group and the two groups receiving prophylaxis.

CONCLUSION

Oscillometric measurement of second-trimester left lateral MAP is a valid predictor of proteinuric PIH. Low-dose aspirin may offer a degree of protection from proteinuric PIH in these high-risk women. Calcium supplementation was not shown to significantly reduce the incidence of PIH.

Sensitivity of concentration and risk predictions in the PRESTO and MMSOILS multimedia models: regression technique assessment

This paper describes the application of two multimedia models, PRESTO and MMSOILS, to predict contaminant migration from a landfill that contains an organic chemical (methylene chloride) and a radionuclide (uranium-238). Exposure point concentrations and human health risks are predicted, and distributions of those predictions are generated using Monte Carlo techniques. Analysis of exposure point concentrations shows that predictions of uranium-238 in groundwater differ by more than one order of magnitude between models. These differences occur mainly because PRESTO simulates uranium-238 transport through the groundwater using a one-dimensional algorithm and vertically mixes the plume over an effective mixing depth, whereas MMSOILS uses a three-dimensional algorithm and simulates a plume that resides near the surface of the aquifer. A sensitivity analysis, using stepwise multiple linear regression, is performed to evaluate which of the random variables are most important in producing the predicted distributions of exposure point concentrations and health risks. The sensitivity analysis shows that the predicted distributions can be accurately reproduced using a small subset of the random variables. Simple regression techniques are applied, for comparison, to the same scenarios, and results are similar. The practical implication of this analysis is the ability to distinguish between important versus unimportant random variables in terms of their sensitivity to selected endpoints.

A common position-dependent mechanism controls cell-type patterning and GLABRA2 regulation in the root and hypocotyl epidermis of Arabidopsis

A position-dependent pattern of epidermal cell types is produced during root development in Arabidopsis thaliana. This pattern is reflected in the expression pattern of GLABRA2 (GL2), a homeobox gene that regulates cell differentiation in the root epidermis. GL2 promoter::GUS fusions were used to show that the TTG gene, a regulator of root epidermis development, is necessary for maximal GL2 activity but is not required for the pattern of GL2 expression. Furthermore, GL2-promoter activity is influenced by expression of the myc-like maize R gene (35S::R) in Arabidopsis but is not affected by gl2 mutations. A position-dependent pattern of cell differentiation and GL2-promoter activity was also discovered in the hypocotyl epidermis that was analogous to the pattern in the root. Non-GL2-expressing cell files in the hypocotyl epidermis located outside anticlinal cortical cell walls exhibit reduced cell length and form stomata. Like the root, the hypocotyl GL2 activity was shown to be influenced by ttg and 35S::R but not by gl2. The parallel pattern of cell differentiation in the root and hypocotyl indicates that TTG and GL2 participate in a common position-dependent mechanism to control cell-type patterning throughout the apical-basal axis of the Arabidopsis seedling.

Control of cell division in the root epidermis of Arabidopsis thaliana

The formation of the root epidermis in Arabidopsis thaliana provides a simple model to study mechanisms underlying patterning in plants. In this paper we have analyzed the relationships between cell fate specification and the pattern of cell division that occur in the root epidermis. Using clonal analysis, the two cell types of the developing root epidermis, trichoblasts and atrichoblasts, were distinguished by different rates of cell division, highest in trichoblasts. This character appears to be dependent on TTG which controls epidermal cell fate specification. The ability of epidermal cells to undergo longitudinal divisions which are involved in the control of the radial symmetry was shown to be controlled in a cell-specific manner by TTG. The control of the rate and the orientation of cell division in the root meristem epidermal layer thus appear to be under the control of cell fate specification mechanisms.

Temperature-induced alteration of inositolphosphorylceramides in the putative glycosylated lipid precursors of Tetrahymena mimbres glycosylphosphatidylinositol-anchored proteins

Tetrahymena species contain relatively prominent glycosylphosphatidylinositol (GPI)-anchored proteins as well as their putative precursor phosphatidylinositol (PI) glycans. We have characterized the lipid components of the two principal T. mimbres PI glycans. Following their purification by preparative TLC, the PI glycans were hydrolysed in methanolic HCl or NaOH, and resulting lipids were analysed by chromatography and mass spectrometry. The two PI glycans contained nearly identical lipid moieties having long-chain bases with N-linked fatty acids. The predominant long-chain base, 3-O-methylsphinganine, was first assumed to be O-methylated as an artifact of hydrolysis, but subsequently, on the basis of control experiments, it was shown to be naturally occurring. PI glycans from cells grown at 28 degrees C contained primarily palmitic acid (79%) and some stearic acid (11%), whereas the principal PI glycan from 38 degrees C-grown T. mimbres contained 65% stearic acid. In 15 degrees C-grown cells stearic acid accounted for only 2% of ceramide-bound fatty acids and was almost totally replaced by palmitic acid (95%). The distributions of fatty acids bound to T. mimbres GPI-anchored proteins [Ko, Hung and Thompson (1995) Biochem. J. 307, 115-121] were similar but not identical to those of the PI glycans described here. Temperature-induced specification of the lipid components of mature T. mimbres GPI-anchored proteins appears to be established both at the level of PI-glycan synthesis and the level of PI-glycan utilization for protein attachment.

Temperature regulation of the Tetrahymena mimbres glycosylphosphatidylinositol-anchored protein lipid composition

By incubating Tetrahymena mimbres cells with [3H]myristic acid, [3H]ethanolamine, [3H]inositol, and [3H]mannose, proteins having apparent molecular masses of 23 and 63 kDa were identified as the cells' principal glycosylphosphatidylinositol (GPI)-anchored proteins. These proteins accounted for as much as 2-5% of the whole cell proteins, with the higher levels being recovered from non-growing cells. The two proteins, gpi 23 and gpi 63, were purified to near homogeneity through Triton X-114/water partitioning followed by preparative SDS/PAGE. The lipid components of the GPI anchors were determined by chemical and enzymic hydrolysis. Both proteins were anchored by ceramides, with the principal long-chain base being C18 sphinganine containing an O-methyl group at the 3 position. O-Methylation was shown not to be an artifact of hydrolysis. When T. mimbres was cultured at 15 degrees C, the ceramide fatty acid component of the GPI anchors was principally palmitic acid (75% in gpi 23 and 76% in gpi 63). GPI anchors from 28 degrees C-grown cells contained mainly stearic acid (79% in gpi 23 and 70% in gpi 63). Temperature change had little effect on the long-chain-base composition. The direction of temperature-induced lipid change in the protein-bound anchors was the same as found in the inositolphosphorylceramide putative precursors of the protein anchors described in the accompanying paper [Hung, Ko and Thompson (1995) Biochem. J. 307, 107-113], but the detailed fatty acid compositions of the precursors and the protein-bound lipids were quite different. The precise metabolic regulation of anchor lipid chain length supports the concept that composition of the lipid anchor is important in the function and/or metabolism of the anchored protein.

Chloroplast segregation in somatic hybrids of Nicotiana plumbaginifolia and N. sylvestris having different ratios of parental nuclear genomes

Fusion of mesophyll protoplasts of haploid Nicotiana plumbaginifolia (P) and N. sylvestris (S) resulted in the production of somatic hybrid plants of various ploidy levels. Analysis of the restriction fragment patterns of chloroplast DNA from 118 plants belonging to genome constitutions PS, PPS, PSS, and PPSS revealed that two had a pattern corresponding to a mixture of parental DNA while all the others had the pattern of either N. plumbaginifolia or N. sylvestris. In the latter case, the ratio of the two parental types fits 1∶1 in all the four genome constitutions studied. Since the protoplasts used in the fusion experiment were physiologically similar and the hybrid cells were not deliberately selected, these results suggest that chloroplast segregation in the somatic hybrids is independent of the chloroplast input of the fusion partners and the nuclear background of the fusion products.

Coronary vascular injury after transient coronary artery occlusion

BACKGROUND

Microvascular function was examined in dog hearts subjected to transient coronary artery occlusion.

EXPERIMENTAL DESIGN

Temporary coronary artery occlusion (15 or 30 minutes) followed by prolonged reperfusion (24 to 72 hours) was performed in dogs. Myocardial blood flow (radioactive microspheres), vascular permeability (human serum albumin uptake), and apparent vascular volume (radioactively labeled erythrocytes) were used as measures of vascular function. Myeloperoxidase was used as a measure of leukocyte uptake. Free radical formation was measured by electron spin resonance using a spin trapping agent (phenyl N-tert-butylnitrone).

RESULTS

A 30-minute occlusion followed by reperfusion produced prolonged hyperemia, increased vascular permeability, increased apparent vascular volume, and increased leukocyte uptake. Extravasation of red blood cells and carbon black was present within the coronary artery distribution. The altered vascular function was temporally correlated with prolonged leukocyte uptake and free radical production, returning to control values only at 72 hours. A 15-minute occlusion increased vascular permeability at 24 hours, without altering myocardial blood flow or apparent vascular volume. Transmural myocardial leukocyte accumulation after a 15-minute occlusion was minimal in the absence of myocardial infarction or other histologic alterations. Active free radical formation was minimal at 24 hours, with a return of vascular permeability to control values at 48 hours.

CONCLUSIONS

The data demonstrate prolonged dysfunction of the coronary microvasculature after a transient 30-minute occlusion of the left anterior descending coronary artery. The prolonged injury is associated temporally with leukocyte uptake and free radical formation in the presence of minimal infarction. A transient 15-minute occlusion produces a different pattern of vascular dysfunction with an abbreviated duration (24 hours), not associated with myocardial necrosis, extensive leukocyte uptake, nor prolonged free radical formation.

Mendelian inheritance of streptomycin resistance in Nicotiana plumbaginifolia

In a previous study two haploid streptomycin-resistant clones of Nicotiana plumbaginifolia were isolated. The chromosome number of one of these clones has now been doubled through leaf-midvein culture and the resultant diploids were characterized genetically. Our results show that streptomycin resistance in this clone is conditioned by a recessive nuclear gene. Haploid protoplasts of this streptomycin-resistant mutant were selected for chlorate resistance. All clones obtained from the selection were deficient in nitrate reductase activity in addition to resistance to streptomycin. Genetic analysis of progeny of one of these clones revealed that the genes for streptomycin resistance and for the apoenzyme of nitrate reductase are unlinked.